WO2025146113A1 - Preparation method for vinyl chloride-series copolymer, and vinyl chloride-series copolymer latex, paste resin, liquid composition and solid composition - Google Patents

Abstract

The present invention relates to a preparation method for a vinyl chloride-series copolymer, and a vinyl chloride-series copolymer latex, paste resin, liquid composition and solid composition. The preparation method for the vinyl chloride-series copolymer comprises: in an aqueous medium which does not contain a surfactant, performing emulsion polymerization on vinyl chloride A, a copolymerization monomer B and a functional monomer C in the presence of a polymerization initiator under stirring, wherein per molecule of the functional monomer C contains one free radical polymerizable group and two functional groups which are selected from an amide group, a carboxyl group and a carboxylate group and which are not an amide group or a carboxyl group at the same time, and the mass ratio of the copolymerization monomer B to the functional monomer C is 1/12-12/1. The vinyl chloride-series copolymer latex of the present invention does not contain a surfactant; and the vinyl chloride-series copolymer constituting the latex has a vinyl chloride A-based unit, a copolymerization monomer B-based unit and a functional monomer C-based unit.

Description

Preparation method of vinyl chloride copolymer, vinyl chloride copolymer latex, paste resin, liquid composition, solid composition Technical Field

The invention relates to a preparation method of a vinyl chloride copolymer, a vinyl chloride copolymer latex, a paste resin, a liquid composition and a solid composition.

Background Art

Vinyl chloride is a byproduct of the chlor-alkali industry. It is low-cost and an important raw material for plastics chemical industry. The solid product of polyvinyl chloride prepared by emulsion polymerization is called "paste resin", which is one of the important varieties of polyvinyl chloride resin. It has good paste-forming properties and good dispersibility. It is mainly used in soft material products such as artificial leather, floor plastics, wallpaper, impregnated plastics, adhesives, coatings, etc. In addition to polyvinyl chloride homopolymer products, polyvinyl chloride paste resin can also be copolymerized with other monomers to obtain paste resin products of vinyl chloride copolymers.

However, due to the use of emulsifiers in the emulsion polymerization of vinyl chloride and the drying process such as direct spray drying in the post-treatment of the paste resin, usually, small molecule emulsifiers will remain in the paste resin, and this residue has an adverse effect on the water resistance, solvent resistance, adhesion, transparency, etc. of the paste resin product. In addition, although it is possible to try to wash the small molecule emulsifier during post-treatment, since the emulsifier is sometimes wrapped in the surface of the latex particles during polymerization, it is difficult to fundamentally solve the problem of emulsifier residue by washing alone.

Therefore, the art is concerned about how to reduce or eliminate the use of small molecule emulsifiers, and the commonly used strategies are to use macromolecular emulsifiers or implement soap-free emulsion polymerization. Among them, soap-free emulsion polymerization includes soap-free emulsion polymerization with an emulsifier concentration lower than the CMC value and soap-free emulsion polymerization based on reactive emulsifiers. Among them, the former often requires a very low monomer concentration in the emulsion polymerization system, which is not conducive to industrial production. The latter is difficult to achieve in the polymerization involving vinyl chloride, because vinyl chloride itself has a large molecular polarity and a strong electron-withdrawing effect. When copolymerized with other monomers, it tends to homopolymerize itself, and there are fewer monomers that can be polymerized with it (there are fewer hydrophilic monomers that may act as reactive emulsifiers), and the vinyl chloride monomer is in a gaseous state. Therefore, the latex is prone to agglomeration during the polymerization process, resulting in instability of the soap-free emulsion, which is not conducive to industrial production. In addition, this also leads to the fact that even if soap-free emulsion is tried, the emulsion polymerization involving vinyl chloride often cannot be separated from the use of emulsifiers.

For example, Patent Document 1 discloses a method for preparing a hyperbranched aqueous vinyl chloride copolymer emulsion by reacting vinyl chloride, vinyl acetate, a hyperbranched monomer, an initiator, an emulsifier, and a neutralizer in water, wherein the hyperbranched monomer is prepared by reacting pentaerythritol with maleic anhydride or fumaric anhydride. The emulsion prepared by this method can be used to modify polyurethane adhesives and has good adhesion, but an emulsifier must still be used.

For example, Non-Patent Document 1 discloses a method for emulsion copolymerization of vinyl chloride, vinyl acetate, and maleic anhydride, in which a combination of SDS and reactive emulsifier HS-10 is used as an emulsifier.

In addition, in order to expand the application range of the paste resin of the vinyl chloride copolymer, it is sometimes desired that the paste resin has more abundant functional groups. However, for the paste resin of the vinyl chloride copolymer obtained by soap-free emulsion polymerization, there is sometimes a competition between increasing the content of functional groups and retaining the performance achieved by the vinyl chloride monomer as much as possible (i.e., the so-called "original performance of the polyvinyl chloride paste resin").

Prior art literature

Patent Literature

Patent document 1: CN201911282721.9

Non-patent literature

Non-patent document 1: Conversion rate and latex properties of vinyl chloride-vinyl acetate-maleic anhydride emulsion copolymerization, Xiang Hongwen et al., Chemical Reaction Engineering and Technology, Vol. 30, No. 6, December 2014, pp. 522-527.

Summary of the invention

Problem that the invention aims to solve

In view of the above-mentioned problems in the prior art, an object of the present invention is to provide a method for preparing a vinyl chloride copolymer, in which emulsion polymerization is simply achieved without using an emulsifier (whether a macromolecular emulsifier or a small molecule emulsifier), the operation is simple, and the method is suitable for industrial production. The obtained vinyl chloride copolymer can have more functional groups while ensuring the performance based on vinyl chloride monomer (for example, relative to 100% by mass of all structural units, the units based on vinyl chloride can reach 70% by mass or more), and the obtained latex has excellent stability.

The object of the present invention is also to provide a vinyl chloride copolymer latex and a liquid composition based on the latex, wherein the latex does not contain a surfactant, is easy to obtain and has excellent stability, and the vinyl chloride copolymer contained therein can ensure the performance based on vinyl chloride monomer while also having more functional groups.

The present invention also aims to provide a paste resin of a vinyl chloride copolymer and a solid composition based on the paste resin, wherein the paste resin does not contain a surfactant and is easy to obtain, and can have more functional groups while ensuring the performance based on vinyl chloride monomer.

Solutions for solving problems

According to the inventor's intensive research, it is found that the above technical problems can be solved by implementing the following technical solutions:

[1]. A method for preparing a vinyl chloride copolymer, wherein the method comprises:

Vinyl chloride A, comonomer B, and functional monomer C are subjected to emulsion polymerization in an aqueous medium without a surfactant under stirring in the presence of a polymerization initiator.

The functional monomer C has one free radical polymerizable group and two functional groups selected from amide groups, carboxyl groups and carboxylate groups and not being amide groups or carboxyl groups at the same time in one molecule,

The mass ratio of the comonomer B to the functional monomer C, comonomer B/functional monomer C, is 1/12 to 12/1.

[2] The preparation method according to [1], wherein the comonomer B is at least one selected from monofunctional (meth)acrylate monomers, monofunctional (meth)acrylamide monomers, monofunctional vinyl ester monomers, monofunctional vinyl ether monomers, vinyl pyrrolidone monomers, vinyl pyridine monomers and vinyl lactam monomers.

[3] The production method according to [1] or [2], wherein the functional monomer C is a monomer obtained by reacting an acid anhydride monomer and/or a dicarboxylic acid monomer with a basic compound.

[4]. The preparation method according to [3], wherein the alkaline compound is at least one selected from ammonia gas, ammonia water, sodium hydroxide and potassium hydroxide, the acid anhydride monomer is at least one selected from maleic anhydride, itaconic anhydride, citraconic anhydride, dimethylmaleic anhydride, aconitic anhydride and phenylmaleic anhydride, and the dicarboxylic acid monomer is at least one selected from C2 to C20 olefin dicarboxylic acids.

[5]. The preparation method according to any one of [1] to [4], wherein, relative to the total mass of 100 mass % of the vinyl chloride A, the comonomer B and the functional monomer C, the amount of the vinyl chloride A used is 70 mass % or more and 95 mass % or less, the amount of the comonomer B used is greater than 0 mass % and less than 30 mass %, and the amount of the functional monomer C used is greater than 0 mass % and less than 20 mass %.

[6] The preparation method according to any one of [1] to [5], wherein a pH adjuster is further added to the aqueous medium so that the initial pH value of the polymerization system before the start of the emulsion polymerization is greater than 7 and less than 11.

[7]. The preparation method according to any one of [1] to [6], wherein in the emulsion polymerization, the polymerization temperature is 30 to 65°C and the polymerization time is 1 to 72 hours.

[8] A vinyl chloride copolymer latex, wherein the vinyl chloride copolymer latex does not contain a surfactant,

The vinyl chloride copolymer constituting the latex has units based on vinyl chloride A, units based on comonomer B, and units based on functional monomer C.

The functional monomer C has one free radical polymerizable group and two functional groups selected from amide groups, carboxyl groups, and carboxylate groups and not being amide groups at the same time in one molecule.

[9] The vinyl chloride copolymer latex according to [8], wherein the average particle size of the vinyl chloride copolymer particles in the latex is 100 to 350 nm; and in the vinyl chloride copolymer, the mass ratio of the units based on the comonomer B to the units based on the functional monomer C, units based on the comonomer B/units based on the functional monomer C, is 1/20 to 40/1.

[10]. A liquid vinyl chloride copolymer composition, comprising a vinyl chloride copolymer latex obtained by the preparation method described in any one of [1] to [7], or a vinyl chloride copolymer latex described in [8] or [9].

[11]. A paste resin of a vinyl chloride copolymer, wherein the paste resin is obtained by using a vinyl chloride copolymer latex obtained by the production method according to any one of [1] to [7], or by using a vinyl chloride copolymer latex according to [8] or [9].

[12]. A solid composition of a vinyl chloride copolymer, wherein the composition comprises the paste resin according to [10].

Effects of the Invention

The present invention provides a method for preparing a vinyl chloride copolymer, wherein the comonomer B ensures good copolymerizability among three monomers, and the functional monomer C having a specific structure plays a role in stabilizing emulsion polymerization. Therefore, by making the comonomer B and the functional monomer C participate in polymerization in a specific ratio, emulsion polymerization involving vinyl chloride can be achieved without using an emulsifier. In addition, the introduction of the functional monomer C also enables the obtained vinyl chloride copolymer to have more functional groups while ensuring the performance based on the vinyl chloride monomer. Moreover, the preparation method of the present invention is easy to operate, has a low raw material cost, is suitable for industrial production, and has excellent stability of the obtained latex.

The present invention provides a vinyl chloride copolymer latex and a liquid composition based on the latex. The latex does not contain a surfactant, thus avoiding the problems caused by the residue of an emulsifier, and can be easily obtained and has excellent stability. In addition, the vinyl chloride copolymer in the latex has more functional groups while ensuring the performance based on vinyl chloride monomer. In addition, the latex of the present invention can be directly used for purposes such as coatings, adhesives, etc., and can also be used to prepare paste resins.

The present invention provides a paste resin of a vinyl chloride copolymer and a solid composition based on the paste resin. The paste resin does not contain a surfactant, thereby avoiding problems caused by residual emulsifiers and can be easily obtained. In addition, the paste resin has more functional groups while ensuring the performance based on vinyl chloride monomer.

DETAILED DESCRIPTION

Various exemplary embodiments, features and aspects of the present invention will be described in detail below. The word "exemplary" used here means "used as an example, embodiment or illustrative". Any embodiment described here as "exemplary" is not necessarily interpreted as being superior or better than other embodiments.

In addition, in order to better illustrate the present invention, numerous specific details are provided in the following specific embodiments. It should be understood by those skilled in the art that the present invention can be implemented without certain specific details. In other examples, methods, means, equipment and steps well known to those skilled in the art are not described in detail in order to highlight the subject matter of the present invention.

Unless otherwise stated, the units used in this specification are all international standard units, and the numerical values and numerical ranges appearing in the present invention should be understood to include the inevitable systematic errors in industrial production.

In this specification, the numerical range expressed using "a numerical value A to a numerical value B" means a range including the endpoints A and B.

In the present specification, the numerical range expressed using "above" and "below" means a range including the endpoint numerical values.

In the present specification, a numerical range expressed using "greater than" and "less than" means a range excluding the numerical endpoints.

In this specification, unless otherwise specified, "%" means percentage by weight.

In this specification, the word "may" may include both performing a certain process and not performing a certain process, or may include both having a certain component and not having a certain component.

In the present specification, "optional" or "optionally" means that the event or situation described below may or may not occur, and the description includes cases where the event occurs and cases where it does not occur.

In the present specification, "alkyl" or "alkylene" means a linear, branched or cyclic unsubstituted "alkyl" or "alkylene", and "aryl" or "arylene" means an "aryl" or "arylene" having no substituents other than the alkyl group on the aromatic ring (benzene ring, naphthalene ring, etc.).

In the present specification, the "unit" in a polymer refers to a polymerized unit derived from a monomer formed by polymerizing the monomer, and a polymerized unit obtained by converting a part of the polymerized unit into another structure by treating the polymer.

In this specification, when "normal temperature" or "room temperature" is used, the temperature may be 10 to 40°C.

In this specification, the references to "some specific/preferred embodiments", "other specific/preferred embodiments", "embodiments", etc., mean that the specific elements (e.g., features, structures, properties and/or characteristics) described in connection with the embodiment are included in at least one embodiment described herein, and may or may not exist in other embodiments. In addition, it should be understood that the elements may be combined in various embodiments in any suitable manner.

<Method for preparing vinyl chloride copolymer>

The preparation method of the vinyl chloride copolymer of the present invention comprises: subjecting vinyl chloride A, comonomer B and functional monomer C to emulsion polymerization in an aqueous medium without surfactant under stirring in the presence of a polymerization initiator,

The functional monomer C has one free radical polymerizable group and two functional groups selected from amide groups, carboxyl groups, and carboxylate groups and not being amide groups or carboxyl groups at the same time in one molecule,

The mass ratio of the comonomer B to the functional monomer C is 1/15 to 15/1.

In some preferred embodiments, from the viewpoint of better obtaining the desired technical effect of the present invention, the mass ratio of the comonomer B to the functional monomer C is preferably 1/10 to 10/1, more preferably 1/6 to 6/1, and further preferably 1/2 to 4/1.

In the present invention, the term "not both amide groups and carboxyl groups" means that the two functional groups are not both amide groups and carboxyl groups. In the present invention, the term "carboxylate group" refers to a group comprising a carboxylate anion and a counter cation. There is no particular limitation on the type of the counter cation, for example, it can be

In the present invention, the term "surfactant" refers to a substance that can be dissolved in water to reduce the surface tension of water, and covers not only those substances commonly referred to as emulsifiers (small molecule emulsifiers and macromolecular (polymer) emulsifiers, etc.) in the art, but also those substances commonly referred to as stabilizers in the art. Examples of surfactants include anionic surfactants such as sodium dodecyl sulfate, sodium salt of styrene/maleic anhydride copolymers and sodium salt of acrylic acid copolymers, nonionic surfactants such as sorbitan ester compounds and polyoxyethylene ether compounds, cationic surfactants such as dodecyl trimethyl ammonium chloride, and amphoteric surfactants such as dodecyl dimethylamine oxide.

In the present invention, there is no particular limitation on the amount of vinyl chloride used. From the viewpoint of better ensuring the performance based on vinyl chloride and better ensuring the progress of soap-free emulsion polymerization, the amount of vinyl chloride A used is preferably 70% by mass or more and 95% by mass or less, more preferably 72% by mass or more and 93% by mass or less, and further preferably 75% by mass or more and 90% by mass or less, relative to 100% by mass of the total mass of vinyl chloride A, comonomer B and functional monomer C.

Since vinyl chloride is difficult to enter water and is easier to homopolymerize than other monomers, and the functional monomer C described later cannot homopolymerize due to its specific structure (steric hindrance, polarity, etc.), vinyl chloride and functional monomer C cannot effectively form amphiphilic oligomers in the initial stage of polymerization. However, the present inventors have found that by using comonomer B in combination with functional monomer C in a specific ratio, the copolymerizability between vinyl chloride and functional monomer C can be improved without negatively affecting the stable emulsion polymerization effect of functional monomer C, thereby enabling soap-free emulsion polymerization to proceed smoothly.

In the present invention, there is no particular limitation on the specific structure of the comonomer B, as long as it can be copolymerized with vinyl chloride and the functional monomer C described below and has no negative impact on the stability of the emulsion polymerization.

In some preferred embodiments, from the viewpoint of being more conducive to the stable progress of emulsion polymerization and being able to participate in copolymerization in a wide ratio, the comonomer B is preferably at least one selected from monofunctional (meth)acrylate monomers, monofunctional (meth)acrylamide monomers, monofunctional vinyl ester monomers, monofunctional vinyl ether monomers, vinyl pyrrolidone monomers, vinyl pyridine monomers, and vinyl lactam monomers.

There is no particular limitation on the monofunctional (meth)acrylate monomer, examples of which include, but are not limited to: alkyl (meth)acrylates (preferably, alkyl (meth)acrylates having an alkyl group with 1 to 8 carbon atoms), such as methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, tert-butyl (meth)acrylate, pentyl (meth)acrylate, n-hexyl (meth)acrylate, cyclohexyl (meth)acrylate, heptyl (meth)acrylate, octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, nonyl (meth)acrylate, decyl (meth)acrylate, dodecyl (meth)acrylate, octadecyl (meth)acrylate, and the like; hydroxyalkyl (meth)acrylates (preferably, hydroxyalkyl (meth)acrylates having an alkyl group with 1 to 8 carbon atoms), such as hydroxymethyl (meth)acrylate, hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate; glycidyl (meth)acrylate, and the like. These monofunctional (meth)acrylate monomers may be used alone or in combination of any two or more.

There is no particular limitation on the monofunctional (meth)acrylamide-based monomers, and examples thereof include, but are not limited to, (meth)acrylamide, etc. These monofunctional (meth)acrylamide-based monomers may be used alone or in combination of any two or more.

There is no particular limitation on the monofunctional vinyl ester monomer, and examples thereof include, but are not limited to, vinyl acetate, vinyl propionate, vinyl butyrate, allyl acetate, etc. These monofunctional vinyl ester monomers may be used alone or in combination of any two or more.

There is no particular limitation on the monofunctional vinyl ether monomers, and examples thereof include, but are not limited to, methyl vinyl ether, ethyl vinyl ether, propyl vinyl ether, isobutyl vinyl ether, n-butyl vinyl ether, pentyl vinyl ether, hexyl vinyl ether, etc. These monofunctional vinyl ether monomers may be used alone or in combination of any two or more.

There is no particular limitation on the vinyl pyrrolidone-based monomers, and examples thereof include, but are not limited to, N-vinyl pyrrolidone, etc. These vinyl pyrrolidone-based monomers may be used alone or in combination of any two or more.

There is no particular limitation on the vinylpyridine monomer, and examples thereof include, but are not limited to, 2-vinylpyridine, 3-vinylpyridine, 4-vinylpyridine, etc. These vinylpyridine monomers may be used alone or in combination of any two or more.

There is no particular limitation on the vinyl lactam monomer, and examples thereof include, but are not limited to, vinyl caprolactam, vinyl enantholactam, vinyl hexadecanoic acid amide, etc. These vinyl lactam monomers may be used alone or in combination of any two or more.

In some preferred embodiments, from the viewpoint of further achieving the above-mentioned desired effects of the present invention, especially better copolymerizability with vinyl chloride A and functional monomer C, comonomer B is more preferably at least one selected from monofunctional (meth)acrylate monomers, monofunctional (meth)acrylamide monomers, monofunctional vinyl ester monomers, and monofunctional vinyl ether monomers, and particularly preferably a monofunctional vinyl ester monomer, for example, vinyl acetate and/or vinyl propionate.

In the present invention, there is no particular limitation on the amount of comonomer B. From the viewpoint of better ensuring the progress of soap-free emulsion polymerization, the amount of comonomer B is preferably greater than 0% by mass and less than 30% by mass, more preferably 2% by mass or more and 25% by mass or less, and further preferably 2.5% by mass or more and 20% by mass or less, relative to 100% by mass of the total mass of vinyl chloride A, comonomer B and functional monomer C.

In the present invention, as long as the functional monomer C has one free radical polymerizable group and two functional groups selected from an amide group, a carboxyl group, and a carboxylate group and not being an amide group or a carboxyl group at the same time in one molecule, there is no particular limitation on the specific structure of the functional monomer C. In the present invention, the functional monomer C can be used alone or in any combination of two or more.

Here, the radical polymerizable group is not particularly limited, such as an alkynyl group (carbon-carbon triple bond C≡C) or an alkenyl group (carbon-carbon double bond C＝C). In some preferred embodiments, from the viewpoint of better achieving emulsion polymerization without the use of an emulsifier and more easily obtaining the functional monomer C, the radical polymerizable group is preferably an alkenyl group.

In some preferred embodiments, the structure of the functional monomer C is shown in the following formula (1):

In formula (1), A is or Wherein, _R3 , _R6 , _R7 , _R8 each independently represent a direct bond or a C1-C20 substituted or unsubstituted alkylene group, and _R4 , _R5 , _R9 , _R10 each independently represent hydrogen or a C1-C20 substituted or unsubstituted alkyl group. Here, the substituent on the alkylene group or the alkyl group may include a hydroxyl group, an amine group, a halogen atom (e.g., fluorine, chlorine, bromine, iodine, etc.), etc.

In formula (1), R ₁ and R ₂ each independently represent -NR ₁₁ R ₁₂ (R ₁₁ and R ₁₂ each independently represent hydrogen or a C1-C8 alkyl group), -OH, or -OM (M represents an alkali metal or an ammonium group), but are not simultaneously -NR ₁₁ R ₁₂ or -OH.

In addition, in the present invention, there is no particular restriction on the source of the functional monomer C, which can be commercially available or homemade. There is no particular restriction on the homemade method, and various chemical methods known in the art can be used.

In some preferred embodiments, from the viewpoint of more easily obtaining the functional monomer C, the functional monomer C is preferably a monomer obtained by reacting an anhydride monomer and/or a dicarboxylic acid monomer with a basic compound. In other words, the preparation method of the present invention includes the following preparation steps of the functional monomer C: reacting an anhydride monomer and/or a dicarboxylic acid monomer with a basic compound to obtain the functional monomer C.

In the present invention, there is no restriction on the timing of the reaction of the anhydride monomer and/or dicarboxylic acid monomer with the alkaline compound. For example, in some specific embodiments, the reaction of the anhydride monomer and/or dicarboxylic acid monomer with the alkaline compound can be carried out in advance, and then the obtained functional monomer C is added to the polymerization system. For example, in other specific embodiments, the anhydride monomer and/or dicarboxylic acid monomer and the alkaline compound can be directly added to the polymerization system, reacted before polymerization or reacted in situ during the polymerization process to obtain the functional monomer C. In this case, there is no particular restriction on the order of adding the anhydride monomer and/or dicarboxylic acid monomer and the alkaline compound.

In addition, although there is no particular limitation, it is further preferred that, from the viewpoint of being able to obtain the above-mentioned functional monomer C at a lower cost and being more conducive to the role of the functional monomer C, in some specific embodiments, the anhydride monomer is preferably selected from at least one of maleic anhydride, itaconic anhydride, citraconic anhydride, dimethyl maleic anhydride, aconitic anhydride, and phenyl maleic anhydride, and more preferably selected from at least one of maleic anhydride, itaconic anhydride, and citraconic anhydride. Although there is no particular limitation, it is further preferred that, from the same viewpoint, the dicarboxylic acid monomer is selected from at least one of C2 to C20 olefin dicarboxylic acids, and more preferably C4 to C8 olefin dicarboxylic acids. Here, C2 to C20 olefin dicarboxylic acids refer to compounds in which two carboxyl groups are connected to any position of an olefin with a carbon number of 2 to 20, such as ethylene dicarboxylic acid, propylene dicarboxylic acid, isopropylene dicarboxylic acid, maleic acid, itaconic acid, citraconic acid, n-hexenedicarboxylic acid, and the like.

Although not particularly limited, further preferably, from the viewpoint of being able to obtain the above functional monomer C at a relatively low cost, in some specific embodiments, the alkaline compound is at least one selected from ammonia gas, ammonia water, sodium hydroxide and potassium hydroxide.

There is no particular restriction on the amount of the basic compound. In order to better obtain the functional monomer C, the basic compound is preferably used in an over-equivalent manner. Here, the so-called "over-equivalent" refers to an amount exceeding the chemical equivalent required for completing the reaction to form the target structure. Preferably, the upper limit is 4 equivalent times. Here, when two or more basic compounds are used, the amount of the basic compound is the total amount of all the basic compounds.

In the present invention, there is no particular limitation on the amount of the functional monomer C. From the viewpoint of better ensuring the progress of the soap-free emulsion polymerization, the amount of the functional monomer C is preferably greater than 0% by mass and less than 20% by mass, more preferably greater than 2% by mass and less than 18% by mass, relative to 100% by mass of the total mass of the vinyl chloride A, the comonomer B and the functional monomer C.

In addition, within the scope of not impairing the technical effects of the present invention, other monomers besides vinyl chloride A, comonomer B and functional monomer C, such as various monomers copolymerizable only with vinyl chloride A or functional monomer C, may also participate in the emulsion polymerization.

In the present invention, the aqueous medium refers to a medium in which the above-mentioned various monomers can be dispersed, and specific examples thereof include: water, a combination of water and one or more organic solvents as cosolvents, etc. Here, there is no particular limitation on the type of cosolvent, and it can be those commonly used in the art, for example, alcohols such as methanol, ethanol, ethylene glycol, diethylene glycol, etc., ketones such as acetone, methyl ethyl ketone, butanone, cyclohexanone, etc. The amount of the cosolvent can be, for example, 0 to 30% by mass, for example, 1 to 25% by mass, and more preferably 2 to 22% by mass, relative to 100% by mass of the total mass of water and the cosolvent.

In the present invention, the total mass of the monomers used (when there are no other monomers, only vinyl chloride A, comonomer B, and functional monomer C) can be 5 to 100 mass%, preferably 10 to 80 mass%, relative to the total mass of the aqueous medium (100 mass%).

In the present invention, there is no particular limitation on the method of adding each monomer to the aqueous medium. They can all be added to the aqueous medium before polymerization and then polymerized. Alternatively, part or all of a certain monomer or multiple monomers can be added to the aqueous medium in portions or continuously during the polymerization process.

In the present invention, there is no particular limitation on the specific type of polymerization initiator. Specific examples may include but are not limited to: azo initiators, such as azobisisobutyronitrile, azobisisovaleronitrile, azobisisoheptanenitrile, azobisisobutylamidine hydrochloride, azobisisobutylimidazoline hydrochloride, etc.; organic peroxide initiators, such as tert-butyl peroxyneoheptanoate, tert-butyl peroxyneodecanoate, di-sec-butyl peroxydicarbonate, bis(4-tert-butylcyclohexyl) peroxydicarbonate, di(hexadecyl) peroxydicarbonate, tert-amyl peroxyneodecanoate, di-tert-butyl peroxide; Ester, cyclohexylsulfonylacetyl peroxide, dibenzoyl peroxide, diisobutyryl peroxide, lauroyl peroxide, 1,1,3,3-tetramethylbutyl peroxyneodecanoate, di-3-methoxybutyl peroxydicarbonate, 1,1,3,3-tetramethylbutyl peroxypivalate, etc.; persulfate initiators, such as potassium persulfate, ammonium persulfate, etc.; redox initiators, wherein the oxidant may be potassium persulfate, ammonium persulfate, etc., and the reducing agent may be sodium bisulfite, sodium thiosulfate, etc. These initiators may be used alone or in combination of two or more. From the viewpoint of inhibiting the chain transfer of vinyl chloride, it is preferred to use a redox initiator.

The amount of the initiator used may be, for example, 0.001 to 4% by mass, preferably 0.005 to 3% by mass, and more preferably 0.01 to 2% by mass, relative to the total mass of the monomers.

In addition, as required, the polymerization system may further include various additives known in the art, such as a chain transfer agent, a buffer, and the like.

In the present invention, there is no limitation on the initial pH value of the polymerization system before the emulsion polymerization starts, and it can be acidic, neutral or alkaline, and is usually appropriately adjusted according to the specific structure of the polymerization initiator and the functional monomer C used. In some preferred embodiments, from the viewpoint of facilitating industrial operation, a pH adjuster is preferably added to the aqueous medium, so that the initial pH value of the polymerization system before the emulsion polymerization starts is preferably greater than 7 and less than 11, more preferably greater than 7.5 and less than 10.5, and further preferably 8 to 10.

There is no limitation on the specific type of pH adjuster, as long as the above initial pH value can be achieved and there is no negative impact on the polymerization reaction. Specific examples may include but are not limited to: ammonia water, ammonium bicarbonate, sodium bicarbonate, sodium hydroxide, disodium hydrogen phosphate, etc.

There is no particular limitation on the method for adjusting the initial pH of the polymerization system before the start of emulsion polymerization. For example, the pH adjuster may be added to the polymerization system alone, or a reaction solution containing residual alkaline substances directly obtained after pre-preparing the functional monomer C using an alkaline compound may be added to the polymerization system.

In the present invention, there is no particular limitation on the polymerization conditions, which can be appropriately adjusted according to the composition of the polymerization system, etc. In some specific embodiments, the polymerization temperature can be 30 to 65° C., for example, 35 to 60° C. In some specific embodiments, the polymerization time can be 1 to 72 hours, for example, 5 to 36 hours or 5 to 20 hours.

In the present invention, there is no particular limitation on stirring conditions, as long as the emulsion polymerization can be stably carried out. In addition, stirring can be applied by various equipment known in the art.

In addition, in the present invention, the average particle size of the vinyl chloride copolymer particles obtained by emulsion polymerization can be 80 to 350 nm, for example, 170 nm, 200 nm, 250 nm, etc. In the present invention, the average particle size can be measured by a laser particle size analyzer according to a known method.

In addition, the preparation method of the present invention may optionally further comprise various solid-liquid separation steps, washing steps, drying steps, pulverizing steps, screening steps, etc. known in the art.

<Vinyl chloride copolymer latex>

The vinyl chloride copolymer latex of the present invention does not contain a surfactant. Here, the definition of the surfactant is as described in the above <Method for Preparing Vinyl Chloride Copolymer>.

The vinyl chloride copolymer constituting the latex has units based on vinyl chloride A, units based on comonomer B, and units based on functional monomer C, wherein the functional monomer C has a free radical polymerizable group and two functional groups selected from amide groups, carboxyl groups, and carboxylate groups and are not amide groups at the same time in one molecule.

Furthermore, the vinyl chloride-based copolymer may optionally contain units based on other monomers.

The details of vinyl chloride A, comonomer B, functional monomer C and other monomers are as described in the above-mentioned <Method for preparing vinyl chloride copolymer> and will not be repeated here.

In some preferred embodiments of the present invention, the average particle size of the vinyl chloride copolymer particles in the latex may be 120 to 300 nm, such as 150 to 260 nm. In the present invention, the average particle size may be measured by a laser particle size analyzer according to known methods.

In the present invention, there is no particular limitation on the method for preparing the vinyl chloride copolymer latex, and the latex can be obtained by various methods, for example, a method of obtaining an initial latex by emulsion polymerization using a surfactant and performing a post-treatment such as removing the surfactant, by using a pre-prepared copolymer having an initiation terminal and having units based on vinyl chloride A and/or comonomer B and units based on a functional monomer C structure as a macromolecular emulsifier for emulsion polymerization, the method described in the above <Preparation method of vinyl chloride copolymer>, etc. In some preferred embodiments, from the viewpoint of more easily obtaining the vinyl chloride copolymer latex of the present invention, the method described in the above <Preparation method of vinyl chloride copolymer> is preferably adopted.

The vinyl chloride copolymer latex of the present invention may be an initial latex directly obtained after emulsion polymerization, or may be a latex obtained by concentrating or diluting the initial latex.

In the present invention, there is no particular limitation on the ratio of each constituent unit, and it can be appropriately adjusted by adjusting the preparation method according to actual needs. In particular, when the method described in the above-mentioned <Preparation method of vinyl chloride copolymer> of the present invention is adopted, the ratio of each constituent unit can be adjusted by adjusting the feed ratio, the pH of the system before polymerization, the type of initiator, the temperature, etc.

In some preferred embodiments, the mass ratio of units based on comonomer B to units based on functional monomer C, units based on comonomer B/units based on functional monomer C, is preferably 1/20 to 40/1, more preferably 1/15 to 35/1, and further preferably 1/5 to 30/1.

In other preferred embodiments, the content of vinyl chloride A is preferably 70 mass% or more and 95 mass% or less, more preferably 72 mass% or more and 93 mass% or less, further preferably 75 mass% or more and 90 mass% or less, relative to 100 mass% of the total mass of units based on vinyl chloride A, units based on comonomer B and units based on functional monomer C.

In other preferred embodiments, the content of the units based on the comonomer B is preferably greater than 0 mass% and less than 30 mass%, more preferably greater than 2 mass% and less than 25 mass%, further preferably greater than 3 mass% and less than 20 mass%, relative to the total mass of 100 mass% of the units based on vinyl chloride A, the units based on the comonomer B and the units based on the functional monomer C.

In other preferred embodiments, the content of the units based on the functional monomer C is preferably greater than 0 mass% and 18 mass% or less, more preferably 0.5 mass% or more and 10 mass% or less, further preferably 1 mass% or more and 5.5 mass% or less, relative to the total mass of 100 mass% of the units based on vinyl chloride A, the units based on the comonomer B and the units based on the functional monomer C.

<Liquid Vinyl Chloride Copolymer Composition>

The vinyl chloride-based copolymer liquid composition of the present invention comprises the vinyl chloride-based copolymer latex obtained by the above-mentioned preparation method of the present invention, or the above-mentioned vinyl chloride-based copolymer latex according to the present invention.

The vinyl chloride copolymer latex of the present invention may be further compounded with various additives, various resin latexes and/or rubber latexes as necessary to prepare a vinyl chloride copolymer composition, which can be used for various purposes.

Examples of the additives include pigments, dyes, viscosity imparting agents, metal oxides, thickeners, fillers, film-forming aids, ultraviolet absorbers, antioxidants, plasticizers, vulcanizers, vulcanization accelerators, defoaming agents, silane compounds, and surfactants.

<Paste resin of vinyl chloride copolymer>

The paste resin of the vinyl chloride copolymer of the present invention is obtained by using the vinyl chloride copolymer latex obtained by the above-mentioned production method of the present invention, or by using the above-mentioned vinyl chloride copolymer latex of the present invention.

In the present invention, the method for obtaining the paste resin from the above-mentioned latexes is not particularly limited, and any method can be used, for example, spray drying, fluidized bed drying, etc. In addition, the dried crude product can also be subjected to conventional processes such as pulverization and screening.

<Solid Vinyl Chloride Copolymer Composition>

The vinyl chloride-based copolymer solid composition of the present invention comprises a paste resin of the vinyl chloride-based copolymer according to the present invention.

The paste resin of the vinyl chloride copolymer of the present invention may be further compounded with various additives as needed to prepare a vinyl chloride copolymer composition, and used for various purposes.

Examples of the additives include other resins, rubbers, pigments, dyes, tackifiers, metal oxides, fillers, film-forming aids, ultraviolet absorbers, antioxidants, plasticizers, vulcanizers, vulcanization accelerators, defoamers, and silane compounds.

Example

The embodiments of the present invention will be described in detail below in conjunction with the examples, but it will be appreciated by those skilled in the art that the following examples are only used to illustrate the present invention and should not be considered as limiting the scope of the present invention. If no specific conditions are specified in the examples, the conditions are carried out according to normal conditions or the conditions recommended by the manufacturer. If the manufacturer is not specified for the reagents or instruments used, they are all conventional products that can be obtained commercially.

<Evaluation method>

For each embodiment and comparative example, the solid content of the vinyl chloride polymer latex, the stability of the vinyl chloride polymer latex (storage stability, calcium ion stability, mechanical stability, freeze-thaw stability), the complex dispersion of the paste resin, and the water resistance of the paste resin film (water absorption of the film) are determined by the following method.

(Copolymer composition)

The copolymer composition was determined by Bruker AV400 NMR spectrometer (THF-d8 as solvent).

(Solid content)

The solid content of latex is determined by weighing. The mass of latex is m ₁ gram, and then the latex is placed in an oven at 105°C and dried to constant weight. The mass of the dry product is m ₂ grams. Then (m ₂ /m ₁ )×100% is the solid content of the latex.

(Storage stability)

Store the latex at 25°C for 3 months and observe the state of the latex system. If there is slight stratification, shake it to mix and observe whether the latex is liquid after shaking. The evaluation criteria are as follows.

In this evaluation and the following stability evaluations, the occurrence of polymer floccules or precipitation is regarded as a sign of demulsification. The term "demulsification" means that the state of an emulsion (latex) is completely destroyed.

○: The latex does not separate after storage, and no demulsification such as floccules or precipitation occurs after shaking.

△: The latex was slightly stratified after storage, but no demulsification such as floccules or precipitation occurred after shaking.

×: Floccules and/or precipitation occurred in the latex after storage.

Here, "slight stratification" means that a water layer that can be discerned by naked eyes appears on the surface of the latex system after storage, but no polymer floccules or precipitation appears in the latex system as a whole. When the evaluation is "○" or "△", the storage stability is considered acceptable, and when the evaluation is "×", the storage stability is considered unacceptable.

(Calcium ion stability)

A 5 g/L CaCl ₂ aqueous solution was prepared, and the latex and the CaCl ₂ aqueous solution were mixed at a mass ratio of 5:1, and the mixture was placed for 24 hours, and the state of the latex system after the mixture was placed was observed. The evaluation criteria are as follows.

○: The latex after standing did not show demulsification such as floccules or precipitation.

×: After standing, the latex showed demulsification such as floccules or precipitation.

When the evaluation was "○", the calcium ion stability was considered to be acceptable, and when the evaluation was "×", the calcium ion stability was considered to be unacceptable.

(Mechanical stability)

20 ml of latex was poured into a centrifuge tube and centrifuged for 30 minutes using a high-speed centrifuge with a speed set at 3000 r/min. The state of the latex system after centrifugation was observed. The evaluation criteria were as follows.

○: There is no demulsification of the latex after centrifugation.

×: The latex was demulsified after centrifugation.

When the evaluation was "○", the mechanical stability was considered to be acceptable, and when the evaluation was "×", the mechanical stability was considered to be unacceptable.

(Freeze-thaw stability)

20 ml of latex was placed in a -20°C environment and frozen for 16 hours, and then thawed at 25°C for 8 hours, and repeated 5 times. The state of the obtained latex system was observed. The evaluation criteria are as follows.

○: The obtained latex had no demulsification such as floccules and precipitation.

×: The obtained latex showed demulsification such as floccules or precipitation.

When the evaluation was "○", the freeze-thaw stability was considered to be acceptable, and when the evaluation was "×", the freeze-thaw stability was considered to be unacceptable.

(Multi-dispersibility)

The latex was demulsified with a _CaCl2 aqueous solution, and the resulting precipitate was washed with water and dried to constant weight. 1.0 g of sample powder was taken, deionized water was added in a twice mass conversion, and the state of the resulting mixture was observed after ultrasonic treatment for 15 min. The evaluation criteria are as follows.

○: The mixture is a stable latex (emulsion) and does not contain any undispersible solid components.

△: The mixture is a stable latex (emulsion), but a small amount of undispersible solid components is present.

×: The mixture cannot form a stable emulsion, or although a partially stable emulsion is formed, a large amount of undispersible solid components are present.

When the evaluation was "○" or "△", the polydispersity was considered acceptable, and when the evaluation was "×", the polydispersity was considered unacceptable.

(Water absorption)

The paste resin obtained after drying the latex is mixed evenly with paste resin (100phr), plasticizer (DOP, 20phr) and heat stabilizer (Ca-Zn, 2phr), hot pressed into film at 150°C, and cut into 20mm×20mm films to determine the water absorption rate. The mass of the resin film is recorded as m3 _grams . Then, the resin film is placed in deionized water at room temperature of 25°C for 24 hours. After being taken out, the surface moisture is absorbed with filter paper. At this time, the mass of the resin film is recorded as _m4 grams. Then [( _m4 - _m3 )/ _m3 ]×100% is the water absorption rate of the resin film.

<Example 1>

5.0 g of deionized water was added to 5.0 g of maleic acid, and 8.8 g of ammonia water as an alkaline compound was added for ring opening to obtain functional monomer C1 (the two functional groups were ammonium carboxylate and ammonium carboxylate, respectively), and then the remaining 288.4 g of deionized water was added, and the pH was controlled to 9.4 using ammonia water.

Subsequently, in a polymerization reactor, the alkaline mixed solution containing the functional monomers is added, and a redox initiator (2.0 g potassium persulfate and 1.2 g sodium bisulfite) is added, and 15 g vinyl propionate (the mass ratio of vinyl propionate/functional monomer C1 is 3/1) is added. After removing the air in the polymerization reactor by inert gas nitrogen replacement method, 80.0 g vinyl chloride is added (the pH of the system before polymerization is about 9.6 at this time). Pre-emulsification is carried out for half an hour, and then the temperature is raised to 45°C, and the reaction is carried out under mechanical stirring at 400 rpm. The initial reaction pressure is 0.56 MPa, and the reaction is carried out for 10 hours until the pressure in the kettle drops to 0.20 MPa. It is determined that the reaction end point has been reached and the reaction is stopped. After the reaction is completed, the latex of the vinyl chloride copolymer E1 is obtained from the reactor.

A latex of a vinyl chloride copolymer having a solid content of 21.5% was obtained, wherein the composition of the vinyl chloride copolymer was as follows: in terms of mass, units based on vinyl chloride: units based on vinyl propionate: units based on functional monomer C1 = 82.2:15.6:2.2, wherein the units based on vinyl propionate/units based on functional monomer C1 were 7.1/1. Furthermore, the stability of the latex was evaluated.

In addition, the latex was dried to remove water to constant weight, and the dried product was washed with water, and the process was repeated three times. After washing, the latex was dried again to constant weight, and then crushed to obtain a paste resin of a vinyl chloride copolymer.

Table 1 shows the physical properties and stability evaluation results of the latex and the paste resin.

<Example 2>

Except that the pH in Example 1 was controlled to 7.0 (so that the pH of the system before polymerization was about 7.2) to obtain the functional monomer C1 (the two functional groups were ammonium carboxylate and ammonium carboxylate), a latex of a vinyl chloride copolymer with a solid content of 13.4% was obtained in a similar manner to Example 1. The composition of the vinyl chloride copolymer is as follows: in terms of mass, units based on vinyl chloride: units based on vinyl propionate: units based on functional monomer C1 = 84.9:13.8:1.3, and units based on vinyl propionate/units based on functional monomer C1 are 10.6/1.

In addition, in a similar manner to that in Example 1, a paste resin of a vinyl chloride-based copolymer was obtained.

Table 1 shows the physical properties and stability evaluation results of the latex and the paste resin.

<Example 3>

Except that the pH in Example 1 was controlled to 10.5 (so that the pH of the system before polymerization was about 10.8) to obtain the functional monomer C1 (the two functional groups were ammonium carboxylate and ammonium carboxylate), a latex of a vinyl chloride copolymer with a solid content of 17.9% was obtained in a similar manner to Example 1. The composition of the vinyl chloride copolymer is as follows: in terms of mass, units based on vinyl chloride: units based on vinyl propionate: units based on functional monomer C1 = 87.7:11.3:1.0, and units based on vinyl propionate/units based on functional monomer C1 are 11.3/1.

In addition, in a similar manner to that in Example 1, a paste resin of a vinyl chloride-based copolymer was obtained.

Table 1 shows the physical properties and stability evaluation results of the latex and the paste resin.

<Example 4>

Except for changing the amount of functional monomer C1 and vinyl propionate in Example 1 (the mass ratio of vinyl propionate/functional monomer C1 is 1/1), a latex of a vinyl chloride copolymer with a solid content of 22.1% is obtained by a method similar to Example 1. The composition of the vinyl chloride copolymer is as follows: calculated by mass, units based on vinyl chloride: units based on vinyl propionate: units based on functional monomer C1 = 86.4:10.1:3.5, and units based on vinyl propionate/units based on functional monomer C1 is 2.9/1.

In addition, in a similar manner to that in Example 1, a paste resin of a vinyl chloride-based copolymer was obtained.

Table 1 shows the physical properties and stability evaluation results of the latex and the paste resin.

<Example 5>

Except that 17.6g of ammonia water, the alkaline compound in Example 4, is replaced by 3.5g of sodium hydroxide, the total amount of deionized water is 300.0g to obtain functional monomer C2 (the two functional groups are sodium carboxylate and sodium carboxylate, respectively), and the reaction is carried out in a mass ratio of propylene vinyl ester/functional monomer C2 of 1/1. A latex of a vinyl chloride copolymer with a solid content of 20.8% is obtained in a similar manner to Example 4. The composition of the vinyl chloride copolymer is as follows: in terms of mass, units based on vinyl chloride: units based on vinyl propionate: units based on functional monomer C2 = 89.2:9.6:1.2, and units based on vinyl propionate/units based on functional monomer C2 are 8/1.

In addition, in a similar manner to that in Example 1, a paste resin of a vinyl chloride-based copolymer was obtained.

Table 1 shows the physical properties and stability evaluation results of the latex and the paste resin.

<Example 6>

A latex of a vinyl chloride copolymer having a solid content of 22.3% was obtained in a similar manner to that in Example 4, except that the comonomer B in Example 4 was replaced with vinyl acetate and the reaction was carried out in a vinyl acetate/functional monomer C1 mass ratio of 1/1. The composition of the vinyl chloride copolymer was as follows: calculated on a mass basis, units based on vinyl chloride: units based on vinyl acetate: units based on functional monomer C1 = 86.6:10.4:3.0, and units based on vinyl acetate/units based on functional monomer C1 were 3.5/1.

In addition, in a similar manner to that in Example 1, a paste resin of a vinyl chloride-based copolymer was obtained.

Table 1 shows the physical properties and stability evaluation results of the latex and the paste resin.

<Example 7>

Except that the reaction temperature in Example 4 is increased to 48°C, a latex of a vinyl chloride copolymer with a solid content of 21.5% is obtained in a similar manner to Example 4. The composition of the vinyl chloride copolymer is as follows: calculated by mass, units based on vinyl chloride: units based on vinyl propionate: units based on functional monomer C1 = 85.3:10.9:3.8, and units based on vinyl propionate/units based on functional monomer C1 is 2.9/1.

In addition, in a similar manner to that in Example 1, a paste resin of a vinyl chloride-based copolymer was obtained.

Table 1 shows the physical properties and stability evaluation results of the latex and the paste resin.

<Example 8>

Except that the maleic acid monomer in Example 6 is replaced by maleic anhydride to obtain functional unit C3 (the two functional groups are amide group and ammonium carboxylate, respectively), and the reaction is carried out in a manner with a mass ratio of vinyl acetate/functional monomer C3 of 1/1, a latex of a vinyl chloride copolymer with a solid content of 22.6% is obtained in a similar manner to Example 6. The composition of the vinyl chloride copolymer is as follows: calculated by mass, units based on vinyl chloride: units based on vinyl acetate: units based on functional monomer C3 = 87.2:10.0:2.8, and units based on vinyl acetate/units based on functional monomer C3 are 3.6/1.

In addition, in a similar manner to that in Example 1, a paste resin of a vinyl chloride-based copolymer was obtained.

Table 1 shows the physical properties and stability evaluation results of the latex and the paste resin.

<Example 9>

Except that the initiator in Example 4 is replaced by azobisisobutylamidine hydrochloride and the reaction temperature is 56°C, a latex of a vinyl chloride copolymer with a solid content of 22.4% is obtained in a similar manner to Example 4. The composition of the vinyl chloride copolymer is as follows: calculated on a mass basis, units based on vinyl chloride: units based on vinyl propionate: units based on functional monomer C1 = 84.6:10.4:5.0, and units based on vinyl propionate/units based on functional monomer C1 is 2.1/1.

In addition, in a similar manner to that in Example 1, a paste resin of a vinyl chloride-based copolymer was obtained.

Table 1 shows the physical properties and stability evaluation results of the latex and the paste resin.

<Example 10>

Except that the pH in Example 4 is controlled to 6.2 (so that the pH of the system before polymerization is about 6.5) to obtain functional monomer C4 (the two functional groups are carboxylic acid group and ammonium carboxylate, respectively), and the initiator in Example 4 is replaced by azobisisobutylamidine hydrochloride, and the reaction temperature is 56°C, a latex of a vinyl chloride copolymer with a solid content of 18.6% is obtained by a method similar to that in Example 4. The composition of the vinyl chloride copolymer is as follows: calculated by mass, units based on vinyl chloride: units based on vinyl propionate: units based on functional monomer C4 = 85.6:10.3:4.1, and units based on vinyl propionate/units based on functional monomer C4 are 2.5/1.

In addition, in a similar manner to that in Example 1, a paste resin of a vinyl chloride-based copolymer was obtained.

Table 1 shows the physical properties and stability evaluation results of the latex and the paste resin.

<Example 11>

Except for changing the amount of functional monomer C1 and vinyl propionate in Example 1 (the mass ratio of vinyl propionate/functional monomer C1 is 10/1), a latex of a vinyl chloride copolymer with a solid content of 13.6% is obtained by a method similar to Example 1. The composition of the vinyl chloride copolymer is as follows: calculated by mass, units based on vinyl chloride: units based on vinyl propionate: units based on functional monomer C1 = 91.3:8.4:0.3, and units based on vinyl propionate/units based on functional monomer C1 is 28.0/1.

In addition, in a similar manner to that in Example 1, a paste resin of a vinyl chloride-based copolymer was obtained.

Table 2 shows the physical properties and stability evaluation results of the latex and the paste resin.

<Example 12>

Except for changing the amount of functional monomer C1 and vinyl propionate in Example 1 (the mass ratio of vinyl propionate/functional monomer C1 is 5/1), a latex of a vinyl chloride copolymer with a solid content of 15.5% is obtained by a method similar to Example 1. The composition of the vinyl chloride copolymer is as follows: calculated by mass, units based on vinyl chloride: units based on vinyl propionate: units based on functional monomer C1 = 89.8:9.5:0.7, and units based on vinyl propionate/units based on functional monomer C1 is 14.7/1.

In addition, in a similar manner to that in Example 1, a paste resin of a vinyl chloride-based copolymer was obtained.

Table 2 shows the physical properties and stability evaluation results of the latex and the paste resin.

<Example 13>

Except for changing the amount of functional monomer C1 and vinyl propionate in Example 1 (the mass ratio of vinyl propionate/functional monomer C1 is 1/5), a latex of a vinyl chloride copolymer with a solid content of 14.6% is obtained by a method similar to Example 1. The composition of the vinyl chloride copolymer is as follows: calculated on a mass basis, units based on vinyl chloride: units based on vinyl propionate: units based on functional monomer C1 = 94.9:2.0:3.1, and units based on vinyl propionate/units based on functional monomer C1 is 1/1.6.

In addition, in a similar manner to that in Example 1, a paste resin of a vinyl chloride-based copolymer was obtained.

Table 2 shows the physical properties and stability evaluation results of the latex and the paste resin.

<Example 14>

Except for changing the amount of functional monomer C1 and vinyl propionate in Example 1 (the mass ratio of vinyl propionate/functional monomer C1 is 1/10), a latex of a vinyl chloride copolymer with a solid content of 9.6% is obtained by a method similar to Example 1. The composition of the vinyl chloride copolymer is as follows: calculated by mass, units based on vinyl chloride: units based on vinyl propionate: units based on functional monomer C1 = 92.7:1.3:6.0, and units based on vinyl propionate/units based on functional monomer C1 is 1/4.6.

In addition, in a similar manner to that in Example 1, a paste resin of a vinyl chloride-based copolymer was obtained.

Table 2 shows the physical properties and stability evaluation results of the latex and the paste resin.

<Comparative Example 1>

The polymerization was carried out in a similar manner to Example 1 except that only vinyl chloride was used as the monomer and sodium dodecyl sulfate was added in an amount of 1% by mass. The initial reaction pressure was 0.56 MPa, and the pressure in the reactor dropped to 0.12 MPa after 10 hours of reaction, and the reaction was stopped. A homopolymerized polyvinyl chloride latex with a solid content of 24.6% was obtained.

The latex is dried to remove water to constant weight, and the dried product is washed with water, and the process is repeated three times. After washing, the latex is dried again to constant weight, and the homopolymerized polyvinyl chloride paste resin is obtained after crushing.

Table 2 shows the physical properties and stability evaluation results of the latex and the paste resin.

<Comparative Example 2>

Except that the maleic acid in Example 1 was replaced by acrylic acid to obtain the functional monomer CC1 (having only one functional group in the molecule), polymerization was carried out in a similar manner as in Example 1. The initial reaction pressure was 0.56 MPa, and the pressure in the reactor dropped to 0.15 MPa after 10 hours of reaction, and the reaction was stopped. No latex was obtained, and the product agglomerated and demulsified.

<Comparative Example 3>

The polymerization was carried out in a similar manner to Example 4 except that maleic acid was directly used as the functional monomer CC2 (both functional groups of the functional monomer were carboxyl groups). After 10 hours of reaction, the pressure in the reactor did not decrease, and the reaction was stopped. No latex was obtained, and a small amount of white insoluble matter was present in the solution.

<Comparative Example 4>

Except for changing the amount of vinyl propionate and functional monomer C1 in Example 1 (the mass ratio of vinyl propionate/functional monomer C1 is 15/1), polymerization was carried out in a similar manner as in Example 1. After 10 hours of reaction, the pressure in the reactor did not decrease, and the reaction was stopped. No latex was obtained, and a very small amount of white insoluble matter existed in the solution.

<Comparative Example 5>

Except for changing the amount of functional monomer C1 and vinyl propionate in Example 1 (the mass ratio of vinyl propionate/functional monomer C1 is 1/15), polymerization was carried out in a similar manner as in Example 1. After 10 hours of reaction, the pressure in the reactor did not decrease, and the reaction was stopped. No latex was obtained, and a very small amount of white insoluble matter existed in the solution.

<Comparative Example 6>

The polymerization was carried out in a similar manner to Example 1 except that vinyl propionate was not used. After 10 hours of reaction, the pressure in the reactor did not decrease, so the reaction was stopped. No latex was obtained, and the solution was slightly yellow and unreacted.

In Comparative Example 1, the high water absorption evaluation result shows that even after three washes, there are still surfactants in the paste resin that are difficult to remove. In Comparative Examples 2 to 6, no stable latex was obtained during the polymerization (even if polymerization products were obtained in Comparative Examples 2 and 3), so no evaluation of stability, re-dispersibility and water absorption was performed. In addition, in Table 2, for the purpose of convenience of description, the component C and its amount listed in Comparative Example 2 are descriptions of the functional monomer CC1, and the component C and its amount listed in Comparative Example 3 are descriptions of the functional monomer CC2.

It should be noted that, although the technical solution of the present invention is introduced with specific examples, those skilled in the art will appreciate that the present invention should not be limited thereto.

The embodiments of the present invention have been described above, and the above description is exemplary, not exhaustive, and is not limited to the disclosed embodiments. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments. The selection of terms used herein is intended to best explain the principles of the embodiments, practical applications, or technical improvements in the market, or to enable other persons of ordinary skill in the art to understand the embodiments disclosed herein.

Claims (12)

A method for preparing a vinyl chloride copolymer, characterized in that the method comprises: Vinyl chloride A, comonomer B, and functional monomer C are subjected to emulsion polymerization in an aqueous medium without a surfactant under stirring in the presence of a polymerization initiator. The functional monomer C has one free radical polymerizable group and two functional groups selected from amide groups, carboxyl groups and carboxylate groups and not being amide groups or carboxyl groups at the same time in one molecule, The mass ratio of the comonomer B to the functional monomer C, comonomer B/functional monomer C, is 1/12 to 12/1. The preparation method according to claim 1, characterized in that the comonomer B is at least one selected from monofunctional (meth)acrylate monomers, monofunctional (meth)acrylamide monomers, monofunctional vinyl ester monomers, monofunctional vinyl ether monomers, vinyl pyrrolidone monomers, vinyl pyridine monomers and vinyl lactam monomers. The preparation method according to claim 1 or 2, characterized in that the functional monomer C is a monomer obtained by reacting an anhydride monomer and/or a dicarboxylic acid monomer with a basic compound. The preparation method according to claim 3 is characterized in that the alkaline compound is at least one selected from ammonia gas, ammonia water, sodium hydroxide and potassium hydroxide, the acid anhydride monomer is at least one selected from maleic anhydride, itaconic anhydride, citraconic anhydride, dimethylmaleic anhydride, aconitic anhydride and phenylmaleic anhydride, and the dicarboxylic acid monomer is at least one selected from C2 to C20 olefin dicarboxylic acids. The preparation method according to any one of claims 1 to 4, characterized in that, relative to 100 mass% of the total mass of the vinyl chloride A, the comonomer B and the functional monomer C, the amount of the vinyl chloride A is greater than 70 mass% and less than 95 mass%, the amount of the comonomer B is greater than 0 mass% and less than 30 mass%, and the amount of the functional monomer C is greater than 0 mass% and less than 20 mass%. The preparation method according to any one of claims 1 to 5, characterized in that a pH regulator is further added to the aqueous medium so that the initial pH value of the polymerization system before the start of the emulsion polymerization is greater than 7 and less than 11. The preparation method according to any one of claims 1 to 6, characterized in that in the emulsion polymerization, the polymerization temperature is 30 to 65° C. and the polymerization time is 1 to 72 hours. A vinyl chloride copolymer latex, characterized in that the vinyl chloride copolymer latex does not contain a surfactant, The vinyl chloride copolymer constituting the latex has units based on vinyl chloride A, units based on comonomer B, and units based on functional monomer C. The functional monomer C has one free radical polymerizable group and two functional groups selected from amide groups, carboxyl groups, and carboxylate groups and not being amide groups at the same time in one molecule. The vinyl chloride copolymer latex according to claim 8 is characterized in that the average particle size of the vinyl chloride copolymer particles in the latex is 100 to 350 nm; in the vinyl chloride copolymer, the mass ratio of the units based on the comonomer B to the units based on the functional monomer C, units based on the comonomer B/units based on the functional monomer C, is 1/20 to 40/1. A vinyl chloride copolymer liquid composition, characterized in that the composition comprises a vinyl chloride copolymer latex obtained by the preparation method according to any one of claims 1 to 7, or a vinyl chloride copolymer latex according to claim 8 or 9. A paste resin of a vinyl chloride copolymer, characterized in that the paste resin is obtained by using a vinyl chloride copolymer latex obtained by the preparation method according to any one of claims 1 to 7, or by using a vinyl chloride copolymer latex according to claim 8 or 9. A solid composition of a vinyl chloride copolymer, characterized in that the composition comprises the paste resin according to claim 10.