JPH064810B2 - High solid type synthetic resin coating composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a vinyl chloride-based resin coating material which is highly soluble in an inexpensive solvent and can be applied thickly with a high solid resin solution.

[Conventional technology]

Vinyl chloride-based paints containing vinyl chloride copolymer as the main component have good chemical resistance, water resistance and weather resistance, and can be applied over freely, so they are widely used for coating structures made of steel or concrete.

However, since this type of vinyl chloride copolymer is essentially insoluble in aromatic hydrocarbons such as toluene and xylene or aliphatic alcohols such as ethanol and methanol that are inexpensive and suitable as a coating solvent, it is expensive. A system- or ester-based solvent such as methyl ethyl ketone, methyl isobutyl ketone, ethyl acetate, butyl acetate or the like is required. Further, if the resin concentration of the solution is increased, the viscosity is increased, and gelation is likely to occur when it is made into a paint. Since such a resin paint having poor solubility is diluted with a solvent and used at a low concentration, it has to be repeatedly applied multiple times to obtain a thick film, which is disadvantageous in economical efficiency and workability.

There are some documents regarding the high-concentration resinization of this vinyl chloride-based paint. For example, Japanese Patent Publication No. 47-28887 discloses that a high-concentration resin can be obtained by copolymerization of vinyl chloride and vinyl propionate and has a property of being dissolved in an aromatic hydrocarbon solvent. Also, the patent publication Sho 5
1-10, 873 include vinyl chloride, vinyl acetate and 2
-It is disclosed that the hydroxyalkyl acrylate copolymer has excellent compatibility with other resins, but the solubility for forming a high concentration resin is poor. Furthermore, the patent publication Sho 5
2-24,558 discloses that a resin obtained by copolymerizing vinyl chloride, a vinyl ester of a saturated carboxylic acid and a hydroxyalkyl acrylate can be a high solid content coating material having good compatibility with other resins. There is. However, since it is a copolymer having a high vinyl chloride content of about 70 to 90% by weight, it cannot be sufficiently converted into a high-concentration resin, and its solubility in an aromatic hydrocarbon solvent such as toluene or xylene is poor.

[Problems to be solved by the invention]

The object of the present invention is to improve the drawbacks of conventional products, that is, the inability to thickly coat and the poor solubility in inexpensive aromatic hydrocarbons and aliphatic alcohols, to a coating composition comprising a vinyl chloride copolymer resin. To provide things.

The terpolymer of the present invention is superior to conventional copolymers in terms of high-concentration resinization, and has a wide range of solubility in various solvents, particularly methanol, ethanol, etc. It has an effect on the solubility in aliphatic alcohol solvents. Dilution with an aliphatic alcohol solvent such as ethanol or methanol, which cannot be expected with conventional vinyl chloride resins, is possible.

[Means for solving problems]

That is, the present invention comprises (a) vinyl chloride monomer 50 to 69% by weight, (b) vinyl propionate monomer 16 to 40% by weight,
(c) A copolymer having a degree of polymerization of 100 to 600 obtained by randomly copolymerizing monomers consisting of 2 to 20% by weight of a glycol monoester monomer of acrylic acid or methacrylic acid in an organic solvent, an organic solvent, a pigment, Further, it is a highly compatible high solid type coating composition comprising an auxiliary agent added according to the purpose.

The randomness of the vinyl chloride copolymer resin used in the present invention is important for achieving high-concentration resin and improving the solubility in various solvents. In order to obtain a copolymer having high randomness, it may be carried out by a method such that the monomer composition distribution in the polymerization system is always uniform, and for example, it can be produced by the following method. That is, by supplying each monomer so as to maintain a constant monomer composition ratio in the polymerization system, depending on the respective polymerization rate, in other words, conversion of the monomer into a polymer. By supplying at a rate equal to the rate, the monomer composition distribution of the copolymer becomes more uniform.

The method described in Japanese Patent Application Laid-Open No. 61-278512 “Method for producing vinyl chloride copolymer” by the present applicant can be mentioned as a particularly preferable method.

The copolymerization is carried out in solution. As the solvent, one or a mixture of esters such as ethyl acetate and butyl acetate; ketones such as methyl ethyl ketone and methyl isobutyl ketone; aromatic hydrocarbons such as toluene and xylene; and the like are used. The ratio of the amount of solvent to the amount of monomer in the polymerization is about 3: 7 to 5: because the viscosity of the resulting resin solution is low.
Can be used between 5 Polymerization is possible even in a place where the solvent / monomer ratio is large, but this is not preferable because the productivity is poor and the price per resin component is high. A polymerization vessel is charged with a monomer, a solvent and a polymerization initiator, and polymerization is started at a predetermined temperature. The combination of temperature, monomer-to-solvent ratio and solvent type used controls the molecular weight of the resin. Degree of polymerization (J
IS K-6721, 0.2 g sample / 50 m nitrobenzene at 30 ° C.) is 100 to 600, preferably 20.
The thing of 0-500 is used. As the polymerization initiator, any oil-soluble compound that thermally generates a free radical, such as dibenzoyl peroxide, dilauroyl peroxide, diacetyl peroxide, azobis (isobutyronitrile), or isopropyl peroxydicarbonate can be used.

The vinyl chloride monomer is 50-6 based on the weight of the copolymer.
9% by weight is used. If the vinyl chloride monomer content is less than 50% by weight, the properties as a vinyl chloride-based paint, that is, chemical resistance, water resistance and weather resistance are poor. On the other hand, if it exceeds 70% by weight, the viscosity of the resin solution increases, a high concentration cannot be obtained, and the solubility in an inexpensive solvent such as aromatic hydrocarbons becomes poor.

The vinyl propionate monomer is used in an amount of 16 to 40% by weight based on the weight of the copolymer. If the vinyl propionate monomer is less than 16% by weight, the viscosity cannot be reduced,
Solubility in aromatic hydrocarbon solvents is also poor. Again 4
If it exceeds 0% by weight, the strength or water resistance of the coating film is lowered.

Examples of glycol monoester monomers of acrylic acid or methacrylic acid include monoesters of acrylic acid or methacrylic acid with glycols such as ethylene glycol, propylene glycol, butanediol and pentanediol. Particularly important monomers of the present invention are ethylene glycol or propylene glycol monoesters of acrylic acid or methacrylic acid. These monomers are used alone or in combination of two or more, and used in an amount of 2 to 20% by weight based on the weight of the copolymer. If it is less than 2% by weight, the reduction of the viscosity is insufficient and the dilutability with the aliphatic alcohol solvent is poor. Further, it is insufficient for obtaining an excellent coating film by curing reaction using a hydroxyl group, for example, curing with an isocyanate-containing urethane prepolymer. 20
If it exceeds 5% by weight, it is difficult to obtain a transparent resin solution free from turbidity, and an increase in this monomer is not preferable also in that it causes an increase in price.

The vinyl chloride copolymer resin solution thus obtained is added with an organic solvent, a pigment and, depending on the purpose, an auxiliary agent to form a paint.

〔The invention's effect〕

As apparent from the above description, according to the present invention, (1) a high-concentration resin is obtained because the viscosity of the same concentration in the resin solution of the same solvent is small, and the coating film thickness by one coating is large, The number of coating cycles is reduced, resulting in excellent workability and economy.

(2) It is economically advantageous because inexpensive aromatic hydrocarbons such as toluene, xylene, and ethylbenzene, and aliphatic alcohols such as ethanol and methanol are used as the solvent.

(3) Since the copolymer resin contains a hydroxyl group, it can be co-reacted with urea-formaldehyde resin, melamine-formaldehyde resin, epoxy resin or isocyanate-containing urethane prepolymer to form an excellent cured coating film.

(4) Furthermore, since this copolymer resin is a random copolymer, the compatibility with various polymers containing a hydroxyl group is significantly improved.

〔Example〕

Hereinafter, the present invention will be specifically described with reference to Examples and Comparative Examples. In the example sentence, "part" means "part by weight".

Examples 1 to 6 <Production of Vinyl Chloride Copolymer Resin> In a polymerization vessel of 1, the amounts of vinyl chloride monomer and vinyl propionate monomer shown in Table 1, 200 parts of ethyl acetate and 3 parts of dibenzoyl were added. Peroxide was charged and the temperature was raised to 65 ° C. To the polymerization vessel, the glycol monoester of α, β ethylenically unsaturated carboxylic acid shown in Table 1 was continuously fed over 6 to 10 hours. The resin after the polymerization was a clear solution with no turbidity and had no gel. Average degree of polymerization of resin (JIS K 672
1) is shown in Table 1.

Comparative Example 1 The procedure of Example 1 was repeated except that vinyl acetate was used instead of vinyl propionate. A clear solution with no turbidity is obtained,
The average degree of polymerization was 250.

Comparative Example 2 The same polymerization vessel as in Examples 1 to 6 was charged with 180 parts of vinyl chloride, 120 parts of vinyl propionate, 200 parts of ethyl acetate and 3 parts of dibenzoyl peroxide.
Then, the temperature was raised to 65 ° C. to carry out polymerization. A clear solution having no turbidity was obtained, and the average degree of polymerization was 300.

Comparative Example 3 A polymerization vessel was charged with 240 parts of vinyl chloride, 30 parts of vinyl propionate, 200 parts of ethyl acetate and 3 parts of dibenzoyl peroxide, and the temperature was raised to 65 ° C. Polymerization was carried out while continuously adding 30 parts of 2-hydroxypropyl acrylate thereto. The viscosity increased during the polymerization, and a gel that could not be stirred was produced.

Comparative Example 4 The amount of monomer in Comparative Example 3 was replaced with 180 parts of vinyl chloride, 30 parts of vinyl propionate, and 90 parts of 2-hydroxypropyl acrylate, and this was repeated. It becomes cloudy during the polymerization,
A gel formed.

<Solution Viscosity of Resin> Table 2 shows the viscosities of the 50 wt% ethyl acetate solutions of the resins of Examples 1 to 6 and Comparative Examples 1 and 2.

<Dilutability with Solvent> Table 3 shows the dilutability of the resins of Example 1 and Comparative Examples 1 and 2 with n-heptane, xylene and ethanol.

Test method: After adjusting the resin to a 10 wt% solution of methyl isobutyl ketone, add 5 g or 10 g of the solution to a beaker.
Weighed. Each solvent was added dropwise while stirring the solution, and the point at which the type of the newspaper below could not be seen was taken as the end point.

<Evaluation of coating film> Titanium oxide was added to the resin of Example 1 (Ishihara Sangyo: Taipaque R).
-820), stabilizer (oiled shell: Epikote 828)
And thinner (xylene / methyl isobutyl ketone =
1/1), solid content 46.0% by weight, viscosity 1,20
A coating composition of 0 centipoise (25 ° C) was obtained. The coating film performance was tested according to JIS K-5400, K-5582, and it was confirmed that the film passed sufficiently.

Further, the resin of Comparative Example 1 was similarly made into a coating material to obtain a coating composition, which had a viscosity of 3,300 centipoise (25
℃) and the pigment dispersibility was poor.

<Isocyanate-cured coating film> The resins of Examples 1 and 4 were examined for curing with isocyanate. As an isocyanate, Coronate HL
(Nippon Polyurethane, NCO content 13%) was blended so that the OH / NCO ratio was 1 to form a coating film. 23 ° C, 60
% RH After being left in a temperature-controlled room for 2 weeks, tensile test (Shimadzu:
Autograph IS-5000 type, pulling speed 10mm / mi
n) was performed.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification number Office reference number FI technical display area C08F 220: 28) (56) References JP-A-61-278512 (JP, A) JP-A-61 -126180 (JP, A) JP-A-60-206875 (JP, A) JP-B-52-50204 (JP, B2)

Claims (2)

[Claims] 1. A vinyl chloride monomer (a) 50 to 69% by weight, (b) vinyl propionate monomer 16 to 40% by weight, (c) acrylic acid or methacrylic acid glycol monoester monomer 2 Degree of polymerization of 100 to 600 by random copolymerization of monomers of 20 to 20% by weight in an organic solvent
High-solid type synthetic resin coating composition comprising the copolymer of 1., an organic solvent, a pigment and an auxiliary agent added according to the purpose. 2. A glycol monoester monomer of acrylic acid or methacrylic acid is ethylene glycol monoester or propylene glycol monoester of acrylic acid or ethylene glycol monoester or propylene glycol monoester of methacrylic acid. The coating composition according to item 1.