JPS6028459A - Acrylic lacquer - Google Patents

Abstract

PURPOSE:To provide an acrylic lacquer for application to iron plate, etc., with high water, weather and chemical resistance and coatability, which comprises a copolymer from p-methylstyrene and another monomer in a specific proportion. CONSTITUTION:The objective lacquer can be obtained by incorporating (A) a copolymer of a number-average molecular weight 5,000-50,000 from (i) 5- 95wt% of p-methylstyrene and (ii) 95-5wt% of another monomer (e.g., C1-18 alkyl acrylate or alkyl methacrylate) with, if required, (B) one or more ingredients selected from pigments, coating additives and fibrous compounds.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an acrylic lacquer, and more particularly to an acrylic lacquer having excellent water resistance, weather resistance and chemical resistance, which is obtained by using a specific copolymer obtained using a specific amount of para-methylstyrene. Regarding lacquer. Lacquer-type paints containing cellulose compounds are used in a wide variety of fields because of their performance, such as drying properties, and their ease of use.

Among these acrylic lacquers, acrylic lacquers whose resin composition includes aromatic vinyl monomers such as styrene and vinyltoluene as hard monomers are extremely excellent in terms of gloss and physical properties, and are particularly widely used.

However, since paints using these acrylic lacquers are air-drying, they are inferior to cross-linked paints in terms of performance, especially water resistance, weather resistance, and chemical resistance, and it is difficult to improve these properties. It was wanted.

As a result of intensive studies to solve the above problems, the present inventors discovered that these problems could be solved all at once by using paramethylstyrene as a component of the polymer, and arrived at the present invention.

That is, the present invention has a number average molecular weight of 50.000 obtained by copolymerizing (A) 5 to 95% by weight of halamethylstyrene and (B) 5 to 95% by weight of another copolymerizable monomer. This is an acrylic lacquer characterized by using a certain copolymer and, if necessary, one or more of pigments, paint additives, and fiber-based compounds.

Here, as the monomer (B) copolymerizable with paramethylstyrene (A), for example, alkyl acrylate or alkyl methacrylate having 1 to 18 carbon atoms, β-hydroxyethyl (meth)acrylate, β -Hydroxypropyl (meth)acrylate, acrylic acid,
Methacrylic acid, itaconic acid, fumaric acid, maleic anhydride, glycidyl (meth)acrylate, 2-ethoxymethyl (meth)acrylate, 2-ethoxymethyl (meth)acrylate, acrylonitrile, methacrylonitrile, cyclohexyl (meth)acrylate, etc. However, these can be used alone or in a mixture of two or more.

In the present invention, the amount of paramethylstyrene (A) used is 5 to 95% by weight, preferably 1% by weight in the resulting copolymer.
On the other hand, the amount of copolymerizable monomer (B) used is in the range of 5 to 95% by weight, preferably 2% by weight.
It ranges from 0 to 90% by weight.

In the present invention, the amount of paramethylstyrene used is 5% by weight.
If the amount is less, the water resistance and chemical resistance (alcohol resistance) of the acrylic lacquer will be poor, and if it exceeds 95% by weight, the weather resistance will be poor.

The acrylic lacquer having such a monomer composition has a glass transition temperature in the range of 40 to 95°C (the glass transition temperature is Fo
From the viewpoint of performance, it is preferable that each monomer to be copolymerized with para-methylstyrene be selected as follows:
It should also be done from this perspective. Further, the copolymer has a number average molecular weight of 5,000 to 50.00.
It needs to be in the range of 0, 6,000 to 3t1
．． Preferably, it is in the range of 000. The number average molecular weight in this case is expressed by a polystyrene equivalent value determined by gel vermation chromatography according to a conventional method. If the number average molecular weight is lower than 5.0 On, the water resistance, chemical resistance and weather resistance will be insufficient;
If the molecular weight is higher than 0.000, there is a problem in terms of spray workability due to stringiness.

In the present invention, to obtain a copolymer of paramethylstyrene and other copolymerizable monomers, any known polymerization method can be employed, but preferably a solution polymerization method is employed. The above-mentioned monomers are used, and the solvent is, for example, aromatic hydrocarbons such as toluene and xylene, esters such as ethyl acetate and butyl acetate, ketones such as methyl ethyl ketone and methyl isobutyl ketone, butanol and methanol. Alcohols can be used. The polymerization is generally carried out in the presence of a known radical initiator such as azobisisobutyronitrile, benzoyl peroxide, or t-butyl perbenzoate.

The acrylic lacquer obtained in this way can be diluted with a suitable thinner and used as a clear paint, and if necessary, one or more of pigments, paint additives, and cellulose compounds may be added as appropriate. They can also be used in combination. Examples of the pigment include pigments conventionally used in the paint field, such as inorganic pigments such as titanium oxide, red iron oxide, and carbonaceous pigments, and organic pigments.

In addition, additives for paint include antifoaming agents, leveling agents,
Known paint additives such as ultraviolet absorbers, antioxidants, and pigment dispersion aids are used in amounts.

Furthermore, examples of cellulose compounds include nitrified cotton and cellulose acetate butyrate.

As a method for applying the acrylic lacquer of the present invention, known methods such as brush coating, spray coating, or roll coating can be employed.

The above-described acrylic lacquer of the present invention has particularly excellent water resistance, weather resistance, and chemical resistance, and has excellent paintability by using a specific amount of paramethylstyrene.

Next, the present invention will be explained with reference to Examples and Comparative Examples.
Parts or percentages are by weight unless otherwise specified.

Examples 1 to 3 and Comparative Examples 1 to 4 After charging 500 g of toluene and 5009 butanol into a 4-ton flask equipped with a stirring device, an inert gas inlet, a thermometer, and a condenser, the temperature was raised to 98°C. At that point, the mixture shown in Table 1 was added dropwise over 4 hours each, and the same temperature was maintained for 7 hours to carry out polymerization to obtain the desired copolymer. The number average molecular weights of these copolymers were measured and summarized in Table 1. Next, to 100 parts of each of these copolymers, 10 parts of aluminum paste (manufactured by Toyo Aluminum Co., Ltd., trade name 1109MA) was added and dispersed, and then ethyl acetate/'n-butanol/butyl seron rub= The lacquer was prepared by diluting it with a thinner having a polymerization ratio of 40/'40/20 using a Ford cup flattener 4 for 30 seconds.

After that, this was air-sprayed to a film thickness of 15~
0.6 of Bonderite #144 treatment to make it 18μ
I painted my iron plate and baked it at 60℃ for 30 minutes.

Thereafter, each coating film was left at room temperature for 3 days, and the performance of each film was evaluated. The performance evaluation results are shown in Table 2.

Table 1 "Note" Measurement method Gloss; according to JISK-5400 According to the 60 degree specular gloss test method.

Erichsen extrusion test: Expressed as the maximum extrusion mm in which no cracks or the like occur in the coating film using an Erichsen tester.

Water resistance: Immediately after being immersed in 80°C hot water for 24 hours, it was visually judged by comparison with the original plate.

Weather resistance test: Based on the weather resistance test method according to JIS-5400.

patent applicant Mitsui Toatsu Chemical Co., Ltd.

Claims (1)

[Claims] (1) (A) 5 to 95% by weight of halamethylstyrene and (
B) A copolymer having a number average molecular weight of 5,000 to 50,000 obtained by copolymerizing with 5 to 95% by weight of other copolymerizable monomers, and pigments and paint additives as necessary. and an acrylic lacquer characterized by using one or more types of fiber-based compounds in combination.