JP3543924B2 - Phenolic resin molding material - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a phenolic resin molding material having excellent dielectric breakdown strength, tracking resistance, flame resistance, and strength.
[0002]
[Prior art]
Phenolic resin molding materials are excellent in heat resistance, dimensional stability, moldability, and the like, and have been used for a long time in key industrial fields such as automobiles, electricity, and electronics. In particular, recently, the demand for reliability of products has become strict, and electrical performance such as dielectric breakdown strength and tracking resistance has been demanded.
[0003]
Usually, for parts requiring electrical characteristics, resins having excellent electrical characteristics such as unsaturated polyester resin, diallyl phthalate resin, melamine resin, and melamine / phenol resin are often used, but heat resistance, moldability, There is a problem in terms of cost and the like, and it is desired to impart higher tracking resistance, dielectric breakdown strength and flame resistance while maintaining excellent heat resistance and moldability of the phenol resin molding material. Electronic components, especially coil bobbins, are required to have mechanical strength such as impact strength and bending strength in addition to electrical characteristics.
[0004]
The characteristics of molding materials using resole resin are that, in addition to not generating ammonia gas from the molded product, and suppressing ionic impurities such as inorganic fillers contained, the electrical characteristics, especially moisture resistance and dielectric breakdown strength, are reduced. It is characterized by good things. In general, pulverized laminates, inorganic fillers, and the like are often used as fillers, and it has been studied to further improve tracking resistance and the like by blending an inorganic filler containing crystallization water. (Japanese Patent Application No. 07-68241, etc.), however, there was also a problem that the strength was brittle, and it was not always satisfactory.
[0005]
If attention is paid only to the impact strength and the bending strength, the addition of the conventionally used glass fiber has a sufficient effect, but the drawback of being hard and brittle appears due to the increase in the elastic modulus.
Similarly, by adding rubber components such as NBR and SBR in order to increase the amount of bending of the molded product, it is possible to improve the impact strength together with the amount of bending, but there is a disadvantage that the bending strength decreases. .
[0006]
[Problems to be solved by the invention]
The present invention has been made as a result of various studies in order to solve such a problem of the molding material using the conventional resol type phenol resin, and its purpose is to achieve tracking resistance and dielectric breakdown strength. Another object of the present invention is to provide a phenolic resin molding material having excellent mechanical strength such as flame resistance, bending strength and impact strength.
[0007]
[Means for Solving the Problems]
The present invention provides a molding material containing 25 to 35% by weight of a resole type phenol resin, at least one kind of a first inorganic filler selected from zinc borate and unfired clay as a flame retardant component, and calcium borate. , A total of at least one kind of a second inorganic filler selected from aluminum hydroxide and magnesium hydroxide and at least 40% by weight, and the content of the second inorganic filler is at least 10% by weight. In addition, the present invention relates to a phenol resin molding material containing 5 to 15% by weight of glass fiber and 2 to 5% by weight of polyvinyl butyral.
[0008]
The resole type phenolic resin used here is used for a general phenolic resin molding material, and is a dimethylene ether type resole resin, a methylol type resole resin, and the like. However, if hexamethylenetetramine is used as a curing agent, hexamethylenetetramine cannot be used due to the problem that the moisture resistance and electrical characteristics are reduced due to the generation of ammonia from the molded article. The amount of the phenolic resin is 25 to 35% by weight based on the whole molding material. If the content is less than 25% by weight, the wettability with the substrate is not sufficiently obtained, and the strength is reduced and the formability is reduced due to insufficient flow. On the other hand, if it exceeds 35% by weight, the tracking resistance is lowered and the cost of the material is increased, which is not practical.
[0009]
As the inorganic filler used as the flame retardant component, at least one first inorganic filler selected from zinc borate and unfired clay, and at least one type selected from calcium borate, aluminum hydroxide and magnesium hydroxide It is necessary to contain 40% by weight or more, preferably 45% by weight or more in the molding material in total with the second inorganic filler .
Further, the content of the second inorganic filler is 10% by weight or more. If the total amount of the inorganic filler as a flame-retardant component is less than 40% by weight, sufficient flame resistance and tracking resistance cannot be obtained, and if the second inorganic filler is not used in the molding material in an amount of 10% by weight or more, it is insufficient. High flame resistance cannot be obtained.
[0010]
The glass fiber may be a commonly used chopped strand, and E glass with little ionic impurities is preferred, but not limited thereto. The addition amount is preferably 5 to 15% by weight in the molding material, and if it is less than 5% by weight, the effect of imparting sufficient strength cannot be obtained. If it exceeds 15% by weight, the elastic modulus is too high, and polyvinyl butyral (PVB) is used in combination. Even so, fragility cannot be fully overcome.
[0011]
The type of polyvinyl butyral is not particularly limited, but preferably has a degree of polymerization of 250 to 2500 and a degree of butyralization of 60 to 80 mol%. Further, a granular material having a size of 100 mesh or less is preferable. The addition amount is preferably 2 to 5% by weight, and if it is less than 2% by weight, the effect of sufficiently increasing the strength is small, and if it exceeds 5% by weight, there is a problem that the bending strength is reduced although the bending amount is increased.
As the other fillers, crushed cloth, laminated board crushed powder, calcined clay, calcium carbonate, and the like used in ordinary resol-type phenolic resin molding materials are used, and those having little ionic impurities are desirable from the viewpoint of electrical characteristics.
[0012]
The phenolic resin molding material of the present invention is generally prepared by adding a release agent, a curing accelerator, and the like used for a general phenolic resin molding material to the above-described composition, and uniformly mixing these materials. It is manufactured by heating and kneading with a kneading machine such as a shaft extruder and pulverizing.
The phenolic resin composition-shaped material of the present invention is suitable for electric parts and electronic parts that require mechanical strength such as dielectric strength, tracking resistance, impact strength, and bending strength, and particularly for electronic parts such as coil bobbins. .
[0013]
【Example】
The molding material was obtained by heating and kneading with the usual two rolls at the raw materials and mixing ratios shown in the upper column of Table 1. The molded article characteristics of these molding materials were measured, and the results shown in the lower column of Table 1 were obtained. Table 2 shows the dissociation temperature of crystal water and the amount of released crystal water of the inorganic filler used.
[0014]
(Measuring method)
1. Crystal water release amount: Release amount (% by weight) at 200 to 500 ° C. Differential thermal analysis method Crystal water dissociation temperature: determined by differential thermal analysis Tracking resistance: Measured according to JIS C 2134.
4. Other properties: Measured according to JIS K 6911.
All the test pieces having the characteristics of the molded product were formed by transfer molding (molding at 175 ° C. for 3 minutes).
[0015]
[Table 1]
[0016]
[Table 2]
[0017]
【The invention's effect】
The phenolic resin molding material of the present invention is such that a molded article obtained therefrom is excellent in heat resistance, dielectric strength, tracking resistance and mechanical strength such as impact strength and bending strength, and these properties are required. It is suitable for electric machines and electronic components, especially electronic components such as coil bobbins.

Claims (2)

The molding material contains 25 to 35% by weight of a resole type phenol resin, and as a flame retardant component, at least one first inorganic filler selected from zinc borate and unfired clay; calcium borate; and aluminum hydroxide. And at least one type of second inorganic filler selected from magnesium hydroxide in a total amount of 40% by weight or more, and the content of the second inorganic filler is 10% by weight or more , A phenolic resin molding material containing 5 to 15% by weight of glass fiber and 2 to 5% by weight of polyvinyl butyral. The phenolic resin molding material according to claim 1, wherein hexamethylenetetramine is not contained.