JPS5928588B2 - How to thicken emulsion latex - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to post-thickening emulsion latex with an acetoacetyl group-containing polyvinyl alcohol resin (hereinafter abbreviated as AA-PVA resin).

Emulsion latex has a wide range of uses, including adhesives, paints, processing of fibers and textiles, processing of paper and leather, binders for various materials, and admixtures for cement and mortar.

However, emulsion latex has a high viscosity depending on the purpose and use, and one with moderate structural viscosity shows excellent effects on workability, mechanical suitability, finishing condition, adhesion, etc., so we provide such emulsion latex. is desired.

The inventors of the present invention have repeatedly investigated ways to easily post-thicken emulsion latex without impairing its inherent performance, and found that by adding an appropriate amount of AA-PVA resin, emulsion latex They discovered that it is possible to increase the viscosity of latex and completed the present invention.

According to the present invention, (1) it is sufficient to simply add and mix the AA-PVA resin into the emulsion latex;
2) By selecting the degree of AA or the amount added,
Emulsion latex of any viscosity can be obtained depending on the application, and viscosity stability is also excellent. (3) Compared to polyvinyl alcohol and cellulose derivatives, which are conventionally used as thickeners, Effects such as improved water resistance of the emulsion latex film can be obtained.

The AA-based PVA resin in the present invention is obtained by reacting a PVA resin with diketene, acetoacetic acid, acetoacetic ester, or the like.

When converting AA with diketene, disperse the PVA resin in acetic acid and add diketene to it. Dissolve the PVA resin in a solvent such as dimethylformamide or dioxane in advance and add diketene to it. There are known methods such as , and a method in which diketene is brought into direct contact with the PVA resin to react, and this method is preferred because it can easily yield an AA-modified PVA resin. The PVA resin used in the AA-based PVA resin is PVA obtained by saponifying polyvinyl acetate (polymerization degree 200-3000, saponification degree 30-100 mol%), its derivatives, and copolymerizable with vinyl acetate. A water-soluble copolymer saponified product with a monomer having the following is preferred.

The monomers include (anhydrous) maleic acid, fumaric acid,
Unsaturated carboxylic acids and their esters such as crotonic acid, itaconic acid, (meth)acrylic acid, α-olefins such as ethylene and propylene, (meth)allylsulfonic acid (soda), sodium sulfonate (monoalkyl maleate) , sodium disulfonate alkyl maleate, N-methylol acrylamide, alkali salt of acrylamide alkyl sulfonate, N-vinylprolidone, N-vinylpyrrolidone derivatives, etc., and these may be used alone or in combination of two or more thereof.

Of the AA-PVA resins obtained as described above, those used in the present invention are referred to as the degree of acetoacetylation (hereinafter referred to as AA
(abbreviated as "degree of oxidation") is approximately in the range of 0.1 to 15 mol%.

An AA-PVA resin with an AA degree of less than 0.1 mol cannot be expected to have much of a thickening effect, and if it exceeds 15 mol %, it becomes insoluble in water and the viscosity does not increase even if the amount added is increased. , which is undesirable because it impairs the appearance of the emulsion latex coating. A of degree of AA within the above range
The amount of A-PVA resin added to the emulsion latex is approximately 0 to 100 parts by weight of the emulsion latex (based on a solid content of 50% by weight).
．． It ranges from 1 to 10 parts by weight.

When using AA PVA resin with a small degree of AA,
If the amount added is large and an AA-PVA resin with a high degree of AA is used, a small amount will produce a thickening effect. That is, the thickening effect is approximately proportional to the degree of AA and the amount added. Therefore, it is desirable to understand these relationships and select the degree of AA and the amount added depending on the purpose. Examples of the emulsion latex in the present invention include natural rubber latex, styrene/ptadiene latex, cis-1,4 polyisoprene latex, chloroprene latex, acrylonitrile/butadiene latex, vinylpyridine latex, methyl methacrylate/ptadiene latex,
Examples include polyurethane latex, acrylic ester emulsion, vinyl acetate emulsion, ethylene/vinyl acetate emulsion, vinyl chloride latex, polystyrene latex, polyethylene emulsion, silicone emulsion, polybutene emulsion, thiokol latex, etc. . When adding and mixing AA-PVA resin to emulsion latex, AA-PVA resin
When adding the VA resin as an aqueous solution, it is sufficient to simply add the aqueous solution to the emulsion latex at room temperature while stirring, but when adding the powder of the AA-modified PVA resin, the emulsion latex is stirred. It is preferable to add the powder and heat it to 60 to 80° C., since the thickening can be completed in a short time.

The emulsion latex thickened in the present invention can be used in paints, adhesives, sealants, cast products, carpet packing, flocking, etc. by blending appropriate amounts of fillers, pigments, and other additives as necessary. Widely used for processing, civil engineering joint materials, etc.

In such applications, when a water resistant agent is used in combination, the water resistance is further improved. Some examples of agents used for water resistance are listed below. Of course, the present invention is not limited to such drugs. Aldehydes (glyoxal, glutaraldehyde) Amines (urea,
Melamine or its methylolated products, hexamethylene diamine) Metal salts (iron salts, nickel salts, magnesium salts) Isocyanate compounds (tolylene diisocyanate, trimethylolpropane-tolylene diisocyanate adduct, triphenylmethane triisocyanate, isoborone diisocyanate) Epoxy compounds (ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, glycerin di- or triglycidyl ether) oxidizing agents (potassium dichromate,
Ammonium dichromate) Compounds having radical-forming ability (potassium persulfate, azobis, azide, diazo) and others (phenolic resin) Next, the present invention will be specifically explained with reference to Examples.

In the examples, "parts" and "%" are based on weight unless otherwise specified. Example 1 Ethylene monovinyl acetate copolymer emulsion (ethylene: vinyl acetate - 21:79 (weight ratio), resin content 50%,
PVA (polymerization degree 1700) to 100 parts (viscosity 530 eps)
, saponification degree of 99 mol%) with an AA degree of 5.4 mol%
When 2.5 parts of AA-PVA was added and mixed, the viscosity was 1.
A 500 cps emulsion was obtained.

The thixotropic index of this emulsion was 0.38. Examples 2 to 7 Vinyl acetate resin emulsion (resin content 50%, viscosity 74
00cps) 100 parts of AA with a degree of AA of 2.3 mol% obtained from PVA (degree of polymerization 1700, degree of saponification 99 mol%)
In Example 2, 1 part of PVA, in Example 3, 2 parts, and in Example 4, 6 parts were added and mixed.

In addition, 100 parts of the above emulsion was added with PVA (polymerization degree 180).
In Example 5, 1 part of AA-PVA with a degree of AA of 1.6 mol% obtained from 0, saponification degree of 88 mol%), and in Example 6, 2 parts
In Example 7, 6 parts were added and mixed. The properties of the obtained emulsion are shown in Table 1. Comparative examples 1 to 3
▲Blue PV in Example 1
Comparative Example 1 and Example 3 were conducted in the same manner except that PV
Comparative Example 2 and Example 6 were conducted in the same manner except that PV
Comparative Example 3 is a case in which the same procedure was carried out except that A (degree of polymerization: 1800, degree of saponification: 88 mol %) was used, and the emulsion properties of each emulsion are shown in Table 1.

Examples 8 to 12 Emulsion properties were measured in the same manner as in Example 1, except that emulsion latex and AA-PVA as shown in Table 2 were used instead of the ethylene monovinyl acetate copolymer emulsion used in Example 1.

Claims (1)

[Claims] 1 Emulsion latex characterized by adding and mixing an acetoacetyl group-containing polyvinyl alcohol resin at a ratio of 0.1 to 10 parts by weight to 100 parts by weight of emulsion latex (based on 50% by weight resin solid content). thickening method.