WO2008035709A1

WO2008035709A1 - Solvent-type removable adhesive composition and removable adhesive product

Info

Publication number: WO2008035709A1
Application number: PCT/JP2007/068181
Authority: WO
Inventors: Masahiko Saito; Shigeru Oka
Original assignee: Nippon Shokubai Co., Ltd.
Priority date: 2006-09-21
Filing date: 2007-09-19
Publication date: 2008-03-27
Also published as: TW200833801A; KR20090037950A; TWI390000B; KR101073098B1

Abstract

Disclosed is a solvent-type removable adhesive composition which comprises a high-Tg polymer (A) having a glass transition temperature (Tg) of 0˚C or higher, a low-Tg polymer (B) having a Tg lower than that of the high-Tg polymer and also having a pressure-sensitive adhesion property, and a solvent. In an adhesive layer produced by using the adhesive composition, the high-Tg polymer (A) and the low-Tg polymer (B) are not dissolved in each other and form a sea-island structure, wherein the high-Tg polymer (A) forms an island phase and the low-Tg polymer (B) forms a sea phase. The composition enables to form an adhesive layer having an excellent high-speed peeling property when used as a surface protection film for an optical film.

Description

Specification

Solvent-type re-peeling pressure-sensitive adhesive composition and re-peeling pressure-sensitive adhesive product

Technical field

[0001] The present invention relates to a re-peeling adhesive product that is re-peeled after being attached to an adherend and then peeled again, and exhibits excellent peelability even at high-speed peeling, and the adhesive product is produced. The present invention relates to a solvent-type pressure-sensitive adhesive composition. More specifically, the present invention relates to a re-peeling adhesive product for protecting the surface of optical members such as optical polarizing plates (TAC), retardation plates, EM 1 (electromagnetic wave) shield films, antiglare films, antireflection films, etc. Is.

Background art

[0002] For liquid crystal displays and plasma displays, optical films having various functions, such as optical polarizing plates (TAC), retardation plates, EMI (electromagnetic wave) shield films, antiglare films, antireflection films, etc. Etc. are laminated and used. These optical films have a protective film affixed to the surface in order to prevent damage to the surface during the display manufacturing process and performance inspection stage. Stripped and removed in the panel assembly process.

[0003] As a surface protective film, it is necessary not only to prevent performance inspection, but also to have an adhesive property that does not allow stagnation of bubbles and the like, and to increase adhesion after being applied to an adherend. It is necessary that there is no adhesive residue on the adherend. Furthermore, recently, as the size of the display has increased, the protective film has also increased in area, so that the peeling process has been mechanized, and as a result, it has become an important required characteristic that high-speed peeling by a machine is possible.

[0004] However, as the peeling speed increases, the peeling force (adhesive force) tends to increase, which places a heavy load on the peeling machine. In addition, when peeling off, a part that peels off smoothly and a part that does not peel off easily occur, and the phenomenon of peeling while making a buzzing sound (zibbing peeling) occurs, and the optical film surface is damaged or broken. I had a problem.

[0005] For this reason, many attempts have been made to improve the high-speed peelability of the protective film! For example, Japanese Patent Application Laid-Open No. 2005-146151 discloses a high Tg (meth) atari which has no adhesiveness at room temperature. By blending a low molecular weight polymer with a low Tg (meth) acrylic polymer with sufficient adhesive strength, there is no lifting or peeling (having a certain level of adhesiveness), and high-speed peelability is good. Further, a pressure sensitive adhesive for a protective film is disclosed.

[0006] The adhesive product for the protective film as described above is designed to have a considerably lower adhesive strength (slight adhesion) than a general adhesive product on the premise that it is peeled off. However, if the Tg of the high τg polymer is too high, it is inherently at a low level of adhesive strength, so that the adhesiveness at low temperatures is almost lost or the crosslinking progresses over time and sticks to the adherend. It sometimes caused the inconvenience of not sticking.

[0007] In general, different types of polymers are incompatible even with a few! /, Except for exceptions, and even the same (meth) acrylic polymer causes phase separation. Such a poorly compatible pressure-sensitive adhesive has a large haze when formed into a coating film, and may be unsuitable as a protective film for optical applications. Furthermore, when the pressure-sensitive adhesive composition is diluted with a solvent to a viscosity suitable for coating to produce a protective film, it becomes easier to separate, and the pressure-sensitive adhesive composition phase-separates on standing for about 1 day. There was a problem that it was necessary to carry out stirring and mixing again, or it could not be used.

[0008] Further, if the pressure-sensitive adhesive product is peeled off from the adherend under severe conditions, adherend contamination may occur in which part of the pressure-sensitive adhesive remains on the adherend, and improvement in removability is required. It was done. In addition, there was room for improvement in terms of conformability (wettability) to the adherend.

[0009] Therefore, in the present invention, for the purpose of being applied to the surface protective film of an optical film, the pressure-sensitive adhesive is excellent in high-speed peelability and has low haze and hardly causes troubles such as adherend contamination. A solvent-type re-peeling pressure-sensitive adhesive composition capable of forming a layer was found, and an object was to provide a re-peeling pressure-sensitive adhesive product having good characteristics.

Disclosure of the invention

[0010] The solvent-based re-peeling pressure-sensitive adhesive composition of the present invention has a high Tg polymer (A) having a glass transition temperature (Tg) of o ° c or higher and a Tg lower than this high Tg polymer, A solvent-type re-peeling pressure-sensitive adhesive composition containing a low-Tg polymer (B) exhibiting pressure adhesion and a solvent, wherein a high-Tg polymer (A) and a low Tg are used in the pressure-sensitive adhesive layer obtained from the pressure-sensitive adhesive composition. Sea-island structure where high Tg polymer (A) is an island and low Tg polymer (B) is the sea without polymer (B) being compatible with each other It has a special feature!

[0011] The pressure-sensitive adhesive product for re-peeling of the present invention is characterized in that a pressure-sensitive adhesive layer obtained from the solvent-based re-peeling pressure-sensitive adhesive composition is formed on at least one side of a support substrate. ing.

Brief Description of Drawings

FIG. 1 is an SEM photograph (sea-island structure) of a coating film of an adhesive polymer solution obtained in Synthesis Example 1. BEST MODE FOR CARRYING OUT THE INVENTION

[0013] First, the solvent-based re-peeling pressure-sensitive adhesive composition according to the present invention will be described. However, the scope of the present invention is not limited to these descriptions, and the present invention is not limited to the following examples. Changes can be made as appropriate without departing from the spirit of the invention. The solvent-type re-peeling pressure-sensitive adhesive composition of the present invention becomes a pressure-sensitive adhesive product by drying (removing the solvent), and has a 180 ° adhesive strength in low-speed peeling against an acrylic plate measured under the conditions described later. Refers to the case of 10N / 25mm or less. The “polymer” in the present invention includes not only homopolymers but also copolymers and copolymers of three or more. The “monomer” of the present invention is an addition polymerization type monomer.

[0014] First, the first essential component in the solvent-based re-peeling pressure-sensitive adhesive composition of the present invention is a high Tg polymer (A) having a glass transition temperature (Tg) of 0 ° C or higher. The presence of this high Tg polymer (A) suppresses the increase in the high speed peel force.

Here, the Tg of the polymer can be determined by DSC (Differential Scanning Calorimetry), DTA (Differential Thermal Analysis), and TMA (Thermomechanical Measurement). In addition, since the Tg of homopolymers is described in various literatures (for example, polymer handbooks), the Tg of copolymers is calculated from the following formula using Tg (K) of various homopolymers and mass fraction (W) of monomers. Finding what you want.

[0016] In [Equation 1], w ₂

Tg T _gl Tg ₂

[0017] where W is the mass fraction of each monomer.

Tg: Tg (K) of homopolymer of each monomer

The Tg of the main homopolymer is 105.85 ° C for polyacrylic acid, 9.85 ° C for polymethyl acrylate, 24.15 ° C for polyethyl acrylate, and poly n butyl acrylate. -54.15 ° C, Poly-2-Hethinoreta Talelate (70.00 ° C, Poly-2Hydroxyethylaretalate) 85 ° C, poly 4-hydroxybutyl attalate is 3 · 00 ° C, polymethylmetatalylate is 104 ° 85 ° C: Polyacetate, Ninole, 30. 00 ° C :, Polybenzenore 6. 00 ° C: 125 ° C for Polynitronitroré and 100 ° C for Polystyrene.

[0018] The high Tg polymer (A) used in the present invention is not particularly limited as long as Tg is 0 ° C or higher, and may be a homopolymer or a polymer obtained by copolymerizing two or more monomers. In order to further improve the high-speed peelability, Tg is preferably 10 ° C or higher, more preferably 20 ° C or higher, and further preferably 30 ° C or higher. However, if the Tg of the high Tg polymer (A) is too high, although it may be a slightly adhesive type for re-peeling, the adhesive strength may be insufficient, so less than 80 ° C is preferred 75 ° C or less The preferred temperature is 70 ° C or less.

[0019] The high Tg polymer (A) of the present invention is an essential component for improving the high-speed peelability. However, as a second problem, a case where importance is attached to haze and a case where importance is placed on suppression of adherend contamination. And the preferred composition is different. Thus, the high Tg polymer when haze is emphasized is (A-1), and the high Tg polymer when emphasis is placed on adherend contamination control is (A-2).

[0020] (1) High-Tg polymer when haze is important (A—1)

In order to reduce the haze of the pressure-sensitive adhesive layer obtained from the pressure-sensitive adhesive composition of the present invention, the high Tg polymer (A-1) has units derived from butyl acetate! /. The refractive index of the butyl acetate polymer and the refractive index of the (meth) acrylate polymer (particularly a polymer containing 2-ethylhexyl acrylate or butyl acrylate), which is the main component of the low Tg polymer (B). This is because the haze is reduced because of the approximation. Therefore, the high Tg polymer (A-1) is preferably obtained from a raw material monomer having 70% by mass or more of butyl acetate. The amount of butyl acetate is more preferably 90% by mass or more. Most preferred in terms of haze The high Tg polymer (A-1) is poly (butyl acetate) (bule acetate homopolymer). If polyacetic acid bule is used as a high Tg polymer (A-1), the haze of the resulting adhesive layer can be reduced to 2% or less, and surface protection of optical films that require high transparency is required. It is suitable as a film.

[0021] In the case of a high Tg polymer (A-1) that is not a butyl acetate homopolymer, the homopolymer has a high Tg. (Meth) acrylic acid, methyl (meth) acrylate, ethyl (meth) acrylate, acrylate, styrene Etc. are preferably used in combination with butyl acetate. Monomers that can be used as raw material monomers for the low Tg polymer (B) described below can also be used if the type and amount are selected so that the Tg of the high Tg polymer (A-1) is 0 ° C or higher. .

[0022] (2) High Tg polymer when importance is placed on the suppression of adherend contamination (A-2)

In order to suppress adherend contamination, it is preferable to introduce a functional group having reactivity with a crosslinking agent to be added later into the high Tg polymer (A-2). By crosslinking the high Tg polymer (A-2), the high Tg polymer (A-2) having a relatively low molecular weight that causes adherend contamination is increased in molecular weight, thereby suppressing adherend contamination. Examples of the functional group include a hydroxyl group, a carboxyl group, an amino group, an amide group, and an epoxy group.

In order to introduce the functional group into the high Tg polymer (A-2), a functional group-containing monomer may be used as a raw material monomer for the high Tg polymer (A-2). Examples of functional group-containing monomers include 2-hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, 4-h

Hydroxyl group-containing (meth) acrylates such as mono (meth) acrylate of polyester diol that can also be used with taric acid and propylene glycol; unsaturated carboxylic acids such as (meth) acrylic acid, cinnamate and crotonic acid; Unsaturated dicarboxylic acids such as maleic acid, fumaric acid, itaconic acid and citraconic acid; carboxy group-containing monomers such as monoesters of these unsaturated dicarboxylic acids; amino groups, amide groups, epoxy groups, etc. And meta) atarylates.

Of the above, hydroxyl group-containing (meth) acrylates having a hydroxyl group as a functional group are preferred. In particular, when the hydroxyl group is separated from the (meth) attalyloyl group The monomers in this group have better cross-linking reactivity and conformability, so if you want to reduce the amount of cross-linking agent or if suitability for adherends is important, 2-hydroxyethyl (meth) atari The hydroxyl group is bonded to an alkyl group having a larger number of carbon atoms than the rate (propyl group or higher)! /, And (meth) acrylate (eg, 4-hydroxy pentanol (meth) acrylate) is used. preferable.

[0025] These functional group-containing monomer, in the raw material monomer 100 mass ^_0/0 of the high Tg polymer (A- 2), 0.; is preferably set to 1-10% by mass!. If the amount of the functional group-containing monomer is less than 0.1% by mass, the amount of the functional group in the high Tg polymer (A-2) is decreased, and the effect of suppressing adherend contamination is not sufficiently exhibited. Absent. On the other hand, if it exceeds 10% by mass, the adhesive strength of the adhesive and the wettability to the adherend tend to decrease, which is not preferable. The amount of the functional group-containing monomer is more preferably 0.3 to 8% by mass, and further preferably 0.5 to 6% by mass.

[0026] As the copolymerization partner of the functional group-containing monomer, any known radical polymerizable monomer can be used as long as the Tg of the high Tg polymer (A-2) is 0 ° C or higher. However, as described in the high-Tg polymer (A-1), the use of butyl acetate reduces the haze of the adhesive layer and is suitable as a surface protective film for optical films. Therefore, the high Tg polymer (A-2) is preferably obtained from a raw material monomer that necessarily contains butyl acetate and the functional group-containing monomer. In this case, acetic acid vinyl Honoré (or 70 to 99.9 mass ^_0/0 Ca Preferably, 80 to 99. More preferably 9 mass ^_0/0 Ca, more preferably 90 to 99.9 mass%.

[0027] Methyl acrylate may be used as a copolymerization partner for the functional group-containing monomer. Adhesiveness and familiarity are improved. Methyl acrylate is preferably 70-99.9% by weight, more preferably 80-99.9% by weight, and more preferably 90-99.9% by weight.

[0028] When a methyl acrylate high Tg polymer (A-2) is used, it is preferable to use a monomer for controlling the refractive index as a raw material monomer for the low Tg polymer (B) described later! The haze of the obtained pressure-sensitive adhesive layer can be reduced. Refractive index control monomer is a monomer used to bring the refractive index of a low Tg polymer close to that of a high Tg polymer. For example, when high-Tg polymer (A-2) is synthesized from methyl acrylate and hydroxyl group-containing monomarker, it is added to 2-ethyl hexyl acrylate, butyl acrylate and 2-hydroxyethyl acrylate. By selecting benzyl acrylate as the raw monomer of the low Tg polymer (B), the refractive index of the high Tg polymer (A-2) and that of the low Tg polymer (B) can be brought close to each other. The haze can be reduced to 3% or less.

[0029] For the synthesis of high Tg polymer (A-2), other monomers that can be used in addition to butyl acetate, methyl acrylate, and the above functional group-containing monomers include (meth) acrylic acid having a high homopolymer Tg, Methyl methacrylate, ethyl (meth) acrylate, acrylonitrile, styrene and the like are preferable. A monomer that can be used as a raw material monomer for the low Tg polymer described below can also be used if the type and amount are selected so that the Tg of the high Tg polymer (A-2) is 0 ° C or higher. A preferred embodiment of the high Tg polymer (A-2) is a polymer synthesized from butyl acetate and 2-hydroxyethyl acrylate and / or 4-hydroxybutyl acrylate. The ability to reduce haze to 3% or less while suppressing adherend contamination. Further, as described above, if a monomer for controlling the refractive index is used during the synthesis of the low Tg polymer (B), it is synthesized from methyl acrylate and 2-hydroxyethyl acrylate and / or 4-hydroxy butyl acrylate. High Tg polymer (A-2) can also be preferably used because haze can be reduced to 3% or less while suppressing adherend contamination.

[0030] If the refractive index of a typical homopolymer is shown, polyacrylic acid is 1 · 5270, polymethyl phthalate 1, 4720, polyurethane tantalate 1, 4685, poly η-f, chinoleate talate m 4660, polymethylolene methacrylate 1 4900, poly-2-hydroxyhexylene chloride m. 4650, poly-2-hydroxyethylenol talelate (1/4480, poly-2-hydroxyethyl methacrylate) (MA 1.5119, poly 4-hydroxyph, chinolea talylate (MA 1.4520, poly oxalate, Nino acrylate 1. 4665, polybenzeno acrylate 1.5 or 5132.

[0031] If the haze and adherend contamination are not important, the homopolymer has a high Tg, such as (meth) acrylic acid, methyl methacrylate, ethyl (meth) acrylate, acrylonitrile, styrene, etc. What is necessary is just to comprise a high Tg polymer (A) so that the said Tg range may be satisfied.

[0032] The molecular weight of the high Tg polymer (A) (hereinafter, simply referred to as high Tg polymer (A) means both high Tg polymer (A-1) and high Tg polymer (A-2)). , Mass average molecular weight ( Mw) is preferably from 2000 to about 100,000. More preferably, it is about 40,000 to 90,000.

[0033] The second essential component contained in the solvent-based re-peeling pressure-sensitive adhesive composition of the present invention is a low Tg polymer (B) exhibiting pressure-sensitive adhesiveness. This low Tg polymer (B) is required to be lower than the Tg (0 ° C or higher) of the above high Tg polymer (A), and Tg force S0 ° Preferably it is less than C. More preferably, it is 1-20 ° C or less, and further preferably 135 ° C or less. However, if the Tg of the low Tg polymer (B) is lower than -80 ° C, the cohesive force tends to decrease, and the adhesive residue tends to occur.

[0034] To obtain this low Tg polymer (B), an alkyl (meth) acrylate and a high Tg polymer (A

It is preferable to use a combination of the functional group-containing monomers described in 2). The alkyl (meth) acrylate is necessary for ensuring adhesive strength, and the functional group-containing monomer is a monomer for introducing a functional group for reacting with a crosslinking agent described later into the low Tg polymer (B). As the functional group-containing monomer, any of the monomers exemplified for the high Tg polymer (A-2) can be used. As in the case of the high Tg polymer (A-2), the hydroxyl group-containing monomer (meth) Atallate is preferred. Further, the use amount thereof is preferably from 0.;! To 10% by mass in 100% by mass of the raw material monomer as in the case of the high Tg polymer (A-2). When the amount of the functional group-containing monomer is less than 0.1% by mass, the amount of the functional group in the low Tg polymer (B) is decreased, the speed of the crosslinking reaction is decreased, or the high-speed adhesive force is too high. If it exceeds 20% by mass, the adhesive strength of the pressure-sensitive adhesive and the wettability to the adherend tend to decrease, such being undesirable. The use amount of the functional group-containing monomer is more preferably 0.3 to 8% by mass, and further preferably 0.5 to 6% by mass.

[0035] The alkyl (meth) acrylate which is the main constituent of the low Tg polymer (B) preferably has an alkyl group having a carbon number power of ~ 12 from the viewpoint of adhesive properties. This carbon number is preferably 4 to 10; more preferably 4 to 8. If the carbon number is less than 4 (3 or less), or exceeds 12 (13 or more), the adhesive strength may decrease. Specifically, n butyl (meth) acrylate, isobutyl (meth) acrylate, sec butyl (meth) acrylate, tert butyl (meth) acrylate, amino acrylate (meth) acrylate, isoamino acrylate (meth) acrylate , Hexyl (meth) acrylate, cyclohexyl (meth) acrylate, heptyl (me Examples include ruhexyl (meth) acrylate, nonyl (meth) acrylate, isononyl (meth) acrylate, decyl (meth) acrylate, dodecyl (meth) acrylate, butyl acrylate, 2-ethyl Hexyl acrylate, octyl acrylate and isooctyl acrylate are more preferred. These may be used alone or in combination of two or more, and are not limited.

[0036] In 100% by mass of the raw material monomer of the low Tg polymer (B), the above alkyl having 4 to 12 carbon atoms

(Meth) Atari rate is preferably employed in the range of 50-99. 9 mass ^_0/0. More preferably «60-99. 7 mass ^_0/0, even more preferably 70 to 99 · 5 weight ^_0/0. Anolequinolate (meth) If the amount of attalylate used is within the above range, the resulting adhesive exhibits sufficient adhesive strength and tackiness, but if it is less than 50% by mass, the adhesive strength and adhesion are reduced. The wettability to the body may be insufficient, and if it exceeds 99.9% by mass, the amount of the functional group-containing monomer that becomes a cross-linking point is too small, and the high-speed adhesive force may become too large.

[0037] In the synthesis of the low Tg polymer (Β), other monomers may be copolymerized.

The other monomer is a monomer that can be copolymerized with the alkyl (meth) acrylate and the functional group-containing monomer, and other monomers. For example, the above-described alkyl (methacyclic ring-containing (meth) acrylates; halogen-substituted aliphatic unsaturated hydrocarbons such as ethylene and butadiene, and aliphatic unsaturated hydrocarbons such as butyl chloride; styrene and α-methyl Aromatic unsaturated hydrocarbons such as styrene; Bull esters such as butyl acetate; Bull ethers; Esters of allylic alcohol and various organic acids; Ethers of allylic alcohol and various alcohols; Unsaturated such as acrylonitrile cyanide compound;.. etc. these may be used alone in combination of two or more not Yogu limit Jowa the other monomers, raw monomer 100 mass ^_0/0 in 0 to 49.9% by mass is preferable 49. When the content exceeds 9% by mass, the result is that the amount of alkyl (meth) acrylate or functional group-containing monomer is small. Because, the desired adhesive properties can not be obtained. More preferred correct upper limit is 40 mass%, still more preferred upper limit is 30 mass%.

[0038] The most preferred low Tg polymer (B)! /, Embodiments, if the high Tg polymer (A) contains acetic acid Byuruyu knit as the main component (70 mass ^_0/0 or more), 2- Echiru Hexyl Relay And a polymer obtained from a raw material monomer mixture containing butyl acrylate, 2-hydroxyethyl acrylate and / or 4-hydroxy butyl acrylate. This polymer has good adhesive properties and is close to the refractive index of high Tg polymer (A), the main component of which is a butyl acetate unit, so it can reduce the haze of the resulting adhesive layer. The power that can be S. When the total of 2-ethyl hexyl acrylate, butinorea acrylate and hydroxy acetyl acrylate is 100% by mass, 2-ethyl hexyl acrylate is 20 to 80% by mass, and butyl acrylate is 20%. The total content of ˜80 mass%, hydroxyethyl acrylate and 4-hydroxybutyl acrylate is preferably 0.5 to 6 mass%. Of course, other monomers can be used in combination as described above. However, when the high Tg polymer is a high Tg polymer (A-1), 2-ethylhexyl acrylate, butyl acrylate and hydroxy Monomers other than ethyl acrylate and 4-hydroxybutyl acrylate are preferably 10% by mass or less.

[0039] On the other hand, when a high Tg polymer (A) force is, for example, a methyl acrylate unit as a main component, the most preferred embodiment of the low Tg polymer (B) is 2-ethyl hexyl acrylate and butyrate. This is a copolymer of noreatalylate, 2-hydroxyethyl acrylate and / or 4-hydroxybutyl acrylate and benzyl acrylate. As described above, the haze of the pressure-sensitive adhesive layer can be reduced to 3% or less by using benzyl acrylate in combination. The sum of these monomers is 100 mass%, 2 Echiru hexyl Atari rate from 20 to 80 weight ^_0/0, butyl Atari rate from 20 to 80 weight ^_0/0, hydroxy E chill Atari rate and 4 over hydroxybutyl Atari rate from 0.5 to 6 weight in total ^_0/0, benzyl Atari Les chromatography DOO is preferably 5 to 20 wt%.

[0040] The low Tg polymer (B) preferably has an Mw of 200,000 or more from the viewpoint of improving the adhesive properties. When the two-stage polymerization method described later is adopted, the molecular weight of only the low Tg polymer (B) cannot be measured, but a mixture of the high Tg polymer (A) and the low Tg polymer (B) (Draft product). The total Mw is preferably 100,000 to 700,000. A more preferable Mw range is 150,000 to 650,000, and a more preferable Mw range is 200,000 to 600,000.

[0041] The high Tg polymer (A) and the low Tg polymer (B) are incompatible because of different Tg and different compositions. In the present invention, the high Tg polymer (A) and the low Tg polymer (B) do not form a sea-island structure. I have to. The sea-island structure is in a microphase-separated state, and the larger amount is the sea (continuous phase). In the present invention, the amount of the low Tg polymer (B) is increased to disperse the low Tg polymer (B) as sea (continuous phase) and the high Tg polymer (A) as islands. Due to the action of the high Tg polymer (A) dispersed in islands, an increase in the adhesive force during high-speed peeling can suppress the jbbing phenomenon. In order to exert this effect, the content of the high Tg polymer (A) is required to be 1% by mass or more, and if it is less than this, the above effect will be insufficient. More preferably, it is 3% by mass or more, and further preferably 4% by mass or more. However, if the amount is too large, adhesive strength and wettability to the adherend may be insufficient.

[0042] As to whether or not the sea-island structure is expressed, the pressure-sensitive adhesive layer obtained by applying and drying the pressure-sensitive adhesive composition was measured using an optical microscope, a transmission electron microscope, a scanning electron microscope, a phase difference, and the like. By observing with a microscope, polarizing microscope, scanning tunneling microscope, microscope Raman, etc., it is possible to determine the presence or absence of a sea-island structure. The preferred form of the sea-island structure is such that the island-like portions are almost spherical and dispersed in the continuous phase (sea), and the average diameter of each island-like substance is about 0.;! To 10 m. The presence or absence of such a sea-island structure can also be observed using an optical microscope, a phase contrast microscope, and a polarizing microscope.

[0043] In order to confirm that the pressure-sensitive adhesive layer is obtained from a pressure-sensitive adhesive composition containing two types of polymers, for example, by measuring the dynamic viscoelasticity tan δ, Tg is 2 Check if they are observed. The tan δ of the dynamic viscoelasticity is obtained by, for example, using a rheometer (manufactured by TI-A Instruments Co., Ltd .; “ARES”) and by using the shear mode, paraplate method (8 mm φ), the angular vibration frequency 6. / s, measuring temperature range 50 ~;

[0044] In the present invention, a high-Tg polymer (A) and a low-Tg polymer (B) having an approximate refractive index are used, and a sea-island structure in which both are phase-separated microscopically has a haze of 3% or less. Adhesive products with excellent transparency can be obtained. The smaller the haze, the better the power to use a high Tg polymer (A-1), and the use of a refractive index control monomer when synthesizing a low Tg polymer (B) can reduce the haze to 2.5% or less. The haze can be measured, for example, with a turbidimeter. In addition, the haze of this invention employ | adopts the measured value in the state of the adhesive product which provided the adhesive layer in transparent films (support base material), such as a polyethylene terephthalate, for example. Next, the method for producing the solvent-type re-peeling pressure-sensitive adhesive composition of the present invention will be described. There are three types of suitable manufacturing methods. First, the blending method is a method in which a high Tg polymer (A) and a low Tg polymer (B) are polymerized separately, and then both are mixed (blended). The polymerization method is not particularly limited, but solution polymerization is simple. If the high Tg polymer (A) and the low Tg polymer (B) are polymerized with the same or compatible solvent, they can be blended in solution, eliminating the need for a solvent removal step during blending. Convenient. When blending, it is preferable to stir at high speed with a disperser or the like to form a sea-island structure. When the pressure-sensitive adhesive composition of the present invention is prepared by a blending method, when the total amount of non-volatile components of the high Tg polymer (A) and the low T g polymer (B) is 100% by mass, the high Tg polymer (A) The amount is preferably 4 to 20% by mass. In this method, when the high Tg polymer (A) is dispersed in the low Tg polymer, the amount of the high Tg polymer (A) can be reduced because a clear sea-island structure is adopted.

[0046] The second method is a two-stage polymerization method. In this two-stage polymerization method, all the monomers for the high Tg polymer (A) (hereinafter referred to as “monomer (A)”) are polymerized by solution polymerization, and then the high Tg polymer (A) solution In this method, the monomer for low Tg polymer (B) (hereinafter referred to as “monomer (B)”) is polymerized in the presence. The pressure-sensitive adhesive composition obtained by this two-stage polymerization method is more stable than the pressure-sensitive adhesive composition obtained by the blend method (high Tg polymer (A) and low Tg polymer (B) are difficult to separate). Is excellent. This is because when the monomer (B) is polymerized, a part of the polymer is formed such that the low Tg polymer (B) is grafted to the high Tg polymer (A), which has an affinity for both the sea and the islands. It is thought to stabilize the island by exerting its surfactant action. In the pressure-sensitive adhesive layer formed of the pressure-sensitive adhesive composition formed by the two-stage polymerization method, the island diameter is about 0.3 to 10 πι. When the pressure-sensitive adhesive composition is prepared by the two-stage polymerization method, the amount of high Tg polymer (A) when the total amount of non-volatile content of high Tg polymer (A) and low Tg polymer (B) is 100% by mass. The content (including the graft content) is preferably 4 to 35% by mass.

[0047] In the two-stage polymerization method, it is preferable to start adding the monomer (B) to the reaction vessel after the polymerization rate of the monomer (A) reaches about 70 to 95% by mass. This method causes separation during storage of the composition. The polymerization rate (mass%) is determined by the monomer in the reaction vessel It is the ratio of the mass converted to non-volatile content, and can be easily obtained by measuring the non-volatile content. The low Tg monomer (B) is preferably added dropwise to the reactor together with the polymerization initiator. Increase the molecular weight with the force S.

[0048] The separately polymerized high Tg polymer (A) may be added after the two-stage polymerization of the high Tg polymer (A) and the low Tg polymer (B) is completed. The composition of the post-added high Tg polymer (A) is preferably the same as the initially polymerized high Tg polymer (A) from the viewpoint of dispersion stability, but the molecular weight may be different. Furthermore, the effect of reducing the adhesive strength of high-speed peeling appears

[0049] The third method is a combination of the two-stage polymerization method and the post-addition of the high Tg polymer (A). The high Tg polymer (A) to be charged by the two-stage polymerization and the high Tg for post-addition are used. In this method, polymer (A) is polymerized together. A part of the obtained high Tg polymer (A) is charged into a reaction vessel for synthesizing the low Tg polymer (B), and then the monomer (B) is polymerized. This is a two-stage polymerization in a broad sense. Also in this case, it is considered that a graft product in which the low Tg polymer (B) is grafted to the high Tg polymer (A) is formed. This method has the advantage that the high Tg polymer (A) to be charged in the reaction vessel in advance when polymerizing the low Tg polymer (B) and the high Tg polymer (B) to be added later can be polymerized simultaneously.

[0050] In this method, the amount of the high Tg polymer (A) charged during the polymerization of the low Tg polymer (B) is 100% by mass of the total amount of the high Tg polymer (A) and the monomer (B); ! ~ 10% by mass is preferable. Storage stability is improved. After the polymerization of the monomer (B) is completed, the high Tg polymer (A) (including the graft content) out of the total non-volatile content of 100% by mass of the high Tg polymer (A) and the low Tg polymer (B) It is preferable to add the high Tg polymer (A) afterwards so that the amount of the polymer becomes 4 to 35% by mass. The post-addition may be performed immediately after the polymerization of the low Tg polymer (B), but may be any time as long as it is actually mixed with a crosslinking agent and applied. The same applies when post-added by the second-stage polymerization method of the second method described above.

[0051] In any of the above production methods, specific examples of the solvent used in the solution polymerization include aromatic hydrocarbons such as toluene and xylene; aliphatic esters such as ethyl acetate and butyl acetate; Examples include alicyclic hydrocarbons such as cyclohexane; aliphatic hydrocarbons such as hexane and pentane, etc., but are not particularly limited as long as the polymerization reaction is not inhibited. Absent. These solvents may be used alone or in combination of two or more. What is necessary is just to determine the usage-amount of a solvent suitably. The solvent-type re-peeling adhesive composition of the present invention contains a solvent as an essential component, but it is preferable to use the same solvent as the polymerization solvent. This is because the power obtained by the completion of the polymerization is directly used as a raw material for the solvent-type re-peeling pressure-sensitive adhesive composition.

[0052] Reaction conditions such as a polymerization reaction temperature and a reaction time are not particularly limited as long as they are appropriately set according to, for example, the composition and amount of the monomer. Further, the reaction pressure is not particularly limited, and any of normal pressure (atmospheric pressure), reduced pressure and increased pressure may be used. The polymerization reaction is desirably performed in an atmosphere of an inert gas such as nitrogen gas.

[0053] The polymerization catalyst (polymerization initiator) is not limited, but examples thereof include methyl ethyl ketone peroxide, benzoyl peroxide, dicumyl peroxide, t-butyl hydroperoxide, cumene hydride peroxide, t-butyl. Organics such as peroxyctoate, t-butylperoxybenzoate, lauroyl peroxide, trade name "Nyper B MT-K40J (manufactured by NOF Corporation; m mixture of toluoyl peroxide and benzoyl peroxide)" Known compounds such as peroxides, azobisisobutyronitrile, azo compounds such as “ABN-E” [Nippon Hydrazine Kogyo; 2, 2'-azobis (2-methylbutyronitrile)], etc. Things can be used. Also, for example, known molecular weight regulators represented by mercaptans such as dodecyl mercabtan may be used! /.

[0054] It should be noted that the pressure-sensitive adhesive composition obtained by the blend method as the first method and the pressure-sensitive adhesive composition obtained by using the second-stage polymerization method as the second or third method are subjected to the following separation degree check. Can be clearly distinguished. That is, a high-Tg polymer (A), a low-Tg polymer (B), and a solvent are prepared to prepare a solution having a nonvolatile content of 30% by mass, poured into, for example, a test tube and sealed, and then sealed at 25 ° C. What is necessary is just to check the separation state when left for a period of time. If the high-Tg polymer (A) and the low-Tg polymer (B) have a sea-island structure that is easy to phase-separate obtained by the blending method, they will separate after standing for 24 hours. If the obtained sea-island structure is difficult to separate, it will not separate at all in 24 hours! /. The solution prepared by the above method may be cloudy as long as the cloudy state is uniform throughout the solution. After standing for 24 hours under the above conditions, two or more phases with transparent parts appearing at the top and bottom of the liquid column or with different turbidity If it is divided, it is determined that it is “separated”. The mass ratio of the high Tg polymer (A) and the low Tg polymer (B) in the solution is within the above-mentioned preferred range.

[0055] The solvent that can be used for the separation degree check is not particularly limited as long as it is a solvent used at the time of coating, but is not limited to aromatic hydrocarbons such as toluene and xylene; aliphatic esters such as ethyl acetate and butyl acetate. And alicyclic hydrocarbons such as cyclohexane; aliphatic hydrocarbons such as hexane and pentane, and the like. These may be used alone or in admixture of two or more.

[0056] The pressure-sensitive adhesive composition of the present invention preferably contains a crosslinking agent. As the crosslinking agent, a compound having two or more functional groups capable of reacting with a functional group of the high Tg polymer (A) and / or the low Tg polymer (B) is used.

[0057] For example, if the high Tg polymer (A) and / or the low Tg polymer (B) has a hydroxyl group, and the isocyanate compound has a preferred carboxyl group as a crosslinking agent, the isocyanate A compound, an epoxy compound, etc. are preferable. In terms of reactivity, the combination of a hydroxyl group and an isocyanate compound is most preferred.

[0058] Examples of the isocyanate compound include tolylene diisocyanate (TDI), 4,4'-diphenylmethane diisocyanate (MDI), hexamethylene diisocyanate, xylylene, hydrogenated diphenolate. Diisocyanate compounds such as methane diisocyanate, hydrogenated tolylene diisocyanate, hydrogenated xylylene diisocyanate, and isophorone diisocyanate; Bullet polyisocyanate compounds: “Desmodur (registered trademark) IL”, “Desmodur (registered trademark) HL” (both manufactured by Bayer AG), “Coronate (registered trademark) EH” (Nippon Polyurethane Industry) Polyisocyanate compound having an isocyanurate ring known as “Sumidur (registered trademark) L” Adduct polyisocyanate compounds such as “Sumitomo Bayer Urethane Co., Ltd.”; Adduct polyisocyanate compounds such as “Coronate (registered trademark) L” (manufactured by Nippon Polyurethane); “Deyuranate (registered trademark) D201” ( It is possible to list polyisocyanate compounds such as Asahi Kasei Corporation. These can be used alone or in combination of two or more. In addition, the isocyanate group of these compounds and a masking agent having active hydrogen It is also possible to use so-called block isocyanate which has been inactivated by reaction.

[0059] Examples of the epoxy compound include ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, 1,6-hexane diglycidyl ether, bisphenol A type epoxy resin, N, N, Ν ', N'— Examples thereof include tetraglycidyl 1-m-xylenediamine, 1,3-bis (N, N-diglycidylaminomethinole) cyclohexane, N, N-diglycidyl dilin, N, N-diglycidyl toluidine and the like.

[0060] These cross-linking agents should be added so that the total amount of functional groups of the high Tg polymer (A) and the low Tg polymer (B) is 1 equivalent; Is preferred. If the amount of the cross-linking agent is too small, the resulting adhesive may have insufficient cohesive force to cause adhesive residue, but if it is too large, the adhesive force may be insufficient or the wettability to a rough surface may be reduced. The amount of the crosslinking agent is more preferably 0.2 to 4 equivalents, still more preferably 0.3 to 2 equivalents.

[0061] The non-volatile content of the solvent-based re-peeling pressure-sensitive adhesive composition of the present invention is not particularly limited, but for example, it is preferably 10 to 80% by mass, more preferably 20 to 60% by mass, Preferably it is 25-45 mass%. If the non-volatile content is less than 10% by mass, drying after application takes a long time, which may reduce productivity. On the other hand, if it exceeds 80% by mass, the viscosity of the whole composition becomes high, handling properties and coating properties are lacking, and there is a possibility that the practicality becomes poor. As the solvent for the pressure-sensitive adhesive composition, any of the above-mentioned polymerization solvents can be used, and as described above, the same solvent as the polymerization solvent is preferred!

[0062] To the pressure-sensitive adhesive composition of the present invention, known crosslinking accelerators, tackifiers, modifiers, pigments, colorants, fillers, anti-aging agents, ultraviolet absorbers, ultraviolet stabilizers and the like are added. Add agents to the extent that they do not interfere with the purpose of the present invention.

[0063] Also, do not destroy the sea-island structure! /, So long as the compatibilizer may be added! The compatibilizer is not particularly limited. For example, a block copolymer (graf) copolymer of (meth) acrylate and butyl acetate, a graft copolymer, or the like, or a compatibilizer by an ionic interaction (a compound or polymer having a specific functional group). Etc.) can be used. The addition amount of the compatibilizer is preferably about 0 to 20 parts by mass per 100 parts by mass of the resin component (total amount of the polymer (A) and the polymer (B)) in the solvent-type re-peeling pressure-sensitive adhesive composition. .

[0064] The pressure-sensitive adhesive composition of the present invention is used for production of a re-peeling pressure-sensitive adhesive product. Base material or An adhesive product (adhesive tape or sheet) in which an adhesive layer is formed on one side of the substrate by applying the adhesive composition on the release paper and forming a dry coating film on both sides of the substrate It is possible to obtain a pressure-sensitive adhesive product having a pressure-sensitive adhesive layer formed thereon, or a pressure-sensitive adhesive product having only a pressure-sensitive adhesive layer having no base material. In the case of producing a paper base adhesive product, a method of applying a pressure sensitive adhesive composition on a release paper to form a pressure sensitive adhesive layer and then transferring it to a paper base material can be employed. In forming the adhesive layer, it is desirable to heat and dry under conditions where the solvent scatters (for example, 50 to; 60 to 120 ° C for 60 to 180 seconds).

[0065] Examples of the base material include conventionally known papers such as fine paper, kraft paper, crepe paper, and dalasin paper; plastics such as polyethylene, polypropylene, polyester, polystyrene, polyethylene terephthalate, polychlorinated bure, and cellophane; Textile products such as cloth and non-woven fabric; laminates of these can be used. When used for surface protection of optical films, the substrate is preferably a transparent film such as polyethylene terephthalate!

[0066] The method of applying the pressure-sensitive adhesive composition to the substrate is not particularly limited, and a known method such as a roll coating method, a spray coating method, or a dating method can be employed. In this case, any of a method of directly applying the pressure-sensitive adhesive composition to the base material, a method of applying the pressure-sensitive adhesive composition to a release paper, and then transferring the coated material onto the base material can be employed. After applying the pressure-sensitive adhesive composition, the pressure-sensitive adhesive layer is formed on the substrate by drying.

[0067] On the surface of the pressure-sensitive adhesive formed on the substrate, for example, a release paper may be stuck! /. The surface of the adhesive can be suitably protected and stored. The release paper is peeled off from the surface of the adhesive when the adhesive product is used. In addition, when a pressure-sensitive adhesive surface is formed on one side of a substrate such as a sheet or tape, a known release agent is applied to the back surface of the substrate to form a release agent layer. If the adhesive layer is placed inside and the adhesive sheet (tape) is wound in a roll shape, the adhesive layer comes into contact with the release material layer on the back surface of the substrate. Protection 'Saved.

[0068] The adhesive product for re-peeling obtained from the pressure-sensitive adhesive composition of the present invention has a 180 ° adhesive strength of 0.05—0.3 N / 25 mm, 30 m / min at a low speed of 0.3 m / min. In high-speed peeling, it is preferably 0.2 to 3 N / 25 mm. If the low-speed peel adhesive strength is in the above range, the optical part This is because if it is sufficient as a surface protective sheet for the material and the high-speed peel adhesive strength is in the above range, it can be peeled smoothly without causing inconveniences such as zipping. A more preferable low-speed peeled rice occupying force is 0.06—0.2 N / 25 mm, and more preferably 0.0 07—0.15 N / 25 mm. Further, the more preferable high-speed peel adhesive strength is 0.3 to 2 N / 25 mm, and more preferably 0.5 to 1.5 N / 25 mm. If the value obtained by dividing the high-speed peel adhesive force by the low-speed peel adhesive force is 15.0 or less, an increase in the adhesive force during high-speed peel can be suppressed. The 180 ° adhesive force was measured at 23 ° C using an adhesive product in which an adhesive layer having a thickness of 20 m was formed on a polyethylene terephthalate film substrate having a thickness of 38 m. The case value is adopted. In the unit “N / 25 mm”, the part “/ 25 mm” means the width of the pressure-sensitive adhesive sheet that is pressure-bonded to the adherend.

[0069] In addition, the re-peeling pressure-sensitive adhesive product obtained from the pressure-sensitive adhesive composition using the high Tg polymer (A-2) has a low speed of 0.3 m / min when subjected to a 180 ° peel test on an acrylic plate. Adherent contamination does not occur even with peeling! /, (See Examples).

Example

[0070] The present invention will be described in detail below with reference to examples, but the scope of the present invention is not limited to these examples. Note that “%” means “mass%” unless otherwise specified.

[0071] Synthesis Example 1 (two-stage polymerization)

A flask equipped with a thermometer, stirrer, inert gas inlet tube, reflux condenser and dropping funnel using 70 parts of butyl acetate (VAC) as the monomer for the high Tg polymer and 210 parts of ethyl acetate as the solvent. Added to. While circulating nitrogen gas, raise the internal temperature of the flask to 75 ° C, and use the polymerization initiator “NIPER (registered trademark) BMT-K40” (manufactured by NOF Corporation; m-toluoyl peroxide and benzoyl peroxide). Mixture of oxides) 0 · 9 parts were put into a flask to initiate polymerization.

[0072] After 1.5 hours from the start of the reaction, "ABN-E" (manufactured by Nippon Hydrazine Kogyo Co., Ltd .; 2, 2, -azobis (2-methylbutyronitrile)) was used as a booster (post-addition initiator). · After 25 parts were added, the mixture was further aged at 76 ° C for 1.5 hours to obtain a polyacetic acid bull solution. At this point The polymerization rate of butyl acetate was 73%.

[0073] Subsequently, in the same flask, as a monomer for a low Tg polymer, 120 parts of n-butyl acrylate (BA), 268 parts of 2-ethylhexyl acrylate (2EHA) and 12 parts of 2-hydroxyethyl oleate (HEA), A monomer solution was prepared by thoroughly mixing 0.5 parts of the above-mentioned Nyper BMT-K40J and 105 parts of ethyl acetate, and was added dropwise evenly over 1 hour from the dropping funnel. Then, 0.2 part of the above-mentioned “ABN-E” was added as a booster together with 200 parts of ethyl acetate, and further aged at 78 ° C. for 2.5 hours to obtain an adhesive polymer solution No. 1. As a result of observing the pressure-sensitive adhesive layer obtained from this pressure-sensitive adhesive polymer solution No. 1 using an optical microscope, it was confirmed that it had a sea-island structure.

[0074] Synthesis Example 2 (two-stage polymerization)

Using 100 parts of VAC as the monomer for the high Tg polymer and 185 parts of ethyl acetate as the solvent, they were mixed well and added to a flask equipped with a thermometer, stirrer, inert gas inlet tube, reflux condenser and dropping funnel. While circulating nitrogen gas, the internal temperature of the flask was raised to 75 ° C., and 0.05 part of the “ABN-E” was charged into the flask to initiate polymerization.

Thereafter, two-stage polymerization was performed in exactly the same manner as in Synthesis Example 1 to obtain a pressure-sensitive adhesive polymer solution No. 2. As a result of observing the pressure-sensitive adhesive layer obtained from this pressure-sensitive adhesive polymer solution No. 2 using an optical microscope, it was confirmed that it had a sea-island structure.

[0076] Synthesis Example 3 (two-stage polymerization + addition after separate polymerization)

250 parts of VAC and 1.25 parts of “Tiocalcol (registered trademark) 20” (manufactured by Kao Corporation; n-dodecyl mercaptan) as a molecular weight regulator were weighed and mixed well to prepare a monomer mixture. 50% of this monomer mixture and 375 parts of ethyl acetate were added to a flask equipped with a thermometer, stirrer, inert gas inlet tube, reflux condenser and dropping funnel. The remaining monomer mixture and the dropping monomer mixture consisting of 0.16 part of “Nyper BMT-K40” were put into a dropping funnel and mixed well. While circulating nitrogen gas, the internal temperature of the flask was raised to 73 ° C., and 0 · 32 parts of “Nyper BMT-Κ40” was charged into the flask to initiate polymerization. After 10 minutes had passed since the polymerization initiator was added, the dropping of the monomer mixture for dropping was started. The monomer mixture for dropping was dropped evenly over 1 hour. After completion of the dropwise addition, 38 parts of ethyl acetate was added to the flask. Also, 1 hour after the end of dripping, booster As a result, 0.125 part of the above-mentioned “ABN-E” was added, and then further aged at 76 ° C. for 1.5 hours to obtain a polyacetate butyl solution. At this time, the polymerization rate of butyl acetate was 82%.

[0077] With respect to 100 parts of the non-volatile content of the polymer solution No. 1 produced in Synthesis Example 1, both are mixed so that the non-volatile content of the polyvinyl acetate solution is 10 parts, and the mixture is stirred well, and the pressure-sensitive adhesive Polymer solution No. 3 was obtained. As a result of observing the pressure-sensitive adhesive layer obtained from this pressure-sensitive adhesive polymer solution No. 3 using an optical microscope, it was confirmed that it had a sea-island structure.

[0078] Synthesis Example 4 (one-stage polymerization of low Tg polymer only; for comparative example)

485 parts of BA and 15 parts of HEA were weighed and mixed well to prepare a monomer mixture. 40% of this monomer mixture and 240 parts of ethyl acetate were added to a flask equipped with a thermometer, stirrer, inert gas inlet tube, reflux condenser and dropping funnel. The monomer mixture for dropping composed of 60% of the remaining monomer mixture and 0.3 part of the above-mentioned “Nyper BMT-K40” was put into a dropping funnel and mixed well. While circulating nitrogen gas, the internal temperature of the flask was raised to 84 ° C., and 0.4 part of the above-mentioned “Nyper BMT-Κ40” was charged into the flask to initiate polymerization. After 10 minutes had elapsed since the polymerization initiator was charged, the dropping of the monomer mixture for dripping was started. The monomer mixture for dropping was dropped evenly over 1 hour. After completion of dropping, 42 parts of toluene was added to the flask. Also, 1.5 hours after the completion of the dropwise addition, 165 parts of ethyl acetate and 0.25 part of the above-mentioned “Nyper ΒΜΤ—Κ40” were added as a booster, and further aged for 2.5 hours at 85 ° C., and 360 parts of toluene. Was added to obtain an adhesive polymer solution No. 4.

[0079] Synthesis Example 5 (—polymerization; for comparative example)

120 parts of BA, 2268 parts of 2EHA, 12 parts of HEA, and 100 parts of VAC were weighed and mixed well to prepare a monomer mixture. 40% of this monomer mixture and 240 parts of ethyl acetate were added to a flask equipped with a thermometer, stirrer, inert gas inlet tube, reflux condenser and dropping funnel. The remaining monomer mixture 60% and the above-mentioned monomer mixture for dripping consisting of 0 · 75 parts of “NyperΒΜΤ40” were put into a dropping funnel and mixed well. While circulating nitrogen gas, the internal temperature of the flask was raised to 82 ° C., and 0.5 part of the above-mentioned “Nyper ΒΜΤ—Κ40” was put into the flask to initiate polymerization. After 10 minutes had passed since the polymerization initiator was added, the dropping of the monomer mixture for dripping was started. The monomer mixture for dropping was dropped evenly over 1 hour. After completion of the dropwise addition, 305 parts of ethyl acetate was added to the flask. The end of dripping After 1.5 hours, 220 parts of ethyl acetate and 0.2 part of “Ε- として” were added as a booster and then aged at 77 ° C for 2.5 hours. Got.

[0080] Synthesis Example 6 (Blend)

A polymer solution of a low Tg polymer was obtained in the same manner as in Synthesis Example 4 except that the monomer yarn was changed to 150 parts BA, 2EHA335 parts, and HEA15 parts.

[0081] With respect to 100 parts of the non-volatile content of the polymer solution of the above-mentioned low Tg polymer, both were mixed so that the non-volatile content of the polyacetic acid butyl solution synthesized in Synthesis Example 3 would be 10 parts, and the mixture was well stirred and adhered. Agent polymer solution No. 6 was obtained. As a result of observing the pressure-sensitive adhesive layer obtained from the pressure-sensitive adhesive polymer solution No. 6 using an optical microscope, it was confirmed that it had a sea-island structure.

[0082] Synthesis Example 7 (Blend)

A low Tg polymer solution was obtained in the same manner as in Synthesis Example 4 except that the monomer yarns were changed to 150 parts BA, 2EHA335 parts and HEA15 parts.

[0083] With respect to 100 parts of the non-volatile content of the above low Tg polymer solution, the both are mixed so that the non-volatile content of the polyvinyl acetate solution synthesized in Synthesis Example 3 is 3 parts, and the mixture is stirred well, and the pressure-sensitive adhesive polymer Solution No. 7 was obtained. As a result of observing the pressure-sensitive adhesive layer obtained from this pressure-sensitive adhesive polymer solution No. 7 using an optical microscope, it was confirmed that it had a sea-island structure.

[0084] Synthesis Example 8 (Blend)

A low Tg polymer solution was obtained in the same manner as in Synthesis Example 4 except that the monomer yarns were changed to BA335 parts, 2EHA150 parts, and HEA15 parts.

[0085] Separately, 190 parts methyl methacrylate (MMA), 1 part BA15 and 12.5 parts HEA were used as monomers for the high Tg polymer, and 32.5 parts of the above-mentioned "Tiocalcol (registered trademark) 20" were weighed. And mixed well to prepare a monomer mixture. 50% of this monomer mixture and 188 parts of ethyl acetate were added to a flask equipped with a thermometer, stirrer, inert gas inlet tube, reflux condenser and dropping funnel. The monomer mixture for dripping consisting of the remaining monomer mixture 50% and 0.125 part of “Nypa I BMT-K40” was put in the dropping funnel and mixed well. While circulating nitrogen gas, the internal temperature of the flask was raised to 82 ° C., and 0-25 parts of “Nyper BMT-MT40” was charged into the flask to initiate polymerization. After 10 minutes had passed since the polymerization initiator was added, the dropping of the monomer mixture for dropping was started. Dropping module The nomer mixture was added dropwise evenly over 1 hour. After completion of the dropwise addition, 58 parts of ethyl acetate was added to the flask. Also, 1.5 hours after the completion of the dropping, add 0.125 parts of the above-mentioned Nyper B MT-K40J as a booster, and then ripen at 85 ° C for 2.5 hours to add the MMA high Tg polymer solution. Obtained.

[0086] With respect to 100 parts of the non-volatile content of the initially synthesized low Tg polymer solution, both were mixed so that the non-volatile content of the above-mentioned high Tg polymer solution was 15 parts, stirred well, and pressure-sensitive adhesive polymer solution No. I got 8. As a result of observing the pressure-sensitive adhesive layer obtained from this pressure-sensitive adhesive polymer solution No. 8 using an optical microscope, it was confirmed that it had a sea-island structure.

[0087] Synthesis Example 9 (Blend)

A MMA-based high Tg polymer solution was obtained in the same manner as in Synthesis Example 8, except that 250 parts of MMA and 1.0 part of “thiocalcol 20” were used. The 100% non-volatile content of the same low Tg polymer solution as in Synthesis Example 8 is mixed together so that the non-volatile content of this MMA high Tg polymer solution is 20 parts. I got 9. As a result of observing the pressure-sensitive adhesive layer obtained from this pressure-sensitive adhesive polymer solution No. 9 using an optical microscope, it was confirmed that it had a sea-island structure.

[0088] Experimental Example 1

Table 1 shows the synthesis method for each of the pressure-sensitive adhesive polymer solutions;! To 9, and Table 2 shows the characteristics. The characteristic evaluation method is as follows.

[0089] [Tg]

Tg calculated by the above formula.

[0090] [Mass average molecular weight (Mw)]

GPC measurement apparatus: Liquid Chromatography Model 510 (manufactured by Waters) was used under the following conditions.

Detector: M410 differential refractometer

Column: Ultra Styragel Linear (7.8 mm x 30cm; 'Styragel' is a registered trademark)

Ultra Styragel ΙΟθΑ (7.8 mm x 30cm)

Ultra Styragel 500 A (7.8 mm x 30cm)

Solvent: Tetrahydrofuran (abbreviated as THF) The sample concentration was 0.2%, the injection volume was 200 microliters / time, and the polystyrene standard sample conversion value was Mw.

[0091] In the case of two-stage polymerization, the high Tg polymer (A) was sampled and Mw was measured before the second-stage monomer was added to the flask. In addition, Mw of the whole polymer mixture was measured after the completion of the two-stage polymerization.

[0092] [tan δ]

Using a rheometer (manufactured by Ti-A Instruments Inc .; “ARES”), by shear mode, normal plate method (8 mm φ), angular vibration frequency 6.28 rad / s, measurement temperature range 50 to 150 Measured at ° C.

[0093] [Presence or absence of separation]

For polymer solution No .;! To 9, adjust the concentration with ethyl acetate so that the non-volatile content is 30% by mass, and collect 50 g in a beaker. After thoroughly stirring by hand, pour into a 12m πι φ test tube until the height of the liquid column reaches 100mm, and seal the test tube opening to prevent the solvent from evaporating. Stand in a test tube stand, leave it in an atmosphere of 25 ° C for 24 hours, and visually observe the state of separation. The case where the degree of turbidity was uniform throughout the solution and no separation boundary was observed was defined as “no separation”. When transparent parts are formed at the top and bottom of the liquid column, or when two phases with different turbidity levels are formed (for example, at the upper 90 mm of the liquid column, the turbidity is strong, and at the lower 10 mm, In the case of a slightly less turbid state), it was judged as “separated”.

[0094] [Adhesive properties]

The pressure-sensitive adhesive polymer solution was taken, and the nonvolatile content was adjusted to 34% with ethyl acetate. Dibutyltin dilaurate 250 ppm (mass basis) as a crosslinking accelerator per 100 parts of polymer, and “deyuranate (registered trademark) D-201” (hexamethylene diisocyanate series; bifunctional; bifunctional; manufactured by Asahi Kasei Co., Ltd.) ) Was added in an amount corresponding to 10 parts, and stirred well to obtain an adhesive composition.

[0095] A polyethylene terephthalate (PET) film (manufactured by Toray Industries, Inc .; thickness 3 8 111) was used as a supporting substrate, and the pressure-sensitive adhesive composition was applied so that the thickness after drying was 20 m. An adhesive film was prepared by drying at 0 ° C. for 2 minutes. After sticking and protecting the adhesive surface with a PET film that had been subjected to a release treatment, it was cured in an atmosphere of 40 ° C for 3 days. The cured adhesive film was conditioned for 24 hours in an atmosphere of 23 ° C. and 65% relative humidity, and then cut to an appropriate length with a width of 25 mm to prepare a test tape. The release film was peeled off during the test.

[0096] A 3 mm thick acrylic plate (standard test plate made by Nippon Test Panel Co., Ltd.) was used as the adherend, and the above test tape was placed on the acrylic plate in an atmosphere of 23 ° C and 65% relative humidity. 1 reciprocate and crimp. After standing for 25 minutes after crimping, the peel rate is 0.3 m / min for low speed peel and 30 m / min for high speed peel, and 180 ° peel adhesive strength in accordance with JIS K 6854 under an atmosphere of 23 ° C. It was measured. Table 2 also shows the low-speed peel adhesive strength, the high-speed peel adhesive strength, and the value obtained by dividing the high-speed peel adhesive strength by the low-speed peel adhesive strength (shown as “high speed / low speed”).

[0097] [Haze (%)]

Using a turbidimeter (manufactured by JEOL Ltd .; “NDH-2000”), the haze (%) of the test tape was measured according to JIS K 7105.

[0098] In Table 1, each monomer and molecular weight modifier are abbreviated as follows.

VAC: Bull acetate

BA: n-Butyl acrylate

2EHA: 2-Ethylhexyl acrylate

HEA: 2-hydroxyethyl acrylate

MMA: Methyl metatalylate

DM: Dodecyl mercabtan (molecular weight regulator)

[0099] [Table 1]

[Star 0

As is apparent from Table 2, the pressure-sensitive adhesive compositions of Examples 2 to 3 in which two-stage polymerization was carried out were excellent in storage stability without causing separation. In addition, high Tg polymer (A-1) and low Tg polymer (B) are blended in a well-balanced manner. 0 or less. Since Comparative Example 1 consisted of only the low Tg polymer (B), the high-speed peel adhesive strength was too large. Even in Comparative Example 2 in which the high Tg polymer (A) and the low Tg polymer (B) were polymerized in a lump, the high-speed peel adhesive strength was high, and zippering occurred.

[0102] From the comparison between Example 4 blended with high Tg polymer (A-1) and low Tg polymer (B) and Reference Example 1, the adhesive properties deteriorated when the amount of high Tg polymer (A-1) is too small. I was able to find out.

[0103] Further, in Example 5 and Reference Example 2, since a MMA-based polymer having a refractive index different from that of 2EHA or BA was used as the high Tg polymer (A), it was not very good for haze! However, in Reference Example 2, it was found that the Tg of the high Tg polymer (A) was too high, so that the peel force at low speed was too small and the adhesive strength might be insufficient.

[0104] Synthesis Example 10 (two-stage polymerization + post-addition)

10.8 parts of VAC and 263 parts of ethyl acetate as solvent were added to a flask equipped with a thermometer, stirrer, inert gas inlet tube, reflux condenser and dropping funnel. While stirring, nitrogen gas was circulated, the temperature inside the flask was raised to 75 ° C, and “Laurox” diluted with 1.1 parts of ethyl acetate as a polymerization initiator (manufactured by Kayaku Akuzo; Lauroyl peroxide) 0.12 parts were charged into the flask to initiate the polymerization.

[0105] After 30 minutes from the start of the reaction, a mixture consisting of 24 parts of VAC, 4.2 parts of HEA, 0.14 parts of "Laurox" and 52 parts of ethyl acetate was dropped into the flask over 1 hour. After completion of the dropping, the dropping funnel was washed with 14 parts of ethyl acetate and added to the flask. Immediately after that, 0.7 parts of “Laurox” diluted with 6.3 parts of ethyl acetate was added as a booster, and then further aged at 76 ° C for 2 hours. The non-volatile content synthesized from VAC and HEA was 30%. A high Tg polymer in ethyl acetate was obtained. This high Tg polymer had a Tg of 28 ° C and an Mw of 69,000.

[0106] Next, in the presence of a high Tg polymer, a monomer for a low Tg polymer was polymerized to synthesize a graft polymer. In a flask equipped with a thermometer, stirrer, inert gas inlet tube, reflux condenser and dropping funnel, 15 parts of the above high Tg polymer (non-volatile content), and 27 parts of BA, 2EHA60.3 as the monomer for the low Tg polymer , 2 · 7 parts, and 120 parts of ethyl acetate were mixed well. Keep the temperature of the flask up to 82 ° C while flowing nitrogen gas under stirring. Then, 0.12 part of the above-mentioned “Nyper BMT-K40”, which is a polymerization initiator, was added to the flask to initiate polymerization.

[0107] After 15 minutes from the start of the reaction, add a mixture of ΒΑ63 parts, 2EHA140.7 parts, ΗΕΑ6.3 parts, “Nyper ΒΜΤ—Κ40” 0.26 parts, and ethyl acetate 152.4 parts. It was dropped into the flask over time. After the completion of dropping, 1.5 hours to 2.5 hours later, 1 part of “ΑΒΝ-Ε” and 54.9 parts of ethyl acetate were added in three portions as a booster. Thereafter, the mixture was further aged at 78 ° C for 1.5 hours.

[0108] An adhesive polymer solution No. 10 was obtained by adding 20 parts of the high Tg polymer ethyl acetate solution in a nonvolatile content to 100 parts of the nonvolatile content in the obtained graft polymer solution. The pressure-sensitive adhesive layer obtained from this adhesive polymer solution No. 10 was observed using SEM, and as a result, it was confirmed that it had a sea-island structure (Fig. 1). In FIG. 1, the upper side is polyethylene terephthalate (PET) of the base film, and the lower side is an adhesive layer.

[0109] Synthesis Example 11 (two-stage polymerization + post-addition)

A high Tg polymer was synthesized in the same manner as in Synthesis Example 10 except that the monomer composition for the high Tg polymer was changed as shown in Table 3.

[0110] Next, a monomer for low Tg polymer was polymerized in the presence of high Tg polymer to synthesize a graft polymer. In a flask equipped with a thermometer, stirrer, inert gas inlet tube, reflux condenser and dropping funnel, 15 parts of the above-mentioned high Tg polymer (non-volatile content), and 27 parts of BA, 2EHA61. 4-hydroxybutyl acrylate (4HBA; homopolymer Tg = 241K) 1.7 parts, 0.09 part dodecyl mercaptan (DM) as a chain transfer agent and 105 parts ethyl acetate were charged and mixed well. While stirring, while supplying nitrogen gas, the internal temperature of the flask was raised to 82 ° C., and 0 · 12 parts of the above-mentioned “Nyper BMT-Κ40” were put into the flask to initiate polymerization.

[0111] 15 minutes after the start of the reaction, ΒΑ63 parts, 2EHA143. 1 part, 4 ΗΒΑ3.9 parts, D Μ0.21 parts, “Nyper ΒΜΤ—Κ40” 0 · 26 parts, ethyl acetate 62.4 parts The mixture was dropped into the flask over 1 hour. After completion of the dropping, the dropping funnel was washed with 30 parts of ethyl acetate and added to the flask. After the completion of dripping 1. After 5 hours and 2.5 hours, add 1 part of “ΑΒΝ-Ε” and 9.9 parts of ethyl acetate as a booster in 3 portions. Added. Thereafter, the mixture was further aged at 78 ° C. for 1.5 hours to obtain a graft polymer solution. The ratio of graft polymer to high Tg polymer was 100: 20 in non-volatile content. Using the resulting pressure-sensitive adhesive polymer solution No. 11, a coating film was formed on a slide and observed with an optical microscope. As a result, it was confirmed that the structure was a sea-island structure.

[0112] Synthesis Examples 12 and 13 (two-stage polymerization + post-addition)

Synthesis Example 12 and Synthesis Example 13 are examples in which the mixing ratio of the high Tg polymer obtained in Synthesis Example 11 and the graft polymer was changed. As a result of forming a coating film on the preparation using the pressure-sensitive adhesive polymer solutions No. 12 and 13 obtained in each example and observing with an optical microscope, it was confirmed that the structure was a sea-island structure.

[0113] Synthesis Example 14 (two-stage polymerization + post-addition)

A high Tg polymer solution and a graft polymer solution were obtained in the same manner as in Synthesis Example 11 except that the amount of DM used to synthesize the graft polymer was reduced to 0.15 part. The ratio of graft polymer to high Tg polymer was 100: 20 in non-volatile content. As a result of forming a coating film on the preparation using the obtained pressure-sensitive adhesive polymer solution No. 14 and observing it with an optical microscope, it was confirmed that the structure was a sea-island structure.

[0114] Synthesis Example 15 (two-stage polymerization + post-addition)

In synthesizing the graft polymer, a high Tg polymer solution and a graft polymer solution were obtained in the same manner as in Synthesis Example 11, except that the amount of the high Tg polymer charged was reduced to 6 parts. The ratio of graft polymer to high-Tg polymer was 100: 20 in terms of nonvolatile content, and both solutions were mixed to obtain adhesive polymer solution No. 15. As a result of forming a coating film on the slide and observing it with an optical microscope, it was confirmed that the structure was a sea-island structure.

[0115] Synthesis Example 16 (blend)

A high Tg polymer solution was prepared in the same manner as in Synthesis Example 11. Next, a monomer for low Tg polymer was separately polymerized. In a flask equipped with a thermometer, stirrer, inert gas inlet tube, reflux condenser and dropping funnel, 36 parts BA, 2EHA 82.2 parts, HEA 1.8 parts, and ethyl acetate as low Tg polymer monomers 144 parts were charged and mixed well. While the nitrogen gas was circulated under stirring, the internal temperature of the flask was raised to 82 ° C., and 0.15 part of the above-mentioned “Nyper (registered trademark) BMT-K40” was put into the flask to initiate the polymerization. [0116] After 15 minutes from the start of the reaction, a mixture of 54 parts of BA, 2 parts of 2EHA123.3, 7 parts of HEA, 0.23 parts of Nyper ΒΜΤ—ΒΜΤ40, and 92 parts of ethyl acetate for 1 hour The solution was dropped into the flask. After completion of the dropping, the dropping funnel was washed with 60 parts of ethyl acetate and added to the flask. After the completion of dripping, 1.5 hours and 2.5 hours later, 1 part of “ΑΒΝ-Ε” and 69.9 parts of ethyl acetate were added in three portions as a booster. Thereafter, it was further aged at 78 ° C. for 1.5 hours to obtain a low Tg polymer solution. The low Tg polymer solution and the high Tg polymer solution were mixed so that the non-volatile content ratio was 100: 20 to obtain an adhesive polymer solution No. 16. As a result of forming a coating film on the slide and observing it with an optical microscope, it was confirmed that the structure was a sea-island structure.

[0117] Synthesis Example 17 (two-stage polymerization + post-addition)

A high Tg polymer was synthesized in the same manner as in Synthesis Example 10 except that the monomer composition for the high Tg polymer was changed as shown in Table 3. Next, the monomer for low Tg polymer was polymerized in the presence of high Tg polymer to synthesize the graft polymer. In a flask equipped with a thermometer, stirrer, inert gas inlet tube, reflux condenser and dropping funnel, 15 parts of the above-mentioned high Tg polymer (non-volatile content), and 27 parts of BA, 2EHA60. 3 parts as monomers for low Tg polymer 2.7 parts of HEA and 120 parts of ethyl acetate were charged and mixed well. While the nitrogen gas was circulated under stirring, the internal temperature of the flask was raised to 82 ° C., and 0 · 12 parts of “NIPPER ΒΜΤ—Κ40” were put into the flask to initiate the polymerization.

[0118] After 15 minutes from the start of the reaction, a mixture of ΒΑ63 parts, 2EHA140. The solution was dropped into the flask. After completion of dropping, the dropping funnel was washed with 120 parts of ethyl acetate and added to the flask. 1. After 5 hours and 2.5 hours had elapsed, 1 · 1 part of “ΑΒΝ-ΑΒΝ” and 9.9 parts of ethyl acetate were added in three portions as a booster. Thereafter, the mixture was further aged at 78 ° C. for 1.5 hours to obtain a graft polymer solution. The ratio of graft polymer to high Tg polymer was 100: 20 in non-volatile content. As a result of forming a coating film on the preparation using the obtained pressure-sensitive adhesive polymer solution No. 17 and observing it with an optical microscope, it was confirmed that the structure was a sea-island structure.

[0119] Experimental Example 2 For the pressure-sensitive adhesive polymer solution No. 10 to 17; and pressure-sensitive adhesive polymer solution No. 1 obtained in Synthesis Example 1, Tg, Mw, low-speed peel adhesive strength, high-speed peel adhesive strength, and high-speed peel adhesive The value obtained by dividing the force by the low-speed peel adhesion (“high speed / low speed”) and haze were measured and are shown in Table 3. In addition, adherend contamination and conformability were evaluated as shown below, and the results are shown in Table 3.

[0120] [Adherent contamination]

Using a 3mm thick acrylic plate (standard test plate manufactured by Nippon Test Panel Co., Ltd.) as an adherend, the test tape is reciprocated once with a 2kg rubber roller in an atmosphere of 23 ° C and relative humidity of 65%. And crimp. After crimping, it was left in an oven at 70 ° C. for 72 hours, and then temperature-controlled for 24 hours in an atmosphere at 23 ° C. and 65% relative humidity. The test tape was peeled off at a peeling speed of 0.3 m / min, and the surface state of the acrylic plate after peeling was visually observed. V, no contamination (no glue residue) was rated as 0, and there was a slight amount of glue residue and contamination! /, And X was rated as X.

[0121] [Familiarity]

A test piece having a size of 4 cm × 4 cm is cut out from the test tape. Use the rough surface of a commercially available LCD protective film (antiglare) (manufactured by BUFFALO; BOF-H141 S) as the adherend, and place the antiglare film horizontally on a flat surface so that the rough surface is on top. Place the specimen gently on the antiglare film in an atmosphere of 23 ° C and 65% relative humidity. Measure the time from when the specimen starts to get wet to the film until the entire specimen is fully integrated with the film. The case was evaluated as X for less than 120 seconds, ◎ for 120 seconds to less than 180 seconds, or for more than 180 seconds, or to be completely wet! /.

[0122] [Table 3]

As is apparent from Table 3, the adhesive compositions of Examples 10 to 18 in which hydroxyl groups were introduced into the gaps between the high Tg polymer (A) and the low Tg polymer (B) were not contaminated with the adherend. It became clear that it was useful as an adhesive for re-peeling at all. In addition, using 4HBA rather than HEA has shown that the compatibility is very good. On the other hand, Example 17 and Example 1 are high Tg Since no hydroxyl group was introduced into the polymer (A) and no cross-linking reaction occurred, some contamination of the adherend was observed. In both examples, high Tg polymer (A) and low Tg polymer (B) are blended in a well-balanced manner and have a sea-island structure. Directly it was below 15.0.

[0124] Synthesis Example 18 (Blend)

[High Tg polymer]

Methinorea tallylate (MA) 155 咅, HEA 4.8 咅, DMO. 64 咅, 298.3 parts of ethyl acetate as solvent, thermometer, stirrer, inert gas inlet tube, reflux condenser and dripping Added to a flask equipped with a neck. While stirring the nitrogen gas, raise the internal temperature of the flask to 78 ° C, and use 0.4 parts of “Nyper ΒΜΤ—Κ40” diluted with 3.6 parts of ethyl acetate as a polymerization initiator. To initiate polymerization.

[0125] After 15 minutes from the start of the reaction, a mixture consisting of を 233 parts, ΗΕΑ7.2 parts, DMO.96 parts, the above-mentioned “Nyper ΒΜΤ—Κ40” 0.3 parts, and 279 parts of ethyl acetate It was added dropwise to the flask over 1 hour. After completion of the dropping, the dropping funnel was washed with 20 parts of ethyl acetate and added to the flask. 1.5 hours to 2.5 hours after the completion of dropping, add 0.8 parts of the above-mentioned “ΑΒΝ-Ε” and 7.2 parts of ethyl acetate as a booster in three portions. did. Thereafter, the mixture was further aged at 78 ° C for 1.5 hours. The non-volatile content of the obtained high Tg polymer solution was 38.6%. This high Tg polymer had Tg of 8.4 ° C and Mw of 69,000.

[0126] [Low Tg polymer]

BA 60 kg, 2EHA 134 kg, HEA 6 kg, and 240 μm of lutinole acetate as a solvent were added to a flask equipped with a thermometer, a stirrer, an inert gas introduction tube, a reflux condenser, and a dropping funnel. While flowing nitrogen gas under stirring, the internal temperature of the flask was raised to 87 ° C, and 0.25 parts of “Nyper BMT-K40” diluted with 2.3 parts of ethyl acetate as a polymerization initiator was added to the flask. To initiate polymerization.

[0127] After 15 minutes from the start of the reaction, a mixture consisting of 90 parts, 2EHA201 parts, 9 parts, the above-mentioned "Niper BMT-K40J 0.38 parts, and ethynole acetate 153.4 parts over 1 hour. After dropping, the dropping funnel was washed with 100 parts of ethyl acetate, Added to the flask. From 1.5 hours to 2.5 hours after the completion of dropping, the mixture of 75 parts of “ΑΒΝ-E” and 22 parts of ethyl acetate was added in three portions as a booster. In addition, 100 parts of ethyl acetate was added at an appropriate time during the addition of the booster. Thereafter, it was further aged at 78 ° C for 1.5 hours. The non-volatile content of the obtained low Tg polymer solution was 45.5%. The Tg was 64 ° C and the Mw was 58.10,000.

Both were mixed so that the non-volatile content of the high Tg polymer solution was 20 parts with respect to 100 parts of the non-volatile content of the low Tg polymer solution, and stirred well to obtain adhesive polymer solution No. 18. As a result of observing the pressure-sensitive adhesive layer obtained from this pressure-sensitive adhesive polymer solution No. 18 using an optical microscope, it was confirmed that it had a sea-island structure.

[0129] Synthesis Example 19 (Blend)

[High Tg polymer]

High Tg polymer was synthesized in the same manner as in Synthesis Example 18.

[0130] [Low Tg polymer]

The initial monomer composition was changed to BA 60 parts, 2EHA 114 parts, HEA 9 parts, benzyl acrylate (BZA) 20 parts, and the dropped monomer composition was changed to BA 90 parts, 2EHA 171 parts, HE A 9 parts, BZA 30 parts. A low Tg polymer was synthesized in the same manner as in Synthesis Example 18. The non-volatile content of the obtained low Tg polymer solution was 45.5%. The Tg was 58 ° C and the Mw was 64.70,000.

[0131] With respect to 100 parts of the non-volatile content of the low Tg polymer solution, both were mixed so that the non-volatile content of the high Tg polymer solution was 20 parts, and stirred well to obtain adhesive polymer solution No. 19. As a result of observing the pressure-sensitive adhesive layer obtained from this pressure-sensitive adhesive polymer solution No. 19 using an optical microscope, it was confirmed that it had a sea-island structure.

[0132] Experiment 3

For adhesive polymer solutions Nos. 18 and 19, Tg, Mw, low-speed peel adhesive strength, high-speed peel adhesive strength, and high-speed peel adhesive strength divided by low-speed peel adhesive strength as described above (“high speed / low speed”) Table 4 shows the measured haze, adherend contamination, and conformability.

[0133] [Table 4]

— Means the same as the left column.

[0134] As clearly shown in Table 4, even when a high Tg polymer was synthesized using methyl acrylate in place of butyl acetate, adherend contamination was not observed and adhesive properties were also good. Met. In Example 18, the haze was 5.7%, which was higher than the target of 3%. This is thought to be due to the difference between the refractive index of high Tg polymer 1.4728 and the refractive index of low Tg polymer 1.4664. In Example 19, benzyl acrylate, which has a high refractive index of the homopolymer, was added to the copolymer component of the low Tg polymer, so that the refractive index of the low Tg polymer increased to 1.4712 and the haze was greatly increased to 2.1. Declined.

Industrial applicability

[0135] In the present invention, the high Tg polymer and the low Tg polymer have a sea-island structure. Adhesive with the advantages of both polymer and low Tg polymer

High-speed peelability could be improved. We have also succeeded in obtaining an adhesive product with low haze.

Therefore, the adhesive products obtained using the above-mentioned adhesive composition are the surfaces of optical members such as optical polarizing plates (TAC), retardation plates, EMI (electromagnetic wave) shield films, antiglare films, antireflection films and the like. It can be used as an adhesive product for re-peeling to protect the film. It can also be used as a protective film for the surface of other plastics and metal plates.

Claims

The scope of the claims

[1] High Tg polymer (A) with glass transition temperature (Tg) above 0 ° C and lower than this high Tg polymer

A solvent-type re-peeling pressure-sensitive adhesive composition comprising a low Tg polymer (B) having V and Tg and exhibiting pressure-sensitive adhesion, and a solvent,

In the pressure-sensitive adhesive layer obtained from the above pressure-sensitive adhesive composition, the high Tg polymer (A) and the low Tg polymer (A) are compatible with the high Tg polymer (A) and the low Tg polymer (B). A solvent-type re-peeling pressure-sensitive adhesive composition, wherein the polymer (B) forms a sea-island structure in which the sea is formed.

[2] The solvent-based re-peeling adhesive according to claim 1, wherein the high Tg polymer (A) has a Tg of 0 ° C or higher and lower than 80 ° C, and the low Tg polymer (B) has a Tg of lower than 0 ° C. Composition.

[3] The solvent-based re-peeling adhesive composition according to claim 1 or 2, wherein the high Tg polymer is synthesized from a raw material monomer containing 70% by mass or more of butyl acetate or methyl acrylate.

[4] The pressure-sensitive adhesive composition is used by blending a cross-linking agent, and the high Tg polymer (A) and the low Tg polymer (B) are! /, Both of which react with the cross-linking agent. 4. The solvent-type re-peeling pressure-sensitive adhesive composition according to claim 1, which contains a functional group capable of!

[5] The high Tg polymer (A) and the low Tg polymer (B), respectively, hydroxyl group-containing (meth) Atari rates starting monomer in 100 parts by mass ^_0/0 0.1;! ~ 10 weight ^_0/0 containing material The pressure-sensitive adhesive composition for solvent-based re-peeling according to any one of claims 1 to 4, which is synthesized from monomer power.

Yes

[6] When the total amount of the high Tg polymer (A) and the low Tg polymer (B) is 100% by mass, the high Tg polymer (A) is 4 to 35% by mass and the low Tg polymer (B) is The solvent-based re-peeling pressure-sensitive adhesive composition according to any one of claims 1 to 5, wherein the pressure-sensitive adhesive composition is 65 to 96% by mass.

[7] The adhesive layer obtained from the solvent-type re-peeling pressure-sensitive adhesive composition according to any one of claims 6 to 6 of claim 6 is formed on at least one side of a supporting substrate. Re-peeling adhesive product.

[8] The adhesive product for re-peeling according to claim 7, wherein the haze is 3% or less.

[9] When measuring 180 ° adhesive strength to an acrylic plate using an adhesive product with a 20 um thick adhesive layer formed on a 38 μm thick polyethylene terephthalate film substrate Furthermore, 0.35 / min for low-speed peeling is 0.55 / 0.3 mm, and 30 m / min for high-speed peeling is 0.2 to 3 N / 25 mm. The pressure-sensitive adhesive product for re-peeling according to claim 7 or 8, wherein a value divided by adhesion is 15.0 or less.