JPH08302159A - Production of phenol resin molding material - Google Patents

Abstract

PURPOSE: To obtain a phenol resin molding material which gives an injection molded item having impact strength and static strengths well balanced at high level, greatly improves impact strength esp. in high-productivity injection molding, and greatly promotes the substitution for metals in the fields of automobiles and electric appliances. CONSTITUTION: A process for producing this phenol resin molding material is provided which comprises compounding a binder comprising 20-40wt.% dimethylene ether type resole resin and 5-15wt.% random novolak resin with 3-10wt.% carboxylated NBR. 40-60wt.% glass fibers, and a small amt. of a solvent and mixing the resulting compsn. under high-speed stirring to thereby remove the solvent and simultaneously granulate the compsn.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention provides a high resilience type phenolic resin, a novolac type phenolic resin, a carboxyl-modified NBR and a glass fiber to give a high impact strength even in injection molding, and to provide a metal for automobiles and electric appliances. The present invention relates to a method for producing a phenolic resin molding material having excellent impact strength, which is suitable for substitution from parts.

[0002]

2. Description of the Related Art Phenolic resin molding materials are excellent in heat resistance, dimensional stability, moldability and the like, and have a long history of use in core industrial fields such as automobiles, electricity and electronics. Particularly in recent years, since replacement of metal parts with high-strength phenol resin molded products reinforced with glass fibers enables a significant cost reduction, active alternative studies are being conducted. However, in the extreme, thermosetting resin molding materials such as phenolic resins have the drawback of weak impact strength, such as cracking when dropped, which is a factor that has hindered the expansion of application to metal parts. Can be said. Many attempts have been made to ameliorate this drawback. For example, as disclosed in Japanese Patent Laid-Open No. 3-137151, a resol resin, a novolac resin, a modified NBR and a glass fiber are mixed to solve this problem. is there. However, even in the case of the phenol resin molding material disclosed in this publication, the glass fiber is often ruptured by the shearing force at the time of kneading in the cylinder portion in injection molding, and it is often impossible to obtain sufficiently satisfactory impact resistance. On the other hand, it is also a fact that injection molding with high productivity is becoming the main molding method in order to reduce the product cost.

[0003]

DISCLOSURE OF THE INVENTION The method for producing a phenolic resin molding material having excellent impact strength according to the present invention is such that glass fiber is left in the obtained molding material for a long time, so that high impact is achieved even in injection molding. In addition, the molding material in which the kneading degree is kept low and the glass fiber is left for a long time has the drawback that the static strength such as bending strength becomes low, but in the cylinder part in injection molding, It was found that the drawback can be compensated to some extent by adjusting the kneading action. In particular, it was found that impact strength and static strength were well balanced in injection molding, and the present invention was completed.

[0004]

According to the present invention, a carboxyl-modified NBR, glass fiber and a solvent are added as essential components to a binder consisting of a resol type phenol resin (resole resin) and a novolac type phenol resin (novolac resin). Then, the present invention relates to a method for producing a phenol resin molding material having excellent impact strength, which comprises granulating by removing a solvent while mixing with high speed stirring.

The resole resin used in the present invention is preferably a dimethylene ether type resin having a number average molecular weight of 500.
It is preferably from 900 to 900. Next, the novolac resin is not particularly limited, but a random novolac resin is preferable, and one having a number average molecular weight of 800 to 1200 is preferable. Therefore, it is preferable to use these resins in combination. The reason for this is that one is stable productivity when producing by high-speed stirring and mixing, and the other is the effect of improving the toughness of the cured product. For example, if you use only resol resin as the phenol resin, you cannot expect a significant improvement in impact strength,
It is difficult to control the flow when forming a molding material, which makes stable production difficult. On the other hand, the combined use of the novolac resin and the resol resin can significantly improve the impact strength. This is because when the novolac resin and the resole resin are used in combination, the cured product is not an aggregate of the micro-cured products, but is considered to be one uniform cured product by the reaction of both.

The resol resin and the novolac resin can be used in a combined ratio of about 60/40 to 90/10, and 70/30 to 80/20 is effective in terms of impact strength and is preferable. is there. When the resol ratio is increased, the impact strength is lowered, and when the novolac ratio is more than this range, the curability is deteriorated.

Next, the carboxyl-modified NBR is not particularly limited, but can be preferably used as long as it has a SP value of 9 to 10 and is solid at room temperature. According to the literature, the SP values of polybutadiene and nitrile rubber are 8.5 and 9.5, respectively, so that the butadiene and acrylonitrile bond ratios may be adjusted so that the SP values are 9 to 10. Further, it is known that the carboxyl group reacts with the methylol group of the resole resin, and has an effect of improving the dispersion state of the carboxyl-modified NBR mixed with the resole resin and the novolac resin and reacting (micro phase separation structure), The presence of carboxyl groups is significant. The proportion of carboxyl groups in the carboxyl-modified NBR is preferably 2 to 10 mol%.
If it is less than 2 mol%, the effect of the carboxyl group is small and 10
If it exceeds mol%, the flow characteristics of the molding material will deteriorate. The molecular weight of the carboxyl-modified NBR is not particularly limited, but it is preferably solid at room temperature. If the compounding amount is less than 3% by weight with respect to the entire molding material, the effect of improving the impact strength is small, and if it is 10% by weight or more, the heat resistance tends to decrease, so 3-10% by weight is preferable.

It is preferable to use only glass fibers as the inorganic filler. This is because using a fibrous inorganic filler having a high aspect ratio such as glass fiber is more effective in improving impact strength. The compounding amount is 40 with respect to the entire molding material.
The range of ˜60% by weight is preferred. If it is less than 40% by weight, the impact strength will decrease, and if it exceeds 60% by weight, it will be difficult to make it into a molding material. The glass fiber length of 1 to 3 mm is advantageous in terms of the impact strength improving effect and the ease of materialization. Furthermore, if a silane coupling agent such as aminosilane or epoxysilane is used to improve the adhesion between the filler and the resin, it is effective in improving strength and heat resistance.

Next, the method for producing the phenolic resin molding material according to the present invention will be described by way of example. A fluid type high speed agitator is a typical device for high speed agitation and mixing. This device has, for example, four stirring blades in a mixing tank, a side temperature is equipped with a jacket type temperature control device through which water and steam pass, a resin temperature measuring sensor is provided inside, and an exhaust pipe is provided above. It is provided. First, such a mixer is charged with the phenol resin composition and the necessary amount of the curing aid, the release agent, and the colorant described above, and the mixture is stirred and mixed for several tens of seconds, and an appropriate amount and a small amount of a low boiling solvent such as methanol. Add the coupling agent. The total amount of the solvent and the like added is preferably 2 to 5%. The role of the solvent is to facilitate particle formation. When it is less than 2%, the phenol resin as a binder and the glass fiber do not sufficiently adhere to each other when the material is made, and the glass fiber is defibrated and pills are generated. Cheap. On the other hand, if it is 5% or more, the particles may adhere to each other and the particles may become huge. In either case, the particle shape cannot be injection-molded.
Subsequently, regarding particle formation, while maintaining the temperature in the tank at 60 to 100 ° C., high speed (500 to 3000 rp) for 10 to 30 minutes.
While stirring and mixing in m), the solvent and water are removed from the exhaust pipe, and drying and particle formation can be performed at the same time. In the initial stage of stirring, heating is carried out to cause a polycondensation reaction of the phenol resin, and cooling is carried out when the resin temperature rises due to mutual friction heat and reaction heat between the phenol resin and glass fiber due to heating and stirring. That is, the reaction does not proceed at low temperature, and the reaction proceeds too much at high temperature and the phenol resin gels. If the stirring speed is too slow, the granulation of the phenolic resin molding material is delayed, and a uniform granular product cannot be obtained.
If it is too fast, the glass fiber may be cut, which is not preferable.

As a result of using the above-mentioned manufacturing method, the phenol resin molding material is in the form of particles having a diameter of 2 to 10 mm, and a molding material in which impact strength and static strength are well balanced in injection molding can be obtained. .

[0011]

The present invention will be described below with reference to examples. Table 1 shows the formulations and characteristics of the examples and comparative examples.

In Table 1, the numerical values of the composition show% by weight.
The properties were measured according to JIS K 6911.

[Table 1]

(Note 1) Resol type phenol resin: dimethylene ether type phenol resin (number average molecular weight 70
0) Novolac type phenol resin: Random novolac type phenol resin (number average molecular weight 1000) (Note 2) Glass fiber: Fiber length 1.5 mm, fiber diameter 10 μ
m (Note 3) Carboxyl-modified NBR: Carboxyl modification rate 4 mol% (Note 4) The test piece was set to a mold temperature of 180 ° C and a cylinder tip temperature of 80 ° C using an injection molding machine of 100 tons, and the curing time was 60 seconds. It was molded in. Furthermore, the test piece is heated to 180 ° C.
Heat aged for 8 hours. (Note 5) The injection moldability was 100 t using an injection molding machine. ◯: There is no variation in measurement and good continuous moldability. Δ: Continuous molding is possible, but there is variation in measurement. (Note 6) The glass fiber length in the material was measured by ashing the molding material.

[0014]

As is clear from the above Examples and Comparative Examples, the phenolic resin molding material of the present invention has a high balance of impact strength and static strength in injection molding. In particular, the impact strength in injection molding, which has high productivity, has been greatly improved, and therefore, it will greatly promote the substitution of metal in the fields of automobiles and electric machines.

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Claims (4)

[Claims] 1. A binder consisting of a resol type phenolic resin and a novolac type phenolic resin is mixed with carboxyl-modified NBR (acrylonitrile butadiene rubber), glass fiber and a solvent as essential components, and then the solvent is removed by high speed stirring and mixing. A method for producing a phenolic resin molding material having excellent impact strength, which is characterized by granulating. 2. A dimethylene ether type resole resin 20 as a resole type phenol resin for the whole molding material.
The method for producing a phenolic resin molding material according to claim 1, wherein the phenolic resin molding material comprises 40 to 40% by weight, a random novolac resin as a novolac phenolic resin 5 to 15% by weight, a carboxyl-modified NBR 3 to 10% by weight, and a glass fiber 40 to 60% by weight. . 3. The method for producing a phenol resin molding material according to claim 1, wherein the glass fiber has a fiber length of 1 to 3 mm. 4. The stirring and mixing is heating stirring.
Or the method for producing the phenolic resin molding material according to 3 above.