JPS61268777A - Pressure-sensitive adhesive composition - Google Patents

Abstract

PURPOSE:To provide the titled composition having high adhesivity to rough surface and suitable as an adhesive tape for packaging, adhesive tape for masking in painting, adhesive label, etc., containing a specific elastomeric block copolymer as a base polymer and containing a tackifier resin. CONSTITUTION:The objective composition contains (A) 100pts.wt. of a block copolymer composed of a nonelastomer block and an elastomer block containing conjugated diene compound as the constituent monomer and (B) 20-300pts.wt. of a tackifier resin, and has a tensile strength of <=20kg/cm<2> and breaking extension of >=500% at normal temperature. The content of cis-1,4-bond in the conjugated diene compound constituting the elastomer block of the component A is >=50%, and the component B contains >=3wt% resin having a softening point of <=10 deg.C.

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention provides a pressure-sensitive adhesive with excellent rough surface adhesion that is useful for adhesive articles such as packaging adhesive tapes, paint masking adhesive tapes, and adhesive labels. The present invention relates to a composition, and particularly to the adhesive composition described above whose base polymer is a block copolymer consisting of a non-elastomer block and an elastomer block whose constituent monomer is a conjugated diene compound.

[Conventional technology]

Traditionally, natural rubber has been used as a base polymer for adhesive applications that require light (press-bonding) adhesion to the adherend, such as adhesive tapes for packaging, adhesive tapes for paint masking, and adhesive labels. Adhesive compositions using rubbery polymers such as Therefore, it is generally treated as an organic solvent solution type.
In this case, it is necessary to volatilize organic solvents when manufacturing tapes, labels, etc., which may harm the health of workers.
There were problems such as the risk of fire.

Therefore, in recent years, hot-melt type or high-concentration type pressure-sensitive adhesive compositions that use no or little organic solvent have begun to attract attention as adhesive compositions to solve this problem.・A-B-A as a polymer
type block copolymers, such as styrene-isoprene-styrene type block copolymers and styrene-butadiene-styrene type block copolymers, have come into use.

[Problem that the invention seeks to solve]

However, pressure-sensitive adhesive compositions using block copolymers as the base polymer have advantages such as excellent creep properties; If the adhesion performance to the adherend surface is insufficient and the adhesive article is pasted on the adherend surface and left for a long period of time (if the adhesive article itself shrinks or external force is applied to the article, the article may become attached). There have been problems such as the adhesive article gradually peeling off from the surface, and when an external impact is applied to the attached adhesive article, it easily peels off because it lacks the ability to absorb and cushion the impact.

In practice, these problems significantly reduce reliability in terms of quality of adhesive products in case of (a), and in case of (a), cardboard, which is one of the typical uses of adhesive products such as adhesive tape, If used to seal a box, it would lead to serious drawbacks such as the box being opened unexpectedly during transportation.

Therefore, in order to eliminate the drawbacks of adhesive compositions that use block copolymers as base polymers, it is possible to use a combination of two or more block copolymers with different properties, or to add additive components. Although various improvement measures have been proposed, such as devising techniques, sufficient results have not yet been obtained to overcome the above-mentioned problems, and in particular, rough surface adhesion under light pressure bonding is significantly inferior. The reality is that this problem has hardly been resolved.

Therefore, the present invention solves the above-mentioned problems and provides an adhesive composition having a block copolymer as a base polymer, which can adhere well to rough surfaces such as corrugated paper and plywood under light pressure bonding, and It is an object of the present invention to provide a pressure-sensitive adhesive composition that also has the ability to absorb and alleviate external impact, and thus exhibits significantly superior rough surface adhesion compared to conventional compositions of this type.

[Means for solving problems]

As a result of intensive studies to achieve the above object, the inventors found that in conventional A-B-A block copolymers, non-elastomer blocks made of polystyrene aggregate molecularly, resulting in a type of physical Because it has a pseudo-crosslinked structure called crosslinking, it forms a strong adhesive coating even when blended with tackifying resins, softeners, etc., and as a result it has the advantage of exhibiting excellent creep properties. However, it was found that the above-mentioned properties on the contrary inhibit penetration into the irregularities of the rough surface, and this is a major cause of the decrease in rough surface adhesion.

In other words, a strong coating film has poor adhesion to uneven surfaces under slight pressure, and even if it is made to adhere strongly to uneven surfaces by strong pressure, if it is left for several days, temperature and humidity changes. Due to the expansion and contraction of the tape support and the adherend, the adhesive gradually separates from the uneven surface, resulting in a decrease in adhesion and, ultimately, interfacial peeling.

Furthermore, when an external impact is applied, the adhesive causes cohesive failure, and the shear caused by this cohesive failure makes it difficult to impart the function of alleviating the external impact, which causes interfacial delamination.

Therefore, the inventors conducted further studies to improve rough surface adhesion by reducing the toughness of the adhesive coating, that is, by improving the mechanical properties of the adhesive composition. A durable bond with a tensile strength of the adhesive at room temperature of 20 Ky/cII or less and a breaking elongation of 500% or more, which is determined by the type of combination and the type and amount of additives such as tackifier resin added to it. When the adhesive composition is used, it is possible to adhere well to uneven surfaces even under slight pressure, and since this adhesion is developed by the plastic flow of the adhesive, a decrease in oral adhesion does not occur. Furthermore, we obtained the knowledge that when an external impact is applied, the adhesive causes cohesive failure, and the shear behavior of the adhesive based on this failure can successfully absorb and alleviate the external impact.

As already mentioned, the conventional adhesive composition of this type uses an A-B-A type block copolymer as a base polymer, and generally contains 80 to 120 parts by weight of a tackifier resin per 100 parts by weight of this polymer. Most of them are in the mixing section. The base polymer itself generally has a tensile strength of 100 Ky/crt at room temperature! Therefore, the tensile strength of the adhesive far exceeds 20 kg/i at room temperature. Furthermore, even if the above-mentioned strength could be reduced to 20 Kg/cJ or less depending on the type of tackifying resin, the elongation at break would be less than 500%.

In other words, none of the conventional adhesive compositions of this type satisfy the above conditions.

In this way, the inventors found that the tensile strength at room temperature of an adhesive composition containing an additive such as a tackifying resin is 2.
By selecting and using a block copolymer that has a breaking elongation of 500% or more at 0h/c+yf or less,
They found that rough surface adhesion can be improved, and they also identified the bonding mode of the conjugated diene compound in the elastomer block constituting the block copolymer, and also determined that adhesiveness, which is one of the essential components of adhesive compositions, could be improved. It has been found that using a specific property-imparting resin is an extremely important factor in improving rough surface adhesion.

In other words, the surfaces of corrugated paper, plywood, etc. have extremely fine irregularities, and in order to achieve good adhesion to these irregularities with slight pressure, the mechanical properties of the adhesive must be set as described above. In addition, it has been found that it is important to specify the bonding mode of the conjugated diene compounds that constitute the elastomer block. In other words, the elastomer block has a structure in which conjugated diene compounds are bonded in any of the following bonding modes: cis-1,4-bonds, trans-4-bonds, 1,2-bonds, and 3,4-bonds. Among these bonds, the higher the content of cis-1 and 4 bonds, the better the adhesion to rough surfaces will be exhibited even under light pressure bonding force.In particular, when cis-1 and 4 bonds account for 50% or more of the total bonds, rough surface adhesion will be better. It has been found that this material significantly improves surface adhesion.

In addition, the surfaces of the corrugated paper and plywood mentioned above are not only finely uneven, but also have countless fluff-like fibers or protrusions. It is necessary for the adhesive to penetrate between the objects, and if this penetration is insufficient, minute deformation and peeling will progress over time, and there is a risk that interfacial peeling will eventually occur. This tendency becomes especially noticeable under high load conditions.

In order to improve the above-mentioned permeability, the inventors have discovered that at least 3% by weight of the tackifying resin has a softening point of 10°.
By selecting and using a material that has a rating of C or less, it is possible to penetrate well into the spaces between the fluffy substances, and in particular, the effect of rapidly expanding wetting after being applied to a rough surface is obtained. We learned that this allows for extremely strong adhesion to rough surfaces, and that it is possible to suppress interfacial peeling over time even under high loads.

This invention has been made based on the above findings, and its gist is to provide a block copolymer consisting of a non-elastomer block and an elastomer block whose constituent monomer is a conjugated diene compound, and a block copolymer of this block copolymer. Contains 20 to 300 parts by weight of tackifying resin and 100 parts by weight of the combined material, and has a tensile strength of 20 kg/
cJ or less, the elongation at break is 500% or more, the content of cis-1,4 bonds in the conjugated diene compound constituting the elastomer block is 50% or more, and the tackifying resin has a softening point of 10 The present invention provides a pressure-sensitive adhesive composition containing at least 3% by weight of a resin having a grade of C or lower.

In this specification, the tensile strength and elongation at room temperature of a block copolymer or a pressure-sensitive adhesive composition containing this copolymer refer to tax, a strip-shaped test piece with a width of 5 cm was prepared, and both ends of the test piece in the length direction were fixed with a chuck interval of 10 m, at a tensile rate of 50 fl/min, and at a measurement temperature of 20 to 23 cm.
It means the strength and elongation at break when stretched at ℃.

In addition, the content of cis-1.4 bonds in the conjugated diene compound constituting the elastomer block refers to the content of cis-1.4 bonds in the total elastomer block of one or more block copolymers. binding mode (trans-
1.4 bonds, 1.2 bonds, and 3.4 bonds), and the measurement was carried out by nuclear magnetic resonance method.

Furthermore, the softening point indicating the characteristics of the tackifier resin means a value measured by the ring and ball method (JIS K2207).

In addition, in this specification, the term "number average molecular weight" refers to G
PC (gel permeation chromatography) refers to the average molecular weight determined in terms of polystyrene.

[Structure and operation of the invention]

The block copolymer in this invention is a block copolymer consisting of a non-elastomer block and an elastomer block whose constituent monomer is a conjugated diene compound, and is an adhesive composition formed by blending a tackifying resin and other additive components. The tensile strength of the object is 20Kg/CI! In the following, those having a breaking elongation of 500% or more are selected and used.

Block copolymers that provide such properties include:
Its own tensile strength is 100 Kg/'ffl or less, especially 80 Kg/cd or less, and the elongation at break is 1,000% or more,
In particular, it is desirable that it be 1,500% or more.

The conventional general-purpose A-B-A type block copolymer does not satisfy the above characteristics as described above, and cannot be used alone as the block copolymer of the present invention.

The above-mentioned block copolymer according to the present invention may be used alone or as a mixture of two or more kinds, and in the case of a mixture, it is sufficient that the tensile strength and elongation at break of the mixture satisfy the above ranges. Therefore, the use of the conventional general-purpose A-B-A type block copolymers is not particularly excluded as long as they can be used in combination with other block copolymers to satisfy the above characteristics.

Examples of such block copolymers include A
Knee B1 type block copolymer (A1 is a non-elastomer block, B1 is an elastomer block whose constituent monomer is a conjugated diene compound) and A2-82-A3 type block copolymer and/or (A4-BJnX type block copolymer) (A2, A3-A4 has a number average molecular weight of 10,
000 or more non-elastomeric blocks, B2. B3 is an elastomer block having a conjugated diene compound as a constituent monomer, X is a coupling agent residue, and n is an integer from 2 to 6).

The above A1-B type block copolymer has a number average molecular weight of A1 of usually i,ooo or more, preferably 2,000 to 10
0.000, and the number average molecular weight of B1 is usually 5,000 or more, preferably 10,000 to 250,000,
The number average molecular weight of the entire copolymer is 10,000 to 300.
It is preferable that it be in the range of 000. Further, the content of A□ is desirably 50% by weight or less, particularly 5 to 20% by weight of the entire copolymer.

In addition, A2. of the A2-B2-A3 type block copolymer and the (A4-83)n
The number average molecular weight of A3°A4 is io, ooo or more, preferably in the range of 10,000 to 50,000, and B2.
The number average molecular weight of B3 is 15,000 or more, preferably 3
It is preferably in the range of 0,000 to soo, ooo, and the number average molecular weight of the entire copolymer is 50,000 to 50.
Preferably, it is in the range of 0,000. Also, A2. A
It is preferable that the total content of 3 and the total content of n A4s is 50% by weight or less, particularly 5 to 20% by weight, based on the total weight of each copolymer.

In addition, X in the above (A4-83) n It is a residue of a ring agent, and examples of such coupling agents include silicon tetrachloride, silicon tetrabromide, silicon dimethyldichloro, silicon monomethyldichloro, and 1,2-bis(
Examples include trichlorosilyl) ethale, dichloroethane, methylene chloride, dibromomethane, divinylbenzene, divinyltoluene, dibromoethane, and tin tetrachloride.

The A1-81 type block copolymer having such a structure and the A, -82-A3 type block copolymer and/or (A4-83)nX type block copolymer are combined in a weight ratio of the former to the latter. By using them together in a ratio of 5:95 to 95:5, the tensile strength and elongation at break of the entire block copolymer will fall within the above range, and the tensile strength of the pressure sensitive adhesive composition will be 20 kg/cd. Below, the elongation at break is 500%
The above settings can be easily made.

Special IC1 (A4=B3) nX type block copolymer can be synthesized with A, -B type block copolymer and (A, -B3) at the synthesis stage by setting the reaction rate of the coupling agent.
n Since the weight ratio of the copolymer can be easily set, it is very easy and convenient to keep the tensile strength and elongation at break of the pressure-sensitive adhesive composition within the above ranges.

In addition, the inventors have discovered that in addition to a mixture of such an A1-B1 type block copolymer and an A2-82-A3 type block copolymer and/or (A4-B3)nX type block copolymer, A5-B, -A6 type block copolymer (A, , A6 is a non-elastomeric block,
When at least one of them has a number average molecular weight of 5,000 or less and %B4 is an elastomer block whose constituent monomer is a conjugated diene compound), the tensile strength and elongation at break of the pressure-sensitive adhesive composition are It has been found that setting within the range becomes even easier.

A6 of the above A5-B, -A6 type block copolymer. A
6 has a number average molecular weight of at least one, preferably both, of 3,00 or less, particularly preferably within the range of 300 to 3,000, and B4 has a number average molecular weight of 10,0
00 or more, preferably in the range of 20,000 to 500,000. The number average molecular weight of the entire copolymer is 11,000 or more, preferably 15,000 to 500.
,000, and A5. The total content of A6 is 30% by weight or less, especially 5 to 20% by weight in the copolymer body.
It is desirable that

The amount of such A5-B4-A6 type block copolymer to be used is as follows:
-B, -A3 type block copolymer and/or (A,
-B3) Less than 50% by weight in the total amount with the nX type block copolymer, that is, in the total block copolymer, especially 10 to 4
It is preferable to set it to 0% by weight. If you use too much of this,
This is undesirable since it may become difficult to satisfy the above-mentioned tensile strength and elongation at break, or it may be difficult to maintain the cohesive force of the adhesive composition within an appropriate range even if the tensile strength and elongation at break can be satisfied.

The block copolymers used in this invention are composed of the various block copolymers described above, and these block copolymers are composed of cis-1,4 bonds of the conjugated diene compound constituting the elastomer block. It is necessary that the content is 50% or more of all bonding modes. When this content is less than 50%, a high degree of improvement in rough surface adhesion cannot be obtained. The particularly preferable content is 60% or more.0 Note that when the block copolymer is composed of a mixture of two or more types as mentioned above, it accounts for 1.4% of the total amount of elastomer blocks in all the copolymers. - It is sufficient that the bond content falls within the above range. Of course, it is particularly desirable that each copolymer is composed of elastomer blocks consisting of 1,4-bonds having the above-mentioned content.

The block copolymer according to the present invention constructed in this manner is produced by a known glueing anionic polymerization method using an organolithium-based initiator, and (A, -B3) nX type block copolymers are produced by further polymerization after the above polymerization. It can be obtained by carrying out a known coupling reaction using a required coupling agent.

In the above synthesis method, organolithium-based initiators such as n-butyllithium, nibutyllithium, etc. give good results in the formation of cis-1.4 bonds in the covalent diene compound. That is, when other initiators such as organic sodium-based initiators and organic potassium-based initiators are used, the production rate of cis-1.4 bonds becomes low, which is not so preferred. In addition, as a reaction solvent during polymerization, an inert solvent selected from hydrocarbons such as benzene, cyclohexane, and n-hexane, or a mixture thereof with a small amount of a polar solvent such as tetrahydrofuran is used.
Desirable because it gives good results for bond generation. It is observed that when a polar solvent such as tetrahydrofuran is used alone or in a large amount, the number of cis-1.4 bonds tends to decrease.

In the block copolymer according to the present invention having the above-mentioned properties obtained in this way, a monovinyl compound is used as the hexamer constituting the non-elastomer block in any of the above types. In general, it is preferable to use a monovinyl-substituted aromatic compound such as styrene, 3-methylstyrene, 3,5-diethylstyrene, or 4-phenylstyrene, and a particularly preferred monovinyl-substituted aromatic compound is styrene. Further, examples of the conjugated diene compound constituting the elastomer block include isoprene, 1,3-butadiene, and 2,3-dimethyl-1,3-butadiene, among which isoprene is particularly preferred.

In this invention, a tackifying resin is used as an essential component together with the block copolymer having the above structure. This tackifying resin usually has a softening point of 40 to 150.
A high softening point resin having a softening point of 10° C. or less, preferably 0° C. or less is used, and the latter low softening point resin accounts for at least 3% by weight.
By using it in a proportion such that it becomes, preferably 5 to 40% by weight, the wettability to rough surfaces becomes good and rough surface adhesion is highly improved.

The type of such tackifying resin is not particularly limited, and any conventionally known resin such as rosin resin, terpene resin, terpene modified resin, coumaron-indene resin, petroleum resin, etc. can be used. The amount of the tackifier resin to be used is 20 to 300 parts by weight, preferably 50 to 200 parts by weight, based on 100 parts by weight of the block copolymer, and if it is less than 20 parts by weight, the adhesive will have a good initial adhesive strength. If it is added (< or more than 300 parts by weight), the cohesiveness will be poor, and in either case, a decrease in adhesive properties cannot be avoided.

The pressure-sensitive adhesive composition of the present invention contains the above-mentioned block copolymer and tackifying resin as essential components, and also contains an elastomer other than the above-mentioned block copolymer, that is, a natural Various rubbery polymers such as rubber, butyl rubber, acrylic rubber, styrene-butadiene copolymer rubber, and polyisoprene rubber can be included. The amount used is preferably less than 50% by weight, preferably less than 30% by weight based on the total amount with the block copolymer,
If too much is used, the characteristics of the block copolymer will be impaired, so pN is preferable.

The pressure-sensitive adhesive composition of the present invention further includes process oils, oils such as tung oil, low molecular weight polymers such as polybutadiene, polybutene, and polyisoprene with a number average molecular weight of less than 100,000, and resins or rubbers such as dioctyl phthalate. Softeners such as plasticizers can be blended as mechanical property modifiers, and various other conventionally known antioxidants, ultraviolet absorbers, fillers, pigments, extenders, etc. that are added to pressure-sensitive adhesives can be added. Additives may be added. These amounts may be normal amounts.

As mentioned above, the pressure-sensitive adhesive composition of the present invention constructed in this way has a tensile strength of 20 kg/c at room temperature.
d or less, preferably 3 to 15 KfI/cal.

Breaking elongation is 500% or more, preferably 800 to 2500
%, and by exhibiting such mechanical properties, it exhibits very good adhesive strength to rough surfaces such as corrugated paper and plywood.・This pressure-sensitive adhesive composition can generally be handled as a solvent-free hot-melt coating type, but it may also be a solution type using an appropriate organic solvent such as toluene, and it can also be handled as a solution type using an appropriate organic solvent such as toluene. It can also be a water-based emulsion type. In addition, the production of adhesive articles using this composition can be achieved by, for example, coating the various types of compositions described above onto a known base material such as a polyester film by appropriate means depending on each type, and drying or other methods. All you have to do is go through the necessary steps. The thickness of the adhesive layer when used as an adhesive tape can be selected depending on the purpose of use, but is usually about 5 to 500 mm.
What is necessary is to make it μ.

〔Effect of the invention〕

As described above, in this invention, the tensile strength of the adhesive composition at room temperature, which is determined by the type of block copolymer and the type and amount of the tackifying resin blended therein, is 20 kg/cd or less. , the elongation at break is 500% or more, and the content of cis-1.4 bonds in the conjugated diene compound constituting the elastomer block of the copolymer is 500% or more.
By setting the tackifying resin to 0% or more and using at least 3% by weight of a resin with a softening point of 10°C or less as the tackifying resin, the adhesion to rough surfaces such as corrugated paper and plywood is significantly improved. It is possible to provide a pressure-sensitive adhesive composition useful for adhesive articles such as adhesive packaging tapes, paint masking adhesive tapes, and adhesive labels.

〔Example〕

EXAMPLES Below, examples of the present invention will be described in more detail. In addition, in the following, parts mean parts by weight. Further, the block copolymers A-D used in the following Examples and Comparative Examples were synthesized by Haggi's method.

Block copolymer A〉 Styrene monomer is introduced into an inert solvent of benzene containing dibutyl lithium to perform anionic polymerization, then isoprene monomer is added and anionic polymerization is performed again, and finally a coupling agent is added. By performing a coupling reaction by adding divinylbenzene as a liquid, Sl-I
A polymer solution I containing a block copolymer consisting of 60% by weight of a type block copolymer and 40% by weight of a (Sl-■)2x type block copolymer was obtained. Note that S1 is a polystyrene block, ■ is a polyisoprene block, and X is a residue of divinylbenzene as a coupling agent.

On the other hand, by sequentially introducing styrene monomer, imprene monomer, and styrene monomer into an inert solvent of benzene containing dibutyllithium to perform three-stage anionic polymerization, S, -1-82 type block copolymerization was carried out. A polymer solution (2) containing coalescence was obtained. In addition, the above S, , S2 are polystyrene blocks, and ■ is a polyisoprene block.

After mixing the above polymer solution I and polymer solution ■ so that the solid content (block copolymer) ratio was 8:2 by weight, the solvent was heated and volatilized to form 51-I. A block copolymer A consisting of a mixture of a (51-I)2X type block copolymer, and an S-I-52 type block copolymer was obtained.

<Block copolymer B> As in the case of block copolymer A, it contains a mixture of 70% by weight of the 51-I type block copolymer and 30% by weight of the (Sl-1)2X type block copolymer. A polymer solution (■) and a polymer solution (■) containing an Sl-I-52 type block copolymer were obtained, and the solid content (block copolymer) ratio of the copolymer solution (■) and the copolymer solution (■) was After mixing so that the weight ratio is 6 = 4, by heating and volatilizing the solvent,
Block copolymer B was obtained.

Block copolymer C> Add n-butyllithium to an inert solvent consisting of 70% by weight of benzene and 30% by weight of tetrahydrofuran, add imprene monomer to this for anionic polymerization, and then add a small amount of styrene monomer. was added and anionic polymerization was performed again to obtain a polymer solution V containing the Sl-I type block copolymer.

On the other hand, in the same manner as in the case of polymer solution (1) of block copolymer A, a polymer solution (2) containing an S, -I-52 type block copolymer was obtained. This solution (■) and the above polymer solution (V) were mixed so that the solid content (block copolymer) ratio was 6:4 by weight, and then the solvent was evaporated by heating to obtain block copolymer C. Ta.

Block Copolymer D> A commercially available S□-I-5 type block copolymer (trade name: Kraton 1107, manufactured by Shell Chemical Co., Ltd.) was used as the block copolymer.

The mixing ratio of each block copolymer constituting the above block copolymers A-D, and the Sl and S2 constituting each copolymer.
．． The number average molecular weight of I was as shown in Table 1 below.

Table 1 also shows the tensile strength and elongation at break of the above block copolymers A-D and the cis-1/4 of the elastomer block (I).
The results of examining the bond content were as shown in Table 2 below. The tensile strength and elongation at break were determined by preparing sheet pieces of 0 and 2 m in thickness and 5 widths from each copolymer A'-D, and using these sheet pieces as test pieces in the method described above. . In addition, in block copolymers A-C, the content of cis-1.4 bonds is the content of cis-1.4 bonds in the total amount of elastomer block (I) of each block copolymer constituting these. Expressed as content.

Examples 1 to 3 Block copolymers A and B and natural rubber were mixed with the tackifying resin and anti-aging agent shown in Table 3 in the composition shown in the table, Further, three types of pressure-sensitive adhesive compositions of the present invention were prepared by dissolving and mixing in toluene.

Each of the above compositions was coated on a silicone-treated release paper to a dry thickness of 0.1 m, then peeled off, and the resulting adhesive films were stacked together to a thickness of 0.2 tx. A strip-shaped film with a width of 5 fl was produced and used as an adhesive film for measuring tensile strength and elongation at break.

Separately, each of the above compositions was applied and dried on the surface of kraft paper to a dry thickness of 30 μm, and then cut to a predetermined width to prepare adhesive tapes for adhesive performance tests.

Comparative Examples 1 to 4 Block copolymers A, C, and D were mixed with a tackifying resin and an antiaging agent shown in Table 3 in the composition shown in the same table, and further mixed with toluene. Four comparative pressure-sensitive adhesive compositions were prepared by dissolving and mixing the following:

Furthermore, adhesive films for measuring tensile strength and elongation at break, and adhesive tapes for testing adhesive performance were produced from these compositions in the same manner as in Examples 1 to 3.

Using each of the adhesive films and adhesive tapes of Examples 1 to 3 and Comparative Examples 1 to 4, tensile strength, elongation at break, and adhesion to glass as adhesive properties, 2 corrugated board sealability, and rough surface retention were evaluated. The results of the investigation were as shown in Table 3. Note that the adhesive properties were measured by the following method.

Adhesion to glass〉 Average unevenness depth (depth between the top of the mountain and the bottom of the valley) approx. 6
An adhesive tape was applied to the sandblasted frosted glass surface of P, and after light pressure bonding was performed with a pressure force of 109/at/I, the adhesion area to the glass surface was measured.

The adhesion area was calculated from the light reflectance.

Cardboard sealability> The flaps of a JISA-type cardboard box were lightly pasted together with a 50 tns wide adhesive tape, and after being left at room temperature for one week, the ratio of the area to which the adhesive tape was pasted, that is, the peeling ratio was measured.

Rough surface holding power〉 Apply adhesive tape to the surface of the cardboard so that it has a crimping area of 2511 IIX 25 txM, and after crimping it from the back side of the tape with a 200y roller, hang an IK9 load on the bottom end of the tape and hold the tape at a temperature of 40'C. The time until it slipped off was measured.

As is clear from the results in Table 3 above, the adhesive tape made using the pressure-sensitive adhesive composition of the present invention has good adhesion to glass surfaces and strong rough surface retention ( It is clear that the adhesiveness to rough surfaces is much better than that of conventional products.

Claims (7)

[Claims] (1) Contains a block copolymer consisting of a non-elastomer block and an elastomer block whose constituent monomer is a conjugated diene compound, and 20 to 300 parts by weight of a tackifier resin based on 100 parts by weight of this block copolymer. ,
The tensile strength at room temperature is 20 Kg/cm^2 or less, the elongation at break is 500% or more, and the content of cis-1.4 bonds in the conjugated diene compound constituting the elastomer block is 50% or more, A pressure-sensitive adhesive composition, wherein the tackifying resin contains at least 3% by weight of a resin having a softening point of 10° C. or less. (2) The block copolymers are an A_1-B_1 type block copolymer (A_1 is a non-elastomer block, B_1 is an elastomer block whose constituent monomer is a conjugated diene compound), an A_2-B_2-A_3 type block copolymer, and / or (A_4-B_3)_nX type block copolymer (A_2, A_3, A_4 are non-elastomer blocks with a number average molecular weight of 10,000 or more, B_2,
B_3 is an elastomer block whose constituent monomer is a conjugated diene compound, X is a coupling agent residue, and n is 2 to 6
Claim No. (1) containing a mixture of
) The pressure-sensitive adhesive composition described in item 1. (3) The block copolymer is a mixture of an A_1-B_1 type block copolymer, an A_2-B_2-A_3 type block copolymer and/or a (A_4-B_3)_nX type block copolymer, and an A_5-B_4 type block copolymer. -A_6 type block copolymer (A_5 and A_6 are non-elastomer blocks, at least one of which has a number average molecular weight of 5,000
and B_4 is an elastomer block whose constituent monomer is a conjugated diene compound), and this A_
The pressure-sensitive adhesive composition according to claim (2), wherein the content of the 5-B_4-A_6 type block copolymer is less than 50% by weight in the total block copolymer. (4) Claims Nos. (1) to 1, wherein the constituent monomer of the non-elastomer block is a monovinyl-substituted aromatic compound.
The pressure-sensitive adhesive composition according to any one of (3). (5) The pressure-sensitive adhesive composition according to claim (4), wherein the monovinyl-substituted aromatic compound is styrene. (6) Claim No. 1, wherein the conjugated diene compound that is the constituent monomer of the elastomer block is isoprene.
) to (5). (7) Any one of claims (1) to (6) in which an elastomer (rubber-like polymer) other than the block copolymer is contained in an amount less than 50% by weight based on the total amount of the block copolymer. The pressure sensitive adhesive composition described.