JPH03287634A - Coated polycarbonate molding and preparation thereof - Google Patents

Abstract

PURPOSE:To improve surface hardness, abrasion resistance, weatherability, and adhesive properties by forming a cured coating film from a specific silicone ladder oligomer on the surface of a polycarbonate molding. CONSTITUTION:5-50wt.% (meth)acrylate copolymer having carboxyl groups and obtd. by copolymerizing 80-98 pts.wt. (meth)acrylate with 20-2 pts.wt. monomer having a carboxyl group [e.g. (meth)acrylic acid] and 0.01-2wt.% silane coupling agent are dissolved in a solvent to give a primer compsn. Separately, 100 pts.wt. silicone ladder oligomer of the formula (wherein R is 1-5C alkyl, phenyl, or hydroxyl; the molecular terminals are methoxy, ethoxy, or hydroxyl; and n is 3-100), 0.01-5 pts.wt. silicone surfactant, and 0.01-3 pts.wt. curing catalyst are dissolved in a solvent to give a top coating compsn. Then, the surface of a polycarbonate molding is coated with the primer compsn., dried at 20-100 deg.C for 5-30min, coated with the top coating compsn., dried at 20-100 deg.C, and heated at 70-130 deg.C for 10min to 3hr to cure the coating film.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention has excellent surface hardness, abrasion resistance (scratch resistance), weather resistance, and transparency, and has extremely strong adhesion to polycarbonate molded products. The present invention relates to a coated polycarbonate molded article having a cured film and a method for producing the same.

[Conventional technology]

Polycarbonate resin is widely used as a transparent plastic material because it has poor heat resistance, mixing resistance, cold resistance, transparency, and strength, but it also has the disadvantage of having low surface hardness and being easily scratched. As a method for improving this drawback, a hard coating method has been proposed in which the surface of the polycarbonate molded product is coated with various coating materials, but it is not always fully satisfactory.

For example, a typical method for hard court is (meta)
A method of applying an acrylic acid ester and curing it with ultraviolet light, and a method of applying a silicone monomer and curing it by heating are known. However, the former method does not provide sufficient surface hardness, and the latter method not only needs to be carried out in a completely controlled humidity and temperature workplace, but even when carried out in a workplace that is controlled in this way, the surface hardness still remains. However, it has the disadvantage of varying weather resistance.

In recent years, with the rapid development of molded products made of transparent plastic materials, especially in the fields of lenses, compact discs, and optical discs, polycarbonate molded products are also becoming increasingly popular.
Furthermore, there has been a strong demand for the development of a coated polycarbonate molded article that can provide a cured film with excellent performance with a simple operation, and a method for manufacturing the same.

[Problem to be solved by the invention]

The object of the present invention is to overcome the drawbacks of the conventional coated polycarbonate molded products, to provide a product that is easy to operate, has excellent surface hardness, abrasion resistance, weather resistance, and transparency, and has extremely strong adhesion to polycarbonate molded products. An object of the present invention is to provide a coated polycarbonate molded article having a cured film and a method for producing the same.

[Means to solve the problem]

The present invention provides a coated polycarbonate molded article that can achieve the above object and a method for producing the same.

That is, the present invention provides a method in which a cured film of a ladder-type silicone oligomer containing a silicone surfactant is formed on the surface of a polycarbonate molded article via a film of a (meth)acrylate copolymer having a carboxyl group. The present invention relates to a coated polycarbonate molded article characterized in that:

In addition, the present invention applies a solution of a (meth)acrylic ester copolymer having a carboxyl group to the surface of a polycarbonate molded article, dries it, and then applies a solution containing a ladder-type silicone oligomer, a silicone surfactant, and a curing catalyst. The present invention relates to a method for producing a coated polycarbonate molded article, which comprises coating the coated polycarbonate molded article, drying it, and then curing it by heating.

The present invention will be explained below.

In addition to ordinary polycarbonate resins, the polycarbonate molded products used in the present invention include diethylene glycol bisallyl carbonate resin (trade name CR-3).
Examples include automobile window glass, instrumentation panels, electrical product housings, furniture, architectural window glass, medical equipment, fashion lenses, sunglasses, compact disks, optical disks, etc. formed from 9).

The (meth)acrylic ester copolymer having a carboxyl group used as an undercoat for these polycarbonate molded products is a (meth)acrylic ester (in this specification, both acrylic ester and methacrylic ester). A carboxyl group is introduced into a part of the polymer by copolymerizing a monomer with a carboxyl group (the same applies in other cases) and a monomer having a carboxyl group.

(Meth)acrylic acid esters include methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, octyl (meth)acrylate, and (meth)acrylate. Dodecyl acrylate, (meth)octadecyl acrylate, (meth)
Examples include cyclohexyl acrylate, methylcyclohexyl (meth)acrylate, (iso)bornyl (meth)acrylate, and adamantyl (meth)acrylate.

Two or more of these (meth)acrylic esters may be used in combination.

Further, typical examples of monomers having a carboxyl group include (meth)acrylic acid, itaconic acid, 2-(meth)acryloyloxyethylsuccinic acid, 2-(meth)acryloyloxyethyl phthalic acid, and 2-(meth)acryloyloxyethyl succinic acid. ) Acryloyloxyethyl hexahydrophthalic acid, (meth)acryloyloxyethylmaleic acid, maleic anhydride,
Examples include fumaric acid.

The amount is 2 to 20 parts by weight of a (meth)acrylic acid ester and a monomer having a carboxyl group. The copolymerization is carried out by a conventionally known method such as a radical polymerization method.

In addition, in the present invention, a small amount of a component that reacts with carboxyl groups and crosslinks intramolecularly and intermolecularly by heating is incorporated into the (meth)acrylic acid ester copolymer having carboxyl groups, and this copolymer is It is also possible to apply the coalescing solution to the surface of a polycarbonate molded article, dry it, and then further heat it to cause a crosslinking reaction. Examples of this reaction include an amide bond-forming reaction by reacting a carboxyl group with an amine group, an ester bond-forming reaction by reacting a carboxyl group with a hydroxyl group, and the like.

When this (meth)acrylic acid ester copolymer having a carboxyl group is used as an undercoat, it is diluted with a solvent and used in the form of a solution to make it suitable for coating work. Examples of the solvent used include alcohols such as methanol, ethanol, and butanol, and in some cases, mixed solvents in which acetone, ethyl acetate, and the like are added thereto.

The degree of production of the (meth)acrylic acid ester copolymer having a carboxyl group in the solution may be determined as appropriate, but
Usually, it is preferably 5 to 50% by weight.

Adhesion is further improved by adding 0.01 to 2% by weight of a silane coupling agent to the undercoat.

Further, a crosslinking agent, a catalyst, etc. may be added to the undercoat as necessary.

This primer can be applied by dipping, spraying, flow coating,
It is applied to the surface of a polycarbonate molded product by a spin code method, a hand coating method, etc., and heated at 20 to 100°C for 5
By drying for ~30 minutes, a coat of primer is formed on the surface of the polycarbonate molded article.

The thickness of the undercoat film is generally between 0.1 and 2 microns, although it cannot be determined exactly.

Next, the top coat applied on the undercoat film will be explained. The topcoat is a ladder type silicone oligomer,
Main ingredients are silicone surfactant and curing catalyst,
It is prepared by dissolving these components in a solvent.

The ladder type silicone oligomer used to prepare the top coat has a structure represented by the following general formula (I).

- Monna [In the formula, R is an alkyl group having 1 to 5 carbon atoms, a phenyl group, or a hydroxyl group, and the terminal is a methoxy group, an ethoxy group, or a hydroxyl group.

n is a number from 3 to 100. ] This ladder-type silicone oligomer is easily cured by heating and forms a highly hard coating, making it suitable as a hard coating agent. is needed.

Therefore, when a silicone surfactant is blended with a ladder-type silicone oligomer and used, it contributes to adhesion, abrasion resistance, and weather resistance, and provides good results.

As silicone surfactants, C3H6 shown below
(OC2H4)a (OC3H6)bOR (m, n, a, b are integers of 0 or 1 or more, R is an alkyl group or H) can be used.

Examples of curing catalysts include alkalis such as amines, and specific metal salts. Typical curing catalysts that take into account the usability include a combination of formic acid and tetramethylammonium hydroxide. By adding a curing catalyst,
Ladder-type silicone oligomers can be cured at low temperatures and in a short time.

Examples of the solvent used include alcohols such as methanol, ethanol, and butanol, and in some cases, mixed solvents in which acetone, ethyl acetate, and the like are added thereto.

The content of the ladder type silicone oligomer in the top coat is preferably 5 to 50% by weight.

The amount of silicone surfactant used is 0.01 to 5 parts by weight, preferably 0.1 to 2 parts by weight, based on 100 parts by weight of the ladder type silicone oligomer. If the silicone surfactant is less than 0.01 part by weight, the effect of improving adhesion, abrasion resistance and weather resistance will be small, and if it exceeds 5 parts by weight, the surface hardness of the cured film of the ladder type silicone oligomer after heat curing will be reduced. It has the disadvantage that it decreases.

The amount of curing catalyst to be used cannot be determined unconditionally as it varies depending on the curing temperature and curing time, but it is usually 0.01 to 3 parts by weight, preferably 0.1 to 1 part by weight, based on 100 parts by weight of the ladder type silicone oligomer. Parts by weight.

The top coat is cured by heating polycarbonate coated with an undercoat by a conventional method such as dipping, spraying, flow coating, spin cording, or hand coating.

In this way, a cured film with excellent surface hardness, abrasion resistance, weather resistance, and transparency and extremely excellent adhesion to polycarbonate molded articles can be obtained.

The thickness of the cured film formed from the topcoat is between 1 and 10 microns, preferably between 2 and 5 microns.

The coated polycarbonate molded product of the present invention is characterized by forming a cured film of the top coat through the film of the base coat. ), has the disadvantage of poor weather resistance,
The cured coating of the topcoat alone has the drawback of poor hot water resistance and peeling of the cured coating, and the effects of the present invention cannot be achieved using either the undercoat or the topcoat alone.

[For production]

The film made of the carboxyl group-containing (meth)acrylic acid ester copolymer of the present invention has excellent adhesion to both the polycarbonate molded product and the cured film of the ladder-type silicone oligomer, so it can firmly integrate the two and In addition to exhibiting these characteristics, the adhesion between the two is maintained even under harsh conditions such as resistance to hot water.

Hereinafter, the present invention will be explained in more detail with reference to Examples and Comparative Examples. Note that "parts" in Examples and Comparative Examples indicate "parts by weight" unless otherwise specified.

In addition, in Examples and Comparative Examples, wear resistance, base material (
The adhesion and water resistance of the molded article were evaluated according to the following method.

(Abrasion Resistance) The coating was lightly rubbed with soooo steel wool back and forth 15 times, and then the degree of scratches on the coating was examined and evaluated in four ranks as shown below.

A: No scratches at all.

B: Less than 10 scratches occur.

C: 10 or more scratches or gloss still retained.

D = Loss of luster due to countless scratches.

(Adhesion to the base material (molded product)) Goban peel test, that is, make 100 cuts reaching the base material of 1 square millimeter with a razor on the film, paste cellophane tape on top of the cuts, and firmly cut upward at 90 degrees. The number of coatings remaining when peeled off was determined.

(Water Resistance) The sample was immersed in hot water at 70° C. for 300 hours, and after drying at room temperature, the adhesion test described above was conducted.

Example 1 2.5 parts of methyl methacrylate copolymer with a weight average molecular weight of 58,000, prepared by copolymerizing 83 parts of methyl methacrylate, 11 parts of hydroxyethyl methacrylate, and 6 parts of acrylic acid, 1 part of γ-aminopropyltrimethoxysilane An undercoat was prepared by dissolving 1 part of methyl cellosolve in a mixed solvent consisting of 42.5 parts of methyl cellosolve and 54 parts of n-butanol.

Moreover, the top coating agent was prepared as follows.

Ladder type silicone oligomer (polymethylsilsesquioxane, glass resin GR-650, weight average molecular weight f
fi 4,800) 30 parts of the silicone surfactant (L-7002, -
It was dissolved in a solution consisting of 1.5 parts of BO type (manufactured by Nippon Unicar Co., Ltd.), 43.5 parts of n-butanol, 18 parts of methyl cellosolve, and 7 parts of curing catalyst liquid.

Note that the curing catalyst liquid was prepared in advance as follows.

Add 1.25 parts of a 10% methanol solution of tetramethylammonium hydroxide to 50 parts of ethanol and stir well.
Then 2 parts of formic acid were slowly added and mixed with stirring.

The above-mentioned undercoat was applied to the surface of a commercially available polycarbonate plate (Corpilon E2000, manufactured by Mitsubishi Gas Chemical Co., Ltd.) by a dipping method, and heated at 80° C. for 0.5 hour to form a film. Next, the top coat was applied onto the undercoat film by the dipping method in the same manner as above, dried at 80°C, and then heated at 120°C for 1 hour to cure.

The resulting coated polycarbonate plate had a coating film with a thickness of 3.2 microns (base coat thickness 0.2 microns, top coat cured film thickness 3 microns), and a light transmittance of 91.
0%, and the evaluation of the steel wool abrasion test was A1, and the adhesion by the goban peel test was 100/100. Further, even when this cured film was subjected to a water resistance test at 70° C., no change in adhesion, abrasion resistance, or appearance was observed.

Comparative Example 1 In Example 1, a film was formed using the top coat of Example 1 without forming a film using the undercoat.

The obtained coated polycarbonate plate had a coating film with a thickness of 3 microns, the light transmittance was 91.0%, and the evaluation of the steel wool abrasion resistance test was A1, and the adhesion by the goban peel test was 100/100. Ta. However, when a water resistance test was conducted at 70°C, the cured film peeled off.

Example 2 A polycarbonate optical disc base material was set on a spinner, and methyl cellosolve was dropped onto the heart coated surface for 30 minutes.
It was washed by shaking it off at 00 rpm. This operation was repeated three times and then dried. Next, drop the primer of Example 1, apply by rotating at 200 rpm for 15 seconds, and apply at 80°C.
It was dried for 0.5 hours to form a film. Next, using a spinner in the same manner as above, a solution obtained by diluting the topcoat of Example 1 twice with an equal amount of methyl cellosolve was dripped onto this film while rotating at 1100 orp, and then
Apply by rotating at 00 rpm for 20 seconds, then apply at 80°C for 20 seconds.
A cured film was formed by heating for a period of time. The resulting coated polycarbonate optical disk substrate has a thickness of 2.8 microns (
It has a coating film with a thickness of 0.2 microns (undercoat film) and 2.6 microns (thickness of top coat cured film), and has a rating of A in the steel wool abrasion test, and an adhesion property in the goban peel test of +00/+00. Met. In addition, the adhesion and abrasion resistance after the 70°C water resistance test were also good.

Example 3 A well-washed lens made of ethylene glycol bisallyl carbonate resin (trade name CR-39) was immersed in the primer of Example 1, pulled up, and then heated at 100°C for 30 minutes to form a film. . Next, it was immersed in the top coating agent of Example 1, pulled up at a speed of 4 cm/min, and then heated to 130°C.
It was heated and cured for 1 hour.

The coating film of the obtained lens was 3 microns thick (undercoat film thickness 0.2 microns, top coat cured film thickness 2.8 microns), and the steel wool abrasion test evaluation was A.
, Adhesion by goban peel test is 100/100
There was. Further, no change was observed in adhesion or abrasion resistance after the 70°C water resistance test.

〔Effect of the invention〕

The coated polycarbonate molded product of the present invention has excellent adhesion, surface hardness, scratch resistance, and durability, and can be used as automobile window glass, interior parts, instrumentation panels, electrical products, etc.
It is useful for housings, furniture, architectural window glass, medical equipment, fashion lenses, Sunplus, compact discs, optical discs, etc.

Claims (2)

[Claims] (1) A cured film of a ladder-type silicone oligomer containing a silicone surfactant is formed on the surface of a polycarbonate molded product via a film of a (meth)acrylic acid ester copolymer having a carboxyl group. Characteristic coated polycarbonate molded product. (2) After applying a solution of a (meth)acrylic acid ester copolymer having a carboxyl group to the surface of a polycarbonate molded product and drying it, a ladder-type silicone oligomer,
A method for producing a coated polycarbonate molded article, which comprises applying a solution containing a silicone surfactant and a curing catalyst, drying it, and then curing it by heating.