JPH0554483B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to a method for producing a vinyl chloride graft copolymer. More specifically, the present invention relates to a method for producing an impact-resistant and weather-resistant vinyl chloride-based graft copolymer that has no skin on the particle surface, is highly porous, and has excellent processability. [Prior Art] Polyvinyl chloride is a useful resin with excellent physical properties and is used in a wide variety of fields ranging from hard to soft. However, when vinyl chloride homopolymers are used in hard applications, they have the disadvantage of poor impact resistance and weather resistance. As a method to improve these drawbacks, there is a polymer blend of vinyl chloride homopolymer and various elastic bodies, but this method can improve impact resistance, but it requires sufficient kneading. If mixing is insufficient, lumps may remain on the surface of the product.
There is a problem of reducing the value of the product. By graft copolymerizing vinyl chloride to an ethylene-vinyl ester copolymer, a vinyl chloride-based graft copolymer with excellent impact resistance and weather resistance can be obtained (Japanese Patent Publication No. 39-27876, Japanese Patent Application Laid-Open No. 1983-1999)
205415). However, although the vinyl chloride-based graft copolymer obtained by the above method is improved compared to polymer blends, the porosity is small even when the particle size is made fine, and there is a film on the particle surface. It has the disadvantage that it causes differences in gelation and tends to remain as lumps on the surface of the product. Furthermore, if sufficient kneading is performed to eliminate lumps, the impact resistance will be reduced, so there is also the drawback that the range of processing conditions is very narrow. As described above, all of the methods known to date tend to leave spots on the product surface, require extreme care when kneading the resin, and are also somewhat limited in their uses. [Problems to be Solved by the Invention] An object of the present invention is to provide a method for producing a vinyl chloride-based graft copolymer that has excellent impact resistance, weather resistance, and a product surface. [Means for Solving the Problems] In order to achieve the above object, the present inventors have made intensive studies and found that when graft copolymerizing vinyl chloride to an ethylene-vinyl ester copolymer, sorbitan Polymerization is initiated in the presence of a higher fatty acid ester dispersant and/or a polyvinyl alcohol dispersant with a degree of polymerization of 500 or less and a degree of saponification of 60 mol% or less, and once the polymerization has progressed to a certain extent, water-soluble dispersion is performed. By further adding the agent,
The inventors have discovered that it is possible to produce a vinyl chloride-based graft copolymer that has excellent impact resistance, weather resistance, and a product surface, leading to the present invention. That is, the present invention provides a method for graft copolymerizing an ethylene-vinyl ester copolymer with vinyl chloride or a mixture of a monomer copolymerizable with vinyl chloride and a sorbitan higher fatty acid ester dispersant. /or Start polymerization in the presence of a polyvinyl alcohol dispersant with a degree of polymerization of 500 or less and a degree of saponification of 60 mol% or less, and while the polymerization conversion rate is 5 to 40%, a water-soluble dispersant This is a method for producing a vinyl chloride-based graft copolymer that has excellent impact resistance, weather resistance, and a product surface. The ethylene-vinyl ester copolymer used in the present invention preferably contains 10 to 65% by weight as a vinyl ester component, more preferably 15 to 55% by weight, particularly 25 to 50% by weight. %
Preferably, those containing If the content of vinyl ester is less than 10% by weight, the compatibility will decrease, which is undesirable, and if it exceeds 65% by weight, the effect of impact resistance will decrease, which is not preferred. The molecular weight of the ethylene-vinyl ester copolymer is not particularly limited, but the melt index (JISK-6730) is preferably about 0.1 to 500 g/10 minutes. Examples of the vinyl ester copolymer in the ethylene-vinyl ester copolymer include vinyl acetate and vinyl propionate. Particularly suitable is vinyl acetate. Examples of polymerization methods for the ethylene-vinyl ester copolymer include suspension polymerization, emulsion polymerization, solution polymerization, and high-pressure polymerization, but when used in the present invention, the polymer obtained by any of the polymerization methods can be used. But it's okay. The appropriate amount of the ethylene-vinyl ester copolymer used in the present invention is 0.5 to 20 parts by weight per 100 parts by weight of the ethylene-vinyl ester copolymer and the vinyl chloride monomer. If the amount of ethylene-vinyl ester copolymer used is less than 0.5 parts by weight, impact resistance and weather resistance will be insufficient, and
Exceeding the weight part is not preferable because the rigidity decreases. As the monomer copolymerizable with vinyl chloride used in the present invention, α having 2 to 30 carbon atoms is used.
- Fatty acid vinyl esters such as olefin, vinyl acetate, and vinyl propionate, unsaturated fatty acids such as acrylic acid, methacrylic acid, maleic acid, fumaric acid, and crotonic acid, and their esters, and unsaturated acid anhydrides such as maleic anhydride. , unsaturated nitriles such as acrylonitrile and methacrylonitrile, alkyl vinyl ethers having 2 to 30 carbon atoms such as methyl vinyl ether and ethyl vinyl ether,
Examples include vinylidene chloride and styrene. When these monomers are copolymerized, the amount is preferably 10% by weight or less of the total amount of all monomers. Sorbitan higher fatty acid ester dispersants used as the dispersant of the present invention include sorbitan monolaurate, sorbitan monomyristate,
Sorbitan higher fatty acid esters such as sorbitan monopalmitate, sorbitan monostearate, sorbitan distearate, sorbitan tristearate, sorbitan monooleate, sorbitan sesquioleate, sorbitan trioleate, polyoxyethylene sorbitan monolaurate, polyoxy Ethylene sorbitan monomyristate, polyoxyethylene sorbitan monopalmitate, polyoxyethylene sorbitan monostearate, polyoxyethylene sorbitan distearate, polyoxyethylene sorbitan tristearate, polyoxyethylene sorbitan monooleate, polyoxyethylene sorbitan Examples include polyoxyethylene sorbitan higher fatty acid esters such as sesquioleate and polyoxyethylene sorbitan trioleate. The other dispersant is a polyvinyl alcohol dispersant with a degree of polymerization of 500 or less and a degree of saponification of 60 mol% or less, and one or both of the degree of polymerization and saponification is greater than these values. This is not preferable because the porosity of the resulting polyvinyl chloride decreases and the processability decreases. These dispersants may be used alone or in combination of two or more. Hereinafter, a sorbitan higher fatty acid ester-based dispersant and/or a polyvinyl alcohol-based dispersant having a degree of polymerization of 500 or less and a saponification degree of 60 mol% or less will be referred to as a sorbitan higher fatty acid ester-based dispersant. In any case, the amount of these dispersants used during the first stage polymerization is 0.05 to 0.05% of the vinyl chloride monomer.
5% by weight is suitable. Further, in the present invention, a water-soluble dispersant is used in addition to the above-mentioned sorbitan higher fatty acid ester dispersant during the production of polyvinyl chloride. Examples of water-soluble dispersants used include polyvinyl alcohol with a degree of polymerization of 700 or more and a degree of saponification of 75 mol% or more, methylcellulose, ethylcellulose, hydroxypropylmethylcellulose, hydroxyethylcellulose, gelatin, anhydrous maleic. Examples include acid-styrene copolymer and polyvinylpyrrolidone. These may be used alone or in combination of two or more. In the present invention, these water-soluble dispersants are preferably added when the polymerization conversion rate in the polymerization system reaches 5 to 40%, preferably 10 to 30%, and the amount used is the same as that of the vinyl chloride monomer. 0.02 to 1% by weight. A water-soluble dispersant may be used at the same time as the above sorbitan dispersant, or if the polymerization conversion rate of vinyl chloride is 5.
% to the polymerization system, the porosity decreases and processability decreases. In addition, if no water-soluble dispersant is added at all, or if it is added after the polymerization conversion rate exceeds 40%, a large amount of polymer scale may adhere to the inner wall of the polymerization machine or the polymerization dispersion system may become unstable. Coarse particles are formed and processability is reduced. When carrying out the graft copolymerization method of the present invention, the amount of water used is 1 to 5 times, preferably 1 to 3 times, relative to the total amount of ethylene-vinyl ester copolymer and vinyl chloride monomer. In the present invention, a known oil-soluble radical catalyst is used as a polymerization catalyst. For example, organic peroxides such as benzoyl peroxide, lauroyl peroxide, caproyl peroxide, diisopropyl peroxydicarbonate, di2-ethylhexyl peroxydicarbonate, tertiary butyl peroxypivalate, 2,2'-azobis Isobutyronitrile, 2,2'-azobis-
These are azo compounds such as 2,4-dimethylvaleronitrile, 2,2'-azobis-4-methoxy-2,4-dimethylvaleronitrile, or a combination thereof. The temperature of the polymerization reaction is preferably in the range of 40 to 70°C,
Further, a polymerization time of 5 to 15 hours is sufficient. In carrying out the present invention, a PH regulator, a chain transfer agent, etc. may be added. A method for obtaining a vinyl chloride graft copolymer (hereinafter referred to as a PVC graft copolymer) by a general suspension polymerization method is, for example, in a jacketed polymerization reactor, pure water and a sorbitan higher fatty acid ester dispersion. Add a radical polymerization initiator, a radical polymerization initiator, and a polymerization degree reducing agent if necessary, add an ethylene-vinyl ester copolymer (hereinafter referred to as EVa) and suspend it, then remove the air in the can, and then Press in vinyl chloride. Thereafter, the inside of the can is heated through the jacket to dissolve EVa in the vinyl chloride and initiate graft copolymerization. When the polymerization conversion rate reaches 5 to 40% after the start of polymerization, a water-soluble dispersant is introduced, and the graft copolymerization is continued under the same conditions. Graft copolymerization is an exothermic reaction, and the internal temperature is controlled by a jacket as necessary. After the reaction is complete, unreacted vinyl chloride is removed from the can to obtain a slurry of PVC graft copolymer. The slurry is dehydrated and dried according to a conventional method to obtain a PVC graft copolymer. In addition, the charging method to the polymerization reactor is not limited, and the other charging materials such as pure water, suspension stabilizer, EVa, and vinyl chloride are
A method of charging EVa after dissolving it in vinyl chloride is also adopted. The vinyl chloride graft copolymer obtained by the method of the present invention has high porosity and has no skin on the particle surface, so it can be easily broken down into single particles by kneading. In addition, since the gelation is uniform, there is little occurrence of fish eyes and the surface of the molded product is very clean. Therefore, the vinyl chloride graft copolymer obtained by the method of the present invention can be advantageously used for building materials, parts for electronic devices, audiovisual recording media, etc. As described above, the present invention provides a method for producing a high-quality vinyl chloride-based graft copolymer having unique particle characteristics, and its contribution is significant. [Example] Hereinafter, the present invention will be specifically explained with reference to Examples. Example 1 In a polymerization machine with an internal volume of 7 m ³ equipped with a stirrer, 3000 kg of deionized water, 30 kg of sorbitan monostearate (“Rheodol SP-510” manufactured by Kao Soap), and ethylene-vinyl acetate copolymer (manufactured by Mitsui Polychemical Co., Ltd.) were added. "Evaflex 450") 45kg, 0.4kg of 2,2'-azobisisobutyronitrile and 0.2kg of 2,2'-azobis-2,4-dimethylvaleronitrile were charged, and the air inside the machine was pumped out using a vacuum pump. After removal, 1455 kg of vinyl chloride was charged and stirred at 35℃ for 1 hour.
EVa was dissolved. Next, the temperature of the polymerization machine was raised to 57°C to start polymerization, and 2 hours after the start of polymerization (polymerization conversion rate: 15%), 200 kg of an aqueous solution in which 4 kg of hydroxypropyl methylcellulose was dissolved was injected under pressure. Polymerization was further continued under the same conditions, and 11 hours after the start of polymerization, the internal pressure of the polymerization machine decreased to 6.5Kg/ ^cm2 .
Unreacted vinyl chloride was collected. The contents were overdried to obtain 1210 kg of white powder. The average degree of polymerization of this graft copolymer according to JISK-6712 was 1050. As a result of analysis, the content of components other than vinyl chloride was 3.7%. Example 2 In Example 1, 225 kg of "Evaflex 310" manufactured by Mitsui Polychemical Co., Ltd. was used as the ethylene-vinyl acetate copolymer, the amount of vinyl chloride was reduced to 1275 kg, and a water-soluble dispersant was added under pressure 2 hours after the start of polymerization. Polymerization was carried out in the same manner as in Example 1, except that 8 kg of partially saponified polyvinyl alcohol having a saponification degree of 2000 and a saponification degree of 80 mol% was used. After 11 hours, the polymerization reaction was stopped and 1200 kg of white powder was obtained. The average degree of polymerization of this graft copolymer according to JISK-6712 was 1050. As a result of analysis, the content of components other than vinyl chloride was 18.8%. Example 3 In Example 1, 150 kg of "Evaflex 40" manufactured by Mitsui Polychemical Co., Ltd. was used as the ethylene-vinyl acetate copolymer, the amount of vinyl chloride was reduced to 1350 kg, and the degree of polymerization was changed by replacing it with sorbitan monostearate.
250, polyvinyl alcohol with saponification degree of 46 mol%
Except for using 20 kg, polymerization was carried out in the same manner as in Example 1, and the polymerization reaction was stopped after 10 hours and 30 minutes to obtain 1210 kg of white powder. The average degree of polymerization of this graft copolymer according to JISK-6712 was 1040. Further, as a result of analysis, the content of components other than vinyl chloride was 12.4%. Example 4 In Example 1, “Levabrene 450P” manufactured by West German Bayer AG was used as the ethylene-vinyl acetate copolymer.
Using 2,2'-azobis-2, 2,2'-azobis-2,
Without using 4-dimethylvaleronitrile, the water-soluble dispersant was 8 kg of partially saponified polyvinyl alcohol with a degree of polymerization of 2000 and a degree of saponification of 80 mol%, and the reaction temperature was
Polymerization was carried out in the same manner as in Example 1, except that the temperature was 64.5°C and the stopping pressure was 8.5Kg/ ^cm2 , and the polymerization was carried out for 10 hours.
The polymerization reaction was stopped after 30 minutes, and 1250 kg of white powder was obtained. The average degree of polymerization of this graft copolymer according to JISK-6712 was 830. Further, as a result of analysis, the content of components other than vinyl chloride was 7.2%. Example 5 In a polymerization machine with an internal volume of 7 m ³ equipped with a stirrer, 3000 kg of deionized water, 20 kg of polyvinyl alcohol with a degree of polymerization of 250 and a degree of saponification of 46 mol%, and an ethylene-vinyl acetate copolymer (Levaprene 450P manufactured by Bayer AG, West Germany) were added. )
After charging 30 kg, and removing the air inside the machine using a vacuum pump, 15 kg of 1-hexene and 1455 kg of vinyl chloride were charged, and the mixture was stirred at 38°C for 3 hours to dissolve the ethylene-vinyl acetate copolymer. Next, 2.5 kg of 2,2'-azobisisobutyronitrile and 1.5 kg of 2-mercaptoethanol were charged, and the internal temperature of the polymerization machine was raised to 63°C to start polymerization. Two hours after the start of polymerization (when the polymerization conversion rate reached 15%), 200 kg of an aqueous solution containing 8 kg of partially saponified polyvinyl alcohol having a degree of polymerization of 2000 and a degree of saponification of 80 mol % was injected. Polymerization was continued under the same conditions, and 13 hours after the start of polymerization, the internal pressure of the polymerization machine decreased to 6.0Kg/ ^cm2 .
Unreacted monomers were collected. When the contents were overdried, 1220 kg of white powder was obtained. The average degree of polymerization of this graft copolymer according to JISK-6712 was 480. Further, as a result of analysis, the content of components other than vinyl chloride was 3.4%. Comparative Example 1 Polymerization was carried out in the same manner as in Example 1 except that hydroxypropyl methylcellulose was added before the start of polymerization, and the polymerization reaction was stopped after 10.5 hours to obtain 1210 kg of white powder. The average degree of polymerization of this graft copolymer according to JISK-6712 was 1040. Further, as a result of analysis, the content of components other than vinyl chloride was 3.6%. Comparative Example 2 Polymerization was carried out in the same manner as in Example 1, except that hydroxypropyl methylcellulose was charged after 6 hours when the polymerization conversion rate reached 50%, and the polymerization reaction started after 11 hours. stop and
1200Kg of white powder was obtained. The average degree of polymerization of this graft copolymer according to JISK-6712 was 1050. As a result of analysis, the content of components other than vinyl chloride was 3.7%. Comparative Example 3 In Example 4, instead of polyvinyl alcohol with a degree of polymerization of 250 and a degree of saponification of 46 mol%, a degree of polymerization of 2000,
Polymerization was carried out in the same manner as in Example 4, except that 0.7 kg of partially saponified polyvinyl alcohol with a degree of saponification of 80 mol% and 0.7 kg of hydroxypropyl methyl cellulose were used, and the injection of the water-soluble dispersant was stopped.
After 10 hours and 30 minutes, the polymerization reaction was stopped and 1225 kg of white powder was obtained. The average degree of polymerization of this graft copolymer according to JISK-6712 was 850. As a result of analysis, the content of components other than vinyl chloride was 7.2%. Comparative Example 4 In Example 5, instead of polyvinyl alcohol with a degree of polymerization of 250 and a degree of saponification of 46 mol%,
2000, polymerization was carried out in the same manner as in Example 5, except that 0.7 kg of partially saponified polyvinyl alcohol with a degree of saponification of 80 mol% and 0.7 kg of hydroxypropyl methyl cellulose were used, and the injection of the water-soluble dispersant was stopped. After a period of time, the polymerization reaction was stopped and 1215 kg of white powder was obtained. The average degree of polymerization of this graft copolymer according to JISK-6712 was 490. As a result of analysis, the content of components other than vinyl chloride was 3.3%. The polymerization conditions of the PVC graft copolymers obtained in the above Examples and Comparative Examples are shown in Table 1, and various physical properties are shown in Table 2. In addition, various physical properties were measured according to the notes below. Note 1 Plasticizer absorption (porosity) Accurately weigh 5 g of resin into a glass filter with a roughness of G-2, and remove excess DOP from the resin.
Add plasticizer (approximately 10 c.c.) and mix well with a spatula. After that, excess DOP is separated using a centrifugal separator with a rotation speed of 5000 rpm, and the amount of DOP adsorbed by the resin is determined. DOP adsorption amount (phr) per 100 parts of resin. Note 2: 100 g of Fisher Eye Resin, 60 g of DOP, 5 g of ADVASTAB BC-1000J manufactured by Toa Rika (Cd-Ba heat stabilizer), and 0.1 g of carbon.
A sheet is prepared by heating two rolls at 21 rpm to 145°C and kneading for 5 minutes with a roll gap of 0.3 mm. After that, you can calculate the number of fisheyes that exist in an area of 15 x 10 cm. Note 3 Brabender Plastograph measurement conditions Kneader 50c.c. Number of rotations used 50rpm Temperature 150℃ Sample: Henschel resin 1kg T.S (tribasic lead sulfate) 20g, DBL (dibasic lead stearate) 10g, stearin Add 15g of acid lead,
Using 65g of powder stirred for 3 minutes 65g of powder was put into a 50c.c. kneader, preheated for 3 minutes, and gelation time was measured under a load of 10Kg.

【table】

〔Effect of the invention〕

The resin obtained according to the present invention has high porosity, low fixity eyes, short gelation time using Brabender plastograph, and excellent processability, so it can be used as building materials, parts for electronic devices, audiovisual recording media, etc. It can be suitably used in the field.

Claims (1)

[Claims] 1. When graft copolymerizing an ethylene-vinyl ester copolymer with vinyl chloride or a mixture of vinyl chloride as a main component and a monomer copolymerizable with it, (a) a sorbitan higher fatty acid ester dispersant and/or Polymerization degree is 500 or less and saponification degree is 60
Polymerization is initiated in the presence of a polyvinyl alcohol dispersant of mol % or less, and (b) the polymerization conversion rate is 5.
1. A method for producing a vinyl chloride-based graft copolymer with excellent processability, characterized in that a water-soluble dispersant is added within a range of 40% to 40%.