JPS62236833A - Hard coating agent - Google Patents

Abstract

PURPOSE:To form a hard coating agent excellent in adhesion to polycarbonate resin or other engineering plastics and remarkably excellent in boiling water resistance, by mixing a silane condensate with butyral resin and water-based melamine resin. CONSTITUTION:100pts.wt. silane condensate is mixed with 4.0-10.0pts.wt. at least one butyral resin, 2.0-5.0pts.wt. (in terms of solid matter) water-based melamine resin, 0.2-0.3pt.wt. curing catalyst and 0.5-1.5pts.wt. cure accelerator. Exemplary of the silane condensate is one obtained by hydrolysis and condensation of an alkoxysilane. Exemplary of the butyral resin is one having a degree of polymerization of about 300-800 and a degree of butylation of about 63-70 + or -3mol%. Exemplary of the water-based melamine resin is a lowly condensed water-based methylated melamine resin.

Description

[Detailed description of the invention] Industrial applications The present invention relates to a hard coating agent.

Prior Art and its Problems Silane hydrolysis condensates have conventionally been used as hard coating agents to protect the surfaces of plastics. Silane condensates are excellent octo-coating agents that impart scratch resistance, weather resistance, solvent resistance, etc. to plastics. However, the silane condensate was used as a polycarbonate resin (hereinafter referred to as p), which is widely used as engineering plastic.
, c, resin), etc., it is undesirable because various problems such as those described below occur.

l) The silane condensate and P, C, resin do not adhere directly, so P, C, resin is
It becomes necessary to treat with a primer such as a pre-treatment liquid prepared with silane, γ-methacrylic 0+silvanic acid disilane, or a modified acrylic resin-based ashita coating agent.

2) Even if the silane condensate and the P, C0 resin are bonded together via a primer, the silane condensate film and the P, C0 resin will be bonded together.
, the adhesion strength with the resin is not sufficient. In particular, the silane condensate coating has poor boiling water resistance and undergoes changes such as cracking and whitening after 60 minutes of boiling, and loses its effectiveness.

3) The two-step processing method of treating the p, c, resin with a primer and then adhering the silane condensate coating is inefficient and therefore increases the operating cost. As a result of extensive research in view of the above problems, the present inventor has discovered the following:
The present invention was completed based on the discovery that a hard coating agent with extremely excellent adhesiveness and boiling water resistance can be obtained by blending a butyral resin and an aqueous melamine resin with a silane condensate.

That is, in the present invention, 1
Seed or two or more types of butyral resin 4.0 to 1000 parts by weight, aqueous melamine resin solid content 2.0 to 5.0 parts by weight, curing accelerator 0.5 to 1.5 parts by weight, curing catalyst 0.2 ~0.
3 parts by weight of the hard coating agent.

Examples of the silane condensate used in the present invention include silane condensates obtained by hydrolyzing and condensing alkoxydisilane. The method of hydrolyzing and condensing alkoxydisilane is not particularly limited, but may be carried out, for example, as follows. That is, hydrolyzed in a mixed solvent consisting of water and an alcohol solvent in the presence of an alkoxysilane acid catalyst,
A silane condensate can then be obtained by heating this solution and condensing the hydrolyzed Al+Shish and Ran. The above hydrolysis reaction is maintained at a temperature of 20° C. or lower and is completed in about 2 to 3 hours.

Further, the above condensation reaction is completed in about 1 to 3 hours under a temperature condition of about 50 to 60°C. As the acid catalyst and alcoholic solvent, any commonly used ones can be used.

In the present invention, the alcohol solution containing the silane condensate thus obtained may be used as it is, or the silane condensate may be isolated and used.

The hard coating agent of the present invention includes a silane condensate, a butyral resin, and an aqueous mela! :: By blending J resin,
It provides extremely excellent adhesion and boiling water resistance that cannot be expected with conventional hard coating agents made only of silane condensates.

Butyral resin has complete compatibility with the silane condensate used in the present invention, and is used as an adhesion improver and reinforcing agent for the silane condensate. Furthermore, butyral resin has the advantage that it does not impair the transparency of the silane condensate. Water-based melamine resins are also used as reinforcing agents and cross-linking agents for dithiral resins. By heating the silane condensate, the curing accelerator, the curing catalyst, the butyral resin, and the aqueous melamine resin under the same conditions, the crosslinked structure of the silane condensate and the crosslinked structure of the butyral resin are simultaneously formed. Due to the coexistence of these two types of crosslinked structures, the hard coating agent of the present invention has a high level of adhesiveness and strength, and also exhibits excellent boiling water resistance. For example, a degree of polymerization of about 300 to 800,
An example of a butylation degree is about 63 to 70±3 ma1%. Specific examples thereof include the BL series and 8M series of "ELEX B" (trade name, manufactured by Block Chemical Co., Ltd.).

The blending amount of butyral resin is Shirashi condensate xoom1m
The amount is preferably about 4.0 to 1080 parts by weight. If it is less than 460 parts by weight, adhesion is insufficient;
．． If it exceeds 0 parts by weight, there is a risk that adhesion will be impaired.

Further, as the aqueous melamine resin, any commonly used aqueous melamine resin can be used, such as a low condensation type aqueous methylated melamine resin. Specific examples include M, -30W, and M-4 of Suemar (product name, manufactured by Juju Chemical).
0W, M-5QiF.

A[)-101 etc. can be mentioned.

The amount of the water-based melamine resin to be blended is preferably about 2.0 to 5.0 parts by weight per 100 parts by weight of the shirashi condensate. If it is less than 2.0 parts by weight, crosslinking adhesion will be insufficient;
If the amount exceeds the weight part, adhesion may be impaired.

In the present invention, benzyltrimethyla:J7nium chloride or penzyltriethylA:J7nium chloride is used as a curing accelerator for the silane hydrolysis feed, and dibutyltin diacetate is used as a curing catalyst. The blending amount is 0.5 to 1.0 parts by weight, respectively, per 100 parts by weight of the shirashi hydrolyzed condensate.
The amount is preferably about 5 parts by weight, and about 0.2 to 0.3 parts by weight.

Further, in the present invention, special modified acrylic resin, liquid epoxy resin, etc. may be added to further strengthen the adhesiveness. Furthermore, if necessary, a small amount of ultraviolet absorber, silicone-based spreading agent, etc. may be added.
Part by weight, one or more butyral resins 4.0 to i
o, o parts by weight, aqueous mela, l resin solid content 2.0-5
．． 0 parts by weight, 0.5 to 1.5 parts by weight of a curing accelerator, and 0.2 to 0.3 parts by weight of a curing catalyst, in an alcohol-based mixture with a weight ratio of 5 to 6 times that of the silane hydrolysis feed. It is produced by sufficiently dissolving it in a mixed solvent consisting of a solvent, a polyhydric alcohol solvent, and an acetate solvent. To bake the hard coating agent of the present invention onto the plastic surface,
First, a hard coat agent may be applied to the plastic surface, and then baked by heating at about 125 to 130°C for about 40 to 60 minutes. As the coating method, a wide variety of conventionally known methods can be employed, such as spray coating, electrostatic coating, dipping coating, brush coating, and the like.

The hard coating agent of the present invention is not only used for p-, c-, and resins, but is also effective for industrial engineering plastics, such as polyethylene terephthalate resins.

The hard coating agent of the present invention exhibits the following excellent effects.

l) The coating film of the hard coating agent of the present invention applied to the plastic surface has excellent adhesive properties. In particular, its boiling water resistance is
It is significantly superior to conventional hard coating agents, and its protective effect on plastic surfaces remains unchanged even after 60 minutes of boiling.

2) The conventional two-step processing method can be omitted, resulting in a significant improvement in work efficiency and a significant reduction in work costs.

Examples and comparative examples are given below to further clarify the present invention.

Example! Methyltrimethoxyethyl 100 parts by weight Silicate Co-condensed metal Ral resin BL-1 (Sekisui Chemical Co., Ltd.) 5.0# Butyral resin BL-3 (Sekisui Chemical Co., Ltd.) 3. Of special modified acrylic resin H-4702, 5g (manufactured by Nippon Carbide Industries) Water-based melamine resin M-5011' 3.
0 1 (solid content, manufactured by Juju Chemical) Benzyltriethylantinium chloride 0.5#
Dibutyltin diacetate 0.2 parts by weight methyl trime, disilane and ethyl silicate were added dropwise to a mixed solvent of water and isopropyl alcohol containing an acid catalyst over 2 to 3 hours, keeping the temperature below 20°C. After hydrolysis, the solution was heated at 55° C. for 1.5 hours to obtain a methyltrimethodisilane-ethylsilicate co-assembly.

A predetermined amount of the above components is added to a mixed solvent consisting of an alcohol solvent, a polyhydric alcohol solvent, and an acetate solvent in an amount of 5 times the weight ratio of the methyltrimethodisilane-ethylsilicate cocondensate, and the components are mixed and dissolved to produce the present invention. A hard coat agent was manufactured.

The obtained hard coat agent was applied to a 2-inch thick plate of P and C0 resins, and then baked at 130°C for 60 minutes. The film thickness of the coating film after baking was 5 μm. This coating film was subjected to an adhesion test and a boiling water resistance test. Results first
Shown in the table.

Table 1 Comparative Example 1 Methyltrimethoxydisilane-ethyl 100 parts by weight Silicate cocondensation cocondensate Benzyltriethylantinium 0.51 Dibutyltinthiatate 0.21 Using the above components, alco+disilane was prepared in the same manner as in Example 1. A conventional hard coating agent consisting only of a condensate was manufactured. l!
The obtained hard coat agent was applied to a 2n-thick P, C, resin plate that had been pretreated with a modified acrylic resin undercoat agent, and baked at 130° C. for 60 minutes. This coating,
It was subjected to the same performance test as in Example 1. The results are shown in Table 2.

From the results shown in Table 2 and above, it can be seen that the hard coating agent of the present invention has significantly superior boiling water resistance compared to conventional hard coating agents.

9j! Example 2 Cocondensate butyral resin B L -12,5 parts by weight Butyral resin BL-32,5# Nium dibutyltin diacetate 0.21 Methyl triethane was prepared in the same manner as in Example I except that the gold condensation time was 2 hours. A disilane-condensate dimethylshed-disilane cocondensate was obtained.

A hard coat agent of the present invention was produced in the same manner as in Example 1 using the above components. The obtained hard coat agent showed excellent adhesion and boiling water resistance.

9! Example 3 Monozu Tyral Resin BL-14, 0# Butyral Resin BL-32, Op Liquid Epoch Resin Engineering Coat 1.5) Water-based Meramishi Resin M-30F! 3.0 (solid content) Benzyltrimethylchloride: J7 0.5nium dibutyltin diacetate 0.2 Methyltriethane disilane-vinyltriacetate was prepared in the same manner as in Example 1 except that the feeding time was 2.5 hours. A silane cocondensate was obtained.

A hard code agent of the present invention was produced in the same manner as in Example 1 using the above components. The obtained hard coat agent showed excellent adhesion and boiling water resistance.

5j! Example 4 Methyltrimethoxydisilane condensation 100 parts by weight Hardware butyral resin BL-15,Qt Water-based melamine resin M-50114.0# (solid content) Benzyltrimethylane chloride 1! : 0.5 #dibutyltin diacetate 0.2 parts by weight A methyltrimethodisilane condensate was obtained in the same manner as in Example 1 except that the feeding time was changed to 3 hours.

A docoating agent for the present invention was produced using the above components in the same manner as in Example 1 except that a mixed solvent consisting of an alcohol solvent and an acetate solvent was used as the solvent.

The obtained hard coating agent showed excellent adhesion and boiling water resistance.

(that's all)

Claims (1)

[Claims] (1) 4.0 to 10.0 parts by weight of one or more butyral resins, 2.0 to 5.0 parts by weight of aqueous melamine resin, and hardening accelerator per 100 parts by weight of the silane condensate. 0
．． A hard coating agent containing 5 to 1.5 parts by weight and 0.2 to 0.3 parts by weight of a curing catalyst.