JPS6212925B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing a novel aqueous dispersion of a synthetic resin useful as a heat sealing agent or binder in surface processing or impregnation processing of paper, cellophane, metal foil, plastic film, textile products, etc. Generally, the synthetic resin dispersion used as a heat sealant or binder for the above-mentioned substrates has the following characteristics: the treated film has blocking resistance, adhesion to the substrate, water resistance, oil resistance, heat resistance, workability, and is required to be advantageous in terms of cost. Although vinyl chloride polymers provide treated films with excellent water resistance, oil resistance, chemical resistance, and mechanical strength, they have poor film-forming properties and poor adhesion to the above-mentioned substrates. As a result, it has the disadvantage of reduced tear strength. Furthermore, although vinyl acetate polymers have excellent film-forming ability and adhesion, they have the drawbacks of poor mechanical strength, water resistance, alkali resistance, and oil resistance. The present inventors have intensively investigated ways to improve the functionality of a copolymer of vinyl chloride and vinyl acetate, which has the above-mentioned excellent physical properties as a homopolymer, as a heat sealing agent or binder, and have discovered the present invention. Ta. That is, the present invention contains 25 to 95% by weight of vinyl chloride monomer,
5 to 70% by weight of vinyl acetate monomer, 0.1 to 0.1 to alkali metal salt of methallylsulfonic acid or allylsulfonic acid (hereinafter collectively referred to as (meth)allylsulfonic acid)
A monomer mixture consisting of 5.0% by weight and 0 to 40% by weight of other ethylenically unsaturated monomers is added as a dispersant to 100 parts by weight of the monomer mixture, with a degree of saponification of 80 mol% or more, average polymerization. This is a method for producing a synthetic resin dispersion characterized by copolymerizing in water in the presence of 0.1 to 3.0 parts by weight of partially saponified polyvinyl alcohol having a degree of 500 to 2000. Generally, it is industrially advantageous to use heat sealants or binders in the form of aqueous dispersions; It must have the property of not being able to easily release solids even under adverse conditions. Also other formulations, such as plastics, pigments,
It must be possible to easily disperse the metal powder such as a magnetic material or a thermal stabilizer to obtain a stable mixture. In order to impart such physical properties, an alkali metal salt of (meth)allylsulfonic acid is suitable as a comonomer of these together with vinyl chloride and vinyl acetate monomers. This monomer is a highly polar alkali metal salt of sulfonic acid, and it is understood that the effects of the present invention can be obtained by allowing it to exist in the produced polymer. In the present invention, the amount of each monomer used is 25 to 95% by weight of vinyl chloride monomer and 5 to 70% by weight of vinyl acetate monomer. It is necessary to effectively exhibit each characteristic of merging. If the vinyl chloride monomer content is less than 25% by weight, a film with good water resistance, oil resistance, and mechanical strength cannot be obtained, and if it exceeds 95% by weight, the film forming properties of the synthetic resin dispersion are poor and Adhesion becomes poor. Also, vinyl acetate monomer is 5% by weight.
If it is less than 70% by weight, film forming properties and adhesion will not be improved, and if it exceeds 70% by weight, mechanical strength, water resistance, and oil resistance will be poor. The preferred amount used is vinyl chloride monomer 30
~90% by weight, vinyl acetate monomer 10-65% by weight. Further, the amount of the alkali metal salt of (meth)allylsulfonic acid used must be 0.1 to 5.0% by weight, preferably 0.3 to 3.0% by weight. 0.1% by weight
If it is less than 5.0% by weight, the above-mentioned effects of use will not be observed, and if it exceeds 5.0% by weight, the polymerization rate and degree of polymerization will be significantly lowered, which is not preferable. Ethylenically unsaturated monomers that can be used as monomers other than the above three types of monomers that are essential monomers of the present invention include It is used in an amount of 40% by weight or less to adjust the physical properties. Generally, the following monomers can be selected to adjust the glass transition temperature, solubility parameter, crosslink density, etc. Examples of acrylic esters include butyl acrylate, 2-ethylhexyl acrylate, ethoxyethyl acrylate, methoxypropyl acrylate, and the like. Examples of the vinyl alkyl ether include pentyl vinyl ether, octyl vinyl ether, lauryl vinyl ether, and cetyl vinyl ether. Examples of vinyl esters of saturated fatty acids include valeric acid vinyl ester, caprylic acid vinyl ester, capric acid vinyl ester, and lauric acid vinyl ester. Examples of monomers containing halogen include vinylidene chloride, vinyl bromide, methallyl chloride, vinyl chlorobutyrate, and the like. Examples of monomers providing other functional groups include acrylic acid, methacrylic acid, methacrylic acid glycidyl ester, acrylamide, and N-methylol acrylamide. Furthermore, when using monomers having highly reactive functional groups, such as acrylic acid, methacrylic acid, and N-methylol acrylamide, the amount is preferably 2.0% by weight or less. This is because if these monomers are used in large amounts, they tend to form gel components during the polymerization reaction. Next, partially saponified polyvinyl alcohol, which is a dispersant necessary for copolymerizing these monomers in water, will be explained. This dispersant provides a good dispersion state of the polymerization system when used simultaneously with the alkali metal salt of (meth)allylsulfonic acid mentioned above. In other words, it is a slightly porous material that is difficult to obtain with normal polymerization methods.
Dispersed polymers with particle sizes of several microns can be obtained. This improves blendability with compounding agents such as plasticizers and heat stabilizers. Partially saponified PVA that satisfies these purposes has a degree of saponification of 80 mol% or more and an average degree of polymerization of 500 or more.
Must be 2000. If this condition is exceeded, the dispersion state of the polymerization system becomes extremely unstable, which is not preferable. The amount of the dispersant used must be 0.1 to 0.3 parts by weight, preferably 0.2 to 2.0 parts by weight, based on 100 parts by weight of the monomer mixture. If it is less than 0.1 part by weight, the particle size is significantly non-uniform, and
Fine particles of micron size or less will be generated, and the viscosity of the resulting dispersion will change greatly. On the other hand, if it exceeds 3.0 parts by weight, the viscosity of the polymerization reaction system will increase, giving an unstable dispersion system, so both are unsuitable. be. In the present invention, a synthetic resin dispersion is obtained by blending predetermined amounts of each of the above-mentioned components and copolymerizing them in water using a known polymerization method. At this time, it is of course possible to use other types of dispersants or emulsifiers in combination. For example, dispersants such as alkyl cellulose, hydroxyalkyl cellulose, and gelatin, emulsifiers such as alkylaryl sulfonates, alkyl sulfates, polyoxyethylene alkyl allyl ethers, polyoxyethylene aryl sulfates, and alkali salts of sulfosuccinates are used as appropriate. I can do it. Examples of catalysts include water-soluble compounds such as potassium persulfate, ammonium persulfate, and hydrogen peroxide hydride, and oils such as benzoyl peroxide, azobisisobutyronitrile, di-2-ethylhexyperoxydicarbonate, and lauroyl peroxide. Soluble compounds can be selected and used depending on the polymerization method. As the polymerization method, emulsion polymerization method or suspension polymerization method is used. Other polymerization conditions can be carried out according to conventional methods. The copolymer thus obtained is used in the form of an aqueous dispersion as a heat sealing agent or a binder for various uses. In this case, the synthetic resin dispersion obtained by this method is particularly effective when blended with a plasticizer and a heat stabilizer. In the case of a blending method, in the case of a compound such as a plasticizer that does not cause much trouble in the polymerization reaction, good results can be obtained by employing a method in which the compound is made to exist in the polymerization system in advance and the polymerization reaction is carried out. Such plasticizers include epoxidized soybean oil, epoxidized linseed oil, dibutyl phthalate, diisodecyl phthalate, and the like. According to the present invention, a synthetic resin dispersion having the respective advantages of vinyl chloride resin and vinyl acetate resin, that is, important properties such as excellent mechanical strength, water resistance, oil resistance, adhesion, tear strength and filmability, is produced. is easily obtained and is particularly useful as a heat sealing agent or binder for substrates such as paper, cellophane, metal foil, plastic film, and textile products. Next, Examples and Comparative Examples of the present invention will be given and explained in more detail. In addition, the physical property test in each example was conducted according to the following method. (1) Heat sealing strength A polymer or a composition containing it is uniformly sprinkled on a Tetoron/cotton (65/35) blended fabric at a solid content of 15 to 20g/ ^m2 , and then PVC soft leather is added to this. , heat-sealed under the conditions of 150° C. x 5 Kg/cm ² x 10 seconds, and the peel strength at a width of 20 m/m was measured. (2) Tear strength A cut was made in a test base material (thickness 0.8 to 1.0 m/m) prepared for measuring heat seal strength, and the strength was measured when it was torn at 180°. (The value was calculated by dividing the load by the thickness.) (3) Water resistance After immersing the test base material prepared for measuring heat seal strength in pure water at 20°C for 3 days, the peel strength was measured. was measured, and the same strength was divided by the strength before immersion to determine the retention rate. (4) Minimum film forming temperature The lowest temperature at which a uniform film was formed from the aqueous dispersion was measured using a thermal gradient film forming temperature measurement tester. (5) Storage stability The obtained aqueous dispersion was left at 40°C for 2 weeks.
The presence or absence of release of cake-like solid matter was observed. Examples 1 to 7 and Comparative Examples 1 to 3 140 parts by weight of pure water was added to the stainless steel polymerization vessel of 5.
100 as the total monomer under the conditions of the monomer composition in Table 1.
Parts by weight, partially saponified PVA as dispersant, Table 1
0.4 parts by weight of potassium persulfate was added as a catalyst, and the mixture was heated at room temperature at 700 rpm for 30 minutes.
After preliminary stirring, emulsion polymerization was carried out at 60° C. x 200 rpm x 20 hours to obtain an aqueous dispersion with a solid content of 40% by weight. This aqueous dispersion was applied to a substrate using a blade coater, and the above-mentioned tests were conducted.

【table】

[Table] Comparative Examples 4 and 5 Monomers and dispersants were used under the conditions shown in Table 2, and other conditions were the same as those described in Examples 1 to 7 and Comparative Examples 1 to 3. I got a body. The above-mentioned tests were conducted on this aqueous dispersion. The results are shown in Table 2.

【table】

【table】

Claims (1)

[Claims] 1 Vinyl chloride monomer 25-95% by weight, vinyl acetate monomer 5-70% by weight, alkali metal salt of methallylsulfonic acid or allylsulfonic acid 0.1-5.0% by weight
A monomer mixture consisting of 0 to 40% by weight of other ethylenically unsaturated monomers is added to the monomer mixture.
A synthetic resin characterized by being copolymerized in water in the presence of 0.1 to 3.0 parts by weight of partially saponified polyvinyl alcohol having a degree of saponification of 80 mol% or more and an average degree of polymerization of 500 to 2000 as a dispersant per 100 parts by weight. Method for manufacturing dispersion.