JP2009057668A - Multi-ply paper and method for producing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide multi-ply paper having improved hot water-resistant peeling strength and a method for producing the multi-ply paper. <P>SOLUTION: The multi-ply paper 6 has an improved delamination strength by bonding between fibers of a nonwoven fabric layer 2 and a paper layer 1 by carrying out the combined paper making of the fiber of the paper layer 1 with the nonwoven fabric 2 produced at least by the blended paper-making with a sheath-core thermal bonding fiber 4 having a heat-weldable sheath part and a hydrophilic fiber 5 and further has an improved hot water-resistant peeling strength by producing the nonwoven fabric 2 by blending the sheath-core thermal bonding fiber 4 having a sheath part having a melting point of 90°C or higher and provides a method of producing the multi-ply layer. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a multilayer laminated paper in which a non-woven fabric is produced by a wet process using a core-sheath type heat-fusible fiber and a hydrophilic fiber, and is laminated with a stock layer fiber discharged by a long net paper machine. It is about the method.

  As a general method for producing multilayer laminated paper, a raw material tank containing raw materials containing water and fibers is prepared according to the number of layers to be combined, and a mesh-like circular net is provided in the raw material tank. The fibers in the raw material tank are picked up to form a fiber web, the web is transferred to a net-like transport belt such as a wire, and the fiber webs formed by the other raw material tanks and the circular net are sequentially stacked to form a multi-layer plow. Methods for producing laminated paper are known.

  In the above-described method, there is a problem that a raw material tank and a net are required for the number of layers to be combined. This problem is solved by installing slices for discharge rectification on a long net using a single long net and sequentially laminating a plurality of raw materials on the long net. However, in this method, since the raw material is squeezed until it loses fluidity on the long net and is laminated after forming the web, the hydrogen bonding between the fibers between the layers becomes weak, and the paper after papermaking peels off. There was a problem of delamination that was easy.

  As a means for preventing such delamination of paper, when producing multilayer laminated paper with a plurality of circular paper machines, when producing multilayer laminated paper by combining circular paper machines and long paper machines, and In the case of producing multi-layer laminated paper by combining a long web paper machine and a long web paper machine, a method has been proposed in which an adhesive is applied to each layer with a spray device, a roll coater device, or the like at the stage of bonding. .

  In addition, when producing multi-layered laminated paper with a single long paper machine, a plurality of tanks containing raw materials including water and fibers are placed on a circulating endless paper net, and the width of the endless paper net In a long net paper machine having at least one sheet feeding unit for feeding out a sheet having an arbitrary width below, a plurality of tanks in a tank arranged at a position preceding the endless paper making circuit circulation process. After discharging the raw material onto the endless paper mesh and forming at least one layer of raw material laminar flow on the endless paper web, the sheet is run over the laminar flow, and further, a plurality of tanks on the sheet, A multilayer laminated paper has been proposed in which a raw material in a tank disposed at a later position with respect to the endless papermaking mesh circulation process is discharged to form a wet web on the endless papermaking net. This sheet of laminated paper is a non-woven fabric using natural fibers such as rayon. By joining these non-woven fabrics of natural fibers, hydrogen bonding (interfiber bonding) occurs, and interlayer adhesion is obtained. A means for preventing delamination has been proposed (see, for example, Patent Document 1).

  In addition, a spunbond nonwoven fabric having a core-sheath structure, the sheath part containing fibers of a heat-fusible resin having a melting point lower than that of the core part, and the nonwoven fabric surface is continuously or discontinuously laminated by wet papermaking. The paper material layer is laminated to the nonwoven fabric in the form of a wet sheet formed by the wet part of the paper machine, and the paper material layer and the nonwoven fabric are a low melting point heat-meltable resin in the sheath portion of the nonwoven fabric. Multi-layered laminated paper that is bonded by thermal melting via a sheet has been proposed (for example, see Patent Document 2).

  In addition, multilayer paper has also been proposed in which a nonwoven fabric produced using polyethylene fiber, polypropylene fiber, or the like is sandwiched between wet paper and wet paper, and is produced by thermal fusion.

JP 2003-13395 A Japanese Patent No. 2784292

  However, in the method of applying the adhesive with the spray device or the roll coater as described above, the adhesive strength between the wet paper and the nonwoven fabric surface is improved because the adhesive is combined before drying, but the strength within the nonwoven fabric layer is improved. When it is low, peeling occurs in the nonwoven fabric layer.

  In addition, the method using a nonwoven fabric using natural fibers such as rayon as disclosed in Japanese Patent Application Laid-Open No. 2003-13395 does not provide sufficient adhesion only between the fibers of rayon fibers and wet paper fibers, and delamination Will occur.

  In addition, a multilayer laminated paper produced using a spunbonded nonwoven fabric made of synthetic resin fibers, such as Japanese Patent No. 2784292, is a laminated multilayered sheet because the spunbonded nonwoven fabric itself lacks uniformity. Laminated paper also lacks uniformity, deteriorating appearance, printability and paper characteristics.

  Moreover, in the method using the nonwoven fabric produced using olefin fiber such as polyethylene fiber and polypropylene fiber, these olefin materials have low wettability and water repellency. Therefore, the nonwoven fabric and upper and lower pulp fibers ( The compatibility with the wet paper) is poor, and delamination occurs. Furthermore, when the low melting point binder fiber is mixed during the production of the nonwoven fabric, the binder fiber melts and peels off in the nonwoven fabric layer when immersed in warm water of about 90 ° C.

  For example, when multi-layered laminated paper is used for the base of valuable printed matter such as banknotes and there are the above-mentioned problems, delamination may occur due to transport in cash processing machines such as ATMs and ticket vending machines. Therefore, a significant improvement in durability has been desired.

  The present invention aims to solve the above problems, and specifically, a non-woven fabric produced by mixing a core-sheath type heat-fusible fiber and a hydrophilic fiber whose sheath part is heat-sealed, By interleaving with the stock layer fiber, the interlaminar bond strength of the non-woven layer fiber and the stock layer fiber improves the delamination strength, and the sheath melting point of the core-sheath type heat-fusible fiber exceeds 90 ° C. An object of the present invention is to provide a multi-layered laminated paper and a method for producing the same, in which the nonwoven fabric is produced by mixing the materials to improve the hot water-resistant peel strength.

  The multilayer laminated paper in the present invention is a multilayer paper in which at least three layers of an upper paper layer, an intermediate layer, and a lower paper layer are laminated, and the intermediate layer has at least a core-sheath type heat-fusible fiber and a hydrophilic property. It consists of the nonwoven fabric which mixed the fiber, The melting | fusing point of the sheath part of a core-sheath-type heat-fusible fiber is characterized by being lower than melting | fusing point of the core part of a core-sheath-type heat-fusible fiber.

  The multilayer laminated paper in the present invention comprises a nonwoven fabric in which core-sheath type heat-fusible fibers and hydrophilic fibers are bonded to each other by thermal fusion. The paper layer fibers of the layers and the lower paper material layer are characterized by being bonded between fibers by hydrophilization and thermal fusion.

  The method for producing a multilayer laminated paper in the present invention is to produce a nonwoven fabric by mixing at least a core-sheath type heat-fusible fiber and a hydrophilic fiber, and the produced nonwoven fabric is made up of an upper paper stock and a lower paper stock on a paper machine. A multilayer laminated paper having an upper paper layer, a non-woven cloth intermediate layer and a lower paper layer is formed, and the multilayer laminated paper includes a melting point of the sheath portion of the core-sheath type heat-fusible fiber. Heat drying within a temperature range is characterized.

  In the method for producing a multilayer laminated paper in the present invention, a binder is applied to at least one surface of a nonwoven fabric obtained by mixing core-sheath type heat-fusible fibers and hydrophilic fibers, and the applied binder is dried. A multilayer laminated paper having an upper paper layer, an intermediate layer made of non-woven fabric, and a lower paper layer is formed between the upper paper stock and the lower paper stock, and in the drying section of the paper machine, Heat drying in the range of melting | fusing point of the sheath part of a core-sheath-type heat-fusible fiber is characterized by the above-mentioned.

  The sheath of the core-sheath type heat-fusible fiber is melted by the heat during the production of the non-woven fabric because it is a non-woven fabric made by mixing the core-sheath type heat-fusible fiber and the hydrophilic fiber. And the bond between fibers increases by the heat | fever adhesion by fusion | melting, and the peeling strength in a nonwoven fabric layer improves. Furthermore, the sheath part melts again because the melting point of the sheath part of the core-sheath-type heat-bonding fiber is almost the same as the drying part of the paper machine in the drying part when the paper material layer and the nonwoven fabric layer are joined together by the paper machine. The delamination strength between the paper material layer and the non-woven fabric layer is improved by thermal bonding by melting.

  In addition, by selecting the sheath of the core-sheath type heat-fusible fiber having a component familiar to the stock layer fiber such as a carboxyl group or a hydroxyl group, the inter-fiber bond between the stock layer fiber and the non-woven fabric layer fiber is selected. The force is increased and the delamination strength is improved.

  Moreover, since it is a nonwoven fabric in which hydrophilic fibers are mixed with core-sheath type heat-fusible fibers, the nonwoven fabric itself becomes hydrophilic. Therefore, at the time of wet papermaking, the familiarity of the stock layer fiber and the non-woven fabric layer fiber becomes good, the bond strength between fibers is increased, and the delamination strength is improved.

  In addition, by using a core-sheath type heat-fusible fiber having a sheath melting point exceeding 90 ° C. and having a component of 110 ° C. or less, the fiber does not melt even when immersed in warm water at 90 ° C. The delamination strength in hot water resistance is improved.

  It is also possible to mix the binder fiber with the nonwoven fabric, thereby improving the peel strength in the nonwoven fabric layer. By using a binder fiber having a melting point equal to or higher than the warm water temperature (90 ° C.), the peel strength in warm water resistance is further improved.

  In addition, since it is not necessary to install an adhesive application device or a roll coater device for bonding the stock layer and the nonwoven layer, the paper machine can be simplified.

  Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows a cross-sectional view of a multilayer laminated paper. Fig.2 (a) shows the longitudinal cross-sectional view of a core-sheath-type heat-fusible fiber, (b) shows the cross-sectional view of a core-sheath-type heat-fusible fiber. FIG. 3 shows the overall configuration of a multilayer laminated paper manufacturing apparatus. FIG. 4 shows the fiber mixing ratio of the nonwoven fabric of one Example and a comparative example in the present invention. FIG. 5 shows the peel strength of multilayer laminated paper of one example and a comparative example in the present invention.

  First, multilayer laminated paper will be described with reference to FIG. FIG. 1 shows a cross-sectional view of a multilayer laminated paper. The multilayer laminated paper (6) has an upper stock layer (1) made of fibers, an intermediate layer made of nonwoven fabric (2), and a lower stock layer (3) made of fibers.

  The nonwoven fabric referred to in the present invention means that various fiber webs are processed mechanically, chemically, thermally, or a combination thereof without using a loom, and the constituent fibers are bonded to each other by the adhesive or the fusing force of the fibers themselves. It is a cloth made.

  The fibers used for the upper stock layer (1) and the lower stock layer (3) are not particularly limited, and chemical pulps such as KP and SP made from plant fibers such as wood and cotton, GP, etc. , TMP, CTMP and other mechanical pulps and pulp such as waste paper recycled pulp can be appropriately selected and used.

  The fiber used for the intermediate layer composed of the nonwoven fabric (2) is a mixture of at least the core-sheath type heat-fusible fiber (4) and the hydrophilic fiber (5). The ratio of the core-sheath type heat-sealable fiber and the hydrophilic fiber is not particularly limited, and the more the core-sheath type heat-sealable fiber, the greater the delamination strength of the nonwoven fabric itself. However, if the ratio of the core-sheath fiber is too large, the nonwoven fabric becomes hydrophobic, and the familiarity with the nonwoven fabric when the upper paper layer and the lower paper layer are combined with each other deteriorates. The fiber-to-fiber bond between the fabric and the nonwoven fabric is reduced.

  FIG. 2 shows a cross-sectional view of the core-sheath type heat-fusible fiber. (A) is a longitudinal cross-sectional view, (b) is a cross-sectional view. The core-sheath type heat-fusible fiber (4) is composed of a core part (28) and a sheath part (29), and the melting point of the component constituting the sheath part is lower than the melting point of the component constituting the core part, Desirably, the temperature is in the range of more than 90 ° C. and 110 ° C. or less which melts in the drying section of the paper machine. Since the sheath part of the core-sheath type heat-fusible fiber has a heat-fusible component and the core part of the core-sheath type heat-sealable fiber has a fiber-forming component, the melting point of the sheath part The greater the difference in melting point of the core portion, the lower the thermal shrinkage rate in the case of heat processing, and the better the dimensional stability. Moreover, you may select the component which is familiar with a paper layer fiber, such as a carboxyl group or a hydroxyl group, for a sheath part.

  The melting point is a temperature at which a solid substance changes to a liquid. In the case of a solid mixture composed of two or more components, the melting point is the temperature at which the liquid first appears when heated. The heat-fusible substance referred to in the present invention expresses adhesiveness when the substance is liquefied and melted with this melting point as a boundary.

  The hydrophilic fiber (5) is a fiber having a lot of hydrophilic groups such as hydroxyl groups and carboxyl groups and having affinity for water.

  The nonwoven fabric (2) may be obtained by mixing binder fibers with those obtained by mixing the core-sheath type heat-fusible fibers (4) and the hydrophilic fibers (5). By mixing the binder fibers, the binder fibers are melted by the heat at the time of producing the nonwoven fabric, and the bond between fibers is increased by the thermal adhesion by melting, so that the peel strength in the nonwoven fabric layer is improved.

  The binder fiber as used in the field of this invention is a fiber which melt | dissolves with the heat | fever at the time of nonwoven fabric preparation, and expresses thermal adhesiveness. The melting point of the binder fiber is preferably about room temperature to 180 ° C., and by using a material having a temperature exceeding 90 ° C. and not higher than 180 ° C., the binder fiber does not elute even when immersed in warm water at 90 ° C. Improves the delamination strength.

  Moreover, you may apply | coat a liquid binder to a nonwoven fabric (2) previously. Applying a binder to the nonwoven fabric (2) in advance using a coater, etc., and heat drying improves the bond strength between the fibers of the nonwoven fabric (2). In the drying section, the delamination strength between the paper material layer and the nonwoven fabric layer is improved by the thermal bonding of the binder.

  The liquid binder referred to in the present invention is an adhesive that expresses an adhesive force for bonding two solids, and refers to latex, emulsion, solution, suspension (suspension) and the like. The glass transition point of the binder is preferably about room temperature to 100 ° C. The room temperature here means a temperature at which the binder to be used does not melt, and is about 30 ° C.

  The glass transition point is that a polymer substance is solidified into a glass state that can be said to be a frozen liquid through a supercooled liquid. When the substance constituting the binder is a polymer substance having a glass transition point (for example, latex), the glass transition point is a temperature at which the binder is easily deformed rapidly.

  Furthermore, it is desirable that the liquid binder penetrates between the fibers constituting the nonwoven fabric (2) and is fixed throughout the thickness direction of the nonwoven fabric. Further, the amount of the binder applied is an optimum amount of application that exhibits an anti-peeling effect and does not cause a problem with watering during production.

  In addition to heat fusible materials such as latex in liquid binders, colored pigments, colorless fluorescent pigments, colored fluorescent pigments, magnetic pigments, pigments having infrared absorption or reflection characteristics, microcapsules, etc. It is also possible to apply at least one kind of the material having the above to the nonwoven fabric (2).

  The multilayer laminated paper in the best mode for carrying out the present invention can be subjected to other anti-counterfeiting techniques. For example, colored fiber or strip, colorless fluorescent fiber or strip, colored fluorescent fiber or strip, magnetic fiber or strip, metal strip, aluminum strip, fiber or strip with infrared absorption characteristics, infrared reflection It is possible to mix at least one kind of fibers or strips having characteristics and thermochromic fibers or strips, and it is also possible to apply threads and a cut image.

  The multilayer laminated paper (6) has been described with the three-layer structure of the upper paper layer (1), the nonwoven fabric (2), and the lower paper layer (3), but the upper paper layer sandwiching the nonwoven fabric (2). As long as (1) and the lower stock layer (3) are included, a structure of four layers or five layers may be used.

  Next, an apparatus for producing multilayer laminated paper will be described with reference to FIG.

  FIG. 3 shows the overall configuration of a multilayer laminated paper manufacturing apparatus. An apparatus for producing multilayer laminated paper is composed of a web band called a long web paper machine (8), and has an endless paper machine wire (9) that circulates. The wire (9) is bridged between the driven pulley (10) and the driving pulley (11), and is supported by a plurality of rolls (not shown) arranged on the inner side along the wire (9). Has been circulating.

  From the upstream side to the downstream side, the lower stock supply tank (12), the non-woven fabric supply device (13), and the upper stock supply tank ( 14) are sequentially arranged at intervals.

  The lower stock supply tank (12) and the upper stock supply tank (14) are filled with the lower stock (15) and the upper stock (16), respectively, and are appropriately replenished from a supply source (not shown). The liquid level is controlled to be maintained. The lower stock (15) and the upper stock (16) are materials that are materials of the lower stock layer (3) and the upper stock layer (1), and are mainly composed of pulp fibers, water, and additives.

  In the downstream portion of each of the lower stock supply tank (12) and the upper stock supply tank (14), a lower stock seal plate (17) and an upper stock stop plate (18) are respectively disposed. ing. Supply the lower and upper papers on the wire (9) through the gaps between the lower paper supply plate (17) and the upper paper supply plate (18) and the wire (9). Paper making is possible.

  The nonwoven fabric supply part by the nonwoven fabric supply device (13) is provided on the downstream side of the lower stock supply tank (12) and upstream of the upper stock supply tank (14), and is formed on the wire (9). The nonwoven fabric (2) is supplied toward the lower stock layer (lower wet paper) (19). The nonwoven fabric supply device (13) includes a nonwoven fabric supply drum (20) and a tension roll (21).

  The width (w) of the strip-shaped non-woven fabric (2) supplied from the non-woven fabric supply device (13) is formed by being supplied from the lower material sealing plate (17) to the upper surface (conveying surface) of the wire (9). The width of the lower stock layer (lower wet paper) (19) is substantially the same as that of the lower stock layer (19), and is further supplied from the upper stock sealing plate (18) to the upper surface of the lower stock layer (19). The width of the upper stock layer (upper wet paper) (22) is substantially the same.

  The nonwoven fabric supply drum (20) moves along the longitudinal direction of the axis (the direction perpendicular to the paper surface in FIG. 1), that is, in the width direction of the nonwoven fabric (2), and moves in the width direction along with the wound nonwoven fabric. It is the structure adjusted with the nonwoven fabric supply drum width direction position adjustment apparatus which is not shown in figure so that it can adjust.

  A water squeezing box (23) is disposed below the wire (9) at the downstream side (the movement terminal portion on the upper surface of the wire). This water squeezing box (23) is a multilayer laminated paper (6) comprising a lower stock layer (19), a non-woven fabric (2) and an upper stock layer (22) in the downstream portion of the wire (9) in the paper making process. The water contained inside is aspirated and squeezed.

  The multilayer laminated paper (6) formed of the wire (9) is guided by a guide roll (not shown) and wound up by a winding roll as a final product, but between the wire (9) and the winding roll, it is upstream. From the side, a press roll (24) and a drying device (25) are arranged. A press roll (24) is used when giving a gap to a multilayer laminated paper.

  The press roll (24) sandwiches the multilayer laminated paper (6) and sends it to the downstream winding roll side. The gap is formed by the well-known press roll (24) or tundee roll (26). The drying device (25) uses a known drying device.

  Next, the manufacturing method of the multilayer laminated paper in this invention is demonstrated with reference to FIG.

  First, a nonwoven fabric is produced. The core-sheath type heat-fusible fiber (4), the hydrophilic fiber (5) and, if necessary, the binder fiber are uniformly dispersed in water at a dilute concentration to prepare a suspension of each fiber. Each of these suspensions is mixed in a predetermined composition and uniformly dispersed, and the mixed fiber suspension is made on a screen to form a sheet-like web.

  Secondly, the picked-up web is dewatered between rollers, passed through a drying device, and dried by heating. The fibers are bonded to each other by heat fusion of the sheath portion of the core-sheath type heat-fusible fiber (4) or the binder fiber, and the sheet-like nonwoven fabric (2) is formed. The dried nonwoven fabric (2) is wound up by a reel device.

  When a liquid binder is applied to the nonwoven fabric (2) in advance, the binder is applied to the nonwoven fabric (2) using a coater device or the like, and dried by heating. Thereby, the bond strength between the fibers of the nonwoven fabric (2) is improved. The application method in the application processing unit is a gravure method, an impregnation method, or a method that can be applied to a nonwoven fabric. The dried nonwoven fabric (2) coated with the binder is wound up by a reel device.

  Thirdly, the nonwoven fabric is laminated into the stock layer using a multi-layer laminated paper manufacturing apparatus. The lower stock (15) is supplied from the lower stock supply tank (12) to the upper surface of the wire (9) in circulation through the gap between the lower stock sealing plate (17) and the wire (9). The lower stock (15) supplied on the wire (9) is sent in the paper making direction as a lower stock layer (19).

  A strip-shaped nonwoven fabric (2) is continuously supplied from the nonwoven fabric supply device (13) to the upper surface of the lower stock layer (19). The strip-shaped non-woven fabric (2) and the lower stock layer (19) are overlapped while being fed in the paper making direction on the wire (9), and the lower stock (15) enters between the fibers of the non-woven fabric (2). The pulp fiber of the material (15) and the fiber of the nonwoven fabric (2) are intertwined, and a strong bond between the two is generated. Further, when a carboxyl group or a hydroxyl group is used in the sheath portion of the core-sheath fiber (4), these functional groups of the core-sheath fiber (4), Due to the hydrogen bond between the hydroxyl group of the hydrophilic fiber (5) and the carboxyl group or hydroxyl group of the cellulose fiber of the lower stock layer, the interfiber bonding force between the lower stock layer and the nonwoven fabric layer fiber is increased.

  On the upper surface of the strip-shaped non-woven fabric (2) overlapped with the pulp fibers of the lower stock (15), the gap between the upper stock supply tank (14) and the upper stock sealing plate (18) and the wire (9) The top stock (16) is fed through. The upper stock (16) overlaps with the nonwoven fabric (2) while being fed in the paper making direction as the upper stock layer (22) on the wire (9), and the upper stock (16) is between the fibers of the nonwoven fabric (2). Get in. Thus, by producing a multi-layered laminated paper with a long paper machine, the pulp fibers of the upper stock (16) are intertwined with the fibers of the non-woven fabric (2) and already enter the non-woven fabric (2). It also entangles with the pulp fibers of the lower stock (15) and produces a strong bond. In addition, the carboxyl groups and hydroxyl groups of the core-sheath fiber (4), the hydroxyl groups of the hydrophilic fiber (5), and the hydrogen bonds between the carboxyl groups and hydroxyl groups of the cellulose fibers of the upper stock layer, The bond strength between the fiber layer and the nonwoven fabric fiber increases.

  The multi-layered laminated paper (6), which has been laminated together, passes through the squeezing box (23), and the fibers of the lower stock (15), the nonwoven fabric (2) and the upper stock (16) enter each other and become entangled. To form a strong bonding layer. In addition, the dehydration solidifies the hydrogen bond between the core-sheath type heat-fusible fiber (4) and the hydrophilic fiber (5) and the cellulose fiber of the upper and lower paper layers, and the firmness of the upper and lower paper layers and the nonwoven fabric layer fibers. An interfiber bond is formed.

  Fourth, it passes through the drying device (25) and is dried. At the time of drying, due to the heat fusion effect of the sheath portion of the core-sheath type heat-fusible fiber (4) constituting the nonwoven fabric (2), the interlayer between the lower layer paper layer (15) and the nonwoven fabric (2) and the nonwoven fabric (2 ) And the upper paper stock layer (22) are further increased in bond strength, and the peeling prevention effect is improved. In addition, when a binder fiber having a melting point within the temperature range (about 90 to 110 ° C.) of the drying apparatus is used, a heat-sealing effect by the binder fiber is also added, and the peeling prevention effect is improved. When the liquid binder is applied to the nonwoven fabric, the delamination strength between the paper material layer and the nonwoven fabric layer is further improved due to the heat fusion effect of the liquid binder.

  Fifth, the multilayer laminated paper (6) heated and dried by the drying device (25) is wound up by the reel device (27) to be completed as a final product.

  When the press roll (24) is used for squeezing, the squeezing box (23) is passed through and the press roll (31) is used for squeezing.

  Further, by using a material having a melting point of more than 90 ° C. and not more than 110 ° C. in the sheath portion of the core-sheath type heat-fusible fiber (4), the multilayer laminated paper is immersed in warm water at 90 ° C. However, the fiber is not melted, and the peel strength in hot water resistance is improved. The hot water resistant peel strength here is the peel strength measured after the multilayer laminated paper is immersed in warm water at 90 ° C. for 1 hour and dried.

  There is also a technique for improving the peel strength by subjecting the nonwoven fabric (2) to a hydrophilic treatment such as corona discharge treatment and hydrophilizing the nonwoven fabric surface to increase the interfiber bonding force with the stock layer (15). By applying corona discharge treatment to the nonwoven fabric surface, hydrophilic groups are selected on the nonwoven fabric surface, and the hydrogen bond between these and the cellulose fibers of the stock layer (15), the inter-fiber bond between the stock layer and the nonwoven fabric layer fiber. Power increases.

  It is also possible to produce multi-layered laminated papers with different colors, basis weights or fiber configurations by changing the stock properties of the raw materials stored in the lower stock supply tank (12) or the upper stock supply tank (14) It is. The color can be adjusted depending on the type of fiber, pigment and dye mixing, bleached or unbleached, etc. The basis weight can be adjusted by adjusting the raw material concentration and the raw material discharge part. The adjustment can be made by changing the fiber type, blending ratio, fiber length, beating degree, and the like.

  As the core-sheath type heat-fusible fiber, the sheath component is ethylene acrylic acid (EAA, acrylic acid content is about 10 wt%, melting point 95 ° C.), the core component is polypropylene (PP, melting point 160 ° C.), and the fineness is 2.2 dtex. The thing of fiber length 5mm was used. High-melting polyvinyl alcohol (PVA) fibers (melting point> 100 ° C., fineness 1.2 dtex, fiber length 3 mm) as hydrophilic fibers, and low-melting polyvinyl alcohol (PVA) fibers (melting point 60 ° C., fineness 1.2 dtex) as binder fibers. , Fiber length 3 mm) was used.

  First, a nonwoven fabric was produced by a wet method. The core-sheath type heat-fusible fiber (4), hydrophilic fiber (5), and binder fiber were uniformly dispersed in water at a dilute concentration to prepare a suspension of each fiber. Each of these suspensions was blended and uniformly dispersed so that the ratio of core-sheath type heat-fusible fiber 50%, hydrophilic fiber 30%, and binder fiber 20%, and the mixed fiber suspension was screened. A sheet-like web was formed by sheeting on top.

The removed web is dewatered between rollers, passed through a drying device, and dried by heating. By forming the sheath of the core-sheath type heat-fusible fiber (4) and the heat-bonding of the binder fiber, the constituent fibers are bonded to form a sheet-like nonwoven fabric (2). The dried nonwoven fabric (2) is wound up by a reel device. The basis weight of the nonwoven fabric was 15 ± 3 g / m ² .

  Next, a multi-layer laminated paper was made using the long web paper machine (8) shown in FIG. The lower stock (15) discharged from the lower stock supply tank (12) passes through the gap between the lower stock sealing plate (17) and the wire (9), and is circulated on the upper surface of the wire (9) being circulated. Supply. The lower stock (19) supplied on the wire (9) is sent in the paper making direction as a lower stock layer (lower wet paper) (19).

  The nonwoven fabric (2) produced by the above method is set on the nonwoven fabric supply drum (20), and the nonwoven fabric (2) is continuously supplied from the nonwoven fabric supply device (13) to the upper surface of the lower stock layer (19). The upper stock (16) discharged from the upper stock supply tank (14) is further sealed on the upper surface of the strip-shaped nonwoven fabric (2) overlapped with the pulp fibers of the lower stock (15). Supply is made through a gap between the plate (18) and the wire (9).

  The upper stock (16) overlaps with the nonwoven fabric (2) while being fed in the paper making direction as the upper stock layer (22) on the wire (9), and the upper stock (16) is between the fibers of the nonwoven fabric (2). Get in. Thereby, the pulp fibers of the upper stock (16) are entangled with the fibers of the non-woven fabric (2) and are also entangled with the pulp fibers of the lower stock (15) that have already entered the non-woven fabric (2). The fibers of the pulp fiber and the nonwoven fabric (2) are entangled and a strong bond between the two is generated. Moreover, by the hydrogen bond between the carboxyl group of the sheath part of the core-sheath type heat-fusible fiber (4) and the hydroxyl group of the hydrophilic fiber (5) and the carboxyl group and hydroxyl group of the cellulose fiber of the paper layer (15). Further, the bonding force between the fiber layer and the nonwoven fabric layer fiber is increased.

  The multilayer laminated paper (6) laminated in the multilayer structure passes through the water squeezing box (23), and further passes through the drying drum device (25) at 50 to 120 ° C. to be dried by heating, and the core-sheath type heat fusion Due to the heat-sealing effect of the sheath portion of the adhesive fiber (4), the interlaminar bond strength is further increased, and a multilayer laminated paper having an excellent anti-peeling effect is completed.

(Comparative Example 1)
A nonwoven fabric consisting only of polyvinyl alcohol (PVA) fibers was used. 70% high melting point main fiber (PVA, melting point> 100 ° C., fineness 1.2 dtex, fiber length 3 mm), low melting point binder fiber (PVA, melting point 70 ° C., fineness 1.2 dtex, fiber length 3 mm) 30% A nonwoven fabric was prepared by a wet method. The papermaking method and conditions are the same as those described in Example 1. The basis weight of the nonwoven fabric was 12 ± 2 g / m ² .

  A multilayer laminated paper was made using the multilayer laminated paper manufacturing apparatus shown in FIG. The papermaking method and conditions are the same as those described in Example 1.

  FIG. 5 shows the peel strength of the multilayer laminated paper made in Example 1 and Comparative Example 1.

  Based on these peel strengths, the multilayer laminated paper using the nonwoven fabric blended with the core-sheath type heat-fusible fiber (Example 1) is the multilayer ply paper using the nonwoven fabric not blended with the core-sheath type heat-fusible fiber. It can be seen that the peel strength is higher than that of the laminated paper (Comparative Example 1). The delamination strength between the paper material layer and the nonwoven fabric layer was improved by the heat fusion effect of the sheath portion of the core-sheath type heat-fusible fiber (4).

  In addition, since the core-sheath-type heat-fusible fiber has a sheath having a component having a melting point of 95 ° C., the decrease in peel strength in hot water resistance after being dipped in 90 ° C. warm water and dried again can be suppressed. It was. In Comparative Example 1, since heat bonding is performed only with a binder fiber having a low melting point of 90 ° C. or less, when immersed in warm water at 90 ° C., the binder fiber is melted, and the peel strength in hot water resistance is remarkably reduced. . However, by blending the core-sheath type heat-fusible fiber, a significant decrease in peel strength in hot water resistance was suppressed.

  As the core-sheath type heat-fusible fiber, the sheath component is ethylene acrylic acid (EAA, acrylic acid content is about 10 wt%, melting point 95 ° C.), the core component is polypropylene (PP, melting point 160 ° C.), and the fineness is 2.2 dtex. The thing of fiber length 5mm was used. High-melting polyvinyl alcohol (PVA) fibers (melting point> 100 ° C., fineness 1.2 dtex, fiber length 3 mm) as hydrophilic fibers, and low-melting polyvinyl alcohol (PVA) fibers (melting point 60 ° C., fineness 1.2 dtex) as binder fibers. , Fiber length 3 mm) was used.

First, a nonwoven fabric was produced by a wet method. The papermaking method and conditions are the same as those described in Example 1. The blending ratio of each fiber was 50% core-sheath type heat-fusible fiber, 20% hydrophilic fiber, and 30% binder fiber. The basis weight of the nonwoven fabric was 15 ± 3 g / m ² .

The liquid binder was apply | coated to the nonwoven fabric using the coater apparatus. As the liquid binder, an acrylate latex having a glass transition temperature of 43 ° C. was used. It was applied by an impregnation method, dried through a drum dryer, and wound around a paper tube to produce a binder-coated nonwoven fabric. The coating amount was 5 ± 1 g / m ² by dry weight.

  Next, the multilayer laminated paper was made using the multilayer laminated paper manufacturing apparatus shown in FIG. The papermaking method and conditions are the same as those described in Example 1.

  When the multilayer laminated paper (6) laminated in the multilayer structure passes through a drying drum apparatus (25) at 50 to 120 ° C. and is heat-dried, the sheath of the core-sheath type heat-fusible fiber (4) Due to the synergistic effect of heat fusion of the part, the binder fiber and the applied liquid binder, the interlaminar bond strength is further increased, and a multilayer laminated paper having an excellent anti-peeling effect is completed.

  As the core-sheath type heat-fusible fiber, the same fiber as described in Example 1 was used. High melting point polyvinyl alcohol (PVA) fiber (melting point> 100 ° C., fineness 1.2 dtex, fiber length 3 mm) as hydrophilic fiber, polyethylene terephthalate (PET) fiber (melting point 110 ° C., fineness 1.7 dtex, fiber) as binder fiber 5 mm long) was used.

First, a nonwoven fabric was produced by a wet method, and a liquid binder was applied thereto. The papermaking method and conditions are the same as in Example 1, and the binder application method and conditions are the same as in Example 2. The blending ratio of each fiber was 50% core-sheath type heat-fusible fiber, 20% hydrophilic fiber, and 30% binder fiber. The basis weight of the nonwoven fabric was 15 ± 3 g / m ² , and the binder coating amount was 5 ± 1 g / m ² (dry weight).

  Next, using the multilayer laminated paper manufacturing apparatus shown in FIG. The papermaking method and conditions are the same as those described in Example 1.

  As the core-sheath type heat-fusible fiber, the same fiber as described in Example 1 was used. Rayon fiber (fiber length 2 mm) was used as the hydrophilic fiber.

First, a nonwoven fabric was produced by a wet method, and a liquid binder was applied thereto. The papermaking method and conditions are the same as in Example 1, and the binder application method and conditions are the same as in Example 2. The blending ratio of each fiber was 50% core-sheath type heat-fusible fiber and 50% hydrophilic fiber. The basis weight of the nonwoven fabric was 15 ± 3 g / m ² , and the binder coating amount was 5 ± 1 g / m ² (dry weight).

  Next, using the multilayer laminated paper manufacturing apparatus shown in FIG. The papermaking method and conditions are the same as those described in Example 1.

  As the core-sheath type heat-fusible fiber, the same fiber as described in Example 1 was used. Rayon fibers (fiber length 2 mm) were used as hydrophilic fibers, and low-melting polyvinyl alcohol (PVA) fibers (melting point 60 ° C., fineness 1.2 dtex, fiber length 3 mm) were used as binder fibers.

First, a nonwoven fabric was produced by a wet method, and a liquid binder was applied thereto. The papermaking method and conditions are the same as in Example 1, and the binder application method and conditions are the same as in Example 2. The blending ratio of each fiber was 50% core-sheath fiber, 30% hydrophilic fiber, and 20% binder fiber. The basis weight of the nonwoven fabric was 15 ± 3 g / m ² , and the binder coating amount was 5 ± 1 g / m ² (dry weight).

  Next, using the multilayer laminated paper manufacturing apparatus shown in FIG. The papermaking method and conditions are the same as those described in Example 1.

  As the core-sheath type heat-fusible fiber, the same fiber as described in Example 1 was used. Rayon fiber (fiber length 2 mm) was used as the hydrophilic fiber, and polyethylene terephthalate (PET) fiber (melting point 110 ° C., fineness 1.7 dtex, fiber length 5 mm) was used as the binder fiber.

First, a nonwoven fabric was produced by a wet method, and a liquid binder was applied thereto. The papermaking method and conditions are the same as in Example 1, and the binder application method and conditions are the same as in Example 2. The blending ratio of each fiber was 50% core-sheath type heat-fusible fiber, 20% hydrophilic fiber, and 30% binder fiber. The basis weight of the nonwoven fabric was 15 ± 3 g / m ² , and the binder coating amount was 5 ± 1 g / m ² (dry weight).

  Next, using the multilayer laminated paper manufacturing apparatus shown in FIG. The papermaking method and conditions are the same as those described in Example 1.

  As the core-sheath type heat-fusible fiber, the same fiber as described in Example 1 was used.

First, a nonwoven fabric was produced by a wet method. The papermaking method and conditions are the same as those described in Example 1. Fabricated with 100% core-sheath type heat-fusible fiber, basis weight was 30 ± 3 g / m ² .

The nonwoven fabric surface was subjected to corona discharge treatment. The treatment conditions were discharge energy 6.3 × 10 ⁶ J / m ² .

  Next, using the multilayer laminated paper manufacturing apparatus shown in FIG. The papermaking method and conditions are the same as those described in Example 1.

(Comparative Example 2)
A nonwoven fabric consisting only of polyvinyl alcohol (PVA) fibers was used. 70% high melting point main fiber (PVA, melting point> 100 ° C., fineness 1.2 dtex, fiber length 3 mm), low melting point binder fiber (PVA, melting point 70 ° C., fineness 1.2 dtex, fiber length 3 mm) 30% Then, a nonwoven fabric was produced by a wet method, and a liquid binder was applied thereto. The papermaking method and conditions are the same as in Example 1, and the binder application method and conditions are the same as in Example 2. The basis weight of the nonwoven fabric was 12 ± 2 g / m ² , and the binder coating amount was 5 ± 1 g / m ² (dry weight).

  A multilayer laminated paper was made using the multilayer laminated paper manufacturing apparatus shown in FIG. The papermaking method and conditions are the same as those described in Example 1.

  FIG. 6 shows the peel strength of the multilayer laminated paper made in Examples 2 to 7 and Comparative Example 2.

  Based on these peel strengths, multilayer laminated paper (Examples 2 to 7) using a nonwoven fabric blended with a core-sheath-type heat-fusible fiber used a nonwoven fabric not blended with a core-sheath-type heat-fusible fiber. It can be seen that the peel strength is higher than that of the multilayer laminated paper (Comparative Example 2). The delamination strength between the paper material layer and the non-woven fabric layer was improved by the heat bonding effect by melting the sheath portion of the core-sheath type heat-fusible fiber.

  In addition, since the core-sheath type heat-fusible fiber having a sheath having a component having a melting point of 95 ° C. is used, it is possible to suppress a decrease in peel strength in hot water resistance after being dipped in 90 ° C. warm water and dried again. It was. In Comparative Example 2, heat bonding is performed with a binder fiber having a low melting point of 90 ° C. or less and a coated liquid binder. Therefore, when immersed in warm water at 90 ° C., the binder fiber melts, and the peel strength in hot water resistance is high. Declined. However, by blending a core-sheath type heat-fusible fiber and further applying a liquid binder, even at a level where a low-melting binder fiber is blended (for example, Examples 2 and 5), the peel strength in warm water resistance is almost the same. It did not drop.

  In addition, the nonwoven fabric with only the core-sheath type heat-fusible fiber has low wettability and is water-repellent, so it is not well-suited with the upper and lower paper layers, resulting in uneven formation. By applying the blending or corona discharge treatment, it was possible to produce a multilayer laminated paper having good familiarity with the upper and lower paper layers at the time of papermaking, no uneven formation, and high peel strength.

FIG. 3 shows a cross-sectional view of a multilayer laminated paper in one embodiment of the present invention. Sectional drawing of the core-sheath-type heat-fusible fiber in one Example of this invention is shown. 1 shows an overall configuration of a multilayer laminated paper manufacturing apparatus in an embodiment of the present invention. The fiber mixture ratio of the nonwoven fabric of one Example and a comparative example in this invention is shown. The peeling strength of the multilayer laminated paper of one Example and comparative example in this invention is shown. The peeling strength of the multilayer laminated paper of one Example and comparative example in this invention is shown.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Upper stock layer 2 Nonwoven fabric 3 Lower stock layer 4 Core-sheath type heat-fusible fiber 5 Hydrophilic fiber 6 Multi-layer laminated paper 7 Hot air dryer 8 Long net paper machine 9 Paper making wire 10 Driven pulley 11 Drive Pulley 12 Lower stock supply tank 13 Non-woven fabric feeder 14 Upper stock supply tank 15 Lower stock 16 Upper stock 17 Lower stock stop plate 18 Upper stock stop plate 19 Lower stock layer (lower moisture layer) paper)
20 Nonwoven fabric supply drum 21 Tension roll 22 Upper stock layer (upper wet paper)
23 squeezing box 24 press roll 25 drying device 26 tundy roll 27 reel device 28 core part 29 sheath part

Claims (3)

In a multilayer paper in which at least three layers of an upper stock layer, an intermediate layer and a lower stock layer are laminated,
The intermediate layer is made of a nonwoven fabric obtained by mixing at least a core-sheath type heat-fusible fiber and a hydrophilic fiber. A multilayer laminated paper characterized by being lower than the melting point of its core. In the non-woven fabric, the core-sheath type heat-fusible fiber and the hydrophilic fiber are formed by inter-fiber bonding by heat fusion,
In the multilayer paper, the nonwoven fabric layer fibers of the nonwoven fabric and the stock layer fibers of the upper stock layer and the lower stock layer are formed by interfiber bonding by hydrophilization and thermal fusion. The multilayer laminated paper according to claim 1. A nonwoven fabric is prepared by mixing at least a core-sheath type heat-fusible fiber and a hydrophilic fiber, and the produced nonwoven fabric is combined between an upper stock and a lower stock on a paper machine, an upper stock layer, A multilayer laminated paper having an intermediate layer made of a nonwoven fabric and a lower stock layer is formed, and the multilayer laminated paper is heated and dried within a temperature range including a melting point of the sheath portion of the core-sheath type heat-fusible fiber. A method for producing a multilayer laminated paper characterized by the above.

Images