JPS5950711B2 - Aqueous coating composition - Google Patents

Description

[Detailed description of the invention] The present invention relates to aqueous coating compositions.

A coating film obtained using a vinyl polymer emulsion using a neutralized product of a maleated polybutadiene polymer as an emulsifier has very excellent performance in terms of water resistance, alkali resistance, and quick drying properties.

However, since it is an emulsion, the dispersibility of the pigment is insufficient, the gloss is not sufficient, and the steel plate surface is easily rusted during drying after being coated on the steel plate. The inventors of the present invention conducted extensive research with the aim of eliminating the defects without reducing the excellent performance of emulsion paints, and found that the main chain of the resin itself is considerably hard compared to the vinyl polymer emulsion described above. It has been found that even if air drying properties are not sufficient, good results can be obtained by using a resin that has apparent drying properties or contains a large number of groups active in oxidative drying. Based on this knowledge, the combination use of water-soluble alkyd resins was considered to be highly desirable. However, water-soluble alkyd resins using trimellitic acid or dimethylolpropionic acid, which are generally used, are vinyl-based polymers using the neutralized product of the maleated polybutadiene-based polymer as an emulsifier. It was found that it could not be used because it had no compatibility with the combined emulsion and had poor storage stability. The reason for this is that in water-soluble alkyd resins, the carboxyl group, which becomes a water-soluble group when neutralized, is directly connected to the highly hydrophilic ester bond main chain, so the carboxyl group is bonded to the highly lipophilic main chain. It is not compatible with emulsions whose particle surfaces are covered with maleated polyptadiene (emulsifier), and such water-soluble alkyd resins take a form in which the ester bonds, which are susceptible to hydrolysis, are in direct contact with water. This seems to be because the emulsion is easily hydrolyzed and has poor storage stability, and the good storage stability of the emulsion is lost by mixing. As a result of further experiments, it was found that instead of the water-soluble alkyd resin, a water-soluble or water-dispersible resin obtained by maleating or fumarizing a fatty acid-modified polymer and then neutralizing the maleated polybutadiene-based polymer was used. It was discovered that when used in combination with a vinyl polymer emulsion containing a vinyl polymer emulsion as an emulsifier, both components are well compatible with each other, and a coating film can be obtained which eliminates the disadvantages of emulsion coatings without impairing their excellent features. completed. That is, the present invention is directed to (trans)drying or semi-drying oils having a number average molecular weight of 600 to 30, in which an average of two or more fatty acids are introduced into one molecule through ester bonds.
000 polymer is maleated or fumarized to give an acid value of 2.
0 to 300 and neutralized water-soluble or water-dispersible resin and a neutralized product of an (auto)maleated polybutadiene-based polymer as an emulsifier, the Q determined by the Q-e theory in a radical polymerization reaction. One or more hydrophobic polymerizable vinyl monomers with a Q value of about 0.1 or more, or about 90% by weight or more of one or more of the above vinyl monomers and a hydrophilic polymerizable vinyl monomer with a Q value of about 0.1 or more. A vinyl polymer emulsion obtained by emulsion polymerization of about 10% by weight or less of a polymerizable vinyl monomer is mixed in a resin solid weight ratio of (to)/(auto) = 0.05 to 20. This relates to an aqueous coating composition containing as a main component.

In the present invention, the resin obtained by maleating or fumarizing the fatty acid-modified polymer and then neutralizing it has a carboxyl group directly connected to a carbon-carbon chain with strong lipophilicity, and because this is in contact with water, it is susceptible to hydrolysis. Since the ester bonds are protected internally, it has good storage stability, and when mixed with the above emulsion, it is presumed that they are easily compatible because the structures of the mutually contacting parts are very similar.

In the present invention, the water-soluble or water-dispersible resin [hereinafter abbreviated as component] that is neutralized after maleating or fumarizing the fatty acid-modified polymer is a resin that is used to neutralize the fatty acid-modified polymer by converting the fatty acid of the drying or semi-drying oil into an ester bond. A polymer having a number average molecular weight of 600 to 30,000 in which an average of two or more molecules are introduced into one molecule is bonded with maleic anhydride, maleic acid, or fumaric acid near the carbon-carbon double bond based on the above fatty acid in the polymer. Maleated or fumarized with acid value 20-30
0 and then neutralized to make it water-soluble or water-dispersible, and has a structure in which an unsaturated fatty acid to which maleic anhydride, maleic acid, or fumaric acid has been added is connected to the polymer main chain through an ester bond. It is essential that the

A hydroxyl group for introducing fatty acids, which has an appropriate hardness as a substance to be modified with fatty acids constituting the above-mentioned prisoner component;
It has an epoxy group or a glycidyl group, and in the case of a hydroxyl group, it is necessary to have an average of 2 or more per molecule, and in the case of an epoxy group or a glycidyl group, it is necessary to have an average of 1 or more per molecule. Specific examples of these include alkyd resins, copolymer resins of acrylate or methacrylate having a hydroxyl group and other polymerizable monomers, copolymer resins of glycidyl acrylate or glycidyl methacrylate and other polymerizable monomers, styrene, vinyltoluene, etc. Examples include copolymer resins of and allyl alcohol, epoxy resins, and compounds having two or more hydroxyl groups in one molecule. Examples of monomers that can be copolymerized with the monomer containing a hydroxyl group and a glycidyl group include esters of acrylic acid or methacrylic acid and monoalcohols having 1 to 18 carbon atoms, styrene, vinyltoluene,
Mention may be made of the usual monomers such as α-methylstyrene, acrylamide, methacrylamide, acrylonitrile, methacrylonitrile and the like.

Examples of compounds having two or more hydroxyl groups in one molecule include ethylene glycol, propylene glycol, polyethylene glycol, polypropylene glycol, trimethylolethane, pentaerythritol, dipentaerythritol, sorbitol, diglycerol, and average molecular weight of about 1000. The following polyvinyl alcohols and partially saponified products thereof can be mentioned. Examples of the fatty acids of the drying oil or semi-drying oil used in the present invention include safflower monofatty acid, linseed oil fatty acid, dehydrated castor oil fatty acid,
Soybean oil fatty acid, hempseed oil fatty acid, oiticica oil fatty acid, eno oil fatty acid, sunflower oil fatty acid, tall oil fatty acid, tung oil fatty acid, corn oil fatty acid, grape kernel oil fatty acid,
Examples include poppy oil fatty acids.

The esterification reaction for introducing a fatty acid into a resin having a hydroxyl group, an epoxy group, or a glycidyl group may be carried out in accordance with a conventional method. For example, both components are placed in a reaction vessel and the
This may be carried out by heating to 250°C and stirring. It is preferable to introduce an average of two or more fatty acids per molecule of the resin having the above-mentioned functional groups, and this modification amount is usually 15% or more in terms of oil length in oil-modified alkyd resins, for example. desirable. Further, it is more preferable that the oil length is 30% or more. If the oil length is shorter than 15%, the hydrophilicity becomes strong and the compatibility with the emulsion of the present invention decreases, which is not preferable. The number average molecular weight of the polymer obtained by introducing the fatty acid thus obtained is in the range of 600 to 30,000, and when the number average molecular weight is less than 600, drying properties are decreased, and when it is greater than 30,000, the viscosity is high. The maleation or fumarization reaction becomes difficult, which is not preferable. Next, in the present invention, maleation is carried out by adding maleic anhydride or maleic acid, and fumarization is carried out by adding fumaric acid. The maleation or fumarization reaction may be carried out by a conventional method, for example, the fatty acid-modified polymer obtained above is placed in a reaction vessel together with maleic acid, maleic anhydride, or fumaric acid, and if necessary, a solvent, and the atmosphere is sufficiently purged with nitrogen. , usually about 150~ while stirring at high speed.
This can be done by heating to 250°C. The degree of maleation or fumarization is determined by increasing the oiliness of the main chain of the fatty acid-modified polymer itself, in order to improve the compatibility with the highly lipophilic acrylic resin emulsion, which is another component of the composition of the present invention. Therefore, the acid value of the resin after maleation or fumarization is usually 20 to 300, preferably 60 to 200, thereby imparting water solubility or water dispersibility to the resin.
When the acid value after maleation or fumarization is less than 20, water dispersibility and compatibility with the above emulsion decrease,
If it exceeds 300 degrees, the water resistance, weather resistance, etc. of the coating film will deteriorate.

The maleated or fumarated fatty acid-modified polymer thus obtained neutralizes the carboxylic acid groups as it is, except when maleic anhydride is used in the maleation reaction.
On the other hand, when maleic anhydride is used, water, alcohol,
Ring-opened with ammonia or amine, dicarboxylic acid,
After forming a half-esterified product and a half-amidated product, the carboxylic acid group is further neutralized. Examples of the neutralizing agent used to neutralize the carboxylic acid group include ammonia, amines, and alkali metal hydroxides, oxides, carbonates, and bicarbonates. The maleated or fumarized polymer can be water-solubilized or water-dispersed as described above, and if necessary, water-solubilization may be promoted using a small amount of an organic solvent. Next, the vinyl polymer emulsion used in the present invention [hereinafter abbreviated as component (B)] has a Q value determined by Q, e theory using a neutralized product of a maleated polybutadiene polymer as an emulsifier [for example, Asakura Co., Ltd. Bookstore, June 1972
"Polymer Dictionary" published on March 30th, page 162 and Ency
clOpediaOfPOlymerSciencea
ndTechnOlOgy, Ol4 (1966, J0h
nWiley & SOns, Inc. )] is 0.1 or more by emulsion polymerization of a polymerizable vinyl monomer. The polymerizable vinyl monomer with a Q value of 0.1 or more used here has the general formula CH2=C(R1
) COOR2 (However, R1 is hydrogen or methyl group, R2 has 1 to 18 carbon atoms
(representing an alkyl group), allyl acrylate, allyl methacrylate, styrene and its derivatives, acrylonitrile and methacrylonitrile.

These polymerizable vinyl monomers may be used alone or in combination of two or more, and one of the above vinyl monomers may be used in combination.
It is also possible to use water-soluble or hydrophilic vinyl monomers such as acrylic acid, methacrylic acid, itaconic acid, acrylamide, N-methylolacrylamide, etc. in an amount of about 0% by weight or less. A neutralized product of a maleated polybutadiene polymer used as an emulsifier when emulsion polymerizing a vinyl polymer emulsion can be easily obtained by maleating a polybutadiene polymer and then neutralizing it.

A wide variety of polybutadiene polymers can be used, but those with a number average molecular weight of about 200 to about 4
0,000, preferably about 500 to about 10,000, or a butadiene copolymer having the above number average molecular weight containing 10% by weight or more, preferably 40% by weight or more as butadiene units, or a polymer thereof. Modified products of and the like are preferred. The above-mentioned polybutadiene may have a 1,2-vinyl type, 1,4-trans type, or 1,4-cis type structure, and of course may be a partial mixture of these structures. do not have. Other monomers constituting the above putadiene copolymer include olefins having 2 to 18 carbon atoms, dienes other than butadiene (for example, isoprene, chloroprene, cyclopentadiene, etc.), acrylic acid or methacrylic acid and alcohol (carbon Examples include esterified products of formulas 1 to 16), styrene, a-methylestyrene, vinyletnolene, acrylonitrile, methacrylonitrile, and the like. Examples of modified butadiene-based polymers include polybutadiene or butadiene copolymers subjected to partial hydrogenation or cyclization reaction. The number average molecular weight of the butadiene-based polymer is about 200 to about 400.
It is preferably in the range of 00, and if it is less than about 200, the physical properties of the coating film and its action as a polymer emulsifier tend to deteriorate, and if it is more than about 40,000, the viscosity increases and the maleation reaction is carried out advantageously. This becomes difficult and is not desirable. In the present invention, the above-mentioned butadiene-based polymer is used as a polymer. To form a lane, the polymer is subjected to an addition reaction with maleic acid or maleic anhydride. This reaction may be carried out by placing the polymer in a reaction vessel together with maleic acid or maleic anhydride and, if necessary, a solvent, thoroughly purging with nitrogen, and heating the mixture to usually about 150° C. to about 3250° C. while stirring at high speed. In the maleated polybutadiene polymer thus obtained, when maleic acid is used in the maleation reaction, the carboxylic acid groups are neutralized after the maleation reaction.

On the other hand, when maleic anhydride is used, the ring is opened with 4-water, alcohol, amine, etc. to form a dicarboxylic acid, half-esterified product, or half-amidated product, and the carboxylic acid group is further neutralized.
After the maleation reaction, the polymer may be modified by hydroxylation or epoxidation, and then neutralized in the same manner as above. The degree of maleation, ring opening, and neutralization is determined based on the water-solubilizing ability and storage stability of the paint, usually when the acid value of the maleated butadiene polymer after final neutralization is in the range of about 20 to about 350. Preferably, it is in the range of about 40 to about 200. If the acid value is lower than about 20, the water solubilizing ability tends to be insufficient and the storage stability as a paint is poor.
This is not preferable since it may interfere with film formation in humid conditions. Neutralizing agents used for neutralizing carboxylic acid groups include ammonia, amines or alkali metal hydroxides, oxides, carbonates or bicarbonates,
As the amine neutralizer, primary, secondary, or tertiary amines, and polyvalent amines such as diamines, triamines, and tetramines can be used. The proportion of the emulsifier thus obtained may be appropriately determined within a range that allows efficient emulsion polymerization, and usually the theoretical acid value based on the total solid content of the final product produced by emulsion polymerization is Approximately 10 to 15
It is preferable to use it so that it is about 0. In preparing the composition of the present invention, it is sufficient to mix both the components ^ and (g) above, and if necessary, ordinary pigments, antirust pigments, dryers, etc. ) and I
B) The mixing ratio of the components is the solid content weight ratio, (to) component / old) component = 0.05-20) Desirably 0.1-9
A range of is preferred. If the mixing ratio is outside this range, the defects of each component will be noticeable and no synergistic effect will be observed by mixing. In other words, by mixing within this range, various properties such as gloss, corrosion resistance, coating film density, and pigment stability can be maintained without impairing the advantages of the emulsion of component (B), such as quick drying, water resistance, and alkali resistance. can be increased. Even in areas where the amount of emulsion is small, the overall gel fraction is significantly higher than the simple average due to the synergistic effect, so even if the blending ratio is 20, a sufficient effect can be observed. Further, the spaces between the emulsion particles can be filled considerably even with a ratio of 0.05. The present invention will be explained below with reference to production examples and examples. Production examples of maleated and fumarated polymers obtained by modifying fatty acids Production examples A-1 Styrene-allyl alcohol copolymer (molecular weight 1140, containing 7.5% by weight of 0H groups) Linseed oil fatty acid 635f! xylene
619 dibutyl thioxide 1.1g The above mixture was heated to 9
After heating for a period of time to cause an esterification reaction and dehydration, the acid value is 5.3.
(number average molecular weight approximately 2500).

Add maleic anhydride 2069 to this polymer to give a
After heating at 200° C. for 3 hours and purification under reduced pressure, 50 g of water was added and reacted at 100° C. for 2 hours to open the ring to obtain resin A-1 having an acid value of 133. Production example A-2 Phthalic anhydride 5499 Pentaerythritol 711f! Linseed oil fatty acids
30009 Mineral Spirits
2009 dibutyl thioxide
Put 209 or more raw materials into the 514 Tulo flask 2
A fatty acid-modified low molecular weight alkyd resin with an acid value of 3.5 was obtained by heating and dehydrating at 20°C for 5 hours [peak molecular weight 2 by gel permeation chromatography (G.P.C.)]
3001 number average molecular weight of about 900].

200 g of acetic anhydride was added to 1000 g of the above alkyd resin and heated at 150° C. for 4 hours to esterify the hydroxyl groups, and then excess acetic anhydride was removed. Next, maleic anhydride 1109 and xylene 1009 were added to this reaction product to give 180-2
Heating at 00° C. for 4 hours adds 97% by weight of maleic anhydride. After purifying under reduced pressure, add 100% of water and add 100% of water.
Resin A is ring-opened by reacting at ℃ for 3 hours and has an acid value of 90.6.
-2 is obtained. Production Example A-3 Fatty acid modified alkyd resin 1000f obtained in Production Example A-2
After esterifying the hydroxyl group with acetic anhydride in the same manner as in 1,
Maleic anhydride 1329 was added, and maleation reaction and ring-opening reaction with water were performed in the same manner to obtain resin A with an acid value of 102.
-3 is obtained.

Production Example A-4 1000g of fatty acid modified alkyd resin obtained in Production Example A-2
After esterifying the hydroxyl group with acetic anhydride in the same manner, maleic anhydride 160f! was added, and a maleation reaction and a ring-opening reaction with water were carried out in the same manner to obtain resin A with an acid value of 128.
-4 is obtained.

Production Example A-5 The number average molecular weight,
A fatty acid modified low molecular weight alkyd resin having almost the same acid value is obtained.

After esterifying the hydroxyl groups of this alkyd resin 5009 in the same manner as in Production Example A-2, maleic anhydride 1069 was added and heated at 180 to 200°C for 4 hours. Resin A-5 having an acid value of 110 is obtained after vacuum purification. Production example A-6 Phthalic anhydride 4419 Pentaerythritol 571f! Tung oil fatty acids 16909 Linseed oil fatty acids
721g dibutyl thioxide
20f! mineral spirits
161 g of the above mixture was heated and dehydrated at 180 to 200°C for 7 hours to obtain an alkyd resin having a number average molecular weight of about 1100.

After adding 420 g of fumaric acid and heating until the cloudiness disappears, unreacted substances and solvent are removed under reduced pressure to obtain resin A-6 having an acid value of 135. Production example A-J■■ (molecular weight 350, manufactured by Ciel Chemical Co., Ltd., trade name)
348f! Linseed oil fatty acids
9749 Sodium benzoate
0.49 toluene 6
6f! The above mixture is heated and dehydrated at 230 to 240°C for 12 hours to obtain a fatty acid-modified epoxy resin having a number average molecular weight of about 1500 and an acid value of 7.1.

Next, maleic anhydride 2309 was added and heated at 180 to 200°C for 3 hours, and after vacuum purification, 50 f1 of water was added to open the ring.
Resin A-7 with an acid value of 130 is obtained. Production Example A-8 440 g of xylene was placed in a 4-tube flask, and during 2 hours while refluxing at 140°C, n-butyl methacrylate 248f1 and 2-hydroxyethyl methacrylate 11 were mixed.
29 and a mixture of 25 g of 2,2'-azobis-2,4-dimethylvaleronitrile and 100 y of xylene are added dropwise from separate loads.

After 1 hour while continuing to reflux, 2,2'-azobis-2,4-dimethylvaleronitrile 59 and xylene 2
Add the mixture No. 09 and continue refluxing for an additional 5 hours. Next, 240 g of linseed oil fatty acid and 1 g of dibutyl thioxide are added to this reaction product, and heated to 210° C. while removing xylene.

Continue heating and dehydration at this temperature for 5 hours, and the number average molecular weight is approximately 1.
800) A resin with an acid value of 5.1 is obtained. To this, 105 g of maleic anhydride is added and heated at 180 to 190°C for 3 hours. After purification under reduced pressure, 30 g of water is added to open the ring to obtain resin A-8 with an acid value of 100. Production example of vinyl polymer emulsion using neutralized product of maleated polybutadiene polymer as emulsifier Production example B-1 Ring-opened product of 1,2-vinyl maleated polybutadiene with number average molecular weight 3000 and acid value 100 with water (Composition of polybutadiene: 1.2 bonds, 91% by weight, 9% by weight of 1,4-trans type), 400g of 29% ammonia water, 409g of 29% ammonia water
, butyl cellosolve 1489 and water 19839 are first mixed, then n-butyl methacrylate 10359, ammonium persulfate 2.51 and water 50.09 are added and dispersed, and polymerized at 80°C for 2 hours to obtain stable microemulsion B-1. .

Production Example B-2 Emulsion B-2 was obtained in the same manner as in Production Example B-1, except that the same amount of maleated polybutadiene ring-opened with methanol and having an acid value of 75 was used instead of the maleated polybutadiene used in Production Example B-1.

Production Example B-3 Styrene 615 was used instead of n-butyl methacrylate 10359 used in Production Example B-1.
A stable microemulsion B-3 was obtained in the same manner except that 420 g of 9 and 2-ethylhexyl acrylate were used.

Production Example B-4 Instead of 1035 g of n-butyl methacrylate used in Production Example B-1, 3119 g of methyl methacrylate was used.
A stable microemulsion B-4 was obtained in the same manner except that 311 g of styrene and 4139 2-ethylhexyl acrylate were used.

Production Example B-5 A stable microemulsion was produced in the same manner as in Production Example B-1 except that styrene 5629, 420 g of 2-ethylhexyl acrylate, and 52 g of 2-hydroxyethyl methacrylate were used instead of n-butyl methacrylate 10359. B-5 was obtained.

Production Example B-6 About 1% of n-butyl methacrylate 10351 used in Production Example B-1, that is, 10? A stable emulsion B-6 was obtained in the same manner as in Production Example B-1 except that allyl methacrylate was used.

Production Example B-7 Approximately 5% of the styrene 6159 used in Production Example B-3
Stable microemulsion B was prepared in the same manner as in Production Example B-3 except that %, that is, 311, was changed to methacrylonitrile.
-7 was obtained.

Production Example B-8 A stable microemulsion B-8 was obtained in the same manner as Production Example B-3 except that about 1%, or 6 g, of styrene 6159 was replaced with methacrylic acid.

Examples 1 to 4 Resin A-11009 Butyl cellosolve 389 Cobalt naphthenate (containing 5% metal) 1929% ammonia water 149 Clean water 120f1 The above mixed solution was used with emulsion B-1 at the mixing ratio shown in Table 1. Table 1 also shows the performance of the coating film when it was applied using the following methods.

For comparison, the coating film performance when using resin A-1 and emulsion B-1 alone is also shown. (Comparative Examples 1-2)
The mixing ratio of resin and emulsion is indicated by the weight ratio of each solid content. Examples 5 to 11 First, each resin obtained in Production Examples A-2 to A-8 was neutralized with the second formulation.

Table 3 shows the performance of the coating film when each of the above neutralized solutions and emulsion B-1 or B-2 were used at a mixing ratio of A/B = 3/7 (solid weight ratio). .

For comparison, the coating properties of each individual sample are also listed. (Comparative Examples 3 to 10) The method for measuring coating film performance was the same as the method in Table 1.

Examples 12 to 17 and Comparative Examples 11 to 16 Examples except that emulsions B-3 to B-8 obtained in Production Examples B-3 to B-8 were used in place of B-1 in Example 4, respectively. The coating film performance was examined in the same manner as in 4.

Claims (1)

[Scope of Claims] 1 (A) Number average molecular weight 60 in which an average of two or more fatty acids of drying or semi-drying oil are introduced into one molecule through ester bonds.
A water-soluble or water-dispersible resin obtained by maleating or fumarizing a polymer having an acid value of 0 to 30,000 to give an acid value of 20 to 300 and neutralizing it, and (B) a neutralized product of a maleated polybutadiene-based polymer as an emulsifier. , general formula CH_2=
C(R^1)COOR^2 (However, R^1 is hydrogen or methyl group, R^2 has 1 or more carbon atoms
Q determined by the Q-e theory in a radical polymerization reaction selected from esters of acrylic acid or methacrylic acid represented by One or more hydrophobic polymerizable vinyl monomers with a Q value of about 0.1 or more, or about 90% by weight or more of one or more of the above vinyl monomers and a hydrophilic polymerizable vinyl monomer with a Q value of about 0.1 or more. Approximately 10% by weight of polymerizable vinyl monomer
Resin solid content weight ratio of vinyl polymer emulsion obtained by emulsion polymerization of the following: (A)/(B) = 0.05 to 2
An aqueous coating composition containing as a main component a mixture of 0.0 and 0.0%.