JPH0364389A - Uv-curable silicone adhesive composition - Google Patents

Abstract

PURPOSE:To provide the title adhesive compsn. with excellent adhesive properties, workability, heat resistance, etc., by mixing a specified wt. ratio of two specified polyorganosiloxanes, a silicon compd. with a hydrolyzable group or a trialkenyl isocyanurate and a photoreaction initiator. CONSTITUTION:100 pts.wt. polyorganosiloxane with a viscosity at 25 deg.C of 50-100,000cPs and an aliph. unsatd. group, a polyorganosiloxane with a viscosity at 25 deg.C of 10-100,000cPs and a mercaptoalkyl group in an amt. in such a ratio that the mercaptoalkyl group is 0.2-5mol based on 1mol of the aliph. unsatd. group of the component A, 0.1-20 pts.wt. silicon compd. with a hydrolyzable group (e.g. gamma-aminopropyltriethy=oxysilane) or a trialkenyl isocyanurate (or its deriv.) and 0.1-50 pts.wt. photoreaction initiator (e.g. benzophenone) are mixed to prepare a UV curable silicone adhesive compsn.

Description

Detailed Description of the Invention [Object of the Invention] (Industrial Application Field) The present invention relates to an ultraviolet curable silicone adhesive composition, and more specifically, it has adhesive properties and excellent properties of silicone rubber, and furthermore, , relates to an ultraviolet curable silicone adhesive composition that cures and adheres in a short time by irradiation with ultraviolet rays, contributing to improved productivity.

(Prior Art) Conventionally, photocurable organic adhesives have been used as ultraviolet curable adhesives. However, while this organic adhesive has advantages such as easy curing and good transparency, it also has disadvantages such as insufficient moisture resistance and heat resistance, and large shrinkage during curing. However, there was a problem of poor adhesion reliability under high temperature and multi-source conditions.

In order to solve these problems, the use of silicone-based adhesives is considered.1 The room-temperature-curing liquid silicone rubber adhesives that are normally used are cured by a condensation reaction, so when used for bonding large areas. There are problems such as a long time required for curing, which limits the range of application. Therefore, a heat-curable liquid silicone rubber adhesive was developed that utilized an addition reaction for curing, but in order to cure and bond, it was necessary to
Since it requires a heating process of several minutes to over an hour at a temperature of 0 to 150°C, its application to heat-sensitive plastic substrates, heat-sensitive electronic component materials, etc. has been limited.

Furthermore, the application of the heat-curing type may be limited due to the usage environment. For these reasons, the development of a photocurable silicone rubber adhesive has been awaited.

Such photocurable silicone compositions have already been described in several documents6. For example, in U.S. Pat. It is described that the compound is cured by adding an agent and irradiating it with high-intensity ultraviolet rays.

However, the compositions described therein are for producing silicone release papers and, although suitable for curing thin films, are not suitable for use as adhesives.
That is, the reason for this is that the above-mentioned composition does not have adhesive properties, and its curability is significantly reduced or it does not cure when exposed to light transmitted through glass.

Further, U.S. Pat. It had no adhesive properties and could not be used as an adhesive.

Furthermore, Japanese Patent Publication No. 52-40334 discloses a composition comprising a vinyl group-containing polyorganosiloxane, a polyorganohydrodiene siloxane, and a photosensitizer.
Publication No. 5-125123 describes a composition consisting of a vinyl group-containing polyorganosiloxane and an organic peroxide, but these all lack adhesive strength to the substrate and require extremely high ultraviolet energy for curing. There was a problem.

Further, Japanese Patent Application No. 100750/1983 proposes a composition comprising a polyorganosiloxane containing a vinyl group, an aromatic ketone photoreaction initiator, and trialkenyl isocyanurate or a derivative thereof. . Although this composition exhibited good adhesion and excellent properties such as heat resistance and moisture resistance, curing was still insufficient.

(Problems to be Solved by the Invention) The present invention was made in response to the above-mentioned conventional circumstances, and is a highly sensitive ultraviolet-curing silicone adhesive that cures and bonds with short-term ultraviolet irradiation. On the other hand, it is an object of the present invention to provide an ultraviolet curable silicone adhesive composition that has high adhesive strength, low shrinkage rate, and excellent moisture resistance and heat resistance.

[Structure of the Invention] (Means for Solving the Problems) In order to achieve the above object, the present inventors have discovered a polyorganosiloxane containing an aliphatic unsaturated group and a mercaptoalkyl group. After applying a composition consisting of a polyorganosiloxane, a silicon compound having a hydrolyzable group or a trialkenyl isocyanurate and its derivative, and a photoreaction initiator to a substrate, the composition can be quickly activated by irradiating it with ultraviolet rays. Cures and has high adhesive strength.
In addition, the inventors have discovered that the adhesive exhibits low shrinkage and excellent moisture resistance and heat resistance, leading to the completion of the present invention.

That is, the present invention is an ultraviolet curable silicone adhesive composition comprising the following components and blending ratios.

(A viscosity at 125℃ is 50 to 100.000 cP
g, 100 parts by weight of polyorganosiloxane having an aliphatic unsaturated group, (B) viscosity at 25° C. 1O to 100.000 cP
s, and is a polyorganosiloxane having a mercaptoalkyl group, the amount of the mercaptoalkyl group in a ratio of 02 to 5.0 mol per mol of the aliphatic unsaturated group of the polyorganosiloxane of component (A) ( C) Silicon compound or trialkenyl isocyanurate or derivative thereof having a hydrolyzable group 0.1~
20 parts by weight, and (D) photoreaction initiator 0.1 to 50 parts by weight.

The polyorganosiloxane as component (A) used in the present invention has a viscosity of 50 to 100.000 cP at 25°C.
If the viscosity is lower than 50 cPs, the curing time will be long and it is not practical.
If it is larger than 0 cPs, sufficient fluidity as an adhesive cannot be obtained.

Examples of the aliphatic unsaturated group of component (A) include alkenyl groups such as vinyl, propenyl, butenyl, and hexenyl;
Cycloalkenyl groups such as cyclohexynyl and cyclooctenyl; alkynyl groups such as ethynyl, propynyl, butynyl, and hexynyl; cycloalkynyl groups such as dichlorohexynyl and cyclooctenyl;
From the viewpoint of reactivity, an alkenyl group with an unsaturated terminal is preferable.Also, from the viewpoint of ease of synthesis and availability of raw materials, a vinyl group is preferable.The aliphatic unsaturated group of component (A) is It is preferred that the average number of groups per molecule of polyorganosiloxane is - from the viewpoint of crosslinking efficiency and physical properties.The remaining groups include alkyl groups such as methyl, ethyl, and propyl; cycloalkyl groups such as dichlorohexyl; phenyl, tolyl, Aryl group such as xylyl: 2-phenylethyl,
Examples include aralkyl groups such as 2-phenylpropyl and substituted hydrocarbon groups such as chloromethyl, chlorophenyl, and 3.3.3-)-lifluoropropyl groups.3 From the viewpoint of ease of synthesis and heat resistance, etc. , methyl group or phenyl group are preferred.

The structure of the main chain of component (A) may be linear, cyclic, or branched, and these polyorganosiloxanes may be used alone or in a mixture of two or more. It may contain an alkoxy group such as methoxy or ethoxy.

Component (B) used in the present invention is a polyorganosiloxane having a mercaptoalkyl group, and is a fluid liquid having a viscosity of 10 to 100.000 cPs at 25°C. If the viscosity is less than 10 cPs, the crosslinking efficiency deteriorates, causing a practical problem. Moreover, if it is larger than 100.0OOcPs, sufficient fluidity for use as an adhesive cannot be obtained. Examples of the mercaptoalkyl group include mercaptomethyl, mercaptoethyl, mercaptopropyl, and mercaptobutyl groups. However, the remaining organic groups other than the mercaptoalkyl group, which is preferably a mercaptopropyl group from the viewpoint of ease of raw material availability and ease of synthesis, are as described above regarding the remaining groups of component (A).

The structure of the main chain of component (B) may be linear, cyclic, or branched, and these polyorganosiloxanes may be used alone or as a mixture of 2f1 or more. It is preferable that the mercaptoalkyl group, which may have an alkoxy group such as (A Since it crosslinks with the unsaturated groups of component (A) by irradiation with ultraviolet rays, its amount needs to be 0.2 to 5.0 moles per 1 mole of unsaturated groups of component (A). .

If it is less than 0.2 mol, crosslinking will be insufficient and 5.0 mol
When the amount is more than mol, heat resistance deteriorates. The preferred range is 0
．． It is 2 to 2.0 moles.

Component (C) of the present invention imparts adhesive properties to the composition of the present invention and is a silicon compound having a hydrolyzable group, trialkenyl isocyanurate, or a derivative thereof. Examples of hydrolyzable groups of silicon compounds having a hydrolyzable group include alkoxy groups such as methoxy, ethoxy, and propoxy; alkenyloxy groups such as 2-propenyloxy; aryloxy groups such as cophenoxy; acyloxy groups such as acetoxy; In addition, dialkylketoximes such as methylethylketoxime, dialkylamino groups such as didiethylamino, acylamino groups such as niacetylamino, dialkylaminooxy groups such as didiethylaminooxy, and those substituted with halogens or cyano groups, and halogens. Examples include atoms and hydroxy groups.

These groups may be partially hydrolyzed,
The remaining organic groups are alkyl groups such as methyl, ethyl, and propyl; cycloalkyl groups such as dichlorohexyl and cyclooctyl; alkenyl groups such as vinyl, allyl, butenyl, and hexenyl; cycloalkenyl groups such as dichlorohexenyl and cyclooctenyl; -aminopropyl, 3
-chloropropyl, 3.3.31-lifluoropropyl, cyanoethyl, glycidoxypropyl, acryloxypropyl, meccryloxypropyl, mercaptomethyl, mercaptopropyl, chloromethyl, N-(2-aminoethyl)amino Examples include substituted alkyl groups such as propyl; aryl groups such as phenyl, tolyl, xylyl, and chlorophenyl; aralkyl groups such as 2-phenylethyl and 2-phenylpropyl; and hydrogen atoms. Further, hexamethyldisilazane, tetramethyldisilazane, and the like are also included in silicon compounds having a hydrolyzable group.

As mentioned above, the hydrolyzable group is preferably an alkoxy group or a hydroxy group in terms of stability and adhesiveness, and the remaining groups are γ-aminopropyl group or γ-mercaptopropyl group in terms of reliability of adhesiveness. A group, a γ-methacryloxypropyl group, and a vinyl group are preferable.

Preferred silicon compounds having hydrolyzable groups include:
γ-aminopropyltriethoxysilane, γ-aminopropyltrimethoxysilane, γ-mercaptopropyltrimethoxysilane, γ-mercaptopropyltriethoxysilane, γ-methacryloxypropyltrimethoxysilane, γ-methacryloxypropyltriethoxysilane, Examples include vinyltrimethoxysilane and vinyltriethoxysilane. A mixture of two or more of these may be used, and it is even more effective to use these in combination with methyl orthosilicate or ethyl orthosilicate.

The trialkenyl isocyanurates as component (C) used in the present invention include triallyl isocyanurate, tributenyl isocyanurate, trivinyl isocyanurate, tricyclohexenyl isocyanurate, trimethoxysilylpropyl diallyl isocyanurate, bis(trimethoxy silylpropyl) allyl isocyanurate,
Examples include triethoxysilylprobyl diallylisocyanurate. Trimethoxysilylpropyl diallyl isocyanurate is triallyl isocyanurate 1
It can be easily obtained by reacting 1 mole of trimethoxysilane with 1 mole of trimethoxysilane in the presence of a platinum compound catalyst. Among these, triallylisocyanurate is particularly preferred because it is commercially the easiest to obtain and has excellent effects.

These trialkenyl isocyanurates may be used alone or in a mixture of two or more.

The blending amount of these is polyorganosiloxane (A) 100
The amount is 0.1 to 20 parts by weight. If it is less than 0.1 part by weight, the adhesive strength is insufficient, and if it exceeds 20 parts by weight, the curability or stability will deteriorate, which is not preferable.

The photoreaction initiator as component (D) acts as a radical initiator or sensitizer when photocrosslinking (A) and (B).

The photoreaction initiator of the present invention includes, for example, aromatic hydrocarbons, acetophenone and its derivatives, benzophenone and its derivatives, 0-benzoylbenzoic acid ester, benzoin and benzoin ether and its derivatives, xanthone and its derivatives, thioxanthone and its derivatives, Examples include disulfide compounds, quinone compounds, halogenated hydrocarbons and amines, organic peroxides, etc., and an appropriate one is selected from among them.

Among these photoinitiators, compatibility with silicone,
From the viewpoint of stability, photoreaction initiators or organic peroxides containing substituted or unsubstituted benzoyl groups are preferred.

The amount of the photoreaction initiator (D) is 0.1 to 50 parts by weight per 100 parts by weight of the polyorganosiloxane (Δ). If it is less than 0.1 part by weight, the photoreaction initiation effect will be insufficient, and if it exceeds 50 parts by weight, the heat resistance will deteriorate, the shrinkage rate will increase, and other problems will occur.

The composition of the present invention may contain a gelling inhibitor (dark reaction inhibitor), a heat resistance improver, a filler, and a colored dye and pigment, if necessary.

As the gelation inhibitor, a dark reaction inhibitor can be used, and examples thereof include hydroquinone, p-methoxyphenol, t-butylcatechol, and phenothiazine.

A preferred example of the heat resistance improver is a phenolic anti-aging agent.

In addition, the filler is used for the purpose of improving the mechanical strength and controlling the flow of the composition, and includes fumed silica, hot silica,
A filler such as fine quartz powder is used as necessary. Further, these may have surfaces treated with an organosilane compound or siloxane.

(Example) The present invention will be explained below using examples.

Example 1 Both ends are capped with dimethylvinylsilyl groups, consisting of 95 mol% dimethylsiloxy units and 5 mol% diphenylsiloxy units, and the viscosity at 25°C is 1.0 OO
cPs vinyl group-terminated polymethylphenylsiloxane 8
In Part 9, the average structural formula is [(CHs) asis 1st edition 5C
H2CH*CH25iOB←→fcHsl ts10]
a.

To Mercap 1 having a viscosity of 300 cPs at 25°C, 11 parts of propyl group-containing polymethylsiloxane and 0.01 part of p-methoxyphenol were added to 0.01 part of toluene.
5 parts of the solution was added and mixed uniformly to prepare a base composition. To 100 parts by weight of this base composition, 1 part of a silicon compound having a hydrolyzable group shown in Table 1 and triallyl isocyanurate were added and mixed uniformly to obtain Compositions 1 to 5. In addition, a composition 6 containing no silicon compound having a hydrolyzable group and no trialkenyl isocyanurate was prepared for comparison. In addition, the terminal is blocked with a trimethylsilyl group, and the methylvinylsiloxy unit is 10 mol%, and the remainder is dimethylsiloxy unit,
2 parts of 2-hydroxy-2-methyl-propiophenone and 0.5 parts of triallyl isocyanurate were added to 100 parts of polyorganosiloxane having a viscosity of 3.0OOcPs at 25°C, and mixed uniformly to prepare a comparative composition. I got a 7.

25mm x 80ms+x 5mm of the above compositions 1 to 6
Sandwich the two glass plates so that the overlapping part is 251 x 20 mm and the thickness of the adhesive is 200 P.
From a distance of locm with a 60w/cm high pressure mercury lamp,
A test piece was prepared by irradiating it with ultraviolet light for 5 seconds. The amount of ultraviolet rays at this time was measured with a 365 nai integrated light meter and was measured at 500 m.
J/cm'.

A shear adhesion test was conducted on this sample, and the results are shown in Table 1.

Table 1 also shows that adhesive test pieces made with compositions 1 to 5 were heated at -40°C.
A heat cycle test was conducted by repeating a cycle of cooling to 80°C for 20 minutes and then heating to 80°C for 20 minutes 100 times.

Table 2 shows the presence or absence of cracks, shear adhesive strength, and cohesive failure rate at this time. In addition, the same test piece was heated at 85°C.
Table 2 shows the results of a moisture resistance test after being left for 1,000 hours at 95% RH. Also, 150℃, 20℃
Table 2 also shows the results after standing at 0°C for 24 hours.

Composition 1 and Comparative Composition 7 in Table 1 are each 0.5g and 50mm
It was placed on a glass plate of X50nunX 1ma+, and then a glass plate of the same shape was placed on top of it, taking care not to introduce air bubbles, and the adhesive composition layer was pressurized and uniformed using a spacer so that the thickness was 0.1 mm. A single layer was formed. For this, a high pressure mercury lamp with an output of 4 kW is used to turn on 100+ on.
From the distance above, the cover glass was irradiated with light and the cumulative amount of light until curing was measured using a 365n+++ cumulative light meter. The results are shown in Table 3.

When the test piece of Composition 1 in Table 3 was mechanically peeled off, the cohesive failure rate was 100%. In addition, composition 1 was
According to K6850, using a glass plate with a specified size of 1 mm + thickness, it was cured under the same conditions of 90 mJ/cta'' as described above so that an adhesive composition layer with a thickness of 0.1 mm was formed, and sheared. When the adhesive strength was measured, it was 3,5
kgf/car", and the cohesive failure rate was 100%.

Example 2 Both ends are blocked with dimethylvinylsilyl groups, the remainder consists of dimethylsiloxy units, and the viscosity at 25°C is 3.
000 cPs polymethylvinylsiloxane and the average structural formula is [fcHs l s SiOH+r
-r+C,Hs (CHt =CH)S iO rod SiO
*l+* 40 parts of polymethylvinylsiloxane having a melting point of 100° C. was charged into a universal mixer and uniformly dispersed by heating and stirring. After cooling, 15 parts of dimethylsiloxane-treated fumed silica (specific surface area: 200/g) was charged, uniformly dispersed, and then heated and kneaded at 150° C. and a pressure of 10m+oHg or less for 4 hours. After cooling, a mercaptopropyl group-containing polyorganosiloxane having a viscosity of 400 cPs at 25° C. whose ends are capped with trimethylsilyl groups, 20 mol% of methyl (3-mercaptopropyl) siloxane units, and the remainder is dimethylsiloxy units is added to a fourth After adding the amount shown in the table and mixing uniformly, take 2.5 parts of 2-hydroxy-2-methyl-1-phenylpropan-1-one as a photoreaction initiator, and add 0.1 part of p-methoxyphenol as a polymerization inhibitor. and pt-butylpyrocatechol 0.05
part, the antioxidant tetrakis[methylene-3-(3',
0.2 parts of 5'-di-t-butyl-4'-hydroxyphenyl)propionate comethane and 2 parts of ultraviolet absorber
- Add 0905 parts of (2'-hydroxy-3',5'-di-t-butylphenyl)benzotriazole to make a uniformly dissolved solution, add the solution to the above polyorganosiloxane, and mix uniformly. did.

γ-methacryloxypropyltrimethoxysilane and methyl orthosilicate were added to these compositions in the mixing ratios shown in Table 4 to prepare adhesive compositions 8 to 20.

A shear adhesion test was conducted on the compositions 8 to 20 in the same manner as in Example 1. Further, the composition was thinly coated on an aluminum plate, and the cumulative exposure amount at 365 nm was measured using an integrated light meter, and the minimum curing exposure amount was measured, and the results are shown in Table 4. Then, compositions 19 and 20 were tested for adhesion to various adherends and glass, and the results are shown in Table 5.

Table 5 ○; Cohesive failure rate 100% Δ; 80% or more but less than 100% Less than 80% Example 3 Terminals are blocked with vinyldimethylsilyl groups, 5 mol% methylvinylsiloxy units, 3 diphenylsiloxy units
0 mol%, the remainder consists of dimethylsiloxy units, 25
100 parts by weight of a polyorganosiloxane having a viscosity of 1.500 cPs at °C and an average structural formula of [H5CH
tCH*(:HtSiOg)-(shasiog rod(◎+
tSiOh-((CHsl*SiO), 25°C
50 parts of polyorganosiloxane with a viscosity of 40.000 cPs, 1.5 parts of γ-methacryloxypropyltrimethoxysilane, 2-hydroxy-2-methyl-
0.01 part of p-methoxyphenol and 0.007 parts of p-t-butylcatechol in 3.75 parts of 1-(p-isopropylphenyl)propan-1-one and 1.0 part of toluene.
Composition 21 was prepared by adding the dissolved part. In addition, Composition 22 excluding γ-methaclnoroxypropyltrimethoxysilane was also prepared as a comparison.

Glass/glass shear adhesion tests were conducted on compositions 21 and 22 in the same manner as in Example 1, and the results are shown in Table 6.

As shown in Table 6, the composition 21 is:

It was found that the addition of γ-methacryloxypropyltrimethoxysilane significantly improved the adhesion to glass. In addition, the minimum curing exposure dose of Compositions 21 and 22 was tested, and both were 30 mJ/cm'', and γ-
The addition of methacryloxypropyltrimethoxysilane had no effect on curing.

Table 6: Composition 21 was applied to a glass plate, aluminum plate, brass plate, stainless steel plate, iron plate, copper plate, epoxy plate, polyester plate, ABS plate, and phenol plate to a thickness of 200F, and a metal halide of 80W/cm was applied. 1 with lamp
When UV irradiation was applied from a distance of 0 cm, the minimum curing exposure amount was measured with a 365 rus integrated light meter, and the result was 30
mJ/cm'' of UV irradiation, the surface became sticky (cured and strongly adhered).This test piece was subjected to a moisture resistance test at 80℃, 95% R), 000 hours of moisture resistance test, and 70℃. A heat cycle test was conducted for 30 minutes and 0°C for 30 minutes, but no change was observed in the adhered coating film.

[Effects of the Invention] The composition of the present invention is cured by short-term ultraviolet irradiation and exhibits adhesive properties, so it has excellent workability and can be used as an adhesive fixing material for glass and various substrates, and as an adhesive coating material for various substrates. It can be used as The composition also exhibits excellent heat resistance, moisture resistance, and reliability in heat cycle tests. Therefore, the present composition can be effectively used as an adhesive between glass and glass, glass and plastic, glass and metal or ceramic, transparent plastic and plastic, gold X and ceramic, etc.

It is also useful as a coating material for glass, ceramics, metals, etc.

Procedural amendment Heisei October 2nd year 2 days

Claims (1)

[Scope of Claims] An ultraviolet curable silicone adhesive composition comprising the following components and blending ratio. (A) Viscosity at 25°C is 50 to 100,000 cP
s, 100 parts by weight of polyorganosiloxane having an aliphatic unsaturated group, (B) a viscosity at 25°C of 10 to 100,000 cP
s, which is a polyorganosiloxane having a mercaptoalkyl group, with a ratio of 0.2 to 5.0 mol of mercaptoalkyl group per 1 mol of aliphatic unsaturated group of the polyorganosiloxane of component (A). Amount (C) Silicon compound having a hydrolyzable group or trialkenyl isocyanurate or its derivative 0.1-2
0 parts by weight, and (D) 0.1 to 50 parts by weight of photoreaction initiator.