JP3056959B2 - Molding method for resin molded products - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for molding a resin molded article in which a thermosetting resin mixed with a crosslinking agent is molded by heating and pressing with a mold.

[0002]

2. Description of the Related Art Conventionally, a thermosetting resin mixed with a crosslinking agent has been heated and pressed using a mold.
There are dents and burning. Therefore, it has been proposed to provide a vacuum deaerator in a mold and perform vacuum deaeration at the time of molding.
It is disclosed in Japanese Patent Publication No. 2-50370. However,
When the styrene gas is degassed by vacuum degassing, there is a problem that the ratio of the crosslinking agent to the thermosetting resin decreases, the crosslink density decreases, and the performance of the molded resin product decreases. For example, there is a problem that a whitening phenomenon occurs in an immersion test in a hot water environment.

[0003]

SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and has as its object the following.
Provided is a method for molding a resin molded article capable of preventing a local crosslink density from being lowered in a portion below a liquid level where a high-temperature liquid is contained in a container to be molded, while preventing a phenomenon such as a void from being caused by vacuum degassing. To be.

[0004]

In order to solve the above-mentioned problems of the prior art and achieve the object of the present invention, a method of molding a resin molded product of the present invention comprises a method of forming a thermosetting resin mixed with a crosslinking agent. High-temperature liquid B which is heated and pressurized by the split mold 2 and put into it
In the method for molding a resin molded product in which a container A of a molded product whose liquid level is equal to or lower than a predetermined position is obtained, after disposing the thermosetting resin at the cavity 3 position of one mold corresponding to the bottom of the container A The mold closing of the split mold 2 is started, and the cavity 3 becomes airtight in the process of closing the mold. After the resin has passed, the cavity 3
The vacuum deaeration is started, and the molding is performed by ending the vacuum deaeration together with the completion of the closing of the split mold 2.

[0005]

According to the method of the present invention as described above, after the thermosetting resin mixed with the crosslinking agent is placed in the mold 2, the mold is closed in the step of closing the mold 2. After the thermosetting resin passes through the position of the cavity 3 of the split mold 2 corresponding to a predetermined position of the container A, the cavity 3
Vacuum deaeration is started, and the vacuum deaeration is completed when the mold closing of the split mold 2 is completed. Therefore, the vacuum deaeration is performed halfway (that is, until the thermosetting resin passes through a predetermined position of the cavity 3). By not doing so, the cross-linking agent does not volatilize, and the local cross-linking density is prevented from lowering from the bottom of the container A to be molded to a predetermined position where the high-temperature liquid B is put,
After the thermosetting resin has passed through a predetermined position of the cavity 3, vacuum degassing is performed, thereby preventing generation of voids.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail based on a first embodiment shown in the accompanying drawings. 1 to 4 show the molding order of the present invention. In the figure, reference numeral 2 denotes a split mold for molding a container A, which is a molded product, which is composed of a lower mold 2a and an upper mold 2b, wherein the lower mold 2a is a convex mold and the upper mold 2b is a concave mold. ing. The split mold 2 (the upper mold 2b in the embodiment) is provided with a vacuum deaeration hole 6, and a vacuum pump (not shown) is connected to the vacuum deaeration hole 6. In the drawing, reference numeral 7 denotes a packing provided on the split mold 2.

Then, the split mold 2 is opened, and FIG.
The thermosetting molding material 1 is arranged on the upper surface of the lower mold 2a which is the convex corresponding to the bottom of the container A to be molded as described above. As the thermosetting molding material 1, a thermosetting resin such as an unsaturated polyester resin or a vinyl ester resin is used as a base resin, and a predetermined amount (5 to 15% by weight) with respect to the base resin. SMC that performs radical crosslinking polymerization with styrene monomer as a mixed crosslinking agent
(Sheet mold compound), BMC (bulk mold compound), and the like are used. next,
As shown in FIG. 2, the mold closing is started, and as shown in FIG. 3, the vacuum degassing is started in the middle of the mold closing step. Thereafter, as shown in FIG. 4, the mold closing is completed and the vacuum degassing is ended. By heating and pressing, a deep drawn box-shaped container A which is a molded product is obtained.

In the present invention, it is assumed that a high-temperature liquid B (for example, hot water) is put in a container A which is a molded product as shown in FIG. It does not come into contact with hot water in the range of height H. Also, FIG.
As shown in FIG. 5, when the mold is closed from the height Hp from the upper surface of the container A, which is a molded product, the packing 7 is fitted so that vacuum degassing is possible. Then, in the present invention, after the thermosetting molding material 1 is arranged on the upper surface of the lower mold 2a corresponding to the bottom of the container A, the mold closing of the split mold 2 is started, and FIG.
Time cavity 3 is hermetically from, rows closed further mold
Time after the cavity 3 position of the split mold 2 corresponding through thermosetting resin to a predetermined position of the container A to be cane molding (at a height H from the upper surface of the container A) I, i.e., FIG. 3 When Hv becomes Hv ≦ H, vacuum closing of the cavity 3 is started and the mold closing is continued while performing vacuum degassing, and the mold closing of the split mold 2 is completed as shown in FIG. At the same time, the vacuum degassing is completed and the molding is performed. Here, a graph showing the relationship between the mold opening amount and the time at the time of closing the mold is as shown in FIG. 6. In FIG. 6, C indicates the start of fitting of the packing 7, and D indicates the time during which vacuum degassing is performed. Is shown.

The container A, which is a molded article formed in this manner, is not degassed in vacuum at least in a portion excluding the range of the height Hv from the upper surface of the container A, so that the crosslinking agent does not volatilize, and Since the crosslink density does not decrease, and Hv ≦ H in the present invention, as a result, at least the portion of the container A that is in contact with the high-temperature liquid B at a portion below the water surface of the assumed high-temperature liquid B Means that the local crosslink density does not decrease. Further, in forming the container A, vacuum degassing is performed at the time of molding in a range of the height Hv from the upper surface of the container A (this range is included in a portion of the container A not in contact with the high-temperature liquid B). The formation of voids can be prevented, and in this portion, the cross-linking agent volatilizes due to vacuum degassing. However, since this portion does not come into contact with the high-temperature liquid B, even if there is a local decrease in the cross-linking density, the container A In the use as, there is no contact with the high-temperature liquid B, so no whitening or the like occurs. The container A to be molded is, for example, a bathtub.

Next, specific examples and comparative examples of the present invention will be described. (Specific Example) In this embodiment, the container A, which is a molded product to be molded, is assumed to contain the high-temperature liquid B, and does not come into contact with the high-temperature liquid B within a range of a height H (30 mm) from the upper surface of the container A. Shall be. In molding a container under such conditions, first, an unsaturated polyester resin is used as a base resin, and 90% by weight of the base resin and 10% by weight of a styrene monomer are mixed. BMC, which is a thermosetting molding material 1 containing 25% by weight of a saturated polyester resin, 65% by weight of a filler, and 7% by weight of a reinforcing material, is formed on the upper surface of a convex lower mold 3b (that is, a container A to be molded). (The cavity 3 portion corresponding to the bottom of the above). Next, as the mold is closed, the packing 7 is fitted from the height Hp (60 mm) from the upper surface of the container A as shown in FIG. The thermosetting molding proceeds to Hv (10 mm in the embodiment) after the thermosetting molding material 1 has passed H (30 mm), which is a height not in contact with the high-temperature liquid B of the container A to be molded. Vacuum degassing is started when the material 1 comes, and 60 hours until the mold closing is completed.
mmHg was maintained (the mold closing time was 1 minute). Simultaneously with the closing of the mold, the vacuum degassing was stopped, and the container A, which was the target molded product, was molded by heating and pressing. In the container A, which is a molded product thus obtained, no whitening phenomenon occurred for 300 hours or more in a immersion test in a hot water environment at 98 ° C.

(Comparative Example) An unsaturated polyester resin was used as a base resin, and 90% by weight of the base resin and 10% by weight of a styrene monomer were mixed. , Filler 65
Thermosetting molding material 1 containing 7% by weight of reinforcing material
Is placed on the upper surface of the lower mold 3b (ie, the cavity 3 corresponding to the bottom of the container A to be molded). Next, as the mold is closed, the packing 7 is fitted from the height Hp (60 mm) from the upper surface of the container A as shown in FIG. When mold closing progresses and Hv becomes 50 mm, vacuum degassing starts,
60 mmHg was maintained until the mold closing was completed (the mold closing time was 1 minute). Simultaneously with the closing of the mold, the vacuum degassing was stopped, and the container A, which was the target molded product, was molded by heating and pressing. In the immersion test in a hot water environment at 98 ° C., the container A, which is a molded product obtained in this way, showed a whitening phenomenon within a range of 30 to 50 mm in height from the upper surface of the molded product within 150 hours.

As is clear from the test results of the specific examples of the present invention and the comparative examples, it can be seen that the whitening phenomenon does not occur in the present embodiment.

[0013]

According to the first aspect of the present invention, a thermosetting resin mixed with a cross-linking agent is heated and pressurized by a split mold so that the liquid level of the high-temperature liquid to be put into the resin is below a predetermined position. In the method for molding a resin molded article to obtain a molded article container, the thermosetting resin is arranged at a cavity position of one of the molds corresponding to the bottom of the container, and then the mold closing of the split mold is started. Then, in the process of closing the mold, the cavity becomes airtight, and after the thermosetting resin passes through the cavity position of the split mold corresponding to a predetermined position of the container to be molded,
Since the vacuum degassing of the cavity is started and the vacuum degassing is completed at the same time as the mold closing of the split mold is completed and the molding is performed, local cross-linking in a portion of the container to be molded below the liquid level where the high-temperature liquid is put is provided. Since the density can be prevented from lowering, and vacuum degassing is performed at a position that does not come into contact with the high-temperature liquid, not only can the generation of voids and the like be suppressed, but also the crosslinking agent volatilizes due to vacuum degassing in this area. However, since it is a portion that does not come into contact with the high-temperature liquid, there is no problem in terms of heat resistance.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a molding order according to the present invention.

FIG. 2 is a cross-sectional view showing a molding order in the same.

FIG. 3 is a cross-sectional view showing a molding order in the same.

FIG. 4 is a cross-sectional view showing a molding order in the same.

FIG. 5 is an explanatory view of putting a high-temperature liquid into a container which is a molded product to be molded in the present invention.

FIG. 6 is a graph showing vacuum degassing time in relation to the amount of mold opening and time when closing the mold of the split mold according to the present invention.

[Explanation of symbols]

 2 Split mold 3 Cavity A Container B High temperature liquid

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Satoshi Yamauchi 1048 Kadoma Kadoma, Osaka Pref.Matsushita Electric Works, Ltd. Inventor Masami Matsumoto 1048 Kadoma, Kazuma, Osaka Prefecture Inside Matsushita Electric Works Co., Ltd. (72) Inventor Shozo Tanaka 5-8 Nisoburi-cho, Suita-shi, Osaka Japan Resin Technology Research Institute, Inc. (72) Invention Person: Shigeru Oka 5-8, Nishiomibashi-cho, Suita-shi, Osaka Inside of the Japan Catalyst Resin Research Institute Co., Ltd. (56) References JP-A-2-258236 (JP, A) JP-A-63-268608 (JP, A) JP-A-63-178013 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B29C 43/00-43/58

Claims (1)

(57) [Claims] 1. A method of molding a resin molded article, in which a thermosetting resin mixed with a cross-linking agent is heated and pressurized by a split mold to obtain a molded article container in which the liquid level of a high-temperature liquid to be put into is below a predetermined position. In the above, after disposing the thermosetting resin at the cavity position of one of the molds corresponding to the bottom of the container, the mold closing of the split molds is started, and the cavity becomes airtight in the process of mold closing, and molding is performed. After the thermosetting resin has passed through the cavity position of the split mold corresponding to the predetermined position of the container to be cleaned, vacuum deaeration of the cavity is started, and the vacuum deaeration is performed when the mold closing of the split mold is completed. A method for molding a resin molded article, wherein the molding is performed after completion of the above.