JPH1034759A - Cushioning material for liquid crystal display and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve processing operability in an assemblying process of a liquid crystal display which is excellent in heat resistance and heat radiation, good in electricity control properties, and little in generation of static electricity. SOLUTION: A silicone rubber composition wherein fine silica particles, heat-conductive fine particle of at least 15W/(m. deg.C) heat conductivity, and conductive carbon black are blended, is molded in a sheet shape, and cross linkingly treated. Thereby, a cushioning material for a liquid crystal display composed of a silicone rubber sheet of 390N/cm<2> or higher tensile strength, at least 0.4W/(m. deg.C) heat conductivity, and at most 10<12> Ω.cm volumetric specific resistance is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cushioning material for a liquid crystal display which is used as a backing for protecting a liquid crystal cell, and a method of manufacturing the same, which improves processing operability in a process of assembling the liquid crystal display. is there.

[0002]

2. Description of the Related Art A liquid crystal display is provided with a chloroprene rubber or the like on the back surface of a cell for the purpose of protecting a liquid crystal cell from external force and keeping two glass substrates in parallel to maintain a uniform thickness of a liquid crystal layer. It is assembled by attaching a cushion material made of a rubber sheet. This liquid crystal display is widely used for OA equipment such as notebook personal computers, home appliances, display panels for automobiles, and the like.
Market demands for higher performance and lower prices of liquid crystal displays have been increasing.

One of the cost factors of the liquid crystal display is the processing operability of the assembling process, and improvement of the processing operability is desired in order to meet the market demand for price reduction. One means of improving the processing operability is to raise the curing temperature of the adhesive by increasing the bonding temperature and shorten the working time.
For that purpose, the heat resistance of the silicone rubber has attracted attention because it is necessary to increase the heat resistance of the cushion material. However, since silicone rubber has a low thermal conductivity and has a limit in raising the temperature, it is necessary to improve the heat dissipation of the silicone rubber in order to achieve the above-mentioned purpose. Thus, it has become necessary to reduce the thickness of the silicone rubber sheet.

As a means for improving the heat dissipation of the silicone rubber, it is conceivable to incorporate fine particles having high thermal conductivity into the silicone rubber. However, in this method, since the strength of the silicone rubber decreases in proportion to the thermal conductivity, it is necessary to increase the thickness of the silicone rubber sheet in order to maintain processing operability in terms of strength, and the heat radiation property is increased. And the high market demands described above could not be met.

[0005] In addition, general silicone rubber has a high electric resistance and is easily charged. Therefore, in the manufacturing process of a liquid crystal display, the silicone rubber sheet is charged and the rubber sheet is attracted by static electricity, thereby deteriorating the processing operability. This problem becomes more serious as the thickness of the sheet becomes thinner, and it has been desired to solve the problem.

[0006]

The inventions according to the first to fourth aspects of the present invention utilize the heat resistance of a silicone rubber while improving the low heat conductivity without lowering the strength of the silicone rubber, thereby improving the heat resistance. The present invention provides a cushioning material for a liquid crystal display which is excellent in heat resistance, heat dissipation and strength, and which can improve processing operability in a process of assembling the liquid crystal display. It is intended to improve the processing operability by further improving the chargeability as well as the conductivity, thereby reducing the generation of static electricity, and further improving the processing operability.
The invention described in Item 6 provides a method of manufacturing the cushioning material for a liquid crystal display.

[0007]

According to the first aspect of the present invention,
It consists of a silicone rubber sheet and has a tensile strength of 390
A cushion material for a liquid crystal display characterized by having a thermal conductivity of at least N / cm ² and a thermal conductivity of at least 0.4 W / (m · ° C.).

The silicone rubber used in the present invention is an organopolysiloxane represented by an average unit formula: RaSiO _{(4-a) / 2} . In the above formula, R is a substituted or unsubstituted monovalent hydrocarbon group, for example, an alkyl group such as a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, a vinyl group, an allyl group, and butenyl. Group, pentenyl group, alkenyl group such as hexenyl group, phenyl group, tolyl group, xylyl group, aryl group such as naphthyl group, cyclopentyl group, cycloalkyl group such as cyclohexyl group,
Benzyl group, aralkyl group such as phenethyl group, halogenated alkyl group such as 3-chloropropyl group, 3,3,3-trifluoropropyl group, and the like, preferably methyl group, vinyl group, phenyl group, 3, 3,3-trifluoropropyl group. In the above formula, a is 1.9 to 2.
A number in the range of 1. The silicone rubber component is represented by the above average unit formula. Specific siloxane units constituting the silicone rubber component include, for example, R ₃ SiO _1/2 unit, R
₂ (HO) SiO _{2 1/2} unit, R ₂ SiO _2/2 unit, RS
_{io3 / 2} units and _{io4 / 2} units.

The main component of the silicone rubber component is R ₂ Si
O _2/2 unit and R ₃ SiO _1/2 unit or R ₂ (HO)
It is a linear polymer essentially containing SiO _1/2 units, and optionally a small amount of RSio _3/2 units and / or R ₃ S
It can have a partially branched structure by containing _{iO1 / 2} units. Also, as part of the silicone rubber component, R ₃ Si
A resinous polymer composed of O _1/2 units and _{SiO 4/2} units can be blended. As described above, the silicone rubber component may be a mixture of two or more polymers.
When the composition is an addition reaction-curable silicone rubber composition, at least two Rs in the organopolysiloxane represented by the above average unit formula must be alkenyl groups.

The molecular structure of the silicone rubber component is not particularly limited, and may be, for example, linear, partially branched linear, branched, or resinous. , A linear polymer, or a mixture mainly composed of a linear polymer. Such silicone rubber components include, for example, dimethylpolysiloxane having trimethylsiloxy groups at both ends of molecular chains, methylvinylpolysiloxane having trimethylsiloxy groups at both ends of molecular chains, methylphenylpolysiloxane having trimethylsiloxy groups at both ends of molecular chains, and methylphenylpolysiloxane. Trimethylsiloxy group-blocked dimethylsiloxane / methylvinylsiloxane copolymer at both ends of chain, trimethylsiloxy group-blocked dimethylsiloxane / methylphenylsiloxane copolymer at both ends of molecular chain, dimethylsiloxane / methyl-blocked trimethylsiloxy group at both ends of molecular chain 3,3-trifluoropropyl) siloxane copolymer, molecular chain terminal trimethylsiloxy group-blocked dimethylsiloxane / methylvinylsiloxane / methylphenylsiloxane copolymer, molecular chain terminal dimethyl Nylsiloxy group-blocked dimethylpolysiloxane, molecular chain terminal dimethylvinylsiloxy group-blocked methylvinylpolysiloxane, molecular chain terminal dimethylvinylsiloxy group-blocked methylphenylpolysiloxane, molecular chain terminal dimethylvinylsiloxy group-blocked dimethylsiloxane / methylvinylsiloxane Copolymer, dimethylvinylsiloxy-group-blocked dimethylsiloxane / methylphenylsiloxane copolymer with both ends of molecular chain, dimethylsiloxane-methyl (3,3,3-trifluoropropyl) siloxane-copolymer with both ends of molecular chain dimethylvinylsiloxy-group Coupling, dimethylvinylsiloxy group-blocked dimethylsiloxane at both ends of molecular chain
Methyl vinyl siloxane / methyl phenyl siloxane copolymer, dimethyl polysiloxane with silanol groups at both ends of molecular chain, methyl vinyl polysiloxane with silanol groups at both ends of molecular chain, methyl phenyl polysiloxane with silanol groups at both ends of molecular chain, both ends of molecular chain Silanol group-blocked dimethylsiloxane / methylvinylsiloxane copolymer, molecular chain-terminated silanol group-terminated dimethylsiloxane / methylphenylsiloxane copolymer, molecular chain-terminated silanol group-blocked dimethylsiloxane / methyl (3,3
3-trifluoropropyl) siloxane copolymer, dimethylsiloxane / methylvinylsiloxane / methylphenylsiloxane copolymer with silanol groups at both ends of molecular chain, dimethylpolysiloxane with trimethoxysiloxy groups at both ends of molecular chain, tris at both ends of molecular chain Methoxysiloxy group-blocked dimethylsiloxane / methylvinylsiloxane copolymer, molecular chain terminal trimethoxysiloxy group-blocked dimethylsiloxane / methylphenylsiloxane copolymer, molecular chain terminal trimethoxysiloxy group-blocked dimethylsiloxane / methylvinylsiloxane / methyl Phenylsiloxane copolymer, organopolysiloxane copolymer comprising R ₃ SiO _1/2 units and _{SiO 2/2} units, R ₂ SiO
Organopolysiloxane copolymers consisting of _2/2 units and RSi O _3/2 units, R ₃ Si O _1/2 units and R ₂ Si O _2/2
And organopolysiloxane copolymers consisting of RSiO _3/2 units and a mixture of two or more of these. The viscosity of the silicone rubber component at 25 ° C.
Although not particularly limited, it is preferably 10,000 centistokes or more.

The silicone rubber sheet of the present invention has a tensile strength of 390 N / cm ² or more, preferably 450 N / cm ^2.
cm ² or more and a thermal conductivity of 0.4 W / (m · ° C.) or more, preferably 0.6 W / (m · ° C.) or more. As appropriate, heat-conductive fine particles having good conductivity and conductive carbon black are appropriately blended, and further, if necessary, other additives are blended and kneaded to form a sheet. It can be manufactured by preparing and vulcanizing. And, by having the above tensile strength, it is possible to provide a practically sufficient strength even if the thickness is reduced, and to make the discharge performance good, and furthermore, to have a thermal conductivity of 0.4.
W / (m · ° C.) or more, which means that the silicone rubber itself has heat resistance, and when used as a cushion material for a liquid crystal display, the operability during assembly processing is improved.

However, if the tensile strength is less than 390 N / cm ² , the strength of the sheet is too low when used as a cushioning material for a liquid crystal display, and the sheet is easily broken when the thickness is reduced, so that the workability at the time of assembling the liquid crystal display is improved. And when the thickness is increased, the heat radiation property is reduced. When the thermal conductivity is less than 0.4 W / (m · ° C.), the heat dissipation of the silicone rubber sheet is deteriorated. Therefore, when the silicone rubber sheet is used as a cushioning material for a liquid crystal display, for example, when it is bonded with an adhesive at a high temperature. Since the silicone rubber deteriorates due to heat storage during the treatment, the treatment temperature cannot be set high, so that the assembly cycle of the liquid crystal display is lengthened and the cost is increased.

The silicone rubber sheet of the present invention preferably has a volume resistivity of not more than 10 ¹² Ω · cm, particularly not more than 10 ¹¹ Ω · cm, as described in claim 2, by blending a conductive material. As a result, a silicone rubber sheet having good antistatic properties that satisfies market requirements is obtained. However, when the volume resistivity exceeds 10 ¹² Ω · cm, the silicone rubber sheet is easily charged, and is attracted to each other or other parts by the generated static electricity. In addition, the workability of assembling the liquid crystal display deteriorates, the assembly cycle becomes longer, and the cost increases.

The silicone rubber sheet according to the present invention has a thickness of 0.03 to 0.5.
mm, especially 0.05 to 0.3 mm, in which case it is easy to obtain the desired heat dissipation while satisfying the desired tensile strength. However, the thickness is 0.
If it is less than 03 mm, the strength and cushioning properties are insufficient. Conversely, if it exceeds 0.5 mm, the heat radiation property deteriorates, and the processing temperature at the time of bonding with the adhesive as described above cannot be set high,
Therefore, the assembly cycle of the liquid crystal display is lengthened, and the cost is increased.

The compounding agent to be added to the organopolysiloxane includes fine silica particles as a reinforcing material and a thermal conductivity of 15 W / (m · ° C.).
It is preferable to use the above-mentioned heat conductive fine particles and conductive carbon black, whereby desired tensile strength, heat dissipation and electric conductivity can be easily obtained.

The fine silica particles are not particularly limited as long as they have the reinforcing property of silicone rubber. For example, fumed silica, precipitated silica, and silica obtained by hydrophobizing the surface of these silicas may be used. The fine silica particles have a specific surface area of 50 m ² / g or more, especially 100 to 300.
Those having m ² / g are preferred. If the specific surface area is less than 50 m ² / g, it is difficult for the silicone rubber to exhibit reinforcing properties. Further, the addition amount of the fine silica particles is preferably 5 to 100 parts, especially 20 to 60 parts, and preferably less than 5 parts with respect to 100 parts of the organopolysiloxane.
If the amount exceeds the above range, the processability deteriorates and the mechanical strength of the obtained silicone rubber decreases.

The heat conductive fine particles have a heat conductivity of 15
There is no particular limitation as long as it is W / (m · ° C.) or more, and particularly preferably 20 W / (m · ° C.) or more. For example,
Examples include alumina, magnesium oxide, boron nitride, aluminum nitride, and graphite. When the thermal conductivity of the thermally conductive fine particles is less than 15 W / (m · ° C.), it is necessary to add a large amount of fine particles to make the thermal conductivity of the silicone rubber sheet 0.4 W / (m · ° C.) or more. Yes, the mechanical strength of the silicone rubber sheet is reduced. The amount of the thermally conductive fine particles to be added is preferably 50 to 800 parts by weight, particularly preferably 100 to 500 parts by weight, based on 100 parts of the organopolysiloxane. If the amount is less than 50 parts by weight, the thermal conductivity of the silicone rubber sheet is insufficient, and if it exceeds 800 parts by weight, the mechanical strength of the silicone rubber sheet is reduced.

The carbon black is not particularly limited as long as it has a conductivity imparting effect. For example,
Those manufactured by a known method such as a furnace method, an acetylene method, a lamp method, and a thermal method can be used. One of these carbon blacks may be used alone,
The conductivity may be adjusted by using two or more kinds having different particle diameters in combination. Further, a graphite powder and a semiconductive fine powder made of a metal oxide may be used in combination. Further, an antistatic compound composed of a surfactant may be used in combination. The addition amount of this carbon black is preferably 1 to 100 parts, particularly preferably 2 to 50 parts, per 100 parts of the organopolysiloxane.

In the cushioning material for a liquid crystal display, as described in claim 5, the above-mentioned fine silica particles, heat conductive fine particles having a heat conductivity of 15 W / (m · ° C.) or more, and an organic polysiloxane. It can be produced by molding a silicone rubber composition containing carbon black into a sheet, followed by a crosslinking treatment.

In the above method of the present invention, in addition to the above-mentioned additives, if necessary, pigments, dyes, antioxidants,
An antioxidant, a release agent, a flame retardant, a thixotropic agent, a filler dispersant, and the like can be optionally added. In addition, the use of a reaction control agent such as a co-crosslinking agent to improve the mechanical strength is not limited at all. The silicone rubber composition of the present invention is obtained by uniformly mixing the above components using a rubber kneader such as a two-roll, Banbury mixer, dough mixer (kneader) or the like, and subjecting it to a heat treatment if necessary. Can be

The silicone rubber sheet of the present invention can be produced by molding the above-mentioned silicone rubber composition into a sheet and then subjecting it to a crosslinking treatment. The molding method and the crosslinking method are also not particularly limited, but the method of dissolving the silicone rubber composition in a solvent, forming the sheet by a casting method, and then crosslinking by electron beam irradiation can produce a thin material having a uniform thickness. It is preferred in that respect. That is, as described in claim 6, the above silicone rubber composition is dissolved in a solvent to form a rubber solution having a solid content of 10 to 50% by weight, and this rubber solution is formed on a release support film made of polyethylene terephthalate. , Dried, and then the silicone rubber composition on the support film is cross-linked by electron beam irradiation, and then the support film is peeled off.

The above-mentioned silicone rubber composition may be produced by simultaneously kneading the above-mentioned compounding agent with the organopolysiloxane by the above-mentioned method, or may be a method of adding and kneading the compounding agent sequentially. Further, a composition in which the organopolysiloxane and each compounding agent are separately kneaded may be blended and then re-kneaded. This re-kneading method is a preferred embodiment in that the degree of dispersion of each compounding agent is improved. In the case of molding by a solution method, the above-mentioned compounding agent may be added at the time of preparing the solution, and a dispersion treatment may be performed.

[0023]

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiment 1 Organopolysiloxane 1 having a viscosity of 10,000 cs or more
5 parts by weight of fine silica particles having a specific surface area of 100 to 300 m ² / g, and a thermal conductivity of 15 W /
(M · ° C.) 100 to 800 parts by weight of heat conductive fine particles and 2 to 50 parts by weight of conductive carbon black are simultaneously added and kneaded at a temperature of 100 to 200 ° C.
Form a 0 mm sheet. Next, the unvulcanized rubber sheet is cut into small pieces of 5 to 50 mm square, and the small pieces are dissolved in a solvent such as toluene to obtain a silicone rubber solution having a solid content of 10 to 50% by weight. The rubber solution is applied on a release support film made of polyethylene terephthalate so as to have a thickness of 0.03 to 0.5 mm after drying, dried, then crosslinked by electron beam irradiation, and peeled off from the support film.

The obtained cushion material for a liquid crystal display comprising a silicone rubber sheet has a tensile strength of 390 N / cm.
² or more, thermal conductivity of 0.4 W / (m · ° C.) or more, volume resistivity of 10 ¹² Ω · cm or less, and thickness of 0.03 to 0.5 mm
It is excellent in heat resistance, strength and heat dissipation, and it is hard to be charged, so it can be cut into a desired shape as a cushion material for liquid crystal display and can withstand high temperature bonding when used for assembling liquid crystal display Excellent in processing operability.

Embodiment 2 Organopolysiloxane 1 having a viscosity of 10,000 cs or more
5 to 100 parts by weight of fine silica particles having a specific surface area of 100 to 300 m ² / g to 100 parts by weight,
Knead at 0 ° C. to produce base compound. Next, the heat conductive fine particles 100 to 80 having a heat conductivity of 15 W / (m · ° C.) or more are added to 100 parts of the base compound.
0 parts by weight and 2 to 50 parts by weight of conductive carbon black are simultaneously added and kneaded at a temperature of 100 to 200 ° C., and then a sheet having a thickness of 2 to 10 mm is formed. Hereinafter, a cushioning material for a liquid crystal display made of a silicone rubber sheet is manufactured in the same manner as in the first embodiment. The obtained cushioning material for a liquid crystal display can be used in the same manner as the cushioning material of Embodiment 1, and is particularly excellent in mechanical strength.

Embodiment 3 With respect to 100 parts of the base compound of Embodiment 2, heat conductive fine particles having a heat conductivity of 15 W / (m · ° C.) or more
Except that 800 parts by weight and 2 to 50 parts by weight of conductive carbon black are sequentially added and kneaded, kneading is performed in the same manner as in Embodiment 2, a sheet is formed, and further a silicone rubber sheet is formed in the same manner as in Embodiment 1. Manufactures cushioning materials for liquid crystal displays. The obtained cushioning material for a liquid crystal display can be used in the same manner as the cushioning material of Embodiment 1, and is particularly excellent in mechanical strength.

Embodiment 4 Organopolysiloxane 1 having a viscosity of 10,000 cs or more
00 parts by weight based on the temperature by adding 10 to 200 parts by weight of fine silica particles having a specific surface area of 100 to 300 m ² / g 100
Knead at ~ 200 ° C to produce a base compound.
On the other hand, with respect to 100 parts by weight of the organopolysiloxane, 200 to 1600 parts by weight of thermally conductive fine particles having a thermal conductivity of 15 W / (m · ° C.) or more or 4 to 100 parts by weight of conductive carbon black are individually compounded. Temperature 100
Knead at ~ 200 ° C to produce a thermally conductive compound and a conductive compound. Next, the base compound, the thermally conductive compound and the electrically conductive compound are fine silica particles of the final composition, the thermally conductive fine particles and the electrically conductive carbon black are each 5 to 100 parts by weight based on 100 parts by weight of the organopolysiloxane, 10
It is blended so as to be 0 to 800 parts by weight and 2 to 50 parts by weight, and is kneaded again at a temperature of 100 to 200 ° C., and then a sheet having a thickness of 2 to 10 mm is formed. Hereinafter, a cushioning material for a liquid crystal display made of a silicone rubber sheet is manufactured in the same manner as in the first embodiment. The obtained cushioning material for a liquid crystal display can be used in the same manner as the cushioning material of Embodiment 1, and is particularly excellent in mechanical strength.

[0028]

The present invention will be described below in detail with reference to examples. In the following description, "parts" indicates parts by weight.

Example 1 Organopolysiloxane 1 having a viscosity of 10,000,000 cs and comprising 99.85 mol% of dimethylsiloxane units and 0.15 mol% of methylvinylsiloxane units
40 parts of fumed silica ("Aerosil 200" manufactured by Nippon Aerosil Co., Ltd.) was added to 00 parts, and the mixture was kneaded at 100 to 200 [deg.] C. using two rolls to produce a base compound. Next, this base compound 10
For 0 parts, thermal conductivity of 50 W /
(M · ° C.) 250 parts of magnesium oxide fine particles and conductive carbon black (“Ketchin Black EC” manufactured by Lion Akzo Co., Ltd., specific surface area: 1000 m ² / g;
(Oil absorption: 340 ml), and kneaded in the same manner as described above to prepare a silicone rubber composition, which was formed into a sheet having a thickness of 3 mm.

The unvulcanized rubber sheet made of the above silicone rubber composition is cut into 1 cm square pieces, weighed so that the weight ratio with respect to toluene is 33%, and vacuum removed together with toluene. Put into a stirrer with a foam device
After stirring under atmospheric pressure for 15 hours to dissolve the strips in toluene, the vacuum defoaming device was driven to a gauge pressure of -750 mmHg.
The mixture was further stirred for 20 minutes under vacuum and degassed.

Next, the silicone rubber solution obtained by the above dissolution and defoaming is supplied to a roll coater, and a support film ("Lumipearl TC1" manufactured by Toyo Cross Co., Ltd.) obtained by roughening the surface of a polyethylene terephthalate film.
10)) at a speed of 5 m / min, while drying the above silicone rubber solution on the surface to a thickness of 0.15 mm.
And then introduced into an oven at 80 ° C.
For 5 minutes, and further continuously with an electron beam irradiation device (200
KV, 200 MR), a crosslinking treatment is performed at the above-mentioned traveling speed, and then the support film is peeled off to a thickness of 0.15
mm silicone rubber sheet was obtained.

The properties of the obtained silicone rubber sheet of Example 1 were tested, and the results are shown in Table 1. The test method is as follows. (1) Tensile strength and elongation Measured according to JIS K-6301. (2) Thermal conductivity Measured with a “Kemtherm QTM-D3 quick thermal conductivity meter” manufactured by Kyoto Electronics Industry Co., Ltd. (3) Volume resistivity value Measured according to ASTM D991.

Table 1 Tensile strength Tensile elongation Thermal conductivity Volume resistivity (kgf / cm ² ) (%) (W / (m · ° C.)) (Ω · cm) Example 1 56 220 1.2 2.5 × 10 ⁶ Example 2 62 330 1.2 2.2 × 10 ⁶ Example 3 70 320 0.8 2.5 × 10 ⁶ Example 4 75 400 1.0 2.6 × 10 ⁶ Comparative Example 1 10 50 1.2 2.8 × 10 ⁶ Comparative Example 2 95 600 0.2 2.5 × 10 ⁶ Comparative Example 3 95 600 0.2 1.5 × 10 ¹⁴

As shown in Table 1, the silicone rubber sheet of Example 1 is excellent in tensile strength, heat conductivity and conductivity. As a result of using the silicone rubber sheet of Example 1 as a cushioning material for a liquid crystal display, excellent mechanical strength and little generation of static electricity were obtained, so that the workability of assembling into a liquid crystal display was good and at 300 ° C. It was able to withstand the bonding treatment for 30 seconds and was highly practical.

Comparative Example 1 Example 1 was repeated except that the fumed silica of Example 1 was omitted.
A silicone rubber composition and a silicone rubber sheet were produced in the same manner as described above. The characteristics are also shown in Table 1. The silicone rubber sheet of Comparative Example 1 is excellent in heat conductivity and conductivity, but is inferior in mechanical strength, and has low mechanical strength when used as a cushioning material for a liquid crystal display. Was inferior in workability for integration and low in practicality.

Comparative Example 2 A silicone rubber composition and a silicone rubber sheet were produced in the same manner as in Example 1 except that the magnesium oxide fine particles of Example 1 were omitted. The characteristics are also shown in Table 1. The silicone rubber sheet of Comparative Example 2 is excellent in tensile strength and conductivity, but is inferior in heat dissipation and, when used as a cushioning material for a liquid crystal display, has excellent mechanical strength and antistatic properties, and Although the workability of assembling into the substrate was good, the heat dissipation was poor, so that it could not withstand the bonding treatment at 300 ° C. for 30 seconds.

Comparative Example 3 Comparative Example 3 was carried out in the same manner as in Example 1 except that the magnesium oxide fine particles and carbon black in Example 1 were omitted, and the base compound was used as a silicone rubber composition.
Was manufactured. The characteristics are also shown in Table 1. The silicone rubber sheet of Comparative Example 3 is excellent in mechanical strength, but inferior in heat dissipation and conductivity, of low quality, and inferior in antistatic properties when used as a cushioning material for a liquid crystal display. The sheet is charged at the time of unwinding, the sheet is attracted by static electricity, the workability of assembling into a liquid crystal display is poor, and the heat dissipation is poor,
It could not withstand the bonding treatment at 300 ° C. for 30 seconds.

Example 2 The fumed silica, magnesium oxide fine particles and carbon black of Example 1 were individually compounded. That is, a blend of 100 parts of organopolysiloxane and 100 parts of fumed silica, organopolysiloxane 10
0 parts and a mixture of 500 parts of magnesium oxide fine particles and a mixture of 100 parts of organopolysiloxane and 40 parts of conductive carbon black were separately prepared, and 40 parts of a mixture of fumed silica and 50 parts of a magnesium oxide particle were prepared.
Parts and 10 parts of the carbon black blend were added to the base compound of Example 1 and re-kneaded to produce a silicone rubber composition.

Using the above silicone rubber composition, a silicone rubber sheet was produced in the same manner as in Example 1. The characteristics are also shown in Table 1. The silicone rubber sheet of Example 2 was excellent in all characteristics and high in quality as in Example 1, and was highly practical as a cushion material for a liquid crystal display.

Example 3 A silicone rubber sheet was produced in the same manner as in Example 2 except that 300 parts of boron nitride fine particles having a thermal conductivity of 71 W / (m. ° C.) were used instead of 500 parts of magnesium oxide fine particles of Example 2. did. The properties of the obtained silicone rubber sheet are also shown in Table 1. As in Example 1, the silicone rubber sheet of Example 3 was excellent in all characteristics and of high quality, and was highly practical as a cushioning material for a liquid crystal display.

Example 4 A silicone rubber sheet was prepared in the same manner as in Example 2, except that 500 parts of the magnesium oxide fine particles of Example 2 were replaced with 150 parts of aluminum nitride fine particles having a thermal conductivity of 178 W / (m · ° C.). Manufactured. The properties of the obtained silicone rubber sheet are also shown in Table 1. As in Example 1, the silicone rubber sheet of Example 4 was excellent in all the characteristics and of high quality, and was highly practical as a cushioning material for a liquid crystal display.

[0042]

The invention according to claim 1 is excellent in heat resistance, mechanical strength and heat radiation, and when used as a cushioning material for a liquid crystal display, has excellent processing operability in an assembly process of the liquid crystal display. To increase the productivity of LCDs,
Since the cost can be reduced, it can be suitably applied as a cushion material for a liquid crystal display. Since the second aspect of the present invention is obtained by imparting conductivity to the first aspect of the present invention, it is possible to prevent the occurrence of static electricity in the assembly process of the liquid crystal display and to further improve the workability. it can.

The third aspect of the present invention is the first or second aspect.
In the invention described in (1), since the thickness of the silicone rubber sheet is limited, the balance between the strength and heat dissipation of the silicone rubber sheet is good, and the above-described processability is further improved. Furthermore, the invention according to claim 4 uses fine silica particles, heat conductive fine particles having a heat conductivity (15 W / (m · ° C.) or more) and conductive carbon black as an additive. Good thermal conductivity and conductivity can be easily provided without lowering the strength, and the practicality is further improved.

According to the fifth aspect of the present invention, a silicone rubber sheet suitable as the cushioning material for a liquid crystal display can be manufactured economically, stably and easily. According to the invention of claim 6, the thickness is small,
In addition, a silicone rubber sheet which is uniform with high accuracy and particularly suitable as the cushioning material for a liquid crystal display can be easily manufactured.

Claims (6)

[Claims] 1. A silicone rubber sheet having a tensile strength of 390 N / cm ² or more and a thermal conductivity of 0.4 W /
(M · ° C.) or higher. 2. The cushion material for a liquid crystal display according to claim 1, wherein the silicone rubber sheet has a volume resistivity of 10 ¹² Ω · cm or less. 3. The thickness of the silicone rubber sheet is 0.03.
The cushion material for a liquid crystal display according to claim 1 or 2, which has a thickness of 0.5 mm. 4. The silicone rubber composition according to claim 1, wherein the silicone rubber sheet comprises fine silica particles, heat conductive fine particles having a thermal conductivity of 15 W / (m · ° C.) or more, and conductive carbon black. The cushioning material for a liquid crystal display according to any one of the above. 5. Fine silica particles, thermal conductivity 15 W / (m
(C) forming a silicone rubber composition containing heat conductive fine particles of not less than (C) or more and conductive carbon black into a sheet, followed by crosslinking.
The method for producing a cushion material for a liquid crystal display device according to any one of the above. 6. A silicone rubber composition is dissolved in a solvent to form a rubber solution having a solid content of 10 to 50% by weight. This rubber solution is coated on a release support film made of polyethylene terephthalate, dried, and then dried. The method for producing a cushion material for a liquid crystal display according to claim 5, wherein the silicone rubber composition on the support film is cross-linked by electron beam irradiation, and then the support film is peeled off.