JPS6131723B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a novel synthetic resin aqueous dispersion useful as a binder by surface treatment or impregnation treatment of paper, cellophane, metal foil, plastic film, textile products, etc. . Generally, the synthetic resin dispersion used as a binder for the above-mentioned base materials requires that the treated coating has superior adhesion, water resistance, oil resistance, heat resistance, workability, and cost advantage to the base material. It will be done. However, although vinyl chloride polymers provide treated films with excellent oil resistance, chemical resistance, and mechanical strength, they have poor film-forming properties and poor adhesion to the above-mentioned substrates. However, when trying to improve the heat sealability, the tear strength decreases. Furthermore, although vinyl acetate polymers have excellent film-forming ability and adhesion, they have the drawbacks of poor mechanical strength, alkali resistance, and oil resistance. Furthermore, when manufacturing a water-dispersed binder, emphasis must be placed on the selection of the emulsifier or dispersant. If commonly used low molecular weight emulsifiers or surfactants are mainly used, water resistance, which is an important function as a binder, will be significantly impaired, and at the same time, adhesive strength will also be affected due to the migration of these compounds to the adhesive interface. It becomes defective. The present inventors have intensively studied copolymers of vinyl chloride and vinyl acetate having the above-mentioned physical properties as respective homopolymers in order to improve their functions as binders, and as a result, they have discovered the present invention. That is, the present invention provides a monomer mixture consisting of 25 to 90% by weight of vinyl chloride monomer, 5 to 80% by weight of vinyl acetate monomer, and 0 to 40% by weight of other ethylene monomers. For 100 parts by weight of the mixture, the epoxidized soybean oil contains 5 to 40 parts by weight of linseed oil, 0.1 to 3.0 parts by weight of partially saponified polyvinyl alcohol with a degree of saponification of 80 mol% or more, an average degree of polymerization of 300 to 2000, and a water-soluble catalyst. This is a method for producing an aqueous synthetic resin dispersion, characterized in that copolymerization is carried out by stirring in the presence of a synthetic resin at a stirring power of 1.0 to 2.0 kW/m ³ . It is generally advantageous industrially to use the binder as an aqueous dispersion. However, in order to take the form of an aqueous dispersion, it is necessary that the solid material cannot be easily released even if left for a long time or under some adverse mechanical or chemical conditions. Furthermore, it must be possible to obtain a stable dispersion that can be easily dispersed with other compounds such as plasticizers, pigments, metal powders such as magnetic materials, or heat stabilizers. Furthermore, in order to impart water resistance as a binder, it is necessary to reduce the amount of a commonly used emulsifier having a low molecular weight as much as possible, as described above. In order to impart such physical properties to the binder, the various conditions of the present invention described above are necessary. Next, the usage ratio of each component of the present invention will be explained. The vinyl chloride monomer content is 25-90% by weight, preferably 30-80% by weight. Vinyl chloride monomer
If it is less than 25% by weight, the oil resistance, chemical resistance, or mechanical strength of the resulting film will be poor.
Moreover, if it exceeds 90% by weight, film forming properties will be poor. The vinyl acetate monomer content is 5 to 80% by weight, preferably 20 to 70% by weight. If the vinyl acetate monomer content is less than 5% by weight, the resulting coating will have poor adhesion, and if it exceeds 80% by weight, the resulting coating will have poor mechanical strength, alkali resistance, and oil resistance. The amount of other ethylene monomers is 0 to 40% by weight, preferably 0 to 20% by weight. If it exceeds 40% by weight, the properties of the vinyl chloride monomer or vinyl acetate monomer described above will not be exhibited. Other monomers that can be used as ethylene monomers may be used as appropriate to adjust the desired physical properties of the resulting aqueous dispersion. 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, and vinyl chloroacetate. Monomers providing other functional groups include acrylic acid, methacrylic acid, glycidyl methacrylate, acrylamide, N
- Methyloacrylamide and the like. In particular, when using monomers with highly reactive functional groups, such as acrylic acid, methacrylic acid, and N-methylolacrylamide, 2.0 It is desirable that the amount is less than % by weight. This is because if these monomers are used in large amounts, they tend to form gel components during the polymerization reaction. The amount of epoxidized soybean oil or linseed oil is 5 to 40 parts by weight, preferably 10 to 30 parts by weight, per 100 parts by weight of the monomer mixture. Its presence provides a suitable viscosity in the aqueous dispersion state during the polymerization reaction, and together with the other polymerization conditions of the present invention results in the formation of stable fine particles. Epoxidized soybean oil or linseed oil
If the amount is less than 1 part by weight, an aqueous dispersion consisting of fine particles cannot be obtained and the heat sealability will be poor.
If it exceeds 40 parts by weight, the viscosity of the polymerization system will become abnormally high, which is inappropriate. In addition, the partially saponified polyvinyl alcohol as a dispersion has a saponification degree of 80 mol% or more, preferably 86% or more, and an average polymerization degree of 300 to 300%.
2000, preferably 500-1800. The presence of partially saponified polyvinyl alcohol provides a mechanism by which finely divided water-dispersed polymers can be produced from the above monomers when water-soluble catalysts are used. The proportion of the partially saponified polyvinyl alcohol used is 0.1 to 3.0 parts by weight, preferably 0.3 to 2.0 parts by weight, based on 100 parts by weight of the monomer mixture. If the amount is less than 0.1 part by weight, a dispersion consisting of fine particles cannot be obtained, and if it exceeds 3.0 parts by weight, the viscosity of the polymerization system will become abnormally high and give an uneven particle size distribution, which is unsuitable. Furthermore, as an essential condition, it is necessary to provide an average stirring power of 1.0 to 2.0 kW/m ³ and preferably 1.2 to 1.8 kW/m ³ per unit volume during the reaction period. As for the stirring power during the reaction period, as the reaction progresses, the required stirring power tends to increase when the number of stirrings is the same, so it is necessary to use the averaged value as an index. While common emulsion polymerization methods that give fine particles with a particle size of 0.2 to several microns have a differential value of 0.3 to 0.6 kW/m ³ , the present invention shows a remarkable difference. 1.0k
Coarse particles are likely to be generated when W/ ^m3 is less than 2.0kW/
If it exceeds m ³ , the polymerization system will become extremely viscous and unsuitable. The stirring device used in the present invention has the shape of the reactor,
Depending on the structure and volume, those commonly used in suspension polymerization of vinyl chloride monomers may be used. For example, a stainless steel (SUS304) cylindrical vertical high-pressure reactor (several to several m ³ ) uses two or three arc-shaped stirring blades (surface area approximately 10 to 1000 cm ² ) in one stage. ). Further, as the water-soluble catalyst, potassium persulfate, ammonium persulfate, hydrogen peroxide, etc. can be used. A good synthetic resin dispersion can be obtained by adopting the above requirements for monomer composition, polymerization aid, and stirring conditions. That is, it is possible to obtain an aqueous dispersed polymer that is slightly porous and has a particle size of 0.2 to several microns, which is difficult to obtain by ordinary polymerization methods. At this time, it is of course possible to use other types of dispersants and 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. Can be used. For other polymerization conditions, known means may be employed. According to the present invention, a synthetic resin dispersion has 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 film forming property. is easily obtained and is particularly useful as a binder for substrates such as paper, cellophane, metal foil, plastic film, and textile products. In particular, since it is possible to obtain an aqueous dispersion that does not contain, or even hardly contains, a commonly used low molecular weight emulsifier, it has extremely excellent water resistance as a binder. Next, the present invention will be explained in more detail with reference to Examples and Comparative Examples. The tests conducted in each of the following examples were conducted in accordance with the following method. (1) Heat-sealing strength: Apply the polymer uniformly as a solid content of 15 to 20gr/m ² to a Tetron/cotton (65/35) blended fabric, add vinyl chloride soft leather to this,
Heat sealing was performed under the conditions of 150° C. x 5 Kg/cm ² x 10 seconds, and the peel strength of a width of 20 m/m was measured. (2) Tear strength A cut was made in the 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°. (3) Water resistance The test base material prepared for measuring heat seal strength was immersed in pure water at 20℃ for 3 days, then the peel strength was measured, and the peel strength was divided by the strength before immersion. The rate was calculated. (4) Bottom film forming temperature The bottom temperature at which a uniform film is formed from the aqueous dispersion was measured using a thermal gradient type film forming temperature measurement tester. (5) Storage stability The obtained aqueous dispersion was left at 40℃ 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 a 2 m ³ stainless steel polymerization vessel.
Under the conditions of monomer composition in Table 1, as total monomers
100 parts by weight, using partially saponified PVA and epoxidized soybean oil or linseed oil as dispersants as shown in Table 1, adding 0.3 parts by weight of potassium persulfate as a catalyst and stirring to provide stirring power as shown in Table 1. , 60
C. for 20 hours to obtain an aqueous dispersion with a solid content of 41% by weight. This aqueous dispersion was applied to a substrate using a blade coater, and each of the tests described above was conducted. 【table】

Claims (1)

[Claims] 1. In the suspension polymerization of vinyl chloride monomers, 25 to 90% by weight of vinyl chloride monomers, 5 to 80% by weight of vinyl acetate monomers, and 0 to 0 to 100% of other ethylene monomers.
A monomer mixture consisting of 40% by weight is added to 100 parts by weight of the monomer mixture, 5 to 40 parts by weight of epoxidized soybean oil or linseed oil, and a saponification degree of 80 mol% or more and an average polymerization degree of 300 to 2000. Production of an aqueous synthetic resin dispersion characterized by copolymerization by stirring in the presence of 0.1 to 3.0 parts by weight of partially saponified polyvinyl alcohol and a water-soluble catalyst at a stirring power of 1.0 to 2.0 kW/m ³ Law.