JPS61213225A - Thermosetting resin molding material - Google Patents

Abstract

PURPOSE:To obtain the titled material having low molding shrinkage and excellent surface smoothness and dimensional stability, and useful for electrical apparatuses, etc., by mixing a thermosetting resin homogeneously with specific carbon fibers and an inorganic filler. CONSTITUTION:The objective material can be produced by using (A) a thermosetting resin, (B) a carbon fiber having a fiber length of 0.02-1mm, and (C) an inorganic filler having particle diameter of <=50mum as main components, and mixing the components homogeneously or almost homogeneously. The amounts of the components B and C in the material are 35-65wt% and 3-35wt%, respectively. Preferably, the component A is epoxy resin or polyester resin and the component C is selected from fine powder of silica, kaolin, etc., and lamellar inorganic compounds such as montmorillonite, etc.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention is directed to the excellent mechanical properties, electrical properties, and
It is a composite molding material that is widely used in various fields such as electrical equipment, vehicle and aircraft parts, marine equipment parts, sports and leisure goods, etc., taking advantage of its properties such as dimensional stability, heat resistance, and chemical resistance. Specifically, the main materials are thermosetting resin, carbon fiber, and inorganic filler, and these are uniformly or approximately uniformly distributed.
This invention relates to a carbon fiber-reinforced thermosetting resin molding material.

<Prior art> Composite molding materials of this type that have been in practical use for a long time include: (1) The main materials are glass fiber, unsaturated polyester resin, inorganic filler, and thermoplastic resin powder. A molding material made by uniformly or almost uniformly mixing carbon fiber and phenolic resin,
A molding material made by uniformly or almost uniformly mixing these, (3) Carbon fiber with a fiber length of 6B to 25 mm, a thermosetting resin, and a main material, a molding material made of these in bulk or sheet form, etc. It has been known.

<Problems to be Solved by the Invention> However, in the case of using each of the above-mentioned conventional molding materials, molded products made of them each had the following drawbacks.

That is, in the case of using the molding material (1), the upper limit content of glass fiber is not only limited to 35% (weight percent) or less in order to maintain fluidity during molding, but also
Thermoplastic resin powder such as polyethylene powder is added to improve molding shrinkage and reduce curing shrinkage, so molded product dimensions may vary due to differences in molding conditions such as temperature and pressure. tends to occur.

Furthermore, the orientation of the glass fibers varies depending on the flow condition of the material during molding, and this causes a difference in the amount of molding shrinkage in different directions, resulting in the disadvantage that the shaped product is easily distorted.

(In the case of 210 molding material, although the molding shrinkage rate is small, it tends to generate moisture during curing, and the influence of this moisture causes variations in the dimensions of the molded product, making it unsuitable as a molding material for complex shapes and precision products. However, the drawback is that the scope of use is very narrow.

(For example, when using the molding material No. 31, the fiber length is 6 mm.
Molding materials containing T-40 to T-60 carbon fibers of 25 mm to 25 mm have very small molding shrinkage, but on the other hand,
Because the fiber length is large, the orientation of the fibers due to fluidity during molding causes directional molding shrinkage, which not only deforms the molded product, but also results in a FiL shaped surface and lacks surface smoothness. In addition, it is impossible to mold small objects with thin walls, and it is also difficult to obtain molded products with high dimensional accuracy.

As mentioned above, all of the molding materials that have been in practical use have been in the spotlight in recent years, and there are great expectations for their progress in the electronic industry, automation equipment fields, and optical-related fields. It is not suitable for molded products that have high requirements for dimensional accuracy and surface smoothness, such as various devices and precision parts used in manufacturing, etc., and its range of applications is therefore narrow.

Means for solving the problems> In view of the above-mentioned circumstances, the composition ratio of the main materials and the
Through intensive research into the selection of the properties of these materials, the objective is to provide a thermosetting resin molding material that can significantly improve the dimensional stability and surface smoothness of molded products, and this objective has been achieved. In order to achieve this, the thermosetting resin molding material according to the present invention has carbon fibers of 0.02 mm to 1 m! that should be mixed uniformly or approximately uniformly into the thermosetting resin! Il
fiber length of 50%, and as an inorganic filler,
In addition to using particles with a particle size of 4 m or less, the blending ratio of these carbon fibers and inorganic fillers is 35 to 6 in weight percentage.
It is notable that the values are 5% and 35%.

The basic technical idea of the uninvented molding material having the above-mentioned characteristics is that by increasing the carbon fiber content to a very high level, a thermosetting resin is formed between the fibers during heat and pressure molding. Is it possible to reduce the mold shrinkage of a molded product by filling it with an inorganic filler, and to reduce fluidity due to high carbon fiber content? It is suppressed by mixing inorganic fillers, and gives appropriate viscosity to optimize fluidity.
By using carbon fibers with a fiber length of 0.02 to 1 mm, the shrinkage rate can be reduced by 7 mm, while the directionality of mold shrinkage due to fiber orientation can be eliminated, and the particle size can be reduced to 50 mm.
．． By using an inorganic filler of less than 100 mL, it is possible to maintain appropriate fluidity during molding and to make the surface of the molded product smooth. The details will be explained in detail.

That is, carbon fiber has a thermal expansion coefficient of -0.1XIO in PM ratio.
/? C, pitch thread is extremely small, 5X1010C,
High content in materials such as thermosetting resins that require high molding temperatures is effective in suppressing molding shrinkage.

However, thermosetting resins shrink by about 1 to 4 percent during curing, regardless of their blending ratio.
This curing shrinkage generates internal stress between the carbon fibers and the resin, causing deformation of the molded product and a decrease in the strength of the molded product due to small clutches occurring in the resin layer.

In view of this point, the present invention has developed a resin (30-100XIO/'
The coefficient of thermal expansion is smaller than C) (5~8X10/'
0 By adding an inorganic filler, the curing shrinkage of the thermosetting resin is reduced, and the generation of internal stress between the carbon fiber and the resin is alleviated, thereby reducing molding shrinkage without causing deformation or strength reduction of the molded product. can be improved.

Furthermore, the average fiber length of the carbon fibers used in the present invention is 0.0
The best value is between 2 mm and 1 mm.

In other words, when carbon fibers with an average fiber length of 1 mm or more are used, the fibers are aligned in one direction due to the flow during molding, and this combination of fibers causes directional shrinkage of the molded product, causing deformation. . In addition, the average fiber length is 0.02
If carbon fibers with a diameter of 2 mm or less are used, the effect of suppressing molding shrinkage will be low.

Next, the inorganic fillers used in the invention include fine powders such as silica, kaolin, clay, calcium carbonate, magnesium carbonate, dolomite, calcium hydroxide, wollastonite, palicum sulfate, and montmorillonite. , clays such as hectorite, verculite, hydrated halloysite, and birophyllite, sulfides such as thallium sulfide, phosphates such as zirconium hydrogen phosphate, and halides such as ferric oxychloride. In particular, layered inorganic compounds that have excellent affinity for resins, maintain fluidity during molding, and can improve the strength of molded products are preferred.

In addition, as an inorganic filler, the average particle size is 0.02/lA
m to 50. -Am is the most effective.

In other words, if a material having an average particle size of 50 μm or more is used, the fluidity during molding will be reduced and the moldability will be adversely affected, and the surface of the molded product will become rough and lack surface smoothness.

In view of this, it is preferable that the inorganic filler has a smaller average particle diameter, and the smaller the particle diameter, the greater the substantial surface area, and therefore the smaller the content.

Furthermore, the content of carbon fiber is 35% by weight.
65% to 65%, preferably 40% or more6
Less than 5% are a.

If the carbon fiber content exceeds 65%, the fluidity within the mold during molding will decrease, making it particularly difficult to mold products with complex shapes, and if it is less than 35%, molding shrinkage will occur. The ratio is not as small as expected, and the method cannot be applied to molding precision parts.

<Effects of the invention> As detailed above, the uninvented problem lies in the selection of the properties of two main materials such as the fiber length of carbon fiber and the particle size of inorganic filler, and the blending ratio of three main materials including thermosetting resin. By selecting , it is possible to suppress the generation of internal stress due to the contraction of the resin during molding and curing, and to reduce the molding shrinkage rate of the molded product to less than 0.2% relative to the mold dimensions. There is almost no reduction in strength due to product deformation or cracking, and the surface is excellent in smoothness. In addition, the coefficient of thermal expansion of the molded product is approximately 1.3 x 10.10 (approximately 1.3 x 10.10), which is extremely small compared to ordinary plastics, and the dimensional change due to temperature changes is also very small, which improves the surface accuracy and dimensional stability of the molded product surface. It also has excellent effects, and together with improved dimensional accuracy during molding, it can be fully applied to small thin material products and precision molded parts.

Therefore, it is possible to replace conventional metal products such as aluminum die-casting with molded products that can be mass-produced, making it a major contribution to the industry in that it can significantly reduce production costs and significantly reduce product weight. As a result, we have been able to provide a molding material with high quality.

<Example> Examples of the present invention will be described in detail below.

The cooled and pulverized molding material was heated by transfer molding at a molding pressure of 600 WaR and a mold temperature of 1606 C for 5 minutes to obtain a molded product.

Example 2゜The above materials were uniformly mixed while being heated, then cooled and pulverized.The molding material was then injected into a t1 injection molding machine at an injection pressure of 1500.
WcI? The mixture was injected into a mold at 210°C and heated for 60 seconds to obtain a molded product.

Example 3 A molding material obtained by uniformly mixing the above-mentioned materials while heating them was molded at a molding pressure of 600'lF/' (
! ffi'' into a 1609C mold and heated for 5 minutes to obtain a molded product.

Example 3: A molding material obtained by homogeneously mixing the above-mentioned materials while heating them. Next, conventional examples to be compared with the above-mentioned uninvented examples will be described in detail.

Conventional Example 1゜A molding material obtained by uniformly mixing each of the above materials was used as Example 3. A molded product was obtained by molding under the same conditions as .

Conventional Example 2゜10F-8i Heating method After uniformly mixing, the cooled and pulverized molding material was heated by transfer molding at a pressure of 600Q+7am'' and a mold temperature of 160°C for 5 minutes to produce a molded product. I got it.

Conventional Example 3゜Commercially available dry unsaturated polyester resin molding material (including glass fiber, average fiber length 3mmt-201)
1 at an injection pressure of 1500re/m" depending on the injection molding method.
The mixture was injected into a mold at 70'C and heated for 50 seconds to obtain a molded product.

Example 1 of the present invention listed above. to 4. and conventional example 1,
, 2. , 3. The following table shows the evaluation of molded products by
As shown in FIGS. 1 and 2.

The measured dimensions of the molded product are t-'4° with respect to the flow direction of the molding material and the direction perpendicular thereto. It is measured to 0mm, and the molding shrinkage rate (percentage) relative to the mold dimensions.
The results of the comparison are shown below.

As is clear from the above comparative evaluation of molded products, the molded products made of the uninvented molding material have very small mold shrinkage in absolute terms, and the mold shrinkage rates in the three-dimensional directions such as A and B %H. The difference is very small compared to the conventional example. Incidentally, the difference in molding shrinkage rate of the molded product of Conventional Example 1 is A:B:
Whereas in H it is 1: 17.5: 20.5,
In the molded article according to the embodiment of the present invention, A:B:H and l:L
33:1.33. This technology has extremely high molding dimensional accuracy, which is sufficient to support its application to precision parts. It is also proof that you can grow old by achieving cost-effectiveness.

The montmorillonite composite described in Examples & in the unspecified section is one of the layered minerals in which a hardening accelerator is adsorbed between the layers, and is a type of hydrous aluminum gaitate called Altos *4.
s1θs ah nHso, another name is bentonite.

[Brief explanation of the drawing]

FIGS. 1 and 2 are a plan view and a side view showing the shape of a molded product (mold) used for evaluation of molding materials.

Claims (5)

[Claims] (1) A molding material whose main materials are a thermosetting resin, carbon fibers, and inorganic filler, and which are uniformly or almost uniformly mixed, wherein the carbon fibers have a thickness of 0.02 mm to 1 mm.
The carbon fibers with a fiber length of 50 mm are used, and the inorganic filler has a particle size of 50 mm or less, and the blending ratio of these carbon fibers and the inorganic filler is 35 to 65 percent and 3 to 35 percent by weight. Thermosetting resin molding material. (2) The thermosetting resin molding material according to claim (1), wherein the thermosetting resin is an epoxy resin. (3) The thermosetting resin molding material according to claim (1), wherein the thermosetting resin is a polyester resin. (4) The inorganic filler is selected from fine powders of silica, kaolin, clay, calcium carbonate, magnesium carbonate, dolomite, calcium hydroxide, wollastonite, barium sulfate, etc. ) The thermosetting resin molding material described in item 1. (5) The inorganic filler may be clays such as montmorillonite, hectorite, vermiculite, hydrated halloysite, birophyllite, sulfides such as thallium sulfide, phosphates such as zirconium hydrogen phosphate, ferric oxychloride, etc. The thermosetting resin molding material according to claim (1), which is selected from a group of layered inorganic compounds represented by halides.