JP7095269B2 - How to use a pressure-sensitive adhesive composition, a pressure-sensitive adhesive formed by cross-linking the pressure-sensitive adhesive composition, a pressure-sensitive adhesive for a masking film, a masking film, a pressure-sensitive adhesive film for a transparent electrode layer forming process, a tape for a semiconductor manufacturing process, and a masking film. - Google Patents

Description

The present invention relates to a pressure-sensitive adhesive composition, a pressure-sensitive adhesive formed by cross-linking the pressure-sensitive adhesive composition, a pressure-sensitive adhesive for a masking film, a masking film, a pressure-sensitive adhesive film for a transparent electrode layer forming process, a tape for a semiconductor manufacturing process, and a masking film. be. Specifically, a pressure-sensitive adhesive composition that has a sufficient pot life, is extremely excellent in immediate curing and is also excellent in heat resistance, and can be used for a masking film or the like, and the pressure-sensitive adhesive composition is crosslinked. A pressure-sensitive adhesive, a pressure-sensitive adhesive for a masking film made of the pressure-sensitive adhesive, a masking film having a pressure-sensitive adhesive layer made of the pressure-sensitive adhesive on a film, a pressure-sensitive adhesive film for a transparent electrode layer forming process, a tape for a semiconductor manufacturing process, and a masking film. It is about how to use.

Conventionally, a removable adhesive film has been used to temporarily fix and protect members when processing various members. In recent years, for example, circuit boards such as flexible printed wiring (FPC) boards and ITO have been used. It is used as a masking film for temporarily protecting the surface of a transparent electrode layer such as a flat panel display or as an adhesive film for surface protection of a flat panel display or a touch panel.
However, since the annealing process and the wiring forming process include a process of exposing the transparent electrode layer of the FPC substrate or ITO to a high temperature with the protective film attached, the adhesive layer of the adhesive film adheres to the laminated board. Therefore, when the adhesive film is peeled off, contamination due to adhesive residue may occur, or the FPC substrate or the laminated plate of the transparent electrode layer may be damaged. Therefore, even after the high temperature process, it is required to be able to peel off without adhesive residue with a light force when peeling.

On the other hand, at the time of manufacturing the pressure-sensitive adhesive film, in order to sufficiently cure (crosslink) the pressure-sensitive adhesive layer, the pressure-sensitive adhesive composition is applied onto the base film to form the pressure-sensitive adhesive layer, and then the film is allowed to stand for a certain period of time. It is necessary to perform the aging process. Here, if the aging process takes a long time, the adhesive layer follows the fine irregularities on the surface of the base film or the release film during that time, resulting in an adhesive film having irregularities on the surface of the adhesive layer. It ends up.
When such an adhesive film is used for surface protection of, for example, a flat panel display or a touch panel, the unevenness of the surface of the adhesive layer is transferred to an optical film on the surface of the flat panel display which is an adherend, and the flat panel display or the like is used. Depending on the field of application, such as deterioration of visibility, problems may occur even with slight irregularities.
Therefore, the following pressure-sensitive adhesive compositions are known as pressure-sensitive adhesive compositions in which the aging time is shortened (in other words, excellent immediate curing property) and the change in adhesive strength is small due to the progress of cross-linking immediately after coating. Has been done.

Patent Document 1 describes 100 parts by mass of an acrylic polymer (A) containing a hydroxyl group and a carboxyl group, 0.1 parts by weight to 15 parts by weight of an isocyanate-based cross-linking agent (B), and 0 of a catalyst (C) containing iron as an active center. .002 parts by mass to 0.5 part by mass, a pressure-sensitive adhesive composition containing a compound (D) that causes keto-enol telecommunication, and has keto-enol tyranny with respect to a catalyst (C) having an iron as an active center. A pressure-sensitive adhesive composition in which the weight ratio (D / C) of the resulting compound (D) is 3 to 70 is disclosed, and according to the pressure-sensitive adhesive composition, cross-linking proceeds rapidly and adhesion is performed without using a tin compound. It is stated that there is little change in force.

Further, Patent Document 2 describes a (meth) acrylic polymer (A) and isocyanate obtained by polymerizing a monomer component having a glass transition temperature of −50 ° C. or lower and containing an alkyl (meth) acrylate and a hydroxyl group-containing monomer. A pressure-sensitive adhesive composition containing a system cross-linking agent (B) and a catalyst (C) containing iron as an active center is disclosed. It is stated that it can be suppressed.

Japanese Unexamined Patent Publication No. 2015-000945 Japanese Patent Application Laid-Open No. 2015-048394

However, in the techniques of Patent Document 1 and Patent Document 2, although the deformation of the pressure-sensitive adhesive layer is suppressed by promoting the cross-linking reaction, the smoothness of the pressure-sensitive adhesive layer is currently required to be higher. , It was not enough to meet such high standards of demand.

Therefore, under such a background, the present invention has a sufficient pot life, is excellent in immediate curing property, has a small increase in adhesive strength after use under high temperature conditions, can be peeled off with a small force, and further. It is an object of the present invention to provide an adhesive composition which is less likely to be contaminated when peeled from an adherend and can be suitably used for a masking film or the like.

However, as a result of diligent research in view of such circumstances, the present inventor has made an iron-based cross-linking catalyst (C) together with an isocyanate-based cross-linking agent (B) in a pressure-sensitive adhesive composition using a hydroxyl group-containing acrylic resin (A). By further adjusting the product so that the product of the number of hydroxyl groups (mol) in the hydroxyl group-containing acrylic resin (A) and the number of iron-based cross-linking catalysts (C) (mol) is within a specific range. We have found that a pressure-sensitive adhesive composition that solves the above problems can be obtained, and completed the present invention.

That is, the gist of the present invention is a pressure-sensitive adhesive composition containing a hydroxyl group-containing acrylic resin (A), an isocyanate-based cross-linking agent (B), an iron-based cross-linking catalyst (C), and a cross-linking retarder (D). , Satisfy the following equations (1) and (2) ,
The content of the hydroxyl group-containing monomer (a1) in the polymerization component of the hydroxyl group-containing acrylic resin (A) is 2 to 20 % by weight.
For 100 parts by weight of the hydroxyl group-containing acrylic resin (A), 3 to 20 parts by weight of the isocyanate-based crosslinking agent (B) , 0.00005 to 0.05 mol of the iron-based crosslinking catalyst (C), and a crosslinking retarder (D). ) Is contained in an amount of 0.1 to 50 parts by weight.
1.2 × 10 ^-5 ≤ X × Y ≤ 1.0 × 10 ^-2 ... Equation (1)
X: Number of hydroxyl groups (mol) in 100 g of hydroxyl group-containing acrylic resin (A)
Y: The number (mol) of the iron-based cross-linking catalyst (C) with respect to 100 g of the hydroxyl group-containing acrylic resin (A), which is 0.00005 to 0.05 mol.
0.6 ≤ Z / X ≤ 2.0 ... Equation (2)
X: Number of hydroxyl groups (mol) in 100 g of hydroxyl group-containing acrylic resin (A)
Z: Number of isocyanate groups (mol) in the isocyanate-based cross-linking agent (B) with respect to 100 g of the hydroxyl group-containing acrylic resin (A).

Further, the gist of the present invention is a masking film comprising a pressure-sensitive adhesive characterized by being cross-linked by the isocyanate-based cross-linking agent (B) of the pressure-sensitive adhesive composition of the present invention and the pressure-sensitive adhesive of the present invention. A masking film characterized by having a pressure-sensitive adhesive layer made of the pressure-sensitive adhesive of the present invention on a film, a pressure-sensitive adhesive film for a transparent electrode layer forming process, a tape for a semiconductor manufacturing process, and a method for using the masking film. Is also related.

According to the pressure-sensitive adhesive composition of the present invention and the pressure-sensitive adhesive obtained by cross-linking the pressure-sensitive adhesive, the pressure-sensitive adhesive has a sufficient pot life, and when the pressure-sensitive adhesive composition is cured (cross-linked), the adhesive has very excellent immediate curing property. A smooth adhesive layer surface can be formed without transferring the uneven shape of the base film or the release film having fine irregularities, and further, after being used under high temperature conditions, it is peeled off from the adherend. The pressure-sensitive adhesive of the present invention is particularly useful as a pressure-sensitive adhesive for a masking film because it is less likely to be contaminated and can be peeled off with a small force.

Hereinafter, the present invention will be described in detail, but these are examples of desirable embodiments. In the present specification, (meth) acrylic means acrylic or methacrylic, (meth) acryloyl means acryloyl or methacrylic, and (meth) acrylate means acrylate or methacrylate.
Further, in the present invention, the "film" conceptually includes a sheet, a film, and a tape.

<Adhesive composition>
The pressure-sensitive adhesive composition of the present invention contains a hydroxyl group-containing acrylic resin (A), an isocyanate-based cross-linking agent (B), an iron-based cross-linking catalyst (C), and a cross-linking retarder (D).

The pressure-sensitive adhesive composition of the present invention is characterized by satisfying the following formula (1), preferably the following formula (1a), particularly preferably the following formula (1b).
1.2 × 10 ^-5 ≤ X × Y ≤ 1.0 × 10 ^-2 ... Equation (1)
1.3 × 10 ^-5 ≤ X × Y ≤ 1.0 × 10 ^-3 ... Equation (1a)
1.5 × 10 ^-5 ≤ X × Y ≤ 5.0 × 10 ^-4 ... Equation (1b)
X: Number of hydroxyl groups (mol) in 100 parts by weight of the hydroxyl group-containing acrylic resin (A)
Y: Number (mol) of iron-based cross-linking catalyst (C) with respect to 100 parts by weight of hydroxyl group-containing acrylic resin (A)
If the value of X × Y is too large, the pot life is shortened and the coatability is deteriorated, and if it is too small, the immediate curing property is insufficient.

X in the above formula is the number of hydroxyl groups (mol) in 100 parts by weight of the hydroxyl group-containing acrylic resin (A), preferably 0.001 to 1.0 mol, particularly preferably 0.005 to 0.9 mol. More preferably, it is 0.01 to 0.8 mol.
If the value of X is too large, cross-linking proceeds before the drying step, and the coatability tends to deteriorate. If the value of X is too small, the crosslink density becomes low, and it tends to be difficult to improve the unevenness on the surface of the pressure-sensitive adhesive layer.

Y in the above formula is the number (mol) of the iron-based crosslinking catalyst (C) with respect to 100 parts by weight of the hydroxyl group-containing acrylic resin (A), preferably 0.00001 to 0.1 mol, and particularly preferably 0.00005. It is ~ 0.05 mol, more preferably 0.0001 to 0.01 mol.
If the value of Y is too large, the stability of the compounding solution tends to decrease. If the value of Y is too small, the immediate curing property becomes insufficient, and it tends to be difficult to improve the unevenness on the surface of the pressure-sensitive adhesive layer.

Further, the pressure-sensitive adhesive composition of the present invention preferably satisfies the following formula (2), preferably the following formula (2a), and particularly preferably the following formula (2b).
0.6 ≤ Z / X ≤ 2.0 ... Equation (2)
0.7 ≤ Z / X ≤ 1.8 ... Equation (2a)
0.8 ≤ Z / X ≤ 1.5 ... Equation (2b)
X: Number of hydroxyl groups (mol) in 100 parts by weight of the hydroxyl group-containing acrylic resin (A)
Z: Number of isocyanate groups (mol) in the isocyanate-based cross-linking agent (B) with respect to 100 parts by weight of the hydroxyl group-containing acrylic resin (A).
If the Z / X value is too large, the adherend tends to be contaminated, and if it is too small, the adhesive strength tends to be too high and the peelability at the time of peeling tends to decrease.

Z in the above formula is the number (mol) of isocyanate groups in the isocyanate-based cross-linking agent (B) with respect to 100 parts by weight of the hydroxyl group-containing acrylic resin (A), preferably 0.001 to 1.0 mol, particularly. It is preferably 0.005 to 0.9 mol, more preferably 0.01 to 0.8 mol.
If the value of Z is too large, the adherend tends to be contaminated. If the value of Z is too small, the adhesive strength becomes too high, and the peelability at the time of peeling tends to decrease.

The pressure-sensitive adhesive composition of the present invention preferably satisfies the following formula (3), preferably the following formula (3a), and particularly preferably the following formula (3b).
1.0 × 10 ^-4 ≦ Y / Z ≦ 10 ・ ・ ・ Equation (3)
1.0 × 10 ^-3 ≤ Y / Z ≤ 5 ... Equation (3a)
1.0 × 10 ^-3 ≤ Y / Z ≤ 1 ... Equation (3b)
Y: Number (mol) of iron-based cross-linking catalyst (C) with respect to 100 parts by weight of hydroxyl group-containing acrylic resin (A)
Z: Number of isocyanate groups (mol) in the isocyanate-based cross-linking agent (B) with respect to 100 parts by weight of the hydroxyl group-containing acrylic resin (A).
If the Y / Z value is too large, the pot life is shortened, so that the coatability tends to be deteriorated, and if it is too small, the immediate curing property tends to be insufficient.

The pressure-sensitive adhesive composition of the present invention preferably satisfies the following formula (4), preferably the following formula (4a), and particularly preferably the following formula (4b).
1.0 × 10 ^-6 ≤ Z × Y ≤ 5.0 × 10 ^-2 ... Equation (4)
5.0 × 10 ^-6 ≤ Z × Y ≤ 1.0 × 10 ^-3 ... Equation (4a)
1.0 × 10 ^-5 ≤ Z × Y ≤ 5.0 × 10 ^-4 ... Equation (4b)
Y: Number (mol) of iron-based cross-linking catalyst (C) with respect to 100 parts by weight of hydroxyl group-containing acrylic resin (A)
Z: Number of isocyanate groups (mol) in the isocyanate-based cross-linking agent (B) with respect to 100 parts by weight of the hydroxyl group-containing acrylic resin (A).
If the value of Z × Y is too large, the pot life tends to be short, so that the coatability tends to decrease, and if it is too small, the immediate curability tends to be insufficient.

[Hydroxy group-containing acrylic resin (A)]
The hydroxyl group-containing acrylic resin (A) used in the present invention is obtained by polymerizing a polymerization component containing a hydroxyl group-containing monomer (a1) as an essential component, and if necessary, an alkyl (meth) acrylate. It is obtained by polymerizing a polymerization component appropriately containing an ester-based monomer (a2), a functional group-containing monomer (a3) other than the hydroxyl group-containing monomer (a1), and another polymerizable monomer (a4) as a polymerization component.

Examples of the hydroxyl group-containing monomer (a1) include a primary hydroxyl group-containing monomer, a secondary hydroxyl group-containing monomer, and a tertiary hydroxyl group-containing monomer. Examples of the primary hydroxyl group-containing monomer include 2-hydroxyethyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 5-hydroxypentyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate, and 8-hydroxyoctyl. Acrylic acid hydroxyalkyl esters such as (meth) acrylates; Caprolactone-modified monomers such as caprolactone-modified 2-hydroxyethyl (meth) acrylates; Oxyalkylene-modified monomers such as diethylene glycol (meth) acrylates and polyethylene glycol (meth) acrylates; Others, 2 -Acryloyloxyethyl-2-hydroxyethylphthalic acid and the like can be mentioned. Examples of the secondary hydroxyl group-containing monomer include 2-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, 3-chloro2-hydroxypropyl (meth) acrylate and the like. Examples of the tertiary hydroxyl group-containing monomer include 2,2-dimethyl2-hydroxyethyl (meth) acrylate and the like.
As these hydroxyl group-containing monomers (a1), one type can be used alone or two or more types can be used in combination.
Among the above hydroxyl group-containing monomers, it is preferable to use a primary hydroxyl group-containing monomer because of its excellent reactivity with the isocyanate-based cross-linking agent (B), and in particular, 2-hydroxyethyl (meth) acrylate and 4-hydroxybutyl. It is preferable to use (meth) acrylate.

The content of the hydroxyl group-containing monomer (a1) in the polymerization component is preferably 0.1 to 30% by weight, particularly preferably 1 to 25% by weight, and even more preferably 2 to 20% by weight. If the content is too high, cross-linking will proceed before the drying process, which tends to cause problems in coatability, or the resin is too hard and tends to float between the resin and the adherend. If the content is too low, the cross-linking tends to proceed. The degree of cross-linking tends to decrease and the adherend contamination tends to increase.

As the hydroxyl group-containing monomer (a1) used in the present invention, it is preferable to use one having a content ratio of di (meth) acrylate as an impurity of 0.5% or less, and particularly 0.2% or less. Further, it is preferable to use one having a content of 0.1% or less.

The (meth) acrylic acid alkyl ester-based monomer (a2) used in the present invention usually has an alkyl group having a carbon number of 1 to 20, preferably 1 to 12, and particularly preferably 1 to 8. If the carbon number is too large, the adherend contamination after the heating step tends to increase.

Specifically, for example, methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, n-butyl (meth) acrylate, iso-butyl (meth) acrylate, tert-butyl (meth) acrylate. , N-hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, n-octyl (meth) acrylate, iso-octyl acrylate, isodecyl (meth) acrylate, lauryl (meth) acrylate, cetyl (meth) acrylate, n- Examples thereof include stearyl (meth) acrylate and iso-stearyl (meth) acrylate.
These can be used alone or in combination of two or more.
Among them, the (meth) acrylic acid ester-based monomer (a2) includes methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, iso-butyl (meth) acrylate, and tert-butyl (meth). ) An aliphatic (meth) acrylic acid ester having 1 to 8 carbon atoms of an alkyl group such as acrylate, n-propyl (meth) acrylate, n-hexyl (meth) acrylate, and 2-ethylhexyl (meth) acrylate is preferable.

The content of the (meth) acrylic acid alkyl ester-based monomer (a2) in the polymerization component is usually 40 to 99.9% by weight, preferably 45 to 99% by weight, and particularly preferably 50 to 98% by weight. be. If the content is too small, the adhesive strength after the heating step tends to be too high, and if it is too large, the adherend contamination after the heating step tends to increase.
Further, in the (meth) acrylic acid alkyl ester-based monomer (a2), the content of the (meth) acrylic acid alkyl ester-based monomer having 1 to 8 carbon atoms of the alkyl group is 80% by weight or more after the heating step. It is preferable in that it is excellent in adherent contamination resistance, and is particularly preferably 85% by weight or more, further preferably 90% by weight or more, and particularly preferably 95% by weight or more.

Examples of the functional group-containing monomer (a3) other than the hydroxyl group-containing monomer (a1) include a carboxyl group-containing monomer, an acetoacetyl group-containing monomer, an isocyanate group-containing monomer, a glycidyl group-containing monomer, an amino group-containing monomer, and an amide group. Examples include monomers.

Examples of the carboxyl group-containing monomer include (meth) acrylic acid, acrylic acid dimer, crotonic acid, maleic acid, maleic anhydride, fumaric acid, citraconic acid, glutaconic acid, itaconic acid, acrylamideN-glycolic acid, and silica skin. Acids and the like are mentioned, and among them, (meth) acrylic acid is preferably used because it is excellent in copolymerizability, but when it is used for a metal substrate, it is preferable that it does not contain a carboxyl group from the viewpoint of preventing corrosion. ..

Examples of the acetoacetyl group-containing monomer include 2- (acetoacetoxy) ethyl (meth) acrylate and allyl acetoacetate.

Examples of the isocyanate group-containing monomer include 2-acryloyloxyethyl isocyanate, 2-methacryloyloxyethyl isocyanate, and alkylene oxide adducts thereof.

Examples of the glycidyl group-containing monomer include glycidyl (meth) acrylate and allyl glycidyl (meth) acrylate.

Examples of the amino group-containing monomer include monomers having an ethylenically unsaturated double bond and an amino group (unsubstituted or substituted amino group), for example, aminomethyl (meth) acrylate, aminoethyl (meth) acrylate, and the like. Aminoalkyl (meth) acrylates such as aminopropyl (meth) acrylate and aminoisopropyl (meth) acrylate and (meth) of N-alkylaminoalkyl such as N- (t-butyl) aminoethyl (meth) acrylate. Mono-substituted amino group-containing (meth) acrylic acid ester such as acrylic acid ester; (meth) acrylic acid N, N-dimethylaminoethyl, (meth) acrylic acid N, N-diethylaminoethyl, (meth) acrylic acid N, N -Disubstituted amino group-containing (meth) acrylic acid esters such as (meth) acrylic acid esters of N, N-dialkylaminoalkyl such as dimethylaminopropyl; quaternized salts of these amino group-containing monomers, etc .; p- Amino group-containing styrenes such as aminostyrene; styrenes having a dialkylamino group such as 3- (dimethylamino) styrene and dimethylaminomethylstyrene; N, N-dimethylaminoethylvinyl ether, N, N-diethylaminoethylvinyl ether and the like. Dialkylaminoalkylvinyl ethers; examples include allylamine, 4-diisopropylamino-1-butene, trans-2-butene-1,4-diamine, 2-vinyl-4,6-diamino-1,3,5-triazine and the like. ..
In addition, in this specification, a monomer having an ethylenically unsaturated double bond and an amino group (unsubstituted or substituted amino group) and having an amide group (a group having an amide bond) is described below. It shall be included in the amide group-containing monomer.

Examples of the amide group-containing monomer include a monomer having an ethylenically unsaturated double bond and an amide group (a group having an amide bond), and examples thereof include (meth) acrylamide; N-methyl (meth) acrylamide and N-ethyl. (Meta) acrylamide, N-propyl (meth) acrylamide, N-isopropyl (meth) acrylamide, Nn-butyl (meth) acrylamide, N-isobutyl (meth) acrylamide, N-s-butyl (meth) acrylamide, N -T-Butyl (meth) acrylamide, N-hexyl (meth) acrylamide, diacetone (meth) acrylamide, N, N'-methylenebis (meth) acrylamide, N- (1,1-dimethyl-3-oxobutyl) (meth) ) N-alkyl (meth) acrylamide such as acrylamide; N, N-dimethyl (meth) acrylamide, N, N-diethyl (meth) acrylamide, N, N-dipropyl (meth) acrylamide, N, N-diisopropyl (meth) Acrylamide, N, N-di (n-butyl) (meth) acrylamide, N, N-diisobutyl (meth) acrylamide, N, N-di (s-butyl) (meth) acrylamide, N, N-di (t-) Butyl) (meth) acrylamide, N, N-dipentyl (meth) acrylamide, N, N-dihexyl (meth) acrylamide, N, N-diheptyl (meth) acrylamide, N, N-dioctyl (meth) acrylamide, N, N -N, N-dialkyl (meth) acrylamide such as diallyl (meth) acrylamide, N, N-ethylmethylacrylamide; dialkylaminoalkyl (meth) acrylamide such as N, N-dimethylaminopropyl (meth) acrylamide; N-vinyl Substituent group-containing monomers such as acetoamide, N-vinylformamide, (meth) acrylamide ethylethylene urea, (meth) acrylamide t-butyl sulfonic acid; N-methylol (meth) acrylamide, N-hydroxyethyl (meth) acrylamide, N -Hydryl group-containing (meth) acrylamide such as methylolpropane (meth) acrylamide; alkoxy group-containing (meth) acrylamide such as N-methoxymethyl (meth) acrylamide and N- (n-butoxymethyl) (meth) acrylamide; these amides Examples thereof include quaternized salts of group-containing monomers.

As the functional group-containing monomer (a3) other than the hydroxyl group-containing monomer (a1), one type may be used alone, or two or more types may be used in combination.
Among these, in the present invention, from the viewpoint of promoting cross-linking effect, it is preferable to contain a functional group-containing monomer containing a nitrogen atom, particularly preferably an amino group-containing monomer, an amide group-containing monomer, and further preferably dimethylamino. Ethyl (meth) acrylate, diethylaminoethyl methacrylate, dimethylaminopropyl (meth) acrylamide, dimethyl (meth) acrylamide, particularly preferably dimethylaminopropyl acrylamide.

The content of the functional group-containing monomer (a3) other than the hydroxyl group-containing monomer (a1) in the polymerization component is usually 0.001 to 30% by weight, preferably 0.01 to 20% by weight, and particularly preferably 0. It is 0.05 to 15% by weight. If the content is too high, cross-linking will proceed before the drying process, which tends to cause problems in coatability, or the resin is too hard and tends to float between the resin and the adherend. If the content is too low, the cross-linking tends to proceed. The degree of cross-linking tends to decrease and the adherend contamination tends to increase.

When the functional group-containing monomer (a3) other than the hydroxyl group-containing monomer (a1) contains an amino group-containing monomer and / or an amide group-containing monomer, the content ratio of the monomer in the polymerization component is preferably 0.001. It is ~ 30% by weight, particularly preferably 0.005 to 5% by weight, still more preferably 0.01 to 2% by weight. If the content ratio is too large, the molecular weight tends to decrease during polymerization or the pressure-sensitive adhesive tends to be colored, and if it is too small, the cross-linking promoting effect tends to be difficult to obtain sufficiently.

Examples of other copolymerizable monomers (a4) include, for example.
(Meta) acrylic acid containing an aromatic ring such as phenyl (meth) acrylate, benzyl (meth) acrylate, phenoxyethyl (meth) acrylate, phenyldiethylene glycol (meth) acrylate, 2-hydroxy-3-phenoxypropyl (meth) acrylate. Ester-based monomer;
It has an alicyclic structure such as cyclohexyl (meth) acrylate, cyclohexyloxyalkyl (meth) acrylate, t-butylcyclohexyloxyethyl (meth) acrylate, isobornyl (meth) acrylate, and dicyclopentanyl (meth) acrylate (meth). ) Acrylic acid ester-based monomer;
Biphenyloxy structure-containing (meth) acrylic acid ester-based monomers such as biphenyloxyethyl (meth) acrylate;
Alkoxy such as 2-methoxyethyl (meth) acrylate, 2-ethoxyethyl (meth) acrylate, methoxydiethylene glycol (meth) acrylate, ethoxydiethylene glycol (meth) acrylate, methoxypolyethylene glycol (meth) acrylate, polypropylene glycol mono (meth) acrylate. A (meth) acrylic acid ester-based monomer containing a group or an oxyalkylene group;
Styline, α-methylstyrene, acrylonitrile, methacrylonitrile, vinyl acetate, vinyl propionate, vinyl stearate, vinyl chloride, vinylidene chloride, alkyl vinyl ether, vinyl toluene, vinyl pyridine, vinyl pyrrolidone, itaconic acid dialkyl ester, dialkyl fumarate Examples thereof include esters, allyl alcohols, acrylic chlorides, methyl vinyl ketones, allyltrimethylammonium chlorides, and dimethylallylvinyl ketones.
These can be used alone or in combination of two or more.

The content of the other copolymerizable monomer (a4) in the polymerization component is usually 0 to 40% by weight, preferably 0.001 to 30% by weight, and particularly preferably 0.01 to 25% by weight. .. If the content is too high, the adhesive properties tend to deteriorate.

For the polymerization of the hydroxyl group-containing acrylic resin (A), conventionally known methods such as solution radical polymerization, suspension polymerization, bulk polymerization and emulsion polymerization can be adopted. Among them, a solvent-based hydroxyl group-containing acrylic resin obtained by solution radical polymerization is preferable because an acrylic resin composition can be safely and stably produced with an arbitrary monomer composition. For example, in the organic solvent, the hydroxyl group-containing monomer (a1), the (meth) acrylic acid alkyl ester-based monomer (a2), and if necessary, a functional group-containing monomer (a3) other than the hydroxyl group-containing monomer (a1), and the like. A solvent-based hydroxyl group-containing acrylic resin obtained by mixing or dropping a polymerization component containing the polymerizable monomer (a4) and a polymerization initiator and polymerizing in a reflux state or at 50 to 90 ° C. for 2 to 20 hours is preferable.

The weight average molecular weight of the hydroxyl group-containing acrylic resin (A) of the present invention is usually 100,000 to 2.5 million, preferably 200,000 to 2.2 million, and particularly preferably 400,000 to 2 million. If the weight average molecular weight is too large, a large amount of diluting solvent is required, which tends to be disadvantageous in terms of coatability and cost, and if it is too small, the heat resistance of the adhesive layer is lowered and the adherend contamination is increased. Tend.

The dispersity (weight average molecular weight / number average molecular weight) of the hydroxyl group-containing acrylic resin (A) is, for example, usually 20 or less, preferably 15 or less, particularly preferably 10 or less, and the lower limit is usually 1. It is 1. If the degree of dispersion is too high, the heat resistance of the pressure-sensitive adhesive layer is lowered, and foaming or the like tends to occur easily.

The above weight average molecular weight is a weight average molecular weight converted to a standard polystyrene molecular weight, and is used in high performance liquid chromatography (manufactured by Japan Waters, "Waters 2695 (main body)" and "Waters 2414 (detector)"). : Chromatography GPC KF-806L (exclusion limit molecular weight: 2 × 10 ⁷ , separation range: 100 to 2 × 10 ⁷ , theoretical number of stages: 10,000 stages / piece, filler material: styrene-divinylbenzene copolymer, filler It is measured by using three series having a particle size (particle size: 10 μm), and the same method can be used for the number average molecular weight. The degree of dispersion is obtained from the weight average molecular weight and the number average molecular weight.
Further, the polymer may be derivatized at the time of measurement, or the type of eluent may be appropriately changed.

Further, the glass transition temperature of the hydroxyl group-containing acrylic resin (A) is usually −80 to 10 ° C., preferably −75 to 5 ° C., and particularly preferably −70 to 0 ° C. If the glass transition temperature is too high, the adhesive strength after the heating step tends to be high, and if the glass transition temperature is too low, the heat resistance tends to decrease and the adherend contamination tends to increase.

Ｔｇ：共重合体のガラス転移温度（Ｋ）
Ｔga：モノマーＡのホモポリマーのガラス転移温度（Ｋ） Ｗａ：モノマーＡの重量分率
Ｔgb：モノマーＢのホモポリマーのガラス転移温度（Ｋ） Ｗｂ：モノマーＢの重量分率
Ｔgn：モノマーＮのホモポリマーのガラス転移温度（Ｋ） Ｗｎ：モノマーＮの重量分率
（Ｗａ＋Ｗｂ＋・・・＋Ｗｎ＝１） The glass transition temperature is calculated from the following Fox formula.

Tg: Copolymer glass transition temperature (K)
Tga: glass transition temperature of homopolymer of monomer A (K) Wa: weight fraction of monomer A Tgb: glass transition temperature of homopolymer of monomer B (K) Wb: weight fraction of monomer B Tgn: homomer of monomer N Polymer glass transition temperature (K) Wn: Weight fraction of monomer N (Wa + Wb + ... + Wn = 1)

That is, it is a value calculated by applying the glass transition temperature and the weight fraction when homopolymers of the respective monomers constituting the acrylic resin are applied to the Fox formula.
The glass transition temperature when a homopolymer of a monomer constituting an acrylic resin is used is usually measured by a differential scanning calorimeter (DSC).

The content of the hydroxyl group-containing acrylic resin (A) is preferably 30 to 99% by weight, particularly preferably 40 to 98.5% by weight, still more preferably 50 to 98% by weight, based on the total amount of the pressure-sensitive adhesive composition. It is% by weight.

[Isocyanate-based cross-linking agent (B)]
It is important that the pressure-sensitive adhesive composition of the present invention contains an isocyanate-based cross-linking agent (B) as a cross-linking agent in that the reactivity is high and the heat resistance is improved.

Examples of the isocyanate-based cross-linking agent (B) include, for example.
Aromatic diisocyanates such as 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, diphenylmethane diisocyanate, 1,5-naphthylenedi isocyanate, trizine diisocyanate, xylylene diisocyanate, tetramethylxylylene diisocyanate;
Alicyclic diisocyanates such as isophorone diisocyanate, hydrogenated xylylene diisocyanate, hydrogenated diphenylmethane diisocyanate, dimerate diisocyanate, norbornene diisocyanate, trans-cyclohexanediisocyanate, and hydrogenated tolylene diisocyanate;
Aliphatic isocyanates such as hexamethylene diisocyanate;
Etc.,
Further, an adduct form of these polyisocyanate compounds and a polyol compound such as trimethylolpropane, a burette form of these polyisocyanate compounds, an isocyanurate form and the like can be mentioned.

Among them, isocyanurates of hexamethylene diisocyanate and 2,4-tolylene diisocyanate are good in that the increase in adhesive strength after heating is small and the adhesive residue is difficult to remain when peeled off after heating (heat-resistant stain resistance). And / or an adduct of 2,6-tolylene diisocyanate and trimethylolpropane, isocyanurate of 2,4-tolylene diisocyanate and / or 2,6-tolylene diisocyanate, tetramethylxylylene diisocyanate and trimethylolpropane. The adduct body with is preferable.

The content of the isocyanate-based cross-linking agent (B) is preferably 0.5 to 40 parts by weight, particularly preferably 3 to 30 parts by weight, more preferably 3 parts by weight, based on 100 parts by weight of the hydroxyl group-containing acrylic resin (A). It is 5 to 20 parts by weight. If the content of the isocyanate-based cross-linking agent is too large, the cross-linking of the pressure-sensitive adhesive proceeds too much and the adhesive strength is lowered, so that there is a tendency for floating to occur between the adhesive and the surface of the adherend. The cohesive force of the agent is reduced, which tends to cause adhesive residue.

Further, in the present invention, other cross-linking agents usually used for the pressure-sensitive adhesive composition can be used in combination as long as the object of the present invention is not impaired.
Examples of such a cross-linking agent include an epoxy-based cross-linking agent, an aziridine-based cross-linking agent, an oxazoline-based cross-linking agent, a melamine-based cross-linking agent, an aldehyde-based cross-linking agent, an amine-based cross-linking agent, and the like.

[Iron-based cross-linking catalyst (C)]
The iron-based cross-linking catalyst (C) is a catalyst having iron as an active center and promotes the reaction of the isocyanate-based cross-linking agent (B). It is important that the pressure-sensitive adhesive composition of the present invention contains the iron-based cross-linking catalyst (C) in that both pot life and immediate curability can be achieved and a smooth pressure-sensitive adhesive layer can be obtained.

As the iron-based cross-linking catalyst (C), an iron chelate compound can be preferably used, and can be represented by, for example, the general formula Fe (L) (M) (N). The iron chelate compound is represented by any of Fe (L) ₃ , Fe (L) ₂ (M), and Fe (L) (M) (N) depending on the combination of (L), (M), and (N).
In the iron chelate compounds Fe (L) (M) (N), (L) (M) (N) are ligands for Fe, respectively. For example, when L, M or N is β-diketone, the β-diketone may be, for example, acetylacetone, hexane-2,4-dione, heptane-2,4-dione, heptane-3,5-dione, 5-. Methyl-hexane-2,4-dione, octane-2,4-dione, 6-methylheptane-2,4-dione, 2,6-dimethylheptane-3,5-dione, nonane-2,4-dione, Nonane-4,6-dione, 2,2,6,6-tetramethylheptane-3,5-dione, tridecane-6,8-dione, 1-phenyl-butane-1,3-dione, hexafluoroacetylacetone, Ascorbic acid and the like can be mentioned.
When L, M or N is β-ketoester, the β-ketoester may be, for example, methyl acetoacetate, ethyl acetoacetate, acetoacetic acid-n-propyl, isopropyl acetoacetate, acetoacetic acid-n-butyl, acetoacetic acid. -Sec-Butyl, Acetate Acetic Acid-tert-Butyl, Propionyl Acetic Acid Methyl, Propionyl Acetate Ethyl, Propionyl Acetic Acid-n-propyl, Propionyl Acetic Acid isopropyl, Propionyl Acetic Acid-n-Butyl, Propionyl Acetic Acid-sec-Butyl, Propionyl Acetic Acid-tert- Examples thereof include butyl, benzyl acetate acetate, dimethyl malonate, diethyl malonate and the like. One of these iron-based cross-linking catalysts (C) can be used alone or in combination of two or more.

In the present invention, among these iron-based cross-linking catalysts (C), an iron chelate compound having β-diketone as a ligand is preferable in terms of reactivity and curability, and tris (acetylacetonate) iron is particularly used. Is preferable.

Specific iron-based cross-linking catalysts (C) include, for example, "Nasem Daini Iron" manufactured by Nippon Kagaku Sangyo Co., Ltd., "Nikka Octix Iron" manufactured by Nippon Kagaku Sangyo Co., Ltd., and "Tris" manufactured by Tokyo Kasei Kogyo Co., Ltd. 2,4-Pentandionato iron (III), "2,4-Pentandionate iron (III)" manufactured by Wako Pure Chemical Industries, Ltd., "Iron (III) acetylacetonate" manufactured by Sigma Aldrich Japan GK, etc. Can be mentioned.

The content of the iron-based cross-linking catalyst (C) is preferably 0.001 to 30 parts by weight, particularly preferably 0.005 to 20 parts by weight, based on 100 parts by weight of the hydroxyl group-containing acrylic resin (A). It is preferably 0.01 to 15 parts by weight.
If the content of the iron-based cross-linking catalyst (C) is too large, the stability of the compounding solution tends to decrease, and if the content is too small, the immediate curability tends to decrease, and unevenness tends to be easily transferred to the surface of the coating film. There is.

[Crosslink retarder (D)]
It is necessary for the pressure-sensitive adhesive composition of the present invention to contain a cross-linking retarder (D) in order to maintain a sufficient pot life and improve coatability.
The cross-linking retarder (D) is contained to regulate the activity of the iron-based cross-linking catalyst (C) and balance the pot life and curability of the pressure-sensitive adhesive composition. The cross-linking retarder (D) acts as a chelating agent for the iron-based cross-linking catalyst (C) in the pressure-sensitive adhesive composition, and blocks the iron-based cross-linking catalyst (C) to block the iron-based cross-linking catalyst (C). It is possible to suppress excessive increase in viscosity and gelation of the pressure-sensitive adhesive composition and prolong the pot life of the pressure-sensitive adhesive composition. After that, when the cross-linking retarder (D) volatilizes by applying the pressure-sensitive adhesive composition to a substrate or the like and drying it, the iron-based cross-linking catalyst (C) blocked by the cross-linking retarder (D) becomes active. The effect of promoting cross-linking is exhibited, and the cross-linking of the pressure-sensitive adhesive composition proceeds.

Examples of the cross-linking retarder (D) include β-ketoesters such as methyl acetoacetic acid, ethyl acetoacetate, octyl acetoacetic acid, oleyl acetoacetic acid, lauryl acetoacetic acid, and stearyl acetoacetic acid, and acetylacetone and 2,4-hexanedione. , Β-diketone such as benzoylacetone. These are ketoenol remutable compounds, and by protecting the iron-based cross-linking catalyst (C), the catalytic activity of the iron-based cross-linking catalyst (C) in a solution state is reduced, and the pressure-sensitive adhesive composition after compounding is used. It is possible to suppress an excessive increase in viscosity and gelation, and to extend the pot life of the pressure-sensitive adhesive composition.
Among these, it is preferable to use acetylacetone as the cross-linking retarder (D) from the viewpoint of the balance between pot life and immediate curing.
As these cross-linking retarders (D), one type may be used alone or two or more types may be used in combination.

Specific examples of the cross-linking retarder (D) include "acetylacetone" manufactured by Daicel Corporation, "acetylacetone" manufactured by Tokyo Chemical Industry, "acetylacetone" manufactured by Wako Pure Chemical Industries, Ltd., and "acetylacetone" manufactured by Kishida Chemical Industries.

Since the cross-linking retarder (D) has an effect of suppressing cross-linking as opposed to the cross-linking promoting effect of the iron-based cross-linking catalyst (C), the ratio of the cross-linking delaying agent (D) to the iron-based cross-linking catalyst (C). Is preferably set appropriately.
In order to extend the pot life of the pressure-sensitive adhesive composition and not impair the immediate curing property, the content ratio (weight ratio) of the iron-based crosslinking catalyst (C) (solid content equivalent amount) to the crosslinking retarder (D) ( C) / (D) is preferably (C) / (D) = 0.1 to 100, particularly preferably 0.5 to 90, and even more preferably 1 to 80.
If the content of the cross-linking retarder (D) is too small with respect to the content of the iron-based cross-linking catalyst (C), the pot life tends to be short and the coatability tends to deteriorate, and if it is too large, the immediate curability deteriorates. Tend to do.

The content of the cross-linking retarder (D) is preferably 0.1 to 50 parts by weight, particularly preferably 0.5 to 40 parts by weight, still more preferably, with respect to 100 parts by weight of the hydroxyl group-containing acrylic resin (A). Is 1.0 to 30 parts by weight.
If the content of the cross-linking retarder (D) is too large, the immediate curability tends to decrease, and if the content is too small, the pot life tends to be shortened.

[Other ingredients]
The pressure-sensitive adhesive composition of the present invention further comprises an antioxidant, an antioxidant, a plasticizer, a filler, a pigment, a diluent, an antioxidant, an ultraviolet absorber, and an ultraviolet stabilizer as long as the effects of the present invention are not impaired. , Additives such as tackifier resin may be further contained, and these additives may be used alone or in combination of two or more. In particular, antioxidants are effective in maintaining the stability of the pressure-sensitive adhesive layer. The content of the antioxidant when blended is not particularly limited, but is preferably 0.01 to 5% by weight. In addition to the additives, a small amount of impurities and the like contained in the raw materials for producing the constituent components of the pressure-sensitive adhesive composition may be contained.

The pressure-sensitive adhesive composition of the present invention contains a hydroxyl group-containing acrylic resin (A), an isocyanate-based crosslinking agent (B), an iron-based crosslinking catalyst (C), a crosslinking retarder (D), and other components as necessary. It can be prepared by blending by a conventional method, but if the iron-based cross-linking catalyst (C) is blended before the cross-linking retarder (D) is blended, cross-linking starts and gels, so that iron-based cross-linking occurs. It is preferable to add the cross-linking retarder (D) before adding the catalyst (C), or to add a mixture of the iron-based cross-linking catalyst (C) and the cross-linking delay agent (D).

The gel fraction of the pressure-sensitive adhesive obtained by cross-linking the pressure-sensitive adhesive composition of the present invention with the isocyanate-based cross-linking agent (B) is usually 40 to 100%, preferably 60 to 100%, particularly preferably 80 to 100%. It is more preferably 85 to 100%, and particularly preferably 90 to 100%.
If the gel fraction is too low, the cohesive force of the pressure-sensitive adhesive will decrease, resulting in adhesive residue, which tends to cause contamination of the adherend.

The gel fraction is a measure of the degree of cross-linking and is calculated by the following method. That is, a pressure-sensitive adhesive sheet (without a release film) in which a pressure-sensitive adhesive layer is formed on a polymer sheet (for example, a polyethylene terephthalate film) as a base material is wrapped in a 200-mesh SUS wire net and placed in toluene. Is immersed in 23 ° C. for 24 hours, and the weight percentage of the insoluble adhesive component remaining in the wire net is defined as the gel fraction. However, the weight of the base material is subtracted from the calculation.

<Adhesive, adhesive film>
The pressure-sensitive adhesive composition of the present invention can be cross-linked with an isocyanate-based cross-linking agent (B) to obtain a pressure-sensitive adhesive having a slightly adhesive to low-adhesive adhesive strength (about 2N / 25 mm or less). Such an adhesive is suitably used as an adhesive for an adhesive film such as an adhesive for a masking film to be bonded to the adherend for a short period (several hours to several days) in order to temporarily protect the surface of the adherend. Be done.
Examples of such an adhesive film include an adhesive film for a transparent electrode layer forming step used in a process for forming a transparent electrode layer made of ITO and the like, a tape for a semiconductor manufacturing process used in a semiconductor manufacturing process, and the like, in addition to a masking film.

In the present invention, a pressure-sensitive adhesive such as a masking film pressure-sensitive adhesive is prepared from the above-mentioned pressure-sensitive adhesive composition, and a pressure-sensitive adhesive layer is laminated and formed on a film as a base material to obtain a pressure-sensitive adhesive film such as a masking film. Can be done. The pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer is a pressure-sensitive adhesive composition obtained by cross-linking the above-mentioned pressure-sensitive adhesive composition with an isocyanate-based cross-linking agent (B).

Examples of the base material on which the pressure-sensitive adhesive layer is laminated include a single-layer or laminated film made of a metal, a polyester-based resin, a polyfluoroethylene-based resin, a polyimide and a derivative thereof, an epoxy resin, and the like. For an adhesive film such as a masking film, it is preferable to further provide a release film on the surface of the adhesive layer opposite to the base material. When an adhesive film such as a masking film is put into practical use, the release film is peeled off and used. As the release film, for example, a silicon-based release film, an olefin-based release film, a fluorine-based release film, a long-chain alkyl-based release film, and an alkyd-based release film can be used. ..

Regarding the method for producing the above-mentioned pressure-sensitive adhesive film, [1] a method of applying a pressure-sensitive adhesive composition on a substrate, drying it, and then laminating a release film to perform an aging treatment, [2] a release-type film. Examples thereof include a method in which a pressure-sensitive adhesive composition is applied, dried, and then a base material is attached to perform an aging treatment. Among these, the method of [1] is preferable in terms of improving the adhesion to the base material, workability and stable production.

The above aging treatment is carried out in order to balance the adhesive characteristics, and the aging conditions are such that the temperature is usually 0 to 150 ° C., preferably 10 to 100 ° C., particularly preferably 20 to 80 ° C., and the time is Usually, it is 30 days or less, preferably 14 days or less, particularly preferably 7 days or less, and specifically, it can be carried out under conditions such as, for example, 23 ° C. for 3 to 10 days, 40 ° C. for 1 to 7 days, and the like. ..

In the production of the pressure-sensitive adhesive film, an aging treatment is usually required in order to sufficiently proceed the cross-linking reaction of the layer made of the pressure-sensitive adhesive composition (hereinafter referred to as the pressure-sensitive adhesive composition layer). Since the content of the iron-based cross-linking catalyst (C) makes it excellent in immediate curing, fine irregularities on the surface of the base film and the release film are not transferred to the pressure-sensitive adhesive composition layer during aging. A smooth pressure-sensitive adhesive layer surface can be formed.

When applying the pressure-sensitive adhesive composition, it is preferable to dilute the pressure-sensitive adhesive composition with a solvent and apply the pressure-sensitive adhesive composition, and the dilution concentration is preferably 5 to 60% by weight, particularly preferably 10 to 50% by weight. The solvent is not particularly limited as long as it dissolves the pressure-sensitive adhesive composition, and is, for example, an ester solvent such as methyl acetate, ethyl acetate, methyl acetoacetate, ethyl acetoacetate; acetone, methyl ethyl ketone, and the like. Ketone-based solvents such as methylisobutylketone; aromatic solvents such as toluene and xylene; alcohol-based solvents such as methanol, ethanol and propyl alcohol can be used. Among these, ethyl acetate, methyl ethyl ketone, and toluene are preferably used from the viewpoints of solubility, dryness, price, and the like.

Further, the pressure-sensitive adhesive composition can be applied by a conventional method such as roll coating, die coating, gravure coating, comma coating, screen printing and the like.

The thickness of the pressure-sensitive adhesive layer in the pressure-sensitive adhesive film is usually 5 to 300 μm, preferably 5 to 50 μm, and particularly preferably 10 to 30 μm. If the pressure-sensitive adhesive layer is too thin, the adhesive properties tend to be difficult to stabilize, and if it is too thick, the entire pressure-sensitive adhesive film tends to be too thick, which tends to deteriorate usability.

As the adherend of the adhesive film, it is preferable to use a base material made of a heat-resistant material, for example, a metal plate such as aluminum, copper, iron, stainless steel, magnesium, nickel, titanium, or a metal foil; polyethylene terephthalate, Polyester resins such as polyethylene naphthalate, polybutylene terephthalate, polyethylene terephthalate / isophthalate copolymer, and ester acrylate; Polyfluoroethylene resin; polyimide and its derivatives; bisphenol type epoxy resin, epoxy resin composite material, alicyclic epoxy resin, epoxy novolak, biphenyl type epoxy resin, epoxy resin such as epoxy acrylate and the like can be mentioned.

The adhesive strength of the pressure-sensitive adhesive layer (or pressure-sensitive adhesive composition layer) of the pressure-sensitive adhesive film is appropriately adjusted depending on the material of the adherend and the like. When attached to a polyimide film or the like, the adhesive strength of the pressure-sensitive adhesive composition layer immediately after coating (before aging) is preferably 0.01 to 1.0 N / 25 mm, and particularly preferably 0.05 to. It is 0.5 N / 25 mm, more preferably 0.1 to 0.3 N / 25 mm.

The adhesive strength of the pressure-sensitive adhesive composition layer of the pressure-sensitive adhesive film after aging is preferably 0.01 to 1.0 N / 25 mm, particularly preferably 0.05 to 0.5 N / 25 mm, and even more preferably 0. .1 to 0.3 N / 25 mm.

Further, the adhesive strength of the pressure-sensitive adhesive layer of the pressure-sensitive adhesive film after heating is preferably 0.01 to 1.0 N / 25 mm, particularly preferably 0.05 to 0.5 N / 25 mm, and further preferably 0.1 to 0.1 to. It is 0.3N / 25mm.

An adhesive film such as a masking film obtained by using the adhesive composition of the present invention is less likely to be contaminated when peeled from an adherend even after being used under high temperature conditions, and can be peeled off with a small force. For masking applications that require heat resistance, such as circuit boards such as FPC boards and masking films for temporarily protecting the surface of transparent electrode layers, or for temporarily holding and reinforcing products during the manufacturing process. It can be used for general temporary fixing applications such as an adhesive film for a transparent electrode layer forming process for fixing and a tape for a semiconductor manufacturing process.
Further, the pressure-sensitive adhesive composition of the present invention has immediate curing property, and fine irregularities of the release film are not easily transferred to the pressure-sensitive adhesive surface of the pressure-sensitive adhesive layer, so that it is used as a protective film for displays such as flat panel displays and touch panels. Even when it is used as, it is possible to prevent deterioration of visibility due to unevenness.

As a method of using the masking film obtained by using the pressure-sensitive adhesive composition of the present invention, for example, the masking film is attached to the surface of an adherend and is usually 100 ° C. or higher (preferably 110 ° C. or higher, particularly preferably 120 ° C.). As described above, more preferably, the masking film is peeled off from the surface of the adherend after being subjected to the heating step (more preferably 130 ° C. or higher).

Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to the following examples as long as the gist of the present invention is not exceeded. In the example, "%" and "part" mean a weight standard.

<Manufacturing of acrylic resin (A) solution>
[Manufacturing Example 1: Acrylic Resin (A-1)]
40 parts of ethyl acetate was placed in a reactor equipped with a thermometer, a stirrer, a dropping funnel and a reflux cooler, and the temperature was raised while stirring. When the temperature reached about 80 ° C., butyl acrylate (BA) (a2) 64.85. Part, methyl methacrylate (MMA) (a2) 30.0 part, hydroxyethyl methacrylate (HEMA) (a1) 5.0 part, acrylic acid (AAc) (a3) 0.15 part, azobisisobutyronitrile (AIBN) ) 0.05 part and 5.0 part of ethyl acetate were mixed and dissolved, and the mixed solution was added dropwise over 2 hours. Further, during the polymerization, a mixed solution of 5.0 parts of ethyl acetate mixed with 0.025 part of AIBN and finally a mixed solution of 5.0 parts of ethyl acetate mixed with 0.05 part of AIBN are sequentially added to the above temperature. After ^refluxing at -1) was obtained.

[Manufacturing Example 2: Acrylic Resin (A-2)]
In a reactor equipped with a thermometer, agitator, a dropping funnel and a reflux condenser, 74.2 parts of ethyl acetate was charged, the temperature was raised while stirring, and when the temperature reached about 80 ° C., 91.85 parts of BA (a2), A mixed solution containing 7.0 parts of hydroxyethyl acrylate (HEA) (a1), 0.15 part of dimethylaminopropylacrylamide (DMAPAA) (a3), 0.06 part of AIBN, and 6.0 parts of ethyl acetate was mixed and dissolved for 2 hours. Dropped over. Further, during the polymerization, 0.3 part of ethyl acetate was mixed with 0.8 part of 4-hydroxybutyl acrylate (4HBA) (a1), and 0.3 part of ethyl acetate was mixed with 0.05 part of AIBN. The above-mentioned mixed solution, a mixed solution in which 0.2 part of 4HBA (a1) was mixed with 0.3 part of ethyl acetate, and finally a mixed solution in which 0.05 part of AIBN was mixed with 0.3 part of ethyl acetate. After refluxing at temperature for 7.5 hours, dilute with ethyl acetate and dilute by 42% to obtain an acrylic resin having 6.7 × ^10-2 mol of hydroxyl groups in 100 parts by weight (solid content equivalent). (A-2) was obtained.

Tables show the raw material composition, weight average molecular weight, dispersity (weight average molecular weight / number average molecular weight), and glass transition temperature of the acrylic resins (A-1) and (A-2) produced in Production Examples 1 and 2, respectively. Shown in 1.

<Isocyanate-based cross-linking agent (B)>
(B-1) "Coronate HX" manufactured by Tosoh Corporation
<Iron-based cross-linking catalyst (C)>
(C-1) "Narsem Ferric" manufactured by Nihon Kagaku Sangyo Co., Ltd. (molecular weight 353.17)
<Crosslink retarder (D)>
(D-1) "Acetylacetone" manufactured by Daicel Corporation

<Other metal catalysts>
"Bis (2,4-pentanedionato) zinc (II)" manufactured by Tokyo Chemical Industry Co., Ltd. (molecular weight 263.61)
"Narsem Titanium" manufactured by Nihon Kagaku Sangyo Co., Ltd. (Molecular weight 392.31)
"Nasem tin" manufactured by Nihon Kagaku Sangyo Co., Ltd. (molecular weight 431.15)
"Narsem Aluminum" manufactured by Nihon Kagaku Sangyo Co., Ltd. (Molecular weight 324.31)

<Example 1>
For 100 parts of solid content of acrylic resin (A-1), 7 parts of coronate HX (B-1), 1.0 part of Nasem ferric iron (C-1), and acetylacetone (D-1). A pressure-sensitive adhesive composition was prepared by blending 20 parts. The obtained pressure-sensitive adhesive composition is applied to a PET film (T60 Lumirror manufactured by Toray Industries, Inc., thickness 38 μm) as a base material so that the thickness after drying is about 20 μm, and then the pressure is 120 ° C. for 2 minutes. It was dried. Then, a release-treated PET film (PET-01-BU, thickness 38 μm, manufactured by Mitsui Chemicals Tocello Co., Ltd.) was attached and protected on the coated surface to prepare an adhesive film.

<Examples 2 and 3 and Comparative Examples 1 to 7>
A pressure-sensitive adhesive composition was prepared in the same manner as in Example 1 except that each component of the pressure-sensitive adhesive composition was blended in the proportions shown in Table 2, and a pressure-sensitive adhesive film was further prepared.

The following evaluations were performed using the obtained pressure-sensitive adhesive composition and pressure-sensitive adhesive film, and the results are summarized in Table 3.

<Immediate curing (surface unevenness)>
(Evaluation method)
After aging the adhesive film obtained above at 40 ° C. for 7 days, the release film of the adhesive film is peeled off, and platinum is vapor-deposited on the surface of the adhesive layer at 30 mA and 40 s with a JFC-1600 auto fine coater. (Thickness of the vapor-filmed layer is about 10 nm). Then, the surface of the pressure-sensitive adhesive layer on which platinum was vapor-deposited was observed with a microscope (VHX-900 (model number) manufactured by KEYENCE CORPORATION) and evaluated according to the following criteria.
(Evaluation criteria)
○ ・ ・ ・ Almost no surface irregularities were confirmed.
Δ: Some irregularities on the surface were confirmed.
×: Many irregularities on the surface were confirmed.

<Pot life>
(Evaluation method)
The pre-coating pressure-sensitive adhesive composition prepared above is placed in a sample bottle, stirred for 30 minutes, and then placed in a constant temperature water bath at 25 ° C., one hour after the start of the test (when the pressure-sensitive adhesive composition is prepared). The viscosity of the pressure-sensitive adhesive composition was measured at 25 ° C. × 1 minute using a B-type viscometer. After that, the mixture was further immersed in a constant temperature water bath at 25 ° C., and the viscosity 8 hours after the start of the test was measured at 25 ° C. × 1 minute using a B-type viscometer and evaluated according to the following criteria.
(Evaluation criteria)
◯: The viscosity after 8 hours was less than twice the viscosity after 1 hour.
Δ: The viscosity after 8 hours was more than twice or less than 3 times the viscosity after 1 hour.
X ... The viscosity after 8 hours was 3 times or more the viscosity after 1 hour.

<Adhesive strength>
・ Before heating (evaluation method)
After aging the adhesive film obtained above at 40 ° C. for 7 days, a 25 mm × 100 mm test piece was prepared, and after the release film was peeled off, HC (hard coat) -PET was applied to a stainless steel plate (SUS304BA plate). Pressurized and affixed to the HC surface of the adherend to which the PET surface of the film ("Tough Top THS" manufactured by Toray Industries, Inc.) was attached by two reciprocating 2 kg rubber rollers in an atmosphere of 23 ° C. and 50% relative humidity. It was left in the same atmosphere for 30 minutes.
Then, the peel strength (N / 25 mm) of 180 degrees was measured at a peeling speed of 0.3 m / min and evaluated according to the following criteria.
(Evaluation criteria)
○ ・ ・ ・ Less than 0.3N / 25mm △ ・ ・ ・ 0.3N / 25mm or more, less than 1.0N / 25mm × ・ ・ ・ 1.0N / 25mm or more

・ After heating (evaluation method)
After aging the adhesive film obtained above at 40 ° C. for 7 days, a 25 mm × 100 mm test piece was prepared, and after the release film was peeled off, HC (hard coat) -PET was applied to a stainless steel plate (SUS304BA plate). Pressurized and affixed to the HC surface of the adherend to which the PET surface of the film ("Tough Top THS" manufactured by Toray Industries, Inc.) was attached by two reciprocating 2 kg rubber rollers in an atmosphere of 23 ° C. and 50% relative humidity. It was left in the same atmosphere for 30 minutes.
Subsequently, it was exposed to an atmosphere of 150 ° C. for 1.0 hour, and then returned to 23 ° C. Further, after leaving it for 2 hours in an atmosphere of 23 ° C. and a relative humidity of 50%, the peeling strength (N / 25 mm) of 180 degrees was measured at a peeling speed of 0.3 m / min and evaluated according to the following criteria.
(Evaluation criteria)
○ ・ ・ ・ Less than 0.3N / 25mm △ ・ ・ ・ 0.3N / 25mm or more, less than 1.0N / 25mm × ・ ・ ・ 1.0N / 25mm or more

From the results shown in Tables 2 and 3, in Examples 1 to 3 according to the present invention, while having a sufficient pot life, the immediate curing property is excellent, and the increase in adhesive strength after use under high temperature conditions is small. It can be seen that it can be peeled off with a small force, and that contamination is unlikely to occur when it is peeled off from the adherend.
On the other hand, in Comparative Example 1, the product (X × Y) of the number of hydroxyl groups (X) of the hydroxyl group-containing acrylic resin and the number (Y) of the iron-based crosslinking catalyst (C) is less than the lower limit of the formula (1). Therefore, that is, because the amount of the iron-based crosslinking catalyst added was not sufficient for the hydroxyl value of the hydroxyl group-containing acrylic resin, many irregularities were confirmed on the surface of the pressure-sensitive adhesive layer.
Further, in Comparative Examples 2 to 5, since a metal catalyst other than the iron-based cross-linking catalyst (C) was used, the pot life was insufficient, the immediate curability was poor, and the catalyst was used under high temperature conditions. The effect as in the present invention could not be obtained, such as an increase in the adhesive strength afterwards.
Further, in Comparative Examples 6 and 7, since the iron-based cross-linking catalyst (C) was not used, the quick-curing property was inferior, and many irregularities were confirmed on the surface of the pressure-sensitive adhesive layer.

The pressure-sensitive adhesive composition of the present invention is a masking film for masking and fixing in a heating process included in a manufacturing process of a circuit substrate such as an FPC substrate and a touch panel-related member such as a transparent electrode layer, and an adhesive for a transparent electrode layer forming process. It can be suitably used for adhesive films such as films and tapes for semiconductor manufacturing processes.

Claims (9)

A pressure-sensitive adhesive composition containing a hydroxyl group-containing acrylic resin (A), an isocyanate-based cross-linking agent (B), an iron-based cross-linking catalyst (C), and a cross-linking retarder (D), wherein the following formula (1) and formula are used. Satisfy (2) and
The content of the hydroxyl group-containing monomer (a1) in the polymerization component of the hydroxyl group-containing acrylic resin (A) is 2 to 20 % by weight.
It is characterized by containing 3 to 20 parts by weight of the isocyanate-based crosslinking agent (B) and 0.1 to 50 parts by weight of the crosslinking retarder (D) with respect to 100 parts by weight of the hydroxyl group-containing acrylic resin (A). Adhesive composition.
1.2 × 10 ^-5 ≤ X × Y ≤ 1.0 × 10 ^-2 ... Equation (1)
X: Number of hydroxyl groups (mol) in 100 g of hydroxyl group-containing acrylic resin (A)
Y: The number (mol) of the iron-based cross-linking catalyst (C) with respect to 100 g of the hydroxyl group-containing acrylic resin (A), which is 0.00005 to 0.05 mol.
0.6 ≤ Z / X ≤ 2.0 ... Equation (2)
X: Number of hydroxyl groups (mol) in 100 g of hydroxyl group-containing acrylic resin (A)
Z: Number of isocyanate groups (mol) in the isocyanate-based cross-linking agent (B) with respect to 100 g of the hydroxyl group-containing acrylic resin (A). The pressure-sensitive adhesive composition according to claim 1 , wherein the pressure-sensitive adhesive composition satisfies the following formula (3).
1.0 × 10 ^-4 ≦ Y / Z ≦ 10 ・ ・ ・ Equation (3)
Y: The number (mol) of the iron-based cross-linking catalyst (C) with respect to 100 g of the hydroxyl group-containing acrylic resin (A), which is 0.00005 to 0.05 mol.
Z: Number of isocyanate groups (mol) in the isocyanate-based cross-linking agent (B) with respect to 100 g of the hydroxyl group-containing acrylic resin (A). The pressure-sensitive adhesive composition according to claim 1 or 2 , wherein the pressure-sensitive adhesive composition satisfies the following formula (4).
1.0 × 10 ^-6 ≤ Z × Y ≤ 5.0 × 10 ^-2 ... Equation (4)
Y: The number (mol) of the iron-based cross-linking catalyst (C) with respect to 100 g of the hydroxyl group-containing acrylic resin (A), which is 0.00005 to 0.05 mol.
Z: Number of isocyanate groups (mol) in the isocyanate-based cross-linking agent (B) with respect to 100 g of the hydroxyl group-containing acrylic resin (A). A pressure-sensitive adhesive comprising the pressure-sensitive adhesive composition according to any one of claims 1 to 3 cross-linked with an isocyanate-based cross-linking agent (B). A pressure-sensitive adhesive for a masking film, which comprises the pressure-sensitive adhesive according to claim 4 . A masking film comprising a pressure-sensitive adhesive layer made of the pressure-sensitive adhesive according to claim 4 on the film. A pressure-sensitive adhesive film for a transparent electrode layer forming step, which comprises a pressure-sensitive adhesive layer made of the pressure-sensitive adhesive according to claim 4 on the film. A tape for a semiconductor manufacturing process, which comprises a pressure-sensitive adhesive layer made of the pressure-sensitive adhesive according to claim 4 on a film. A method for using a masking film, which comprises attaching the masking film according to claim 6 to the surface of an adherend, subjecting the masking film to a heating step of 100 ° C. or higher, and then peeling the masking film from the surface of the adherend.