JPH11323083A - Melamine resin molding material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a melamine resin molding material, which gives a molded product excellent in electrical properties (e.g. resistance to tracking), resistance to heat, flexibility and rigidity. SOLUTION: This melamine resin molding material contains, as the essential components, 100 pts.wt. of a melamine resin having a number-average molecular weight of 180 to 400, 2 to 40 pts.wt. of epoxy resin and 2 to 40 pts.wt. of polyvinyl butyral. It is preferable that the molding material further contains an acrylonitrile-butadiene rubber at 2 to 40 pts.wt. and also glass fibers at least as part of the filler at 20 to 200 pts.wt. both per 100 pts.wt. of the melamine resin.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a melamine resin molding material having excellent electrical properties such as tracking resistance and flame resistance, excellent workability during production, and excellent flexibility and toughness.

[0002]

2. Description of the Related Art Melamine resin molding materials have been used for wiring appliances, electric appliances and the like due to their excellent tracking resistance, electrical insulation, coloring property and the like. Conventionally, organic fillers such as pulp, cotton dust, cloth chips, and inorganic fillers such as glass, calcium carbonate, clay, and mica have been mainly used as melamine resins to improve molding shrinkage and mechanical properties such as impact strength and bending strength. However, the melamine resin has a higher number of functional groups than other thermosetting resins, and therefore has a high crosslinking density and is liable to cause the resin to be rigid, and lacks flexibility and toughness. Therefore, thermoplastic molding materials and other thermosetting resin molding materials are mainly used for molded products requiring flexibility, and melamine resins do not require flexibility and toughness but are required to have electrical properties. Often used in goods.

In recent years, melamine resins having high flame resistance and excellent electrical characteristics have been replaced by thermoplastic resin molding materials having low electrical resistance such as tracking resistance and low flame resistance due to the enforcement of the PL method (Product Liability Law). Although molding materials are being reviewed, there is a problem of brittleness derived from melamine resin. In order to improve this point, it has been studied to mix various fillers and resins with the melamine resin.However, there are problems such as impairment of electrical properties, flame resistance and appearance of molded articles, and the effect is sufficient. I can't say. Attempts have also been made to suppress the rigidity of the resin itself by modifying the melamine resin to develop a material with excellent flexibility and toughness. At present it has not been obtained.

[0004] For these reasons, melamine resin molding materials are often used for molded articles in fields where thermoplastic resin molding materials requiring flexibility and toughness such as fitting properties and snap-ins are used. Absent. Therefore, the melamine resin molding material is mainly used in applications where coloring properties are absolutely necessary, such as electric parts and dishes requiring only tracking resistance.

[0005]

In view of the above, the present invention provides a melamine resin molding having excellent electrical properties such as tracking resistance and flame resistance, excellent workability in production, and excellent flexibility and toughness. It is to provide materials.

[0006]

According to the present invention, 100 parts by weight of a melamine resin having a number average molecular weight of 180 to 400 are mixed with 2 to 40 parts by weight of an epoxy resin and 2 to 40 parts by weight of polyvinyl butyral.
A melamine resin molding material characterized in that it is compounded as an essential component by weight, preferably, 2 to 40 parts by weight of acrylonitrile butadiene rubber is added to 100 parts by weight of the melamine resin, and more preferably, A melamine resin molding material characterized by containing 20 to 200 parts by weight of glass fiber as at least a part of the agent.

[0007] The type of epoxy resin used in the present invention is not particularly limited and may be a commercially available epoxy resin such as bisphenol A type or bisphenol F type. It is preferable to use a tracking resistant grade such as a glycidyl ester type.

[0008] The flexibility of the melamine resin molded article depends on the crosslinking density of the melamine resin molding material at the time of curing.
Since the number of functional groups of the melamine resin is as large as 6 per triazine nucleus, the melamine resin component has a high crosslinking density at the time of curing. Since the epoxy resin used in the present invention has a smaller number of functional groups per molecular weight than the melamine resin, the rigidity of the melamine resin is reduced by blending the epoxy resin having a long bond chain. The compounding amount of this epoxy resin is preferably 2 to 40 parts by weight, more preferably 5 to 15 parts by weight, based on 100 parts by weight of the melamine resin.
If the amount is less than 2 parts by weight, no improvement in flexibility is observed. If the amount exceeds 40 parts by weight, the epoxy resin which remains unreacted at the time of molding emerges on the surface of the molded product, resulting in poor appearance and reduced flame resistance.

[0009] Polyvinyl butyral is used for improving strength and flexibility and for improving production workability. The type of polyvinyl butyral is not particularly limited, but preferably has a polymerization degree of 250 to 2500, Butyral degree is 6
0 to 80 mol%. Further, a granular material having a size of 100 mesh or less is preferable. The addition amount is melamine resin 10
2 to 40 parts by weight, more preferably 5 to 0 parts by weight
20 parts by weight. Even if it is added in excess of 40 parts by weight, no further improvement in flexibility when the molding material is formed into a molded product is observed, and the flame resistance is also reduced. If the amount is less than 2 parts by weight, sufficient flexibility cannot be obtained.

In the production of a melamine resin molding material, there is a problem that as the degree of polymerization of the melamine resin increases, the viscosity increases and the workability deteriorates. However, adding epoxy resin and polyvinyl butyral imparts flexibility to the resin. Productivity is improved.

Acrylonitrile butadiene rubber is used for imparting flexibility and toughness to a molded article when used in combination with polyvinyl butyral. The type of the acrylonitrile butadiene rubber is not particularly limited. It is preferably a partially crosslinked type or a carboxy modified type with a compatibility parameter value of 9 to 11 at 45 mol%. The partially cross-linked NBR has a cross-linked structure in the molecule, and further has a carboxy-modified NBR.
Has a highly polar carboxyl group in the molecule, so that the impact strength is further improved as compared with general NBR.
When the compatibility parameter value is in the range of 9 to 11, the compatibility with the melamine resin is good. When the amount of bound acrylonitrile exceeds 45%, the hardness of the acrylonitrile-butadiene rubber itself increases, and when blended in a molding material, the flexibility cannot be sufficiently improved, and when the amount is less than 30%, acrylonitrile-butadiene rubber is not obtained. The heat resistance of the rubber itself is reduced, and when compounded in a molding material, the heat resistance of the molded product is reduced. The addition amount is 2 to 40 parts by weight, more preferably 5 to 15 parts by weight, based on 100 parts by weight of the melamine resin.
Parts by weight. If it is added in excess of 40 parts by weight, the tracking resistance, flame resistance and strength decrease, and if it is less than 2 parts by weight, sufficient effects cannot be obtained.

The glass fiber used as the filler is used for improving the strength, and is not particularly limited, and may be a commercially available glass fiber. The addition amount is 20 to 200 parts by weight, more preferably 30 to 100 parts by weight, based on 100 parts by weight of the melamine resin. 200
Even if it is added in excess of parts by weight, no further improvement in toughness is observed when the molding material is used as a molded article, and further problems such as poor workability during production of the molding material arise. If the amount is less than 20 parts by weight, it is difficult to obtain a target strength. In addition, all or part of the glass fiber pulp,
It may be replaced with an organic fiber such as a crushed cloth.

A melamine resin for producing a molding material,
Raw materials used with epoxy resin, polyvinyl butyral, acrylonitrile butadiene rubber, and glass fiber are other fillers, curing agents, coloring agents, release agents, plasticizers,
Flame retardants such as hydrated metal hydroxides.

The melamine resin used in the present invention may be modified with a phenol resin, an epoxy resin, a rubber or the like. Further, a part of the melamine resin may be replaced with a urea resin or the like. In the method for producing a molding material using the melamine resin composition, kneading may be carried out using a usual mixing roll or twin-screw extruder, or granulation may be carried out using a high-speed rotary mixer.

The molding method for obtaining a molded article using the melamine resin molding material of the present invention can be applied to any of injection molding, transfer molding, compression molding and the like, and is not limited.

[0016]

EXAMPLE A raw material shown in Table 1 was kneaded with a predetermined mixing ratio by a mixing roll and pulverized to produce a molding material. A test piece was formed from the obtained molding material, and the bending strength, the flexural modulus, the Charpy impact strength, the amount of bending deflection, and the arc resistance, tracking resistance, and flame resistance were measured. The test specimen is formed by transfer molding, and the molding condition is 1
At 50 ° C. for 3 minutes.

[0017]

[Table 1]

* 1) Melamine resin: Methylolation degree 1.
70, number average molecular weight 300 * 2) epoxy resin: bisphenol A type, epoxy equivalent 600-700, number average molecular weight 1100 * 3) polyvinyl butyral (PVB): degree of polymerization 30
0, butyralization degree 65 mol% * 4) Acrylonitrile butadiene rubber (NBR): bound acrylonitrile amount 40 mol%, partially crosslinked, compatibility parameter value 9.5 * 5) Acrylonitrile butadiene rubber (NBR): bound acrylonitrile amount 40 Mol%, carboxy-modified,
Compatibility parameter value 9.5

(Measurement method) Flexural strength, flexural modulus, flexural deflection: JIS K72
03. Charpy impact strength: Measured according to JIS K 7111. Arc resistance: Measured according to JIS K 6911. Tracking resistance: IEC. It was measured by Pub112. Flame resistance: Measured according to UL94.

As in the embodiment, by blending epoxy resin and polyvinyl butyral with melamine resin, and preferably using acrylonitrile butadiene rubber and glass fiber, it is excellent in electrical properties such as tracking resistance, flame resistance, and flexibility. A melamine resin molding material having excellent toughness was obtained.

[0021]

According to the present invention, it is possible to obtain a molded article excellent in electrical properties such as tracking resistance and flame resistance, and excellent in flexibility and toughness. Therefore, it is possible to easily produce a molded article for applications requiring flexibility and toughness, which is excellent in electric properties such as tracking resistance and flame resistance which could not be produced conventionally, and also has good productivity of molding material. It is suitable as an industrial melamine resin molding material.

Continued on the front page (51) Int.Cl. ⁶ Identification code FI C08L 9:02)

Claims (6)

[Claims] 1. A melamine resin molding material comprising, as essential components, 2 to 40 parts by weight of an epoxy resin and 2 to 40 parts by weight of polyvinyl butyral in 100 parts by weight of a melamine resin having a number average molecular weight of 180 to 400. 2. An epoxy resin having an epoxy equivalent of 100 to
The melamine resin molding material according to claim 1, wherein the number average molecular weight is from 5,000 to 5,000. 3. Polyvinyl butyral has a degree of polymerization of 250.
The melamine resin molding material according to claim 1 or 2, which has a butyralization degree of 60 to 80 mol%. 4. The method according to claim 1, wherein 100 parts by weight of the melamine resin
The melamine resin molding material according to claim 1, wherein the acrylonitrile-butadiene rubber is compounded in an amount of from 40 to 40 parts by weight. 5. The melamine resin molding material according to claim 4, wherein the acrylonitrile-butadiene rubber is of a partially crosslinked or carboxy-modified type, has a bound acrylonitrile content of 30 to 45%, and has a compatibility parameter value of 9 to 11. 6. The melamine resin molding material according to claim 1, wherein 20 to 200 parts by weight of glass fiber is blended as at least a part of the filler with respect to 100 parts by weight of the melamine resin. .