JPS61143445A - Surface-hardened plastics - Google Patents

Abstract

PURPOSE:To obtain the titled plastics with markedly improved weather-ability, by providing, on the surface of a plastic base at least the surface layer of which is impregnated with ultraviolet light absorber, primer layer followed by hard-coat layer. CONSTITUTION:A plastic base (of any shape formed from polycarbonate resin, acrylic resin, ABS resin, etc.) is immersed in a solution prepared by dissolving an ultraviolet light absorber (e.g., of benzophenone-, triazole-, benzoate-base) in, e.g., isopropyl alcohol. The resultant plastic base is coated with a primer (e.g., of silicone-, acrylic-base), e.g., by spraying process to provide primer layer through air-drying, followed by coating spreading process to provided hard-coat layer through air-drying, thus obtaining the objective plastics.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a surface-hardened plastic that is a plastic that has been subjected to a hard coat treatment, that is, a surface hardening treatment.

(Prior Art) Surface-hardened plastics have been used in a wide range of applications such as automobile parts materials, building materials, and covers for television cathode ray tubes because of their high hardness and durability. As shown in FIG. 7, for example, such surface hardening plastics are made by laminating a primer layer 2 and then a hard coat layer 8 on a polycarbonate substrate 1, which is a plastic plate, and usually the hard coat layer (cured layer) is coated with ultraviolet rays. Contains absorbent.

(Problems to be Solved by the Invention) In such conventional surface-hardened plastics, even if the hard coat layer contains an ultraviolet absorber, the surface of the polycarbonate still deteriorates due to ultraviolet rays, and the hard coat agent and The adhesive strength of the Sunshine Weatherometer G, OO is weakened, for example, in an accelerated test.

There was a problem that it would peel off over time.

(Means for Solving the Problems) This invention applies the ultraviolet absorber to at least the surface layer of the plastic substrate by immersing the plastic used as the substrate in an ultraviolet absorber liquid or applying the ultraviolet absorber liquid to the surface of the plastic substrate. The above-mentioned problem is solved by sufficiently containing it.

Therefore, the surface-hardened plastic of the present invention is characterized in that a primer layer is laminated, followed by a hard coat layer, on the surface of a plastic substrate whose surface layer is impregnated with an ultraviolet absorber.

The plastic substrate used in this invention may be of any shape molded from any conventionally used resin such as polycarbonate resin, acrylic resin, MuBS resin, polyester, napun, polystyrene, polysal 7on, etc. can be used.

As the primer to be coated on this substrate, all primers such as silicone-based, acrylic-based, urethane-based, etc. can be used to form a single layer of primer.

Next, as the hard coat agent used to form the hard coat layer, all silicone-based, acrylic-based, melamine-based, and urethane-based hard coat agents can be used.

Furthermore, as the ultraviolet absorber, benzphenone type, triazole type, benzoate type, acrylate type, anilide type, etc. can be applied.

(Example) The present invention will be explained below by way of examples with reference to the drawings.

Example 1 Uvinal 4.00 (manufactured by Bayer AG, trade name) was used as an ultraviolet absorber and dissolved in isopropyl alcohol to prepare an 80% by weight isopropyl alcohol solution. A pre-cleaned polycarbonate plate was then immersed in this solution for 24 hours at 25°C. A primer layer and a hard coat layer were formed on the dipping-treated polycarbonate plate at 25° C. and a relative humidity (RH) of 45 degrees or less as follows. That is, as shown in FIG. Then, apply Toshiba Silicone Co., Ltd. PH91 solid content thermoplastic acrylic remer, solvent ethyl cellosolve, cellosolve acetate) to a film thickness of 1.26μ (possible in the range of 1.0 to 2.0μ) for 25 minutes. This was left to air dry to form a primer layer 2. This primer layer can also be formed by a dipping method or a flow coating method instead of the spray method.

Next, Toshiba Silicone Co., Ltd.'s Tosgard 510 (solid content colloidal silica, methyl silsesxyloxane, solvent ethanol, isobutanol, cellosolve acetate) was applied to the primer layer 2 to a thickness of 9 μm using a flow coating method, and left for 20 minutes. A hard coat layer 8 was provided by air drying.

This hard foot layer may be formed by a dipping method or a spraying method in addition to the flow coating method, and may be applied to a film thickness in the range of 6 to 10 μm.

The substrate provided with the primer layer and the hard coat layer was baked at 120° C. for 60 minutes to obtain a surface hardened polycarbonate plate as shown in FIG. In addition, 4 in FIG. 1 indicates the Uvinal 400.

Next, for comparison, a surface-hardened polycarbonate plate was prepared in the same manner except that the polycarbonate plate was not impregnated with an ultraviolet absorber.

The performance of these two types of polycarbonate plates was evaluated and the results are shown in Table 1 below.

Table 1 *a) Black panel temperature: 68°C Next, Uvinal 40o (benzophenone, 1) and Biosolp 80 (manufactured by Kyodo Yakuhin Co., Ltd., trade name, benzoate type) were each used as 0.5% by weight solutions as ultraviolet absorbers. A surface-treated polycarbonate plate was produced in the same manner. For each surface-treated polycarbonate board, the relationship between the immersion time of the polycarbonate board in the above solution and the time at which weather resistance was improved was evaluated. The results obtained are shown in Figure 2. In addition, the concentrations of Upinal 400 and Biosolve 8o were varied within the range of 0 to 5.0% by weight, and polycarbonate plates were immersed in each solution for 7 days, and the time taken for improved weather resistance at each concentration was evaluated. Shown below. Regarding the time period during which the weather resistance was improved, the performance of the hard coating agent base was 2,000 hours (in both cases, peeling occurred in the base grain peeling test at this time).

From Figure 2, the immersion time in the ultraviolet absorber solution is 1 day (24
Time) The above shows something remarkable. Moreover, from FIG. 8, it can be seen that the effect is small when the concentration of the ultraviolet Si absorbent solution is less than 0.5 weight JIS.

Next, we used an acrylic board instead of a polycarbonate board,
A case where PH98 manufactured by Toshiba Silicone Co., Ltd. (solid content thermoplastic acrylic polymer, solvent ethyl cellosolve, diacetone alcohol) was used as a Biosolp 8o1 primer as an ultraviolet absorber, and Tosguard 510 as a hard foot agent, and the polycarbonate plate was used as a substrate. A similar test was conducted and the results obtained are shown in FIGS. 4 and 5. Figure 4 shows the relationship between the immersion time of the acrylic plate in the solution and the time for improved weather resistance when Piosolp 80 is used as a 0.5% by weight solution. It shows the relationship between the concentration and the time during which weather resistance improved during immersion time of 7 days. However, in this case, the performance of the base of the hard foot agent regarding the time period during which the weather resistance was improved was 4500 hours (peeling occurred within this time period). Figures 4 and 5 also show the same trends as Figures 2 and 8, respectively.From the above, in order to improve weather resistance, the concentration of the ultraviolet absorber should be 0.5% by weight or more, and the immersion time should be 24 hours or more is required.

Example 2 Tinuvin 900 manufactured by Ciba-Geigi Co., Ltd. was used as an ultraviolet absorber. It was dissolved in a mixed solvent of toluene, ethyl acetate, and special rubber volatile oil to prepare a 10% by weight solution. A pre-cleaned polycarbonate plate was then immersed in this solution for 48 hours at 25°C. As shown in FIG.
teosA/B) was applied to a film thickness of 15 to 16 μm by a spray method, and dried at 90° C. for 80 minutes to form an undercoat layer 6. 7 Jihart top coat on this layer 6 (
EXP1558H (manufactured by Fujikura Kasei Co., Ltd.) was applied using a spray method to a film thickness of 15 to 17μ, dried at 90°C for 15 minutes, and then irradiated with ultraviolet light (80L x 2 lights x 6 lights 4 x 8 times).
A top foot layer 7 was then provided to obtain a surface hardened carbonate plate. In addition, 6 in FIG. 6 indicates Tinuvin 900.

This surface-hardened plastic, which used to peel off in 900 hours with Sunshine Weather Omate, actually peeled off in just 2 hours.
It was extended to 500 hours.

(Effects of the Invention) As explained above, the surface-hardened plastic of the present invention is constructed by applying a surface-hardening treatment to the base material, which is a plastic whose surface layer is impregnated with an ultraviolet absorber. Therefore, it is possible to suppress the deterioration reaction that progresses to the plastic surface, and as a result, the weather resistance of surface-hardened plastics is significantly improved, and especially when polycarbonate plates are used, yellowing of the surface can be suppressed. can get.

[Brief explanation of the drawing]

Fig. 1 is a cross-sectional view of a surface-hardened plastic according to an example of the present invention, and Fig. 2 shows the relationship between the immersion time of the polycarbonate of the surface-hardened polycarbonate plate of Example 1 in an ultraviolet absorber solution and the time at which the weather resistance is improved. Figure 8 is a curve diagram showing the relationship between ultraviolet absorber concentration and time for improved weather resistance, Figure 4 is a curve diagram similar to Figure 2 when the acrylic substrate of Example 1 is used. Figure 5 is a curve diagram showing the relationship between immersion time and time for improved weather resistance. Figure 5 is a curve diagram showing the relationship between ultraviolet absorber concentration and time for improved weather resistance, similar to Figure 8. Figure 6 7 is a cross-sectional view of a surface-treated plastic according to another example of the present invention, and FIG. 7 is a cross-sectional view of a conventional surface-treated plastic.・1...Polycarbonate board 2...Primer single layer 8...Hard foot layer 4・
...Uvinal 4005...Tinuvin 9006...Fuji Hard Underfoot Layer...Fuji Hard Top Coat Layer Patent Applicant Nissan Motor Co., Ltd. Figure 1 Figure 2 Comic; tv! between the days

Claims (1)

[Claims] 1. A surface hardening plastic comprising a primer layer and then a hard coat layer laminated on the surface of a plastic substrate whose surface layer is impregnated with an ultraviolet absorber.