JPH11323789A - Paper base and pressure sensitive adhesive sheet using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a paper base suitable for adhesive sheet not disturbing the hand cutting properties, excellent in line drawing and masking effect by using wood pulp and short fiber as the blending components and laminating several pieces of paper having different blend ratio. SOLUTION: This paper base having integrated layer structure is manufactured by paper making the second paper layer on the first paper layer having different blending ratio comprising the wood pulp and the short fiber such as polyvinyl alcohol fiber. A pressure sensitive adhesive sheet is obtained by impregnating an impregnating agent comprising a synthetic resin such rubber or acrylic resin or the like to the prescribed paper base in amount of 1 to 30 g/m<2> , preferably 5 to 20 g/m<2> as solid base, forming the pressure sensitive adhesive layer comprising a pressure sensitive adhesive such as natural rubber or an acrylic rubber on the surface of the first paper layer rich in the short fiber content, and making a top coat layer comprising silicone resin or the like to the surface of the prescribed second paper layer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

FIELD OF THE INVENTION The present invention relates to paper substrates, and more particularly, to paper substrates for supporting a secondary layer. Here, the "secondary layer" refers to a layer to be supported thereon by a paper base, in other words, a layer to be additionally or additionally formed on the paper base, for example, an adhesive layer , Various layers or films such as a paint layer and an ink layer. The present invention also relates to the use of such a paper substrate, particularly to an adhesive sheet using the paper substrate of the present invention. The pressure-sensitive adhesive sheet of the present invention, particularly when it is used as a masking material, can be torn in a desired shape without impairing the hand-cutting property, and can be properly masked. It can be peeled off cleanly in one operation without any residue. Note that, as described below, the term "hand tearability" means that when a paper substrate is torn by hand, it can be satisfactorily torn along a desired tear line. This means that there is no inconvenience that the lower layer is separated and only the upper layer is torn and the lower layer remains at least partially.

[0002]

2. Description of the Related Art Conventionally, various products have been proposed as pressure-sensitive adhesive sheets and are commercially available. Similarly, various types of substrates are known as a substrate for supporting the pressure-sensitive adhesive layer in such a pressure-sensitive adhesive sheet. Among many substrates,
When the pressure-sensitive adhesive sheet is adhered to an adherend for a certain purpose, and is peeled off at the end of the purpose, in general, a mixture of beaten wood pulp and synthetic staple fibers is added, and this is mixed with, for example, butyl rubber. A porous base material in which synthetic rubbers are uniformly impregnated and fixed is used. However, in this type of porous substrate, if the amount of impregnation of the synthetic rubber is too small, there is a problem that the strength of the substrate cannot withstand the adhesive strength at the time of peeling the pressure-sensitive adhesive sheet, and the material is torn or broken. On the contrary, if the impregnation amount is too large, the above-mentioned problem can be solved as a result of the improvement of the physical strength, but a new problem of floating of the tape occurs.

[0003] Japanese Patent No. 2589357 relates to a porous substrate invented in order to solve the above-mentioned problems of the conventional porous substrate for an adhesive sheet, and relates to a first surface layer side and a second surface layer. The fibrous substance density is different on the surface layer side of the above, and rubber and / or synthetic resin is added to the porous thin leaf material composed of the fibrous substance having the first surface layer side having a higher fibrous substance density than the second surface layer side It is impregnated, and the amount of impregnation is greater on the first surface layer side than on the second surface layer side. When this porous substrate is used for the pressure-sensitive adhesive sheet, the impregnation amount of the rubber and the like on the first surface layer is made larger than that on the second surface layer, so that the physical strength can be improved,
In addition, the rigidity is suppressed by the presence of the second surface layer, so that the adherence of the sheet to the adherend can be improved at the time of sticking the pressure-sensitive adhesive sheet, the sheet can be stuck without lifting, and the sheet is broken at the time of peeling. It has the effect of being able to be peeled off without any friction.

However, Japanese Patent No. 2,589,357
In the case of the porous base material described in the above item, the physical strength can be improved by increasing the amount of impregnation of the rubber or the like on the first surface side, and the tearing or breaking of the sheet can be prevented, but the strength is improved. It has the disadvantage that it is not possible to cut it easily by hand, in other words, the hand-cutting property is poor. It is a very important issue that the adhesive tape can be easily cut by hand from the viewpoints of sticking workability, handleability, and the like.

Further, in the porous base material described in Japanese Patent No. 2589357, a fiber having a higher fibrous substance density on the first surface layer side than on the second surface layer side of the porous thin leaf material constituting the same. Although it is formed from a fibrous material (i.e., kraft paper, crepe paper, Japanese paper, etc., and preferably a Japanese paper obtained by mixing beaten wood pulp and synthetic staple fibers), in such a fibrous material, wood pulp and synthetic short fiber are used. Some inconveniences cannot be avoided when trying to change the mixing ratio with fiber. For example, when a pressure-sensitive adhesive layer is applied to one side of a porous substrate and used as a pressure-sensitive adhesive sheet, if the mixing ratio of synthetic short fibers to wood pulp in the substrate is small, the obtained substrate is physically When the pressure-sensitive adhesive sheet is peeled off, the adhesive strength of the pressure-sensitive adhesive layer to the adherend is greater than the strength of the base material itself. Cannot be performed. Conversely, if the blending ratio of the synthetic short fibers is increased, the tear strength is also improved, so that the above-described problem of tearing or breaking in the pressure-sensitive adhesive sheet can be solved, but at the same time, the pressure-sensitive adhesive sheet is manually torn and cut. Therefore, the above-mentioned problem of a decrease in the "hand-cutting property", which means a decrease in the sticking workability, newly occurs. In addition, an increase in the blending rate of the synthetic short fibers causes an increase in the price of the obtained pressure-sensitive adhesive sheet.

[0006]

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned problems of the prior art, and to tear and cut a sheet when used as a base material for an adhesive sheet without impairing hand-cutting properties. An object of the present invention is to provide an improved base material which can be peeled off without using the pressure-sensitive adhesive sheet without tearing or breaking the sheet after use.

Still another object of the present invention is to provide an improved pressure-sensitive adhesive sheet which can be advantageously used particularly as a masking material.

[0008]

SUMMARY OF THE INVENTION The present invention, in one aspect, is a paper substrate for supporting a secondary layer, comprising two layers, a first paper layer and a second paper layer. The first paper layer and the second paper layer are made of wood pulp and short fiber, respectively, with different mixing ratios of short fiber to wood pulp. And a paper substrate characterized by the following.

[0009] Another object of the present invention is to provide a pressure-sensitive adhesive sheet comprising a paper base and a pressure-sensitive adhesive layer provided on one surface thereof, wherein the paper base comprises a first paper. A first layer and a second layer of paper, wherein the first layer and the second layer are made of wood pulp and short fibers, respectively. And the pressure-sensitive adhesive layer is provided on the surface of the first paper layer of the first and second paper layers where the mixing ratio of short fibers to the wood pulp is large. Provided is a pressure-sensitive adhesive sheet characterized in that:

[0010] In the pressure-sensitive adhesive sheet according to the present invention, preferably, the paper substrate constituting the pressure-sensitive adhesive sheet further contains rubber and / or synthetic resin impregnated into the entire paper substrate, Has a top coat layer on the surface of the second paper layer located on the side opposite to the paper layer. Preferably, such an adhesive sheet can be advantageously used particularly as a masking material.

[0011] In the paper base material according to the present invention, as described above, between the first paper layer and the second paper layer, a mixture of wood pulp and short fibers in short fibers constituting each paper layer. The difference is in the rate. Here, the "mixing rate" of the short fibers is the time when paper is made from wood pulp and short fibers, that is, after adding water to the beaten wood pulp to form a porridge, further adding short fibers. It refers to the mixing ratio of short fibers to wood pulp contained in the pulp liquid when the pulp liquid is prepared and the pulp liquid is further prepared by a paper machine. In the present invention, in the first and second paper layers constituting the paper base material, the first paper layer has a shorter fiber mixing ratio than the second paper layer which is another paper layer. There is another characteristic that is large.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described with reference to preferred embodiments. The paper substrate according to the invention is designed, in particular, to support a secondary layer, as described above, and thus also a two-layer lamination of a first paper layer and a second paper layer Having a structure, wherein the first paper layer and the second paper layer are manufactured from wood pulp and short fiber, respectively, at different mixing ratios of short fiber to wood pulp. Features.

The wood pulp used as the first blending component in each of the first and second paper layers can be a wood pulp generally used as a papermaking raw material in the field of papermaking. It is beaten wood pulp.
The short fibers used as the second blending component can be short fibers generally used as a papermaking raw material in the field of papermaking, and include various natural and synthetic short fibers. Examples of suitable staple fibers include, but are not limited to, those listed below, for example, polyvinyl alcohol fibers, such as those referred to by the generic name "vinylon", polyamide fibers, such as the tradename "DuPont" Nylon '' available polyamide fiber, polyester, polyethylene, polypropylene, polyurethane, polyvinyl chloride, polyvinylidene chloride, synthetic staple fiber such as polyacrylonitrile, for example, semi-synthetic staple fiber such as cellulose, regenerated staple fiber such as rayon, For example, natural short fibers such as bast, seed hair, leaf veins, fruits, animal hair, asbestos (asbestos), inorganic short fibers such as glass and metal, and the like. In particular, for the preparation of the paper substrate of the present invention, synthetic short fibers can be advantageously used as the second blending component. Preferably, the length of such short fibers is usually in the range of about 3 to 20 mm.

In the first and second paper layers formed of wood pulp and short fibers, respectively, the mixing ratio of short fibers to wood pulp is usually preferably about 50% or less. Further, in the paper base material of the present invention, the mixing ratio of each of these two paper layers is not the same. The difference in the mixing ratio between the two is not particularly limited, and may be a small difference of about several percent, or about 20 to 30% otherwise.
Alternatively, the difference may be larger. But,
If the difference between the two is more than 50%, the hand-cutting property may be deteriorated. Therefore, it is generally preferable that the difference be less than 50%. In addition, when the paper base material of the present invention is used for producing a pressure-sensitive adhesive sheet for masking purposes, the resulting pressure-sensitive adhesive sheet may be cut off at the time of peeling (also referred to as “slippering”) after being applied to an adherend. And the difference in the mixing ratio between the second paper layer and the second paper layer has a great effect. For example, even if the mixing ratio is greatly increased, if the mixing ratio is reversed between the first layer and the second layer, the slippering generally deteriorates. In the past, slippering has been prevented by making the paper uniformly regardless of the front and back, and increasing the mixing ratio of the whole paper.

In the present invention, it is preferable that such a difference in the mixing ratio between the first and second paper layers is produced, preferably at the stage of preparation of each paper layer. This is done by recognizing the difference in the mixing ratio of wood pulp and short fibers. When the paper substrate of the present invention is used particularly for supporting an adhesive layer, that is,
In the case where the pressure-sensitive adhesive sheet is produced using the paper base material of the present invention, as will be described in detail below, the first and second paper layers having the larger mixing ratio of the short fibers are used in the first and second paper layers. 1
Preferably, an adhesive layer is provided on the surface of the first paper layer.

The above-mentioned first and second paper layers are laminated to form a two-layer laminated structure, which is usually performed by using an apparatus used for cardboard papermaking, for example, a multilayer paper former. According to the papermaking method used, the first and second paper layers may be separately made and then integrally formed to such an extent that the interface between the two layers cannot be identified. In producing the paper base material of the present invention in this manner, the basis weight (g / g) of the first and second paper layers is used.
m ² ) is preferably adjusted so that the basis weight ratio is 95: 5 to 5:95. The paper base material whose basis weight ratio has been adjusted in this manner has, in the first paper layer, increased physical strength, for example, tear strength, break strength, interlayer strength, and the like.
Can be played.

The paper substrate according to the invention can advantageously be used for producing products supporting various additional layers, in particular for producing pressure-sensitive adhesive sheets. The adhesive sheet is usually made of the paper base material of the present invention and its 1
And a pressure-sensitive adhesive layer provided on one surface of the first paper layer. Preferably, the pressure-sensitive adhesive layer is formed on the surface of the first paper layer of the first and second paper layers in which the mixing ratio of short fibers is large. Is provided. The thickness of the paper substrate in the pressure-sensitive adhesive sheet and the thickness of the pressure-sensitive adhesive layer thereon, the type of the pressure-sensitive adhesive, etc., are those which are generally known in the art, or depending on the final use. It can be selected or changed and applied. Further, the pressure-sensitive adhesive sheet of the present invention, if necessary, may have another layer on the same side as the pressure-sensitive adhesive layer or on the side opposite to the pressure-sensitive adhesive layer.
For example, a release layer can be used.

The pressure-sensitive adhesive sheet of the present invention can be advantageously used as a masking material particularly in a painting operation or the like. In addition, for such a use, the paper base material is further impregnated with an aqueous dispersion impregnating agent impregnated in the entire paper base material, preferably a rubber or synthetic resin or a combination thereof as a main component. And it is advantageous to have a top coat layer on the surface of the second paper layer opposite to the first paper layer.

The rubber which can be advantageously used as an aqueous dispersion impregnating agent in the production of the pressure-sensitive adhesive sheet of the present invention is, for example, natural rubber, synthetic isoprene rubber, butyl rubber, styrene butadiene rubber, acrylic rubber, etc. Synthetic resins that can also be used to advantage are, for example, acrylic resins. These impregnating agents generally have a preferable impregnation amount of 1 based on the solid content.
Range to 30 g / m ^2, more preferably from 5 to 20 g / m ^2. When the content of the impregnating agent in the paper base is less than 1 g / m ² , the binding of the fibers becomes poor, and the paper base cannot be used as a base for the adhesive sheet for masking. Further, the paper base material may be broken and remain between the first and second paper layers, and may not be removed again. Conversely, when the impregnant content is 30
If it exceeds g / m ² , the rigidity of the substrate becomes too strong.
The tear strength is reduced and the effect of adding short fibers is lost, that is, a resin film mainly composed of paper is obtained. The application of such an impregnating agent to a paper substrate is
It can be performed according to various methods, preferably,
Examples of the method include a coating method, a size press method, and a dipping method.

The topcoat layer to be applied to the surface of the second paper layer can be formed from various topcoat agents. Preferred topcoat agents are, for example, polyvinyl acetate emulsions and polyacryl emulsions. For coating, various coating methods can be advantageously used. Manufacturing a pressure-sensitive adhesive sheet for the purpose of masking using a paper substrate manufactured by laminating the first and second paper layers as described above and further impregnating rubber and / or synthetic resin, Although it can be carried out according to various procedures, preferably, the surface of the second paper layer of the paper base material is coated with a top coat agent as described above to form a top coat layer, and the top coat layer is further formed on the top coat layer. By providing a layer of a weakly adhesive material such as a silicone resin or a long-chain alkyl ester resin as a back surface treatment agent. Next, among the surfaces of the paper base material, as described above, a common adhesive such as a natural rubber type or an acrylic rubber type is applied to the surface of the first paper layer (the surface not in contact with the second paper layer). An agent can be applied to form an adhesive layer.

[0021]

EXAMPLES The present invention will be further described with reference to examples. Example 1 Preparation of paper substrate: 20% by weight based on beaten wood pulp
Polyvinyl alcohol (vinylon) in the amount (based on the total amount)
Short fibers (length: about 3 to 20 mm, manufactured by Kuraray Co., Ltd.) are mixed to prepare a porridge pulp solution, and the pulp solution is further pulp-pulled to a basis weight of 20 g / m ² by a paper machine. Was prepared. Further, the same method as described above was repeated, except that vinylon short fibers were not mixed. Basis weight 20g
/ M ² of the second paper layer was obtained. Next, the first and second paper layers are integrally formed by a paper making method using a multi-layer forming former so that the interface between the two paper layers cannot be distinguished, and the total tsubo having a Japanese paper-like texture is obtained. 40 g / m ²
Was prepared.

The whole of the obtained paper base material was impregnated with an acrylic resin emulsion as an impregnating agent by a dipping method under the condition that the solid content impregnation amount was 5 g / m ² . In order to evaluate the hand-cutting properties of the acrylic resin-impregnated paper base material thus obtained, the tear strength of the paper base material in the longitudinal and transverse directions was measured according to the procedure specified in JIS P8116.
The measurement results as shown in Table 1 below were obtained. Preparation of pressure-sensitive adhesive tape: Acrylic pressure-sensitive pressure-sensitive adhesive, masking acrylic adhesive (trade name, MT) on the surface of the first paper layer (mixed with vinylon short fibers) of the acrylic resin-impregnated paper base material prepared in the above process TACK5268ER, manufactured by Mitsui Chemicals, Inc.) to form an adhesive layer having a thickness of 30 μm. Further, a polyvinyl acetate emulsion and Sumikaflex (registered trademark, manufactured by Sumitomo Chemical Co., Ltd.) were coated on the surface of the second paper layer not mixed with vinylon short fibers at a coating amount of 3 g / m ² and dried. Further, a long-chain alkyl acrylic resin (as an easy peeling agent) was applied thereon at a coating amount of 0.05 g / m ² and dried again. An adhesive tape having an adhesive layer on one side of a paper substrate was obtained.

In order to evaluate the tear resistance of the obtained pressure-sensitive adhesive tape, 5 was prepared according to the procedure specified in JIS Z2307.
A piece of aluminum panel (width 30 mm x length 100 mm) was prepared, and an adhesive tape shredded to a width of 15 mm was attached to each aluminum panel, and a load of 2 was applied on the adhesive tape.
A kg roller was reciprocated once at 300 mm / min. After the pressure-sensitive adhesive tape was completely adhered to the aluminum panel by pressing with a roller, it was left at room temperature for 16 hours. After the specified standing time is completed, remove the adhesive tape from the aluminum panel,
It was quickly peeled off by hand in the 180 ° peel direction, and it was visually confirmed how many of the adhesive tapes among the adhesive tapes pressed on the five aluminum panels were torn. The results (0/5, ie, no tearing of the pressure-sensitive adhesive tape at all) relating to the tear resistance as shown in Table 1 below were obtained. Example 2 The procedure described in Example 1 was repeated. In this example, as shown in Table 1 below, the mixing ratio of vinylon short fibers in the first paper layer was set to 20% in order to evaluate the effect of the change in the mixing ratio on the hand-cutting property and the tear resistance. % To 30
Weight percent. The first and second paper layers are integrally formed by a papermaking method using a multilayer paper former so that the interface between the two paper layers cannot be identified, and a total basis weight of 40 g having a Japanese paper-like texture. / M ² of paper substrate was prepared.
By the subsequent treatment, the same acrylic resin-impregnated paper base material and pressure-sensitive adhesive tape as those obtained in Example 1 were obtained.

When the hand-cutting property of the obtained acrylic resin-impregnated paper substrate and the tear resistance of the pressure-sensitive adhesive tape were evaluated according to the method described in Example 1, the results shown in Table 1 below were obtained. Was. Example 3 The procedure described in Example 1 was repeated. In this example, as shown in Table 1 below, the mixing ratio of vinylon short fibers in the first paper layer was set to 20% in order to evaluate the effect of the change in the mixing ratio on the hand-cutting property and the tear resistance. %, But in the second paper layer, the blending ratio of vinylon short fibers was set to 0% by weight, but the vinylon short fibers were blended according to the method described in Example 1 to obtain a blending ratio of 1%.
0% by weight. The first and second paper layers are integrally formed by a papermaking method using a multilayer paper former so that the interface between the two paper layers cannot be identified, and a total basis weight of 40 g having a Japanese paper-like texture. / M ² of paper substrate was prepared. By the subsequent treatment, the same acrylic resin-impregnated paper base material and pressure-sensitive adhesive tape as those obtained in Example 1 were obtained.

When the hand-cutting property of the obtained acrylic resin-impregnated paper substrate and the tear resistance of the pressure-sensitive adhesive tape were evaluated according to the method described in Example 1, the results shown in Table 1 below were obtained. Was. Example 4 The procedure described in Example 1 was repeated. In this example, as shown in Table 1 below, the mixing ratio of vinylon short fibers in the first paper layer was set to 20% in order to evaluate the effect of the change in the mixing ratio on the hand-cutting property and the tear resistance. % To 30
% By weight, and in the second paper layer, the blending rate of vinylon short fibers was set to 0% by weight. Then, vinylon short fibers were blended according to the method described in Example 1, and the blending rate was 10%. % By weight. The first and second paper layers are integrally formed by a papermaking method using a multilayer paper former so that the interface between the two paper layers cannot be identified, and a total basis weight of 40 g having a Japanese paper-like texture. / M ² of paper substrate was prepared. By the subsequent treatment, the same acrylic resin-impregnated paper base material and pressure-sensitive adhesive tape as those obtained in Example 1 were obtained.

When the hand-cutting property of the obtained acrylic resin-impregnated paper base material and the tear resistance of the pressure-sensitive adhesive tape were evaluated in accordance with the method described in Example 1 above, the results shown in Table 1 below were obtained. Was. Comparative Example 1-1 The procedure described in Example 1 was repeated. However, in this example, for comparison, a single-sheet paper substrate was prepared in place of the paper substrate having the two-layer laminated structure. That is, 20% by weight of vinylon (manufactured by Kuraray Co., Ltd.) is mixed with the beaten wood pulp to prepare a porridge pulp solution, and the pulp solution is adjusted to a basis weight of 20 g / m ² by a paper machine. I drew it. A one-sheet paper substrate having a total basis weight of 40 g / m ² having a Japanese paper-like texture was obtained. Using this paper base material, an acrylic resin-impregnated paper base material and an adhesive tape were prepared in the same manner as in Example 1.

The obtained acrylic resin-impregnated paper base material was evaluated for hand-cutting property and tear resistance of the pressure-sensitive adhesive tape according to the method described in Example 1 above. The results shown in Table 1 below were obtained. Was. Comparative Example 1-2 The method described in Comparative Example 1-1 was repeated. In this example, as shown in Table 1 below, the mixing ratio of vinylon short fibers in the paper base material was increased from 20% by weight to evaluate the effect of the change in the mixing ratio on the hand-cutting property and the tear resistance. 3
0% by weight. Total basis weight 4 with Japanese paper texture
A single-sheet paper substrate of 0 g / m ² was obtained. By the subsequent treatment, the same acrylic resin-impregnated paper substrate and pressure-sensitive adhesive tape as those obtained in Comparative Example 1-1 were obtained.

The hand-cutting property of the obtained acrylic resin-impregnated paper base material and the tear resistance of the pressure-sensitive adhesive tape were evaluated according to the method described in Example 1 above, and the results shown in Table 1 below were obtained. Was. Comparative Example 2-1 The procedure described in Example 1 was repeated. However, in this example, for comparison, in the paper base material having the two-layered laminated structure, the mixing ratio of the vinylon short fibers was higher in the second paper layer than in the first paper layer. Changed to be big. That is, a gruel-like pulp solution is prepared from beaten wood pulp, and the pulp solution is further processed with a paper machine at a basis weight of 20 g / g.
The first paper layer was prepared so as to have a m ² of not mixed with vinylon short fibers. Furthermore, a pulp pulp liquid is prepared by mixing polyvinyl alcohol (vinylon) staple fibers (length: about 3 to 20 mm, manufactured by Kuraray) in an amount of 20% by weight (based on the total amount) with the beaten wood pulp. Then, this pulp solution was made with a paper machine so as to have a basis weight of 20 g / m ² to prepare a second paper layer. Next, the first and second paper layers were separated by a papermaking method using a multilayer paper former.
A paper base material having a total basis weight of 40 g / m ² having a Japanese paper-like texture was prepared by integrally laminating the paper layers so that the interface between the two paper layers could not be identified.

Next, an acrylic resin emulsion as an impregnating agent was impregnated into the entirety of the obtained paper base material at an impregnation amount of 5%.
The impregnation was carried out by an immersion method under the condition of g / m ² . The hand-cutting properties of the thus-obtained acrylic resin-impregnated paper substrate were evaluated according to the method described in Example 1 above, and the results shown in Table 1 below were obtained. An acrylic pressure-sensitive adhesive was applied to the surface of the first paper layer, not mixed with vinylon short fibers, of the acrylic resin-impregnated paper base material prepared in the above-described step to form a 30 μm-thick pressure-sensitive adhesive layer. . Further, the surface of the second paper layer (mixed with vinylon short fibers) of the acrylic resin-impregnated paper substrate is coated with a polyvinyl acetate emulsion on the surface of the second paper layer at a coating amount of 3 g / m ² and dried. Then, a long-chain alkyl acrylic resin was further applied thereon at a coating amount of 0.05 g / m ² and dried again. An adhesive tape having an adhesive layer on one side of a paper substrate was obtained. When the tear resistance of the obtained pressure-sensitive adhesive tape was evaluated in accordance with the method described in Example 1, the results shown in Table 1 below were obtained. Comparative Example 2-2 The procedure described in Comparative Example 2-1 was repeated. In this example, to evaluate the effect of the change in the mixing rate on the hand-cutting property and the tear resistance, a second sheet was prepared as described in Table 1 below.
The mixing ratio of vinylon short fibers in the paper layer of was increased from 20% by weight to 30% by weight. The first and second paper layers are integrally formed by a papermaking method using a multilayer paper former so that the interface between the two paper layers cannot be identified, and a total basis weight of 40 g having a Japanese paper-like texture. / M ² of paper substrate was prepared. By the subsequent treatment, the same acrylic resin-impregnated paper substrate and pressure-sensitive adhesive tape as those obtained in Comparative Example 2-1 were obtained.

The hand-cutting property of the obtained acrylic resin-impregnated paper base material and the tear resistance of the pressure-sensitive adhesive tape were evaluated according to the method described in Example 1 above, and the results shown in Table 1 below were obtained. Was. Comparative Example 2-3 The method described in Comparative Example 2-1 was repeated. In this example, to evaluate the effect of the change in the mixing rate on the hand-cutting property and the tear resistance, a second sheet was prepared as described in Table 1 below.
The blending ratio of vinylon short fibers in the paper layer of Example 1 was maintained at 20% by weight, but the blending ratio of vinylon short fibers in the first paper layer was 0% by weight. Mixed vinylon short fibers according to the described method,
The mixing rate was 10% by weight. The first and second paper layers are integrally formed by a papermaking method using a multilayer paper former so that the interface between the two paper layers cannot be identified.
A paper substrate having a total basis weight of 40 g / m ² having a Japanese paper-like texture was prepared. By the subsequent treatment, the same acrylic resin-impregnated paper substrate and pressure-sensitive adhesive tape as those obtained in Comparative Example 2-1 were obtained.

The hand-cutting properties of the obtained acrylic resin-impregnated paper base and the tear resistance of the pressure-sensitive adhesive tape were evaluated according to the method described in Example 1 above, and the results shown in Table 1 below were obtained. Was. Comparative Example 2-4 The procedure described in Comparative Example 2-1 was repeated. In this example, to evaluate the effect of the change in the mixing rate on the hand-cutting property and the tear resistance, a second sheet was prepared as described in Table 1 below.
Comparative Example 2 in which the blending ratio of vinylon short fibers in the paper layer was increased from 20% by weight to 30% by weight and the blending ratio of vinylon short fibers in the first paper layer was 0% by weight. According to the method described in -1, vinylon short fibers were mixed, and the mixing rate was 10% by weight. The first and second paper layers are formed by a papermaking method using a multilayer paper former.
A paper base material having a total basis weight of 40 g / m ² having a Japanese paper-like texture was prepared by integrally laminating the two paper layers so that the interface between the two paper layers could not be identified. By the subsequent processing, Comparative Example 2-
The same acrylic resin-impregnated paper substrate and pressure-sensitive adhesive tape as those obtained in 1 were obtained.

When the obtained acrylic resin-impregnated paper substrate was evaluated for the hand-cutting property and the tear resistance of the pressure-sensitive adhesive tape according to the method described in Example 1, the results shown in Table 1 below were obtained. Was. Comparative Example 2-5 The method described in Comparative Example 2-1 was repeated. In this example, to evaluate the effect of the change in the mixing rate on the hand-cutting property and the tear resistance, a second sheet was prepared as described in Table 1 below.
Comparative Example 2 in which the blending ratio of vinylon short fibers in the paper layer was increased from 20% by weight to 30% by weight and the blending ratio of vinylon short fibers in the first paper layer was 0% by weight. According to the method described in -1, vinylon short fibers were mixed, and the mixing ratio was set to 20% by weight. The first and second paper layers are formed by a papermaking method using a multilayer paper former.
A paper base material having a total basis weight of 40 g / m ² having a Japanese paper-like texture was prepared by integrally laminating the two paper layers so that the interface between the two paper layers could not be identified. By the subsequent processing, Comparative Example 2-
The same acrylic resin-impregnated paper substrate and pressure-sensitive adhesive tape as those obtained in 1 were obtained.

The hand-cutting property of the obtained acrylic resin-impregnated paper base and the tear resistance of the pressure-sensitive adhesive tape were evaluated according to the method described in Example 1 above, and the results shown in Table 1 below were obtained. Was.

[0034]

[Table 1]

As can be understood from the results shown in Table 1 above, the tear resistance is good as seen in the examples.
An acrylic resin-impregnated paper base material and an adhesive tape with favorable lateral tear strength as evaluated for hand-cutting properties can be obtained, but when one sheet is made as in Comparative Example 1, the tear resistance is good, but The tear strength is too high, and the hand-cutting property deteriorates. Further, when the first paper layer and the second paper layer are reversed as in Comparative Example 2, the hand-cutting property is good, but the tear resistance is poor. Although the tear resistance is good as in Comparative Example 2-5, the transverse tear strength is too high and the hand-cutting property is poor. Example 5 In this example, it was evaluated whether or not the impregnation amount of the water-dispersed impregnating agent affects the strength of the obtained tape in the production of the pressure-sensitive adhesive tape. In this example, for convenience of the evaluation test, a single-sheet paper base was used in place of the paper base having a two-layer bonding structure. That is, 10% by weight of vinylon (manufactured by Kuraray Co., Ltd.) is mixed with the beaten wood pulp to prepare a mushroom pulp solution, and the pulp solution is further adjusted to a basis weight of 30 g / m ² by a paper machine. I drew it. A one-sheet paper substrate having a total basis weight of 40 g / m ² having a Japanese paper-like texture was obtained.

Subsequently, styrene-butadiene rubber as an impregnating agent was impregnated into the whole of the obtained paper base material in an amount of 0.5, 1, 5, 1 as shown in Table 2 below.
The impregnation was carried out by a dipping method under the conditions of 5, 30 and 45 g / m ² . The rubber-impregnated paper substrate thus obtained was measured for tensile strength in the longitudinal direction, elongation, and tear strength in the transverse and longitudinal directions according to the method described in Example 1. The measurement results as shown in Table 2 below were obtained.

Subsequently, a slipper test was performed in accordance with the evaluation of the tear resistance described in Example 1 to determine whether the tape was cut when the adhesive tape was peeled from the aluminum panel. "In two stages. Evaluation results as shown in Table 2 below were obtained.

[0038]

[Table 2]

As can be understood from the results shown in Table 2 above, if the impregnation amount is 0.5 g / m ² , the adhesive tape is broken between the layers of the base material due to insufficient binding of the fibers. It cannot be removed cleanly. On the other hand, when the impregnation amount is 45 g / m ² , the tear strength is extremely reduced, and the adhesive tape is cut, so that it cannot be peeled off cleanly. When the impregnation amount is 1 to 30 g / m ² , the fiber bundling is sufficient, the tear strength is not extremely reduced, and the adhesive tape can be peeled off without cutting. Example 6 The procedure described in Example 1 was repeated. In this example, Table 3 below was used to evaluate the effect of the average blending ratio (the average of the blending ratio of the first paper layer and the blending ratio of the second paper layer) on the hand-cutting property and the tear resistance. As described, the mixing ratio of vinylon short fibers in the first paper layer was reduced from 20% by weight to 10% by weight, and the average mixing ratio was 5% by weight. The first and second paper layers are integrally formed by a papermaking method using a multilayer paper former so that the interface between the two paper layers cannot be identified, and a total basis weight of 40 g having a Japanese paper-like texture.
/ M ² of paper substrate was prepared. By the subsequent treatment, the same acrylic resin-impregnated paper base material and pressure-sensitive adhesive tape as those obtained in Example 1 were obtained.

When the hand-cutting property of the obtained acrylic resin-impregnated paper substrate and the tear resistance of the pressure-sensitive adhesive tape were evaluated in accordance with the method described in Example 1 above, the results shown in Table 3 below were obtained. Was. In Table 3 below, the results of Example 1 are also shown for reference. Comparative Example 1-3 The method described in Comparative Example 1-1 was repeated. In this example, Table 3 below was used to evaluate the effect of the average blending ratio (the average of the blending ratio of the first paper layer and the blending ratio of the second paper layer) on the hand-cutting property and the tear resistance. As described, the blending ratio of vinylon short fibers in the first paper layer is from 20% by weight to 5%.
Weight percent. Total basis weight 40 with Japanese paper texture
g / m ² of a one-sheet paper substrate was obtained. By the subsequent treatment, the same acrylic resin-impregnated paper substrate and pressure-sensitive adhesive tape as those obtained in Comparative Example 1-1 were obtained.

When the hand-cutting property of the obtained acrylic resin-impregnated paper substrate and the tear resistance of the pressure-sensitive adhesive tape were evaluated according to the method described in Example 1, the results shown in Table 3 below were obtained. Was. Comparative Example 1-4 The method described in Comparative Example 1-1 was repeated. In this example, Table 3 below was used to evaluate the effect of the average blending ratio (the average of the blending ratio of the first paper layer and the blending ratio of the second paper layer) on the hand-cutting property and the tear resistance. As described, the blending ratio of vinylon short fibers in the first paper layer is from 20% by weight to 1%.
0% by weight. Total basis weight 4 with Japanese paper texture
A single-sheet paper substrate of 0 g / m ² was obtained. By the subsequent treatment, the same acrylic resin-impregnated paper substrate and pressure-sensitive adhesive tape as those obtained in Comparative Example 1-1 were obtained.

The hand-cutting property of the obtained acrylic resin-impregnated paper substrate and the tear resistance of the pressure-sensitive adhesive tape were evaluated according to the method described in Example 1 above, and the results shown in Table 3 below were obtained. Was.

[0043]

[Table 3]

As can be understood from the results shown in Table 3 above, the impregnated paper base material having good tear resistance and good transverse tear strength evaluated as hand-cutting property as shown in Examples. Although an adhesive tape can be obtained, even if the vinylon blending ratio of the entire paper is the same as that of the example as in the comparative example, the cut resistance is deteriorated if only one sheet is made.

[0045]

As described above, according to the present invention, especially when used as a base material of an adhesive sheet, it can be attached to an adherend without lifting, and can be applied to a masking area. When cutting with a pressure-sensitive adhesive sheet, the sheet can be torn and cut without losing its hand-cutting properties.As a result, a good line-out effect and a masking effect can be achieved. Provided is an improved paper substrate that can be easily and cleanly peeled off without causing any problem. Further, according to the present invention, there are provided a paper substrate and a pressure-sensitive adhesive sheet which can be advantageously applied to the production of a pressure-sensitive adhesive tape for masking.

Claims (4)

[Claims] 1. A paper base material for supporting a secondary layer, wherein the paper base material has a two-layer lamination structure of a first paper layer and a second paper layer. And the second paper layer is manufactured from wood pulp and short fiber, respectively, with a different blending ratio of short fiber to wood pulp. 2. A pressure-sensitive adhesive sheet comprising a paper base and a pressure-sensitive adhesive layer provided on one surface thereof, wherein the paper base comprises a first paper layer and a second paper layer. The first paper layer and the second paper layer are manufactured from wood pulp and short fibers, respectively, at different mixing ratios of short fibers to wood pulp. And a pressure-sensitive adhesive sheet, wherein the pressure-sensitive adhesive layer is provided on the surface of the first paper layer of the first and second paper layers in which the mixing ratio of the short fibers is large. 3. The paper base further contains rubber and / or synthetic resin impregnated in the whole of the paper base, and a paper base located on the side opposite to the first paper layer. 3. The pressure-sensitive adhesive sheet according to claim 2, wherein the pressure-sensitive adhesive sheet has a topcoat layer on the surface of the paper layer. 4. The pressure-sensitive adhesive sheet according to claim 3, which is used as a masking material.