JPS63178136A - Highly light-transmitting molding - Google Patents

Abstract

PURPOSE:To obtain the title molding excellent in light transmission and suitable as, e.g., a signal lens for weak light, by injection-molding a polymethyl methacrylate comprising methyl methacrylate and a deuterated methyl acrylate. CONSTITUTION:A polymethyl methacrylate obtained by mixing or copo lymerizing 70-0% methyl methacrylate with 20-100% deuterated methyl methacrylate is used as a molding material. This material is injection-molded to obtain the desired title molding.

Description

[Detailed Description of the Invention] Polystyrene, polycarbonate, and polymethyl methacrylate are highly transparent, have an appropriate refractive index, are non-porous, and have far superior moldability compared to glass. Recently, it has been used to mold everything from general-purpose lenses to high-quality lenses.

Among these, polymethyl methacrylate is one of the most commonly used materials because it has good light transmittance and is unlikely to cause birefringence.

However, recently, polymethyl methacrylate lenses have also begun to be used for applications that transmit and refract weak optical signals. In such applications, polymethyl methacrylate lenses have a wavelength-4 wavelength of 530 to 570 nm.
At m, the light transmittance is good, but at wavelengths of 700 nm or more, light absorption (reduction in transmittance) suddenly begins to appear.

In response to this, we produced a deuterated polymethyl methacrylate molding material using deuterated methyl methacrylate as a raw material, in which the hydrogen in the polymethyl methacrylate molecules was replaced with deuterium, molded it into an optical lens, and measured the light transmittance. It was found that the optical transmission loss was significantly reduced even in the long wavelength region, making it suitable for use as a signal lens for weak light.

For example, the relationship between the wavelength of light and the light transmission loss of a lens is as follows.

Wavelength (nm) PMMA Deuterium P MMA5
00 1.00 1.00530
1.00 0.98550 1
．． 00 0.50600 1.00
0.30630 1.00
0.12650 1
．． 00 0.24700
1.00 0.10?50
1.00 0.25780
1.00 0. QB8
00 1.00 0.
25850 1.00
0.23 The above numerical value is the result of molding a plane lens of the same shape and measuring the light transmittance at each wavelength. When the transmittance of polymethyl methacrylate (PMMA) is 1, it is a deuterium PMMA molded product. It represents the transmittance loss ratio of
1.00 is equivalent to PMMA, and i,oo or less indicates better light transmittance than that.

As shown in the above results, deuterium polymethyl methacrylate did not show a significant change in the short wavelength region, but a significant difference was observed in the long wavelength region.

Since camera lenses and the like usually use the entire visible wavelength range, it has been clearly shown that lenses molded using 9 deuterium polymethyl methacrylate are bright lenses.

This characteristic is also important for weak signal light, especially for 780
Since it has excellent wavelength absorption characteristics of nm, it is very effective for optical systems that utilize such signal light. Furthermore, even if optical discs and the like come to use short wavelength light in the future, the deuterated polymethyl methacrylate lens can be said to be a plastic lens that can be fully put to practical use.

However, nine deuterium polymethyl methacrylate is currently an expensive material. Therefore, the present inventor conducted various studies on the optical properties of copolymer compositions of inexpensive general-purpose polymethyl methacrylate and expensive deuterated polymethyl methacrylate, and mixtures of each polymer. As a result, it was found that the light transmission loss of the lens decreased in proportion to the amount of deuterium polymethyl methacrylate added.

Deuterated PMMA Loss ratio addition rate (%) (light transmission) 0 1, 00 20 0.86 40 0.70 60 0, 5380
0, 33100
0, 16 (measurement wavelength: 650
nm) Therefore, in the present invention, the composition of the molding material can be determined in actual industrial production based on the relationship between the required performance of the optical component, the light transmission characteristics of the lens, and the product price.

Example 1 A molding material was produced by polymerizing deuterium methyl methacrylate alone under heat and pressure under nine general conditions.

Example 2 A molding material was obtained under the same conditions as in Example 1 by mixing 80 parts of deuterium methyl meth-6-rylate and 20 parts of methyl methacrylate.

Example 3 80 parts of deuterium polymethyl methacrylate and 20 parts of polymethyl methacrylate were melt-kneaded to obtain a molding material.

Comparative Example 1 Methyl methacrylate was polymerized alone under the same conditions as in Example 1 to obtain a molding material.

The molding materials obtained in Examples 1 to 3 and Comparative Example 1 were molded using a small injection molding machine (injection molding capacity: 12 g, clamping pressure: 10 tons) at a cylinder temperature of 240°C.

Molding was carried out at an injection pressure of 1200 kg/cm2 and a mold of 80°C to form a molded product with a diameter of 10 mm and a thickness of 2 mm, and the light transmission loss of this sample was measured.

Light transmission loss ratio of molded product Comparative example 1 1.00 Example 1 0.16 Example 2 0.32 Example 3 0.35 (Measurement wavelength 650nm)

Claims (1)

[Claims] A transparent optical molded article molded by injection molding using a polymethyl methacrylate molding material in which methyl methacrylate and deuterium methyl methacrylate are mixed or copolymerized in a ratio of 70:20 to 0:100.