JP4037430B2 - Crimp paper - Google Patents

Description

  The present invention relates to a crimped paper. More specifically, it has excellent printing and writing suitability, and not only has both crimpability and easy peelability, but also has high water resistance and damages the recorded information even when wet. In addition, the present invention relates to a pressure-sensitive paper that can easily peel the pressure-bonding surface when necessary and can reliably read information printed on the pressure-bonding surface.

  Crimped paper is a paper with an adhesive layer formed on at least one side of the base paper, and this adhesive layer has no adhesion / tackiness at room temperature, but exhibits the adhesiveness when given pressure is applied. (Hereinafter referred to as “crimpability”) and the ability to be easily peeled after bonding (hereinafter referred to as “easy peelability”). For the pressure-bonded paper, after printing on the base paper, what is called a post-glue method in which an adhesive layer is formed on the printed surface, and direct printing or information recording is performed on the adhesive layer formed on the base paper. Although there is a so-called “adhesive” method, since the adhesive layer is not required to be formed at the printing destination, generally, an adhesive paper of the “adhesive” method is widely used.

  The pressure-bonding paper as described above is usually used by folding the adhesive layers so that the adhesive layers face each other and pressing the surfaces in contact with each other so that they can be peeled off again. As described above, since this adhesive layer has both crimpability and easy peelability, the information on the printed surface can be easily concealed by a simple process called crimping, and it is crimped when necessary. The sheet can be easily peeled off at the interface of the adhesive layer, and the printed information can be read again. For this reason, most of the crimping papers are used as postcards for communicating information that needs to be concealed (hereinafter referred to as “concealment information”), so-called crimping postcards.

  A printed postcard prints concealment information on the surface to be crimped, so that the concealment information can be mailed without leaking to the outside, and the concealment information can be read easily by the recipient. is there. Since the concealing part is detachably bonded with a predetermined pressure, it is impossible to artificially adhere the concealing part again after the detachment, and information concealment can be easily confirmed.

  It also has the advantage that it can be mailed at the same rate as a commonly used postcard. Therefore, in recent years, its use has rapidly spread as an alternative to concealment information transmission means using envelopes and direct mail in sealed format.

  By the way, in addition to being able to conceal the concealment information (concealment) and to be able to read the information after receipt (easy peelability), the crimped postcard also considers accidental wetting due to rain during mailing, Furthermore, water resistance is required. Specifically, even if the adhesion strength (improvement of hydration bond strength) caused by getting wet with water occurs, the postcard that has been crimped can be easily opened, and the printed information is damaged. Water resistance that can be clearly read without any problem is required.

  Therefore, concealment using a base sheet having water resistance to the base paper as an attempt to impart water resistance to the pressure-bonded paper in the past, in order to solve the problem that the adhesive strength of the adhesive is improved or the strength of the base paper is reduced due to wetting. An information carrier sheet (see Patent Document 1) and a water-resistant reproduction concealment information carrying sheet (see Patent Documents 1 and 2) in which a base sheet is further provided with a water-resistant treatment layer have been proposed.

  Here, when using high-quality paper as the base sheet, laminated paper whose surface is provided with water resistance by coating the surface with synthetic resin or synthetic resin paper generally called synthetic paper must be used. I must. However, such laminated paper is difficult to reuse and has problems in terms of environmental protection, and printing on the surface of the synthetic resin and the printing method are limited, and the cost is high as with synthetic paper. The advantage of a postcard that can be transmitted is lost. Therefore, the use of inexpensive form paper or high-quality paper without coating has been demanded for the base paper of pressure-bonded paper.

  However, pressure-bonded postcards using foam paper or high-quality paper with no coating as the base paper have the disadvantage that the strength of the base paper decreases when wet. In addition, natural rubber (modified) that is usually used for the adhesive layer of pre-adhesive pressure-bonded paper improves its adhesion when it gets wet with water, so when the recipient tries to open the pressure-bonded postcard, the base paper May be torn, or peeling may occur at an inadvertent location, so that printed information cannot be read. Therefore, a pressure-sensitive paper having a water-resistant treatment layer provided on the base sheet as described above has been proposed. However, such a pressure-sensitive paper has a complicated manufacturing process and a water-resistant treatment layer is formed on the printing surface. Therefore, it is necessary to consider the familiarity between the water-resistant layer and the ink. Moreover, there exists a problem that the press bonding property and easy peelability of an adhesive bond layer are impaired by forming a water-resistant treatment layer on an adhesive bond layer.

In addition, as described above, the adhesive layer of the pre-bonded pressure-bonded paper is mainly made of normal (modified) natural rubber and fine particles. Such (modified) natural rubber is very easily deteriorated, and its adhesive strength changes depending on humidity conditions. For this reason, the pressure-sensitive paper having an adhesive layer formed of such raw materials has a problem that its easy peelability is lowered when wet. In particular, it is known that the adhesive strength of the adhesive layer after being dipped in water and dried is about twice that in a constant humidity state. Therefore, the pressure-bonded postcard made from such pressure-bonded paper has a large problem that the adhesive strength is increased and the easy peelability is impaired, and it cannot be easily opened when the recipient tries to open it. is there.
Japanese Patent Laid-Open No. 7-309086 JP 2003-103968 A

  The present invention has been made in view of the above-mentioned background art, and is excellent in printing / writing ability, not only having both crimpability and easy peelability, but also having high water resistance and being wet with water. It is another object of the present invention to provide a pressure-sensitive paper that can easily peel the pressure-bonding surface when necessary without damaging the recorded information provided, and can reliably read the information printed on the pressure-bonding surface. .

  That is, the present invention is a pressure-sensitive adhesive paper having an adhesive layer formed on at least one of the front and back surfaces of a base paper, and the base paper has Canadian freeness (hereinafter referred to as JIS P 8120 test piece and disaggregation). "CSF") is made of raw pulp beaten in the range of 350-600 mL, and cation-based wet paper strength agent and anionic dry paper strength agent are 1 / 4-1 / 3 (cationic-type wet paper strength agent / anion The present invention relates to a pressure-sensitive adhesive paper characterized in that it is contained at a ratio of a dry paper strength agent (mass ratio). As described above, the pressure-sensitive adhesive paper of the present invention contains two kinds of paper strength agents in a specific ratio and uses a base paper made of a specific raw material pulp. In addition to having high water resistance, even when wet, the crimping surface can be easily peeled off when necessary without damaging the recorded information provided. The information printed on can be read reliably.

  The adhesive layer is formed from an adhesive composition containing at least a binder component containing natural rubber, polyvinyl alcohol (hereinafter referred to as “PVA”) and fine particles, and the PVA has a polymerization degree of 300. In the case of a partially saponified PVA having a saponification degree in the range of ~ 1000 and a saponification degree in the range of 86 to 89 mol%, the pressure-bonding property and water resistance can be further improved, Also, the strength reduction and breakage of the adhesive layer are more sufficiently prevented.

  Further, when the base paper has a wet tensile strength in the MD direction of 1.5 kN / m or more in accordance with JIS P 8135 after being immersed in water for 24 hours, the water resistance of the pressure-bonded paper is further improved. be able to.

  The pressure-sensitive adhesive paper of the present invention is excellent in printability and writing suitability, and not only has both the pressure-bonding property and the easy peeling property, but also has high water resistance, and even when it is wet, the recorded information is provided. The crimping surface can be easily peeled off when necessary without damage, and the information printed on the crimping surface can be read reliably.

(First embodiment)
As described above, the pressure-sensitive adhesive sheet of the present invention is a pressure-sensitive adhesive sheet in which an adhesive layer is formed on at least one of the front and back surfaces of the base paper, and the base paper is used for the test piece and disaggregation of JIS P 8120. Consists of raw pulp with compliant CSF beaten in the range of 350 to 600 mL, 1/4 to 1/3 (cationic wet paper strength / anionic dry strength) It is contained at a ratio of paper strength agent (mass ratio). Thus, the use of the base paper of the specific raw material is one of the great features of the present invention. By using such a base paper, the excellent effects as described above can be exhibited at the same time.

  Hereinafter, a pressure-sensitive adhesive paper according to an embodiment of the present invention will be described. The pressure-sensitive adhesive paper of the present invention has, for example, the structure shown in the schematic cross-sectional view of FIG. 1, and in FIG. 1, 1 is a pressure-sensitive paper, 2 is a base paper, and 3 is an adhesive layer. Such an adhesive layer 3 is formed on at least one of the front and back surfaces of the base paper 2, and FIG. 1 shows a state in which the adhesive layer 3 is formed on the surface of the base paper 2.

  First, the base paper 2 used in the present invention will be described below.

  As the base paper 2, either non-recycled paper using virgin pulp as raw material pulp or recycled paper using waste paper pulp as raw material pulp can be used.

  The kind of the virgin pulp is not particularly limited, and for example, a known pulp used in the production of fine paper can be used. Specific examples of such virgin pulp include kraft pulp (KP) such as sulfite pulp (SP), soda pulp (AP), hardwood bleached kraft pulp (LBKP) and softwood bleached kraft pulp (NBKP), and chemiground pulp (CGP). ), Semi-chemical pulp (SCP), bleached pulp crushed under pressure (BPGW), and the like, and these can be used alone or in combination of two or more. Such virgin pulp is used after being bleached if necessary. In this case, it is preferable to employ a bleaching method not using chlorine. That is, when bleached pulp is used, it is desirable to use pulp bleached by chlorine-free bleaching such as Total Chlorine Free (TCF) and Elemental Chlorine Free (ECF). Such a chlorine-free bleached pulp is a pulp that has been subjected to ozone bleaching or oxygen bleaching, and although it is not clear, since the end groups of the fibers (cellulose) constituting the pulp are activated by oxygen, the cationic system described later Affinity with wet paper strength agent and anionic dry paper strength agent is high, and a paper strength improvement effect is more suitably exhibited.

  As the used paper pulp, used paper pulp that has been bleached, in particular, reduced-bleached with thiourea dioxide (FAS) can be preferably used. The reason why FAS-bleached waste paper pulp is not clear compared to conventional chlorine bleached pulp is high in affinity with the cationic wet paper strength agent and anionic dry paper strength agent, which will be described later. Is more suitably exhibited.

  In addition, when using used paper pulp, it is preferable that content of the used paper pulp in raw material pulp is 70 mass% or more. In this way, by using 70% by mass or more of waste paper pulp, environmental protection and cost reduction can be realized, and the opacity is higher than the base paper of only the same basis weight virgin pulp, The pressure-bonding paper 1 can be suitably used by, for example, a pressure-bonded postcard. In consideration of sufficiently maintaining the surface strength of the base paper 2, the content of the used paper pulp in the raw pulp is preferably 95% by mass or less.

  The raw material pulp of the base paper 2 conforms to the method described in “7. Test pieces and disaggregation” of JIS P 8120 from the viewpoint of improving the water resistance of the pressure-bonding paper 1 and specifically improving the wet tensile strength of the base paper. The CSF is beaten in a range of 350 mL or more, preferably 400 mL or more and 600 mL or less, preferably 550 mL or less. When the raw material pulp has a CSF of less than 350 mL, the paper strength improvement effect is low, the stiffness and strength of the base paper itself are reduced, and curling is likely to occur during, for example, electrophotographic printing, and the printability is poor. It becomes. In addition, when the CSF of the raw material pulp exceeds 600 mL, the formation deteriorates, for example, not only the printability at the time of ink jet printing is inferior, but also the surface strength unevenness of the base paper due to the formation unevenness is easily generated. It becomes inferior also in peelability and adhesive strength. In addition, a known beating machine such as a reioner or a kneader is used for beating the raw pulp, but the CSF of the raw pulp can be adjusted by classifying the short fiber and the long fiber with a classifier. By appropriately adjusting the treatment concentration and treatment time, a raw material pulp having a CSF within the above range can be obtained.

  When manufacturing the base paper 2 from raw material pulp, a cationic wet paper strength agent and an anionic dry paper strength agent are added to the raw material pulp. The cationic wet paper strength agent has an action of improving the wet tensile strength of the base paper 2, and the anionic dry paper strength agent improves the fixability of the cationic wet strength paper strength to the base paper 2. Has an effect.

  Examples of the cationic wet paper strength agent include those obtained by imparting cationicity to resins such as polyamide resin, urea-formaldehyde resin, melamine-formaldehyde resin, polyamide-polyamine-epichlorohydrin resin, polyethyleneimine, and the like. Or two or more can be used simultaneously. For example, in the case of urea-formaldehyde resin, these resins are modified with a polyvalent amine such as ethylenediamine or diethylenetriamine to promote the fixing to pulp fibers to impart a cationic property. In the case of a melamine-formaldehyde resin, heat condensation is performed in the presence of hydrochloric acid to form a so-called acid colloid having a cationic property. Among these cationic wet paper strength agents, polyamide resin, polyamide-polyamine-epichlorohydrin resin, and polyethyleneimine can be suitably used in consideration of environmental aspects due to recent restrictions on free formalin.

  Examples of the anionic dry paper strength agent include polyacrylamide (hereinafter referred to as “PMA”), PVA, carboxymethylcellulose, and the like, and these can be used alone or in combination of two or more. When PVA is used as such an anionic dry paper strength agent, as will be described later, since the PVA is contained in the adhesive composition forming the adhesive layer 3, the base paper 2 and the adhesive layer 3 are used. It becomes possible to further improve the adhesion between the two.

The addition amount of the cationic wet paper strength agent and the anionic dry paper strength agent with respect to the raw material pulp is not particularly limited, but in order to obtain a sufficient water resistance improvement effect of the base paper 2, 10 ³ kg of the raw material pulp is used. It is preferable that both of them are about 20 kg or more, further about 30 kg or more with respect to (absolutely dry), and in order to avoid high cost due to use more than necessary, 10 ³ kg of raw pulp (absolutely dry) Both of them are preferably about 100 kg or less, more preferably about 90 kg or less.

  In addition, these cationic wet paper strength agents and anionic dry paper strength agents are adjusted in their proportions so that the cationic wet paper strength agents can be easily fixed on the base paper 2 by balancing the ion balance between them. Specifically, the ratio of the cationic wet paper strength agent to the anionic dry paper strength agent (cationic wet paper strength agent / anionic dry paper strength agent (mass ratio)) is 1/4 or more, and further 1 / It is preferable to adjust to 3.9 or more, 1/3 or less, and further 1/3 or less. When the ratio of both is less than 1/4, the effect of improving the wet tensile strength is reduced. When the ratio is more than 1/3, the blending ratio of the anionic dry paper strength agent is reduced. Fixing property of wet paper strength agent decreases.

  There is no particular limitation on the manufacturing method of the base paper 2, and it can be manufactured by paper making using a general paper making technique of Western paper. That is, after the raw pulp is made into a slurry, the paper may be made using a long net paper machine, a round net paper machine, a twin wire type paper machine, a multilayer paper machine, or the like.

  The base paper 2 used in the present invention thus obtained has a high wet tensile strength, is extremely resistant to tearing even when wet with water, and can sufficiently read information printed after peeling. Can be provided. Specifically, for example, the wet tensile strength in the MD direction of a conventionally used base paper is about 0.2 kN / m. In the present invention, the wet tensile strength in the MD direction of the base paper 2 is 1.5 kN. / M or more, further up to 1.7 kN / m or more.

  Here, the wet tensile strength will be described. The wet tensile strength according to the present invention is a value measured in accordance with the method described in JISP 8135 after the crimping paper 1 is immersed in water for 24 hours. The reason why the immersion time in water is set to 24 hours is not based on the premise that the crimping paper 1 is soaked in water. This is because it is sufficient if it has water resistance that can withstand even when it gets wet by water. The wet tensile strength is measured in a state wet with water. As described above, when the wet tensile strength in the MD direction is 1.5 kN / m or more, and further 1.7 kN / m or more. It has been confirmed that even the pressure-bonded paper 1 which has been dried after being wetted with water has a sufficient strength to prevent tearing during peeling.

  If the wet tensile strength is too large, there is a possibility that recycle as used paper becomes difficult, and the rigidity becomes high, so that the processing suitability at the time of bonding and the curling problem at the time of peeling are likely to occur. Usually, it is preferably about 5 kN / m or less.

  For example, a filler such as clay, calcium carbonate, or titanium dioxide may be added to the base paper 2 as necessary. In addition, the surface strength can be further increased by applying a size press liquid containing an inorganic pigment, starch or the like to the surface as necessary.

Moreover, there is no limitation in particular in the basic weight of the base paper 2 used for this invention, For example, what is necessary is just about 100-150 g / m < ² >.

  Next, the adhesive layer 3 formed on at least one of the front and back surfaces of the base paper 2 will be described below.

  The adhesive layer 3 is not particularly limited, but can further improve the pressure-bonding property and water resistance, and even when the adhesive layer is wet, the strength reduction and destruction of the adhesive layer are more sufficiently prevented. Therefore, it is preferably formed from an adhesive composition containing at least a binder component containing natural rubber, PVA and fine particles, for example.

  The binder component includes, for example, natural rubber. In the present invention, in addition to such natural rubber, latex, synthetic rubber, synthetic resin and the like that are usually used as a binder component of an adhesive can be used in combination. Among them, for example, natural rubber latex obtained by sulfur-free vulcanization of natural rubber and mixed with methyl methacrylate, natural rubber latex obtained by graft copolymerization of methyl methacrylate with natural rubber, acrylic modified rubber latex, rubber latex And a mixture of a protective colloidal acrylic copolymer emulsion alone or in combination of two or more thereof can be particularly preferably used from the viewpoints of blocking resistance, aging resistance, and ink inking property.

  The amount of the natural rubber in the binder component is not particularly limited, and is usually 50% by mass or more, and more preferably about 55 to 95% by mass.

  Further, as the binder component, starch, a dispersant, a humectant, a water-resistant agent, a surfactant, and the like may be included as long as the characteristics are not impaired. Examples of such a dispersant include polyethylene oxide and calcium stearate. Examples of the humectant include acrylic acid, acrylic acid ester, carboxymethyl cellulose and the like. Examples of the water-proofing agent include urea formalin resin and polyamide polyurea resin, and examples of the surfactant include silicone wax GZ-650 (trade name, manufactured by Seiko PMC Co., Ltd.).

  PVA acts as an auxiliary agent for binder components including natural rubber. As described above, the adhesive composition containing natural rubber is easily deteriorated depending on the humidity condition, and when applied to the base paper 2 containing the cationic wet paper strength agent, the base paper when wetted with water. Although there is no tear of 2, there is a tendency for easy peelability to decrease. Also, for example, the base paper using waste paper pulp is less easily peelable between the adhesive layers due to the influence of the ink in the waste paper and the solidified binder used in, for example, coated paper, especially when wet. Or, the strength of the adhesive layer tends to decrease and the layer breaks. However, these problems can be solved more easily by blending PVA as an auxiliary agent in a binder component containing natural rubber.

  PVA is obtained by performing a polymerization reaction and a saponification reaction using vinyl acetate monomer as a raw material, and the degree of polymerization affects viscosity and the like. A lower polymerization degree of PVA is preferable because the amount of delamination between the base paper 2 and the adhesive layer 3 is reduced and the adhesion between the two is increased, but if it is too low, the viscosity becomes too low, The effect of the binder component containing natural rubber as an auxiliary agent is not sufficiently exhibited, and the press bonding property is poor. Therefore, the polymerization degree of such PVA is preferably 300 or more, and more preferably 350 or more. If the degree of polymerization of PVA is too high, the viscosity is high and the pressure-bonding property is excellent, but the amount of delamination between the base paper 2 and the adhesive layer 3 becomes large, resulting in poor adhesion between the two. Therefore, the degree of polymerization of such PVA is preferably 1000 or less, more preferably 950 or less. By using PVA having such a degree of polymerization, the adhesive strength between the base paper 2 and the adhesive layer 3 is further increased, and the easy peelability is not easily lowered even when wet.

  Further, as the PVA, it is preferable to use partially saponified PVA, not completely saponified PVA or intermediate saponified PVA. The degree of saponification of such partially saponified PVA affects not only the pressure-bonding property of the adhesive layer, but also the strength and easy peelability of the adhesive layer when wetted with water. When the degree of saponification is too small, the strength and easy peelability of the adhesive layer particularly when wetted with water tends to decrease. Therefore, it is preferably 86 mol% or more, more preferably 87 mol% or more. . If the degree of saponification is too large, the adhesive composition may be thickened and preparation may be difficult, or the pressure-bonding property may be lowered. Therefore, it is 89 mol% or less, more preferably 88 mol% or less. Preferably there is.

  In the present invention, a partially saponified PVA having a polymerization degree and a saponification degree within the above-mentioned ranges, that is, a partial saponification having a polymerization degree in the range of 300 to 1000 and a saponification degree in the range of 86 to 89 mol%. When PVA is used, problems such as a decrease in easy peelability of the adhesive layer and a layer breakage due to a decrease in strength when wetted with water can be solved more sufficiently.

  The amount of PVA blended is 5 masses per 100 parts by mass of the binder component in order to sufficiently prevent layer breakage due to a decrease in the peelability of the adhesive layer and a decrease in strength when wetted with water. Part or more, more preferably 8 parts by weight or more. In consideration of water resistance, operational stability, and viscosity stability, the amount of PVA is preferably 20 parts by mass or less and more preferably 15 parts by mass or less with respect to 100 parts by mass of the binder component. In the present invention, two or more types of PVA having different degrees of polymerization and saponification may be used simultaneously.

  The fine particles are components that control the pseudo-adhesion between the pressure-bonded adhesive layers 3 and facilitate the peeling of the pressure-bonded surfaces when necessary.

  Examples of the fine particles include, in addition to pigments such as silica, clay, and calcium carbonate, amorphous synthetic silica powders having different average particle sizes, calcined kaolin, acidic clay, activated clay, colloidal silica, colloidal alumina, zeolite, and magnesium carbonate. , Titanium dioxide, zinc oxide, aluminum hydroxide, corn starch, potato starch, wheat starch, polyethylene fine particles, polystyrene fine particles and the like, and these can be used alone or in combination of two or more.

  If the particle size of the fine particles is too small, blocking of the adhesive layer and re-peeling failure will occur, causing problems that cause concealment information damage, and tending to cause conveyance failure and double feed in printing and processing processes Therefore, the average particle diameter is preferably 1 μm or more, more preferably 3 μm or more. Also, if the particle size of the fine particles is too large, inadvertent peeling may occur and the concealability may be impaired, and since the fine particles form unique protrusions protruding from the adhesive layer, printing defects and Since there is a tendency that workability defects occur in the processing and printing steps, and the printing appearance tends to deteriorate, the average particle diameter is preferably 25 μm or less, more preferably 20 μm or less.

  The blending amount of the fine particles is 1 part by mass or more, further 3 parts by mass or more with respect to 100 parts by mass of the binder component so that the pseudo-adhesiveness between the adhesive layers is sufficiently controlled to a desired level. It is preferable that If there are too many fine particles, the fine particles will not be sufficiently fixed on the surface of the adhesive layer, causing fine particles to drop off during processing and printing / recording processes. Since the quality may be deteriorated, the amount of the fine particles is preferably 10 parts by mass or less, more preferably 8 parts by mass or less with respect to 100 parts by mass of the binder component. In the present invention, two or more kinds of fine particles having different particle diameters may be used simultaneously.

  There is no particular limitation on the method for preparing the adhesive composition. For example, PVA and fine particles with an appropriately blended ratio are added to a dispersion of a binder component containing natural rubber and other components as necessary, and a uniform composition is obtained. What is necessary is just to mix at appropriate temperature so that it may become.

The viscosity and solid content concentration of the obtained adhesive composition are not particularly limited as long as the object of the present invention is not impaired, and may be in a range that can sufficiently exert the action as the adhesive layer in the pressure-bonded paper. For example, the viscosity at 25 ° C. (measured with a B-type viscometer) is preferably about 13 × 10 ^{−3 to} 35 × 10 ⁻³ Pa · s, and the solid content concentration is preferably about 5 to 50%.

  For example, the adhesive layer 3 is formed by applying the adhesive composition having the above composition to the base paper 2.

  The method for applying the adhesive composition is not particularly limited, and a method using a normal coating machine can be employed. Examples of such a coating machine include an air knife coater, a blade coater, a rod metering coater, a curtain coater, and a roll coater. However, in particular, when a colored adhesive composition is applied, the coating is performed more uniformly. It is preferable to use a curtain coater that can be worked. In addition to the method using these coating machines, a method of printing by a printing method such as gravure offset, letterpress, or flat plate can also be employed.

If the coating amount of the adhesive composition is too small, the desired adhesive strength cannot be obtained, and unintended peeling tends to occur. If it is too large, the adhesive strength becomes too strong and easy peeling. In general, the adhesive composition is attached to a coating roll or the like at the time of coating, and troubles in operation and quality are likely to be caused. Therefore, it is usually preferably about 3 to 15 g / m ^2. .

  After coating the adhesive composition on the base paper 2, it is preferable to smooth the coated surface, and when performing such smoothing treatment, normal calendering can be employed. The calendar process can be performed by a coating machine and a series of calendars (on-machine calendar), or by a completely separate calendar (off-machine calendar) instead of a series of coating machines. . The type of the calendar is not particularly limited, and a known calendar such as a calendar provided with a metal roll and an elastic roll, or a calendar obtained by combining metal rolls can be used.

  Thus, when the thickness of the adhesive layer 3 formed on the base paper 2 is too small, the pressure-bonding property is low, for example, there is a possibility that peeling occurs during the mailing of the pressure-bonded postcard, and it is too large. In some cases, the adhesive composition may stick out at the time of pressure bonding, and it is usually preferably about 5 to 20 μm.

  The pressure-bonding paper 1 configured as described above is a so-called “front paste method” in which an adhesive layer 3 is formed on a base paper 2 before information is printed. For example, when creating a pressure-bonded postcard from a pressure-bonding paper of a pre-glue method, after printing shared data that is invariant information on the pressure-bonding paper 1, printing of variable data that requires concealment of personal information or the like is performed on the adhesive layer. 3 is printed, and the pressure-sensitive paper 1 is folded in two or three so as to conceal at least the variable data that needs to be concealed, and then pressure-bonded by a pressure sealer or the like. The crimp postcard constructed in this way has high water resistance, so even when wet, the adhesive layer is not destroyed and the crimp surface can be easily peeled off when necessary. The information printed on can be read reliably. In addition, the pressure-sensitive adhesive paper 1 according to the present invention is not limited to the one formed by such a pre-glue method, and can also be applied to a post-glue method.

  Next, the pressure-sensitive adhesive paper of the present invention will be described in more detail based on the following examples, but the present invention is not limited to such examples.

(Production Examples 1 to 8) Preparation of base paper Cationic wet paper strength agent was prepared by pulping the pulp type, bleaching means and blending ratio of raw pulp shown in Table 1 with a refiner and adjusting to CSF as shown in Table 1. (Cationic polyamide resin, trade name: WS4002, manufactured by Seiko PMC Co., Ltd.) and anionic dry paper strength agent (PMA, trade name: Hermide EX, manufactured by Harima Kasei Co., Ltd.) The amount of the pulp is 10 ³ kg (absolutely dry)), and the papermaking raw material is made with a long paper machine. When making paper, adjust the paper making raw material discharge rate with respect to the opening paper making speed of the head box raw material discharge port (lip), shake the wire in the wire part (rolling), and press the postcard shown in the schematic perspective view of FIG. Use No. 1 to 8 base papers were obtained. A size press solution containing an inorganic pigment and starch was applied to the front and back surfaces of each base paper at 1.5 g / m ² per side. The basis weights were all adjusted to 130 g / m ² .

Abbreviations in Table 1 are as shown below.
Pulp type D: DIP (quality paper pulp)
L: LBKP
N: NBKP
Bleaching means F: FAS bleaching E: ECF bleaching

(Preparation Examples 1 to 8) Preparation of Adhesive Composition Graft-copolymerized natural rubber emulsion 70% by mass, synthesized by graft copolymerization of 100 parts by mass of natural rubber latex (NR) and 10 parts by mass of methyl methacrylate (MMA), synthesis As rubber latex, 20% by mass of styrene-MMA copolymer emulsion (trade name: Polysol AP6730, manufactured by Showa High Polymer Co., Ltd.) and 10% by mass of modified starch (trade name: HSS Coat 100, manufactured by Oji Cornstarch Co., Ltd.) The PVA shown in Table 2 and 5 parts by mass of silica (trade name: W500, manufactured by Grace Devison, average particle diameter: 8 μm) as fine particles are blended with 100 parts by mass of the binder component dispersion liquid to be contained. Mix well with No. 1-8 adhesive compositions were obtained.

  The viscosity at 25 ° C. of each adhesive composition was measured with a B-type viscometer. The results are shown in Table 2 together with the solid concentration.

(Examples 1 to 16 and Comparative Examples 1 to 10) Preparation of pressure-bonded postcards Using combinations of Tables 3 and 4 using an air knife coater and an on-machine calendar, No. The adhesive compositions 1 to 8 After coating with the coating amount of 10 g / m ² on the front and back surfaces of the base papers 1 to 8, the coated surface is smoothed to form an adhesive layer having a thickness of about 5 to 20 μm. The pressure-bonded postcard 4 shown in FIG. The adhesive layers are not formed on the entire front and back surfaces of the base paper, but are adhesive layers on the surfaces 5b and 5c on the front side of the base paper and on the surfaces 5d and 5e on the back side of the base paper, respectively. Is formed. The adhesive layer is not formed on the surface 5a on the front surface side and the surface 5f on the back surface side of the base paper. Therefore, in this crimped postcard 4, it is possible to print invariant information (non-concealment information) such as the address on the surfaces 5a and 5f and concealment information on the surfaces 5b, 5c, 5d and 5e.

  Color printing was performed on the surfaces 5a to 5f of the pressure-bonded postcard 4 by the method described in the column of “(Test Example 2) Printability (1) Inkjet printing” below. The crimping postcard 4 is folded in three so that the surface 5b and the surface 5c face each other, and the surface 5d and the surface 5e face each other, and a crimping sealer (model number: MS-9100, manufactured by Dai Nippon Printing Co., Ltd.) is used. A pressure-bonding process was performed under the conditions of the sealer gap 17 and the faces facing each other were pressure-bonded to obtain a pressure-bonded postcard 6 shown in FIG. This crimping postcard 6 is a 6-sided 6-inch specification.

  The following tests were conducted on the obtained pressure-bonded postcard 6 after pressure bonding and the pressure-bonded postcard 4 before pressure bonding, and the characteristics thereof were examined. The results are shown in Tables 3 and 4.

(Test Example 1) Wet tensile strength of base paper After the crimped postcard 6 was immersed in water for 24 hours, the wet tensile strength in the MD direction was measured in accordance with the method described in JIS P 8135.

(Test Example 2) Printability (1) Inkjet printing Using an inkjet printer (model number: PIXUS860i, manufactured by Canon Inc.), black, red, blue, and yellow solid colors on the surfaces 5a to 5f of the crimped postcard 4 Printing was performed (size: 5 cm × 5 cm). After 30 minutes from the start of printing, the dried state of the ink and the presence or absence of bleeding between adjacent printing boundaries were visually observed and evaluated based on the following evaluation criteria.

[Evaluation criteria]
○: The ink is completely dry and there is no bleeding.
Δ: Ink is not completely dried or bleeding is observed.
X: The ink is not completely dried and bleeding is recognized.

(2) Electrophotographic copying Using an electrophotographic copying machine (model number: NP6550, manufactured by Canon Inc.), 13-point characters were copied over the entire printing area on the surfaces 5a to 5f of the crimping postcard 4. It was confirmed whether double feeding would occur during copying, and evaluated based on the following evaluation criteria.

[Evaluation criteria]
○: No double feed occurred.
Δ: Partial double feeding occurred.
X: The occurrence of double feeding was significant.

(Test Example 3) Easy peelability The crimped postcard 6 was peeled from the end by a normal method, and the state was evaluated based on the following evaluation criteria.
[Evaluation criteria]
A: No particular force is required, and peeling is very easy.
B: Peeling is easy.
C: Neither can be said.
D: Slightly difficult to peel and requires force.
E: It is very difficult to use because force is required for peeling.

(Test Example 4) Water resistance The pressure-bonded postcard 6 was immersed in water at room temperature for 24 hours. After that, the pressure-bonded postcard 6 taken out from the water was peeled off and examined for easy peelability, tearing of the base paper, breakage of the adhesive layer and reading of printing information.

(1) Easy peelability The state when peeled was evaluated based on the following evaluation criteria.
[Evaluation criteria]
A: No particular force is required, and peeling is very easy.
B: Peeling is easy.
C: Neither can be said.
D: Slightly difficult to peel and requires force.
E: It is very difficult to use because force is required for peeling.

(2) Breaking of base paper The state of the base paper after peeling was visually observed and evaluated based on the following evaluation criteria.
[Evaluation criteria]
A: There is no tear at all.
B: There are only a few small tears that are hardly visible.
C: There are several tears.
D: The tear is conspicuous.
E: The tear is remarkable and the base paper hardly keeps the original pattern.

(3) Destruction of the adhesive layer The uneven state of the adhesive layer surface after peeling was observed with an optical microscope, and the adhesion state of dirt when the surface of the layer was rubbed by hand was examined. Based on the following evaluation criteria evaluated.
[Evaluation criteria]
A: There is no unevenness and it is smooth, and no dirt adheres to the hand.
B: There are almost no unevenness | corrugations and the stain | pollution | contamination of a hand is also slight.
C: Several small unevenness | corrugations are confirmed and there is also some dirt.
D: There are many uneven parts, and a lot of dirt adheres to the hand.
E: Overall unevenness is remarkable, and dirt is severe.

(4) Reading of printing information After peeling, it was confirmed whether the information printed on the surfaces 5b, 5c, 5d, and 5e could be read, and evaluated based on the following evaluation criteria.
[Evaluation criteria]
A: All print information can be read easily and accurately on all sides.
B: Most print information can be accurately read on all sides.
C: On some surfaces, there is a portion where the print information cannot be read accurately.
D: There are many places where print information cannot be read accurately on all sides.
E: Print information can hardly be read on all sides.

  From the results shown in Table 3, as in Examples 1 to 16, the CSF was made of raw material pulp having 420 to 520 mL, and the cationic wet paper strength agent and the anionic dry paper strength agent were 1/4 to 1/3. The pressure-bonded postcards in which the adhesive layer is formed on the base paper obtained by blending within the range of the above are not only excellent in printability but also in easy peelability, Despite the use of 70% by weight or more of recycled paper pulp as raw material pulp, the wet tensile strength in the MD direction after immersion for 24 hours in water is as large as 1.5 kN / m or more, and it is highly water-resistant. It can be seen that the printing paper information can be reliably read with excellent properties, almost no tearing of the base paper and destruction of the adhesive layer. Moreover, since the waste paper pulp is used as the raw material pulp as described above, the cost can be sufficiently reduced.

  In particular, as can be seen from Examples 1 to 12, not only LBKP with high fiber strength and LBKP having an effect of improving printability, but also a considerable amount of used paper, a specific range of CSF, and a specific proportion of cationic wet paper strength In combination with an adhesive composition containing a partially saponified PVA having a polymerization degree of 300 to 1000 and a saponification degree of 86 to 89 mol%, using a base paper containing an agent and an anionic dry paper strength agent In the case of the ink, the water resistance is greatly improved as well as the printability.

  On the other hand, as in Comparative Examples 1 to 10 in Table 4, a base paper obtained from a raw pulp having a CSF of less than 350 mL or more than 600 mL, or a cationic wet paper strength agent and an anionic dry paper strength agent 1 A crimped postcard using a base paper obtained by blending at a ratio of less than / 4 or more than 1/3 is not only inferior in printability but also has low easy peelability, making it difficult to reliably read print information. Or the wet tensile strength in the MD direction after being immersed in water for 24 hours becomes insufficient, the easy peelability is low, or the base paper is torn and inferior in water resistance, and it is difficult to reliably read printing information. It can be seen that it is.

  The pressure-sensitive adhesive paper of the present invention can be suitably used not only for pressure-bonded postcards but also for information concealment papers and concealment envelopes that require concealment, for example.

It is a schematic sectional drawing which shows one embodiment of the crimping | compression-bonding paper of this invention. BRIEF DESCRIPTION OF THE DRAWINGS It is a schematic perspective view of the pressure-bonded postcard concerning the Example of this invention, (a) is a schematic perspective view before pressure bonding, (b) is a schematic perspective view after pressure bonding.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Crimp paper 2 Base paper 3 Adhesive layer 4 Crimp postcard 5a-5f Surface 6 Crimp postcard

Claims (3)

A pressure-sensitive adhesive paper having an adhesive layer formed on at least one of the front and back surfaces of the base paper,
The base paper is composed of a test piece of JIS P 8120 and a raw pulp with a Canadian freeness in accordance with disaggregation in the range of 350 to 600 mL. A pressure-sensitive adhesive paper characterized by containing at a ratio of ˜1 / 3 (cationic wet paper strength agent / anionic dry strength paper (mass ratio)).   The adhesive layer is formed from an adhesive composition containing at least a binder component containing natural rubber, polyvinyl alcohol and fine particles, and the polyvinyl alcohol has a degree of polymerization in the range of 300 to 1000, and The pressure-bonded paper according to claim 1, which is partially saponified polyvinyl alcohol having a saponification degree in the range of 86 to 89 mol%.   The pressure-sensitive adhesive paper according to claim 1 or 2, wherein the base paper has a wet tensile strength in the MD direction of 1.5 kN / m or more in accordance with JIS P 8135 after being immersed in water for 24 hours.

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