JPH02218783A - Pressure-sensitive adhesive composition - Google Patents

Abstract

PURPOSE:To obtain the subject composition capable of reducing adhesive force by irradiation of ultraviolet light containing elastic polymer, (meth)acrylate crosslinkable by ultraviolet light and polyisocyanate, etc., as main components. CONSTITUTION:The aimed composition is composed of (A) 100 pts.wt. elastic polymer, (B) (meth)acrylate crosslinkable by ultraviolet light, (C) polyisocyanate and (D) 5-150 pts.wt. urethane group-containing (meth)acrylate crosslinkable by ultraviolet light expressed by formula I {A is polyester group-containing diol expressed by formula II [R<1> and R<2> are hydrocarbon, bifunctional aromatic group or bifunctional composed of the aromatics and oxyalkylene group added to the group; p is 1-10] or alkylene diol expressed by the formula -OR<1>O-; B is (meth)acrylate-containing group expressed by the formula III [R<3> is H or CH3; R<4> 1-5C hydrocarbon having (q+1) functionality (q is 1-5)]; U is urethane expressed by formula IV; n is 1-10; n1 and n2>=1} and having 700-2500 average molecular weight as main components.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to pressure sensitive adhesive compositions. For more details,
The present invention relates to a pressure-sensitive adhesive composition whose adhesive strength can be reduced by ultraviolet irradiation.

[Problems to be solved by conventional technology/invention] Generally,
2. Description of the Related Art Pressure-sensitive adhesive sheets or pressure-sensitive adhesive sheets, in which a pressure-sensitive adhesive is coated on a base sheet, are used for various purposes in general households and in various industrial fields. Accordingly, the properties required for pressure-sensitive adhesive sheets have become diverse, and various functions have come to be required in accordance with a wide variety of uses.

For example, when manufacturing integrated circuits, in order to obtain dice by cutting (dicing) a silicon wafer into predetermined dimensions, the silicon wafer is placed on a pressure-sensitive adhesive sheet called a dicing film.
After being fixed with pressure-sensitive adhesive and cut, it is peeled off from the dicing film and picked up.

Therefore, in order to accurately dice silicon wafers, the dicing film must have a strong adhesive force to the silicon wafer during dicing, while the adhesive force of the dicing film must be strong when picking up the dice from the dicing film. It is necessary that the For example, when dicing silicon wafers, the dicing film generally weighs 100 to 800 g.
/25 fins, while the dicing film has an adhesive force of several tens of g/25 m when picking up dice.
It is said that it is desirable to have an adhesive force of about m or less.

In addition, a technique has recently been adopted in which the adhesive sheet is stretched (expanded) before being picked up to widen the gap between cut silicon wafers, thereby making it easier to pick them up.

In this case, the ability of the sheet that is the base material of the adhesive to withstand stretching is also important.

Pressure-sensitive adhesive compositions with such properties are useful when it is necessary to reduce the adhesive force after application to the adherend surface, and when it is necessary to expand the adhesive sheet before pick-up. There is a need for pressure-sensitive adhesive sheets with such characteristics, and various studies have been made regarding these.

For example, JP-A-62-153378 discloses a method using urethane acrylate oligomers, but since urethane acrylate oligomers have a high molecular weight, long-term irradiation is required to reduce the adhesive strength by UV irradiation. Moreover, the adhesion strength is not significantly reduced and artificial peeling may be necessary. Furthermore, when the adhesive is peeled off from the adhered object, adhesive may remain on the adhered object (adhesive residue), and a cleaning operation or the like is required to remove it. In particular, if the adhesive layer does not have flexibility after curing, cracking may occur, and adhesive may easily remain on the adherend.

As described above, pressure-sensitive adhesive compositions with such properties are required when it is necessary to reduce the adhesive strength after application to the adhered surface, but there are no pressure-sensitive adhesive compositions with sufficient performance. The reality is that it is still unknown.

[Means for Solving the Problem] As a result of intensive research by the present inventors to create a pressure-sensitive adhesive that initially has strong adhesive force and can reduce the adhesive force as needed, Unexpectedly, when a pressure-sensitive adhesive composition consisting of a mixture containing an elastic polymer and an ultraviolet crosslinkable acrylic ester as main components is irradiated with ultraviolet light, its adhesive strength is significantly reduced. I found it. Furthermore, when a pressure-sensitive adhesive composition using polyisocyanate is used, the initial adhesive strength is strong, but when the composition is irradiated with ultraviolet rays, the adhesive strength is more significantly reduced or substantially eliminated; By using a urethane group-containing (meth)acrylic ester having a specific structure as the ultraviolet crosslinkable acrylic ester contained in the composition, the formed adhesive layer has flexibility and has excellent expandability. The present invention was completed based on these findings.

That is, the present invention comprises (ω elastic polymer (b) ultraviolet crosslinkable (meth)acrylic ester (c)
Polyisocyanate and +d+ General formula (1): (R11ij2 is a group selected from a saturated hydrocarbon group, an unsaturated hydrocarbon group, a divalent aromatic group, and a divalent group to which an oxyalkylene group is added) , and p is 1~
10) The polyester group-containing diol residue represented by 10RI or the alkylene diol residue represented by 0- (R1 is the same as above) or CH3, R4 has 1 to 5 carbon atoms and (
q + 1) valent hydrocarbon group, q is 1 to 5.9 R3s do not need to be the same), (same as (meth)acrylic acid), urethane group is 1 to 1O1 old and n2 are each 1 or more, - a number such that the average molecular weight of the compound represented by formula (1) is 700 to 2500)
Contains a urethane group-containing ultraviolet crosslinkable (meth)acrylic ester shown as the main component, and (the urethane group-containing ultraviolet crosslinkable (meth)acrylic ester as a minor component is (ω
The present invention relates to a pressure-sensitive adhesive composition whose adhesive strength can be reduced by irradiation with ultraviolet rays, characterized in that it is used in an amount of 1 to 150 parts per 100 parts (parts by weight, hereinafter the same) of an elastic polymer as a component.

The composition of the present invention exhibits strong adhesive strength when not irradiated with ultraviolet rays, and when irradiated with ultraviolet rays, the adhesive strength can be significantly reduced, and the composition exhibits excellent expandability. It is a pressure adhesive composition.

[Example] Conventionally, for example, "Adhesive Handbook (2nd edition)" (edited by Japan Adhesive Association, published by Nikkan Kogyo Shimbun, 1980) No. 3
Various pressure sensitive adhesive compositions are known, as described on pages 98-414.

A typical pressure-sensitive adhesive composition has an elastic polymer as its main component,
In addition, tackifiers and plasticizers with good compatibility, and
It is a composition in which fillers, anti-aging agents, colorants, etc. are added as necessary and mixed uniformly.

In the present invention, preferred examples of the elastic polymer of component (a) include saturated copolymerized polyester resins, homopolymers of (meth)acrylic esters, and copolymers of (meth)acrylic esters. However, it is not limited to these. These may be used alone, and 2F! The above may be used in combination.

Specific examples of the saturated copolymerized polyester resin include "Industrial Materials" Volume 25, No. 11, No. 1, No. 101-
Usually different 2FJ as described on page 10B
Examples include saturated copolymer resins with relatively low glass transition points that can be obtained by polycondensing the above-mentioned saturated dihydric carboxylic acids and saturated dihydric alcohols. Usually, aromatic dihydric carboxylic acids and aliphatic dihydric carboxylic acids are used together as the saturated dihydric carboxylic acids, and aliphatic or alicyclic dihydric alcohols, that is, glycols, are used as the saturated dihydric alcohols. It is not limited to. In particular, the saturated copolymerized polyester resin used in the present invention has a molar ratio of aromatic divalent carboxylic acid/aliphatic divalent carboxylic acid of 80.
/20-20/80, preferably 70/80-5
A saturated copolymerized polyester resin obtained by polycondensing a 0/50 saturated dicarboxylic acid mixture and glycol in equimolar amounts is preferably used.

The aromatic divalent carboxylic acids include, for example, terephthalic acid, the aliphatic divalent carboxylic acids include, for example, sebacic acid and adipic acid, and the glycols include, for example, ethylene glycol, 1,4-butanediol, propylene glycol, etc. are mentioned, and saturated copolymerized polyester resins obtained using these are preferably used. In addition, when manufacturing a saturated copolymerized polyester resin, a saturated polyhydric carboxylic acid having a valence of 3 or more or a saturated polyhydric alcohol having a valence of 3 or more may be used in combination as a carboxylic acid component, if necessary.

The above (meth)acrylic acid ester homopolymer or (
As a specific example of the meth)acrylic acid ester copolymer, adhesives conventionally known as (meth)acrylic acid ester adhesives can be used without particular limitation. The polymer used as the elastic polymer in the above-mentioned (meth)acrylic acid ester pressure-sensitive adhesive can usually be a homopolymer or a copolymer, but a copolymer of (meth)acrylic acid ester is used. There are a lot of people. This copolymer usually uses an acrylic alkyl ester as a raw monomer, such as ethyl acrylate, butyl acrylate, or 2-ethylhexyl acrylate, to form a polymer with a low glass transition temperature to provide adhesive properties. , comonomers that form hard polymers with high glass transition temperatures for cohesive properties, such as vinyl acetate, acrylonitrile, styrene, methyl acrylate, methyl methacrylate, etc., and for improved crosslinking and adhesion properties. Monomers having functional groups such as carboxylic acid groups, hydroxyl groups, amide groups, glycidyl groups, and hydroxylmethyl groups, such as acrylic acid, methacrylic acid, itaconic acid, hydroxylethyl methacrylate, hydroxylpropyl methacrylate, acrylamide, glycidyl methacrylate, etc. It is a copolymer obtained by copolymerizing.

Ultraviolet crosslinking property (b> component used in the present invention)
The meth)acrylic ester refers to an acrylic ester or methacrylic ester as an oligomer or monomer that is crosslinked by ultraviolet irradiation, and has at least two acryloyl or methacryloyl groups in the molecule. Specifically, such oligomers include, for example, oligoester acrylate, and monomers include, for example, 1,6-hexanediol diacrylate, trimethylolpropane triacrylate,
Esters of polyhydric alcohol and acrylic acid such as tetramethylolmethanetetraacrylate, dipentaerythritol hexaacrylate, or 1,6-hexanediol diacrylate, trimethylolpropane trimethacrylate, tetramethylolmethanetetramethacrylate, dipentaerythritol pentamethacrylate Examples include esters of polyhydric alcohols such as methacrylic acid and methacrylic acid.

The amount of the ultraviolet crosslinkable (meth)acrylic acid ester that is the +b> component is generally preferably about 15 to 200 parts, and about 50 to 200 parts per 100 parts of the ω component elastic polymer.
About 150 parts is more preferable. (b) Even if an adhesive composition containing less than 15 parts of component is irradiated with ultraviolet rays, its adhesive strength will not substantially change; Although it can be reduced, it is not preferable because adhesive may remain on the dice when picking up the dice after dicing a silicone wafer, for example.

The polyinsocyanate used in the present invention as component <C) is not particularly limited and may be used as long as it is a polyisocyanate, but diisocyanates and triisocyanates are industrially easily available and are used.

Specific examples of the diisocyanate include 2.
4-) Luene diisocyanate, -monophenylene diisocyanate, -xylylene diisocyanate, 4,4°
-diphenyl diisocyanate, 4,4°-diphenylmethane diisocyanate, (1), 5-naphthalene diisocyanate, isophorone diisocyanate, hexamethylene diisocyanate and the like.

Various triisocyanates are commercially available; for example, trimethylolpropane toluene isocyanate, which is commercially available as "Sumidur L" from Sumitomo Chemical Co., Ltd., is a preferred specific example of the triisocyanate used in the present invention. It can be given as follows.

Furthermore, a terminal isocyanate compound obtained by reacting a diisocyanate and a polyol in the presence of an excess amount of diisocyanate, such as a urethane oligomer obtained as an intermediate for the compound represented by general formula (1), can also be used as the polyisocyanate. .

The amount of polyisocyanate used as component (c) is <081 to 20 parts per 100 parts of the elastic polymer as a minor component.
part is preferred, and 1 to 15 parts is more preferred.

In the present invention, (general formula (1) as a small component: % formula %) (RI R2 is a saturated hydrocarbon group, an unsaturated hydrocarbon group, a divalent aromatic group, and an oxyalkylene group added thereto) a group selected from divalent groups, or p is 1
A polyester group-containing diol residue represented by ~10) or an alkylene diol residue represented by 10RI0- (R1 is the same as above), or CH3, R4 is a hydrocarbon group having 1 to 5 carbon atoms and a valence of <q+1) , q is 1 to 5, if Q is 2 or more, the nine R3s do not need to be the same); U is a urethane group;
■ is 1 to l, old and n2 are each 1 or more,
The average molecular weight of the compound represented by general formula (1) is 700
A urethane group-containing ultraviolet crosslinkable (meth)acrylic acid ester having a number of 2,500 to 2,500 is used.

The moe component is the flexibility of the adhesive layer after UV curing.
It is a component used to improve the extendability, and the part A in general formula (1) mainly improves the compatibility with other components and the physical properties of the cured product, and the part B mainly has UV curability. , U mainly serve to improve the flexibility and expandability of the resin.

^ in the general formula (1) is a thyl group-containing diol residue or an alkylene diol residue represented by 10R10-, and RI in the residue is
R2 is a saturated hydrocarbon group, an unsaturated hydrocarbon group,
Divalent aromatic groups and oxyalkylene groups containing one
It is a group selected from divalent groups to which p is 1 to IO, and the molecule ffi of formula (1) is within the range of 700 to 2500. Yes, it is possible, and in fact, the larger the molecular weight, the better the flexibility and expandability, but if it is too large, the ultraviolet curing speed will be slow, which will cause the adhesive strength to not decrease after ultraviolet irradiation.

Further, B in the general formula (1) is a acrylate ester group, R3 in this group is It or CH3, R4 is a (q+1)-valent hydrocarbon group having 1 to 5 carbon atoms, and q is 1 to 5, curing is fast during ultraviolet curing and there is less adhesive residue.

Furthermore, the U container in general formula (1) contributes to improving the flexibility and expandability of the adhesive layer after being cured by ultraviolet rays.

The amount in general formula (1) is preferably as large as possible from the viewpoint of improving flexibility and expandability, but if it is too large, the ultraviolet curing speed will be slow and the adhesive strength will be difficult to reduce. ~10, preferably 1
~2, and old and n2 are both 1 or more and old + n
2≧2, preferably 4≧old+02≧1, when the average molecular weight of the urethane group-containing (meth)acrylic ester represented by the general formula (1) is 700 to 2500°, preferably 1000 to 2500. It is also preferable that it be used. Note that the average molecular weight of the urethane group-containing (meth)acrylic ester represented by general formula (1) is 7.
If it is smaller than 00, there will be a lot of glue left, and the value will be 2500.
If it is larger than , the adhesive force after irradiation with ultraviolet rays will not decrease, which is not preferable.

The compound represented by the general formula (1) is a terminal isocyanated urethane oligomer synthesized by the reaction of a diol component and an incyanate component, and a terminal (meth) obtained by reacting a (meth)acryloyloxy group with a hydroxyl compound. ) It is an acrylic acid esterified urethane compound.

The diol component used in the synthesis of the compound represented by the general formula (1) may be an alkylene diol as described above, a polyester-containing diol, a polyoxyalkylene group-containing diol, or the like. For example 1.4
- Aliphatic diols such as butanediol, 6-hexanediol, polyoxyalkylene glycols such as polyethylene glycol, polypropylene glycol, and polytetraethylene glycol, alkylene oxide adducts of aliphatic diols, bisphenol A alkylene oxide adducts, etc. A double-terminated hydroxy polyester compound obtained by esterifying the above-mentioned hydroxy compound with a dicarboxylic acid compound such as succinic acid, fumaric acid, adipic acid, or phthalic acid. etc. can be given.

In addition, diisocyanates and triisocyanates are suitable as the isocyanate component, and examples of the diisocyanates include 2.4-)luene diisocyanate, 1-phenyl diisocyanate, ■-xylylene diisocyanate, and 4°4°-diphenyl diisocyanate. , 4,4°-diphenylmethane diisocyanate, 1
．． Examples include 5-naphthalene diisocyanate, isophorone diisocyanate, dianisidine diisocyanate, and hexamethylene diisocyanate.

Further, examples of the triisocyanate include triphenylmethane triisocyanate and trimethylolpropane tolylene triisocyanate adduct (for example, Coronate manufactured by Nippon Polyurethane Industries, Ltd.).

Specific examples of (meth)acryloyloxy-containing hydroxyl compounds include hydroxyethyl acrylate, hydroxypropyl acrylate, trimethylolpropane diacrylate, glycerin diacrylate, pentaerythritol triacrylate, and these acrylates. Examples include methacrylates that have become methacrylate.

Urethane group-containing ultraviolet crosslinking property (
Specific examples of meth)acrylic acid esters include, for example, 4 moles of ethylene oxide adduct (1
reaction product of bisphenol A with 4 moles of ethylene oxide (2 moles) and inphorone diisocyanate (3 moles) and hydroxyethyl acrylate (2 moles). Reactant; L, 6
-hexanediol (5 mol) and adipic acid (4 mol)
A reaction product of polyester diol (1 mol), 2.4-)luene diisocyanate (2 mol), glycerin diacrylate (1 mol), and hydroxypropyl acrylate (1 mol) produced by esterification with diethylene glycol (6 mol) Reaction product of polyester diol (1 mol) produced by esterification with succinic acid (5 mol), xylylene diisocyanate (2 mol), and hydroxypropyl acrylate (2 mol); ethylene oxide 4 mol adduct of bisphenol A (2 mol), xylylene diisocyanate (3 mol), hydroxyethyl acrylate (1 mol), and pentaerythritol triacrylate (1 mol).

(The urethane group-containing ultraviolet crosslinkable (meth)acrylic ester represented by the general formula (1), which is a minor component, is used in an amount of 5 to 150 parts per 100 parts of the elastic polymer, which is a minor component, for initial adhesion. The adhesive strength is strong, the adhesive force is greatly reduced by ultraviolet irradiation, there is little adhesive residue when picked up after ultraviolet irradiation, and the expandability is good, so the amount is preferably 10 to 130 parts.

The pressure-sensitive adhesive composition according to the present invention usually contains a photopolymerization initiator, and may further contain a photosensitizer or a polymerization inhibitor.

The photopolymerization initiator is used for crosslinking polymerization of the ultraviolet crosslinkable acrylic ester by ultraviolet irradiation.

Such photopolymerization initiators are generally well known in the technical field of ultraviolet crosslinking polymerization, and in the present invention, photopolymerization initiators that are generally well known can be used. Specific examples of such polymerization initiators include benzoin alkyl ethers such as benzoin methyl ether and benzoin isopropyl ether, and aromatic oxyketones and aromatic ketones such as benzoin, benzyl, and benzophenone.
It is not limited to these.

The polymerization inhibitor is used to inhibit the polymerization of the compound represented by general formula (1), which is a small component, and the ultraviolet crosslinkable (meth)acrylic acid ester, which is component (b), regardless of ultraviolet irradiation, for example, by heat. It is added to prevent such polymerization, and conventionally known ordinary polymerization inhibitors can be used as such polymerization inhibitors. Examples of such polymerization inhibitors include hydroquinone, hydroquinone monomethyl ether, etc. I can give it to you.

The blending amounts of the photopolymerization initiator and polymerization inhibitor may be in accordance with those generally used in the technical field of ultraviolet polymerization. For example, in the case of a polymerization initiator, It is preferably about 1 to 20 parts per part, and in the case of a polymerization inhibitor, 0.01 parts as necessary.
It is used in a range of 1 part to 1 part.

The pressure-sensitive adhesive composition of the present invention contains an elastic polymer, an ultraviolet crosslinkable (meth)acrylic acid ester, an ultraviolet crosslinkable acrylic acid ester containing a urethane group represented by the formula (1), and a polyisocyanate in the above-mentioned amounts. , along with a polymerization initiator, an acrylic ester tackifier, a polymerization inhibitor, a filler, an anti-aging agent, a coloring agent, etc. as necessary, and an appropriate organic solvent for dissolving these, such as aromatic hydrocarbons, By dissolving it in a ketone or a mixed solvent thereof, it can be made into a uniform solution composition. As a specific solvent, for example, a mixed solvent of toluene and methyl ethyl ketone is preferably used, but the solvent is not limited thereto.

In addition, the content of the elastic polymer in the pressure-sensitive adhesive composition may be appropriately selected depending on the application, but is usually 10 to 10%.
The range is 50% (weight %, the same applies hereinafter). However, it is not limited to this range.

Although there are no restrictions on the method for preparing the pressure-sensitive adhesive composition of the present invention, the elastic polymer and tackifier are usually commercially available in the form of a solution, and it is convenient to use them. , for example, by mixing these solutions, adding an ultraviolet crosslinkable (meth)acrylic ester, a urethane group-containing ultraviolet crosslinkable acrylic ester and polyisocyanate represented by the formula (1), and, if necessary, a polymerization initiator. , an acrylic acid ester heavy blocking agent, a filler, an anti-aging agent, a coloring agent, etc. may be added and mixed and dissolved.

Furthermore, the pressure-sensitive adhesive composition of the present invention may appropriately contain a plasticizer such as liquid polyacrylic ester, liquid polybutene, mineral oil, and lanolin, as necessary.

The pressure-sensitive adhesive composition of the present invention is used as a pressure-sensitive adhesive sheet, for example, by forming a layer of the pressure-sensitive adhesive composition on a base sheet that can transmit ultraviolet rays. therefore,
For example, the pressure-sensitive adhesive sheet is manufactured by applying a liquid pressure-sensitive adhesive composition as described above onto a base sheet and drying it.

The base sheet is not particularly limited as long as it is a sheet that can transmit ultraviolet rays, and various sheets can be used, but transparent to translucent synthetic resin sheets are usually used. Specific examples of such synthetic resin sheets include vinyl chloride resin, vinyl chloride-vinylidene chloride copolymer, vinyl chloride-vinyl acetate copolymer, vinylidene chloride resin, polyolefin, acetyl cellulose, polyvinyl alcohol, polyamide, polyester. ,
A resin sheet made of polycarbonate or the like and having a thickness of approximately 50 to 300 mm is preferably used.

Among the resin sheets used as the base sheet, polyvinyl chloride or vinyl chloride copolymers such as vinyl chloride-vinylidene chloride copolymer, vinyl chloride-vinyl acetate copolymer, vinyl chloride-acrylic acid ester copolymer, etc. A resin sheet consisting of is particularly preferred because it is flexible and inexpensive.

In addition to the vinyl chloride resin sheet, sheets made of polyvinylidene chloride, acetyl cellulose, etc., for example, can be suitably used as the flexible base sheet.

When a resin sheet containing a plasticizer is used as the base resin sheet of the pressure-sensitive adhesive sheet, the plasticizer may migrate from the resin sheet into the pressure-sensitive adhesive composition, and depending on the resin sheet, ultraviolet rays may Since it has good compatibility with the crosslinkable acrylic ester, the UV crosslinkable acrylic ester contained in the pressure-sensitive adhesive composition migrates into the resin sheet, and due to this mutual migration, the pressure-sensitive adhesive sheet The effect of reducing adhesive strength after UV irradiation is significantly reduced.

Therefore, in the present invention, as a base sheet of a pressure-sensitive adhesive sheet, a resin layer that does not transmit a plasticizer and an ultraviolet crosslinkable acrylic ester is formed between this base sheet and the pressure-sensitive adhesive sheet. It is preferable to interpose a barrier layer. However, this barrier layer must not impede the transmission of ultraviolet light.

In other words, this barrier layer does not impede the transmission of ultraviolet light in any way.
This difference prevents the plasticizer contained in the base resin sheet from migrating into the pressure-sensitive adhesive composition, and also prevents the UV-crosslinkable acrylic ester contained in the pressure-sensitive adhesive composition from migrating. This prevents the plasticizer contained in the base resin sheet from migrating to the base resin sheet, thus retaining the plasticizer contained in the base resin sheet in this base material and eliminating the UV crosslinking contained in the pressure sensitive adhesive composition. acrylic ester in the adhesive composition.

As the barrier layer, a film of poly-α-olefin such as polyethylene or polypropylene, or polyalkylene terephthalate such as polyethylene terephthalate, or a resin coating layer, such as a resin coating layer such as a modified polyacrylic resin, is suitably used. Therefore, the barrier layer can be formed by pressing a film made of the above-mentioned resin onto a base resin sheet, or by applying a melt of this resin and cooling it, or by applying a solution of the above-mentioned resin and drying it. can be formed. The barrier layer can also be formed by coating a modified polyacrylic resin solution and, if necessary, heating and drying it to form a coating film.

Various types of modified polyacrylic resins have been known in the past, but in the present invention, they generally have excellent solvent resistance, and therefore UV crosslinkable acrylic esters and plasticizers contained in the base resin sheet are used. Alkyd-modified polyacrylic resins and thermosetting polyacrylic resins that do not dissolve or swell are suitable. As the thermosetting polyacrylic resin, for example, acid type, hydroxyl type, epoxy type, amide type, etc. are preferably used.

However, in the present invention, as described above, the barrier layer does not substantially transmit the ultraviolet crosslinkable acrylic ester contained in the pressure-sensitive adhesive composition and the plasticizer contained in the base resin sheet. It is easily understood that the material is not limited and is selected depending on the specific ultraviolet crosslinkable acrylic ester and plasticizer used in the present invention.

Next, the composition of the present invention will be explained in more detail based on Examples, but the present invention is not limited to these Examples.

Synthesis Example 1 (Synthesis example of urethane acrylate A) 116 g (1 mol) of 2-hydroxyethyl acrylate and 0 of hydroquinone monomethyl ether as a polymerization inhibitor
．． 25 g was placed in a III-volume four-neck flask and stirred. The internal temperature was raised to 60° C., and 188 g (1 mol) of xylylene diisocyanate was added. Since it generated heat, it was cooled as necessary to keep the internal temperature below 80°C.

The fever subsided 2 hours after the addition, but
Stirring was continued for 1 hour at 0°C.

Next, glycerin diacrylate (hydroxyl value 28
01 saponification number 562, bromine number 1 Go) 200 g (1 mol) was added, and the mixture was stirred at 75 to 80°C. After 4 hours, 1 g of dibutyltin dilaurate was added, and after another 1 hour, 2 g of dibutyltin dilaurate was added.
11.8 g (0.1 mol) of hydroxyethyl acrylate was added. The reaction was continued until the amount of free isocyanate became 0.2% (weight %, the same applies hereinafter) or less, and the reaction was terminated.

When the reaction product was analyzed by gel chromatography, the molecular weight distribution width was relatively narrow, and the average molecular weight was 500.

Synthesis Example 2 (Synthesis Example of Urethane Acrylate B) 232 g (2 mol) of 2-hydroxyethyl acrylate and 0 of hydroquinone monomethyl ether as a polymerization inhibitor
．． 50 g was placed in a 1 g four-bottle flask and stirred. Heat the internal temperature to 60℃ and add xylylene diisocyanate 3.
76 g (2 mol) was added. The reaction was carried out under the same reaction conditions as in Synthesis Example 1. Three hours after the addition of xylylene diisocyanate, 405 g (1 mole) of bisphenol A ethylene oxide 4 mole adduct (hydroxyl value 277) was added and stirred at 75 to 80°C. Thereafter, the reaction was carried out in the same manner as in Synthesis Example 1, and the reaction was terminated when the amount of free isocyanate became 0.2% or less.

When the reaction product was analyzed by gel chromatography, it was found to have a relatively narrow molecular weight distribution width and an average molecular weight of 1010.

Synthesis Example 3 (Synthesis example of urethane acrylate C) Polyester diol having hydroxyl groups at both ends (hydroxyl number 93) synthesized by esterification of diethylene glycol and adipic acid BO3.5g (0
, 5 mol) was placed in a 1 g four-neck flask, heated to 60°C, and 188 g (1 mol) of xylylene diisocyanate was added. Since it generated heat, it was cooled as necessary to keep the internal temperature below 80°C. Although the exotherm subsided 2 hours after the addition, stirring was continued for an additional 2 hours at 75-80°C.

Next, 83.8 g of 2-hydroxyethyl acrylate
(0.55 mol), trimethylolpropane diacrylate (purity by gas chromatographic analysis is 60%,
The other is trimethylolpropane triacrylate, hydroxyl value 139) 202g.

0.53 g of hydroquinone monomethyl ether was added and stirred at 75-80°C. After 4 hours, dibutyltin dilaurate 1. The reaction was terminated after the amount of free isocyanate became 0.2% or less.

When the reaction product was analyzed by gel chromatography, the average molecular weight excluding trimethylolpropane triacrylate contained as an impurity was 1950.

Synthesis Example 4 (Synthesis Example of Urethane Acrylate D) Synthesis Example 3
Polyester diol used in (hydroxyl number 93)
482.7 g (0.4 mol) was placed in a 1 fl four-bottle flask, heated to 60°C, and stirred. 112.8 g (0.6 mol) of xylylene diisocyanate was added, and the internal temperature was maintained at 80° C. or lower by cooling as necessary. After stirring while maintaining the temperature at 75 to 80°C for 3 hours after addition, 2
-Hydroxyethyl acrylate 25.8g (0,
22 mol), trimethylolpropane diacrylate (
Gas chromatography analysis purity 60%, hydroxyl number 1
39) 110.8 g of hydroquinone monomethyl ether and 0.35 g of hydroquinone monomethyl ether were added, and the mixture was stirred while being maintained at 75 to 80°C.

After 4 hours, 1.0 g of dibutyltin dilaurate was added, and heating and stirring were continued until the amount of free incyanate was 0.
The reaction was terminated when the concentration became 2% or less.

Gel chromatography analysis of the reaction product revealed that the average molecular weight was 3,300.

Examples 1 to 4 and Comparative Examples 1 to 6 The urethane acrylates shown in Table 2 were added to the formulations shown in Table 1, and the urethane acrylates shown in Table 2 were added to the formulations shown in Table 1 to 100 parts of the elastomeric polymer shown in Table 1. A pressure-sensitive adhesive composition was prepared by blending the components in the numbers shown in Table 2. The resulting composition was applied onto a release paper and dried at 120° C. for 1 minute to form a layer of the pressure-sensitive adhesive composition with a solid content of 101 s.

Next, a modified acrylic resin was molded onto a 0.1 mm thick sheet formed from a vinyl chloride resin composition consisting of 100 parts of polyvinyl chloride with an average degree of polymerization of 1300, 35 parts of dioctyl phthalate as a plasticizer, and an appropriate amount of a stabilizer. The solution was applied and dried to form a barrier layer. After that, the pressure-sensitive adhesive layer formed on the release paper is laminated and bonded to the surface of the barrier layer of this base resin sheet,
I got a pressure-sensitive adhesive sheet.

After each pressure-sensitive adhesive sheet thus obtained was left at room temperature for 20 minutes, the release paper was peeled off and the adhesive strength was directly measured. Separately, the adhesive force was measured after irradiating ultraviolet rays at a dominant wavelength of 3651 μm and 120 W/am for 7 seconds from the vinyl chloride resin sheet side. In addition, the adhesive residue property and the extractability were evaluated by the following methods. The results are shown in Table 2.

(Adhesive strength) A pressure-sensitive adhesive sheet was cut into 25 mm width and 100 mm length to prepare a test piece, and this was used as an adherend on a stainless steel plate (S
After stacking on US-304) and pressing it back and forth 5 times with a 3 kg roller, it was pulled at a speed of 300 m using a shopper.
A 180° peel test was performed at m/min.

The higher the adhesive strength before UV irradiation, the better. However, if the adhesive layer suffered cohesive failure and did not function as an adhesive, a mark of ↓1 was given as a judgment.

After UV irradiation, if it is 100 g / 25 mm or less, it can be used, but if it is less than 50 g / 25 + em, it is 015.
0-100sr/25mm is Δ, 100g/2
If it exceeded 5+sm, it was judged as X.

(Adhesive Remaining Resistance) The wafer was cut using a dicing machine (manufactured by DISCO), and after UV irradiation, the wafer chips were picked up by a pick-up machine (manufactured by Chiden Kikai ■), and the back side of the resulting wafer chip was observed. The evaluation was rated as ○ if no adhesive remained on the surface, △ if a little adhesive remained, and × if a lot of adhesive remained on the entire back side.

(Expansion properties) A wafer is pasted on this pressure-sensitive adhesive sheet, cut with a dicing machine (manufactured by DISCO), then UV irradiated, and then applied to an extraction machine (manufactured by Chiden Kikai ■) for approximately 25% expansion. Then, chips were observed for disturbances, tape breaks, etc., and those with no chip disturbances, no tape breaks, and equally spaced chips were evaluated as 0, and those with no chips were evaluated as ×.

[Left below] Pressure-sensitive adhesive sheets produced using the pressure-sensitive adhesive composition of the present invention exhibit a particularly remarkable decrease in adhesive strength due to ultraviolet irradiation even after long-term storage. It has an adhesive force of several hundred g/25 mm, and after UV irradiation, the adhesive force can be reduced to about several tens of g/25 mm or virtually eliminated, so as mentioned above, it is suitable for dicing silicon wafers. It can be suitably used.

From the results in Table 2, the performance varies greatly depending on the type of urethane acrylate added. Urethane acrylate A has an average molecular weight of less than 700, and
It can be seen that with urethane acrylate D exceeding 0, the adhesive strength, adhesive residue, and expandability after irradiation with ultraviolet rays are significantly inferior.

Note that if the amount of urethane acrylate added is too large or too small, the adhesive strength will be poor, which is not preferable.

[Effects of the Invention] The pressure-sensitive adhesive composition of the present invention initially has strong adhesive strength, but when it is irradiated with ultraviolet rays, the adhesive strength is significantly reduced. Therefore, if a pressure-sensitive adhesive sheet is manufactured by coating this pressure-sensitive adhesive composition on a base sheet that can transmit ultraviolet rays, the adhesive strength will be significantly reduced by irradiation with ultraviolet rays, and the pressure-sensitive adhesive sheet will be coated with ultraviolet rays. It can be easily peeled off from the adhered surface, and there is no adhesive residue (adhesive layer remaining on the adhered surface).
This eliminates the need for cleaning operations after peeling off the adhered surface.

Therefore, the pressure-sensitive adhesive sheet as described above produced using the composition of the present invention can be suitably used, for example, as a film for dicing silicone wafers as described above.

Patent applicant Band-Kagaku Co., Ltd.

Claims (1)

[Claims] 1 (a) Elastic polymer (b) Ultraviolet crosslinkable (meth)acrylic ester (c)
Polyisocyanate and (d) General formula (1): ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (1) (In the formula, A is ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (R^1, R^2 are Both are groups selected from saturated hydrocarbon groups, unsaturated hydrocarbon groups, divalent aromatic groups, and divalent groups to which an oxyalkylene group is added, or p is 1
~10) A polyester group-containing diol residue or an alkylene diol residue represented by -OR^1O- (R^1 is the same as above), B has a ▲numeric formula, chemical formula, table, etc.▼(R^ 3 is H or CH_3, R^4 is a (q+1)-valent hydrocarbon group with 1 to 5 carbon atoms, q is 1 to 5, and the q R^3s do not have to be the same) (meth) ) acrylic acid ester-containing group,
U is a urethane group represented by ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (R^1 is the same as above), m is 1 to 10,
n_1 and n_2 are each 1 or more, and the general formula (
The average molecular weight of the compound represented by 1) is 700 to 250
urethane group-containing ultraviolet crosslinkability (number equal to 0)
The urethane group-containing ultraviolet crosslinkable (meth)acrylic ester which contains meth)acrylic acid ester as a main component and is component (d),
5 to 150 parts by weight per 100 parts by weight of the elastic polymer of component a)
A pressure-sensitive adhesive composition whose adhesive strength is reduced by ultraviolet irradiation, characterized in that part by weight is used. 2. Claim 1, wherein the elastic polymer as component (a) is a polymer selected from saturated copolymerized polyester resins, homopolymers of (meth)acrylic esters, and copolymers of (meth)acrylic esters. Compositions as described.