TW201809193A - Adhesive composition and adhesive sheet characterized in that the adhesive composition is adhered firmly to the adhered object during processing or handling at 60 DEG C, and can be easily peeled from the adhered object after treatment at 150 DEG C for 1 hour - Google Patents

Abstract

The present invention provides an adhesive composition and an adhesive sheet having an adhesive layer formed from the adhesive composition. The adhesive composition can be formed at room temperature, and can be used in a re-bonding operation, and the adhered object can be kept in a good condition. When the film is heated (e.g. 60 DEG C), the adhesive sheet is adhered firmly to the adhered object during processing or handling, and can be easily peeled from the adhered object after treatment at high temperature conditions (e.g. 150 DEG C, 1 hour). The adhesive sheet is formed by forming an adhesive layer, which is made of the following adhesive composition, on a substrate film. The adhesive composition is characterized by the following physical properties: an initial release force of 0.05 (Newton/25mm) at 23 DEG C or more, the peeling force is 0.05 (Newton/25mm) or more at a heating temperature of 60 DEG C, and after heating at 150 DEG C for 1 hour, the peeling force after heating at room temperature is 0.7 (Newton/25mm). The composition includes a resin component (A) in which two specific acrylic resins are blended in a specific ratio and a cross-linking agent (B).

Description

Adhesive composition and adhesive sheet

The present invention relates to an adhesive composition suitable for forming a re-peelable adhesive layer and an adhesive sheet having an adhesive layer composed of the adhesive composition.

In various processes for processing thin adherends such as an insulating substrate of a flexible printed circuit board (FPC), a reinforcing sheet is attached to the adherend to improve operability during work. Since the reinforcing sheet needs to be removed after the processing is completed, a re-peelable adhesive sheet is usually used as the reinforcing sheet. As a re-peelable adhesive sheet, there is known an adhesive sheet provided with an adhesive layer containing an adhesive polymer having a main chain and / or a side chain of a crystalline polymer on a substrate (Patent Document 1).

[Patent Document 1] Japanese Unexamined Patent Publication No. 9-251923

The adhesive sheet disclosed in Patent Document 1 has sufficient adhesive force during use, and at the same time is cooled to a temperature lower than normal temperature (23 ° C.), the adhesive force decreases, so that it can be easily peeled from the adherend. It also has the advantage that once the adhesion is reduced, it can be reused after peeling from the adherend.

However, the pressure-sensitive adhesive sheet disclosed in Patent Document 1 is under a heating condition (such as 60 ° C). Although it can be firmly adhered to the adherend during film processing or transportation (adhesion is sufficient during heating, and the peelability is good during heating), the initial peel force is small, so the adherend is maintained at normal temperature. Difficult (small initial adhesion. Poor initial peelability at normal temperature). In addition, after treatment under high temperature conditions (such as 150 ° C, 1 hour), when the adherend needs to be peeled from the adhesive layer, After the end of use and after it is no longer necessary, when peeling, there is a tendency that paste residue on the adherend tends to occur (poor peelability after heating).

Such a problem becomes a particularly serious problem when the adherend is a very thin film during processing.

It is therefore an object of the present invention to provide an adhesive composition and an adhesive sheet having an adhesive layer composed of the adhesive composition. The adhesive composition can be formed at normal temperature and can be re-adhered. The adherend is well maintained, and it can be firmly adhered to the adherend during film processing or transportation under heating conditions (such as 60 ° C), and it can be easily processed even under high temperature conditions (such as 150 ° C, 1 hour). An adhesive layer which is peeled off from an adherend.

In order to solve the above problems, the inventors of the present invention have made intensive studies to complete the present invention. That is, according to the present invention, it is possible to provide an adhesive composition having the structure shown below. Moreover, according to this invention, the adhesive sheet which provided the adhesive layer which consists of the adhesive composition which consists of the following in the base film can be provided.

The adhesive composition of the present invention is characterized by including a resin component (A) and a cross-linking agent (B) containing A1 and A2 shown below, and the compounding ratio (A1: A2) of A1 and A2 in A, 95: 5 to 65:35 in weight conversion to form The initial peeling force at 23 ° C (normal temperature) is 0.05 (Newton / 25mm (N / 25mm)) or more, and the peeling force at 60 ° C heating is 0.05 (Newton / 25mm) or more. Heating at 150 ° C After 1 hour, the pressure-sensitive adhesive layer having a peeling force of 0.7 (Newton / 25 mm) after heating at 23 ° C (normal temperature).

A1 (first acrylic resin) has a glass transition temperature (Tg1) and weight average molecular weight (Mw1), and A2 (second acrylic resin) has a glass transition temperature (Tg2) and weight average molecular weight (Mw2).

The relationship between Tg1 and Tg2 is Tg1 <Tg2 (Tg2 is higher than Tg1).

Mw1 and Mw2 are both above 100,000.

In the adhesive composition of the present invention, the mixing ratio (A1: A2) of A1 and A2 in A is preferably 90:10 to 80:20 in terms of weight.

In the adhesive composition of the present invention, Tg1 is -70 ° C to -25 ° C, Tg2 is -15 ° C to 30 ° C, and the difference between Tg2 and Tg1 (Tg2-Tg1) is preferably 10 ° C or more.

In the adhesive composition of the present invention, the ratio (Mw2 / Mw1) of Mw2 to Mw1 is preferably 0.5 to 2.

In the adhesive composition of this invention, the composition of A1 and A2 is not specifically limited. As an example, A2 may be formed of at least the copolymers of A11, A12, and A13 shown below. As an example, A1 may have a coefficient of at least a copolymer of A12 and A13 shown below.

A11: ethyl methacrylate or methyl methacrylate.

A12: (meth) acrylate having a functional group capable of reacting with B and an alkyl group having 2 to 8 carbon atoms.

A13: A monomer having an ethylenically unsaturated double bond (except for ethyl methacrylate and methyl methacrylate).

The adhesive composition of the present invention includes, in the resin component (A), a plurality of acrylic resins (at least A1 and A2) satisfying a specific relationship between a glass transition temperature (Tg) and a weight average molecular weight (Mw). The range includes a crosslinking agent (B). Therefore, the adhesive layer formed from the adhesive composition can have an initial peeling force of 0.05 (Newton / 25 mm) or higher at 23 ° C, and a peeling force of 0.05 (Newton / 25 mm) when heated at 60 ° C. ) Above, the peeling force at room temperature after heating at 150 ° C. for 1 hour is a physical property of 0.7 (Newton / 25 mm) or less.

Since A contains A1 and A2 having a specific relationship between Tg and Mw, it can be re-attached at normal temperature (23 ° C). Since the peeling force at the initial stage of 23 ° C. is 0.05 (Newton / 25 mm) or more, the adherend at room temperature is well maintained. In addition, since the peeling force during heating at 60 ° C is above 0.05 (Newton / 25 mm), it can be firmly adhered to the adherend during film processing or transportation during heating conditions (such as 60 ° C). The peeling force at room temperature after heating at 150 ° C. for 1 hour is 0.7 (Newton / 25 mm) or less. Therefore, the peeling force can be easily peeled from the adherend even after processing under these conditions.

That is, according to the present invention, it is possible to provide a re-adhesion operation at normal temperature, and the adherend can be maintained well. It can form a film that is firmly adhered to the adherend during processing or transportation of the film under heating conditions (such as 60 ° C). Adhesive group of an adhesive layer that can be easily peeled off from an adherend even after a high-temperature condition (for example, 150 ° C, 1 hour) Composition and an adhesive sheet having an adhesive layer composed of the adhesive composition.

The adhesive composition of the present invention is formed by achieving the following properties with respect to an adherend.

First, the initial peel force at 23 ° C. (the initial peel force (X1) at room temperature is 0.05 (Newton / 25 mm)) or more. If X1 is less than 0.05 (Newton / 25 mm), it may cause discomfort such as poor adhesion to the adherend and poor workability. Therefore, X1 is 0.05 (Newton / 25 mm) or more to prevent this. In this example, X1 is preferably 0.15 (Newton / 25 mm) or more. The upper limit of X1 is, for example, about 1 (Newton / 25 mm).

Second, the peeling force (peeling force (X2) during heating) at a temperature of 60 ° C. is 0.05 (Newton / 25 mm) or more. When X2 is less than 0.05 (Newton / 25mm), the adhesion to the adherend in the processing process is deteriorated, causing improper situations such as floating and peeling from the adherend. X2 is 0.05 (Newton / 25mm) or more To prevent this from happening. In this example, X2 is preferably 0.07 (Newton / 25 mm) or more. The upper limit of X2 is, for example, about 1 (Newton / 25 mm).

Third, the peeling force at room temperature after heating at 150 ° C (1 hour) (peeling force (X3) after heating is 0.7 (Newton / 25 mm) or less. If X3 exceeds 0.7 (Newton / 25 mm) or more, When the adhesive is peeled off from the adhesive, it is difficult to peel off, which may cause rolling or paste residue on the adherend, causing aggregation damage. X3 is 0.7 (Newton / 25 mm) or less to prevent this. In this example, X3 It is preferably 0.3 (Newton / 25 mm) or less. In addition, the lower limit of X3 is theoretically 0 (Newton / 25 mm).

The composition of the adhesive composition of the present invention that achieves the above-mentioned properties (physical properties) is not particularly limited, and may be, for example, an adhesive composition shown below.

The adhesive composition which concerns on an example contains a resin component (A) and a crosslinking agent (B) as an essential component.

As the resin component (A), at least two (two or more) acrylic resins are used. As two or more types of acrylic resins, it is desirable that it contains at least a component (A1) that maintains X1 (that is, maintains close contact with the adherend) and maintains X2 (that is, that keeps warming with the adherend) The component (A2) which can suppress the rise of X3 and make re-peelability at room temperature good at the same time.

In order to maintain X1 while maintaining X2 and suppress the increase of X3, as A1 and A2, both of the weight average molecular weights (Mw1 and Mw2) are appropriately high (Mw1 and Mw2 are more than 100,000), and as A2, those having a ratio of A1 Substances with a higher glass transition temperature (Tg1) (Tg1 <Tg2).

As A1 (the first acrylic resin), one having a weight average molecular weight (Mw1) of 100,000 or more and a glass transition temperature (Tg1) of -25 ° C or less is used. If Mw1 is less than 100,000, the peeling force after heating is likely to increase, which is not preferable. The reason why Tg1 is lower than -25 ° C is that it is considered that its adhesive force starts to work before and after it is 30 ° C (Tg + 30 ° C) higher than the glass transition temperature (Tg) of the adhesive. In addition, if Mw1 is too high, the compatibility with A2 deteriorates, it is difficult to adjust the initial peeling force at room temperature and the peeling force after heating, and if Tg1 is too low, the adjustment of the peeling force during heating becomes very difficult. difficult. Therefore, the ideal system as A1 satisfies the above conditions (Mw1 is above 100,000 and Tg1 is below -25 ° C), and Mw1 is below 1 million, preferably below 800,000 and / or Tg1 is above -70 ° C.

For example, A1 may be a (meth) acrylate (A12) having a functional group capable of reacting with a cross-linking agent (B) described later and an alkyl group having 2 to 8 carbon atoms, and an ethylenically unsaturated double bond It is composed of a copolymer of the monomer (A13) and the like.

A12 is a component for improving the cohesive force of the adhesive layer which consists of the adhesive composition of this invention, and does not generate a paste residue on an adherend. Examples of the functional group include a hydroxyl group, a carboxyl group, an amino group, an ethyl acetate, and an epoxy group. From the viewpoint of versatility, at least one selected from a hydroxyl group and an amino group is preferred. As A12 having such a functional group, for example, a monomer having a hydroxyl group is 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate , Diethylene glycol mono (meth) acrylate, N-hydroxymethacrylamide, allyl alcohol, p-hydroxystyrene, and the like. Examples of the monomer having a carboxyl group include β-carboxyethyl (meth) acrylate, (meth) acrylic acid, itaconic acid, crotonic acid, maleic acid, anhydrous maleic acid, and the like. Examples of the monomer having an amino group include aminomethyl (meth) acrylate, methylaminomethyl (meth) acrylate, methylaminoethyl (meth) acrylate, methylaminopropyl (meth) acrylate, and acrylamide Wait. Examples of the ethyl acetate-containing monomer include ethyl (meth) acrylate. Examples of the epoxy-group-containing monomer include glyceryl (meth) acrylate. Among them, the use of at least one selected from the group consisting of a monomer having a hydroxyl group, 2-hydroxyethyl methacrylate (HEMA) and 2-hydroxyethyl acrylate (HEA), can further improve the cohesive force of the adhesive layer. Can make the adherend not produce paste Residual.

A13 is a component that adjusts the peeling force when peeling from an adherend, and more easily adjusts the Tg of the entire adhesive layer composed of the adhesive composition of the present invention to an appropriate range. A13 includes (meth) acrylates (but not including ethyl methacrylate and methyl methacrylate) having an alkyl group having 2 to 8 carbon atoms, and examples thereof include ethyl acrylate (EA), methyl acrylate , Butyl (meth) acrylate (BA, BMA), 2-ethylhexyl (meth) acrylate (2-EHA, 2-EHMA), propyl (meth) acrylate, amyl (meth) acrylate Esters, hexyl (meth) acrylate, vinyl acetate (VA), vinyl propionate, vinyl ether, styrene, methacrylonitrile, and the like. Among them, by using at least one selected from the group consisting of ethyl acrylate, butyl (meth) acrylate, acrylonitrile (AN), methyl acrylate, 2-ethylhexyl (meth) acrylate, and vinyl acetate, It is easier to adjust the peeling force when peeling from the adherend, and at the same time, it is possible to more easily adjust the entire adhesive layer T9 to an appropriate range.

The preferable quality ratios of A12 and A13 which can constitute A1 are as follows. The lower limit of A12 is preferably 0.5% by weight or more, more preferably 1% by weight or more, and the upper limit is 10% by weight or less, and more preferably 5% by weight or less. A13 is preferably 30% by weight or more, more preferably 50% by weight or more, and 99.5% by weight or less, and more preferably 70% by weight or less as the upper limit.

As A2 (second acrylic resin), a substance having a weight average molecular weight (Mw2) of 100,000 or more and a glass transition temperature (Tg2) higher than Tg1 is used. When Mw2 is less than 100,000, the peeling force after heating is likely to increase. On the other hand, when a substance having a Tg2 of Tg1 or less (Tg2 ≦ Tg1) is used, the peeling force during heating is increased. Easily become inadequate. In addition, if Mw2 is too high, the compatibility with A1 deteriorates, and it becomes difficult to adjust the initial peeling force at room temperature and the peeling force after heating. If Tg2 is too high, it becomes difficult to adjust the peeling force at room temperature after heating. Therefore, as A2, the ideal system not only needs to meet the above conditions (Mw is more than 100,000, and Tg2 is higher than Tg1 (Tg2> Tg1)), but also Mw2 is less than 1 million, preferably less than 600,000, and / Or Tg is below 30 ° C.

For example, A2 may be composed of the above-mentioned A12 and a copolymer of A13 and A11 (ethyl methacrylate or methyl methacrylate) and the like.

A11 is used in order to make the thickness of the adhesive layer composed of the adhesive composition of the present invention not thin, and to stick to the adherend, and after heating at high temperature, no paste residue will be generated on the adherend. ingredient.

The weight ratios of A11, A12, and A13 which can constitute A2 are as follows. The lower limit of A11 is 20% by weight or more, preferably 30% by weight or more, more preferably 50% by weight, the upper limit is 80% by weight or less, preferably 70% by weight or less, and more preferably 65% by weight; A12 is the lower limit 0.5% by weight or more, preferably 1% by weight or more, with an upper limit of 10% by weight or less, preferably 5% by weight or less; A13 as a lower limit of 10% by weight or more, preferably 25% by weight or more, more preferably 30% by weight or more, the upper limit is 79.5% by weight or less, preferably 69% by weight or less, and more preferably 49% by weight or less.

In the present invention, the mixing ratio (A1: A2) of A1 and A2 is in the range of 95: 5 to 65:35 (preferably 90:10 to 80:20) in terms of weight conversion. When the mixing ratio of A2 is less than 95: 5, the peeling force is insufficient during heating, and the peeling force after heating is insufficient. It is easy to rise. On the other hand, if the blending ratio of A2 exceeds 65:35, the initial peeling force is low and the compatibility is liable to deteriorate. Therefore, it is not preferred.

In the present invention, it is better to select A1 and A2 so that the difference (Tg2-Tg1) between Tg2 and Tg1 becomes 10 ° C or more from the viewpoint of an increase in peeling force during heating. In addition, or at the same time, the ratio of Mw2 to Mw1 (Mw2 / Mw1) is 0.5 to 2, and the selection of A1 and A2 is preferable. By setting Mw2 / Mw1 to 0.5 or more, it is possible to more easily suppress an increase in peeling force after heating, and by setting Mw2 / Mw1 to 2 or less, it is possible to further improve compatibility. Therefore, it is possible to more easily obtain an adhesive layer having a desired performance.

The cross-linking agent (B) refers to a person that can cross-link A1 and / or A2 as described above to form a cross-linked polymer. Since the crosslinked polymer is formed, it is possible to easily exhibit sufficient adhesive force during film processing and excellent peelability after cooling.

As B, an isocyanate-based crosslinking agent, a metal chelate crosslinking agent, or an epoxy resin-based crosslinking agent is generally known. However, in the present invention, an isocyanate-based crosslinking agent is suitably used.

As the isocyanate-based crosslinking agent, conventionally known isocyanate-based crosslinking agents such as polyvalent isocyanate compounds and oligomers or prepolymers thereof can be suitably used. Examples of the polyvalent isocyanate compound include toluene-2,4-diisocyanate, toluene-2,6-diisocyanate, 1,3-bis (isocyanatemethyl) benzene, and 1,4-bis (isocyanate). (Meth) benzene, diphenylmethane-4,4'-diisocyanate, diphenylmethane-2,4'-diisocyanate, 3-methyldiphenylmethane diisocyanate, hexamethylene diisocyanate, iso Furone diisocyanate (IPDI), dicyclohexylmethane-4,4-diisocyanate, Dicyclohexylmethane-2,4-diisocyanate, lysine isocyanate, etc. Among them, alicyclic diisocyanates such as isophorone diisocyanate can be suitably used. This cross-linking agent is preferable in terms of being able to exert an excellent effect of obtaining re-peelability and heat resistance. The "crosslinking agent" may be used alone or in combination of two or more.

Since the blending ratio of B varies depending on the type of the crosslinking agent and the number of functional groups, it is not particularly limited, but it is preferably 1 to 8 weights relative to 100 parts by weight of A (for example, the total of A1 and A2). The range of parts is more preferably in the range of 1.5 to 6 parts by weight. By setting the blending ratio of B to 1 part by weight or more, it is possible to further suppress the increase in peeling force after heating, and it is possible to easily peel without leaving a paste. When it is set to 8 parts by weight or less, it is possible to further suppress The initial peeling strength at room temperature was low.

The adhesive composition of this example is prepared by dissolving or dispersing the above-mentioned (A) and (B), and further adding various conventionally-used additives in an arbitrary order as necessary. The mixing of the above raw materials can be performed using a mixer or a kneader such as a dissolver, a planetary mixer, a butterfly mixer, or the like.

Examples of the various additives include crosslinking accelerators, antioxidants, stabilizers, viscosity modifiers, adhesion-imparting resins, organic or inorganic fillers, and light absorbers that absorb ultraviolet rays and the like. Examples of the crosslinking accelerator include substances such as triethylamine, cobalt naphthenate, tin-based, zinc-based, titanium-based, and zirconium-based materials. When the cross-linking agent is an isocyanate-based cross-linking agent, it is particularly preferable to use zinc-, titanium-, and zirconium-based accelerators such as alkoxides, organic acid salts, and complexes, or stannous chloride, tetrabutyltin, tetrachloride Tin oxide, trimethyltin hydroxide, dimethyltin dichloride, dibutyl dilaurate Tin-based accelerators. When epoxy resin is used as a cross-linking agent, phenols containing three tertiary amines in one molecule, which are known under the trade name TMP-30, are particularly effective. Examples of the light absorber include a benzotriazole-based ultraviolet absorber or a triazine-based ultraviolet absorber.

Examples of the antioxidant include phenolic antioxidants. By containing an appropriate amount of an antioxidant in the adhesive composition of this example, when it is used as an adhesive layer, it is possible to further suppress an increase in peeling force after heating.

The amount of the antioxidant added is preferably 10 parts by weight or less, and more preferably 1 part by weight or less, based on 100 parts by weight of A (for example, the total of A1 and A2). In addition, since an effect obtained by adding an antioxidant in excess is also constant, it is preferable to set the range of the antioxidant to the above range from the viewpoint of economy. In addition, the excessively added antioxidant has a tendency to be separated from the adhesive chromatography with the passage of time, and may have a bad influence on the peeling force after heating. Therefore, the above range is preferably selected from this viewpoint.

The adhesive sheet of the present invention has an adhesive layer. This adhesive layer can be prepared by applying the above-mentioned adhesive composition to a base film, and drying it as needed.

The substrate film used in the adhesive sheet of the present invention is not particularly limited, and it may be a material having heat resistance, and examples thereof include polyethylene terephthalate and polyethylene terephthalate. In addition to polyester resins such as esters and polybutylene terephthalate, there are also polyimide resins, polycarbonate resins, polystyrene resins, polyimide resins, polyetherimide resins, and polyetherketones. Resins, polyphenylene sulfide resins, polyacrylate resins, polyester ether resins, polyimide resins, methyl methacrylate trees Films made of grease, fluororesin, and the like are particularly preferred in terms of economy and performance from polyethylene terephthalate. The base film may be used regardless of whether it is transparent or opaque, and may be colored to be colored.

As long as the thickness of the substrate film can protect the adherend and can support the thickness of the adherend with the necessary strength, a thickness conventionally used as a substrate film, such as a thickness of about 10 to 125 microns, can be used.

The surface of the base film may be surface-treated as necessary. Examples of the surface treatment at this time include (1) discharge treatment such as corona discharge treatment or glow discharge treatment, (2) plasma treatment, (3) flame treatment, (4) ozone treatment, and (5) ultraviolet treatment. And ionization active ray treatment such as electron beam and radiation treatment, (6) rough surface treatment such as sand cushion treatment and sanding treatment, (7) chemical treatment, (8) underlayer formation, etc. As the base layer, a urethane resin, a polyester resin, an acrylic resin, a polyester urethane resin, or the like can be used. The thickness of the underlayer is usually in the range of 0.01 to 1.5 microns.

The thickness of the adhesive layer is not particularly limited as long as it has the specified peeling properties (X1 to X3), and is generally about 2 to 50 microns, preferably about 3 to 20 microns. If it is thinner than this, X1 becomes smaller, and X2 cannot satisfy 0.05 (Newton / 25 mm) or more. As a result, the adherend may float or peel off in the process. If it exceeds this range, X1 becomes higher and X3 becomes larger, causing re-peeling obstacles, which is not preferable.

In order to facilitate the operation of the pressure-sensitive adhesive sheet of the present invention, it is preferable to stick a peelable separator on the surface of the pressure-sensitive adhesive layer until it is adhered to the adherend. Any known separator can be used, and its thickness is preferably about 15 to 200 microns.

The adhesive sheet of the present invention can be used in a wide range of applications, such as forming a fine pattern on a substrate (fine pattern is a fine pattern substrate that is arranged on a substrate).

As the fine pattern, for example, a decorative pattern with a decorative film or a wiring pattern for transmitting a signal can be exemplified. The wiring pattern substrate formed by wiring patterns arranged on a substrate can be used in various electronic accessories such as a touch screen, a liquid crystal display, an organic EL display, a solar cell module, a printed wiring board, and the like. The decorative pattern substrate formed by placing the decorative pattern on the substrate can be used, for example, in electronic equipment, vehicle interiors, exteriors, and the like.

Therefore, the adherend mentioned above in this example refers to a laminated body that becomes the basis for the formation of the above-mentioned fine pattern (manufacturing of a substrate with a fine pattern). Such a laminated body can be exemplified by a laminated body provided with a pattern forming layer (a layer that becomes the basis of a fine pattern, such as a wiring pattern forming layer or a decorative pattern forming layer) and a photosensitive resin layer on a substrate. A photosensitive film of a photosensitive layer, a laminated body of a base material having a pattern forming layer formed on the entire surface of one surface, and a dry film photoresist corresponding to the photosensitive resin layer. In this example, a pattern forming layer is provided on a substrate, and a photosensitive resin layer is provided on the pattern forming layer.

(Example)

The following specifically describes the experimental examples (including examples and comparative examples) of the present invention, but the present invention is not limited to these examples.

1. Production of adhesive sheet (Experimental Example 1-14)

An adhesive layer prepared by uniformly mixing and dissolving the following constituent components in accordance with the solid content ratio (weight conversion) described in Table 2 on one surface of a heat-resistant base film (50 micron, polyethylene terephthalate) The coating liquids a to p were formed by applying a baker-type applicator so that the thickness of the dried film became about 7 μm. In addition, all the solid components in each coating liquid were adjusted to 30% by weight. Then, an adhesive layer was formed by drying at 160 ° C. for 1 minute, and then a 25 μm-thick PET film (isolation film) with a silicone release treatment was applied to the surface of the adhesive layer. And cured at room temperature to obtain the adhesive sheet of each example.

的 Constituent components of the coating liquids a to p forming the adhesive layer≫

． First acrylic resin (A1, A1 '): the ratio of the type / composition described in Table 1 to the solid content described in Table 2

． Second acrylic resin (A2, A2 '): ratio of the type / composition described in Table 1 to the solid content described in Table 2

． Crosslinking agent (B): solid content ratios shown in Table 2

(TAKENATE D-140N, alicyclic diisocyanate, manufactured by Mitsui Chemicals)

． Solvent (mixed solvent of toluene and methyl isobutyl ketone): appropriate amount

Table 1

2. Evaluation

About the obtained adhesive sheet, the physical property of the adhesive layer was measured and evaluated by the following method.

(2-1) Initial peeling force X1 (Newton / 25mm)

Prepare an experimental example of 2 cm x 10 cm at 23 ° C and 65% RH The obtained adhesive sheet was peeled off from the release film, and a round trip was performed at a speed of 300 mm / min (mm / min) using a 2 kg rubber roller to adhere the exposed adhesive layer to the PET film (50 μm, exposed Miqin T-60 (manufactured by Toray Co., Ltd.). Next, the test piece was left under the same conditions (23 ° C, 65% RH) for 20 minutes, and the tensile strength of the PET film was measured in a 180-degree direction using a tensile tester at a tensile speed of 300 mm / min under the same conditions. The peel force at the time of opening (initial peel force X1) (Table 2) was evaluated by the following criteria, and the results are shown in Table 3.

(AA): 0.15 (Newton / 25 mm) or more (excellent adhesion)

(A): 0.05 (Newton / 25 mm) or more and less than 0.15 (Newton / 25 mm) (good adhesion).

(B): less than 0.05 (Newton / 25 mm) (poor adhesion).

(2-2) Peeling force during heating X2 (Newton / 25mm)

In the same manner as in (2-1) above, the PET film was adhered to the adhesive sheet, and the test piece after being left for 20 minutes was measured in a 60 ° C environment in the same manner as in (2-1) above. The peeling force X2 at the time of heating (Table 2) was evaluated according to the following criteria. The results are shown in Table 3.

(AA): 0.07 (Newton / 25 mm) or more (excellent adhesion).

(A): 0.05 (Newton / 25 mm) or more and less than 0.07 (Newton / 25 mm) (good adhesion).

(B): Less than 0.05 (Newton / 25 mm) (poor adhesion).

(2-3) Peeling force after heating X3 (Newton / 25mm)

As in (2-1) above, the PET film and the adhesive sheet were adhered, and The test piece after 20 minutes was heated in an environment of 150 ° C for 1 hour, and then cooled under the conditions of 23 ° C and 65RH%, and then the peeling force (peeling force X3 after heating) was measured in the same manner as in (2-1) above. Table 2) was evaluated according to the following criteria, and the results are shown in Table 3.

(AA): 0.3 (Newton / 25 mm) or less (excellent peelability).

(A): More than 0.3 (Newton / 25 mm), 0.7 (Newton / 25 mm) or less (good peelability).

(B): More than 0.7 (Newton / 25 mm) (poor peelability).

(2-4) Compatibility of acrylic resin (A1) and acrylic resin (A2) of coating liquid

The compatibility of the first acrylic resin (A1) and the second acrylic resin (A2) in the coating liquid forming the adhesive layer was evaluated by visually observing the state of the surface of the coating liquid and the adhesive layer. . The results are shown in Table 3.

(AA): The coating liquid is not white and turbid, is transparent, and has no whitening on the surface of the adhesive layer (excellent compatibility).

(A): The coating solution has only a small amount of white turbidity, and there is no whitening on the surface of the adhesive layer (good compatibility).

(B): The coating liquid is white and turbid, and there is whitening (poor compatibility) on the surface of the adhesive layer.

table 3

3. Inspection

Experimental examples 2 to 4, 4a, 4b, 5, 6, 8, 9, 12, 13, 14, and substances with Mw (Mw1, Mw2) all above 100,000 (A1a, A2a, A2b, A2c) were used as A1 And A2, and the substances (A2a, A2b, A2c) used as A2 are substances having a glass transition temperature Tg2 higher than the glass transition temperature Tg1 of A1, and also have a compound ratio (A1) satisfying A1 and A2 : A2) An adhesive sheet (Table 1 and Table 2) of an adhesive layer composed of an adhesive composition having a weight conversion of 95: 5 to 65:35. These adhesive sheets have sufficient initial adhesion and good adhesion (X1 is A or AA). In addition, it has sufficient adhesion when heating (X2 is A or AA), and no paste remains after heat treatment, and the peelability is good (X3 is A or AA). In addition, the compatibility of A1 and A2 of the coating liquid is good (the compatibility is A or AA) (table 3).

In particular, Experimental Examples 3, 4, and 5, where Mw1 and Mw2 are both above 100,000, and Mw1 is below 800,000, and Mw2 is below 600,000. In order to satisfy the mixing ratio of A1 and A2 (A1: A2), For substances in the range of 90:10 to 80:20, X1, X2, X3 and compatibility are all excellent results.

On the other hand, Experimental Example 1 contained a substance (A1a) belonging to A1 as an adhesive composition, and did not contain a substance belonging to A2 (Table 2). As a result, compared with Experimental Examples 2 to 4, 4a, 4b, 5, 6, 8, 9, 12, 13, and 14, X2 was low and X3 was high (Table 3). From this, it can be seen that the adhesive composition must contain substances belonging to A1 and A2 as A.

In addition, the mixing ratio (A1: A2) of A1 and A2 in Experimental Example 7 was 64:36 (not satisfying 95: 5 to 65:35) in terms of weight. As the adhesive composition, it was an adhesive sheet with more A2 ( Table 2). As a result, compared with Experimental Examples 2 to 4, 4a, 4b, 5, 6, 8, 9, 12, 13, and 14, X1 became low. In addition, the compatibility of the coating liquids A1 and A2 was poor (Table 3). From this, it can be seen that the adhesive composition must have a suitable ratio of A1 and A2.

In addition, Experimental Example 10 contained A1 as an adhesive composition, and did not contain a component belonging to A2. Instead, it contained a component (A2d) having an Mw2 of 24,000 (less than 100,000) (Tables 1 and 2). The results are compared with Experimental Examples 2 to 4, 4a, 4b, 5, 6, 8, 9, 12, 13, 14, and X3 is high (Table 3). From this, it can be seen that as the adhesive composition A, not only A1, but also Mw2 belonging to A2 must be 100,000 or more.

In addition, in Example 11, although A1 was contained as an adhesive composition, it was not Contains a component belonging to A2, instead of containing A11, and uses a component (A1b) having an Mw1 of 27,000 (less than 100,000) (Tables 1 and 2). As a result, compared with Examples 2 to 4, 4a, 4b, 5, 6, 8, 9, 12, 13, 14, X3 was very high (Table 3). From this, it can be seen that A in the adhesive composition must contain not only A1, but also those belonging to A2, that is, those containing A11, and those having Mw of 100,000 or more.

Next, the effect when antioxidant was added was investigated as follows.

1. Production of adhesive sheet (Experimental Examples 15 to 18)

As a coating liquid for forming an adhesive layer, an adhesive sheet was produced in the same manner as in Experimental Examples 1 to 14 except that the following components were added with an antioxidant.

"Components for Forming Adhesive Layer Coating Liquids q to t"

． The first acrylic resin (A1, A1 '): the type / composition described in Table 1 and the solid content ratio described in Table 4

． Second acrylic resin (A2, A2 '): the type / composition table shown in Table 1 and the solid content ratio shown in Table 4

． Crosslinking agent (B): solid content ratios shown in Table 4 (TAKENATE D-140N, alicyclic diisocyanate, manufactured by Mitsui Chemicals)

． Antioxidants: solid content ratios shown in Table 4 (IRGANOX3114, phenolic antioxidants, BASF)

． Solvent (mixed solvent of toluene and methyl isobutyl ketone): appropriate amount

2. Evaluation

For the adhesive sheet obtained in each example, in the same manner as described above, the initial peel force X1 (Newton / 25 mm), the peel force during heating (Newton / 25 mm), and the peel force X3 after heating (Newton / 25 mm) were measured. . The results are shown in Table 4. In addition, the results of Experimental Example 4 are also shown in Table 4 for comparison.

3. Inspection

In any of Experimental Examples 15 to 18, X1 is 0.15 (Newton / 25 mm) or more, X2 is 0.07 (Newton / 25 mm) or more, and X3 is 0.3 (Newton / 25 mm) or less.

Experimental Examples 15 to 17 Compared with Experimental Example 4, the initial peeling force X1 (Newton / 25mm) and the peeling force X2 (Newton / 25mm) during heating are the same, and the peeling force X3 (Newton / 25mm) after heating is more excellent. .

Compared with Experimental Example 4, Experimental Example 18 has an excellent initial peeling force X1 (Newton / 25 mm) and a peeling force X2 (Newton / 25 mm) during heating. The peeling force X3 (Newton / 25 mm) after heating is approximately the same.

From the above, it can be seen that by adding an antioxidant, one of the initial peeling force X1 (Newton / 25 mm), the peeling force X2 (Newton / 25 mm) during heating, and the peeling force X3 (Newton / 25 mm) after heating can be achieved Better. In particular, by increasing the amount of the antioxidant to 10 parts by weight or less with respect to 100 parts by weight of A, the initial peeling force X1 and the peeling force X2 during heating can be maintained while suppressing the increase in the peeling force X3 after heating. .

Claims (10)

An adhesive composition comprising a resin component (A) and a crosslinking agent (B), wherein the resin component (A) contains a first acrylic resin (A1) and a second acrylic resin (A2), and The second acrylic resin (A2) has a glass transition temperature (Tg2) higher than the glass transition temperature (Tg1) of the A1, and the weight average molecular weight (Mw1) of the A1 and the weight average molecular weight (Mw2) of the A2 are both Above 100,000; the mixing ratio (A1: A2) of A1 and A2 in the aforementioned A is 95: 5 to 65:35 in terms of weight, and is used to form an initial peeling force at 23 ° C of 0.05 (Newton / 25mm (N / 25mm)) or more, peeling force when heating at 60 ° C is 0.05 (Newton / 25mm) or more, and peeling force at 23 ° C after heating at 150 ° C for 1 hour is 0.7 (Newton / 25mm) Mm). The adhesive composition according to item 1 of the scope of patent application, wherein Tg1 is -70 to -25 ° C, Tg2 is -15 to 30 ° C, and the difference between Tg2 and Tg1 (Tg2-Tg1) is 10 ° C or more. The adhesive composition according to item 1 of the scope of patent application, wherein the ratio (Mw2 / Mw1) of Mw2 to Mw1 is 0.5 to 2. The adhesive composition according to item 2 of the scope of patent application, wherein the ratio (Mw2 / Mw1) of Mw2 to Mw1 is 0.5 to 2. The adhesive composition according to item 1 of the scope of patent application, wherein A2 is composed of at least ethyl methacrylate or methyl methacrylate (A11), has a functional group capable of reacting with B, and has a carbon number of 2 to 8 alkyl (meth) acrylates (A12) and monomers (A13) having ethylenically unsaturated double bonds The copolymer is formed, and wherein A13 is not ethyl methacrylate or methyl methacrylate. The adhesive composition according to item 5 of the scope of patent application, wherein A1 is formed from at least a copolymer of A12 and A13. The adhesive composition according to item 1 of the patent application scope further comprises an antioxidant. The adhesive composition according to item 2 of the patent application scope, further comprising an antioxidant The adhesive composition according to item 3 of the patent application scope, further comprising an antioxidant. An adhesive sheet which has an adhesive layer which consists of the adhesive composition as described in any one of Claims 1-9 in the patent application range on a base film.