Plastic and nonmetallic article shaping or treating: processes – Mechanical shaping or molding to form or reform shaped article – To produce composite – plural part or multilayered article
Patent
1994-01-04
1997-10-14
Weisberger, Richard
Plastic and nonmetallic article shaping or treating: processes
Mechanical shaping or molding to form or reform shaped article
To produce composite, plural part or multilayered article
264259, 264260, 264261, 264279, 425553, 425566, B29C 4516, B29C 4514, B29C 4122, B29C 4120
Patent
active
056769016
DESCRIPTION:
BRIEF SUMMARY
SPECIFICATION
1. Technical Background of the Invention
This invention relates to a resin-coating process for forming a resin coating layer on one side surface of resin moldings prepared with upper and lower split molds employed and with a fluid coating material injected into the molds after the preparation of the moldings, a resin-coating apparatus for use in performing the process, material for use in performing the process, and a molded product such as, in particular, a bathtub and the like obtained through the particular process.
2. Disclosure of Prior Art
In molding the bathtub, paneling or the like made of a thermosetting resin, it has been common to form a resin coating on one side surface of the same, on the inner side surface in the case of the bathtub, for example, and as a practical process there has been a process known as an in-mold coating process, for example. According to this process, a pair of split molds comprising a stationary mold and a movable mold (generally constituted by such male mold as a lower mold and such female mold as an upper mold) are employed, and the process comprises a step of obtaining resin moldings of a predetermined shape with such molding material as a bulk or sheet shaped resin molding material (BMC, SMC etc) disposed between the split molds and thereafter subjected to a mold clamping (compression) and a hot pressing, and a step of coating the surface of each molding with the fluid coating material injected between one side surface of the resin molding and a surface of the mold, which process is advantageous in that the molding and coating can be carried out with the same apparatus employed and through sequential steps. In addition to this advantage, it is also possible to obtain a molded resin product having the surface beautifully coated and excellent in the smoothness.
Since in the foregoing process the molded resin product is manufactured generally with a thermosetting resin, the molding requires the heating along with the compression, whereas it is also necessary that, because the thermosetting resin is employed generally as the foregoing coating material, the material maintains the fluidity at its injecting step as cooled to an extent not causing the curing to excessively advance. Accordingly, there is a problem that temperature administration of the mold is complicated. In injecting the fluid coating material, further, it has been general that a mold which allows an excess body part to be formed at part of peripheral edge of the molded resin product is employed, and the fluid coating material is injected through a nozzle facing the excess body part, but there remains a problem that the coating material cannot be distributed constantly stably and sufficiently to the peripheral part at positions separated far from the excessive body part. Further, to cope with this, it may be possible to employ an arrangement having a plurality of the excess body parts, but it becomes necessary to provide mutually independent injecting means with respect to them, and there arises a problem that required costs for the mold rise or maintenance/administration or productivity of the apparatus is deteriorated.
With respect to the above, there has been suggested an improved apparatus such as disclosed in Japanese Patent Laid-Open Publication No. 62-160216, according to which there has been provided an apparatus for supplying the coating material from a substantially central position on reverse side of the resin molding, while the upper mold is arranged to be movable and the lower mold is made to be stationary. In the central part of the lower mold, means for injecting the coating material is ptovided, which means is provided with a casing incorporating a plug-shaped hole forming means for free projection and retraction, and this casing is disposed with a space interposed for restraining as much as possible a heat intrusion from its circumference, in particular, from the lower mold. When the foregoing resin molding is prepared, the hole forming means is projected to render the injec
REFERENCES:
patent: 4076788 (1978-02-01), Ditto
patent: 4668460 (1987-05-01), Ongena
patent: 4783298 (1988-11-01), Oda
Higashi Keiji
Kajiura Hisanao
Kobayakawa Masunori
Maki Yoshikazu
Matsumura Shusuke
Matsushita Electric & Works Ltd.
Weisberger Richard
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