JP2005163254A - Base paper for release paper, and method for producing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a base paper for release paper with high rigidity used for a release paper for pressure sensitive adhesive label, low in generation of paper powder, having reproducibility and having optical transparency sufficient for position detecting performance by a phototube. <P>SOLUTION: The base paper for release paper is produced in the following steps, a step impregnating 1-20 wt.%. based on paper weight of an acrylic resin having glass transition temperature of 20-100°C in a base paper mainly comprises a chemical pulp having 100-300 ml of Canadian standard drainability as the main component, and forming a filling up layer mainly comprising polyvinyl alcohol and/or starch on at least one side and the base paper has 0.85-1.25 g/cm<SP>3</SP>of density. The release paper is produced by forming a releasing layer on the side with the filling up layer. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a base paper for release paper used for release paper for pressure-sensitive adhesive labels and a method for producing the same, and is strong in paper, has little paper dust, has reproducibility, and particularly for position detection performance in a photoelectric tube. The present invention relates to a base paper for release paper that has no problem light transmittance.

  Adhesive labels are widely used for labels and stickers such as glass containers, plastic containers, and paper containers, stickers, and emblems. This adhesive label usually has a release paper bonded to the opposite side. When the label is affixed to a product container or the like, the release paper is discarded.

  When used in supermarkets, adhesive labels are printed, die-cut and wound into rolls one by one, and automatically weighed products are printed with quantities and barcodes using a printer, peeled off from release paper, and placed in product containers. Affixed. In this case, the difference in light transmittance between the pressure-sensitive adhesive paper and the release paper is used to accurately attach the surface label to the container. For this reason, glassine paper having excellent light transmission is generally used as the release paper.

  Glassine paper is made by pulverizing pulp and applying a water-soluble polymer resin such as polyvinyl alcohol or starch on the surface to which the release agent such as silicone resin is applied to increase the sealing effect of the release agent. In general, the sheet is compressed by a calendar or a super calendar (see Patent Documents 1 to 4).

  The glassine paper is made transparent by increasing the bonding area between fibers by using high beaten pulp and further densifying the paper layer by compression treatment. For this reason, there is a problem that the paper becomes thin and the paper stiffness is lowered, and the paper stiffness is inferior at the time of die-cutting or printing, so that wrinkles and misalignment are likely to occur and work efficiency is inferior.

  Basically, the entire paper layer except for the surface of the paper layer is mainly composed of pulp fibers, so that paper dust is likely to occur when cutting the paper. If a lot of paper dust is generated, printing failure, barcode reading failure, mixing into foods, etc. will be a problem.

  In view of the recent increase in prevention of environmental pollution, the release paper can be disposed of as waste paper after the adhesive paper label is attached to the product container, etc., or can be recycled as waste paper. Is required. However, glassine paper has the disadvantage that it is difficult to disperse in water even when trying to disaggregate, because the fiber pulp is used by extremely beating the pulp of the raw material, and the inter-fiber bond is strengthened by calendaring etc. ing. Furthermore, even if the mechanical treatment is strengthened, the fibers are significantly damaged due to the strengthening of the beating treatment, and the pulp fibers are further damaged by the disaggregation treatment, so it is difficult to reuse them as raw materials for general paper. Met.

Japanese Patent No. 3250340 JP-A-9-31898 JP-A-9-41286 JP-A-9-176990

  In view of the situation as described above, the object of the present invention is to provide a base paper for release paper that has good paper stiffness, less generation of paper dust, has reproducibility, and has light transmittance with no problem in photoelectric tube detection performance. Is to provide.

As a result of intensive studies, the present inventors have determined that a base paper mainly composed of chemical pulp having a Canadian standard freeness of 100 to 350 ml, an acrylic resin having a glass transition temperature of 20 to 100 ° C. per paper weight. It is contained in the range of 1% by weight to 20% by weight, and a sealing layer mainly composed of polyvinyl alcohol and / or starch is provided on at least one side, and the density is 0.85 g / cm ³ or more and 1.25 g / cm ³ or less. It was found that the problem can be solved by setting the range of.

As a method of containing an acrylic resin, the glass transition temperature is different from the surface on which a sealing property-imparting layer mainly composed of polyvinyl alcohol and / or starch is provided by impregnating the base paper with the acrylic resin. However, a method of providing a transparency imparting layer mainly composed of an acrylic resin having a temperature of 20 ° C. or higher and 100 ° C. or lower is preferred. The basis weight is preferably in the range of 40 g / m ^{2 to} 70 g / m ² . The base paper for release paper of the present invention is a sealant-imparting solution containing polyvinyl alcohol and / or starch as a main component on one side of a base paper mainly composed of chemical pulp having a Canadian standard freeness of 100 to 350 ml. The other surface is coated with a transparency imparting liquid mainly composed of an acrylic resin having a glass transition temperature of 20 ° C. or more and 100 ° C. or less, and the density is 0.85 g / cm ³ or more and 1.25 g / cm ^3. It is manufactured by calendering so that it becomes ³ or less.

  According to the present invention, it is possible to obtain a release paper base paper having sufficient release agent sealing properties, strong paper strength, little generation of paper dust, and recyclability.

  The base paper used in the present invention must use delignified wood-based chemical pulp fibers (bleached kraft pulp, bleached sulfite pulp) as a pulp raw material. Either softwood or hardwood can be used as the material. Use of non delignified pulp such as mechanical pulp such as crushed wood pulp or thermomechanical pulp is not preferable because the desired light transmittance cannot be obtained. Pulp beating should be at least 100ml and not more than 350ml with Canadian standard freeness. If the Canadian standard freeness is less than 100 ml, the dewaterability of the wire part at the time of papermaking is significantly reduced, so it is not preferable because the papermaking speed needs to be greatly reduced. Further, if the Canadian standard freeness exceeds 350 ml, the bonding area between the fibers decreases, so even if pressure densification is carried out, the improvement in light transmittance is low, and the desired light transmittance cannot be obtained.

  Regarding the papermaking of the above base paper, within the range that does not affect the quality of the light transmission, release agent sealing and other problems, paper strength enhancers, fixing agents, yield improvers, internal additives such as dyes, and Internal fillers such as calcium carbonate, kaolin, talc, and aluminum hydroxide can be added.

  In the present invention, it is necessary to provide a sealing property-imparting layer mainly composed of polyvinyl alcohol and / or starch on one surface of the base paper in order to impart the sealing property of the release agent and the paper dust suppressing effect. It is. As the polyvinyl alcohol, it is possible to use fully saponified or partially saponified polyvinyl alcohol. Although unmodified starch can be used as starch, enzyme modified starch, oxidized modified starch, and modified starch such as phosphate esterified starch, hydroxyethylated starch, cationized starch, and dialdehyde starch are preferred.

The coating amount of the sealability-imparting layer is preferably 1.0 g / m ² or more and 10.0 g / m ² or less, and more preferably 2.0 g / m ² or more and 8.0 g / m ² or less. When the coating amount is less than 1.0 g / m ² , the release agent's sealability and paper dust suppressing effect are insufficient, and when it exceeds 10 g / m ² , the release agent's sealability is sufficient, but drying is not possible. The load increases, and rolls and canvas stains are generated in the drying process and calendar processing process. In addition to polyvinyl alcohol and starch, it can be used by appropriately selecting from casein, acrylic resin, styrene-acrylic resin, vinyl acetate resin, etc. May be. Moreover, you may contain various auxiliary agents normally used, such as a dispersing agent, a mold release agent, a thickener, a water retention agent, an antifoamer, antiseptic | preservative, and a water-resistant agent.

  In the present invention, in order to impart transparency and a paper dust suppressing effect, the base paper needs to contain an acrylic resin having a glass transition temperature of 20 ° C. or more and 100 ° C. or less. As a method of incorporating an acrylic resin into the base paper, a method of impregnating the base paper with an impregnating liquid mainly composed of an acrylic resin, or a surface of the base paper not provided with the above-described sealing property-imparting layer. There is a method of providing a transparency imparting layer mainly composed of an acrylic resin.

  As the acrylic resin, acrylic resin copolymers such as acrylic polymers and acrylic-styrene copolymers, and modified acrylic resin copolymers can be used alone or in admixture of two or more. The glass transition point of the acrylic resin must be in the range of 20 ° C. or higher and 100 ° C. or lower. When the glass transition point is less than 20 ° C., the resin becomes soft and the paper stiffness is lowered, and the resin has high adhesiveness and is difficult to disaggregate during reproduction. When the glass transition point exceeds 100 ° C., the paper becomes too hard. For example, when the paper passes through a roll or bar having a small diameter, the paper is easily broken or cracked, which is not preferable. Further, for example, when a styrene-butadiene latex is used as the resin other than the acrylic resin, the transparency is lowered, which is not preferable.

  The acrylic resin used in the present invention includes acrylic acid, (meth) acrylic acid ester, and other monomers (styrene, acrylonitrile, acrylamide, methylol acrylamide, vinyl acetate, vinyl versatate, vinyl propionate, and 2 if necessary. -Hydroxyethyl methacrylate, dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate, diethylaminopropyl methacrylate, dimethylaminoethylacrylamide, etc.). As the (meth) acrylic acid ester, those having about 1 to 20 carbon atoms of the constituent alcohol are preferable.

  The content of the acrylic resin is preferably 1% by weight or more and 20% by weight or less per paper weight. When the content of the acrylic resin is less than 1% by weight, the imparting of transparency is insufficient. On the other hand, if it exceeds 20% by weight, transparency is sufficient, but the amount of resin becomes excessive, so the reproducibility is impaired, and in addition, the cost is increased and the practicality is poor. The resin liquid may contain various commonly used auxiliaries such as a dispersant, a release agent, a thickener, a water retention agent, an antifoaming agent, a preservative, and a water resistance agent.

  As a method of containing the acrylic resin, an impregnation method is preferable, and a known impregnation machine such as a size press, a gate roll coater, or a shim sizer can be used.

In the case of providing a transparency-imparting layer mainly composed of an acrylic resin, the coating amount of the transparency-imparting layer is preferably 0.5 g / m ² or more and 5.0 g / m ² or less. If the coating amount is less than 0.5 g / m ² , the transparency is insufficient, and if it exceeds 5.0 g / m ² , the transparency is sufficient, but the reproducibility is increased because the resin amount becomes excessive. In addition, the cost is increased and the utility is poor. The transparency-imparting layer may contain various commonly used auxiliaries such as a dispersant, a release agent, a thickener, a water retention agent, an antifoaming agent, a preservative, and a water-resistant agent.

  Moreover, in order to obtain the transparency and the paper dust suppressing effect, it is preferable that the transparency imparting liquid described above is not only penetrated into the surface layer but also penetrated into the paper layer to some extent. For this reason, it is preferable that the sizing degree of the base paper is 1 second or less, more preferably non-size paper.

  As a method for providing a sealing property-imparting layer and a transparency-imparting layer, it can be applied by a coating machine such as a blade coater, gate roll coater, air knife coater, comma coater or bar coater installed in the middle of the paper making process. It is. Further, after the paper is formed, it can be applied by the above-described coating machine in post-processing. However, so-called on-machine coating using a coating machine installed in a paper machine is preferable because the manufacturing cost can be greatly reduced as compared with the case where the base paper is made by a paper machine and then coated by an off-machine. On the other hand, when impregnating the transparency-imparting solution on-machine and applying the sealing property-imparting layer with an off-coater, the coating amount is lower than when applying the sealing property-imparting layer by on-machine coating. Can be reduced.

The base paper is further subjected to a compression treatment in order to improve the sealing property and light transmittance of the release agent. The compression device can be achieved by using a known calendar, a super calendar, a soft calendar, or the like. The density after the compression treatment needs to be in the range of 0.85 g / cm ³ or more and 1.25 g / cm ³ . When the density is less than 0.85 g / cm ^3, it is not possible to obtain sufficient release agent light transmittance. On the other hand, if it exceeds 1.25 g / cm ³ , the paper becomes too thin and the paper stiffness is lowered. Therefore, the density needs to be 0.85 g / cm ³ or more and 1.25 g / cm ³ or less in order to satisfy the release agent sealing property and the light transmittance while maintaining good paper strength.

Kamikoshi of the base paper for release paper of the present invention preferably Clark broken was measured according to JIS P 8143 paper flow direction is in the range of 45cm ^3/100 or more 80 cm ^3/100 or less. When Clark break is less than 45cm ^3/100, wrinkles or deviation is likely to occur because the paper waist is insufficient at the time of die-cutting and printing. When Clark destroyed is more than 80cm ^3/100, because the paper waist is too hard, or cracked in the paper as it passes through the small guide roll or a corner of the diameter, because the cause delamination undesirable.

The basis weight of the base paper for release paper of the present invention is preferably 40 g / m ² or more and 70 g / m ² or less. If the basis weight is less than 40 g / m ² , the paper becomes insufficient, and wrinkles and misalignments are likely to occur during die cutting and printing. If it exceeds 70 g / m ² , the film becomes too thick and the light transmittance decreases. The light transmittance is preferably 32% or more. If it is less than 32%, the difference in light transmittance between the label and the release paper is so small that it cannot be detected by the phototube and the position cannot be detected.

When producing release paper using the release paper base paper of the present invention, a release agent is coated on the surface of the release paper base paper on which the sealing property-imparting layer is provided to provide the release layer. As the release agent, silicone resin, polyethylene resin, alkyd resin and the like can be used. The coating amount is not particularly limited, but is suitably adjusted in the range of 0.1 g / m ^{2 to} 3.0 g / m ² , preferably 0.5 g / m ^{2 to} 2.0 g / m ² . In addition, when the coating amount is less than 0.1 g / m ² , the peelability is insufficient and the peel becomes heavy, and when it is more than 3.0 g / m ² , the improvement in the peelability reaches a peak and is practical from an economical viewpoint. Poor nature.

  EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited by these. In addition, the part and% in an example show a weight part and weight%, respectively. Further, the coating amount, the number of parts, the mixing ratio, etc. were all expressed in solid content.

  The light transmittance, release agent sealability, paper stiffness, paper dust, and disaggregation property of the base paper for release paper produced in Examples and Comparative Examples were measured and evaluated by the following methods.

<Quality evaluation method>
-Light transmittance: An integrating sphere was attached to a self-recording spectrophotometer UV-3100PC manufactured by Shimadzu Corporation, and the light transmittance of release paper base paper having a wavelength of 960 nm was measured.
-Release agent sealing property: The surface of the release paper base paper coated with the sealing agent was printed with oil-based magic ink, and the degree of back-through of the magic ink on the non-printing surface was visually observed.
Evaluation criteria ○: No show-through, △: Some show-through, XX: Through-out on the entire surface, XX: Through-out on the entire surface in a moment ・ Clear paper (Clark Kowasa): Vertical direction of paper according to JIS P 8143 Was measured.
Paper dust: SEMI standard Doc. No. A rubbing test was carried out in accordance with 2363, and the number per 0.01 ft ^{3 of} paper powder having a diameter of 0.3 μm or more was measured.
-Disaggregation property: The sample was cut into a 1 cm square, subjected to 20 disaggregation treatment with a Tappi standard disaggregator at a sample concentration of 2% and a volume of 2 L, and the degree of disaggregation was visually observed.
Evaluation criteria ○: Good disaggregation, △: Some undissolved material remains, ×: Undissolvable

[Example 1]
Using raw pulp (adjusted Canadian standard freeness to 304 ml) consisting of 70% by weight hardwood bleached kraft pulp (Canadian standard freeness 220 ml) and softwood bleached kraft pulp (Canadian standard freeness 500 ml) , 0.1% by weight of a wet paper strength agent (trade name: WS547, manufactured by Nippon PMC Co., Ltd.) was added, and the pH was adjusted to 4.5 with a sulfuric acid band. went. Subsequently, with a blade coater installed in the middle of the papermaking process, 70 parts of partially saponified polyvinyl alcohol (trade name: PVA217, manufactured by Kuraray Co., Ltd.) and phosphate esterified starch (trade name: MS-) are provided on one side as a texture imparting solution. 4400, manufactured by Nippon Foods Co., Ltd.) 30 parts of a mixed solution was applied so that the coating amount was 5.5 g / m ^2, and on the other side, a gate roll coater also installed in the middle of the papermaking process. Then, 100 parts of an acrylic resin (trade name: EK-61, manufactured by Seiden Chemical Co., Ltd., glass transition temperature: 24 ° C.) as a transparency imparting liquid was applied so that the coating amount was 2.0 g / m ² . In addition, a base paper for release paper having a basis weight of 65 g / m ² was manufactured by pressing and compressing so as to have a density of 1.00 g / cm ³ by a calender at the latter stage of the paper forming process. The release paper base paper was evaluated for light transmittance, release agent sealability, Clark wrinkle, paper dust generation, and disaggregation.

[Example 2]
A base paper for release paper was obtained in the same manner as in Example 1 except that a liquid mixture of 30 parts of partially saponified polyvinyl alcohol and 70 parts of phosphate esterified starch was used as the sealing property-imparting liquid.

[Example 3]
A base paper for release paper was obtained in the same manner as in Example 1 except that a liquid containing 100 parts of partially saponified polyvinyl alcohol was used as the sealing ability-imparting liquid.

[Example 4]
A base paper for release paper was obtained in the same manner as in Example 1 except that 100 parts of phosphoric esterified starch was used as the sealing ability-imparting liquid.

[Example 5]
A base paper produced by the same method as in Example 1 was subjected to acrylic resin (trade name: EK-61, manufactured by Syden Chemical Co., Ltd., glass transition temperature 24 ° C.) by a size press installed in the middle of the paper making process. ) Was impregnated at 5% per paper weight. Subsequently, in a post-process using a blade coater, 30 parts of partially saponified polyvinyl alcohol (trade name: PVA217, manufactured by Kuraray Co., Ltd.) as a sealing coating solution on one side, phosphate esterified starch (trade name: MS-) A mixed solution of 70 parts of 4400, manufactured by Nippon Foods Co., Ltd. was coated at 2 g / m ² . Then, the base paper for release paper having a basis weight of 65 g / m ² was manufactured by pressing and compressing with a super calender so that the density was 1.00 g / cm ³ .

[Comparative Example 1]
A base paper for release paper was obtained in the same manner as in Example 1 except that raw pulp having a Canadian freeness adjusted to 430 ml was used.

[Comparative Example 2]
A release paper base paper was obtained in the same manner as in Example 1 except that the transparency-imparting solution was not applied to one surface of the base paper.

[Comparative Example 3]
A release paper base paper was obtained in the same manner as in Example 1 except that the sealing property-imparting solution was not applied to one side of the base paper.

[Comparative Example 4]
A release paper base paper was obtained in the same manner as in Example 1 except that an acrylic resin having a glass transition temperature of 0 ° C. (trade name: GF-5, manufactured by Nippon NSC Co., Ltd.) was used as the transparency imparting solution.

[Comparative Example 5]
A release paper base paper was obtained in the same manner as in Example 1 except that the calender treatment was performed so that the density was 0.70 g / cm ³ .

[Comparative Example 6]
A base paper for release paper was obtained in the same manner as in Example 1 except that the calender treatment was performed so that the density was 1.3 g / cm ³ .

[Comparative Example 7]
A release paper base paper was obtained in the same manner as in Example 5 except that the sealing property-imparting solution was not applied to one side of the base paper.

[Comparative Example 8]
A release paper base paper was obtained in the same manner as in Example 1 except that a styrene-butadiene latex having a glass transition temperature of 25 ° C. was used as the transparency imparting solution.

  The release paper base paper produced in Examples 1 to 4 and Comparative Examples 1 to 6 were measured for light transmittance, silicone sealability, Clark wrinkle, amount of paper dust, and disaggregation, and the evaluation results are shown in Table 1.

表１から明らかなように、実施例１〜４の剥離紙用原紙は光透過性、目止め性、離解性が良好で、紙腰があり、紙粉の発生量も少なかった。一方、カナダ標準ろ水度が350ｍｌを超えたパルプを使用した比較例１の剥離紙用原紙は、光透過性、目止め性が劣っていた。透明性付与層を設けなかった比較例２の剥離紙用原紙は光透過性が劣り紙粉発生量が多かった。目止め性付与層を設けなかった比較例３の剥離紙用原紙は目止め性が劣り、紙粉発生量が多かった。ガラス転移温度が20℃未満のアクリル系樹脂を使用した比較例４の剥離紙用原紙は離解性が劣っていた。密度が0.85ｇ／ｃｍ^３未満である比較例５の剥離紙用原紙は光透過性、目止め性が劣り、紙粉発生量が多かった。密度が1.25ｇ／ｃｍ^３を超えた比較例６の剥離紙用原紙は紙腰及び離解性が劣っていた。目止め性付与層を設けなかった比較例７の剥離紙用原紙は目止め性が劣っていた。透明性付与層にスチレン−ブタジエン系ラテックスを使用した比較例８の剥離紙用原紙は光透過性が劣っていた。

As is clear from Table 1, the release paper bases of Examples 1 to 4 had good light transmittance, sealing properties, and disaggregation properties, had a low level of paper, and generated less paper dust. On the other hand, the base paper for release paper of Comparative Example 1 using pulp having a Canadian standard freeness of more than 350 ml was inferior in light transmittance and sealability. The base paper for release paper of Comparative Example 2 in which the transparency imparting layer was not provided was inferior in light transmittance and generated a large amount of paper dust. The base paper for release paper of Comparative Example 3 in which the sealability-imparting layer was not provided was inferior in sealability and generated a large amount of paper dust. The base paper for release paper of Comparative Example 4 using an acrylic resin having a glass transition temperature of less than 20 ° C. was inferior in disaggregation. The base paper for release paper of Comparative Example 5 having a density of less than 0.85 g / cm ³ was inferior in light transmission and sealing properties, and produced a large amount of paper dust. The base paper for release paper of Comparative Example 6 having a density exceeding 1.25 g / cm ³ was inferior in paper stiffness and disaggregation. The base paper for release paper of Comparative Example 7 in which the sealability-imparting layer was not provided had poor sealability. The base paper for release paper of Comparative Example 8 using a styrene-butadiene latex for the transparency imparting layer was inferior in light transmittance.

Claims (5)

A range of 1% by weight to 20% by weight of acrylic resin with a glass transition temperature of 20 ° C or higher and 100 ° C or lower on a base paper composed mainly of chemical pulp with a Canadian standard freeness of 100ml to 350ml. Release paper, characterized in that a sealing property-imparting layer comprising polyvinyl alcohol and / or starch as a main component is provided on at least one surface of the ink and has a density of 0.85 g / cm ³ or more and 1.25 g / cm ³ or less. Base paper. Canadian standard freeness is 100ml or more and 350ml or less chemical pulp as the main component is provided with a sealant-imparting layer with polyvinyl alcohol and / or starch as the main component on one side and glass transition temperature on the other side. A base paper for release paper, which is provided with a transparency imparting layer mainly composed of an acrylic resin having a temperature of 20 ° C. or higher and 100 ° C. or lower and a density of 0.85 g / cm ³ or more and 1.25 g / cm ³ or less. A release paper provided with a release layer on the surface of the release paper base paper according to claim 1 provided with a sealing property-imparting layer. Apply a sealant-imparting solution mainly composed of polyvinyl alcohol and / or starch on one side of a base paper composed mainly of chemical pulp with a Canadian standard freeness of 100 ml to 350 ml and glass on the other side. Applying a transparency-imparting liquid mainly composed of an acrylic resin having a transition temperature of 20 ° C. or higher and 100 ° C. or lower, and calendering so that the density becomes 0.85 g / cm ³ or higher and 1.25 g / cm ³ or lower. A method for producing a base paper for release paper. A base paper mainly composed of chemical pulp with a Canadian standard freeness of 100 ml to 350 ml is impregnated with an acrylic resin using an impregnation machine, and a sealing layer is provided on at least one surface of the base paper, and the density is 0.85 g. A method for producing a base paper for release paper, which is calendered so as to be not less than / cm ^{3 and not} more than 1.25 g / cm ³ .