JPH041014B2 - - Google Patents

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 primer layer 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 this primer layer. The present invention relates to a method for producing a composite aromatic polycarbonate molded article formed with a synthetic resin protective film obtained 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, it is strongly desired 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 (JP-A-47-33164, JP-A-48-80175,
51-111276 and others) and a method of coating a hydrolyzed product of an organosilane compound and thermally curing it to form a protective film made of organopolysiloxane (U.S. Pat. No. 3,707,397, JP-A-52
-138565, and many others) have been proposed. However, these methods of forming a protective film by heating and curing require the molded product to be cured under harsh conditions of high temperature and long time, and this treatment can damage the aromatic polycarbonate molded product. There is a greater risk of damaging its originally excellent mechanical properties. Furthermore, problems arise 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 hardened resin, forming a synthetic resin protective film. Methods have also been proposed to
Publication No. 7771, Special Publication No. 55-500855, Special Publication Sho
49-14859, Tokko Sho 52-47763, 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, especially its weather resistance, is not sufficient. Rather, for example, it turns yellow after 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 in known techniques, and completed the present invention. That is, the present invention forms a primer layer made of a thermoplastic acrylic polymer containing an ultraviolet absorber on the surface of an aromatic polycarbonate molded article,
Next, a synthetic resin protective film obtained from a multi-tubular acrylic compound that is cured by energy rays is formed on the primer layer to produce a composite polycarbonate molded article with excellent surface properties. The primer layer is a high molecular weight thermoplastic acrylic with a molecular weight of 50,000 or more obtained by polymerizing 70 to 90% by weight of alkyl methacrylate and 30 to 10% by weight of alkyl acrylate using a solvent that does not corrode the polycarbonate molded product. This is a method for producing a composite polycarbonate molded article with excellent surface properties, which is characterized in that it is formed using a polymerization solution of a copolymer. The thermoplastic acrylic copolymer used as the primer layer in the method of the present invention is a copolymer of methacrylic acid alkyl ester and acrylic acid alkyl ester, and the copolymer composition is 70 to 70% It means a copolymer consisting of 90% by weight of acrylic acid alkyl ester and 30 to 10% 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 the primer layer using this copolymer and the adhesion of the top coat layer during long-term use. As the amount of acrylic acid alkyl ester increases, the abrasion resistance decreases, and on the other hand, when the amount of acrylic acid alkyl ester decreases, adhesion decreases. In addition, the thermoplastic acrylic copolymer must have a specific molecular weight. That is, 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. It has been observed that when the molecular weight is lower than 50,000, the abrasion resistance of the top coat layer becomes significantly lower, especially when using acrylic polymers with a molecular weight of around 30,000, which are easily available on the market. On the other hand, if the molecular weight of the thermoplastic acrylic copolymer becomes significantly large, the viscosity of the primer coating solution will become extremely high, the workability of primer coating will deteriorate, and it will be difficult to obtain a smooth coating film. The molecular weight of the thermoplastic acrylic copolymer is preferably 300,000 or less. The methacrylic acid alkyl esters used here include methacrylic acid methyl ester, methacrylic acid ethyl ester,
It is a lower alkyl ester of methacrylic acid exemplified by butyl methacrylate 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. It is. 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
It dissolves only in highly soluble solvents such as methyl ethyl ketone, acetate, and toluene, and these solvents are good solvents for polycarbonate. Therefore, the acrylic copolymer of the present invention can be used in these good solvents. When dissolved, the solution corrodes polycarbonate moldings, making it unsuitable for use as a primer coating. The present inventors conducted various studies in order to eliminate such disadvantages, and copolymerized methacrylic acid alkyl ester and acrylic acid alkyl ester in a poor solvent for polycarbonate, such as ethylene glycol monoethyl ether. It has been found that by obtaining a solution of a high molecular weight acrylic copolymer in ethylene glycol monoethyl ether and using this solution as a primer coating, it is possible to suitably form a desired primer layer on a polycarbonate molded article. . If desired, other solvents can be added to the acrylic copolymer solution obtained by this method to adjust the viscosity of the primer coating, as long as they do not corrode the polycarbonate molded article. The method of using the acrylic copolymer solution obtained in this way as a primer coating is an extremely preferred embodiment of the method of the present invention. The copolymer concentration in the primer paint containing the above acrylic copolymer should be in the range of 5 to 30% by weight in relation to various factors such as workability, primer layer thickness, and crack occurrence in the top coat layer. is desirable. In other words, it has been observed that 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. . Therefore, the thickness of the primer layer is 5 to 25μ.
It is desirable that the concentration of the primer coating solution be within the above range, and the concentration of the primer coating solution may be appropriately selected from the above range in order to form the film thickness. As described above, a primer layer made of a thermoplastic acrylic copolymer with a predetermined high molecular weight is formed on the surface of a polycarbonate molded article by the method of the present invention, and then a hardened acrylic resin protection layer is applied on the primer layer. Although a composite polycarbonate molded article having the desired surface properties is obtained by forming a film, another important objective of the present invention is to provide a composite polycarbonate molded article with the ability to withstand long-term outdoor use, i.e., with excellent weather resistance. Our objective is to provide polycarbonate molded products. To achieve this purpose, the surface of the polycarbonate substrate must be exposed to 80% of ultraviolet light with a wavelength of 300 to 380 mμ.
80% by weight in essential ingredients to prevent more than % from reaching
You can make a trowel that contains up to When adding these reinforcing agents or fillers, known silane coupling agents can be used. Furthermore, lubricants such as fluororesins and molybdenum compounds can also be used. In addition, the composition of the present invention may contain small amounts of a mold release agent, a coloring agent, a heat stabilizer, an ultraviolet stabilizer, a weather stabilizer, a blowing agent, a flame retardant, and a flame retardant aid without departing from the purpose of the present invention. , a rust preventive agent can be contained. Furthermore, the following polymers can be mixed and used in the same manner. These polymers include monomers such as ethylene, propylene, butylene, pentene, butadiene, isoprene, chloroprene, styrene, α-methylstyrene, vinyl acetate, vinyl chloride, acrylic ester, methacrylic ester, and (meth)acrylonitrile. homopolymers or copolymers, polyurethanes, polyamides, polyesters, polycarbonates, polyacetals, polysulfones, polyarylsulfones, polyethersulfones, polyarylates, polyphenylene oxides, polyphenylene ethers, polyether ether ketones Examples include homopolymers, copolymers, block and graft copolymers of polyimide, polyamideimide, silicone resin, phenoxy resin, fluororesin, polyaryl ether and the like. The composition of the present invention has a stable melt viscosity and can be easily adjusted. Moreover, although unexpected, there is no generation of pores, which is seen in conventional oxidation-crosslinked products. Furthermore, it has superior strength and bleedability compared to mixtures of epoxy resins other than novolak type epoxy resins. Therefore, it can be used in a wide variety of applications. That is, the composition obtained according to the present invention can be used not only for injection molding and compression molding, but also for extrusion molding, blow molding, and foam molding, and can be processed into films, sheets, monofilaments, and fibers. Also, after molding, 200
Heat resistance can be further improved by heating at ~300°C under vacuum or in the presence of oxygen gas. Next, the present invention will be explained in detail with reference to Examples.
Note that % and parts in the examples are based on weight. [Reference Example 1] 98.4 g of sodium sulfide (60% purity) and 4.7 g of sodium hydroxide were added to 3080 g of N-methylpyrrolidone, heated to 205°C while dehydrating, and then 1113g of paradichlorobenzene and N-methylpyrrolidone were added.
510 g was added and heated under pressure at 260° C. for 5 hours, cooled, washed with water and dried. The obtained PPS has a melt viscosity of
It was 37 poise, and the non-Newtonian coefficient was 0.95. This is called Polymer A. The melt viscosity of Polymer A cross-linked in air at a temperature of 270°C for 3 hours, 4 hours, 5 hours, and 6 hours, respectively, is the product name "NUV-2836" and "NUV-2836" provided by Nitto Kasei Co., Ltd. Examples include "NUV-165" or "NUV-1010" and Mitsubishi Gas Chemical Co., Ltd.'s product numbers "EX 9014" and "EX 9015." 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. A primer layer is formed by heating and drying. Application of the primer paint is carried out using any known means such as brushing, dipping, spraying, roll coating, and the like. Next, a paint containing a polyfunctional acrylic compound (top coat paint) is applied onto the primer layer and cured by irradiation with ultraviolet rays or electron beams. The top coat paint is applied by any of the known methods such as brushing, dipping, spraying, roll coating, etc. The aromatic polycarbonate molded article to which the method of the present invention is applied is obtained by polymerizing an aromatic dihydric phenol, typically bisphenol A, and a carbonate precursor, such as phosgene, by a known method. A molded product obtained by molding polycarbonate resin into a sheet or other shape. 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 also has excellent weather resistance, with no yellowing even after long-term outdoor use, no cracks in the top coat layer, and no loss of adhesion between the protective film and the polycarbonate base. There is. Hereinafter, based on reference examples, working examples, and comparative examples,
The method of the present invention will be explained in more detail. 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: 〇...Good △...Cracks occur in the paint film ×...The paint film peels off naturally (2) Steel wool test Repeat 15 times while lightly pressing the paint surface with #〇〇〇〇 steel wool. The degree of scratches on the surface of the coating film after that was determined according to the following criteria, and the abrasion resistance was evaluated. A'... No scratches A... Hardly any scratches B... Scratches but maintains gloss C... Numerous scratches and loss of gloss (3) Adhesion Paint film Make 100 goblets (1 mm ² ) on the surface, stick cellophane tape on it, and then peel it off sharply at right angles. At this time, the total number of stitches remaining without peeling is 100.
The adhesion was evaluated. (4) Weathering test Sunshine carbon arc type accelerated weathering tester (manufactured by Suga Test Instruments, Sunshine Weather Meter)
WE-SUN-HC type) was used to process the sample for a predetermined period of time, and various performances after the weathering test were evaluated. Reference Example 1 A solution of 255 parts of methyl methacrylate and 45 parts of n-butyl acrylate dissolved in 300 parts of ethylene glycol monoethyl ether was charged into a four-necked flask equipped with a reflux device, a stirrer, and a thermometer. benzoyl peroxide 1.5 to
Added a section. The liquid temperature was gradually raised while stirring under a nitrogen atmosphere, and stirring was continued at 80 to 85°C for 5 hours. The molecular weight of the acrylic copolymer obtained through this polymerization reaction was determined to be 120,000 from the position of the top peak determined by gel permeation chromatography. The acrylic copolymer solution thus obtained is used as a primer paint. Example 1 According to the method of Reference Example 1, the molecular weight was 50,000 and 10
Acrylic copolymers of 10,000, 200,000, and 300,000 were prepared in ethylene glycol monoethyl ether, and diluted and adjusted to a solution having a copolymer concentration of 15% by weight. Furthermore, in order to improve the smoothness, a silicone leveling agent (manufactured by BYK-Marinckrodt, trade name "BYK-300") 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, it was air-dried for about 10 minutes, and then dried in a hot air circulation dryer at 100°C for 30 minutes. A commercially available ultraviolet curing paint (manufactured by Mitsubishi Gas Chemical, trade name "EX 9014") was applied to a primer-treated polycarbonate resin sheet using a bar coater to a film thickness of 5 μm, and a high-pressure mercury lamp (manufactured by Nippon Battery, high-pressure The coating film was cured by irradiation with a mercury lamp (80 w/cm) at a line speed of 2 m/min. The surface characteristics of the resulting composite polycarbonate resin molded product are as shown in Table 1.

[Table] Example 2 and Comparative Example Acrylic copolymer was produced according to the method of Reference Example 1, changing the blending ratio of methyl methacrylate (MMA) and butyl acrylate (BA) from 100/0 to 70/30. I got it. The molecular weights were all 120,000 to 150,000.
The above copolymer solution was diluted with ethylene glycol monoethyl ether so that the concentration of the acrylic copolymer was 15% by weight, and an amount of 20% by weight of the copolymer was added to this solution. -(2'-Hydroxy-5'-tert-butylphenyl)benzotriazole (manufactured by Ciba Geigy Japan, trade name "Tinuvin PS") and an amount equivalent to 0.1% by weight of a silicone leveling agent ("BYK-300" mentioned above) This was used as a primer paint. Apply the above primer paint to a polycarbonate resin sheet by dipping method, heat it at 100℃ for 30 minutes,
It was dried to form a primer layer with a thickness of 10 to 15 μm on one side. Next, a commercially available ultraviolet curable resin (trade name "A-TMPT",
A paint consisting of 97 parts (Shin Nakamura Chemical Co., Ltd.) and 3 parts benzoin ethyl ether was applied to a thickness of 10μ using a bar coater, and then applied using the high-pressure mercury lamp used in Example 1.
The coating was cured 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 is significantly reduced when no primer treatment is performed and when the MMA homopolymer is used as the primer layer.

[Table] Example 3 and Comparative Example 410 parts of methyl methacrylate, butyl acrylate
90 parts, ethylene glycol monoethyl ether
500 parts of azobisisobutyronitrile and 1.5 parts of azobisisobutyronitrile were placed in a four-necked flask equipped with a 3-capacity reflux, a stirrer, and a thermometer, and heated under a nitrogen atmosphere for 80 to 80 minutes.
It was heated to 85°C and stirred. 1.0 after 3 hours
of azobisisobutyronitrile was added, and the mixture was further stirred under heating for 2 hours to obtain an acrylic copolymer with a molecular weight of 150,000. A mixed solvent of ethylene glycol monomethyl ether/meta-xylene/isopropyl alcohol (mixed volume ratio is
1.2/0.8/1.5) and diluted to adjust the acrylic copolymer concentration to 15% by weight. In addition, silicone leveling agent ("BYK-
300'') was added in an amount of 0.1% by weight based on the copolymer. Next, divide this acrylic copolymer solution into appropriate amounts, and apply the ultraviolet absorber "Tinuvin" to each portion.
PS” to acrylic copolymer at 2, 5, 10,
It was added in an amount of 15, 20 or 30% by weight. The various primer paints obtained were applied to a polycarbonate sheet using a bar coater, and the primer film thickness was adjusted to 10 μm.
℃, heated and dried for 30 minutes. Commercially available ultraviolet curing paint (manufactured by Nitto Kasei Co., Ltd., "NUV-165") on the primer-treated sheet
was applied to a thickness of 10μ using a bar coater, and the coating was cured using a high-pressure mercury lamp (manufactured by Oak Seisakusho, 80w/cm). Table 3 shows the surface properties of the composite polycarbonate molded product obtained.

【table】

Claims (1)

[Claims] 1. 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 cured with energy rays on the primer layer. In producing a composite polycarbonate molded product with excellent surface properties by forming a synthetic resin protective film obtained from a polyfunctional acrylic compound, the primer layer is formed of a methacrylic acid alkyl ester of 70 to 70%.
Using a polymer solution of a thermoplastic acrylic copolymer with a molecular weight of 50,000 or more, which is obtained by polymerizing 90% by weight and 30 to 10% by weight of an acrylic acid alkyl ester using a solvent that does not corrode the polycarbonate molded product. Method 2 for producing a composite polycarbonate molded article with excellent surface properties characterized by forming a primer layer by blending an amount of an ultraviolet absorber equivalent to 10 to 20% by weight with respect to the acrylic copolymer. Manufacturing method 3 according to claim 1 in which the ultraviolet absorber is formed by 2-(2'-hydroxy-5'-
The manufacturing method according to claim 2, in which the acrylic copolymer is tert-butylphenyl)benzotriazole; The manufacturing method according to claim 1, in which the acrylic copolymer is a copolymer of methyl methacrylate and butyl acrylate. .