JPH0653872B2 - Adhesive sheet - Google Patents

Description

TECHNICAL FIELD The present invention relates to a pressure-sensitive adhesive sheet, and more specifically, a pressure-sensitive adhesive composed of a diene-based copolymer is directly and firmly adhered to a substrate sheet. The present invention relates to a pressure-sensitive adhesive sheet that can be suitably used.

Conventional technology Adhesive sheets are used in various applications, for example,
BACKGROUND OF THE INVENTION Patches prepared by laminating an adhesive containing a drug such as a skin stimulant or an anti-inflammatory analgesic on a base sheet are used for medical purposes. In such a patch, for example, as described in JP-A-54-138124, not only does the patch have good adhesiveness and elasticity when it is applied to the skin, but also the skin when peeled off. It is known that a diene-based copolymer, particularly a diene-based block copolymer, is particularly suitable as the pressure-sensitive adhesive because it can be easily peeled off without giving any irritation.

On the other hand, in the patch as described above, as the base sheet, a vinyl chloride resin which is soft and conforms to the skin is preferable, but on the other hand, the vinyl chloride resin sheet is a diene-based adhesive as an adhesive. Poor affinity with block copolymer, especially in patch, since diene block copolymer as an adhesive contains higher fatty acid and fluid paraffin as a plasticizer together with a drug, vinyl chloride type Poor affinity with resin base sheet. As a result, when a pressure-sensitive adhesive composed of a diene-based block copolymer is simply applied directly onto a vinyl chloride-based resin base sheet to form a patch, there is a problem in that the adhesiveness of the pressure-sensitive adhesive to the base sheet is poor.

Therefore, it is possible to increase the affinity for the diene block copolymer by subjecting the vinyl chloride resin sheet to an appropriate primer treatment, but with this method, as the number of steps increases, However, the manufacturing cost must be high.

In order to solve this problem, for example, Japanese Patent Laid-Open No. 1-22
No. 3186 discloses that a base film is formed from a resin composition containing a polyurethane-polyvinyl chloride graft copolymer and an ethylene-vinyl acetate copolymer and containing no plasticizer, and a styrene-diene-containing film is formed on the base film. A pressure-sensitive adhesive sheet has been proposed in which a pressure-sensitive adhesive composed of a styrene block copolymer is laminated and adhered, and further release paper is laminated thereon.
As described above, when the pressure-sensitive adhesive sheet has a release paper, the release paper is usually cut so that it can be easily peeled off.

The above-mentioned pressure-sensitive adhesive sheet, while the base sheet has a strong adhesive force to the pressure-sensitive adhesive layer, while the drug in the pressure-sensitive adhesive is slightly over time, it migrates to the base sheet and causes the base sheet to swell over time. For example, when stored over a long period of time, the release paper follows the base sheet, and as a result, voids are formed between the cuts.

In particular, it has been attempted to add a styrene-ethylene-butylene-styrene block copolymer to the base material sheet in order to enhance the affinity with the pressure-sensitive adhesive layer. Wide voids are formed between the cuts in the paper pattern, which significantly impairs the appearance of the product.

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention The inventors of the present invention have conducted extensive studies to solve the above-mentioned problems, and as a result, the cause of the voids between the cuts of the release paper is that the components in the drug are It was determined that this is to transfer to a base sheet and swell the base sheet with time. In particular, when the pressure-sensitive adhesive layer contains salicylic acid as a drug, it swells the polyurethane-polyvinyl chloride polymer, and when the substrate sheet contains a styrene-ethylene-butylene-styrene block copolymer, this causes adhesion. It was clarified that it swells due to the fluid paraffin in the agent, and by incorporating a predetermined amount of a relatively low molecular weight plasticizer into the substrate sheet, effective swelling of the substrate sheet over time is achieved. The present invention has been made by finding that the above can be prevented.

That is, in the present invention, a pressure-sensitive adhesive comprising a diene block copolymer is directly and strongly laminated and adhered on a base material sheet having excellent feeling and flexibility, and further, it can be stored for a long period of time. An object of the present invention is to provide a pressure-sensitive adhesive sheet in which voids are not formed between the cut lines of the release paper.

Means for Solving the Problems The present invention is a pressure-sensitive adhesive sheet in which a pressure-sensitive adhesive is laminated on a base material sheet made of a resin, and further release paper having cuts is laminated thereon, (a) polyurethane-poly Vinyl chloride graft copolymer,
With respect to 100 parts by weight of a base resin made of a polyvinyl chloride-based polymer or a mixture thereof, (b) 1 to 20 parts by weight of styrene-ethylene-butylene-styrene block copolymer, (c) ethylene-vinyl acetate copolymer Styrene-based on a resin sheet comprising 1 to 50 parts by weight of a resin, and (d) 4 to 15 parts by weight of a phthalate ester or an aliphatic dibasic acid ester plasticizer having an average molecular weight of 300 to 800 A pressure-sensitive adhesive comprising a diene-styrene block copolymer is laminated and adhered.

In the present invention, the base resin comprises a polyurethane-polyvinyl chloride graft copolymer, a polyvinyl chloride-based polymer or a mixture thereof.

The polyvinyl chloride-based polymer means, in addition to polyvinyl chloride, a copolymer of vinyl chloride, for example, vinyl chloride-vinyl acetate copolymer, vinyl chloride-ethylene copolymer, vinyl chloride-propylene copolymer, etc. Or a mixture of these, but among these, the average degree of polymerization is 400
.About.2000, particularly preferably polyvinyl chloride having an average degree of polymerization of 700 to 1400.

As the polyurethane-polyvinyl chloride graft copolymer, for example, one commercially available as "Dominus" from Toyo Soda Kogyo Co., Ltd. can be preferably used. The degree of polymerization of polyvinyl chloride and the composition of polyurethane in the copolymer may be variously changed, but in the present invention, JIS A hardness is 100 to 70, tensile strength is 250 to 450 kg / cm ² , and elongation is 2.
A copolymer having a content of 00 to 600% is preferably used.

As the ethylene-vinyl acetate copolymer, one having a vinyl acetate content of 5 to 85% by weight is usually used.
In particular, one having a vinyl acetate content of 45% by weight or more is preferably used so that the resin composition has excellent calenderability. The ethylene-vinyl acetate copolymer includes an ethylene-vinyl acetate-vinyl chloride copolymer.

According to the present invention, the pressure-sensitive adhesive sheet has the base resin 100.
Regarding parts by weight, 1 to 20 parts by weight of a styrene-ethylene-butylene-styrene block copolymer, 1 to 50 parts by weight of an ethylene-vinyl acetate copolymer resin, and an average molecular weight of 3
And a resin composition containing 4 to 15 parts by weight of a phthalate ester or an aliphatic dibasic acid ester plasticizer of 0 to 800.

In the above resin composition, the vinyl chloride polymer or the polyurethane-polyvinyl chloride graft copolymer gives its moldability, in particular, the fluidity under heating necessary for calendering and extrusion, as well as the substrate. Gives the sheet the required strength.

The styrene-ethylene-butylene-styrene block copolymer gives the base sheet an affinity for the pressure-sensitive adhesive layer. In the present invention, the styrene-ethylene-butylene-styrene block copolymer is contained in the range of 1 to 20 parts by weight with respect to 100 parts by weight of the base resin.

The ethylene-vinyl acetate copolymer gives metal slidability when the resin composition is heat-formed into a base sheet, and also gives flexibility to the obtained base sheet, and further, styrene constituting a pressure-sensitive adhesive. -Provides a high affinity for diene-styrene block copolymers. In the resin composition,
When the blending amount of the ethylene-vinyl acetate copolymer is less than 1 part by weight with respect to 100 parts by weight of the base resin, the above effects cannot be sufficiently obtained, resulting in moldability and styrene-diene-styrene block copolymerization. It has poor affinity for coalescence. On the other hand, when it exceeds 50 parts by weight, the obtained base sheet has excessive elasticity, and for example,
When it is used as a patch, it will not fit well on the skin.
In addition, the resin composition is likely to soften at high temperatures, resulting in poor processability.

Thus, the pressure-sensitive adhesive sheet according to the present invention contains the styrene-ethylene-butylene-styrene block copolymer and the ethylene-vinyl acetate copolymer resin together with the base resin and the plasticizer. Among these, the elastic polymers are polyurethane-polyvinyl chloride graft copolymers, styrene-ethylene-butylene-styrene block copolymers and ethylene-vinyl acetate copolymer resins. However, the ethylene-vinyl acetate copolymer resin has a large thermochromic property, and if it is blended in a large amount, it imparts excessive tackiness to the base sheet, resulting in poor lubricity, while styrene-ethylene-butylene-
Since the styrene block copolymer has a strong rubber elasticity, it is not preferable to add too much of it.

Therefore, according to the present invention, as described above, the amount of the styrene-ethylene-butylene-styrene block copolymer in the base sheet is set to 1 to 20 parts by weight, and the amount of the ethylene-vinyl acetate copolymer resin is set to 1 to 50. In parts by weight, the flexibility of the base sheet is basically designed by the compounding ratio of the plasticizer and the polyurethane-polyvinyl chloride graft copolymer while imparting the above-mentioned desirable properties to the base sheet. From such a viewpoint, in the present invention, the base resin preferably comprises 20 to 80% by weight of the polyurethane-polyvinyl chloride graft copolymer and 80 to 20% by weight of the polyvinyl chloride polymer.

Further, according to the present invention, by containing a predetermined amount of a plasticizer having a relatively low molecular weight in the base material sheet, the flexibility of the base material sheet is ensured, and an appropriate amount of the plasticizer is compounded. Even if a release paper is laminated on the pressure-sensitive adhesive sheet, the base sheet is effectively prevented from swelling with time during storage for a long period of time, and voids are not formed between the cuts of the release paper.

The plasticizer used in the present invention has an average molecular weight of 300 to
Must be in the range of 800, preferably 40
It is in the range of 0 to 700. As such a plasticizer,
Particularly, a phthalic acid ester plasticizer or an aliphatic dibasic acid ester plasticizer is preferably used. Specific examples include, for example, di-2-ethylhexyl phthalate, dioctyl adipate, diundecyl phthalate, and tri (2
-Ethylhexyl) trimellitate, diisoheptyl phthalate and the like can be mentioned.

A plasticizer having an average molecular weight of less than 300 has a high volatility and is inferior in stability over time, and thus does not meet the purpose of the present invention for preventing swelling of a base sheet during storage for a long period of time. On the other hand, even if a high molecular weight plasticizer having an average molecular weight of more than 800 is used, it is not possible to prevent the swelling of the base sheet during storage for a long period of time.

The compounding amount of these plasticizers in the base sheet is in the range of 4 to 15 parts by weight with respect to 100 parts by weight of the base resin.
When the amount of the plasticizer blended is less than 4 parts by weight per 100 parts by weight of the base resin, the effect of preventing the base film from swelling with time is poor, and when it exceeds 15 parts by weight, the plasticizer is added in excess. Since it migrates into the pressure-sensitive adhesive layer to reduce the pressure-sensitive adhesive force or to change the quality of the pressure-sensitive adhesive layer, it becomes difficult to put it into practical use as a pressure-sensitive adhesive sheet for patches. Particularly, in the present invention, the compounding amount of the plasticizer is preferably in the range of 5 to 12 parts by weight.

According to the present invention, since the plasticizer contained in the base material sheet is small in this way, it hardly affects the adhesive,
Therefore, the adhesive strength does not decrease with time. Furthermore, by blending a plasticizer into the base sheet, the polyurethane-polyvinyl chloride graft copolymer in the base sheet can be reduced, thus improving the fluidity of the resin composition,
It is possible to obtain a base material sheet which is free from thermal discoloration during processing and has excellent transparency.

In the present invention, the thickness of the substrate sheet is appropriately selected depending on the application, but is usually 0.05 to 0.20 mm.

In the pressure-sensitive adhesive sheet according to the present invention, a layer of styrene-diene-styrene block copolymer as a pressure-sensitive adhesive is directly laminated and adhered on the base sheet. According to the invention,
Since the base material sheet comprising the above resin composition contains a styrene-ethylene-butylene-styrene block copolymer and has an excellent affinity for a styrene-diene-cytylene copolymer, a styrene-diene-styrene copolymer is further added. When a pressure-sensitive adhesive made of a polymer is applied, high adhesiveness can be obtained during that time.

In the present invention, styrene-diene-constituting the pressure-sensitive adhesive
Specific examples of the styrene block copolymer include a styrene-butadiene-butylene block copolymer and a styrene-isoprene-styrene block copolymer. These styrene-diene-styrene block copolymers may be used alone or as a mixture as a pressure-sensitive adhesive, or a composition containing a plasticizer, a tackifying resin, a filler, an antioxidant and the like together with these block copolymers. It may be used as a product. Further, it may contain a necessary drug as in the case of the above-mentioned patch.

Such a styrene-diene-styrene block copolymer is already known as described in detail in, for example, JP-A-54-138124 mentioned above, and A is a glassy or hard non-polymer made of styrene. When the block is an elastic thermoplastic polymer and B is the block of an elastic polymer of a conjugated diene such as butadiene or isoprene, the block copolymer having the structure ABA, in which all the blocks A are It accounts for 10 to 50% by weight of the polymer weight. Such styrene-butadiene-styrene block copolymers are known as Califlex TR-1101, TR-.
1102 and the like, and a styrene-isoprene-styrene block copolymer is Califlex TR-1107.
(Both are manufactured by Shell Chemical Co., Ltd.) and can be obtained.

The pressure-sensitive adhesive sheet according to the present invention is obtained by molding the resin composition into a sheet, melt-coating a styrene-diene-styrene block copolymer containing a drug and other additives as necessary, and further releasing the release paper. Can be obtained by sticking.

EFFECTS OF THE INVENTION As described above, according to the pressure-sensitive adhesive sheet of the present invention, the base material sheet further comprises a base material resin made of a polyurethane-polyvinyl chloride graft copolymer, a polyvinyl chloride-based polymer or preferably a mixture thereof. , Ethylene as the resin component
Vinyl acetate copolymer and styrene-ethylene-butylene-
Since it is composed of a resin composition containing a styrene copolymer, it has an excellent feel and flexibility, and further has an excellent affinity with a styrene-diene-styrene block copolymer, so that it is an adhesive on a base sheet. As styrene-diene-
The styrene block copolymer is directly and firmly adhered, and can be suitably used, for example, as a patch.

Furthermore, according to the pressure-sensitive adhesive sheet of the present invention, since the base material sheet contains a relatively low molecular weight plasticizer, the reason is not always clear, but even by long-term storage of the pressure-sensitive adhesive sheet, The substrate sheet does not swell and, as a result, does not produce voids between the cuts in the release paper.

EXAMPLES The present invention will be described below with reference to examples. In the following, parts mean parts by weight.

Examples As shown in Table 1, polyvinyl chloride having an average degree of polymerization of 800, polyurethane-polyvinyl chloride graft copolymer,
An ethylene-vinyl acetate copolymer and a styrene-ethylene-butylene-styrene block copolymer were used as resin components, and a stabilizer and a plasticizer were added to the resin component to give a thickness of 130 μm.
Was formed into a film.

The obtained film was used as a base sheet, and a styrene-isoprene-styrene block copolymer was melt-coated as a pressure-sensitive adhesive to a thickness of 0.1 mm and punched with a 10 cm square dumbbell. Using this as a sample, it was sealed in an aluminum bag and left in a gear oven at 50 ° C. for 1 day.
The vertical and horizontal areas of the film were determined, and this was divided by the initial area to determine the swelling rate. The results are shown in Table 1. When the swelling ratio is 2.9% or less, no void is formed between the cuts of the release paper, but when it exceeds 2.9%, voids are formed between the cuts of the release paper.

The sample was sealed in an aluminum bag, left in a gear oven at 50 ° C for 1 day, cut into 25 mm, stuck to a bakelite plate, left for 10 minutes, and then 2
A 180 ° peeling peel test was performed at 00 mm / min to examine the adhesive residue on the Bakelite plate. The results are shown in Table 1. ○ indicates no adhesive residue, △ indicates 1 to 5 adhesive residue
%, X means that the adhesive residue exceeds 5%.

Claims (2)

[Claims] 1. A pressure-sensitive adhesive sheet comprising a base sheet made of a resin, a pressure-sensitive adhesive laminated on the base sheet, and a release paper having a slit formed thereon, comprising: (a) a polyurethane-polyvinyl chloride graft copolymer. ,
With respect to 100 parts by weight of a base resin made of a polyvinyl chloride polymer or a mixture thereof, (b) 1 to 20 parts by weight of styrene-ethylene-butylene-styrene block copolymer, (c) ethylene-vinyl acetate copolymer Styrene on a base sheet made of a resin composition containing 1 to 50 parts by weight of a resin, and (d) 4 to 15 parts by weight of a phthalate ester or an aliphatic dibasic acid ester plasticizer having an average molecular weight of 300 to 800 A pressure-sensitive adhesive sheet, characterized in that a pressure-sensitive adhesive comprising a diene-styrene block copolymer is laminated and adhered. 2. The adhesive according to claim 1, which comprises a base resin polyurethane-polyvinyl chloride graft copolymer of 20 to 80% by weight and a polyvinyl chloride polymer of 20 to 20% by weight. Sheet.