JPS6321686B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a fast-curing unsaturated polyester resin composition mainly used for resin molded products for sealing electrical and electronic parts. In recent years, in order to lower the cost and improve productivity of electrical and electronic equipment parts, plastics have been used to seal them. These electrical components include transistors, diodes, capacitors,
There are filters, rectifiers, resistors, coils, etc. These plastic sealing methods include casting, compression molding, injection molding, and transfer molding.In order to improve productivity, injection and transfer molding methods, which are superior in mass production and workability, are used. It is widely used. Generally, these electrical parts are small and are molded in a large number of molds, such as 50 to 200 molds. For this reason, sealing materials are required to have excellent flowability when melted and plasticized to satisfy extremely large number of moldings, and that this flowability does not deteriorate during storage or molding operations. . In addition, when embedding electrical parts using these low-voltage sealing materials, the electric wires, electromagnetic plates, heat sinks, etc. and the molding material must be integrally molded, so it is necessary to make sure that the metal wires and metal parts are not tightly connected. Without proper adhesion, it is impossible to protect the interior from changes in the external environment, which is the original purpose of sealing. Epoxy resin molding materials, silicone resin molding materials, diallyl phthalate resin molding materials, unsaturated polyester resin molding materials, etc. are generally used as sealing materials for such sealing, but they do not adhere well to metal. Epoxy resin molding materials with excellent properties are the most widely used. However, this epoxy resin molding material has poor flowability and storage stability, and usually needs to be stored in a freezer.
The drawback was that the flowability deteriorated significantly when left at room temperature during molding operations. Also,
Unsaturated polyester resin molding materials, diallyl phthalate resin molding materials, and silicone resin molding materials are
Although it is superior to epoxy resin in terms of flowability and storage stability, its use is currently limited to low-grade electrical parts with a low sealing level because of its poor adhesion to metals. Furthermore, when molding a large number of pieces by injection or transfer molding as described above, a molding material that maintains fluidity for a long injection time and has a fast curing rate is required. The present invention has been made in view of the above points, and has excellent preservability, excellent adhesion to metal parts, and can take a long injection time and can be cured quickly. The object of the present invention is to provide an unsaturated polyester resin composition. The present invention will be explained in detail below. The unsaturated polyester resin composition according to the present invention includes an unsaturated polyester resin, copolymerizable monomers, an unsaturated epoxy resin, and two different decomposition temperatures.
It is a composition obtained by blending inorganic fillers, mold release agents, colorants, flame retardants, inorganic and organic fibers, and thoroughly mixing or kneading the composition with at least one curing catalyst. As the unsaturated polyester resin, commonly used ones can be used, such as isophthalic acid, orthophthalic acid, phthalic anhydride, succinic acid, adipic acid, sebacic acid, endomethylenetetrahydrophthalic anhydride, chlordic acid, etc. Saturated dibasic acid, polyhydric alcohol such as ethylene glycol, dipropylene glycol, 1,3-butanediol, hydrogenated bisphenol, neopentyl glycol, isopentyl glycol, 1,6 hexanediol, maleic acid, maleic anhydride It is obtained by reacting an acid, an unsaturated dibasic acid such as fumaric acid, itaconic acid, etc. according to a conventional method. Examples of copolymerizable monomers include those having copolymerizability with unsaturated polyester resins such as styrene, t-butylstyrene, chlorostyrene, divinylbenzene, diallyl phthalate, vinyltoluene, and acrylic esters, and having unsaturated groups. or a prepolymer thereof can be used. Copolymerizable monomers are used to improve the flowability and crosslinking density of the molding material, and are used in amounts of 0.5 to 100 parts by weight of the unsaturated polyester resin.
It is recommended to use 100 parts by weight, preferably 3 to 100 parts by weight. If the copolymerizable monomer is less than 3 parts by weight, especially less than 0.5 parts by weight, based on 100 parts by weight of the unsaturated polyester resin, sufficient flow for molding will not be obtained and the molded product will become blurred, and if it exceeds 100 parts by weight, This is undesirable because it lowers the mechanical strength of the molded product and deteriorates the appearance of the molded product. As the unsaturated epoxy resin, use a copolymerizable unsaturated epoxy resin obtained by reacting a copolymerizable unsaturated monocarboxylic acid such as oleic acid, methacrylic acid, or acrylic acid with a bisphenol type epoxy resin. Can be done. In addition, as such unsaturated epoxy resins, those having an average bisphenol skeleton of 0 to 1 and those having a molecular weight of 2 to 10, that is, those having n of 0 to 1 and those having a molecular weight of 2 to 10 in the general formula shown below. - It is best to use two types of agents with different reactivities in combination. (R is, for example, H, CH ₃ , R' is, for example, CH ₂ ,
CHCH ₃ , CH ₃ -C-CH ₃ ) By using an unsaturated epoxy resin, the adhesion between the molded product and the metal insert is improved. It is preferable to use 10 to 300 parts by weight. If the amount of the unsaturated epoxy resin exceeds 300 parts by weight per 100 parts by weight of the unsaturated polyester resin, problems will arise in the storage stability of the molding material and the moldability will deteriorate; if it is less than 10 parts by weight, the molding will be difficult. There is no improvement in the adhesion between the product and the metal insert, which is not desirable. Further, the unsaturated epoxy resin in which n=0 to 1 in the above general formula has high reactivity, so the curing speed is fast, and the crosslinking density is also high, so it is useful for improving mechanical properties and dimensional stability. In addition, unsaturated epoxy resins with n = 2 to 10, preferably n = 2 to 4, have the effect of slowing down the gel time and lengthening the injection time due to their large molecular weight and steric hindrance, but their curing properties does not cause any major harm. In other words, it not only hinders the curing catalyst, which attacks and activates unsaturated groups above the decomposition temperature of the curing reaction initiator, but also suppresses its action as a crosslinking agent for a certain period of time, but the system as a whole is extremely Because it is active, there is a limit even if the unsaturated epoxy resin with n = 2 to 10 (2 to 4) rotates freely in the free volume and suppresses the effects of the above components, and eventually crosslinking progresses and hardening occurs. However, since the activation level of the entire system is high and the phenomenon of radical scavenging is not a phenomenon, the curing progresses rapidly after gel curing has started. Gel time and curing rate are adjusted by the decomposition temperature of the curing catalyst used and the molecular weight of the unsaturated epoxy resin. In this case, inhibitors are commonly used to lengthen the gel time, but ordinary inhibitors, such as phenol derivatives, parabenzoquinone, and hydroquinone, are highly effective below the decomposition temperature of the curing catalyst; If the temperature exceeds that range, the radical scavenging ability becomes insufficient, and as a result, the gel time at or above the decomposition temperature of the catalyst is close to zero, making it impossible to obtain fluid stability. Furthermore, even if the amount of inhibitor used is increased, no improvement in the effect on gel time is observed, and adding too much may not only slow down the curing speed but also increase mold shrinkage and adversely affect physical properties. Furthermore, when using a large multi-cavity mold, the variation in mold temperature increases, but if a large amount of inhibitor is used at this time, the molding temperature condition will be within a very limited temperature range of 5 to 10 degrees Celsius. Therefore, there is a risk that filling defects may occur or that molding material may remain in the cavity due to insufficient curing. Next, as a curing catalyst, organic peroxides such as hydroperoxide, dialkyl peroxide, peroxyketal, peroxyester, and diacyl peroxide can be used, but the decomposition temperature to obtain a half-life of 10 hours is 10~30
It is preferable to use a combination of two or more types of curing catalysts having different degrees Celsius. When two or more types of curing catalysts having decomposition temperatures different by 10 to 30°C are used in combination, it is possible to obtain a molded article that is uniformly cured over a wide temperature range. In other words, if the average skeleton of unsaturated epoxy resin is large, the reactivity of the molding material will be poor and shrinkage will be large. curing catalyst, and high-temperature catalysts with higher decomposition temperatures, such as Percyl H and Perhexine.
When used in conjunction with a curing catalyst such as 2.5B, it is possible to perform molding at high to medium temperature ranges, that is, around 150 to 180°C, and mold temperatures can vary by 10 to 20°C in large molds. Even if there is a problem, molding is possible. It is more preferable to use a curing catalyst that decomposes in an intermediate temperature range. The curing catalyst is preferably used in an amount of 1 to 3 parts by weight per 100 parts by weight of the unsaturated polyester resin. When a single curing catalyst is used, the molding temperature range is narrow, and the mold temperature for large molds varies widely, so when performing high-temperature molding to perform high-speed molding, it is difficult to stabilize the flow of the molding material. However, by using a composite catalyst and using two types of unsaturated epoxy resins with different average skeletons, the gel time at high temperatures can be extended and the fluidity time can be extended. Moreover, it can be used in large molds, has good flow stability at high temperatures, and can be poured for a long time, and can be made into a molding material that cures quickly in about 60 seconds or less. As described above, according to the present invention, not only is there no problem of poor storage stability as in the case of epoxy resin composition molding materials, but also the copolymerizable monomers improve flowability during molding. It is possible to perform multi-cavity molding of small molded products by transfer molding and injection molding.
Furthermore, the unsaturated epoxy resin can further improve the adhesion between the molded product and the metal insert, and the use of a composite curing catalyst improves flow stability over a wide molding temperature range, making it possible to cycle up. It is something that becomes. Next, the present invention will be explained by examples. <Example 1> Unsaturated polyester resin (Nippon Shokubai Kagaku N
-317) 100 parts by weight, unsaturated epoxy resin synthesized based on bisphenol type epoxy resin with average skeleton n=0.5 (unsaturated epoxy resin A) 50
Parts by weight, n=4 (unsaturated epoxy resin B)
50 parts by weight, styrene 20 as copolymerizable monomers
Parts by weight, 3 parts by weight of Perhexine 2.5B as a curing catalyst, and 3 parts by weight of Perbutyl Z were placed in a kneader and thoroughly mixed. Next, additives were added in the order of decreasing oil absorption according to the formulation shown in Table 1, and the mixture was kneaded until a uniform paste was formed to obtain an unsaturated polyester resin molding material.

[Table] <Example 2> An unsaturated polyester resin molding material was obtained in the same manner as in Example 1, except that 2 parts by weight of each of Perhexin 2.5B, Percyl D, and Perbutyl Z were used as curing catalysts. <Example 3> An unsaturated polyester resin molding material was obtained in the same manner as in Example 1, except that 30 parts by weight of unsaturated epoxy resin A and 70 parts by weight of unsaturated epoxy resin B were used. <Comparative Example 1> An unsaturated polyester resin molding material was obtained in the same manner as in Example 1, except that 200 parts by weight of unsaturated polyester resin was used instead of unsaturated epoxy resins A and B. <Comparative Example 2> An unsaturated polyester resin molding material was obtained in the same manner as in Example 1, except that 150 parts by weight of the unsaturated polyester resin was used instead of the unsaturated epoxy resin B. <Comparative Example 3> An unsaturated polyester resin molding material was obtained in the same manner as in Example 1, except that only 6 parts by weight of Percmill D was used as a curing catalyst. Examples 1 to 3 and Comparative Examples 1 to 3 as described above
With ^the molding material obtained in
A molded product with metal inserts was molded under the conditions of 240 pieces. The molded product is made of resin 1 with a=10, b=8, c=5 and d=5, e as shown in Figure 1 a and b.
= 1 (unit: mm) metal piece 2 was obtained as an insert. As shown in FIG. 2, this metal piece 2 is inserted into the resin 1 and is divided into four parts, each of which is labeled A and B. Metal piece 2 and resin 1
A red ink test was conducted to measure the adhesion with the paper. In other words, a 0.5% by weight rhodamine solution is placed in a 3ι three-necked flask, a condenser and a thermometer are attached to the three-necked flask, and the flask is heated. Once boiling begins, the molded product is suspended in the flask and heated. After continuing boiling for the time shown in Table 2, the molded product was taken out and left at room temperature for 1 hour to destroy the molded product.
The adhesive surface between the insert metal piece 2 and the resin 1 was observed. The evaluation is carried out in such a way that a rhodamine solution with a unique bright red color infiltrates between the insert metal piece 2 and the resin 1. If no rhodamine is observed in the part B of the metal piece 2, it is marked as ○, and in the part A. When rhodamine could not be confirmed but was confirmed in part B, it was marked as △, and when rhodamine was confirmed in part A, it was marked as ×, and the results were as shown in Table 2.

【table】

[Table] In addition, when molding the above molded product, we intentionally varied the mold temperature by partially disconnecting the heater, and experimented with injection times ranging from 5 to 30". The moldability was determined. Table 2 shows the moldability based on the overall mold temperature when no scratches, pinholes, unfilling, or molded product remained on the mold occurred in the molded product, Injection time and curing time are shown.The minimum curing time is defined as the time when the molded product does not remain on the mold and the runner breaks during removal.

[Table] From the results in Tables 2 and 3, it is confirmed that Examples 1 to 3 are superior to Comparative Examples in both adhesion to metal and moldability.

[Brief explanation of the drawing]

Figures 1 a and b are front and side views of the molded product, Figure 2
The figure is a front view of the metal piece. 1 is a resin, and 2 is a metal piece.

Claims (1)

[Scope of Claims] 1. An unsaturated polyester resin, copolymerizable monomers that are reactive with the unsaturated polyester resin and have an unsaturated group, an unsaturated epoxy resin, and two or more types of curing catalysts with different decomposition temperatures. An unsaturated polyester resin composition comprising: 2. The unsaturated polyester resin composition according to claim 1, which comprises 0.5 to 100 parts by weight of copolymerizable monomers based on 100 parts by weight of the unsaturated polyester resin. 3. The unsaturated polyester resin composition according to claim 1 or 2, characterized in that 10 to 300 parts by weight of an unsaturated epoxy resin is blended with 100 parts by weight of the unsaturated polyester resin. 4. Claims characterized in that the unsaturated epoxy resin is a bisphenol type, and is made by using two types of unsaturated epoxy resins, one with an average skeleton number of 0 to 1 and one with an average skeleton number of 2 to 10. The unsaturated polyester resin composition according to item 1, item 2, or item 3. 5. Claim 1, characterized in that the curing catalyst is an organic peroxide, and is a composite of two or more curing catalysts with decomposition temperatures different from 10 to 30°C.
The unsaturated polyester resin composition according to item 1 or 2 or 3 or 4.