JPH03404B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a resin composition for powder molding, and more particularly to a resin composition that can be cured into a resin with excellent heat resistance by heating.

In recent years, there has been a demand for lighter weight transportation machines from the perspective of energy conservation, and the use of organic polymer materials for structural members around engines and oil-free bearings, for example, is being considered. Furthermore, organic polymer materials are being actively used in solar heating equipment and the like, and these materials are required to have a high degree of heat resistance.

On the other hand, in recent years, as electrical equipment has become larger in capacity, smaller and lighter, operating temperatures have risen, and electronic components are required to have higher density and higher reliability. There is a strong need to develop organic polymer materials that have excellent electrical properties and mechanical strength even at high temperatures.

Traditionally, epoxy resins and silicone resins have been mainly used for these applications, but the former has well-balanced properties such as adhesiveness, mechanical strength, and electrical properties, but the upper limit of the operating temperature is 180°C.
℃, and it is becoming difficult to meet the above requirements for heat resistance. On the other hand, although the latter has excellent heat resistance and dielectric properties, it cannot be used satisfactorily for the above-mentioned applications because of its low adhesiveness and low mechanical strength at high temperatures. In addition, there are organic polymer materials that can withstand temperatures above 180°C, such as polyimide resin, diphenyl ether resin, and polytetrafluoroethylene, but these have poor moldability and are expensive, so they are extremely difficult to use as molding materials. is restricted to.

In view of the above circumstances, an object of the present invention is to provide a polyisocyanurate resin composition that can be converted into a polymer having good moldability and curing properties and excellent heat resistance.

Polyisocyanurate polymers are obtained by trimerizing organic polyisocyanates, but the decomposition temperature of the isocyanurate rings that make up the polymer chain is
Because it has a temperature of over 300°C, its application as a heat-resistant and flame-retardant material has been considered for some time.

As a molding method for such polyisocyanurate resin, a trimerization catalyst is present in liquid organic polyisocyanate, and molding is carried out in liquid form, but the pot life is short and it takes a long time to cure. In the case of organic polyisocyanates, which require high vapor pressure and have a high vapor pressure, there is a problem of environmental pollution during molding operations.

Therefore, an organic polyisocyanate and an epoxy resin are reacted in the presence of oxazolidone and an isocyanurate-forming catalyst to obtain a solid prepolymer containing isocyanate groups, which is pulverized and mixed with a heterocycle-forming catalyst for powder molding. Resin compositions are increasingly being used. However, such resin compositions for powder molding have disadvantages in storage stability because the isocyanurate catalyst is dissolved in the resin, and there is also a risk of gelation during the production of the prepolymer, making it undesirable. I had a problem.

The present invention was made as a result of intensive research to obtain a powder molding resin composition having excellent storage stability, curability, heat resistance, and moldability under the above circumstances. This is a powder molding resin composition comprising a solid polyisocyanate containing a ring and/or a uretidione ring in its structure, triethylene melamine, and, if necessary, a solid resin.

The isocyanurate ring-containing solid polyisocyanate of the present invention can be prepared by using, for example, alicyclic diisocyanates, aliphatic substituted aromatic diisocyanates, or aromatic diisocyanates as an isocyanurate ring-forming catalyst (for example, as a tertiary amine, triethylenediamine, tris( (dimethylaminomethyl) phenol, as weak acid salts of alkali metals, potassium acetate, potassium octenoate, potassium laurate, as strong alkaline substances, triethylammonium hydroxide, sodium ethylate, as heavy metal compounds, lead naphthenate, nickel octenoate, As an imidazole compound, 2-methylimidazole, 1-cyanoethyl-2-ethyl-
3-methylimidazole, etc.). Used in the production of solid polyisocyanates containing isocyanurate rings. Alicyclic diisocyanates are, for example, 1-
Isocyanate-3.3.5-trimethyl-5-isocyanatocyclohexane, hexahydrotolylene-2,4- or -2,6-diisocyanate, cis- or trans-cyclohexane-1,4-diisocyanate, dicyclohexylmethane-4,4'-diisocyanate, ω.ω' -diisocyanatomethylcyclohexane, etc. In addition, aliphatic substituted aromatic diisocyanates include, for example, xylylene-1.3-
or -1.4-diisocyanate, 2.2-dimethyl-2-isocyanatoethyl-p-phenyl isocyanate, and the like. Furthermore, aromatic diisocyanates may include, for example, tolylene-2.4- or 2.6-
Examples include diisocyanate, naphthylene-1.5-diisocyanate, bitlylene diisocyanate, m- or p-phenylene diisocyanate, and polyphenylpolymethylene polyisocyanates of the type obtained by condensing aniline with formaldehyde and then phosgenating it. These can be used singly or as a mixture of two or more, but the above-mentioned diisocyanates modified with urethane bonds, urea bonds, allophanate bonds, amide bonds, etc. can also be exemplified. Isocyanurate ring-containing solid polyisocyanates can also be obtained by phosgenating isocyanurate ring-containing polyamines, but because they are easily available industrially, they can also be obtained by trimerizing tolylene diisocyanate or diphenylmethane diisocyanate. Particularly suitable are

The solid polyisocyanate containing a uretidione ring of the present invention can be prepared by using, for example, an aromatic diisocyanate as a uretidione formation catalyst, a tertiary amine (such as triethylamine, pyridine, triethylenediamine, etc.) or a phosphine (such as tributylphosphine). , dibutylphenylphosphine, etc.) and dimerize it. Aromatic diisocyanates used in the production of such uretidione ring-containing solid polyisocyanates include, for example, tolylene-2.6- or -2.4-diisocyanate,
p- or m-phenylene diisocyanate, diphenylmethane-2.4'- or 4.4'-diisocyanate, diphenyl ether-4.4'-diisocyanate, 1.5-naphthylene diisocyanate, 2.2-
Dimethyl-2-isocyanatoethyl-p-phenyl isocyanate is mentioned. Among these, uretidione ring-containing solid polyisocyanates derived from tolylene-2,4-diisocyanate or diphenylmethane diisocyanate, which are industrially easily available, are particularly preferred.

Solid polyisocyanates containing isocyanurate rings or uretidione rings have poor storage stability if they contain trimerization or dimerization catalysts, so it is more preferable to remove these or decompose and neutralize them. The above-mentioned solid polyisocyanate treated in this manner can be stably stored as a powder for a long period of time in a moisture-free atmosphere.

Furthermore, the solid polyisocyanate has a melting point of
The melting point is preferably 140 to 250°C, and those with a molecular weight as low as possible are preferred because they are easy to flow.

In addition, in the present invention, solid polyisocyanates or liquid polyisocyanates that do not contain isocyanurate rings, uretidione rings, etc. in their structure may be used as long as the resin composition of the present invention is in the form of powder. Can be done.

Triethylene melamine in the present invention is used in an amount of 0.1 to 10 parts by weight per 100 parts by weight of the solid polyisocyanate, is pulverized together with or separately from the solid polyisocyanate, and has a particle size of 100 mesh or more.
Preferably it is finely ground to 300 mesh. Inorganic fillers such as quartz and talc, lubricants, colorants, stabilizers, etc. can also be added to these pulverized products.

In the present invention, other solid resins such as general thermosetting resins and thermoplastic resins can be blended as necessary. Examples of thermosetting resins include epoxy resins, phenoxy resins, phenolic resins, unsaturated polyester resins, and amino resins, which are useful for improving flexibility, electrical properties, and economic efficiency. Examples of the thermoplastic resin include polyamide resin, acrylic resin, polyurethane rubber, and polyester resin.

Such a powdered resin composition is molded using a compression molding machine, and a particularly preferred molding method is as follows:
This method uses a transfer molding machine. In this case, the powdered resin composition is previously formed into tablets using a tablet machine, and the tablets are filled into a transfer molding machine and molded at 140 to 250°C. The molding temperature is related to the activation of triethylene melamine, and in particular triethylene melamine decomposes at 149°C to accelerate the polyisocyanurate reaction, so it is preferably molded at 150°C or higher. Furthermore, molding at a high temperature of 230° C. or higher is not very preferable because it increases the curing shrinkage rate and increases the internal stress in the cured product, and because it tends to cause a foaming reaction due to the formation of carbodiimide bonds of isocyanate groups.

Further, the powdered resin composition of the present invention can be applied by bringing it into contact with a heated material to be coated, or by heating and melting it and then spraying it. In order to improve the physical properties after curing, the molded article or coated article can be further heat treated.

Next, the present invention will be explained in more detail with reference to Examples. However, the present invention is not limited to these examples.

Manufacture of trimmer body 1 Nitrogen gas introduction pipe, thermometer, calcium chloride pipe,
500 g of tolylene-2,4-diisocyanate was placed in a 4-necked flask equipped with a stirrer, and the internal temperature was
While maintaining the temperature at 40℃ and stirring thoroughly, 10ml of ethyl acetate containing 0.1% potassium laurate was added and stirring was continued for about 5 hours, resulting in an NCO content of 38.5.
%. At this point benzoyl chloride 0.1%
9 ml of ethyl acetate was added thereto, the internal temperature was raised to 60°C, the mixture was stirred for about 1 hour, and the reaction was stopped. 6 contents
The mixture was added to n-hexane with stirring, the resulting insoluble matter was filtered and dried to obtain 202 g of white fine powder. The infrared absorption spectrum (hereinafter abbreviated as IR) shows that this material has an absorption based on isocyanate groups at 2250 cm ^-1 and 1705 cm ^-1
and tolylene, which has a strong absorption at 1420 cm ^-1 due to the carbonyl bond of the isocyanurate ring.
It is a trimer of 2.4-diisocyanate and has a softening point of 110℃.

Production of trimer body 2 Millionate was placed in the same reaction vessel as in Example 1.
Pour 500 g of MTL (Japan Polyurethane Industrial Products, carbodiimide-modified liquid MDINCO content 29.0%), maintain the internal temperature at 25°C, and add 20 ml of ethyl acetate containing 0.1% potassium octylate while stirring thoroughly.
added. Pour this into a Teflon-coated vat to a depth of 5 mm, and pour it under a nitrogen stream for 25 minutes.
When the mixture was allowed to stand at ℃ for 24 hours, a glassy solid with a melting point of 120 ℃ was obtained. This one is 2250 by IR
It has an absorption based on isocyanate groups in cm ^-1 ,
It also has strong absorption at 1705 and 1420 cm ^-1 due to the carbonyl bond of the isocyanurate ring, and is a trimerized modified product of diphenylmethane diisocyanate.

Example 1 Tolylene-2.4 obtained in Preparation 1 of trimer body
- Diisocyanate trimer 100g, Araldite ECN1273 (Ciba Geigy, novolac type, epoxy equivalent 225, melting point 73°C) 50g, Fuselex RD-8 (Tatsumori, fused silica powder) 250
g, KBM403 (manufactured by Shin-Etsu Chemical Co., Ltd., epoxy silane coupling agent) 2 g, Alflow p-10 (manufactured by Nippon Oil & Fats Co., Ltd., lubricant) 2 g, and triethylene melamine 3 g were mixed in a Henschel mixer and roughly pulverized to obtain a molding material. . This material was molded at 150°C for 3 minutes at 100psi, after-cured at 180°C for 3 hours and 220°C for 3 hours, and a bending test piece (dimensions 5 x 12 x
120mm). The bending strength of this product at 180°C was 205 Kg/cm ² with almost no deterioration even after being left at 220°C for 30 days. In this molded product, absorption based on isocyanate groups almost disappeared at 2250 cm ^-1 by IR, and strong absorption based on carbonyl bonds of the isocyanurate ring increased and appeared at 1705 cm ^-1 and 1420 cm ^-1 .

Example 2 150g of MDI trimer block obtained in trimer production 2, Fuselex RD-
8150g, KBM403 3g, Alflo-p-102g,
A molding material was obtained by mixing and coarsely pulverizing 3 g of triethylene melamine in a Henschel mixer. This material was molded at 150° C. for 3 minutes at 100 psi, and then after-cured at 180° C. for 3 hours and 220° C. for 3 hours to prepare bending test pieces. The bending strength of this product at 180°C was 673 kg/cm ² with almost no deterioration even after being left at 220°C for 30 days. In this molded product, absorption based on isocyanate groups almost disappeared at 2250 cm ^-1 and 1750 cm ^-1 and 1402 cm ^-1
The strong absorption based on the carbonyl bond of the isocyanurate ring increased.

Example 3 Desmodyur TT (Bayer product TDI dimer) 100 g, 1.5-naphthylene diisocyanate 50 g, Desmodyur N (Bayer product) 50
g, Araldite ECN1273 50g, Fuserex RD-8306g, coupling agent KBM403 3
g, Alflo-p-103 g, and triethylene melamine 3 g were mixed and coarsely ground in a Henschel mixer to obtain a molding material. Heat this material at 150℃ for 3 minutes.
After molding at 100psi, 180℃ for 3 hours and 220℃
After curing for 3 hours, a bending test piece was prepared. The bending strength of this product at 180℃ is 220℃
Even after being left for 30 times, there was almost no deterioration and the weight was 254 kg/cm ² . In this molded product, absorption based on the isocyanate group almost disappeared at 2250 cm ^-1 and absorption based on the carbonyl bond of the isocyanurate ring appeared at 1705 cm ^-1 and 1420 cm ^-1 by IR.

Example 4 IPDI-T1890 (trimer of isophorone diisocyanate, melting point approximately 85°C, product of Hiels) 150
g, Hughes Rex RD-18 150g, KBM403
3 g, Alflo-p-102 g, and 4 g of triethylene melamine were mixed and coarsely ground in a Henschel mixer to obtain a molding material. This material was heated to 150℃ for 3 minutes.
After molding at 100psi and after-curing at 180℃ for 6 hours, the 2250
The strong infrared absorption based on the isocyanate group at cm ^-1 almost disappeared, and strong absorption based on the carbonyl bond of the isocyanurate ring appeared at 1705 and 1420 cm ^-1 . The bending strength of the bending test piece molded as described above at 150°C was 267 Kg/cm ² with almost no deterioration even after being left at 220°C for 30 days.

Comparative Example 1 A shell material was obtained in the same manner as in Example 1, except that 0.3 g of 1-cyanoethyl-2-ethyl-3-methylimidazole was used instead of 3 g of triethylene melamine. When a bending test piece was prepared under the same conditions, minute cracks were generated in the test piece after 3 hours of after-cure at 220°C, and the heat resistance was poor.

Comparative Example 2 A molding material was obtained in the same manner as in Example 2, except that 0.2 g of potassium linolenate was used instead of 3 g of triethylene melamine. When a bending test piece was prepared under the same conditions, voids were observed in the test piece after 3 hours of after-curing at 220°C, and the heat resistance was poor.

Comparative Example 3 A molding material was obtained in the same manner as in Example 3, except that 0.1 g of triethylene diamine was used instead of 3 g of triethylene melamine. When a bending test piece was prepared under the same conditions, minute cracks were generated in the test piece after 3 hours of after-cure at 220°C, and the heat resistance was poor.

Comparative Example 4 A molding material was obtained in the same manner as in Example 4 except that 0.2 g of triethylene diamine was used instead of 3 g of triethylene melamine. When a bending test piece was prepared under the same conditions, fine cracks were generated in the test piece after 6 hours of after-cure at 180°C, and the heat resistance was poor.

Claims (1)

[Claims] 1. A powder molding resin composition comprising a solid polyisocyanate containing an isocyanurate ring and/or uretidione ring in its structure, triethylene melamine, and, if necessary, a solid resin.