JPH0160169B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to an epoxy resin composition that is highly stable in the screw of an injection molding machine and can be injection molded. Epoxy resin is used to manufacture electrical and electronic parts by sealing elements such as coils, transistors, diodes, ICs, and LSIs because of its excellent electrical performance and adhesive properties. used for a purpose. For example, an epoxy resin composition made by blending an epoxy resin and a phenolic novolak resin as a curing agent with an accelerator such as a tertiary amine or imidazole is put into a transfer spot, and after melting, it is poured into a mold with a plunger. Electrical and electronic parts are manufactured by sealing coils and the like using a discontinuous indentation transfer molding method. However, this method has many problems, such as very low productivity, and this accelerator system causes large shrinkage during curing, causing distortion in the product. In order to improve productivity, the present inventor considered manufacturing the electric/electronic parts by injection molding,
When various compositions were tested, it was found that in the epoxy resin composition described above, gelation progresses in the cylinder of an injection molding machine heated to about 60 to 120 degrees Celsius because the temperature dependence of gelation is small, resulting in poor fluidity. It has been difficult to continuously perform molding by injection molding due to poor stability such as insufficient maintenance. however,
The present inventor has found that a composition containing a small amount of urea together with a novolac resin as a curing agent can be heated to a temperature of approximately 60 to 120°C.
In the cylinder of an injection molding machine, which is heated to a high temperature, it maintains sufficient fluidity for a sufficient period of time, making it highly stable and injection moldable.In the mold, which is heated to a higher temperature, it hardens rapidly and has little shrinkage. Furthermore, the inventors have discovered that good electrical and electronic components with less distortion can be obtained by further performing post-curing after molding, leading to the completion of the present invention. That is, the gist of the present invention is an injection-moldable epoxy resin composition comprising 20 to 120 parts by weight of novolac resin and 0.1 to 20 parts by weight of urea to 100 parts by weight of epoxy resin. The present invention will be explained in more detail below. The epoxy resin used in the present invention is, for example, a compound having a 1,2-epoxyethyl group at an end, and particularly preferably a compound in which a 1,2-epoxypropyl group is bonded to an oxygen, nitrogen, or sulfur atom. . Examples of such epoxy resins include polyglycidyl ethers, which can be treated with compounds having at least two free alcoholic and/or phenolic hydroxyl groups in the molecule, for example in the presence of an alkali or an acid catalyst. It is obtained by reacting with epichlorohydrin or glycerol dichlorohydrin. The ethers include ethylene glycol, diethylene glycol, triethylene glycol, higher polyoxyethylene glycol, propane-1,2-diol, polyoxypropylene glycol, propane-1,3-diol, butane-1,4-diol, and polyoxybutylene. Glycol, pentane-1,5-diol, hexane-1,6-diol, hexane-1,6-diol
2,4,6-triol, glycerol, 1,
Acyclic alcohols such as 1,1-trimethylolpropane, pentaerythritol, poly(epichlorohydrin); resorcitol, quinitol, bis(4-hydroxycyclohexyl)-methane, 2,2-bis(4- cycloaliphatic alcohols such as hydroxycyclohexyl)propane, 1,1-bis(hydroxymethyl)cyclohexene-3; N,N-bis(2-hydroxyethyl)aniline, 4,4'-bis(2-hydroxyethylamino) ) It can be obtained from alcohols with aromatic nuclei such as diphenylmethane. Alternatively, mononuclear phenols such as resorcinol, hydroquinone, bis(4-hydroxyphenyl)methane, bis(4-hydroxyphenyl)
Sulfone, 1,1,2,2-tetrakis(4-hydroxyphenyl)ethane, 2,2,-bis(4
-hydroxyphenyl)propane (known as bisphenol A), 2,2-bis(3,
Polynuclear enofures such as 5-dibromo-4-hydroxyphenyl)propane, aldehydes and phenols such as formaldehyde, acetaldehyde, chloral, furfuraldehyde, 4-chlorophenol, 2-methylphenol, o-cresol, 4-tersia It can also be obtained from novolacs obtained from phenols such as butylphenol. Among the poly(N-glycidyl) compounds are, for example, epichlorohydrin and aniline, n-butylamine, bis(4-aminophenyl)methane,
Amines containing at least two amino hydrogen atoms such as bis(4-methylaminophenyl)methane, triglycidyl isocyanurate, and cyclic ureas such as ethylene urea, 1,3-propylene urea, 5,5- Also included are those obtained by dihydrochlorination with reaction products of hydantoins, such as dimethylhydantoin, with N,N'-diglycidyl derivatives. Examples of poly(S-glycidyl) compounds include:
Examples include di-S-glycidyl derivatives of dithiols such as ethane-1,2-dithiol and bis(4-mercaptoethyl phenyl) ether. Also included are polyglycidyl esters obtained by reacting a compound having two or more carboxyl groups in one molecule with epichlorohydrin or glycerol dichlorohydrin in the presence of an alkali. Such polyglycidyl esters are
oxalic acid, acetic acid, glutaric acid, adipic acid, pinelic acid, suberic acid,
Aliphatic polycarboxylic acids such as azelaic acid, sebacic acid, dimerized or trimerized linoleic acid; alicyclic acids such as tetrahydrophthalic acid, 4-methyltetrahydrophthalic acid, hexahydrophthalic acid, 4-methylhexahydrophthalic acid Formula polycarboxylic acid;
It can be obtained from aromatic carboxylic acids such as phthalic acid, isophthalic acid, and terephthalic acid. Epoxy resins in which the terminal 1,2-epoxide groups are bonded to various hetero elements can also be used. Examples of these include N,N,O-triglycidyl derivatives of p-aminophenol or glycidyl ether-glycidyl esters of salicylic acid or phenolphthalein. In the present invention, a mixture of these epoxy resins can be used. In the present invention, glycidyl ether of novolak obtained by reacting phenol or cresol with formaldehyde is particularly preferred since the cured product has good heat resistance. The epoxy equivalent is preferably 100-300. Next, the novolac resin referred to in the present invention is produced by combining phenol, alkyl-substituted phenol, such as o-cresol, p-cresol, t-butylphenol, cumylphenol, vinylphenol, and formaldehyde under an acidic catalyst. It is obtained by condensation with, especially 2 to 10
It is preferable that the core has a softening point of about 50 to 140°C.
Novolac resins are required as curing agents in the compositions of this invention. The composition of the present invention also contains a small amount of urea.
Urea has a hardening accelerating effect. The blending ratio of the composition is 20 to 120 parts by weight, preferably 40 to 100 parts by weight, of the novolak resin per 100 parts by weight of the epoxy resin. At this blending amount, sufficient curing is achieved, and even if it is more or less, curing will not be sufficient. Further, urea is used in an amount of 0.1 to 20 parts by weight, preferably 1 to 10 parts by weight. 0.1
If it is less than 20 parts by weight, the curing accelerating effect will be poor, and if it exceeds 20 parts by weight, curing will proceed too rapidly, resulting in large shrinkage of the molded product and making the molded product brittle. Further, in the present invention, by further adding dicyandiamide, curing within the mold can be promoted without impairing stability within the cylinder of the injection molding machine. In this case, the blending amount of dicyandiamide is approximately 0.1 to 5 parts by weight per 100 parts by weight of the epoxy resin.
Parts by weight are preferred. In addition, additives commonly used in epoxy resin molding materials can also be incorporated as optional components in the injection molding composition. For example, mica,
Asbestos short fibers, calcium carbonate, alumina,
About 50 to 900 parts by weight of a filler such as silica, talc, glass fiber or aluminum hydroxide, about 0.1 to 10 parts by weight of a mold release agent such as carnauba wax or stearic acid, and about 0.01 part by weight of a coloring agent such as carbon black. ~5 parts by weight, or an appropriate amount of a flame retardant such as antimony oxide or a halogenated polyphenol such as tetrabromobisphenol A can also be blended. The components in the composition are mixed, for example, by kneading at a temperature of about 80 to 120°C using rolls such as two rolls, a twin screw extruder, etc., and then cooling and pulverizing. After dry blending in a tumbler mixer at room temperature, the mixture may be compression molded into pellets or granules to facilitate feeding into an injection molding device. As the injection molding device, a known device for thermosetting resin can be used. Since the composition of the present invention is a thermosetting type, it is necessary to use a long press that allows the curing reaction to proceed in a heating cylinder, and on the other hand, it is necessary to increase the molding cycle by making curing in the mold as fast as possible. The temperature inside the cylinder or cylinder head is 60 to 120℃, and the mold temperature is 120 to 120℃.
The temperature is preferably 200°C. Hardening in a mold is done to the extent that it can be taken out into the desired shape. The temperature is 120~200℃ as mentioned above.
The curing time is approximately 20 seconds to 3 minutes. Further, the molded product taken out from the mold is usually post-cured in an oven at a temperature of 100 to 200°C for about 2 to 10 hours to completely cure it. As a result, a molded product with less cracks and less distortion after curing can be obtained. As described above, the composition of the present invention can be injection molded, and compared to molding by conventional transfer molding manufacturing methods, productivity is greatly improved, and curing with less shrinkage, cracking, distortion, etc. It is something that gives things. The composition of the present invention is suitably used in the production of electric/electronic parts, sealing, production of mechanical parts, and other production of epoxy resin molded products by injection molding. It goes without saying that the composition of the present invention can also be applied to transfer molding. Example 1 A compound with the following composition was kneaded with two rolls (90~
After cooling, the mixture was ground into granules and the gelation time was measured using the Brabender plastograph method (using Labo Plastomill, manufactured by Toyo Seiki Co., Ltd.) (Table 1). EOCN-102S (Nippon Kayaku Co., Ltd. product, o-cresol novolac epoxy resin, epoxy equivalent 210
~240) 30 parts by weight Phenol novolak resin (Showa Union Co., Ltd. product, OTM-007, softening point 85-95℃) 13.5 parts by weight Fuzulex RD-8 (Tatsumori Co., Ltd. product, fused silica) 70 parts by weight Stearin Acid: 0.5 parts by weight Carbon black: 0.3 parts by weight Urea: 3 parts by weight Comparative Example 1 In the formulation of Example 1, instead of 3 parts by weight of urea, 1 weight of 2-ethyl-4-methyl-imidazole-azine complex (product of Shikoku Kasei Co., Ltd.) was used. The gelation time was measured in the same manner as in Example 1, except that 100% of the gel was used.
The results are shown in Table 1.

[Table] It is clear that the composition of Example 1 has a greater temperature dependence of gelation than the composition of Comparative Example 1, and is suitable for injection molding. Example 2 and Comparative Example 2 The following formulation (parts by weight) was kneaded for 5 minutes using two rolls at a temperature of 90 to 100°C, and then cooled.
A molding material was obtained by pulverizing it into granules.

[Table] For Example 2, the obtained molding material was injection molded using a Meiki injection molding machine (Thermosetter, clamping pressure 100t) under the following conditions. Cylinder head temperature 80℃ Screw rotation speed 37r.pm Injection pressure 400Kg/cm ² Injection speed 7.3cm/sec Mold temperature 180℃ Mold holding time (corresponding to the molding cycle) 50sec The molded product was then post-cured at 160℃ for 8 hours.
A test piece based on JIS K 6911 was created. Regarding Comparative Example 2, injection molding was attempted under the same conditions as in Example 1, but the viscosity of the composition increased significantly in the injection molding machine, making continuous molding difficult. Therefore, transfer molding was performed under the following conditions (using a transfer molding machine manufactured by Matsuda Machinery, mold clamping pressure
50t). Plunger pressure 70Kg/cm ² Plunger descending speed 3cm/sec Mold temperature 180°C Mold holding time 180sec Next, the molded product was post-cured at 160°C for 8 hours to prepare a test piece. The physical properties of the test pieces obtained in Example 2 and Comparative Example 2 were measured, and the results are shown in Table 2. Measurements were conducted based on JIS K 6911. However, the glass transition temperature was determined by a linear expansion coefficient measurement method. From the above results, the molded product of Example 2 is the same as that of Comparative Example 2.
Less curing shrinkage than conventional molded products.

[Table] Example 3 In place of EOCN-102S in Example 1,
EOCN-103S (Nippon Kayaku Co., Ltd. product, o-cresol novolac epoxy resin, epoxy equivalent 210~
The gelation time was measured in the same manner as in Example 1, except that dicyandiamide (235) was used and 1 part by weight of dicyandiamide was further added. The results are shown in Table 3.

【table】

Claims (1)

[Scope of Claims] 1. An injection moldable epoxy resin composition comprising 20 to 120 parts by weight of novolak resin and 0.1 to 20 parts by weight of urea to 100 parts by weight of epoxy resin. 2. An injection moldable epoxy resin composition comprising 100 parts by weight of epoxy resin, 20 to 120 parts by weight of novolak resin, 0.1 to 20 parts by weight of urea, and 0.1 to 5 parts by weight of dicyandiamide.