JP2015089941A - Polyurethane resin composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polyurethane resin composition having excellent thermal durability under cooling-and-heating cycles.SOLUTION: The polyurethane resin composition includes a hydroxy group-containing compound, an isocyanate group-containing compound, and an inorganic filler (D). The hydroxy group-containing compound includes polybutadiene polyol (A). The isocyanate group-containing compound includes an isocyanurate-modified polyisocyanate compound (B) and an allophanate-modified polyisocyanate compound (C).

Description

  The present invention relates to a polyurethane resin composition.

Conventionally, electronic circuit boards and electronic components have been sealed using polyurethane resin or the like in order to prevent external contamination. In recent years, as electronic parts and the like have a longer life, they are used under a high temperature condition for a long period of time, and thus have excellent heat resistance.

In view of such a point, in order to solve the above problems, the present inventors have made polybutadiene polyol, castor oil-based polyol, and polyisocyanate compound excellent in heat resistance even in a sealed and high-temperature environment such as the inside of a transformer case. A polyurethane resin composition containing a modified product of isocyanurate has been disclosed (Patent Document 1).

In recent years, there has been a demand for a polyurethane resin composition that not only has excellent heat resistance under a high temperature environment but also has excellent heat resistance under a high temperature / low temperature environment, that is, excellent thermal durability under a cold cycle. Yes.

On the other hand, a urethane elastomer having improved workability and reactivity by using allophanate-modified, isocyanurate-modified and prepolymer of hexamethylene diisocyanate (Patent Document 2), prepolymer having allophanate group and isocyanurate group Has been disclosed for urethane elastomers that have been dissolved in organic solvents and improved coating film properties (Patent Document 3), but these structures are excellent in thermal durability under a cold cycle. Not disclosed.

JP 2011-1426 A JP 2004-263108 A JP 2010-215857 A

This invention is made | formed in view of the said problem, and makes it a subject to provide the polyurethane resin composition excellent in the thermal durability under a thermal cycle.

As a result of intensive studies to solve the above problems, the inventors of the present invention can solve the above problems by using a polyol having a specific structure, an isocyanate group-containing compound, and an inorganic filler as a polyurethane resin composition. As a result, the present invention has been completed.

That is, the polyurethane resin composition of the present invention is a polyurethane resin composition containing a hydroxyl group-containing compound, an isocyanate group-containing compound and an inorganic filler (D), wherein the hydroxyl group-containing compound contains a polybutadiene polyol (A). The isocyanate group-containing compound contains an isocyanurate-modified product (B) of a polyisocyanate compound and an allophanate-modified product (C) of a polyisocyanate compound.

The polyurethane resin composition of the present invention is characterized in that the polyisocyanate compound is hexamethylene diisocyanate.

In the polyurethane resin composition of the present invention, the mass mixing ratio of (B) and (C) is (B):
(C) = 25: 75 to 75:25.

  The polyurethane resin composition of the present invention is used for electric and electronic parts.

By using the polyurethane resin composition of the present invention, it is possible to obtain a polyurethane resin excellent in thermal durability under a cold cycle.

The polyurethane resin composition of the present invention contains a hydroxyl group-containing compound, an isocyanate group-containing compound, and an inorganic filler (D).

  The hydroxyl group-containing compound used in the present invention contains polybutadiene polyol (A).

As the polybutadiene polyol (A) used in the present invention, those conventionally known for use in polyurethane resins can be used, and the average hydroxyl value is preferably 20 to 120 mgKOH / g.

The compounding quantity of polybutadiene polyol (A) is 0-4 with respect to a polyurethane resin composition.
It is preferably 0% by mass, more preferably 1 to 35% by mass, and even more preferably 2 to 30% by mass.

It is also a preferred embodiment that the hydroxyl group-containing compound used in the present invention contains castor oil-based polyol (E). Since it contains two types of polyol compounds, the polybutadiene polyol (A) and the castor oil-based polyol (E), the compatibility of the polyurethane resin composition during mixing is excellent, and the heat of the polyurethane resin under the cold cycle The durability is better. As the castor oil-based polyol, castor oil, castor oil fatty acid, and polyols produced using hydrogenated castor oil or hydrogenated castor oil fatty acid hydrogenated to these can be used. Examples of such polyols include castor oil, a transesterification product of castor oil and other natural fats, a reaction product of castor oil and polyhydric alcohol, an esterification reaction product of castor oil fatty acid and polyhydric alcohol, and alkylene oxide added thereto. Examples include polymerized polyols.

It is preferable that the compounding quantity of a castor oil type polyol (E) is 0-40 mass% with respect to a polyurethane resin composition, It is more preferable that it is 2-35 mass%, 3-30 mass%
More preferably.

The polybutadiene polyol (A) and the castor oil-based polyol (E) are obtained by reacting with a polyisocyanate compound isocyanurate-modified product (B) and a polyisocyanate compound isocyanurate-modified product (C) under hydroxyl-excess conditions. It may be a urethane prepolymer.

The mixing ratio of the polybutadiene polyol (A) and the castor oil-based polyol (E) is preferably 100/0 to 40/60 (mass ratio). By setting it within the above range, the compatibility at the time of mixing the polyurethane resin composition and the thermal durability of the polyurethane resin under a cooling / heating cycle become better.

The isocyanate group-containing compound used in the present invention contains an isocyanurate-modified product (B) of a polyisocyanate compound and an allophanate-modified product (C) of a polyisocyanate compound. When the isocyanate group-containing compound contains the isocyanurate-modified product (B) of the polyisocyanate compound, the polyurethane resin has excellent thermal durability under a cooling / heating cycle. Although the reason is not clear, it can be presumed to be due to the hydrolysis-inhibiting effect of the isocyanurate-modified product of the polyisocyanate compound and the flexible structure of the allophanate-modified product (C) of the polyisocyanate compound.

Examples of such isocyanurate-modified (B) and allophanate-modified (C) of polyisocyanate compounds include aliphatic polyisocyanate compounds, alicyclic polyisocyanate compounds, aromatic polyisocyanate compounds, and araliphatic polyisocyanate compounds. Isocyanurate modified and allophanate modified.

Examples of the aliphatic polyisocyanate compound include tetramethylene diisocyanate, dodecamethylene diisocyanate, hexamethylene diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, 2,4,4-trimethylhexamethylene diisocyanate, lysine diisocyanate, 2-methylpentane- 1,5-diisocyanate, 3-
And methylpentane-1,5-diisocyanate.

Examples of the alicyclic polyisocyanate compound include isophorone diisocyanate, hydrogenated xylylene diisocyanate, 4,4′-dicyclohexylmethane diisocyanate, 1,4-
Cyclohexane diisocyanate, methylcyclohexylene diisocyanate, 1,3-
Bis (isocyanatomethyl) cyclohexane and the like can be mentioned.

Examples of the aromatic polyisocyanate compound include tolylene diisocyanate, 2,2′-diphenylmethane diisocyanate, 2,4′-diphenylmethane diisocyanate, 4,
4'-diphenylmethane diisocyanate (MDI), 4,4'-dibenzyl diisocyanate, 1,5-naphthylene diisocyanate, xylylene diisocyanate, 1,3-
Examples thereof include phenylene diisocyanate and 1,4-phenylene diisocyanate.

Examples of the araliphatic polyisocyanate compound include dialkyldiphenylmethane diisocyanate, tetraalkyldiphenylmethane diisocyanate, and α, α, α, α-tetramethylxylylene diisocyanate.

In addition, either or both of the polyisocyanate compound isocyanurate-modified product (B) and the polyisocyanate compound allophanate-modified product (C) may be used as the polyisocyanate compound isocyanurate-modified product (B) and An isocyanate group-terminated urethane prepolymer obtained by reacting an allophanate-modified polyisocyanate compound (C) with a polybutadiene polyol (A) and / or a castor oil-based polyol (E) can also be used.

Among these, from the viewpoints of reactivity, viscosity, and workability, an aliphatic polyisocyanate compound or an alicyclic polyisocyanate compound is preferable, and an isocyanurate-modified product of hexamethylene diisocyanate is particularly preferable.

The isocyanurate-modified product (B) of the polyisocyanate compound and the allophanate-modified product (C) of the polyisocyanate compound have a mass mixing ratio of (B) :( C) = 25: 75-7.
5:25 is preferable, and (B) :( C) = 30: 70 to 60:40 is more preferable. These ranges are preferred in terms of thermal durability, reactivity, viscosity, and workability of the polyurethane resin under high temperature and under a cold cycle.

These isocyanurate-modified products (B) of polyisocyanate compounds and allophanate-modified products (C) of polyisocyanate compounds may be used alone or in combination of two or more.

The polyurethane resin of the present invention has a molar ratio of isocyanate group to hydroxyl group (NCO / OH).
Is preferably 0.5 to 1.5. This is because if the molar ratio of isocyanate group to hydroxyl group is smaller than this range, curing failure may occur or the heat resistance of the resulting resin may be reduced, and if it exceeds this range, curing failure may occur.

Examples of the inorganic filler (D) used in the present invention include alumina, aluminum hydroxide,
Aluminum nitride, boron nitride, magnesium hydroxide, magnesium oxide and the like can be mentioned. Of these, alumina, magnesium oxide, aluminum nitride, and boron nitride are preferable because of excellent heat dissipation.

40-95 mass% is preferable with respect to a polyurethane resin composition, as for the compounding quantity of an inorganic filler (D), 50-90 mass% is more preferable, and 60-85 mass% is further more preferable. When the blending amount of the inorganic filler (E) is less than the above range, the heat dissipation effect tends to be small. There is.

If necessary, the polyurethane resin composition of the present invention may contain a plasticizer (F).

Examples of such plasticizers (F) include phthalic acid esters such as dioctyl phthalate, diisononyl phthalate, and diundecyl phthalate, adipic acid esters such as dioctyl adipate and diisononyl adipate, methyl acetyl ricinoleate, butyl acetyl ricinoleate, and acetyl. Castor oil ester such as triglyceride triglyceride, triglyceride triglyceride acetylated, trimellitic ester such as trioctyl trimellitate, triisononyl trimellitate, tetraoctyl pyromellitate,
Examples include pyromellitic acid esters such as tetraisononyl pyromellitate, phosphoric acid esters such as tricresyl phosphate, trisoxyrenyl phosphate, cresyl diphenyl phosphate, xylenyl phosphate, and triphenyl phosphate.

The blending amount when blending the plasticizer (F) is 0.0 with respect to the polyurethane resin composition.
It is preferable that it is 1-50 mass%, and it is more preferable that it is 0.1-40 mass%.
By setting the blending amount within the above range, the mixing viscosity at the time of production of the polyurethane resin composition can be further reduced without greatly reducing the heat resistance of the polyurethane resin composition.

In addition, polyols other than polybutadiene polyol (A) and a castor oil-type polyol (E) can be mix | blended with the polyol component used for this invention to such an extent that the effect of this invention is not impaired. Examples of such polyols include polyether polyols, polyester polyols, polycarbonate polyols, polyisoprene polyols, polybutadiene polyol hydrides, and polyisoprene polyol hydrides.

Moreover, various additives, such as a catalyst, an antioxidant, a hygroscopic agent, an antifungal agent, and a silane coupling agent, can be added to the polyurethane resin composition of the present invention as necessary. Examples of the silane coupling agent include alkoxysilanes, vinyl group-containing silane coupling agents, epoxy group-containing silane coupling agents, methacryl group-containing silane coupling agents, and acrylic group-containing silane coupling agents.

The polyurethane resin composition of the present invention preferably has a thermal conductivity in the range of 0.5 to 3 W / m · K.

Since the polyurethane resin obtained from the polyurethane resin composition of the present invention has thermal durability under a cooling and heating cycle, it can be suitably used for electrical and electronic parts that generate heat. Examples of such electric and electronic parts include transformers such as transformer coils, choke coils, and reactor coils, and equipment control bases. Electric and electronic parts using the polyurethane resin of the present invention can be used in electric washing machines, toilet seats, water heaters, water purifiers, baths, dishwashers, electric tools, automobiles, motorcycles, and the like.

Hereinafter, the polyurethane resin composition of the present invention and the polyurethane resin raw material composition of the present invention will be described in detail based on Examples and Comparative Examples. In the present specification, “parts” and “%” represent “parts by mass” and “mass%”, respectively, unless otherwise specified.

The raw materials used in Examples and Comparative Examples are shown below.
(Polybutadiene polyol (A))
A1: Polybutadiene polyol having an average hydroxyl value of 103 mgKOH / g
(Product name: Poly bd R-15HT, manufactured by Idemitsu Kosan Co., Ltd.)
A2: Polybutadiene polyol having an average hydroxyl value of 47 mgKOH / g
(Product name: Poly bd R-45HT, manufactured by Idemitsu Kosan Co., Ltd.)
(Castor oil-based polyol (E))
E1: Castor oil (Brand name: Castor oil, manufactured by Ito Oil Co., Ltd.)
E2: Castor oil fatty acid-polyhydric alcohol ester (trade name: URIC Y-403, manufactured by Ito Oil Co., Ltd.)
E3: Castor oil fatty acid-polyhydric alcohol ester
(Product name: HS 2G 160R, manufactured by Toyokuni Oil)
(Isocyanurate-modified polyisocyanate compound (B))
B1: Isocyanurate-modified product of hexamethylene diisocyanate
(Product name: Duranate TPA-100, manufactured by Asahi Kasei Chemicals Corporation)
B2: Isocyanurate-modified product of hexamethylene diisocyanate
(Product name: Duranate TLA-100, manufactured by Asahi Kasei Chemicals Corporation)
(Isocyanurate-modified polyisocyanate compound (C))
C: Allophanate modified product of hexamethylene diisocyanate
(Product name: Duranate A201H, manufactured by Asahi Kasei Chemicals Corporation)
(Inorganic filler (D))
D1: Aluminum hydroxide
(Product name: Heidilite H-32, Showa Denko)
D2: Aluminum hydroxide
(Product name: Aluminum hydroxide C-305, manufactured by Sumitomo Chemical)
(Plasticizer (F))
F1: Trixylenyl phosphate
(Product name: TXP, manufactured by Daihachi Chemical Industry Co., Ltd.)
F2: tricresyl phosphate
(Product name: TCP, manufactured by Daihachi Chemical Industry Co., Ltd.)
F3: Diundecyl phthalate
(Product name: Sunsizer DUP, manufactured by Shin Nippon Rika Co., Ltd.)
(Silane coupling agent (G))
G1: Decyltrimethoxysilane (trade name: KBM-3103, manufactured by Shin-Etsu Chemical Co., Ltd.)
G2: Vinyltrimethoxysilane (trade name: KBM-1003, manufactured by Shin-Etsu Chemical Co., Ltd.)
G3: 3-glycidoxypropyltrimethoxysilane (trade name: KBM-403, manufactured by Shin-Etsu Chemical Co., Ltd.)
G4: 3-methacryloxypropyltrimethoxysilane (trade name: KBM-503, manufactured by Shin-Etsu Chemical Co., Ltd.)
(Catalyst (H))
H: Dioctyltin dilaurate
(Product name: Neostan U-810, Nitto Kasei Co., Ltd.)
(Antioxidant (I))
I: pentaerythritol tetrakis [3- (3,5-di-tert-butyl-4-
Hydroxyphenyl) propionate]
(Product name: Irganox 1010, manufactured by Ciba Specialty Chemicals)

<Examples 1-22 and Comparative Examples 1-3>
The polyurethane resin composition of each Example and each comparative example was prepared according to the formulation shown in Table 1.
In preparation, among the components shown in Table 1, isocyanurate-modified polyisocyanate compound (B), allophanate-modified polyisocyanate compound (C) and catalyst (H
) Using a blender (trade name: Awatori Nertaro, manufactured by Shinky Corporation)
After mixing for 1 minute at m, the temperature was adjusted to 25 ° C. Subsequently, the polyisocyanate compound isocyanurate-modified product (B) adjusted to 25 ° C. and the polyisocyanate compound allophanate-modified product (C) are added to this mixture, and mixed at 2000 rpm for 30 seconds using the same mixer. Thereby, the polyurethane resin composition of each Example was obtained.

<Evaluation method>
(Compatibility)
Separately, components other than the inorganic filler (D), the plasticizer (F) and the catalyst (H) are mixed using the mixer, and allowed to stand at 25 ° C. for 5 minutes. Confirmed.
○: No turbidity ×: Turbidity

(Thermal conductivity)
The polyurethane resin composition was poured into a 6 cm × 12 cm × 1 cm mold, cured at 80 ° C. for 16 hours, then demolded, and then allowed to stand at 25 ° C. for 24 hours to test for thermal conductivity measurement. Created a piece. Thermal conductivity is measured using a thermal conductivity meter (QTM manufactured by Kyoto Electronics Industry Co., Ltd.)
-D3) was measured by the probe method.

(Heat resistance (Evaluation of thermal durability at high temperature))
1. Preparation of test piece The polyurethane resin composition was poured into a mold having a diameter of 5 cm and a height of 3 cm.
After curing for 6 hours, a test piece for heat resistance evaluation was prepared by removing the mold.
2. Evaluation of internal melt At 125 ° C, the polyurethane resin before and after the heat resistance test for 4 days was divided into two equal parts, the center hardness (type A) of the cut surface was measured according to JIS K6253, and the heat resistance test against the hardness before the heat resistance test The later hardness ratio was defined as hardness retention rate (%) and evaluated as follows.
○: Hardness retention is 60% or more ×: Hardness retention is less than 60%

(Heat resistance (Evaluation of thermal durability under cold cycle))
1. Preparation of test piece A test piece for heat resistance evaluation was prepared in the same manner as the test piece used for the thermal durability evaluation at the high temperature.
2. Measurement of stress Using an Instron universal testing machine, the lower part was fixed and the temperature was raised from 23 ° C to 125 ° C.
The difference in stress applied to the upper part before and after the temperature rise was read. The stress after the temperature rise was read after the stress reached equilibrium.
3. Evaluation of durability under a cooling cycle Before and after the cooling cycle under a condition of repeating 30 cycles of -10 ° C for 30 minutes, heating time of 1 hour, 125 ° C for 30 minutes, cooling time of 1 hour for 1 cycle Was evaluated. The ratio of the stress after the cooling cycle to the stress before the cooling cycle was defined as the stress retention rate (%) and evaluated as follows.
○: Stress retention is 75% or more and 125% or less ×: Hardness retention is less than 75% or greater than 125%

<Evaluation results>
As can be seen from Examples 1 to 22, the polyurethane resin composition of the present invention has a mixed viscosity in a usable range and is excellent in compatibility. Furthermore, it can be seen that the resulting polyurethane resin has good thermal conductivity and thermal durability under a cold cycle.

On the other hand, when only the isocyanurate-modified polyisocyanate compound (B) is used as the isocyanate group-containing compound as in Comparative Examples 1 and 2, the resulting polyurethane resin has poor thermal durability under a cold cycle. I understand.

Further, as in Comparative Example 3, when only an allophanate modified product (C) of a polyisocyanate compound is used as an isocyanate group-containing compound, a polyurethane is obtained when a polyisocyanate compound that is not an isocyanurate modified product is used. It can be seen that the thermal durability of the resin at high temperatures and the thermal durability under a cold cycle are inferior.

If the polyurethane resin composition of the present invention is used, the resulting polyurethane resin has excellent thermal durability and can be used in the fields of electrical products, electronic parts and the like.

Claims (4)

A polyurethane resin composition comprising a hydroxyl group-containing compound, an isocyanate group-containing compound and an inorganic filler (D),
The hydroxyl group-containing compound contains a polybutadiene polyol (A),
The polyurethane resin composition in which the isocyanate group-containing compound contains an isocyanurate-modified product (B) of a polyisocyanate compound and an allophanate-modified product (C) of a polyisocyanate compound. The polyurethane resin composition according to claim 1, wherein the polyisocyanate compound is hexamethylene diisocyanate. The polyurethane resin composition according to claim 1 or 2, wherein a mass mixing ratio of the (B) and (C) is (B) :( C) = 25: 75 to 75:25. The polyurethane resin composition according to any one of claims 1 to 3, wherein the polyurethane resin composition is used for electrical and electronic parts.