JPS6038438A - Production of composite polycarbonate molding excellent in surface property - Google Patents

Abstract

PURPOSE:To obtain the titled molding excellent in surface hardness, weather resistance, etc., by forming a primer layer containing a specified copolymer on the surface of an aromatic polycarbonate molding and forming an energy ray- curable resin coating thereon. CONSTITUTION:A primer layer comprising a thermoplastic acrylic polymer containing an ultraviolet ray absorber is formed on the surface of an aromatic polycarbonate molding. On this surface a protective film of a synthetic resin obtained from an energy ray-curable polyfunctional acrylic compound is formed to produce a composite polycarbonate molding. A high MW (MW>=50,000) copolymer obtained by copolymerizing an alkyl methacrylate with an alkyl acrylate is used as the thermoplastic acrylic polymer for forming a primer layer. It is possible to obtain a composite polycarbonate molding having a coating excellent in surface properties such as surface hardness and excellent weather resistance.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a composite aromatic polycarbonate molded article having a coating film with excellent surface properties such as surface hardness and excellent weather resistance. More specifically, a single layer of primer made of a thermoplastic acrylic polymer is formed on the surface of an aromatic polycarbonate molded article, and then a polyurethane resin that is cured by energy rays, specifically ultraviolet rays or electron beams is applied on top of this single layer of primer. The present invention relates to a method for producing a composite aromatic polycarbonate molded article having a synthetic resin protective film formed from a functional acrylic compound.

Aromatic polycarbonate has various features such as being transparent, lightweight, having excellent mechanical properties, and being easy to process. Taking advantage of these properties, it is used as a structural component material to replace glass. As is well known, it is used for various purposes. However, compared to metals and glass, they are inferior in various surface properties such as surface hardness, abrasion resistance, scratch resistance, and solvent resistance, which naturally limits their use. Therefore, there is a strong need to improve the surface properties of aromatic polycarbonate molded articles.

In order to improve the surface properties of aromatic polycarbonate molded articles, various attempts have been made to apply paint to the surface of the molded article to form a protective film. For example, a method in which a thermosetting melamine resin paint is applied and a protective film is formed by thermosetting (Japanese Unexamined Patent Publication No. 47-35164,
No. 48-80175, No. 51-111276, etc.) or a hydrolysis product of an organosilane compound is coated and cured by heat to form a protective film made of organopolysiloxane. ! ! Method of forming a film (USff1%i'F No. 5,
No. 707,397, Japanese Unexamined Patent Publication No. 52-138565, and many others). however,
These are maintained by heating and curing! ! The film-forming method requires the molded product to be cured under harsh conditions, including high temperatures and long periods of time, and this treatment poses a risk of damaging the original excellent mechanical properties of the aromatic polycarbonate molded product. growing.

Additionally, K causes problems in the adhesion between the polycarbonate base material and the protective film and in the durability of the protective film itself.

On the other hand, as an alternative to heating and curing, a polyfunctional acrylic compound is used as a paint, and by irradiating it with energy rays such as ultraviolet rays or electron beams, it is converted into a cured resin.
A method of forming a synthetic resin protective film has also been proposed (for example, Japanese Patent Laid-Open Publication No. 7771/1982, Japanese Patent Publication No. 55/1983)
00855, Japanese Patent Publication No. 49-14859, Japanese Patent Publication No. 52-47765, and others).

Although the method proposed here has the advantage of completing curing in a short time, the adhesion between the polycarbonate base material and the protective film is not satisfactory, and the durability of the coating film
In particular, the weather resistance is not sufficient (for example, it turns yellow in about 500 hours using a Sunshine Weather-O-meter, and poor adhesion and deterioration of abrasion resistance are also observed.

The present inventors conducted extensive studies to improve the shortcomings of known techniques and completed the present invention.

That is, in the method of the present invention, a primer layer made of a thermoplastic acrylic polymer containing an ultraviolet absorber is formed on the surface of an aromatic polycarbonate molded article, and then energy rays, such as ultraviolet rays or In producing a composite aromatic polycarbonate molded product having a coating film with excellent surface properties by forming a synthetic resin protective film obtained from a polyfunctional acrylic compound that is cured by electron beams, it is necessary to It is unique in that a single layer of primer is formed using a plastic acrylic copolymer.

The thermoplastic acrylic copolymer used as the primer layer in the method of the present invention is a copolymer of methacrylic acid furkyl ester and 7-acrylic acid alkyl ester, and the copolymer composition is 7
0-90% by weight and acrylic acid alkyl ester 60-1
It means a copolymer consisting of 0 M% by weight, preferably 80 to 85% by weight of the former and 15 to 20% by weight of the latter. The copolymer composition specified here is important for the abrasion resistance of the cured resin layer (top coat layer) of a polyfunctional acrylic compound formed on a single layer of primer using this copolymer composition, and for the top coat layer during long-term use. It is involved in the adhesion of the acrylic acid alkyl ester.
If the amount of acrylic acid alkyl ester is small, adhesion will decrease. In addition, the thermoplastic acrylic copolymer is
Must have a specific molecular weight. i.e. 1
The thermoplastic acrylic copolymer suitably used in the method of the present invention needs to have a high molecular weight of 50,000 or more, preferably 100,000 or more. When the molecular weight is lower than 50,000, especially acrylic polymers with a molecular weight of around 30,000, which are easily available on the market, the wear resistance of the top foot layer is extremely low (
It has been observed that On the other hand, if the molecular weight of the thermoplastic acrylic copolymer is extremely large, the viscosity of the primer paint solution will be extremely high, which will impair the workability of primer application and make it difficult to obtain a smooth coating film. The molecular weight of the thermoplastic acrylic copolymer used in the invention is preferably 300,000 or less.The methacrylic acid alkyl ester used here includes methacrylic acid methyl ester, methacrylic ethyl ester, butyl methacrylate. It is a lower fullkyl ester of methacrylic acid, exemplified by ester, etc., and an acrylic acid alkyl ester is a lower alkyl ester of acrylic acid, exemplified by acrylic acid methyl ester, acrylic acid ethyl ester, acrylic acid butyl ester, etc. .

In particular, a copolymer of methyl methacrylate and butyl acrylate is preferably used.

The primer paint is used in the form of a solution in which the acrylic copolymer is dissolved in a solvent that does not corrode the polycarbonate substrate. However, unlike commercially available acrylic copolymers, the acrylic copolymers with a molecular weight of 50,000 or more used in the present invention are methyl ethyl ketone and acetate.

It dissolves only in highly soluble solvents such as toluene, and these solvents are good solvents for polycarbonate.
Therefore, when the heptacrylic copolymer of the present invention is dissolved in these good solvents.

This solution is unsuitable for use as a primer coating because it attacks polycarbonate moldings. The inventors.

Various studies have been conducted to resolve this inconvenience.

For polycarbonate, methacrylic acid alkyl ester and acrylic acid furkyl ester are copolymerized in ethylene glycol monoethyl ether, which is a poor solvent. It has been found that by obtaining a solution and using this solution as a primer coating, a desired primer layer can be suitably formed on a polycarbonate molded article. If desired, other solvents may be added to the acrylic copolymer solution obtained by the sintering method to adjust the viscosity of the primer coating, as long as it does not corrode the polycarbonate molded product. The method of using the acrylic copolymer solution obtained as a primer coating in this way is an extremely preferred embodiment of the method of the present invention.

The copolymer concentration in the primer paint containing the above acrylic copolymer is in the range of 5 to 30% by weight based on various factors such as workability, primer mm#) cracking in the base coat layer, etc. It is desirable that the In other words, the thicker the primer layer, the more likely cracks will occur when forming the top coat layer, and the more likely cracks will occur when the polycarbonate molded product on which the top coat layer is formed is used for a long time. has been observed. Therefore, it is desirable that the thickness of a single layer of primer be in the range of 5 to 25 microns, and the concentration of the primer paint solution may be appropriately selected from the above range in order to form such a film thickness.

As described above (by the method of the present invention, a primer layer made of a thermoplastic acrylic copolymer with a predetermined high molecular weight is formed on the surface of a polycarbonate molded product, and then a hardened acrylic resin AT+TIY is applied on the primer layer). Although a composite polycarbonate molded article having the desired surface properties can be formed, another important object of the present invention is to form a polycarbonate molded article that has excellent weatherability, i.e., the ability to withstand extended outdoor use. The aim is to provide products.

In order to achieve this objective, the inventors have found that it is necessary to prevent more than 80% of ultraviolet radiation with a wavelength of 300 to 380 mμ from reaching the surface of the polycarbonate substrate. Meeting such goals requires the use of significant amounts of UV absorbers, which is not a problem that can be solved in a top coat layer.

The present inventors have found that the above goal can be met by further improving the primer (after further investigation, the acrylic copolymer is used as a standard in the first layer of the primer made of the above-mentioned heat-floodable acrylic copolymer). It has been found that the desired objective can be achieved by blending an amount of UV absorber equivalent to 10 to 20% by weight.By blending such a large amount of UV absorber into a single layer of the primer, Surprisingly, no adverse effects were observed, not only in the primer layer itself but also in relation to the top foot layer. A composite polycarbonate molded product with good adhesion and a top foot with excellent wear resistance was obtained.

The ultraviolet absorber used here is benzotriacyl.
The UV absorbent may be appropriately selected from among the compounds commonly used as ultraviolet absorbers such as benzophenone, benzophenone, and benzony.

Examples of ultraviolet absorbers that are easily compatible with the acrylic copolymer of the present invention in amounts of 10 to 20% include 2-(2'-
Hydroxy-5'-tert-butylphenyl)benzotriazole (which is commercially available from Ciba Geigy under the trade name "Tinuvin PS") is particularly preferably used.

In the method of the present invention, the protective film formed on the single layer of primer is formed by using a paint made of a polyfunctional acrylic compound that can be cured by irradiation with energy rays, specifically ultraviolet rays or electron beams. Formed by irradiation with energy rays. A paint containing a polyfunctional acrylic compound is, for example, a paint containing a polyfunctional vinyl monomer having two or more (meth)7 acryloyl groups in one molecule or a polyfunctional vinyl monomer. and other crosslinkable vinyl monomers. As a specific ultraviolet curing paint, the product name provided by Nitto Kasei [
NUV-283<SJ, rNUV-165J or r
NUV-1010J and Mitsubishi Gas Chemical ■ product number rFtX
Examples include 9014J and rEX 90'15J.

Specifically, the method of the present invention is carried out according to the following operations. That is, a primer paint containing the high molecular weight acrylic copolymer of the present invention blended with an ultraviolet absorber is applied to the surface of an aromatic polycarbonate molded article, and after air-drying for several minutes, it is heated to a temperature of 70 to 110°C. Heat and dry to form a single layer of primer. Application of the primer paint is carried out using any known means such as brushing, dipping, spraying, roll coating, etc. Next, a paint containing a polyfunctional acrylic compound (top coat paint) is applied onto the single layer of primer and cured by irradiation with ultraviolet rays or electron beams. Top foot paint can be applied by brushing, dipping, or spraying.

This can be done using any known means such as p-ru coating.

The aromatic polycarbonate molded article to which the method of the present invention is applied is a polycarbonate resin obtained by polymerizing an aromatic dihydric phenol, typically bisphenol A, and a carbonate precursor, such as phosgene, by a known method. Refers to molded products obtained by molding into sheets or other shapes.

The thus obtained composite polycarbonate molded product has excellent surface properties such as excellent abrasion resistance and chemical resistance, high surface hardness, and good adhesion to the polycarbonate base of the protective film. It does not yellow even when used outdoors for long periods of time (it also has excellent weather resistance, with no cracks in the top coat layer and no reduction in the adhesion between the protective film and the polycarbonate base). There is.

Hereinafter, the method of the present invention will be explained in more detail using Reference Examples, Examples, and Comparative Examples.

In Reference Examples, Examples, and Comparative Examples, all formulations are in parts by weight unless otherwise specified.

The performance test method shown in the examples is as follows.

(1) Appearance Judgment was made visually.

Judgment criteria: ○...Good △...Crank occurs in the paint film ×...The paint film naturally peels off (2) Steel wool testite ○ (○○ steel The coated film surface was lightly (pressed down) 15 times with wool.The degree of scratches on the coated film surface was then determined based on the following criteria, and the abrasion resistance was evaluated.

A'... No scratches A... Almost no scratches B... Kamokatsu (but the luster is maintained C...
...There will be countless scratches and the gloss will be lost (3) Make 100 hard gobs (1 mm2) on the adhesive A film, stick Hirohentabe on it, and then peel it off sharply at right angles. At this time, the number of stitches remaining without being peeled off was expressed against the total number of stitches of 100, and the adhesiveness was evaluated.

(4) Weathering test Sunshine carbon arc type accelerated weathering tester (manufactured by Suga Test Instruments, Sunshine Weather Meter WB-8UN-
HC type) for a predetermined period of time, and various performances after the weathering test were evaluated.

Reference example 1 255 parts of methyl methacrylate and n-acrylic acid
A solution of 45 parts of butyl dissolved in 300 parts of ethylene glycol 7-ethyl ether was charged into a four-way flask equipped with a reflux device, a stirrer and a thermometer, and 1.5 parts of benzoyl peroxide was added thereto. Gradually raise the liquid temperature without stirring in a nitrogen atmosphere to 80-85
Stirring was continued for 5 hours at °C. The molecular weight of the acrylic copolymer obtained by this polymerization reaction was determined to be 120.000 from the top beak position determined by the gel permeation polymer.

The solution of the acrylic copolymer obtained in this manner is used as a primer paint.

Example 1 According to the method of Reference Example 1, molecular weights of 50,000, 100,000, 20
10,000 and 30,000 acrylic copolymers were each prepared in ethylene glycol monoethyl ether, and diluted and adjusted to a solution having a copolymer concentration of 15% by weight. Furthermore,
To improve smoothness, silicone leveling agent (
B Y K - Manufactured by Mallinckrodt, product name r B Y
K-500J) was added in an amount of 0.1% by weight based on the copolymer. The obtained acrylic copolymer solution is used as a primer paint.

Each of these primer paints was applied to the surface of a polycarbonate resin sheet using a bar coater, and the primer layer was adjusted to have a thickness of 20μ. After applying the primer paint, let it air dry for about 10 minutes, then dry it in a hot air circulation dryer for about 10 minutes.
It was dried at 0° C. for 30 minutes.

Primed polycarbonate resin sheet,
Commercially available ultraviolet curing paint (Mitsubishi Gas Chemical #, product name rBX)
9014J) with a bar coater to a film thickness of 5μ, and a high-pressure mercury lamp (Japan Battery Department, high-pressure water hammer,
The coating film was cured by irradiation at a line speed of 2 m/min K at 80 ψ)K.

The surface characteristics of the resulting composite polycarbonate resin molded product are as shown in Table 1.

Example 2 and Comparative Examples Methyl methacrylate (MMA) and butyl acrylate (
An acrylic copolymer was obtained according to the method of Reference Example 1 by changing the blending ratio of BA) from 10010 to 70/3 OK. All molecular weights were 120,000 to 150,000. The above copolymer solution was diluted with ethylene glycol 7-ethyl ether so that the concentration of the acrylic copolymer was 15% by weight, and an amount equivalent to 20% by weight based on the copolymer was added to this solution. 2
- (2'-Hydroxy-5'-tert-butylphenyl)benzotriazole (manufactured by Ciba Geigy Japan,
A silicone leveling agent (rBYK-300J listed above) in an amount equivalent to 0.1% by weight of the product name "Tinuvin P8J"
) was added, and this was used as a primer paint.

The above primer paint was applied to a polycarbonate resin sheet by a dipping method, heated and dried for 30 minutes to form a single layer of primer with a thickness of 10 to 15 μm on one side.

Next, a commercially available ultraviolet curable resin (trade name rA-TMPTJ, manufactured by Shin Nakamura Chemical Co., Ltd.) 97 was applied to the primer-treated sheet.
A paint consisting of 1 part tobe/3 parts to diyne ethyl ether was applied to a thickness of 10 μm using a barter, and the coating film was cured using the high-pressure mercury lamp used in Example 1 at a line speed of 1 m/min. Table 2 shows the surface properties of the composite polycarbonate molded product obtained.

Table 2 shows various performances before and after the weathering test, and it can be seen that the adhesion after the weathering test deteriorates prematurely when no primer treatment is performed or when an MMA homopolymer is used as the primer layer.

Example 3 and Comparative Examples Methyl methacrylate 410 parts, butyl acrylate
90 parts, ethylene glyfur monoethyl ether 50
0 parts and 1.5 parts of 7zobisisoduthyronitrile,
The mixture was charged into a four-way flask equipped with a 61-volume refluxer, a stirrer, and a thermometer, heated to 80 to 85°C under a nitrogen atmosphere, and stirred. After 3 hours, 1.0 part of 7zobisisobutyE-=)lyl was added, and the mixture was further stirred under heating for 2 hours to obtain an acrylic copolymer having a molecular weight of 150,000.

A mixed solvent of ethylene clyfluor monomethyl ether/ ivy xylene/isopropyl alcohol (mixed volume ratio 1.2/138/1.5) was added to the obtained acrylic copolymer solution.
) and dilute it so that the acrylic copolymer concentration is 15 molecules! Pi was adjusted. Furthermore, 0.1% by weight of a silicone leveling agent (rBYK-300J mentioned above) was added to the copolymer.

Next, this acrylic copolymer solution was divided into appropriate amounts, and the above-mentioned ultraviolet absorber "Tinuvin P8J 47" was added to each in an amount of 2, 5, 10, 115, 20, or 60% by weight based on the acrylic copolymer. did.

The obtained various primer paints were applied to a polycarbonate sheet using a bar coater, and the primer film thickness was 10.
Adjust it so that it is μ, heat it at 100℃ for 30 minutes,
Dry.

Commercially available ultraviolet curing paint (
"rNUV-165" manufactured by Nitto Kasei Co., Ltd.) was applied to a thickness of 10 μm using a bar coater, and the coating film was cured using a high-pressure mercury lamp (manufactured by Oak Seisaku Shin, 80 W/cm). The surface performance of the composite polycarbonate molded product obtained is shown below.
O shown in 6

Claims (1)

[Claims] t. A primer layer made of a thermoplastic acrylic polymer blended with an ultraviolet absorber is formed on the surface of an aromatic polycarbonate molded article, and then. In producing a composite polycarbonate molded article with excellent surface properties by forming a synthetic resin protective film obtained from a polyfunctional acrylic compound that is cured by energy rays on the primer layer, the primer layer is A thermoplastic acrylic copolymer having a high molecular weight of 50,000 or more obtained by copolymerizing an alkyl methacrylate and an alkyl acrylate is used as the thermoplastic acrylic polymer to be formed. Method 2
Method 3 according to claim 1, in which a single primer layer is formed by blending an ultraviolet absorber in an amount corresponding to 10 to 20% by weight with respect to the acrylic copolymer, the ultraviolet absorber is 2-(2 '-Hydroxy-5't
crt-)f ruphenyl) benzotriazole, the method 4 according to claim 2, and the method according to claim 1, wherein the acrylic copolymer is a copolymer of methyl methacrylate and dithyl 7-acrylate. Method