JPH06200220A - Production of gas-permeable pressure-sensitive tape or sheet - Google Patents

Abstract

PURPOSE:To obtain stably the subject tape or sheet having vents with diameters of a sufficient size by applying a pressure-sensitive adhesive solution obtained by diluting a pressure-sensitive substance and a water-absorptive polymer compound in the state of absorbing water in a hydrophobic organic solvent to a substrate and drying the wet film under specified conditions. CONSTITUTION:A pressure-sensitive adhesive solution prepared by diluting a pressure- sensitive substance and a water-absorptive polymer compound in the state of sufficiently absorbing water in a hydrophobic organic solvent having a boiling point of 100-110 deg.C is applied to a substrate or a release sheet. The wet film is subjected to the initial drying under conditions including a gas velocity of 5m/sec or below and a drying time of a least 50 sec and the subsequent drying under conditions in which the drying rate is higher than that under the initial drying condition to form a porous adhesive layer. To perform the subsequent drying, it is not necessary to reduce the gas velocity, and every effort is made to evaporate completely the water from the water-absorptive polymer compound. It is suitable that the drying conditions are gradually made severer in several stages so as to inhibit the foaming, etc., of the pressure-sensitive agent.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing an air-permeable pressure-sensitive adhesive tape or sheet.

[0002]

2. Description of the Related Art As is well known, in an adhesive tape used for medical purposes, air permeability is required as an essential function in order to prevent stuffiness and fogging.

As a method for producing such a pressure-sensitive adhesive tape having air permeability, a method is known in which a pressure-sensitive adhesive layer formed by coating a pressure-sensitive adhesive on a base material and then drying it is made porous.

As one of the methods, a pressure-sensitive adhesive formed by dispersing a water-absorbing polymer substance in an organic solvent for diluting the pressure-sensitive adhesive, coating the pressure-sensitive adhesive on a breathable substrate and drying. There is a report that the agent layer is aerated (Japanese Patent Publication No. 63-41585).

[0005]

However, in the method described in Japanese Examined Patent Publication No. 63-41585, the size of pores generated is much larger than the diameter corresponding to the volume of the water-absorbing polymer compound absorbing water. It was observed to be small.

The present invention has been made in view of the above problems, and further provides a method for producing a breathable pressure-sensitive adhesive tape or sheet comprising a breathable pressure-sensitive adhesive layer having a stable and sufficient size. The purpose is.

[0007]

Means for Solving the Problems As a result of extensive studies as a method for solving the above problems, the present invention has a mechanism that pores having a stable size are generated in an adhesive layer as follows. I came to the conclusion.

By dispersing the water-absorbing water-absorbing polymer compound in the pressure-sensitive adhesive dissolved and diluted with a hydrophobic organic solvent by stirring or the like, the water-absorbing polymer compound is present in the pressure-sensitive adhesive. The water-absorbent polymer compound is uniformly dispersed with a certain size, and the portion corresponding to the volume of the water-absorbing polymer compound functions as a discontinuous layer of the pressure-sensitive adhesive, that is, pores. According to the method described in JP-B-63-41585, it was observed that the size of pores generated was much smaller than the diameter corresponding to the volume of the water-absorbing polymer compound absorbing water.

Here, the mechanism by which the adhesive solution is dried to generate pores will be described with reference to FIG. Adhesive solution 1
As a condition for drying 1, the water content in the water-absorbing polymer compound 13 that is absorbing water until the organic solvent 12 is first evaporated is prevented from evaporating, so that the volume of the water-absorbing polymer compound 13 becomes a prototype in the initial stage of drying. And the pore diameter corresponding to the volume of the water-absorbing polymer compound 13 is 15
Can be sufficiently secured, and will act as pores having a function of passing gas.

If the organic solvent 12 evaporates as shown in FIG. 2, or if the water content in the water-absorbing polymer compound 13 that is absorbing before the organic solvent 12 completely evaporates, from the beginning of drying. This means that the volume of the water-absorbing polymer compound 13 contracts, and as a result, a sufficient pore size 15 cannot be secured.

Therefore, we have found that the above object can be achieved by limiting the drying conditions for drying the adhesive solution and the organic solvent for dissolving and diluting the adhesive substance to a certain specific range. Is.

That is, according to the present invention, the adhesive substance and the water-absorbing polymer compound which is sufficiently absorbing water are 100 to 110 ° C.
A pressure-sensitive adhesive solution diluted with a hydrophobic organic solvent having a boiling point of
m / sec or less and a drying time of at least 50 seconds or more and an initial drying condition, and a late drying condition in which the drying speed is higher than the initial drying condition causes a porous adhesive layer to be produced. A method for producing a breathable pressure-sensitive adhesive tape or sheet, characterized in that the pressure-sensitive adhesive layer is positioned on a substrate.

The details of the present invention will be described below. The pressure-sensitive adhesive solution used in the present invention is obtained by diluting a pressure-sensitive adhesive substance with an organic solvent having a hydrophobic boiling point of 100 to 110 ° C. and uniformly dispersing a water-absorbing polymer compound which has sufficiently absorbed water. is there. The adhesive substance is not particularly limited as long as it can be dissolved and diluted in the hydrophobic organic solvent used in the present invention, and examples thereof include natural or synthetic rubber used for ordinary adhesive tapes or An acrylic type can be mentioned.

When the organic solvent for dissolving and diluting the above-mentioned adhesive substance is hydrophilic, the above-described water-absorbing polymer compound which has sufficiently absorbed water has an interface in the adhesive diluted with the organic solvent. However, it becomes impossible to maintain the state of dispersion with a constant particle size.

Further, even if it is hydrophobic, if the boiling point is less than 100 ° C., the evaporation rate of the organic solvent becomes too fast.
It is not necessary that the evaporation of the organic solvent simply becomes faster than the water in the water-absorbing polymer compound that is sufficiently absorbing water, and if the evaporation rate becomes too fast, then the water-absorbing polymer compound becomes It becomes difficult to remain in a state of being uniformly dispersed in the pressure-sensitive adhesive layer, and the obtained pores also become non-uniform.

Further, the boiling point of the hydrophobic organic solvent is 110 ° C.
When it exceeds the above, the organic solvent in the pressure-sensitive adhesive solution, as described above, evaporates at the same time or slowly as the water in the water-absorbing polymer compound that is sufficiently absorbing water evaporates, so that the water-absorbing polymer The volume of the compound contracts, and it becomes impossible to obtain pores having a sufficient size.

An organic solvent satisfying the above requirements, that is, an adhesive substance can be dissolved and diluted, and it is hydrophobic and has a boiling point of 1
Examples of the organic solvent having a temperature of about 00 to 110 ° C. include aromatic hydrocarbons, and among them, toluene is particularly preferable as an industrially usable solvent.

The water-absorbing polymer compound that can be used in the present invention absorbs water several hundred times to four times its own weight and swells, and does not dissolve in water and absorbs water even when pressure is applied to the swollen material. It means one that does not release water. Regarding the water-absorbing polymer compound as a means for achieving such a state, for example, starch-based compounds include starch-acrylonitrile graft polymer, starch-acrylic acid graft polymer, starch-styrenesulfonic acid graft polymer or starch- Examples of the vinyl sulfonic acid graft polymer, the cellulose-based, cellulose-acrylonitrile graft polymer, cellulose-styrene sulfonic acid graft polymer or carboxymethyl cellulose cross-linked polymer, polyvinyl alcohol-based, polyvinyl alcohol cross-linked Polymer or acrylic
Saponified vinyl acetate, polyethylene oxide-based or polyethylene glycol diacrylate cross-linked polymer, etc., and other polymers containing carboxyl group, carboxylic acid group, hydroxyl group or sulfonic acid group, polyvinyl porolidone-based cross-linked polymer, etc. Is mentioned.

The water-absorbing polymer compound which is sufficiently absorbing water is a water-absorbing polymer compound which absorbs water having a weight larger than its own weight and is sufficiently swollen. The water absorption amount is at least 5 parts by weight or more, and more preferably 1 part by weight per 1 part by weight of the water-absorbing polymer compound.
It is preferably 0 part by weight or more.

If a water-absorbing polymer compound in a state of not sufficiently absorbing water, that is, a compound that does not satisfy the above conditions is used, it becomes difficult to uniformly disperse the water-absorbing polymer compound in the organic solvent, and as a result, , It becomes impossible to obtain a uniform breathable hole.

Further, the smaller the particle size of the water-absorbing polymer compound that is sufficiently absorbing water, the easier it is to disperse in the organic solvent. Therefore, the particle size is preferably 60 μm or less, and more preferably 60 μm or less. You can

The amount of the water-absorbing polymer compound obtained in this manner, which is sufficiently absorbing water, is 10 to 30 parts by weight based on 100 parts by weight of the adhesive substance diluted with the above-mentioned hydrophobic organic solvent. Are preferred. The solid content concentration of the adhesive substance is 10 to 80% by weight, preferably 20 to 50% by weight.

A pressure-sensitive adhesive solution prepared by uniformly dispersing the pressure-sensitive adhesive substance diluted with the above-mentioned hydrophobic organic solvent and the water-absorbing polymer compound that has sufficiently absorbed water is applied to the substrate or release paper. Apply.

The coating machine that can be used in the present invention is not particularly limited as long as it can be used for coating an ordinary pressure-sensitive adhesive solution, but it is preferable that the paste thickness can be accurately adjusted and the productivity can be improved. Examples of coating machines that can be well coated include knife coaters, comma coaters, roll coaters and the like. Further, as a coating method, a method of directly applying the adhesive solution to the base material or a transfer method in which the adhesive solution is once applied to the release paper and dried to form an adhesive layer and then bonded to the base material, etc. You can choose.

The substrate which can be used in the present invention is not particularly limited, but if it is intended to be used as a pressure-sensitive adhesive tape or sheet having air permeability, it is preferable to use a substrate having air permeability. Needless to say, is preferable.

The air-permeable base material referred to herein has a property of allowing gas and liquid to pass therethrough, and is, for example, a woven cloth, a non-woven cloth, a knitted material, a lattice-shaped material or a sheet having a porous treatment. Alternatively, a film-shaped material can be used.

The conditions for initial drying used in the present invention are that the wind speed is 5 m / sec or less, preferably 2.5 m / sec or less. The wind speed referred to here means the wind speed when the air or nitrogen gas blown out from the nozzle of the drying furnace passes over the pressure-sensitive adhesive solution layer formed on the substrate or the release sheet.

As a condition for initial drying, the wind speed is 5 m.
If the water content in the water-absorbing polymer compound is more than 100 msec / sec, the water content in the water-absorbing polymer compound will evaporate in preference to the solvent in the adhesive solution even if a hydrophobic organic solvent having a boiling point of 100 to 110 ° C. is used. As a result, volumetric shrinkage of the water-absorbing polymer compound will occur,
It will not be possible to obtain sufficient ventilation holes.

For the same reason as above, as a condition of the initial drying, by drying the pressure-sensitive adhesive solution at a drying time of at least 50 seconds, the organic solvent content of the pressure-sensitive adhesive solution is given priority and the target of the initial drying is set. Minutes can be evaporated.

When the initial drying is performed under the above conditions, the evaporation of the organic solvent is preferentially promoted, and the water in the water-absorbing polymer compound, which is sufficiently absorbing water, is extremely evaporated and is not dispersed. It remains in a form of holding a volume of a similar size, so that pores having a sufficient size are generated in the formed pressure-sensitive adhesive layer.

However, the initial drying referred to in the present invention means the drying which is carried out in the initial stage after the pressure-sensitive adhesive solution is applied onto the substrate or the release sheet. In order to obtain the above-mentioned drying time, for example, when using an ordinary pressure-sensitive adhesive coating machine, adjust by taking into consideration the length of the initial drying zone of the drying furnace and the line speed at which the substrate is conveyed. Can be done.

The term "late drying" as used in the present invention refers to the drying after the completion of the initial drying, and the latter drying conditions are such that the drying speed is higher than the initial drying conditions, that is, the drying wind speed,
The drying time and the drying temperature are set to be larger than the initial drying conditions.

As the latter drying conditions, it is not necessary to suppress the wind speed, and it suffices to focus only on completely evaporating the water content in the water-absorbing polymer compound, but it does not cause foaming of the adhesive. In order to achieve the above, it is preferable to gradually increase the drying condition in several stages after the initial drying is completed until the latter drying is completed.

For the purpose of the present invention, a pressure-sensitive adhesive solution obtained by uniformly dispersing a water-absorbing polymer compound which has sufficiently absorbed water under the conditions detailed above is applied on a substrate or release paper and dried. A breathable pressure-sensitive adhesive tape can be formed by forming a porous pressure-sensitive adhesive layer having a certain air permeability, and further by placing the pressure-sensitive adhesive layer as it is on the substrate or by transferring it separately from the release paper to the substrate. Alternatively, the sheet can be manufactured.

The breathable pressure-sensitive adhesive tape or sheet produced by the production method of the present invention is suitable as a material for a medical tape which requires breathability when it is directly attached to the skin for use.

[0036]

According to the present invention, a water-absorbing polymer compound which is sufficiently absorbing water is diluted with a hydrophobic organic solvent having a boiling point of 100 to 110 ° C. to form a pressure-sensitive adhesive solution on a substrate or a release sheet. It was applied and dispersed in the pressure-sensitive adhesive by an initial drying under an initial drying condition of a wind speed of 5 m / sec or less and a drying time of at least 50 seconds or more, and a late drying condition in which a drying speed was higher than the initial drying condition. It is possible to evaporate the water in the water-absorbing polymer compound which has sufficiently absorbed water, after the organic solvent has evaporated. As a result, the water-absorbing polymer compound can be present in the pressure-sensitive adhesive layer without causing volume shrinkage during initial drying.

[0037]

EXAMPLES Examples of the present invention will be described below. As Example 1, a hydrophobic organic solvent having a boiling point of 110 ° C.,
Water-absorbent polymer absorbed into 100 parts by weight of a rubber-based pressure-sensitive adhesive (SPX glue, solid content concentration 30% by weight: Sekisui Chemical Co., Ltd.) diluted by dissolving it in the solvent using toluene. Compound (Sunweto IM-1000MP
S: 1 part by solid content, 10 parts of water) was uniformly dispersed by a dissolver to obtain a pressure-sensitive adhesive solution used in the present invention. In this example, initial drying was performed under the drying conditions of the drying zone 31 shown in FIG. 3 such that the air velocity was 2.5 m / sec, the residence time was 60 seconds, and the drying temperature was 100 ° C.

Further, the drying conditions of the intermediate drying zone 32 are as follows: wind speed, 10 m / sec, residence time: 60 sec, drying temperature: 100
The drying conditions for the latter stage drying zone 33 are as follows: air velocity, 20 m / sec, residence time 60 sec, drying temperature 120 ° C.
Then, by performing the latter stage drying, an adhesive layer having air-permeable holes was formed.

A polyester non-woven fabric (Sontara 8010, manufactured by DuPont) was used as the adhesive tape substrate, and the pressure-sensitive adhesive layer surface of the release paper on which the above-mentioned pressure-sensitive adhesive layer was formed was bonded to the non-woven fabric to obtain an adhesive tape.

Comparative Example 1 was prepared by using the same pressure-sensitive adhesive, base material and manufacturing conditions as in Example 1 except that the drying condition in the drying zone in Example was 10 m / sec and the initial drying was performed. .

Further, as Example 2, except that the number of parts by weight of water absorbed by the water-absorbing polymer compound was 100 parts by weight of 100 parts by weight of the rubber-based adhesive used in Example 1, which was doubled to 20 parts. It was created in exactly the same way.

Each of the pressure-sensitive adhesive tapes prepared by the above method was once wound up, and then cut into a size of 10 cm × 15 cm, and 300 ml of gas based on JIS standard P-8117.
The time it took for the slab to pass was measured with a galley densometer. Further, the 180 ° C peel adhesive strength was measured. The following table shows the results of air permeability with respect to the drying conditions and the type of organic solvent used for the adhesive solution.

[0043]

[Table 1]

As is clear from the results of comparison between Example 1 and Comparative Example 1 in the table, the air permeability is remarkable by using a hydrophobic organic solvent and suppressing the drying conditions for initial drying to a wind speed of 5 m / min or less. It can be seen that there is a difference in improvement.

[0045]

As described above in detail, according to the method for producing an air-permeable pressure-sensitive adhesive tape or sheet of the present invention, the water-absorbing polymer compound which has sufficiently absorbed water has a boiling point of 100 to 110 ° C. Apply the pressure-sensitive adhesive solution diluted with the hydrophobic organic solvent on the base material or release sheet, and wind speed 5 m.
/ Second or less and a drying time of at least 50 seconds or more and initial drying under the initial drying conditions and late drying under a later drying condition having a higher drying speed than the initial drying conditions to sufficiently absorb water dispersed in the adhesive solution. The water content in the water-absorbing polymer compound can be evaporated after the organic solvent is evaporated.

As a result, the volume of the prototype of the dispersed and sufficiently absorbed water-absorbing polymer compound is retained in the pressure-sensitive adhesive layer, and when the water content of the water-absorbing polymer compound is evaporated thereafter, the volume of the prototype is maintained. The pores corresponding to the amount are provided in the pressure-sensitive adhesive layer, and sufficient air permeability can be exhibited.

Further, a breathable pressure-sensitive adhesive tape or sheet can be obtained by forming the above-mentioned pressure-sensitive adhesive layer on a breathable substrate.

[Brief description of drawings]

FIG. 1 is a conceptual diagram showing a mechanism in which pores are generated by drying an adhesive solution.

FIG. 2 is a conceptual diagram showing a mechanism in which pores are generated by drying another adhesive solution.

FIG. 3 is a conceptual diagram showing a configuration of a drying furnace in a coating machine.

[Explanation of symbols]

 11 Adhesive Solution 12 Organic Solvent 13 Water Absorbing Polymer Compound 14 Pore Diameter 31 Early Drying Zone 32 Middle Drying Zone 33 Late Drying Zone 34 Nozzle 35 Air 36 Base Material or Release Sheet

Claims (1)

[Claims] 1. A pressure-sensitive adhesive solution obtained by diluting a pressure-sensitive adhesive substance and a water-absorbing polymer compound that has sufficiently absorbed water with a hydrophobic organic solvent having a boiling point of 100 to 110 ° C. on a substrate or a release sheet. Which has been applied to, and which has been made porous by the initial drying under the initial drying conditions of a wind speed of 5 m / sec or less and a drying time of at least 50 seconds or more, and the late drying conditions in which the drying speed is higher than the initial drying conditions. A method for producing a breathable pressure-sensitive adhesive tape or sheet, which comprises producing a layer and arranging the pressure-sensitive adhesive layer on a substrate.