JPS60221475A - Pressure-sensitive adhesive composition - Google Patents

Abstract

PURPOSE:The titled composition, obtained by incorporating a specific copolymer with a tackifier resin in a specific proportion, having apecific mechanical characteristics, moderate adhesive force in such an extent as not to damage the surface of adherends and good holding performance on rough surfaces. CONSTITUTION:A pressure-sensitive adhesive composition, obtained by incorporating 100pts.wt. block copolymer, derived from a block copolymer of the type expressed by the formula (S1-I1)n-S2 [S1 and S2 are block copolymer, derived from styrene (homolog), and having <=7,000 number-averaged molecular weight; the total content of S1 and S2 is <=15wt% based on the total polymer; I1 is block polymer derived from isoprene (homolog); n is an integer 1-5] with 0-100 pts.wt. block copolymer of the type expressed by the formula S3-I2 (S3 has the same meaning as S1 and S2; I2 has the same meaning as I1) and 30-400pts.wt. tackifier resin, e.g. rosin based resin, and having <=5kg/cm<2> tensile strength at ordinary temperature and >=500% elongation at breaking point. USE:Adhesive tapes used for sealing, packaging, masking, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a pressure-sensitive adhesive composition, a method for producing the composition, and an adhesive article comprising a single-sided or double-sided pressure-sensitive adhesive tape/sheet or similar article made using the composition. More specifically, it has adhesive strength that is mainly composed of a block copolymer consisting of styrene and isoprene, and has enough adhesive strength to be able to be peeled off without damaging surfaces such as paper materials, which have relatively low interlayer strength. A pressure-sensitive adhesive composition that exhibits good retention performance even on rough surfaces such as materials due to fine cohesive failure at the adhesive interface of the adhesive layer, and a tape made using the composition. Adhesive articles such as sheets or labels are provided.

Pressure-sensitive adhesive compositions used for products that adhere to the surface of an adherend by light pressure, such as packaging adhesive tapes, masking adhesive tapes for painting, and adhesive labels, include rubber components such as natural rubber. There are two known types: a rubber type whose main component is a rubber type, and a resin type whose main component is a resin component represented by an acrylic resin.

These rubber- or resin-based pressure-sensitive adhesive compositions generally have a polymer constituting the main component dispersed in water or dissolved in an organic solvent. Due to the surfactant added during the production of the composition, there is a problem that the water resistance of the resulting adhesive article is poor, and in the case of a solvent type, it is necessary to volatilize the solvent during the production of the adhesive article. This poses a problem in that it can impair the health of workers and pose a risk of fire, and therefore requires a large solvent recovery device.

Recently, hot-melt or high-concentration pressure-sensitive adhesive compositions that use no or almost no surfactants or organic solvents have been developed as pressure-sensitive adhesive compositions that solve the problems of water-dispersed or solvent-based adhesives. Compositional power (has been developed and is being used.

A styrene-isoprene (or butadiene) yarn block copolymer is generally known as a typical main component of these adhesive compositions, but since butadiene-based ones lack rubber elasticity, isoprene-based ones At present, it has not been widely used because it does not have sufficient adhesion and adhesion properties.

Therefore, an adhesive article such as an adhesive tape made of l/X using an adhesive composition containing such a styrene-isoprene block copolymer as a main component has a high content of the copolymer which is the main component of the composition. Due to its cohesive properties, it is easily peeled off from the surface of the adherend after being pasted.

For example, recently, the number average molecular weight is about 8,000 to 30,000.
styrene block polymer with a number average molecular weight of about 10
0,000 to 200,000 isoprene block polymer, and the styrene content is 15 to 2 of the total polymer.
Adhesive compositions based on 0% by weight of styrene-isoprene-styrene block copolymer have also been proposed.

Adhesive products such as adhesive tapes using this composition have slightly lower adhesion than adhesive products using natural rubber compositions, but they can be used on smooth adherends such as stainless steel plates. It has an extremely high adhesive strength of 1000 l/25wn or more. However, it has poor retention performance for rough materials such as paper.

Incidentally, adhesive articles such as adhesive tapes do not necessarily require high adhesive force or cohesive force; rather, a lower adhesive force may be desirable as long as the desired function can be achieved.

A typical example is when it is used for applications such as sealing, packaging, and masking.When sealing a cardboard box, it is not always possible to paste the adhesive tape in the correct position, and the tape must be peeled off. However, if the adhesive strength of the tape is too high, the surface layer of the cardboard box will be caught by the adhesive layer of the tape and cannot be reattached. Furthermore, when adhesive tapes with high adhesive strength are used to package articles with painted surfaces, such as furniture, there is a problem in that when the tape is removed, the surface paint is also peeled off.

Furthermore, when painting a target surface, it is common practice to cover the untargeted surface with masking adhesive tape, or to fix paper or plastic film as a covering material with abrasive adhesive tape in series. However, when removing the adhesive tape after painting, if the adhesive strength of the tape is higher than necessary, the surface of the adherend to which the tape is attached may be damaged.

Furthermore, if the condensation force is too high, the adhesive layer has a poor ability to absorb and moderate external impact, resulting in problems such as a phenomenon in which the adhesive tape easily peels off and poor adhesion to rough surfaces.

Therefore, as described above, adhesive articles such as adhesive tapes made using pressure-sensitive adhesive compositions containing the styrene-isobrene-styrene block copolymer as a main component have high adhesive strength and high adhesive strength. Because it is cohesive, it does not solve the disadvantages of reduced adhesion to rough surfaces and peeling due to impact.

That is, although the adhesive article made using the styrene-isoprene-styrene block copolymer shows sufficiently satisfactory test results in the test method specified by J. When used on rough surfaces such as paper or polyolefin films or sheets, it has practical drawbacks such as damaging the surface.

Therefore, it is an object of the present invention to have an appropriate adhesive strength that does not damage the surface of the adherend even if it is peeled off from the surface of the adherend when used for purposes such as sealing, packaging, and masking. An object of the present invention is to provide a pressure-sensitive adhesive composition that has sufficient practical holding performance even on rough surfaces such as corrugated paper and plywood, and adhesive articles such as adhesive tapes using the composition.

Other objects of the invention will be understood from the following description.

The object of the present invention is to obtain a compound of the general formula (S, -111)n -
S2 type block copolymer (wherein S and S2 are block polymers derived from styrene or styrene analogs and have a number average molecular weight of 7,000 or less, and ■ is a block derived from isoprene or isoprene analogs) It is a polymer, and the total content of S and S2 is 15% by weight or less of the total polymer. n is an integer of 1 to 5) For 100 parts by weight, the general formula 83'2m of θ ~ 100
floc co-arashi coalescence (S is a block polymer derived from styrene or a styrene analog and has a number average molecular weight of 7000 or less, and I2 is a block polymer derived from isoprene or an isoprene analog);
This is achieved by blending 30 to 400 parts by weight of an adhesion-imparting resin, and having a tensile strength at room temperature of 5 to 91 crl or less and an elongation at break of 500% or more.

According to the pressure-sensitive adhesive composition of the present invention and adhesive articles such as adhesive tapes made using the composition, the tensile strength at room temperature is set to 5#/c+7 or less and the elongation at break is set to 500% or more. As a result, it has the characteristics of moderate adhesion and good retention performance on rough surfaces. What is distinctly different from pressure adhesive compositions and adhesive articles such as adhesive tapes made using the compositions is that in conventional adhesive articles, the peeling between the adherend and the adhesive layer of the adhesive article is not an adhesive process. In contrast to peeling at the interface, peeling between the adhesive layer and the adherend of an adhesive article made using the pressure-sensitive adhesive composition of the present invention is due to fine cohesive failure at the adhesive interface of the adhesive layer. Due to this phenomenon, the shear resistance against external impact was significantly increased, and the impact resistance and adhesion retention performance on rough surfaces were dramatically improved.

General formula (S□-11) used in carrying out the present invention
The block copolymer particles represented by n-82 are S□ and S
2 is a styrenic block polymer derived from styrene or a styrene analog and has a number average molecular weight of 7000 or less, ■□ is an isoprene block polymer derived from isoprene or an isoprene analog, and S□
The total content of S2 and S2 must be 15% by weight or less of the total polymer.

The number average molecular weight of the copolymer is 50,000 to 10,000.
00 is preferably used.

As the styrene-based block polymer, homologs obtained by adding functional groups such as methyl groups and nitrile groups to styrene by conventional methods can also be used, but when the number average molecular weight exceeds 7000, the adhesive properties aimed at in the present invention are not obtained. It is undesirable because it cannot be
A value of 0 is desirable. Further, the total content of the styrenic block polymer is preferably 2 to 15% by weight,
If the amount exceeds 15% by weight, the cohesive force of the pressure-sensitive adhesive composition becomes too high, which may cause the problems described above, which is not preferable.

Further, as the isoprene block polymer, one having a number average molecular weight of 45,000 or more and containing 85% by weight or more is used.

The structure of the copolymer may be radial (n in the general formula is 2 to 5) or linear (n = 1), but a linear structure with fewer branches is preferable. This is preferable in terms of adhesive properties.

In addition, the general formula S3-In type block copolymer used as necessary in carrying out the present invention is a block copolymer in which S3 is derived from styrene or a styrene analog, and the number average molecular weight is 7000 or less. The copolymer is composed of a block polymer derived from ali, (2) kaisoprene, or an isoprene analog, and the range covered by each block polymer is approximately the same as that of copolymer (4). The number average molecular weight of copolymer CB) is 50,000 to 10
00000 is practically preferable.

These copolymers (2) and (2) can be obtained by living or anionic polymerization using a lithium-based initiator.

That is, a mobile lithium compound such as n-butyl lithium or 5ec-butyl lithium is added to an inert solvent selected from hydrocarbons such as benzene, cyclohexane, and n-hexane, and then styrene and vinyltoluene are added. , vinyl xylene, α-methylstyrene, and homologue monomers such as isoprene and methyl isoprene are sequentially added to form each block under a temperature condition of usually 50 to 70°C. This is obtained by

Copolymer (4) can also be obtained by coupling copolymer CB) with a coupling agent such as tin tetrachloride, polyepoxide, divinylbenzene, divinyltoluene.

These copolymers (2) and CB) can also be obtained by the methods described in U.S. Pat. It will be done.

The adhesion-imparting resin is one that imparts appropriate adhesive strength to the pressure-sensitive adhesive composition, and includes, for example, rosin-based resin, terpene-based resin, terpene-modified resin, coumaron-indene-based resin, petroleum-based resin, and styrene. One or more types of resins are used.

The pressure-sensitive adhesive composition of the present invention contains the above-mentioned copolymer (8) and adhesion-imparting resin as essential components, and optionally contains the above-mentioned copolymer CB) at normal temperature (general VC of 20°C). By adjusting the tensile strength at K of 5 to 9/crl or less, preferably 0.3 to 3 kq/crl, and the elongation at break to 5001 or more, preferably in the range of 800 to 2000%. , an adhesive force of about 150 to 5009/10B and a holding force of about 50 to 150 minutes (40''C) are obtained.

In order to obtain even more optical adhesion, the storage modulus (based on dynamic measurement of linear viscoelasticity) at 20"C and IHz should be 3 x 106d)'ne/cTI or less, preferably 3 x -105~ It is preferable to adjust it to a range of 2×10 6 dyne/crI.

When the tensile strength exceeds 51Q/ctl, the adhesive force becomes too high and peeling occurs at the adhesive interface with the adherend, resulting in poor shear resistance against external impact and peeling due to impact. Easy/fh 1/7
)+7'5Z'&l/fP 1. % if
/l'% ``y's 'k, s, shi~IJk If the degree of bhikkhu is less than 500%, the adhesive force will be too low and the impact resistance and creep resistance will also be poor, which is not preferable. Also, the storage modulus is 3 x 106dVne
If it exceeds /c1, the adhesion to rough surfaces decreases, which is undesirable.

The pressure-sensitive adhesive composition having the above-mentioned physical properties contains 30 to 40 parts by weight of the adhesion-imparting resin based on 100 parts by weight of the copolymer.
0 parts by weight, preferably in the range of 50 to 300 parts by weight. If the resin is less than 30 parts by weight, the adhesive strength will be poor, and if it exceeds 400 parts by weight, the adhesive strength will be too high and the retention performance on rough surfaces will deteriorate, which is not preferred.

The use of ) of said copolymers is not essential. However, when attempting to obtain a pressure-sensitive adhesive composition with the above-mentioned physical properties by combining the copolymer (5) and an adhesion-imparting resin, the range of the types and number of parts of the resin that can be used is narrowed, Although there is a practical problem in that it requires more labor and expense than necessary, the combined use of copolymers (2) and (2) is an attempt to eliminate the problem of A and A.

Therefore, the blending amount of copolymer (B) is as follows: copolymer (8)
The amount should not exceed 100 parts by weight at most, and is preferably used in the range of 8 to 80 parts by weight.

Known compounding agents such as fillers, pigments, softeners, plasticizers, and anti-aging agents may be added to the pressure-sensitive adhesive composition of the present invention as long as the above-mentioned physical properties are satisfied. Preferred compounds other than those mentioned above include rubbers such as stranded natural rubber, styrene-butadiene rubber, polyisobutylene rubber, polybutadiene rubber, butadiene-nitrile rubber, or polymers such as acrylic polymers. . The addition of these rubbers or polymers serves to improve other desired properties of the pressure sensitive adhesive composition, such as cold resistance.

Therefore, the amount of these rubbers or polymers added should not exceed 50 parts by weight per 100 parts by weight of the copolymer (1), and if it exceeds 50 parts by weight, the pressure sensitive adhesive composition However, the melt viscosity of the composition increases significantly and the workability of coating the tape support film or sheet material decreases, which is undesirable.

The pressure-sensitive adhesive composition of the present invention is usually charged into the hopper of an extruder, heated at 150-200'C, and heated at 100'C.
It is melted to 0 to 4000 voids and coated on the surface (one or both sides) of a tape support such as a plastic film or sheet, paper, woven fabric, non-woven fabric, foil, etc., with a thickness of 5 to 300 μm, and used as adhesive tape, etc. This is what adhesive articles are made from.

As described above, the pressure-sensitive adhesive composition of the present invention has styrene-
A blend consisting of an isoprene-styrene block copolymer and an adhesion-imparting resin has a tensile strength of 5 kq at room temperature.
/cJ or less and the elongation at break is set to 500% or more, and more preferably the storage modulus is 3X 10'dyne /c
- Since the vc was adjusted below, it has the characteristics of having an appropriate adhesion force that does not damage the surface of the adherend and good holding performance against rough surfaces.

Examples of the present invention will be shown below, and the tensile strength and elongation at break were measured by the following methods.

<Tensile strength and elongation at break> A short shelf-shaped sample piece (pressure-sensitive adhesive composition sheet piece) with a thickness of 0.21+Lm and a width of 5 mm was fixed at both lengthwise ends with a chuck interval of IQ mm, Tensile speed 5 Cram)In
In (conditions 20 to 26C), the tensile strength and elongation of the sample piece at break are measured.

In the following examples, parts by weight are meant by parts by weight.

Example 1 49% of sec-butyl lithium was added to cyclohexane 7e as an inert solvent, the temperature was raised to 60° (Ic), and then 279 vc of styrene and 600q of isoprene monomer were added in the order of styrene-isoprene-styrene. Living polymerization is carried out by adding phenolic antioxidant 1 to this.
Add 5g of methyl alcohol containing 0g to about 4000
a styrene block polymer having a number average molecular weight of
A linear styrene-isoprene-styrene block copolymer solution consisting of an isoprene block polymer having a number average molecular weight of about 90,000 was obtained.

The content of the styrene block polymer in the copolymer is about 8% by weight, but the copolymer includes a styrene block polymer having a number average molecular weight of about 4000, and the total number average molecular weight is about 8% by weight. It contained about 10% by weight of 50,000 styrene-isoprene block copolymer.

Next, the copolymer solution is dried to obtain a solid content, and to 100 parts of this solid content, 100 parts of petroleum resin and 5 parts of process oil are added.
1 part of anti-aging agent and 1 part of anti-aging agent and kneaded in a pressure kneader for 16 minutes.
A pressure sensitive adhesive composition was obtained by kneading at 0'C for 20 minutes.

To evaluate this composition, it was dissolved in toluene and coated on a release paper coated with a silicone release agent so that the thickness after drying was 100 μm and dried to obtain a pressure-sensitive adhesive film. .

When two sheets of this film were stacked together and the tensile strength and elongation at break were measured, values of 1.8 to 9/crl and 1600% were obtained.

In addition, 5 sheets of the above film were stacked and the frequency was 1Hz at 20"C.
When the storage elastic modulus was measured, it was found to be 5.2X10'
A value of dyne/c- was obtained.

Next, the above-mentioned composition dissolved in toluene was applied and dried on one side of kraft paper so that the thickness after drying was 30 μm to prepare an adhesive tape.

When the adhesive strength of this tape was measured according to JIS Z 1522, it was 3509/1011, and when the holding force was measured according to the same method (condition α 140°C), it was 150.
It was a minute. When measuring the holding force, the peeling state of the tape from the adherend was observed, and it was found that this was due to fine cohesive failure at the adhesive interface of the adhesive layer.

Furthermore, when the tape was attached to corrugated paper and slowly peeled off after a predetermined period of time, there was only slight surface damage to the corrugated paper.

Reference Example 1 As a styrene-isoprene-styrene block copolymer, the number average molecular weight of the styrene lock polymer is about 11
Everything is the same as in Example 1 except that 000 is used.

The measured values and results were as follows.

Tensile strength: 18.3 parts g/crI Elongation at break: 1600% Storage modulus at 20"C and IHzK: 9.I
10'd3'n J Adhesive Crab 840S/10 Intoxication Holding Crab for 1000 minutes or more Peeling condition: Peeling at adhesive interface Peeling from corrugated paper: Completely destroy the surface of corrugated paper Example 2 Same operation as Example 1 , a linear styrene-isoprene-styrene having a styrene block polymer having a number average molecular weight of about 2,500 and an isoprene block polymer having a number average molecular weight of about 100,000, the content of the styrene block polymer being 5% by weight. A block copolymer solution was obtained.

A pressure-sensitive adhesive composition was obtained consisting of 100 parts of solid content of the copolymer, 80 parts of petroleum resin, 25 parts of low softening point resin (softening point: 5°C), and 1 part of anti-aging agent.

For comparison, 50 parts of a styrene-isoprene-styrene block copolymer consisting of a styrene block polymer having a number average molecular weight of about 8,500 and an isoprene block polymer having a number average molecular weight of about 120,000; The above two types of resins and an anti-aging agent are added to 50 parts of a styrene-isoprene-styrene block copolymer consisting of a styrene block polymer having a molecular weight and an in-prene block polymer having a number average molecular weight of about 5000 to 120,000. A pressure-sensitive adhesive composition was obtained by blending the same nail.

The measurement results are as follows.

1. Indication of the case Patent Application No. 52651 of 1988 2. Name of the invention Pressure-sensitive adhesive composition 3. Person making the amendment Relationship with the case Patent applicant 4. Daily ( Voluntary) 5. Amend the "Claims" and "Details of the Invention" of the specification to be amended 1) Amend the "Claims" of the specification as attached 0 2) Line 7 of page 3 of the specification 0 3) Correct ``1 adhesive article'' on line 18 of the same page to ``adhesive article'' 0 4) Correct ``number average molecular weight'' on page 4, line 20 of the same page. " is corrected to "number average molecular weight per block."

5) Correct "collection power" on page 6, line 16 of the same page to "1 cohesive force."

j) [S+
and correct S2J to "styrene"07) Correct [Ss -InJ to rSa SJ on page 19, line 7.

8) Correct "49" in the 12th line of page 17 to ro, 4gJ.

9) Page 19, line 7 of the same document, “JIS Z
Corrected to 1524J.

Change “(condition at 40°C)” to “(condition a
t 40 included Adherent is cardboard paper, pasting area is 25
+u x 10 ”1111) Correct “styrene block polymer” in line 17 of the same to “1 block of styrene block polymer” 12) Correct “approximately 8500 J to [1
Corrected to approximately 18,500J per block.

13) Correct [approximately 8,500 J in the third line of page 21 to [approximately 8,500 J per block. Copolymer (wherein S+ and S2 are block polymers derived from styrene or styrene analogs and have a number average molecular weight of 7000 or less, It is a block polymer derived from isoprene or imprene analogs, and styrene The total content of O is less than or equal to 15M of the total polymer.
n is an integer of 1 to 5) 0 to 100 parts by weight
Parts by weight of the general formula 5s-Is type block copolymer (Ss is a block polymer derived from styrene or a styrene analog and has a number average molecular weight of 7000 or less,
is a block polymer derived from isoprene or isoprene analogs. ) and 30 to 400 parts by weight of an adhesion-imparting resin, the pressure-sensitive adhesive composition is characterized in that it has a tensile strength at room temperature of 5ψ or less and an elongation at break of 500% or more.

2) The blending amount of the general formula 8B-12 type block copolymer is 8
80 parts by weight of the pressure sensitive adhesive composition of claim 1.

3) Rubber or polymer other than the general formula S8-I2 type block copolymer is blended in an amount not exceeding 50 parts by weight with respect to 100 parts by weight of the general formula (S+, r+) n-82 type block copolymer. A pressure-sensitive adhesive composition according to claim 1, comprising:

4) Procedure amendment for the pressure-sensitive adhesive composition O according to claim 1, which has a storage modulus (based on dynamic measurement of linear viscoelasticity) at 20° C. and IHz of 3 X 10 dyne/a+' or less Document: July 10, 1982 1. Indication of the case: Patent Application No. 52651 of 1988 2. Name of the invention: Pressure-sensitive adhesive composition 3. Relationship with the person making the amendment: Date and time of the patent applicant: 4. Voluntary 5. Subject of amendment Procedural amendment submitted on April 23, 1980 l) The "Scope of Claims" will be amended as shown in the attached sheet.

2) In the specification, page 13, line 12, page 14, line 3, page 16, line 16, page 19, line 1, page 20, line 3, and page 21, in the table. Correct the "storage modulus" of "shear storage modulus".

Attachment [2, Claims 1] General formula (S+ -L) n -Ss type block copolymer (wherein, Sl and S2 are block polymers derived from styrene or styrene homologues, and number average The molecular weight is 7,000 or less, and (2) is a block polymer derived from isoprene or an isoprene analog, and the total content of styrene is 15% by weight or less of the total polymer. n is an integer of 1 to 5) 0 to 1 per 100 parts by weight
00 parts by weight of general formula Ss 12 type block copolymer (S
l is a block polymer derived from styrene or a styrene homologue and has a number average molecular weight of 7000 or less;
Is is a block polymer derived from isoprene or isoprene analogs. ) and 30 to 400 parts by weight of adhesion-imparting resin, and the tensile strength at room temperature is 5.
A pressure-sensitive adhesive composition characterized in that it has an elongation at break of not more than kf/- and an elongation at break of not less than 500%.

2) The blending amount of the general formula Ss Iz type block copolymer is 8
80 parts by weight of the pressure sensitive adhesive composition of claim 1.

3) General formula (S+L)n Sl type block copolymer 1
2. The pressure-sensitive adhesive composition according to claim 1, which contains rubber or polymer other than the general formula Ss I2 type block copolymer in an amount not exceeding 50 parts by weight based on 00 parts by weight.

4) The shear storage modulus (by dynamic measurement of linear viscoelasticity) at 20°C and IHz is 3 x 1 (1'dyne/
The pressure-sensitive adhesive composition according to claim 1, which has a molecular weight of 6/I or less. ”

Claims (1)

[Scope of Claims] 1) A block copolymer of the general formula (Sl-I,)n-82 type (wherein S and S2 are block polymers derived from styrene or styrene analogs, and whose number average molecular weight is 7000 or less, and (■) is a block polymer derived from isoprene or an isoprene analogue, and the total content of 80 and S2 is 15% by weight or less of the total polymer. n is an integer from 1 to 5) 100% by weight 0-1 for internal part
00 parts by weight of general formula S3 I2 type block copolymer (S
3 is a block polymer derived from styrene or a styrene analog and has a number average molecular weight of 7000 or less,
I2 is a block polymer derived from isoprene or isoprene analogs. ) and 30 to 400 parts by weight of an adhesion-imparting resin, a pressure-sensitive adhesive composition characterized in that the tensile strength at room temperature is 5.eta. or less and the elongation at break is 500% or more. . 2) The blending amount of the general formula S3-E type 2 block copolymer is 8
80 parts by weight of the pressure sensitive adhesive composition of claim 1. 3) Rubber or polymer other than the general formula S3-I2 type block copolymer is blended in an amount not exceeding 50 parts by weight with respect to 100 parts by weight of the general formula (S knee 11) n-S2 type block copolymer. A pressure-sensitive adhesive composition according to claim 1, comprising: 4) At 20°C: 1) The storage modulus at 1z (by dynamic measurement of linear viscoelasticity) is 3 X 10' ayne/c
2. The pressure-sensitive adhesive composition according to claim 1, wherein the pressure-sensitive adhesive composition is not more than nl.