JP2003327788A - Epoxy resin composition and its molded product - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an epoxy resin composition which shows an excellent moldability and dimensional stability and a high cured product specific gravity and reduces temporal deterioration in appearance caused by moisture, and a molded product obtained from this composition. <P>SOLUTION: The epoxy resin composition essentially comprises (A) an epoxy resin, (B) a phenol resin, (C) a curing accelerator and (D) tungsten carbide and shows a cured product specific gravity of ≥5. Here, 70-98 wt.% tungsten carbide (D) is contained against the total weight of the resin composition. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an epoxy resin composition having excellent moldability and a molded article.

[0002]

2. Description of the Related Art In ink jet printer heads and high-speed rotating parts made of resin molded products, the weight of the parts themselves is lighter than that of metal parts, so that the parts do not operate smoothly due to inertia and centrifugal force. , It is a very important issue in terms of component performance.

[0003]

To increase the specific gravity of parts, there is a method of polishing a metal ingot.
There are problems that complicated processing is difficult and takes man-hours, mass production is impossible, and the price is high. There is also a method of insert-molding a metal part, but similarly, complicated processing cannot be performed, and there is a problem that man-hours are required. Furthermore, if a molded product made of a thermoplastic resin is created, a large number of complicated products can be produced, but it has poor heat resistance and solvent resistance, and if metal powder is used as a filler to achieve high specific gravity, There was a problem that the appearance changed with time due to humidity.

The present invention, in order to overcome the above drawbacks,
The purpose is to increase the specific gravity by using a thermosetting resin molded product having excellent productivity.

[0005]

Means for Solving the Problems As a result of intensive studies to achieve the above object, the present inventors have found that the composition described below using epoxy resin, phenol resin, curing accelerator and tungsten carbide as filler. By using the resin composition of No. 3, a cured product has a high specific gravity, a resin composition having excellent moldability and dimensional stability is obtained, and it has been found that the above objects can be achieved, and the present invention has been completed. .

That is, the present invention relates to (A) epoxy resin,
(B) Phenolic resin, (C) Curing accelerator and (D)
Tungsten carbide is an essential component, and the above (D) tungsten carbide is added to the entire resin composition by 70%.
The epoxy resin composition is characterized in that it is contained at a ratio of up to 98% by weight and has a specific gravity of the cured product of 5 or more. Also,
A molded article is formed by molding with this epoxy resin composition.

The present invention will be described in detail below.

Examples of the (A) epoxy resin used in the present invention include o-cresol novolac type epoxy resin, biphenyl type epoxy resin, dicyclopentadiene type epoxy resin and other generally known epoxy resins.
There is no particular limitation as long as it has two or more functional groups in the molecule, but considering the dimensional stability of the molded product, the epoxy resin represented by the following Chemical formula 3 is preferable.

[0009]

[Chemical 3] (However, in the formula, R represents a hydrogen atom or an alkyl group, and n represents an integer of 1 or more.) The (B) phenol resin used as the curing agent in the present invention includes the epoxy group of the epoxy resin of (A) above. There is no particular limitation as long as it has two or more phenolic hydroxyl groups capable of reacting with. As a specific compound, for example,

[Chemical 4] (However, in the formula, n represents an integer of 0 or more)

[Chemical 5] (However, in the formula, n represents an integer of 0 or more)

[Chemical 6] (However, in the formula, n represents an integer of 0 or more)

[Chemical 7] (However, in the formula, n represents an integer of 0 or more) and the like. These resins can be used alone or in combination of two or more kinds.

The mixing ratio of the phenol resin is such that the equivalent ratio [(a) / (b)] between the epoxy group (a) of the epoxy resin and the phenolic hydroxyl group (b) of the phenol resin is 0.5 to 5. It is desirable to be within the range. If the equivalent ratio is less than 0.5 or exceeds 5, the curing characteristics and the molding workability are deteriorated, which is not preferable in any case. Therefore, it is preferable to limit it within the above range.

As the (C) curing accelerator used in the present invention, phosphorus-based curing accelerator, imidazole-based curing accelerator, D
Examples thereof include BU-based curing accelerators, and the urea-based curing accelerator represented by the above formula 8 is preferable from the viewpoint of the stability of the viscosity of the molten resin in the syringe.

[0012]

[Chemical 8] Further, these curing accelerators can be used alone or in combination of two or more.

The (D) tungsten carbide used as a filler in the present invention preferably has a maximum particle size of 500 μm or less and an average particle size of 3 to 100 μm. The presence of fillers with a maximum particle size exceeding 500 μm,
If the average particle diameter exceeds 100 μm, the precision molded product is inferior in moldability and is not suitable for practical use. The content of tungsten carbide is preferably 70 to 98% by weight with respect to the entire resin composition. If the blending ratio is less than 70% by weight, the specific gravity of the cured product is small, which is not suitable for the purpose of the present invention. On the other hand, if it exceeds 98% by weight, the dryness becomes large and the moldability is poor and it is not suitable for practical use.

As the silicon oxide (E) used as a filler in the present invention, crystalline silica, fused silica, cristobalite and the like can be used regardless of the crystal structure, but in the case of aiming for high filling, spherical fused silica. Powder is preferred. Also, for the above-mentioned reason, it is preferable that the total content of (D) tungsten carbide and (E) silicon oxide be 70 to 98% by weight based on the total resin composition.

The epoxy resin composition of the present invention contains the above-mentioned specific epoxy resin, phenolic resin, curing accelerator and tungsten carbide as essential components, but may be used as long as it does not defeat the purpose of the present invention. For example, release agents such as natural waxes and synthetic waxes, flame retardants such as antimony trioxide and brominated epoxy resins, colorants such as carbon black, rubber-based and silicone-based low-stress imparting agents, amine-modified and A coupling agent such as an epoxy-modified silicone oil can be appropriately added and blended. The epoxy resin composition of the present invention can be diluted with a solvent and used. As the solvent,
Examples thereof include non-polar or polar organic solvents, non-polar or polar inorganic solvents, and these can be used alone or in combination of two or more.

As a general method for preparing the epoxy resin composition of the present invention as a molding material, the above-mentioned epoxy resin, phenolic resin, curing accelerator, tungsten carbide and other components are blended and mixed with a mixer or the like. After sufficiently homogeneously mixing, a melt mixing process using a hot roll or a mixing process using a kneader or the like is further performed, followed by cooling and solidification, and crushing to an appropriate size to obtain a molding material. The use of the molding material thus obtained is not particularly limited.

The molded product of the present invention can be easily manufactured by molding using the molding material obtained as described above. The most common method of molding is
Although there are injection molding and transfer molding methods, compression molding and the like are also possible. When the resin is cured by heating after molding, it is desirable that the temperature be 150 ° C. or higher.

[0018]

[Function] The epoxy resin composition and molded article of the present invention are
By using a phenol resin curing agent and a tungsten carbide filler as the epoxy resin molding composition components, the appearance of the molded product does not change over time due to humidity, the specific gravity of the cured product is high, and the moldability and dimensions are high. A resin composition having excellent stability can be obtained.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION Next, the present invention will be specifically described with reference to Examples, but the present invention is not limited to these Examples. Moreover, in the following Examples and Comparative Examples, "%" means "% by weight".

Example 1 Epoxy resin shown in Chemical formula 3, EPPN-502H (manufactured by Nippon Kayaku Co., Ltd., 2.87%), phenol resin MEH-1085 shown in Chemical formula 4 (manufactured by Meiwa Kasei Co., Ltd., Trade name) 0.67%, M of the phenolic resin shown in Chemical formula 7 above
EH-7500 (Maywa Chemical Co., Ltd., trade name) 1.03%,
0.08% of the urea-based curing accelerator shown in Chemical formula 8 and AER-8 of tetrabromobisphenol A type epoxy resin
028 (manufactured by Asahi Ciba Co., Ltd.) 0.59%, 71.60% tungsten carbide powder having a maximum particle size of 200 μm and an average particle size of 15 μm, spherical particles having a maximum particle size of 75 μm or less and an average particle size of 25 μm Fused silica powder 21.4
8% and carnauba wax 0.12%, carbon black 0.12%, antimony trioxide 0.98%, and coupling agent (γ-glycidylepoxysilane) and silicone oil (1cs dimethylpolysiloxane) 2: 1. 0.45% of the mixture was mixed at room temperature, melt-kneaded at 90 to 110 ° C., and then cooled and ground to produce a molding material.

Example 2 EOCM-10, a cresol novolac type epoxy resin
20-55 (Nippon Kayaku Co., Ltd., trade name) 1.86%, phenolic resin MEH-1085 (Meiwa Kasei Co., Ltd., trade name) 0.48%, shown in Chemical Formula 7 above. Phenol resin MEH-7500 (manufactured by Meiwa Kasei Co., Ltd., trade name) 0.66%, urea-based curing accelerator 0.05% shown in Chemical formula 8 above, tetrabromobisphenol A type epoxy resin AER-8028 (Asahi Ciba Company name, trade name) 0.3
8%, maximum particle size 200μm, average particle size 15μm
87.48% tungsten carbide powder, 7.98% spherical fused silica powder having a maximum particle size of 75 μm or less and an average particle size of 25 μm, and carnauba wax 0.08
%, Carpon black 0.08%, antimony trioxide 0.67%, and a mixture of a coupling agent (γ-glycidylepoxysilane) and silicone oil (1 cs dimethylpolysiloxane) in a ratio of 2: 1.
28% was mixed at room temperature, melt-kneaded at 90 to 110 ° C., and then cooled and ground to produce a molding material.

Example 3 1.27% of epoxy resin EPPN-502H (manufactured by Nippon Kayaku Co., Ltd., trade name) shown in Chemical formula 3, MEH-1085 of phenolic resin shown in Chemical formula 4 (manufactured by Meiwa Kasei Co., Ltd., Trade name) 0.31%, M of the phenolic resin shown in Chemical formula 7 above
EH-7500 (manufactured by Meiwa Kasei Co., Ltd., trade name) 0.46%,
0.03% of the urea-based curing accelerator shown in Chemical formula 8 and AER-8 of tetrabromobisphenol A type epoxy resin
028 (trade name, manufactured by Asahi Ciba Co., Ltd.) 0.26%, 96.92% tungsten carbide powder having a maximum particle diameter of 200 μm and an average particle diameter of 15 μm, carnauba wax 0.06
%, Carbon black 0.05%, antimony trioxide 0.44%, and a mixture of a coupling agent (γ-glycidylepoxysilane) and silicone oil (1 cs dimethylpolysiloxane) in a ratio of 2: 1.
20% was mixed at room temperature, melt-kneaded at 90 to 110 ° C., and then cooled and ground to produce a molding material.

Comparative Example 1 82.24% of fused silica powder having a maximum particle size of 75 μm or less and an average particle size of 25 μm, and the epoxy resin EPPN-502H shown in Chemical formula 3 (trade name, manufactured by Nippon Kayaku Co., Ltd.) 7. Three
8%, phenolic resin MEH-10 shown in Chemical Formula 4 above
85 (Meiwa Kasei Co., Ltd., trade name) 1.78%, phenolic resin MEH-7500 shown in Chemical Formula 7 (Meiwa Kasei Co., Ltd., trade name) 2.66%, phosphorus-based curing accelerator 0.13
%, A of tetrabromobisphenol A type epoxy resin
ER-8028 (Asahi Ciba, trade name) 1.51%, carnauba wax 0.30%, carpon black 0.32
%, Antimony trioxide 2.52%, and a mixture of a coupling agent (γ-glycidylepoxysilane) and silicone oil (1 cs dimethylpolysiloxane) in a ratio of 2: 1 1.16% at room temperature. , 9 more
After melt-kneading at 0 to 110 ° C., this was cooled and ground to produce a molding material.

Comparative Example 2 EPN-502H (manufactured by Nippon Kayaku Co., trade name) 2.36% of the epoxy resin shown in Chemical formula 3, MEH-1085 (made by Meiwa Kasei Co., Ltd., the phenolic resin shown in Chemical formula 4) Product name) 0.57%, M of the phenolic resin shown in Chemical formula 7 above
EH-7500 (manufactured by Meiwa Kasei Co., Ltd., trade name) 0.85%,
0.06% of the urea-based curing accelerator shown in Chemical formula 8 and AER-8 of tetrabromobisphenol A type epoxy resin
028 (trade name, manufactured by Asahi Ciba Co., Ltd.) 0.48%, iron powder 94.3 having a maximum particle diameter of 200 μm and an average particle diameter of 20 μm.
1%, carnauba wax 0.10%, carbon black 0.10%, antimony trioxide 0.81%, and coupling agent (γ-glycidylepoxysilane) and silicone oil (1cs dimethylpolysiloxane) 2: 2.
0.37% of the mixture mixed at a ratio of 1 is mixed at room temperature,
After further melt-kneading at 90 to 110 ° C., this was cooled and ground to produce a molding material.

Comparative Example 3 94.92% of copper powder having a maximum particle size of 200 μm or less and an average particle size of 25 μm, EP of epoxy resin shown in Chemical formula 3
PN-502H (Nippon Kayaku Co., Ltd., trade name) 2.10%,
MEH-1085, a phenolic resin shown in Chemical Formula 4 above.
(Meiwa Kasei Co., Ltd., trade name) 0.50%, phenolic resin MEH-7500 shown in Chemical formula 7 (Meiwa Kasei Co., Ltd.,
(Trade name) 0.76%, urea-based curing accelerator 0.06% shown in Chemical formula 8 above, and tetrabromobisphenol A type epoxy resin AER-8028 (manufactured by Asahi Ciba, trade name)
0.43%, carnauba wax 0.09%, carbon black 0.09%, antimony trioxide 0.72%, and coupling agent (γ-glycidylepoxysilane) and silicone oil (1cs dimethylpolysiloxane).
0.33% of the mixture prepared by mixing 2: 1 at room temperature was mixed at room temperature, melt-kneaded at 90 to 110 ° C., and then cooled and pulverized to produce a molding material.

Using the molding materials obtained in Examples 1 to 3 and Comparative Examples 1 to 3, various tests were conducted on the curability at 140 ° C. and 175 ° C., the specific gravity of the cured product, and the time until appearance failure when absorbing moisture. The results are shown in Table 1. Further, in order to compare the time for maintaining a molten state having a low viscosity at a molding temperature of 175 ° C. or lower, the time dependence of the viscosity at 140 ° C. is shown in FIG.
Shown in.

[0027]

[Table 1] * 1: Time when a certain amount of molding material was spread in a circle with a diameter of 4 to 5 cm on a hot plate kept at a constant temperature and kneaded at a constant speed until the sample thickened and finally became tenacious. Was measured.

* 2: A test piece was placed in a constant temperature / humidity bath of 85 ° C./85%, and the time when the appearance was obviously changed was measured visually.

[0029]

As is clear from the above description and Table 1 and FIG. 1, the epoxy resin composition and the molded product of the present invention have a high specific gravity of the cured product and can reduce the appearance defect due to humidity. In addition, by selecting a specific curing accelerator, it is possible to maintain a low melt viscosity below that temperature while maintaining the curing characteristics at the molding temperature, which makes it possible to fill a large amount of filler. A resin composition having excellent moldability and dimensional stability can be obtained.

[Brief description of drawings]

FIG. 1 is a graph showing a comparison of a low viscosity molten state maintaining time at 140 ° C. between Example 1 and Comparative Example 1.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) C08K 5/21 C08K 5/21 C08L 61/00 C08L 61/00 F term (reference) 4F071 AA41 AA42 AB11 AB26 AE17 BA01 BB05 4J002 CC04X CD00W CE00X DB017 DJ018 ET016 FD018 FD14X FD156 FD157 GM00 4J036 AC02 AF06 AF08 DB05 DC25 FA02 FA06 FB06 FB07 FB08 KA05 KA06

Claims (5)

[Claims] 1. An epoxy resin (A), a phenol resin (B), a curing accelerator (C) and a tungsten carbide (D) as essential components, and the (D) tungsten carbide to the entire resin composition. 70 to 98% by weight, and the specific gravity of the cured product is 5 or more. 2. The epoxy resin composition according to claim 1, wherein the epoxy resin (A) is represented by the following general formula. [Chemical 1] (However, in the formula, R represents a hydrogen atom or an alkyl group, and n represents an integer of 1 or more.) 3. The epoxy resin composition according to claim 1, wherein (C) the curing accelerator is a urea compound represented by the following general formula. [Chemical 2] 4. The epoxy resin composition according to claim 1, wherein (E) silicon oxide is used together as a filler. 5. A molded article, which is molded by the epoxy resin composition according to any one of claims 1 to 4.