KR20110119140A - Curable silicone composition for solvent-free pressure sensitive adhesive - Google Patents

Abstract

PURPOSE: A curable silicone composition and an adhesive manufactured therefrom are provided to ensure high temperature agglomeration intensity while ensuring excellent adhesive properties since an M^OHQ resin is used and an organic solvent is not used. CONSTITUTION: A curable silicone composition comprises (a) 10-50 parts by weight of an M^OHQ resin, (b) 20-60 parts by weight of silicone gum having a number average molecular weight of 100,000-900,000, (c) 5-10 parts by weight of polyorganohydrogen siloxane which has a number average molecular weight of 4,000-8,000 and includes two or more hydrogen groups directly bonded with silicon atoms, wherein a substituent directly bonded with silicon atoms excluding the hydrogen groups is a C1-C10 hydrocarbon group without aliphatic unsaturated bonds, (d) 0.1-1 parts by weight of a hydrosilylation metal catalyst as a crosslinking accelerator, and (e) 20-60 parts by weight of volatile silicone oil as a diluent.

Description

Curable silicone composition for solvent-free pressure-sensitive adhesive {CURABLE SILICONE COMPOSITION FOR SOLVENT-FREE PRESSURE SENSITIVE ADHESIVE}

The present invention relates to silicone compositions suitable for making pressure sensitive adhesives (PSA). More particularly, the present invention relates to an addition curable silicone composition suitable for preparing a solvent-free pressure-sensitive adhesive having improved high temperature cohesive strength while retaining good adhesion and adhesion.

A pressure-sensitive adhesive can be adhered to the surface to be adhered sufficiently even at low pressure, and even when it is pulled out, it can be easily peeled off without leaving a trace on the surface to be adhered to. Say.

Among these, silicone pressure-sensitive adhesives have adhesive properties such as adhesive tapes, bandages, low temperature supports, transfer films, labels, automotive parts, etc. Used to assemble toys, electronic circuits and keyboards.

Addition curable silicone compositions useful for making silicone-based pressure sensitive adhesives are known in the art. Silicone compositions containing alkenyl containing polyorganosiloxanes, polyorganosiloxane resins, polyorganohydrogensiloxanes, and hydrosilylation catalysts are described in US Pat. Nos. 4,998,779, 4,774,297, 3,983,298.

The polyorganosiloxane can spleen called MQ resin essentially as R _{¹ 3} SiO _^1/2 polymers consisting of (M units) and SiO _4/2 units (Q units) where R ¹ is a group directly bonded to a silicon atom of hydrogen, A functional group such as a vinyl group or an OH group or a nonfunctional organic group such as a methyl group or an ethyl group. These resins may comprise a portion of R ^{₂ 2} SiO _^2/2, and R _{³ 1} siO _^3/2 units known as D and T units, respectively. The term MQ resin, as used generally, means that on average only 20 mole percent of the resin molecule contains D and T units. M ^OH Q resin containing Si-H groups has the formula of ^{_{(R 1 3 SiO 1/2) w}} (R 2 2 SiO 2/2) x (R 3 1 SiO 3/2) y (SiO 4/2) z Has Wherein R ¹ , R ² and R ³ are each independently a hydrogen group directly bonded to a silicon atom, a functional group such as a vinyl or OH group, or a C ₁ -C ₆ nonfunctional hydrocarbon group such as a methyl or ethyl group, wherein ^one of R ¹ Is necessarily an OH group and any one of the remaining R ¹ , R ² and R ³ is necessarily a hydrogen group, w, z> 0 and x, y ≧ 0, provided that w + x + y + z = 1, where 0 ≦ {(x + y) / 2} ≦ 0.4. If w, z ≤ 0, and y <0 it does not have a M unit and Q unit to have a suitable crosslink density, in which case the hardness of the cured rubber may be too low or too high.

The present invention provides an addition-curable silicone composition comprising a polyorganosiloxane resin called an M ^OH Q resin and an alkenyl-containing silicone gum. The present invention also provides Silicone Pressure Sensitive Adhesives (Silicone PSA) made from such compositions.

The present invention ^{_{(R 1 3 SiO 1/2}} ) w (R 2 2 SiO 2/2) x (R 3 1 SiO 3/2) y (SiO 4/2) ( where R ^1, R having the formula _z ² and R ³ are each independently a hydrogen group, a vinyl group, an OH group or a C ₁ -C ₆ hydrocarbon group directly bonded to a silicon atom, wherein one of R ¹ is necessarily an OH group and the remaining R ¹ , R ² and R ³ Any one of which is necessarily a hydrogen group, w, z> 0, x, y ≥ 0, provided that w + x + y + z = 1, 0≤ {(x + y) / 2} ≤ 0.4 M ^OH Q resin) Using a polyorganosiloxane resin containing M units and Q units and an ultra high viscosity alkenyl-containing silicon gum having a number average molecular weight of 100,000 to 900,000, excellent crosslinking strength and high crosslinking of three-dimensional network structure By maintaining the density, the adhesive property of the product is maintained after a certain period of time, the curing time can be shortened compared to the existing products, and to prepare a silicone pressure-sensitive adhesive without using an organic solvent It provides an addition-curable silicone composition for.

The present invention and more particularly of the formula ^{_{(R 1 3 SiO 1/2}} ) w (R 2 2 SiO 2/2) x (R 3 1 SiO 3/2) y (SiO 4/2) z ( wherein R ^1, R ² and R ³ are each a hydrogen group, a vinyl group, an OH group or a C ₁ -C ₆ hydrocarbon group directly bonded to a silicon atom, wherein one of R ¹ is necessarily an OH group and the other of R ¹ , R ² and R ³ One is necessarily a hydrogen group, w, z> 0, x, y ≥ 0, except w + x + y + z = 1, 0≤ {(x + y) / 2} ≤0.4. 10 to 50 parts by weight of M ^OH Q resin having; b) 20 to 60 parts by weight of a silicone gum having a number average molecular weight of 100,000 to 900,000 and having the following structural formula

Wherein R ⁴ , R ⁵ and R ⁶ are each independently a substituent selected from C ₁ -C ₁₀ alkyl and alkenyl groups, m is from 100 to 10,000 and the silicone gum contains at least two alkenyl groups; c) a number average molecular weight of 4,000 to 8,000 and includes two or more hydrogens directly bonded to silicon atoms, wherein the substituents directly bonded to silicon atoms except hydrogen are C ₁ -C ₁₀ hydrocarbon groups without aliphatic unsaturated bonds 5 to 10 parts by weight of polyorganohydrogen siloxane; d) 0.1 to 1 parts by weight of a hydrosilylation metal catalyst as a crosslinking accelerator; And e) 20 to 60 parts by weight of a volatile silicone oil as a diluent.

In the case of the M ^OH Q resin corresponding to component a) of the present invention, the number average molecular weight (Mn) is generally in the range of 3,000 to 8,000 and the weight average molecular weight (Mw) as measured by resin-corrected gel permeation chromatography (GPC). ) Ranges from 10,000 to 30,000. The M ^OH Q resin is preferably used in an amount of 10 to 50 parts by weight.

In the case of silicone gum corresponding to component b) of the present invention, it exhibits a high viscosity of 100,000 to 1,000,000 cps at 25 ° C. and 50% relative humidity, wherein the alkenyl group is preferably a vinyl group and more preferably an amount of silicone gum. The terminal is a vinyl group. When the alkenyl group is a vinyl group, it is preferable that at least 95% of the total substituents are methyl groups and the vinyl group constitute 1.0 to 3.0 mol% of the total organic groups bonded to the silicon atoms in the silicon gum.

The polyorganohydrogensiloxane corresponding to component c) of the present invention comprises two or more hydrogen groups directly bonded to silicon atoms in one monomer, and the silicon-bonded hydrogen group is located at the terminal or side chain of the polyorganohydrogensiloxane And side chains. Substituents directly bonded to silicon atoms other than hydrogen groups are C ₁ -C ₁₀ hydrocarbon groups which are free of aliphatic unsaturated bonds for compatibility with the above components and are preferably methyl groups. The polyorganohydrogensiloxane has a viscosity of 0.1 to 0.4 cps at 25 ℃, 50% relative humidity, the number average molecular weight is preferably 4,000 to 8,000, the ratio between the hydrogen and other substituents directly bonded to silicon is 50:50 It is preferable.

In the case of the hydrosilylation metal catalysts corresponding to component d) of the invention, the addition reaction of components b) with components a) and c) is promoted, wherein the metal comprises platinum, rhodium, ruthenium, palladium and iridium. Preferably the metal is platinum and the hydrosilylation platinum catalyst is a well known hydrosilylation catalyst comprising a platinum group metal, a compound containing a platinum group metal, or a microencapsulated platinum group metal or a compound containing the same. Hydrosilylation platinum catalyst, more preferably a _{[{(CH 2 = CH)} (CH 3) 2 SiO 1/2} p] q as a complex between (here a p = 2, q is 4 or 6 Im) and platinum Although the amount is a catalytic amount, it is preferable to use 0.1-1 weight part with respect to the total amount of a composition.

Conventional compositions have to use an appropriate amount of organic solvents such as toluene or xylene to reduce viscosity and ease of manufacture, handling and application, but in the present invention, such organic solvents have been used in the present invention to address environmental problems and to apply to humans. did not use. In the present invention, 20 to 60 parts by weight of a volatile silicone oil was used as a diluent corresponding to component e) instead of such an organic solvent, and as an example of volatile silicone oil, a low viscosity methyl silicone oil, octamethylcyclo tetrasiloxane, hexamethyl Cyclotrisiloxane etc. are mentioned.

The composition of the present invention may further comprise a retardant as optional component f). This retardant is used to prevent the curing of the adhesive from occurring below a predetermined temperature and to prevent excessive curing. In general, although not essential to the function of the coating itself, the catalyst can, in the absence of a retardant, initiate or catalyze the curing of the silicone composition at ambient temperature. Retarders delay the curing of the silicone composition of the present invention at room temperature but do not interfere with curing at elevated temperatures. Suitable retardants should be soluble in the silicone composition, such as 3-methyl-3-pentin-1 phosphorus and 3,5-dimethyl-3-hexene-1-yne, 3-5-dimethyl-1-hexyn-3-ol Acetylene alcohols are preferred, and maleates and fumarates may also be used. The composition containing the retardant is preferably included in the composition at 0.1 to 0.5 parts by weight for effective curing, and requires heating at 70 ° C or higher.

The addition-curable silicone composition of the present invention and the adhesive prepared therefrom, unlike the conventional silicone composition and the adhesive prepared therefrom, use an M ^OH Q resin and do not use an organic solvent, thus improving the adhesiveness and adhesion while maintaining excellent adhesiveness and adhesion. High temperature cohesive strength.

The present invention is explained in more detail by the following examples and comparative examples. The following examples are merely examples for illustrating the present invention and are not intended to limit the protection scope of the present invention.

All percentages are by weight and all measurements are taken at 25 ° C. unless otherwise indicated in this Example and Comparative Examples. The molecular weight characteristics of the M ^OH Q resin were determined by gas phase chromatography (GPC) using polydimethylsiloxane in solvent toluene as a standard.

Nonvolatile matter  content

2 g of adhesive sample was placed in an aluminum sample cup and heated in an oven at 150 ° C. for 1 hour, and the weight of the residue was measured as a percentage of the original sample weight.

Materials used in the examples and comparative examples are as follows unless otherwise specified.

Component a) M ^OH Q resin: molar ratio M: Q is 0.8: 1.0 and contains 0.2 mol% of hydroxy groups, prepared by condensing dimethylchlorosilane and water-soluble silica sol according to the method disclosed in US Pat. No. 3,627,851, M ^OH Q with molecular weight Mn 4,300 when measured by GPC

Component b) Silicone gum: A siloxane gum containing 1-3 mol% of hydroxy groups and having a viscosity of about 70,000,000 cps at 25 ° C., 50% relative humidity and soluble in benzene with Mw 13,000, Mw / Mn 3.02.

Component c) Methylhydrogen Fluid: Low Viscosity Polydimethylhydrogensiloxane Fluid with 0.25 mol% Hydrogen

Component d) Catalyst: Platinum complex of 1,3-diethenyl-1,1,3,3, -tetramethyldisiloxane containing about 3.5 parts by weight of platinum.

Component e) Diluent: Octmethylmethyl Tetrasiloxane

Component f) Retardant: 2-Methyl-3-butyn-2-ol

[ Example  One]

a) 24 parts by weight of component a), 25 parts by weight of component b), 7 parts by weight of component c) and 44 parts by weight of component e) are incorporated. To this, 0.1 part by weight of component f) is added to prepare a silicone composition, and 0.01 part by weight of d) component is incorporated per 10 parts by weight of the prepared composition.

As a result, a silicone pressure-sensitive adhesive having a nonvolatile content of 56% and a viscosity of 8,500 cps is produced. The silicone pressure-sensitive adhesive is applied to the polyester film so as to have a dry thickness of 50 μm, and then molded by heating and curing in a 150 ° C. oven for 3 minutes. The viscosity, adhesion and initial adhesion to the cured moldings are tested. The measurement results are shown in Table 1.

[ Example  2]

a) 22 parts by weight of component a), 30 parts by weight of component b), 5 parts by weight of component c) and 43 parts by weight of component e) are incorporated. To this, 0.1 part by weight of component f) is added to prepare a silicone composition, and 0.01 part by weight of d) component is incorporated per 10 parts by weight of the prepared composition.

As a result, a silicone pressure-sensitive adhesive having a nonvolatile content of 57% and a viscosity of 9,000 cps is produced. The silicone pressure-sensitive adhesive is applied to the polyester film so as to have a dry thickness of 50 μm, and then molded by heating and curing in a 150 ° C. oven for 3 minutes. The viscosity, adhesion and initial adhesion to the cured moldings are tested. The measurement results are shown in Table 1.

[ Comparative example  One]

To 24 parts by weight of a) the component b) 30 parts by weight of the component, c) 5 parts by weight of the component and 41 parts by weight of an organic solvent (toluene or xylene) as a diluent. To this, 0.1 part by weight of component f) is added to prepare a silicone composition, and 0.01 part by weight of d) component is incorporated per 10 parts by weight of the prepared composition.

As a result, a silicone pressure-sensitive adhesive having a nonvolatile content of 59% and a viscosity of 9,000 cps is produced. The silicone pressure-sensitive adhesive is applied to the polyester film so as to have a dry thickness of 50 μm, and then molded by heating and curing in a 150 ° C. oven for 3 minutes. The viscosity, adhesion, and initial adhesion to the cured moldings are tested. The measurement results are shown in Table 1.

[ Comparative example  2]

To 22 parts by weight of a) the component b) 25 parts by weight of the component, c) 7 parts by weight of the component and 46 parts by weight of an organic solvent (toluene or xylene) are mixed. To this, 0.1 part by weight of component f) is added to prepare a silicone composition, and 0.01 part by weight of d) component is incorporated per 10 parts by weight of the prepared composition.

As a result, a silicone pressure-sensitive adhesive having a nonvolatile content of 54% and a viscosity of 7,000 cps is produced. The silicone pressure-sensitive adhesive is applied to the polyester film so as to have a dry thickness of 50 μm, and then molded by heating and curing in a 150 ° C. oven for 3 minutes. The viscosity, adhesion and initial adhesion to the cured moldings are tested. The measurement results are shown in Table 1.

Viscosity, adhesion, and initial adhesion of the cured moldings prepared from the silicone compositions shown herein were measured in the following manner.

Viscosity

Cps was measured at 25 ° C. and 50% relative humidity using a Brookfield rotating disk viscometer.

Adhesion

A 6 inch x 1 inch strip of adhesive applied to Mylar® polyester film with a 50 μm dry thickness was cured at 100 ° C. for 2 minutes and 180 ° C. for 2 minutes, then 4.5 lb on a clean 2 inch x 6 inch stainless steel panel. It was measured by applying by pushing twice with a rubber coating roller. The force required to remove the tape from the panel was measured at a rate of 12 in / min at a peel angle of 180 ° using a tensile and rapid peel tester. The recorded value is the average value of the various values read during the process of pulling at a certain interval per sample. The measurements were recorded in g _f (gram force) / inch with the force required to peel off per film thickness.

Initial adhesion

A 6-inch x 1-inch strip of adhesive coated on a Mylar® polyester film with a thickness of 50 µm was cured at 100 ° C for 2 minutes and 180 ° C for 2 minutes. Roll the ball and measure the number of stops of steel ball in a certain section. There is no unit of measured value and it is generally described as Ball No.

TABLE 1

As a result of the experiment, it can be seen that in Examples 1 and 2, the initial adhesive strength and the adhesive strength were higher than those in Comparative Examples 1 and 2.

Claims (15)

a) the formula ^{_{(R 1 3 SiO 1/2}} ) w (R 2 2 SiO 2/2) x (R 3 1 SiO 3/2) y (SiO 4/2) z ( wherein R ^1, R ² and R ³ Are each independently a hydrogen group, a vinyl group, an OH group, or a C ₁ -C ₆ hydrocarbon group directly bonded to a silicon atom, wherein one of R ¹ is necessarily an OH group and one of the remaining R ¹ , R ^2, and R ³ is M ^OH , which is necessarily a hydrogen group, w, z> 0, x, y> 0, with w + x + y + z = 1, where 0≤ {(x + y) / 2} ≤0.4 10 to 50 parts by weight of a Q resin;
b) 20 to 60 parts by weight of a silicone gum having a number average molecular weight of 100,000 to 900,000 and having the following structural formula

Wherein R ⁴ , R ⁵ and R ⁶ are each independently a substituent selected from C ₁ -C ₁₀ alkyl and alkenyl groups, m is from 100 to 10,000 and the silicone gum contains at least two alkenyl groups;
c) a number average molecular weight of 4,000 to 8,000 and includes two or more hydrogen groups directly bonded to silicon atoms, wherein the substituents directly bonded to silicon atoms except hydrogen groups are C ₁ -C ₁₀ hydrocarbon groups without aliphatic unsaturated bonds 5 to 10 parts by weight of polyorganohydrogen siloxane;
d) 0.1 to 1 parts by weight of a hydrosilylation metal catalyst as a crosslinking accelerator; And
e) Curable silicone composition comprising 20 to 60 parts by weight of volatile silicone oil as a diluent. The curable silicone composition of claim 1, wherein the M ^OH Q resin has a number average molecular weight (Mn) of 3,000 to 8,000 and a weight average molecular weight (Mw) of 10,000 to 30,000. The method of claim 1, wherein the alkenyl group of the silicone gum is a vinyl group, in which case at least 95% of the total substituents are methyl groups and the vinyl group is 1.0 to 3.0 mol% of the total organic groups bonded to the silicon atoms in the silicone gum. Curable silicone composition, characterized in that. The curable silicone composition according to claim 3, wherein both ends of the silicone gum are vinyl groups. The curable silicone composition of claim 1, wherein the silicone gum has a viscosity of 100,000 to 1,000,000 cps at 25 ° C. and 50% relative humidity. The curable silicone composition according to claim 1, wherein the hydrocarbon group of the polyorganohydrogensiloxane is a methyl group. The addition curable silicone composition according to claim 1, wherein the polyorganohydrogensiloxane has a viscosity of 0.1 to 0.4 cps at 25 ° C and 50% relative humidity. The curable silicone composition of claim 1, wherein the polyorganohydrogensiloxane has a ratio of 50:50 between hydrogen and other substituents directly bonded to silicon. 2. The curable silicone composition of claim 1 wherein the metal of the hydrosilylation metal catalyst is selected from the group consisting of platinum, rhodium, ruthenium, palladium and iridium. 10. The curable silicone composition of claim 9 wherein the hydrosilylation metal catalyst is a hydrosilylation platinum catalyst. The hydrosilylation platinum catalyst of claim 10 wherein the hydrosilylation platinum catalyst is [{(CH ₂ = CH) (CH ₃ ) ₂ SiO _1/2 } _p ] _q (where p = 2, q is 4 or 6) and platinum Curable silicone composition, characterized in that the complex of the liver. 2. The curable silicone composition of claim 1 wherein the volatile silicone oil is low viscosity methyl silicone oil, octamethylcyclo tetrasiloxane. The curable silicone composition of claim 1, further comprising 0.1 to 0.5 parts by weight of a retardant. The curable silicone composition of claim 13, wherein the retardant is an acetylene alcohol. Pressure-sensitive adhesive prepared from the curable silicone composition of any one of claims 1-14.