JPH09225961A - Manufacture of optical plastic product - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize the high productivity and improve the dimension accuracy and surface accuracy of a product by including the process B for injecting resin same as the resin used in the process A for a part or the whole of a preliminary molded product and molding the molded procut in which the preliminary molded product is integrated with the molten injected resin and molding in several stages. SOLUTION: A mold is of a two-stage structure, upper and lower, and a secondary molded product 2 is injection molded, while a tertiary molded product 3 is injected molded on the lower side. In the upper stage section of the mold, a preliminary molded product 1 molded in another injection molding die is set in a fixed mold 10. Then molten resin is injected into a cavity 12 for molding the secondary molded product 2 to manufacture the secondary molded product 2 integrated with the preliminary molded product 1. After the secondary molded product 2 is molded, a movable mold 11 is released from a fixing fitment 10, opened and rotated to set the mold in the lower stage state. Molten resin is injected into a cavity 13 for molding the tertiary molded product 3 to manufacture a tertiary molded product in which the preliminary molded product 1 is molten integrated with the secondary molded product 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical plastic product such as a macroscopic optical system (loupe, various viewfinders, etc.), an ophthalmic optical system (eyeglass lens, contact lens), illumination / light receiving system (condenser). , Infrared projectors, radiation thermometers, solar furnaces, vehicle lamps, etc.), photography systems (various lenses, etc.), laser optical systems (interferometers, scanners, etc.), etc.

[0002]

2. Description of the Related Art Generally, glass is used as a material for optical products. The reason for this is that there are advantages such as a wide variety of glasses, good stability of optical physical properties, excellent heat resistance, and little change in physical properties due to temperature change. However, this optical glass is not without its drawbacks, it is heavy, hard and brittle, and requires man-hours to grind, resulting in poor productivity.Products with an aspherical shape have poor reproducibility of the polishing process and productivity. There was also a disadvantage that it was inferior. Further, depending on the type of glass used, there are some which have problems such as poor weather resistance.

In view of these drawbacks, recently, the use of plastic as a material for optical products has been studied. The advantages of this optical plastic product are its lightness and high impact resistance, and it is currently used as a material for eyeglass lenses. Another advantage is that
It can be easily made into any shape, and mass production can be done according to injection molding, reducing man-hours.
And excellent reproducibility.

As a method for producing an optical plastic product, there is a grinding and polishing method in addition to the injection molding method. Recently, the Rolinks method, the micromolder method, and the injection press method have been developed as injection compression molding methods, which are more advanced molding methods that are further developments of the injection molding method. Melted resin is injected into the mold that is held with a low mold clamping force in advance, the mold clamping force loses the injection pressure during the filling process, the mold division surface is opened, and the injection gate is closed when the filling is completed. In this method, the mold is pressurized to close the dividing surface, and the pressure is maintained while cooling. Is a method of closing the dividing surface of the mold by mold clamping force, injecting a predetermined amount of resin into the cavity, and then partially applying compressive force to the resin by another independent pressure device. There are those in which a hydraulic cylinder is incorporated in a mold and those in which a movable plate of an injection molding machine is incorporated. Is a method of injecting a molten resin into a mold space that has been enlarged by a compression stroke in advance, closing the mold during filling or at the time of completion of filling, and compressing the filled resin with a mold clamping force. By these methods, plastic products with high dimensional accuracy are being obtained, but due to the complicated mechanism of injection molding machines and molds, and more advanced and precise technology on molding, It is hard to say that it is popular as a general method in the industrial production method of optical plastic products both technically and economically.

[0005]

However, in the cutting and polishing method, it is easy to obtain a high surface accuracy for a flat surface or a spherical surface, but it is possible to obtain a surface accuracy in spite of the large number of man-hours required for an aspherical surface. There are drawbacks such as difficulty. Also,
The injection molding method has a drawback that the product shrinks as the temperature of the product decreases after the product is taken out of the mold, and the product has a size different from that of the mold. This phenomenon becomes more remarkable as the maximum wall thickness of the product is 10 mm or more, and the uneven thickness structure having no symmetry is formed.

Therefore, according to the present invention, the maximum wall thickness of the product is 1
To provide a method for producing an optical plastic product having high productivity and good dimensional accuracy and surface accuracy even if the product has a thickness of 0 mm or more or a product having an uneven thickness structure without symmetry. With the goal.

[0007]

In order to achieve the above-mentioned object, the present invention provides a step of molding a primary molded product by injecting a molten resin into a cavity of a mold in a method for manufacturing an optical plastic product. A, and the step B of injecting the same resin as in step A into a part or the whole of this primary molded product to form a molded product in which the primary molded product and the injected resin are melt-integrated.

[0008]

DETAILED DESCRIPTION OF THE INVENTION The present invention will be described below with reference to the drawings.

FIG. 1 shows an example of a mold according to the method for producing an optical plastic product of the present invention, and FIGS. 2 to 4 show a molded product obtained in each step of the method for producing an optical plastic product of the present invention. It is a perspective view which shows an example. In FIG. 1, the mold has an upper and lower two-stage structure, the secondary molded product 2 is injection molded on the upper side, and the tertiary molded product 3 is injection molded on the lower side. The right side shows the fixed mold 10, and the left side shows the movable mold 11. In the upper part of this mold, the primary molded product 1 (see FIG. 2) molded by another injection molding mold is set in the fixed mold 10.

Next, a molten resin is injected into the cavity 12 for molding the secondary molded product 2 to obtain a secondary molded product 2 (see FIG. 3) integrated with the primary molded product 1. Here, by using resins of the same quality and the same grade as the materials of the primary molded product 1 and the secondary molded product 2, the primary molding is performed when the molten resin for molding the secondary molded product 2 comes into contact with the primary molded product 1. Item 1
Since they can be covered and integrated while melting, in the molded product shown in FIG. 3, there is no material or optical interface between the primary molded product 1 and the secondary molded product 2.

Finally, after molding the secondary molded product 2, the movable mold 11 is opened from the fixed mold 10 and rotated to the lower state shown in FIG. 1, and the cavity 13 for molding the tertiary molded product 3 is formed. A molten resin is injected into the mixture to obtain a tertiary molded product (final product) (see FIG. 4) which is melt-integrated with the primary molded product 1 and the secondary molded product 2. Here, similarly to the above-mentioned secondary molded product 2, the primary molded product 1, the secondary molded product 2, and the tertiary molded product 3 are made of the same quality and the same grade of resin material.
When the molten resin for molding is in contact with the primary molded article 1 and the secondary molded article 2, the primary molded article 1 and the secondary molded article 2 can be covered and integrated while melting, and therefore the primary molded article shown in FIG. No interface is formed between the molded product 1 / secondary molded product 2 / tertiary molded product 3 in terms of material and optical properties.

The mold used in the manufacturing method of the present invention is not limited to the mold composed of the fixed mold 10 and the movable mold 11 as described above, but a known mold such as a final product. It is also possible to provide multiple primary molded products or numbered molded products in a single mold, including this, and this mold can be used to mold each primary molded product to the final product in one molding cycle. You can In addition, here, each subsequent molded product is processed in the mold for each subsequent step (process) every molding cycle.
It is necessary to move it to a predetermined place in the same mold, but at the same time, as described above, the final product is
It is possible to create individual pieces. As a result, the molding time to reach the final product is significantly shorter than the method of molding using one mold for each subsequent molded product and final product. An improvement can be achieved.

Further, the step B is preferably performed once or more. When the number of times of the step B is a plurality of times, it is as described above (molding of the secondary and tertiary molded products 2 and 3), but when the number of times is only once, the inside of the cavity of the mold is After undergoing the step A of injecting the molten resin into the primary molded article 1 and then performing the step A on a part or the whole of the primary molded article 1.
The final product is obtained through step B in which the same resin is injected and the primary molded product 1 and the injected molten resin are integrated to form a molded product.

Further, in the above-mentioned embodiment, one primary molded product 1 serving as the core is used, but two or more primary molded products 1 may be used depending on the shape and size of the final molded product. Further, although the case where the convex lens is molded with the resin material is illustrated in FIGS. 1 to 4, in the case of the concave lens, the primary molded product 1 can be provided near the outer peripheral edge. At this time, as the primary molded product 1, a donut-shaped product having a hole at the center is used. Optical components such as lenses are required to have dimensional accuracy.

When selecting an optical plastic, it is important to select a resin that is transparent to visible light. Further rationale is as follows. Do not absorb visible light inside the resin. That is, it has a light transmittance as high as possible. The tissue is dense, each size is smaller than the wavelength and does not cause scattering. It is better that spherulites do not exist. Be isotropic. This relates to the stability of optical properties such as the refractive index. Suitable resin for use is P
MMA, PS, AS, PC, Sebian MAS20, polymethylpentene, styrene-butadiene copolymer, K
Examples thereof include resins.

Hereinafter, the present invention will be described more specifically by showing Examples and Comparative Examples, but the present invention is not limited to the following Examples.

[0017]

EXAMPLES Molding of Primary Molded Product A primary molded product 1 shown in FIG. 5 was injection molded under the following conditions. Injection molding machine: Meiki Seisakusho M-100A-TS Resin: Delpet 80N (PMMA manufactured by Asahi Kasei Corporation)
Resin) Pre-drying 80 ° C x 4 hours Injection molding conditions: Barrel (cylinder) temperature setting Nozzle temperature 230 ° C Barrel temperature 245 ° C Hopper side temperature 230 ° C Mold temperature setting: 90 ° C by water circulation Here, injection 2 ~ 3rd pressure Depending on the condition setting of (holding pressure), although no void was generated, a sink mark on the surface generated due to shrinkage or a dimensional defect sometimes occurred. In addition,
These molded products were also directly subjected to the molding process of the secondary molded product 2 and further subjected to the process of the tertiary molded product 3.

Molding of Secondary Molded Product and Tertiary Molded Product Next, the obtained primary molded product 1 is injection molded under the above conditions, and the secondary molded product 2 and the tertiary molded product 3 shown in FIGS. 6 and 7 are shown.
Were sequentially molded. In both cases, including the dimensionally defective product in the primary molded product 1, it was possible to mold the secondary molded product 2 and the tertiary molded product 3 with the desired size without the occurrence of defective phenomena such as sink marks. . In particular, even when the lens surface in FIG. 7 has an aspherical shape, it was confirmed by three-dimensional shape measurement that the aspherical shape could be molded according to the mold dimension. Further, when the final molded product was visually observed under sunlight, the interface between the primary to tertiary molded products 1 to 3 was not visually recognized. Further, even when the laser light is incident at a right angle, the interface between the molded products is not visible. Further, when laser light was incident at an angle of 45 degrees, the interface was not visually recognized.

[Comparative Example] The molding of the final molded product of the embodiment was tried without molding the above-mentioned primary and tertiary molded products 1 to 3, but in ordinary injection molding, voids were generated depending on the injection conditions. Although somehow avoided, sink marks were conspicuous on the outer surface including the aspherical portion, and molding with a desired dimension, that is, a dimension as a mold could not be performed only by setting injection conditions.

[0020]

As described above, according to the present invention, in the method for producing an optical plastic product, the step A of injecting the molten resin into the cavity of the mold to form the primary molded article, and the primary molding It includes the step B of injecting the same resin as in step A into a part or the whole of the article, and molding a primary article and a molded article in which the injected resin is melt-integrated, and is formed in several stages. Therefore, the cycle time is shortened and the productivity is improved. Further, by making the thickness formed in the final injection relatively thin, an optical plastic product having a desired shape and high surface accuracy can be obtained. In particular, in the present invention, some sink marks or the like at the time of the primary molded product are not a problem because the resins are melted and integrated between the molded product and the coated resin. Furthermore, in the method in which the process B is repeated, the wall thickness can be adjusted freely.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an example of a mold used in the manufacturing method of the present invention.

FIG. 2 is a perspective view showing a primary molded product.

FIG. 3 is a perspective view in which a primary molded product and a secondary molded product are integrated.

FIG. 4 is a perspective view showing a final molded product.

FIG. 5 is a perspective view showing a primary molded product of Example.

FIG. 6 is a perspective view in which the primary molded product and the secondary molded product of the embodiment are integrated.

FIG. 7 is a perspective view showing the final molded product of the embodiment.

[Explanation of symbols]

 1 Primary molded product 2 Secondary molded product 3 Tertiary molded product

Claims (5)

[Claims] 1. A method of manufacturing an optical plastic product, which comprises a step A of injecting a molten resin into a cavity of a mold to form a primary molded article, and a step A for a part or whole of the primary molded article. Step B of injecting the same resin and molding a molded product in which the primary molded product and the injected resin are melt-integrated.
A method for producing an optical plastic product, which comprises: 2. The method for producing an optical plastic product according to claim 1, wherein the maximum thickness of the optical plastic product is 10 mm or more. 3. The optical plastic product having an uneven thickness structure having no symmetry.
A method for producing the described optical plastic product. 4. The method for manufacturing an optical plastic product according to claim 1, wherein the step B is repeated twice or more. 5. The optical plastic product has an aspherical surface on the surface thereof.
5. The method for producing an optical plastic product according to any one of items 1 to 4.