KR20040082725A - Primer Composition - Google Patents

Abstract

PURPOSE: A primer composition is provided to improve adhesive strength between a silicone adhesive and a film, thereby improving cutting properties of the silicone tape and improving preciseness when being used in a mask process. By using the composition, excellent adhesiveness to silicone is provided, thereby preventing the silicone adhesive from being removed together with a release tape. Further, the composition provides excellent effects in both silicone pressure-sensitive adhesives using a platinum curing agent or a peroxide curing agent. CONSTITUTION: The primer composition comprises: 100pts.wt of a polydiorganosiloxane having a hydroxyl group at each end of the chain; 15-60pts.wt of a polyorganosiloxane resin having less than 0.7% of hydroxyl groups bonded to the silicone; 4-15pts.wt of a polyhydrogenorganosiloxane crosslinking agent having two or more hydrogen atoms connected to the silicon atom, and having 10cST or more of viscosity at 25deg.C; and a catalytic amount of a curing agent, wherein the polydiorganosiloxane having a hydroxyl group at each end of the chain is a compound represented by the following formula 1: HOR2SiO(R2SiO)mSiR2OH, in which R is independently a monovalent hydrocarbon or a halogenated hydrocarbon and m is an integer which provides 1000 or more viscosity at 25deg.C.

Description

Primer Composition

The present invention relates to novel primer compositions. In particular, the present invention relates to novel primer compositions useful for improving adhesion between a silicone pressure sensitive adhesive and a substrate. Silicone adhesive excellent in heat resistance forms an adhesive layer based on films, such as polyester and a polyimide, and is used as an adhesive tape etc. At this time, since the silicone adhesive and the substrate are separated from each other without adhesion, a primer is used to bond the two. As such primers, silicone primers composed of polyorganosiloxanes blocked with hydroxy groups, polyorganosiloxanes having hydrogen atoms bonded to silicon, and tin catalysts have been conventionally used.

However, these primers had two problems. The first is that the performance of the primer is not perfect and the quality stability is not satisfactory. Secondly, the silicone pressure sensitive adhesive is generally cured by a peroxide or by a platinum catalyst. When the primer used for the silicone pressure sensitive adhesive is cured by a platinum catalyst, the platinum catalyst is hardened to the peroxide. There is a concern that it may be easily contaminated and lose its performance, and when the primer used for the silicone pressure-sensitive adhesive cured by the platinum catalyst is cured by the tin catalyst, it may be difficult to cure the silicone pressure-sensitive adhesive due to the tin catalyst. It can be caused by poor curing.

Japanese Patent Application Laid-open No. 52-29831 discloses a very common conventional primer composition for curing polyorganosiloxanes having a hydrogenated atom bonded to polyorganosiloxane and a silicon terminated with a hydroxy group with a tin catalyst. have.

Japanese Patent Application Laid-Open No. 54-61242 discloses (A) a partially condensed organopolysiloxane of a copolymer in which a diorganopolysiloxane and at least one hydroxy group are bonded directly to a silicon atom, (B) an organohydrogen polysiloxane, and (C) A primer composition consisting of platinum catalyst was used. This primer composition is a product that improves the reactivity with a film substrate by reacting a silane, that is, tetraethoxysilane, with a polymer, and is a composition using only a platinum catalyst. The cutting performance was not good, and special care was needed to prevent the catalyst poison in using the platinum catalyst.

Japanese Patent Application Laid-Open No. 3-28283 discloses a primer composition using a copolymer of acryl and polyorganosiloxane to improve adhesion to a film as a primer composition using a tin catalyst. This primer composition also did not provide perfect adhesion, and the use of platinum-type silicone adhesive showed curing inhibition.

As described above, the primer composition has been used to improve the adhesive force between the silicone adhesive and the substrate, but it has not provided a satisfactory property such as unstable adhesive properties. Therefore, a primer composition having stable adhesive properties and improved adhesion between the pressure-sensitive adhesive and the substrate is strongly desired.

As a result of various studies on the primer composition having stable adhesive properties and improved adhesion between the pressure-sensitive adhesive and the substrate, the inventors have found that 100 parts by weight of polydiorganosiloxane having a hydroxyl group at the end and 0.7% by weight of the silicon-bonded hydroxy group are present. 15 to 60 parts by weight of a polyorganosiloxane resin having less than 2 hydrogen atoms bonded to a silicon atom, containing 4 to 15 parts by weight of a polyhydrogenorganosiloxane crosslinking agent having a viscosity of 10 cST or more at 25 ° C, and a curing agent catalyst amount It has been found that the primer composition characterized by the above-mentioned conditions fulfills the present invention.

Therefore, an object of the present invention is to provide a primer composition of the composition as described above to have a stable adhesive properties of the adhesive tape, and to improve the adhesive force between the adhesive and the substrate.

According to the present invention, there is provided a primer composition characterized by containing the following components (a)-(d).

(a) 100 parts by weight of polydiorganosiloxane having a hydroxy group at the terminal,

(b) 15 to 60 parts by weight of polyorganosiloxane resin having less than 0.7% by weight of silicon-bonded hydroxy group,

(c) 4 to 15 parts by weight of a polyhydrogenorganosiloxane crosslinking agent having two or more hydrogen atoms bonded to a silicon atom and having a viscosity of 10 cST or more at 25 ° C .;

(d) Curing agent catalyst amount.

Component (a) in the present invention is a polydiorganosiloxane having a hydroxyl group at the end. This component (a) represents a polymer, ie a polydiorganosiloxane fluid or gum. This polydiorganosiloxane is represented by following formula (1).

HOR ₂ SiO (R ₂ SiO) _m SiR ₂ OH

In the formula, R independently represents a monovalent hydrocarbon group or a halogenated hydrocarbon group. Examples of monovalent hydrocarbon groups include alkyl groups such as methyl, ethyl, propyl, and butyl; Aryl groups such as phenyl and naphthyl; Alkoxy groups, such as a methoxy, ethoxy, and a propoxy group, are mentioned. As a halogenated hydrocarbon group, the hydrocarbon group in which one or more substituents were substituted by halogen groups, such as fluorine, chlorine, and bromine, is mentioned. m is an integer giving a viscosity (3,000,000 cST or more) corresponding to 1,000 cST to gum at 25 ° C.

Component (b) is a polyorganosiloxane resin having less than 0.7% by weight of silicon-bonded hydroxy groups, soluble in organic solvents, represented by the following formula (2).

_{R 'n SiO (4-n} ) / 2

Wherein R 'represents a monovalent hydrocarbon group, and n is 0.6 to 1.7.

The polyorganosiloxane resins useful in the present invention generally include organic solvent-soluble polyorganosiloxane resins such as hexaorganodisiloxane (Me ₂ ViSiOSiViMe ₂ ), hexaorganodisilazane (Me ₃ SiNHSiMe ₃ ) and triorganochlorosilane (Me). Prepared by reacting with a terminal blocker such as ₃ SiCl) to reduce the hydroxy content to less than 0.7% by weight, preferably less than 0.33% by weight. Typical organic solvent-soluble polyorganosiloxane resins are prepared by conventional methods known in the art. Xylene-soluble polyorganosiloxane resins contain large amounts of RSiO _3/2 (unit T) and / or SiO _4/2 (unit Q), with R ₂ SiO _2/2 (unit D) and R ₃ SiO _1/2 ( Small amounts of unit M) may be present. For example, xylene-soluble polyorganosiloxane resins containing unit M and unit Q are called MQ resins and are disclosed in US Pat. No. 2,676,182 and the like. In addition, T resins containing only unit T, MT resins containing unit M and unit T are well known.

The common organic solvent-soluble polysiloxane resin contains about 2 to about 3 weight percent of hydroxy groups. In order to use it in the present invention, the OH content should be reduced to less than 0.7 wt%, preferably less than 0.3 wt% by reaction with the terminal blocker. Polyorganosiloxane resins used in the present invention are disclosed in US Pat. No. 4,831,070.

Component (b) is present at 15 to 60 parts by weight, preferably 20 to 50 parts by weight, based on 100 parts by weight of component (a). If component (b) deviates from this lower limit or the upper limit, it does not show excellent performance as a primer.

Component (c) of the present invention is a polyhydrogenorganosiloxane having two or more hydrogen atoms bonded to a silicon atom and having a viscosity of 10 cST or more. This component (c) is represented by following formula (3).

(H) _a R " _3-a SiO (R" ₂ SiO) _m (R "HSiO) _n SiR" _3-a (H) _a

Wherein R ″ independently represents a hydrocarbon group, where a is 0 or 1 and the sum of m and n is less than 70 as an integer sufficient to provide a viscosity of at least 10 cST at 25 ° C., provided that a is 0 N is 2 or more.

Component (c) may be present in an amount of 4 to 15 parts by weight, relative to 100 parts by weight of component (a). Component (c), which acts as a crosslinking agent, is of great importance for the ratio of silicon-bonded hydrogen atoms to hydroxy groups. This ratio ranges from 1: 1 to 20: 1. This amount will be measured by simple mixing and curing test. If the component (c) is out of the lower and upper limits, it does not show excellent performance as a primer.

Component (d) of the present invention is a curing agent that promotes a reaction between an OH group and a hydrogen atom bonded to a silicon atom. The following well known silicone curing agents can be used to cure the compositions of the present invention.

Metal salts of carboxylic acids such as zinc octoate, lead-2-ethyl hexate, lead naphthenate, dibutyltin diacetate, dibutyltindilactate, tin octoate, zinc naphtanate and iron octoate, etc. Reaction catalyst ".

Platinum containing catalysts such as chloroplatinic acid, platinum on charcoal and chloroplatinic acid complexing with various liquids, etc. and rhodium containing catalysts-called "hydrosilylation catalysts".

The curing agent, which is a metal salt of carboxylic acid, is used in an amount of 10 to 30 parts by weight based on 100 parts by weight of component (a). This platinum-containing catalyst may be present in an amount of 10 to 100 ppm. The catalytic amount of the curing agent can be measured by a simple test. The smaller the amount of hardener, the longer the hardening time, and the higher the amount of hardener, the more accelerated curing may be, but more than necessary.

The primer composition is an additive such as a curing accelerator for a condensation reaction catalyst and an inhibitor of a hydrosilylation reaction (a reaction between an alkenyl group bonded to a silicon atom of one polyorganosiloxane and hydrogen bonded to a silicon atom of another polyorganosiloxane). It may further contain. These additives are well known in the art.

The primer composition of the present invention can be applied to a substrate by a conventional coating method. The substrate to be coated by the primer composition is, for example, a PET film, a polyamide film, or the like as a substrate on which a silicone film such as Si-PSA is usually applied thereon. This substrate is commercially available.

In general, Si-PSA is classified into two types according to the curing reaction type.

1. Si-PSA in Peroxide Cured Form: This form of Si-PSA is cured using organic peroxide as the curing agent. Curing is carried out by a radical reaction between the carbon of the methyl group and the organic peroxide present in the polyorganosiloxane.

2. Si-PSA in platinum cured form: This Si-PSA is cured using the above-described platinum catalyst. Curing is carried out by a reaction between a hydroxy group present in the polyorganosiloxane and hydrogen bonded to a silicon atom present in the polyorganosiloxane.

These forms of Si-PSA are commercially available from Dow Corning Corporation, USA under the trade names Dow Corning 7335 Adhesive and Dow Corning 7657 Adhesive.

Example 1:

<Preparation of Primer Composition>

The following descriptions used in the examples of the primer composition have the following components.

OH siloxane solution

OH endblocked polydimethylsiloxane gum with a plasticity of 60. "OH siloxane solution" is a toluene solution containing 30% by weight of OH siloxane.

-Capped Si resin

Xylene- _solubles containing silicon-bonded hydroxy groups, treated with hexamethyldisilazane to reduce the silicon-bonded hydroxy content to less than 0.33% by weight and having trimethylsiloxane units of 0.7 per SiO _4/2 units. Polymethylsiloxane resin. "Capped resin solution" is a xylene solution containing 70% by weight of capped resin.

-Uncapped Si resin

Xylene-soluble polymethylsiloxane resin containing 2.5% by weight of silicon-bonded hydroxy groups and having 0.7 trimethylsiloxane units per SiO _4/2 unit. This Si resin produced by the method described in US Pat. No. 2,676,18 to Daudt et al. Was a resin that was not treated with hexamethyldisilazane to form a capped Si resin as described above. "Unblocked Si resin solution" is a xylene solution containing 80% by weight of Si resin.

-H siloxane

Polymethylhydrogensiloxane blocked end by trimethylsiloxy units having a viscosity of 20 cps at 25 ° C.

-Tin hardener

Dibutyl diacetate.

-Curing accelerator

Polymethyl (dimethylaminoethoxy) siloxane.

<Composition A>

1 g of the capped resin solution was mixed with 5.83 g of OH siloxane solution to form a first composition. 0.1 g of H siloxane, 0.3 g of tin curing agent, and 0.15 g of a curing accelerator were added to the first composition, followed by 93 g of heptane to form a primer composition (composition A).

<Composition B-F>

Compositions B-F were prepared in the same manner as in composition A, except that each component was used in the same amount as in Table 1a.

Usage of Raw Material (Unit: g) Composition OH siloxane solution Capped Si Resin Solution H siloxane Tin Hardener Curing accelerator Heptane Composition B 5.83 One 0.18 0.3 0.15 93 Composition C 5 1.4 0.08 0.3 0.15 93 Composition D 7.5 0.36 0.1 0.3 0.15 93 Composition E 6.67 0.71 0.1 0.3 0.15 93 Composition F 5.83 1.06 ^* 0.1 0.3 0 93.1

Composition F used uncapped Si resin instead of capped Si resin

The amount of each component was recalculated based on 100 parts by weight of OH siloxane. The results are shown in Table 1b below.

The amount of raw materials calculated based on 100 parts by weight of OH siloxane (unit: parts by weight) Composition OH siloxane solution Capped Si Resin H siloxane Tin hardener Curing accelerator Composition A 100.0 40.0 5.7 17.2 8.6 Composition B 100.0 40.0 10.3 17.2 8.6 Composition C 100.0 65.3 5.3 20.0 10.0 Composition D 100.0 11.2 4.4 13.3 6.7 Composition E 100.0 24.8 5.0 15.0 7.5 Composition F 100.0 48.5 ^* 5.7 11.4 0

Composition F used uncapped Si resin instead of capped Si resin

<Performance Test of Composition>

The primer composition was coated onto a 50 micron thick PET film substrate (commercially available from Nan Ya Pleastic Co.) using the Meyer Rod 8th method. This primer coating was cured under the conditions shown in Table 2 below, and then left for 24 hours.

Si-PSA, which can be cured by peroxide, is applied onto the primer surface of a PET film and then cured by heating at 70 ° C. for 2 minutes and at 178 ° C. for 2 minutes to have a 5.1 mm thick adhesive layer of silicone. PSA tape was formed. Si-PSA that can be cured by the peroxide used contains 100 parts by weight of the trademark “Dow Corning 7355 Adhesive”, 2 parts by weight of benzoyl peroxide and 50 parts by weight of toluene.

Silicone PSA tapes were evaluated by a legging test and a Folding Anchorage Test (FAT). In the legging test, "Cohesive Failure" means good performance, and "Adhesive Failure" means unsatisfactory performance. "Normal" or "excellent" in FAT indicates good performance, and "bad" indicates unsatisfactory. These results are shown in Table 2 below.

Legging Test & FAT Check Composition Curing condition of the primer Legging test Primer adhesion test Composition A 120 ℃ X 120 seconds Clean fall Great 120 ℃ X 60 seconds Clean fall Great 120 ℃ X 30 seconds Clean fall Great Composition B 120 ℃ X 120 seconds Clean fall usually 120 ℃ X 60 seconds Clean fall Normal / excellent 120 ℃ X 30 seconds Clean fall Great Composition C 120 ℃ X 120 seconds 0.5cm Leggings Occur usually Composition D Not measurable 2 cm leggings Not good Composition E Not measurable Clean fall Great Composition F 120 ℃ X 120sec120 ℃ X 60sec120 ℃ X 30sec 9cm leggings happen -

Primer compositions of the present invention containing a limited amount of capped Si resin provide superior Si-PSA adhesion on PET substrates as compared to compositions without such capped Si resin.

Example 2:

<Preparation of Primer Composition>

The composition M was found to be the same as the composition A except for the organic solvent. Compositions M and N were prepared in the same manner as described above, except that each component was used in the amounts shown in Table 3a.

Usage of Raw Material (Unit: g) OH siloxane solution Capped Si Resin Solution H siloxane Tin Hardener Curing accelerator H siloxane ^* & inhibitor Platinum hardener liquid toluene Composition M 5.83 One 0.1 0.3 0.15 - - 93 Composition N 5.83 One - - - 0.1 0.08 93

In the above table, "OH siloxane solution", "capped Si resin solution", "H siloxane", "tin curing agent" and "hardening accelerator" are as described above.

-H siloxane ^* & inhibitor

A mixture of 97.5% of polymethylhydrogen siloxane and 2.5% of methyl butynol having a viscosity at 25 ° C. of 10 cST and which is terminally blocked by trimethylsiloxy units.

-Platinum hardener liquid

A platinum-divinyltetramethyldisiloxane complex containing 1.5% of a platinum complex diluted with dimethylvinyl terminated with polydimethylsiloxane having a viscosity of 450 csT at 25 ° C. This platinum complex was prepared by the method described in US Pat. No. 5,175,325.

The amount of each component was recalculated based on 100 parts by weight of OH siloxane. The results are shown in Table 3b below.

The amount of raw materials calculated based on 100 parts by weight of OH siloxane (unit: parts by weight) OH siloxane solution Capped Si Resin Solution H siloxane Tin Hardener Curing accelerator H siloxane ^* Inhibitor Platinum hardener liquid Composition M 100.0 40.0 5.7 17.2 8.6 - - - Composition N 100.0 40.0 - - - 5.6 0.14 4.6

<Performance Test of Composition>

These primer compositions were coated in the same manner as in Example 1 and then cured under the conditions shown in Table 4 below.

Legging Test & FAT Check Curing condition of the primer Legging test Primer adhesion test Composition M 120 ° C. X 30 seconds; Dow Corning 7355 Adhesive Clean fall Great 120 ° C x 30 seconds: Dow Corning 7657 Adhesive Clean fall Great Composition N 120 ° C x 30 seconds: Dow Corning 7355 Adhesive Clean fall Great 120 ° C x 30 seconds: Dow Corning 7657 Adhesive Clean fall Great

Silicon PSA as in Example 1 by applying Si-PSA, which can be cured by peroxide, to the surface of each of the primer compositions M, N and then cured by heating at 70 ° C. for 2 minutes and at 178 ° C. for 2 minutes. The tape was formed.

In addition, a silicon PSA tape was formed by applying Si-PSA, which can be cured by platinum, to the surface of each of the primer compositions M, N and then curing at 120 ° C. for 2 minutes. Si-PSA, which can be cured by the peroxide used, contains 100 parts by weight of the "Dow Corning 7355 Adhesive", 2 parts by weight of benzoyl peroxide and 50 parts by weight of toluene as in Example 1. Si-PSA that can be cured by the platinum used contains 100 parts by weight of the registered "Dow Corning 7657 adhesive" and 0.5 parts by weight of the trademark "SYL-OFF 4000 catalyst".

Their legging test and FAT test results are as shown in Table 4 above.

The primer composition of the present invention further improves the adhesive strength of the silicone pressure-sensitive adhesive and the film, thereby making it possible to precisely mask when used for masking by excellent cutting property of the silicone tape, and other primer compositions have excellent adhesion with silicone. Therefore, it provides an effect that the silicone adhesive is not removed together with the release paper or release film in actual use. In addition, when the primer composition of the present invention is used in the pressure-sensitive adhesive silicone, it provides excellent effects in both the platinum curable type and the peroxide curable type. That is, it can be cured using platinum or tin as a curing agent at the user's option.

Claims (4)

(a) 100 parts by weight of polydiorganosiloxane having a hydroxy group at the terminal, (b) 15 to 60 parts by weight of a polyorganosiloxane resin having less than 0.7% by weight of a silicon-bonded hydroxy group, (c) 4 to 15 parts by weight of a polyhydrogenorganosiloxane crosslinking agent having two or more hydrogen atoms bonded to a silicon atom and having a viscosity of 10 cST or more at 25 ° C .; (d) Curing agent catalyst amount Primer composition comprising a. The primer composition of claim 1, which is useful for improving adhesion between the silicone adhesive and the substrate. The primer composition according to claim 1, wherein the polydiorganosiloxane (a) having a hydroxy group at the terminal is a compound represented by the following Chemical Formula 1. Formula 1 HOR ₂ SiO (R ₂ SiO) _m SiR ₂ OH In the above formula, R independently represents a monovalent hydrocarbon group or a halogenated hydrocarbon group, m is an integer giving a viscosity of at least 1,000 at 25 ° C. The polyorganosiloxane resin (b) having a silicon-bonded hydroxy group of less than 0.7% by weight is reacted with a xylene soluble polysiloxane resin of formula By reducing the hydroxy content to less than 0.7% by weight. Formula 2 _{R 'n SiO (4-n} ) / 2 In the above formula, R 'represents a monovalent hydrocarbon group, n is 0.6 to 1.7.