Multicomponent-curable thermally-conductive silicone gel composition, thermally-conductive member and heat dissipation structure

Abstract

Provided is: a multicomponent curable thermally conductive silicone gel composition which has a high thermal conductivity, has excellent gap-filling ability and repairability, and has superior storage stability; a thermally conductive member comprising the composition; and a heat dissipating structure using the same. The thermally conductive silicone gel composition comprises: (A) an alkenyl group-containing organopolysiloxane; (B) an organohydrogenpolysiloxane; (C) a catalyst for hydrosilylation reaction; (D) a thermally conductive filler; (E) a silane-coupling agent or a hydrolysis condensation product thereof; and (F) a specific organopolysiloxane having a hydrolyzable silyl group at one end thereof. The thermally conductive silicone gel composition includes (I) a liquid composition that includes components (A), (C), (D), (E), and (F), but does not include component (B) and (II) a liquid composition that includes components (B), (D), (E), and (F), but does not include component (C) which are individually stored.

Claims

1. A multicomponent curable thermally conductive silicone gel composition comprising: (A) an alkenyl group-containing organopolysiloxane having a viscosity at 25° C. of 10 to 100,000 mPa s in an amount of 100 parts by mass; (B) an organohydrogenpolysiloxane in an amount such that the silicon-bonded hydrogen atoms in component (B) are from 0.2 to 5 mol per mol of alkenyl groups in component (A); (C) a hydrosilylation reaction catalyst in a catalytic amount; (D) a thermally conductive filler; (E) one or more silane coupling agents or hydrolyzed condensates thereof; and (F) an organopolysiloxane having a hydrolyzable silyl group at one end of the molecular chain; wherein at least liquids (I) and (II) below are stored separately; (I): a liquid composition containing components (A), (C), (D), (E) and (F), but not component (B), and (II): a liquid composition containing components (B), (D), (E) and (F), but not component (C); and wherein the amount of component (D) in liquid (I) is from 600 to 3,500 parts by mass, the amount of component (D) in liquid (II) is from 600 to 3,500 parts by mass, and the mass ratio of the sum of component (E) and component (F) in liquid (II) to the sum of component (E) and component (F) in liquid (I) is in a range from 1.5 to 10.0.

2. The multicomponent curable thermally conductive silicone gel composition according to claim 1, wherein the total amount of component (E) and component (F) is 0.1 to 5.0% by mass and the mass ratio of component (E) to component (F) is in a range from 5:95 to 95:5 when the total mass of component (D) in the composition is 100% by mass.

3. The multicomponent curable thermally conductive silicone gel composition according to claim 1, wherein the thermal conductivity is at least 2.0 W/mK.

4. The multicomponent curable thermally conductive silicone gel composition according to claim 1, wherein component (E) comprises (E1) an alkoxysilane having an alkyl group with 6 or more carbon atoms in the molecule, and component (D) is surface-treated with component (E) and component (F).

5. The multicomponent curable thermally conductive silicone gel composition according to claim 1, wherein component (F) is an organopolysiloxane represented by general formula (1) below, general formula (2) below, or a mixture of these; (i) organopolysiloxanes having a viscosity at 25° C. of from 10 to less than 10,000 mPa s represented by general formula (1): ##STR00005## where R.sup.1 represents an unsubstituted or substituted monovalent hydrocarbon group, each R.sup.2 independently represents a hydrogen atom, an alkyl group, an alkoxyalkyl group, or an acyl group, a is an integer from 5 to 250, and b is an integer from 1 to 3; (ii) organopolysiloxanes represented by general formula (2): R.sup.4.sub.3SiO(R.sup.4.sub.2SiO).sub.pR.sup.4.sub.2Si-R.sup.5—SiR.sup.4(.sub.3-d)(OR.sup.2).sub.d (2) where R.sup.4 represents the same or different monovalent hydrocarbon group, R.sup.5 is an oxygen atom or a divalent hydrocarbon group, R.sup.2 is the same as above, p is an integer from 100 to 500, and d is the same as above.

6. The multicomponent curable thermally conductive silicone gel composition according to claim 1, wherein the mass ratio of component (F) in liquid (II) to component (F) in liquid (I) is in a range from 1.5 to 10.0.

7. The multicomponent curable thermally conductive silicone gel composition according to claim 1, wherein the amount of component (D) in liquids (I) and (II) is in a range from 85 to 98% by mass relative to the composition as a whole, and the composition is substantially free of fillers other than component (D).

8. The multicomponent curable thermally conductive silicone gel composition according to claim 1, wherein component (B) comprises component (B1) and component (B1) has a viscosity at 25° C. of from 1 to 1,000 mPa s and contains an average of 2 to 4 silicon-bonded hydrogen atoms per molecule, some being linear organohydrogenpolysiloxanes having at least 2 such atoms on a side chain of the molecular chain, and a relationship is established between the silicon-bonded hydrogen atoms [H.sub.B1] in component (B1) of the composition and the silicon-bonded hydrogen atoms in organohydrogenpolysiloxanes other than component (B1) [.sup.H.sub.non-B1] such that the value of [H.sub.non-B1]/([H.sub.B1[+[H.sub.non-B1] is in a range of from 0.0 to 0.70.

9. The multicomponent curable thermally conductive silicone gel composition according to claim 1, further comprising (G) a heat resistance-imparting agent.

10. The multicomponent curable thermally conductive silicone gel composition according to claim 1, wherein component (D) is (D1) a tabular boron nitride powder having an average particle size of 0.1 to 30 μm, (D2) a granular boron nitride powder having an average particle size of 0.1 to 50 μm, (D3) a spherical and/or crushed aluminum oxide powder having an average particle size of 0.01 to 50 μm, (D4) graphite having an average particle size of 0.01 to 50 μm, or a mixture of two or more of these.

11. The multicomponent curable thermally conductive silicone gel composition according to claim 1, wherein the multicomponent curable thermally conductive silicone gel composition is a two-component thermally conductive silicone gel composition comprising liquid (I) and liquid (II).

12. A thermally conductive member comprising the multicomponent curable thermally conductive silicone gel composition according to claim 1 or a cured product thereof.

13. A heat-dissipating structure comprising the thermally conductive member according to claim 12.

14. The heat-dissipating structure according to claim 13, wherein the heat-dissipating structure is an electrical device or electronic device.

15. The heat-dissipating structure according to claim 13, wherein the heat-dissipating structure is an electrical device, an electronic device, or a secondary battery.

16. A heat-dissipating structure obtained by providing a heat-dissipating member via the multicomponent curable thermally conductive silicone gel composition according to claim 1 or a cured product thereof on a heat-dissipating component or a circuit board including a mounted heat-dissipating component.

Description

EXAMPLES

(1) The following is a more detailed description of the present invention with reference to examples. The present invention is not limited to these examples. In the examples, the compounds and compositions listed below were used as raw materials.

(2) Components (A)-(G) were mixed together at the number of parts shown in Tables 1-2 using the methods indicated in each example and comparative example to obtain the multicomponent thermally conductive silicone gel compositions in Examples 1-2 and Comparative Examples 1-2 consisting of liquid (I) and liquid (II). Preparation of Comparative Example 3 was also attempted.

(3) [Preparation of the Thermally Conductive Silicone Gel Cured Products]

(4) A 15 mm high×100 mm long×50 mm wide frame was prepared using a polyethylene backer on a polypropylene sheet, the frame was filled with a composition obtained by uniformly mixing together liquid (I) and liquid (II) obtained in each example and comparative example, a Teflon (registered trademark) sheet was pressed down on top to make the surface smooth, and curing was performed at 25° C. for one day. After curing, the Teflon (registered trademark) sheet and polyethylene backer were removed to obtain a thermally conductive silicone gel cured product. The thermally conductive silicone gel compositions obtained with the number of parts shown in Examples 1-2 and Comparative Examples 1-2 contained enough component (D) to obtain thermal conductivity of 5.0 W/mK. The thermal conductivity was measured with the probe method using QTM-500 from Kyoto Electronics.

(5) Tests were performed to determine the effects of the present invention. The viscosity, hardness, and storage stability of the thermally conductive silicone compositions were measured as follows.

(6) [Viscosity]

(7) The viscosity (Pa.Math.s) at 25° C. of the thermally conductive silicone compositions was measured using a rheometer (AR550) from TA Instruments. The geometry was measured using a parallel plate with a diameter of 20 mm after 120 seconds with gap of 200 μm and shear rates of 1.0 and 10.0 (1/s).

(8) [Hardness]

(9) The hardness of the thermally conductive silicone cured product obtained under conditions described above was measured using an ASKER TYPE E hardness tester from ASKER.

(10) [Storage Stability]

(11) The thermally conductive silicone compositions were separated into liquid (I) and liquid (II), and 2.5 kg of each was placed in a 1.1 L ointment bottle and stored at room temperature. After one month, liquid (I) and liquid (II) were checked for the presence or absence of oil separation.

(12) The compositions of the present invention were formed using the following components.

(13) Component (A):

(14) A-1: Dimethylpolysiloxane capped at both ends of the molecular chain with a dimethylvinylsiloxy group (viscosity 60 mPa.Math.s, Vi content 1.52% by mass)

(15) A-2: Dimethylpolysiloxane capped at both ends of the molecular chain with a dimethylvinylsiloxy group (viscosity 400 mPa.Math.s, Vi content 0.43% by mass)

(16) Component (B):

(17) B-1: A methyl hydrogen siloxane/dimethyl siloxane copolymer capped at both ends of the molecular chain with a trimethylsiloxy group, 2 on average in the molecule and 2 on a side chain of the molecular chain (viscosity 20 mPa.Math.s, Si—H content 0.10% by mass)

(18) Non-B-2: A methyl hydrogen siloxane/dimethyl siloxane copolymer capped at both ends of the molecular chain with a trimethylsiloxy group, 5 on average in the molecule and 5 on a side chain of the molecular chain (viscosity 5 mPa.Math.s, Si—H content 0.75% by mass)

(19) Non-B-3: A methyl hydrogen siloxane/dimethyl siloxane copolymer capped at both ends of the molecular chain with a dimethylhydroxy group, 3 on average in the molecule and 1 on a side chain of the molecular chain (viscosity 20 mPa.Math.s, Si—H content 0.14% by mass)

(20) Component (C):

(21) C-1: Complex of platinum and 1,3-divinyl-1,1,3,3-tetramethyldisiloxane with a platinum concentration of 0.6% by weight

(22) Component (D):

(23) D-1: Crushed aluminum oxide powder with an average particle size of 0.4 μm

(24) D-2: Crushed aluminum oxide powder with an average particle size of 2.5 μm

(25) D-3: Spherical aluminum oxide powder with an average particle diameter of 35 μm

(26) Component (E):

(27) E-1: Decyltrimethoxysilane

(28) Compound (F):

(29) F-1: A polyorganosiloxane represented by the following formula

(30) ##STR00004##

(31) Component (G):

(32) G-1: 29H,31H-phthalocyaninato (2-)-N29, N30, N31, N32 copper

(33) G-2: Iron oxide

Example 1

(34) First, 92.2 parts by mass of component (A-1), 13.8 parts by mass of component (E-1), and 23 parts by mass of component (F-1) were weighed out, and then 461 parts by mass of component (D-1), 461 parts by mass of component (D-2), and 1,244 parts by mass of component (D-3) were successively mixed in over 30 minutes. Once uniform, the mixture was heated and mixed at 160° C. for 60 minutes under reduced pressure, and then cooled to room temperature to obtain a mixture. Then, 0.263 parts by mass of component (C-1) and 7.8 parts by mass of component (A-2) for uniform mixing were mixed into the mixture to obtain liquid (I) of a thermally conductive silicone composition. Next, 95.6 parts by mass of component (F-1) and 13.8 parts by mass of component (E-1) were weighed out, and then 461 parts by mass of component (D-1), 461 parts by mass of component (D-2), and 1,244 parts by mass of component (D-3) were successively mixed in over 30 minutes. Once uniform, the mixture was heated and mixed at 160° C. for 60 minutes under reduced pressure, and then cooled to room temperature to obtain a mixture. Then, 18.66 parts by mass of component (B-1), 0.46 parts by mass of component (Non-B-2), 2.76 parts by mass of component (G-1), and 0.014 parts by mass of phenylbutynol serving as a reaction inhibitor were uniformly mixed into the mixture to obtain liquid (II) of the thermally conductive silicone composition. The viscosity of the thermally conductive silicone composition was measured with a rheometer (AR550) from TA Instruments. Also, the composition was cured at 25° C. for 1 day, and the hardness was measured. One month later, the storage stability was checked. The results are shown in Table 1.

Example 2

(35) First, 87.3 parts by mass of component (A-1), 9.4 parts by mass of component (E-1), and 23.6 parts by mass of component (F-1) were weighed out, and then 354 parts by mass of component (D-1), 354 parts by mass of component (D-2), and 1,509 parts by mass of component (D-3) were successively mixed in over 30 minutes. Once uniform, the mixture was heated and mixed at 160° C. for 60 minutes under reduced pressure, and then cooled to room temperature to obtain a mixture. Then, 0.269 parts by mass of component (C-1) and 12.7 parts by mass of component (A-2) for uniform mixing were mixed into the mixture to obtain liquid (I) of a thermally conductive silicone composition. Next, 94.3 parts by mass of component (F-1) and 9.4 parts by mass of component (E-1) were weighed out, and then 354 parts by mass of component (D-1), 354 parts by mass of component (D-2), and 1,509 parts by mass of component (D-3) were successively mixed in over 30 minutes. Once uniform, the mixture was heated and mixed at 160° C. for 60 minutes under reduced pressure, and then cooled to room temperature to obtain a mixture. Then, 34.9 parts by mass of component (B-1) and 0.014 parts by mass of phenylbutynol serving as a reaction inhibitor were uniformly mixed into the mixture to obtain liquid (II) of the thermally conductive silicone composition. The viscosity of the thermally conductive silicone composition was measured with a rheometer (AR550) from TA Instruments. Also, the composition was cured at 25° C. for 1 day, and the hardness was measured. One month later, the storage stability was checked. The results are shown in Table

(36) TABLE-US-00001 TABLE 1 Example 1 Example 2 Component Liquid (I) Liquid (II) Liquid (I) Liquid (II) A-1 92.2 — 87.3 — A-2 7.8 — 12.7 — B-1 — 18.66 — 34.9 Non-B-2 — 0.46 — — C-1 0.263 — 0.269 — D-1 461 461 354 354 D-2 461 461 354 354 D-3 1244 1244 1509 1509 E-1 13.8 13.8 9.4 9.4 F-1 23.0 95.6 23.6 94.3 G-1 — 2.76 — — G-2 — — 3.54 — Phenylbutynol — 0.014 — 0.014 Si—H/Alkenyl Group 0.46 0.69 Mol Ratio [H.sub.non-B1]/ 0.16 0.0 [H.sub.B1] + [H.sub.non-B1] [(II)[E-1] + [F-1]]/ 3.0 3.1 [(I)[E-1] + [F-1]] [(II)[F-1]]/[(I)[F-1]] 4.2 4.0 [(II)[E-1]]/[(I)[E-1]] 1.0 1.0 Type E Hardness 20 64 Viscosity 10.0 (1/s) 177 209 118 98 (Pa .Math. s) Storage Stability No No No No Separation Separation Separation Separation

Comparative Example 1

(37) Liquid (I) of a thermally conductive silicone composition was obtained in the same manner as Example 2. Next, 66.0 parts by mass of component (A-1), 9.4 parts by mass of component (E-1) and 18.9 parts by mass of component (F-1) were weighed out, and then 354 parts by mass of component (D-1), 354 parts by mass of component (D-2), and 1,509 parts by mass of component (D-3) were successively mixed in over 30 minutes. Once uniform, the mixture was heated and mixed at 160° C. for 60 minutes under reduced pressure, and then cooled to room temperature to obtain a mixture. The mixture could not be maintained in a uniform paste form. Then, 36.6 parts by mass of component (B-1), 0.71 parts by mass of component (Non-B-2), 2.45 parts by mass of component (G-1), and 0.014 parts by mass of phenylbutynol serving as a reaction inhibitor were mixed into the mixture, but a uniform liquid (II) of the thermally conductive silicone composition could not be obtained. The viscosity of the thermally conductive silicone composition was measured with a rheometer (AR550) from TA Instruments. Also, the composition was cured at 25° C. for 1 day, and the hardness was measured. One month later, the storage stability was checked. The results are shown in Table 2.

Comparative Example 2

(38) Liquid (I) of a thermally conductive silicone composition was obtained in the same manner as Example 2. Next, 82.5 parts by mass of component (A-1), 9.4 parts by mass of component (E-1), and 11.8 parts by mass of component (F-1) were weighed out, and then 354 parts by mass of component (D-1), 354 parts by mass of component (D-2), and 1,509 parts by mass of component (D-3) were successively mixed in over 30 minutes. Once uniform, the mixture was heated and mixed at 160° C. for 60 minutes under reduced pressure, and then cooled to room temperature to obtain a mixture. Then, 0.71 parts by mass of component (Non-B-2), 28.77 parts by mass of component (Non-B-3), 2.17 parts by mass of component (G-1), and 0.014 parts by mass of phenylbutynol serving as a reaction inhibitor were uniformly mixed into the mixture to obtain liquid (II) of the thermally conductive silicone composition. The viscosity of the thermally conductive silicone composition was measured with a rheometer (AR550) from TA Instruments. Also, the composition was cured at 25° C. for 1 day, and the hardness was measured. One month later, the storage stability was checked. The results are shown in Table 2.

(39) TABLE-US-00002 TABLE 2 Comparative Comparative Example 1 Example 2 Component Liquid (I) Liquid (II) Liquid (I) Liquid (II) A-1 87.3 66.0 87.3 82.5 A-2 12.7 — 12.7 — B-1 — 36.6 — — Non-B-2 — 0.71 — 0.71 Non-B-3 — — — 28.77 C-1 0.269 — 0.269 — D-1 354 354 354 354 D-2 354 354 354 354 D-3 1509 1509 1509 1509 E-1 9.4 9.4 9.4 9.4 F-1 23.6 18.9 23.6 11.8 G-1 — 2.45 — 2.17 G-2 3.54 — 3.54 — Phenylbutynol — 0.014 — 0.014 Si—H/Alkenyl Group 0.49 0.47 Mol Ratio [H.sub.non-B1]/ 0.13 1.0 [H.sub.B1] + H.sub.non-B1] [(II)[E-1] + [F-1]]/ 0.86 0.64 [(I)[E-1] + [F-1]] [(II)[F-1]]/[(I)[F-1]] 0.80 0.50 [(II)[E-1]]/[(I)[E-1]] 1.0 1.0 Type E Hardness Unmeasurable 6 Viscosity 10.0 (1/s) 118 Not 118 129 (Pa .Math. s) Uniform Storage Stability No Not No No Separation Uniform Separation Separation

Comparative Example 3

(40) Liquid (I) of a thermally conductive silicone composition was obtained in the same manner as Example 1. Next, 23 parts by mass of component (F-1) (=same amount as in liquid (I) of Example 1) and 13.8 parts by mass of component (E-1) were weighed out, and when 461 parts by mass of component (D-1), 461 parts by mass of component (D-2), and 1,244 parts by mass of component (D-3) were successively mixed in over 30 minutes, a solid power composition was obtained instead of a liquid composition. In other words, liquid (II) could not be prepared.

(41) When the mass ratio of the sum of component (E) and component (F) in liquid (II) to the sum of component (E) and component (F) in liquid (I) was 3.0 or 3.1 as in Examples 1-2, each thermal conductive silicone gel composition of the present invention (designed thermal conductivity: 5.0 W/mK) maintained a viscosity in liquids (I) and (II) before curing indicating excellent gap filling properties, and no oil separation was observed when the storage stability was checked after one month. In other words, good storage stability was obtained.

(42) In Comparative Example 1, a thermally conductive silicone gel composition could not be obtained in the form of a uniform paste. In Comparative Example 2, a thermally conductive silicone gel composition could be obtained in the form of a uniform paste, but a large amount of oil separation was observed when the storage stability was checked after one month. In other words, storage stability was insufficient. In Comparative Example 3, the components corresponding to liquid (II) were not in liquid form, and a multicomponent curable thermally conductive silicone gel composition could not be obtained. Therefore, when the mass ratio of the sum of component (E) and component (F) in liquid (II) to the sum of component (E) and component (F) in liquid (I) was not within the scope of the present patent, a stable multicomponent curable thermally conductive silicone gel composition could not be obtained.