TWI589659B - Adhesive, adhesive sheet using the same and method for producing adhesive sheet - Google Patents

Description

Adhesive, adhesive sheet and adhesive sheet obtained by using the same

The present invention relates to an adhesive which can be used for bonding various substrates mainly composed of a plastic substrate or a metal substrate.

In recent years, various industrial products mainly composed of automobiles or home electric appliances have been produced, for example, foams such as polyurethane foams or acrylonitrile-butadiene-styrene resins (ABS resins). A component having a characteristic material or shape such as a substrate having a difficult-to-adhere substrate or a substrate having a complicated shape such as an R portion or an inverse R portion, in particular, in recent years, with the high functionality of industrial products, a complicated shape portion is often used. Parts.

Adhesives have been used for the bonding of the above-mentioned components. However, since the surface of the curved portion having the R portion or the like of the base material has a large returning force, even if the adhesive sheet is adhered to the curved surface portion, the adhesive is caused. The peeling of the end portion of the sheet with time leads to a decrease in the yield of the industrial product.

In order to prevent the adhesive which is caused by the peeling force of the aforementioned substrate, the adhesive composition is, for example, an adhesive composition which must contain a polymer for an adhesive and a crosslinking agent. The polymer for the adhesive is composed of a (meth) acrylate having a carbon number of 2 to 18, a nitrogen atom-containing monomer, a functional group-containing monomer as an essential component, and a monomer having no carboxyl group-containing monomer. The mixture (I) is obtained by dividing the monomer mixture (I) into a monomer component A and a monomer component B having different monomer compositions, and any one of the monomer components A and B contains the above functional group. The monomer for the adhesive is first polymerized by feeding the monomer component A to the reactor, and after the polymerization of the monomer component A starts, and the polymerization rate of the monomer A component does not exceed 50%, the polymerization starts. The monomer component B is supplied to the reactor and obtained by polymerization; the crosslinking agent is a compound having two or more functional groups in the molecule, and the functional group can react with the functional group of the functional group-containing monomer. (For example, refer to Patent Document 1.).

However, since the above-mentioned adhesive composition still has a situation in which the adhesive sheet is peeled off due to the returning force of the substrate, there is no case where it is suitable for the curved portion of the substrate or the like. Further, the above-mentioned adhesive composition is easily peeled off due to the load, and since the above-mentioned adhesive composition is a so-called re-peeling type adhesive, it does not have a strong adhesive force to the planar portion of the substrate. In addition, in recent years, it is required to have an excellent adhesive force of the adhesive, and at the same time, it is possible to prevent the so-called general adhesive retention force characteristic in which the lateral displacement between the substrates is likely to occur at the initial stage of bonding of the two or more substrates. The adhesive does not have good adhesion retention.

As described above, although there is an adhesive which is excellent in adhesion between the curved surface portion of the substrate and excellent adhesion retention which prevents lateral displacement of the substrate, in fact, it has not been seen. To.

[Previous Technical Literature] [Patent Literature]

[Patent Document 1] JP-A-2003-277709

An object of the present invention is to provide an adhesive which does not have any shape such as a flat portion or a curved portion such as an R portion or an inverse R portion, even if the base material to which the adhesive sheet is adhered is used. When the substrate is pressed back, the adhesion of the adhesive sheet or the like is excellent, and the adhesion is excellent.

In order to solve the above problems, the inventors of the present invention conducted the review based on the composition described in Patent Document 1. Specifically, an adhesive obtained by using two or more different specific acrylic polymers in combination is examined, and various types or combinations of functional groups introduced into the acrylic polymer are reviewed.

As a result, it has been found that when a high molecular weight acrylic polymer and a low molecular weight acrylic polymer are used in combination, only the nitrogen atom-containing group is introduced to the high molecular weight acrylic polymer, the problem of the present invention can be solved.

That is, the present invention relates to an adhesive comprising: an acrylic polymer (A) having a nitrogen atom group having a weight average molecular weight of 1,000 to 50,000, and an acrylic polymer having a weight average molecular weight of 500,000 or more (B) And the solvent (C), the acrylic polymer (A) does not have a carboxyl group, and the acrylic polymer (B) does not have a carboxyl group and a nitrogen-containing atomic group; and an adhesive sheet using the same.

Since the adhesive of the present invention is less likely to cause peeling of the adhesive sheet over time due to the returning force of the substrate, the substrate and the adhesive sheet can be strongly adhered to each other, and have an excellent degree of preventing lateral displacement of the substrate and the adhesive sheet. Since it has an adhesive retention force, it is suitable for use in the bonding of a base material having a complicated shape portion such as an R portion.

Further, since the adhesive of the present invention can prevent corrosion of the metal substrate, it can be used for the production of industrial products such as automobiles or home electric appliances.

<Embodiment for use in the present invention>

The adhesive of the present invention comprises: an acrylic polymer (A) having a nitrogen atom group having a weight average molecular weight of 1,000 to 50,000, an acrylic polymer (B) having a weight average molecular weight of 500,000 or more, a solvent (C), and a visual field. Other additives required, the acrylic polymer (A) does not have a carboxyl group, and the acrylic polymer (B) does not have a carboxyl group and a nitrogen atom-containing group, and the acrylic polymer (A) or the acrylic polymer (B) or the like is dissolved. Or dispersed in the aforementioned solvent (C).

The adhesive of the present invention is important in imparting an excellent adhesion (curved surface adhesion) to the extent that the adhesive sheet is peeled off from the curved portion such as the R portion or the reverse R portion, and it is important to use a relatively low molecular weight acrylic polymer (A). And a high molecular weight acrylic polymer (B) is used in combination. In particular, the acrylic polymer (A) and the acrylic polymer (B) preferably have a mass ratio [(A)/(B)] = 1/100 to 50/100, preferably 5/100~. In the range of 30/100, it is preferable to have an adhesive having a degree of adhesion preventing from peeling off from the flat portion and the curved portion of the substrate, and an adhesive layer capable of forming an adhesive layer having good transparency, and more preferably 5/100. Range of ~15/100.

From the viewpoint of imparting excellent adhesion to the curved portion of the substrate and improving the transparency of the obtained adhesive, the acrylic polymer (A) is important in that a weight average molecular weight of 1,000 to 50,000 is used. Among them, it is preferred to use a weight average molecular weight of 5,000 to 30,000, more preferably a weight average molecular weight of 10,000 to 25,000.

Further, in the acrylic polymer (A), it is necessary to promote the crosslinking reaction of the crosslinking agent and the acrylic polymer to be described later, and to prevent the peeling of the adhesive sheet on the curved surface of the substrate having a large backing force. It has a nitrogen atom-containing group. Specifically, the acrylic polymer (A) preferably has a structure derived from a nitrogen atom-containing (meth) acrylate (a1). For example, an adhesive containing an acrylic polymer obtained by polymerizing an alkyl acrylate having no nitrogen atom in place of the nitrogen atom-containing (meth) acrylate (a1) cannot sufficiently increase the cohesive force, and as a result, It is impossible to impart strong adhesion to any of the planar portion or the curved portion of the substrate.

The (meth) acrylate (a1) structure derived from the above nitrogen atom can be used as the (meth)acrylic monomer produced by the above acrylic polymer (A) by using a nitrogen atom-containing (meth) group. The acrylate (a1) is introduced into the acrylic polymer (A).

As the nitrogen atom-containing (meth) acrylate (a1), for example, N-vinylpyrrolidone, N-vinylcaprolactam, or acrylonitrile can be used. Porphyrin, (meth)acrylonitrile, etc., or (meth)acrylamide, N,N-dimethyl(meth)acrylamide, N,N-diethyl(meth)acrylamide, N , N-dibutyl (meth) acrylamide, N-methylol acrylamide, N-methoxymethyl acrylamide, N-ethoxyethyl acrylamide, N- (n-butyl) Oxymethyl) acrylamide, dimethylaminopropyl methacrylamide, tertiary butyl acrylamide, aminoethyl (meth) acrylate, (meth) acrylate - N, N - dimethyl An amine ethyl ester, N-N-dimethylaminopropyl (meth)acrylate, butylaminoethyl methacrylate, etc., wherein an amino group-containing (meth) acrylate is preferably used; It is preferable to use (meth)acrylic acid in order to improve the polymerization stability in the production of the acrylic polymer (A) and to provide an adhesive capable of preventing the degree of adhesion on the flat portion or the curved portion of the substrate over time. -N,N-dimethylamine ethyl ester.

When the base material is bonded by using the adhesive of the present invention, excellent adhesion holding force to the extent that lateral displacement between the substrates can be prevented is not impaired, and the curved portion or the flat portion from the substrate is imparted. From the viewpoint of excellent adhesion against peeling prevention, the nitrogen atom-containing (methyl) is the total amount of the (meth)acrylic monomer used for the production of the acrylic polymer (A). The acrylate (a1) is preferably used in the range of 2 to 30% by mass, more preferably 2 to 15% by mass, most preferably 2 to 10% by mass.

Further, in the acrylic polymer (A), the excellent adhesion of the adhesive of the present invention is maintained, and when the adhesive is used on a metal substrate, from the viewpoint of preventing corrosion of the surface of the metal substrate, Use those who do not have a carboxyl group. Further, from the viewpoint of preventing the adhesive of the present invention from being viscous and viscous (gelling) without lowering the productivity of the adhesive sheet, it is also necessary to use a carboxyl group. Specifically, as the acrylic polymer (A), a (meth)acrylic acid ester containing no carboxyl group-containing (meth)acrylic acid monomer and containing a nitrogen atom-containing (meth)acrylate such as the aforementioned dimethylaminoethyl acrylate or the like (a1) It is preferred that the (meth)acrylic monomer is polymerized.

Further, as for the acrylic polymer (A), it is preferred to use a glass transition temperature of 0 to 160 ° C in terms of further improving the adhesion. For example, the nitrogen atom-containing (meth) acrylate (a1) such as the aforementioned dimethylaminoethyl acrylate or the like, and the (meth)acrylic monomer which can form a homopolymer having a glass transition temperature of 0 to 180 ° C (a2) In combination, an acrylic polymer having a glass transition temperature of the aforementioned range can be obtained by using the polymerization.

As the (meth)acrylic monomer (a2), for example, methyl acrylate, butyl acrylate, cyclohexyl acrylate, or acrylic acid can be used. Ester, methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, butyl methacrylate, butyl methacrylate , n-hexyl methacrylate, cyclohexyl methacrylate, n-octyl methacrylate, isooctyl methacrylate, 2-ethylhexyl methacrylate, etc., wherein an aliphatic ring-containing ring is preferably used. a (meth) acrylate having a structure; further improving agglutination using cyclohexyl (meth) acrylate in terms of an adhesive having an adhesive strength capable of preventing peeling from a flat portion or a curved portion of a substrate The power is better.

As the above-mentioned (meth)acrylic acid, the acrylic polymer (A) is provided with an adhesive having an adhesive strength which can be prevented from peeling off from the flat portion or the curved portion of the substrate. 2 to 10% by mass of a nitrogen atom-containing (meth) acrylate (a1) such as dimethylamine ethyl ester, and a (meth)acrylic acid which can form a homopolymer having a glass transition temperature of 0 to 180 ° C as described above. The (a2) 90 to 98% by mass of the (meth)acrylic monomer mixture is obtained by polymerization, and it is preferred to further increase the cohesive force.

In the production of the aforementioned acrylic polymer (A), in addition to the aforementioned nitrogen atom-containing (meth) acrylate (a1) and (meth)acrylic monomer (a2), other (methyl) groups may be combined as needed. Acrylic monomer (a3) is used.

As the other (meth)acrylic monomer (a3), for example, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, n-butyl acrylate, n-hexyl acrylate, isooctyl acrylate may be used. , 2-ethylhexyl acrylate, n-octyl acrylate.

As the other (meth)acrylic monomer (a3), for example, hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, hydroxybutyl (meth)acrylate, or (meth)acrylic acid hydroxy group can be used. a hydroxy group of hexyl ester, hydroxyoctyl (meth) acrylate, hydroxy decyl (meth) acrylate, hydroxylauryl (meth) acrylate, (4-hydroxymethylcyclohexyl) methacrylate, etc. Methyl) acrylate.

The acrylic polymer (A) can be produced by polymerizing a (meth)acrylic monomer mixture, the polymerization (meth)acrylic monomer mixture comprising the nitrogen atom-containing (meth)acrylate (a1), and The aforementioned (meth)acrylic monomer (a2) or the aforementioned other (meth)acrylic monomer (a3) may be optionally used.

Specifically, the (meth)acrylic acid monomer, the polymerization initiator, and the organic solvent are preferably mixed and stirred at a temperature of 40 to 120 ° C to carry out radical polymerization, and the acrylic polymer (A) and the acrylic polymer The organic solvent mixture is preferably an organic solvent solution in which the aforementioned acrylic polymer (A) can be produced.

As the polymerization initiator, for example, a peroxide such as hydrogen peroxide, potassium persulfate, sodium persulfate or ammonium persulfate, or 2,2'-azobis-(2-aminodipropane) II can be used. Hydrochloride, 2,2'-azobis-(N,N'-dimethyleneisobutylphosphonium) dihydrochloride, 2,2'-azobis{2-methyl-N-[ An azo compound such as 1,1-bis(hydroxymethyl)-2-hydroxyethyl]propanamine}. The amount of the polymerization initiator to be used is preferably 0.01 to 5 parts by mass based on 100 parts by mass of the total of the acrylic monomers.

Further, as the above-mentioned organic solvent which can be used for the production of the aforementioned acrylic polymer (A), it can be used as the solvent (C) described below, for example, toluene, ethyl acetate or butyl acetate can be used. , methyl ethyl ketone, hexane, acetone, cyclohexanone, 3-pentanone, acetonitrile, propionitrile, isobutyronitrile, valeronitrile, dimethyl hydrazine, dimethylformamide, and the like.

The above acrylic polymer (A) is preferably contained in an amount of from 1 to 20% by mass based on the total amount of the adhesive of the present invention.

Next, the acrylic polymer (B) used in the present invention will be described.

As the acrylic polymer (B) used in the present invention, unlike the acrylic polymer (A), it is important to use a high molecular weight of up to 500,000 or more by weight average molecular weight. The use of an adhesive which replaces the acrylic polymer (B), for example, an acrylic polymer having a weight average molecular weight of, for example, about 400,000, may cause a temporal peeling of a curved portion or a flat portion of the substrate. Further, since the above-mentioned adhesive cannot maintain a good adhesive holding force, the force in parallel lateral direction on the surface of the substrate is shifted. As the acrylic polymer (B), a weight average molecular weight in the range of from 50 to 1.4 million is preferably used.

In the acrylic polymer (B), from the viewpoint of having excellent adhesion to the flat portion or the curved portion of the substrate and adhesion retention, it is necessary to have no nitrogen atom-containing base.

Further, in the case where the acrylic polymer (B) maintains excellent adhesion and the adhesive of the present invention is used for a metal substrate, it has no carboxyl group from the viewpoint of preventing corrosion of the surface of the metal substrate. It is better. Further, from the viewpoint of preventing the adhesive of the present invention from being viscous and viscous (gelling) without lowering the productivity of the adhesive sheet, it is also necessary to use a carboxyl group. Specifically, as the acrylic polymer (B), a (meth)acrylic monomer which does not contain a carboxyl group-containing (meth)acrylic monomer and a nitrogen atom-containing (meth)acrylic monomer is used. Aggregated. When the (meth)acrylic acid monomer having a nitrogen atom group is used for the production of the above acrylic polymer (B), it hinders the high molecular weight of the acrylic polymer (B), and may hinder both excellent adhesion and adhesion retention. In the case of force, it is better not to use it.

Examples of the carboxyl group-containing (meth)acrylic monomer such as (meth)acrylic acid, and the nitrogen atom-containing (meth)acrylic monomer may, for example, be a mercapto group-containing acrylic monomer or an amine group-containing monomer. Specific examples of the acrylic monomer, the acrylonitrile-containing acrylic monomer, and the like include dimethylaminoethyl (meth)acrylate, acrylonitrile, and N-vinylpyrrolidone.

The aforementioned acrylic polymer (B) can be produced by polymerizing a (meth)acrylic monomer containing, for example, methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, N-butyl acrylate, butyl acrylate, butyl acrylate, n-hexyl acrylate, cyclohexyl acrylate, n-octyl acrylate, isooctyl acrylate, 2-ethylhexyl acrylate, acrylic acid Ester, methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, butyl methacrylate, butyl methacrylate A (meth) acrylate such as n-hexyl methacrylate, cyclohexyl methacrylate, n-octyl methacrylate, isooctyl methacrylate or 2-ethylhexyl methacrylate.

The (meth)acrylic monomer used for the production of the acrylic polymer (B) is preferably one which does not inhibit the high molecular weight of the acrylic polymer (B) and can improve productivity. To use acrylic monomers.

In the case of the above-mentioned (meth)acrylic acid monomer, it is possible to impart excellent adhesion to the extent that it does not cause peeling over time even with respect to either the planar portion or the curved portion of the substrate, and imparts excellent adhesion retention. On the other hand, it is preferred to use a (meth)acrylic monomer which polymerizes the (meth) acrylate (b1) having an aliphatic cyclic structure.

As the (meth) acrylate (b1) having an aliphatic cyclic structure, for example, cyclohexyl acrylate or dicyclopentyl acrylate can be used. (dicyclopentanyl isobornyl acrylate), cyclohexyl methacrylate, etc., can provide excellent adhesion to the extent that it is not peeled off over time, even if it is applied to either the planar portion or the curved portion of the substrate. It is possible to prevent the degree of offset of the adhesive sheet due to the force of the parallel lateral direction on the surface of the substrate, and it is preferable to use cyclohexane (meth) acrylate.

The (meth) acrylate (b1) having an aliphatic cyclic structure is preferably used in an amount of from 1 to 50, based on the total amount of the (meth)acrylic monomer used in the production of the acrylic polymer (B). The range of the mass % can impart excellent adhesion to the extent that it does not cause peeling over time even for either the planar portion or the curved portion of the substrate, and the adhesion can be prevented because of the parallel lateral direction on the surface of the substrate. The degree of offset of the adhesive sheet generated by the force is excellent in the adhesive retention force, and it is preferably in the range of 20 to 40% by mass.

Further, from the viewpoint of enhancing the cohesive force of the adhesive of the present invention, when the above-mentioned crosslinking agent is used in combination, the acrylic polymer (B) is used as a group reactive with a functional group having a crosslinking agent. It is preferred to have a hydroxyl group.

The above-mentioned hydroxyl group can be introduced into the acrylic polymer (B) by using the above-mentioned aliphatic (cyclo)-containing (meth) acrylate (b1) and hydroxyl group-containing (meth) acrylate (b2) in combination. .

As the hydroxyl group-containing (meth) acrylate (b2), for example, hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, hydroxybutyl (meth)acrylate, or (meth)acrylic acid can be used. Hydroxyhexyl ester, hydroxyoctyl (meth)acrylate, hydroxydecyl (meth)acrylate, hydroxylauryl (meth)acrylate, (4-hydroxymethylcyclohexyl)methyl methacrylate, etc. It is preferable to use 4-hydroxybutyl acrylate in the crosslinking reaction with the crosslinking agent mentioned later.

When the (meth)acrylic acid ester (b1) having an aliphatic cyclic structure is used in an amount of from 1 to 50% by mass based on the total amount of the (meth)acrylic monomer used for the production of the acrylic polymer (B) The hydroxyl group-containing (meth) acrylate (b2) is preferably excellent in imparting an excellent adhesion to the extent of peeling off to the planar portion of the substrate and promoting crosslinking reaction with the crosslinking agent. To use a range of 1 to 10% by mass.

As the acrylic polymer (B), for example, an (meth) acrylate (b1) having an aliphatic cyclic structure and optionally a hydroxyl group-containing (meth) acrylate (b2) may be used (methyl group). The acrylic monomer is produced by polymerization in the same manner as in the production method of the above acrylic polymer (A).

Specifically, the (meth)acrylic acid monomer, the polymerization initiator, and the organic solvent are preferably mixed and stirred at a temperature of 40 to 120 ° C to carry out radical polymerization, and the acrylic polymer (B) and the organic compound are used. The solvent mixture is preferably an organic solvent solution of the above acrylic polymer (B).

As the polymerization initiator and the organic solvent, those similar to those used in the production of the above-mentioned acrylic polymer (A) can be used.

The acrylic polymer (B) is preferably contained in an amount of from 20 to 50% by mass based on the total amount of the adhesive of the present invention.

Next, the solvent (C) used in the adhesive of the present invention will be described.

Any solvent (C) used in the present invention may be used as long as it can dissolve or disperse the aforementioned acrylic polymer (A) and acrylic polymer (B). Specifically, toluene, ethyl acetate, butyl acetate, methyl ethyl ketone, hexane, acetone, cyclohexanone, 3-pentanone, acetonitrile, propionitrile, isobutyronitrile, valeronitrile, and dimethyl can be used. Among them, hydrazine, dimethylformamide and the like are preferred, and toluene, ethyl acetate and methyl ethyl ketone are preferably used.

The solvent (C) is preferably contained in the range of 40 to 75% by mass based on the total amount of the adhesive of the present invention.

The adhesive of the present invention may contain other additives as needed in addition to the aforementioned components.

As the additive, for example, a powder such as a crosslinking agent, a crosslinking catalyst, a coloring agent, a pigment, a surfactant, a plasticizer, an adhesion imparting agent, a low molecular weight polymer, a surface smoothing agent, and a leveling agent can be used. An antioxidant, a preservative, a light stabilizer, a UV absorber, a polymerization inhibitor, a decane coupling agent, an inorganic or organic filler, a metal powder, a particulate form, a foil, etc., and are suitably used depending on the use thereof.

The aforementioned crosslinking agent will contribute to the formation of an adhesive layer forming a three-dimensional crosslinked structure. As long as it is the adhesive of the present invention containing the crosslinking agent, the adhesion of the adhesive sheet formed of the base material having the curved portion such as the R portion or the reverse R portion can be prevented from being peeled off.

As the crosslinking agent, for example, an epoxy group-containing compound or an isocyanate group-containing compound or the like can be used. Among them, a compound having two or more isocyanate groups is used because the gel fraction of the adhesive layer can be easily adjusted to The proper range is preferred.

As the compound having two or more isocyanate groups, for example, an aliphatic polyisocyanate such as butyl diisocyanate or hexamethylene diisocyanate, a cyclopentyl diisocyanate, a cyclohexyl diisocyanate or the like can be used. An aromatic polyisocyanate such as an aliphatic polycyclic isocyanate, a methylphenyl diisocyanate, a diphenylmethane diisocyanate or a decyl diisocyanate, such as a ketone diisocyanate, or a trimethylolpropane/methyl phenylene An isocyanate adduct of a diisocyanate trimer adduct, a trimethylolpropane/hexamethylene diisocyanate trimer adduct, a hexamethylene diisocyanate isomeric cyanate, or the like.

As the epoxy group-containing compound, polyethylene glycol diglycidyl ether or the like can be used.

The crosslinking agent containing the aforementioned isocyanate group is used in an amount such that the crosslinking agent has a molar number of isocyanato group (NCO), and the above-mentioned acrylic polymer (A) or (B) has a hydroxyl group (OH). The ratio [NCO/OH] is in the range of 0.05 to 2.5, preferably 0.05 to 1, more preferably 0.05 to 0.4. By using a crosslinking agent obtained by reacting at the above ratio, an adhesive having excellent adhesion to a flat portion of a substrate and also having excellent adhesion to a curved portion of the substrate can be obtained.

Next, a method of producing the adhesive of the present invention will be described.

The adhesive of the present invention is produced, for example, by mixing and stirring an organic solvent solution of the acrylic polymer (A) produced by the above method and an organic solvent solution of the acrylic polymer (B).

Further, when the above-mentioned crosslinking agent is used in combination, it is preferred to mix the crosslinking agent immediately before using the adhesive. Specifically, in order to obtain an adhesive having good coating workability or excellent adhesion, it is preferred to apply an organic solvent solution of the above acrylic polymer (A) and an organic solvent of the above acrylic polymer (B). The adhesive and the crosslinking agent are mixed before the adhesive formed by the mixture of the solution to the surface of the substrate or the like.

The adhesive of the present invention obtained as described above has excellent adhesion, and in particular, even for a substrate having a curved portion such as an R portion or an inverted R portion, it has excellent adhesion to a degree that does not cause peeling of the adhesive sheet. Force (curvature adhesion) can be used, for example, in the manufacture of adhesive sheets for use in complex shaped parts of automobiles or home appliances.

The adhesive sheet is attached to one or both sides of various supports and has an adhesive layer composed of the adhesive of the present invention. For the above-mentioned adhesive sheet, for example, the adhesive of the present invention is applied to one surface or both surfaces of various supports, and generally, it can be produced by forming a gel fraction of about 65 to 75% and curing it. The gel fraction may be adjusted, for example, by placing the substrate coated with the adhesive for a predetermined period of time in an environment of 23 to 40 ° C.

For the support, a resin film can be used, and for the resin constituting the resin film, for example, polyester, polypropylene, polyethylene, polyethylene carbonate, a laminate of these, or the like can be used. Among them, a polyester resin film of polyethylene terephthalate (PET) or the like is preferably used.

In order to improve the adhesion between the resin film and the adhesive layer, it is preferred to carry out surface treatment by corona treatment or the like.

Further, as the support, for example, a fibrous support can be used. The aforementioned fibrous support can be suitably used for the manufacture of double-sided tape, and is particularly suitable for the case where the thickness of the double-sided adhesive sheet is required. Specific examples of the fibrous support include non-woven fabrics and the like, and are, for example, those made of materials such as cotton, hemp, and enamel.

The adhesive sheet obtained as described above can be bonded to the surfaces of the various substrates described above. Specifically, it can be applied to a substrate formed of plastic or metal. Further, as the substrate, not only a flat portion but also an R portion or a curved portion may be used.

The adhesive sheet obtained by the above method has excellent adhesion to the extent of peeling over time even for either the flat portion or the curved portion of the substrate, and can prevent the force due to parallel lateral direction on the surface of the substrate. The offset of the resulting adhesive sheet can be used for, for example, the manufacture of a curved reflector or the like.

The adhesive or adhesive sheet of the present invention can be used for the production of a laminate which is composed of two or more substrates and an adhesive layer formed of the above-mentioned adhesive or the like.

As the substrate to which the adhesive of the present invention or the above-mentioned adhesive sheet can be applied or bonded, for example, a plastic substrate or a metal substrate can be used. In addition, as the substrate, for example, a film or sheet which constitutes a transparent conductive film such as a touch panel can be used.

In the case of a plastic substrate, in general, as a raw material used in plastic molded articles such as mobile phones, home electric appliances, automotive interior and exterior materials, and OA machines, ABS (acrylonitrile-butadiene-benzene) can be cited. Ethylene resin, PC (polycarbonate) resin, ABS/PC resin, PS (polystyrene) resin, acrylic resin, polypropylene resin, polyethylene resin, etc.; as a plastic substrate, polyethylene terephthalate can be used. A substrate composed of an ester, a polyester, a polyethylene, a polypropylene, a TAC (cellulose triacetate), a polycarbonate, a polyvinyl chloride or the like.

As the metal substrate, for example, a heat-expanded steel sheet, a cold-rolled steel sheet, a galvanized steel sheet, an electrogalvanized steel sheet, a hot-dip galvanized steel sheet, an alloyed hot-dip galvanized steel sheet, or a galvanized steel used for automobiles, home electric appliances, and building materials can be used. Alloy steel plate, aluminized-zinc alloy steel plate, aluminized steel plate, copper plated steel plate, galvanized nickel steel plate, galvanized aluminum steel plate, iron-zinc steel plate, tin plated steel plate, etc., or stainless steel plate, aluminum plate, copper plate, A metal substrate such as an aluminum alloy plate or an electromagnetic steel plate.

Further, each of the base materials may have a plate shape, a spherical shape, a film shape, or a sheet shape, and may have a curved surface portion such as an R portion or an inverse R portion.

Further, as a method of applying the pressure-sensitive adhesive to the surface of the substrate, a method using a roll coater, a gravure coater, a reverse coater, a spray coater, a pneumatic blade coater, a die coater or the like can be mentioned.

The thickness of the adhesive layer formed on the surface of the substrate is not particularly limited, but is preferably in the range of 1 to 100 μm, more preferably in the range of 10 to 50 μm.

The laminate obtained by the above method can be used for various articles such as automobile parts or home appliance parts, curved reflectors, and the like.

[Examples]

Hereinafter, the present invention will be specifically described by way of examples and comparative examples.

[Modulation of acrylic polymer] <Modulation Example 1>

35 parts by mass of toluene was fed into a reaction vessel having a stirrer, a thermometer, a reflux cooling tube, and a dropping funnel, and the mixture was heated to a temperature of 90 °C.

Next, a premix 1 containing 95 parts by mass of cyclohexyl methacrylate and 5 parts by mass of N,N-dimethylaminoethyl acrylate, and 2 masses of azobisisobutyronitrile as a polymerization initiator A premix 2 of 50 parts by mass of toluene and 50 parts by weight of each of the toluene was dropped into the reaction vessel. The aforementioned premix 1 was dropped in 6 hours, and the aforementioned premix 2 was dropped in over 6.5 hours.

After the completion of the dropwise addition, the reaction liquid obtained by further heating at the same temperature for 2 hours was mixed with toluene to obtain a solution of the acrylic polymer (A-1) having a nonvolatile content of 50.6 mass%.

<Modulation Example 2>

35 parts by mass of toluene was fed into a reaction vessel having a stirrer, a thermometer, a reflux cooling tube, and a dropping funnel, and the mixture was heated to a temperature of 90 °C.

Next, a premix 3 containing 95 parts by mass of methyl methacrylate and 5 parts by mass of N,N-dimethylaminoethyl acrylate, and 2 parts by mass of azobisisobutyronitrile as a polymerization initiator The premix 4 of 50 parts by mass of toluene was dropped into the reaction vessel. The aforementioned premix 3 was dropped in 6 hours, and the aforementioned premix 4 was dropped in over 6.5 hours.

After the completion of the dropwise addition, the reaction liquid obtained by further heating at the same temperature for 2 hours and toluene were mixed to obtain a solution of an acrylic polymer (A-2) having a nonvolatile content of 50.4% by mass.

<Modulation Example 3>

35 parts by mass of toluene was fed into a reaction vessel having a stirrer, a thermometer, a reflux cooling tube, and a dropping funnel, and the mixture was heated to a temperature of 90 °C.

Next, 100 parts by mass of cyclohexyl methacrylate and a premix 5 containing 2 parts by mass of azobisisobutyronitrile as a polymerization initiator and 50 parts by mass of toluene were dropped into the reaction container. The aforementioned aforementioned cyclohexyl methacrylate was dropped over 6 hours, and the aforementioned premix 5 was added dropwise over 6.5 hours.

After the completion of the dropwise addition, the reaction liquid obtained by further heating at the same temperature for 2 hours and toluene were mixed to obtain a solution of an acrylic polymer (A-3) having a nonvolatile content of 49.5% by mass.

<Modulation Example 4>

35 parts by mass of toluene was fed into a reaction vessel having a stirrer, a thermometer, a reflux cooling tube, and a dropping funnel, and the mixture was heated to a temperature of 90 °C.

Next, 93 parts by mass of cyclohexyl methacrylate, 5 parts by mass of acrylic acid-N,N-dimethylaminoethyl ester and 2 parts by mass of acrylic acid, and an azo containing a polymerization initiator A premix 7 of 2 parts by mass of diisobutyronitrile and 50 parts by mass of toluene was dropped into the reaction vessel. The aforementioned premix 6 was added dropwise over 6 hours, and the aforementioned premix 7 was dropped in over 6.5 hours.

After the completion of the dropwise addition, the reaction liquid obtained by further heating at the same temperature for 2 hours and toluene were mixed to obtain a solution of an acrylic polymer (A-4) having a nonvolatile content of 50.9 mass%.

[Calculation method for calculating Tg (glass transition temperature)]

The glass transition temperature of the acrylic polymer obtained above was calculated based on the FOX equation and the glass transition temperature (literature value) of the homopolymer of the acrylic monomer used.

According to the FOX equation, the glass transition temperature of the homopolymer of each of the acrylic monomers used for calculating the glass transition temperature of the acrylic polymer may be VI/213-258 of "POLYMER HANDBOOK, THIRD EDITION" or " New Polymer Library ‧ Volume 7 ‧ Introduction of Synthetic Resin for Coatings (Beigang Association, Polymer Publishing Association, Kyoto, 1974), 168-169

[Method for measuring viscosity]

The viscosity of the above acrylic polymer can be measured using a BM type rotary viscometer (25 ° C) manufactured by Toki Sangyo Co., Ltd.

[Method for Measuring Weight Average Molecular Weight]

The weight average molecular weight of the aforementioned acrylic polymer can be measured by gel permeation chromatography (GPC). The aforementioned weight average molecular weight means a value obtained in terms of standard polystyrene.

[Table 1]

<Modulation Example 5>

67 parts by mass of butyl acrylate, 30 parts by mass of cyclohexyl acrylate and 3 parts by mass of 4-hydroxybutyl acrylate are fed into a reaction vessel having a stirrer, a thermometer, a reflux cooling tube and a dropping funnel, followed by mixing as a polymerization 0.05 parts by mass of azobis 2-methylbutyronitrile and 150 parts by mass of ethyl acetate as an initiator, after being replaced by nitrogen, an acrylic polymer (B-1) was obtained by polymerization at 65 to 75 ° C for 10 hours. The solution.

<Modulation Example 6~10>

The acrylic polymer (B-2) to (B-) was obtained by the same method as the method for producing the acrylic polymer (B-1) except that the composition of the (meth)acrylic monomer was changed as described in Table 2 below. 6). The calculated Tg, viscosity, number average molecular weight, and weight average molecular weight of the obtained acrylic polymer were measured by the same method as described above.

[Table 2]

Examples 1 to 8 and Comparative Examples 1 to 9

The solid content ratios of the acrylic polymers (A-1) to (A-4) and the acrylic polymers (B-1) to (B-6) are as described in the following Tables 3 to 5, and are mixed in the above-mentioned results. a solution of the acrylic polymer (A-1) to (A-4) and a solution of the acrylic polymer (B-1) to (B-6); further mixed by the amounts described in the following Tables 3 to 5, 6-hexamethylene diisocyanate was used as the isocyanate crosslinking agent (D-1) to obtain an individual adhesive.

Next, the adhesive obtained above was applied to a polyester film (hereinafter referred to as "#50 peeling film") having a thickness of 50 μm which was subjected to polysilicon oxide peeling treatment, and dried at 80 ° C for 3 minutes to be dried. The thickness of the adhesive layer was 25 μm.

Next, a corona-treated transparent polyester film (hereinafter referred to as "#25 PET film") having a thickness of 25 μm was attached to the surface of the dried adhesive layer, and an adhesive was obtained by aging at 23 ° C for 7 days. An adhesive sheet having a thickness of 25 μm and a gel fraction of 75% by mass.

[Method for measuring gel fraction]

First, the mass (G0) of the #25 PET film having a size of 50 mm in length × 50 mm in width was measured. Next, the mass (G1) of the #50 release film was measured from the above-mentioned adhesive sheet having a size of 50 mm in length × 50 mm in width.

Next, the above-mentioned adhesive sheet having a size of 50 mm in length × 50 mm in width of the #50 release film was immersed in a toluene solution, and allowed to stand at room temperature for 24 hours.

After standing, the residue remaining as a toluene insoluble fraction was separated by filtration through a 300 mesh mesh, and the residue was dried at 110 ° C for 1 hour, and then the mass (G2) of the residue was measured. Using the values of G0, G1, and G2 obtained as described above, the gel fraction was calculated from the equation of gel fraction (% by mass) = [(G2-G0) / (G1-G0)] × 100. Further, after the production of the above-mentioned adhesive, the measurement of the gel fraction cannot be performed in the case of causing rapid gelation.

[Method for evaluating the adhesion of the planar portion of the substrate]

The adhesion to the planar portion of the substrate was evaluated by a 180 degree peel test. Specifically, the release film was removed from the above-mentioned adhesive sheet, and the surface of the adhesive layer of the adhesive sheet was bonded to a stainless steel plate, and left for 24 hours to obtain a laminate.

Next, according to JIS Z-0237, the 180-degree peeling strength (tensile speed: 300 mm/min; N/25 mm) of the adhesive sheet constituting the above-mentioned laminated body was measured in an atmosphere of a relative humidity of 50% at 23 °C.

When the 180-degree peeling strength is about 5 N/25 mm or more, it is evaluated that even when the adhesive sheet is bonded to the flat portion of the substrate, the adhesive strength is not caused to cause peeling over time. In addition, the adhesive sheet cannot be produced due to the rapid adhesion of the adhesive or the like, and the evaluation of the adhesive strength cannot be described as "-" in the table.

[Evaluation method for the adhesion of the curved portion of the substrate (resistance to edge-lift)]

For the adhesion of the curved portion of the substrate, an adhesive sheet of 15 mm × 30 mm was cut out from the above-mentioned adhesive sheet, and the release film was removed, and it was attached to the circumferential portion of the cylinder formed of polypropylene having a diameter of 20 mm. , placed in an environment of 40 ° C for 24 hours. The bonding is performed such that the 30 mm wide side of the adhesive sheet is formed in parallel with the circumferential direction of the cylindrical portion. After the above placement, the distance (mm) at which the end of the adhesive sheet was released or peeled from the cylinder was measured.

[Evaluation method of adhesion retention]

The #50 release film was removed from the above-mentioned adhesive sheet, and the surface of the adhesive layer constituting the adhesive sheet was bonded to a stainless steel plate to obtain a laminate having a subsequent area of 25 mm in length × 25 mm in width.

Next, the laminated body is fixed in the longitudinal direction in an environment of 70 ° C so as to hang a load of 1 kg with respect to the end portion of the adhesive sheet constituting the laminated body and in a direction parallel to the adhesive sheet. State, placed for 24 hours.

After 24 hours, the distance from which the adhesive sheet was slid downward was measured with respect to the stainless steel sheet constituting the laminate. When the distance is 0.1 mm, it is evaluated as having an adhesive holding force which is capable of preventing the offset of the adhesive sheet parallel to the force in the lateral direction of the surface of the substrate. In addition, the adhesive sheet cannot be formed due to the rapid adhesion of the adhesive or the like, and the evaluation of the adhesive strength cannot be described as "-" in the table. Further, the time required for the adhesive sheet to peel off from the stainless steel sheet before the above-mentioned 24 hours passed, and the time required until it fell, is shown in Tables 3 and 4.

[Method of evaluating haze value]

The surface of the adhesive layer of the adhesive sheet of the #50 release film and the colorless transparent glass plate having a haze value of 0% were bonded together, and then placed under conditions of 60 ° C and 90% RH for 100 hours to obtain a laminate. body.

The transparency of the above-mentioned adhesive layer was measured from the surface of the glass plate which comprises the said laminated body using the haze value. When the haze value (%) is less than 3%, it is evaluated as "○", 3% or more, less than 5%, and evaluated as "△", and 5% or more as "X". Further, the adhesive sheet cannot be produced due to the rapid adhesion of the adhesive or the like, and the evaluation of the adhesive strength cannot be described as "-" in the table.

[Evaluation method of corrosion resistance]

The surface of the adhesive layer of the above-mentioned adhesive sheet of the #50 release film and the aluminum plate were adhered and placed in an environment of 60 ° C and 95% RH for 250 hours to obtain a laminate.

After the above-mentioned placement, the adhesive sheet and the adhesive layer were peeled off from the laminated body, and the surface of the aluminum plate in contact with the above-mentioned adhesive layer was visually observed to evaluate the presence or absence of corrosion.

Those having no corrosion on the surface of the aluminum plate were evaluated as "○", and those having corrosion were evaluated as "x". In addition, the adhesive sheet cannot be produced due to the rapid adhesion of the adhesive or the like, and the evaluation of the adhesive strength cannot be described as "-" in the table.

[table 3]

[Table 4]

[table 5]

Claims (11)

An adhesive comprising an acrylic polymer (A) having a weight average molecular weight of 1,000 to 50,000, an acrylic polymer (B) having a weight average molecular weight of 500,000 or more, and a solvent (C), wherein: The acrylic polymer (A) does not have a carboxyl group, and is polymerized to contain 2 to 10% by mass of a nitrogen atom-containing (meth) acrylate (a1), and 90 to 98% by mass to form a 0 to 180 ° C. a glass transition temperature homopolymer of a (meth)acrylic monomer (a2) of a (meth)acrylic monomer mixture; the acrylic polymer (B) has no carboxyl group and a nitrogen atom-containing group; the acrylic polymer (A) The mass ratio [(A)/(B)] to the acrylic polymer (B) is in the range of 1/100 to 50/100; and is 40 to 75 mass with respect to the total amount of the adhesive The range of % contains the solvent (C). The adhesive of claim 1, wherein the nitrogen atom-containing (meth) acrylate (a1) is N,N-dimethylaminoethyl acrylate. The adhesive of claim 1, wherein the (meth)acrylic monomer (a2) is selected from the group consisting of alkyl (meth)acrylates and (meth)acrylates having an aliphatic cyclic structure. One or more of the groups formed. The adhesive of claim 3, wherein the alkyl (meth)acrylate contains methyl (meth)acrylate. The adhesive of claim 1, wherein the acrylic polymer (A) has a glass transition temperature in the range of 0 to 160 °C. An adhesive according to claim 1, wherein the acrylic acid is polymerized The substance (B) has an aliphatic ring structure and a hydroxyl group. The adhesive of the first aspect of the invention, wherein the acrylic polymer (B) is polymerized and contains 1 to 50% by mass of an aliphatic cyclic structure (meth) acrylate (b1) and 1 to 10% by mass. A mixture of (meth)acrylic monomers of a hydroxyl group-containing (meth) acrylate (b2). The adhesive of claim 1, which further contains a crosslinking agent. The adhesive of claim 8, wherein the crosslinking agent is a compound having two or more isocyanate groups. An adhesive sheet attached to a surface of a support having an adhesive layer formed using an adhesive as disclosed in claim 8 or 9. A method for producing an adhesive sheet, characterized in that an adhesive as disclosed in claim 8 or 9 is applied onto a surface of a substrate to which a release treatment is applied, and then a support is laminated on the coated surface, the adhesive sheet being The support has an adhesive layer on the surface thereof, and an adhesive sheet of the substrate to which the release treatment is applied is provided on the surface of the adhesive layer.