JP3259142B2 - Molding resin material - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a molding resin material.

[0002]

Using BACKGROUND ART molding resin material, for example, injection molding
Although it is common to make a plastic molded product in the form , the molded product has a disadvantage that sinks and warpages are caused by the shrinkage of the molding resin. Sinking and warping are likely to occur when the molding resin is crystalline or in thick places. Of course, various measures have been taken to prevent such sink marks and warpage.

[0003] First, there is one improvement measure by designing a molded product into a shape that is unlikely to cause sink marks and warpage. The thickness of the molded product, the size of the boss, and the size of the ribs are adjusted to minimize sink marks and warpage. However, this remedy has the disadvantage that the shape of the molding is limited.
Further, there is an improvement measure by devising a mold structure. By adjusting the position of the mold cooling pipe and the size of the gate, sink and warp are minimized. However, this remedy has the disadvantage that the mold structure is complicated.

[0004] In addition, there are improvement measures by adjusting molding conditions. By adjusting the mold temperature, resin melting temperature, injection pressure, injection speed, etc., sinks and warpage are minimized. However, this remedy has the disadvantage that it is difficult to implement due to stricter molding conditions.

[0005]

SUMMARY OF THE INVENTION In view of the above circumstances, the present invention does not involve the limitation of the shape of the molded product or the complexity of the mold structure, the molding conditions are moderate, and the molding resin is less likely to sink or warp. It is an object to provide materials.

[0006]

In order to solve the above-mentioned problems, a molding resin material according to the present invention comprises a thermoplastic crystal.
A molding resin made of RESIN, a molding resin material for injection molding obtained by adding a material having a negative coefficient of thermal expansion. Hereinafter, the molding resin material of the present invention will be described in detail. The formed shape resin (base resin), but are not limited to a particular type of resin, thermoplastic crystalline resin is suitable because the effect is remarkable. Specific types of resin include:
For example, polypropylene (PP), nylon (PA: polyamide), polybutylene terephthalate (PBT) and the like can be mentioned.

In the present invention, a material having a negative coefficient of thermal expansion (hereinafter, “coefficient of thermal expansion” is abbreviated simply to “coefficient of expansion”,
It is referred to as "negative expansion coefficient material" . In addition, the coefficient of thermal expansion
Abbreviation coefficient. ) Is not limited to a specific type, but for example, β-eucryptite having an average particle size of about 15 μm (expansion coefficient: −86 × 10 ⁻⁷ / ° C.), aluminum titanate having an average particle size of about 20 μm (expansion) Coefficient: -1
9 × 10 ⁻⁷ / ° C.). The amount of the negative expansion coefficient material to be added is not particularly limited, but usually, the range of [weight of the negative expansion coefficient material] ≦ 0.6 × [weight of the molding resin] is preferable. 60% by weight of negative expansion material for 100% by weight of molding resin
It is as follows. 60wt% of negative expansion material
When the ratio exceeds the above, molding tends to be difficult.

[0008] In addition to the negative expansion coefficient material, the molding resin may be pigments, glass fibers, ultraviolet absorbers, release agents, etc. for the purpose of coloring, improving heat resistance, improving weather resistance, and improving releasability. May be added, and these additions can be performed without any particular problem. As a molding method for producing a molded article with the molding resin material of the present invention, for example, injection molding is exemplified, but it goes without saying that the molding method is not limited to this.

[0009]

When molding is performed using the molding resin material of the present invention, the molding resin shrinks as the molding temperature falls to room temperature, but the negative expansion coefficient material expands conversely. Therefore, the shrinkage of the molding resin is just absorbed (supplemented) by the expansion of the negative expansion coefficient material, and sinking and warping hardly occur.

In the case of the present invention, since it is an improvement measure that makes sinks and warpage less likely to occur by devising the molding resin material itself, the molding conditions are not limited without limiting the shape of the molded product and complicating the mold structure. It is practically not limited to a specific range and becomes severe.

[0011]

Embodiments of the present invention will be described below. Of course,
The present invention is not limited to the following embodiments. -Example 1-In Example 1, the following molded resin material was used, and molded articles shown in FIGS. 1 and 3 were produced by injection molding. Molding temperature is 26
0 ° C.

The molded article 1 shown in FIG. 1 has a shape in which a column 3 is erected at the center of the back surface of a flat plate 2. The molded article 6 in FIG. 3 has a shape with a partition 8 on the right side of the box 7. The unit of the numeral indicating the dimension in the drawing is mm. Molding resin material of Example 1 Molding resin: polypropylene, type of negative expansion coefficient material: β-eucryptite, addition amount of negative expansion coefficient material: 30.0 wt%-Example 2-In Example 2, the following molding was performed. A molded article shown in FIGS. 1 and 3 was produced by injection molding using a resin material. Molding temperature is 26
0 ° C.

Molding resin material of Example 2 Molding resin: polypropylene, type of negative expansion coefficient material: aluminum titanate, addition amount of negative expansion coefficient material: 50.0 wt%-Example 3-In Example 3, Using the molding resin material, molded articles shown in FIGS. 1 and 3 were produced by injection molding. Molding temperature is 26
0 ° C.

Molding resin material of Example 3 Molding resin: nylon, type of negative expansion coefficient material: β-eucryptite,
Addition amount of negative expansion coefficient material: 10.0 wt%-Example 4 In Example 4, the following molded resin materials were used, and molded articles shown in FIGS. 1 and 3 were produced by injection molding. Molding temperature is 26
0 ° C.

Molding resin material of Example 4 Molding resin: nylon, type of negative expansion coefficient material: aluminum titanate,
Addition amount of negative expansion coefficient material: 25.0% by weight-Example 5 In Example 5, the following molded resin material was used, and molded articles shown in FIGS. 1 and 3 were produced by injection molding. Molding temperature is 28
0 ° C.

Molding resin material of Example 5 Molding resin: polybutylene terephthalate, type of negative expansion coefficient material: β-
Addition amount of eucryptite and negative expansion material: 20.0wt
%-Comparative Example 1-A molded article was produced in the same manner as in Example 1 except that the same molding resin material was used except that the negative expansion coefficient material was not added.

Comparative Example 2 A molded product was produced in the same manner as in Example 3 except that the same molding resin material was used except that the negative expansion coefficient material was not added. Comparative Example 3 A molded article was produced in the same manner as in Example 5, except that the same molding resin material was used except that the negative expansion coefficient material was not added.

With respect to the molded products obtained in the examples and comparative examples, the sink depth LA shown in FIG. 2 for the molded product 1 in FIG. 1 and the warpage amount shown in FIG. 4 for the molded product 8 in FIG. LB was measured respectively. The measurement results are as follows. Example 1 Sinking depth: 48 μm Warpage amount: 0.4 mm Example 2 Sinking depth: 65 μm Warpage amount: 0.5 mm Comparative Example 1 Sinking depth: 125 μm Warpage amount: 1.3 mm Example 3 Sinking depth: 47 μm Warp amount: 0.5 mm Example 4 Sink depth: 42 μm Warp amount: 0.4 mm Comparative Example 2 Sink depth: 89 μm Warp amount: 1.0 mm Example 5 Sink depth: 40 μm Warp amount: 0.3 mm Comparative example 3 sink depth: 75 μm warpage amount: 0.7 mm Comparing the measurement results of the example and the comparative example, it can be clearly understood that sink and warpage hardly occurred in the molded resin material of the present invention.

[0019]

According to the molding resin material of the present invention, since the shrinkage of the molding resin is absorbed by the expansion of the negative expansion coefficient material, sink and warp hardly occur, and the molding resin material itself is devised. Because it is an improvement measure that makes sinks and warpage less likely to occur, molding conditions are limited to a specific range and are not strict, without limiting the shape of the molded product and complicating the mold structure, and therefore, The present invention is very useful.

[Brief description of the drawings]

FIG. 1 is a perspective view showing the appearance of molded articles produced in Examples and Comparative Examples.

FIG. 2 is an explanatory view showing locations where sink marks are measured on the molded article of FIG. 1;

FIG. 3 is a perspective view showing the appearance of another molded article produced in the example and the comparative example.

FIG. 4 is an explanatory view showing locations where the warpage amount of the molded article in FIG. 3 is measured.

[Explanation of symbols]

 1 molded product 6 molded product LA sink mark depth LB warpage

──────────────────────────────────────────────────続 き Continuation of front page (58) Field surveyed (Int. Cl. ⁷ , DB name) C08L 1/00-101/16 C08K 3/00-13/08

Claims (2)

(57) [Claims] To 1. A molding resin made of a thermoplastic crystalline resin, formed by adding a material having a negative coefficient of thermal expansion injection molding
Molding resin material for shapes . 2. The molding according to claim 1, wherein the amount of the material having a negative coefficient of thermal expansion is: [weight of material having a negative coefficient of thermal expansion] ≦ 0.6 × [weight of molding resin]. Resin material.