JPH03166280A - Adhesive sheet - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] The present invention relates to a pressure-sensitive adhesive sheet, and more specifically, a pressure-sensitive adhesive sheet made of a diene copolymer is directly and strongly adhered to a base sheet. The present invention relates to an adhesive sheet that can be suitably used as a medicine.

Kyomai Raw Technology Distorted Adhesive Sheet is used for various purposes, for example,
BACKGROUND OF THE INVENTION Patch medicines made by laminating an adhesive containing drugs such as skin irritants and anti-inflammatory analgesics on a base sheet are used for medical purposes. For example, as described in JP-A No. 54-138124, such patch medicines not only have good adhesiveness and elasticity when applied to the skin, but also have good adhesiveness and elasticity when removed from the skin. It is known that diene-based copolymers, particularly diene-based block copolymers, are suitable as adhesives because they do not cause irritation and can be easily peeled off.

On the other hand, for the above-mentioned patches, vinyl chloride resin is suitable as the base sheet because it is flexible and blends well with the skin. It has poor affinity with block copolymers, and in particular, in patch medicines, diene block copolymers as adhesives contain higher fatty acids, liquid paraffin, etc. as plasticizers together with drugs, so vinyl chloride-based Compatibility with the resin base sheet is even poorer.

As a result, when an adhesive made of a diene block copolymer is simply applied directly onto a vinyl chloride resin base sheet to form a patch, there is a problem that the adhesive has poor adhesion to the base sheet. .

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 this method requires an increase in the number of steps. , manufacturing costs inevitably increase.

In order to solve this problem, for example, Japanese Patent Laid-Open No. 1-22
No. 3186 discloses that a base film is formed using a resin film made of a polyurethane-polyvinyl chloride graft copolymer and an ethylene-vinyl acetate copolymer and does not contain a plasticizer, and then a styrene film is formed on the film. A pressure-sensitive adhesive sheet has been proposed in which a pressure-sensitive adhesive made of a low-styrene block copolymer is laminated and bonded, and a release paper is further laminated thereon.

In this way, when the adhesive sheet has a release paper, the release paper is usually cut so that it can be easily peeled off.

In the above-mentioned adhesive sheet, although the base sheet has strong adhesion to the adhesive layer, a small amount of the drug in the adhesive migrates to the base sheet over time, causing the base sheet to swell over time. For example, when stored for a long period of time, as a result of the release paper following the base sheet, voids are formed between the cuts.

In particular, attempts have been made to include a styrene-ethylene-butylene-styrene block copolymer in the base sheet in order to improve its affinity with the adhesive layer, but in such cases, especially when releasing Wide gaps are left between the cuts in the paper pattern, which seriously detracts from the appearance of the product.

As a result of intensive research in order to solve the above-mentioned problem, the inventors of the present invention found that the cause of the formation of voids between the cuts in the release paper as described above is due to the presence of air in the drug. It was determined that the precepts migrate to the base sheet over time, causing the base sheet to swell over time.Especially, when the adhesive layer contains salicylic acid as a drug, polyurethane-polyvinyl chloride-based They also found that when the base sheet contains a styrene-ethylene-butylene-styrene block copolymer, this is swollen by the liquid paraffin in the adhesive. We have discovered that swelling of the base sheet over time can be effectively prevented by blending a predetermined amount of a relatively low molecular weight plasticizer with
This led to the present invention.

That is, in the present invention, a pressure-sensitive adhesive made of a diene block copolymer is directly and strongly laminated and bonded onto a base sheet having excellent texture and flexibility. To provide an adhesive sheet in which no voids are formed between cuts in a paper pattern.

The present invention provides a pressure-sensitive adhesive sheet in which a pressure-sensitive adhesive is laminated on a base sheet made of resin, and a release paper having cuts is further laminated thereon. (b) 1 to 20 parts by weight of a styrene-ethylene-butylene-styrene block copolymer, (C ) Ethylene-vinyl acetate copolymer resin 1-50
parts by weight, and (d) styrene-diene-styrene on a base sheet made of a resin composition containing 4 to 15 parts by weight of a phthalate ester or aliphatic dibasic acid ester plasticizer with an average molecular weight of 300 to 800. It is characterized by being laminated and bonded with an adhesive made of a block copolymer.

In the present invention, the base resin is made of a polyurethane-polyvinyl chloride graft copolymer, a polyvinyl chloride polymer, or a mixture thereof.

The above-mentioned polyvinyl chloride polymers include polyvinyl chloride as well as vinyl chloride copolymers, such as vinyl chloride-vinyl acetate copolymers, vinyl chloride-ethylene copolymers, vinyl chloride-propylene copolymers, etc. and mixtures thereof, but among these, those with an average degree of polymerization of 400
Polyvinyl chloride having an average degree of polymerization of 700 to 1,400 is preferably used.

As the polyurethane-polyvinyl chloride graft copolymer, for example, one commercially available as "Dominus" from Toyo Soda Kogyo ■ can be suitably used. The degree of polymerization of polyvinyl chloride and the composition of polyurethane in the copolymer may vary, but in the present invention, JIS A hardness of 100 to 70 and tensile strength of 250 to 450 k.
A copolymer having an elongation of 200 to 600% in g/cJ is preferably used.

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

According to the present invention, the adhesive sheet includes such a base resin too
For m parts, 1 to 20 parts by weight of styrene-ethylene-butylene-styrene block copolymer, 1 to 50 parts by weight of ethylene-vinyl acetate copolymer resin, and average molecular weight 3
00 to 800 phthalate ester or aliphatic dibasic acid ester plasticizer and 4 to 15 parts by weight.

In the above resin composition, the vinyl chloride polymer or the polyurethane-polyvinyl chloride graft copolymer provides shape processability, particularly fluidity under heating necessary for calendering and extrusion processing, and Provides the required strength to the base sheet.

The styrene-ethylene-butylene-styrene block copolymer gives the base sheet compatibility with the adhesive layer. In the present invention, the styrene-ethylene-butylene-styrene block copolymer is contained in an amount of 1 to 20 Ii parts per 100 parts by weight of the base resin.

The ethylene-vinyl acetate copolymer provides metallic lubricity and flexibility to the resulting base sheet when the resin composition is heated or shaped into a base sheet, and also serves as a pressure-sensitive adhesive. Provides high affinity for styrene-diene styrene block copolymers. In the resin composite, when the amount of the ethylene-vinyl acetate copolymer blended 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, and the shapeability and styrene It has poor affinity for diene-styrene block copolymers. On the other hand, if the amount exceeds 50 parts by weight, the resulting base sheet will have excessive elasticity and, for example, will have poor adhesion to the skin when used as a patch. Further, the resin composition easily softens at high temperatures, resulting in poor processability.

As described above, the adhesive sheet according to the present invention contains a styrene-ethylene-butylene-styrene block copolymer and an ethylene-vinyl acetate copolymer resin together with a base resin and a 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, ethylene-vinyl acetate copolymer resin has a large thermochromic property, and if added in a large amount, it imparts excessive tackiness to the base sheet, resulting in poor lubricity.On the other hand, styrene-ethylene-butylene-styrene block Since the copolymer has strong rubber elasticity, it is not preferable to blend it in too much.

Therefore, according to the present invention, as described above, the amount of styrene-ethylene-butylene-styrene blotter copolymer in the base sheet is 1 to 20 parts by weight, and the amount of ethylene-vinyl acetate copolymer resin is 1 to 50 parts by weight. The flexibility of the base sheet is basically designed by the blending ratio of the plasticizer and the polyurethane-polyvinyl chloride graft copolymer while imparting the above-mentioned desirable properties to the base sheet in terms of parts by weight. From this point of view, in the present invention, the base resin preferably consists of 20 to 80% by weight of a polyurethane-polyvinyl chloride graft copolymer and 80 to 20% by weight of a polyvinyl chloride polymer. Furthermore, according to the present invention,
By incorporating a predetermined amount of a relatively low molecular weight plasticizer into the base sheet, the flexibility of the base sheet is ensured, and by incorporating an appropriate amount of such plasticizer, a release paper is laminated on the adhesive sheet. Also, during long-term storage, the base sheet is effectively prevented from swelling over time, and no voids are formed between the breaks in 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 ranges from 0 to 700. Such plasticizers include
In particular, phthalate ester plasticizers or aliphatic dibasic acid ester plasticizers are preferably used. Specific examples include di-2-ethylhexyl phthalate, dioctyl adipate, diundecyl phthalate, tri(2-ethylhexyl) trimellitate, diisoheptyl phthalate, and the like.

Plasticizers with an average molecular weight of less than 300 have high volatility and poor stability over time, so they do not particularly meet the purpose of the present invention, which is to prevent swelling of the base sheet during long-term storage. On the other hand, even if a high molecular weight plasticizer with an average molecular star exceeding 800 is used, swelling of the base sheet during long-term storage cannot be prevented.

The blending amount of these plasticizers in the base sheet is in the range of 4 to 15 parts by weight based on 100 parts by weight of the base resin.

When the amount of 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 over time is poor, while when it exceeds 15 parts by weight, the plasticizer is Since the agent migrates into the adhesive layer and reduces the adhesive force or alters the quality of the adhesive layer, it becomes difficult to put it into practical use as an adhesive sheet for patch medicine. In particular, in the present invention, the amount of plasticizer blended is preferably in the range of 5 to 12 parts by weight.

According to the present invention, since the plasticizer contained in the base sheet is small, it hardly affects the adhesive.
Therefore, there is no decrease in adhesive strength over time. Furthermore, by incorporating a plasticizer into the base sheet, it is possible to reduce the amount of polyurethane-polyvinyl chloride graft copolymer in the base sheet, thus improving the fluidity of the resin composition.
It is possible to obtain a base sheet that does not undergo thermal discoloration during processing and has excellent transparency.

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

In the pressure-sensitive adhesive sheet of the present invention, a layer of styrene-gene-styrene block copolymer as a pressure-sensitive adhesive is directly laminated and adhered onto the base sheet. According to the invention,
The base sheet made of the above resin composition contains a styrene-ethylene-butylene-styrene block copolymer and has excellent affinity for the styrene-diene-styrene copolymer. When applying an adhesive made of a styrene copolymer, high adhesion can be obtained between the adhesives.

In the present invention, specific examples of the styrene-diene-styrene block copolymer constituting the adhesive include a styrene-butadiene-styrene block copolymer and a styrene-isoprene-styrene block copolymer. . These styrene-diene-styrene block copolymers may be used alone or as a mixture as an adhesive, or in combination with these block copolymers containing a plasticizer, tackifying resin, filler, anti-aging agent, etc. It may also be used as an ornament. Furthermore, as in the case of the patch medicine described above, it may contain necessary drugs.

Such styrene-diene-styrene block copolymers are already known, for example, as described in detail in the above-mentioned Japanese Patent Application Laid-open No. 54-138124. a block of an elastic thermoplastic polymer, and B is a block of an elastic polymer of a conjugated diene such as butadiene or isoprene;
A block copolymer having the structure AB-8,
Block A accounts for ~50% by weight of the total polymer weight. Such styrene-butadiene-styrene block copolymers are called Cariflex TR-1101, TR-11.
The styrene isobrene-styrene block copolymer is commercially available as Cariflex TR-1107 (all manufactured by Shell Chemical Company).

The pressure-sensitive adhesive sheet according to the present invention is produced by molding the resin composition into a sheet, melt-coating a styrene-diene-styrene block copolymer containing drugs and other additives as necessary, and then releasing the resin composition onto the sheet. It can be obtained by gluing paper patterns.

As described above, according to the adhesive sheet of the present invention, the base sheet is made of a polyurethane-polyvinyl chloride graph 1 copolymer, a polyvinyl chloride polymer, or preferably a mixture thereof. Since it is made of a resin composition that further contains ethylene-vinyl acetate copolymer and styrene-ethylene-butylene-styrene copolymer as resin components, it has excellent texture and flexibility. Since it has excellent affinity with styrene block copolymer, the styrene diene-styrene block copolymer as an adhesive is directly and strongly adhered to the base sheet.
For example, it can be suitably used as a patch.

Furthermore, according to the pressure-sensitive adhesive sheet of the present invention, the base sheet contains a relatively low molecular weight plasticizer, and although the reason is not necessarily clear, even when the pressure-sensitive adhesive sheet is stored for a long period of time, the base sheet may deteriorate. The sheet does not swell and, as a result, does not create voids between the breaks in the release paper.

The present invention will be described below with reference to Examples. In addition, in the following, parts mean parts by weight.

Examples As shown in Table 1, polyvinyl chloride with an average degree of polymerization of 800, a polyurethane-polyvinyl chloride graft copolymer,
An ethylene-vinyl acetate copolymer and a styrene-ethylene-butylene-styrene block copolymer were used as resin parts, a stabilizer and a plasticizer were added thereto, and the mixture was shaped into a film with a thickness of 130 μm.

The obtained film was used as a base sheet, and a styrene-isoprene-styrene block copolymer was used as an adhesive to give a thickness of 0. 10cm after melt coating on 1 ++nn
I punched it out with a dangel on the corner. This was used as a sample, sealed in an aluminum bag, and heated at 50°C in a gear oven for 1 hour.
After standing for a day, the area of the film in the vertical and horizontal directions was determined, and this was divided by the initial area to determine the swelling ratio. The results are shown in Table 1. When the swelling ratio is 2.9% or less, no voids are formed between the cut ends of the release paper, but when it exceeds 2.9%, voids are formed between the cut ends 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 width, pasted on a Bakelite plate, left for IO minutes, and then heated at 2001+111/min. A 180° peeling test was conducted to examine the adhesive residue on the Bakelite strip. The results are shown in Table 1. ◯ means that there is no adhesive residue at all, Δ means that the adhesive residue is 1 to 5%, and × means that the adhesive residue exceeds 5%.

Claims (2)

[Claims] (1) An adhesive is laminated on a base sheet made of resin,
Furthermore, in an adhesive sheet on which a release paper having cuts is laminated, (a) 100 parts by weight of a base resin made of a polyurethane-polyvinyl chloride graft copolymer, a polyvinyl chloride-based polymer, or a mixture thereof; about, (2) 1 to 20 parts by weight of styrene-ethylene-butylene-styrene block copolymer, (c) 1 to 50 parts by weight of ethylene-vinyl acetate copolymer resin, and (d) phthalate ester with an average molecular weight of 300 to 800. Or, an adhesive made of a styrene-diene-styrene block copolymer is laminated and bonded on a base sheet made of a resin composition containing 4 to 15 parts by weight of an aliphatic dibasic acid ester plasticizer. Adhesive sheet. (2) The pressure-sensitive adhesive sheet according to claim 1, wherein the base resin comprises 20 to 80% by weight of a polyurethane-polyvinyl chloride graft copolymer and 80 to 20% by weight of a polyvinyl chloride polymer. .