JPH0558603B2 - - Google Patents

Description

[Detailed description of the invention]

INDUSTRIAL APPLICATION FIELD The present invention relates to an adhesive sheet, and more specifically, an adhesive made of a diene copolymer is directly and firmly adhered to a base sheet made of a vinyl chloride copolymer and an ethylene-vinyl acetate copolymer. The present invention relates to an adhesive sheet that can be suitably used as a patch, for example. Conventional technology Adhesive sheets are used for various purposes, but
For example, patches are used for medical purposes, in which adhesives containing drugs such as skin irritants and anti-inflammatory analgesics are laminated on a base sheet. In such patch medicines, for example, as described in JP-A-54-138124, when the patch medicine is applied to the skin, it not only has good adhesiveness and elasticity, but also has good adhesion and elasticity.
As adhesives, diene copolymers,
It is known that diene block copolymers are particularly suitable. 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 a pressure-sensitive adhesive made of a diene block copolymer is simply applied directly onto a vinyl chloride-based resin base sheet to form a patch, there is a problem that the adhesive properties of the pressure-sensitive adhesive to the base sheet are poor. Therefore, although it is possible to increase the affinity for the diene block copolymer by subjecting the vinyl chloride resin sheet to an appropriate primer treatment,
However, according to this method, manufacturing costs inevitably increase as the number of steps increases. In order to solve this problem, for example,
61-215682 and JP-A-62-227983 disclose that a resin composition prepared by mixing polyvinyl chloride with a styrene-ethylene-butylene-styrene block copolymer is molded into a base sheet. A method has been proposed in which a pressure-sensitive adhesive sheet made of a styrene-diene-styrene block copolymer is laminated and bonded onto a base sheet, but styrene-ethylene-butylene-styrene block copolymer is In addition to being expensive, there is a risk that chemicals in the adhesive may migrate into the base sheet and impair the strength of the base sheet. Problems to be Solved by the Invention The present invention was made to solve the above-mentioned problems, and is made of a vinyl chloride polymer and an ethylene-vinyl acetate copolymer that have excellent texture and flexibility. An object of the present invention is to provide a pressure-sensitive adhesive sheet in which a pressure-sensitive adhesive made of a diene block copolymer is directly laminated and bonded firmly onto a base sheet. Means for Solving the Problems The adhesive sheet according to the present invention contains (a) 100 parts by weight of a vinyl chloride polymer, (b) 10 to 100 parts by weight of an ethylene-vinyl acetate copolymer having a vinyl acetate content of 5 to 85% by weight. parts by weight, and (c) an adhesive made of a styrene-diene-styrene block copolymer on a base sheet made of a resin composition containing 10 to 100 parts by weight of a high molecular weight ester plasticizer with an average molecular weight of about 800 or more. It is characterized by being laminated and bonded. In the present invention, vinyl 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. Polyvinyl chloride having an average degree of polymerization of 400 to 2000, particularly preferably 700 to 1400, is preferably used. Similarly, ethylene-vinyl acetate copolymer includes ethylene-vinyl acetate-vinyl chloride copolymer, but in the present invention, in particular, those having a vinyl acetate content of 5 to 85% by weight are used. preferable. The plasticizer used in the present invention has a molecular weight of about
It is an ester-based high molecular weight plasticizer with a molecular weight of 800 or more, preferably 1000 or more. Preferred specific examples of such ester-based high molecular weight plasticizers include polyalkylene glycol diesters such as polyethylene glycol diester of phthalic acid, polypropylene glycol diester, polyethylene glycol polypropylene glycol diester, etc., and aliphatic plasticizers such as adipic acid, sebacic acid, etc. Mention may be made of polyalkylene glycol diesters such as polyethylene glycol diesters of dibasic acids, polypropylene glycol diesters, polyethylene glycol polypropylene glycol diesters, and the like. In the adhesive sheet according to the present invention, the base sheet is made of a vinyl chloride polymer as described above.
It consists of a resin composition containing 10 to 100 parts by weight of the ethylene-vinyl acetate copolymer and 10 to 100 parts by weight of the plasticizer per 100 parts by weight. In the resin composition, the vinyl chloride polymer provides moldability, particularly fluidity under heating necessary for calendering and extrusion processing, and also provides the base sheet with the required strength. The ethylene-vinyl acetate copolymer provides metallic slipperiness and flexibility to the resulting base sheet when the resin composition is heat-molded into a base sheet, and also provides styrene constituting the adhesive. - Provides high affinity for diene-styrene block copolymers. Therefore, in the resin composition, when the amount of the ethylene-vinyl acetate copolymer is less than 10 parts by weight per 100 parts by weight of the vinyl chloride polymer, the above effects cannot be sufficiently obtained.
It is inferior in both moldability and affinity for styrene-diene-styrene block copolymers. On the other hand, if the amount exceeds 100 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. Since the plasticizer has a predetermined high molecular weight, it does not migrate to the adhesive, thus providing flexibility to the base sheet while preventing the adhesive from decreasing over time. Therefore, in the resin composition, the amount of plasticizer blended per 100 parts by weight of vinyl chloride polymer is
When the amount is less than 10 parts by weight, the above effects cannot be sufficiently obtained. On the other hand, if it exceeds 100 parts by weight, the molding processability of the resin composition deteriorates, and the resulting base material becomes excessively flexible, making it difficult to apply it to the skin when used as a patch. 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-diene-styrene block copolymer as a pressure-sensitive adhesive is directly laminated and adhered onto the base sheet. According to the present invention, since the base sheet made of the resin composition has excellent affinity for the styrene-diene-styrene block copolymer, an adhesive made of the styrene-diene-styrene copolymer is directly applied thereon. By applying this, high adhesion can be achieved between them. In the present invention, styrene constituting the adhesive
Specific examples of the diene-styrene block copolymer include styrene-butadiene-styrene block copolymer and styrene-isoprene-styrene block copolymer. These styrene-diene-styrene block copolymers may be used alone or as a mixture as an adhesive, or in compositions containing plasticizers, tackifying resins, fillers, anti-aging agents, etc. together with these block copolymers. It may also be used as an object. 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. 138124/1983, in which A is a glassy or hard non-styrene copolymer. When the block is made of an elastic thermoplastic polymer, and B is a block of an elastic polymer of a conjugated diene such as butadiene or isoprene, it is a block copolymer having the structure A-B-A, and the block A is entirely It accounts for 10-50% by weight of the polymer weight. Such styrene-butadiene-styrene block copolymers are called Cariflex TR-1101, TR-
1102 etc., and styrene-isoprene-styrene block copolymer is CARIFLEX TR-
1107 (all manufactured by Ciel Kagaku Co., Ltd.), and can be obtained. The adhesive sheet according to the present invention can be obtained by molding the resin composition into a sheet and melt-coating the styrene-diene-styrene block copolymer containing drugs and other additives as necessary. can. In connection with the molding process of the resin composition into a sheet, particularly when calendering is used, the resin composition according to the present invention contains (a) based on 100 parts by weight of vinyl chloride polymer, (b) 10 to 30 parts by weight of an ethylene-vinyl acetate copolymer having a vinyl acetate content of 25 to 45% by weight, or 30 to 100 parts by weight of an ethylene-vinyl acetate copolymer having a vinyl acetate content of 25 to 45% by weight, and (c) average The resin composition preferably contains 10 to 100 parts by weight of a high molecular weight ester plasticizer having a molecular weight of about 800 or more, preferably about 1000 or more. When the vinyl acetate content of the ethylene-vinyl acetate copolymer is less than 25% by weight, the resulting resin composition is difficult to form into a sheet by calendering, even when used in combination with the high molecular weight plasticizer. . According to the invention, the vinyl acetate content is from 25 to 45% by weight, preferably from 30 to 35% by weight, in particular about 33% by weight.
By blending 10 to 30 parts by weight of the ethylene-vinyl acetate copolymer with respect to 100 parts by weight of the vinyl chloride polymer, high roll processability can be obtained, and the base sheet can be formed by calendering. can be manufactured. Further, an ethylene-vinyl acetate copolymer having a vinyl acetate content of 45 to 85% by weight, preferably 55 to 65% by weight, particularly 56 to 62% by weight is added to 30 to 100 parts by weight per 100 parts by weight of the vinyl chloride polymer. High roll processability can be obtained even by adding the amount in parts by weight, and a base sheet can be manufactured by calendering. Effects of the Invention As described above, the pressure-sensitive adhesive sheet of the present invention contains an ethylene-vinyl acetate copolymer as well as a vinyl chloride polymer, and therefore has excellent texture and flexibility. Because it has excellent affinity with diene-styrene block copolymer,
A styrene-diene-styrene block copolymer as an adhesive is directly and strongly adhered to the base sheet, and can be suitably used as a patch, for example. Furthermore, according to the adhesive sheet of the present invention, since the plasticizer contained in the base sheet is a high molecular weight plasticizer, there is no change in the hardness of the base sheet over time, etc.
It has excellent durability, and since the transfer of plasticizer to the adhesive is suppressed, the adhesive properties of the adhesive sheet are maintained over a long period of time, and even when used as a patch, there is no irritation to the skin. Less is. Furthermore, since there is no need to perform primer treatment on the base sheet, it can be manufactured at low cost. Further, according to the present invention, a base sheet is prepared by blending a predetermined amount of an ethylene-vinyl acetate copolymer having a predetermined vinyl acetate content with a predetermined high molecular weight plasticizer into a vinyl chloride polymer. It can be manufactured by a calendar method. Examples The present invention will be explained below with reference to Examples. still,
In the following, parts mean parts by weight. Example As shown in Table 1, a resin composition was prepared by mixing polyvinyl chloride with an average degree of polymerization of 1250 with ethylene-vinyl acetate copolymers and plasticizers having various vinyl acetate contents, and roll processing was performed. In addition to evaluating the properties, after processing this resin composition into a sheet, a styrene-isoprene-styrene block copolymer (Califlex TR-1) was applied as an adhesive on the sheet.
1107) was melt applied and the adhesion between the base sheet and the above adhesive was evaluated. In addition, roll processability is 12 inches, 2 rolls,
Visually observe gelation and bank conditions of the resin composition during kneading at a surface temperature of 170°C, slipperiness with rolls, plate-out properties, and surface smoothness and discoloration of the resulting sheet. It was evaluated as follows. The results are shown in Table 1. In this evaluation, ○ is good, △
indicates that the condition is normal and no problems are observed, × indicates that it is not good, and XX indicates that it is extremely bad.

[Table] For the adhesive between the base sheet and the adhesive, apply the adhesive to the base sheet at a rate of 70g/m ² and store at 23°C.
Alternatively, the adhesiveness was evaluated after being left for 7 days under constant temperature and humidity conditions of 95% RH at a temperature of 50°C. Adhesion was evaluated by preparing a test piece of an adhesive sheet with a width of 25 mm and a length of 5 cm, pasting it on a Bakelite plate, leaving it for 1 hour, and then performing a 180° peel test at a tensile speed of 200 mm/min. The results are shown in Table 1. In this evaluation, ○ means that the adhesive does not peel off from the base sheet (◎ is particularly good), △ means that the adhesive partially peels off from the base sheet, but no particular problem is observed in practical use, × indicates that the adhesive peels off easily from the base sheet (XX indicates particularly bad). Example 2 As shown in Table 2, a resin composition was prepared by mixing polyvinyl chloride with an average degree of polymerization of 1250, an ethylene-vinyl acetate copolymer, and plasticizers having various average molecular weights. In the same manner as in Example 1, roll processability was evaluated, and this resin composition

After processing [Table] into a sheet, the same styrene-isoprene-styrene block copolymer as in Example 1 was melt-coated as an adhesive onto the sheet, and the adhesive between the base sheet and the above adhesive was evaluated. The results are shown in Table 2.

Claims (1)

[Scope of Claims] 1 (a) 100 parts by weight of vinyl chloride polymer, (b) 10 to 100 parts by weight of ethylene-vinyl acetate copolymer having a vinyl acetate content of 5 to 85% by weight, and (c) average An adhesive made of a styrene-diene-styrene block copolymer is laminated and bonded onto a base sheet made of a resin composition containing 10 to 100 parts by weight of a high molecular weight ester plasticizer with a molecular weight of approximately 800 or more. Adhesive sheet with special features. 2 (a) For 100 parts by weight of vinyl chloride polymer, (b) 10 to 30 parts by weight of ethylene-vinyl acetate copolymer having a vinyl acetate content of 25 to 45% by weight, or ethylene having a vinyl acetate content of 45 to 85% by weight. - 30 to 100 parts by weight of a vinyl acetate copolymer, and (c) 10 to 100 parts by weight of a high molecular weight ester plasticizer with an average molecular weight of about 800 or more. - A pressure-sensitive adhesive sheet characterized in that a pressure-sensitive adhesive comprising a diene-styrene block copolymer is laminated and bonded.