JP2016223036A - Base paper for release paper and release paper - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a base paper for a release paper that can be re-used and can suppress penetration of a release agent such as a silicone resin or the like into a filler layer and to provide a release paper excellent in glossiness, adhesion and releasability that is produced by applying a release agent on the base paper for a release paper.SOLUTION: The base paper for a release paper has a filler layer composed mainly of a pigment component and an adhesive component formed on at least one surface of a base paper. The pigment component has a median diameter (D50) of 2.0 to 7.0 μm as measured by laser diffraction by use of a scattering type particle size distribution measuring instrument; the adhesive component comprises at least a synthetic resin latex; and the blending amount of the synthetic resin latex is 8 to 20 pts.mass based on 100 pts.mass of the pigment component.SELECTED DRAWING: None

Description

  The present invention relates to a base paper for a release paper used for a release paper used for an adhesive label, an adhesive seal, an adhesive tape and the like, and in particular, a solvent-based silicone resin, an aqueous emulsion, which is a release agent without laminating polyethylene on the base paper Base paper for release paper that can be directly coated with a base silicone resin or a solvent-free silicone resin, and excellent glossiness, adhesion, and release obtained by applying a release agent to the base paper It is related with the release paper which has property.

The release paper is used as a backing paper for protecting the adhesive surface such as adhesive labels, adhesive seals, adhesive tapes, etc. so that dust or the like does not adhere to it, and a release agent such as silicone resin is used on the surface in contact with the adhesive surface Is applied.
Conventional release paper is manufactured by applying a release agent to the surface of a base paper such as polyethylene laminated paper, glassine paper, clay coat paper, clear coat paper, etc. These release agents are made of an organic solvent such as toluene. Since it was used after diluting, there was a problem of causing environmental destruction.
Therefore, in recent years, the demand for water-based emulsion type silicone resins and solventless silicone resins has increased.

  In addition, since the silicone resin used as the release agent is very expensive, the silicone resin coating solution penetrates into the base paper so that a small amount of the silicone resin coating solution can be applied uniformly. Although it is necessary as a characteristic of the base paper for release paper to suppress this as much as possible, in recent years, recyclability has also been required from the viewpoint of resource saving.

  In order to suppress the penetration of a release agent such as silicone resin, a base paper for release paper in which polyethylene is laminated on a base paper is suitable, but it is difficult to disassemble the release paper after use. Had the disadvantage of not being suitable.

  In order to improve the above disadvantages, an invention relating to a releasable base paper for release paper provided with a pigment coating layer comprising a pigment and a synthetic latex in order to prevent penetration of the silicone resin coating liquid into the base paper (Patent Document 1), however, the penetration of the silicone resin coating solution was not sufficiently prevented, and a release paper having sufficient glossiness, adhesion, peelability and the like could not be obtained.

JP 2000-28297A

The inventors of the present invention have intensively studied to solve the above-mentioned problems. As a result, a sealing layer containing a pigment having a specific median diameter (D50) and a specific adhesive component in a specific ratio range is formed on the surface of the base paper. By providing, it has been found that a base paper for release paper can be obtained which can be recycled and can sufficiently suppress the penetration of the release agent such as silicone resin into the sealing layer.
Accordingly, a first object of the present invention is to provide a base paper for release paper that can be recycled and can prevent the release agent from entering the sealing layer.
A second object of the present invention is to provide a release paper excellent in glossiness, adhesion and peelability, which is obtained by applying a release agent such as silicone resin to the release paper base paper.

That is, the present invention is a release paper base paper provided with a sealing layer containing at least a pigment component and an adhesive component on at least one surface of a base paper, and a scattering type particle size distribution measuring instrument for the pigment component is provided. The median diameter (D50) by laser diffraction used is 2.0 to 7.0 μm, the adhesive component contains at least a synthetic resin latex, and the synthetic resin latex is 100 parts by mass of the pigment component. Peeling having a release agent layer formed by applying a release agent on the release paper base paper, and a release paper base paper characterized in that the blending amount is 8 to 20 parts by mass when absolutely dry The coating amount of the release agent layer obtained from the basis weight difference between the base paper for release paper and the release paper measured in accordance with JIS P8124: 2011 under the environment of JIS P 8111: 1998. , 0. A release paper, which is a to 2.0 g / ^{m 2.}
However, in the present invention, “absolutely dry” refers to drying at 105 ° C. for 1 to 2 hours. Hereinafter, the parts by mass of the pigment and synthetic resin latex used in the present invention are “parts by mass after absolute drying”. .

The pigment used for the base paper for release paper of the present invention is preferably kaolin, and the synthetic resin latex preferably has a glass transition temperature of −20 to 30 ° C., in particular, the synthetic resin latex. Is preferably a styrene / budadiene copolymer latex.
Moreover, the coating amount of the sealing layer calculated | required from the basic weight difference of the base paper and the base paper for release paper measured based on JIS P 8124: 2011 in the environment of JIS P 8111: 1998 is 8-20 g / m ² is preferable.

  Moreover, it is preferable that the surface roughness measured based on JIS B0601: 1994 of the said sealing layer surface is 0.5-1.0 micrometer, and based on JISP8155: 2010 of the said sealing layer surface. The measured smoothness is preferably 500 to 2,000 seconds.

In addition, the air resistance measured based on JIS P 8117: 2009 of the base paper for release paper of the present invention is preferably 100,000 seconds or more, and the surface of the release agent layer in the release paper of the present invention, The 75 ° glossiness measured based on JIS P 8142: 2005 is preferably 70 to 90%.
The release agent layer is preferably a silicone resin layer.

  According to the present invention, it is possible to provide a base paper for release paper that can be recycled and sufficiently suppresses the penetration of the release agent into the sealing layer, and has high gloss, adhesion, and peelability. An excellent release paper can be provided.

The release paper base paper of the present invention is provided with a sealing layer on at least one surface of a base paper, and the sealing layer contains at least a pigment component and a synthetic resin latex as an adhesive component.
The median diameter (D50) by laser diffraction using a scattering type particle size distribution measuring instrument for the pigment contained in the filler layer is required to be 2.0 to 7.0 μm, and 3.0 to 5.0 μm. It is preferable that

  When the median diameter (D50) of the pigment is less than 2.0 μm, the effect of filling the gaps between the fibers on the surface of the base paper can be obtained, but the latex cannot sufficiently adhere between the pigments, and the fine gaps are not formed. Therefore, the penetration of the release agent coating liquid into the sealing layer cannot be prevented. On the other hand, when the median diameter (D50) exceeds 7.0 μm, the unevenness of the surface of the sealing layer of the release paper base paper becomes large, and the release agent coating solution cannot be uniformly applied.

  The pigment used in the present invention is not particularly limited as long as the median diameter (D50) by laser diffraction using a scattering type particle size distribution measuring device is in the range of 2.0 to 7.0 μm. The pigments used, for example, kaolin, clay, heavy calcium carbonate, light calcium carbonate, talc, titanium dioxide, aluminum hydroxide, mica and the like can be used alone or in combination of two or more.

  Among the above pigments, it is possible to obtain a release paper with excellent flatness and excellent releasability, and it is possible to apply a release agent coating liquid uniformly and thinly and to cure the release agent. In the present invention, it is preferable to use kaolin, which is a flat pigment, from the viewpoint that it is necessary to be a substance that does not inhibit.

  The amount of the synthetic resin latex used in the adhesive component used for the sealing layer needs to be 8 to 20 parts by mass with respect to 100 parts by mass of the pigment component, and 10 to 15 parts by mass. Part.

If the amount of the synthetic resin latex used for 100 parts by mass of the pigment component is less than 8 parts by mass, the ratio of the pigment becomes too high, so that the gap between the pigment and the pigment is not sufficiently filled with the latex. Many fine voids are generated and it becomes impossible to prevent penetration of the release agent coating liquid into the filler layer.
Moreover, when the usage-amount of synthetic resin latex exceeds 20 mass parts, since the water disintegration property of the base paper for release paper deteriorates, utilization as a recycled paper will become difficult.

  Moreover, it is preferable that the glass transition temperature (Tg) of synthetic resin latex is -20-30 degreeC. If the glass transition temperature of the synthetic resin latex is lower than −20 ° C., the coating layer becomes too soft and defects such as being easily scratched occur. On the other hand, when the glass transition temperature exceeds 30 ° C., the sealing layer is likely to be non-uniform and pinhole defects are likely to occur.

The glass transition temperature (Tg) of the synthetic resin latex is 10 mg under a nitrogen atmosphere in accordance with JIS K-7122 after pretreatment of the synthetic resin latex at 130 ° C. for 30 minutes. The change in specific heat accompanying the secondary transition at a temperature of 20 ° C./min) is determined from the following formula as the glass transition temperature.

(Tg) = Tg1 × α1 + Tg2 × α2 +... + Tgn × αn
Tg1, Tg2,... Tgn: Glass transition temperature (K) of each measured composition alone
α1, α2,... αn: Mass fraction (%) of each composition alone relative to the total resin mass

Moreover, the said synthetic resin latex may use only 1 type, or may use 2 or more types together, if the range of glass transition temperature is -20-30 degreeC.
The synthetic resin latex used in the present invention includes a styrene / butadiene copolymer, a styrene / acrylic copolymer, an ethylene / vinyl acetate copolymer, a butadiene / methyl methacrylate copolymer, and a vinyl acetate / butyl copolymer. Examples include latexes of various copolymers such as acrylate copolymers. In the present invention, it is preferable to use styrene / budadiene copolymer latexes having good compatibility with kaolin.

  In addition to the synthetic resin latex, a binder such as starch, polyvinyl alcohol, or an acrylic resin may be used in combination as appropriate as the adhesive component.

The base paper used for the base paper for release paper of this invention has a wood pulp fiber as a main component. Wood pulp fibers include chemical pulp such as softwood kraft pulp, hardwood kraft pulp, sulfite pulp, mechanical pulp such as stone grind pulp, thermomechanical pulp, refiner grind pulp, and newspapers, coated paper, fine paper, etc. The obtained recycled pulp or the like can be used by appropriately blending.
Moreover, you may mix | blend fiber materials other than cellulose fibers, such as non-wood pulp, such as kenaf, hemp, and bamboo, glass fiber, and polyethylene fiber as needed.

  When making the above base paper, add internal additives such as sizing agent, paper strength enhancer, fixing agent, yield improver, dye, etc., talc, kaolin, titanium dioxide, aluminum hydroxide, calcium carbonate, etc. In the middle of the paper making process, a paper strength improver such as starch or polyvinyl alcohol, a surface sizing agent, a dye, or the like may be applied appropriately using a size press, a gate roll, or the like. .

  As a method for applying the sealing layer coating liquid to the base paper, a method using various coating apparatuses such as a blade coater, an air knife coater, a rod blade coater, and a bar blade coater can be appropriately selected.

The coating amount of the sealing layer in the base paper for release paper of the present invention is preferably 8 to 20 g / ^{m 2,} and more preferably 10 to 15 g / ^{m 2.}
If the coating amount of the sealing layer is less than 8 g / m ² , a uniform sealing layer cannot be obtained. Moreover, even if the coating amount of the sealing layer exceeds 20 g / m ² , it is not economical because improvement in quality accompanying an increase in coating amount cannot be expected.
Moreover, you may add a dispersing agent, a water-proofing agent, a lubricant, an antifoamer, a preservative, a dye etc. suitably in the coating liquid of a sealing layer as needed.

Moreover, it is preferable that the surface roughness measured based on JISB0601: 1994 of the said sealing layer is 0.5-1.0 micrometer, and it is more preferable that it is 0.6-0.8 micrometer.
When the surface roughness is less than 0.5 μm, the adhesion between the filler layer and the release agent layer is lowered. On the other hand, when the surface roughness exceeds 1.0 μm, the uniformity of the release agent layer decreases.

  The smoothness measured based on JIS P 8155: 2010 of the filler layer in the base paper for release paper of the present invention is preferably 500 to 2,000 seconds, more preferably 700 to 1,500 seconds. preferable. When the smoothness is less than 500 seconds, it becomes difficult to apply the release agent thinly and uniformly. Moreover, when smoothness exceeds 2,000 second, the adhesiveness of the base paper for release paper and a release agent layer will fall.

  The air permeation resistance measured based on JIS P 8117: 2009 of the base paper for release paper of the present invention is preferably 100,000 seconds or more. If the air resistance is less than 100,000 seconds, the sealing is insufficient and the penetration of the release agent cannot be suppressed.

Examples of the release agent that can be used for the base paper for release paper of the present invention include silicone resins, fluorine compounds, aminoalkyd compounds, and polyester compounds.
In the present invention, it is particularly preferable to use a silicone resin. Examples of the silicone resin used as the release agent include solvent-free silicone resins, solvent-based silicone resins, water-based emulsion silicone resins, and solvent-free UV curable silicone resins.

The release paper of the present invention is obtained by coating the release agent on the sealing layer of the base paper for release paper of the present invention so as to be 0.5 to 2.0 g / m ² .
In addition, as a method of applying the release agent to the release base paper, various coating apparatuses such as a blade coater, an air knife coater, a rod blade coater, a bar blade coater, and a gravure coater can be appropriately selected and used.

The 75 ° glossiness of the release agent layer surface of the release paper of the present invention is preferably 70 to 90%, and more preferably 75 to 85%.
If the 75 ° gloss is less than 70%, a uniform release agent coating surface cannot be obtained. On the other hand, when the 75 ° glossiness exceeds 90%, the release agent layer becomes excessively thick, and the adhesion between the release paper base paper and the release agent layer becomes insufficient.

The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples.
In addition, unless otherwise indicated, the part and% in an Example show a mass part and mass%, respectively.

The volume distribution average particle diameter of the pigment used in the examples, the quality of the base paper for release paper, and the quality of the release paper were measured and evaluated by the following methods.
<Volume distribution average particle diameter of pigment>
The volume particle size distribution of the pigment particles was measured using a laser diffraction / scattering type particle size distribution analyzer (manufactured by Malvern Co., Ltd., device name: Mastersizer S), and the median diameter (D50) was determined.

<Quality evaluation of base paper for release paper>
(1) Air permeability resistance Measured based on JIS P 8117: 2009.
(2) Smoothness The coated surface of the sealing layer was measured based on JIS P 8155: 2010.
(3) Surface roughness The center line average roughness (μm) of the sealing layer coating surface was measured based on JIS B 0601: 1994 using a small surface roughness shape measuring instrument (SURFCOM 130A).
(4) Coating suitability The degree of occurrence of streaks, scratches and coating unevenness on the coating surface of the sealing layer when blade coating of 10,000 m was performed at a coating speed of 500 m / min was evaluated.
[Evaluation criteria]
◯: Not generated Δ: Slightly generated ×: Generated frequently (5) Uniformity A 10% oil blue toluene solution was prepared as a staining solution. This dyeing solution was uniformly applied to the coating surface of the sealing layer, wiped with gauze after 5 seconds, and then visually evaluated for defects (missing pinholes, etc.) in the sealing layer.
[Evaluation criteria]
○: There are almost no defects and the seal is uniform. △: There are some defects. X: There are many defects. (6) Disaggregation The tappi standard disaggregator is immersed in water so that the concentration of the base paper for release paper is 2.0%. The degree of disaggregation into water when disaggregating for 60 minutes was evaluated.
[Evaluation criteria]
○: Pulp fibers are dispersed and disaggregation is good. ×: Pulp fiber lump and pulp fiber bundle remain, and disaggregation is impossible.

(1) Glossiness of silicone resin The 75 ° glossiness was measured based on JIS P 8142: 2005.
[Evaluation criteria]
○: 70% or more ×: Less than 70% (2) Adhesiveness of silicone resin The surface of the silicone resin layer was rubbed with a finger (3 kg load) to evaluate the surface condition.
[Evaluation criteria]
○: No rubbing trace Δ: Rubbing trace ×: Silicone resin peeling occurred at the rubbing location (3) Coverage of silicone resin The surface was written with magic ink to evaluate the repellency of the ink.
[Evaluation criteria]
○: Repels evenly ×: There is a part that does not repel

<Preparation of base paper for release paper>
A raw material pulp having LBKP of 100% by mass was used, and 0.3 part by mass of cationized starch was added as a paper strength agent to 100 parts by mass of the raw material pulp. Next, 1.5 parts by mass of a sulfuric acid band was added, and then paper making was performed using a long mesh multi-cylinder paper machine to produce a base paper having a basis weight of 120 g / m ² .

  100 parts by weight of kaolin KCS (Imeris, D50: 4.6 μm) as a pigment and 100 parts by mass as an adhesive, styrene-butadiene copolymer latex (trade name: PA0330, manufactured by Japan A & L, Tg-10 ° C.) as an adhesive 12 parts by mass, and further, a small amount of a thickener and a dispersant, an antifoaming agent and a lubricant were blended as appropriate to prepare a coating solution for a sealing layer.

Next, using a blade coater, the coating liquid was applied to one side of the base paper so that the coating amount was 10 g / m ² , and a sealing layer was provided to obtain a base paper for release paper.

  A base paper for release paper was obtained in the same manner as in Example 1 except that kaolin Hydrasperse for papermaking (Kamine, D50: 3.2 μm) was used as the pigment.

  A base paper for release paper was obtained in the same manner as in Example 1, except that 50 parts by mass of the kaolin KCS (manufactured by Imerys) and 50 parts by mass of the kaolin Hydrasperse (manufactured by Kamin) were used as pigments. It was.

  A release paper base paper was obtained in the same manner as in Example 1 except that heavy calcium carbonate (trade name: Sunlite SL-100, Takehara Chemical Industries, D50: 6.5 μm) was used as the pigment.

  A base paper for release paper was obtained in the same manner as in Example 1 except that 20 parts by mass of the latex (PA0330) was used as an adhesive.

  In addition to the latex (PA0330) as an adhesive, a release paper base paper was prepared in the same manner as in Example 1 except that 10 parts by mass of oxidized starch (MS # 3800, manufactured by Nippon Shokuhin Kako) was further blended. Obtained.

[Comparative Example 1]
A base paper for release paper was obtained in the same manner as in Example 1 except that Astra Grace (Imeris, D50: 0.7 μm) was used as the kaolin of the pigment.

[Comparative Example 2]
A base paper for release paper was obtained in the same manner as in Example 1, except that the pigment was changed to commercially available heavy calcium carbonate TP-SO-10 (Okutama Kogyo Co., Ltd., D50: 8.0 μm).

[Comparative Example 3]
A base paper for release paper in the same manner as in Example 1 except that 50 parts by mass of kaolin KCS (D50: 4.6 μm) and 50 parts by mass of Astra Grace (D50: 0.7 μm) were used as pigments. Got.

[Comparative Example 4]
A release paper base paper was obtained in the same manner as in Example 1 except that the amount of the latex was 7 parts by mass.

[Comparative Example 5]
A release paper base paper was obtained by the same method as in Example 1 except that the amount of the latex was 23 parts by mass.

[Comparative Example 6]
A base paper for release paper was obtained in the same manner as in Example 1 except that oxidized starch (MS # 3800, manufactured by Nippon Shokuhin Kako) was used as the adhesive.

[Comparative Example 7]
A release paper base paper was obtained by the same method as in Example 1 except that PVA (PVA117, manufactured by Kuraray) was used as the adhesive.

[Comparative Example 8]
A base paper for release paper was obtained in the same manner as in Example 1 except that ethylene vinyl acetate (Polysol AM-3150, Showa Denko) was used as the adhesive.

The quality evaluation mentioned above was performed about the base paper for release paper obtained in Examples 1-6 and Comparative Examples 1-8. The results are shown in Tables 1 and 2.

<Preparation of release paper>
A necessary amount of catalyst was added to a solventless silicone resin (LTC-1053L: manufactured by Toray Dow Corning Silicone Co., Ltd.) to obtain a coating solution for a release agent. Next, using a RI printer, a coating solution for the release agent and a coating amount of the solventless silicone resin are 1.0 g / m ² on the sealing layer of the release paper base paper of Example 1. After coating, a curing treatment was performed with a dryer (130 ° C., 10 sec) to obtain a release paper.

The quality evaluation described above was performed on the release paper obtained in Example 7. The results are shown in Table 3.

From the results of Examples 1 to 6 and Comparative Examples 1 to 8, it was confirmed that the base paper for release paper of the present invention has good quality of the sealing layer.
Moreover, from the result of Example 7, it was confirmed that the release paper of the present invention has good gloss, adhesion and peelability.

  The base paper for release paper of the present invention is reusable and not only prevents penetration of the release agent into the sealing layer, but also provides glossiness and adhesion by applying the release agent. In addition, since a release paper having excellent peelability can be provided, it is suitable for the production of adhesive labels, adhesive seals, adhesive tapes and the like, and is extremely useful industrially.

Claims (11)

  A release paper base paper provided with a sealing layer containing at least a pigment component and an adhesive component on at least one surface of a base paper, and by laser diffraction using a scattering type particle size distribution measuring device for the pigment component The median diameter (D50) is 2.0 to 7.0 μm, the adhesive component contains at least a synthetic resin latex, and the blending amount of the synthetic resin latex with respect to 100 parts by mass of the pigment component is absolutely A base paper for release paper, characterized by being 8 to 20 parts by mass when dry.   The base paper for release paper according to claim 1, wherein the pigment is kaolin.   The base paper for release paper according to claim 1 or 2, wherein the synthetic resin latex has a glass transition temperature of -20 to 30 ° C.   The base paper for release paper according to any one of claims 1 to 3, wherein the synthetic resin latex is a styrene / budadiene copolymer latex. The coating amount of the sealing layer determined from the basis weight difference between the base paper and the base paper for release paper measured in accordance with JIS P 8124: 2011 under the environment of JIS P 8111: 1998 is 8 to 20 g / m ^2. The base paper for release paper as described in any one of Claims 1-4 which is.   The base paper for release paper according to any one of claims 1 to 5, wherein the surface roughness of the surface of the sealing layer measured based on JIS B 0601: 1994 is 0.5 to 1.0 µm.   The release paper base paper according to any one of claims 1 to 6, wherein the release resistance measured based on JIS P 8117: 2009 of the release paper base paper is 100,000 seconds or more.   The base paper for release paper according to any one of claims 1 to 7, wherein the smoothness of the surface of the sealing layer measured based on JIS P 8155: 2010 is 500 to 2,000 seconds. A release paper having a release agent layer formed by applying a release agent on the sealing layer of the release paper base paper according to any one of claims 1 to 8, and in an environment of JIS P 8111: 1998, The coating amount of the release agent layer determined from the basis weight difference between the base paper for release paper and the release paper measured based on JIS P 8124: 2011 is 0.5 to 2.0 g / m ^2. Characteristic release paper.   The release paper according to claim 9, wherein the release agent layer is a silicone resin layer.   The release paper according to claim 9 or 10, wherein the 75 ° glossiness measured on the surface of the release agent layer based on JIS P 8142: 2005 is 70 to 90%.