JP2001207148A - Adhesive composition and method for producing the same and adhesive sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an adhesive composition based on a block copolymer composed of non-elastomeric polymer block A and elastomeric polymer block B, and exhibiting improved adhesivity, in particular high adhesivity to low-polar polyolefin-based adherends as well. SOLUTION: This adhesive composition is obtained by incorporating a low- molecular weight polymer 0-16 deg.C in glass transition temperature and 1,000-10,0000 in number-average molecular weight in a block copolymer 15,000-200,000 in number-average molecular weight composed of non-elastomeric polymer block A >=20 deg.C in glass transition temperature and elastomeric polymer block B consisting of a (meth)acrylate-based polymer in at least two block-bonded fashion and produced by living radical polymerization in an appropriate monomer order between a monomer to give the above non-elastomeric polymer block A and a (meth)acrylate-based monomer in the presence of a transition metal and its ligand using a polymerization initiator.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pressure-sensitive adhesive composition using a block copolymer, a method for producing the same, and pressure-sensitive adhesive sheets (sheets, tapes, etc.).

[0002]

2. Description of the Related Art In recent years, adhesive tapes for packaging, adhesive tapes for masking for coating, adhesive tapes for medical use, adhesive tapes for sanitary products, adhesive tapes for fixing disposable diapers, adhesive labels, and the like. For applications that require easy adhesion by pressing, adhesives such as solvent type, emulsion type and hot melt type are used.

[0003] Rubber-based and (meth) acrylate-based adhesives are known as solvent-based pressure-sensitive adhesives. However, in recent years, from the viewpoint of drying efficiency, energy saving and working environment, the amount of solvent used has been reduced. It is desired to reduce as much as possible. In response to this demand, if the amount of the solvent used in the production of the polymer is reduced, there is a problem in safety from the viewpoint of controlling the generated heat of polymerization. In addition, in the emulsion type pressure-sensitive adhesive, since the polymer particles are dispersed in water, it is necessary to finally remove water when forming the pressure-sensitive adhesive layer, and for reasons of drying efficiency and energy saving, After all there was a problem.

[0004] Hot-melt pressure-sensitive adhesives are superior to solvent-type and emulsion-type pressure-sensitive adhesives in terms of safety and economy, and for example, those containing a styrene-isoprene block copolymer as a main component. It has been known. However, this kind of pressure-sensitive adhesive generally has poor light resistance, and there is a problem of deterioration in performance of a product using the same over time. Therefore, instead of the above-mentioned isoprene-based polymer component which causes a decrease in light fastness, a (meth) acrylate-based polymer component which is generally known to have good light fastness is introduced, and the above problem is solved. Attempts have been made to obtain a tack-free adhesive.

However, a random copolymer of a (meth) acrylate monomer and a styrene monomer is
Although it can be easily synthesized and there are examples in which this is used as the main component of the pressure-sensitive adhesive, no satisfactory adhesive property has been obtained. On the other hand, a block copolymer of a styrene-based polymer component and a (meth) acrylate-based polymer component is easily prepared by any of radical polymerization, anion polymerization, and cation polymerization. It was not obtained, and there was no case where this was used as a main component of the pressure-sensitive adhesive.

[0006]

SUMMARY OF THE INVENTION In view of the above-mentioned circumstances, the present invention provides a non-elastomeric polymer component composed of a styrene-based polymer and the like and an elastomer composed of a (meth) acrylate polymer. -By easily forming a block copolymer with a non-soluble polymer component in the absence of a solvent or in the presence of a small amount of solvent without causing a problem in safety, and using this as the main component of the adhesive, Improvement of light resistance based on introduction of (meth) acrylate polymer without causing economical problems such as conventional emulsion type, that is, problems such as drying efficiency for removing water and energy saving. A pressure-sensitive adhesive composition that exhibits improved pressure-sensitive properties in addition to the effect, and particularly has high adhesion to low-polarity polyolefin-based adherends such as polyethylene and polypropylene. And its object is to provide the door such - production method and the adhesive sheet.

[0007]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to achieve the above object, and as a result, have found that a styrene-based monomer or the like which provides a non-elastomeric polymer and a (meth) acrylate According to the method of subjecting a monomer to a living radical polymerization using a specific activator and a polymerization initiator, a non-elastomer composed of a styrene-based polymer or the like, for which no suitable synthesis method has been conventionally known, has been known. A formed by combining a polymer block A with an elastomeric polymer block B comprising a (meth) acrylate polymer.
Block copolymers such as -B type and ABA type can be easily produced in the absence of a solvent or in the presence of a small amount of a solvent without causing safety problems such as control of polymerization heat. I can tell you. Further, by using this block copolymer as a main component of the pressure-sensitive adhesive, and further mixing a specific low-molecular-weight polymer with this, without causing the economical problems of the conventional emulsion type,
In addition to the original effect of improving light resistance based on (meth) acrylate-based polymers, it exhibits improved adhesive properties, especially for low-polarity polyolefin-based adherends such as polyethylene and polypropylene. It has been found that a pressure-sensitive adhesive composition having adhesive properties and excellent heat resistance can be obtained, and the present invention has been completed.

That is, the present invention relates to a) a non-elastomeric polymer block A having a glass transition temperature of 20 ° C. or higher;
A block copolymer having a number-average molecular weight of 15,000 to 200,000 and having at least two blocks bonded to an elastomeric polymer block B of a (meth) acrylate polymer; and b) a glass transition temperature. A pressure-sensitive adhesive composition comprising a low molecular weight polymer having a number average molecular weight of 1,000 to 10,000 in the range of 0 to 160 ° C., in particular, the block copolymer of the component a is -B
The present invention relates to the pressure-sensitive adhesive composition having the above-mentioned constitution, which is a block copolymer of A type or ABA type. Also, the present invention
The present invention relates to pressure-sensitive adhesive sheets characterized in that a layer comprising the pressure-sensitive adhesive composition having the above structure is provided on a support.

Further, the present invention provides a method for producing a pressure-sensitive adhesive composition having the above constitution, which comprises a monomer for imparting a non-elastomer polymer having a glass transition temperature of 20 ° C. or higher, and a (meth) acrylate monomer. Is subjected to living radical polymerization in the proper monomer sequence using a polymerization initiator in the presence of a transition metal and its ligand, and a) a non-elastomeric polymer block having a glass transition temperature of 20 ° C. or higher. A and an elastomeric polymer block B composed of a (meth) acrylate polymer are bonded to at least two blocks to form a block copolymer having a number average molecular weight of 15,000 to 200,000, In addition, b) a glass transition temperature of 0 to 160 ° C.
The method for producing a pressure-sensitive adhesive composition, comprising mixing a low molecular weight polymer having a number average molecular weight of 1,000 to 10,000 in the range of (1) to (3), in particular, when the combination of the transition metal and the ligand is Cu ^{+ 1} The present invention relates to a method for producing a pressure-sensitive adhesive composition having the above constitution, which is a bipyridine complex.

[0010]

The living radical polymerization method is described in, for example, (1) a report by Patten et al., "Radical
Polymerization Yielding Polymers with Mw / Mn 〜 1.0
5 by Homogeneous Atom Transfer Radical Polymerizat
ion ”Polymer Preprinted, pp 575-6, No37 (March 199
6), (2) Report by Matyjasewski et al., “Controlled
/ LivingRadical Polymerization. Halogen Atom Trans
fer Radical Polymerization Promoted by a Cu (I) / Cu
(II) Redox Process ”Macromolecules 1995,28,7901-10
(October 15,1995), (3) Same PCT / US96 / 0330
2, International Publication No. WO96 / 30421 (Oc
tober 3, 1996), (4) Report by M. Sawamoto et al., “Ruthen
ium-mediated Living Radical polymerization of Meth
yl Methacrylate "Macromolecules, 1996, 29, 1070.

The present inventors have focused on this living radical polymerization method, using a transition metal and its ligand as an activator, and using a polymerization initiator in the presence of these, to reduce the glass transition temperature. By subjecting a monomer such as a styrene monomer giving a non-elastomeric polymer at 20 ° C. or higher and a (meth) acrylate monomer to a living monomer in an appropriate monomer order, the glass A block copolymer obtained by bonding at least two blocks of a non-elastomer polymer block A having a transition temperature of 20 ° C. or more and an elastomer polymer block B composed of a (meth) acrylate polymer. That can be easily generated.

The transition metals include Cu, Ru, Fe, R
There are h, V and Ni, which are usually used from halides (chlorides, bromides, etc.) of these metals. The ligand is a ligand which coordinates with a transition metal as a center to form a complex, and a bipyridine derivative, a mercaptan derivative, a trifluorate derivative and the like are preferably used. Among combinations of transition metals and their ligands, C
The u ^{+ 1} -bipyridine complex is most preferred in terms of polymerization stability and polymerization rate.

The polymerization initiator is preferably an ester or styrene derivative containing a halogen at the α-position, particularly preferably a 2-bromo (or chloro) propionic acid derivative or a 1-phenyl chloride (or bromide) derivative. Used. Specifically, methyl 2-bromo (or chloro) propionate, 2-bromo (or chloro)
Ethyl propionate, 2-bromo (or chloro) -2
Methyl-methylpropionate, ethyl 2-bromo (or chloro) -2-methylpropionate, 1-phenylethyl chloride (or bromide) and the like.

In the present invention, styrene, α-methyl styrene, styrene, α-methyl styrene, and the like are typically used as monomers that provide a non-elastomer polymer having a glass transition temperature of 20 ° C. or higher, which is one of the polymerizable monomers. Styrene monomers such as 1,4-dimethylstyrene and 4-methoxystyrene are used. However, the monomer is not particularly limited as long as it is a monomer to which the above-mentioned non-elastomer polymer is added. For example, non-styrene-based polymers such as isobornyl acrylate and dicyclopentanyl acrylate may be used. Monomers can also be used.

The (meth) acrylate monomer as another polymerizable monomer is represented by the general formula (1): CH ₂ ＣＲCR ¹ COOR ² (where R ¹ is a hydrogen atom or A methyl group, and R ² is an alkyl group having 2 to 14 carbon atoms), and a main monomer is (meth) acrylate represented by n-butyl (meth).
Acrylate, 2-ethylhexyl (meth) acrylate
(Meth) acrylates having an alkyl group having 4 to 12 carbon atoms, such as isooctyl (meth) acrylate, isononyl (meth) acrylate and the like are preferably used.

As the (meth) acrylate-based monomer, together with the above-mentioned main monomer, a modifying monomer copolymerizable therewith is used in an amount of 40% by weight of the whole (meth) acrylate-based monomer. Below, preferably 30% by weight or less, more preferably 20% by weight or less. Such modifying monomers include (meth) acrylamide, mono or diesters of maleic acid, glycidyl (meth) acrylate, N, N-dimethylaminoethyl (meth) acrylate, N, N-dimethyl Examples include aminopropyl (meth) acrylate, N-vinylpyrrolidone, acrylonitrile, (meth) acryloylylmorpholine and the like.

In the living radical polymerization method, for example, a non-elastomer having a glass transition temperature of 20 ° C. or more is used.
When the monomer to which the hydrophilic polymer is added is a styrene monomer, the styrene monomer is first polymerized, and then a (meth) acrylate monomer is added to the monomer.
If the polymerization is continued, an AB block copolymer can be produced. In addition, the above (meth) acrylate monomer
After the polymerization of, a styrene monomer is added again and the polymerization of this monomer is continued, whereby an ABA block copolymer can be produced. Further, by reversing the order of these polymerizations, an arbitrary block copolymer such as BA type or BAB type can be produced. When the subsequent monomer is added in such a sequential polymerization, when the polymerization conversion of the previous monomer exceeds at least 50% by weight, usually at least 60% by weight, preferably 70% by weight. %, More preferably at least 80% by weight, even more preferably at least 90% by weight.

In the above living radical polymerization, the polymerization initiator is used in a proportion of usually 0.01 to 10 mol%, preferably 0.1 to 5 mol%, based on the entire polymerizable monomer. The transition metal is used in an amount of usually 0.01 to 3 mol, preferably 0.1 to 1 mol, per 1 mol of the polymerization initiator in the form of a halide or the like. Further, the ligand is used in an amount of usually 1 to 5 mol, preferably 2 to 3 mol, per 1 mol of the above-mentioned transition metal (form such as halide). When the polymerization initiator and the activator are used in such a ratio, good results can be obtained in the reactivity of living radical polymerization, the molecular weight of the produced polymer, and the like.

Such a living radical polymerization can proceed without a solvent or may proceed in the presence of a solvent such as butyl acetate, toluene or xylene.
When a solvent is used, it is preferable to use a small amount so that the concentration of the solvent after the completion of the polymerization becomes 50% by weight or less in order to prevent a decrease in the polymerization rate. Even with no solvent or a small amount of solvent, there is no particular safety problem related to the control of the heat of polymerization, etc. Rather, the reduction of the solvent can provide good results in terms of economy and environmental measures. In addition, the polymerization conditions depend on the final molecular weight and the polymerization temperature at a polymerization temperature of 70 to 130 ° C. from the viewpoint of the polymerization rate and the deactivation of the catalyst, but the polymerization time is about 1 to 100 hours. I just need.

The block copolymer thus produced is a non-elastomeric polymer block A having a glass transition temperature of 20 ° C. or higher, such as an AB type block copolymer, such as a styrene-based polymer. It has a structure in which an elastomeric polymer block B composed of a (meth) acrylate polymer is bonded to the starting point, and the above-mentioned non-elastomer polymer is used in the ABA type block copolymer. Block A is used as a starting point, to which the above-mentioned elastomeric polymer block B and the above-mentioned non-elastomeric polymer block A are added.
And are sequentially bonded. Thus, the non-elastomeric polymer block A having a glass transition temperature of 20 ° C. or more
Elastomer consisting of and (meth) acrylate polymer
Any block copolymer in which at least two blocks are bonded to the hydrophilic polymer block B shows a microdomain structure as seen in a commonly used styrene-isoprene-styrene-based block copolymer, which together with adhesive strength It appears to provide excellent cohesive properties, satisfying cohesion.

In such a block copolymer having at least two blocks bonded thereto, the proportion of the non-elastomer polymer block A having a glass transition temperature of 20 ° C. or more, such as a styrene polymer, is defined as a block copolymer. The content is 5 to 50% by weight, preferably 10 to 40% by weight, and more preferably 15 to 30% by weight. If the proportion of the non-elastomeric polymer block A is too large,
The polymer lacks the viscoelastic properties required for the pressure-sensitive adhesive and is too hard for the pressure-sensitive adhesive. Conversely, if the amount is too small, the cohesive strength required for the pressure-sensitive adhesive is inferior.

The number average molecular weight of such a block copolymer is 15,000 to 200,000, preferably 30,000, from the viewpoint of adhesive properties and coatability.
It is good to be 0-100,000. Here, the above number average molecular weight means a value determined in terms of polystyrene by GPC (gel permeation chromatography). The number average molecular weight [Mn] of the block copolymer is Mn (calculated value) = [(molecular weight of monomer)
X (molar ratio of monomer)] / (molar ratio of polymerization initiator). Therefore, theoretically, the number average molecular weight of the obtained block copolymer can be intentionally controlled by adjusting the charge ratio of the polymerizable monomer and the polymerization initiator.

In the present invention, a block copolymer having at least two blocks bonded thereto is used as the component a. The component a is used as a main component, and a low molecular weight polymer of the component b described below is mixed with the component a. The pressure-sensitive adhesive composition is prepared. When the pressure-sensitive adhesive composition is subjected to a crosslinking treatment, an appropriate functional group is previously added to the polymer chain of the block copolymer (a) in order to facilitate the crosslinking treatment. It is better to include it.

The type of the functional group can be appropriately selected according to the method of the crosslinking treatment. When a polyfunctional isocyanate or the like is used as a crosslinking agent, a hydroxyl group is used as a functional group that reacts with the crosslinking agent. Is desirable. The block copolymer having a hydroxyl group can be further prepared by using a polymer having a hydroxyl group in a molecule as a polymerization initiator or using a monomer having a hydroxyl group in a molecule as one kind of a polymerizable monomer. Can be easily generated by combining these.

When a polymerization initiator having a hydroxyl group in the molecule is used, the above-mentioned hydroxyl group can be introduced into the starting terminal of the polymer chain. As such a polymerization initiator, α-
Ester- or styrene-based derivatives containing a halogen at the 1-position and having a hydroxyl group in the molecule are preferred. Specifically, 2-hydroxyethyl 2-bromo (or chloro) propionate, 4-hydroxybutyl 2-bromo (or chloro) propionate, 2-hydroxyethyl 2-bromo (or chloro) -2-methylpropionate , 4-bromobutyl (or chloro) -2-methylpropionate, and the like.
The polymerization initiator having a hydroxyl group in the molecule may be used in combination with the polymerization initiator having no hydroxyl group in the molecule, and in this case, the total amount of both may be in the above range. .

When a monomer having a hydroxyl group in the molecule is used, the hydroxyl group can be introduced at an arbitrary position in the polymer chain according to the time of addition of the monomer. Such monomers include the formula (2): CH ₂ ＣＲCR ³ COOR ⁴ (where R ³ is a hydrogen atom or a methyl group, and R ⁴ is an alkyl having 2 to 6 carbon atoms having at least one hydroxyl group. A hydroxyalkyl (meth) acrylate represented by the following formula: Specifically, 2-hydroxyethyl (meth) acrylic
3-hydroxypropyl (meth) acrylate, 4
-Hydroxybutyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate and the like.
These monomers having a hydroxyl group in the molecule are used in an amount of not more than 10% by weight, preferably not more than 5% by weight of the whole polymerizable monomer in order to maintain good adhesive properties.

When a polymerization initiator having a hydroxyl group in the molecule is used in combination with a monomer having a hydroxyl group in the molecule, good results can be obtained due to the adhesive properties after crosslinking. In particular, the above monomer is added at a later stage of polymerization, that is, at the final stage (for example, A-
When the polymerization conversion of the monomer reaches 80% by weight or more during the formation of the polymer block of the second stage in the B type and the third stage in the ABA type), the polymer is terminated at the terminal end of the polymer chain. The hydroxyl group of the above monomer can be introduced into the block copolymer, and two or more hydroxyl groups are telechelically introduced into the block copolymer by this and the hydroxyl group derived from the polymerization initiator introduced into the starting terminal of the polymer chain. Will be. As a result, the block copolymer is extended more linearly by the cross-linking reaction, and a uniform cross-linked polymer with a small variation in the distance between cross-links is obtained, which leads to a better result by improving the adhesive properties. .

The low molecular weight polymer as the component (b) used in the present invention can be mixed with the block copolymer of the component (a) to reduce the compatibility and weather resistance of a general tackifying resin. It is intended to further improve the adhesive force without causing the problem of the above and without reducing the cohesive force, and in particular, has high adhesiveness to low-polarity polyolefin-based adherends such as polyethylene and polypropylene. It will greatly contribute to the further improvement of the adhesive properties.

Such a low molecular weight polymer has a glass transition temperature in the range of 0 to 160 ° C., particularly 0 to 100 ° C.
Having a number average molecular weight of 1,000 to 10,000.
It is preferably in the range of 0, especially 3,000 to 10,000. Here, the above number average molecular weight means a value measured in the same manner as in the case of the block copolymer of the component a. When the glass transition temperature and the number average molecular weight deviate from the above ranges, it is difficult to obtain good results in improving the adhesive properties. In particular, when the glass transition temperature is lower than 0 ° C., the cohesive force tends to decrease, and
When the temperature exceeds ℃, it becomes too hard, and the performance as an adhesive is deteriorated.

Such a low molecular weight polymer, as a monomer, has a glass transition temperature of a homopolymer or a copolymer within the above range, and desirably contributes particularly to an improvement in adhesion to a low-polarity polyolefin-based adherend. It can be obtained by selecting a low-polar monomer component and polymerizing the same by an appropriate polymerization method. Examples of the low polarity monomer component include, for example, isobornyl (meth)
Acrylate, phenoxyethyl (meth) acrylate
Styrene, dicyclopentanyl acrylate, methyl (meth) acrylate, and (meth) acrylate which is one of the polymerizable monomers for obtaining a block copolymer of the above and component a. And a combination system with a terpolymer monomer.

The polymerization of these monomers includes radical polymerization,
Various polymerization methods such as ionic polymerization (cationic polymerization or anionic polymerization), coordination polymerization, ring-opening polymerization, polycondensation, and polyaddition can be employed, and the block copolymer of component a is particularly desirable. It is preferable to employ the living radical polymerization method used to obtain the compound. According to this living radical polymerization method, it is easy to control the molecular weight and a polymer having a narrow molecular weight distribution can be easily obtained. Further, when a functional group is contained in the polymer molecule, the amount of the functional group is reduced. And the introduction position can be easily controlled. Such a living radical polymerization method can be carried out in the same manner as in the case of obtaining the block copolymer of the component a, except that the above component is selectively used as a monomer.

The low molecular weight polymer of the component b thus obtained is used in a proportion of usually 5 to 70 parts by weight, preferably 10 to 50 parts by weight, per 100 parts by weight of the block copolymer of the component a. When the amount of the low molecular weight polymer of the component b is less than 5 parts by weight, the effect of improving the adhesive force, particularly the effect of improving the adhesiveness to a low-polarity polyolefin-based adherend is reduced, and when it exceeds 70 parts by weight, Cohesive strength is reduced, and none of them has a favorable effect on improving the adhesive properties.

The pressure-sensitive adhesive composition of the present invention is obtained by mixing a block copolymer as the component a as a main component and a low-molecular weight polymer as the component b in the ratio described above. If necessary, various additives such as a filler, an antioxidant, and a pigment, which are blended in a general pressure-sensitive adhesive composition, can be included. These various additives are used in usual addition amounts without impairing the effects of the present invention.

The pressure-sensitive adhesive composition of the present invention can be used as it is without subjecting it to crosslinking treatment. Further, if necessary, an appropriate crosslinking treatment is carried out so that the main chain extension and network formation of the block copolymer as the component a or this and the low molecular weight polymer as the component b are simultaneously carried out to reduce the molecular chain length. A long cross-linked polymer may be produced, which may be used as a pressure-sensitive adhesive with further increased cohesion.

The method of the crosslinking treatment is not particularly limited, and various known methods can be employed. The most effective method is, as described above, a method in which a hydroxyl group is previously contained in the polymer chain of the block copolymer as the component a. In this case, if necessary, a hydroxyl group is also contained in the molecule of the low molecular weight polymer as the component b, and a polyfunctional isocyanate is added to these as a crosslinking agent, and the above hydroxyl group and isocyanate are added. ―
And a method of causing a heat reaction with a thio group. Alternatively, a polyfunctional acid anhydride such as pyromellitic anhydride may be used as a crosslinking agent other than the above, and the reaction may be performed in the same manner as described above.

Examples of the polyfunctional isocyanate include tolylene diisocyanate, diphenylmethane diisocyanate
G, p-phenylene diisocyanate, hexamethylene diisocyanate, 1,5-naphthalene diisocyanate
And adducts of these diisocyanates with polyhydric alcohols, such as propanetriol, and tricyanuric derivatives obtained by trimerizing these diisocyanates. Further, a block of such polyfunctional isocyanate, specifically, a compound protected with ethyl acetoacetate, methyl ethyl ketoxime, caprolactam, or the like may be used after being activated by heating during the crosslinking treatment.

The amount of such a polyfunctional isocyanate to be used is determined according to the number of hydroxyl groups contained in the block copolymer of the component a, etc., and usually, the amount per 100 parts by weight of the above block copolymer is The use ratio is preferably 0.05 to 5 parts by weight. If the amount is too large, the adhesive strength decreases, and if the amount is too small, the cohesive strength becomes insufficient. In addition, the above-mentioned cross-linking treatment can be usually carried out by heating to 50 to 150 ° C. In this case, a catalyst such as a tin compound may be used to accelerate the cross-linking speed.

The pressure-sensitive adhesive sheets of the present invention are prepared by applying a pressure-sensitive adhesive composition to one or both surfaces of a support, drying if necessary, and then performing a cross-linking treatment by the above-mentioned method. Is formed on one surface of a layer of the pressure-sensitive adhesive composition which usually has a thickness of 10 to 100 μm, and is formed into a tape or sheet shape. As the support, paper, plastic laminate paper, cloth, plastic laminate cloth, plastic film, metal foil, foam, etc. are used.
In addition, a peeled film or paper may be used. Further, when applying the pressure-sensitive adhesive composition on the support, the pressure-sensitive adhesive composition can be applied in a state where the viscosity is reduced by heating as necessary.
, A comma roll, a gravure coater, a roll coater, a kiss coater, a slot die coater, a squeeze coater and the like.

[0039]

The present invention will be described more specifically with reference to the following examples. The AB block copolymer (1) used in the examples and the ABBA block copolymer
(2) and the low molecular weight polymers (1) to (7) and the low molecular weight polymers (8) and (9) used in Comparative Examples were prepared in the following Production Examples 1a and 2a, Production Examples 1b to 7b and Comparative Production Example 1c,
2c.

In these production examples, most of the production raw materials used were commercially available raw materials, and as polymerization initiators, commercially available ethyl 2-bromoisobutyrate (hereinafter referred to as 2-ILE) and α, α ′ were used. -Azobisisobutyronitrile (hereinafter referred to as AIBN), 2-hydroxyethyl 2-bromo-2-methylpropionate (hereinafter simply referred to as 2-H2MPN), 2-bromopropion synthesized by the following method 4-hydroxybutyl acid (hereinafter simply referred to as 2-H
4PN) was used.

<Synthesis of 2-H2MPN> 4.1 g (20 mmol) of dicyclohexylcarbodiimide, 5 g (81 mmol) of anhydrous ethylene glycol and 1 mmol (12 mmol) of pyridine were placed in a reaction vessel, and 14 ml of acetone and 14 ml of acetone were added thereto. 3.6 g (16.7 mmol) of 2-bromo-2-methylpropionic acid were added while cooling in an ice bath to suppress the exothermic reaction. After the reaction overnight, the precipitate was removed by filtration, and 20 ml of ethyl acetate and 15 ml of saturated saline were added thereto, followed by shaking well. After standing for a while, the upper ethyl acetate layer was washed twice with dilute hydrochloric acid and three times with 15 ml of saturated saline, and dried over anhydrous magnesium sulfate. After removing magnesium sulfate, ethyl acetate was distilled off under reduced pressure to obtain a crude product. The crude product thus obtained was purified by silica gel chromatography (developing solvent: ethyl acetate / hexane = 1/1 mixed solvent) to give the desired product, 2-H.
2 MPN was obtained. The yield was 1.5 g (46% by weight).

<Synthesis of 2-H4PN> Except that 1,4-butanediol was used instead of ethylene glycol anhydride and 2-bromopropionic acid was used instead of 2-bromo-2-methylpropionic acid, 2-H4PN was synthesized by the same operation as the synthesis of 2-H2MPN.

Production Example 1a 45.5 g of styrene was placed in a four-necked flask equipped with a mechanical stirrer, a nitrogen inlet, a condenser, and a rubber septum.
(438 mmol), 2.05 g (13.1 mmol) of 2,2'-bipyridine was added thereto, and the atmosphere in the system was replaced with nitrogen. 626 mg of copper bromide (4.
The reaction system was heated to 90 ° C., and 923 mg (4.37) of 2-H2MPN was used as a polymerization initiator.
(Mmol) was added to initiate polymerization, and polymerization was performed at 90 ° C for 12 hours under a nitrogen stream without adding a solvent. It was confirmed that the polymerization rate (the value obtained by dividing the weight of the polymer from which the volatile components were removed by heating by the amount of the polymer in the polymerization solution as it was before removing the volatile components; the same applies hereinafter) was 80% by weight or more. Thereafter, 182 g (1,420 mmol) of n-butyl acrylate was added from a rubber septum, and the mixture was further heated for 20 hours. After confirming that the polymerization rate was 80% by weight or more again, 1.13 g (6.56 mmol) of 6-hydroxyhexyl acrylate was added to the polymerization system, and polymerization was performed for 20 hours. The polymer thus obtained was diluted to about 20% by weight with ethyl acetate, and the catalyst was removed by filtration. Finally,
Ethyl acetate was distilled off, and the mixture was heated under reduced pressure (60 ° C.) to give an AB block copolymer having hydroxyl groups at both molecular ends (1)
Was manufactured. This block copolymer (1) had a number average molecular weight of 47,000.

Production Example 2a 14.2 g of styrene was placed in a four-necked flask equipped with a mechanical stirrer, a nitrogen inlet, a condenser, and a rubber septum.
(137 mmol), 1.3 g (8.3 mmol) of 2,2'-bipyridine was added thereto, and the atmosphere in the system was replaced with nitrogen. Under a nitrogen stream, 410 mg of copper bromide (2.84
), The reaction system was heated to 90 ° C, 600 mg (2.84 mmol) of 2-H2MPN was added as a polymerization initiator to initiate polymerization, and 12 hours at 90 ° C under a nitrogen stream without a solvent. Polymerized for hours. After confirming that the conversion was 80% by weight or more, 182 g (1,420 mmol) of 2-ethylhexyl acrylate was added from a rubber septum, and the mixture was further heated at 110 ° C. for 20 hours. After confirming that the polymerization rate is 80% by weight or more again, 6-hydroxyhexyl acrylate 7
40 mg (4.28 mmol) was added and polymerized for 16 hours. Finally, 14.2 g of styrene (137
Mmol) from a rubber septum and add
Heated for hours. The polymer thus obtained was diluted to about 20% by weight with ethyl acetate, and the catalyst was removed by filtration. Finally, the ethyl acetate was distilled off and heated under reduced pressure (60 ° C).
An ABA type block copolymer (2) having hydroxyl groups at both molecular ends was prepared. The ABA type block copolymer (2) had a number average molecular weight of 50,000.

Production Example 1b 50 g (240 mmol) of isobornyl acrylate was added to a four-necked flask equipped with a mechanical stirrer, a nitrogen inlet, a condenser, and a rubber septum. ′
4.67 g (30 mmol) of -bipyridine was added, and the system was replaced with nitrogen. This was mixed with copper bromide 1.43 under a nitrogen stream.
g (10 mmol), the reaction system was heated to 90 ° C., and 167 mg (1 mg) of 2-H2MPN as a polymerization initiator was added.
(0 mmol) to initiate polymerization, and polymerization was carried out at 90 ° C. for 6 hours under a nitrogen stream without adding a solvent. 80% by weight polymerization
After confirming the above, 1.72 g (10 mmol) of 6-hydroxyhexyl acrylate was added to the polymerization system, and polymerization was performed for 16 hours. The polymer thus obtained was diluted to about 20% by weight with ethyl acetate, and the catalyst was removed by filtration. Finally, the ethyl acetate was distilled off, and the mixture was heated under reduced pressure (6.
0 ° C.) to obtain a low molecular weight polymer (1) having hydroxyl groups at both molecular ends.

Production Examples 2b-6b Except that the type and amount of the monomer, the type and amount of the polymerization initiator, and the type and amount of the hydroxyl group-containing monomer were changed as shown in Table 1,
By the same method as in Production Example 1b, low molecular weight polymers (2) to (6) having or not having hydroxyl groups at both molecular terminals were obtained. In each polymerization, the amount of copper bromide used was the same as the molar amount of the polymerization initiator, and the amount of 2,2'-bipyridine was three times the molar amount.

In Table 1, "IBXA" is isobornyl acrylate, "FEA" is phenoxyethyl acrylate, "St" is styrene, and "6-HHA" is 6-hydroxyhexyl. Acrylate. Also,
The numerical value in parentheses in Table 1 means the number of moles (mmol) of each raw material component.

[0048]

Production Example 7b A flask equipped with a stirrer and a condenser was charged with 20 g (156 mmol) of n-butyl acrylate and 80 g (770 mmol) of styrene dissolved in 100 g of toluene and charged as a polymerization initiator. 0.1 g of AIBN and 2 g of 2-mercaptoethanol as a chain transfer agent were added, and the reaction system was heated to 60 ° C. under a nitrogen stream to carry out polymerization. Thus, a low molecular weight polymer (7) was obtained.

The glass transition temperatures of the low molecular weight polymers (1) to (7) produced according to Production Examples 1b to 7b were as shown in Table 2. The results of measurement of the number average molecular weight [Mn], the weight average molecular weight [Mw], and the degree of polymer dispersion [Mw / Mn] were as shown in Table 3. The molecular weight was measured by the GPC method described in the text.

[0051]

[0052]

Comparative Production Example 1c A low molecular weight polymer (8) was prepared in the same manner as in Production Example 1b except that 50 g (271 mmol) of 2-ethylhexyl acrylate was used instead of isobornyl acrylate. ) Was manufactured. This low molecular weight polymer (8) has a glass transition temperature [Tg] of -69 ° C and a number average molecular weight [Mn] of 6,000.
0, the weight average molecular weight [Mw] was 13,900, and the degree of dispersion of the polymer [Mw / Mn] was 2.3.

Comparative Production Example 2c A low molecular weight polymer (9) was prepared in the same manner as in Production Example 1b except that 50 g (390 mmol) of n-butyl acrylate was used instead of isobornyl acrylate. Manufactured. This low molecular weight polymer (9) has a glass transition temperature [T
g] is -58 ° C, the number average molecular weight [Mn] is 7,400,
The weight average molecular weight [Mw] was 13,700, and the degree of polymer dispersion [Mw / Mn] was 1.9.

Example 1 A-B type block copolymer (1) produced in Production Example 1a
5 g and 1 g of the low molecular weight polymer (1) prepared in Preparation Example 1b were diluted with 3 milliliters of ethyl acetate, 2 g of a 1% by weight solution of dibutyltin dilaurate in toluene as a crosslinking catalyst, and trimethyloyl as a crosslinking agent. Toluene was added with 2 g of a 10% by weight toluene solution of tolylene diisocyanate adduct of lupropane, and uniformly mixed to prepare a pressure-sensitive adhesive composition. Next, this adhesive composition was applied on a polyethylene terephthalate film having a thickness of 25 μm,
The resultant was dried by heating at 0 ° C. for 5 minutes and at 50 ° C. for 16 hours to form an adhesive composition layer having a thickness of 50 μm, thereby obtaining an adhesive sheet.

Examples 2 to 5 Types and Use Ratios of Low Molecular Weight Polymer [Block Copolymer
(1) Number of parts by weight of low molecular weight polymer per 100 parts by weight]
Was changed as shown in Table 4, and an adhesive composition was prepared and an adhesive sheet was prepared in the same manner as in Example 1.

Comparative Example 1 AB block copolymer (1) produced in Production Example 1a
Low molecular weight polymer produced in Production Example 1b
Except not using (1), the same as in Example 1,
An adhesive composition was prepared and an adhesive sheet was prepared.

Comparative Examples 2 and 3 Types and Use Ratios of Low Molecular Weight Polymer [Block Copolymer
(1) Number of parts by weight of low molecular weight polymer per 100 parts by weight]
Was changed as shown in Table 4, and an adhesive composition was prepared and an adhesive sheet was prepared in the same manner as in Example 1.

[0059]

Example 6 ABA block copolymer prepared in Preparation Example 2a
(2) 5 g of the low molecular weight polymer produced in Production Example 2b (2) 1
and 3 g of ethyl acetate, and 2 g of a 1% by weight solution of dibutyltin dilaurate in toluene as a crosslinking catalyst, and 10% by weight of toluene in a tolylene diisocyanate adduct of trimethylolpropane as a crosslinking agent. 2 g of the solution was added and uniformly mixed to prepare a pressure-sensitive adhesive composition. Next, the pressure-sensitive adhesive composition was applied to a thickness of 25 μm
Of polyethylene terephthalate film
The resultant was dried by heating at 120 ° C. for 5 minutes and at 50 ° C. for 16 hours to form an adhesive composition layer having a thickness of 50 μm, thereby obtaining an adhesive sheet.

Examples 7 to 10 Types of Low-Molecular-Weight Polymers and Their Ratios [Block Copolymers]
(2) Number of parts by weight of low molecular weight polymer per 100 parts by weight]
Was changed as shown in Table 5, and a pressure-sensitive adhesive composition was prepared and a pressure-sensitive adhesive sheet was prepared in the same manner as in Example 6.

Comparative Example 4 ABA block copolymer prepared in Production Example 2a
A pressure-sensitive adhesive composition was prepared and a pressure-sensitive adhesive sheet was prepared in the same manner as in Example 6, except that only (2) was used and the low-molecular-weight polymer (2) prepared in Production Example 2b was not used. Went.

Comparative Examples 5 and 6 Types and Use Ratios of Low Molecular Weight Polymer [Block Copolymer
(2) Number of parts by weight of low molecular weight polymer per 100 parts by weight]
Was changed as shown in Table 5, and a pressure-sensitive adhesive composition was prepared and a pressure-sensitive adhesive sheet was prepared in the same manner as in Example 6.

[0064]

The above Examples 1 to 10 and Comparative Examples 1 to 6
The adhesive force and cohesive force (creep) of each of the adhesive sheets were measured by the following methods. The results of these measurements were as shown in Table 6.

<Adhesive Strength> The adhesive sheet is 20 mm wide and 1 long.
A stainless plate and a polypropylene plate (P) polished with a # 280 sandpaper using this as an adherend.
(P board), a rubber roller weighing 2 kg was reciprocated and pressed back and forth, left at 23 ° C. for 20 minutes, and peeled 180 ° at a tensile speed of 300 mm / min in an atmosphere of 23 ° C. and 65% RH. The force required for peeling was measured and defined as the adhesive force.

<Cohesion> Adhesive sheet was 10 mm wide and 2 mm long.
It is bonded to a phenol resin plate with an adhesive area of 0 mm, left at 40 ° C. for 20 minutes, and then the phenol resin plate is hung down to obtain an adhesive sheet.
A uniform load of 500 g was applied to the free end of the sheet, and the time required for the adhesive sheet to fall at 40 ° C. and the displacement distance (fall distance) per hour were measured. It is generally known that the smaller the displacement distance, the higher the cohesive force.

[0068]

As is clear from Table 6 above, each of the adhesive sheets of Examples 1 to 5 in which an AB type block copolymer was used as a main component and a specific low molecular weight polymer was mixed with the block copolymer, In each case, the cohesive force was satisfied and a higher adhesive strength was obtained as compared with the pressure-sensitive adhesive sheet of Comparative Example 1 in which the low-molecular-weight polymer was not mixed.
It can be seen that high adhesiveness was also obtained with respect to (plate). On the other hand, in the case of both pressure-sensitive adhesive sheets of Comparative Examples 2 and 3 in which a low molecular weight polymer different from that of the present invention was mixed, the cohesive force was greatly reduced and the adhesive force was also low.

Similarly, each of the pressure-sensitive adhesive sheets of Examples 6 to 10 in which an ABA type block copolymer was used as a main component and a specific low molecular weight polymer was mixed, Compared with the pressure-sensitive adhesive sheet of Comparative Example 4 in which the low-molecular-weight polymer is not mixed, the adhesive sheet satisfies the cohesive force and has a higher adhesive strength. It is clear that high adhesion is obtained. On the other hand, in the case of both pressure-sensitive adhesive sheets of Comparative Examples 5 and 6 in which a low molecular weight polymer different from that of the present invention was mixed, the cohesive force was significantly reduced and the adhesive force was also lowered.

[0071]

As described above, the present invention relates to a non-elastomeric polymer block A comprising a styrenic polymer or the like.
And a block copolymer of an elastomeric polymer block B composed of a (meth) acrylate polymer and at least two block bonds, such as AB type or AB type.
-Block copolymer of A type is produced by a living radical polymerization method using no solvent or a small amount of a solvent, and by using this as a main component, a specific low-molecular-weight polymer is further mixed therewith. Without the conventional problems of safety and economy, in addition to the effect of improving light resistance based on the introduction of a (meth) acrylate-based polymer, it exhibits improved adhesive properties, especially polyethylene and The present invention can provide a pressure-sensitive adhesive composition having high adhesiveness to a low-polarity polyolefin-based adherend such as polypropylene, a method for producing the same, and pressure-sensitive adhesive sheets.

Continued on the front page (72) Inventor Michiharu Yamamoto 1-1-2 Shimohozumi, Ibaraki-shi, Osaka Nitto Denko Corporation (72) Inventor Tomoko Doi 1-1-2 Shimohozumi, Ibaraki-shi, Osaka Nitto Denko In-house F-term (reference) 4J004 AA07 AA10 CA01 CA02 CA08 CB01 CB02 CB04 CC02 CC03 FA06 FA08 FA09 4J040 DB042 DF032 DF042 DM001 GA07 GA08 GA13 GA15 GA17 GA22 HB31 HD43 JA09 JB09 KA11 LA01 LA02 LA06 LA07 MA06 NA01 NA05

Claims (5)

[Claims] 1. A) a non-elastomeric polymer block A having a glass transition temperature of 20 ° C. or more, and (meth) acrylic acid
Number-average molecular weight of 1 obtained by bonding at least 2 blocks with an elastomeric polymer block B composed of
5,000 to 200,000 block copolymers,
b) A pressure-sensitive adhesive composition comprising a low molecular weight polymer having a number average molecular weight of 1,000 to 10,000 having a glass transition temperature in the range of 0 to 160 ° C. 2. The block copolymer of component (a) is an AB type or ABA type block copolymer.
The pressure-sensitive adhesive composition according to item 1. 3. A polymer which gives a non-elastomeric polymer having a glass transition temperature of 20 ° C. or higher and a (meth) acrylate monomer are polymerized in the presence of a transition metal and its ligand. Using an initiator, a living radical polymerization is carried out in an appropriate monomer sequence, and a) an elastomer comprising a non-elastomer polymer block A having a glass transition temperature of 20 ° C. or higher and a (meth) acrylate polymer. A block copolymer having a number average molecular weight of 15,000 to 200,000, which is formed by bonding at least two blocks with the functional polymer block B, has a glass transition temperature in the range of 0 to 160 ° C. A method for producing a pressure-sensitive adhesive composition, comprising mixing a low-molecular-weight polymer having a number average molecular weight of 1,000 to 10,000. 4. The combination of a transition metal and a ligand is Cu ⁺¹
The method for producing a pressure-sensitive adhesive composition according to claim 3, which is a bipyridine complex. 5. An adhesive sheet comprising a support and a layer comprising the pressure-sensitive adhesive composition according to claim 1 provided on a support.