JPS60223880A - Pressure-sensitive adhesive composition - Google Patents

Abstract

PURPOSE:To provide a pressure-sensitive adhesive compsn. which has a low tensile strength and a high degree of elongation at break and is suitable for use in masking, by blending a tackifying resin with a styrene/isoprene block copolymer having a specified composition. CONSTITUTION:100pts.wt. block copolymer of the formula of (S1-I1)n-S2 is mixed with 0-100pts.wt. block copolymer of the formula of S3-I2. In the formulas, S1, S2 and S3 are each a block polymer derived from styrene (homolog), S1 has a number-average MW of 10,000 or above, S2 has a number-average MW of 8,000 or above, I1 and I2 are each a block polymer derived from isoprene (homolog) and n is 1-5. 30-400pts.wt. tackifying resin such as rosin resin is blended with said block copolymer mixture to obtain the desired pressure-sensitive adhesive compsn. having a tensile strength of 10kg/cm<2> and a degree of elongation at break at 500% or above at room temp.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a pressure-sensitive adhesive composition, a method for producing the composition, and a pressure-sensitive adhesive composition comprising a single-sided or double-sided pressure-sensitive adhesive tape, sheet, or similar article using the composition. Damages surfaces with relatively weak surface interlayer strength, such as paper materials, whose main component is a block copolymer consisting of styrene and isoprene. A pressure-sensitive adhesive that exhibits adhesive strength that allows it to be peeled off without causing any damage, and exhibits good retention performance even on rough adherend surfaces such as paper due to minute cohesive failures at the adhesive interface of the adhesive layer. The present invention provides an adhesive composition and an adhesive article such as a tape, sheet, or label using the composition.

Pressure-sensitive adhesive compositions used for products that adhere to the surface of adherends by light pressure, such as adhesive tapes for packaging, adhesive tapes for paint masking, and adhesive labels, contain rubber components such as natural rubber. There are known rubber-based types that have a main component as a main component, and resin-based types that have a resin component as a main component such as 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 product is poor, and in the case of solvent-based products, it is necessary to volatilize the solvent during the production of the adhesive product. However, there is a problem in that it may impair the health of workers or pose a risk of fire, and therefore requires a large solvent recovery device.

Recently - Kagaro is a pressure-sensitive adhesive composition that solves the problems of the water-dispersed or demolition type, and is a hot-melt type or high-concentration type that uses no or almost no surfactants or organic solvents. Pressure sensitive adhesive compositions have been developed and are being used.

Styrene-isoprene (or butadiene)-based block copolymers are generally known as typical main components of these adhesive compositions, but since butadiene-based ones lack rubber elasticity, isoprene-based block copolymers are generally known. At present, it has not been widely used because it does not have sufficient adhesive properties.

Therefore, adhesive articles such as adhesive tapes made using adhesive compositions containing such a styrene-isoprene block copolymer as a main component are difficult to obtain due to the high cohesiveness of the copolymer that is the main component of the composition. Therefore, it is easy to peel off from the surface of the adherend after pasting. For example, recently, the number average molecular weight per block is about 10.
A styrene-isoprene-based polymer consisting of a styrene block polymer having a molecular weight of 000 to aooooo and an inprene block polymer having a number average molecular weight of approximately 100,000 to 200,000, with a styrene content of 10 to 20% by weight of the total polymer.
Adhesive compositions containing styrene block copolymers as a main component 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 is 10009725 mM
It has extremely high adhesion strength. However, it has poor retention performance for rough surfaces such as paper materials.

By the way, adhesive products such as adhesive tapes do not necessarily require high adhesion or cohesive strength; a typical example is when they are used for sealing, packaging, masking, etc. When sealing corrugated pole boxes, it is not always possible to paste the adhesive tape in the correct position, and it is common practice to peel off the tape and reapply it, but the adhesive strength of the tape If it is too flat, the surface layer of the cardboard box may be destroyed when ladle is applied, and the adhesive layer of the tape may take hold of the tape, making it impossible to reapply it. If adhesive tape with high adhesive strength is used, there is a problem that when the tape is removed, the surface coating will also come off. Furthermore, when painting the intended surface, use masking adhesive tape to cover the unintended surface. It is common practice to cover the area or to cover it by fixing paper or plastic film as a masking material with the adhesive tape, but when removing the adhesive tape after painting, the tape may be damaged more than necessary. It happens sometimes.

On the other hand, if the cohesive force is too high, the adhesive layer has a poor ability to absorb and moderate external impact, resulting in problems such as the adhesive tape being easy to peel off and poor adhesion to rough surfaces.

Therefore, as described above, adhesive articles such as adhesive tapes made of pressure-sensitive adhesive compositions containing the nutyrene-isoprene-styrene Bronoch copolymer as a main component have high adhesive strength and may have high adhesive strength. Due to its high cohesiveness, it does not solve the disadvantages of poor adhesion to rough surfaces and peeling due to impact.

In other words, the adhesive article made using a styrene-isoprene-styrene block copolymer shows sufficiently satisfactory test results in the test methods specified by JIS, etc., but in reality, corrugated paper When applied to rough surfaces, such as polyolefin films or sheets, it has practical drawbacks such as damage to the surface.

Furthermore, when a deep-shaped adhesive article made using a previously known styrene-isoprene-styrene block copolymer is cut using a cutting tool such as a tape cutter or scissors, adhesive residue may be left on the cutting edge of the tape cutter or scissors. Not only does it not cut smoothly, but it also causes diagonal cuts.

Therefore, the first object of the present invention is to provide suitable adhesion that is not damaged to 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. A pressure-sensitive adhesive composition that has a high strength and has sufficient practical holding performance even on rough surfaces such as corrugated paper and plywood, and adhesive tapes and the like using the composition. The purpose is to provide sexual goods.

A second object of the present invention is to provide an adhesive article that does not leave adhesive residue on the cutting edge of a cutting tool, and other objects will be understood from the following description.

The object of the present invention is to obtain the general formula (S+ -L)n S
Type 2 block copolymer (wherein S+ and SR are block polymers derived from styrene or styrene analogs, and the SIO number average molecular weight is 10,000 or more, the number average molecular weight of SR is 8,000 or less, and L is isoprene) or a block polymer derived from an isoprene homologue.N is an integer of 1 to 5) 0 to 1 part by weight per 100 parts by weight
00 parts by weight of general formula Ss It type block copolymer (S
s is a block polymer derived from styrene or a styrene analog, and I2 is a block polymer derived from isoprene or an imprene analog. ) and 3
0-400! This is achieved by being formulated to include an adhesion-imparting resin.

The pressure-sensitive adhesive composition of the present invention and adhesive articles such as adhesive tapes made using the composition have the characteristics of exhibiting appropriate adhesive strength and good retention performance on rough surfaces. In particular, the tensile strength at room temperature is 5.
97 OR" or less and the elongation at break is set to 500% or more, the pressure-sensitive adhesive composition containing a conventional styrene-in-prene-styrene block copolymer as a main component and the pressure-sensitive adhesive composition made using the composition. What is distinctly different from adhesive products such as adhesive tapes is that in conventional adhesive products, the separation between the adherend and the adhesive layer of the adhesive product occurs at the adhesive interface. Peeling between the adhesive layer and the adherend of the adhesive article formed using the pressure-sensitive adhesive composition of the present invention is due to minute cohesive failure at the adhesive interface of the adhesive layer, and As a result of 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 (Sl-I,) used in carrying out the present invention
In the block copolymer CA+ represented by n-82, Sl and SR are styrenic block polymers derived from styrene/styrene homologs, and the S10 number average molecular weight is 10,000 or more, and the SR number average molecular weight is 8,000 or less. % Il must be an isoprene-based block polymer derived from isoprene or an isoprene analog. The number average molecular weight of the copolymer is 5000.
0 to 1oooooo is preferably used.

As the styrene-based block polymer, a homologue obtained by adding a functional group such as a methyl group or a nitrile group to styrene by a conventional method can also be used. The number average molecular weight of Sl is 100
If the number average molecular weight of S2 exceeds 8,000, the adhesive properties targeted by the present invention cannot be obtained, which is not preferable. Practically, Sl is 10,000 to 100
000 and S2 is preferably 1000 to 7500. The content of the styrene block polymer in the copolymer is preferably 2 to 45% by weight for the S1 component and 0.1 to 5% by weight for the S2 component. This is not preferable because it may become too high and cause the problems described above.

In addition, the isoprene block polymer has a number average molecular weight of 45,000 or more, preferably 100,000 to 50
In the range of 0,000, those containing 50% by weight or more in the copolymer are used.

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

Further, in the general formula S-12 type block copolymer (B) used as necessary in carrying out the present invention, S8 is a block polymer derived from styrene or a styrene homolog, and (2) is isoprene. Or, it consists of a block polymer derived from an imprene homolog, and the range of homologs etc. included in each block polymer is approximately the same as that of the copolymerization group. In addition, it is practically preferable that the copolymer (BIO) has a number average molecular weight of 50,000 to 1,000,000.

These copolymerization compounds and CB+ can be obtained by living or anionic polymerization using a lithium-based initiator.

That is, an organolithium compound such as n-butyl lithium or 5ec-butyl lithium is added to an inert solvent selected from hydrocarbons such as hydrogen, benzene, cyclohexane, and n-hexane, and then styrene and vinyltoluene are added. By sequentially adding aromatic vinyl monomers such as , vinylxylene, and α-methylstyrene and homologue monomers such as imprene and methylimprene, each block is formed under a temperature condition of usually 50 to 70°C. That's what you get.

Copolymers (Al) can also be obtained by coupling copolymers (Bl) with a camping agent such as tin tetrachloride, polyepoxide, divinylbenzene, divinyltoluene.

Moreover, these copolymers (A) and (13) are
:r, Permit Specification No. 3787531, No. 328138
No. 3, Special Publication No. 36-19286, No. 40-249
It can also be obtained by the method described in Publication No. 14 and the like.

The adhesion-imparting resin imparts suitable 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, One or more types of styrene resins are used.

The pressure-sensitive adhesive composition of the present invention contains the above-mentioned copolymer (5) and the adhesion-imparting resin as essential components, and if necessary, the above-mentioned copolymer (Bl) is blended to form a normal flow (generally 20% 0
．． 1 to 7 #/am', by adjusting the elongation at break to be 500% or more, preferably in the range of 800 to 2500%, to about 150 to 10009718 jlj
1 of adhesive strength and a holding strength of about 5 to 50 minutes (at 40°C).

Also, to obtain even more adhesion, heat at 20°C.
The storage modulus (by dynamic measurement of linear viscoelasticity) at I Hz is below 3 X 10 dyne/n', preferably between 5 X 10 dyne//cN' and 2X10
It is preferable to adjust it so that it falls within the range of dyne/cyJ'.

If the tensile strength exceeds 10 kg/α', the adhesive force becomes too cylindrical and peeling occurs at the adhesive interface with the adherend, resulting in poor shear resistance against external impact and impact resistance. If the elongation at break is less than 500%, the adhesive force will be too low and the impact resistance and creep resistance will also be poor, which is undesirable. In addition, when the storage modulus exceeds 3 x 10'dyne/z', the adhesiveness to animal surfaces decreases.A pressure-sensitive adhesive composition having the above-mentioned physical properties has an adhesive property with respect to 100 parts by weight between the copolymers. It is obtained by blending a sex-imparting resin in an amount of 30 to 400 parts by weight, preferably 50 to 300 parts by weight. The resin is 3
If it is less than 0 parts by weight, the adhesive strength is insufficient, and if it exceeds 400 parts by weight, the adhesive strength is too high and the holding performance on rough surfaces is deteriorated, which is not preferable.

The use of the copolymer (B) is not essential. However, when an attempt is made to obtain a pressure-sensitive adhesive composition having the various physical properties by combining the copolymer (3) and an adhesion-imparting resin, the range of the types and number of parts of the resin that can be used is narrowed, and the range of the amount of resin that can be used is narrowed. Although there is a practical problem of requiring the above-mentioned labor and cost, the combination of copolymer (Bl) is effective in solving this problem and also contributes to improving the retention performance on rough surfaces. .

Therefore, the blending amount of copolymer (Bl) is as follows: copolymer (5)
The amount should not exceed at most 100 parts by weight per 100 parts by weight, and is preferably used in the range of 8 to 90 parts by weight.

The pressure-sensitive adhesive composition of the present invention may contain known compounding agents such as fillers, pigments, softeners, plasticizers, and anti-aging agents, 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 based on 100 parts by weight of the copolymer, and if it exceeds 50 parts by weight, the pressure sensitive adhesive composition The above-mentioned physical properties of the present invention are undesirable because the above-mentioned physical properties are not obtained, and the melt viscosity of the composition increases significantly, reducing the workability of coating the tape support film or sheet-like material. The pressure-sensitive adhesive composition is usually charged into the hopper of an extruder and heated at 150 to 200°C, and heated to 1000 to 200°C.
It is melted to 4,000 pores 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. to a thickness of 5 to 300 μIn, and has the adhesive properties of adhesive tape, etc. As described above, the pressure-sensitive adhesive composition of the present invention is one in which an article is made by applying a blend consisting of a specific styrene-isoglene-styrene block copolymer and an adhesion-imparting resin to a tensile strength at room temperature. 1
0 ky/am' or less and the elongation at break is set to 500% or more, and more preferably the storage modulus is 3 x 10' d
Since it is adjusted to yne/♂ or less, it has an appropriate adhesion force that does not damage the surface of the adherend, has good retention performance on rough surfaces, and has the characteristics that it does not leave adhesive residue on the cutting edge of the cutting tool. Examples of the present invention are shown below, and the tensile strength and elongation at break were measured by the following method.
Tensile strength and elongation at break> A strip-shaped sample piece with a thickness of 0.2 saw and a width of 5 n+ (pressure sensitive adhesive 21 + Or4F & , / L IJ-'1
4 & ,--,,force 1tN IM 1 ('+ +
+m 1 JL Fix both ends in the horizontal direction, tensile strength 51)
Measured by pulling at I scraps/min (conditions 20-25°C), and calculating the tensile strength and elongation at break of the sample piece. Example I A S, -I, -8 type block copolymer was heated to 60°C by adding 0.29% of sec-butyl lithium to 41% of cyclohexane as an inert solvent. , then styrene monomer (72g): isoprene monomer (4109):
Styrene monomer (5 g) was added in this order to carry out living polymerization, and 59% of methyl alcohol containing 109% of a phenolic antioxidant was added thereto to give an Sl of about 29,200,
S! has a number average molecular weight of 2000
sinam Kanso Hibata theory@@-1 block polymer and in-prene block polymer having a number average molecular weight of about 150,800 and fx, 7: r line autumn styrene-
An isoprene-styrene block copolymer was obtained. The copolymer has an SI content of about 16% by weight and a %S content of about 1% by weight.

To 100 parts of this solid content, 100 parts of petroleum resin, 20 parts of petroleum resin with a softening point of 5°C, and 1 part of anti-aging agent were added, and the mixture was kneaded in a pressure kneader at 160°C for 20 minutes. A pressure sensitive adhesive composition was obtained.

In order 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 μn1, and dried to obtain a pressure-sensitive adhesive film. Ta.

Two of these films were stacked to measure the tensile strength and elongation at break, and five films were stacked to measure the storage modulus at 20° C. and IHz.

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 adhesive tapes with widths in order of 25.

The following test was conducted using this adhesive tape.

Retention force test: Attach one end of a 100-shoulder* tape to the end of a two-stage pole paper strip, and the area is 25M x 10! Paste it so that it becomes IP, apply a load of l kq to the other end of the tape,
The time required for the tape to slip off the cardboard piece was measured in an atmosphere of 40°C.

Surface destruction test: A tape is pasted on the surface of two corrugated cardboard sheets, and after a predetermined period of time, it is slowly peeled off. 1 point is given when the surface of the corrugated paperboard is completely destroyed, 2 points are given when the surface of the corrugated paper is partially destroyed, and almost no destruction is observed. Naka- and Tatoki were evaluated as 3 points.

Drop impact test Two-person cardboard box (width 27α length 641
17 kg of goods are filled in the depth 27α), the flaps are pressed together and sealed with tape, and the product is dropped from the height IFF+ (
At 5°C), observe the peeling of the tape due to impact, and score 1 point if it has completely peeled off in some areas, 2 points if it is starting to peel off, and 3 points if it has not peeled off. did.

Sieve temperature retention performance test, 10 of the above sealed cardboard boxes were
The tape was stored at 0°C for 96 hours, and the tape was observed to see if it peeled off. Those that did not peel off were counted.

Cutting test: The tape was cut with commercially available scissors, and the number of times until adhesive residue appeared on the cutting edge and it became difficult to cut was counted.

Example 2 S8-I2 type block copolymer was mixed with 41 parts of cyclohexane as an inert solvent and 0.0 parts of sec-butyl lithium.
Add 4g and raise the temperature to 60℃, then add styrene monomer (
Living polymerization was carried out by adding isoprene monomer (436 g) in the following order: 5 g of methyl alcohol containing 10 g of a phenolic antioxidant (138 was added, and 88 was a styrene block having a number average molecular weight of about 10,100. A styrene-isopre/block copolymer was obtained consisting of a polymer and an isogrene block polymer having a number average molecular force i of %I2 of 80200.The content of 88 in the copolymer was about 11.2 Article.

70 parts of this solid content was added to the formulation of Example 1, and the same procedure as in Example 1 was carried out to obtain a pressure-sensitive adhesive composition.

The comparative examples in Table 1 show the characteristics evaluation results of Examples 1 and 2. A styrene-isoprene-styrene block copolymer having a number average molecular weight of several thousand mers per block of about 140,000 and a total content of styrene block polymers of about 14% by weight is used.Table 1 Examples 3 Mooney viscosity ML + + 4 to the blending composition of Example 1
(100℃) 30 parts of unrefined natural rubber of 45 and 40 parts of Vaseline
part to form a pressure-sensitive adhesive composition, which is about 10 g/
Basis weight 28 Riri'M impregnated with np backsizing agent
'141tEI/'In,,lN/7-1ml
-ys4% I + W 4-/Ga [n adhesive tape was obtained.

The adhesive strength of this tape is approximately 210 g/1811, and the holding strength (according to JIS Z 1524). However, the area for pasting is 18 MN x 25 #111, the load is 500, and the temperature condition is 40°.
C) was 30 minutes, and even if it was applied to furniture or a painted wall and then peeled off, it could be removed well without damaging the surface, and it also had excellent retention performance for the masking sheet (polyethylene film). .

The tensile strength of the composition is 2 kg/α゛, and the tensile elongation is 1.
500%, storage modulus is 0.8 x 10' dyne
/'II+'.

patent applicant Nitto Electric Industry Co., Ltd. Representative Kamigata Sanbe Procedural amendment July 10, 1981 Commissioner of the Patent Office Gakudono Shiga 1.Display of the incident 1982 Patent Application No. 82311 2. Name of the invention pressure sensitive adhesive composition 3. Person who makes corrections Relationship to the incident: Patent applicant 4 Daily Independent 5. Subject of correction (1) Amend the "Claims" as shown in the attached sheet.

(2) Specification page 14, line 7, page 18, line 17
0 or more attached sheet to correct the "storage modulus" in lines 11-12 of page, line 12 of page 19, table 1 of page 22, and line 10 of page 23 with "shear storage modulus""2. Claims 1) General formula (Sl -L)n-S, type block copolymer (wherein Sl and S2 are block polymers derived from styrene or styrene analogs, and the number average of Sl When the molecular weight is 10 (more than 100, the number average molecular weight of %St is 8
000 or less, and II is a block polymer derived from isoprene or an isoprene analog. n is 1
-5 integer) 0 to 100 parts by weight of General Formula 53-1. type block copolymer (Ss is a block polymer derived from styrene or a styrene homologue and % 1m is a block polymer derived from isoprene or an isoprene homolog), and 30 to 40%
1. A pressure-sensitive adhesive composition characterized by being formulated to contain 0 parts by weight of an adhesion-imparting resin.

2) Under a pressure-sensitive adhesive compounded to contain the general formula (Sl L)n S type block copolymer, the general formula S = I2 type block copolymer, and an adhesion-imparting resin, and with a breaking elongation 500% or more of the pressure-sensitive adhesive composition according to claim 1.

3) The blending amount of the general formula Ss la type block co-east combination is 8
90 parts by weight of the pressure sensitive adhesive composition of claim 1.

4) Rubber or polymer other than the general formula S=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+I+)n S2 type a block copolymer. A pressure-sensitive adhesive composition according to claim 1, comprising:

5) Shear storage modulus (by dynamic measurement of linear viscoelasticity) at 20°C and IHz of 3 X 10'dyne/cJ
The pressure-sensitive adhesive composition according to claim 1, which is as follows. ”

Claims (1)

[Scope of Claims] 1) General formula (Sl-11) n-82 type block copolymer (in the formula s S+ and S2 are block polymers derived from styrene or styrene analogs, and the number average molecule t of S+ is 10,000 or more, and the number average molecular weight of Sp is 800
0 or less and %It is a block polymer derived from inglene or imprene analogues On is 1 to 5
0 to 100 parts by weight of a general 25s-Is type block copolymer (Ss is a block polymer derived from styrene or a styrene homolog, etc.) to 100 parts by weight.
1LIa is a pressure-sensitive adhesive characterized by being formulated to contain 0), which is a block polymer derived from isoprene or an isoprene homologue, and 30 to 400 parts by weight of an adhesion-imparting resin. Composition. 2) The pressure-sensitive adhesive composition formulated to contain the general formula (S, -I, ) n-S type block copolymer resin has a tensile strength at room temperature of 10V1 or less and an elongation at break of 500. % or more of the pressure-sensitive adhesive composition according to claim 1. 3) The blending amount of the general formula 5s-It type block copolymer is 8.
~90 parts by weight of the pressure-sensitive adhesive composition according to claim 1 4) General formula (S+L) HS2 type block copolymer 10
The pressure-sensitive adhesive composition according to claim 1, which contains a rubber or polymer other than the general formula 811 I2 block copolymer in an amount not exceeding 50 parts by weight based on 0 parts by weight. 5) The pressure-sensitive adhesive composition according to claim 1, which has a storage modulus (based on dynamic measurement of linear viscoelasticity) in IH2 at 20°C of 3 x 10'dyne/3 or less.