JPS61281133A - Composition for coating surface - Google Patents

Abstract

PURPOSE:The titled composition, containing a specific acrylic resin, curing agent and alpha-alumina particles in a solvent, capable of forming films having high hardness and improved smoothness, adhesion, etc., and suitable for coating thermoplastics. CONSTITUTION:A composition obtained by incorporating (A) an acrylic resin having >=30 deg.C glass transition temperature and 20-120 hydroxyl value, (B) a curing agent for the component (A), e.g. amino resin or polyisocyanate compound and (C) 35-85wt%, based on the total solid content in the composition, particulate alpha-alumina having 5-50mum average particle diameter in a solvent, e.g. toluene or xylene.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field] The present invention relates to improved surface coating compositions, particularly AB
The present invention relates to a surface coating composition suitable for coating thermoplastic plastics such as S resin and polycarbonate resin.

[Summary of the invention]

The present invention provides a surface coating composition containing as a main ingredient an acrylic resin having a specific glass transition temperature and a specific hydroxyl value, a curing agent for the acrylic resin, and specific α-alumina particles. It is possible to form a coating having high hardness and excellent abrasion resistance, as well as excellent smoothness, adhesion, and chemical resistance.

[Conventional technology]

In recent years, as the proportion of thermoplastic molded products such as ABS resin and polycarbonate resin being used instead of metal parts in the fields of light electrical appliances and mechanical parts has increased, the surface durability such as wear resistance and scratch resistance of these materials has increased. There is a desire for improvement in sexual performance.

Conventionally, as a method to improve the durability of metal materials and wood-based flooring materials, (1) mineral substances mainly composed of aluminum oxide were added to the solid content of acid-curing amino alkyd resin or moisture-curing polyurethane resin; (Japanese Patent Publication No. 51-35487), (2) 5 to 30 parts by weight of α-alumina per 100 parts by weight of urethane resin. A composition containing 7.5 parts by weight and 2.5 to 5.0 parts by weight of silicon carbide (
(3) surface coating with a wear-resistant coating material such as a composition in which hard ceramics are mixed and dispersed in a wear-resistant thermoplastic resin (Japanese Patent Publication No. 54-4930); A treatment method has been proposed.

[Problem that the invention seeks to solve]

However, methods (1) and (2) above are methods for improving the durability of flooring materials, and it is not only difficult to impart surface durability to thermoplastic molded products, but also The adhesion to is also insufficient.

Furthermore, it is difficult to dissolve the abrasion-resistant thermoplastic resins used in method (3), such as nylon, polyacecool, Teflon, etc. in ordinary solvents, and it is therefore difficult to produce an abrasion-resistant coating material with good workability. The problem is that it is difficult.

The object of the present invention is to provide a surface coating composition that can form a film that has high hardness and excellent wear resistance, and also has excellent properties such as smoothness, adhesion, and chemical resistance. It is about providing.

Another object of the present invention is to form a film with excellent surface properties such as abrasion resistance and scratch resistance, so that it can be used particularly for coating thermoplastic molded products such as ABS resin and polycarbonate resin. The object of the present invention is to provide a surface coating composition that can be used for surface coating.

[Means for solving problems]

In order to achieve the above object, the present inventors conducted intensive research on various combinations of α-alumina and thermoplastic resin, and as a result, completed the present invention. That is, the present invention provides a surface characterized by containing an acrylic resin having a glass transition temperature of 30° C. or higher and a hydroxyl value of 20 to 120, a curing agent for the acrylic resin, and spherical α-alumina as main ingredients in a solvent. It is a coating composition.

The acrylic resin used in the present invention has a glass transition temperature of 30
Any acrylic resin having a temperature of 20 to 120 and a hydroxyl value of 20 to 120 may be used. If the glass transition temperature is less than 30°C, it is not preferable because not only the abrasion resistance and scratch resistance of the resulting coating film are significantly reduced, but also the stain resistance and weather resistance are deteriorated. In addition, if the hydroxyl value of the acrylic resin is less than 20, the solvent resistance, surface hardness, and abrasion resistance of the resulting coating film will decrease, and if it exceeds 120, the coating workability, adhesion, and weather resistance will decrease. This is not desirable as it will make things worse.

The acrylic resin contains hydroxyl group-containing monomers such as (meth)acrylic acid 2-hydroxyethyl ester, (meth)acrylic acid 2-hydroxypropyl ester, (meth)acrylic acid 4-hydroxybutyl ester, and hydroxyl group-free ( A monomer mixture containing meth)acrylic acid alkyl ester as an essential component, or a vinyl monomer copolymerizable with the essential component, such as styrene, vinyltoluene, vinyl acetate, acrylonitrile, methacrylic acid, acrylic acid, itaconic acid It is a resin obtained by polymerizing a monomer mixture containing the same or a mixture thereof using a conventional method. Note that (meth)acrylic acid in the above refers to either acrylic acid or methacrylic acid.

The curing agent for the acrylic resin used in the present invention is not particularly limited, and can be appropriately selected from conventionally known curing agents that can react with hydroxyl group-containing polymers, such as methyl etherified melamine resin, Amino resins represented by butyl etherified melamine resins, butyl etherified benzoguanamine resins, and butyl etherified urea resins; polyisocyanate compounds having at least two isocyanate groups in one molecule; two or more acid anhydride groups in one molecule Compounds or resins; silicone base resins having two or more alkoxysilane groups in one molecule; etc., among which amino resins and polyisocyanate compounds are particularly preferred as they exhibit remarkable effects as wear-resistant coating materials. used. The properties of the film can be controlled by adjusting the amount of the curing agent as appropriate depending on the combination of resin and curing agent, taking into consideration the amount of curing reactive groups and the like. Usually, the amount of reactive groups in the curing agent is equivalent to or less than the amount of reactive groups in the acrylic resin.

The raw material or manufacturing process for the spherical α-alumina particles used in the present invention is not particularly limited, but for example, T-
Preferably used are those produced directly as α-alumina spheres using alumina, or high-quality granular particles obtained by crushing and resintering a fine sintered body of α-alumina.

Next, regarding the particle size of the spherical α-alumina particles used, the average particle size in the range of 5 to 50 μm provides the best wear resistance. In other words, if it exceeds 50I1m, the frictional sliding will capture particles during the sliding process by the friction element, and they will easily separate from the resin layer.On the other hand, if it is less than 5μm, they will tend to behave in the same way as the acrylic resin, which will affect the resin properties. has a large influence, and the spherical effect tends to disappear. Regarding the sphericity of spherical α-alumina, it is best if all the particles are perfectly spherical, but α-alumina particles sufficiently exhibit their characteristics if about half of them are spherical.

The blending amount of the spherical α-alumina particles is preferably 35 to 85% by weight based on the total solid content of the surface coating composition, and if it is less than 35% by weight, the abrasion resistance and scratch resistance will be extremely poor. Moreover, if it exceeds 85% by weight, it is not preferable because it not only causes a decrease in painting workability but also causes a decrease in adhesion to substrates such as thermoplastic plastics as described above.

The solvent used in the present invention is not particularly limited as long as it does not cause deterioration of the surface to be coated. Examples include hydrocarbons such as toluene and xylene, and esters such as ethyl acetate and butyl acetate. and ketones such as methyl ethyl ketone and methyl isobutyl ketone.

When using the surface coating composition of the present invention, a predetermined amount of the acrylic resin, curing agent, spherical α-alumina particles, and diluting solvent are blended, and the composition is applied by spray coating, roll coater coating, etc. After that, the coating film is dried to obtain a strong film.

When formulating the composition, commonly used additives, colorants, pigments, thermoplastic resins, solvents, etc. may be added to the extent that they do not impair the effects of the present invention.

[Effects of the Invention] According to the present invention, the glass transition temperature of the acrylic resin is reduced to 30
°C or higher and the hydroxyl number is defined as 20 to 120,
In addition, by defining the shape of the α-alumina particles as spherical, a surface coating composition containing these two components and the curing agent for the acrylic resin as main ingredients in a solvent can be used as a surface coating composition compared to conventional wear-resistant coating materials. It is possible to impart excellent durability to the surface of thermoplastic molded products, and the coating workability is also good.

〔Example〕

The present invention will be specifically explained below using Examples.

In the examples, "part" means part by weight, and "%" means weight %.

(Examples 1 to 3) Using azobisisobutyronitrile as a polymerization initiator in toluene according to the polymerization composition shown in Table 1,
By polymerizing at ℃, toluene solutions of acrylic resins with different glass transition temperatures and hydroxyl values were obtained.

After adding Takenate D-11ON (manufactured by Takeda Pharmaceutical Co., Ltd.), a polyisocyanate compound, to this acrylic resin solution in an amount equivalent to the amount of hydroxyl groups in the acrylic resin, spherical α-alumina with a particle size of 10 μm was solidified. The coating material (
I), (II) and (Ill) were obtained.

Each coating material obtained in this way was applied to an ABS resin plate with a thickness of 30 μm.
It was spray-painted so that it became m, and it dried at 60 degreeC for 60 minutes. Table 1 shows the results of evaluating the coating film performance of the coated plates obtained by this method. From this result, it is clear that the wear-resistant coating material of the present invention exhibits extremely good wear resistance and scratch resistance.

(Comparative Examples 1 and 2) For comparison, Example 1 was used except that acrylic resins with different glass transition temperatures and hydroxyl values were used as shown in Table 1.
The coating material (IV
) and (V) were obtained. A coated plate was prepared using this coating material under the same conditions as in Example 1, and performance evaluation was performed.

The results are shown in Table 1.

(Example 4) Butyl etherified melamine resin (trade name Yubazo: 22R, manufactured by Mitsui Toatsu Chemical Co., Ltd.) was solidified in a mixed solvent solution of toluene and ethyl acetate of the acrylic resin used in the coating material (n) of Example 2. After mixing and dissolving the acrylic resin/melamine resin in a ratio of 70/30 (weight ratio), spherical α-alumina with a particle size of 10 μm was added to give a solid content of 65%, and the mixture was stirred at high speed. By doing so, a coating material (Vl) was obtained.

The coating material (Vl) thus obtained was applied to each molded product of polycarbonate resin, noryl resin, and nylon resin, and each molded product was dried at 110° C. for 60 minutes. It was observed that the obtained coated article exhibited excellent adhesion, abrasion resistance, and scratch resistance.

(Continued below in the margin on the next page)

Claims (1)

[Claims] 1. The solvent contains an acrylic resin having a glass transition temperature of 30° C. or higher and a hydroxyl value of 20 to 120, a curing agent for the acrylic resin, and spherical α-alumina as main ingredients. A composition for surface coating. 2. The surface coating composition according to claim 1, wherein the curing agent for the acrylic resin is an amino resin. 3. The surface coating composition according to claim 1, wherein the curing agent for the acrylic resin is a polyisocyanate compound. 4. According to any one of claims 1 to 3, the amount of the spherical α-alumina particles is 35 to 85% by weight based on the total solid content of the surface coating composition. Composition for surface coating.