JPH07309997A - Phenolic resin molding material - Google Patents

Abstract

PURPOSE:To obtain a phenolic resin transfer or compression molding material excellent in dimensional stability, curability, water resistance, etc., by incorporating predetermined amts. of a specific curing agent and a specific curing aid into a specific resin compsn. CONSTITUTION:A phenolic resin molding material comprises a resin compsn. comprising 20-50wt.% alkylbenzene-modified novolak phenolic resin, 25-55wt.%, high-ortho novolak phenolic resin and 25-55wt.% methylol resol phenolic resin; hexamethylenetetramine as a curing agent, the amt. of which is 18 to 24wt.% based on the novolak phenolic resins; and a curing aid (e.g. slaked lime), the amt. of which is 1 to 3wt.%, based on the phenolic resins.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a phenol resin molding material for transfer molding or compression molding, wherein the resin component is an alkylbenzene-modified phenol resin, a high ortho novolac type phenol resin and a methylol resole type phenol resin. It has the features of excellent dimensional stability at room temperature and very fast curing,
By highly filling an inorganic filler such as glass fiber, a phenol resin molding material particularly suitable for electric components for automobiles and home appliances is provided.

[0002]

2. Description of the Related Art Conventionally, phenol resin molding materials have excellent moldability and have been used in various industrial applications. In recent years, however, the environment in which they have been used has become harsh. Materials are no longer sufficient. In particular, in order to overcome the disadvantage that the dimensional change is large under high humidity or in water immersion, which is a weak point of the phenol resin so far, a method of using an alkylbenzene-modified phenol resin having a small amount of hydrophilic phenolic hydroxyl group. Is being done. For example, JP-A-2-4514
No. 7, gazette discloses alkylbenzene-modified phenolic resin,
A phenol resin molding material containing a novolac type phenol resin and a dimethylene ether resol type phenol resin as a resin component is disclosed. However, a molding material using an alkyl-modified phenol resin has a limitation in curability, and is not optimal for transfer or compression molding requiring curability, and has a drawback that the molding cycle becomes long.

[0003]

DISCLOSURE OF THE INVENTION The present inventors have conducted various studies to improve the drawbacks of molding materials using the above-mentioned alkylbenzene-modified phenolic resin, and as a result, alkylbenzene-modified phenolic resin, high ortho novolac type phenolic resin, The inventors have found that a phenolic resin molding material containing a methylol resol type phenolic resin as a resin component has a very small dimensional change under high humidity and has an excellent curability, and has completed the present invention.

[0004]

According to the present invention, a resin composition having an alkylbenzene-modified novolac type phenol resin 20 to 20 is used.
50 parts by weight, high ortho novolac type phenolic resin 2
5 to 55 parts by weight and 25 to 55 parts by weight of methylol resole type phenol resin, and hexamethylenetetramine as a curing agent is added to the novolac type phenol resin in an amount of 1
A phenol resin molding material for transfer molding or compression molding, characterized by containing 8 to 24% by weight and 1 to 3% by weight of a curing aid with respect to the phenol resin, wherein each resin is preferably Alkylbenzene-modified novolac type phenolic resin having an alkylbenzene modification rate of 30 to 60 mol% and a number average molecular weight of 400 to 600, ortho / para (O / P ratio) of 2.0 to
Novolak type phenolic resin having a number average molecular weight of 2.5 and 800 to 1100, and a number average molecular weight of 400 to 60
It is a phenol resin molding material which is a methylol resol type phenol resin of 0. Then, as a preferable composition, the above resin composition is added to the whole molding material in an amount of 25 to 3
The present invention relates to a phenol resin molding material containing 5% by weight and further containing 40% by weight or more of glass fiber as a reinforcing material.

The alkylbenzene-modified novolak resin is
The curability is inferior to that of the unmodified novolac type phenolic resin, and the crosslink density of the cured product is low, so there is a problem in using it alone as a molding material. Although it has been studied to use the unmodified novolac type phenolic resin in combination while taking advantage of the characteristics of the alkylbenzene-modified novolac type phenolic resin, sufficient curability has not been obtained. The present inventor has made diligent studies in order to improve the above-mentioned drawbacks, and as a result, it has become possible to obtain desired properties by using a resin composition having the compounding ratio described in the claims.

The alkylbenzene-modified novolak type phenol resin is usually obtained as follows. Xylene,
Alkylbenzene such as mesitylene and formaldehyde are reacted in the presence of strong acid such as sulfuric acid.
A formaldehyde condensate is obtained, and then a novolac type phenol resin or phenol is added and reacted, and further formaldehyde is added as necessary to continue the reaction. After the completion of the reaction, the product is neutralized to remove water and unreacted materials to obtain a final product.

In the present invention, the alkylbenzene modification rate of the alkylbenzene-modified novolak type phenolic resin is 3
0-60 mol% is preferable. When it is 30 mol% or less, the improvement in water resistance is small, and when it is 60 mol% or more, the curability is deteriorated, which is not practical. The number average molecular weight is preferably 400 to 600. If it is larger than 600, the fluidity of the molding material at the time of molding becomes small, and if it is smaller than 400, the amount of low-molecular components increases, the handling of the resin becomes difficult, and the strength of the molded product decreases.

The high ortho novolac type phenolic resin is usually obtained by reacting phenol and formaldehyde in the presence of a weakly acidic divalent metal salt catalyst such as zinc acetate and has an O / P ratio of 1.1 to 2.5. Is desirable in terms of curability. If the O / P ratio is less than 1.1, the desired sufficient curability cannot be obtained, and if it is 2.5 or more, the thermal stability when formed into a molding material is low, which is a practical problem. Further, in the present invention, the O / P ratio is more preferably 2.0 to 2.5 in order to improve the curability as much as possible. The number average molecular weight is preferably 800 to 1100. If it is more than 1100, the fluidity of the molding material at the time of molding becomes small, and if it is less than 800, the amount of low-molecular components increases and it becomes difficult to handle the resin, and the strength of the molded product decreases.

The methylol type phenol resin is obtained by reacting phenol and formaldehyde under a basic catalyst, and the number average molecular weight is preferably 400 to 600. If it is less than 400, the amount of low-molecular components becomes large, and it becomes difficult to handle the resin, and further the curability and the strength of the molded product deteriorate. Further, when it is 600 or more, the fluidity of the molding material becomes small.

Next, when a molding material is obtained from such a phenol resin composition, hexamethylenetetramine as a cross-linking agent is added to these resins in an amount of 18 to 24% by weight with respect to the high ortho novolac type phenol resin and the alkylbenzene-modified novolac type phenol resin. % Compound. If it is 24% by weight or more, the crosslink density becomes too high, and the excess hexamethylenetetramine increases the amount of water absorption of the molded product, resulting in a decrease in moisture resistance. If it is 18% by weight or less, sufficient curability cannot be obtained, and further, since the crosslink density is low, the chemical resistance and moisture resistance of the molded product are deteriorated.

Further, in order to further improve the curability, 1 to 3% by weight of a metal oxide, a metal hydroxide or the like is added to the phenol resin as a curing aid. If it is 1% by weight or less, the desired curability will not be sufficiently obtained, and if it is 3% by weight or more, the water resistance of the molded article will be reduced. In addition to these, organic or inorganic fillers, mold release agents, colorants, etc. can be added. The filler is preferably an inorganic material, particularly glass fiber, in order to exhibit the high strength, heat resistance and water resistance which are the features of the present invention. The glass fiber may be any ordinary commercially available glass chopped strand having a fiber length of 3 to 13 μm. As a preferred composition, by containing 25 to 35% by weight of the phenolic resin composition and 40% by weight or more of glass fiber with respect to the entire molding material, high strength, heat resistance and water resistance can be more sufficiently achieved. Can be demonstrated. Furthermore, in order to improve the adhesiveness at the interface between the resin and the filler, if a coupling agent such as aminosilane or epoxysilane is used,
It is more effective in improving water resistance and strength.

In order to obtain the phenol resin molding material of the present invention, after uniformly mixing the above raw materials, the mixture is heated and kneaded by a kneading machine such as a roll, a co-kneader or a twin-screw extruder alone or a combination of a roll and another kneading machine, Obtained by crushing. The phenol resin molding material of the present invention is excellent in heat resistance, dimensional stability, water resistance, and strength, and is used in an environment where it is necessary to consider various effects such as gasoline, alcohol, water, or temperature. It can be applied to electrical components.

[0013]

EXAMPLES Table 1 shows the formulations and characteristics of the examples and comparative examples.

[Table 1]

[Measuring Method] 1. Bending strength, deflection temperature under load: Performed according to JIS K 6911. The test piece was formed by transfer molding at 175 ° C. for 3 minutes and after baking at 180 ° C. for 3 hours. 2. Water resistance dimensional change rate: A test piece of 127 × 12.7 × 0.5 mm was obtained by transfer molding in the same manner as above. This test piece was subjected to a pressure cooker test at 130 ° C., and the dimensional change rate when saturated with water was taken as the water resistant dimensional change rate. 3. Curability: When transferring a test piece of 50φ × 3 mm to transfer molding, the test piece was taken out at 175 ° C. for 20 seconds, and after 10 seconds, Bacol hardness (No. 935) was measured to obtain curability.

[0015]

As is clear from the above Examples and Comparative Examples, the phenol resin molding material of the present invention is excellent in dimensional stability, water resistance, strength and curability. In particular, it is excellent in dimensional stability and water resistance at high temperatures, and is suitable for molded products that require these characteristics, especially for electrical components for automobiles and home appliances. It is also very suitable for shortening the molding cycle in compression and transfer molding.

Claims (3)

[Claims] 1. A resin composition comprising 20 to 50% by weight of an alkylbenzene-modified novolac type phenol resin, 25 to 55% by weight of a high ortho novolac type phenol resin, and 25 to 55% by weight of a methylol resole type phenol resin, and hexamethylene as a curing agent. A phenol resin molding material for transfer molding or compression molding, containing tetramine in an amount of 18 to 24% by weight based on the novolac type phenol resin, and containing a curing aid in an amount of 1 to 3% by weight based on the phenol resin. 2. The phenol resin composition according to claim 1, wherein each resin has an alkylbenzene modification ratio of 30 to 60 mol% and a number average molecular weight of 400 to 600.
Alkylbenzene modified novolac type phenolic resin,
The ortho / para bond ratio is 2.0 to 2.5, the number average molecular weight is 800 to 1100, and the novolac-type phenol resin has a methylol bond ratio of 40 in the bound formaldehyde.
A phenol resin molding material which is a methylol resole-type phenol resin having a number average molecular weight of 400 to 600 at a mol% or more. 3. The phenol resin molding material according to claim 1, which contains 25 to 35% by weight of the phenol resin composition and 40% by weight or more of glass fiber as a reinforcing material with respect to the entire molding material.