JPS6313461B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a new coating material whose main ingredient is a synthetic resin emulsion. When preparing a synthetic resin emulsion used as a paint, the method differs somewhat depending on the type of resin, but in all cases it is essential to use an emulsifier or a protective colloid. For example, to prepare emulsions of vinyl polymers such as vinyl acetate, acrylic esters, and vinyl chloride, the monomers are emulsion polymerized in the presence of an emulsifier or protective colloid, and polyester resin emulsions, To prepare an epoxy resin emulsion, a silicone resin emulsion, etc., the above resin in solution or molten form is dropped into an aqueous solution containing an emulsifier or protective colloid and stirred to form an emulsion, or the emulsifier and the emulsifier are added to the molten resin. An aqueous solution of a protective colloid is added dropwise and stirred to form an emulsion. As typical emulsifiers or protective colloids, nonionic surfactants and anionic surfactants are used alone or in combination, and polyvinyl alcohol (PVA) is used, but surfactant-based Since there are many problems in terms of mechanical stability of the emulsion obtained, PVA-based materials have become mainstream. However, when using a partially saponified PVA with an average degree of saponification of about 88 mol%, it has a large structural viscosity, a small temperature dependence of viscosity, and good freezing stability or storage stability at low temperatures. An emulsion can be obtained, but water resistance is insufficient.On the other hand, if a completely saponified type with an average degree of saponification of about 99 mol% is used, an emulsion with high water resistance and a small structural viscosity index can be obtained, but the viscosity temperature It is known that they are highly dependent and have poor freezing stability and low-temperature storage stability, and are used differently depending on the purpose of the emulsion. However, with the advancement of technology, emulsions with the above-mentioned properties alone are no longer satisfactory, and the performance of both emulsions using partially saponified PVA and completely saponified PVA has been improved. There is a need for an emulsion that has a suitable structural viscosity index, excellent water resistance, low temperature dependence of viscosity, and good freeze stability and storage stability at low temperatures. In order to obtain an emulsion with such performance, it is possible to use a mixture of partially saponified PVA and completely saponified PVA, but in this case, each
In many cases, the characteristics of PVA cancel each other out, and the drawbacks of each PVA become more apparent. However, the present inventors have conducted various studies on emulsifiers or protective colloids that can simultaneously satisfy these various properties of emulsions, and have found that by using acetoacetylated PVA as an emulsifier or protective colloid, emulsions with excellent properties can be obtained. was obtained and found to be extremely useful as a paint, leading to the completion of the present invention. According to the present invention, the following remarkable effects can be obtained. (1) The emulsion's low-temperature storage stability and freeze-thaw stability are improved, as well as the film's water resistance. (2) Emulsions with high viscosity can be obtained even at low concentrations.
(3) Water resistance can be more easily enhanced by using in combination with a crosslinking agent (aldehydes, amines, metal salts, etc.). (4) It can be used in the same way as when PVA is used as an emulsifier, and can be used in a wide range of ways, including in combination with surfactants. (5) Since it has excellent cohesiveness with clay minerals, it exhibits strong water resistance when used together with clay minerals. (6) Wastewater containing the emulsion can be easily treated by coagulation and precipitation using clay or the like. The acetoacetylated PVA used in the present invention is
Obtained by reacting PVA and diketene. (The chemical reaction formula is

It is shown by [Formula]. ) For example, PVA is dispersed in an acetic acid solvent,
One method is to add diketene to this, and the other is to dissolve PVA in a solvent such as dimethylformamide or dioxane in advance and add diketene to it. It is also possible to obtain acetoacetylated PVA by directly contacting PVA with diketene gas or liquid diketene. use here
PVA can be used not only in saponified polyvinyl acetate, but also in PVA that has been slightly modified with carboxyl groups, amide groups, nitro groups, carboxylic acid ester groups, hydrocarbon residue sulfonic acid (salt) groups, etc. be. The average degree of saponification and average degree of polymerization of acetoacetylated PVA are not particularly limited, but from the viewpoint of effectiveness as a protective colloid, the residual acetate group should be 0.1 to 15.
The mole % and average degree of polymerization are preferably in the range of 500 to 2,600. The content of acetoacetyl group is 0.05-25 mol%
A suitable range is preferably 1 to 15 mol%.
If it is less than 0.05 mol%, the contribution to the water resistance, stability, and thickening property of the emulsion is small and undesirable;
If it exceeds 15 mol%, the emulsion will be destroyed and it will be difficult to obtain a homogeneous emulsion. To prepare the acetoacetylated PVA-containing synthetic resin emulsion of the present invention, monomers are emulsion polymerized using acetoacetylated PVA as an emulsifier or protective colloid, and a synthetic resin solution or melt is prepared in the presence of acetoacetylated PVA. The above three cases include adding acetoacetylated PVA to a synthetic resin emulsion obtained by an arbitrary method to produce a more stable emulsion. Each case will be specifically explained below. Emulsion Polymerization Method This method is usually suitably carried out when producing a polymer emulsion of a vinyl compound.
During emulsion polymerization, water, acetoacetylation
A conventional emulsion polymerization method can be carried out, in which a vinyl compound is added once or continuously in the presence of PVA and a polymerization catalyst, followed by heating and stirring. The weight of the acetoacetylated PVA used is approximately 0.1 to 30% by weight, preferably 2 to 20% by weight, based on the solid content of the polymer. If it is less than 2% by weight, sufficient effect cannot be obtained, and 20
If the amount exceeds % by weight, the effect will not increase in proportion to the amount used. The acetoacetylated PVA can be added at any time, such as at the beginning, during or after emulsion polymerization, but it is usually added at the beginning or during the emulsion polymerization. Vinyl compounds used in this method include vinyl acetate, vinyl propionate, acrylic ester, methacrylic ester, vinyl chloride, vinylidene chloride, acrylonitrile,
methacrylonitrile, styrene, ethylene,
Glycidyl group-containing compounds such as propylene, glycidyl acrylate, glycidyl methacrylate, glycidyl divinyl ether, glycidyl vinyl ether, methylol group-containing compounds such as N-methylolacrylamide and N-methylolmethacrylamide, and alkoxy group-containing derivatives thereof, acrylamide, methacrylamide, etc. Carboxylic acid amides, carboxylic acids such as acrylic acid and methacrylic acid, divinyl adipate,
Divinyl succinate, triallyl cyanurate, diallyl fumarate, triallyl citrate, diallyl maleate, vinyl versatate,
These include homopolymerization or copolymerization. Among these, vinyl acetate alone or a copolymer mainly composed of vinyl acetate is preferred. When a vinyl compound containing an N-methylol group or a glycidyl group is used, a self-crosslinking emulsion can be produced, and a coating material with good water resistance can be prepared. As the emulsion polymerization catalyst, a catalyst used in normal emulsion polymerization is used. Redox catalysts are particularly preferred, and specific examples include hydrogen peroxide and formaldehyde/zinc sulfoxylate, glyoxal/zinc sulfoxylate, glyoxylic acid/zinc sulfoxylate, hydrogen peroxide, ammonium persulfate, or potassium persulfate and methane. sodium bisulfite, sodium bisulfite,
Examples include combinations with ferrous sulfate, dimethylaniline, formaldehyde zinc sulfoxylate or formaldehyde sodium sulfoxylate. Furthermore, nonionic surfactants and ionic surfactants can also be used in combination with acetoacetylated PVA. Furthermore, other emulsifiers, such as PVA, cellulose derivatives (carboxymethylcellulose, hydroxyethylcellulose, methylcellulose, etc.),
Polyacrylic acid derivative, maleic acid (anhydride)
Vinyl ether copolymer, (anhydrous) maleic acid-vinyl acetate copolymer, vinyl acetate-(meth)
A saponified allylsulfonic acid (salt) copolymer can also be used in combination as appropriate. Other various additives, regulators, etc. used in ordinary emulsion polymerization can also be used as appropriate. Method by post-emulsification This method is suitably carried out when preparing a synthetic resin emulsion that is difficult to produce by emulsion polymerization. In this method, acetoacetylated PVA may be dissolved in water, and a solution or molten resin may be added dropwise to the solution and stirred, or an aqueous solution of acetoacetylated PVA may be dropped into the molten resin and stirred. There is no particular need for heating to form an emulsion, but if necessary, it may be heated to about 45 to 85°C. The substances to be emulsified are not particularly limited, and include epoxy resins, urethane resins, urea-formalin initial condensates, phenol-formaldehyde initial condensates, alkyd resins, polyester resins,
Examples include ketene dimer, silicone resin, wax, polypropylene, polyethylene, and the like. The amount of acetoacetylated PVA to be used varies somewhat depending on the resin content of the required emulsion, etc., but it is usually selected from the range of 0.1 to 30% by weight, preferably 1 to 25% by weight based on the material to be emulsified. . If necessary, a nonionic activator such as a polyoxyethylene-alkyl ether type, a polyoxyethylene-alkyl phenol type, a polyhydric alcohol ester type, or a cationic activator such as a higher alkyl amine salt is used in combination with the resin. You can also. It is also possible to mix these active agents into the object to be emulsified. Post-addition method This method is carried out by adding acetoacetylated PVA to a synthetic resin emulsion obtained by any method for the purpose of further improving stability or thickening. Targeted emulsions include styrene/butadiene emulsions, cis-1,4 polyisoprene emulsions, chloroprene emulsions, acrylonitrile/butadiene emulsions, vinylpyridine emulsions, methyl methacrylate/butadiene emulsions, polyurethane emulsions, and acrylic esters. emulsions, vinyl acetate emulsions, ethylene/vinyl acetate emulsions, vinyl chloride emulsions, polystyrene emulsions, polyethylene emulsions, silicone emulsions, polybutene emulsions, thiol emulsions, and the like. When adding and mixing acetoacetylated PVA to an emulsion, when adding the PVA as an aqueous solution, it is sufficient to simply add the aqueous solution to the emulsion while stirring the emulsion at room temperature, but when adding the PVA powder, , add the powder while stirring the emulsion, stirring for 60 to 80 minutes.
It is preferable to heat the mixture to 0.degree. C. because uniform mixing can be completed in a short time. The amount of acetoacetylated PVA used is approximately 0.1 to 0.1 to the solid content of the emulsion.
30% by weight, preferably in the range of 0.1-10% by weight. When using acetoacetylated PVA with a low degree of acetoacetylation, increase the amount added.
Acetoacetylation with a large degree of acetoacetylation
When using PVA, a small amount will produce effects such as thickening. That is, the thickening effect and the stability improving effect are approximately proportional to the degree of acetoacetylation and the amount added. Therefore, it is desirable to understand these relationships and then select the degree of acetoacetylation and the amount added depending on the purpose. Thus, the emulsion obtained can be used as it is or, if necessary, may be further treated with a plasticizer, a film-forming agent such as a high-boiling solvent, clay, calcium carbonate,
Extender pigments such as kaolin and diatomaceous earth, colored pigments such as titanium oxide, preservatives, insect repellents, rust preventives, thickeners, etc. are appropriately blended and used. In particular, metal compounds,
(Beryllium, zirconium, titanium, chromium, calcium, magnesium, zinc, barium, strontium, aluminum, bismuth,
oxides, hydroxides, salts, basic salts, acidic salts, neutral salts, amine complexes, etc. of antimony, cobalt, iron, nickel, etc.), formaldehyde, glyoxal, dimethylolated products of urea or melamine, isocyanate compounds, epichlorohydrin The combined use of curing agents such as various epoxy compounds such as ethylene glycol diglycidyl ether, glycerol di- or triglycidyl ether has the effect of further improving the water-resistant adhesive strength. Preferred metal compounds include zinc acetate, zinc oxide, zinc glycinate, chromium nitrate, titanyl sulfate, carbonic acid, zinc,
Examples include aluminum chloride, zinc benzoate, zinc salicylate, zinc glycolate, calcium hydroxide, magnesium oxide, titanium lactate, and the like. It is also possible to add a water-soluble polymer substance for the purpose of increasing viscosity. The amount added is usually in the range of 5 to 500% in terms of solid content based on the emulsion. Such water-soluble polymer substances include
Examples include PVA, starch, CMC, hydroxymethylcellulose, hydroxyethylcellulose, methylcellulose, casein, etc., and these can be mixed in any form such as an aqueous solution or powder. The paint of the present invention can be applied to various locations using various coating methods such as brush, spray, roller, and dipping to form a good coating film. Generally used for interior painting, with good adhesion and sealing properties for wood, walls, wallpaper, concrete, plaster, stone, stucco, etc., and for painting general buildings, interior painting of ships and vehicles, hospital rooms, and cooking. It is ideal for painting places, etc., but it is not limited to this, and can also be applied to road paints and metal surfaces. The paint of the present invention may contain extender pigments such as calcium carbonate, clay, talc, mica, pallite, and ziecrite, coloring pigments such as titanium white, red iron, carbon, ocher, cyanine blue, and Hansa Yellow, and cellulosoblu acetate. , volatile film-forming aids such as butylcarpitol acetate, antifreeze agents such as ethylene glycol, and general paint aids such as plasticizers, dispersants, antifoaming agents, thickeners such as alkali, and antifungal agents. Reagents used as agents can be blended as appropriate. Next, the present invention will be specifically explained with reference to Examples. In the examples, "parts" or "%" represent "parts by weight" or "% by weight." Example 1 Acetoacetylated PVA with an average degree of polymerization of 1700, residual acetic acid group 1 mol%, and degree of acetoacetylation 2.3 mol%
An emulsion for paint was obtained in the following manner. In a separate flask equipped with a stirrer, reflux condenser, addition funnel, and thermometer, add 131.3 parts of the above water.
11.5 parts of PVA and 10 parts of vinyl acetate monomer were charged, and the temperature inside the flask was raised to 60°C while stirring. While replacing the inside of the flask with nitrogen gas, 2 ml of 10% H ₂ O ₂ water and 3 ml of 10% tartaric acid were added to initiate polymerization. Initial polymerization was carried out for 30 minutes, and the remaining 90 parts of vinyl acetate monomer was added dropwise over 3 hours to charge all the monomers. Afterwards, the mixture was aged at 70°C for 1 hour and then cooled. The obtained emulsion had good fluidity. Table 1 shows various characteristics. Control example 1 Acetoacetylation used in Example 1
Instead of PVA, use regular PVA (average degree of polymerization 1700,
An emulsion was obtained in the same manner as in Example 1 using 1 mol % of residual acetic acid groups. Table 1 shows various properties of the emulsion. Example 2 Acetoacetylated PVA with average degree of polymerization of 1800, residual acetic acid groups of 12 mol%, and degree of acetoacetylation of 1.6 mol%
An emulsion was obtained in the following manner. In the same apparatus as in Example 1, 155.5 parts of water and the
Initial polymerization was carried out in the same manner as in Example except that 7.0 parts of PVA and 10 parts of vinyl acetate monomer were used. Thereafter, the remaining 90 parts of vinyl acetate monomer was added dropwise over 2 hours, and after completion of the addition, the mixture was aged at 75°C for 1 hour and then cooled. Table 1 shows various characteristics. Control example 2 Acetoacetylation used in Example 2
Instead of PVA, use regular PVA (average degree of polymerization 1800,
An emulsion was obtained in the same manner as in Example 2 using 12 mol % of residual acetic acid groups. Table 1 shows various properties of the emulsion. Example 3 Acetoacetylated PVA with an average degree of polymerization of 1400, residual acetic acid group 1 mol%, and degree of acetoacetylation 5.9 mol%
An emulsion was obtained in the following manner. 11.0 parts of the above PVA, 0.5 parts of Emulgen 950 (polyoxyethylene nonylphenol ether, manufactured by Kao Seiken), 70 parts of vinyl acetate monomer, 30 parts of butyl acrylate, and 101.5 parts of water were charged into the same apparatus as above, and 5 parts of ammonium persulfate was charged. % aqueous solution 5ml,
5 ml of a 5% aqueous solution of sodium bisulfite was added, and emulsion polymerization was carried out at 40 to 50°C for 30 minutes and at 80 to 85°C for 3 hours under a nitrogen gas atmosphere. Table 1 shows various characteristics. Control example 3 Acetoacetylation used in Example 3
In place of PVA, average degree of polymerization 1400, residual acetate group 1
An emulsion was obtained in the same manner as in the example except that mol % of PVA was used. Table 1 shows various characteristics. Example 4 Acetoacetylated PVA with an average degree of polymerization of 1800, residual acetic acid group 1 mol%, and degree of acetoacetylation 3.5 mol%
An ethylene/vinyl acetate/vinyl chloride copolymer emulsion was obtained in the following manner. Add 100 parts of water and the above to the autoclave for polymerization.
Charge 8 parts of PVA, raise the internal temperature to 65℃ and PVA
Then, ethylene was introduced under pressure to maintain the temperature at 30Kg/ ^cm2 , the internal temperature was raised to 75℃, and 40 parts of vinyl chloride and
Emulsion polymerization was carried out by dropping 45 parts of vinyl acetate and 8 parts of a 5% aqueous solution of ammonium persulfate over 5 hours, the ethylene pressure was returned to normal pressure, and after further aging for 1 hour, the concentration was adjusted to 50%. . Table 1 shows various characteristics. Example 5 Using the same acetoacetylated PVA as in Example 4, a vinyl acetate/veova (vinyl ester of carboxylic acid branched at the α-position: trade name of Ciel Chemical) copolymer emulsion was obtained in the following manner. Charge 100 parts of water and 8 parts of the above PVA into a polymerization container, raise the internal temperature to 65°C to dissolve the PVA, further raise the temperature to 75°C, and then add 50 parts of Veova and vinyl acetate.
50 parts of ammonium persulfate and 8 parts of a 5% aqueous solution of ammonium persulfate were simultaneously added dropwise over 3.5 hours to carry out emulsion polymerization, and after further aging for 1 hour, the concentration was adjusted to 50%. Table 1 shows various characteristics. Example 6 Using the same acetoacetylated PVA as in Example 4, a butyl acrylate/styrene copolymer emulsion was obtained in the following manner. An emulsion having a concentration of 50% was obtained in the same manner as in Example 5, except that the monomers were changed to 60 parts of butyl acrylate and 40 parts of styrene, and 0.2 parts of dodecyl mercaptan was added as a chain transfer agent.
Table 1 shows various characteristics.

【table】

[Table] Example 7 100 parts of ethylene-vinyl acetate copolymer emulsion (resin content 50%, viscosity 530 cps), polymerization degree 1700,
2.5 parts of acetoacetylated PVA with residual acetate groups of 1 mol % and degree of acetoacetylation of 5.4 mol % were added and mixed. The characteristic values of this emulsion are shown in Table 2. Examples 8 to 13 In Example 8, 100 parts of vinyl acetate resin emulsion (resin content 50%, viscosity 7400 cps) was mixed with acetoacetylated PVA with a degree of polymerization of 1700, residual acetic acid groups 1 mol %, and acetoacetylation degree 2.3 mol %. In Example 9, 2 parts and in Example 10, 6 parts were added and mixed. In addition, 100 parts of the above emulsion has a polymerization degree of 1800 and residual acetic acid groups.
1 part of acetoacetylated PVA with a degree of acetoacetylation of 12 mol% and acetoacetylation degree of 1.6 mol% in Example 11;
In Example 12, 2 parts and in Example 13, 6 parts were added and mixed. The properties of the obtained emulsion are shown in Table 2. Comparative Examples 4 to 6 Comparative Example 4 was the same as Example 7 except that PVA (degree of polymerization 1700, residual acetic acid group 1 mol%) was used, and PVA (degree of polymerization 1700, residual acetic acid group 1 mol%) was used in Example 9. In Comparative Example 5 and Example 12, PVA (polymerization degree
Comparative Example 6 was a case in which the same procedure was carried out except that 1800 and 12 mol % of residual acetic acid groups were used, and the emulsion properties of each are shown in Table 2.

[Table] Example 14 Acetoacetylated PVA with a degree of polymerization of 500, a residual acetic acid group of 1.3 mol%, and a degree of acetoacetylation of 2.3 mol% was produced. Dissolve 4.0g of the above PVA in 31.0g of 50℃ warm water,
Next, 65 g of Epicote 828 (liquid bisphenol A type epoxy resin, manufactured by Shell Chemical Co., Ltd.), which had been preheated to about 50° C., was gradually added and vigorously stirred with a high-speed mixer to obtain an epoxy resin emulsion. The properties of the emulsion are shown in Table 3. Control Example 7 The same experiment as in Example 14 was carried out, except that PVA with a residual acetate group of 1.3 mol % and a degree of polymerization of 500 was used instead of the above PVA. The results are also shown in Table 3. Example 15 8 parts of acetoacetylated PVA having a degree of polymerization of 1700, a residual acetic acid group of 1.9 mol %, and a degree of acetoacetylation of 3 mol % was dissolved in 82 parts of water and kept at 65°C. Next, pre-molten hexadecyl ketene dimer was gradually added dropwise, and emulsion was formed using a homogenizer to obtain a ketene dimer emulsion. The performance of the emulsion is shown in Table 3. Control Example 8 The same experiment as in the above example was carried out except that PVA having a residual acetate group of 1.9 mol % and a degree of polymerization of 1700 was used in place of the above PVA. The results are also shown in Table 3. Example 16 15 parts of the emulsifier used in Example 15, 15 parts of water, 100 parts of atactic polypropylene (average molecular weight 18,000)
A small amount of octadecylamine acetate was added and kneaded in a kneader at 90°C for 20 minutes. Water was added to obtain a 30% solids polypropylene emulsion. The results are shown in Table 3.

【table】

[Table] Performance evaluation test 1 as a paint (emulsion-type flat paint) Using the emulsions of Examples 1, 4, 5, and 6, paints a, b, c, and d with the following compositions were prepared.
150-200g/ ^m2 for glass plates and flexible plates
(Solid content) was coated and dried at 25°C for 5 days to prepare test pieces, and the following tests were conducted and the test results shown in the table were obtained. (Emulsion type flat paint composition) Emulsion (50%) 1200 parts Hydroxyethyl cellulose 2% aqueous solution 250〃 Pigment dispersant 20〃 Calcium carbonate 420〃 Titanium oxide 780〃 25% ammonia water 5〃 Water Approx. 200〃 (Test method) (1 ) Adhesion test (cross-cut method) Performed on a glass plate test piece. Eleven crosscuts (100 cuts) with a width of 3 mm in length and breadth were made on the test surface, cellophane tape was applied, and immediately peeled off, and the state of peeling was observed. 〇: No peeling △: Partial peeling ×: Complete peeling (2) Water resistance Tested on flexible board test pieces. Fill a glass container with water to a depth of 150 mm, immerse the test piece in the water to a depth of approximately 120 mm, leave it for 96 hours, then take it out and examine the coating immediately. At this time, no wrinkles, creases, blisters, or peeling were observed in the paint film, and the test piece was left standing indoors for 2 hours, and the paint film was examined again. If there is not a large difference in color and gloss between the part and the part that is not immersed, mark it as ``no abnormality even if immersed in water''. Items with abnormalities are marked with an x. (3) Washing resistance Tested using a glass plate test piece. Using a Gardner wash resistance tester, measure the number of times it takes for the paint film to break (one round trip is counted as one time). Test 2 (Ringing effect paint) Using the emulsions of Examples 1, 4, 5, and 6, paints e, f, g, and h with the following compositions were prepared, and applied to a flexible plate with a metal trowel at approximately 1 kg/m ² (Solid content) was coated and dried at 25°C for 5 days to prepare test pieces, and the following tests were conducted and the test results shown in the table were obtained. (Ringing effect paint composition) Emulsion (50%) 100 parts 7th ring (approximately 2 mm) crushed canary stone 2000〃 Water or acetoacetylated PVA was used to adjust the paint viscosity to 20,000 to 30,000 centipoise. Adjust. (Test method) (1) Water resistance: Same as Test 1 (2). (2) Contamination Resistance After the test pieces were exposed outdoors for 3 months, they were washed with water and the state of contamination was observed by comparing them with those that were not exposed. 〇: Almost no stain △: Moderate stain ×: Significant stain Test 3 (convex pattern paint) Using the emulsions of Examples 1, 4, 5, and 6, paints i, j, and Create k, l,
A flexible board was bombarded with a mortar gun at a rate of about 1 kg/m ² and dried at 25° C. for 5 days to prepare test pieces. The following tests were conducted and the test results shown in the table were obtained. (Convex pattern coating composition) Emulsion (50%) 200 parts Calcium carbonate powder (5 μm) 400 (50 μm) 100 (100 μm) 100 Pulp fiber 10 Talc 50 Pigment dispersant 1 Paint The viscosity is adjusted to approximately 200,000 centipoise using water or acetoacetylated PVA. (1) Water resistance: Same as test 1 (2). (2) Pattern shape 〇: Almost hemispherical △: Between 〇 and × ×: Pattern that scatters or splatters

【table】

Claims (1)

[Claims] 1 A paint made of a synthetic resin emulsion containing acetoacetylated polyvinyl alcohol as a protective colloid.