JP2017078230A - Base paper for release paper and manufacturing method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an excellent base paper for release paper, which can suppress curl after printing immediately after printing by heating by such as an electrophotography printer or a heat-sensitive printer from occurring, can suppress a blank curl before printing under high humidity environment from occurring, and has less adhesive deposit.SOLUTION: A base paper for release paper includes a base paper made of pulp fiber having canadian standard freeness according to at least JIS 8121 of 100 to 300 ml, and has an undercoat layer on one surface of the base paper and a back surface layer on the other surface, an ash content based on JIS 8251:2003 of the base paper being 5 to 20%, the undercoat layer containing an aqueous adhesive mainly made of α-olefin modified polyvinyl alcohol and a tabular pigment, the back surface layer containing an aqueous adhesive.SELECTED DRAWING: None

Description

  The present invention relates to a base paper for release paper suitable for an adhesive sheet and a method for producing the same.

  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 as release paper, for example, high-density base paper such as glassine paper composed of a base paper containing pulp fibers, clay-coated paper, polyethylene laminated paper, etc. A base paper for release paper is used. A base paper for release paper is widely used in which a release agent layer is formed by applying a release agent such as a silicone resin or a fluorine compound on the surface on which an adhesive layer is laminated. As the release agent, a solventless silicone resin is usually used from the viewpoints of release 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.

  These pressure-sensitive adhesive sheets are printed under the influence of the heat roll used for fixing the toner when printing from the surface substrate side with an electrophotographic printer, and when printing with a thermal printer, Curling is likely to occur, which is a cause of trouble that causes poor paper feeding and poor paper alignment during paper ejection.

  In recent years, these pressure-sensitive adhesive sheets have been used to make unnecessary parts around the punched labels (hereinafter referred to as “粕”) as thin and small as possible, especially for commercial and industrial labels, from the viewpoint of resource saving. In order to increase productivity and productivity, 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 peeling force. However, the label that should be left on the release paper may be removed together (hereinafter referred to as “lifting”). It becomes a cause of trouble.

  In addition, if there is a pinhole or recess on the release paper side in the process of applying the adhesive to the release paper, it will become an adhesive sheet with the adhesive in the release paper, and the adhesive will adhere in the printing / labeling process When the surface substrate is peeled from the release agent 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 Patent Document 1, a pressure-sensitive adhesive sheet is formed by laminating a surface base material, a pressure-sensitive adhesive, a release agent, an undercoat agent, and a release substrate, and the surface base material and / or the release substrate is measured with a measuring instrument using a microwave method. The ratio of the maximum value and the minimum value of the transmitted microwave intensity is 1.0 to 1.3, and the main component of the primer is at least one kind of (meth) acrylic acid ester having a hydroxyl group in the molecule, and this A pressure-sensitive adhesive sheet made of a copolymer and a pigment obtained by emulsion copolymerization with at least one other vinyl-based monomer copolymerizable with is proposed. However, although the pressure-sensitive adhesive sheet is considered for the paper passing suitability in the printer due to the slanting of the paper in the non-impact printer of the print heating and fixing method and the sticking out of the pressure-sensitive adhesive, the small-sized adhesive sheet in the printer is used. The paper feeding performance and the paper alignment at the time of paper ejection were not taken into consideration and were insufficient.

  In Patent Document 2, in a pressure-sensitive adhesive sheet obtained by sequentially laminating a release substrate, a release agent, a pressure-sensitive adhesive, and a surface base material, (a) a glass transition temperature of an ethylenically unsaturated carboxylic acid-containing monomer and (b) a homopolymer An ethylenically unsaturated bond-containing monomer having a temperature of 50 ° C. or higher, and (c) another monomer copolymerizable with these monomers (provided that at least one of the monomers (b) and (c)) A glass transition temperature of an acrylate copolymer emulsion obtained by emulsion copolymerization (including an acrylate monomer on one side) is 0 to 100 ° C., and a treatment liquid mainly comprising the copolymer emulsion An adhesive sheet formed by applying or impregnating a surface of the surface base material on which the adhesive is not laminated and applying or impregnating a treatment liquid mainly composed of a water-soluble plasticizer on the surface of the release substrate on which the release agent is not laminated. Proposed. However, in printing with a high-speed electrophotographic printer, it is insufficient to suppress the occurrence of curling after printing, and there remains a problem in paper alignment at the time of paper discharge. In addition, the surface of the release substrate on which the release agent is not laminated may be reduced in surface strength by bleeding of the water-soluble plasticizer, printing with flexo ink, offset ink and gravure ink may be impaired, or blocking may occur. There is a problem of poor printability.

  In Patent Document 3, in an electrophotographic pressure-sensitive adhesive sheet obtained by laminating at least a release agent layer, a pressure-sensitive adhesive layer, and a surface substrate on a release substrate, water having a glass transition temperature of −10 to 70 ° C. is formed on the surface of the surface substrate. An electrophotographic pressure-sensitive adhesive sheet proposed by applying or impregnating a treatment liquid containing a dispersible polymer as a main component and having a Beck smoothness (JIS P 8119) of the surface base material of 80 seconds / 10 cc or more is proposed. However, in printing with a high-speed electrophotographic printer, it is insufficient to suppress the occurrence of curling after printing, and there remains a problem in paper alignment at the time of paper discharge.

JP-A-7-102500 Japanese Patent Laid-Open No. 3-179071 Japanese Patent Laid-Open No. 2-245082

  The present invention suppresses curling after printing immediately after printing by heating, such as an electrophotographic printer or a thermal printer, suppresses blank paper curling before printing in a high humidity environment, and is excellent in base paper for release paper without adhesive residue The main purpose is to provide

  The present inventors have intensively studied the feeding property of the pressure-sensitive adhesive sheet in a printer having a heating means such as an electrophotographic printer and the paper alignment property at the time of paper discharge. As a result, by controlling the ash content of the release paper base paper constituting the adhesive sheet within a predetermined range, curling after printing is suppressed, and an adhesive sheet excellent in paper feedability and paper alignment at the time of paper discharge is obtained. The present invention has been reached. That is, the present invention has the following configuration.

  Item 1: A base paper made of pulp fibers having a Canadian freeness of 100 to 300 ml according to JIS P 8121, a base paper for release paper having an undercoat layer on one side of the base paper and a back layer on the other side. Wherein the base paper has an ash content of 5 to 20% based on JIS P 8251: 2003, and the undercoat layer contains an aqueous adhesive mainly composed of α-olefin-modified polyvinyl alcohol and a plate pigment, A base paper for release paper, wherein the back layer contains an aqueous adhesive.

  Item 2: The main component of the aqueous adhesive contained in the back layer is at least one selected from the group consisting of starch and derivatives thereof, polyvinyl alcohol, modified polyvinyl alcohol, and styrene-butadiene copolymer latex. 2. A base paper for release paper according to 1.

  Item 3: The base paper for release paper according to Item 1 or 2, wherein the undercoat layer and the back surface layer contain different water-based adhesives as main components of the water-based adhesive.

  Item 4: The release paper according to any one of items 1 to 3, wherein the release paper base paper composed of the base paper, the undercoat layer, and the back layer has a steecht degree according to JIS P 8122 of 5 seconds or more. Base paper.

  Item 5: JAPAN TAPPI Paper Pulp Test Method No. Item 5. The base paper for release paper according to any one of Items 1 to 4, wherein the Oken air permeability according to 5-2: 2000 is 10,000 to 100,000 seconds.

  Item 6: The base paper for release paper according to any one of Items 1 to 5, further comprising a printing layer containing at least one selected from the group consisting of flexographic ink, offset ink and gravure ink on the back layer.

  Item 7: A method for producing a base paper for release paper having a base paper composed of at least pulp fibers, an undercoat layer on one side of the base paper, and a back layer on the other side, which are different from each other as a main component of the aqueous adhesive Using an undercoat layer coating solution and a back layer coating solution containing an aqueous adhesive, simultaneously applying and drying to form an undercoat layer on one side of the base paper and a back layer on the other side A method for producing a base paper for release paper, comprising:

  Item 8: The method according to Item 7, wherein the step includes a step of simultaneously applying with a film transfer coater, and the film transfer coater is any one of a gate roll coater, a rod metering size press coater, and a blade metering size press coater. A method for producing a base paper for release paper.

  The base paper for release paper of the present invention is curl after printing immediately after printing by heating, such as an electrophotographic printer or a thermal printer, suppresses blank paper curl before printing in a high humidity environment, and has no adhesive residue This is a base paper for release paper. In addition, the barrier property on the release agent layer side is increased, the stability of the release force is excellent, and the printability on the side opposite to the release agent layer is excellent.

  An embodiment of the present invention will be described. However, embodiments of the present invention are not limited to the following embodiments.

  The base paper for release paper of the present invention has a base paper made of pulp fibers having a Canadian freeness of 100 to 300 ml according to JIS P 8121. If the Canadian standard freeness (beatability) is less than 100 ml, blank paper curl before printing becomes a problem in a high humidity environment. On the other hand, if it is larger than 300 ml, the coating solution for the undercoat layer is likely to permeate, a uniform undercoat layer is not formed, and an adhesive residue is generated. Moreover, by setting it as the range of 100-300 ml, it has moderate paper interlayer intensity | strength and can provide light transmittance to the base paper for release paper. A known method can be used as a method for beating the pulp in order to bring the Canadian standard freeness (beatability) to a desired range.

  The base paper can be obtained by making paper using pulp fibers. As pulp to be used, hardwood bleached kraft pulp (hereinafter abbreviated as LBKP), softwood bleached kraft pulp (hereinafter abbreviated as NBKP), and waste paper pulp can be appropriately mixed and used. Waste paper pulp includes DIP and waste products generated in the papermaking process. Considering the uniformity of formation, it is preferable that the ratio of LBKP is large. The pulp raw material is not limited to wood pulp, and synthetic pulp made of any synthetic fiber, non-wood pulp such as hemp and kenaf, and the like can be blended as necessary.

  In the present invention, the ash content of the base paper based on JIS P 8251: 2003 is 5 to 20%. Preferably, the ash content is 5 to 15%. When the ash content is less than 5%, the occurrence of curling after printing is remarkable. In the present invention, the expansion and contraction of the base paper can be suppressed by containing a specific amount of ash. Thereby, immediately after printing, shrinkage of the base paper for release paper can be suppressed, and curling after printing curled to the base paper for release paper on the side opposite to the print surface of the adhesive sheet can be suppressed. On the other hand, when the ash content exceeds 20%, adhesive residue is generated. Further, the barrier property against a release agent such as a silicone resin is lowered, resulting in heavy peeling, and the peeling force is increased with time, so that the stability is impaired.

  The ash content can be adjusted by internally adding a filler to the base paper. Examples of fillers include titanium dioxide, kaolin, talc, heavy calcium carbonate, light calcium carbonate, calcium sulfite, gypsum, calcined kaolin, white carbon, amorphous silica, delaminated kaolin, diatomaceous earth, magnesium carbonate, aluminum hydroxide. And inorganic pigments such as calcium hydroxide, magnesium hydroxide, and zinc hydroxide. Among these, at least one selected from the group consisting of talc, titanium dioxide, and kaolin is preferable. In addition, organic pigments such as urea / formalin resin particles and fine hollow particles may be internally added as a filler. Fillers contained in waste paper and waste paper can be reused. The light transmittance of the base paper for release paper greatly affects the phototube suitability of the pressure-sensitive adhesive sheet, and the light transmittance varies depending on the hue and basis weight of the base paper for release paper, so it can be suitably adjusted by adjusting the ash content. .

  The base paper can contain a sizing agent. Since the base paper contains a sizing agent, when applying the undercoat layer described later to the base paper, it is possible to provide a uniform undercoat layer near the surface without excessive penetration of the undercoat layer coating liquid. It becomes. The sizing agent is originally added for the purpose of preventing the ink from bleeding, but the present invention has found that it has the above-mentioned new effects.

  Specific examples of the sizing agent include rosin, alkyl ketene dimer, alkenyl succinic anhydride, styrene-acrylic, higher fatty acid, and petroleum resin. In order to ensure printability and maintain surface properties, papermaking in an acidic pH region is preferable. A rosin-based sizing agent is preferred for imparting sufficient sizing properties in the acidic pH region. It is preferable that content of a sizing agent is 0.3 mass part or more with respect to 100 mass parts of pulp fibers of a base paper. By setting the content of the sizing agent to 0.3 parts by mass or more, the sizing degree of the release paper base paper is increased, and an appropriate air permeability can be obtained. The preferred sizing agent content is in the range of 0.4 to 1.5 parts by mass, and the more preferred sizing agent content is in the range of 0.5 to 1.0 part by mass.

  In addition to pulp, filler, and sizing agent as necessary, the paper includes a paper strength enhancer, a yield improver, a pH adjuster, a drainage improver, a wet paper strength agent, colored dyes and pigments, and other internal additives for papermaking. Auxiliaries can be added as needed.

  Specific examples of the paper strength enhancer include anionic polyacrylamide, cationic polyacrylamide, amphoteric polyacrylamide, cationic starch, graft copolymer of polyacrylamide and starch, various modified starches, urea resin, polyamide and polyamine resin. , Polyvinyl alcohol, polyethylene oxide and the like. In order to achieve high paper interlayer strength, at least one selected from anionic polyacrylamide, cationic polyacrylamide, amphoteric polyacrylamide, cationic starch, and a graft copolymer of polyacrylamide and starch is preferable.

  Specific examples of the yield improver include polyacrylamide compounds, polyethylene glycol compounds, and polyvinylamine compounds. When titanium dioxide is used as the filler, the overall yield is lowered and the productivity is easily lowered. Therefore, an appropriate yield improver is appropriately selected in order to maintain the productivity.

  Specific examples of pH adjusting agents include sulfuric acid band, aluminum chloride, sulfuric acid, hydrochloric acid, sodium aluminate, basic aluminum compound, sodium hydroxide, potassium hydroxide, ammonia, various primary, secondary, and tertiary. Examples include alkaline compounds such as secondary amines. From the viewpoint of versatility and economy, a sulfuric acid band, sulfuric acid and sodium hydroxide are preferred.

  In order to make the thickness of the release agent layer uniform, it is desirable that the base paper of the release paper base paper is well formed. Compared with NBKP, LBKP is relatively thin and short, has few pinholes, and easily forms a uniform texture. In order to form a uniform formation with few pinholes, the blending amount of LBKP is preferably 70% by mass or more of the total raw material pulp. By setting it as 70 mass% or more, even if it apply | coats release agent resin, a pinhole does not remain and there is no possibility of causing the adhesive 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.

  The base paper for release paper of the present invention has an undercoat layer on one side of the base paper. The undercoat layer contains an aqueous adhesive mainly composed of α-olefin-modified polyvinyl alcohol and a plate pigment. Thereby, it is possible to control the release agent so as to remain uniformly on the surface of the base paper, to stabilize the release force, and to suppress the occurrence of adhesive residue. Here, the main component is a main component among the constituent components, and generally means containing about 30% by mass or more of the whole.

  As a constituent component of the main chain of the α-olefin-modified polyvinyl alcohol, a polymer obtained by saponifying a polymer containing 80 mol% or more of a vinyl ester typified by a vinyl acetate monomer is preferably used. Since α-olefin-modified polyvinyl alcohol has good film-forming properties, it becomes a film with few pinholes, and it is possible to increase the Oken type air permeability of the base paper for release paper. Moreover, since it is excellent also in barrier property and transparency, it is preferably used.

  When producing α-olefin modified polyvinyl alcohol, vinyl esters other than vinyl acetate, such as vinyl formate, vinyl acrylate, vinyl butyrate, vinyl crotonic acid, vinyl chloroacetate, vinyl oleate, vinyl propionate, vinyl caproate Of course, saturated fatty acid vinyl esters such as vinyl caprylate, vinyl caprate, vinyl laurate, vinyl myristate, vinyl palmitate, vinyl stearate, vinyl pivalate, vinyl versatate can be used instead of vinyl acetate. It is.

  The saponification degree of the α-olefin-modified polyvinyl alcohol in the present invention is present before saponification from the viewpoint that the effect of improving the permeability and adhesive residue of the release agent resin of the obtained resin composition is exhibited to a higher degree. The saponification degree is preferably 80 to 100% in terms of the molar ratio of the saponified ester group to the ester group. From the viewpoint of moisture resistance, the degree of saponification is preferably 90% or more, more preferably 95% or more, and most preferably 98% or more.

  As a comonomer component used in an amount of 1 to 20 mol% in addition to the vinyl ester, for example, an α-olefin having 2 to 20 carbon atoms such as ethylene, propylene, isobutylene, 1-butene, 1-pentene, 1-hexene and the like. Can be mentioned. Among these, ethylene is particularly preferably used because it improves the solvent resistance, release agent resin penetration-preventing property and the like of the resulting resin composition and provides a resin composition with excellent characteristics.

  In the present invention, an ethylene-modified polyvinyl alcohol obtained by copolymerizing an α-olefin, particularly ethylene, is preferable because it exhibits good solvent resistance against various solvents such as toluene, methyl ethyl ketone, and hexane. In particular, modified polyvinyl alcohol copolymerized in the ethylene copolymerization ratio range of 1 to 20 mol% is preferable because of excellent balance of solvent resistance, punching workability and the like. When the copolymerization ratio of ethylene is in the range of 1 to 15 mol%, the re-disintegration property of the release paper base paper is remarkably improved, and is several times that of the conventionally used modified polyvinyl alcohol resins other than the α-olefin modified resins. Since it exhibits a degree of re-disaggregation, it is excellent in suitability for recycling as paper after use as release paper. In particular, a base paper for release paper provided with an undercoat layer containing a modified polyvinyl alcohol copolymerized with ethylene in the range of 1 to 9 mol% is most excellent in solvent resistance and punching workability and is optimal. As a method for copolymerization of α-olefin, the comonomer may be copolymerized in the main chain of polyvinyl alcohol, or may be graft-polymerized on the main chain of polyvinyl alcohol.

  The degree of polymerization of ethylene-modified polyvinyl alcohol in the present invention is preferably in the range of 200 to 8000 from the viewpoints of solvent resistance and punching suitability. The degree of polymerization is more preferably in the range of 300 to 2500, further preferably in the range of 400 to 2000, and most preferably in the range of 500 to 1800.

  The type of plate pigment is not particularly limited, and inorganic pigments such as kaolin, talc, illite, mica, artificial mica, calcium carbonate, titanium dioxide, aluminum hydroxide, and silica can be appropriately selected and used. In the case of close-packing the pigment, a plate-like pigment is generally used as compared with a spherical pigment, so that the porosity is generally reduced and a dense coating layer can be formed, which is preferable in terms of quality.

  As the plate pigment, those having an aspect ratio of 7 or more are preferable. Since the plate-like pigment having an aspect ratio of 7 or more is oriented in the plane direction when applied, it is possible to easily obtain a coating layer having excellent barrier properties and smoothness. Here, the aspect ratio can be obtained by measuring the thickness of the tabular pigment by observation with an electron microscope and dividing the volume average particle diameter of the tabular pigment by the thickness. At this time, the volume average particle size can be determined using, for example, a laser diffraction particle size distribution meter (manufactured by Nikkiso Co., Ltd., “Microtrack MT-3000”).

  The average particle size of the plate pigment is preferably 0.2 to 10 μm because of excellent barrier properties and smoothness. The plate pigment preferably has an aspect ratio of 7 or more as shown in the previous section. Further, the plate pigment is preferably excellent in light transmittance. Examples of the plate pigment having an aspect ratio of 7 or more preferably used in the present invention include kaolin, talc, illite, mica, artificial mica, and aluminum hydroxide.

  The content of the plate pigment and α-olefin-modified polyvinyl alcohol in the undercoat layer is preferably 50 to 300 parts by mass of α-olefin-modified polyvinyl alcohol with respect to 100 parts by mass of the plate pigment. More preferably, it is 50-200 mass parts. By setting the content of the α-olefin-modified polyvinyl alcohol to 300 parts by mass or less, contamination of the cylinder dryer immediately after coating can be reduced. Moreover, the effect of improving the adhesive residue can be obtained by improving the coating of the pinhole with the plate pigment. On the other hand, by setting the content of the α-olefin-modified polyvinyl alcohol to 50 parts by mass or more, the space between the pigment and the pigment can be sufficiently filled with the α-olefin-modified polyvinyl alcohol, and the generation of fine voids can be suppressed. The effect of suppressing the penetration of the coating liquid into the coating layer and the substrate can be enhanced.

The coating amount of the undercoat layer is preferably 0.5 to 4.0 g / m ² in terms of dry mass. By setting it to 0.5 g / m ² or more, the penetration preventing effect of the release agent becomes sufficient, and it is possible to suppress an increase in the release force. On the other hand, by setting it as 4.0 g / m < ² > or less, it can suppress effectively that peeling force becomes small too much and a rise is generated.

  For the undercoat layer, for example, an undercoat layer coating solution prepared by mixing and stirring α-olefin-modified polyvinyl alcohol and a plate-like pigment, and, if necessary, an auxiliary agent, with water as a dispersion medium, has the above coating amount. In addition, it is formed by applying and drying on one side of the base paper.

  The base paper for release paper of the present invention has a back layer on the other side of the base paper. The back layer contains an aqueous adhesive. Thereby, curl can be controlled effectively in the presence of the aqueous adhesive of the undercoat layer. In addition, the surface strength on the back layer side can be increased, and excellent printability can be obtained. Here, the printing applied to the back layer is printing using ink such as flexographic ink, offset ink or gravure ink. In the present invention, the main component of the aqueous adhesive contained in the back layer is at least one selected from the group consisting of starch and derivatives thereof, polyvinyl alcohol, modified polyvinyl alcohol, and styrene-butadiene copolymer latex. preferable. Among these, starch and its derivatives are preferable. Thereby, roll dirt of a paper machine, a coater, a calendar, etc. which a back surface layer contacts can be controlled, and the printability to a back surface layer can be improved. Further, fluffing of the base paper and picking during printing can be effectively suppressed.

  A pigment can also be contained in the back layer. The pigment may be appropriately selected from pigments (fillers) that can be contained in the base paper or the undercoat layer. Among these, kaolin is preferable because it is excellent in printability. The content ratio of the aqueous adhesive to the pigment in the back layer (aqueous adhesive: pigment) is preferably about 100: 0 to 50:50 in terms of solid content from the viewpoint of increasing surface strength and improving printability.

The back layer is, for example, a coating solution for the back layer prepared by mixing and stirring an aqueous adhesive, if necessary, a pigment, an auxiliary agent, etc., with water as a dispersion medium, and the coating amount is preferably 0.5 to 3.0 g / ^{m 2,} more preferably about so that 0.5 to 2.0 g / ^{m 2} approximately, is formed by coating and drying on the other surface of the base paper.

  In the present invention, since the curl after printing can be adjusted by including a specific ash content in the base paper, the undercoat layer and the back layer can contain different aqueous adhesives as the main component of the aqueous adhesive. Thereby, the barrier property can be imparted to one surface as a different function between the front and back surfaces of the release paper base paper, and the printability can be imparted to the other surface. Further, even if the release paper base paper is stored in a wound state, there is no risk of blocking on the front and back sides.

  In the release paper base paper of the present invention, it is preferable that the stipet sizing degree according to JIS P 8122: 2004 of the release paper base paper comprising a base paper, an undercoat layer and a back layer is 5 seconds or more. More preferably, it is 7 seconds or more. Thereby, the penetration of the release agent and the pressure-sensitive adhesive can be adjusted appropriately, and the release force can be adjusted so that no adhesive residue occurs. Although the upper limit of the Steecht sizing degree is not particularly limited, it is preferably 20 seconds or shorter, more preferably 15 seconds or shorter from the viewpoint of suppressing the occurrence of rising when scoring at higher speed. The degree of sizing of the release paper base paper can be controlled by the type and content of the sizing agent, the composition of the undercoat layer and the back layer, the smoothing treatment, and the like.

  In this invention, it is a base paper for release paper which can further be equipped with a release agent layer, an adhesive layer, and a surface base material from the side near a base paper on an undercoat layer. That is, the pressure-sensitive adhesive sheet includes at least a surface base material, a pressure-sensitive adhesive layer, a release agent layer, an undercoat layer, a base paper, and a back surface layer in this order.

  In this invention, it is preferable to further provide the printing layer containing at least 1 type chosen from the group which consists of a flexo ink, offset ink, and a gravure ink on the back surface layer on the side far from a base paper. The back layer can increase the surface strength of the base paper and improve the printability for low to high viscosity inks. For this reason, a mode in which a release agent layer is further provided on the undercoat layer of the base paper for release paper, and a print layer containing at least one selected from the group consisting of flexographic ink, offset ink, and gravure ink is further provided on the back surface layer. The effect of the invention can be exhibited without regret, which is preferable.

The basis weight of the base paper for release paper is preferably 40 to 100 g / m ² after humidity control. By setting it as 40 g / m < ² > or more, paper power can be improved and workability can be improved. On the other hand, moderate light transmittance can be provided by setting it as 100 g / m < ² > or less.

  In the present invention, JAPAN TAPPI paper pulp test method no. It is preferable that the Oken type air permeability of the base paper for release paper according to 5-2: 2000 is in the range of 10,000 to 100,000 seconds. By setting the Oken-type air permeability of the base paper for release paper to 10,000 seconds or more, the adhesive residue can be effectively suppressed even when a base paper containing ash is used. On the other hand, by setting it to 100,000 seconds or less, it is possible to eliminate the uneven distribution of moisture in a high humidity environment, and to effectively suppress blank paper curl. Preferably it is 40,000 seconds or less.

  Moreover, as a technique for controlling the surface of the base paper for release paper so as to be uniformly coated with a release agent such as silicone resin, JAPAN TAPPI paper pulp test method No. 1 is used. The Oken type smoothness of the base paper for release paper according to 5-2: 2000 can be used. That is, the release agent can be effectively coated on the surface of the base paper by setting the Oken type smoothness of the base paper for release paper to 300 seconds or more. On the other hand, by setting the Oken type smoothness to 3,000 seconds or less, it is possible to prevent the peeling force from becoming too light and easily rising. The Oken type smoothness of the base paper for release paper is more preferably 500 to 2,000 seconds, and still more preferably 700 to 1,200 seconds.

  The method for making the base paper is not particularly limited, and the paper may be made using a paper material containing pulp fiber and filler, and if necessary, other auxiliary agents. The paper machine is not particularly limited, and the paper machine is made under acidic or neutral conditions by, for example, a long paper machine, a twin wire paper machine, an on-top paper machine, a short paper machine, a circular paper machine, a Yankee paper machine, or the like.

  The present invention is a method for producing a base paper for release paper, which is a base paper made of at least pulp fibers, a method for producing a base paper for release paper having an undercoat layer on one side of the base paper and a back layer on the other side. And using an undercoat layer coating solution and a back layer coating solution containing different aqueous adhesives as the main component of the aqueous adhesive, and simultaneously applying and drying to undercoat on one side of the base paper Forming a back layer on the other side of the layer. That is, both sides are simultaneously applied and dried to form an undercoat layer and a back layer. Thereby, curling after printing is controlled, and process management becomes easy. On the other hand, when different coating layers are formed on the front and back surfaces by applying them to the front and back sequentially, the number of processes increases and productivity decreases, and the behavior of blank paper curl varies from process to process. It is difficult to predict the desired post-print curl while managing the curl.

  In the present invention, the step of simultaneously applying and forming a layer includes the step of simultaneously applying with a film transfer coater, and the film transfer coater is either a gate roll coater, a rod metering size press coater or a blade metering size press coater. Preferably there is. By using these on-machine, the base paper before the calendar process can retain high moisture and increase the operation efficiency.

  In the present invention, it is possible to increase the density of the base paper for release paper by applying the undercoat layer and the back surface layer to the base paper, and then drying and smoothing using a calendar roll. The light transmittance of the paper base paper can be improved. Moreover, it is possible to make the undercoat layer excellent in barrier properties with few pinholes, and to prevent the release agent or the adhesive from penetrating into the inside of the release paper base paper. Here, as the calendar treatment, it is preferable to use a plurality of calendar rolls including a metal roll and a resin roll.

As the calendar treatment, it is preferable that the density is in the range of 0.7 to 1.2 g / cm ³ in consideration of the expression of light transmittance. More preferably, it is the range of 0.8-1.2 g / cm < ³ >. High-temperature multi-stage pressurization with a super calendar that facilitates higher density is preferred. The super calender is a technique in which calender rolls composed of metal rolls and resin rolls are alternately arranged in about 10 to 20 stages and calendered continuously. The smoothing process can be performed on-machine or off-machine using a smoothing apparatus such as a gloss calender, multi-nip calender, soft calender, belt nip calender, etc. in addition to a super calender. By performing the smoothing treatment, the transfer rate of the release agent is improved and the peelability is improved.

  When performing the smoothing process using a calendar roll, it is preferable to perform the smoothing process with 10% to 20% moisture held on the release paper base paper, because it is easier to achieve high density. The water content of the base paper for release paper after the smoothing treatment is preferably 4.5 to 7.5% by mass. As a more preferable range, it is 5.0-7.0 mass%, and 5.5-6.5 mass% is still more preferable.

  In the present invention, a release resin is applied to the release paper base paper in the paper quality range as described above and dried to form a release agent layer, thereby forming the release paper. Examples of the release resin in the present invention generally include silicone resins, fluororesins, amino alkyd resins, polyester resins, etc., but are usually aqueous emulsion type, solvent type or solventless type from the viewpoint of release quality and price. Silicone resin is used. In particular, switching from an aqueous emulsion type to a solventless type is proceeding from the viewpoint of environmental considerations 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 resin include a bar coater, an air knife coater, a direct gravure coater, an offset gravure coater, and a multi-stage roll coater.

The coating amount of the release agent resin is preferably 0.5 to 1.5 g / m ² . When the coating amount is 0.5 g / m ² or more, the peeling performance is sufficient, and there is no possibility of frequent breakage during label processing. On the other hand, by setting it as 1.5 g / m < ² > or less, there is no possibility that the peeling force becomes too light and the rising frequently occurs. 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 manufacturing the 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. As the pressure-sensitive adhesive, for example, natural rubber, styrene-butadiene copolymer, styrene-isopropylene block copolymer, recycled rubber, synthetic rubber, and other rubber-based, acrylic-based, and silicone-based pressure-sensitive adhesives 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. By setting the application amount of the pressure-sensitive adhesive to 10 g / m ² or more, there is no possibility that label lifting occurs when the adhesive strength is increased and the label is applied to various adherends. On the other hand, by setting it to 40 g / m ² or less, there is no possibility that the pressure-sensitive adhesive protrudes from the cross-section of the pressure-sensitive adhesive sheet during label punching, and the pressure-sensitive adhesive accumulates to stain or damage the printed surface of the label. 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 surface substrates include cast coated paper, art paper, coated paper, high-quality paper, thermal paper, inkjet paper, thermal transfer paper, synthetic paper, vapor-deposited paper, various polymer films, etc., depending on the application and purpose. It can be appropriately selected and used.

  The present invention will be described in more detail with reference to examples, but the present invention is not limited thereto. Unless otherwise specified, “parts” and “%” represent “parts by mass” and “mass%”, respectively.

-Preparation of ethylene-modified polyvinyl alcohol A pressure-resistant reaction vessel equipped with a stirrer, thermometer, ethylene inlet tube, nitrogen inlet tube, and cooler was charged with 100 parts of vinyl acetate and 30 parts of methanol, and then purged with nitrogen. Ethylene was injected so that the pressure was 3.0 kg / cm ² . A solution in which 2,2′-azobisisobutyronitrile was dissolved in methanol as a polymerization initiator was prepared, and nitrogen substitution was performed by bubbling with nitrogen gas. The temperature of the reaction vessel charged with the monomer was raised, and when the internal temperature reached 60 ° C., an initiator solution was injected to initiate polymerization. Cooled after 3 hours. Then, it was deethyleneated, and then the unreacted vinyl acetate monomer was removed under reduced pressure to obtain an ethylene-modified methanol solution of polyvinyl acetate. A methanol solution of NaOH (NaOH content of 10% by mass) was added thereto to initiate a saponification reaction. After 1 minute from the addition of the alkaline solution, the resulting gelled product is pulverized with a pulverizer and further allowed to stand for 1 hour to allow the saponification reaction to proceed. Then, methyl acetate is added to the reaction system to remove the remaining alkali. Partially neutralized. White solid-modified polyvinyl alcohol was filtered off, methanol was added thereto, and the mixture was allowed to stand at room temperature for 3 hours, washed, and drained by centrifugation. The denatured polyvinyl alcohol after washing is centrifuged and then dried for 1 day under a nitrogen stream (oxygen concentration 8%) using a drier whose internal temperature is kept at 90 ° C. Got alcohol. The obtained modified polyvinyl alcohol had a polymerization degree of 1200, a saponification degree of 98.6 mol%, and an ethylene modification degree of 2.0 mol%. In the present invention, the degree of polymerization and the degree of saponification were determined according to “3.7 Average degree of polymerization” and “3.5 degree of saponification” in JIS K 6726: 1994 “Testing methods for polyvinyl alcohol”. Further, the degree of ethylene modification was determined by analysis by ¹ H-NMR and ¹³ C-NMR. Regarding the degree of ethylene modification, commercially available ethylene-modified polyvinyl alcohol (manufactured by Kuraray Co., Ltd .: trade name “EVAL L101” or the like) was used as a standard substance.

Example 1
-Preparation of surface base material Blended pulp with 100% LBKP as raw material pulp is adjusted to Canadian standard freeness of 250 ml, and alkenyl succinic acid in terms of solid content with respect to 100 parts by weight of absolutely dry pulp Anhydride (trade name: Fibran 81, manufactured by Arakawa Chemical Co., Ltd.) 0.05 parts by mass, sulfuric acid band 1.0 part by mass, cationic starch (trade name: Pillar Starch P-3T, manufactured by Pillar Starch) 0.6 mass In addition, light calcium carbonate (trade name: Brilliant 15, manufactured by Shiraishi Calcium Co., Ltd.) was added so that the ash content based on JIS P 8251 would be 8%, and the stock was prepared. Made paper. In the papermaking process, a 6.5% solution of starch (trade name: Ace A, manufactured by Oji Cornstarch Co., Ltd.) was size-pressed so as to be ² g / m ^{2 when} both sides of the solid content were combined. The obtained surface base material had a basis weight of 55 g / m ² and a paper thickness of 63 μm.

-Preparation of base paper for release paper Add talc as a filler so that the ash content is 8% in a pulp slurry of Canadian standard freeness 150 ml consisting of 70 parts of LBKP and 30 parts of NBKP, Cationized starch (trade name: “Pillar Starch P-3T”, manufactured by Pillar Starch Co., Ltd.) 0.3 parts by mass as a paper strength agent in terms of solid content with respect to 100 parts by mass of absolutely dry pulp, rosin sizing agent ( Product name: “Size Pine N-776” (manufactured by Arakawa Chemical Industries, Ltd.) Using paper stock with 0.5 parts by mass and 1.0 part by mass of sulfuric acid band, papermaking concentration 0.3% with a long net paper machine The base paper was made. Furthermore, by simultaneous coating on both sides of an on-machine gate roll coater, 40% by mass of α-olefin-modified polyvinyl alcohol (the above-mentioned ethylene-modified polyvinyl alcohol) and kaolin (trade name: “HT” on one side of the obtained base paper in solid content. “Aspect ratio 7; manufactured by Engelhard, Inc.) 60% by mass, a coating solution for an undercoat layer having a concentration of 15% using water as a dispersion medium is applied, and the coating amount is 2.5 g / m ^{2 in} dry mass. An undercoat layer is provided, and the other surface is made of 100% by mass of oxidized starch (trade name: Ace A, manufactured by Oji Cornstarch Co., Ltd.) with a solid content. Then, a back layer having a coating weight of 1.0 g / m ² in terms of dry mass was provided to obtain a release paper base paper. Next, the base paper was supercalendered to increase the density. The obtained base paper for release paper has a humidity control basis weight of 48 g / m ² , a Steecht sizing degree according to JIS P 8122 of 10 seconds, and JAPAN TAPPI paper pulp test method No. The Oken air permeability according to 5-2: 2000 was 20000 seconds.

-Preparation of pressure-sensitive adhesive sheet On the undercoat layer of the above release paper base paper, a three-off offset gravure coater was used to prepare a solvent-free silicone resin ("LTC-1056L" manufactured by Toray Dow Corning Silicone) (viscosity at 25 ° C: 250 mPa After mixing s) with the catalyst necessary for the crosslinking reaction, 1 g / m ^{2 was} applied and cured to form a release agent layer. Next, an adhesive (“Olivein BPW6111” manufactured by Toyochem Co., Ltd.) was applied onto the release agent layer and dried to a solid content of 20 g / m ² to form an adhesive layer. Subsequently, said surface base material was bonded to the adhesive layer side, and the adhesive sheet was obtained.

Example 2
In the production of the base paper for release paper of Example 1, the content ratio of the coating solution for the undercoat layer was changed to 60% by mass instead of 40% by mass of the α-olefin-modified polyvinyl alcohol, and 40% by mass instead of 60% by mass of kaolin. It was. Further, a 1.5 g / ^{m 2} in place of the coating amount of the undercoat layer to 2.5 g / ^{m 2,} was 0.8 g / ^{m 2} in place of the coating amount of the back layer to 1.0 g / ^{m 2.} Except for this, a base paper, a base paper for release paper, and an adhesive sheet were obtained in the same manner as in Example 1. The resulting base paper for release paper had a humidity conditioning basis weight of 48 g / m ² , a Steecht size of 10 seconds, and a Oken air permeability of 16000 seconds.

Example 3
In the production of the base paper for release paper of Example 1, the content ratio of the coating solution for the undercoat layer was changed to 50% by mass instead of 40% by mass of the α-olefin-modified polyvinyl alcohol, and changed to 50% by mass instead of 60% by mass of kaolin. It was. Also, instead of the coating solution for the back layer consisting of 100% by mass of oxidized starch, it consists of 50% by mass of oxidized starch and 50% by mass of kaolin (trade name: “HT”, aspect ratio 7, Engelhard) and disperses water. A back surface layer coating solution having a concentration of 15% was used as a medium. Furthermore the 2.0 g / ^{m 2} in place of the coating amount of the undercoat layer to 2.5 g / ^{m 2,} was 0.6 g / ^{m 2} in place of the coating amount of the back layer to 1.0 g / ^{m 2.} Except for this, a base paper, a base paper for release paper, and an adhesive sheet were obtained in the same manner as in Example 1. The resulting base paper for release paper had a humidity basis weight of 47 g / m ² , a Steecht size of 10 seconds, and a Oken air permeability of 18000 seconds.

Example 4
In the production of the base paper for release paper of Example 1, the amount of talc added to the pulp slurry was adjusted so that the ash content was 10%. The content of the undercoat layer coating solution was 50% by mass instead of 40% by mass of the α-olefin-modified polyvinyl alcohol, and 50% by mass instead of 60% by mass of kaolin. Also, instead of the coating solution for the back layer consisting of 100% by mass of oxidized starch, it consists of 70% by mass of oxidized starch and 30% by mass of kaolin (trade name: “HT”, aspect ratio 7, manufactured by Engelhard) and disperses water. A back surface layer coating solution having a concentration of 12% was used as a medium. Furthermore the 4.5 g / ^{m 2} in place of the coating amount of the undercoat layer to 2.5 g / ^{m 2,} was 0.6 g / ^{m 2} by changing the coating amount of the back layer to 1.0 g / ^{m 2.} Except for this, a base paper, a base paper for release paper, and an adhesive sheet were obtained in the same manner as in Example 1. The resulting base paper for release paper had a humidity control basis weight of 49 g / m ² , a steecht size of 11 seconds, and a Oken air permeability of 25000 seconds.

Example 5
In the production of the base paper for release paper of Example 1, the amount of the rosin sizing agent added to the pulp slurry was changed to 2.0 parts by mass instead of 0.5 parts by mass. Further, the amount of talc added to the pulp slurry was adjusted so that the ash content was 10%. Further, the content of the coating solution for the undercoat layer was changed to 50% by mass instead of 40% by mass of the α-olefin-modified polyvinyl alcohol, and changed to 50% by mass instead of 60% by mass of kaolin. Further, instead of the coating solution for the back surface layer comprising 100% by mass of oxidized starch, 70% by mass of oxidized starch and 30% by mass of kaolin (trade name: “HT”, aspect ratio 7, Engelhard) are used, and water is dispersed in the dispersion medium. A back surface layer coating solution having a concentration of 12% was used. Furthermore, a 4.5 g / ^{m 2} in place of the coating amount of the undercoat layer to 2.5 g / ^{m 2,} was 0.6 g / ^{m 2} by changing the coating amount of the back layer to 1.0 g / ^{m 2.} Except for this, a base paper, a base paper for release paper, and an adhesive sheet were obtained in the same manner as in Example 1. The resulting base paper for release paper had a humidity control basis weight of 49 g / m ² , a Steecht size of 25 seconds, and a Oken air permeability of 26000 seconds.

Example 6
In the production of the base paper for release paper of Example 1, the content ratio of the coating solution for the undercoat layer was changed to 50% by mass instead of 40% by mass of the α-olefin-modified polyvinyl alcohol, and changed to 50% by mass instead of 60% by mass of kaolin. It was. Further, instead of the coating solution for the back layer composed of 100% by mass of oxidized starch, 50% by mass of styrene-butadiene copolymer latex (trade name: “A6160”, solid concentration 48%, manufactured by Asahi Kasei Co., Ltd.) and kaolin ( Product name: “HT”, aspect ratio 7, manufactured by Engelhard Co., Ltd.) 50% by mass, and a back layer coating solution having a concentration of 15% using water as a dispersion medium was used. Furthermore the 2.0 g / ^{m 2} in place of the coating amount of the undercoat layer to 2.5 g / ^{m 2,} was 0.6 g / ^{m 2} in place of the coating amount of the back layer to 1.0 g / ^{m 2.} Except for this, a base paper, a base paper for release paper, and an adhesive sheet were obtained in the same manner as in Example 1. The resulting base paper for release paper had a moisture conditioning basis weight of 48 g / m ² , a Steecht size of 10 seconds, and a Oken air permeability of 17000 seconds.

Comparative Example 1
In the production of the release paper base of Example 1, the Canadian standard freeness was changed to 150 ml instead of 150 ml, and the amount of talc added to the pulp slurry was adjusted to 5% ash. It was adjusted. The content of the undercoat layer coating solution was 50% by mass instead of 40% by mass of the α-olefin-modified polyvinyl alcohol, and 50% by mass instead of 60% by mass of kaolin. It was 2.0 g / ^{m 2} and further changing the coating amount of the undercoat layer to 2.5 g / ^{m 2.} Except for this, a base paper, a base paper for release paper, and an adhesive sheet were obtained in the same manner as in Example 1. The resulting base paper for release paper had a humidity conditioning basis weight of 48 g / m ² , a Steecht size of 10 seconds, and a Oken air permeability of 6000 seconds.

Comparative Example 2
In the production of the base paper for release paper of Example 1, the Canadian standard freeness was 90 ml instead of 150 ml. The content of the undercoat layer coating solution was 50% by mass instead of 40% by mass of the α-olefin-modified polyvinyl alcohol, and 50% by mass instead of 60% by mass of kaolin. It was 2.0 g / ^{m 2} and further changing the coating amount of the undercoat layer to 2.5 g / ^{m 2.} Except for this, a base paper, a base paper for release paper, and an adhesive sheet were obtained in the same manner as in Example 1. The resulting base paper for release paper had a moisture conditioning basis weight of 48 g / m ² , a Steecht size of 10 seconds, and a Oken air permeability of 50000 seconds.

Comparative Example 3
In the production of the base paper for release paper of Example 1, no talc was added to the pulp slurry. The content of the undercoat layer coating solution was 50% by mass instead of 40% by mass of the α-olefin-modified polyvinyl alcohol, and 50% by mass instead of 60% by mass of kaolin. It was 2.0 g / ^{m 2} and further changing the coating amount of the undercoat layer to 2.5 g / ^{m 2.} Except for this, a base paper, a base paper for release paper, and an adhesive sheet were obtained in the same manner as in Example 1. The obtained base paper had an ash content of 0% based on JIS P 8251, a moisture conditioning basis weight of the base paper for release paper of 49 g / m ² , a Steecht sizing degree of 10 seconds, and a Oken air permeability of 18000 seconds.

Comparative Example 4
In the production of the base paper for release paper of Example 1, the amount of talc added to the pulp slurry was adjusted so that the ash content was 30%. The content of the undercoat layer coating solution was 50% by mass instead of 40% by mass of the α-olefin-modified polyvinyl alcohol, and 50% by mass instead of 60% by mass of kaolin. It was 2.0 g / ^{m 2} and further changing the coating amount of the undercoat layer to 2.5 g / ^{m 2.} Except for this, a base paper, a base paper for release paper, and an adhesive sheet were obtained in the same manner as in Example 1. The resulting base paper for release paper had a humidity conditioning basis weight of 48 g / m ² , a Steecht size of 10 seconds, and a Oken air permeability of 7000 seconds.

Comparative Example 5
In the production of the base paper for release paper of Example 1, in place of α-olefin-modified polyvinyl alcohol (the above-mentioned ethylene-modified polyvinyl alcohol) of the undercoat layer coating solution, a completely saponified polyvinyl alcohol (trade name: PVA-110, manufactured by Kuraray Co., Ltd.) ) Was used. Moreover, it was 2.0 g / ^{m 2} in place of the coating amount of the undercoat layer to 2.5 g / ^{m 2.} Except for this, a base paper, a base paper for release paper, and an adhesive sheet were obtained in the same manner as in Example 1. The resulting base paper for release paper had a humidity conditioning basis weight of 49 g / m ² , a Steecht size of 10 seconds, and a Oken air permeability of 9000 seconds.

Comparative Example 6
In the production of the base paper for release paper of Example 1, light calcium carbonate (trade name: Brilliant 15, manufactured by Shiraishi Calcium Co., Ltd.) that is not plate-shaped was used instead of kaolin as the coating liquid for the undercoat layer. Moreover, it was 2.0 g / ^{m 2} in place of the coating amount of the undercoat layer to 2.5 g / ^{m 2.} Except for this, a base paper, a base paper for release paper, and an adhesive sheet were obtained in the same manner as in Example 1. The resulting base paper for release paper had a humidity conditioning basis weight of 48 g / m ² , a Steecht size of 10 seconds, and a Oken air permeability of 8000 seconds.

Comparative Example 7
In the production of the base paper for release paper of Example 1, the content ratio of the coating solution for the undercoat layer was changed to 50% by mass instead of 40% by mass of the α-olefin-modified polyvinyl alcohol, and changed to 50% by mass instead of 60% by mass of kaolin. It was. Further, no back layer was provided on the other side of the base paper. Except for this, a base paper, a base paper for release paper, and an adhesive sheet were obtained in the same manner as in Example 1. The resulting base paper for release paper had a humidity control basis weight of 49 g / m ² , a Steecht size of 6 seconds, and a Oken air permeability of 20000 seconds.

  The following evaluation was performed about the adhesive sheet obtained in this way. The results were as shown in Table 1.

(Curl after printing)
An A4 size sample is prepared from the obtained adhesive sheet, and a character string (40 lines × 40 characters) of font 10.5 is printed on an electrophotographic printer “MFP Apeos Port-IV3370” (Fuji Xerox Co., Ltd.) (paper) Type: thick paper 2 (170 to 256 g / m ² )), and curling and paper alignment at the time of paper discharge were evaluated.
○: Curling does not occur immediately after printing, and the paper alignment at the time of paper discharge is good.
Δ: Some curling occurs immediately after printing, but there is no practical problem with the paper alignment at the time of paper discharge.
X: The curl after printing immediately after printing is large, and there is a problem with paper alignment at the time of paper discharge.

(Blank paper curl)
An A4 size sample was prepared from the obtained adhesive sheet, conditioned at 25 ° C. in a high humidity environment of 60% RH for 4 hours, and the curled side was placed on a flat sample table. The average value was obtained by measuring how much the four corners were lifted from the sample table, and evaluated according to the following criteria.
○: Less than 1.5 cm Δ: 1.5 cm to less than 3.0 cm ×: 3.0 cm or more

(Rise)
A 220 mm wide roll of pressure-sensitive adhesive sheet was scraped off at a speed of 25 m / min with a letterpress rotary printing press SKP-250A (manufactured by Sankisha) and visually evaluated according to the following criteria.
A: No rise occurs.
○: Little rise occurs.
(Triangle | delta): Although raising occurs, it is satisfactory practically.
×: Significant rise occurs.

(Adhesive residue)
In the above evaluation process, the amount of glue adhering to the roll was visually evaluated according to the following criteria.
○: No adhesive residue occurs.
Δ: Almost no adhesive residue is generated.
X: Adhesive residue is remarkably generated.

(Printability on the back layer side)
The dry pick (back ink used: Tack 16 Crimson T & KToka) on the back surface was visually evaluated with an RI printing machine according to the following criteria.
◯: There is no problem with printing missing.
Δ: Partial printing omission occurs, but there is no practical problem.
X: Print omission occurs remarkably.

(Roll dirt that the back layer contacts)
In the papermaking and drying processes, the dirt on the roll such as a dryer that the back layer contacts was visually observed and evaluated according to the following criteria.
◯: There is no transfer of fibers, resin, etc., and there is no roll dirt such as dryer
(Triangle | delta): Although there exists some transition of a fiber, resin, etc., there is almost no roll stains, such as a dryer, which becomes a problem practically.
X: There are many transitions of fiber, resin, etc., and roll dirt of a dryer etc. is remarkable.

Claims (8)

  A base paper made of pulp fiber having a Canadian freeness of 100 to 300 ml according to JIS P 8121, a base paper for release paper having an undercoat layer on one side of the base paper and a back layer on the other side, The base paper has an ash content of 5 to 20% based on JIS P 8251: 2003, the undercoat layer contains a water-based adhesive and a plate pigment mainly composed of α-olefin-modified polyvinyl alcohol, and the back layer is A base paper for release paper, comprising an aqueous adhesive.   The main component of the aqueous adhesive contained in the back layer is at least one selected from the group consisting of starch and derivatives thereof, polyvinyl alcohol, modified polyvinyl alcohol, and styrene-butadiene copolymer latex. The base paper for release paper as described.   The base paper for release paper of Claim 1 or 2 which contains the water-based adhesive from which the said undercoat and a back surface layer mutually differ as a main component of the said water-based adhesive.   The release paper base paper according to any one of claims 1 to 3, wherein the release paper base paper comprising the base paper, the undercoat layer, and the back surface layer has a Steecht sizing degree according to JIS P 8122 of 5 seconds or more.   JAPAN TAPPI Paper Pulp Test Method No. The base paper for release paper according to any one of claims 1 to 4, wherein the Oken air permeability according to 5-2: 2000 is 10,000 to 100,000 seconds.   The release paper base paper according to any one of claims 1 to 5, further comprising a printing layer containing at least one selected from the group consisting of flexographic ink, offset ink and gravure ink on the back layer.   A base paper comprising at least pulp fibers, a method for producing a base paper for release paper having an undercoat layer on one side of the base paper and a back layer on the other side, wherein the aqueous adhesives differ from each other as a main component of the aqueous adhesive Using a coating liquid for an undercoat layer and a coating liquid for a back surface layer, which are simultaneously applied and dried to form an undercoat layer on one side of the base paper and a back layer on the other side. A method for producing a base paper for release paper.   The release paper according to claim 7, wherein the step includes a step of simultaneously applying with a film transfer coater, and the film transfer coater is one of a gate roll coater, a rod metering size press coater, or a blade metering size press coater. A method of manufacturing base paper.