JP2626978B2 - Pressure sensitive adhesive composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to plates of metal, glass, wood, plastic, etc.
Used for temporary surface protection in order to prevent these adherends from being damaged or contaminated during transportation, processing, cutting, etc. of adherends having various surfaces such as columns and semiconductor wafers. The present invention relates to a pressure-sensitive adhesive composition for a pressure-sensitive adhesive tape or sheet.

Conventional surface protection adhesive formed by applying a photocurable adhesive to the substrate surface to prevent and protect the metal plate such as stainless steel, aluminum, etc., glass plate and other decorative plates from being scratched during transportation and processing. A method in which a film is pasted on a required surface of the protected object, and after the transportation and processing are completed, ultraviolet light is irradiated before peeling off the unnecessary surface protection adhesive film, and the adhesive is cured and then peeled off. (For example, JP-B-58-50164 and JP-A-62-59684), these photocurable pressure-sensitive adhesives are unsaturated bonds having photoreactivity with a sensitizer and a main component polymer of the pressure-sensitive adhesive. Has been achieved by providing two or more of these compounds per molecule, or by mixing a low-molecular compound such as a photosensitive monomer in a normal pressure-sensitive adhesive. However, since these base polymers are room-temperature tacky, they can reduce tackiness by light irradiation, but cannot completely eliminate the tackiness. As described in JP-A-62-10180, a pressure-sensitive adhesive formed on a pressure-sensitive adhesive tape or the like by a composition is contained in an acrylic copolymer. In addition to those remaining on the body surface, there are drawbacks such as the fact that the polyfunctional liquid resin is added and the anchorage of the adhesive to the plastic film substrate formed on the adhesive tape or the like is extremely poor.

The present invention has been made as a result of intensive studies in view of the above-mentioned drawbacks. The present invention relates to (A) (a) a C1-C12 alkyl (meth) acrylate 75-99% by weight (b) A copolymer having a glass transition temperature in the range of -40 to 30 ° C., comprising 1 to 15% by weight of a copolymerizable unsaturated monomer (c) and other vinyl compounds of 0 to 24% by weight. (B) 100 parts by weight of a copolymer having a radical polymerizable double bond in a side chain obtained by reacting all or a part of the component with a functional copolymerizable unsaturated monomer reactive with the component (b); B) One to 100 parts by weight of a viscous or liquid resin at room temperature having one or more radically polymerizable double bonds in one molecule cured by ultraviolet irradiation and further having a carboxyl group as a functional group (C) Pressure-sensitive adhesive composition containing 0.5 to 15 parts by weight of photosensitizer When a pressure-sensitive adhesive composed of this pressure-sensitive adhesive composition is applied to, for example, a transparent plastic film, the anchoring property is extremely good, and the pressure-sensitive adhesive is formed by applying the pressure-sensitive adhesive to a plastic film. When the composite (adhesive film) is adhered to the adherend, it adheres well, and after irradiating it with ultraviolet light, the adhered adhesive film is peeled off, leaving the pressure-sensitive adhesive on the surface of the adherend. It can be easily peeled off without doing. The copolymer is desirably slightly tacky or tack-free at room temperature, and has a glass transition temperature (Tg) of -40 to -40.
30 ° C. If the Tg is lower than this, it becomes difficult to eliminate the tackiness even if the copolymer is crosslinked by irradiating an ultraviolet ray by introducing an unsaturated bond into the side chain of the copolymer. Even if the resin (B) is added, tackiness cannot be exhibited.

Among the components (a), (b) and (c) constituting the copolymer (A), (a) alkyl (meth) acrylate having 1 to 12 carbon atoms includes methyl (meth) acrylate, ethyl ( (Meth) acrylate, n-propyl (meth) acrylate, isopropyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, t-butyl (meth) acrylate,
Examples include n-pentyl (meth) acrylate, n-hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, isooctyl (meth) acrylate, isononyl (meth) acrylate, and the like.

(B) In the case of a copolymer having a low Tg, the functional copolymerizable unsaturated monomer introduces an unsaturated group into a side chain, three-dimensionally cures upon irradiation with ultraviolet light, and becomes non-adhesive. (Meth) acrylic acid, glycidyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, acrylamide, N-methylolacrylamide, maleic acid, maleic anhydride, itaconic acid, itaconic anhydride, crotonic acid and the like. When these monomers are present in a large amount in the copolymer, the formed pressure-sensitive adhesive layer is easily transferred to the adherend. Therefore, after introducing an unsaturated group into the side chain, the unsaturated monomer (b ) Must be added so that no more than about 3% by weight remains. (B) in the copolymer
When the proportion of (b) is increased, gelation occurs at the time of the side chain desaturation reaction, so that the component (b) is preferably about 1 to 15% by weight. The functional monomer used for the above-mentioned side chain desaturation may be any monomer having reactivity with the component (b), such as (meth) acrylic acid, glycidyl (meth) acrylate, Hydroxyethyl (meth)
Acrylate, acrylamide, N-methylolacrylamide, maleic acid, maleic anhydride, itaconic acid,
In addition to itaconic anhydride and crotonic acid, 2- (1-aziridinyl) ethyl (meth) acrylate, 2- [1-
(2methylaziridinyl)] ethyl (meth) acrylate, 2- [1- (2.2-dimethylaziridinyl)] ethyl (meth) acrylate, 1- (1-aziridinyl) methyl (meth) acrylate, 3- ( 1-aziridinyl)
Propyl (meth) acrylate, isocyanatoethyl (meth) acrylate, isocyanatomethyl (meth)
Acrylate, isocyanate propyl (meth) acrylate and the like can be mentioned.

The above (c) other vinyl compounds are mainly used for adjusting the Tg of the copolymer, and include vinyl acetate, vinyl propionate, styrene, acrylonitrile and the like. The above-mentioned Tg (glass transition temperature) can be measured by a viscoelasticity measuring device, a thermal analyzer, or the like.
The equation of er Tg = W ₁ Tg ₁ + W ₂ Tg ₂ +... = ΣWiTgi (TgiWi is the Tg of the ith component
(K) and weight fraction).

The mixing ratio of each component (a), (b) and (c) constituting the copolymer (A) is (a) by weight%:
(B): (c) = 75 to 99: 1 to 15: 0 to 24 in many cases.

In the production of this copolymer, the components (a), (b) and (c) are appropriately selected, and the required amounts of a polymerization initiator, a solvent and the like are added to the respective required amounts, followed by a conventional method. The copolymerization reaction is continued, and after the completion of the reaction, the required amount of the appropriate functional monomer used for desaturation of the side chain and a necessary catalyst are added, and the mixture is treated by a conventional method to polymerize the side chain. Thus, a copolymer (A) having an unsaturated bond is formed.

As the solvent used in the above copolymerization reaction, water, benzene, toluene, xylene, ethyl acetate, methyl acetate,
Examples include butyl acetate, acetone, methyl ethyl ketone, methyl isobutyl ketone, methanol, ethanol, n-propanol, isopropanol, sec-butanol, t-butanol, n-hexane, cyclohexane, and n-heptane. As the above polymerization initiator, potassium persulfate, persulfates such as ammonium persulfate, methyl ethyl ketone peroxide, cyclohexane peroxide,
Peroxides such as cumene hydroperoxide, t-butyl hydroperoxide, benzoyl peroxide, lauroyl peroxide, and acetyl peroxide; azo such as αα 'azobisisobutyronitrile and 44' azobis-4-cyanovaleric acid System initiators and the like.
If necessary, mercaptans such as n-butylmercaptan, laurylmercaptanthioglycolic acid, nemercaptoethanol, and carbon tetrachloride can be added as a molecular weight regulator. When water is used as the solvent, various known surfactants can be used.

(B) The viscous or liquid resin at room temperature, which has one or more radically polymerizable double bonds in one molecule cured by ultraviolet irradiation and further has a carboxyl group as a functional group, can be used as the above-mentioned copolymer. The copolymer (A) is added to the polymer (A) to give the copolymer the required tack, adhesive strength, and the like. The component (B) includes 2-hydroxy1.3di (meth) acryloxypropane and an acid. Reaction products with anhydrides,
Reaction product of tetramethylolmethane tri (meth) acrylate and acid anhydride, 2-hydroxyethyl (meth)
Reaction product of acrylate and acid anhydride, reaction product of 2-hydroxyethyl (meth) acrylate and divalent carboxylic acid, reaction product of 2-hydroxypropyl (meth) acrylate and acid anhydride, 2 Reaction products of hydroxypropyl (meth) acrylate and divalent carboxylic acids, reaction products of glycidyl (meth) acrylate and divalent carboxylic acids, and the like.

Further, the photosensitizer (C) generates a radical by irradiation with ultraviolet light, and generates a (meth) acryloyl group of a side chain of the copolymer;
Or (B) component of viscous or liquid resin (meth)
It reacts an acroyl group to detackify a pressure-sensitive adhesive. Benzophenone, P, P'-dimethylaminobenzophenone, P, P'-methoxybenzophenone, benzoin methyl ether, benzoin ethyl Ether, benzoin propyl ether, diacetylbenzylacetylbenzoyl, P-chlorobenzophenone and the like.

The mixing ratio of each of the above components (A), (B) and (C) is as follows: (A) copolymer 100 having an acroyl group in the side chain.
(B) 1 to 100 parts by weight and (C)
0.5 to 15 parts by weight. If the above (B) does not reach 1 part by weight, it becomes difficult to develop a desired tack, and if it exceeds 100 parts by weight, it becomes difficult to develop a desired adhesive force. If the above (C) does not reach 0.5 parts by weight, curing by ultraviolet irradiation is not sufficiently performed, and it is difficult to detackify. If it exceeds 15 parts by weight, the effect of addition does not increase and not only costs increase, but also May be contaminated.

The above components (A), (B) and (C) are selected and blended according to the purpose of use and the like, uniformly mixed in the presence of a solvent or the like, and formed from plastic, paper, nonwoven fabric, cloth, etc. by a conventional method. A pressure-sensitive adhesive sheet or tape having a pressure-sensitive adhesive layer formed on the surface of a base material (support) to a required thickness by applying, drying, etc., and curing by ultraviolet irradiation to become non-tacky is obtained. Can be The obtained pressure-sensitive adhesive sheet or tape has the properties of a pressure-sensitive adhesive sheet or tape in a normal state, and can be adhered to the surface of an adherend such as a silicon wafer together with a substrate, for example. After the purpose of this adhesion is achieved, the double bond of the copolymer (A) and the double bond of the resin (B) undergo radical polymerization by irradiating the resin with ultraviolet light. And the functional carboxyl group of the resin (B) forms a hydrogen bond, and the chemical bond and the hydrogen bond form a tight network structure, whereby the adhesive force is greatly reduced. , The pressure-sensitive adhesive layer loses its function as a pressure-sensitive adhesive,
The pressure-sensitive adhesive layer can be easily removed from the surface of the adherend (without leaving an adhesive residue on the surface).

 Next, examples will be described.

Examples 1 to 4 The respective ingredients shown in the following Table 1 were charged into one flask, and the reaction was continued at 80 ° C. for 10 hours under a nitrogen stream to obtain (a)-(b)-.
(C) A copolymer was obtained. Next, replace the nitrogen stream with an air stream,
A required amount of glycidyl methacrylate (GMA) and triethylamine as a catalyst are added so that 1% by weight of acrylic acid in the copolymer remains, and the mixture is reacted at 80 ° C. for 10 hours to have a methacryloyl group in a side chain. Copolymer (A)
I got 50 parts by weight of an equimolar reaction product of glycidyl methacrylate and succinic acid (unsaturated compound containing a functional group) and 3% of benzophenone are added thereto, mixed uniformly, and the resulting solution is mixed with Lumirror # 25 (trade name of Toray KK) ) Was applied to a thickness of 25 μm after drying, and dried at 80 ° C. for 10 minutes to obtain a pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer. This adhesive sheet was affixed to a stainless steel panel, and the results obtained by measuring the adhesive force of the pressure-sensitive adhesive sheet before and after irradiation with ultraviolet light by a conventional method are also shown. The Tg and the state of gelation of the copolymer produced during the above process are also shown.

Comparative example 1 Except having used the compounding raw material of Table 1, it carried out similarly to Examples 1-4, and obtained the copolymer. Next, the nitrogen stream was replaced with an air stream, and a required amount of glycidyl methacrylate and triethylamine as a catalyst were added so that 1% by weight of acrylic acid in the copolymer remained, and reacted at 80 ° C. for 10 hours.
It was gelled, and the desired copolymer (A) was not obtained.

Comparative Example 2 The procedure of Example 1 was repeated except that 80 parts of tetraethylene glycol dimethacrylate and 3% of benzophenone were added to the copolymer (A) obtained in Example 1 in place of the glycidyl methacrylate and succinic acid equimolar reaction product. Similarly, a pressure-sensitive adhesive sheet was obtained. The adhesive strength of this adhesive sheet was measured in the same manner as in Example 1, but the adhesive was transferred to the panel side during the adhesive strength measurement.

Comparative Example 3 A pressure-sensitive adhesive sheet was obtained in the same manner as in Example 1 except that 120 parts of an equimolar reaction product of glycidyl methacrylate and succinic acid and 3% of benzophenone were added to the copolymer (A) of Example 1. The adhesive strength (before UV irradiation) of this adhesive sheet
120g / 25mm and low.

Comparative Example 4 A pressure-sensitive adhesive sheet was obtained in the same manner as in Example 1, except that the raw materials shown in Table 2 were used. With this adhesive sheet,
The adhesive strength was measured in the same manner as in Example 1, and the results and (a)-
Table 2 also shows the Tg of the (b)-(c) copolymer.

Example 5 A pressure-sensitive adhesive sheet was obtained in the same manner as in Example 1, except that the raw materials shown in Table 2 were used. The adhesive sheet was measured for adhesive force in the same manner as in Example 1 and the Tg of the copolymer was measured.
Are also shown in Table 2.

Comparative Example 5 A pressure-sensitive adhesive sheet was obtained in the same manner as in Example 5, except that the raw materials shown in Table 2 were used. Table 2 shows the results of measuring the adhesive strength of this adhesive sheet in the same manner as in Example 5 and the Tg of the copolymer.

Claims (1)

(57) [Claims] (A) (a) 75 to 99% by weight of an alkyl (meth) acrylate having 1 to 12 carbon atoms; (b) 1 to 15% by weight of a functional copolymerizable unsaturated monomer; A copolymer having a glass transition temperature of -40 to 30 ° C comprising a vinyl compound of 0 to 24% by weight, wherein all or a part of the component (b) in the copolymer is reactive with the component (b). 100 parts by weight of a copolymer having a radical polymerizable double bond in the side chain reacted with a functional copolymerizable unsaturated monomer having (A), (B) one or more radical polymerizations in one molecule cured by ultraviolet irradiation Viscous or liquid resin at room temperature, which has a functional double bond and further has a carboxyl group as a functional group
A pressure-sensitive adhesive composition comprising 1 to 100 parts by weight, and (C) 0.5 to 15 parts by weight of a photosensitizer.