JP2002054090A - Releasing paper and method for producing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing a releasing paper having high safety at a low cost, and also an inexpensive both sides-releasing paper. SOLUTION: This method for producing the releasing paper is characterized by applying a curable silicone on the surface of a paper base material having a high bulk density and curing the silicone before it penetrates to the reverse side of the above paper base material for forming a releasing layer, and the releasing paper produced by the above method is also provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a release paper and a method for producing the same.

[0002]

2. Description of the Related Art Release paper is one in which a release agent such as silicone or a solution thereof is applied to the surface of a paper base material to impart a release property, and is used for adhesive sheets such as labels, seals, stickers, and wallpaper. It is used for protecting the adhesive layer surface.

[0003] In the production of conventional release paper, it is common to apply a solution in which silicone is dissolved in an organic solvent onto a paper base material provided with a barrier layer for preventing penetration of silicone. The barrier layer is provided in order to prevent the problem that the silicone solution permeates the paper base material and a sufficient release agent layer is not formed on the base material surface.

For example, in the case of the most common polyethylene laminate type as an example of a barrier layer, as shown in FIG. 3, a polyolefin resin is laminated on the surface of a paper 21 as a base material to prevent the penetration of a silicone solution. After the barrier layer 23 is provided, a silicone solution is applied on the barrier layer 23, and then the solvent is volatilized to form the release agent layer 22. However, in a process including lamination, the production cost is considerably high in the case of small-lot production. In addition, composite paper containing polyethylene laminate,
In the recycled paper process, polyethylene flakes remain as contaminants, which hinders waste paper recycling.

[0005] Release paper using glassine paper as a base material is also widely used. Glassine paper has a beating degree of 230 to 35
A paper made from chemical pulp that has been subjected to advanced beating processing of about 0 ml CSF (Canadian Standard Freeness) and then densified by compression using finishing equipment such as a super calender. In consideration of this, a sufficient silicone layer can be formed. However, glassine paper is expensive as a paper material because it requires a high-level beating process and a process such as a super calender in the manufacturing process.

[0006] In recent years, in consideration of safety in working environments and the like, it has been required to use solventless silicone instead of conventional solution silicone. Although it is relatively easy to eliminate the solvent in the laminate type, the above-mentioned problems associated with the laminate remain. On the other hand, when solventless silicone is applied to conventional glassine paper, it is difficult to provide a silicone release agent layer with a sufficient thickness on the whole. It has also been attempted to improve the coatability of solventless silicone by providing a polyvinyl alcohol-based resin coating on the glassine paper surface, but such treatment causes problems such as curl and dimensional change due to increased hygroscopicity. . Although a method of solving this kind of problem by using glassine paper subjected to polyethylene lamination as a release base paper has also been proposed (for example, JP-A-10-140104), in this case, a method similar to a laminate type release paper is used. Problem arises.

For the purpose of preventing adhesion between various substrates such as paper materials, synthetic films, knitted fabrics and metal foils, a double-sided release paper having release properties on both sides as well as on one side is required. There are cases. In the laminate type, double-sided release paper can be easily produced only by providing a laminate layer and a release agent layer on both sides, but as described above, there are problems associated with lamination. Also, the production cost is large because the laminate is provided on both sides. When producing a double-sided release paper using glassine paper as a base material, a curable silicone composition is applied to one side and cured to form a first release agent layer, and then the curable silicone composition is coated on the opposite side. Is applied and cured to form a second release agent layer. However, when the first release agent layer is formed, since the release agent has reached the back surface, the second release agent layer formed thereon is formed. (2) There was a problem that the release agent layer had low adhesion to the paper base material and easily fell off (for example, see JP-A-10-158519).

[0008] Instead of a laminate layer, a layer of hot melt resin or the like may be used as a barrier layer (Japanese Patent Application Laid-Open No. 11-288222), or a special undercoat layer containing an acrylic emulsion polymer may be used as a label base paper by on-machine coating (ie, By applying to a paper material in a semi-dry state in a paper machine (JP-A-11-291407), or by dissolving a silicone resin in a supercritical fluid (JP-A-5-68936).
No.) and a method of forming a silicone thin layer have also been proposed, but in each case, the process becomes complicated and special equipment and paper are required, leading to an increase in cost.

[0009]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems in a conventional method for producing a release paper, and a method for producing a release paper which can be produced at low cost and has excellent recyclability. In particular, it is an object of the present invention to provide a method for producing a release paper in which solventless silicone can be used. Another object of the present invention is to provide an efficient method for producing double-sided release paper.

[0010]

Means for Solving the Problems The present inventor has proposed a release paper
Considering a different structure from the conventional release agent layer / barrier layer / paper base material structure, using solventless silicone with high tension and high smoothness paper as the base material and a specific range of viscosity. If the coating is cured within a short time after coating, no lamination is required, and expensive or special paper is not used.
The present inventors have found that a release paper having good properties can be obtained, and that the method is also useful as a method for producing a double-sided release paper, thereby completing the present invention. That is, the present invention provides the following release paper and a method for producing the same.

(1) A curable silicone is applied to the surface of a paper substrate having a high tension, and cured before the silicone penetrates to the back surface of the paper substrate to form a release layer. Release paper manufacturing method. (2) The method for producing a release paper according to the item 1, wherein the curable silicone is used without a solvent. (3) Tension 0.75 g / cm ³ or more, Beck smoothness (JIS P
8119) The method for producing a release paper according to the above item 2, wherein a paper base material of 40 seconds or more is used. (4) The method for producing a release paper according to the above (3), wherein a paper base material having an air permeability (JIS P8117) of 30 seconds or more is used. (5) The method for producing a release paper according to (4), wherein the paper substrate is selected from high-quality paper, lightweight coated paper, and coated paper. (6) The method according to any one of the above 1 to 5, wherein a solvent-free curable silicone having a viscosity of 300 cP or more is applied, and a curing treatment is performed within 5 seconds after the application to cure the silicone without penetrating to the back surface of the paper substrate. A method for producing the release paper according to the above. (7) The coating amount of the curable silicone is 0.5 to ² g / cm ^2.
7. The method for producing a release paper according to the above item 6, wherein (8) The method for producing a release paper according to any one of (1) to (7) above, wherein the curable silicone is a thermosetting silicone. (9) 100-150 curing steps after silicone coating
9. The method for producing a release paper according to the above item 8, wherein the method is carried out by maintaining the temperature in a range of 1 ° C. for 1 to 30 seconds. (10) The method for producing a release paper according to any one of (1) to (6) above, wherein the curable silicone is an ultraviolet curable silicone. (11) A curable silicone is applied to one surface of a paper substrate having a high tension, and cured before the silicone penetrates to the other surface of the paper substrate, and a first release is performed on one surface of the paper substrate. A method for producing a double-sided release paper, comprising forming a layer, forming a second release layer by applying and curing a curable silicone on the other surface. (12) A release paper obtained by any one of the above methods 1 to 10. (13) A double-sided release paper obtained by the method according to the above (11).

[0012]

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a method of applying a curable silicone to the surface of a high-stress paper substrate without providing a barrier layer, and curing the silicone before the silicone penetrates to the back surface of the paper substrate. Thus, a method for producing a release paper for forming a release layer on the surface of a substrate, and a release paper produced by the method. Hereinafter, the structure of the release paper of the present invention and the method for producing the same will be described in detail.

(A) Release Paper As shown in the cross-sectional view of FIG. 1, the release paper of the present invention has a release agent layer 2a on one surface (surface) of a paper substrate 1 having a high tensile strength. Part of the mold agent has a release agent permeable layer 2b in the base material within a range not reaching the back surface of the paper base material. The release agent layer 2a and the release agent permeable layer 2b are cured silicone layers, and the release agent permeable layer 2b
Is a layer in which silicone penetrates between the constituent materials of the base material (fiber such as cellulose, coating agent and other additives) and is hardened. The release agent penetrating layer 2b does not reach the surface (back surface) on the opposite side of the paper base material, and a region 3 where silicone does not permeate is interposed between the release agent permeation layer 2b and the back surface of the paper substrate. .

The present invention also provides a double-sided release paper whose sectional view is shown in FIG. This has a release agent layer 12a and a release agent permeable layer 12b on one surface of the paper substrate 11 of high tension, and has a release agent layer 12c and a release agent permeable layer 12d on the other surface. Things. Release Agent Layers 12a and 12
c is a cured layer of silicone, and the release agent-permeated layers 12b and 12d are layers in which silicone penetrates between the constituent materials of the base material (fiber such as cellulose, coating agent and other additives) and is cured. Release agent layer 12a and release agent permeable layer 12b, and
Since the release agent layer 12c and the release agent permeable layer 12d are simultaneously formed and integrated, respectively, the release agent layer 12a and the release agent layer 12c on each surface are stably held on the paper base material. In FIG. 2, a region 13 consisting only of the constituent material of the base material is interposed between the release agent permeable layers 12b and 12d, but the region 13 is not always necessary in the case of double-sided release paper.

The paper used as the base material in the present invention is a high-tensile paper. Here, the high tension refers to a tension at which the porosity is 50% or more, and is usually 0.75 g / cm ³ or more. In particular, (i) the tension of 0.75 g / cm ³ or more, and (ii) the smoothness (JI
S P8119) Paper satisfying the condition of 40 seconds or more is preferable. Further, (iii) the air permeability (JIS P8117) is preferably 30 seconds or more.

According to the present invention, the apparent density, the tension, is 0.75.
(G / cm ³ ) or more. When the tension is lower than this (that is, when the porosity is high), the penetration into the paper base proceeds in a short time even if a specific silicone having a relatively high viscosity which can be applied as described later is used, and the paper base It is difficult to control so that it does not penetrate to the back surface. It is preferably 0.75 or more for uncoated paper and 0.9 or more for coated paper. The upper limit of the tension may be such that the silicone can penetrate in a range that does not reach the back surface. However, uncoated paper having a tension of more than 1.1 (for example, glassine paper) is expensive, and production as release paper is expensive. The cost is high. In addition, the coatability of the solventless silicone also decreases.

The smoothness is a measure of the smoothness of the paper surface, and the Beck smoothness is such that a test paper is placed on a flat bed having a hole in the center, and the test paper is a predetermined weight plate having a smooth bottom surface. It is a value measured in seconds until a predetermined amount of air is sucked by covering and sucking through the hole.
If there is unevenness on the surface of the test paper, this becomes a flow passage and air flows in. Therefore, the larger the unevenness on the paper surface, the smaller the Beck smoothness. The Beck smoothness of the paper substrate used in the present invention is 40 seconds or more, preferably 50 seconds or more. Smoothness is 4
If the time is less than 0 second, the formation of the film by the silicone becomes insufficient or non-uniform due to large surface irregularities. The upper limit is not particularly limited, but generally the smoothness is improved by a calendering process or a coating process, so that increasing the smoothness increases the manufacturing cost.

The air permeability is a value representing the time required for a predetermined amount of air to pass vertically through the paper in seconds.
The lower the air permeability, the higher the vertical permeability of the paper. The air permeability is related to the porosity of the paper base material. When the air flow path exists between the front and back of the base material, the value of the air permeability is small even if the porosity is low (that is, the air permeability). Is higher). The air permeability of the paper substrate used in the present invention is 30 seconds or more, preferably 40 seconds or more. If the air permeability is less than 30 seconds, the penetration of the silicone liquid into the paper base proceeds in a short time due to the capillary phenomenon, so that it is difficult to control the penetration depth.

A major feature of the method of the present invention is that a conventional commercially available paper material can be used as it is. However, it may be prepared by applying a coating agent or calendering a commercially available paper. Examples of paper that can be used in the present invention without or with these treatments include fine wood for uncoated paper. Coated paper includes coated paper such as light coated paper. Kraft paper has a tension of 0.6.
-0.7, which is not used in the present invention. As described above, on paper whose tension is lower than the range specified in the present invention,
A stable silicone film cannot be formed because the silicone solution or low-viscosity solventless silicone instantaneously penetrates into the paper substrate. Also, kraft paper, especially kraft tape, is generally treated with clupak (a process of imparting fine shrinkage wrinkles for the purpose of enhancing extensibility and making the surface rough structure), so it is intended to apply solventless silicone. Then, there is a problem that fine fibers on the surface of the kraft paper fall off due to a shearing force acting between the coating means and the uniformity of the release agent layer. Even if the surface of the kraft paper is subjected to a super calendering treatment or the like to improve the smoothness or the like of the surface, the rise in the tension is small and the production cost is increased.

The release agent used in the present invention is a polyorganosiloxane derivative generally called a curable silicone. It includes silicone curable by energy application such as thermosetting silicone, ultraviolet curing silicone, and radiation curing silicone. The viscosity of the silicone used in the present invention is 300 cP to 5000 cP or less, preferably 3000 cP or less when not dissolved in a solvent. If it is less than 300 cP, the permeability to the paper surface is high even without solvent, and the effect of the present invention cannot be sufficiently exhibited. If the viscosity of the silicone is too high, it is difficult to form a sufficiently uniform film on the paper surface.

The thermosetting silicone is not particularly limited as long as it has the above viscosity and can be thermoset. For example, solvent-free silicone conventionally used for laminate type release paper can be used as long as it satisfies the viscosity conditions and thermosetting conditions described below. Various types of such solventless silicones have been proposed (for example, JP-A-5-156167,
JP-A-6-1918, JP-A-6-220327, JP-A-6-25602
No. 2554925), generally containing an organopolysiloxane in which one or more reactive groups such as unsaturated groups are bonded to one or more silicon atoms in one molecule, and usually further comprise a catalyst and optionally a curing reaction. Agent. Examples of the catalyst include a tin-based catalyst for the condensation reaction-curing type and various platinum-based catalysts such as chloroplatinic acid and chloroplatinic acid for the addition-reaction curing type. It is. However, in the present invention, silicones other than those mentioned here can be used as long as the penetration depth into the substrate can be controlled by thermosetting.

The thermosetting property of the silicone depends on its structure, the kind and amount of the catalyst.
One that can be cured at a temperature of 150 ° C for 1 second to 1 minute, preferably one that can be cured at a temperature of 100 to 140 ° C for 1 to 30 seconds is used. If the curing temperature and the curing time are outside the above ranges, the productivity will be reduced, and in some cases, the quality of the paper substrate will be adversely affected.

The UV-curable silicone is basically a composition containing a silicone having a radically reactive functional group introduced into a siloxane main chain. A reaction is caused by radicals generated by the irradiation of ultraviolet rays, and curing proceeds. In the present invention, various compounds can be used as long as the above viscosity and curing conditions are satisfied. Examples of such a compound include acrylamide group-containing organopolysiloxane and at least two mercaptoalkyl groups in one molecule. -Curable silicone composition based on a composition comprising an organopolysiloxane having an alkenyl group and an organopolysiloxane having at least two alkenyl groups in one molecule, and an ultraviolet-curable silicone composition based on an alkenyl-containing organopolysiloxane UV curable silicone composition having an acrylic or methacrylic group-containing organopolysiloxane as a main component, an organopolysiloxane having at least two alkenyl groups in one molecule, and at least two silicon-bonded hydrogen atoms in one molecule Have atoms UV-curable silicone composition for a base material a composition comprising organopolysiloxane and the like.
A photoinitiator can be added to such an ultraviolet-curable silicone composition as another optional component. Such photoinitiators include, for example, acetophenone,
Examples include dichloroacetophenone and trichloroacetophenone. The electron beam-curable silicone is a composition obtained by adding a photoinitiator that generates radicals by irradiating an electron beam to polydimethylsiloxane into which an unsaturated group has been introduced. In the present invention, the structure and the like are not particularly limited as long as a predetermined viscosity and curing performance are satisfied.

The amount of silicone to be applied depends on conditions such as the strength of the base paper and the viscosity of the silicone, but is usually 0.1 to 0.1.
5 g / m ^2, preferably from 0.5 to 2 g / m ^2, more preferably 0.6~1.5g / m ^2, more preferably 0.7 to 1.2 g / m ²
Range. If the coating amount of the silicone is small, the silicone film formed on the surface of the base material becomes insufficient, or the film is not uniformly formed and the releasability is reduced. Also, excessive use leads to an increase in the cost of the product, which is not preferable. As described later, when release properties are required on both sides of the paper, silicone may be applied to both sides of the paper base. In this case, silicone may be applied to one side within the above range.

The pressure-sensitive adhesive sheet used in combination with the release paper of the present invention is not particularly limited. In the present invention, since there is no contact between the uncured silicone and the pressure-sensitive adhesive layer, the pressure-sensitive adhesive layer is not limited, for example, acrylic pressure-sensitive adhesive, natural rubber-based,
Rubber-based pressure-sensitive adhesives such as synthetic rubber-based, urethane-based pressure-sensitive adhesives, and silicone-based pressure-sensitive adhesives are exemplified. For labels and the like used outdoors, an acrylic pressure-sensitive adhesive is suitably used because it has good weather resistance. Acrylic adhesives
An acrylic copolymer is used as a main component, but one crosslinked with a crosslinking agent is preferable. When the demand for the weather resistance is not strict, a rubber-based pressure-sensitive adhesive is advantageous in that it is inexpensive.
Examples of the base polymer of the rubber-based adhesive include a styrene-isoprene-styrene block (SIS) copolymer,
Styrene-ethylene butylene-styrene block (SE
BS) copolymer and the like, and formed by combining a rosin-based, coumarone-indene-based, terpene-based, petroleum resin-based, styrene-based, phenol-based, xylene-based tackifying resin, or the like. . As the dosage form of the adhesive, a solvent type,
Either an emulsion type or a hot melt type can be used.

(B) Production method of release paper In the present invention, after applying silicone on a substrate,
The curing treatment is performed within a short time to control the depth of penetration of the silicone into the paper substrate. The time from application to curing is 0.1
About 5 seconds, preferably 2 seconds or less. If this time is too long, the penetration of the silicone into the base material proceeds, and the structure shown in FIG. 1 cannot be obtained. In order to shift to the curing process within such a short time, for example, a manufacturing process described below is employed.

FIG. 4 schematically illustrates a typical process for producing release paper according to the present invention. In the figure, a continuous paper 31 pulled out from a base paper roll 30 is guided by rollers 32a to 32b and the like,
3. It is manufactured as a release paper 35 through a curing unit 34. In the silicone coating section 33, silicone is coated on the surface by, for example, a roller coater. The continuous paper 31 coated with silicone is immediately led to a curing unit 34 provided immediately after the coating unit 33. The time during this period is about 0.1 to 5 seconds, preferably 2 seconds or less, as described above. While passing through the curing section 34, the silicone is cured (cured) by irradiation of heat, ultraviolet rays, electron beams, or the like. The manufactured release paper 35 is coated with an adhesive on the surface on the side opposite to the release agent layer to form an adhesive sheet base material (paper, plastic,
An adhesive sheet product with release paper can be obtained by affixing a metal foil or the like or by laminating the adhesive layer side of a separately produced adhesive sheet on the release layer.

FIG. 5 schematically shows a typical process for producing a double-sided release paper according to the present invention. In the figure, the continuous paper 41 pulled out from the base paper roll 40 is guided by rollers 42a to 42e and the like, one side of which is coated with silicone by a first silicone coating unit 43, and immediately after the coating unit 43. It is immediately led to the first hardening section 44 provided. The time during this period is about 0.1 to 5 seconds, preferably 2 seconds or less, as described above. While passing through the curing unit 44, the silicone is cured (cured) to form a first release agent layer. Next, the second silicone coating unit 45,
A second release agent layer is formed on the other surface via the second curing section 46. The manufactured double-sided release paper is wound up as a release paper roll 47. In the step of forming the second release agent layer, since the silicone cured layer (first release agent layer) has already been formed on the opposite surface, the time control from application to curing is not particularly necessary, but The time between application and curing is 0.1 to 5 as described above.
The first and second release agent layers may be separated in the paper base material for about 2 seconds, preferably 2 seconds or less.

In the above-mentioned process, for example, as a means for applying a silicone liquid, a roll coater, a gravure coater, an air coater, a curtain flow coater or other conventional application means can be used according to the viscosity. The same applies to the application of the adhesive. Various methods such as hot air and radiant heat can be applied as the heating means. Although the drying section is shown as an independent drying chamber in FIGS. 4 and 5, an aspect in which an electric heater is provided immediately after the silicone coating section so as to face the coating surface may be used. The ultraviolet irradiation device is not particularly limited, and conventionally known light sources such as a high-pressure mercury lamp, a medium-pressure mercury lamp, a low-pressure mercury lamp, a hydrogen discharge tube, a xenon discharge tube, and a metal halide lamp can be used. The above example is an example of the manufacturing process of the present invention, and various changes and modifications are possible. For example, it is also possible to use a cut paper instead of a continuous paper, and to continuously apply and dry the silicone by using a conveying means such as a belt conveyor.

[0030]

The present invention will be described more specifically with reference to the following examples and comparative examples. In the following examples, the measurement of the peeling force and the adhesive force was performed according to the following procedure. Peeling force measurement test After leaving the produced adhesive sheet with release paper for one day and 5 days, 5 cm
The sheet was cut into a width, pulled at a peeling speed of 0.3 m / min at an angle of 180 ° using a tensile tester, and the force (g) required to peel off the adhesive paper in the bonded state was measured. The peel force was measured three times for each of the manufactured release paper samples, and it was also evaluated whether a stable peel force was obtained. In the case of a commercially available adhesive cardboard (manufactured by Lintec) using polyethylene laminated paper as the release paper substrate, the release force is 20 g.
/ 5 cm.

Example 1 A coated paper ("Henry Coat O" manufactured by Daishowa Paper Co., Ltd .; base weight: 84.9 g / m ² , strength: 1.19 g /
m ³ , smoothness of 1200 seconds) and a viscosity of 150 as silicone
0cP solvent-free silicone (Toray Dow Corning S
P-7259) was applied at a coating amount of 0.8 g / m ² , introduced into a dryer set at 130 ° C. within 1.5 seconds, and passed through the dryer as it was over 15 seconds. On the other hand, as the adhesive paper base material, high quality paper (“Shiraoi” manufactured by Daishowa Paper Co., Ltd .;
Using a continuous sheet having a basis weight of 64 g / m ² , a tension of 0.81 g / m ³ , an air permeability of 33 seconds, and a smoothness of 51 seconds, an adhesive (PSA AV-6025 manufactured by Showa Polymer Co., Ltd .; strong adhesion) Type) was applied at a coating amount of 25 g / m ^{2 in} terms of solid content and dried. An adhesive sheet with a release paper was manufactured by superimposing the release paper on the adhesive surface of the obtained adhesive paper, and the peel force was measured by the above-described peel force measurement test. The peel force was about 30 g / 5 cm.
It was confirmed that stable and smooth peeling could be realized. Further, when the peeled surface and the adhesive surface were visually observed, both surfaces were smooth, and no peeling of the release agent or migration of the adhesive to the release agent layer was observed.

Example 2 The above high-quality paper ("Shiraoi" manufactured by Daishowa Paper Co., Ltd .; base weight: 64 g / m ² , tension: 0.81 g / m ³ , air permeability: 33 seconds, smoothness: The coated paper (“Henry Coat O” manufactured by Daishowa Paper Co., Ltd .; base weight: 84.9 g / m ² , tightness: 1.19 g / m ³ , smoothness: 12 seconds) was used as an adhesive paper substrate.
A pressure-sensitive adhesive sheet was manufactured in the same manner as in Example 1 except that (00 seconds) was used. When the peeling force between the pressure-sensitive adhesive surface of the obtained pressure-sensitive adhesive sheet and the release paper was measured by the above-mentioned peeling force measurement test, it was confirmed that the peeling force was stable at 30 g / 5 cm and smooth peeling could be realized. Was. Further, when the peeled surface and the adhesive surface were visually observed, both surfaces were smooth, and no peeling of the release agent or migration of the adhesive to the release agent layer was observed.

Comparative Example 1 Ryosara Kraft Paper (manufactured by Daishowa Paper Co., Ltd .; basis weight 53 g / m ² , strength 0.66 g / m ³ , air permeability 16 seconds) was used as a base material (base paper). Except for this, a release paper sample was prepared in the same manner as in Example 1, and this was overlaid with the adhesive paper of Example 1 to produce an adhesive sheet with a release paper. When the peeling force was measured by the above-mentioned peeling force measurement test, many unpeelable portions were formed. Visual observation also confirmed that the release agent layer was insufficiently formed, and there was uneven peeling in which a part of the adhesive surface was fixed to the release layer.

Comparative Examples 2 and 3 Using the coated paper or high-quality paper used in Example 1 or 2 as a base material (base paper), the time required from application of the solventless silicone to introduction into the drying chamber was 8 seconds. A release paper sample was prepared in exactly the same manner as in Example 1 or 2, except that
This was bonded to the pressure-sensitive adhesive surface of the pressure-sensitive adhesive paper prepared in Example 1 or 2 to produce a pressure-sensitive adhesive sheet, and the peeling force was measured by the peeling force measurement test described above. was there. It was also confirmed by visual observation that there was uneven peeling.

Example 3 The high- quality paper used in Example 2 was used as a base material (base paper), and a release agent layer (first material) was formed on one surface under the same conditions as in Example 2.
After forming the release agent layer), a release agent layer (second release agent layer) was also formed on the other surface under the same conditions to manufacture a double-sided release paper. When the adhesive paper of Example 2 was overlaid on each surface of the obtained release paper and bonded, and the release force was measured by the above-described release force measurement test, the release force was 30 g / 5 cm (first).
(Release agent layer) and 30 g / 5 cm (second release agent layer), it was confirmed that stable and smooth peeling could be realized. Further, when the peeled surface and the adhesive surface were visually observed, both surfaces were smooth, and no peeling of the release agent or migration of the adhesive to the release agent layer was observed. Comparative Example 4 A double-sided release paper sample was prepared in exactly the same manner as in Example 3, except that the time required from application of the solventless silicone to introduction into the drying chamber was 8 seconds. Example 2 on both surfaces of the obtained release paper
When the peeling force was measured by the above-mentioned peeling force measurement test, the peeling force was 10
It was 0 g / 5 cm (first release agent layer) and 100 g / 5 cm (second release agent layer), and it was confirmed that the stability of the release agent layer was reduced.

[0036]

The release paper of the present invention can be produced by a production process that does not include a laminating step, so that it can be produced in small lots and the production cost can be greatly reduced. Further, the release paper of the present invention does not contain impurities derived from the barrier layer such as polyethylene flakes, so that it is suitable for use as recycled paper and does not cause a problem in waste disposal. Further, since solventless silicone is used, the safety of the working environment and the like is high, and even when double-sided release paper is used, the stability of the release agent layer on each side is high.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view schematically showing a structure of a release paper according to the present invention.

FIG. 2 is a sectional view schematically showing the structure of a double-sided release paper according to the present invention.

FIG. 3 is a cross-sectional view schematically showing a structure of a release paper according to a conventional technique.

FIG. 4 is a schematic view showing an outline of a release paper manufacturing process according to the present invention.

FIG. 5 is a schematic view showing an outline of a double-sided release paper manufacturing process according to the present invention.

[Explanation of symbols]

 Reference Signs List 1 base material (base paper) 2a release agent layer (paper surface) 2b release agent layer (inside paper) 3 layer composed of only base material 11 base material (base paper) 12a, 12c release agent layer (paper surface) 12b, 12d Release agent layer (inside of paper) 13 Layer composed of only base material 21 Base material 22 Release agent layer 23 Barrier layer 30 Base paper roll 31 Continuous paper 32a to 32c Roller 33 Silicone coated part 34 Cured part 35 Release paper Reference Signs List 40 base paper roll 41 continuous paper 42a to 42x roller 43 first coating unit 44 first curing unit 45 second coating unit 46 second curing unit 47 product roll (release paper)

Claims (13)

[Claims] The present invention is characterized in that a curable silicone is applied to the surface of a high-stress paper substrate, and cured before the silicone penetrates to the back surface of the paper substrate to form a release layer. Production method of release paper. 2. The method for producing a release paper according to claim 1, wherein the curable silicone is used without a solvent. 3. A paper base material having a tension of 0.75 g / cm ³ or more and a Beck smoothness (JIS P8119) of 40 seconds or more.
The method for producing a release paper according to the above. 4. The method for producing a release paper according to claim 3, wherein a paper base material having an air permeability (JIS P8117) of 30 seconds or more is used. 5. The method for producing a release paper according to claim 4, wherein the paper substrate is selected from high quality paper, lightweight coated paper and coated paper. 6. The method according to claim 1, wherein a solvent-free curable silicone having a viscosity of 300 cP or more is applied, and a curing treatment is performed within 5 seconds after the application so that the silicone does not penetrate to the back surface of the paper base material. A method for producing a release paper according to any one of the above. 7. The coating amount of the curable silicone is 0.5 to 2 g.
The method for producing a release paper according to claim 6, wherein the ratio is in the range of / cm ² . 8. The method for producing a release paper according to claim 1, wherein the curable silicone is a thermosetting silicone. 9. The curing step after applying silicone is 100 to 100.
The method for producing a release paper according to claim 8, wherein the method is performed by maintaining the temperature in a range of 150 ° C. for 1 to 30 seconds. 10. The method for producing a release paper according to claim 1, wherein the curable silicone is an ultraviolet curable silicone. 11. A curable silicone is applied to one side of a high-stress paper base and cured before the silicone penetrates to the other side of the paper base to form a first base on one side of the paper base. A method for producing a double-sided release paper, comprising forming a release layer, applying a curable silicone on the other surface, and curing to form a second release layer. 12. A release paper obtained by the method according to claim 1. 13. A double-sided release paper obtained by the method according to claim 11.