JPH06155481A - Method for producing cured plastic - Google Patents

Abstract

(57) [Summary] (Modified) [Purpose] Injecting through the inside in a processing method of casting a plastic raw material mainly composed of a liquid curable compound in a cavity formed between two molds. Provided is a method for reliably sealing an injection hole after filling a plastic raw material 5 through the hole. [Structure] After filling a plastic raw material 5 into the cavity from an injection hole communicating with the inside, an ultraviolet curable resin having a functional group similar to the compound is applied to the injection hole, and is cured by reaction to ensure the injection hole. Seal. [Effect] By coating the injection hole with a UV-curable resin having the same functional group as the compound in the cavity, the deposits around the injection hole are also reactively cured, so that the injection hole can be reliably and quickly sealed. You can stop.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a cured product of plastic. More specifically, the present invention relates to a manufacturing method in which a UV-curable resin is used to seal the injection hole for injecting the raw material into the cavity when a cured plastic product is obtained by casting.

[0002]

2. Description of the Related Art As a conventional manufacturing method, in the case of a processing method of holding a mold with a gasket, a method of pressing the mold against the gasket with a spring as shown in FIG. 5 and sealing it is generally known.

In the case of a processing method in which a mold is held by an adhesive tape, the adhesive tape described on lines 3 to 38 on the left side of page 3 of JP-B-63-23890 is peeled off until the cavity is exposed, and the plastic There has been known a sealing method shown in FIGS. 6 and 7 in which an adhesive tape is overlapped and reapplied and sealed after filling the raw material.

[0004]

However, the above-mentioned prior art has the following problems.

(1) In the method of pressing the mold shown in FIG. 5 against the gasket with a spring for sealing, if the pressing force of the spring is weak, the internal plastic raw material is likely to leak, and conversely, if the pressing force is strong, There are problems such as deformation of the mold and gasket and deterioration of workability when attaching the spring. For example, plastic lenses have different thicknesses depending on the model, and the difference can be up to 40 mm. Therefore, in order to obtain the optimum pressing force, the spring that presses the mold against the gasket must use various kinds of springs for each model of the lens to be manufactured, which complicates the work.

(2) In the method shown in FIGS. 6 and 7, in which the adhesive tape for holding the mold is once peeled off until the cavity is exposed, the plastic raw material is filled, and the adhesive tape is attached again for sealing. When filling the raw material, it is necessary to ensure that no air bubbles remain in the cavity to ensure product quality.Therefore, overflowing plastic raw material adheres to the mold exposed surface of the plastic raw material injection part and the adhesive surface of the adhesive tape. To do. After filling the plastic raw material, attach the adhesive tape again and seal it, but since the plastic raw material adheres to the adhesive surface, the adhesive strength will decrease and the adhesive tape will peel off before the plastic raw material in the cavity hardens There are many accidents where plastic raw materials leak.

(3) Both the method of pressing the mold against the gasket with a spring for sealing and the method of peeling the adhesive tape once and filling the plastic raw material and then attaching the adhesive tape again for sealing, the mechanism becomes complicated when trying to automate. In addition, the cost of the equipment is increased, the reliability is lowered, and the processing time becomes long.

Therefore, the present invention is to solve such a problem, and an object of the present invention is to simply provide a reliable method for sealing a plastic raw material.

[0009]

The sealing method of the present invention comprises two steps.
A plastic material is filled into a cavity formed by one mold and a member that holds the two molds through an injection hole communicating with the inside, and then an ultraviolet curing resin is applied to the injection hole. The ultraviolet curable resin is characterized in that the raw material adhered to the surface of the pressure-sensitive adhesive tape is simultaneously cured by the crosslinking reaction of the functional group to seal the injection hole. The functional group is a reactive vinyl group, allyl group, (meth) acrylic group, organic acid ester group, isocyano group, isothiocyano group, hydroxyl group, amino group, cyano group, mercapto group,
Monomers and prepolymers of carboxyl groups and epoxy groups, alone or in combination, are used.

[0010]

The UV-curable resin used for sealing may be selected from any type of resin as long as it can cause a crosslinking reaction between the raw material to be cast and the functional group.

The material of the member for holding the pair of molds and forming the cavity is not particularly limited. For example, a plastic material such as plastic, rubber, metal, paper or cloth that does not leak out can be used. However, a plastic adhesive tape is most suitable because it is easy to use and economical.

The mold is most commonly made of glass and widely used, but the mold is not limited to this, and a mold made of a material other than glass can be used.

[0013]

【Example】

(Embodiment 1) FIG. 1 is a top view at the time of manufacturing a lens in an embodiment of the present invention, and FIGS. 2, 3, and 4 are sectional views seen from the front in the embodiment of the present invention.

Embodiments will be specifically described below with reference to the drawings, but the present invention is not limited to these embodiments.

As a plastic raw material, 3 parts of isopropyl peroxydicarbonate as a polymerization initiator was added to 100 parts of diethylene glycol bisallyl carbonate (parts by weight, the same applies hereinafter), and 5 parts of anhydrous sodium sulfate was added as a desiccant of water. The resulting mixture was thoroughly stirred, and then anhydrous sodium sulfate was removed by filtration.

The lens is made of (-) 3.00 diopters, 0.00 diopters, and (+) 3.00 diopters having an outer diameter of 75 mm, and a glass-type lens surface molding mold and lens specially designed and manufactured respectively. A back mold was prepared.

Adhesive tapes were prepared by combining a base material made of polypropylene and a base material made of polyethylene terephthalate, and a combination of acrylic, natural rubber, and silicon adhesives.

As the ultraviolet curable resin for sealing, an allyl ester prepolymer was used as a polyene among polyene-thiol photocurable resin systems.

A pair of glass molds 2 and 3 (lens front surface molding, lens back surface molding) are held with a required space, and a pressure-sensitive adhesive layer is provided on one side surface of the two molds. Wrap the adhesive tape 4 a little more than one lap. A space surrounded by the pair of molds 2 and 3 and the adhesive tape 4 becomes a cavity 11.

As shown in FIG. 1, the adhesive tape 4 is provided with an injection hole 1 for injecting the plastic raw material 5.

Next, as shown in FIG. 2, the plastic material 5 is filled from the injection hole 1 using the injector 6 so that no bubbles remain in the cavity 11. At this time, the plastic raw material 5 surely adheres to the surface of the adhesive tape 4 around the injection hole 1.

Next, as shown in FIG. 3, a polyene-thiol-based curable resin 7 containing an allyl group as a functional group is dropped from a discharge device 8 onto the injection hole 1 in an amount sufficient to cover the injection hole. To do.

After that, an ultraviolet irradiation device (trade name ORC
HUW-623 Oak Manufacturing), 200W
By irradiating the surface of the adhesive tape 4 by irradiating the ultraviolet ray for 15 seconds, the sealing is completed in a short time in the state of FIG. At this time, it was confirmed that the adhesive tape and the ultraviolet curable resin were sufficiently fixed even if the plastic raw material was attached to the surface of the adhesive tape.

Thereafter, the mold filled with the plastic raw material was put in a heating furnace and heated at 30 ° C. to 95 ° C. for 20 hours to cure the plastic raw material, but the sealing property was not impaired.

The mold was taken out of the heating furnace, the adhesive tape was peeled off, and the mold and the cured plastic raw material (lens) were separated. The cured product obtained was good without any defects.

Example 2 Instead of the diethylene glycol bisallyl carbonate resin used in Example 1, 1,
2-Bis [(2-mercaptoethyl) thio] -3-mercaptopropane and m-xylylene diisocyanate were mixed and filled in the cavity using a monomer system of dibutyltin dichloride as a polymerization catalyst. UV curable resin for sealing is polyene, urethane acrylate,
As the polythiol, 1,2-bis [(2-mercaptoethyl) thio] -3-mercaptopropane was used as the main component. (Comparative Example 1) A commercially available acrylic UV-curable resin was used in place of the UV-curable resin used in Examples 1 and 2, but even a high-viscosity grade product solidified at the initial stage and adhered to the tape. As the polymerization of the monomer progresses and gelation occurs and the volume shrinkage proceeds, air is drawn in from the interface between the tape and the encapsulant, and air bubbles and internal filling resin leak, resulting in a product with a satisfactory shape. could not.

[0027]

As described above, according to the present invention, the ultraviolet ray curable resin having the same functional group as the functional group of the product monomer is used to seal the plastic raw material. Even if the plastic raw material adheres to the vicinity of the injection hole of the adhesive tape or the mold, the adhered resin is polymerized, so that it firmly adheres to the tape surface and ensures reliable sealing.

(2) Since the adhesive force of the resin itself, which changes from a monomer of an ultraviolet curable resin to a polymer, is utilized, it does not contain various solvents like other adhesives and pressure-sensitive adhesives and is formed into a product. Does not affect the quality of.

(3) Unlike other adhesives, unless light energy is applied, the pot life is remarkably long and it is economical.

(4) Even if the resin is used the previous day and the resin remains, it can be used continuously just by adding it to the container again.
Almost no incidental work such as cleaning inside the coating device is required, and automation is easy. There are features such as. As a result, it becomes possible to perform reliable sealing with a simple device, and the defect rate in the production of plastic lenses and semi-finished blanks for plastic lenses is greatly reduced. Further, since it is a simple method, it can be easily automated and can be sealed in a short time, so that the effect of improving productivity is great. Obviously, the manufacturing technique of the present invention can be used not only for ultraviolet curing but also for electron beam curing, and is included in the present invention.

[Brief description of drawings]

FIG. 1 is a top view showing a configuration of each member, an injection hole for a plastic raw material, and a cavity in an embodiment of the present invention.

FIG. 2 is a cross-sectional view seen from the front, showing a state of filling a plastic raw material in the example of the present invention.

FIG. 3 is a cross-sectional view seen from the front showing a state in which an ultraviolet curable resin is dropped in an example of the present invention.

FIG. 4 is a cross-sectional view seen from the front showing a state where the ultraviolet curable resin in the embodiment of the present invention is cured and sealing is completed.

FIG. 5 is a cross-sectional view of a conventional example in which a mold is pressed against a gasket with a spring to seal a plastic raw material, as viewed from the front.

FIG. 6 is a front view showing a state in which the adhesive tape is peeled off and the plastic material is filled in the conventional example in which the plastic material is sealed using the adhesive tape.

FIG. 7 is a front view showing a state in which, after the adhesive tape is peeled off in the conventional example in which the plastic raw material is sealed using the adhesive tape, the adhesive tape is attached again to complete the sealing.

[Explanation of symbols]

 1 ... Injection hole 2 ... Mold (1) 3 ... Mold (2) 4 ... Adhesive tape 5 ... Plastic material 6 ... Injector 7 ... Polypropylene resin 8 ... Discharge device 9 ... Spring 10 ... Gasket 11 ... Cavity 12 ... UV lamp

Claims (2)

[Claims] 1. A processing method for casting a plastic raw material containing a liquid curable compound as a main component in a cavity formed between two molds, wherein the two molds and the two molds are An ultraviolet-curable resin having at least one functional group that cross-links the injection hole with the material to be cast after the plastic material is filled into the cavity formed by the holding member through the injection hole communicating with the inside. Characterized by closing the injection hole with
A method for producing a cured plastic product. 2. The method for producing a cured plastic product according to claim 1, wherein the cured plastic product is a plastic lens or a semi-finished blank for a plastic lens.