JPH0342301B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a vinyl chloride resin composition having improved properties, and more particularly, it relates to a vinyl chloride resin composition containing a specific modified vinyl acetate/ethylene copolymer resin for molding workability, non-stick properties, and non-stick properties. This invention relates to a resin composition with excellent water absorption properties. [Prior art and its problems] Vinyl chloride resin (hereinafter abbreviated as PVC) has excellent mechanical, electrical, and chemical properties, and is relatively inexpensive, so it is widely used in hard and soft fields as well as foaming. It is widely used as a body. Particularly in the field of soft materials and foams, large amounts of plasticizers are blended and used to take advantage of their suitability for various uses such as films, canvas, leather, sponges, electric wires, and daily necessities. However, when a large amount of plasticizer is added to PVC,
There are drawbacks such as poor durability due to extraction, migration, and volatilization of the plasticizer, and a decrease in physical properties and processability due to heating. to compensate for these shortcomings
NBR (acrylonitrile butadiene rubber),
Addition of highly polar rubber/polymer such as chlorinated polyethylene or vinyl acetate/ethylene copolymer resin (hereinafter abbreviated as VAE) may be considered, but NBR
has poor weather resistance because it has unsaturated bonds;
In addition, chlorinated polyethylene does not have sufficient heat coloring resistance or the effect of suppressing the migration, extraction, and volatilization of liquid plasticizers, and furthermore, even in VAE, if the ethylene content is high, the compatibility with PVC is low, making it difficult to use in practice. The drawback is that they cannot be mixed. On the other hand, VAE with a low ethylene content has excellent compatibility with PVC, and VAE itself acts as a type of polymer with non-migration, non-extractability, and non-volatile properties, and is useful in the field of soft materials, foams, and even as a processability improver. It is also used in hard fields. VAE with such a low ethylene content can be synthesized by bulk polymerization, solution polymerization, suspension polymerization, and emulsion polymerization, but suspension polymerization and emulsion polymerization are carried out on an industrial scale due to economic efficiency in equipment and process costs. Compared to suspension polymerization, VAE produced by emulsion polymerization has advantages such as higher mechanical strength and filler filling capacity because it produces products with higher molecular weights, and is also more effective in suppressing the migration of liquid plasticizers. It is blended with PVC and put into practical use as canvas fabrics, waterproof sheets, flooring materials, wire covering materials, processability improvers, and cell stabilizers for foams. However, the emulsion polymerization method VAE requires a step to extract the polymer from the latex. Generally, salting out is performed by adding a flocculant such as an inorganic salt or acid,
Subsequently, the polymer must be washed to remove impurities such as flocculants and emulsifiers from the polymer. However, VAE with low ethylene content is highly sticky above room temperature.
Due to its tendency to fuse, it was very difficult to precipitate the polymer as particles from VAE latex and wash, dehydrate, and dry it. Therefore, for example, Japanese Patent Publication No. 47-36010 proposes a method of adding fine powder of an inorganic substance to VAE latex and then salting it out to prevent the precipitated polymer particles from bonding with each other. However, even with this method, salting out agents, emulsifiers, inorganic fine powders, etc. that remain in the polymer cause problems.
There were problems in terms of the transparency, non-water absorbency, non-adhesiveness, etc. of the PVC composition being impaired, as well as processing problems such as poor dry blendability during high-speed stirring and mixing. [Means for Solving the Problems] The present inventors have investigated the volatilization, migration, and
The non-adhesive property of the composition without impairing the property of suppressing extraction, etc., filler filling property, molding processability, etc.
As a result of our earnest efforts to obtain a composition with improved non-water absorbing properties and dry blendability during high-speed stirring and mixing, we have found that there are problems when adding a polar vinyl monomer to VAE latex obtained by emulsion polymerization and performing graft polymerization. Modification obtained by completing the reaction in a turbid system
It was discovered that a PVC composition containing VAE has a surprising improvement effect in terms of non-water absorption, non-adhesiveness, and dry blendability during high-speed stirring and mixing.
This led to the present invention. That is, the present invention can reduce the vinyl acetate content by emulsion polymerization.
A vinyl monomer with a solubility coefficient of 8.5 to 15 as a salting out agent is added to a latex of organic peroxide-free vinyl acetate/ethylene copolymer with an ethylene content of 90 to 50% by weight and an ethylene content of 10 to 50% by weight. 1 to 150 parts by weight of a modified vinyl acetate/ethylene copolymer obtained by adding the vinyl monomer to a suspended state and then suspension polymerizing the vinyl monomer to 100 parts by weight of a vinyl chloride resin. The present invention provides a vinyl chloride resin composition characterized by the following. The PVC composition of the present invention can be used without impairing the effect of suppressing migration, extraction and volatilization of liquid plasticizer, filler filling ability, molding processability, etc., which PVC compositions containing emulsion polymerized VAE have. polymerization
The problems of VAE, such as non-water absorption, non-adhesiveness, dry blendability during high-speed stirring and mixing, and heat resistance, have been significantly improved. The modified VAE used in the present invention is a relatively high molecular weight polymer synthesized by emulsion polymerization as a backbone polymer.
Using VAE lux, adding a highly polar vinyl monomer to it and placing it under graft polymerization conditions, and completing the polymerization by inverting the phase of the reaction system from an emulsion system to a suspension system without using a salting out agent. Since the modified VAE is obtained in the form of beads, the polymer can be easily washed, dehydrated, and dried.
By blending it with PVC, the effects of the present invention can be obtained. The VAE is 10-50% by weight of ethylene, preferably
It is a VAE latex having a Mooney viscosity of 5 to 60. The vinyl monomer has a solubility coefficient of 8.5 to 15,
Preferably, one is selected so that the solubility coefficient of the modified VAE obtained by polymerization is 8.5 to 9.5.
The amount of vinyl monomer added is usually 5 to 50% of the modified VAE.
50% by weight, preferably 10-40% by weight. still,
Solubility coefficient is from Encyclopedia of Polymer
Science and Technology (Wiley-Inter-
These are the solubility coefficient values of each monomer and polymer according to Science, Inc.). In the case of multiple components, calculation is performed assuming additivity. The characteristic values of the vinyl monomer for the above-mentioned modified VAE are determined from the balance of processability, physical properties, etc. of the PVC composition, and if the ethylene content of the VAE is less than 10% by weight, the plasticity of the PVC composition The effect of improving filler filling properties and the like is not sufficient, and if it exceeds 50% by weight, the compatibility with PVC deteriorates, and the transparency, processability, etc. of the PVC composition decreases. The VAE latex is obtained by emulsion polymerization from ethylene and vinyl acetate, and usually has a particle size of 10 μm or less. of the present invention
A copolymer latex of vinyl ester and ethylene or a copolymer latex of acrylic ester and ethylene, which exhibit properties similar to those of VAE, may be used in place of VAE. Examples of such vinyl esters include vinyl formate, vinyl propionate,
Examples include vinyl pivalate and vinyl versatate, and acrylic acid esters include methyl acrylate and ethyl acrylate. Furthermore, up to half of the vinyl acetate may be replaced with other vinyl monomers, and other polymers and polymer latexes may be used in combination with the VAE latex, as long as the object of the present invention is not impaired. If the solubility coefficient of the above-mentioned vinyl monomer is lower than 8.5, the phase inversion from VAE latex to suspension system will not be carried out smoothly, and the compatibility with PVC will decrease, resulting in poor transparency and processability of the composition. descend. Furthermore
When it is higher than 15, the compatibility with PVC decreases, and the transparency and processability of the composition decrease. Examples of these vinyl monomers include acrylic acid such as methyl acrylate, ethyl acrylate, and methyl methacrylate, methacrylic acid and its alkyl esters, aromatic vinyl such as styrene and α-methylstyrene, and halogenated vinyl such as vinyl chloride. Examples include vinyl, vinyl esters such as vinyl acetate, and vinyl cyanides such as acrylonitrile, and these may be used in combination. The amount of vinyl monomer added is usually 5 to 50% of the amount of modified VAE, from the viewpoint of non-water absorption, non-adhesiveness, and mechanical strength of the PVC composition.
50% by weight, preferably 10-40% by weight. Further, a chain transfer agent such as dodecylmercabutane may be used in combination to adjust the degree of polymerization. The VAE latex used to produce the modified VAE is synthesized by a known method, for example, in the same manner as in Japanese Patent Publication No. 47-3732. Furthermore, modified VAE can be obtained by adding a vinyl monomer and a radical initiator to VAE latex and performing a kind of graft polymerization, and can be synthesized, for example, by the following method. After adding dispersants used in suspension polymerization to VAE latex, such as organic dispersants such as polyvinyl alcohol, polyvinylpyrrolidone, and methyl cellulose, and inorganic dispersants such as calcium phosphate, calcium carbonate, and magnesium oxide, vinyl monomers are added. The decomposition temperature is 50~50 to obtain an additional 10 hour half-life.
Polymerization is carried out by adding 0.1 to 5 parts by weight of a radical initiator at 130°C per 100 parts by weight of vinyl monomer.
Such radical initiators include benzoyl peroxide, azobisisobutyronitrile, t
-butylperoxybenzoate, t-butylperoxy (2-ethylhexanoate), di-isopropylperoxycarbonate, t-butylperoxypiparate, t-butylperoxyisopropyl carbonate, t-butyllauryl peroxide, etc. be. Phase inversion from an emulsion system to a suspension system is carried out by adding a vinyl monomer, but the phase inversion may also be carried out as the polymerization progresses, using a small amount of a highly polar organic solvent or inorganic salt. Good too. A vinyl monomer may be grafted, and the polymerization temperature is generally 60 to 130°C. The produced modified VAE is separated by simply stopping stirring, thoroughly washed with water, etc., and then dried. At this time, an anti-blocking agent may be added.
Examples of anti-blocking agents include organic and inorganic compounds such as wax, polyethylene powder, silicone oil, silica, calcium carbonate, magnesium oxide, fatty acid salts such as calcium stearate, and the like. In the present invention, PVC refers to homopolymers of vinyl chloride and monomers copolymerizable with vinyl chloride, such as vinyl esters such as vinyl acetate, olefins such as ethylene; acrylic acid, methacrylic acid and their alkyl esters; vinylidene chloride, etc. A copolymer with vinyl chloride containing 30% by weight or less of a compound of the above, and a graft copolymer in which vinyl chloride is added to ethylene/vinyl acetate, chlorinated polyethylene, or thermoplastic polyurethane can also be used. The composition of the present invention is modified based on 100 parts by weight of PVC.
It has improved properties by blending 1 to 150 parts by weight of VAE, and if the modified VAE is less than 1 part by weight, it may prevent sticking to molding machines (so-called plate-out prevention effect). )
If the amount exceeds 150 parts by weight, the molded product may not have sufficient strength as a PVC composition. This is not desirable because it is not possible to obtain The composition of the present invention includes stabilizers, pigments, ultraviolet absorbers, processability improvers, lubricants, plasticizers, impact modifiers,
Flame retardants, crosslinking agents, blowing agents, and other additives can be added as necessary. Molding of the composition of the present invention is carried out using conventional roll, calender, extrusion, injection molding, and the like. [Effects of the invention and industrial fields of application] As explained above, the PVC composition of the present invention has excellent mechanical strength, filler filling properties, moldability, non-stickiness and non-water absorption of molded products, and high-speed stirring. It has excellent dry blendability during mixing, and has excellent properties such as suppressing migration, extraction, and volatilization when a large amount of plasticizer is blended, so it is suitable for food hoses, flexible containers, clothing, leather, drawn fabrics, daily necessities, etc. It can be used in a wide variety of applications such as electric wire covering materials and waterproof sheets. [Example] The present invention will be specifically described with reference to Examples, Comparative Examples, and Reference Examples. Note that all parts and percentages are parts by weight and percentages by weight. Reference example 1 (Production of modified VAE) Sodium lauryl sulfate 1.5%, methyl cellulose
4 parts of calcium phosphate and distilled water are added to 200 parts of latex polymerized in an emulsifying system containing 0.3% VAE (41% ethylene content) to form an aqueous dispersion with a solids content of 20%, and benzoyl peroxide is added to this.
50 parts of methyl methacrylate (solubility coefficient: 9.4) in which 1.0 part was dissolved was added at room temperature and kept stirring for 1 hour to absorb the vinyl monomer into the latex particles. Subsequently, the temperature was raised to 75°C and reacted for 4 hours, and the temperature was further raised to 90°C and maintained for 2 hours. When the temperature was lowered and stirring was stopped, bead-shaped precipitates with a particle size of 0.2 to 0.5 mm were obtained, which were washed with water and dried.
A modified VAE of 238 parts was obtained. Reference Example 2 (Same as above) 30 parts of ethyl acrylate and acrylonitrile in which 0.8 parts of benzoyl peroxide was dissolved instead of 50 parts of methyl acrylate in Reference Example 1.
A bead-shaped precipitate with a particle size of 0.1 to 0.3 mm was obtained in the same manner as in Reference Example 1, except that 10 parts of the mixture (solubility coefficient 10.65) was used, and the mixture was washed with water and dried to produce 225 parts of modified VAE.
I got it. Reference Example 3 (Same as above) Same as Reference Example 1 except that VAE (ethylene content 31%) was used instead of VAE (ethylene content 41%) and methyl acrylate was used instead of methyl methacrylate. 241 parts of modified VAE were obtained. Reference Example 4 (Manufacture of unmodified VEA) 200 parts of the VAE latex from Reference Example 1 was added little by little to a 20% calcium chloride aqueous solution kept at 70°C to coagulate and separate the polymer.The resulting polymer was washed with water and dried. and obtained a VAE of 195 copies. Reference Example 5 (Production of modified VAE by emulsion polymerization) 50 parts of methyl methacrylate emulsified with 75 parts of an aqueous solution containing 1.9 parts of sodium lauryl sulfate and 0.4 parts of methyl cellulose was added to 200 parts of the VAE latex of Reference Example 1, and Add 0.5 part of sodium bisulfite, raise the temperature to 75°C, and add 5% of potassium persulfate.
30 parts of the aqueous solution was added dropwise over a period of 4 hours. The obtained modified VAE latex was coagulated with polymer in the same manner as in Reference Example 4, washed with water, and dried, and 215 parts of modified VAE latex was added.
Got VAE. Reference Example 6 (Manufacture of unmodified EVA) In a magnetically stirred autoclave with an internal volume of 2, 160 parts of vinyl acetate, 800 parts of distilled water, 1.6 parts of azobisisobutyronitrile (radical initiator), and polyvinyl alcohol (dispersant) were placed. ) and 0.8 parts of sodium polyacrylate (dispersant), then the air in the autoclave was replaced with nitrogen and ethylene, the internal temperature was raised to 65°C, and ethylene was added to 75°C.
Suspension polymerization was carried out for 8 hours under pressure up to kg/cm ² . When the temperature was lowered and stirring was stopped, the particle size was 0.5 to 1.
A bead-like precipitate of 1.0 mm in size was obtained, which was washed with water and dried to obtain 165 parts of suspension polymerized VAE. Analysis revealed that the ethylene content was 35% and the Mooney viscosity was 3. Example 1 3000 parts of PVC with an average degree of polymerization () 1300, Ba-Zn
90 parts of a composite stabilizer (Gretzk M-179, manufactured by Dainippon Ink and Chemicals) were added to a super mixer (inner volume 20
After homogeneous mixing at 800 rpm for 2 minutes, 1500 parts of DOP (dioctyl phthalate, manufactured by Dainippon Ink & Chemicals) was added over 30 seconds while stirring. Thereafter, the rotation speed was increased to 1800 rpm, and after the resin temperature rose to 120° C., 360 parts of the modified VAE of Reference Example 1 was added with stirring. After addition 3
Continue stirring at 1800rpm for 1 minute, then reduce the rotation speed.
The speed was reduced to 800 rpm and the mixture was removed. Final resin temperature was 132°C. The dry blendability during high-speed stirring was thereby evaluated. The results are shown in Table 1. Example 2 In Example 1, the rotation speed of the super mixer was
The same procedure as in Example 1 was carried out except that the rpm was increased from 1800 rpm to 2500 rpm and the resin temperature at the time of addition was 140°C.
The evaluation results are shown in Table 1. Comparative Examples 1 to 6 Comparative Examples 1 are those in which the VAE of Reference Example 4 was used instead of the modified VAE of Reference Example 1 in Example 1,
Comparative Example 2 used the modified VAE of Reference Example 5, and Comparative Example 3 used the VAE of Reference Example 6. In addition, in Example 2, the modification of Reference Example 1
Comparative Example 4 uses the VAE of Reference Example 4 instead of VAE, Comparative Example 5 uses the modified VAE of Reference Example 5, and Comparative Example 6 uses the VAE of Reference Example 6. carried out. The evaluation results are shown in Table 1. As is clear from the results in Table 1, the modification of the present invention
PVC compositions using VAE have no stickiness even when added at high temperatures of 120 to 140°C, and are white and uniform powders containing no pellets. By being able to form a uniform powder over a wide temperature range, there is no so-called bridging phenomenon at the hopper feeding section during extrusion molding or injection molding, and the resin composition can be fed uniformly. Example 3 100 parts of PVC with an average degree of polymerization () 1300, Ca-Zn
3 parts of a composite stabilizer (Gretzke M-57, manufactured by Dainippon Ink and Chemicals), 90 parts of a polyester plasticizer (Polycizer W, manufactured by Dainippon Ink and Chemicals), 3 parts of the modified VAE of Reference Example 1, and a red pigment (Watercolor). The mixture was uniformly mixed and kneaded into a sheet using two kneading rolls at a roll gap of 1.5 mm and a roll temperature of 160° C. for 7 minutes. From the sheet obtained in this way 50
Cut out the part, roll gap 0.25mm, roll temperature
The mixture was kneaded at 160°C for 5 minutes. After removing the sheet immediately after 5 minutes, PVC100 with an average degree of polymerization () 1300
Take 50 parts of a pre-compounded mixture (standard white) of 50 parts of DOP, 2 parts of titanium oxide, and 3 parts of the above Ca-Zn composite stabilizer, and mix 160 parts in the same roll.
The mixture was kneaded at ℃ for 5 minutes and the redness of the sheet was observed. The brate-out property was evaluated based on this. The results are shown in Table 2. Comparative Examples 7 to 9 Comparative Example 7 was obtained by using the VAE of Reference Example 4 instead of the modified VAE of Reference Example 1 in Example 3,
Comparative Example 8 was conducted using the modified VAE of Reference Example 5, and Comparative Example 9 was conducted using the VAE of Reference Example 6. The evaluation results are shown in Table 2. As is clear from the results in Table 2, by substituting a portion of the polyester plasticizer with the modified VAE of the present invention, the brate-out properties can be improved. Poor brate-out property is a phenomenon that occurs when, for example, during calender molding, pigments adhere to the surface of the calender roll, resulting in color contamination of the subsequent product when the product is changed in color. There is a large loss in terms of surface area. When a small amount of the modified VAE of the present invention is used in combination, such breakout properties can be improved, contributing to the simplification of raw materials or work processes. Example 4 100 parts of vinyl chloride ethylene resin (ethylene content: about 2%) with an average degree of polymerization () 700, 2 parts of Ca-Zn composite stabilizer (Gretzk M-57), 5 parts of epoxidized soybean oil, 1 part of magnesium oxide A mixture of 110 parts of the modified VAE of Reference Example 1 and 110 parts of the modified VAE of Reference Example 1 was kneaded for 10 minutes at a roll temperature of 170°C using two kneading rolls. The mixture was press-molded at a press temperature of 175℃ for 5 minutes to form a 1mm
A thick sheet was obtained. This sheet was used to evaluate the following physical properties, and the results are shown in Table 3. 1 Adhesiveness Cut a 2cm wide strip specimen from the sheet, 2
The sheets were laminated and left in a dryer at 40° C. for 24 hours under a load of 1 kg/cm ² . After leaving it at 23℃ for 2 hours, it was tested at a tensile speed of 20mm/min using a tensile tester.
A peel test was conducted. If the peel strength is 100g/2cm width or less, it can be used in flexible containers without any problems. 2 Water Absorption ^A 5 x 5 cm square cut piece was immersed in water at 50°C for 120 hours, and the water absorption rate was measured from the change in weight. If the water absorption rate is 2% or less, it can be used in beverage tanks, etc. without any problems. 3 Mechanical properties Using the same sheet, mechanical properties were measured according to JIS K-6723. Tensile strength 100Kg/cm2 ^or more, elongation
If it is 300% or higher, it will pass without any problem even if it is used for flexible containers. Examples 5 to 6, Comparative Examples 10 to 12 Example 5 uses the modified VAE of Reference Example 2 instead of the modified VAE of Reference Example 1 in Example 4.
Example 6 uses the modified VAE of Reference Example 3, Comparative Example 10 uses the VAE of Reference Example 4, and Comparative Example 11 uses the modified VAE of Reference Example 5. , Comparative Example 12 was carried out using the VAE of Reference Example 6. The evaluation results are shown in Table 3. As is clear from the results in Table 3, the modification of the present invention
PVC compositions using VAE are superior to VAE made using conventional emulsion polymerization methods in terms of non-water absorption and non-stick properties. These points make it useful as a non-plasticized soft PVC composition for food packaging materials, medical materials, etc.

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Claims (1)

[Claims] 1 Vinyl acetate content 90-50% by weight by emulsion polymerization
A vinyl monomer with a solubility coefficient of 8.5 to 15 as a salting out agent is added and suspended in a latex of vinyl acetate/ethylene copolymer containing no organic peroxide and an ethylene content of 10 to 50% by weight. 1 to 150 parts by weight of a modified vinyl acetate/ethylene copolymer obtained by suspension polymerization of the vinyl monomer and 100 parts by weight of a vinyl chloride resin. Vinyl resin composition.