JP2009203561A - Base paper for release paper having photoelectric tube suitability, and release paper - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a release paper having photoelectric tube suitability, hardly causing adhesive transfer or entrainment and exhibiting good suitability to label processing. <P>SOLUTION: The base paper for the release paper having the photoelectric tube suitability is obtained by making a paper by blending 70 mass% or more of LBKP based on the whole raw material pulp, and subjecting the resultant paper to supercalender treatment. The air permeability, smoothness, formation, barrier property, density, or the like of the base paper is controlled, and base paper is uniformly impregnated with a remover resin coated at 0.8-1.5 g/m<SP>2</SP>so that the thickness of a single resin layer of the dried remover resin may be 30-150 nm. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a release paper base paper and release paper having light transmittance suitable for a release paper base, and more particularly to a release paper base paper and release paper for an adhesive sheet excellent in label processing suitability. Is.

  The pressure-sensitive adhesive sheet is a sheet in which a pressure-sensitive adhesive layer is formed between the surface base material and the release paper. In recent years, with the progress of the information society, a wide range of commercial, office, household, etc. , Labels, stickers, stickers, emblems, delivery slips, etc. As the surface substrate, paper is mostly used, and the release paper is made of a high density base paper such as glassine paper, clay coated paper, polyethylene laminated paper, etc. with a release agent such as silicone compound or fluorine compound. The coated one is widely used. Usually, solvent-free silicone resin is used from the viewpoints of peeling performance, price, and environment and safety. As the pressure-sensitive adhesive, a solvent type, an emulsion type, a hot melt type and the like are used, and among them, an acrylic emulsion type is usually used in view of safety and quality.

  In recent years, these pressure-sensitive adhesive sheets, especially in commercial and industrial labels, are made as thin and small as possible in unnecessary parts around the label (hereinafter referred to as “粕”) that are punched from the viewpoint of resource saving. In order to increase the performance, it has come to be punched into complex shapes at high speed. For this reason, at the time of label processing, when the ridges are peeled off from the release paper (hereinafter referred to as “wrinkle removal”), the folds are likely to be cut off, resulting in a problem of reduced workability. On the other hand, in order to improve the wrinkle removal suitability, an improvement effect can be expected by reducing the peel force, but the label that is originally left on the release paper may also be removed together (hereinafter referred to as “lifting”). It is a factor.

  As a technique for solving these problems, Patent Document 1 defines the peeling force and the elastic modulus in the thickness direction of the release paper base material, and Patent Documents 2 and 3 also provide the strength and peel strength of the surface base material. The defined technology is disclosed. Further, in order to impart light transparency, a base material that is mainly made of softwood pulp such as glassine paper and is beaten and densified by calendering is used as the release paper base paper. . On the other hand, in Patent Documents 4 to 9, label punching processability is achieved by applying a transparent resin to develop transparency in order to express light transparency with plain paper, and by not making the release paper low in US basis weight. A technique for providing the above is disclosed. Also, in the process of applying adhesive to release paper, if there are pinholes or recesses in the release paper substrate, it becomes an adhesive sheet with the adhesive in, and then the surface substrate to which the adhesive is attached is peeled off When peeled from the adhesive layer, a phenomenon that the adhesive remains on the release paper (hereinafter referred to as “glue residue”) is observed.

  This adhesive residue is the process of subjecting the adhesive sheet to form printing or seal printing, and the adhesive remaining on the release paper on the guide roll, etc., where the release agent surface hits when printing, die-cutting (punching), scoring, etc. Adhering causes troubles such as paper feeding failure and printing misalignment, which becomes a serious obstacle to workability and quality. Further, even in a process of printing or labeling with an auto labeler or a handler labeler, adhesive residue on the surface of the release agent layer such as paper feed failure or printing misalignment becomes a problem. In order to solve this problem, conventionally, it has been a conventional means to apply a release agent more uniformly and to provide a barrier property so that the release agent does not penetrate into the release paper base paper. In particular, Patent Document 10 discloses a technique for imparting labeling suitability while suppressing penetration of a release agent by passing paper through a metal roll and a metal roll to achieve high density and high smoothness. In Patent Document 10, it is described that the smoothness is 2,000 seconds or more. However, in order to achieve the smoothness of 2,000 seconds or more, a metal roll / metal roll as described in Patent Document 10 is used. High-pressure calender treatment is required, and the manufacturing method for achieving high density and high smoothness is limited, and the processing costs enormously. Furthermore, Patent Document 11 discloses that phototube suitability can be imparted by partially using hardwood bleached kraft pulp with a low α-cellulose content, but it is not mentioned with respect to the application of a release agent resin, It is not intended to improve the label processing aptitude such as the rise and the adhesive residue.

  Peeling that can solve the above-mentioned problems and can form a pressure-sensitive adhesive sheet with high workability, which can remove the wrinkle punched into a thin and complex shape at a high speed, and does not rise and generate adhesive residue. At present, there is a demand for paper and release paper base paper.

Japanese Patent Laid-Open No. 11-181364 JP-A-11-293596 JP 2000-144078 A JP 2001-271295 A JP 2003-147696 A JP 2003-253600 A JP 2003-340976 A JP 2005-010513 A JP 2005-089905 A JP 2000-345497 A JP 2007-186816 A

  The present invention provides a base paper for release paper and a release paper having a light-transmitting property for pressure-sensitive adhesive sheets that have no adhesive residue or rise and have good label processing suitability.

The present invention includes the following inventions.
(1) A base paper for release paper having phototube suitability, which is made by mixing 70% by mass or more of hardwood bleached kraft pulp with respect to all raw material pulp and is supercalendered, and the base paper has a release agent Release paper in which the thickness of the release agent resin single layer when applying and curing resin 0.8 to 1.5 g / m ² is 30 to 150 nm.

(2) JAPAN TAPPI Paper Pulp Test Method No. The base paper for release paper according to (1), wherein the air permeability of the base paper for release paper measured according to 5-2: 2000 is 3,000 to 30,000 seconds.

(3) The release paper base paper according to (1) or (2), wherein the release paper base paper measured according to ISO 2471 has an opacity of 50 to 75%.

(4) The peeling according to any one of (1) to (3), wherein a standard deviation of formation unevenness standardization of the release paper after applying and curing a release agent to the base paper for release paper is 0.4 or less. paper.

(5) JAPAN TAPPI Paper Pulp Test Method No. The base paper for release paper according to any one of (1) to (4), wherein the smoothness of the base paper for release paper measured according to 5-2: 2000 is 300 to 1,500 seconds.

(6) The release paper according to any one of (1) to (5), wherein the release agent resin is a solventless silicone resin.

  A base paper for release paper produced mainly from hardwood bleached kraft pulp (hereinafter abbreviated as LBKP), with the formation, smoothness, barrier agent type and coating amount, density, and air permeability controlled to specific ranges. By allowing the release agent resin, such as resin, to penetrate in an appropriate and uniform manner, there is no adhesive residue even if the release agent barrier property of the surface is not increased as in the case of conventional release paper with high smoothness and high air permeability. On the other hand, by exhibiting an appropriate peel strength, it is possible to provide a release paper that has good label processing suitability such as rising and wrinkle removal suitability.

As a result of various studies on physical properties of release paper base paper having light transmissibility in order to improve label processing aptitude such as adhesive residue, finish, and wrinkle removal ability of the adhesive sheet, It is better to control the smoothness, barrier agent type and coating amount, density, and air permeability to a specific range and soak the silicone resin as a release agent in the base paper. It was found to be good. That is, when 0.8-1.5 g / m < ² > of release agent resin is applied to the base paper for release paper and cured, the thickness of the release agent resin single layer needs to be 30-150 nm. When the thickness of the release agent resin single layer is small, the penetration into the release paper base paper is large, and the amount of the release agent resin remaining as a release agent resin single layer on the surface is small. When the thickness is large, it indicates that most of the applied release agent resin is on the surface of the release paper base paper and forms a coating film of the release agent resin single layer. When the thickness of the release agent resin single layer is less than 30 nm, the surface covering of the release agent resin becomes insufficient, the release force becomes too heavy, and the release performance may not be easily exhibited. In addition, various label processing aptitudes such that adhesive residue is liable to occur at the time of label processing are caused. On the other hand, when the thickness of the release agent resin single layer exceeds 150 nm, the peel force becomes light, the adhesive force of the label to the release paper becomes weak, and there is a possibility that it will be easily lifted. Depth direction analysis by ESCA using ion sputtering ("Surface and depth direction analysis method" (Science & Technology), pages 155-163, 2007) Is used), but is not limited to this method.

  As a technique for controlling the penetration of the release resin such as silicone resin, first, the JAPAN TAPPI paper pulp test method No. 1 was used. The air permeability of the base paper for release paper measured according to 5-2: 2000 is controlled. That is, the air permeability of the base paper for release paper is preferably 3,000 to 30,000 seconds, more preferably 5,000 to 20,000 seconds, and particularly preferably 6,000 to 12,000 seconds. . When the air permeability of the base paper for release paper is less than 3,000 seconds, the release agent resin is soaked so that the release performance is hardly exhibited. On the other hand, if it is higher than 30,000 seconds, the release resin does not penetrate, the peel strength is reduced, and the body is likely to rise. Second, the JAPAN TAPPI paper pulp test method no. The smoothness of the base paper for release paper measured according to 5-2: 2000 is preferably 300 to 1,500 seconds, more preferably 500 to 1,200 seconds, and particularly preferably 700 to 1,000 seconds. is there. If the smoothness is less than 300 seconds, it is difficult for the stripper resin to penetrate uniformly in the surface thickness direction, and if the smoothness exceeds 1,500 seconds, the stripper resin itself penetrates. It becomes difficult, the peel strength becomes light, and it becomes easy for the body to rise.

  Furthermore, in order to make the thickness of the release agent resin single layer uniform, it is desirable that the release paper base is well-formed, and in order to impart light transmission as phototube suitability, conventional softwood bleached kraft pulp It is better to make paper with LBKP as a main body and calender it to increase the density, instead of making it high as a main body (hereinafter abbreviated as NBKP). Compared with NBKP, LBKP is relatively thin and short, has few pinholes, and easily forms a uniform texture. Further, among LBKPs, transparency tends to be more easily expressed when hemicellulose is contained more. That is, in order to form a uniform formation with few pinholes, the amount of LBKP needs to be 70% by mass or more of the total raw pulp. If it is less than 70% by mass, the uniformity of formation becomes insufficient, pinholes are easily formed, and even if a release agent resin is applied, the pinholes remain and cause glue residue. In addition, if the formation is not uniform, the punching blade does not have a uniform edge perforation when the adhesive sheet is punched, and the label is not cut well, leading to a rise.

In the case of glassine paper mainly composed of NBKP, even if air permeability and smoothness are high, the fiber width of the original NBKP is very thick compared to LBKP, so there is a tendency that local elimination of pinholes is insufficient. is there. Other pulp raw materials used in the present invention are not limited to wood pulp, and non-wood pulp such as hemp and kenaf, and synthetic fibers may be blended. As a measure of uniformity of formation, in the present invention, the basis weight of a minute part of 1 mm × 1 mm unit (4900 data) is measured by an AMBERTEC beta formation tester (β-line total), and the average basis weight is measured. X / Y / X ^½ when the standard deviation Y of the basis weight is taken as the “standardized standard deviation” of the basis weight unevenness. Because the standard deviation increases as the basis weight increases, the numerical value also increases. Therefore, a value obtained by dividing the standard deviation by the square root of the basis weight is used.

The beating level of the raw pulp does not need to be beaten as high as that of glassine paper, and can be about 200 to 400 csml as Canadian standard freeness. A barrier agent for controlling the penetration of the release resin is applied to the base paper made from such a raw material. A barrier agent is a composition which has a water-soluble polymer as a main component, More preferably, polyvinyl alcohol, starch, etc. are used suitably. The coating amount of the water-soluble polymer composition is 0.3 to 1.0 g / m ² per side in terms of solid content. If it is less than 0.3 g / m ² , the barrier property becomes insufficient, and if it exceeds 1.0 g / m ² , the air permeability increases, and the release agent resin in the present invention does not penetrate, which is not preferable. .

In the present invention, the base paper for release paper is calendered in a state in which 10 to 20% of moisture is retained, thereby increasing the density and expressing transparency. For the application of the barrier agent, an on-machine size press or a gate roll coater is preferable from the viewpoint of operation efficiency such that the base paper before the calendar process needs to retain high moisture. Further, as the calendar treatment, considering the expression of transparency, it is preferable that the density is in the range of 1.0 to 1.2 g / cm ³ , so that high-temperature multi-stage pressurization treatment with a super calender that facilitates higher density is preferable. Is good. In the present invention, the basis paper having a basis weight of about 55 to 75 g / m ² is used for general purposes.

  The air permeability of the release paper base paper thus obtained is in the range of 3,000 to 30,000 seconds as described above, and the opacity measured according to ISO 2471 is in the range of 50 to 75%. . When the opacity exceeds 75%, the phototube suitability is insufficient, and the phototube suitability is not a problem even if the transparency is not increased so that the opacity is less than 50%. In the present invention, in order to express transparency, impregnation and application of a transparent resin is not an essential constituent requirement, and transparency is expressed by increasing the density. When making base paper, as a chemical added internally to the raw slurry, a fixing agent such as sulfuric acid band, a paper strength enhancer such as starch or PAM, an AKD or rosin sizing agent, and other necessary wet paper strength Agents, dyes and pigments can be added as appropriate. Here, the degree of squeeze size (measured according to JIS P 8122: 2004) is preferably about 5 to 20 seconds.

  By the way, since most adhesives are water-based emulsion types, even though the release resin coats the base paper surface, it is not a complete barrier, so the adhesive may penetrate between the base paper gaps. . In order to suppress the penetration of the pressure-sensitive adhesive into the base paper, it is preferable to appropriately give the Steecht sizing degree. Also, from the point of preventing adhesive residue due to the adhesive entering the base paper, there is no pinhole in the uniform texture, and the release resin is soaked in the base paper, so that the adhesive residue can also be suppressed. To do.

  In the present invention, a release agent resin is applied to the release paper base paper in the paper quality range as described above and cured. Examples of the release resin in the present invention generally include silicone resins, fluororesins, aminoalkyd resins, polyester resins, etc., but usually an aqueous emulsion type, a solvent type, or a solventless type in terms of release quality and price. The silicone resin is used. In particular, switching from an aqueous emulsion type to a solventless type is progressing from the viewpoint of environmental consideration and worker safety, and in the present invention, it is more preferable to use a solventless silicone resin. Among these, a solventless silicone resin having a viscosity at 25 ° C. of 50 to 1,000 mPa · s is more preferable. Examples of the method for applying the release agent resin include a bar coater, a direct gravure coater, an offset gravure coater, and a multi-stage roll coater.

About 0.8 to 1.5 g / m ² is required for the application amount of the release agent resin. If the application amount is less than 0.8 g / m ² , the amount of the release agent is small and the release performance is insufficient. Moreover, when it exceeds 1.5 g / m < ² >, in addition to the possibility that peeling force may become too light, it is not preferable economically. As described above, it is important that the release agent resin single layer having such a coating amount range is soaked to some extent. When the thickness of the release agent resin single layer is less than 30 nm, the amount of the release agent on the surface is small and the release force becomes heavy. On the other hand, when the thickness exceeds 150 nm, a large amount of the release agent exists on the surface, the peeling force becomes lighter than necessary, and the body is likely to rise. Further, as described above, when the formation uniformity after the release paper is quantified as formation unevenness by transmitted light, the standardized standard deviation is preferably 0.4 or less. If it exceeds 0.4, the formation unevenness gradually increases, resulting in non-uniform per-blade at the time of punching, and the label processing suitability deteriorates. In addition, the higher the compressive modulus in the thickness direction of the release paper, the better the punching suitability. From this point of view, the higher the density of the release paper is preferable.

When producing a pressure-sensitive adhesive sheet, the pressure-sensitive adhesive is applied to the surface of the release agent layer of the release paper, dried, and then bonded to the surface substrate. Examples of the pressure-sensitive adhesive include natural rubber, styrene- Adhesives such as butadiene copolymers, styrene-isopropylene block copolymers, rubbers such as recycled rubber and synthetic rubber, acrylics, and silicones are appropriately used. These pressure-sensitive adhesives have forms such as a solvent type, an aqueous emulsion type, a hot melt type, and a liquid curable type. The application amount of the pressure-sensitive adhesive is appropriately adjusted in the range of 10 to 40 g / m ² in terms of dry mass. When the application amount of the pressure-sensitive adhesive is less than 10 g / m ² , the effect as the pressure-sensitive adhesive is poor, and when it exceeds 40 g / m ² , the effect is saturated, which is not economically preferable. In addition, as a method of apply | coating an adhesive, a reverse roll coater, a reverse gravure coater, a barrio gravure coater, a knife coater, a bar coater, a die coater, a curtain coater etc. are mentioned.

  Examples of the surface substrate include cast-coated paper, art paper, coated paper, high-quality paper, thermal paper, inkjet paper, synthetic paper, vapor-deposited paper, various polymer films, and the like. Can be used.

  The present invention will be described more specifically with reference to the following examples. In Examples and Comparative Examples, “part” and “%” indicate parts by mass and “% by mass” unless otherwise specified, and the coating amount, the number of parts, the mixing ratio, and the like are all represented by solid content.

(Example 1)
(1) Surface base material As the surface base material, thermal paper having a basis weight of 78 g / m ² (trade name: “LCB575”, manufactured by Oji Paper Co., Ltd.) was used.

(2) Base paper for release paper A pulp slurry made of LBKP 100% and beating freeness 300 ml csf, sulfuric acid band 0.5%, PAM paper strength agent 0.5% ("Polystron 117" manufactured by Arakawa Chemical Industries), AKD size 0.5% of agent (“Size Pine K-903-20” manufactured by Arakawa Chemical Industries, Ltd.) was added to prepare a paper stock.
This paper stock is made with a long mesh multi-cylinder dryer type paper machine, and the polyvinyl alcohol resin (“A-300” manufactured by Daiichi Kogyo Kagaku Co., Ltd.) is about 1 g / m ² per side with an on-machine gate roll coater. As described above, a base paper for release paper was obtained. Subsequently, the base paper was supercalendered and densified to prepare a base paper for release paper having light transmittance according to the present invention. The moisture conditioning basis weight of the obtained base paper for release paper is 64 g / m ² .

(3) Adhesive sheet Crosslinking reaction of solvent-free silicone resin (“LTC-1056L” manufactured by Toray Dow Corning Silicone) (viscosity at 25 ° C .: 250 mPa · s) with three offset gravure coaters on the above release paper base paper 1 g / m ^{2 was} applied and cured to obtain a release paper.
Next, a pressure-sensitive adhesive (“Nicasol L-501” manufactured by Nippon Carbide Industries Co., Ltd.) was applied to the silicone-coated surface of the release paper so as to have a solid content of 20 g / m ² , and was bonded to the surface substrate to be a pressure-sensitive adhesive sheet. Got.

(Example 2)
A pressure-sensitive adhesive sheet was obtained in the same manner as in Example 1 except that the amount of polyvinyl alcohol resin applied to the base paper for release paper was 0.5 g / m ² .

(Example 3)
A pressure-sensitive adhesive sheet was obtained in the same manner as in Example 1 except that the beating freeness of the base paper for release paper was 200 mlcsf.

Example 4
A pressure-sensitive adhesive sheet was obtained in the same manner as in Example 1 except that the raw material pulp for the release paper was LBKP 70% and NBKP 30%, and the freeness by mixing and beating was 300 mlcsf.

(Example 5)
In the papermaking of the base paper for release paper of Example 3, since the papermaking speed was increased, the texture was slightly deteriorated. Other than that was carried out similarly to Example 1, and obtained the adhesive sheet.

(Example 6)
Same as Example 1, except that 1 g / m ^{2 of} solvent type silicone (“SRX-345” manufactured by Toray Dow Corning Silicone Co., Ltd.) was applied with a bar coater in the silicone resin application to the base paper for release paper. Thus, an adhesive sheet was obtained.

(Comparative Example 1)
An adhesive sheet was obtained in the same manner as in Example 1 except that the beating freeness of the base paper for release paper was changed to 450 mlcsf.

(Comparative Example 2)
A pressure-sensitive adhesive sheet was obtained in the same manner as in Example 1 except that the raw pulp of the release release paper was LBKP 60%, NBKP 40%, and the mixed beating freeness was 450 ml.

(Comparative Example 3)
A pressure-sensitive adhesive sheet was obtained in the same manner as in Example 1 except that the raw pulp for the release paper was LBKP 20% and NBKP 80%, and the mixed beating freeness was 200 mlcsf.

  The air permeability and the squeecht sizing degree of the release paper base paper and the label processing suitability (finishing and adhesive residue) of the pressure-sensitive adhesive sheet were measured by the following methods.

<Base paper for release paper>
-Basis weight: Measured according to JIS P 8124: 1998.
Thickness: Measured according to JIS P 8118: 1998.
Density: Measured according to JIS P 8118: 1998.
Air permeability: JAPAN TAPPI No. It was measured according to 5-2: 2000.
Smoothness: JAPAN TAPPI No. It was measured according to 5-2: 2000.
・ Stick human sizing degree: Measured according to JIS P 8122: 2004.
-Opacity: Measured according to ISO 2471.

<Release paper>
-Thickness of release agent resin single layer: Abundance of constituent atoms of release agent resin is measured in the depth direction by X-ray photoelectron spectroscopy.
-Formation: The formation unevenness of the release paper was measured with a beta formation tester (manufactured by Ambertec) and calculated as a standardized standard deviation.
Formation measurement area: 8cm square, formation measurement pitch 1mm

<Adhesive sheet>
-Appropriateness of rising The roll of the adhesive sheet 220 mm width was scraped off at a speed of 20 m / min with a letterpress rotary printing machine SKP-250A (manufactured by Sankisha), and the presence or absence of the rising was evaluated.
○… No lifting occurred △… Slightly rising ×… Booming occurred

-Adhesive residue evaluation It evaluated by the amount of glue adhering to a roll in the above-mentioned applicability evaluation process.
○: The adhesive residue is inconspicuous △: There is a little adhesive residue ×: The adhesive residue is quite conspicuous

-The phototube suitable adhesive label was put on a paper feed detector with an auto labeler, and it was confirmed whether the phototube was detectable through light.
○: Detection with a phototube is possible.
X: Detection with a phototube is impossible.

-Peeling performance An adhesive label was put on an auto labeler to evaluate the peeling performance when peeling the label.
○: No problem in peeling performance △: Although the peeling performance is slightly inferior, there is no problem in use.
×… There is a problem in peeling performance

-Comprehensive evaluation Comprehensive evaluation was made on label processing aptitude, such as appreciation, adhesive residue, and phototube suitability.
A: Processability is very good.
○: Good processability.
Δ: The processing suitability is slightly inferior, but there is no problem.
×… There is a problem in processing suitability.

  As is apparent from Table 1 and Table 2, Examples 1 to 6 in which LBKP is mainly used to control formation, smoothness, barrier agent type and coating amount, density, and air permeability within a specific range are as follows. This is the degree of penetration of the release resin in a specific range, and there is no problem with the rise, adhesive residue, and phototube suitability.

70% by mass or more of the pulp used for the base paper for release paper is LBKP, and the release paper is soaked in the base paper for release paper not less than 0.8 to 1.5 g / m. By providing a release agent resin single layer thickness of 30 to 150 nm when ² is applied and cured, there is no adhesive residue and no rise, there is no problem with phototube suitability, and a release paper excellent in label processing suitability is provided. Can do.

Claims (6)

A base paper for release paper having phototube suitability, which is made by mixing 70% by mass or more of hardwood bleached kraft pulp with respect to all raw material pulp, and is supercalendered. A release paper, wherein the thickness of the release agent resin single layer when applying and curing 8 to 1.5 g / m ² is 30 to 150 nm.   JAPAN TAPPI Paper Pulp Test Method No. The release paper base paper according to claim 1, wherein the air permeability of the release paper base paper measured according to 5-2: 2000 is 3,000 to 30,000 seconds.   The base paper for release paper according to claim 1 or 2, wherein the release paper base paper measured according to ISO 2471 has an opacity of 50 to 75%.   The peeling according to any one of claims 1 to 3, wherein the standard deviation of the formation unevenness of the release paper after applying and curing the release agent to the release paper base paper is 0.4 or less. paper.   JAPAN TAPPI Paper Pulp Test Method No. The release paper base paper according to any one of claims 1 to 4, wherein the release paper base paper measured according to 5-2: 2000 has a smoothness of 300 to 1,500 seconds.   The release paper according to any one of claims 1 to 5, wherein the release agent resin is a solventless silicone resin.