JP5006608B2 - Solvent-type re-peeling pressure-sensitive adhesive composition and re-peeling pressure-sensitive adhesive product - Google Patents

Description

  The present invention relates to a re-peeling adhesive product that is peeled off again after being attached to an adherend, and exhibits excellent peelability even at high-speed peeling, and a solvent mold for producing this pressure-sensitive adhesive product It is related with the adhesive composition. More specifically, the present invention relates to an adhesive product for re-peeling for protecting the surface of optical members such as an optical polarizing plate (TAC), a retardation plate, an EMI (electromagnetic wave) shield film, an antiglare film, and an antireflection film. It is.

  Liquid crystal displays, plasma displays, etc. are laminated with optical films having various functions, such as optical polarizing plates (TAC), retardation plates, EMI (electromagnetic wave) shield films, antiglare films, antireflection films, and the like. It is used. These optical films have a protective film affixed to the surface in order to prevent surface damage during the display manufacturing process and performance inspection stage. It is peeled off in the assembly process.

  As a surface protection film, it is necessary to have transparency that does not interfere with the performance inspection, and a sticking property that does not allow air bubbles and the like, and an increase in adhesive strength after sticking to the adherend and an adhesive residue on the adherend. It is necessary that there is no. 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.

  However, as the peeling speed becomes higher, the peeling force (adhesive force) tends to increase, which places a greater 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, causing a phenomenon of peeling while making a buzzing sound (zipping peeling), and the optical film surface is damaged or broken. was there.

  For this reason, many attempts have been made to improve the high-speed peelability of the protective film. For example, Patent Document 1 discloses that by blending a high Tg (meth) acrylic polymer having no adhesiveness at room temperature and a low Tg (meth) acrylic polymer having sufficient adhesive strength, A pressure-sensitive adhesive for a protective film that does not peel off (has moderate tackiness) and has good high-speed peelability is disclosed.

The adhesive product for the protective film as described above is designed to have a considerably lower adhesive force (slight adhesion) than a general adhesive product on the premise that it is peeled off. However, if the Tg of the high Tg polymer is too high, the adhesive strength is originally low, so that the adhesiveness at a low temperature is almost lost, or the crosslinking progresses with time and does not stick to the adherend. There was a problem. In general, different polymers are incompatible even if they are blended with few exceptions, and phase separation occurs even with the same (meth) acrylic polymer. Such an adhesive having poor compatibility has a large haze when formed into a coating film, and may be unsuitable as a protective film for optical applications. In addition, 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 when left for about a day. There is a problem that it is necessary to perform stirring and mixing again, or it becomes impossible to use.
JP 2005-146151 A

  Therefore, in the present invention, for the main purpose of applying to the surface protective film of an optical film, for solvent-type re-peeling that can form a pressure-sensitive adhesive layer excellent in high-speed peelability, more preferably a pressure-sensitive adhesive layer having a small haze. The present inventors have found a pressure-sensitive adhesive composition and provided a pressure-sensitive adhesive product for re-peeling having good characteristics.

  The solvent-type re-peeling pressure-sensitive adhesive composition of the present invention has a high Tg polymer (A) having a glass transition temperature (Tg) of 0 ° C. or higher and a Tg lower than this high Tg polymer, and has pressure-sensitive adhesive properties. A solvent-type re-peeling pressure-sensitive adhesive composition containing a low Tg polymer (B) and a solvent, wherein a high Tg polymer (A) and a low Tg polymer (B) are used in the pressure-sensitive adhesive layer obtained from the pressure-sensitive adhesive composition. It has a gist in that it forms a sea-island structure without being compatible with each other.

  The high Tg polymer (A), the low Tg polymer (B), and the solvent are mixed to prepare a solution in which the total amount of the high Tg polymer (A) and the low Tg polymer (B) is 30% by mass in terms of nonvolatile content. After being sealed and left at 25 ° C. for 24 hours, if the high Tg polymer (A) and the low Tg polymer (B) do not phase separate, the composition has excellent storage stability. In addition, an adhesive layer having a small haze can be formed, which is preferable.

  When the high Tg polymer (A) and the low Tg polymer (B) have a sea-island structure, when the dynamic viscoelasticity of the coating film obtained without crosslinking the adhesive composition is measured, the high Tg polymer The tan δ peak derived from (A) and the tan δ peak derived from the low Tg polymer (B) are observed separately. The sea-island structure can also be confirmed by an optical observation method described later.

  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 65 to 96% by mass. % Is preferred. In this case, the low Tg polymer (B) becomes a continuous phase, and the high Tg polymer (A) is dispersed in an island shape.

  The solvent-type re-peeling pressure-sensitive adhesive composition of the present invention may be obtained by separately polymerizing a high Tg polymer (A) and a low Tg polymer (B) and then blending them, and the high Tg polymer (A). May be obtained by polymerizing the monomer for the low Tg polymer (B) in the presence of.

  The pressure-sensitive adhesive product for re-peeling of the present invention is such that a pressure-sensitive adhesive layer obtained from the above-mentioned solvent-type re-peeling pressure-sensitive adhesive composition is formed on at least one surface of a support substrate. The haze of this re-peeling pressure-sensitive adhesive product is preferably 3% or less.

  When a 180 ° adhesive force to an acrylic plate was measured using an adhesive product having a 20 μm thick adhesive layer formed on a 38 μm thick polyethylene terephthalate film substrate, 0.05 μm was required for low-speed peeling at 0.3 m / min. When the value obtained by dividing the adhesive force in high-speed peeling by the adhesive force in low-speed peeling is 15.0 or less, it is excellent. This is a preferred embodiment of the present invention because it is a re-peeling pressure-sensitive adhesive product that exhibits high-speed peelability.

  In addition, the evaluation method of the isolation | separation degree of an adhesive composition, the optical confirmation method of a sea-island structure, the measuring method of dynamic viscoelasticity, the preparation methods of an adhesive product sample, and the measuring method of adhesive force are explained in full detail behind.

  In the present invention, since the high Tg polymer and the low Tg polymer adopt the sea-island structure, it is possible to obtain an adhesive having both the advantages of the high Tg polymer and the advantage of the low Tg polymer, and as a result, the high-speed peelability is improved. We were able to. We also succeeded in obtaining an adhesive product with low haze.

  Therefore, it was possible to provide a re-peeling pressure-sensitive adhesive product suitable for protecting the surface of an optical film.

  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 gist of the present invention is not impaired except for the following examples. Changes can be made as appropriate within the range. The solvent-type re-peeling pressure-sensitive adhesive composition of the present invention becomes a pressure-sensitive adhesive product by drying (removing the solvent). Refers to the case of 10 N / 25 mm or less. The “polymer” in the present invention includes not only a homopolymer but also a copolymer or a copolymer of three or more. The “monomer” of the present invention is an addition polymerization type monomer.

  First, the 1st essential component in the solvent-type re-peeling adhesive composition of this invention is a high Tg polymer (A) whose glass transition temperature (Tg) is 0 degreeC or more. The presence of this high Tg polymer suppresses an increase in high speed peeling force.

Here, the Tg of the polymer can be determined by DSC (differential scanning calorimeter), DTA (differential thermal analyzer), and TMA (thermomechanical analyzer). In addition, since the Tg of the homopolymer is described in various documents (for example, the polymer handbook), the Tg of the copolymer can be calculated from the Tg _n (K) of the various homopolymers and the mass fraction (W _n ) of the monomer as follows. It can also be obtained by an expression.

ここで Ｗ_ｎ ；各単量体の質量分率
Ｔｇ_ｎ；各単量体のホモポリマーのＴｇ（Ｋ）

Where W _n ; mass fraction of each monomer
Tg _n : Tg (K) of homopolymer of each monomer

  The Tg of the main homopolymer is 106 ° C. for polyacrylic acid, 8 ° C. for polymethyl acrylate, −22 ° C. for polyethyl acrylate, −54 ° C. for poly n-butyl acrylate, and −70 ° C. for poly 2-ethylhexyl acrylate. Poly-2-hydroxyethyl acrylate is −32 ° C., poly 2-hydroxyethyl methacrylate is 71 ° C., polymethyl methacrylate is 105 ° C., polyvinyl acetate is 32 ° C., polyacrylonitrile is 125 ° C., and polystyrene is 100 ° C.

  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. Therefore, it is preferably less than 80 ° C, preferably 75 ° C or less, and 70 ° C. More preferred are:

  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) preferably has units derived from vinyl acetate. Since the refractive index of the vinyl acetate polymer is close to 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. Therefore, the high Tg polymer (A) is preferably obtained from a monomer having 70% by mass or more of vinyl acetate. As for vinyl acetate, 90 mass% or more is more preferable. The most preferred high Tg polymer (A) is polyvinyl acetate (vinyl acetate homopolymer). Other monomers that can be used in combination with vinyl acetate are (meth) acrylic acid, methyl (meth) acrylate, ethyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, acrylonitrile, styrene, which have a high homopolymer Tg. However, a monomer that can be used as a raw material monomer for the low Tg polymer, which will be described later, can also be used if the type and amount are selected so that the Tg of the high Tg polymer is 25 ° C. or higher. The molecular weight of the high Tg polymer is preferably about 2000 to 100,000 in terms of mass average molecular weight (Mw).

  Next, the second essential component contained in the solvent-type re-peeling pressure-sensitive adhesive composition of the present invention is a low Tg polymer (B) exhibiting pressure-sensitive adhesiveness. The low Tg polymer (B) is required to be lower than the Tg (0 ° C. or higher) of the high Tg polymer (A), and in order to say “shows pressure-sensitive adhesiveness”, the Tg is less than 0 ° C. It is preferable that More preferably, it is -20 degrees C or less, More preferably, it is -35 degrees 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 adhesive residue tends to occur, which is not preferable.

  In order to obtain this low Tg polymer (B), it is preferable to use a combination of alkyl (meth) acrylate (b-1) and functional group-containing monomer (b-2). The alkyl (meth) acrylate (b-1) is necessary for ensuring adhesive strength, and the functional group-containing monomer (b-2) is a low Tg polymer (B) having a functional group for reacting with a crosslinking agent described later. It is a monomer to be introduced into.

  In the alkyl (meth) acrylate (b-1), the alkyl group preferably has 4 to 12 carbon atoms 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 more than 12 (13 or more), the adhesive strength may be reduced. Specifically, n-butyl (meth) acrylate, isobutyl (meth) acrylate, sec-butyl (meth) acrylate, tert-butyl (meth) acrylate, amyl (meth) acrylate, isoamyl (meth) acrylate, hexyl (meth) ) Acrylate, cyclohexyl (meth) acrylate, heptyl (meth) acrylate, octyl (meth) acrylate, isooctyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, nonyl (meth) acrylate, isononyl (meth) acrylate, decyl (meth) ) Acrylate, dodecyl (meth) acrylate, etc., among which butyl acrylate, 2-ethylhexyl acrylate, octyl acrylate and isooctyl acrylate are more preferable. These may be used alone or in combination of two or more, and is not limited.

  As the functional group-containing monomer, 2-hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, caprolactone-modified hydroxy (meth) acrylate, α- (hydroxymethyl) methyl acrylate, Hydroxyl group-containing (meth) acrylates such as mono (meth) acrylate of polyester diol obtained from ethyl α- (hydroxymethyl) acrylate, phthalic acid and propylene glycol; (meth) acrylic acid, cinnamic acid and crotonic acid Unsaturated monocarboxylic acids such as maleic acid, fumaric acid, itaconic acid, citraconic acid and other unsaturated dicarboxylic acids; carboxyl group-containing monomers such as monoesters of these unsaturated dicarboxylic acids; amino groups, amide groups, epoxy groups, etc. Or (meth) acrylates having any of the above. Of these, hydroxyl group-containing (meth) acrylates are preferred.

  The alkyl (meth) acrylate (b-1) is preferably used in the range of 50 to 99.9% by mass in 100% by mass of the raw material monomer of the low Tg polymer (B). More preferably, it is 60-99.7 mass%, More preferably, it is 70-99.5 mass%. If the usage-amount of alkyl (meth) acrylate (b-1) is in the said range, the obtained adhesive will show sufficient adhesive force and tack, However, If less than 50 mass%, adhesive strength and There is a possibility that the wettability to the adherend may be insufficient, and if it exceeds 99.9% by mass, the amount of the functional group-containing monomer (b-2) that becomes a crosslinking point is too small, and the high-speed adhesive force may be too high. There is.

  The functional group-containing monomer (b-2) is preferably 0.1 to 10% by mass. If there are few functional groups, the speed of crosslinking reaction will become slow, or high-speed adhesive force will become large too much, but if it exceeds 10 mass%, the adhesive strength of adhesive and the wettability to the adherend will tend to decrease. Therefore, it is not preferable. The use amount of the functional group-containing monomer (b-2) is more preferably 0.3 to 8% by mass, and further preferably 0.5 to 6% by mass.

  In synthesizing the low Tg polymer, another monomer (b-3) may be copolymerized. The other monomer (b-3) can be copolymerized with the alkyl (meth) acrylate (b-1) and the functional group-containing monomer (b-2), and (b-1) and (b -2) other monomers. For example, alkyl (meth) acrylates other than the alkyl (meth) acrylate (b-1); halogen-substituted products of aliphatic unsaturated hydrocarbons such as ethylene and butadiene, and aliphatic unsaturated hydrocarbons such as vinyl chloride; Aromatic unsaturated hydrocarbons such as styrene and α-methylstyrene; vinyl esters such as vinyl acetate; vinyl ethers; esters of allyl alcohol and various organic acids; ethers of allyl alcohol and various alcohols; acrylonitrile, etc. Of unsaturated cyanide compounds. These may be used alone or in combination of two or more, and is not limited. The other monomer (b-3) is preferably 0 to 49.9% by mass in 100% by mass of the raw material monomer mixture. When it exceeds 49.9 mass%, since the quantity of an alkyl (meth) acrylate (b-1) or a functional group containing monomer (b-2) will decrease as a result, a desired adhesion characteristic cannot be obtained. A more preferred upper limit is 40% by mass, and a still more preferred upper limit is 30% by mass.

  The most preferred embodiment of the low Tg polymer (B) is a polymer obtained from a raw monomer mixture comprising 2-ethylhexyl acrylate, butyl acrylate, and hydroxyethyl acrylate. This polymer has good adhesive properties and has a refractive index close to that of polyvinyl acetate, which is the best mode of the high Tg polymer (A), so that the haze of the resulting adhesive layer can be reduced. Because it can. When the total of 2-ethylhexyl acrylate, butyl acrylate, and hydroxyethyl acrylate is 100% by mass, 2-ethylhexyl acrylate is 20 to 80% by mass, butyl acrylate is 20 to 80% by mass, and hydroxyethyl acrylate is 0.8%. 5-5 mass% is preferable. Of course, (b-1) to (b-3) described above can also be used in combination, but when applied to applications in which haze is important, other than 2-ethylhexyl acrylate, butyl acrylate, and hydroxyethyl acrylate The monomer is preferably 10% by mass or less.

  The low Tg polymer (B) preferably has an Mw of 200,000 or more from the viewpoint of improving the adhesive properties. In addition, when the production method described later is adopted, the molecular weight of only the low Tg polymer (B) cannot be measured, but the Mw of the entire mixture of the high Tg polymer (A) and the low Tg polymer (B) of the present invention is 100,000 to 800,000 are preferable.

  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) must form a sea-island structure. The sea-island structure is in a micro phase separation state, and the larger amount becomes the sea (continuous phase). In the present invention, the total amount of the high Tg polymer (A) and the low Tg polymer (B) is 100% by mass. Since the high Tg polymer (A) is preferably 4 to 35% by mass and the low Tg polymer (B) is preferably 65 to 96% by mass, the low Tg polymer (B) becomes a continuous phase, The polymer (A) will be dispersed as islands. Due to the action of the high Tg polymer (A) dispersed in islands, an increase in adhesive force and a zipping phenomenon during high-speed peeling can be suppressed. In order to exert this effect, the high Tg polymer is preferably 4 to 35% by mass. If the amount is too small, the above effect will be insufficient. If the amount is too large, the adhesive strength and wettability to the adherend may be insufficient.

  In order to produce the pressure-sensitive adhesive composition of the present invention, a blending method and a two-stage polymerization method can be employed as described in detail later. The preferred amount of the high Tg polymer (A) when the blend method is employed is about 4 to 20% by mass, and the preferred amount of the high Tg polymer (A) when the two-stage polymerization method is adopted is 10 to 35% by mass. It has been found by the present inventors that it is a degree. This is because the diameter of the island made of the high Tg polymer (A) is about 1.0 to 100 μm in the case of the blend method, and about 0.5 to 50 μm in the case of the two-stage polymerization method. Since the large blend method is more likely to exhibit the effect of the high Tg polymer (A), it is presumed that the high-speed peelability may be improved even if the amount is somewhat small.

  In the present invention, the pressure-sensitive adhesive layer obtained by applying and drying the pressure-sensitive adhesive composition is used for an optical microscope, a transmission electron microscope, a scanning electron microscope, a phase contrast microscope, a polarizing microscope, a scanning tunnel microscope, a microscope The presence or absence of sea-island structure is judged by observing with Raman. 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 0.1 to 100 μm. 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.

  A pressure-sensitive adhesive composition having a sea-island structure by a blend method and a pressure-sensitive adhesive composition having a sea-island structure by a two-stage polymerization method can be clearly distinguished by performing the following separation degree check. That is, a solution having a non-volatile content of 30% by mass was prepared from the high Tg polymer (A), the low Tg polymer (B), and the solvent, and poured into, for example, a test tube and sealed, and then sealed at 25 ° C. for 24 hours. What is necessary is just to check the separation state when left unattended. When the high Tg polymer (A) and the low Tg polymer (B) have a sea-island structure that is easy to phase-separate obtained by a blending method, they are separated after standing for 24 hours, but are obtained by a two-stage polymerization method. In the case of a sea-island structure that is difficult to separate, it does 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 leaving for 24 hours under the above conditions, if a transparent part is generated in the upper part or the lower part of the liquid column or if the liquid column is separated into two phases having different turbidity, it is judged as “separated”. In addition, the mass ratio of the high Tg polymer (A) and the low Tg polymer (B) in the solution is within the above-described preferable range.

  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. However, aromatic hydrocarbons such as toluene and xylene; aliphatic esters such as ethyl acetate and butyl acetate; cyclohexane and the like Alicyclic hydrocarbons; aliphatic hydrocarbons such as hexane and pentane, and the like may be mentioned, and these may be used alone or in admixture of two or more.

  In order to confirm that the composition does not separate by the above-mentioned separation degree check but contains two types of polymers, for example, whether two Tg are observed in the measurement of tan δ of dynamic viscoelasticity. Check it out. The tan δ of the dynamic viscoelasticity is, for example, an angular vibration frequency of 6.28 rad / s by using a rheometer (manufactured by T.A. Instruments; “ARES”) by a shear mode, a paraplate method (8 mmφ), It may be measured at a measurement temperature range of −50 to 150 ° C.

  As described above, if a high Tg polymer (A) and a low Tg polymer (B) having an approximate refractive index are used, the transparency with a haze of 3% or less is obtained regardless of the blending method or the two-stage polymerization method. It is possible to obtain an adhesive product excellent in The haze is preferably as small as possible, and 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. First, the blending method is a method in which a high Tg polymer (A) and a low Tg polymer (B) are separately polymerized, 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, a solvent removal step is not required at the time of blending, which is more convenient. In addition, when blending, it is preferable to stir at high speed with a disper or the like.

  On the other hand, in the two-stage polymerization method, first, a monomer for high Tg polymer (A) (hereinafter referred to as “monomer (A)”) is polymerized by solution polymerization, and then the presence of this high Tg polymer (A) solution is present. Below, it is the method of superposing | polymerizing the monomer (henceforth "monomer (B)") for low Tg polymer (B). The pressure-sensitive adhesive composition obtained by this two-stage polymerization method does not cause separation even in the above separation degree check, but this is because the low Tg polymer (B) is grafted to the high Tg polymer (A) during the polymerization of the monomer (B). Such a polymer is partially produced, and this is thought to be due to the surfactant action having affinity for both the sea and the island to stabilize the island. For this reason, it is considered that the island diameter is smaller than that of the blend method.

  In the two-stage polymerization method, it is preferable to start adding the monomer (B) to the reactor after the polymerization rate of the monomer (A) reaches about 70 to 95% by mass. This is because separation does not occur. The polymerization rate (mass%) is a ratio of the mass of the monomer in the reaction vessel converted into a polymer (nonvolatile content), and can be easily obtained by measuring the nonvolatile content. The low Tg monomer (B) is preferably added dropwise to the reactor together with the polymerization initiator. The molecular weight can be increased.

  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.

  In both the blending method and the two-stage polymerization method, the solvent used in the solution polymerization specifically includes, for example, aromatic hydrocarbons such as toluene and xylene; aliphatic esters such as ethyl acetate and butyl acetate. Alicyclic hydrocarbons such as cyclohexane; aliphatic hydrocarbons such as hexane and pentane, and the like, but not particularly limited as long as the polymerization reaction is not inhibited. 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. Although the solvent type re-peeling pressure-sensitive adhesive composition of the present invention contains a solvent as an essential component, it is preferable to use the same solvent as the polymerization solvent. This is because the product obtained upon completion of the polymerization can be used as it is as a raw material for the solvent-type re-peeling pressure-sensitive adhesive composition.

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

  Examples of the polymerization catalyst (polymerization initiator) include, but are not limited to, methyl ethyl ketone peroxide, benzoyl peroxide, dicumyl peroxide, t-butyl hydroperoxide, cumene hydroperoxide, t-butyl peroxy octoate, organic peroxides such as t-butylperoxybenzoate, lauroyl peroxide, trade name “NIPPER BMT-K40” (manufactured by NOF Corporation; mixture of m-toluoyl peroxide and benzoyl peroxide), and azobisisobutyrate Known compounds such as nitrile, azo compounds such as trade name “ABN-E” [Nippon Hydrazine Kogyo; 2,2′-azobis (2-methylbutyronitrile)] and the like can be used. Further, for example, a known molecular weight regulator represented by mercaptans such as dodecyl mercaptan may be used.

  It is preferable to mix | blend a crosslinking agent with the adhesive composition of this invention. As the crosslinking agent, a compound having two or more functional groups capable of reacting with the functional group of the high Tg polymer (A) and / or the low Tg polymer (B) is used.

  For example, if the low Tg polymer (B) has a hydroxyl group, an isocyanate compound is preferable, and if it has a carboxyl group, an isocyanate compound or an epoxy compound is preferable. In terms of reactivity, a combination of a hydroxyl group and an isocyanate compound is most preferable.

  Examples of the isocyanate compound include tolylene diisocyanate (TDI), 4,4′-diphenylmethane diisocyanate (MDI), hexamethylene diisocyanate, xylylene diisocyanate, metaxylylene diisocyanate, 1,5-naphthalene diisocyanate, hydrogenated diphenylmethane diisocyanate, Diisocyanate compounds such as hydrogenated tolylene diisocyanate, hydrogenated xylylene diisocyanate, and isophorone diisocyanate; Burette polyisocyanate compounds such as “Sumijour N” (manufactured by Sumitomo Bayer Urethane Co., Ltd .; Sumijoule is a registered trademark); "Death Module HL" (both manufactured by Bayer AG; Death Module is a registered trademark), "Coronate EH" (Nippon Polyureta Manufactured by Kogyo Co., Ltd .; a polyisocyanate compound having an isocyanurate ring known as Coronate is a registered trademark; an adduct polyisocyanate compound such as “Sumijour L” (manufactured by Sumitomo Bayer Urethane Co., Ltd.); “Coronate L” (manufactured by Nippon Polyurethane Co., Ltd.) And polyisocyanate compounds such as “Duranate D201” (manufactured by Asahi Kasei Corporation; Duranate is a registered trademark). These can be used alone or in combination of two or more. In addition, so-called blocked isocyanates in which the isocyanate groups of these compounds are inactivated by reacting with a masking agent having active hydrogen can also be used.

  Examples of the epoxy compound include ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, bisphenol A type epoxy resin, N, N, N ′, N′-tetraglycidyl-m-xylenediamine. 1,3-bis (N, N-diglycidylaminomethyl) cyclohexane, N, N-diglycidylaniline, N, N-diglycidyltoluidine and the like.

  These crosslinking agents are preferably added so as to be 0.1 to 5 equivalents when the total of the functional groups of the high Tg polymer (A) and the low Tg polymer (B) is 1 equivalent. If the amount of the cross-linking agent is too small, the resulting adhesive may have insufficient cohesive force and cause adhesive residue, but if it is too large, the adhesive force will be insufficient or the wettability to a rough surface will be reduced. A more preferable amount of the crosslinking agent is 0.2 to 4 equivalents, and further preferably 0.3 to 2 equivalents.

  The non-volatile content of the pressure-sensitive adhesive composition for solvent-type re-peeling of the present invention is not particularly limited, but is preferably, for example, 10 to 80% by mass, more preferably 20 to 60% by mass, and still more preferably 25 to 25%. 45% by mass. When the non-volatile content is less than 10% by mass, drying after application or the like takes a long time, which may reduce productivity. Moreover, when it exceeds 80 mass%, the viscosity of the whole composition will become high, handling property and applicability | paintability may lack, and there exists a possibility that it may become impractical. As the solvent for the pressure-sensitive adhesive composition, any of the polymerization solvents described above can be used, and as described above, the same solvent as the polymerization solvent is preferable.

  In the pressure-sensitive adhesive composition of the present invention, known crosslinking accelerators, tackifiers, modifiers, pigments, colorants, fillers, anti-aging agents, ultraviolet absorbers, ultraviolet stabilizers, etc. You may add in the range which does not inhibit the objective of invention.

  Further, a compatibilizing agent may be added as long as it does not destroy the sea-island structure. The compatibilizer is not particularly limited. For example, a block copolymer or graft copolymer of (meth) acrylate and vinyl acetate, or a compatibilizer (a compound or polymer having a specific functional group) by ionic interaction is used. be able to. 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.

  The pressure-sensitive adhesive composition of the present invention is used for production of a re-peeling pressure-sensitive adhesive product. An adhesive product (adhesive tape or sheet) in which an adhesive layer is formed on one side of a substrate by applying the adhesive composition on the substrate or release paper and forming a dry coating film thereof, the substrate A pressure-sensitive adhesive product having a pressure-sensitive adhesive layer formed on both sides thereof, or a pressure-sensitive adhesive product having only a pressure-sensitive adhesive layer having no substrate can be obtained. In the case of producing a paper base adhesive product, it is also possible to employ a method in which an adhesive composition is applied on a release paper to form an adhesive layer and then transferred to a paper base material. In forming the pressure-sensitive adhesive layer, it is desirable to perform heat drying under conditions where the solvent scatters (for example, at about 50 to 120 ° C. for about 60 to 180 seconds).

  As the base material, conventionally known papers such as fine paper, kraft paper, crepe paper, glassine paper; plastics such as polyethylene, polypropylene, polyester, polystyrene, polyethylene terephthalate, polyvinyl chloride, cellophane; woven fabric, non-woven fabric, etc. Textile products: These laminates can be used. When used for protecting the surface of an optical film, the substrate is preferably a transparent film such as polyethylene terephthalate.

  The method for 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 dipping method can be employed. In this case, any of a method for directly applying the pressure-sensitive adhesive composition to the substrate, a method for applying the pressure-sensitive adhesive composition to a release paper, and then transferring the coated material onto the substrate can be employed. After apply | coating an adhesive composition, an adhesive layer is formed on a base material by making it dry.

  For example, release paper may be attached to the surface of the pressure-sensitive adhesive formed on the substrate. The pressure-sensitive adhesive surface can be suitably protected and preserved. The release paper is peeled off from the pressure-sensitive adhesive surface when the pressure-sensitive adhesive product is used. In addition, when the pressure-sensitive adhesive surface is formed on one side of a base material such as a sheet or tape, a release agent layer may be formed by applying a known release agent to the back surface of the base material. By winding the pressure-sensitive adhesive sheet (tape) in a roll shape with the pressure-sensitive adhesive layer on the inside, the pressure-sensitive adhesive layer comes into contact with the release material layer on the back of the substrate, so that the pressure-sensitive adhesive surface is protected and preserved. The

  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 to 0.3 N / 25 mm for low-speed peeling at 0.3 m / min and 0 for high-speed peeling at 30 m / min. It is preferable that it is 5-3N / 25mm. If the low-speed peel adhesive strength is in the above range, it is sufficient as a surface protective sheet for an optical member, and if the high-speed peel adhesive strength is in the above range, it can be smoothly peeled without causing inconvenience such as zipping. . Moreover, it can be said that the increase in the adhesive force at the time of high speed peeling was able to be suppressed as the value which remove | divided high speed peeling adhesive force by the low speed peeling adhesive force is 15.0 or less. This 180 ° adhesive strength is a value obtained by measuring 180 ° adhesive strength against an acrylic plate at 23 ° C. using an adhesive product in which an adhesive layer having a thickness of 20 μm is formed on a polyethylene terephthalate film substrate having a thickness of 38 μm. Is adopted. In the unit “N / 25 mm”, the portion “/ 25 mm” means the width of the pressure-sensitive adhesive sheet bonded to the adherend.

  EXAMPLES Hereinafter, the present invention will be described in detail with reference to examples, but the scope of the present invention is not limited only to these examples. Unless otherwise specified, “%” indicates “mass%” and “part” indicates “part by mass”.

Synthesis example 1 (two-stage polymerization)
A flask equipped with 70 parts of vinyl acetate (VAC) as a monomer for a high Tg polymer and 210 parts of ethyl acetate as a solvent and mixed well, and equipped with a thermometer, stirrer, inert gas introduction tube, reflux condenser and dropping funnel Added to. While circulating nitrogen gas, the internal temperature of the flask was raised to 75 ° C., and “Niper (registered trademark) BMT-K40” (manufactured by NOF Corporation; m-toluoyl peroxide and benzoyl peroxide) as a polymerization initiator. 0.09 part of the mixture) was charged into the flask to initiate the polymerization.

  After 1.5 hours from the start of the reaction, “ABN-E” (manufactured by Nippon Hydrazine Kogyo; 2,2′-azobis (2-methylbutyronitrile)) 0.25 is used as a booster (post-initiator). After the addition of a portion, the mixture was further aged at 76 ° C. for 1.5 hours to obtain a polyvinyl acetate solution. At this time, the polymerization rate of vinyl acetate was 73%.

Subsequently, in the same flask, 120 parts of n-butyl acrylate, 268 parts of 2-ethylhexyl acrylate and 12 parts of 2-hydroxyethyl acrylate, 0.5 parts of the above-mentioned “Nyper BMT-K40”, acetic acid as monomers for low Tg polymer A monomer solution was prepared by thoroughly mixing 105 parts of ethyl, and was added dropwise evenly over 1 hour from the dropping funnel. After 1.5 hours had elapsed after the completion of the dropwise addition, 0.2 part of “ABN-E” was added as a booster together with 200 parts of ethyl acetate, and further aged at 78 ° C. for 2.5 hours. 1 was obtained.
As a result of observation using an optical microscope, it was confirmed that the structure was a sea-island structure.

Synthesis example 2 (two-stage polymerization)
A flask equipped with 100 parts of vinyl acetate (VAC) as a monomer for a high Tg polymer and 185 parts of ethyl acetate as a solvent and well mixed, and equipped with a thermometer, stirrer, inert gas introduction tube, reflux condenser and dropping funnel Added to. 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 carried out in exactly the same manner as in Synthesis Example 1, and the polymer solution No. 2 was obtained. It was confirmed by an optical microscope that it has a sea-island structure.

Synthesis example 3
250 parts of vinyl acetate and 1.25 parts of “thiocalcol (registered trademark) -20” (manufactured by Kao Corporation; n-dodecyl mercaptan) 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 monomer mixture for dropping composed of 0.16 part of the above-mentioned “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 part of the “Nyper BMT-K40” was charged into the flask to initiate polymerization. After 10 minutes had passed since the polymerization initiator was added, the dropping of the dropping monomer mixture was started. The monomer mixture for dripping was dripped uniformly over 1 hour. After completion of the dropwise addition, 38 parts of ethyl acetate was added to the flask. Further, 1 hour after the completion of the dropwise addition, 0.125 part of the “ABN-E” was added as a booster, and further aged at 76 ° C. for 1.5 hours to obtain a polyvinyl acetate solution. At this time, the polymerization rate of vinyl acetate was 82%.

  Polymer solution No. 1 produced in Synthesis Example 1 Both were mixed so that the non-volatile content of the polyvinyl acetate solution was 10 parts with respect to 100 parts of the non-volatile content of 1, and stirred well. 3 was obtained. It was confirmed by an optical microscope that it has a sea-island structure.

Synthesis Example 4 (One-stage polymerization of low Tg polymer)
485 parts of n-butyl acrylate and 15 parts of 2-hydroxyethyl acrylate 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 0.3 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 84 ° C., and 0.4 part of the “Nyper BMT-K40” was charged into the flask to initiate polymerization. After 10 minutes had passed since the polymerization initiator was added, the dropping of the dropping monomer mixture was started. The monomer mixture for dripping was dripped uniformly over 1 hour. After completion of dropping, 42 parts of toluene was added to the flask. Further, 1.5 hours after the completion of the dropwise addition, 165 parts of ethyl acetate and 0.25 parts of the above-mentioned “Nyper BMT-K40” as a booster were added, and further aging at 85 ° C. for 2.5 hours, and 360 parts of toluene were added. Polymer solution No. 4 was obtained.

Synthesis example 5 (single-stage polymerization)
120 parts of n-butyl acrylate, 268 parts of 2-ethylhexyl acrylate, 12 parts of 2-hydroxyethyl acrylate, and 100 parts of vinyl acetate 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 dropping monomer mixture consisting of 0.75 parts of the above-mentioned “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 82 ° C., and 0.5 part of the above-mentioned “Niper BMT-K40” was charged into the flask to initiate polymerization. After 10 minutes had passed since the polymerization initiator was added, the dropping of the dropping monomer mixture was started. The monomer mixture for dripping was dripped uniformly over 1 hour. After completion of the dropwise addition, 305 parts of ethyl acetate was added to the flask. Further, 1.5 hours after the completion of dropping, 220 parts of ethyl acetate and 0.2 part of “ABN-E” as a booster were added, and the mixture was further aged at 77 ° C. for 2.5 hours. 5 was obtained.

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 composition was 150 parts of n-butyl acrylate, 335 parts of 2-ethylhexyl acrylate, and 15 parts of 2-hydroxyethyl acrylate.

  Both were mixed so that the non-volatile content of the polyvinyl acetate solution synthesized in Synthesis Example 3 was 10 parts with respect to 100 parts of the non-volatile content of the polymer solution of the low Tg polymer. 6 was obtained. It was confirmed by an optical microscope that it has a sea-island structure.

Synthesis example 7 (blend)
A low Tg polymer solution was obtained in the same manner as in Synthesis Example 4 except that the monomer composition was 150 parts of n-butyl acrylate, 335 parts of 2-ethylhexyl acrylate, and 15 parts of 2-hydroxyethyl acrylate.

  Both were mixed so that the non-volatile content of the polyvinyl acetate solution synthesized in Synthesis Example 3 was 3 parts with respect to 100 parts of the non-volatile content of the low Tg polymer solution. 7 was obtained. It was confirmed by an optical microscope that it has a sea-island structure.

Synthesis Example 8 (blend)
A low Tg polymer solution was obtained in the same manner as in Synthesis Example 4 except that the monomer composition was 335 parts of n-butyl acrylate, 150 parts of 2-ethylhexyl acrylate, and 15 parts of 2-hydroxyethyl acrylate.

  Separately, 190 parts of methyl methacrylate, 15 parts of n-butyl acrylate, 12.5 parts of 2-hydroxyethyl acrylate, and 32.5 parts of “thiocalcol-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 dropping composed of 50% of the remaining monomer mixture and 0.125 part of “Nyper BMT-K40” was placed 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 part of “Nyper BMT-K40” was charged into the flask to initiate polymerization. After 10 minutes had passed since the polymerization initiator was added, the dropping of the dropping monomer mixture was started. The monomer mixture for dripping was dripped uniformly over 1 hour. After completion of the dropwise addition, 58 parts of ethyl acetate was added to the flask. Further, 1.5 hours after the completion of the dropping, 0.125 part of the above-mentioned “Nyper BMT-K40” was added as a booster, and further aged at 85 ° C. for 2.5 hours to obtain a high Tg polymer solution.

  Both were mixed so that the non-volatile content of the high Tg polymer solution was 15 parts with respect to 100 parts of the non-volatile content of the initially synthesized low Tg polymer solution. 8 was obtained. It was confirmed by an optical microscope that it has a sea-island structure.

Synthesis Example 9 (blend)
A high Tg polymer solution was obtained in the same manner as in Synthesis Example 8 except that only 250 parts of methyl methacrylate and 1.0 part of the above “thiocalcol 20” were used as the monomer for the high Tg polymer. Both were mixed so that the nonvolatile content of the high Tg polymer solution was 20 parts with respect to 100 parts of the nonvolatile content of the same low Tg polymer solution as in Synthesis Example 8, and stirred well. 9 was obtained. It was confirmed by an optical microscope that it has a sea-island structure.

Experimental Example Each polymer solution No. The synthesis methods for 1 to 9 are summarized in Table 1, and each characteristic is shown in Table 2. The characteristic evaluation method is as follows.

[Tg]
It is Tg calculated by the above formula.

[Mass average molecular weight (Mw)]
GPC measuring 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 × 30 cm; “Styragel” is a registered trademark)
Ultra Styragel 100Å (7.8mm × 30cm)
Ultra Styragel 500Å (7.8mm × 30cm)
Solvent: Tetrahydrofuran (abbreviated as THF)
The sample concentration was 0.2%, the injection amount was 200 microliters / time, and the polystyrene standard sample conversion value was Mw.

  In the case of two-stage polymerization, the high Tg polymer (A) was sampled and Mw was measured before adding the second-stage monomer to the flask. Moreover, Mw of the whole polymer mixture was measured after completion | finish of two-stage polymerization.

[Tan δ]
Using rheometer (manufactured by TA Instruments Inc .; “ARES”), measured by shear mode, paraplate method (8 mmφ), angular vibration frequency 6.28 rad / s, measurement temperature range −50 to 150 ° C. did.

[Presence / absence of separation]
Polymer solution No. About 1-9, concentration adjustment is carried out with ethyl acetate so that a non volatile matter may be 30 mass%, respectively, and 50g is extract | collected to a beaker. After sufficiently stirring by hand, pour into a 12 mmφ test tube until the height of the liquid column reaches 100 mm, and seal the opening of the test tube so that the solvent does not volatilize. 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 a transparent part is generated at the upper or lower part of the liquid column, or when two phases having different turbidity are formed (for example, the upper 90 mm of the liquid column is strongly turbid, and the lower 10 mm is higher than the upper part, In the case of a slightly less turbid state), it was judged as “separated”.

[Adhesive properties]
The polymer solution was taken, and the nonvolatile content was adjusted to 34% with ethyl acetate. For 100 parts of polymer, 250 parts by weight of dibutyltin dilaurate as a crosslinking accelerator and 10 parts of “Duranate (registered trademark) D-201” (hexamethylene diisocyanate; bifunctional; manufactured by Asahi Kasei Co., Ltd.) as a crosslinking agent The corresponding amount was added and stirred well to obtain an adhesive composition.

  A polyethylene terephthalate (PET) film (manufactured by Toray Industries, Inc .; thickness 38 μm) is used as a supporting substrate, and the pressure-sensitive adhesive composition is applied so that the thickness after drying is 20 μm, and then dried at 100 ° C. for 2 minutes. Thus, an adhesive film was prepared. After sticking and protecting the PET film which gave the mold release process on the adhesive surface, it was cured in an atmosphere of 40 ° C. for 3 days. The pressure-sensitive adhesive film after curing was conditioned for 24 hours in an atmosphere of 23 ° C. and a relative humidity of 65%, and then cut into an appropriate length with a width of 25 mm to prepare a test tape. The release film was peeled off during the test.

  Using a 3 mm thick acrylic plate (standard test plate made by Nippon Test Panel Co., Ltd.) as an adherend, the test tape was reciprocated once with a 2 kg rubber roller in an atmosphere of 23 ° C. and 65% relative humidity. Crimp. After leaving for 25 minutes after pressure bonding, the peeling speed was 0.3 m / min for low speed peeling and 30 m / min for high speed peeling, and 180 ° peeling adhesive strength was measured in an atmosphere of 23 ° C. according to JIS K 6854. . Table 2 also shows the values obtained by dividing the low-speed peel adhesive strength, the high-speed peel adhesive strength, and the high-speed peel adhesive strength by the low-speed peel adhesive strength (shown as “high speed / low speed”).

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

  In Table 1, each monomer and molecular weight modifier are abbreviated as follows. The numbers on the right are the Tg (K) values of homopolymers listed in the polymer handbook.

VAC: Vinyl acetate 305K
BA: n-butyl acrylate 219K
2EHA: 2-ethylhexyl acrylate 203K
HEA: 2-hydroxyethyl acrylate 241K
MMA: Methyl methacrylate 378K
DM: Dodecyl mercaptan (molecular weight regulator)

  As is apparent from Table 2, the pressure-sensitive adhesive compositions of Examples 1 to 3 subjected to two-stage polymerization are excellent in storage stability without causing separation. Moreover, since the high Tg polymer (A) and the low Tg polymer (B) were blended in a well-balanced manner, the high-speed peel adhesive strength was small, and the high-speed / low-speed value was 15.0 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 force was large and zip peeling occurred.

  From a comparison between Example 4 in which the high Tg polymer (A) and the low Tg polymer (B) were blended with Reference Example 1, it was found that the adhesive properties deteriorated when the amount of the high Tg polymer (A) was too small. .

  Further, in Example 5 and Reference Example 2, since a MMA-based polymer different from a polymer having a refractive index of 2EHA or BA was used as the high Tg polymer (A), haze is not so good, but in Reference Example 2, It was found that since the Tg of the high Tg polymer (A) is too high, the peel force at low speed is too small and the adhesive force may be insufficient.

  In the solvent-type re-peeling pressure-sensitive adhesive composition of the present invention, since the high Tg polymer and the low Tg polymer have a sea-island structure, the combination of the high Tg polymer and the low Tg polymer can improve the high-speed peelability. did it. Moreover, the adhesive layer with small haze was also able to be formed.

  Accordingly, the pressure-sensitive adhesive product obtained using the pressure-sensitive adhesive composition has a surface of an optical member such as an optical polarizing plate (TAC), a retardation plate, an EMI (electromagnetic wave) shield film, an antiglare film, an antireflection film, or the like. It can be used as an adhesive product for re-peeling to protect. It can also be used as a protective film for the surface of other plastics and metal plates.

Claims (7)

A high Tg polymer (A) having a glass transition temperature (Tg) of 0 ° C. or higher and 70 ° C. or lower, a low Tg polymer (B) having a Tg lower than the high Tg polymer, and exhibiting pressure-sensitive adhesiveness, and a solvent. A solvent-type re-peeling pressure-sensitive adhesive composition,
The pressure-sensitive adhesive composition is obtained by polymerizing the monomer (A) for the high Tg polymer (A) by solution polymerization, and then the polymerization rate of the high Tg polymer (A) becomes 70 to 95% by mass. Obtained by polymerizing the monomer (B) for the low Tg polymer (B) in the presence of the high Tg polymer (A), starting the addition of the monomer (B) for the low Tg polymer (B),
When the total amount of the high Tg polymer (A) and the low Tg polymer (B) in the above-mentioned pressure-sensitive adhesive composition was adjusted to 30% by mass in terms of non-volatile content and then sealed and allowed to stand at 25 ° C. for 24 hours, high Tg The polymer (A) and the low Tg polymer (B) are not phase separated,
In the pressure-sensitive adhesive layer obtained from the above-mentioned pressure-sensitive adhesive composition, a high-Tg polymer (A) and a low-Tg polymer (B) form a sea-island structure without being compatible with each other. Adhesive composition.   When dynamic viscoelasticity is measured for a coating film obtained without crosslinking the pressure-sensitive adhesive composition, the peak of tan δ derived from the high Tg polymer (A) and the low Tg polymer (B) are derived. The solvent-type re-peeling pressure-sensitive adhesive composition according to claim 1, wherein the tan δ peak is observed separately.   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 65 to 65% by mass. The pressure-sensitive adhesive composition for solvent-based re-peeling according to claim 1 or 2, wherein the pressure-sensitive adhesive composition is 96% by mass.   4. The solvent-based re-peeling pressure-sensitive adhesive composition according to claim 3, wherein the low Tg polymer (B) is a continuous phase and the high Tg polymer (A) is dispersed in an island shape. . A pressure-sensitive adhesive product for re-peeling, wherein a pressure-sensitive adhesive layer obtained from the solvent-type re-peelable pressure-sensitive adhesive composition according to any one of claims 1 to 4 is formed on at least one surface of a support substrate. The adhesive product for re-peeling according to claim 5 , wherein the haze is 3% or less. When a 180 ° adhesive force to an acrylic plate was measured using an adhesive product having a 20 μm thick adhesive layer formed on a 38 μm thick polyethylene terephthalate film substrate, 0.05 μm was required for low-speed peeling at 0.3 m / min. ~0.3N / 25mm, a 0.5~3N / 25mm at 30 m / min fast peeling, and claim 5 divided by the adhesion at a slow peel adhesive force at high-speed peeling is 15.0 or less Or the adhesive product for re-peeling of 6 .