KR20180028770A - Method for preparing polyvinylchloride - Google Patents

Abstract

The present invention relates to a method for polymerizing a vinyl chloride monomer in the presence of a polyhydric alcohol (meth) acrylate compound and an initiator, And a second step of adding a nitroxide-based compound to the vinyl chloride-based polymer when the polymerization has progressed from 70% to 90%, and a second step of producing the vinyl chloride-based polymer.

Description

METHOD FOR PREPARING POLYVINYLCHLORIDE [0002]

TECHNICAL FIELD The present invention relates to a process for producing a vinyl chloride polymer, and more particularly, to a process for producing a vinyl chloride polymer using a (meth) acrylic acid ester compound of a polyhydric alcohol and a nitrile compound.

The vinyl chloride polymer is the most widely used synthetic resin among the thermoplastic resins. The vinyl chloride monomer used as a raw material for the production of the vinyl chloride polymer is polymerized in a batch reactor. As the reaction initiator, an organic peroxide, which is an explosive substance, is used. As the additive, a dispersant (emulsifier) and an antioxidant are used.

Examples of the polymerization method of the vinyl chloride polymer include a suspension polymerization method, an emulsion polymerization method and a bulk polymerization method. The suspension polymerization method and the emulsion polymerization method are a method in which a vinyl chloride monomer is suspended (emulsified) in water and then reacted with an initiator, whereas the bulk polymerization method is a method in which a vinyl chloride monomer and an initiator are reacted directly without using water and a dispersant .

The suspension polymerization method has a high conversion ratio to a vinyl chloride polymer and low operation cost. It is easy to recover unreacted vinyl chloride monomer after the polymerization process, and the scale system in the reactor is small due to the coating system, . At present, the suspension polymerization method has significant advantages in mass production trend.

On the other hand, when a vinyl chloride polymer is produced by a suspension polymerization method, use of a crosslinking agent enables polymerization at a temperature higher than the conventional polymerization temperature while maintaining a specific molecular weight characteristic, and ultimately, productivity improvement effect can be expected. However, in the case of a vinyl chloride polymer having a high degree of polymerization with a crosslinking agent, the gel content increases as the amount of the crosslinking agent is increased. As a result, mechanical properties such as fish eye, impact strength and tensile strength decrease Lt; / RTI > Particularly, in the measurement of the tensile strength, the gel in the vinyl chloride polymer acts as a weak point. Therefore, even if the amount of the crosslinking agent is increased during the production of the vinyl chloride polymer, the study of maintaining the mechanical properties at the level equivalent to the vinyl chloride polymer prepared without the crosslinking agent continues It is progressing.

KR2009-0114916A

An object of the present invention is to provide a method for producing a vinyl chloride-based polymer capable of improving the mechanical properties while realizing a high degree of polymerization of a vinyl chloride-based polymer.

Another object of the present invention is to provide a process for producing a vinyl chloride polymer capable of shortening the reaction time and improving productivity.

In order to solve the above-mentioned problems, the present invention provides a process for producing a vinyl chloride-based copolymer, comprising the steps of: (1) polymerizing a vinyl chloride monomer in the presence of a polyhydric alcohol (meth) acrylate compound and an initiator; And a second step of adding a nitroxide-based compound to the vinyl chloride-based polymer when the polymerization has progressed to 70% to 90%.

By using the method for producing a vinyl chloride polymer of the present invention, it is possible to provide a vinyl chloride polymer improved in mechanical properties while realizing a high polymerization degree.

Further, the process for producing a vinyl chloride-based polymer of the present invention enables polymerization to proceed at a relatively high temperature, shortening the polymerization time, thereby improving productivity.

Hereinafter, the present invention will be described in detail in order to facilitate understanding.

The terms and words used in the present specification and claims should not be construed as limited to ordinary or dictionary terms and the inventor may appropriately define the concept of the term in order to best describe its invention It should be construed as meaning and concept consistent with the technical idea of the present invention.

The method for producing a vinyl chloride polymer according to the first embodiment of the present invention may include a first step of polymerizing a vinyl chloride monomer in the presence of a polyhydric alcohol (meth) acrylate compound and an initiator.

The first step includes a step (1-1) of adding a dispersant, a (meth) acrylic acid ester compound of the polyhydric alcohol and the initiator to water and stirring to form a first mixture; And a second step of polymerizing the vinyl chloride monomer in the presence of the first mixture.

If the first mixture is formed in advance before the initiation of the polymerization, the vinyl chloride polymer having excellent polymerization conversion rate and high polymerization degree can be produced. If the (meth) acrylic acid ester compound of a polyhydric alcohol is added after the initiation of the polymerization without previously forming the first mixture, it is difficult to control the degree of polymerization and the desired degree of polymerization of the vinyl chloride polymer as the final product can not be realized.

The water may be deionized water or pure water.

The dispersant is used for easily dispersing the vinyl chloride monomer. The dispersant may be selected from the group consisting of polyvinyl alcohol, polyacrylic acid, a copolymer of vinyl acetate and maleic anhydride, But are not limited to, hydroxypropyl methylcellulose, gelatin, calcium phosphate, hydroxyapatite, sorbitan monolaurate, sorbitan trioleate, polyoxyethylene, Sodium lauryl sulfate, dodecylbenzene sulfonic acid, sodium salt, and sodium dioctylsulfosuccinate may be used alone or in combination of two or more kinds selected from the group consisting of sodium lauryl sulfate, sodium lauryl sulfate, sodium dodecylbenzene sulfonic acid and sodium dioctylsulfosuccinate. Specifically, the dispersing agent may include a polyvinyl alcohol and a cellulose-based compound having a degree of hydration of 50% to 90%. The polyvinyl alcohol may be at least two selected from the group consisting of polyvinyl alcohols having different degrees of hydration in order to realize excellent stability.

Examples of the (meth) acrylic acid ester compound of the polyhydric alcohol may be one or more kinds selected from the group consisting of the compound described in the following Table 1 and bisphenol A-modified dimethacrylate, and specifically, trimethylolpropane Triacrylate.

Name of compound rescue One Ethylene glycol diacrylate
(Ethylene glycol diacrylate)

2 Trimethylolpropane triacrylate
(Trimethylolpropane triacrylate)

3 Ethylene glycol dimethacrylate
(Ethylene glycol dimethacrylate)

The initiator may be an organic peroxide such as dicumyl peroxide, dipentyl peroxide, di (3,5,5-trimethylhexanoyl) peroxide, diacyl peroxides such as peroxide and dilauroyl peroxide; Diisopropyl peroxydicarbonate, di-sec-butyl peroxydicarbonate, di (2-ethylhexyl) peroxydicarbonate, etc. Peroxycarbonates; t-butylperoxy neodecanoate, t-butylperoxy neoheptanoate, t-amyl peroxy neodecanoate, cumyl peroxyneodecanoate, t-butylperoxy neodecanoate, But are not limited to, cumyl peroxy neodecanoate, cumyl peroxy neoheptanoate, 1,1,3,3-tetramethyl butyl peroxyneodecanoate (1,1,3,3 -tetramethylbutyl peroxy neodecanoate); Azo compounds such as azobis-2,4-dimethylvaleronitrile; Sodium persulfate, potassium persulfate, ammonium persulfate and the like, or a combination of two or more thereof.

The vinyl chloride monomer may be a pure vinyl chloride monomer, and may be a mixed monomer comprising a pure vinyl chloride monomer as a main component and a vinyl monomer capable of copolymerizing with the pure vinyl chloride monomer. The mixed monomer may include 1 to 50 parts by weight of the vinyl monomer based on 100 parts by weight of the vinyl chloride monomer. When the above-mentioned range is satisfied, suspension polymerization is stably carried out, and further, the processability of the obtained vinyl chloride polymer is stabilized. The vinyl monomer may be an olefin compound such as ethylene or propylene; Vinyl esters such as vinyl acetate and vinyl propionate; Unsaturated nitrile type such as acrylonitrile; Vinyl alkyl ethers such as vinyl methyl ether and vinyl ethyl ether; Unsaturated fatty acids such as acrylic acid, methacrylic acid, itaconic acid and maleic acid; And anhydrides of these fatty acids may be used alone or in combination of two or more.

On the other hand, the (meth) acrylic acid ester compound of the polyhydric alcohol has a high degree of polymerization degree-enhancing effect in the crosslinking agent, and thus has excellent crosslinking efficiency. However, when the crosslinking ratio in the molecule is high, there is a problem that the gel content is high and the mechanical properties of the vinyl chloride polymer as a final product are lowered. As a result, the (meth) acrylic acid ester compound of the polyhydric alcohol has not been widely used despite its high crosslinking efficiency. However, if the (meth) acrylic acid ester compound of the polyhydric alcohol is used in a method for producing a vinyl chloride polymer together with a nitroxide-based compound to be described later, mechanical properties such as tensile strength can be improved while realizing a high degree of polymerization .

The initiator may be included in an amount of 0.01 to 0.3 parts by weight, specifically 0.05 to 0.20 parts by weight, more specifically 0.05 to 0.15 parts by weight, based on 100 parts by weight of the vinyl chloride monomer. When the above-mentioned range is satisfied, the stability of the polymerization process is excellent.

The polymerization may be carried out in suspension at 48 to 62 ° C, specifically at 50 to 60 ° C, and may be controlled depending on the content of the have.

The method for producing a vinyl chloride polymer according to the first embodiment of the present invention includes a second step of preparing a vinyl chloride polymer by adding a nitroxide compound when the polymerization proceeds from 70% to 90% can do.

Examples of the nitroxide-based compound may be one or two or more selected from the group consisting of the compounds shown in the following Table 2, specifically, 4-hydroxy-2,2,6,6-tetramethyl- Piperidin-1-oxyl.

Name of compound The One Tasheri - Amil - Tasheri - Butyl
(tert-Amyl-tert-butyl nitroxide)

2 Di-tertiary-butylnitroxide
(Di-tert-butyl nitroxide)

3 2-phenyl-4,4,5,5-tetramethylimidazolidine 1-oxyl
(2-phenyl-4,4,5,5-tetramethylimidazolidine 1-oxyl)

4 2-phenyl-4,4,5,5-tetramethylimidazolidine 3-oxide 1-oxyl
(2-phenyl-4,4,5,5-tetramethylimidazolidine 3-oxide 1-oxyl)

5 2,2,5,5-tetra-methyl-3-imidazoline-3-oxide-1-oxyl
(2,2,5,5-tetra-methyl-3-imidazoline-3-oxide-1-oxyl)

6 2-phenyl-5, 5-dimethyl-l-pyrroline N-oxide
(2-phenyl-5,5-dimethyl-1-pyrroline N-oxide)

7 3-Carbamoyl-2,2,5,5-tetramethyl-3-pyrrolin-l-oxyl
(3-Carbamoyl-2,2,5,5-tetramethyl-3-pyrrolin-1-oxyl)

8 Hydroxy-2,2,6,6-tetramethyl piperidine 1-oxyl (4-hydroxy-2,2,6,6-tetramethyl piperidine-

9 4-Amino-4-carboxy-2,2,6,6-tetramethylpiperidine 1-oxyl
(4-Amino-4-carboxy-2,2,6,6-tetramethylpiperidine 1-oxyl)

10 4-Acetamido-2,2,6,6-tetramethylpiperidine 1-oxyl
(4-Acetamido-2,2,6,6-tetramethylpiperidine 1-oxyl)

11 4-hydroxy-2,2,6,6-tetramethylpiperidine 1-oxylbenzoate
(4-Hydroxy-2,2,6,6-tetramethylpiperidine 1-oxyl benzoate)

On the other hand, the (meth) acrylic acid ester compound of the polyhydric alcohol may be contained in an amount of 0.01 to 0.17 part by weight and the nitroside compound may be contained in an amount of 0.04 to 0.06 part by weight based on 100 parts by weight of the vinyl chloride monomer, And 0.10 to 0.15 parts by weight of the (meth) acrylic acid ester compound of the polyhydric alcohol. When the above-mentioned range is satisfied, it is possible to provide a vinyl chloride-based polymer having improved mechanical properties such as tensile strength while realizing a high polymerization degree. If the above range is not satisfied, specifically, when the (meth) acrylate ester compound and the nitroxide compound of the polyhydric alcohol exceed the above-mentioned range, the effect of improving the mechanical properties is not realized at all, Can be lowered.

In the second step, an additive such as an antioxidant may be added as needed. The antioxidant may be added for the purpose of making the color of the vinyl chloride polymer white.

The method for producing a vinyl chloride polymer according to the first embodiment of the present invention comprises the steps of: stripping the polymer slurry after the second step, dewatering the stripped polymer slurry, and removing the dehydrated polymer slurry And drying it.

The step of stripping is a step of separating unreacted vinyl chloride monomer from the polymer slurry, and the separated unreacted vinyl chloride monomer may be reused in the reaction.

The dewatering step separates water from the stripped polymer slurry, wherein the water can be separated using a centrifuge.

The drying step may be performed using a fluidized bed dryer which is fluidized by hot air.

On the other hand, the vinyl chloride polymer produced according to the first embodiment of the present invention contains a functional group derived from a (meth) acrylic acid ester compound of a polyhydric alcohol and has a number average degree of polymerization of 1,000 to 1,800, To 200, in particular from 150 to 190 mu m, and the particle size distribution can be from 0.50 to 0.80.

The number average degree of polymerization refers to the average number of repeating units in the polymer chain and can be calculated from the ratio of the number average molecular weight to the molecular weight of the repeating unit. Specifically, it can be measured in accordance with ASTM D1243.

The average particle size and the particle size distribution are measured from the magnitude of the angle of light that rotates according to the particle size when a powder as a sample unit passes through a cell And may be an average particle size and a particle size distribution value.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the present invention as defined by the appended claims. Such variations and modifications are intended to be within the scope of the appended claims.

Example  1 and Example  2, Comparative Example  1 to Comparative Example  5: Vinyl chloride series  Preparation of polymer

1 m < 3 >, a stirrer located in the polymerization reactor, a reflux condenser connected to the polymerization reactor and for releasing the temperature of the polymerization reaction, and a vinyl chloride recovery unit connected to the reflux condenser and discharging the unreacted vinyl chloride monomer The vinyl chloride monomer was polymerized by the following method using a polymerization apparatus including a pipe.

First, 0.03 part by weight of polyvinyl alcohol (degree of hydration: 88%), 0.03 part by weight of polyvinyl alcohol (degree of hydration: 72%), polyvinyl alcohol (degree of hydration: 55 %) And 0.005 parts by weight of hydroxypropylmethylcellulose were added thereto. Then, 0.088 parts by weight of t-butyl peroxyneodecarbonate as a crosslinking agent and an initiator shown in Table 3 below were added and stirred, and then the interior of the polymerization reactor was degassed with a vacuum pump. Subsequently, 100 parts by weight of a vinyl chloride monomer was added. Polymerization was carried out while maintaining the internal temperature of the polymerization reactor at 58 占 폚. The polymerization was stopped when the inner pressure of the polymerization reactor had a change of 1.2 kg / cm 2 from the start of polymerization, and the additives described in the following Table 3 were added. Thereafter, unreacted monomers were recovered and the reaction was terminated to obtain a first polymer slurry. Then, the first polymer slurry was recovered, subjected to a stripping process and a dehydration process to separate the unreacted vinyl chloride monomer and water to obtain a second polymer slurry. The second polymer slurry was hot-air dried at 60 ° C in a fluidized bed drier, and a vinyl chloride polymer in powder form was obtained through a screening facility.

division Cross-linking agent additive Kinds content Kinds content Example 1 TMPTA 0.15 parts by weight 4-H-TEMPO 0.05 part by weight Example 2 TMPTA 0.10 parts by weight 4-H-TEMPO 0.05 part by weight Comparative Example 1 DAP 0.15 parts by weight 4-H-TEMPO 0.05 part by weight Comparative Example 2 TMPTA 0.20 parts by weight 4-H-TEMPO 0.05 part by weight Comparative Example 3 DAP 0.15 parts by weight TGP 0.05 part by weight Comparative Example 4 TMPTA 0.15 parts by weight TGP 0.05 part by weight Comparative Example 5 - - 4-H-TEMPO 0.05 part by weight

※ TMPTA: trimethylolpropane triacrylate

)DAP: diallyl phthalate (chemical formula:

)

4-H-TEMPO: 4-Hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl

)TGP: Triethylene glycol-bis-3- (3-t-butyl-4-hydroxy-5-methylphenyl) propionate

)

Test Example  One: Vinyl chloride series  Characterization of polymers

The tensile strength, strain and degree of polymerization of the vinyl chloride type polymers of Examples 1 and 2 and Comparative Examples 1 to 5 were measured and shown in Table 4.

One) Tensile strength (MPa): Measured according to ASTM D638

2) Strain (%): Measured at a tensile speed of 50 mm / min using a UTM (Universal Testing Machine, Lloyd, product name: LR10KInstron, USA)

3) Polymerization degree: Measured according to ASTM D1243

Tensile strength (MPa) Strain (%) Degree of polymerization Example 1 21.7 753 1,355 Example 2 20.6 722 1,285 Comparative Example 1 20.2 716 1,280 Comparative Example 2 18.3 620 1,400 Comparative Example 3 18.1 666 1,290 Comparative Example 4 16.6 586 1,350 Comparative Example 5 17.5 608 1,005

Referring to Table 4, it was found that the vinyl chloride type polymers of Examples 1 and 2 according to the present invention had excellent tensile strength, strain and degree of polymerization. It was found that the vinyl chloride type polymer of Comparative Example 1 had lower properties than the vinyl chloride type polymers of Examples 1 and 2 in all respects. In the case of Comparative Example 2, the amount of trimethylolpropane triacrylate was only about 1.3 times and 2 times that of Example 1 and Example 2, and the tensile strength and the strain were greatly decreased. As a result, it was found that the content of trimethylolpropane triacrylate plays a large role in the tensile strength and strain rate. In the case of Comparative Example 3 and Comparative Example 4 in which 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl was not used, the tensile strength and strain rate were also significantly lowered. In addition, in Comparative Example 5 in which no cross-linking agent was used, the tensile strength, the strain rate, and the degree of polymerization, that is, the characteristics were significantly lowered in all aspects.

On the other hand, in the case of the vinyl chloride polymer, it is considerably difficult to improve the tensile strength by more than 1 MPa. However, due to the synergistic effect of the poly (meth) acrylate ester compound and the nitroxide compound, The effect of increasing the tensile strength by 1.5 MPa was obtained as compared with the use of the same amount of other crosslinking agent.

Claims (10)

A first step of polymerizing a vinyl chloride monomer in the presence of a polyhydric alcohol (meth) acrylate compound and an initiator; And
And a second step of adding a nitroxide-based compound to the vinyl chloride-based polymer when the polymerization has progressed to 70% to 90%.
The method according to claim 1,
The first step includes a step (1-1) of adding a dispersant, a (meth) acrylic acid ester compound of the polyhydric alcohol and the initiator to water and stirring to form a first mixture; And
And a second step of polymerizing the vinyl chloride monomer in the presence of the first mixture.
The method of claim 2,
Wherein the dispersing agent comprises a polyvinyl alcohol and a cellulose-based compound having a degree of hydration of 50% to 90%.
The method of claim 3,
Wherein the polyvinyl alcohol comprises two or more polyvinyl alcohols having different degrees of hydration.
The method according to claim 1,
The (meth) acrylic acid ester compound of the polyhydric alcohol may be one or two kinds selected from the group consisting of ethylene glycol diacrylate, trimethylolpropane triacrylate, ethylene glycol dimethacrylate and bisphenol A-modified dimethacrylate By weight based on the total weight of the vinyl chloride polymer.
The method according to claim 1,
Wherein the polymerization is a suspension polymerization.
The method according to claim 1,
The nitroxide-based compound may be selected from the group consisting of tertiary amyl-tertiary-butyl, di-tertiary-butyl nitroxide, 2-phenyl-4,4,5,5-tetramethylimidazolidin- -Phenyl-4,4,5,5-tetramethylimidazolidine 3-oxide 1-oxyl, 2,2,5,5-tetramethyl-3-imidazoline- 2-phenyl-5,5-dimethyl-1-pyrroline N-oxide, 3-carbamoyl-2,2,5,5-tetramethyl- , 2,6,6-tetramethyl-piperidine-1-oxyl, 4-amino-4-carboxy-2,2,6,6-tetramethylpiperidine 1-oxyl, , 2,6,6-tetramethylpiperidine 1-oxyl, and 4-hydroxy-2,2,6,6-tetramethylpiperidine 1-oxylbenzoate. A method for producing a vinyl chloride polymer.
The method according to claim 1,
Based on 100 parts by weight of the vinyl chloride monomer,
0.08 to 0.17 part by weight of the (meth) acrylic acid ester compound of the polyhydric alcohol; And
And 0.04 to 0.06 part by weight of the nitroxide-based compound.
The method of claim 8,
Based on 100 parts by weight of the vinyl chloride monomer,
And 0.10 to 0.15 parts by weight of the (meth) acrylic acid ester compound of the polyhydric alcohol.
The method according to claim 1,
Wherein the polymerization degree of the vinyl chloride polymer is 1,000 to 1,800.