JP2010106230A - Tacky adhesive composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a tacky adhesive composition which exhibits excellent adhesiveness even when an adherend is a polyolefin resin such as a polypropylene resin and which is excellent in retentivity, weatherability and hot-melt coating properties at high temperature. <P>SOLUTION: The tacky adhesive composition contains at least one acrylic block copolymer selected from the group consisting of the block copolymer shown by (A-B)<SB>a</SB>-A, the block copolymer shown by (B-A)<SB>b</SB>-B and the block copolymer shown by (A-B)<SB>c</SB>, a tackifier and a plasticizer. The content of the plasticizer is within 25-100% of that of the tackifier. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a pressure-sensitive adhesive composition that is excellent in adhesiveness even when the adherend is a polyolefin-based resin such as a polypropylene-based resin and excellent in holding power at high temperatures, weather resistance, and hot-melt coating properties.

  Conventionally, pressure-sensitive adhesive compositions have been widely used as pressure-sensitive adhesive tapes, pressure-sensitive adhesives, and hot-melt adhesives. As such a pressure-sensitive adhesive composition, Patent Document 1 discloses a pressure-sensitive adhesive composition comprising a specific polymer and a pressure-sensitive adhesive composition comprising a polymer having an adhesive strength different from that of the polymer. .

  Patent Document 2 discloses a block copolymer having a specific structure in the polymer main chain and having a weight average molecular weight / number average molecular weight ratio within a specific range, and a specific diblock copolymer. A pressure-sensitive adhesive in which the weight ratio of the block copolymer to the diblock copolymer is within a specific range and the melt viscosity is a predetermined value or less is disclosed.

  Further, Patent Document 3 comprises an acrylic block copolymer, wherein the acrylic block copolymer is present in the composition in an amount of less than about 50% by weight based on the weight of the pressure sensitive adhesive composition. Is disclosed.

  However, although the above-mentioned pressure-sensitive adhesive composition is excellent in holding power, it has a problem that the pressure-sensitive adhesive force is not sufficiently developed and a slip stick phenomenon occurs.

Japanese Patent Laid-Open No. 10-30078 Japanese Patent Laid-Open No. 11-323072 JP 2004-204231 A

  The present invention provides a pressure-sensitive adhesive composition that is excellent in adhesiveness even when the adherend is a polyolefin-based resin such as a polypropylene-based resin, and has excellent holding power at high temperatures, weather resistance, and hot-melt coating properties. .

The pressure-sensitive adhesive composition of the present invention is at least selected from the group consisting of a block copolymer represented by (AB) _a -A, and a block copolymer represented by (CD) _b. A kind of acrylic block copolymer, a tackifier and a plasticizer are contained, and the content of the plasticizer is ¼ or more of the content of the tackifier and the same as the content of the tackifier. It is characterized by being below the amount.
(However, in the formula, A, B, C and D are independently a homopolymer block of an alkyl acrylate having 1 to 12 carbon atoms in an alkyl group or an alkyl methacrylate having 1 to 12 carbon atoms in an alkyl group. A and b represent an integer of 1 to 10.)

  A and B are homopolymer blocks of alkyl acrylate having 1 to 12 carbon atoms in the alkyl group or alkyl methacrylate having 1 to 12 carbon atoms in the alkyl group. In addition, the homopolymer block represented by A and the homopolymer block represented by B should just differ in the monomer component which comprises these homopolymer blocks.

  C and D are homopolymer blocks of alkyl acrylate having 1 to 12 carbon atoms in the alkyl group or alkyl methacrylate having 1 to 12 carbon atoms in the alkyl group. In addition, the homopolymer block represented by C and the homopolymer block represented by D should just differ in the monomer component which comprises these homopolymer blocks.

  The alkyl group having 1 to 12 carbon atoms in the alkyl group is not particularly limited, and examples thereof include methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, and i-propyl (meth). ) Acrylate, n-butyl (meth) acrylate, i-butyl (meth) acrylate, t-butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, n-hexyl (meth) acrylate, cyclohexyl (meth) acrylate, isobornyl (Meth) acrylate, n-octyl (meth) acrylate, lauryl (meth) acrylate, i-nonyl (meth) acrylate and the like can be mentioned. In addition, (meth) acryl means acryl or methacryl.

  When the carbon number of the alkyl group of the alkyl acrylate, which is a monomer component constituting the homopolymer block represented by A, B, C or D, is large, the molecular weight is lowered or the compatibility with the tackifier is lowered. The adhesive properties may be reduced due to the above, so the number is limited to 1 to 12, and 1 to 4 is preferable.

  When the carbon number of the alkyl group of the alkyl methacrylate that is a monomer component constituting the homopolymer block represented by A, B, C, or D is large, the molecular weight is lowered or the compatibility with the tackifier is lowered. The adhesive properties may be reduced due to the above, so the number is limited to 1 to 12, and 1 to 4 is preferable.

  Furthermore, the monomer component constituting the homopolymer block represented by A is preferably an alkyl methacrylate having 1 to 12 carbon atoms in the alkyl group, more preferably methyl methacrylate, t-butyl methacrylate, or isobornyl methacrylate. Preferred is methyl methacrylate.

  And as a monomer component which comprises the homopolymer block represented by B, for example, n-butyl acrylate, isobutyl acrylate, cyclohexyl acrylate, dodecyl acrylate, ethyl acrylate, methyl acrylate, nonyl acrylate, octyl acrylate, n -Propyl acrylate, n-butyl methacrylate, isobutyl methacrylate, cyclohexyl methacrylate, dodecyl methacrylate, ethyl methacrylate, methyl methacrylate, nonyl methacrylate, octyl methacrylate, n-propyl methacrylate and the like, and alkyl having 1 to 12 carbon atoms in the alkyl group Acrylates are preferred and n-butyl acrylate is preferred.

  Further, when the glass transition temperature of the homopolymer block represented by A is low, the holding power at high temperatures of the pressure-sensitive adhesive composition may be lowered, so that it is preferably 100 ° C. or higher, more preferably 100 to 150 ° C. preferable.

  In the present invention, the glass transition temperature of the homopolymer block can be measured by differential scanning calorimetry (DSC) according to the measurement method defined in JIS K7121, and the glass transition temperature is determined by the DSC heat capacity. It is the extrapolation start temperature of the transition region corresponding to the glass transition on the heating curve (intersection temperature obtained by extrapolating the straight line portion of the base line before transition and the tangent of the inflection point of the transition region).

  And, if the glass transition temperature of the homopolymer block represented by B is high, the rigidity of the pressure-sensitive adhesive composition becomes too high, and a slip stick phenomenon is likely to occur in the pressure-sensitive adhesive properties, and the pressure-sensitive adhesive force may be reduced. 30 ° C. or lower is preferable, and −30 to −80 ° C. is more preferable.

(A-B) In the block copolymer represented by _a- A, this block copolymer is a single polymer having the characteristics of A and B, but the weight average of the block copolymer When the molecular weight is the same and the value of a is increased, the respective characteristics are hardly expressed, and the characteristics as a block copolymer may be lost. Moreover, when the weight average molecular weight of each homopolymer block is the same and the value of a becomes large, the weight average molecular weight of a block copolymer will become high and the viscosity of an adhesive composition may become high. Therefore, the value of a is limited to an integer of 1 to 10, an integer of 1 to 3 is preferable, and 1 is more preferable.

And when the whole weight average molecular weight of the block copolymer represented by (A-B) _a -A is low, the holding power of the pressure-sensitive adhesive composition may be lowered at a high temperature. 10000 to 500000 is preferable, 30000 to 250,000 is more preferable, and 50000 to 200000 is particularly preferable.

In addition, when the overall weight average molecular weight of the block copolymer represented by (A-B) _a -A is low, the cohesive force of the pressure-sensitive adhesive composition may be reduced, and the adhesive performance may be reduced. Since the viscosity of the block copolymer becomes too high and the production of the pressure-sensitive adhesive composition may be hindered, 90000 or more is preferable, and 100000 to 200000 is more preferable.

Furthermore, when the content of the homopolymer block represented by A in the block copolymer represented by (A-B) _a -A is low, the cohesive force of the resulting pressure-sensitive adhesive composition becomes small, Adhesive properties such as holding power at high temperatures may be reduced, and if it is high, the adhesive strength of the resulting pressure-sensitive adhesive composition may be reduced, so 5 to 40% by weight is preferred, and 10 to 25% by weight is preferred. More preferred. For the same reason, the content of the homopolymer block represented by B in the block copolymer represented by (AB) _a -A is preferably 60 to 95% by weight, and 75 to 90% by weight. Is more preferable.

  Furthermore, the monomer component constituting the homopolymer block represented by C is preferably an alkyl methacrylate having 1 to 12 carbon atoms in the alkyl group, more preferably methyl methacrylate, t-butyl methacrylate, or isobornyl methacrylate. Preferred is methyl methacrylate.

  And as a monomer component which comprises the homopolymer block represented by D, for example, n-butyl acrylate, isobutyl acrylate, cyclohexyl acrylate, dodecyl acrylate, ethyl acrylate, methyl acrylate, nonyl acrylate, octyl acrylate, n -Propyl acrylate, n-butyl methacrylate, isobutyl methacrylate, cyclohexyl methacrylate, dodecyl methacrylate, ethyl methacrylate, methyl methacrylate, nonyl methacrylate, octyl methacrylate, n-propyl methacrylate and the like, and alkyl having 1 to 12 carbon atoms in the alkyl group Acrylates are preferred and n-butyl acrylate is preferred.

  Further, if the glass transition temperature of the homopolymer block represented by C is low, the holding power at high temperatures of the pressure-sensitive adhesive composition may be lowered, so that it is preferably 100 ° C. or higher, more preferably 100 to 150 ° C. preferable.

  And, if the glass transition temperature of the homopolymer block represented by D is high, the rigidity of the pressure-sensitive adhesive composition becomes too high, and the slip stick phenomenon is likely to occur in the pressure-sensitive adhesive property, and the pressure-sensitive adhesive force may be lowered. 30 ° C. or lower is preferable, and −30 to −80 ° C. is more preferable.

In addition, if the overall weight average molecular weight of the block copolymer represented by (CD) _b is low, the holding power of the pressure-sensitive adhesive composition may be lowered at a high temperature. Since it may rise, 10000-500000 are preferable and 15000-250,000 are more preferable.

Furthermore, when the content of the homopolymer block represented by C in the block copolymer represented by (CD) _b is low, the cohesive force of the resulting pressure-sensitive adhesive composition becomes small, Adhesive properties such as holding power may decrease, and if it is high, the adhesive strength of the resulting pressure-sensitive adhesive composition may decrease, so 2 to 30% by weight is preferable, and 5 to 15% by weight is more preferable. . For the same reason, the content of the homopolymer block represented by D in the block copolymer represented by (CD) _b is preferably 70 to 98% by weight, more preferably 75 to 95% by weight. preferable.

And, in the block copolymer represented by (C−D) _b , this block copolymer is a single polymer and has the characteristics of C and D, but the weight average of the block copolymer When the molecular weight is the same and the value of b is increased, the respective characteristics are hardly expressed and the characteristics as a block copolymer may be lost. Moreover, when the weight average molecular weight of each homopolymer block is the same and the value of b becomes large, the weight average molecular weight of a block copolymer will become high and the viscosity of an adhesive composition may become high. Therefore, the value of b is limited to an integer of 1 to 10, an integer of 1 to 3 is preferable, and 1 is more preferable.

  In the present invention, the number average molecular weight and weight average molecular weight of the entire acrylic block copolymer are determined by performing gel permeation chromatography (GPC) analysis using a tetrahydrofuran (THF) solution of the acrylic block copolymer. It refers to the converted molecular weight.

The pressure-sensitive adhesive composition of the present invention is at least selected from the group consisting of a block copolymer represented by (AB) _a -A, and a block copolymer represented by (CD) _b. Contains a type of acrylic block copolymer, but contains a block copolymer represented by (AB) _a -A and a block copolymer represented by (CD) _b It is preferable.

When the acrylic block copolymer contains a block copolymer represented by (AB) _a -A and a block copolymer represented by (CD) _b Is a weight ratio of the content of the block copolymer represented by (AB) _a -A and the content of the block copolymer represented by (CD) _b ((AB) _If the content of the block copolymer represented by _a- A / (the content of the block copolymer represented by (CD) _b ) is small, the peel strength of the resulting pressure-sensitive adhesive composition and In some cases, the holding power in the case may be reduced. Therefore, it is preferably larger than 1, more preferably 2.1 or more, particularly preferably 5 or more, and most preferably 5 to 15.

  A method for synthesizing the acrylic block copolymer is not particularly limited. For example, a living polymerization method, a method using an initiator having an initiation point having different reactivity, and a reactive group and an initiation point in one molecule. Examples thereof include a method using an initiator, an ultraviolet polymerization method, an anionic polymerization method, a cationic polymerization method, and a polymerization method using an organic rare earth metal complex.

  A synthesis method using an initiator having a reactive group and an initiation point in one molecule is not particularly limited. For example, a method using an initiator having at least one peroxide group and one vinyl group in one molecule. Is mentioned.

  According to the method of using an initiator having at least one peroxide group and one vinyl group in one molecule, the vinyl monomer or the alkyl having 1 to 12 carbon atoms in the alkyl group (initiator different from the initiator) After copolymerizing the (meth) acrylate and the vinyl group of the initiator and polymerizing the homopolymer block represented by A or the homopolymer block represented by B, the peroxide group of the initiator By polymerizing the monomer constituting the other block, the homopolymer block represented by A or the homopolymer block represented by B can be polymerized to synthesize an acrylic block copolymer. .

  Moreover, according to the living polymerization method, for example, polymerization of either a vinyl monomer or an alkyl (meth) acrylate having an alkyl group having 1 to 12 carbon atoms is performed using a living polymerizable initiator. When the homopolymer block represented by A or the homopolymer block represented by B is completely polymerized, the monomer constituting the other homopolymer block is added and further polymerized at the end of the growing chain. An acrylic block copolymer can be synthesized by reacting and polymerizing the homopolymer block represented by B or the homopolymer block represented by A.

  Specifically, as the living polymerization method, for example, N, N, N ′, N′-tetraethyllithium disulfide, benzyl-N, N-diethyldithiocarbamate, p-xylenebis (N, N-diethyldithiocarbamate) A method using an iniferter as an initiator, a method using an organic lanthanoid compound as an initiator, an anionic polymerization method using alkyllithium or the like as an initiator, a group transfer method using silylketene acetal or the like as an initiator, an aluminum porphyrin as an initiator Each method known in the art such as a method used as a metal free living anion method and a living radical method can be employed.

  The method using an initiator having an initiation point with different reactivity is not particularly limited. For example, a method using an initiator having at least two peroxide groups with different radical generation temperatures, and a peroxide group with different radical generation mechanisms. For example, a method using an initiator having at least two can be employed.

  According to the method using an initiator having at least two peroxide groups having different radical generation temperatures, either the vinyl monomer or the alkyl (meth) acrylate having 1 to 12 carbon atoms in the alkyl group from the low temperature side starting point is used. After starting the polymerization of the homopolymer block represented by A or the homopolymer block represented by B, another polymer or copolymer is constituted from the high temperature side starting point. By initiating polymerization of the monomer, the homopolymer block represented by B or the homopolymer block represented by A can be polymerized to synthesize an acrylic block copolymer.

  According to the method using an initiator having at least two peroxide groups having different radical generation mechanisms, for example, a radical is generated using a reducing agent at one starting point, and the number of carbon atoms of the vinyl monomer or alkyl group is reduced. The polymerization of any one of 1 to 12 alkyl (meth) acrylates is started, and after the polymerization of the homopolymer block represented by A or the homopolymer block represented by B is initiated, the temperature is raised. From the other starting point, the polymerization of the monomer constituting the other homopolymer block is started, and the homopolymer block represented by B or the homopolymer block represented by A is polymerized to produce an acrylic block Copolymers can be synthesized.

Specifically, an alkyl (meth) acrylate having 1 to 12 carbon atoms in an alkyl group and a radical polymerization initiator having two or more peroxide groups in one molecule are heated at a set temperature level 1. A polymer comprising an alkyl (meth) acrylate having an alkyl group having 1 to 12 carbon atoms or a copolymer comprising an alkyl (meth) acrylate having an alkyl group having 1 to 12 carbon atoms, A block copolymer represented by (C−D) _b can be synthesized by adding a monomer for two blocks and performing a heat reaction at a temperature level 2 set higher than the above temperature level 1.

According to the ultraviolet polymerization method, for example, an alkyl (meth) acrylate having 1 to 12 carbon atoms in the alkyl group or a vinyl monomer and N, N-diethyldithiocarbamate are mixed, and the inside of the reaction vessel is purged with nitrogen, Irradiate ultraviolet rays using an ultraviolet lamp to polymerize or copolymerize alkyl (meth) acrylates having 1 to 12 carbon atoms in the alkyl group, or polymerize or copolymerize vinyl monomers, and then vinyl monomers or Add an alkyl (meth) acrylate having 1 to 12 carbon atoms in the alkyl group, and further polymerize or copolymerize a vinyl monomer by irradiation with ultraviolet rays, or an alkyl (meth) having 1 to 12 carbon atoms in the alkyl group by polymerizing or copolymerizing an acrylate, it is possible to synthesize a block copolymer represented by _{(a-B) a} -A .

  Other methods include, for example, vinyl polymers having an azo group, vinyl copolymers having an azo group, or alkyl groups having 1 to 12 carbon atoms. A polymer made of (meth) acrylate having an azo group, or a copolymer made of alkyl (meth) acrylate having an alkyl group having 1 to 12 carbon atoms and having an azo group is polymerized. , A method of polymerizing a monomer constituting another polymer or copolymer starting from the azo group, a vinyl polymer or vinyl copolymer in advance by ordinary radical polymerization, and the carbon number of the alkyl group By polymerizing a polymer or copolymer consisting of 1 to 12 alkyl (meth) acrylates, then mixing them and irradiating them with ultraviolet rays, electron beams, radiation, etc. , It may also be employed and a vinyl polymer or vinyl copolymer, a method and to block binding of a polymer or copolymer having a carbon number consists 1-12 alkyl (meth) acrylates of an alkyl group.

The pressure-sensitive adhesive composition of the present invention contains a tackifier in order to impart tackiness to the pressure-sensitive adhesive composition. Such tackifier is not particularly limited, for example, C ₅ petroleum resins, C ₉ petroleum resins, rosin resins, rosin ester resins, terpene resins, terpene phenol resins, coumarone-indene resins, C ₅ based hydrogenated petroleum resins, C ₉ based hydrogenated petroleum resins, hydrogenated rosin resins, hydrogenated rosin ester resins, hydrogenated terpene resins, hydrogenated terpene phenol resin, hydrogenated coumarone-indene resins, disproportionated rosin resins, disproportionated Rosin ester resin, polymerized rosin resin, polymerized rosin ester resin, styrene resin, phenol resin, xylene resin and the like, and hydrogenated rosin ester resin is preferred. In addition, a tackifier may be used independently or 2 or more types may be used together.

  Also, if the softening point of the tackifier is low, the heat resistance of the pressure-sensitive adhesive composition is lowered and the holding power at high temperatures is lowered, so that it is preferably 85 ° C. or higher, more preferably 100 ° C. or higher. From the applicability as an adhesive, 150 degrees C or less is preferable.

  If the content of the tackifier in the pressure-sensitive adhesive composition is small, the tackiness of the pressure-sensitive adhesive composition may be lowered, so that it is preferably 10 parts by weight or more with respect to 100 parts by weight of the acrylic block copolymer, When the amount is too large, the cohesive force of the pressure-sensitive adhesive composition becomes weak, and the pressure-sensitive adhesive property of the pressure-sensitive adhesive composition may be lowered. Therefore, 40 to 1000 parts by weight is more preferable.

  Furthermore, the pressure-sensitive adhesive composition contains a plasticizer. This is because the pressure-sensitive adhesive composition contains a tackifier as described above. However, if the pressure-sensitive adhesive composition is contained, the pressure-sensitive adhesive composition becomes hard and a slip-stick phenomenon occurs in the pressure-sensitive adhesive composition. Adhesive performance may be reduced. Therefore, by adding a plasticizer to the pressure-sensitive adhesive composition, flexibility is imparted to the pressure-sensitive adhesive composition to prevent the pressure-sensitive adhesive performance from deteriorating.

  The plasticizer is not particularly limited, and examples thereof include low molecular weight polymers such as acrylic polymers, animal and vegetable oils and mineral oils or derivatives thereof, dibutyl phthalate, dioctyl phthalate, bis-2-ethylhexyl phthalate, didecyl phthalate, diisodecyl. Aphthalate such as phthalates such as phthalate, adipates such as bis-2-ethylhexyl adipate and dioctyl adipate, sebacates such as bis-2-ethylhexyl sebacate and dibutyl sebacate, and bis-2-ethylhexyl azelate Fatty acid esters such as esters, paraffins such as chlorinated paraffin, glycols such as polypropylene glycol, epoxy polymer plasticizers such as epoxidized soybean oil and epoxidized linseed oil, trioctylpho Examples include phosphoric acid esters such as phosphate and triphenyl phosphate, phosphorous acid esters such as triphenyl phosphite, and ester oligomers such as esterified products of adipic acid and 1,3-butylene glycol. A low molecular weight acrylic polymer is preferred because of good compatibility with the copolymer and easy development of properties. A plasticizer may be used independently or 2 or more types may be used together.

  Further, when the content of the plasticizer in the pressure-sensitive adhesive composition is small, the flexibility of the pressure-sensitive adhesive composition is lowered and slip stick phenomenon is likely to occur. Therefore, it is limited to ¼ or more of the content (weight) of the tackifier and not more than the same weight as the content (weight) of the tackifier, and ½ of the content (weight) of the tackifier. It is preferable that the content is equal to or less than the content (weight) of the tackifier.

  Further, the plasticizer is preferably an acrylic polymer having a weight average molecular weight of 1000 to 10,000 and a glass transition temperature of 0 ° C. or lower. If the weight average molecular weight of the acrylic polymer is low, the holding power of the pressure-sensitive adhesive composition may be reduced, and if it is high, the melt viscosity of the pressure-sensitive adhesive composition may be increased. 1500 to 6000 is more preferable. Moreover, since the adhesive force of an adhesive composition may fall when the glass transition temperature of the said acrylic polymer is high, 10 degrees C or less is preferable and 0-80 degreeC is more preferable. In addition, the glass transition temperature of an acrylic polymer means what was measured based on JISK7121.

  In addition, the following acrylic polymer is mentioned as a commercial item of low molecular weight polymers, such as an acrylic polymer which can be used as a plasticizer. As the non-functional group type acrylic polymer, for example, “ARUFON UP-1000” (weight average molecular weight: 3000, glass transition temperature: −77 ° C.) manufactured by Toa Gosei Co., Ltd., “ARUFON UP-1010” (weight average molecular weight) : 1700, glass transition temperature: −31 ° C.), “ARUFON UP-1020” (weight average molecular weight: 2000, glass transition temperature: −80 ° C.), “ARUFON UP-1021” (weight average molecular weight: 1600, glass transition temperature) : -71 ° C.), “ARUFON UP-1110” (weight average molecular weight: 2500, glass transition temperature: −64 ° C.). As the hydroxyl group-containing type acrylic polymer, “ARUFON UH-2032” (weight average molecular weight: 2000, glass transition temperature: −60 ° C.) manufactured by Toa Gosei Co., Ltd., “ARUFON UH-2041” (weight average molecular weight: 2500, Glass transition temperature: −50 ° C.). Examples of the carboxyl group-containing acrylic polymer include “ARUFON UC-3510” (weight average molecular weight: 2000, glass transition temperature: −50 ° C.) manufactured by Toa Gosei Co., Ltd. Examples of the epoxy group-containing acrylic polymer include “ARUFON UG-4000” (weight average molecular weight: 3000, glass transition temperature: −61 ° C.) manufactured by Toa Gosei Co., Ltd., and “ARUFON UG-4010” (weight average molecular weight). : 2900, glass transition temperature: -57 ° C). Examples of the alkoxysilyl group-containing acrylic polymer include “ARUFON US-6110” (weight average molecular weight: 2500, glass transition temperature: −57 ° C.) manufactured by Toa Gosei Co., Ltd.

  In the pressure-sensitive adhesive composition of the present invention, additives such as an antioxidant, an ultraviolet absorber, and a carboxylic acid metal salt may be added within a range that does not impair the physical properties.

  The pressure-sensitive adhesive composition of the present invention can be obtained by adding a tackifier and a plasticizer and, if necessary, an additive to an acrylic block copolymer and heating and mixing.

  When the storage elastic modulus G ′ at 18 ° C. in the pressure-sensitive adhesive composition is low, the cohesive force of the pressure-sensitive adhesive composition is reduced, and the holding power of the pressure-sensitive adhesive composition at high temperatures may be reduced. Since the slip stick phenomenon may occur in the pressure-sensitive adhesive composition, 80,000-230,000 Pa is preferable. The storage elastic modulus G ′ at 18 ° C. in the pressure-sensitive adhesive composition can be measured by a dynamic property test method based on JIS K6394.

  Here, the adjustment method of the storage elastic modulus G 'in 18 degreeC in an adhesive composition is demonstrated. The storage elastic modulus G ′ at 18 ° C. of the produced pressure-sensitive adhesive composition is measured, and if it is less than 80000 Pa, any one of the following methods 1) to 5) may be selected and adjusted. When the storage elastic modulus G ′ at 18 ° C. of the produced pressure-sensitive adhesive composition exceeds 230000 Pa, the procedure opposite to the procedure of 1) to 5) below may be performed.

  1) Increasing the content of the tackifier added to the currently produced pressure-sensitive adhesive composition. As a procedure for increasing the content of the tackifier, the amount may be increased by using 1/10 to 1/5 of the amount of the tackifier already added to the pressure-sensitive adhesive composition as a guide.

  2) A tackifier having a softening point of 85 ° C. or higher is further added to the currently produced pressure-sensitive adhesive composition.

  3) When the amount of the tackifier contained in the currently produced pressure-sensitive adhesive composition cannot be increased, the amount of the plasticizer contained in the pressure-sensitive adhesive composition is reduced.

  4) A plasticizer having a high glass transition temperature or a softening point or a plasticizer having a higher viscosity is further added to the pressure-sensitive adhesive composition currently produced.

5) Increase the amount of the block copolymer represented by (AB) _a -A. In particular, the amount of the block copolymer represented by (AB) _a -A containing 20% by weight or more of a copolymer block having a glass transition temperature of 100 ° C. or higher is increased. The amount is increased by an amount corresponding to 1/5 of the amount of the acrylic block copolymer in the currently produced pressure-sensitive adhesive composition.

  Moreover, when the peak temperature of tan δ at −30 to 40 ° C. in the pressure-sensitive adhesive composition is low, the cohesive force of the pressure-sensitive adhesive composition at room temperature or higher may be reduced, and the holding power may be reduced. Since the pressure-sensitive adhesive composition may cause a slip stick phenomenon at room temperature to lower the peel strength, −12 to 9 ° C. is preferable. The storage elastic modulus G ′ at 18 ° C. in the pressure-sensitive adhesive composition can be measured by a dynamic property test method based on JIS K6394.

  The peak temperature of tan δ at −30 to 40 ° C. in the produced pressure-sensitive adhesive composition is measured, and if it is less than −12 ° C., any one of the above methods 1) to 5) is selected and adjusted. That's fine. In addition, what is necessary is just to perform the procedure contrary to the procedure of said 1) -5) when the peak temperature of tan-delta in -30-30 degreeC in the produced adhesive composition exceeds 9 degreeC.

  Since the pressure-sensitive adhesive composition of the present invention has the above-described configuration, it has excellent adhesiveness and excellent holding power at high temperatures, weather resistance, and hot melt coating properties.

(Examples 1-6, Comparative Examples 1-4)
Table 1 shows the acrylic block copolymer composed of the triblock copolymer represented by ABA and the diblock copolymer represented by CD shown in Table 1. A predetermined amount of hydrogenated rosin ester resin (trade name “KF399S” manufactured by GUANGZHOU KOMO CHEMICALS CO., LTD., Softening point: 104 ° C.) and a low molecular weight acrylic polymer (trade name “ARUFON UP-1110” manufactured by Toagosei Co., Ltd.) Glass transition temperature: -64 ° C, weight average molecular weight: 2500) was added and melted and kneaded at 180 ° C to obtain an adhesive composition. In Table 1, the triblock copolymer represented by ABA is represented by “ABA”, and the diblock copolymer represented by CD is represented by “CD”. did.

  In the triblock copolymer represented by A-B-A, A is a homopolymer block of methyl methacrylate, and B is a homopolymer block of n-butyl acrylate. In the triblock copolymer represented by A-B-A, the glass transition temperature of the homopolymer block represented by A is 122 ° C., and the glass transition temperature of the homopolymer block represented by B is − It was 45 degreeC, content of the homopolymer block represented by A was 25 weight%, and the weight average molecular weight of the homopolymer block represented by A was 11400. The overall weight average molecular weight of the triblock copolymer represented by A-B-A was 107,000.

  In the diblock copolymer represented by CD, C was a homopolymer block of methyl methacrylate, and D was a homopolymer block of n-butyl acrylate. In the triblock copolymer represented by CD, the glass transition temperature of the homopolymer block represented by C is 122 ° C., and the glass transition temperature of the homopolymer block represented by D is −45 ° C. The content of the homopolymer block represented by C is 7% by weight, the content of the homopolymer block represented by D is 93% by weight, and the homopolymer block represented by C The weight average molecular weight of was 4,700. The overall weight average molecular weight of the triblock copolymer represented by CD was 92400.

  The obtained pressure-sensitive adhesive composition was measured for the storage elastic modulus G ′ at 18 ° C., the peak temperature of tan δ at −30 to 40 ° C., the holding power and the adhesive strength in the following manner, and the results are shown in Table 1. It was.

(Storage modulus G ′ at 18 ° C.)
The storage elastic modulus G ′ at 18 ° C. of the pressure-sensitive adhesive composition was measured according to JIS K6394. Specifically, using a dynamic viscoelasticity measuring apparatus (trade name “DVA-200” manufactured by IT Measurement Control Co., Ltd.), a test temperature of −80 to 200 ° C., a temperature rising condition of 5 ° C./min, shearing as a deformation method, The storage elastic modulus G ′ at 18 ° C. of the pressure-sensitive adhesive composition was measured under the condition of a frequency of 10 Hz.

(Peak temperature of tan δ at -30 to 40 ° C)
The peak temperature of tan δ at −30 to 40 ° C. of the pressure-sensitive adhesive composition was measured according to JIS K6394. Specifically, using a dynamic viscoelasticity measuring apparatus (trade name “DVA-200” manufactured by IT Measurement & Control Co., Ltd.), a test temperature of −80 to 200 ° C., a temperature rising condition of 5 ° C./min, shearing as a deformation method, Under the condition of a frequency of 10 Hz, the tan δ peak temperature of the pressure-sensitive adhesive composition at −30 to 40 ° C. was measured.

(Holding power)
A pressure-sensitive adhesive composition was applied to one surface of a polyethylene terephthalate film having a thickness of 38 μm with a thickness of 30 μm to prepare a pressure-sensitive adhesive tape. The holding force of this adhesive tape was measured according to JIS Z0237. Specifically, a test piece having a width of 25 mm and a length of 25 mm was cut out from the adhesive tape, this test piece was attached to a stainless steel (SUS304) plate, and a 1 kg weight was placed on the lower end of the test piece in an atmosphere of 50 ° C. The moving distance of the test piece from the start of the test after 1 hour had passed after hanging was measured.

(Adhesive force)
A pressure-sensitive adhesive composition was applied to one surface of a polyethylene terephthalate film having a thickness of 38 μm with a thickness of 30 μm to prepare a pressure-sensitive adhesive tape. The adhesive strength of this adhesive tape was measured in accordance with JIS Z0237. Specifically, a test piece having a width of 25 mm and a length of 100 mm was cut out from the adhesive tape, this test piece was stuck on a polypropylene plate having a thickness of 3 mm, and the peeling rate was 30 cm / min at 25 ° C. and 180 °. The film was peeled in the direction of °, and the adhesive strength was measured by peeling the adhesive tape 180 °. In Comparative Examples 1 and 3, a slip stick phenomenon occurred.

Claims (2)

(AB) at least one acrylic block copolymer selected from the group consisting of a block copolymer represented by _a- A, and a block copolymer represented by (CD) _b , It contains a tackifier and a plasticizer, and the content of the plasticizer is ¼ or more of the content of the tackifier and equal to or less than the content of the tackifier. Adhesive composition.
(However, in the formula, A, B, C and D are independently a homopolymer block of an alkyl acrylate having 1 to 12 carbon atoms in an alkyl group or an alkyl methacrylate having 1 to 12 carbon atoms in an alkyl group. A and b represent an integer of 1 to 10.) Acrylic block copolymer comprises a block copolymer represented by A-B-A, and a block copolymer represented by (C-D) _b, it is represented by A-B-A Weight ratio of content of block copolymer and content of block copolymer represented by (CD) _b (content of block copolymer represented by ABA / (C -D) The pressure-sensitive adhesive composition according to claim 1, wherein the content of the block copolymer represented by _b ) is greater than 1.
(In the formula, A is a homopolymer block made of alkyl methacrylate having 1 to 12 carbon atoms in the alkyl group and having a glass transition temperature of 100 ° C. or higher. B has 1 carbon atom in the alkyl group.) A homopolymer block of -12 alkyl acrylate or alkyl methacrylate having 1 to 12 carbon atoms and a glass transition temperature of 30 ° C. or less, C is an alkyl methacrylate having 1 to 12 carbon atoms in the alkyl group And D is a homopolymer of an alkyl acrylate having 1 to 12 carbon atoms in the alkyl group or an alkyl methacrylate having 1 to 12 carbon atoms in the alkyl group. (It is a coalesced block and has a glass transition temperature of 30 ° C. or lower.)