JP2000226440A - Epoxy resin composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an injection-moldable composition possessing such curing characteristics as to show heat stability not allowing curing in a cylinder and to rapidly cure in a mold by compounding an epoxy resin with a curing agent and a cure accelerator being a specified urea compound. SOLUTION: The cure accelerator used is a urea compound obtained by reacting a phenylsulfa isocyanate with a secondary amine. The cure accelerator used is a compound (a substituted or unsubstituted phenylsulfa isocyanate/ dialkylamine adduct) represented by the formula (wherein Y and Z, which may the same as or different from each other, are each hydrogen, a halogen, or an alkyl, desirably a 1-4C lower alkyl; and R1 and R2, which may be the same as or different from each other, are each a hydrogen or an alkyl, desirably, a 1-4C lower alkyl). It is desirable that 100 pts.wt. epoxy resin is compounded with 20-120 pts.wt. curing agent and 0.1-20 pts.wt. cure accelerator.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a novel epoxy resin composition, and more particularly, to the use of a specific curing accelerator so that it can be cured without being cured in a cylinder of an injection molding machine. The present invention relates to an epoxy resin composition having excellent stability and enabling latent-type curing characteristics in which a curing reaction proceeds rapidly in a mold.

[0002]

2. Description of the Related Art It is well known that epoxy resins are excellent in various physical properties such as heat resistance, abrasion resistance, and chemical resistance, and are used for many purposes. Conventionally, a transfer molding method has been known as a molding method suitable for the productivity of an epoxy resin molding material. In transfer molding, it is general that before molding, an epoxy resin composition is charged into a pot in a mold, and this is pressurized with a plunger and fluidized and hardened in the mold.

However, in this molding method, first, it is necessary to make the molding material into a tablet, and further, since a preheating step is required, the molding cycle cannot be shortened beyond a certain level, and productivity and cost reduction are required. Naturalization has its own limitations. Further, transfer molding has a problem that a cull remaining in the pot in addition to the runner at the time of molding is generated as cured waste. The cured cull is usually
Although they are discarded without being reused, they do not decompose when discarded, which contributes to environmental pollution.

[0004] On the other hand, in the injection molding method, usually, only by charging a thermoplastic resin molding material powder into a hopper, residual heat and measurement are automatically performed in a cylinder, and then injected into a mold and cured. Therefore, in this case, the step of tableting the molding material and the step of residual heat become unnecessary, and since continuous production is possible, the molding cycle can be shortened as compared with transfer molding, which is excellent in terms of production efficiency. It can be said that the method. However, conventionally,
Epoxy resin molding materials used for transfer molding have poor thermal stability in a cylinder, and their melt viscosities are significantly increased, so that injection molding cannot be performed.

[0005] In order to recognize such prior art and to solve the problems, studies have been made on epoxy resin compositions that can be injection molded. For example, Japanese Patent Application Laid-Open No. H8-3
01836 and JP-A-8-301988 disclose an invention relating to a curing accelerator for epoxy resin suitable for injection molding, and US Pat. No. 4,533,71.
No. 5 discloses an invention of a curing agent.

The present applicant has also developed a technique for molding an epoxy resin excellent in various physical properties by an injection molding method capable of a short molding cycle and capable of continuous production.
0169, JP-A-10-95900, JP-A-10-109320 and JP-A-10-110
No. 088 is published.

[0007]

In the search for peripheral technology of the above-mentioned application, the present applicant uses a specific compound as a curing accelerator for epoxy resin to cure in a cylinder. The present inventors have found that an injection-moldable epoxy resin composition having excellent heat stability without curing and having a curing property of rapidly curing in a mold can be obtained, thereby completing the present invention.

[0008]

That is, according to the present invention, a urea compound obtained by reacting an epoxy resin (A), a curing agent (B), and phenylsulfur isocyanate (s) with a secondary amine. An epoxy resin composition comprising a curing accelerator (C) comprising:

Further, according to the present invention, the above curing accelerator
The epoxy resin composition is provided, wherein (C) is a compound represented by the following formula (1) (a dialkylamine adduct of phenylsulfur isocyanate (s)).

Embedded image (In the formula, Y and Z represent the same or different hydrogen, halogen or alkyl group, and R ¹ and R ² represent the same or different hydrogen or alkyl group.)

Further, according to the present invention, the epoxy resin (A)
An epoxy resin composition capable of being injection-molded, comprising 20 to 120 parts by weight of a curing agent (B) and 0.1 to 20 parts by weight of a curing accelerator (C) per 100 parts by weight.

[0011]

DETAILED DESCRIPTION OF THE INVENTION An important feature of the present invention is that a urea compound obtained by reacting phenylsulfur isocyanate (s) with a secondary amine is used as a curing accelerator for epoxy resins. .

The curing accelerator (C) is obtained by reacting a phenylsulfur isocyanate (s) such as phenylsulfur isocyanate and tosyl isocyanate with a secondary amine. Is
Dialkylamines such as dimethylamine and alicyclic amines such as piperidine, pyrrolidine, morpholine, and lower alkyl-substituted products thereof are preferably used.

Specific examples of the curing accelerator (C) include compounds represented by the following formula (1).

Embedded image (In the formula, Y and Z are hydrogen atoms, halogen atoms or alkyl groups which may be the same or different, and the alkyl group is preferably a lower alkyl group having 1 to 4 carbon atoms. R ¹ , R ²
Is hydrogen or an alkyl group which may be the same or different, and the alkyl group is preferably a lower alkyl group having 1 to 4 carbon atoms. )

Examples of the curing accelerator (C) for the epoxy resin represented by the above general formula which can be used in the present invention include compounds represented by the following formulas (2) to (8) shown on the following page. Among them, the compounds represented by the formulas (2) and (3) are preferably used.

[0015]

Embedded image

The curing accelerator (C) for epoxy resin is used in an amount of 0.1 to 20 parts by weight per 100 parts by weight of epoxy resin (A).
Parts by weight, preferably 2 to 10 parts by weight, are incorporated.

Incidentally, curing accelerators such as 2-methylimidazole and triphenylphosphine, which have been conventionally used in transfer molding, cannot be injection-molded due to lack of thermal stability in a cylinder by themselves. Can be used together to shorten the curing time in the mold.

Epoxy resin used in the present invention
As (A), for example, an orthocresol type epoxy resin, a biphenyl type epoxy resin, a naphthalene type epoxy resin, and a hydro type epoxy resin may be used alone or in combination.

The epoxy resin composition of the present invention comprises a curing agent (B) and the above-mentioned specific curing accelerator added to the epoxy resin (A).
It is constituted by appropriately blending (C) and an inorganic filler.

As the curing agent (B), phenol resin, melamine resin, acrylic resin, isocyanate resin and the like can be used. In particular, as a phenolic resin,
Phenol novolak resin, cresol novolak resin, resol resin, and the like, among which phenol resin having two or more hydroxyl groups in one molecule, having a hydroxyl equivalent of 80 to 120 and a softening point of 60 to 120 ° C., alone or It can be used in combination with others. In the present invention, among these, a phenol novolak resin is preferably used.

As the phenol novolak resin, a novolak type phenol resin obtained by reacting phenols such as phenol, cresol and xylenol with formaldehyde using an acid catalyst, and modified resins thereof, for example, epoxidized or butylated novolak Type phenolic resin, of which the hydroxyl equivalent is 10
Those having a temperature of 0 to 150 and a softening point of 60 to 110 ° C are preferably used.

The curing agent (B) is blended in an amount of 20 to 120 parts by weight, preferably 30 to 70 parts by weight, particularly preferably 40 to 60 parts by weight, based on 100 parts by weight of the epoxy resin. Taking the case of a phenol novolak resin as an example, the mixing ratio is such that the number of phenolic hydroxyl groups is 0.5 to 2.0, preferably about 1 per epoxy group contained in the epoxy resin. Is equivalent to

Examples of the inorganic filler include talc, ferrite, graphite, silicon nitride, mica, calcium carbonate, clay, alumina, alumina silica, crushed silica, spherical silica, zinc oxide, carbon, aluminum hydroxide, asbestos fiber, glass Powder, fibrous, such as fiber, carbon fiber, glass beads, shirasu balloon, silica balloon,
Balloon-shaped ones are exemplified. Among them, crushed silica, spherical silica and glass fiber are preferably used alone or in combination, and particularly, the maximum particle size is 10 to 500 μm.
m and silica having an average particle size of 5 to 50 μm are preferred.

The epoxy resin composition of the present invention may contain other additives in addition to the above components. Examples of such additives include, for example, natural waxes such as carnauba wax, synthetic waxes, metal salts of linear fatty acids such as stearic acid, release agents such as acid amides, esters and paraffins, Colorants such as carbon black, halogen polyhydric phenols such as tetrabromobisphenol A, flame retardants such as brominated novolak epoxy, coupling agents such as γ-glycidoxypropyltrimethoxysilane, organopolysiloxanes, organosiloxane-modified Phenol, a flexibility imparting agent such as modified butadiene rubber, and the like can be given.

[0025]

According to the present invention, the epoxy resin composition has excellent thermal stability without being cured in a cylinder of an injection molding machine and has a latent curing property in which an effect reaction proceeds rapidly in a mold. And a continuous injection moldable epoxy resin composition. In addition, injection molded articles molded from this composition are also excellent in that the formation of molding burrs is significantly suppressed. The resin composition of the present invention exhibits the above-mentioned excellent properties, is also excellent in electrical insulation, and has a low molding shrinkage ratio. It is suitably used as a resin composition for a sealing agent such as an agent.

[0026]

Next, the present invention will be described by way of examples. This example is intended to illustrate one embodiment of the present invention and is not intended to limit the invention.

Table 1 shows the compositions of the epoxy resin compositions of Examples and Comparative Examples of the present invention.

In Table 1, the symbols of the compositions represent the following compounding agents. A: ortho-cresol novolak epoxy resin B: phenol novolak resin C: brominated novolak epoxy resin D: antimony trioxide E: dimethylamine adduct of tosyl isocyanate (tosyl represented by the formula (3) of [Formula 4] F: triphenylphosphine G: 2-methylimidazole H: crushed silica (average particle size 10 μm) I: silane coupling agent J: carbon black K: carnauba wax

Preparation of Composition The above components were blended in the proportions shown in Table 1, kneaded with an 8-inch roll heated to 100 ° C. for 5 minutes, cooled and pulverized to obtain a homogeneous epoxy resin composition. . Evaluation of Injection Moldability Injection moldability (continuous moldability) of each composition was evaluated, and the results are shown in Table 2 together with molding conditions, molding cycle, weight of discarded parts, and weight of product parts. The injection moldability is determined by touching the tip of the mold sprue bush and the tip of the nozzle of the injection molding machine, and whether injection is possible or not by curing the tip of the nozzle. It was judged.

[0030]

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Tsukasa Sakuraba 580-32 Takuji, Nagaura-shi, Sodegaura-shi, Chiba F-term (reference) 4J036 AA01 AD07 AF05 AF07 DA05 DD01 DD05 FB03 FB07 FB09 FB10

Claims (3)

[Claims] 1. A curing accelerator comprising a urea compound obtained by reacting an epoxy resin (A), a curing agent (B) and a phenylsulfur isocyanate (s) with a secondary amine.
An epoxy resin composition containing (C). 2. The epoxy resin composition according to claim 1, wherein the curing accelerator (C) is a compound represented by the following formula (1). Embedded image (In the formula, Y and Z represent hydrogen or a halogen or an alkyl group which may be the same or different, and R ¹ and R ² represent a hydrogen or an alkyl group which may be the same or different.) 3. The composition according to claim 1, wherein 20 to 120 parts by weight of the curing agent (B) and 0.1 to 20 parts by weight of the curing accelerator (C) are mixed with 100 parts by weight of the epoxy resin (A).
The epoxy resin composition capable of being injection-molded according to the above.