JPS6151547B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention is directed to an improved polymer mainly composed of methyl methacrylate (hereinafter referred to as acrylic resin).
Regarding the sheet. Acrylic resin has excellent transparency, weather resistance, and surface hardness, and is widely used as a variety of molding materials and sheets due to its beautiful appearance. In particular, as a sheet, it is widely used for outdoor signboards, lighting, safety glass, and other applications, taking advantage of its characteristics such as transparency, weather resistance, and surface hardness. However, although the impact strength of acrylic resin is far superior to that of glass, it is still not sufficient, and improvements have been desired. In general, as a method for improving the impact strength of acrylic resins, many methods have been proposed in which a fine particle elastomer phase is dispersed in the resin to absorb the impact (for example, Japanese Patent Publication No. 3941/1983, Japanese Patent Application Laid-Open No. 1983-1989).
Publication No. 55233, etc.). It is true that this method improves impact strength, but it has drawbacks such as the complicated manufacturing method, high cost, and considerable loss of colorless transparency, which is a feature of acrylic resin. There is. In response to this, a method has been used to increase the strength by laminating FRP on an acrylic resin sheet. Although this method improves impact strength, (i) since it is carried out in the atmosphere, monomer vapor and glass powder are generated, which poses major safety and hygiene problems; (ii) it is almost impossible to use manually The disadvantages include: (iii) the resulting laminate is opaque; and (iv) the resulting laminate is difficult to thermoform afterwards. . The present inventors have studied a method for easily improving the impact strength of acrylic resin without impairing its characteristics at all, and have completed the present invention. The present invention relates to an acrylic resin sheet whose impact strength is improved by laminating it with a polycarbonate film. That is, the present invention provides methyl methacrylate monomer
A sheet made of a methyl methacrylate polymer or copolymer obtained by polymerizing 100 to 50 parts by weight and 0 to 50 parts by weight of an unsaturated monomer copolymerizable with the methyl methacrylate monomer, and a sheet having a thickness of 10 ~200μ, an impact strength of 30Kg-cm or more, and a folding strength of 2000 times or more, the thickness of the polycarbonate film is 1/100 to 1/30 of the thickness of the sheet. be,
To provide a laminate with excellent impact resistance, workability, and heat deformation resistance. In addition, in this specification, "sheet" refers to the thickness
"Film" refers to anything larger than 0.5mm (500μ)
refers to a material with a thickness of 0.3mm (300μ) or less. The unsaturated monomer copolymerizable with methyl methacrylate used here includes, for example,
Alkyl acrylates having ~8 alkyl groups (e.g., methyl acrylate, ethyl acrylate, propyl acrylate, n-butyl acrylate, iso-butyl acrylate, cyclohexyl acrylate, 2-ethylhexyl acrylate, etc.),
Examples include alkyl methacrylates having an alkyl group having 2 to 8 carbon atoms (eg, ethyl methacrylate, n-butyl methacrylate, 2-ethylhexyl methacrylate, etc.), styrene, and α-methylstyrene. If the proportion of these unsaturated monomers in the copolymer is too large, the effect of improving the impact strength of the laminate becomes insufficient or the weather resistance is impaired, which is not preferable. Polycarbonate resin is a well-known resin, and its sheets have high impact strength and are used for safety glass, bulletproof glass, etc. However, compared to acrylic resin, polycarbonate resin
It has poor weather resistance, transparency, surface hardness, and workability, and sometimes has poor weather resistance, so it is not necessarily satisfactory for outdoor use. The first feature of the laminate of the present invention is an improvement in the impact strength of the sheet, particularly against impact from flying objects such as stones, typified by falling weights, on the sheet surface. What should be emphasized in particular is that when an acrylic resin sheet and a polycarbonate film are laminated, the strength against impact from the sheet side is significantly improved, and conversely, the strength against impact from the film side is significantly improved. I can't hope. In other words, the strength is improved only when backed with polycarbonate film. This has great practical significance. In other words, it is the acrylic resin sheet surface that is exposed during use, and it completely retains the beauty and surface hardness characteristic of acrylic resin sheets in terms of appearance.
The surface that is constantly exposed to outside air and natural light is an acrylic resin surface with excellent weather resistance. Polycarbonate film, which has poor weather resistance compared to acrylic resin, is protected by the acrylic resin, which means that it can maintain its strength indefinitely. In particular, when the acrylic resin contains a UV absorber, the protective effect is great. The second feature is that the sheet can be easily heated and formed. In the case of a laminate made of a polycarbonate sheet and an acrylic resin sheet, heat molding is difficult because there is a large difference in heat deformation temperature between the two. However, the laminate of the present invention in which a polycarbonate film and an acrylic resin are laminated can be easily heat-formed under the usual molding conditions for acrylic resin sheets, and does not require any special equipment or devices. The third feature is that the heat distortion temperature is improved. Further other features will become clear from the following description. For laminating the acrylic resin sheet and polycarbonate film of the present invention, commonly used means can be applied. For particularly simple lamination, it is also possible to use suitable adhesives. However, in order to take full advantage of the features of the present invention, it is desirable to laminate without using an adhesive. When using adhesives, cracks may occur due to the organic solvents contained in the adhesive, and peeling due to deterioration of the adhesive due to long-term use outdoors, foaming during heat molding, discoloration, etc. Problems such as peeling may occur. The most desirable lamination method is to directly heat and press the acrylic resin sheet and polycarbonate film. As a result of detailed study of the thickness of the sheet and film, heating temperature conditions, etc., the inventors of the present invention found that an acrylic resin sheet and a polycarbonate film can be firmly bonded together without any loss of transparency. As a method for heat-pressing, a polycarbonate film can be pressure-bonded under predetermined conditions when an acrylic resin sheet is thermoformed using a normal press. Furthermore, when extruding the sheet, the high temperature (for example, about 140 to 270° C.) sheet exiting the extruder and the film can be pressed together by passing them through the same roll.
Also, if it is possible to use an adhesive depending on the purpose, it can be bonded in the same way as masking the surface protection paper of the sheet. In the case of an extruded plate, for example, an embossed plate, the effect of the present invention is significant. When an embossed plate, that is, a sheet has a concavo-convex pattern on one side, the concave portion is thin and tends to be weak in strength, but the present invention can sufficiently increase the strength. In addition, by pressing the polycarbonate film at the same time when corrugating a flat plate by pressing, it is possible to laminate the sheets without using any special equipment. It is also extremely effective in improving the strength of irregularly shaped extruded plates such as ribbed two-layer plates with high heat retention effects. The thickness of polycarbonate film is 10~200μ
It is necessary that If the film is less than 10μ thick, there is little hope of improving the strength, and if the film is 200μ or less
In the above case, sufficient adhesive strength cannot be obtained by thermocompression bonding, and the thermoformability of the laminate deteriorates. In order to fully exhibit the effects of the present invention, the thickness of the polycarbonate film must be in the range of 1/100 to 1/30 of the thickness of the acrylic resin sheet. From conventional knowledge, it was completely unknown that the physical properties could be improved to such a large extent simply by laminating such extremely thin films. If the thickness of the polycarbonate film is thinner than this, the effect of the present invention will hardly be obtained, and if it is thicker than this, a large amount of expensive polycarbonate will be used, which is not only economically disadvantageous, but also Heat moldability becomes significantly inferior. The polycarbonate film itself used in the present invention must have an impact strength of 30 kg-cm or more as measured by a method according to JISK-6745. If the strength is less than this, hardly any effect of improving the impact strength of the laminate can be expected. Polycarbonate film must have a bending strength of 2000 times or more according to JISP-8115.
If the bending strength is less than this, the strength of the laminate will be weak, and the processability and workability during heat compression bonding will be poor. The present invention will be explained in more detail with reference to Examples below. The drop weight test shown in the examples is JIS-K-6718.
It was carried out according to the method of (4.9). Example 1 An extruded acrylic resin sheet with a thickness of 3 mm (trade name Delaglass A, manufactured by Asahi Kasei Corporation) was made into a 15 cm x 15
Cut into cm-sized pieces and cover with 75μ thick polycarbonate film (trade name: Carbonex, USA).
(manufactured by Cloudsley) was thermocompression bonded under the conditions shown in Table 1. The results are shown in Table 1.

[Table] Next, a falling weight test was conducted on the laminate obtained under the conditions of 3. The results are shown in Tables 2 and 3.

【table】

【table】

[Table] In the table, S/F and F/S indicate the case where the weight fell from the acrylic resin sheet surface (S) and the polycarbonate film surface (F), respectively. Further, F/S/F refers to a three-layer laminate consisting of film/sheet/film. The blank is one in which only the acrylic resin sheet is heated and pressurized without laminating the polycarbonate film. The numbers in the table indicate the corresponding number out of 10 samples. Comparative Example 1 A polyethylene film with a thickness of 75μ was coated with an ethylene-vinyl acetate adhesive at room temperature in Example 1.
It was laminated onto the same acrylic resin sheet used in Example 1, and a drop weight test was conducted in the same manner as in Example 1, but in all cases, almost no improvement in strength was observed. Example 2 Consisting of 95 parts by weight of methyl methacrylate, 5 parts by weight of methyl acrylate, and 300 ppm of ultraviolet absorber.
During the process of passing copolymer pellets with an average molecular weight of approximately 100,000 from an extruder through a die and a finishing roll to form an extruded plate with a thickness of 3 mm, the molten resin (approximately 250°C) from the die enters the finishing roll. At the same time, the thickness
A 50 μm polycarbonate film was supplied to the roll and bonded to the sheet under heat and pressure. The obtained laminate exhibited an appearance similar to that of general acrylic resin. In order to examine the accelerated weather resistance of this sheet, it was exposed to a Toyo Rika Sunshine Weather-Ometer for 1000 hours. As a result, the sample that was irradiated with light from the polycarbonate film side was colored yellow, but the sample that was irradiated with light from the acrylic resin sheet side showed the same appearance as before. The falling weight strength of these samples was measured in the same manner as in Example 1. The results are shown in Table 4. In addition,
All weights were dropped from the seat side (S/F).

【table】

[Table] Comparative Example 2 When manufacturing an extruded plate under the same conditions as Example 2,
After the acrylic resin sheet had cooled, instead of masking, a 50μ thick polycarbonate film coated with a vinyl acetate adhesive was pressed with a roll. This was subjected to the same sunshine weatherometer as in Example 2, and when examined after 200 hours, the film was found to have peeled off. Example 3 Polycarbonate films of different thicknesses (trade name Panlite Film, manufactured by Teijin Corporation) were placed on an extruded acrylic resin sheet (trade name Delaglass A, manufactured by Asahi Kasei Corporation) with a thickness of 5 mm. Example 1, Table 1 Lamination was carried out under the following conditions. This is 120mm long and wide.
It was cut into a 15 mm strip and used as a sample. With the film side of the sample facing up, place the center part of the sample on a support rod with a width of 8 mm, and leave it in an air bath set at a specified temperature for 1 hour. It was measured. The results are shown in Table 5.

[Table] Example 4 A mixture consisting of 60 parts by weight of methyl methacrylate, 40 parts by weight of styrene, 0.2 parts by weight of octyl mercaptan and 0.3 parts by weight of lauroyl peroxide was mixed at 80°C with sodium polyacrylate as a suspension stabilizer. Then, suspension polymerization was carried out at 95° C. for 1 hour to obtain polymer beads. The obtained beads were press-molded at 210°C to obtain a sheet with a thickness of 3 mm. On this sheet, Example 1,
Polycarbonate films with a thickness of 90 μm (trade name: Panlite Film, manufactured by Teijin Ltd.) were laminated under the conditions of 3 in Table 1, and a drop weight test was conducted. The results are shown in Table 6.

[Table] Example 5 Acrylic resin cast sheet with a thickness of 2 mm (methyl methacrylate monopolymer. Trade name Delaglas K,
45μ thick polycarbonate film (product name: Panlite Film, manufactured by Asahi Kasei Industries, Ltd.).
(manufactured by Teijin Ltd.) were stacked under the conditions of Example 1 and Table 1, 3, and a drop weight test was conducted. The results are shown in Table 7.

【table】

Claims (1)

[Scope of Claims] 1. A methyl methacrylate polymer obtained by polymerizing 100 to 50 parts by weight of a methyl methacrylate monomer and 0 to 50 parts by weight of an unsaturated monomer copolymerizable with the methyl methacrylate monomer. It is made by laminating a sheet made of a combination or copolymer and a polycarbonate film having a thickness of 10 to 200μ, an impact strength of 30 kg-cm or more, and a folding strength of 2000 times or more, and the thickness of the polycarbonate film is the same as that of the sheet. A laminate with excellent impact resistance, workability, and heat deformation resistance, which is 1/100 to 1/30 of the thickness of . 2 The unsaturated monomer copolymerizable with the methyl methacrylate monomer is an alkyl acrylate having an alkyl group having 1 to 8 carbon atoms, an alkyl methacrylate having an alkyl group having 2 to 8 carbon atoms, styrene, and α - The laminate according to claim 1, which is at least one selected from methylstyrene. 3 The transmittance of ultraviolet rays (wavelength 3700 Å or less) of the sheet is
20% or less of the laminate according to claim 1. 4. The laminate according to claim 1, wherein the sheet is an extruded plate. 5. The laminate according to claim 1, wherein the sheet is an embossed plate. 6. The laminate according to claim 1, wherein the sheet is a corrugated sheet. 7. The laminate according to claim 1, wherein the sheet is a profile extruded board. 8. The laminate according to claim 1, wherein the sheet is a foam.