JP7686964B2 - Paste polyvinyl chloride resin - Google Patents

Description

The present invention relates to a paste vinyl chloride resin, and more specifically, to a paste vinyl chloride resin that makes it possible to provide a paste vinyl chloride resin composition that has excellent resistance to devitrification whitening, and a product made from the paste vinyl chloride resin.

Polyvinyl chloride resin for paste processing (hereinafter sometimes abbreviated as paste PVC) is generally kneaded with plasticizers, fillers, stabilizers and/or other compounding agents to prepare a paste PVC sol, which is then used in a variety of molding processes to produce a variety of molded products such as wallpaper, carpet tiles, and gloves.

On the other hand, chlorine-containing resins such as polyvinyl chloride resins are excellent in flame retardancy and chemical resistance, and are used in a variety of applications. However, polyvinyl chloride resin compositions or products made from them become cloudy after immersion in water, and the transparency that should be maintained is lost, causing a phenomenon known as devitrification and whitening, which limits their use, particularly in applications around water.

In order to solve the above problems, various stabilizers have been investigated, and it has been reported that lead compounds, or mixtures of cadmium compounds and barium compounds in particular have excellent stabilizing effects. For example, Patent Document 1 proposes a vinyl chloride resin composition that has been designed to improve resistance to devitrification whitening.

JP 2012-041484 A

However, the improvement in resistance to devitrification whitening in the vinyl chloride resin composition proposed in Patent Document 1 is still at an insufficient level, and no consideration has been given to vinyl chloride resins for paste processing.

The object of the present invention is to provide a paste vinyl chloride resin and a product made from the resin that exhibits extremely little change in devitrification whitening over time and has excellent resistance to devitrification whitening.

As a result of extensive research into the above-mentioned problems, the inventors discovered that a paste vinyl chloride resin having a specific degree of polymerization and a specific amount of emulsifier becomes a paste vinyl chloride resin that exhibits extremely little change over time in terms of devitrification whitening, and that it is possible to provide a vinyl chloride resin composition and product for paste processing that exhibit excellent resistance to devitrification whitening, thus completing the present invention.

That is, the present invention relates to a paste vinyl chloride resin that contains 0.05 to 2 parts by weight of a sulfosuccinate surfactant per 100 parts by weight of vinyl chloride resin having an average degree of polymerization of 1,000 to 3,000.

The present invention will be described in detail below.

The vinyl chloride resin constituting the vinyl chloride paste resin of the present invention has an average degree of polymerization of 1000 to 3000, preferably 1300 to 3000, and more preferably 1500 to 2000, since this provides excellent mechanical strength when molded into flooring, sheets, films, and other products. Here, if the vinyl chloride resin has an average degree of polymerization of less than 1000, the molded product obtained will be inferior in transparency and resistance to devitrification whitening. On the other hand, if it exceeds 3000, the moldability of the vinyl chloride paste resin will be poor. The average degree of polymerization can be determined, for example, by a method conforming to JIS-K6721.

There are no particular limitations on the vinyl chloride resin, and examples of vinyl chloride resins that can be obtained by methods such as bulk polymerization, solution polymerization, suspension polymerization, and emulsion polymerization include polyvinyl chloride, chlorinated polyvinyl chloride, polyvinylidene chloride, chlorinated polyethylene, vinyl chloride-vinyl acetate copolymer, vinyl chloride-ethylene copolymer, vinyl chloride-propylene copolymer, vinyl chloride-styrene copolymer, vinyl chloride-isobutylene copolymer, vinyl chloride-vinylidene chloride copolymer, vinyl chloride-styrene-maleic anhydride terpolymer, vinyl chloride-styrene-acrylonitrile copolymer, vinyl chloride-butadiene copolymer, vinyl chloride-isoprene copolymer, Examples of vinyl chloride resins include vinyl chloride-chlorinated propylene copolymers, vinyl chloride-vinylidene chloride-vinyl acetate terpolymers, vinyl chloride-maleic acid ester copolymers, vinyl chloride-methacrylic acid ester copolymers, vinyl chloride-acrylonitrile copolymers, and vinyl chloride-various vinyl ether copolymers, as well as blends of these resins with other chlorine-free synthetic resins, such as acrylonitrile-styrene copolymers, acrylonitrile-butadiene-styrene copolymers, ethylene-vinyl acetate copolymers, ethylene-ethyl (meth)acrylate copolymers, and blends with polyesters, block copolymers, and graft copolymers.

The vinyl chloride paste resin of the present invention contains 0.05 to 2 parts by weight of a sulfosuccinate surfactant per 100 parts by weight of vinyl chloride resin. In particular, when molded into a molded product, the change in devitrification whitening over time is extremely excellent, and the product is particularly excellent for use as flooring, sheets, and films. Therefore, it is preferable that the content is 0.2 to 1.5 parts by weight, and more preferably 0.4 to 1.0 parts by weight. Here, if the content of the sulfosuccinate surfactant is less than 0.05 parts by weight, polymerization during the production of the vinyl chloride paste resin becomes unstable, resulting in poor paste processability. On the other hand, if the content exceeds 2 parts by weight, the molded product obtained will have poor resistance to devitrification whitening.

The sulfosuccinate-based surfactant may be any surfactant that belongs to the category of surfactants having a sulfosuccinate, and examples of such surfactants include dipotassium sulfosuccinate-based surfactants such as dipotassium polyoxyethylene alkyl sulfosuccinate and dipotassium polyoxyethylene alkyl ether sulfosuccinate; potassium sulfosuccinate-based surfactants such as potassium dialkyl sulfosuccinate, potassium polyoxyethylene lauryl ether sulfosuccinate, potassium dioctyl sulfosuccinate, potassium dioctyl sulfosuccinate, and potassium dihexyl sulfosuccinate; disodium sulfosuccinate-based surfactants such as disodium succinate and disodium polyoxyethylene alkyl ether sulfosuccinate; sodium sulfosuccinate-based surfactants such as dialkyl sodium sulfosuccinate, polyoxyethylene lauryl ether sodium sulfosuccinate, dioctyl sodium sulfosuccinate, dioctyl sodium sulfosuccinate, and dihexyl sodium sulfosuccinate; diammonium sulfosuccinate-based surfactants such as polyoxyethylene alkyl diammonium sulfosuccinate and polyoxyethylene alkyl ether diammonium sulfosuccinate; diammonium sulfosuccinate-based surfactants such as diammonium sulfosuccinate and polyoxyethylene alkyl ether diammonium sulfosuccinate; Ammonium sulfosuccinate surfactants such as ammonium alkyl sulfosuccinate, polyoxyethylene lauryl ether ammonium sulfosuccinate, dioctyl ammonium sulfosuccinate, dioctyl ammonium sulfosuccinate, and dihexyl ammonium sulfosuccinate; ditriethanolammonium sulfosuccinate surfactants such as polyoxyethylene alkyl ditriethanolammonium sulfosuccinate and polyoxyethylene alkyl ether ditriethanolammonium sulfosuccinate; triethanolammonium sulfosuccinate surfactants such as dialkyl triethanolammonium sulfosuccinate, polyoxyethylene lauryl ether triethanolammonium sulfosuccinate, dioctyl triethanolammonium sulfosuccinate, and dihexyl triethanolammonium sulfosuccinate; or two or more of these surfactants, preferably one or more selected from dipotassium sulfosuccinate surfactants, disodium sulfosuccinate surfactants, diammonium sulfosuccinate surfactants, and ditriethanolammonium sulfosuccinate surfactants.

The vinyl chloride resin paste of the present invention preferably contains a nonionic surfactant, since it has an appropriate degree of aggregation and excellent powder properties. In this case, it is preferable that the amount of the nonionic surfactant contained is 1 part by weight or less, and more preferably 0.01 to 0.5 parts by weight, per 100 parts by weight of the vinyl chloride resin.

The nonionic surfactant may be any surfactant that falls within that category, and polyoxyalkylene alkyl ethers are preferred, with polyoxyalkylene lauryl ethers being particularly preferred.

Examples of polyoxyalkylene alkyl ethers include polyoxyethylene lauryl ethers, polyoxyethylene myristyl ethers, polyoxyethylene cetyl ethers, polyoxyethylene stearyl ethers, polyoxyethylene oleyl ethers, polyoxypropylene alkyl ethers such as polyoxyethylene lauryl ether, polyoxypropylene myristyl ether, polyoxypropylene cetyl ether, polyoxypropylene stearyl ether, and polyoxypropylene oleyl ether. Specific examples of polyoxyethylene lauryl ethers include commercially available products such as polyoxyethylene (12) lauryl ether (Kao Corporation, product name: Emulgen 120), polyoxyethylene (21) lauryl ether (Nikko Chemicals Co., Ltd., product name: NIKKOL BL-21), polyoxyethylene (25) lauryl ether (Nikko Chemicals Co., Ltd., product name: NIKKOL BL-25), and polyoxyethylene (47) lauryl ether (Kao Corporation, product name: Emulgen 150). Specific examples of polyoxyethylene cetyl ethers include commercially available products such as polyoxyethylene (15) cetyl ether (Nikko Chemicals Co., Ltd., product name: NIKKOL BC-15), polyoxyethylene (20) cetyl ether (Nikko Chemicals Co., Ltd., product name: NIKKOL BC-25), and polyoxyethylene (22) cetyl ether (Nikko Chemicals Co., Ltd., product name: NIKKOL BC-30). BC-20), polyoxyethylene (23) cetyl ether (Nikko Chemicals Co., Ltd., trade name: NIKKOL BC-23), polyoxyethylene (25) cetyl ether (Nikko Chemicals Co., Ltd., trade name: NIKKOL BC-25), polyoxyethylene (30) cetyl ether (Nikko Chemicals Co., Ltd., trade name: NIKKOL BC-30), polyoxyethylene (40) cetyl ether (Nikko Chemicals Co., Ltd., trade name: NIKKOL BC-40), and other commercially available products are included. Specific examples of polyoxyethylene stearyl ethers include, for example, polyoxyethylene (20) stearyl ether (Nikko Chemicals Co., Ltd., trade name: NIKKOL BC-20), polyoxyethylene (23) cetyl ether (Nikko Chemicals Co., Ltd., trade name: NIKKOL BC-23), polyoxyethylene (25) cetyl ether (Nikko Chemicals Co., Ltd., trade name: NIKKOL BC-25), polyoxyethylene (30) cetyl ether (Nikko Chemicals Co., Ltd., trade name: NIKKOL BC-30), and polyoxyethylene (40) cetyl ether (Nikko Chemicals Co., Ltd., trade name: NIKKOL BC-40). BS-20), polyoxyethylene (50) stearyl ether (Kao Corporation, product name: Emulgen 350), etc. are commercially available products. Specific examples of polyoxyethylene oleyl ethers include commercially available products such as polyoxyethylene (15) oleyl ether (Nikko Chemicals Co., Ltd., product name: NIKKOL BO-15V), polyoxyethylene (30) oleyl ether (Kao Corporation, product name: Emulgen 430), polyoxyethylene (50) oleyl ether (Nikko Chemicals Co., Ltd., product name: NIKKOL BO-50V), etc.

The vinyl chloride resin paste of the present invention may contain or may use other emulsifiers during its production and polymerization. Examples of other emulsifiers include alkylbenzene sulfonates, alkylnaphthalene sulfonates, compounds having alkyldiphenyl ether disulfonates, and compounds having higher fatty acid salts. Examples of compounds having alkylbenzene sulfonates include sodium dodecylbenzene sulfonate and ammonium dodecylbenzene sulfonate. Examples of compounds having alkylnaphthalene sulfonates include sodium alkylnaphthalene sulfonate and potassium alkylnaphthalene sulfonate. Examples of compounds having alkyldiphenyl ether disulfonates include sodium alkyldiphenyl ether disulfonate and potassium alkyldiphenyl ether disulfonate. Examples of compounds having higher fatty acid salts include salts of lauric acid, myristic acid, palmitic acid, stearic acid, oleic acid, and the like with alkali.

The paste vinyl chloride resin of the present invention can be produced by emulsion polymerization, microsuspension polymerization, seed emulsion polymerization, seed microsuspension polymerization, etc., which are known as common polymerization methods for paste vinyl chloride. It can be produced by obtaining a vinyl chloride resin latex by these polymerization methods and removing the moisture from the obtained vinyl chloride resin latex. In this case, methods for removing moisture from the vinyl chloride resin latex include, for example, spray drying, fluidized bed drying, ventilation drying, rotary drying, and conductive heat drying. Among them, the method of obtaining granules/particles by spray drying is preferable because it can efficiently remove moisture. The paste vinyl chloride resin obtained in this case is particularly easy to handle, so it is preferable that it has a particle shape with an average particle size of 3 to 100 μm, especially 30 to 80 μm. The average particle size can be defined as the particle size (median size) at which the cumulative distribution in the particle size distribution is 50%.

Below, the seed microsuspension polymerization method is shown as an example of a method for producing the paste vinyl chloride resin (vinyl chloride resintex) of the present invention.

The seed microsuspension polymerization method is a polymerization method consisting of 1) a first step of obtaining a vinyl chloride resin seed latex containing a vinyl chloride resin containing an oil-soluble polymerization initiator by a microsuspension polymerization method, and 2) a second step of polymerizing the obtained vinyl chloride resin seed latex with vinyl chloride monomer or vinyl chloride monomer and a monomer copolymerizable therewith in the presence of deionized water, emulsifier, surfactant, buffer, and, if necessary, emulsifying aid such as higher alcohol, with gentle stirring to enlarge the seed latex and obtain a vinyl chloride resin latex.

Here, the emulsifiers and surfactants that can be used are those described above.

Examples of buffering agents include alkali metal monohydrogen phosphate, alkali metal dihydrogen phosphate, potassium hydrogen phthalate, sodium bicarbonate, and boric acid-caustic potassium solution.

Examples of emulsifying aids that can be used as needed include higher alcohols such as cetyl alcohol and lauryl alcohol; higher fatty acids such as lauric acid, palmitic acid, and stearic acid; esters thereof, aromatic hydrocarbons, higher fatty acid hydrocarbons, and halogenated hydrocarbons such as chlorinated paraffins.

The vinyl chloride resin seed latex used in the seed microsuspension polymerization method can be prepared by the following microsuspension polymerization method. First, vinyl chloride monomer, oil-soluble polymerization initiator, surfactant, buffer, higher alcohol, higher fatty acid, higher fatty acid ester, dispersion aid such as chlorinated paraffin, and polymerization degree regulator as necessary are added to premix, and then homogenized with a homogenizer to prepare oil droplets. As the homogenizer, for example, a colloid mill, a vibration agitator, a two-stage high-pressure pump, etc. can be used. Then, the homogenized liquid is sent to a polymerization vessel, and the temperature inside the polymerization vessel is raised while gently stirring to start the polymerization reaction, and polymerization is carried out until a predetermined conversion rate is reached, thereby making it possible to prepare a vinyl chloride resin seed latex containing an oil-soluble polymerization initiator.

As an oil-soluble polymerization initiator, a diacyl peroxide with a 10-hour half-life temperature of 30 to 70°C is preferred. Examples of such polymerization initiators include isobutyryl peroxide, 3,3,5-trimethylhexanoyl peroxide, octanoyl peroxide, lauroyl peroxide, stearoyl peroxide, and succinic acid peroxide.

Then, the obtained vinyl chloride resin seed latex is polymerized with gentle stirring in the presence of vinyl chloride monomer, deionized water, emulsifier, buffer, and, if necessary, emulsification aid such as higher alcohol, to enlarge the seed latex and obtain vinyl chloride resin latex.

In this case, the sulfosuccinate surfactant constituting the paste vinyl chloride resin of the present invention, and the nonionic surfactant used in some cases, may be added before, during, or after the polymerization of the paste vinyl chloride resin.

The vinyl chloride paste resin of the present invention can be made into various products by blending a plasticizer to make a paste vinyl chloride resin composition that is a paste vinyl sol. In this case, additives such as stabilizers, antioxidants, flame retardants, diluents, lubricants, ultraviolet absorbers, colorants such as pigments, surfactants, antistatic agents, fillers, etc. may be included, and the blending amounts of these may be within the ranges generally used.

The vinyl chloride paste resin of the present invention has excellent resistance to devitrification whitening, and it is preferable that a product made of the resin has a haze value of 40% or less after immersion in water for three days. The method for measuring and evaluating the resistance to devitrification whitening in this case can be the method described below. The vinyl chloride paste resin of the present invention can be suitably used for applications such as films, sheets, wallpaper, flooring materials, and foam sheets.

The vinyl chloride resin paste of the present invention can provide products that are excellent in resistance to devitrification and whitening, and is of great industrial value.

The present invention will be described in more detail below with reference to examples and comparative examples, but the present invention is not limited to these.

The following describes how to evaluate the vinyl chloride resin paste obtained from the examples.

<Average particle diameter>
The particle size distribution was measured using a laser diffraction particle size distribution measuring instrument (manufactured by Horiba, Ltd.: (product name) LA-920), and the particle size (median size) at which the cumulative distribution was 50% was taken as the average particle size.

<Method of measuring the degree of aggregation>
The degree of cohesion was measured using a powder tester (manufactured by Hosokawa Micron Corporation, product name PT-X). Details are given below.

2.0 g of the paste polyvinyl chloride resin powder was placed on the top of a three-stage sieve (with mesh sizes of 250 μm on the top stage, 150 μm in the middle stage, and 75 μm on the bottom stage) and sieved for 60 seconds with an amplitude of 1 mm. Powder that formed lumps due to vibration was separated, and the degree of cohesion was calculated from the amount of each residue using the following formula.
Cohesion degree = (U/N + M/N x 3/5 + L/N x 1/5) x 100%
U: powder mass on the top sieve [g].
M: powder mass on the middle sieve [g].
L: powder mass on the lower sieve [g].
N: sample mass [g].

<Transparency evaluation method>
The vinyl chloride resin paste was cut into a sheet-like sample (the method for preparing the sheet-like sample will be described later), and the sheet was immersed in warm water at 23° C. for 3 days, after which the sheet was taken out and the transparency was judged visually.
○: The sheet is transparent or slightly cloudy.
× The sheet is cloudy.

<Method for measuring resistance to devitrification whitening>
The paste vinyl chloride resin was made into a sheet-like sample (a method for preparing a sheet-like sample will be described later), which was then immersed in warm water at 23° C. for 3 days, after which the moisture was wiped off and the sample was dried. The haze was measured using a haze meter (Nippon Denshoku Industries Co., Ltd.), and the result and the above-mentioned transparency were combined to evaluate the resistance to devitrification whitening.
〇: Haze meter value is 40 or less and transparency is 〇.
×: Haze meter value exceeds 40 or transparency is ×.

Synthesis Example 1 (Production Example of Seed Containing Initiator, etc.)
In a 1 ^m3 autoclave, 360 kg of deionized water, 300 kg of vinyl chloride monomer, 6 kg of lauroyl peroxide, and 30 kg of 15 wt% aqueous sodium dodecylbenzenesulfonate solution were charged, and the polymerization liquid was circulated using a homogenizer for 2 hours. After homogenization, the temperature was raised to 45°C to proceed with polymerization. After the pressure was reduced by 0.2 MPa from the saturated vapor pressure of the vinyl chloride monomer at 45°C, the unreacted vinyl chloride monomer was recovered. The average particle size of the obtained initiator-containing seed latex (hereinafter abbreviated as seed 1) was 0.60 μm, and the solid content concentration was 32%.

Example 1
Into a 2.5 liter autoclave were charged 700 g of deionized water, 850 g of vinyl chloride monomer, 14 g of a 5% aqueous solution of disodium polyoxyethylene alkylsulfosuccinate, 85 g of seed 1, and 4 g of a 0.1% aqueous solution of copper sulfate. Thereafter, the temperature of this reaction mixture was raised to 48° C. to initiate polymerization, and a 0.05 wt % aqueous solution of ascorbic acid was continuously added throughout the entire polymerization time so as to maintain the polymerization temperature. The polymerization was terminated when the polymerization conversion rate reached 88%.

In addition, 80 g of a 5% aqueous solution of disodium polyoxyethylene alkylsulfosuccinate was continuously added from the start to the end of the polymerization.

The unreacted monomers were then recovered to form a latex, and 30 g of an aqueous solution of disodium polyoxyethylene alkyl sulfosuccinate was added to obtain a latex solution containing vinyl chloride resin particles. The solution was then spray-dried in a spray dryer at a hot air inlet temperature of 110°C and an outlet temperature of 50°C to obtain a vinyl chloride resin paste. The vinyl chloride resin paste thus obtained contained 0.7 parts by weight of disodium polyoxyethylene alkyl sulfosuccinate per 100 parts by weight of vinyl chloride resin with an average degree of polymerization of 1650. The powder characteristics were also good, with an average particle size of 63 μm and a degree of aggregation of 10.2%.

100 parts by weight of the obtained paste polyvinyl chloride resin were mixed with 60 parts by weight of dioctyl phthalate (J-Plus Corporation, industrial grade) as a plasticizer and 3 parts by weight of a stabilizer (ADEKA Corporation, product name SC320) using a dissolver to obtain a paste polyvinyl chloride sol.

The obtained paste vinyl sol was coated to a thickness of 0.3 mm on a PET film that had been heated at 180°C for 1 minute, and then heated at 180°C for 1 minute to create a sheet-shaped sample.

The obtained sheet-like sample was immersed in warm water at 23° C. for 3 days, after which the moisture was wiped off and the sample was dried. The haze was measured using a haze meter (Nippon Denshoku Industries Co., Ltd.) to evaluate resistance to devitrification and whitening.
The test results are shown in Table 1. The haze value was 19, the transparency was good, and the resistance to devitrification and whitening and powder properties were excellent.

Example 2
Into a 2.5 liter autoclave were charged 700 g of deionized water, 850 g of vinyl chloride monomer, 14 g of a 5% aqueous solution of disodium polyoxyethylene alkylsulfosuccinate, 85 g of seed 1, and 4 g of a 0.1% aqueous solution of copper sulfate. Thereafter, the temperature of this reaction mixture was raised to 48° C. to initiate polymerization, and a 0.05 wt % aqueous solution of ascorbic acid was continuously added throughout the entire polymerization time so as to maintain the polymerization temperature. The polymerization was terminated when the polymerization conversion rate reached 88%.

In addition, 80 g of a 5% aqueous solution of disodium polyoxyethylene alkylsulfosuccinate was continuously added from the start to the end of the polymerization.

The unreacted monomers were then collected to form a latex, and 30 g of an aqueous solution of disodium polyoxyethylene alkyl sulfosuccinate and 9 g of polyoxyalkylene lauryl ether were added to obtain a latex solution containing vinyl chloride resin particles. The mixture was then spray-dried in a spray dryer at a hot air inlet temperature of 110°C and an outlet temperature of 50°C to obtain a vinyl chloride resin paste. The vinyl chloride resin paste thus obtained contained 0.7 parts by weight of disodium polyoxyethylene alkyl sulfosuccinate and 0.1 parts by weight of polyoxyalkylene lauryl ether per 100 parts by weight of vinyl chloride resin with an average degree of polymerization of 1600. The powder characteristics were also good, with an average particle size of 65 μm and a degree of aggregation of 8.0%.

100 parts by weight of the obtained paste polyvinyl chloride resin were mixed with 60 parts by weight of dioctyl phthalate (J-Plus Corporation, industrial grade) as a plasticizer and 3 parts by weight of a stabilizer (ADEKA Corporation, product name SC320) using a dissolver to obtain a paste polyvinyl chloride sol.

The obtained paste vinyl sol was coated to a thickness of 0.3 mm on a PET film that had been heated at 180°C for 1 minute, and then heated at 180°C for 1 minute to create a sheet-shaped sample.

The obtained sheet-like sample was immersed in warm water at 23° C. for 3 days, after which the moisture was wiped off and the sample was dried. The haze was measured using a haze meter (Nippon Denshoku Industries Co., Ltd.) to evaluate resistance to devitrification and whitening.
The test results are shown in Table 1. The haze value was 23, the transparency was good, and the resistance to devitrification whitening and powder properties were excellent.

Example 3
Into a 2.5 liter autoclave were charged 700 g of deionized water, 850 g of vinyl chloride monomer, 14 g of a 5% aqueous solution of disodium polyoxyethylene alkylsulfosuccinate, 85 g of seed 1, and 4 g of a 0.1% aqueous solution of copper sulfate. Thereafter, the temperature of this reaction mixture was raised to 48° C. to initiate polymerization, and a 0.05 wt % aqueous solution of ascorbic acid was continuously added throughout the entire polymerization time so as to maintain the polymerization temperature. The polymerization was terminated when the polymerization conversion rate reached 88%.

In addition, 80 g of a 5% aqueous solution of disodium polyoxyethylene alkylsulfosuccinate was continuously added from the start to the end of the polymerization.

The unreacted monomers were then collected to form a latex, and 30 g of an aqueous solution of disodium polyoxyethylene alkyl sulfosuccinate and 27 g of polyoxyalkylene lauryl ether were added to obtain a latex solution containing vinyl chloride resin particles. The mixture was then spray-dried in a spray dryer at a hot air inlet temperature of 110°C and an outlet temperature of 50°C to obtain a vinyl chloride resin paste. The vinyl chloride resin paste thus obtained contained 0.7 parts by weight of disodium polyoxyethylene alkyl sulfosuccinate and 0.3 parts by weight of polyoxyalkylene lauryl ether per 100 parts by weight of vinyl chloride resin with an average degree of polymerization of 1600. The powder characteristics were also good, with an average particle size of 60 μm and a degree of aggregation of 6.2%.

100 parts by weight of the obtained paste polyvinyl chloride resin were mixed with 60 parts by weight of dioctyl phthalate (J-Plus Corporation, industrial grade) as a plasticizer and 3 parts by weight of a stabilizer (ADEKA Corporation, product name SC320) using a dissolver to obtain a paste polyvinyl chloride sol.

The obtained paste vinyl sol was coated to a thickness of 0.3 mm on a PET film that had been heated at 180°C for 1 minute, and then heated at 180°C for 1 minute to create a sheet-shaped sample.

The obtained sheet-like sample was immersed in warm water at 23° C. for 3 days, after which the moisture was wiped off and the sample was dried. The haze was measured using a haze meter (Nippon Denshoku Industries Co., Ltd.) to evaluate resistance to devitrification and whitening.
The test results are shown in Table 1. The haze value was 33, the transparency was good, and the resistance to devitrification whitening and powder properties were excellent.

Comparative Example 1
Into a 2.5-liter autoclave were charged 500 g of deionized water, 800 g of vinyl chloride monomer, 9 g of a 5% aqueous solution of sodium lauryl sulfate, 85 g of seed 1, and 4 g of a 0.1% aqueous solution of copper sulfate. Thereafter, the temperature of this reaction mixture was raised to 48° C. to initiate polymerization, and a 0.05% by weight aqueous solution of ascorbic acid was continuously added throughout the entire polymerization time so as to maintain the polymerization temperature. The polymerization was terminated when the polymerization conversion rate reached 88%.

In addition, 120 g of a 5% aqueous solution of sodium lauryl sulfate was continuously added from the start of polymerization to the end of polymerization.

The unreacted monomers were then recovered to form a latex, to which 30 g of a 5% aqueous solution of sodium lauryl sulfate and 8 g of a 10% polyoxyalkylene lauryl ether were added to obtain a latex solution containing vinyl chloride resin particles. The mixture was then spray-dried in a spray dryer at a hot air inlet temperature of 158°C and an outlet temperature of 55°C to obtain vinyl chloride resin. The obtained vinyl chloride resin contained 0.1 parts by weight of polyoxyalkylene lauryl ether per 100 parts by weight of vinyl chloride resin with an average degree of polymerization of 1650. The powder characteristics were also poor, with an average particle size of 9.6 μm and a degree of cohesion of 58.1%.

100 parts by weight of the obtained vinyl chloride resin were mixed with 60 parts by weight of dioctyl phthalate (J-Plus Corporation, industrial grade) as a plasticizer and 3 parts by weight of a stabilizer (ADEKA Corporation, product name SC320) using a dissolver to obtain a paste vinyl chloride sol.

The obtained paste vinyl sol was coated to a thickness of 0.3 mm on a PET film that had been heated at 180°C for 1 minute, and then heated at 180°C for 1 minute to create a sheet-shaped sample.

The obtained sheet-like sample was immersed in warm water at 23° C. for 3 days, after which the moisture was wiped off and the sample was dried. The haze was measured using a haze meter (Nippon Denshoku Industries Co., Ltd.) to evaluate resistance to devitrification and whitening.
The test results are shown in Table 2. The haze value was 91.6, the transparency was also deteriorated, and the resistance to devitrification whitening and powder properties were poor.

Comparative Example 2
Into a 2.5-liter autoclave were charged 610 g of deionized water, 730 g of vinyl chloride monomer, 15 g of a 5% aqueous solution of sodium dodecylbenzenesulfonate, 85 g of seeds 1, and 4 g of a 0.1% aqueous solution of copper sulfate. Thereafter, the temperature of this reaction mixture was raised to 48° C. to initiate polymerization, and a 0.05% by weight aqueous solution of ascorbic acid was continuously added throughout the entire polymerization time so as to maintain the polymerization temperature. The polymerization was terminated when the polymerization conversion rate reached 88%.

In addition, 105 g of a 5% aqueous solution of sodium dodecylbenzenesulfonate was continuously added from the start of polymerization to the end of polymerization.

The unreacted monomers were then recovered to form a latex, to which 5 g of a 10% aqueous potassium laurate solution and 35 g of a 10% polyoxyalkylene lauryl ether were added to obtain a latex solution containing vinyl chloride resin particles. The solution was then spray-dried in a spray dryer at a hot air inlet temperature of 158°C and an outlet temperature of 55°C to obtain vinyl chloride resin. The obtained vinyl chloride resin contained 0.5 parts by weight of polyoxyalkylene lauryl ether per 100 parts by weight of vinyl chloride resin with an average degree of polymerization of 1650. The powder characteristics were also poor, with an average particle size of 6.4 μm and a degree of cohesion of 73.5%.

100 parts by weight of the obtained vinyl chloride resin were mixed with 60 parts by weight of dioctyl phthalate (J-Plus Corporation, industrial grade) as a plasticizer and 3 parts by weight of a stabilizer (ADEKA Corporation, product name SC320) using a dissolver to obtain a paste vinyl chloride sol.

The obtained paste vinyl sol was coated to a thickness of 0.3 mm on a PET film that had been heated at 180°C for 1 minute, and then heated at 180°C for 1 minute to create a sheet-shaped sample.

The obtained sheet-like sample was immersed in warm water at 23° C. for 3 days, after which the moisture was wiped off and the sample was dried. The haze was measured using a haze meter (Nippon Denshoku Industries Co., Ltd.) to evaluate resistance to devitrification and whitening.
The test results are shown in Table 2. The haze value was 98.0, the transparency was also deteriorated, and the resistance to devitrification whitening and powder properties were poor.

The vinyl chloride resin paste of the present invention can provide products that are excellent in resistance to devitrification and whitening, and is of great industrial value.

Claims (4)

A devitrification-resistant paste vinyl chloride resin comprising 100 parts by weight of a vinyl chloride resin having an average degree of polymerization of 1500 to 2000, 0.4 to 1.0 parts by weight of a sulfosuccinate surfactant, and 0.01 to 0.5 parts by weight of at least one nonionic surfactant selected from polyoxyalkylene alkyl ethers, the sulfosuccinate surfactant being a dipotassium sulfosuccinate surfactant and/or a disodium sulfosuccinate surfactant, and having a median diameter of 30 to 80 μm . The vinyl chloride resin paste according to claim 1, characterized in that the polyoxyalkylene alkyl ether is polyoxyalkylene lauryl ether. A molded article which is a sol molded product comprising the devitrification-resistant vinyl chloride resin paste according to claim 1 or 2. 4. The molded article according to claim 3, which is a flooring material, a sheet or a film.