JP5216574B2 - Polyurethane resin composition and polyurethane resin - Google Patents

Description

  The present invention relates to a polyurethane resin composition and a polyurethane resin. More specifically, the present invention can maintain a high volume specific resistance value over a long period of time, and since the hardness change under high temperature conditions is small, it can be applied to a substrate over a long period of time. The present invention relates to a polyurethane resin composition that can sufficiently adhere and release a large amount of generated heat to the outside, and a polyurethane resin obtained by curing the polyurethane resin composition.

  Conventionally, in an electronic circuit substrate used for electrical appliances, etc., the substrate is made of a sealing material made of a flame-retardant heat-radiating polyurethane resin composition having a high volume resistance value in order to protect electronic components from moisture or the like. The whole is sealed (Patent Document 1). However, many electronic components that generate heat during operation are attached to the electronic circuit board. In recent years, electronic circuits have been integrated and highly functionalized as seen in LSIs, etc. At the same time, the heat generation is becoming local. Thus, in order to efficiently remove the heat generated from the electronic component, the sealing material needs to be in close contact with the circuit board or the electronic component for a long period of time, so that the increase in hardness under high temperature conditions is small. is necessary. In addition, since the heat-dissipating polyurethane resin used as the sealant is used in close contact with the electronic component, it is also necessary to maintain a high volume resistivity value over a long period of time.

In view of such a point, various heat-radiating polyurethane resin compositions have been developed in order to solve the conventional problems (Patent Documents 2 to 7). However, a heat-dissipating polyurethane resin composition that is satisfactory in all performances has not been obtained, and in particular, a high volume resistivity value can be maintained over a long period of time. In fact, a polyurethane resin composition capable of sufficiently adhering to the base material and releasing a large amount of generated heat to the outside has not been obtained.
JP 2000-226426 A JP 2002-121529 A JP 2002-134666 A JP 2003-133493 A JP 2003-138130 A JP 2004-300300 A JP 2007-131830 A

  The present invention has been made in view of the above prior art, and an object of the present invention is to maintain a high volume specific resistance value over a long period of time, and since the change in hardness under high temperature conditions is small, the object of the present invention is extended over a long period of time. It is intended to provide a polyurethane resin composition that can sufficiently adhere to a substrate and release a large amount of generated heat to the outside, and a polyurethane resin obtained by curing the polyurethane resin composition.

The polyurethane resin composition of the present invention comprises (C) an inorganic filler and a carbon-carbon unsaturated bond other than an aromatic ring in a polyurethane resin obtained by the reaction of (A) polyisocyanate and (B) polybutadiene polyol. A heat dissipating polyurethane resin composition containing (D) a plasticizer which is not present and (E) a phosphoric acid ester represented by the general formula (1), wherein 1 in the (B) polybutadiene polyol the ratio of 2-vinyl structure state, and are more than 50 mol%, in the case of the polyurethane resin composition as 100 wt%, and characterized that you containing 30 to 95% by weight of inorganic filler (C) To do.

  In the polyurethane resin composition of the present invention, since a polyfunctional polyisocyanate (A) is used, the resulting polyurethane polymer is formed in a network. On the other hand, since the polybutadiene polyol (B) having a high 1,2-vinyl structure ratio is used as the polyol, the increase in hardness of the resulting polyurethane resin under high temperature conditions is small. As a result, even when (C) the inorganic filler is blended, the obtained polyurethane resin is sufficiently adhered to the base material over a long period of time and can release a large amount of generated heat to the outside. Moreover, since the polyurethane resin composition of the present invention contains (E) phosphate ester represented by the general formula (1), (C) even when an inorganic filler is used at a high blending ratio, The mixing initial viscosity of the polyurethane resin composition can be made relatively low.

  The polyurethane resin of the present invention is obtained by curing the polyurethane resin composition.

  Since the polyurethane resin composition and the polyurethane resin of the present invention can maintain a high volume resistivity over a long period of time, even if they are used for a long period of time, they do not affect the functions of electronic components and the like constituting the circuit. In addition, since the increase in hardness under high temperature conditions is small and can sufficiently adhere to the substrate over a long period of time, it is possible to maintain the function of releasing a large amount of heat generated in close contact with the electronic component over a long period of time. it can.

  The polyurethane resin component of the present invention is obtained by reacting (A) polyisocyanate with (B) polybutadiene polyol having a specific structure. Examples of (A) polyisocyanate that can be used here include aliphatic polyisocyanate, alicyclic polyisocyanate, aromatic polyisocyanate, and araliphatic polyisocyanate.

  Aliphatic polyisocyanates 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-methylpentane-1,5-diisocyanate and the like.

  Examples of the alicyclic polyisocyanate 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.

  Aromatic polyisocyanates include tolylene diisocyanate, 2,2′-diphenylmethane diisocyanate, 2,4′-diphenylmethane diisocyanate, 4,4′-diphenylmethane diisocyanate (MDI), polymethylene polyphenyl polyisocyanate, 4,4′- Examples thereof include dibenzyl diisocyanate, 1,5-naphthylene diisocyanate, xylylene diisocyanate, 1,3-phenylene diisocyanate, 1,4-phenylene diisocyanate, and the like.

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

  Moreover, modified bodies, such as a carbodiimide body, an allophanate body, a burette body, an isocyanurate body, an adduct body, etc. of these organic polyisocyanates can be mentioned. In addition, these can also be used individually or in combination of 2 or more types.

  Of these, aliphatic polyisocyanates and alicyclic polyisocyanates are preferable from the viewpoint that discoloration hardly occurs. Hexamethylene diisocyanate-modified isocyanurate, hexamethylene diisocyanate-modified burette, and hexamethylene diisocyanate-modified adduct Is more preferable.

  Moreover, in this invention, even if it uses the urethane prepolymer obtained by making the said (A) polyisocyanate and (B) polybutadiene polyol which has a specific structure react on isocyanate group excess conditions, as (A) polyisocyanate. Good.

  Moreover, the polyol used for the polyurethane resin composition of this invention is the polybutadiene polyol shown below. There are three types of skeleton structure of polybutadiene: cis-1,4 structure, trans-1,4 structure and 1,2-vinyl structure. In the present invention, the ratio of 1,2-vinyl structure is 50 mol%. The polybutadiene polyol which is the above is used. Moreover, as a polyol, you may use what is obtained by making the above-mentioned (A) polyisocyanate and the (B) polybutadiene polyol which has the said specific structure react on hydroxyl-excess conditions. Thus, by increasing the ratio of the 1,2-vinyl structure, the increase in the hardness of the resulting polyurethane resin under high temperature conditions is reduced.

  Moreover, it is preferable that the average functional group number of the hydroxyl group of (B) polybutadiene polyol is in the range of 1.5 to 2.1. If the average number of functional groups of the hydroxyl group is smaller than this range, the resulting resin has low heat resistance, and if it is larger than this range, the resin becomes hard and may not be able to sufficiently adhere to the substrate.

  In the polyurethane resin composition of the present invention, the ratio of (A) polyisocyanate to (B) polybutadiene polyol is the molar ratio (NCO) of the isocyanate group of (A) polyisocyanate and the hydroxyl group of (B) polybutadiene polyol. / OH) is preferably in the range of 0.3 to 1.1. This is because if the molar ratio of the isocyanate group to the hydroxyl group is smaller than this range, the resulting resin has low heat resistance, and if it is larger than this range, the resin becomes hard and may not be sufficiently adhered to the substrate.

  As the (C) inorganic filler used in the polyurethane resin composition of the present invention, it is preferable to use one having a low electrical conductivity. Specifically, (C) the inorganic filler and water were mixed at a weight ratio of 8/80 (inorganic filler / water), and the electrical conductivity of the supernatant after standing at 80 ° C. for 13 hours was 40 μS / cm or less. Examples of such (C) inorganic fillers include metal oxides such as alumina and metal hydroxides such as aluminum hydroxide and magnesium hydroxide.

  In the polyurethane resin composition of the present invention, a metal nitride can be blended in order to further improve heat dissipation. Examples of such metal nitrides include aluminum nitride and boron nitride.

  In the present invention, the blending amount of the inorganic filler (C) is preferably 30 to 95% by weight and more preferably 50 to 95% by weight when the polyurethane resin composition is 100% by weight. Preferably, it is 60 to 95 weight%, More preferably, it is 70 to 90 weight%. (C) If the blending amount of the inorganic filler is larger than the above range, the initial mixing viscosity tends to be too high, and if it is less than the above range, sufficient heat dissipation tends to be difficult to obtain.

  The plasticizer (D) used in the polyurethane resin composition of the present invention has no carbon-to-carbon unsaturated bonds other than aromatic rings, and specifically includes dioctyl phthalate, diisononyl phthalate, diun. Phthalic acid diesters such as decyl phthalate, adipic acid diesters such as dioctyl adipate and diisononyl adipate, trimellitic acid esters such as trioctyl trimellitate and triisononyl trimellitate, pyromellitic acid esters such as tetraoctyl pyromellitate, Examples thereof include phosphoric acid triesters such as tricresyl phosphate and trixylenyl phosphate. Of these, diundecyl phthalate is preferably used. These may be used alone or in combination of two or more.

  The amount of the plasticizer is preferably 1 to 30% by weight, more preferably 3 to 20% by weight, and 5 to 15% by weight when the polyurethane resin composition is 100% by weight. Further preferred. When the amount is less than the above, it is difficult to obtain a sufficient viscosity-reducing effect of the polyurethane resin composition. When the amount is more than the above, various physical properties such as the strength of the polyurethane resin tend to be lowered.

  Various additives such as an antioxidant can be added to the polyurethane resin composition of the present invention as necessary. For example, as an antioxidant, phenol-containing antioxidants such as dibutylhydroxytoluene (BHT), tetrakis [methylene-3- (3 ′, 5′-di-t-butyl-4-hydroxyphenyl) propionate] methane, Phosphorus-containing antioxidants such as phenyl diisodecyl phosphite, sulfur-containing antioxidants such as dilauryl-3,3′-thiodipropionic acid ester, 2,4-bis (n-octylthio) -6- (4-hydroxy- An antioxidant containing phenol and sulfur in one molecule such as 3 ′, 5′-di-t-butylanilino) -1,3,5-triazine can be mentioned. When using antioxidant, when a polyurethane resin composition is 100 weight%, it is preferable to add in 0.01-5 weight%.

  Furthermore, (E) phosphoric acid ester represented by General formula (1) is mix | blended with the polyurethane resin composition of this invention.

Here, R is a hydrocarbon group having 1 to 30 carbon atoms, m is an integer of 0 to 20, n is an integer of 1 to 20, and R ′ is OH or a group represented by the general formula (2). In 1) and the general formula (2), R ″ is CH ₃ or CH ₂ CH ₃ , and “/” indicates that the oxyalkylene groups described on the left and right sides thereof may be block addition or random addition.

  This (E) phosphate ester can be obtained, for example, by reacting a polyether monool obtained by adding an alkylene oxide to a monoalcohol having 1 to 30 carbon atoms by a known method and anhydrous phosphoric acid. In addition, the said alkylene oxide should just have ethylene oxide as an essential component, and can also use propylene oxide and butylene oxide together. Furthermore, the number of added moles of alkylene oxide and the reaction ratio between the polyether monool and phosphoric anhydride are appropriately selected so as to satisfy the condition of the general formula (1).

  The compounding quantity of (E) phosphate ester represented by General formula (1) used for the polyurethane resin composition of this invention is 0.01-2 weight when a polyurethane resin composition is 100 weight%. % Is preferable, and a range of 0.01 to 1% by weight is more preferable. When the above range is exceeded, it is difficult to obtain a further viscosity-reducing effect due to an increase in the amount used, and the physical properties of the polyurethane resin also tend to be reduced, and below the above range, the addition of (E) phosphate ester The effect of reducing viscosity cannot be obtained.

  In preparing the polyurethane resin composition of the present invention, a catalyst may be added in order to accelerate the curing of the polyurethane resin. As the catalyst, a metal catalyst or an amine-based catalyst usually used for producing a polyurethane resin can be used. Examples of metal catalysts include tin catalysts such as dibutyltin dilaurate, dioctyltin dilaurate and dibutyltin dioctate, lead catalysts such as lead octylate, lead octenoate and lead naphthenate, bismuth catalysts such as bismuth octylate and bismuth neodecanoate, etc. Can be mentioned. Examples of the amine catalyst include diethylenetriamine.

The polyurethane resin composition of the present invention preferably has a hardness of 80 or less according to type A after curing. Moreover, it is preferable that the volume resistivity value after leaving for 100 hours at 121 ° C. and 100% relative humidity is 10 ⁹ Ω · cm or more. Furthermore, it is preferable that the heat conductivity after hardening is 1 W / m · K or more.

  The polyurethane resin of the present invention is obtained by curing a polyurethane resin composition. This resin preferably has a hardness of 90 or less according to Type A after being left at 150 ° C. for 60 hours.

  Hereinafter, based on an Example and a comparative example, the polyurethane resin composition and polyurethane resin of this invention are demonstrated in detail. In the present specification, “parts” and “%” represent “parts by weight” and “% by weight”, respectively, unless otherwise specified.

  Table 1 summarizes the ratio of 1,2-vinyl structure, the hydroxyl value (OHV), and the average number of functional groups of hydroxyl groups for the polyols used in the examples and comparative examples of the present invention.

  Table 2 shows the results of examining the electrical conductivities of various aluminas and aluminum hydroxides having various average particle diameters used as inorganic fillers in the examples and comparative examples of the present invention. The electrical conductivity was examined by measuring the electrical conductivity of the supernatant after mixing at a weight ratio of inorganic filler / water = 8/80 and leaving it at 80 ° C. for 13 hours.

(E-1: Synthesis of phosphate ester)
Using lauryl alcohol as a starting material, 2 mol of propylene oxide and 8 mol of ethylene oxide were block-added by a known method to obtain an alkylene oxide adduct of lauryl alcohol.

  Subsequently, 300 g of the above alkylene oxide adduct of lauryl alcohol and 27.1 g of phosphoric anhydride were charged in a four-necked flask at a molar ratio of 2.4: 1 and reacted at 70 ° C. for 4 hours with stirring. To obtain phosphoric ester (E-1) (theoretical substitution number of phosphoric acid OH group 1.2).

(E-2: Synthesis of phosphate ester 2)
Tridecyl alcohol was used as a starting material, and 10 mol of ethylene oxide was added by a known method to obtain an alkylene oxide adduct A of tridecyl alcohol.

  Subsequently, 300 g of the above tridecyl alcohol alkylene oxide adduct A and 22.2 g of phosphoric anhydride were charged in a four-necked flask at a molar ratio of 3: 1 and stirred at 70 ° C. for 4 hours. The reaction was carried out to obtain phosphate ester (E-2) (theoretical substitution number of phosphoric acid OH group 1.5).

(E-3: Synthesis of phosphate ester 3)
Tridecyl alcohol was used as a starting material, and 7 mol of ethylene oxide was added using a known method to obtain an alkylene oxide adduct B of tridecyl alcohol.

  Subsequently, 300 g of the above-mentioned alkylene oxide adduct B of tridecyl alcohol and 23.3 g of phosphoric anhydride were charged in a four-necked flask at a molar ratio of 3.6: 1 at 70 ° C. with stirring. Reaction was performed for 4 hours, and phosphoric ester (E-3) (theoretical substitution number 1.8 of the OH group of phosphoric acid) was obtained.

(Examples 1-8)
The polyurethane resin compositions of Examples 1 to 8 were prepared according to the formulation shown in Table 3. During the preparation, the components shown in Table 3 except for the (A) polyisocyanate component were mixed, and the isocyanate component was added to this mixture to obtain a polyurethane resin composition of each example.

  In addition, as a method for preparing the polyurethane resin composition, (A) the total amount of polyisocyanate, (B) a part of polybutadiene polyol, and (D) a part of plasticizer are mixed to prepare a polyurethane prepolymer-containing material. It is prepared in advance and (B) the remaining amount of the polybutadiene polyol, (D) the remaining amount of the plasticizer and the mixture of the remaining other components are prepared in advance, and the polyurethane prepolymer is contained. The product and the mixture may be mixed. Thus, according to the method of preparing a polyurethane prepolymer-containing material in advance, the curing speed is increased and the production efficiency is improved as compared with the method of adding the polyisocyanate component (A) described later. There is.

  Next, a test piece of polyurethane resin was prepared using the polyurethane resin composition. First, the polyurethane resin composition was filled in a 110 × 110 × 10 mm mold, covered, and cured at 23 ° C. for 48 hours, and then removed from the mold to obtain a polyurethane resin test piece.

(Comparative Examples 1-7)
By the formulation shown in Table 4, polyurethane resin compositions of Comparative Examples 1 to 7 were obtained in the same manner as in Examples 1 to 8. Moreover, the test piece of polyurethane resin was produced like these Examples 1-8 using these polyurethane resin compositions. In Comparative Example 7, the polyurethane resin composition had a very high viscosity and could not be sufficiently mixed, so that a uniform polyurethane resin could not be produced.

<Performance test>
About the test piece of the polyurethane resin of Examples 1-8 obtained above and Comparative Examples 1-7, the mixing initial stage viscosity was measured. Moreover, about the polyurethane resin test piece of Examples 1-8 and Comparative Examples 1-6 obtained above, the hardness (type A) of the test piece after being left at the initial stage and 150 ° C. for 60 hours, at the initial stage and 121 ° C. The volume resistivity, thermal conductivity, and flame retardancy after 100 hours of relative humidity at 100% were evaluated. Each test result was combined with Table 3 and Table 4, and was shown. Each test method is as follows.

(Initial mixing viscosity)
The viscosity during preparation of the polyurethane resin composition was measured at 25 ° C. using a BH viscometer.

(Hardness (Type A))
Hardness (type A) was measured according to JIS K6253.

(Thermal conductivity)
The thermal conductivity was measured according to JIS R2618 using a thermal conductivity meter (manufactured by Kyoto Electronics Industry Co., Ltd., QTM-D3).

(Volume resistivity)
For the volume resistivity, TR8601 manufactured by ADVANTEST was used, and the value after 5 minutes from the start of measurement was taken as the volume resistivity.

(Flame retardance)
The flame retardancy was measured according to UL standard UL94 (flame retardance of plastic materials).

(Test results)
As a general tendency, the polyurethane resin compositions of Examples 1 to 8 had lower initial viscosity compared to the compositions of Comparative Examples 1 to 6. This is considered to be a large effect by adding (E) phosphate ester.

  Regarding the hardness after standing for 60 hours at 150 ° C. at the initial stage, Examples 1 to 8 have a smaller increase in hardness than Comparative Examples 1 to 6, and thus it can be seen that the hardness can be sufficiently adhered to the substrate.

  Regarding the volume specific resistance value, the polyurethane resin compositions of Examples 1 to 8 were at a practical level both at the initial stage and after being allowed to stand at 121 ° C. and 100% relative humidity for 100 hours. On the other hand, the polyurethane resin compositions of Comparative Examples 1 to 6 all exhibited low volume specific resistance values.

  About thermal conductivity, any polyurethane resin composition of Examples 1-8 and Comparative Examples 1-6 was high. In particular, the thermal conductivity of Examples 7 and 8 having a large alumina blending ratio was high.

  About the flame retardance, any polyurethane resin composition of Examples 1-8 and Comparative Examples 1-6 was favorable.

  If the polyurethane resin composition of the present invention is a polyurethane resin, it maintains a high volume resistivity, and since the increase in hardness under high temperature conditions is small, it adheres sufficiently to the substrate over a long period of time and generates a large amount of heat. Can be released to the outside, so that it can be used in the fields of electrical products, electronic parts and the like.

Claims (4)

The polyurethane resin obtained by the reaction of (A) polyisocyanate and (B) polybutadiene polyol has (C) an inorganic filler and no carbon-carbon unsaturated bonds other than aromatic rings (D) plasticizer And a polyurethane resin composition containing (E) a phosphate ester represented by the general formula (1),
The ratio of 1,2-vinyl structure in the (B) polybutadiene polyol state, and are more than 50 mol%,
Wherein when a polyurethane resin composition was 100% by weight, the polyurethane resin composition characterized that you containing 30 to 95 wt% of (C) an inorganic filler.

(R is a hydrocarbon group having 1 to 30 carbon atoms, m is an integer of 0 to 20, n is an integer of 1 to 20, R ′ is OH or a group represented by the general formula (2), and the general formula (1) In the general formula (2), R ″ is CH ₃ or CH ₂ CH ₃ , and “/” represents that the oxyalkylene groups described on the left and right thereof may be block addition or random addition.
When the polyurethane resin composition as 100 wt%, (E) Formula polyurethane resin composition according to claim 1, wherein the phosphoric acid ester comprising from 0.01 to 2% by weight of the formula (1) object.   The (C) inorganic filler has an electrical conductivity of 40 μS / cm or less after leaving the mixture having the weight ratio of (C) inorganic filler / water 8/80 at 80 ° C. for 13 hours. The polyurethane resin composition according to claim 1 or 2.   A polyurethane resin obtained by curing the polyurethane resin composition according to claim 1.