CN118647636A - Preparation method of chlorinated polyvinyl chloride resin composition - Google Patents

Abstract

The invention provides a preparation method of a chlorinated polyvinyl chloride resin composition, wherein a specific heat stabilizer is added for wet mixing after a neutralization process for preparing the chlorinated polyvinyl chloride resin, so that the dispersion efficiency of the heat stabilizer is improved, and the uniform mixing of the heat stabilizer and the chlorinated polyvinyl chloride resin enables the chlorinated polyvinyl chloride resin composition to have excellent processing color and thermal stability.

Description

Preparation method of chlorinated polyvinyl chloride resin composition

Technical Field

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is based on and claims the benefit of priority of Korean Patent Application Nos. 10-2022-0040467 and 10-2023-0040572, filed on March 31, 2022 and March 28, 2023, respectively, the disclosures of which are incorporated herein by reference in their entirety.

The present invention relates to a method for preparing a chlorinated polyvinyl chloride resin composition having excellent processing color and thermal stability.

Background Art

Compared with existing polyvinyl chloride resin (PVC), chlorinated polyvinyl chloride resin (CPVC) has excellent heat resistance due to its high chlorine content as well as excellent mechanical properties and chemical resistance. It can be used in a variety of applications such as hot and cold water pipes, industrial pipes, sprinkler pipes, adhesives, etc.

This CPVC is produced by chlorination of PVC, during which additional HCl is generated. The high chlorine content in CPVC hardens the polymer, increases the processing temperature, and makes it easy for HCl to be released from the polymer chain. In addition, when the generated HCl and the released HCl remain in the polymer, they act as catalysts for existing polymer chains and produce unzipping reactions, resulting in additional HCl release. As a result, the static thermal stability and processing color (or whiteness index) of CPVC deteriorate.

In order to prevent and reduce this phenomenon, many studies have been conducted on the neutralization and washing process for removing HCl after the chlorination reaction of PVC. Specifically, a method for removing HCl using a neutralizing agent, such as NaHCO ₃ (sodium bicarbonate, hereinafter referred to as SB), Na ₂ CO ₃ (sodium carbonate, hereinafter referred to as SC), HOC(COONa)(CH ₂ COOH) ₂ (sodium citrate), etc. has been proposed. However, when the neutralizing agent is insufficient, HCl cannot be completely removed and remains, and when the neutralizing agent is used excessively, the problem of residual neutralizing agent will occur, making the surface of the processed product rough during the processing and reducing the long-term processing performance. In addition, there are limitations to improving the thermal stability of CPVC by using a neutralizing agent.

In addition, as a method of improving the thermal stability of CPVC, a method of introducing a heat stabilizer during processing and blending has been proposed, which is the most effective method to improve thermal stability. However, since each processing company processes according to its own formula, it is not easy to change the processing and blending. In addition, since processing and blending are usually performed by dry blending, it is difficult to disperse uniformly. In addition, when an excessive amount of heat stabilizer is added, there is a problem that the processing color of CPVC deteriorates.

Therefore, further research is needed to find a method that can improve the processing color and thermal stability of CPVC.

Summary of the invention

Technical issues

The present invention provides a method for preparing a chlorinated polyvinyl chloride resin composition having excellent processing color (or whiteness index) and thermal stability.

The invention also provides a chlorinated polyvinyl chloride resin composition prepared by the preparation method, and a chlorinated polyvinyl chloride resin compound containing the composition.

Technical Solution

According to the present invention, there is provided a method for preparing a chlorinated polyvinyl chloride resin composition, the method comprising the steps of: preparing a slurry containing a chlorinated polyvinyl chloride resin by introducing chlorine gas into a suspension in which a vinyl chloride-based polymer is dispersed in an aqueous solvent and performing a chlorination reaction; preparing a slurry containing a neutralized chlorinated polyvinyl chloride resin by introducing a neutralizer into the slurry containing the chlorinated polyvinyl chloride resin and performing a neutralization reaction; and introducing a heat stabilizer into the slurry containing the neutralized chlorinated polyvinyl chloride resin and mixing, wherein the heat stabilizer comprises an alkyl tin carboxylate, an alkyl tin mercaptan, or a mixture thereof.

According to the present invention, a chlorinated polyvinyl chloride resin composition prepared by the above preparation method is also provided.

According to the present invention, a chlorinated polyvinyl chloride resin compound is also provided, which comprises the chlorinated polyvinyl chloride resin composition; and one or more additives selected from impact modifiers, heat stabilizers, fillers, processing aids, pigments and lubricants.

Beneficial Effects

Due to the uniform dispersion of the heat stabilizer, the chlorinated polyvinyl chloride resin composition prepared by the preparation method of the present invention can show excellent processing color and thermal stability.

DETAILED DESCRIPTION

As used herein, the terms “first”, “second”, etc. are used to describe various components, and these terms are only used to distinguish a certain component from other components.

In addition, the terms used in this specification are only used to explain the exemplary embodiments and are not intended to limit the present invention. Unless otherwise stated in the context, a singular expression may include a plural expression. It must be understood that the terms "including", "equipped with" or "having" in this specification are only used to specify the existence of features, numbers, steps, components or combinations thereof that have been put into effect, and do not exclude the existence or possibility of adding one or more different features, numbers, steps, components in advance.

As used herein, the term "vinyl chloride-based polymer" refers to a vinyl chloride-based monomer alone, or a (co)polymer in which the vinyl chloride-based monomer and a comonomer copolymerizable therewith are copolymerized.

Furthermore, as used herein, the term "chlorinated polyvinyl chloride resin" refers to a resin in which the chlorine content in a vinyl chloride-based copolymer is increased by additionally substituting a chlorine group in the main chain of the vinyl chloride-based polymer.

Furthermore, as used herein, the term "chlorinated polyvinyl chloride resin compound" refers to a composition in which various additives are compounded into a chlorinated polyvinyl chloride resin to achieve desired physical properties.

The present invention can be modified in various ways and has various forms, and specific embodiments will be described and explained in detail below. However, it should be understood that the description is not intended to limit the invention to the specific forms disclosed, but rather, is intended to cover all modifications, equivalents and alternatives within the spirit and scope of the present invention.

The method for preparing a chlorinated polyvinyl chloride resin composition according to the present invention, the chlorinated polyvinyl chloride resin composition prepared according to the method, and a chlorinated polyvinyl chloride resin compound including the composition will be described in detail below.

Method for preparing chlorinated polyvinyl chloride resin composition

Traditionally, after the PVC chlorination process, CPVC is produced through a neutralization and washing process to remove the HCl additionally produced during the preparation process and the HCl released from the CPVC. However, the neutralizer used in the neutralization process will reduce the surface properties and long-term processing properties of the processed products, especially the improvement effect of the static thermal stability of CPVC is low.

Therefore, in order to improve the static thermal stability of CPVC, a heat stabilizer is mixed and used during processing and blending to prepare a rubber compound. However, since the processing and blending usually adopts a dry blending method, the dispersion efficiency of the heat stabilizer is low, so it is difficult to obtain a sufficient static thermal stability improvement effect. In addition, it is not easy to change the mixing ratio during processing and blending, and when an excessive amount of heat stabilizer is used, there is a problem of deterioration in processing color (or whiteness index).

In contrast, in the present invention, a specific heat stabilizer is introduced for wet mixing after the neutralization process for preparing CPVC, thereby increasing the dispersion efficiency of the heat stabilizer and improving the processing color and static thermal stability by uniformly mixing with the CPVC.

Furthermore, in the present invention, when preparing CPVC, by using PVC polymerized in the presence of an optimal combination of suspending agents as a base resin, the effect of improving the processing color (or whiteness index) can be further enhanced.

Specifically, the method for preparing a chlorinated polyvinyl chloride resin composition according to the present invention comprises the following steps:

preparing a slurry containing a chlorinated polyvinyl chloride resin by introducing chlorine gas into a suspension in which a vinyl chloride-based polymer is dispersed in an aqueous solvent and performing a chlorination reaction (step 1);

preparing a slurry containing a neutralized chlorinated polyvinyl chloride resin by introducing a neutralizing agent into the slurry containing the chlorinated polyvinyl chloride resin and performing a neutralization reaction (step 2); and

By introducing a heat stabilizer into the slurry containing the neutralized chlorinated polyvinyl chloride resin and mixing (step 3),

The heat stabilizer comprises alkyl tin carboxylate, alkyl tin mercaptan or a mixture thereof.

The chlorinated polyvinyl chloride resin composition refers to a mixture of a heat stabilizer and a neutralized chlorinated polyvinyl chloride resin. The chlorinated polyvinyl chloride resin composition can be a slurry or a powder after the solvent is removed from the slurry by an additional drying process after mixing with the heat stabilizer.

Each step is described in detail below.

Step 1

In the method for preparing the chlorinated polyvinyl chloride resin composition according to the present invention, step 1 is a step of subjecting a vinyl chloride-based polymer to a chlorination reaction to prepare a chlorinated polyvinyl chloride resin.

The chlorination reaction can be carried out by introducing chlorine gas into a suspension of a vinyl chloride-based polymer dispersed in an aqueous solvent and performing a chlorination reaction. Through the chlorination reaction, at least a portion of hydrogen in the vinyl chloride-based polymer is replaced by a chlorine group, thereby preparing a chlorinated polyvinyl chloride resin with an increased chlorine content.

Specifically, the chlorination reaction can be carried out using a vinyl chloride-based polymer at a chlorine pressure of 1.5kgf/ ^cm2 to 3.0kgf/ ^cm2 and a reaction temperature of 60°C to 95°C. When the chlorine pressure is lower than 1.5kgf/ ^cm2 , the reaction time may be delayed and the productivity may be reduced. In addition, when the chlorine pressure is higher than 3.0kgf/ ^cm2 , the thermal stability of the chlorinated polyvinyl chloride resin may deteriorate, and there may be facility safety issues due to high pressure. In addition, when the reaction temperature is lower than 60°C, the reaction time may be delayed and the productivity may be reduced. When the reaction temperature is higher than 95°C, the thermal stability and processing color (or whiteness index) of the chlorinated polyvinyl chloride resin may deteriorate due to the temperature conditions being higher than the glass transition temperature (Tg) of the vinyl chloride-based polymer.

Since the chlorination reaction is carried out under the above-mentioned chlorine gas pressure and reaction temperature conditions, the effect of chlorine gas penetrating into the vinyl chloride-based polymer is enhanced, and thus the internal pores are enlarged, thereby making it possible to prepare a chlorinated polyvinyl chloride resin having a high porosity and bulk density compared to a chlorinated polyvinyl chloride resin prepared by reacting at a lower chlorine gas pressure and/or a lower reaction temperature.

In this regard, the vinyl chloride-based polymer may meet one or more, two or more, three or more, or four of the following requirements (a1) to (a4):

(a1) average particle size (APS) (D[4,3]) measured by laser diffraction analysis: 110 μm to 200 μm, more specifically, 120 μm to 180 μm;

(a2) dioctyl phthalate absorption (or cold plasticizer absorption: CPA) measured at 25° C. according to ASTM D3367: 15% to 37%, more specifically, 18% to 30%;

(a3) bulk density (BD) measured according to ASTM D1895-90: 0.53 g/cm ³ to 0.60 g/cm ³ , more specifically, 0.54 g/cm ³ to 0.58 g/cm ³ ;

(a4) Degree of polymerization (DP) measured according to JIS K 6720-2: 500 to 1,300, more specifically, 700 to 1,000.

Meanwhile, in the present invention, the average particle size (APS) (D[4,3]) of the vinyl chloride-based polymer is a volume weighted average diameter of vinyl chloride-based polymer particles, which can be measured by laser diffraction analysis. The detailed measurement method is described in the following examples.

Specifically, the vinyl chloride-based polymer may be a powder that is a collection of spherical particles that meet the above requirements. Herein, CPA is a measure of porosity, and a high CPA value means a high porosity. Meanwhile, the method for measuring APS, CPA, BD and degree of polymerization of the vinyl chloride-based polymer is as described in the experiment described later, and therefore, the description of the detailed measuring method is omitted.

When one of the CPA and BD of the vinyl chloride-based polymer is below the above range, the diffusion rate of chlorine gas in the subsequent chlorination reaction may be slow. In addition, when one of the CPA and BD of the vinyl chloride-based polymer exceeds the above range, the value of the other is reduced, making it difficult to prepare vinyl chloride-based polymer particles having a desired morphology.

In addition, the degree of polymerization of the vinyl chloride-based polymer is defined within the above range, but is not particularly limited thereto and may be appropriately adjusted and changed depending on the intended use.

In the present invention, the degree of polymerization of the vinyl chloride-based polymer means the number of repeating units (units or monomers) constituting the polymer, and can be measured according to JIS K6720-2.

Meanwhile, the vinyl chloride-based polymer may be prepared by suspension polymerization of a vinyl chloride-based monomer in the presence of a reaction initiator and a suspending agent.

Specifically, suspension polymerization is carried out by reacting vinyl chloride-based monomers in an aqueous medium inert to the monomers in the presence of a reaction initiator and a suspending agent. First, polymerization occurs as the reaction initiator decomposes and undergoes a chain reaction with the vinyl chloride monomers, and the polymerization is terminated when the reaction conversion rate of the vinyl chloride-based monomers reaches a certain level.

As the vinyl chloride-based monomer, a vinyl chloride monomer may be used alone, or a mixture of a vinyl chloride monomer and other monomers copolymerizable with vinyl chloride may be used.

In addition, other monomers that can be copolymerized with vinyl chloride include: olefins, such as ethylene, propylene, butene, etc.; vinyl esters of carboxylic acids, such as vinyl acetate, vinyl propionate, vinyl stearate, etc.; vinyl ethers with alkyl groups, such as methyl vinyl ether, ethyl vinyl ether, octyl vinyl ether, dodecyl vinyl ether, etc.; vinylidene halides, such as vinylidene chloride, etc.; unsaturated carboxylic acids, such as acrylic acid, methacrylic acid, fumaric acid, maleic acid, itaconic acid, maleic anhydride or itaconic anhydride, etc. and their anhydrides; unsaturated carboxylic acid esters, such as methyl acrylate, ethyl acrylate, monomethyl maleate, dimethyl maleate, butyl benzyl maleate, etc.; aromatic vinyl compounds, such as styrene, α-methylstyrene, divinylbenzene, etc.; unsaturated nitriles, such as acrylonitrile, etc.; or crosslinkable monomers, such as diallyl phthalate, etc., which can be used alone or in a mixture of two or more, but are not limited to this. In addition, depending on the desired physical properties or uses of the vinyl chloride-based polymer, a monomer generally used to form a copolymer through a polymerization reaction with a vinyl chloride monomer may be further included.

Furthermore, when a vinyl chloride-based polymer is prepared by polymerizing a vinyl chloride-based monomer or a vinyl chloride-based monomer and another comonomer copolymerizable therewith, the reaction initiator plays a role in initiating the polymerization reaction.

As the reaction initiator, a common oil-soluble polymerization initiator commonly used in the technical field to which the present invention belongs can be used without particular limitation. Specifically, the reaction initiator may include one or more of lauryl peroxide, acetyl cyclohexanol peroxide, bis(3,5,5-trimethylhexanoyl peroxide), t-butylperoxyneodecanoate, 2,2,4-trimethylpentyl-2-peroxyneodecanoate, α-cumyl peroxyneodecanoate, di-butyl peroxydicarbonate, t-butylhydroxyperoxide, bis(2-ethylhexyl)peroxydicarbonate, azobisisobutyronitrile and azobis(2,4-dimethylvaleronitrile), but is not limited thereto.

In this regard, the reaction initiator may be used in an amount of 0.01 to 1.0 parts by weight, more specifically, 0.04 to 0.1 parts by weight, more specifically, 0.04 to 0.08 parts by weight, based on 100 parts by weight of the vinyl chloride-based monomer. When the content of the reaction initiator is within the above range, appropriate polymerization reactivity can be ensured, and reaction heat generated by the polymerization reaction can be easily controlled.

Furthermore, the suspending agent may be a polyvinyl alcohol (PVA)-based polymer, a hydroxypropylmethylcellulose (HPMC)-based polymer, a polyethylene oxide (PEO) polymer, or a mixture thereof.

Herein, the suspending agent refers to a dispersant used to effectively disperse the vinyl chloride-based monomer in an aqueous solvent such as water and prevent aggregation of polymerized water-insoluble (co)polymer particles during suspension polymerization for preparing the vinyl chloride-based polymer.

When a PVA-based polymer is used as the suspending agent, a PVA-based polymer having a saponification degree of 20 mol % to 90 mol % may be used.

When the saponification degree of the PVA-based polymer is less than 20 mol%, it is difficult to fully achieve normal polymerization. In addition, when the saponification degree of the PVA-based polymer is greater than 90 mol%, a PVC polymer with a uniform spherical particle size can be prepared, but it is foreseeable that the processing performance may be deteriorated due to the reduction in porosity.

Herein, the polyvinyl alcohol (PVA)-based polymer is prepared by hydrolyzing a polyester-based polymer polymerized from a vinyl ester-based monomer with an acid or base. The saponification degree of the polyvinyl alcohol (PVA)-based polymer refers to the saponification degree of the ester group in the polyester-based polymer converted into an alcohol group.

In addition, as a suspending agent, a mixture of two or more PVA-based polymers having different saponification degrees in the range of 20 mol% to 90 mol% can be used. As described, when a mixture of the suspending agents is used, the physical properties required according to the use of the PVC polymer to be prepared can be easily achieved.

For example, the suspending agent may be a mixture comprising a polyvinyl alcohol-based polymer having a saponification degree of 78 mol% to 90 mol% as a first suspending agent; a polyvinyl alcohol-based polymer having a saponification degree of 70 mol% or more and less than 78 mol% as a second suspending agent; and a polyvinyl alcohol-based polymer having a saponification degree of 20 mol% or more and less than 70 mol% as a third suspending agent.

More specifically, the suspending agent may be a mixture comprising a PVA-based polymer having a saponification degree of 78 mol% or more, or 80 mol% or more, and 90 mol% or less, or 85 mol% or less as a first suspending agent; a PVA-based polymer having a saponification degree of 70 mol% or more and less than 78 mol% or less than 75 mol% as a second suspending agent; and a PVA-based polymer having a saponification degree of 20 mol% or more, or 30 mol% or more, or 40 mol% or more and less than 70 mol% or less than 60 mol% as a third suspending agent. When a mixture of PVA-based polymers having the above-mentioned saponification degree requirements is used, a PVC polymer that meets the above-mentioned average particle size, dioctyl phthalate absorption rate, and bulk density requirements may be prepared.

In addition, when a mixture of PVA-based polymers with different saponification degrees is used, the mixing ratio can be selected according to the physical properties of the PVC polymer to be achieved. For example, when a mixture of the first to third suspending agents based on PVA with different saponification degrees as described above is adopted, based on 100 parts by weight of the mixture containing the first to third suspending agents, the content of the first suspending agent can be 50 to 70 parts by weight, the content of the second suspending agent can be 20 to 35 parts by weight, and the content of the third suspending agent can be 5 to 20 parts by weight. More specifically, based on 100 parts by weight of the mixture, the content of the first suspending agent can be 50 to 60 parts by weight, the content of the second suspending agent can be 20 to 30 parts by weight, and the content of the third suspending agent can be 10 to 20 parts by weight.

In addition, when a polymer based on hydroxypropyl methylcellulose (HPMC) is used as a suspending agent, a polymer based on hydroxypropyl methylcellulose (HPMC) having a methoxyl substitution degree of 1.2 to 1.9 and a hydroxypropoxyl substitution degree of 0.15 to 0.25 can be specifically used.

Meanwhile, the methoxy substitution degree indicates the average molar number of methoxy groups (or methyl ether groups) present per anhydroglucose unit in a cellulose molecule, i.e., a polymer molecule based on HPMC, and the hydroxypropoxy substitution degree indicates the average molar number of hydroxypropoxy groups present per anhydroglucose unit in a cellulose molecule.

In addition, when a polyethylene oxide (PEO)-based polymer is used as a suspending agent, a PEO-based polymer having a weight average molecular weight (Mw) of 4,000,000 g/mol or more, or 4,200,000 g/mol or more, or 4,500,000 g/mol or more, and 5,000,000 g/mol or less, or 4,800,000 g/mol or less may be specifically used.

Meanwhile, in the present invention, the weight average molecular weight (Mw) of PEO is a conversion value of standard polystyrene, and can be measured using gel permeation chromatography (measuring temperature: 160° C., solvent: 1,2,4-trichlorobenzene).

In addition, a mixture of a polymer based on HPMC, a polymer based on PVA and a polymer based on PEO can be used as a suspending agent. At this time, the polymer based on HPMC, the polymer based on PVA and the polymer based on PEO are as described above.

For example, the suspending agent can be a mixture including a first suspending agent, a second suspending agent and a third suspending agent, wherein the first suspending agent is an HPMC-based polymer having a methoxyl substitution degree of 1.2 or more, or 1.4 or more and 1.9 or less, and a hydroxypropoxyl substitution degree of 0.15 or more and 0.25 or less, or 0.2 or less; the second suspending agent is a PVA-based polymer having a saponification degree of 20 mol% or more and 60 mol% or less; and the third suspending agent is a PEO-based polymer having a weight average molecular weight (Mw) of 4,000,000 g/mol or more and 5,000,000 g/mol or less.

HPMC-based polymers have excellent stability and high surface activity, so it has a controlling effect on the average particle size of the prepared PVC polymer. As its content increases, the average particle size of the prepared PVC polymer decreases.

The PVA-based polymer has a high solubility for vinyl chloride-based monomers, so it can control the porosity of the prepared PVC polymer and also play a role in increasing the absorption rate of dioctyl phthalate (or cold plasticizer absorption (CPA)).

However, since HPMC-based polymers have higher surface activity than PVA-based polymers, a large amount of foam is generated and there is a problem of deterioration of polymerization stability. For this reason, a mixture of PEO-based polymers is used to increase the viscosity of the prepared PVC polymer, thereby suppressing the generation of foam and improving polymerization stability. In addition, HPMC-based polymers can solve the problem of deterioration of processing color of processed products of chlorinated polyvinyl chloride after chlorination when using PVA-based polymers.

As described above, when a mixture of an HPMC-based polymer, a PVA-based polymer, and a PEO-based polymer is used as a suspending agent, a PVC polymer having improved physical properties can be prepared, specifically, a PVC polymer satisfying the above-mentioned average particle size, dioctyl phthalate absorption rate, and bulk density requirements can be prepared.

In addition, when using a mixture of a polymer based on HPMC, a polymer based on PVA and a polymer based on PEO, the mixing ratio can be selected according to the physical properties of the PVC polymer to be achieved. For example, based on 100 parts by weight of a mixture of a polymer based on HPMC, a polymer based on PVA and a polymer based on PEO, the content of the polymer based on HPMC can be 60 to 85 parts by weight, the content of the polymer based on PVA can be 10 to 30 parts by weight, and the content of the polymer based on PEO can be 3 to 15 parts by weight. More specifically, based on 100 parts by weight of the mixture, the content of the polymer based on HPMC can be 70 to 80 parts by weight, the content of the polymer based on PVA can be 10 to 20 parts by weight, and the content of the polymer based on PEO can be 5 to 10 parts by weight.

Based on 100 parts by weight of vinyl chloride monomer, the amount of the above suspending agent can be: 0.0005 parts by weight or more, or 0.0007 parts by weight or more, or 0.001 parts by weight or more, and 0.002 parts by weight or less, or 0.0015 parts by weight or less, or 0.0013 parts by weight or less. In addition, when a mixture of two or more suspending agents is used, the amount of the suspending agent is the same as the total amount of the suspending agents used in combination.

More specifically, the polymerization reaction can be carried out by the following steps: introducing a reaction initiator and a suspending agent into a reactor together with deionized water, and then evacuating the interior of the reactor to remove oxygen; introducing a predetermined amount of vinyl chloride-based monomer into the deoxygenated reactor, raising the temperature of the reactor to a polymerization temperature, confirming that there is a stable reference pressure in the reactor, and then carrying out a polymerization reaction; terminating the polymerization reaction when the pressure in the reactor drops by 0.5 kgf/ ^cm2 relative to the reference pressure; and recovering the polymerized vinyl chloride-based polymer.

The polymerization reaction may be performed at a temperature range of 40° C. to 80° C. In addition, the polymerization reaction may be performed at the above temperature range for 200 minutes to 600 minutes. Through the above polymerization reaction, a vinyl chloride-based polymer is obtained.

Meanwhile, the chlorination reaction is carried out at a chlorine gas pressure of 1.5 kgf/ ^cm2 to 3.0 kgf/ ^cm2 and a temperature of 60°C to 95°C.

Specifically, during the chlorination reaction, when the chlorine pressure is lower than 1.5 kgf/ ^cm2 , the reaction time may be delayed and the productivity may be reduced. In addition, when the chlorine pressure is higher than 3.0 kgf/ ^cm2 , the thermal stability of the chlorinated polyvinyl chloride resin may deteriorate, and facility safety problems may occur due to the high pressure.

In addition, during the chlorination reaction, when the reaction temperature is lower than 60°C, the reaction time may be delayed and the productivity may be reduced. When the reaction temperature is higher than 95°C, the thermal stability and processing color of the chlorinated polyvinyl chloride resin may be deteriorated due to the temperature condition being higher than the glass transition temperature (Tg) of the vinyl chloride-based polymer.

In addition, the chlorination reaction can be carried out in a suspension or slurry phase in which the vinyl chloride-based polymer is dispersed in an aqueous solvent. In other words, the vinyl chloride-based polymer can be introduced in a suspension or slurry state. Herein, the suspension or slurry refers to a dispersed mixture in which the vinyl chloride-based polymer is dispersed in an insoluble solvent rather than dissolved therein. In the present invention, a mixture in which polymers produced by various stage reactions such as a polymerization reaction, a subsequent chlorination reaction, and a neutralization reaction are dispersed is referred to as a "slurry", and a mixture of a slurry or a dehydrated slurry in which impurities are removed from the slurry and a solvent is referred to as a "suspension". Specifically, the vinyl chloride-based polymer can be introduced as a suspension in which the polymer is dispersed in an aqueous solvent (e.g., deionized water) used in the polymerization reaction.

At this time, the content of the vinyl chloride-based polymer (or solid content) in the suspension may be 10% to 35% of the total weight of the suspension. The chlorination reaction may be effectively performed within the above range.

The chlorination reaction can be initiated by ultraviolet (UV) irradiation. Alternatively, it can also be initiated by introducing a photoinitiator instead of ultraviolet irradiation. Chlorine forms free radicals by ultraviolet irradiation or a photoinitiator, and initiates a chlorination reaction caused by a photoreaction. In this regard, as a photoinitiator, a compound commonly referred to as a photoinitiator can be used without limitation. For example, one or more selected from peroxyesters, hydroperoxides and dialkyl oxides can be used.

More specifically, the chlorination reaction can be carried out by the following steps: introducing a vinyl chloride-based polymer into a reactor and then applying a vacuum inside the reactor to remove oxygen; injecting chlorine gas into the reactor from which oxygen has been removed under the above-mentioned pressure, raising the temperature of the reactor to the above-mentioned reaction temperature, and performing a photoreaction by ultraviolet irradiation; and terminating the reaction when the chlorine content in the vinyl chloride-based polymer reaches a target amount.

In this regard, the chlorination reaction time may be 100 minutes to 180 minutes. Herein, the reaction time specifically refers to the time from the injection of chlorine gas to the time when the chlorine content in the vinyl chloride-based polymer reaches the target amount. As demonstrated in the experimental examples described below, the reaction time is significantly reduced compared to the case of a vinyl chloride-based polymer prepared using a suspending agent combination different from the present invention.

In addition, the chlorination reaction can be carried out so that the chlorine content in the chlorinated polyvinyl chloride resin is 63 wt % to 70 wt % based on the total weight of the chlorinated polyvinyl chloride resin. This can be achieved by setting the target amount of chlorine content in the vinyl chloride-based polymer to be the same as the above range. The vinyl chloride-based resin chlorinated within the above range has excellent mechanical properties, heat resistance and chemical resistance, and can be used in various applications such as hot and cold water pipes, industrial pipes, spray pipes, adhesives, etc.

Furthermore, in the preparation method according to the present invention, the chlorination reaction may be performed in the presence of polystyrene sulfonic acid (PSS) or an alkali metal salt thereof.

PSS or its alkali metal salt is water-soluble, has surface activity and antistatic properties, and can also act as a dispersant. In addition, according to the preparation method of the present invention, the vinyl chloride-based polymer prepared by suspension polymerization has a high porosity. Therefore, the diffusion rate of chlorine gas increases during the chlorination reaction, and as a result, excellent reactivity can be exhibited. However, excess gas may adhere to the vinyl chloride-based polymer, which may cause the aqueous phase resin to float. Therefore, undispersed resin may adhere to the top of the reactor, or cavitation may occur in the pump when transporting for post-processing. In addition, carbon dioxide produced as a neutralization by-product may cause the same phenomenon in the subsequent neutralization reaction. Therefore, this phenomenon can be prevented by adding PSS or its alkali metal salt.

PSS or its alkali metal salt may specifically include the repeating unit of the following formula 1:

[Formula 1]

In Formula 1, n is an integer of 1 to 100, and A is H or Na.

More specifically, PSS is sodium polystyrene sulfonate.

The amount of PSS or its alkali metal salt introduced can be 50 ppm to 1000 ppm based on the weight of the vinyl chloride-based polymer. When the amount of PSS or its alkali metal salt used is less than 50 ppm, there may be a problem of floating of the resulting CPVC. On the contrary, when the amount used exceeds 1000 ppm, bubbles will be generated during the slurry stirring process, which may cause a problem of reducing the reaction and neutralization efficiency. More specifically, based on the weight of the vinyl chloride-based polymer, the amount of PSS or its alkali metal salt introduced can be 50 ppm or more, or 60 ppm or more, or 80 ppm or more, or 100 ppm or more, and 750 ppm or less, or 500 ppm or less, or 200 ppm or less.

In addition, there is no particular recommendation for the time of introduction of PSS or its alkali metal salt, and it can be introduced at any time after the chlorination reaction and before the unreacted chlorine is removed from the suspension. In other words, PSS or its alkali metal salt can be added before chlorine gas is blown into the suspension, while introducing chlorine gas, or after introducing chlorine gas to carry out the reaction. However, it is preferred to introduce PSS or its alkali metal salt before the introduction of chlorine gas. For example, it can be introduced in a mixed form with the suspension containing PVC. As described above, since PSS or its alkali metal salt is introduced before the unreacted chlorine gas is recovered, PSS or its alkali metal salt is not used as a CPVC post-treatment agent in the present invention.

In a preferred embodiment, PSS or an alkali metal salt thereof can be introduced into the suspension. In addition to the introduction of PSS or an alkali metal salt thereof, the chlorination process of step 2 can be carried out using conditions known to be applicable in the art. For example, the preparation of the suspension, the blowing of chlorine gas, the chlorination reaction process and the chlorination post-treatment can all be carried out in exactly the same manner as the conventional method. For example, the chlorination reaction can be promoted by heating the suspension or irradiating the suspension with light such as ultraviolet light during the chlorination reaction.

Through the above chlorination reaction, chlorinated polyvinyl chloride resin can be prepared.

Meanwhile, the chlorinated polyvinyl chloride resin prepared by the polymerization reaction is obtained in a slurry state. Therefore, the slurry obtained after the chlorination reaction may optionally be further subjected to a dehydration process and a suspension preparation process of mixing with a solvent.

Therefore, the chlorinated polyvinyl chloride resin prepared by the chlorination reaction can be i) a slurry after the chlorination reaction, ii) a dehydrated slurry from which impurities are removed, or iii) a suspension prepared by mixing the dehydrated slurry with a solvent.

Step 2

In the method for preparing the chlorinated polyvinyl chloride resin composition according to the present invention, step 2 is a step of introducing a neutralizing agent into the chlorinated polyvinyl chloride resin prepared in step 1 to remove residual HCl in the chlorinated polyvinyl chloride resin by neutralization.

The neutralization reaction is to remove the residual HCl in the chlorinated polyvinyl chloride resin to prevent the residual HCl in the resin from acting as a catalyst to promote the decomposition of the vinyl chloride-based resin, thereby causing a decrease in processing stability and corrosion to equipment.

The neutralization reaction is carried out by adding a neutralizing agent that can increase the pH.

The neutralizing agent may be used without limitation as long as the neutralizing agent can neutralize HCl and increase the pH to a desired level. In the present invention, as the neutralizing agent, a) a percarbonate-based compound; or b) a mixture of a carbonate-based compound and hydrogen peroxide may be used.

a) Percarbonate-based compounds can effectively remove hydrochloric acid and hypochlorite that may remain in the pores of CPVC, thereby improving resin discoloration, thermal stability and processing discoloration.

a) The percarbonate-based compound may specifically be sodium percarbonate (SPC), potassium percarbonate or calcium percarbonate, and any one of them or a mixture of two or more thereof may be used.

Meanwhile, a) the compound based on percarbonate is a mixture of a compound based on carbonate and hydrogen peroxide. Therefore, as a neutralizing agent, the compound based on percarbonate can be used as a single compound, but can also be used in the form of a mixture of a compound based on carbonate and hydrogen peroxide. For example, sodium percarbonate can be used as a compound based on percarbonate, or a mixture of sodium carbonate (SC) and hydrogen peroxide in a mol ratio of 1:1.5 can be used. This mol ratio is only an example, and is not limited thereto.

In addition, in the present invention, when a percarbonate-based compound is used as a neutralizing agent, a basic compound may also be optionally used.

The alkaline compound may include sodium carbonate, sodium bicarbonate or potassium bicarbonate, and any one of them or a mixture of two or more thereof may be used. When the alkaline compound is also used, a percarbonate-based compound and an alkaline compound may be used in a weight ratio of 80:20 to 20:80, or 65:35 to 35:65. For example, as a neutralizer, a neutralizer of 100 wt% SPC may be used; a neutralizer of a mixture of SC and SPC in which 20 wt% SC is mixed; a neutralizer of a mixture of SC and SPC in which 50 wt% SC is mixed; and a neutralizer of a mixture of SC and SPC in which 80 wt% SC is mixed.

In addition, when b) a mixture of carbonate compounds and hydrogen peroxide is used as a neutralizing agent, the carbonate-based compound plays a role in neutralizing hydrochloric acid to increase the pH value, while the hydrogen peroxide plays a role in removing hypochlorite. Therefore, the existing thermal stability and discoloration problems can be improved. In addition, since the carbonate compound and hydrogen peroxide react with each other to generate a compound based on percarbonate, the same effect as the above-mentioned compound based on percarbonate can be obtained.

The carbonate-based compound may include sodium carbonate, sodium bicarbonate, potassium carbonate, potassium bicarbonate or calcium carbonate, and any one of them or a mixture of two or more thereof may be used. Among them, sodium carbonate can more effectively remove hydrochloric acid when mixed with hydrogen peroxide, thereby further improving the physical properties of CPVC.

b) The mixture of the carbonate-based compound and hydrogen peroxide may be mixed in a molar ratio of 1:0.1 to 1:2 or 1:0.5 to 1:1.8. When the mixing molar ratio deviates from the above range, and the amount of hydrogen peroxide used is too small relative to the carbonate-based compound, the processed color (or whiteness index) may be deteriorated. In addition, when the amount of hydrogen peroxide used is too large relative to the carbonate-based compound, there is a problem of increased cost.

Regarding the usage amount, the above neutralizing agent may be introduced to meet the desired pH conditions, specifically, pH 6 to 10, or pH 6.5 to 9. More specifically, the neutralizing agent may be introduced in an amount of 1 to 5 parts by weight based on 100 parts by weight of CPVC. In addition, the neutralizing agent may be introduced in the form of a powder or a solution.

Meanwhile, the neutralization reaction may be performed by introducing the neutralizing agent into a slurry, a cake or a suspension including the chlorinated polyvinyl chloride resin, because as a result of step 2, the chlorinated polyvinyl chloride resin is obtained in the form of i) slurry after the chlorination reaction, ii) cake-shaped dehydrated slurry from which impurities are removed, or iii) a suspension prepared by mixing the dehydrated slurry with a solvent.

For example, after completing the chlorination reaction in step 2, the reaction product may be in a slurry state. At this time, the neutralizer may be directly introduced into the CPVC in a slurry state without performing a separate purification process during the neutralization process. Alternatively, the neutralizer may be introduced into a dehydrated CPVC slurry that has been dehydrated to remove impurities. Alternatively, the neutralizer may be introduced into a suspension that has been re-slurried by introducing a solvent into the dehydrated CPVC slurry. Among the above methods, it is most effective to introduce the neutralizer into the re-slurried suspension after dehydration to remove impurities and reduce the amount of neutralizer used. The solvent added to the dehydrated CPVC slurry may be distilled water, ethanol, or the like. In addition, when a slurry or suspension is used, the solid content may be 20% to 50% by weight.

In addition, the neutralization reaction may be performed at a temperature ranging from 25° C. to 100° C., or from 40° C. to 80° C., or from 60° C. to 80° C. At this time, stirring may be performed to improve the neutralization efficiency.

Through the above neutralization reaction, a neutralized chlorinated polyvinyl chloride resin in a slurry state can be obtained.

Step 3

In the method for preparing a chlorinated polyvinyl chloride resin composition according to the present invention, step 3 is a step of preparing a chlorinated polyvinyl chloride resin composition by introducing a heat stabilizer into a slurry containing a neutralized chlorinated polyvinyl chloride resin and mixing.

Generally, heat stabilizers are introduced during processing and blending and dry-mixed. In contrast, in the present invention, a specific heat stabilizer is introduced into the chlorinated polyvinyl chloride resin in a slurry state after the neutralization process and then mixed, thereby improving the dispersion efficiency of the heat stabilizer so that it can be uniformly mixed with the chlorinated polyvinyl chloride resin.

Specifically, the heat stabilizer includes alkyl tin carboxylates, alkyl tin mercaptides, or mixtures thereof.

Compared with common heat stabilizers, specifically inorganic salts and organic salts of metals such as calcium, zinc, tin, magnesium, sodium, potassium, and epoxy soybean oil, alkyl tin carboxylates and alkyl tin mercaptides can be uniformly mixed when introduced into chlorinated polyvinyl chloride resin in a slurry state, and not only have excellent thermal stability improvement effects, but also have excellent compatibility with PVC polymerized in the presence of an optimal combination of suspending agents. Moreover, since the heat stabilizer is introduced into a slurry state, there will be no safety problems even if it is discharged with wastewater during the preparation process.

More specifically, as the alkyl tin carboxylate, there can be used an alkyl tin carboxylate having 1 or more, 2 or more, or 4 or more, and 20 or less, 10 or less, 8 or less, or 6 or less carbon atoms. Also, as the alkyl tin mercaptide, there can be used an alkyl tin mercaptide having 1 or more, 20 or less, 10 or less, 8 or less, 4 or less, 3 or less, or 2 or less carbon atoms.

Specific examples of heat stabilizers can include methyl tin carboxylate, butyl tin carboxylate, octyl tin carboxylate, methyl tin mercaptide, butyl tin mercaptide, octyl tin mercaptide, etc., and any one of them or a mixture of two or more thereof can be used. In addition, commercially available products corresponding to the above-mentioned heat stabilizers can be used, such as SONGSTAB ^™ TM-600P (Songyuan Industry), SONGSTAB ^™ MT-800 (Songyuan Industry), SONGSTAB ^™ OT-700R (Songyuan Industry), SONGSTAB ^™ BT-711C (Songyuan Industry) or SONGSTAB ^™ TM-700R (Songyuan Industry).

Among them, butyltin carboxylate, methyltin mercaptan, or a mixture thereof may be preferably used as the heat stabilizer in terms of excellent improving effect.

Considering the effect of improving static thermal stability, the thermal stabilizer may be used in an amount of 0.3 to 3 parts by weight or 0.5 to 2 parts by weight based on 100 parts by weight of the neutralized chlorinated polyvinyl chloride resin.

The usage amount of heat stabilizer increases, and static thermal stability can be improved. However, if the usage amount is too large, the processing color (or whiteness index) may deteriorate. Therefore, considering the effects of improving static thermal stability and processing color at the same time, based on 100 parts by weight of neutralized chlorinated polyvinyl chloride resin, the usage amount of heat stabilizer is preferably 0.5 parts by weight to 1.2 parts by weight. When used within the above range, the effect of improving static thermal stability can be achieved without deteriorating the processing color (or whiteness index). More specifically, based on 100 parts by weight of neutralized chlorinated polyvinyl chloride resin, the usage amount of heat stabilizer can be more than 0.5 parts by weight, or more than 0.75 parts by weight, and less than 1.2 parts by weight, or 1 part by weight.

For this purpose, the amount of the neutralized chlorinated polyvinyl chloride resin is determined based on a mass balance calculation according to the input amount of PVC.

In the chlorination reaction, dehydrogenation and chlorination reactions occur simultaneously in the PVC chain. Chlorination occurs when chlorine combines with the site that releases hydrogen. At this time, half of the introduced chlorine reacts with PVC, and the other half becomes hydrochloric acid or hypochlorous acid. For example, in order to synthesize 67.3% CPVC from 100g PVC, 62.6g of chlorine needs to be introduced, and half of the input amount, that is, 31.3g of chlorine, combines with the PVC chain, and 0.89g of hydrogen is released at this time. It has been experimentally confirmed that the chlorine conversion rate is about 97%, and at this time 30.4g of chlorine combines with the PVC chain and releases 0.86g of hydrogen. Therefore, when 100g PVC is introduced, 129.54g, about 130g of CPVC with a chlorine content of 67.3%, is synthesized. At the same time, the CPVC is neutralized after the preparation of CPVC, but neutralization does not affect the weight of CPVC. Therefore, it is considered that the calculated CPVC content is the same as the CPVC content after neutralization.

Therefore, when 0.5 parts by weight of the heat stabilizer is introduced based on 100 parts by weight of the neutralized chlorinated polyvinyl chloride resin, the input amount of the heat stabilizer is 0.65 g.

The mixing of the neutralized chlorinated polyvinyl chloride resin slurry and the heat stabilizer can be carried out according to conventional methods.

For example, mixing may be performed under the same conditions as step 2. Specifically, mixing may be performed at a temperature range of 25° C. to 100° C. More specifically, mixing may be performed at a temperature of 25° C. or more, or 40° C. or more, or 50° C. or more, and 100° C. or less, or 80° C. or less, or 60° C. or less. Furthermore, stirring may be performed for uniform mixing.

Through the above mixing process, a chlorinated polyvinyl chloride resin composition in which the heat stabilizer is mixed with the neutralized chlorinated polyvinyl chloride resin can be obtained.

Although the resin composition is in a slurry state, by removing the solvent in the slurry through an additional dehydration and drying process after mixing with the heat stabilizer, a resin composition in the form of a powder in which the chlorinated polyvinyl chloride resin and the heat stabilizer are uniformly mixed can be obtained. In this regard, the dehydration and drying process can be performed according to a common method.

Chlorinated polyvinyl chloride resin composition

The chlorinated polyvinyl chloride resin composition prepared according to the preparation method of the present invention comprises a chlorinated polyvinyl chloride resin and a heat stabilizer.

Since chlorinated polyvinyl chloride resin is prepared by chlorination and neutralization reactions using PVC as a base resin, which is polymerized in the presence of an optimal combination of suspending agents, it is characterized by increased dioctyl phthalate absorption (CPA) and bulk density (BD), as well as improved resin color and productivity.

Meanwhile, the heat stabilizer is as described above.

Chlorinated polyvinyl chloride resin compound

The chlorinated polyvinyl chloride resin compound according to the present invention comprises a chlorinated polyvinyl chloride resin composition; in addition, it also comprises additives for producing physical properties required for various applications. The use of the additives is not limited as long as they are additives commonly used in the CPVC processing process. Specifically, the additives can be one or more of an impact modifier, a heat stabilizer, a filler, a processing aid, a pigment and a lubricant.

The impact modifier may be one or more selected from acrylic resins, methyl methacrylate-butadiene-styrene (MBS)-based resins, and chlorinated polyethylene (CPE)-based resins, but is not limited thereto.

On the other hand, any heat stabilizer can be used without limitation, as long as it is a heat stabilizer commonly used in the preparation process of polyvinyl chloride resin compound, such as inorganic salts and organic salts of metals such as calcium, zinc, tin, magnesium, sodium, potassium, and epoxy soybean oil. Specifically, an organotin-based heat stabilizer can be used. The organotin-based heat stabilizer can specifically be a tin-containing carboxylate or a tin-containing mercaptan salt, and one or a mixture of two or more thereof can be used.

Further, the tin-containing carboxylate heat stabilizer may include an alkyltin carboxylate having a carbon number of 1 or more, 2 or more, 4 or more, and 20 or less, 10 or less, 8 or less, or 6 or less, such as methyltin carboxylate, butyltin carboxylate, octyltin carboxylate, etc. Further, the alkyltin mercaptan heat stabilizer may include an alkyltin mercaptan having a carbon number of 1 or more, and 20 or less, 10 or less, 8 or less, 4 or less, or 3 or less, such as methyltin mercaptan, butyltin mercaptan, octyltin mercaptan, etc. Among them, butyltin carboxylate, methyltin mercaptan, or a mixture thereof may be preferably used from the aspect of excellent improvement effect. In addition, commercially available products corresponding to the above-mentioned organotin-based stabilizers may be used, such as SONGSTAB ^™ TM-600P (Songwon Industries), SONGSTAB ^™ MT-800 (Songwon Industries), SONGSTAB ^™ OT-700R (Songwon Industries), SONGSTAB ^™ BT-711C (Songwon Industries), or SONGSTAB ^™ TM-700R (Songwon Industries).

In addition, the filler may include titanium dioxide, aluminum oxide, calcium carbonate, talc, etc., and any one of them or a mixture of two or more thereof may be used.

The processing aid may be one or more selected from acrylate, methacrylate, styrene/methacrylate copolymer, acrylonitrile/butadiene/styrene copolymer, styrene/acrylonitrile copolymer, poly(α-methylstyrene), but is not limited thereto.

The pigment may be an organic pigment or an inorganic pigment known in the same technical field. For example, the pigment may include an azo-based pigment, a disazo-based pigment, a phthalocyanine-based pigment, or carbon black, but is not limited thereto.

The lubricant may include stearic acid, a metal salt of stearic acid (e.g., calcium salt, magnesium salt, zinc salt, etc.); a synthetic wax in the form of an ester or amide; a hydrocarbon such as montan wax, paraffin, mineral oil, etc.; or a silicone compound, etc. More specifically, the lubricant may include zinc stearate, magnesium stearate, calcium stearate, PE wax, PP wax, calcium montanate, magnesium montanate, or sodium montanate, but is not limited thereto.

Based on 100 parts by weight of the chlorinated polyvinyl chloride resin composition, the content of these additives can be 1 part by weight to 30 parts by weight. Within the above range, the physical properties required for the compound rubber are achieved while maintaining the original characteristics of the chlorinated polyvinyl chloride resin.

Specifically, based on 100 parts by weight of the chlorinated polyvinyl chloride resin composition, the chlorinated polyvinyl chloride resin mix may include 1 to 10 parts by weight of an impact modifier, 1 to 5 parts by weight of a heat stabilizer, 1 to 5 parts by weight of a lubricant, 1 to 5 parts by weight of a processing aid, and 1 to 5 parts by weight of a filler. More specifically, based on 100 parts by weight of the chlorinated polyvinyl chloride resin composition, the chlorinated polyvinyl chloride resin mix may include 5 to 10 parts by weight of an impact modifier, 2 to 4 parts by weight of a heat stabilizer, 2 to 4 parts by weight of a lubricant, 2 to 4 parts by weight of a processing aid, and 2 to 4 parts by weight of a filler. More specifically, based on 100 parts by weight of the chlorinated polyvinyl chloride resin composition, the chlorinated polyvinyl chloride resin compound may include 5 to 10 parts by weight of an MBS-based resin as an impact modifier; 2 to 4 parts by weight of an alkyl tin carboxylate as a thermal stabilizer; 2 to 4 parts by weight of a paraffin wax as a lubricant; 2 to 4 parts by weight of an acrylic processing aid as a processing aid; and 2 to 4 parts by weight of titanium dioxide as a filler.

After the above additives are added to the chlorinated polyvinyl chloride resin composition, the chlorinated polyvinyl chloride resin compound is mixed with a conventional stirring machine such as a kneader, a mixer, etc., and heating and pressure conditions are applied during the mixing process as needed.

Due to the inclusion of the chlorinated polyvinyl chloride resin composition, the chlorinated polyvinyl chloride resin compound can exhibit excellent static thermal stability and processing color (or whiteness index).

Specifically, the chlorinated polyvinyl chloride resin compound can have a static thermal stability of more than 105 minutes and a whiteness index of more than 5, wherein the static thermal stability is measured by measuring the time until carbonization of a sample made of 1 mm thickness at a temperature of 190° C. to 195° C., and the whiteness index is measured on a sample made of 3 mm thickness. The higher the static thermal stability and the whiteness index, the better, and therefore, the upper limit is not particularly limited. However, considering that the static thermal stability is improved as the amount of the heat stabilizer used increases, but the processing color deteriorates, the chlorinated polyvinyl chloride resin compound can have a static thermal stability of 105 minutes to 200 minutes and a whiteness index of 15 to 50 in terms of the effect of simultaneously improving the static thermal stability and the processing color. More specifically, the chlorinated polyvinyl chloride resin compound can have a static thermal stability of more than 105 minutes, or more than 110 minutes, or more than 120 minutes, or more than 130 minutes, or more than 150 minutes, and less than 200 minutes, or less than 180 minutes, and a whiteness index of more than 15, or more than 20, or more than 30, and less than 50.

Hereinafter, preferred exemplary embodiments will be provided to better understand the present invention. However, the following exemplary embodiments are only used to make it easier to understand the present invention, but the content of the present invention is not limited thereto.

In the present invention, the average particle size, dioctyl phthalate absorption rate, and bulk density of the vinyl chloride-based polymer and the chlorinated polyvinyl chloride resin are measured as follows.

1) Average particle size (APS) (D[4,3]): In the present invention, the average particle size (D[4,3]) of the vinyl chloride-based polymer, i.e., the volume-weighted average diameter of the particles, is measured by laser diffraction analysis. Specifically, vinyl chloride-based polymer particles are dispersed in deionized water (DW) as a dispersion medium, and then put into a laser diffraction particle size distribution instrument Mastersizer 3000 particle size analyzer (manufactured by Malvern), and the particle size distribution is calculated by measuring the difference in diffraction patterns generated according to the particle size when the particles pass through a laser beam, and the average diameter (D[4.3]) calculated according to the volume of the vinyl chloride-based polymer particles is expressed as the average particle size.

2) Dioctyl phthalate absorption (CPA): The dioctyl phthalate (DOP) absorption was measured at 25°C according to ASTM D3367.

3) Bulk density (BD): Bulk density was measured according to ASTM D1895-90. Specifically, the resin was freely dropped into a 50 cc cylinder, and the density of the contained vinyl chloride polymer or chlorinated polyvinyl chloride resin was measured.

4) Degree of polymerization (DP): measured according to JIS K 6720-2.

<Preparation of vinyl chloride-based polymers>

Preparation Example 1

In a 5L reactor, 0.83g (0.0007 weight part) of the first suspending agent (PVA, saponification degree 80.0mol%), 0.42g (0.00035 weight part) of the second suspending agent (PVA, saponification degree 75.0mol%), 0.18g (0.00015 weight part) of the third suspending agent (PVA, saponification degree 40.0mol%), 0.24g of the reaction initiator peroxy neodecanoic acid tert-butyl ester, and 0.54g of bis (3,5,5-trimethylhexanoyl) peroxide were added together with 2070g of deionized water. Then, the reactor was evacuated using a vacuum pump to remove oxygen in the reactor. At the same time, the above "weight parts" are values based on 100 weight parts of vinyl chloride monomer.

1190 g (100 parts by weight) of vinyl chloride monomer (VCM ^TM , manufactured by Hanwha Chemical Co., Ltd.) was added to the reactor from which oxygen was removed, the temperature of the reactor was raised to 68° C. to initiate polymerization, and then the stable reference pressure inside the reactor was checked. Thereafter, the reaction was carried out for 229 minutes while maintaining the above temperature, and the polymerization reaction was terminated when the pressure inside the reactor dropped by 0.5 kgf/cm ² relative to the reference pressure, thereby obtaining a suspension in which a vinyl chloride-based polymer was dispersed in deionized water.

In order to measure the physical properties, a portion of the suspension was dehydrated and dried to obtain a vinyl chloride-based polymer (PVC).

The vinyl chloride-based polymer particles thus synthesized had an average particle size (APS) (D[4.3]) of 172 μm, a dioctyl phthalate absorption (CPA) of 18.8% at 25° C. measured in accordance with ASTM D3367, and a bulk density (BD) of 0.58 g/cm ³ measured in accordance with ASTM D1895-90. In addition, the degree of polymerization (DP) measured in accordance with JIS K 6720-2 was 700.

Preparation Example 2

In a 5L reactor, 1.2g (0.001 parts by weight) of a first suspending agent (HPMC, methoxyl substitution of 1.4, hydroxypropoxyl substitution of 0.2), 0.24g (0.0002 parts by weight) of a second suspending agent (PVA, saponification degree of 40 mol%), 0.12g (0.0001 parts by weight) of a third suspending agent (PEO, weight average molecular weight of 4,500,000 g/mol), 0.24g of a reaction initiator tert-butyl peroxyneodecanoate and 0.54g of bis(3,5,5-trimethylhexanoyl) peroxide were added together with 2070g of deionized water. Then, a vacuum was applied to the reactor using a vacuum pump to remove oxygen in the reactor. Meanwhile, the above "parts by weight" are values based on 100 parts by weight of vinyl chloride monomer.

1190 g (100 parts by weight) of vinyl chloride monomer (VCM ^TM , manufactured by Hanwha Chemical Co., Ltd.) was added to the reactor from which oxygen was removed, the reactor temperature was raised to 68° C. to initiate polymerization, and then the stable reference pressure inside the reactor was checked. Thereafter, the reaction was carried out while maintaining the above temperature for 229 minutes, and the polymerization reaction was terminated when the pressure inside the reactor dropped by 0.5 kgf/cm ² relative to the reference pressure, to obtain a suspension in which a vinyl chloride-based polymer was dispersed in deionized water.

In order to determine the physical properties, a portion of the suspension was dehydrated and dried to obtain a vinyl chloride-based polymer (PVC).

The vinyl chloride-based polymer particles thus obtained had an average particle size (APS) (D[4.3]) of 123 μm, a dioctyl phthalate absorption (CPA) of 22.2% at 25° C. measured in accordance with ASTM D3367, and a bulk density (BD) of 0.57 g/cm ³ measured in accordance with ASTM D1895-90. In addition, the degree of polymerization (DP) measured in accordance with JIS K 6720-2 was 700.

<Preparation of Chlorinated Polyvinyl Chloride Resin Composition>

Example 1-1

Chlorination reaction steps

The suspension prepared in Preparation Example 1 (in which 741 g of a vinyl chloride-based polymer was dispersed in 2964 g of deionized water (solid content was 20% by weight based on the total weight of the suspension)) and 0.37 g of a 20% (w/w) aqueous solution of sodium polystyrene sulfonate were introduced into a reactor and stirred to prepare a PVC suspension. At this time, the amount of sodium polystyrene sulfonate used was 100 ppm based on the total weight of the vinyl chloride-based polymer.

Subsequently, the temperature in the reactor was raised to 70°C by heating the reactor, and then nitrogen was blown into the reactor to remove oxygen in the reactor. Next, chlorine gas at a pressure of 2.0 kgf/ ^cm2 was introduced into the deoxygenated reactor, and the reactor temperature was raised to 70°C again while irradiating UV to initiate a chlorination reaction by photoreaction for 180 minutes. Then, the chlorine gas pressure and temperature were maintained to carry out the reaction.

When the chlorine gas is completely introduced and the pressure in the reactor decreases due to the consumption of chlorine gas, the reaction is terminated to obtain a chlorinated polyvinyl chloride resin (CPVC) in a slurry state (chlorine content in the CPVC: 67.3 wt % based on the total weight of the CPVC).

Neutralization reaction step

To the CPVC slurry after the chlorination reaction was completed, a mixture of sodium percarbonate (SPC) as a neutralizing agent and sodium carbonate (SC) as an alkaline compound was introduced in a weight ratio of 50:50 in an amount such that the pH value of the CPVC slurry was 9, and a neutralization reaction was performed at 60° C. The neutralizing agent was introduced with stirring. As a result, a slurry containing a neutralized chlorinated polyvinyl chloride resin was obtained.

Stabilization step

Based on 100 parts by weight of the neutralized chlorinated polyvinyl chloride resin, 0.5 parts by weight of butyltin carboxylate (TM-600P; SONGSTAB ^TM -600P, Songyuan Industry) was added as a heat stabilizer to the slurry containing the neutralized chlorinated polyvinyl chloride resin obtained above, mixed at 60°C, and then dried to obtain a chlorinated polyvinyl chloride resin composition. At this time, the amount of the neutralized chlorinated polyvinyl chloride resin was calculated from the amount of PVC added according to mass balance. Specifically, in this embodiment, 741 g of PVC was added, so that 960 g of neutralized CPVC with a chlorine content of 67.3% was synthesized. Therefore, 4.8 g of heat stabilizer was added.

Examples 1-2 to 1-6

The preparation methods of the chlorinated polyvinyl chloride resin compositions are the same as those of Example 1-1, except that the type of PVC used as the base resin and the type and amount of the heat stabilizer are changed, as shown in Table 1 below.

Comparative Example 1-1

The preparation method of the chlorinated polyvinyl chloride resin composition is the same as that of Example 1-1, except that the PVC prepared in Preparation Example 1 is used and no heat stabilizer is added, as shown in Table 1 below.

Comparative Example 1-2

The preparation method of the chlorinated polyvinyl chloride resin composition is the same as that of Example 1-1, except that the PVC prepared in Preparation Example 2 is used and no heat stabilizer is added, as shown in Table 1 below.

Comparative Examples 1-3

The preparation method of the chlorinated polyvinyl chloride resin composition is the same as that of Example 1-1, except that the type of thermal stabilizer is changed, as shown in Table 1 below.

【Table 1】

The amount of the heat stabilizer in Table 1 is a relative weight value based on 100 parts by weight of the neutralized chlorinated polyvinyl chloride resin.

In addition, the abbreviations in Table 1 are as follows:

TM-600P: Butyltin carboxylate (SONGSTAB ^TM TM-600P, Songyuan Industry)

MT-800: Methyltin mercaptan (SONGSTAB ^TM MT-800, Songyuan Industry)

E-700: ESBO (epoxidized soybean oil) (SONGSTAB ^TM E-700, Songwon Industries)

<Preparation of Chlorinated Polyvinyl Chloride Resin Compound>

Example 2-1

Based on 100 parts by weight of the chlorinated polyvinyl chloride resin composition prepared in Example 1-1, 2.5 parts by weight of methyltin mercaptan (SONGSTAB ^™ MT-800, Songwon Industrial) as a heat stabilizer, 7.5 parts by weight of MBS (MB-838A ^™ , LG Chemical) as an impact modifier, 2 parts by weight of a paraffin lubricant (C-wax ^™ , SunKyung Chemical), 2.5 parts by weight of a polyester-based processing aid (Paraloid ^™ K-175, Dow) and 2.5 parts by weight of titanium dioxide as a filler were added, and the mixture was stirred and dry-mixed to prepare a chlorinated polyvinyl chloride resin compound.

Examples 2-2 to 2-6

The preparation methods of the chlorinated polyvinyl chloride resin mixes are the same as those of Example 2-1, except that the chlorinated polyvinyl chloride resin compositions prepared in Examples 1-2 to 1-6 are used instead of the chlorinated polyvinyl chloride resin composition prepared in Example 1-1.

Comparative Examples 2-1 to 2-3

The preparation methods of the chlorinated polyvinyl chloride resin compounds are the same as those of Example 2-1, except that the chlorinated polyvinyl chloride resin compositions prepared in Comparative Examples 1-1 to 1-3 are used instead of the chlorinated polyvinyl chloride resin composition prepared in Example 1-1.

Comparative Examples 2-4

Based on 100 parts by weight of the chlorinated polyvinyl chloride resin composition prepared in Comparative Example 1-1, 1.0 parts by weight of butyltin mercaptan (TM-600P; SONGSTAB ^™ TM-600P, Songwon Industrial) and 2.5 parts by weight of methyltin mercaptan (SONGSTAB ^™ MT-800, Songwon Industrial) as a heat stabilizer, 7.5 parts by weight of MBS (MB-838A ^™ , LG Chemical) as an impact modifier, 2 parts by weight of a paraffin lubricant (C-wax ^™ , SunKyung Chemical), 2.5 parts by weight of a polyester-based processing aid (Paraloid ^™ K-175, Dow) and 2.5 parts by weight of titanium dioxide as a filler were added and dry-mixed with stirring to prepare a chlorinated polyvinyl chloride resin compound.

Experimental Example 1: Comparison of the effect of introducing thermal stabilizer

In order to compare the effect of introducing a heat stabilizer when preparing a chlorinated polyvinyl chloride resin composition, the processing color and static thermal stability of the chlorinated polyvinyl chloride-based rubber compounds of Example 2-2, in which a heat stabilizer was introduced after the CPVC neutralization process, and Comparative Examples 2-1 and 2-4, in which no heat stabilizer was introduced when preparing the chlorinated polyvinyl chloride resin composition but a heat stabilizer was introduced only during processing and blending and dry blending were performed, were evaluated during processing. The results are shown in Table 2 below.

1) Processing color (whiteness index)

The mixed rubbers of the examples and comparative examples were pressed at a temperature of 160°C to 200°C to prepare samples with a thickness of 3 mm, and then the whiteness index (WI) was measured using a colorimeter. The higher the whiteness index value, the better the processed color.

2) Static thermal stability

The rubber mixtures of the examples and comparative examples were rolled at 160°C to 200°C to prepare samples with a thickness of 1 mm, and the time until the samples were carbonized in a Mathis oven was measured at 190°C to 195°C. The longer the time until carbonization, the better the static thermal stability. In this experimental example, when the static thermal stability was 105 minutes or more, it was evaluated as very excellent.

【Table 2】

In Table 2, the amount of the heat stabilizer used in preparing the chlorinated polyvinyl chloride resin composition is a relative weight value based on 100 parts by weight of the neutralized chlorinated polyvinyl chloride resin.

The experimental results show that under the condition of adding the heat stabilizer in equal amounts during processing and blending, the rubber compound of Example 2-2 shows better effects in processing color and static thermal stability compared with Comparative Example 2-4. In Example 2-2, the heat stabilizer TM-600P is added to the slurry after the CPVC is neutralized, and in Comparative Example 2-4, the heat stabilizer TM-600P is added in equal amounts during processing and blending, which is the same as the heat stabilizer added to the slurry after neutralization in Example 2-2. This difference is because the heat stabilizer is more evenly dispersed in the slurry compared with the case where the heat stabilizer is added during processing and blending to be dry-mixed with the CPVC, and can therefore be evenly mixed with the CPVC.

Experimental Example 2: Comparison of the effects of different types of thermal stabilizers

In order to compare the effects of different types of heat stabilizers used in preparing chlorinated polyvinyl chloride resin compositions, the chlorinated polyvinyl chloride rubber compounds of Examples 2-1, 2-3 and Comparative Examples 2-1, 2-3 prepared under the same conditions of base resin type, heat stabilizer dosage, and addition method were evaluated for processing color and static thermal stability in the same manner as in Experimental Example 2. The results are shown in Table 3 below.

【Table 3】

The amount of the heat stabilizer used in Table 3 is a relative weight value based on 100 parts by weight of the neutralized chlorinated polyvinyl chloride resin.

The experimental results show that when butyltin carboxylate (TM-600P) is introduced as a heat stabilizer in the preparation of chlorinated polyvinyl chloride resin composition, better effects are shown in terms of processing color and static thermal stability.

Experimental Example 3: Comparison of the effect of heat stabilizer dosage

In order to compare the effect of the amount of heat stabilizer, except for the different amounts of heat stabilizer, the chlorinated polyvinyl chloride rubber compounds of Examples 2-1, 2-2, 2-4 and 2-5 prepared under the same conditions of base resin type, heat stabilizer amount and feeding method were evaluated for processing color and static thermal stability in the same manner as Experimental Example 2. The results are shown in Table 4 below. In order to compare the effects, the experimental results of the chlorinated polyvinyl chloride rubber compound of Comparative Example 2-1 are also shown.

【Table 4】

In Table 4, the usage amount of the heat stabilizer is a relative weight value based on 100 parts by weight of the neutralized chlorinated polyvinyl chloride resin.

The experimental results show that when preparing a chlorinated polyvinyl chloride resin composition, as the amount of heat stabilizer increases, the static thermal stability increases, while the processing color, i.e., the whiteness index, decreases. In particular, when the amount exceeds a certain level, the decrease in the whiteness index is very obvious. However, when the amount of heat stabilizer is 1 part by weight based on 100 parts by weight of the neutralized chlorinated polyvinyl chloride resin, excellent effects are shown in terms of both static thermal stability and processing color. These results show that in order to simultaneously improve static thermal stability and processing color, the amount of heat stabilizer must be controlled within an optimal range.

Experimental Example 4: Comparison of the effects of different PVC types

In order to compare the effect of the type of PVC (base resin), the chlorinated polyvinyl chloride rubber compounds of Example 2-2, Example 2-6, Comparative Example 2-1, and Comparative Example 2-2 were evaluated for processing color and static thermal stability in the same manner as in Experimental Example 2. The results are shown in Table 5 below.

【Table 5】

In Table 5, the usage amount of the heat stabilizer is a relative weight value based on 100 parts by weight of the neutralized chlorinated polyvinyl chloride resin.

The experimental results show that compared with Comparative Example 2-1 using PVC of Preparation Example 1 as the base resin, the rubber compound of Comparative Example 2-2 using PVC of Preparation Example 2 as the base resin (which is polymerized using a mixture of the first suspending agent HPMC, the second suspending agent PVA, and the third suspending agent PEO as the suspending agent) is only improved in processing color (whiteness index). In contrast, compared with the rubber compound of Comparative Example 2-2, the rubber compound of Example 2-6 using PVC of Preparation Example 2 as the base resin and adding a heat stabilizer to the slurry after neutralization shows improved effects in both static thermal stability and processing color.

Claims (22)

1. A method for preparing a chlorinated polyvinyl chloride resin composition, the method comprising the following steps: preparing a slurry containing a chlorinated polyvinyl chloride resin by introducing chlorine gas into a suspension in which a vinyl chloride-based polymer is dispersed in an aqueous solvent and performing a chlorination reaction; preparing a slurry containing a neutralized chlorinated polyvinyl chloride resin by introducing a neutralizing agent into the slurry containing the chlorinated polyvinyl chloride resin and performing a neutralization reaction; and introducing a heat stabilizer into a slurry containing the neutralized chlorinated polyvinyl chloride resin and mixing, Wherein, the heat stabilizer includes alkyl tin carboxylate, alkyl tin mercaptan or a mixture thereof. 2. The method according to claim 1, wherein the heat stabilizer comprises methyl tin carboxylate, butyl tin carboxylate, octyl tin carboxylate, methyl tin mercaptan, butyl tin mercaptan, octyl tin mercaptan, or a mixture thereof. 3. The method according to claim 1, wherein the heat stabilizer comprises butyltin carboxylate, methyltin mercaptan, or a mixture thereof. 4 . The method according to claim 1 , wherein the thermal stabilizer is used in an amount of 0.3 to 3 parts by weight based on 100 parts by weight of the neutralized chlorinated polyvinyl chloride resin. 5 . The method of claim 1 , wherein the vinyl chloride-based polymer is prepared by suspension polymerization of a vinyl chloride-based monomer in the presence of a reaction initiator and a suspending agent. 6. The method according to claim 5, wherein the suspending agent comprises a polyvinyl alcohol-based polymer, a hydroxypropylmethylcellulose-based polymer, a polyethylene oxide-based polymer, or a mixture thereof. 7. The method according to claim 5, wherein the suspending agent is a mixture comprising a polyvinyl alcohol-based polymer having a saponification degree of 78 mol% to 90 mol% as a first suspending agent; a polyvinyl alcohol-based polymer having a saponification degree of 70 mol% or more and less than 78 mol% as a second suspending agent; and a polyvinyl alcohol-based polymer having a saponification degree of 20 mol% or more and less than 70 mol% as a third suspending agent. 8. The method according to claim 5, wherein the suspending agent is a mixture comprising a hydroxypropylmethylcellulose-based polymer having a methoxyl substitution degree of 1.2 to 1.9 and a hydroxypropoxyl substitution degree of 0.15 to 0.25 as a first suspending agent; a polyvinyl alcohol-based polymer having a saponification degree of 20 mol% to 60 mol% as a second suspending agent; and a polyethylene oxide-based polymer having a weight average molecular weight of 4,000,000 g/mol to 5,000,000 g/mol as a third suspending agent. 9. The method according to claim 1, wherein the vinyl chloride-based polymer satisfies the following requirements (a1) to (a4): (a1) average particle size D[4,3] measured by laser diffraction analysis: 110 μm to 200 μm; (a2) dioctyl phthalate absorption measured at 25°C according to ASTM D3367: 15% to 37%; (a3) Bulk density measured according to ASTM D1895-90: 0.53 g/cm ³ to 0.60 g/cm ³ ; (a4) Degree of polymerization measured according to JIS K 6720-2: 500 to 1,300. 10. The method according to claim 1, wherein the chlorination reaction is carried out in the presence of polystyrene sulfonic acid or an alkali metal salt thereof. 11 . The method according to claim 10 , wherein the polystyrene sulfonic acid or the alkali metal salt thereof is introduced in an amount of 50 ppm to 1000 ppm based on the weight of the vinyl chloride-based polymer. 12. The method according to claim 1, wherein the chlorination reaction is performed at a chlorine gas pressure of ^1.5 to 3.0 kgf/ ^cm2 and a temperature of 60 to 95°C. 13. The method of claim 1, wherein the chlorination reaction is initiated by ultraviolet irradiation. 14. The method according to claim 1, wherein the chlorination reaction is performed so that the chlorine content in the chlorinated polyvinyl chloride resin is 63 wt% to 70 wt% based on the total weight of the chlorinated polyvinyl chloride resin. 15. The method of claim 1, wherein the neutralizing agent comprises a percarbonate-based compound; or a mixture of a carbonate-based compound and hydrogen peroxide. 16. The method according to claim 15, wherein the percarbonate-based compound is one or more selected from sodium percarbonate, potassium percarbonate and calcium percarbonate. 17. The method according to claim 15, wherein the carbonate-based compound is one or more selected from the group consisting of sodium carbonate, sodium bicarbonate, potassium carbonate, potassium bicarbonate and calcium carbonate. 18. The method of claim 1, wherein the neutralizing agent comprises a percarbonate-based compound and further comprises one or more alkaline compounds selected from the group consisting of sodium carbonate, sodium bicarbonate and potassium bicarbonate. 19. A chlorinated polyvinyl chloride resin composition prepared according to the preparation method according to any one of claims 1 to 18. 20. A chlorinated polyvinyl chloride resin compound, comprising the chlorinated polyvinyl chloride resin composition according to claim 19; and One or more additives selected from impact modifiers, heat stabilizers, fillers, processing aids, pigments and lubricants. 21. The chlorinated polyvinyl chloride resin mix according to claim 20, wherein, based on 100 parts by weight of the chlorinated polyvinyl chloride resin composition, the chlorinated polyvinyl chloride resin mix comprises 1 to 10 parts by weight of the impact modifier, 1 to 5 parts by weight of the heat stabilizer, 1 to 5 parts by weight of the lubricant, 1 to 5 parts by weight of the processing aid and 1 to 5 parts by weight of the filler. 22. The chlorinated polyvinyl chloride resin mix according to claim 20, wherein the chlorinated polyvinyl chloride resin mix has a static thermal stability of more than 105 minutes and a whiteness index of more than 5, wherein the static thermal stability is determined by measuring the time until carbonization at a temperature of 190° C. to 195° C. for a sample having a thickness of 1 mm, and the whiteness index is measured on a sample having a thickness of 3 mm.