JPS621405B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing a vinyl chloride resin having improved physical properties, and more specifically, the vinyl chloride resin has a secondary transition point of -10°C.
When graft copolymerizing the following alkyl acrylates and/or alkyl methacrylates, by coexisting acrylonitrile, the physical properties and moldability are improved, and the 100% modulus is 300 Kg/cm ² or less, and the tensile strength is 100 Kg/cm 2 or less.
Relates to a method for producing flexible vinyl chloride resin of kg/cm ² or more. Vinyl chloride resin has excellent physical and mechanical properties, so it has many uses such as hard, semi-hard, and soft. In order to obtain a vinyl chloride molded product that is flexible and elastic at room temperature, a plasticizer such as a phthalate ester or an adipate ester is generally blended with the vinyl chloride resin. However, in soft vinyl chloride compositions that are externally plasticized with a plasticizer, the plasticizer volatilizes or migrates, and although vinyl chloride resin is originally a flame-retardant resin, it contains a flammable plasticizer. However, there were drawbacks such as a decrease in flame retardancy. As a method of improving these drawbacks of softened vinyl chloride resins, a number of internally plasticized vinyl chloride resins have been studied. For example,
As seen in Japanese Patent Publication No. 39-27875, examples include vinyl chloride graft copolymer resins in which vinyl chloride is graft copolymerized onto ethylene/vinyl acetate copolymer resins. However, vinyl chloride graft copolymer resin, which is made by graft copolymerizing vinyl chloride onto ethylene vinyl acetate copolymer resin, does not necessarily have sufficient flexibility and strength characteristics, and has poor chemical resistance, especially oil resistance. There are fatal drawbacks such as this, which limits practical use. The present inventors first aimed to obtain an internally plasticized vinyl chloride resin having improved properties without impairing the excellent physical and mechanical properties of conventional externally plasticized vinyl chloride resin. As a result of detailed studies, we found that by graft copolymerizing vinyl chloride resin with alkyl acrylate whose alkyl group has 1 to 4 carbon atoms, the 100% modulus is 300 kg/cm ² or less and the tensile strength is It was discovered that it was possible to obtain a flexible vinyl chloride resin with a strength of 100 kg/cm ² or more, which significantly improved the properties of conventional flexible vinyl chloride resins, and patent application No. 53-93160 disclosed the invention method. I applied. It is true that a flexible vinyl chloride resin having the above characteristics can be obtained by graft copolymerizing a vinyl chloride resin with an alkyl acrylate whose alkyl group has 1 to 4 carbon atoms. However, this resin had the drawback of poor cold resistance when graft copolymerized with an alkyl acrylate whose polymer had a secondary transition point higher than -10°C. Furthermore, in the method of Japanese Patent Application No. 53-93160, especially when an alkyl acrylate whose alkyl group has two or more carbon atoms is graft copolymerized, the surface of the resin and its molded product becomes sticky. It had the drawback of so-called stickiness. Furthermore, since vinyl chloride resin and alkyl acrylate resin originally have poor mutual compatibility with this resin,
It had the disadvantage of poor moldability. When a graft copolymer resin obtained by simply graft copolymerizing a vinyl chloride resin with an alkyl acrylate is produced into a sheet by roll kneading, for example, a beautiful sheet with a smooth surface cannot be obtained. As a result of repeated studies in order to overcome the various drawbacks mentioned above, the present inventors have found that alkyl acrylate and/or alkyl methacrylate whose polymer has a secondary transition point of -10°C or less has been added to vinyl chloride resin. In graft copolymerizing, by coexisting acrylonitrile,
Improved cold resistance, adhesion, and moldability, 100%
Modulus is 300Kg/ ^cm2 or less and tensile strength is
It was discovered that a flexible vinyl chloride resin with a weight of 100 kg/cm ² or more can be obtained, and the properties of conventional flexible vinyl chloride resins can be significantly improved, leading to the completion of the present invention. That is, in the present invention, vinyl chloride resin is used as a backbone polymer, and alkyl acrylate and/or alkyl methacrylate and acrylonitrile, which have a secondary transition point of the polymer of -10°C or less, are used as branch polymers to achieve internal A method for producing a plasticized vinyl chloride graft copolymer resin is provided. The vinyl chloride resin to be the backbone polymer of the graft copolymer resin used in the present invention is a vinyl chloride resin obtained by homopolymerization of vinyl chloride,
Copolymer resins of vinyl chloride and other copolymerizable monomers, or graft copolymer resins of vinyl chloride and other resins are included, but vinyl chloride alone obtained by homopolymerization of vinyl chloride Resin is practically preferred. In addition, vinyl chloride resin can be polymerized by suspension polymerization, bulk polymerization,
It may be produced by any emulsion polymerization method, and may be in the form of a powder or a slurry dispersed in a medium. As will be described later, in the present invention, graft copolymerization is preferably carried out in a suspended state, so it is desirable that the backbone polymer be produced by a suspension polymerization method. The degree of polymerization of the vinyl chloride resin to serve as the backbone polymer is suitably 500 to 5,000, preferably 800 to 1,500. In the present invention, an alkyl acrylate and/or alkyl methacrylate whose polymer has a secondary transition point of -10°C or lower is used for graft copolymerization. Examples of the alkyl acrylate and alkyl methacrylate whose homopolymer has a secondary transition point of -10°C or lower include ethyl acrylate, n-propyl acrylate, iso-butyl acrylate, n-butyl acrylate, n-hexyl acrylate, 2-ethylhexyl acrylate, n-octyl acrylate, n-decyl acrylate and n-octyl methacrylate,
Examples include n-decyl methacrylate, n-dodecyl methacrylate, and lauryl methacrylate. These can be used alone or in combination with other alkyl acrylates and alkyl methacrylates. When used as a mixture, the composition of the mixture is determined so that the secondary transition point of the polymer in the mixture is −10° C. or less according to the following formula. 1/Tg=W ₁ /T ₁ +W ₂ /T ₂ +W ₃ /T ₃
+... However, Tg: Secondary transition point of the polymer in the mixture (〓) W ₁ , W ₂ , W ₃ ...: Weight fraction of specific monomer in the polymer mixture T ₁ , T ₂ , T ₃ ...: The second-order transition point of the homopolymer made of the monomer (〓) In this way, the second-order transition point of the polymer is -
By using alkyl acrylate and/or alkyl methacrylate below 10℃,
The cold resistance of the resulting vinyl chloride graft copolymer resin is significantly improved. In the present invention, n-butyl acrylate is particularly advantageously used. In carrying out the present invention, the amount of alkyl acrylate and/or alkyl methacrylate used is not particularly limited, and the 100% modulus of the obtained graft copolymer resin is 300 Kg/cm ² or less and the tensile strength is 100 Kg/cm. Although it is sufficient if there are ^two or more, 35 to 900 parts by weight of alkyl acrylate and/or alkyl methacrylate are used with respect to 100 parts by weight of vinyl chloride resin.
The optimum amount used is determined by the strength properties and processability of the final vinyl chloride graft copolymer resin. In the present invention, the graft copolymerization of the alkyl acrylate and/or alkyl methacrylate is carried out in the coexistence of acrylonitrile. By graft copolymerizing an alkyl acrylate and/or alkyl methacrylate whose secondary transition point is -10°C or lower,
Although a flexible vinyl chloride graft copolymer resin can be obtained, it alone lacks tensile strength.
Moreover, as mentioned above, fatal defects in adhesiveness and moldability occur. The present inventors have discovered that when graft copolymerizing an alkyl acrylate and/or alkyl methacrylate whose polymer has a secondary transition point of -10°C to a vinyl chloride resin,
It has been discovered that when acrylonitrile is coexisting, the tensile strength is greatly improved, and the adhesion and moldability are surprisingly improved. If we consider alkyl acrylate and/or alkyl methacrylate whose polymer has a secondary transition point of −10°C or lower as a soft segment, and consider acrylonitrile as a hard segment, the explanation that tensile strength is improved by the introduction of acrylonitrile is It is possible. However, the fact that the introduction of acrylonitrile surprisingly improves adhesion and moldability is a completely unexpected discovery.
The present inventors are also unable to academically elucidate the reason. In the present invention, the amount of acrylonitrile used is not particularly limited, and the 100% modulus of the obtained graft copolymer resin is 300 kg% cm ² or less,
It is sufficient if the tensile strength is 100 kg/ ^cm2 or more, but the above objective can be achieved by coexisting with the resin in an amount of 2-50 parts by weight, preferably 2-30 parts by weight, based on 100 parts by weight of vinyl chloride resin. It will be done. If it is less than 2 parts by weight, the above effect will be small, and if it exceeds 50 parts by weight, the resulting graft copolymer resin will lose its flexibility and cold resistance. The optimum amount used is determined by the strength properties and processability of the final vinyl chloride graft copolymer resin. In the graft copolymerization, other monomers may be present in the coexistence within the range of the above-mentioned mechanical properties. In carrying out the present invention, it is advantageous to carry out the graft copolymerization by a radical polymerization method, and the radical polymerization initiators used for this purpose include lauroyl peroxide, tert-butyl peroxypivalate, diisopropyl peroxydi carbonate, organic peroxides such as dioctyl peroxydicarbonate, 2,2'-azobisisobutyronitrile, 2,2'-azobis-2,
Examples include oil-soluble polymerization initiators such as azo compounds such as 4-dimethylvaleronitrile, and water-soluble polymerization initiators such as potassium persulfate and ammonium persulfate. The amount of these polymerization initiators used is preferably 0.005 to 1.0 parts by weight per 100 parts by weight of vinyl chloride resin. Alternatively, as another means, graft copolymerization by radiation irradiation may be performed. Examples of the polymerization method of the present invention include an aqueous suspension polymerization method, an aqueous emulsion polymerization method, a solution polymerization method, and a solvent-free polymerization method. However, in order to carry out the present invention advantageously, an aqueous suspension polymerization method is adopted. This is desirable. When carrying out an aqueous suspension polymerization method, the ratio of (vinyl chloride resin as the backbone polymer + alkyl acrylate and/or alkyl methacrylate + acrininitrile) to water is 1:1 to 1:5, preferably 1:1 to 1. :3. Suspension stabilizers may be used in this case, and they may be those commonly used in the polymerization of vinyl chloride, such as polyvinyl alcohol and its partially saponified products, methylcellulose, starch, gelatin, etc., used alone or in combination. , the amount added is 0.01 to 1.0 per 100 parts by weight of vinyl chloride resin.
Parts by weight. Furthermore, in the present invention, a chain transfer agent used in conventional methods for polymerizing vinyl monomers may be added in an amount of 0.001 to 10 parts by weight per 100 parts by weight of vinyl chloride resin. For the purpose of increasing the grafting efficiency, compounds having a swelling effect on the vinyl chloride resin, such as ketones, may be freely added. The reaction temperature for graft copolymerization is preferably in the range of 30 to 100°C. If the reaction temperature is less than 30°C, the reaction rate of graft copolymerization will be slow, while if the reaction temperature exceeds 100°C, the vinyl chloride resin will deteriorate. The reaction time is determined by the type and amount of the polymerization initiator used and the reaction temperature, but in the present invention it is adjusted so that the reaction is completed in 1 to 10 hours. The reaction vessel used for graft copolymerization is preferably a stainless steel or glass-lined autoclave equipped with a stirrer, and may also be equipped with a backflow condenser for auxiliary heat removal. The interior of the reaction vessel must be an inert gas atmosphere that does not contain oxygen. In the graft copolymerization, the alkyl acrylate and/or alkyl methacrylate and acrylonitrile may be charged all at once, or may be charged in portions or continuously. After the graft copolymerization reaction has been completed, the slurry is dehydrated and dried after recovering unreacted monomers in a conventional manner. The graft copolymer resin obtained by the method of the present invention can be easily processed by ordinary molding processes by adding heat stabilizers, lubricants, processing aids, antioxidants, etc. It is possible to obtain a soft and elastic vinyl chloride molded product without adding a plasticizer. In this case, for the purpose of further improving the physical and mechanical properties, a small amount of plasticizer, chlorinated polyethylene, ethylene-vinyl acetate copolymer resin, acrylic rubber, nitrile rubber, etc. may be blended. Furthermore, general fillers and heat retardants can be added freely. The present invention will be specifically explained below with reference to Examples, in which parts shown are parts by weight. Examples 1 to 2 and Comparative Examples 1 to 4 Graft copolymerization was carried out using a suspension polymerized vinyl chloride resin with a degree of polymerization of 1050 as a backbone polymer according to the polymerization recipe shown in Table 1. i.e. internal volume 10
The raw materials shown in Table 1 were charged into a stainless steel autoclave, and the air inside was replaced with nitrogen.
After reacting at 80° C. for 3 hours, unreacted molymer was removed from the reaction product, which was dehydrated and dried to obtain a powdery graft copolymer resin. Table 1 shows Example and Comparative Example numbers in the horizontal direction, and reaction conditions and characteristic values of the obtained graft copolymer resin in the vertical direction. These characteristic values are the results of measurements on the following samples. That is, 3.0 parts of tribasic lead sulfate and 1.0 parts of dibasic lead stearate were mixed with 100 parts of the obtained graft copolymer resin, kneaded for 5 minutes with hot rolls at 160°C, and then heated with a hot press at 180°C. A sheet was prepared by pressing the sheet for 5 minutes, and measurements were taken on a sample taken from this sheet. For further comparison, 100 parts of suspension polymerized vinyl chloride resin with a degree of polymerization of 1050 was added with dioctyl phthalate.
40 parts of lead tribasic sulfate, 3.0 parts of tribasic lead sulfate, and 1.0 part of dibasic lead stearate were mixed and externally plasticized in the same manner as above to prepare a sheet, which is listed in Table 1 as Comparative Example 4. As can be seen from Table 1, the alkyl acrylate of the polymer of the present invention whose secondary transition temperature is -10°C or lower (-54°C in Example 1 and -76°C in Example 2) is added to acrylonitrile. The graft copolymer resin grafted to vinyl chloride resin in coexistence is a flexible resin with a 100% modulus of 300 Kg/cm ² or less and a tensile strength of 100 Kg/cm ² or more,
The rolled sheet has a good surface condition, is non-sticky, and has excellent cold resistance. However, in Comparative Example 1, which was grafted with methyl acrylate whose polymer has a secondary transition point higher than -10°C, the surface of the roll sheet was uneven, indicating that the moldability of the graft copolymer resin was poor, and the cold resistance was poor. Sex is also extremely bad. Further, in Comparative Example 3 in which methyl acrylate was grafted in the presence of acrylonitrile, the surface condition of the roll sheet was improved, but the cold resistance was still not improved. In Comparative Example 2, in which only n-butyl acrylate whose secondary transition point is -54°C was grafted, the graft copolymer resin had excellent cold resistance but lacked tensile strength, and the roll sheet The surface was uneven and sticky.

[Table] Example 3 100 parts of suspension polymerized vinyl chloride resin with a degree of polymerization of 1050,
100 parts of n-decyl methacrylate whose polymer has a secondary transition point of -70°C, 10 parts of acrylonitrile,
300 parts of pure water, 0.05 hydroxymethyl cellulose
parts, 0.3 parts of lauroyl peroxide, internal volume
10 stainless steel autoclaves, and the air inside was replaced with nitrogen. After reacting at 80° C. for 3 hours, unreacted monomers were removed from the reaction product, which was dehydrated and dried to obtain a powdery graft copolymer resin. The reaction rate was 98%. A sheet was prepared using the obtained graft copolymer resin in the same manner as described in Example 1, and its characteristic values were measured. The obtained rolled sheet had a good surface condition and no stickiness. The 100% modulus was 160 Kg/cm ² , the tensile strength was 180 Kg/cm ² and the elongation was 130%. Moreover, the cold resistance was -20℃.

Claims (1)

[Claims] 1 Add alkyl acrylate and/or acrylic methacrylate whose polymer has a secondary transition point of -10°C or lower to 100 parts by weight of vinyl chloride resin.
35 to 900 parts by weight for graft copolymerization,
A method for producing a flexible vinyl chloride resin having improved physical properties, adhesiveness and moldability, and having a well-balanced 100% modulus value and tensile strength, characterized by the coexistence of 2 to 50 parts by weight of acrylonitrile.