KR100989790B1 - Primer Composition - Google Patents

Abstract

By the present invention

(a) 100 parts by weight of polydiorganosiloxane having a hydroxyl 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 at 25 ° C. of 10 cSt or more;

(d) A primer composition is provided, which contains a catalytic amount of a curing agent.

Primers, compositions, adhesives, polyorganosiloxanes, silicones

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 pressure-sensitive adhesive (Si-PSA) having excellent heat resistance is used as an adhesive tape by forming an adhesive layer based on a film such as polyester or polyimide. At this time, since the silicone pressure-sensitive adhesive and the substrate are separated from each other without being adhered well, a primer is used to adhere the two. Such primers have conventionally been used polyorganosiloxanes endblocked with hydroxy groups, polyorganosiloxanes having hydrogen atom (s) bonded to silicon atoms, and silicone primers comprising tin catalysts.

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 pressure sensitive adhesive cured by a peroxide is cured by a platinum catalyst, the platinum catalyst is If the primer used for the pressure-sensitive adhesive cured by the platinum catalyst is cured by the tin catalyst, the pressure-sensitive adhesive is cured due to the tin catalyst. Difficulties in this can lead to poor curing.

Japanese Patent Application Laid-Open No. 52-29831 discloses a very common conventional technique for curing polyorganosiloxanes having a hydroxyl group terminated with a hydroxy group and a polyorganosiloxane having hydrogen atom (s) bonded to silicon atoms. Primer compositions are disclosed.

Japanese Patent Application Laid-Open No. 54-61242 discloses a partial condensation product of a copolymer in which (A) a diorganopolysiloxane and at least one hydroxy group are directly bonded to a silicon atom, (B) an organohydrogenpolysiloxane, and (C A primer composition consisting of a platinum catalyst is described. This primer composition is a product that improves the reactivity with a film substrate by reacting a polymer with silane, that is, tetraethoxysilane, 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 which improves adhesion to a film by using a copolymer of acryl and polyorganosiloxane as a primer composition using a tin catalyst. This primer composition also did not provide perfect adhesion and exhibited a cure inhibitory action when using a pressure sensitive adhesive in the form of platinum.

As described above, the primer composition has been used in order to improve the adhesion between the silicone adhesive and the substrate, but it has not provided a satisfactory property such as unstable adhesive properties. Therefore, there is a strong demand for a primer composition having stable adhesive properties and improved adhesion between the adhesive and the substrate.

As a result of various studies on the primer composition having stable adhesive properties and improved adhesion between the adhesive and the substrate, the inventors have (a) 100 parts by weight of a polydiorganosiloxane having a hydroxy group at the end, and (b) silicon-bonded hydride. 15 to 60 parts by weight of a polyorganosiloxane resin having less than 0.7% by weight of hydroxy group, (c) a polyhydrogenorganosiloxane crosslinker having two or more hydrogen atoms bonded to a silicon atom, and having a viscosity at 25 ° C. of 10 cSt or more 4 The present invention has been accomplished by discovering that a primer composition characterized by containing from 15 parts by weight to (d) a catalytic amount of a curing agent satisfies these conditions.

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, to improve the adhesion 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 hydroxyl 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 at 25 ° C. of 10 cSt or more;

(d) A catalytic amount of hardener.

Component (a) in the present invention is a polydiorganosiloxane having a hydroxyl group at the terminal and having a viscosity at 25 ° C. corresponding to 1,000 cSt to gum (3,000,000 cSt or more). 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) _m1 SiR ₂ OH

In Formula 1 above,
R independently represents a monovalent hydrocarbon group or a halogenated hydrocarbon group,
m1 is an integer such that the viscosity of the polydiorganosiloxane (a) at 25 ° C. becomes a viscosity (3,000,000 cSt or more) corresponding to 1,000 cSt to gum.
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. Halogenated hydrocarbon groups include hydrocarbon groups in which one or more substituents are substituted by halogen groups such as fluorine, chlorine, bromine and the like.

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

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

In Formula 2 above,
R 'represents a monovalent hydrocarbon group,
n is 0.6 to 1.7.

The polyorganosiloxane resins useful in the present invention generally include organic solvent-soluble polyorganosiloxane resins 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 polyorganosiloxane 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% by weight, preferably less than 0.3% by weight 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 at 25 ° C. of 10 cSt or more. This component (c) is represented by following formula (3).

(H) _a R " _3-a SiO (R" ₂ SiO) _m2 (R "HSiO) _n SiR" _3-a (H) _a

In Formula 3 above,
R ″ independently represents a hydrocarbon group,
a is 0 or 1,
The sum of m2 and n is less than 70 as an integer such that the viscosity of the polyhydroorganosiloxane (c) at 25 ° C is 10 cSt or more,
However, when a is 0, n is two 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, tin octoate, zinc naphtanate and iron octoate, etc.-called "condensation reaction catalysts" , And

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 hardener can be measured by simple tests. The smaller the amount of the curing agent, the longer the curing time, and the larger the amount of curing agent may promote the curing, but more than necessary amount may be consumed.

The primer composition is a reaction between a curing accelerator for a condensation reaction catalyst and a hydrosilylation reaction wherein hydrosilylation is an alkenyl group bonded to a silicon atom of one polyorganosiloxane and hydrogen bonded to a silicon atom of another polyorganosiloxane. ) May further contain additive (s), such as inhibitors of the catalyst. 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.                     

There are two general types of Si-PSA depending on the type of curing reaction:

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 radical reaction between the carbon of the methyl group present in the polyorganosiloxane and the organic peroxide.

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 7355 Adhesive and Dow Corning 7657 Adhesive, respectively.

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, reduced 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 end-blocked by a trimethylsiloxy unit having a viscosity of 20 cp at 25 ° C.

-Tin hardener

Dibutyltin 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 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 Primer Composition>

The primer composition was coated onto a 50 μm thick PET film substrate (commercially available from Nan Ya Plastic Co.) using the Meyer Rod No. 8 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 PET film and then cured by heating at 70 ° C. for 2 minutes and at 178 ° C. for 2 minutes to have a 1.5 mil thick adhesive layer 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”, 2.0 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 and 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 120 seconds
120 ℃ X 60 seconds
120 ℃ X 30 seconds 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
Remark
Hardener Hardening
accelerant H siloxane ^* and 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 ^* and inhibitor

A mixture of 97.5% polymethylhydrogensiloxane and 2.5% methyl butynol having a viscosity at 25 ° C. of 10 cSt and terminally blocked by trimethylsiloxy units.

-Platinum hardener liquid

A platinum-divinyltetramethyldisiloxane complex containing 1.5% platinum complex, diluted with dimethylvinyl terminated 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
Remark
Hardener Hardening
accelerant 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 Primer 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 and 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

Silicone 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 and 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 and N and then curing at 120 ° C. for 2 minutes. Si-PSA that can be cured by the peroxide used contains 100 parts by weight of the "Dow Corning 7355 adhesive", 2.0 parts by weight of benzoyl peroxide and 50 parts by weight of toluene as in Example 1. Si-PSA, which can be cured by the platinum used, contains 100 parts by weight of the "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 adhesive and the film, thereby making it possible to precisely mask when used for masking by making the cutting performance of the silicone tape excellent, and the other primer composition has excellent adhesion with the silicone. Therefore, it provides the 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 silicone pressure-sensitive adhesive, 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 polyorganosiloxane resin having less than 0.7% by weight of silicon-bonded hydroxy groups, (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 at 25 ° C. of 10 cSt or more, and (d) catalytic amount of curing agent Characterized in that it contains a primer composition. The primer composition of claim 1, wherein the primer composition is used between the silicone adhesive and the substrate. The primer composition of claim 1, wherein the polydiorganosiloxane (a) having a hydroxy group at the terminal is a compound of formula (1). Formula 1 HOR ₂ SiO (R ₂ SiO) _m1 SiR ₂ OH In the above formula (1) R independently represents a monovalent hydrocarbon group or a halogenated hydrocarbon group, m1 is an integer such that the viscosity of the polydiorganosiloxane (a) at 25 ° C is 1,000 cSt or more. The polyorganosiloxane resin (b) having a silicon-bonded hydroxy group of less than 0.7% by weight is reacted with a terminal blocker of disiloxane, silazane or chlorosilane to react with the A primer composition, characterized in that it is prepared by reducing the content to less than 0.7% by weight. Formula 2 _{R 'n SiO (4-n} ) / 2 In Formula 2 above, R 'represents a monovalent hydrocarbon group, n is 0.6 to 1.7.