JP4480448B2 - Waterproof paper - Google Patents

Description

  The present invention is a water-resistant paper provided with a coating layer containing at least a binder component on one side or both sides of a base paper mainly composed of wood pulp fiber, which has excellent adhesive strength with a laminate layer, and after resin lamination It is related with the water-resistant paper which has the heat-sealing ability of.

  In order to provide water resistance, a resin laminate may be provided on one or both sides of the paper. When bonding such waterproof papers by heat sealing, thermocompression bonding is performed with the resin laminate layer side of one waterproof paper and the base paper side of the other waterproof paper or the resin laminate layer side of both waterproof papers facing each other. However, at this time, because the heat seal device that has been thermocompression bonded and the laminate layer facing this heat seal device are stuck together, when the heat seal device is separated from the laminate paper after thermocompression bonding, a tensile force acts on the laminate layer, Peeling may occur between the laminate layer and the base paper layer. In order to prevent such a situation, the adhesive strength between the paper surface and the laminate layer is strengthened, and consists of an organic titanium-based, isocyanate-based, polyethyleneimine-based, polybutadiene-based compound and / or ethylene / vinyl acetate copolymer. It is known to apply a so-called anchor agent to a base paper (for example, see Non-Patent Document 1).

In order to improve the water resistance of the paper, to inhibit the penetration of water from the surface and the end surface of the paper, usually, or internally added the size agent during base paper production, size press, gate roll coater, A sizing agent is applied to the paper surface with a sizer or the like (for example, see Non-Patent Document 2).
"Laminating that anyone can understand" Koichi Matsumoto Co., Ltd. Processing Technology Research Group, published on October 6, 1998, Chapter 11 Adhesives and AC agents (P144-164) “Paper and Pulp Paper Chemistry and Technology” Volume 3 Reezaburo Oe, Translation and Supervision Chugai Industry Research Committee, issued April 30, 1983, Chapter 16 Internal Sizing (P101-143), Chapter 20 Surface Sizing (P221-) 263)

However, the isocyanate-based and polyethyleneimine-based compounds that are used to strengthen the adhesive strength between the paper surface and the laminate layer have a problem that they may adversely affect the human body. Organic titanium-based compounds are expensive and need to be dissolved in a solvent such as hexane or toluene for coating, and there are problems in operability and safety. Since polybutadiene compounds use alcohol for dilution, they still have problems in operability and safety. Ethylene-vinyl acetate copolymer is not sufficient to provide sufficient sealability. Furthermore, when the adhesive force between the surface of the paper and the laminate layer is increased using these anchor agents, there is a problem that the cushioning property is deteriorated and the printability is deteriorated.

  The inventors of the present invention have strengthened the adhesive force between the paper surface and the laminate layer without using the anchor agent as described above, which may adversely affect the human body or cause problems in operability, etc. As a result of repeated research to obtain water-resistant paper with excellent suitability and excellent printability, it was found that it is effective to apply two types of synthetic resin binders with different Tg to the surface of the paper. The present invention has been completed.

  That is, the object of the present invention is to provide strong adhesion between the surface of the paper and the laminate layer in a manner that has little adverse effect on the human body, operability, etc., excellent heat sealability, and printability. It is to provide an excellent water-resistant paper.

In order to solve the above problems, the invention according to claim 1 is provided with a coating layer containing at least a binder component on one side or both sides of a base paper mainly composed of wood pulp fibers. A water-resistant paper, further comprising a laminate layer made of thermoplastic resin by extrusion lamination , wherein the binder component is a styrene / butadiene copolymer having a glass transition temperature (Tg) of 35 ° C. or higher , styrene / acrylic At least one or more of an acid copolymer, a styrene / maleic acid copolymer, a styrene / butadiene copolymer or an ethylene / vinyl acetate copolymer having a glass transition temperature (Tg) of less than 35 ° C. Are blended at a ratio of 3:97 to 50:50.

Thus, the binder component contained in the coating layer is at least one of a styrene / butadiene copolymer, a styrene / acrylic acid copolymer, and a styrene / maleic acid copolymer having a glass transition temperature (Tg) of 35 ° C. or higher. At least one kind of styrene / butadiene copolymer and ethylene / vinyl acetate copolymer having a glass transition temperature (Tg) of less than 35 ° C. is blended at a ratio of 3:97 to 50:50. In addition, the binder component provides sufficient adhesive strength between the base paper and the laminate layer, and the binder having a glass transition temperature (Tg) of 35 ° C. or higher provides excellent heat sealability. Water absorption from the surface (cobb water absorbency) and end face (end face water absorbency) is small and water resistance is excellent. Furthermore, a binder having a glass transition temperature (Tg) of less than 35 ° C. provides cushioning properties and excellent printability.

  The invention according to claim 2 is characterized in that the coating layer according to claim 1 further contains a pigment.

  As described above, when the coating layer contains a pigment in addition to the binder component, the coverage of the base paper is improved and the printability is excellent.

  The invention described in claim 3 is characterized in that the pigment described in claim 2 is a flat pigment.

  Thus, when the pigment is a flat pigment, the printability can be further improved.

The invention according to claim 4 is characterized in that the coating amount of the binder component of the coating layer according to claim 1, 2 or 3 is 0.5 g / m ² or more and 10 g / m ² or less. And

Thus, when the coating amount of the binder component of the coating layer is 0.5 g / m ² or more and 10 g / m ² or less, sufficient adhesive strength is provided between the base paper and the laminate layer, It is particularly excellent in heat sealability, water resistance and printability.

  As described above, according to the present invention, sufficient adhesion strength can be obtained between the surface of the paper and the laminate layer by a method having little adverse effect on the human body, excellent heat sealability, excellent water resistance, and printability. Water-resistant paper suitable for applications that require water resistance and excellent printability, such as wrapping paper, paper bags, paper containers, paper boxes, outdoor posters, paper cups, etc. Can be obtained.

  Hereinafter, an example of the best mode for carrying out the waterproof paper according to the present invention will be described.

  The waterproof paper of this example is provided with a coating layer containing at least a binder component on one side or both sides of a base paper mainly composed of wood pulp fibers, and a laminate layer made of a thermoplastic resin is formed on the coating layer. Further, a water-resistant paper provided, wherein the binder component contained in the coating layer includes at least one binder having a glass transition temperature (Tg) of 35 ° C. or higher (hereinafter referred to as high Tg), and a glass transition temperature (Tg). ) One or more binders of less than 35 ° C. (hereinafter referred to as low Tg) are blended at a ratio of 3:97 to 50:50.

  The base paper mainly composed of wood pulp fiber mainly comprises pulp obtained by appropriately mixing chemical pulp, mechanical pulp, and recycled pulp obtained from wood, and non-wood pulp such as kenaf and bamboo, and glass fiber. Fiber materials other than cellulose fibers, such as polyethylene fibers, can be blended as necessary and made by a normal paper making process. At this time, fillers such as talc, kaolin, clay, heavy calcium carbonate, light calcium carbonate, titanium dioxide, and general chemicals such as paper strengthening agents, sizing agents, antifoaming agents, and coloring agents are added as appropriate. can do. Moreover, you may mix | blend fiber materials other than cellulose fibers, such as non-wood pulp, such as kenaf and bamboo, glass fiber, and polyethylene fiber, with the said wood pulp fiber as needed.

  In addition, there is no restriction | limiting in particular in the basic weight of the said base paper, According to the use of the water-resistant paper of this invention, it can select suitably.

  Further, this base paper may be subjected to surface sizing treatment using starch, polyvinyl alcohol, polyacrylamide or the like using a size press, a gate roll coater, or a pre-metering size press.

  As the binder for the coating layer provided on the base paper, at least two types of binders, one or more high Tg binders and one or more low Tg binders, are used. Examples of the high Tg binder include aqueous emulsions such as styrene / acrylic acid copolymers, styrene / maleic acid copolymers, olefin copolymers, alkyl copolymers, styrene / acrylic acid, styrene / maleic acid, It is preferable to use at least one of an acrylic-based, olefin-based, alkyl-based water-soluble binder or an insect shell alkaline solution. In addition, as a low Tg binder, at least one of SBR (styrene butadiene copolymer), vinyl acetate copolymer, ethylene vinyl acetate copolymer, acrylic copolymer, urethane copolymer, etc. is used. It is preferable to do.

  Among these binders, starch, polyvinyl alcohol, and casein have a strong hydrophilicity, so that the water resistance of the coating layer is lowered and the printability after lamination is also reduced. It is preferable to stop.

  In the coating layer, the ratio of high Tg binder: low Tg binder is blended so as to be in the range of 3:97 to 50:50. When the ratio of the high Tg binder is higher than 50:50, the coating layer becomes hard, the cushioning property is lowered, and smoothing is difficult even by the supercalender treatment. Getting worse. In particular, at this time, the number of speckles in gravure printing increases. Further, when the ratio of the high Tg binder is less than 3:97, the proportion of the hydrophobic portion of the high Tg binder in the binder component is also small, so that the water resistance is lowered, and it becomes easy to soften by heating. It becomes inferior to heat seal suitability.

The sealability, the heat - is an index indicating the occurrence difficulty of delamination between the laminate layer and the base paper in the case of performing bonding by Toshiru. When using a low Tg binder to soften by heat, after thermocompression bonding, if the La Mi sulfonates layer provided thereon is pulled by heat sealing equipment, peeling within the binder layer occurs It is easy to cause peeling between the laminate or the like and the base paper.

In this invention, it is preferable that the coating amount of the binder component of the said coating layer shall be 0.5 g / m < ² > or more and 10 g / m < ² > or less. When the coating amount is less than 0.5 g / m ² , the adhesion between the laminate layer and the base paper, heat sealability, and water resistance are not sufficient. Moreover, when higher than 10 g / m < ² >, the printability after lamination will fall.

The coating layer provided on the base paper may contain a pigment in addition to the binder component. By containing the pigment, the covering property of the base paper is improved, and the printability is improved in either case of printing before lamination or printing after lamination. In particular, the use of white pigment as Pigments, whiteness is improved, and that clear printing can be obtained. The pigment is preferably a flat pigment. When it is a flat pigment, smoothness is obtained on the surface of the coating layer, and clear printing is obtained.

The type of the pigment is not particularly limited. For example, kaolin, clay, engineered kaolin, delaminated clay, heavy clay conventionally used as a pigment for forming a pigment coating layer of coated paper is used. Inorganic pigments such as fine calcium carbonate, light calcium carbonate, talc, titanium dioxide, barium sulfate, calcium sulfate, silicic acid, silicate, colloidal silica, and satin white, and organic pigments such as plastic pigment and binder pigment, if necessary Or 2 or more types can be mixed and used. Even when the coating layer contains a pigment, the coating amount as the binder component is preferably 0.5 g / m ² or more and 10 g / m ² or less for the same reason as described above.

  The water-resistant paper of the present invention is obtained by preparing a coating layer by dispersing at least the above binder in an aqueous solvent to prepare a coating solution and then coating the coating solution on at least one side of the base paper. .

  In addition to the binder or binder and pigment, the coating liquid may contain an auxiliary agent such as a dispersant, a water retention agent, a water resistance agent, a lubricant, an antifoaming agent, a preservative, and a dye as necessary. Also good. The coating liquid is usually prepared by adding (adding), dispersing, and adjusting pigments, binders, and auxiliary agents in this order. However, in the present invention, this order may be appropriately changed. .

  To apply the coating liquid, various coating devices such as blade coaters, air knife coaters, bar coaters, curtain coaters, spray coaters, gravure coaters, gate roll coaters, size presses, bill blade coaters, and velvapa coaters must be adopted. Can do.

In the waterproof paper of the present invention, other layers may be present in addition to the coating layer. For example, as a lower layer of the coating layer, one or more coating liquids containing a pigment and a binder may be preliminarily applied to form a preliminary coating layer. Also for this coating layer, if at least two binders of high Tg and low Tg are set so that the ratio of high Tg binder: low Tg binder is in the range of 3:97 to 50:50, the laminate layer and the base paper The adhesive strength, heat sealability, water resistance (water absorption at the end face), and printability are further improved.

  In order to further improve the water resistance and printability, the water-resistant paper of the present invention is preferably subjected to a calendar treatment at a high temperature and a high linear pressure on the base paper after the coating process. However, if the base paper is crushed too much by calendering, the paper thickness will decrease and the stiffness will decrease, so the calender temperature and linear pressure at this time will be high and high linear pressure enough to ensure the paper thickness. It is preferable to do. Specifically, the soft calendar process or the super calendar process is preferably performed at a calendar temperature of 60 ° C. or higher.

According to the present invention described above, by using at least two kinds of synthetic resin binders having high Tg and low Tg, the ratio of high Tg binder / low Tg binder is set in the range of 3:97 to 50:50, By providing an adhesive layer between the laminate layer and the base paper, heat sealability, printability and water resistance, and at least 0.5 g / m ² or more and 10 g / m ² or less of a coating layer comprising a synthetic resin binder is provided. It is possible to obtain a water-resistant paper having excellent adhesion between the laminate layer and the laminate layer .
In addition, in the laminated structure of the water-resistant paper in the present invention, in addition to the base paper / coating layer / laminate layer, the coating layer / base paper / coating layer / laminate layer, laminate layer / coating layer / base paper / Coating layer / laminate layer may be used. Also, the laminate layer may be two or more layers, and there may be other layers other than the coating layer and the laminate layer, such as a printing layer.

  EXAMPLES Hereinafter, although an Example and a comparative example demonstrate this invention concretely, this invention is not limited by these.

  The Cobb water absorption, end surface water absorption, laminate adhesiveness, gravure printability and heat sealability measured in Examples and Comparative Examples were measured and evaluated by the following methods.

<Cobb water absorption>
This was performed according to JIS P8140.

< End face water absorption>
Measurement was performed according to the following procedure, and the end face water absorption was calculated.

(1) A polyethylene adhesive tape was applied to both surfaces of a base paper provided with a coating layer containing a binder or a binder and a pigment obtained in Examples and Comparative Examples so that air would not enter. After preventing water absorption, five test pieces are prepared by cutting 50 mm in the vertical direction (MD direction) × 50 mm in the horizontal direction (CD direction), and an electronic basis weight scale capable of measuring each weight to the third decimal place. Measured using.

(2) Each test piece was immersed in pure water in a pad so as not to overlap, and the weight was placed on the test piece to prevent lifting. In addition, the pure water used what was left to stand in the constant temperature and humidity chamber of 23 degreeC and 50% for one day.

(3) After 60 minutes, each test piece was taken out from pure water, and moisture adhering to the surface was quickly removed with a blotting paper, and each weight was measured in the same manner as in ( 1) above. .

(4) From the weight of the test piece before dipping in pure water (weight before dipping) and the weight after dipping (weight after dipping), the end face water absorption was calculated using the following formula.

End surface water absorption = (weight after immersion−weight before immersion) (mg / m)

<Laminate adhesion>
Pre-melted low-density polyethylene (MFR 7.2 g / 10 min at 190 ° C., density 0.917 g / cm ³ , melting point 106 ° C.) contains the binder or binder and pigment obtained in the examples and comparative examples. On one side coated surface of the base paper provided with a coating layer, extrusion lamination is performed using a T-die at an extrusion temperature of 300 ° C., and then the base paper and the molten laminate layer are pressure-bonded by a matte finish cooling roll. Thus, a laminate sheet was prepared in which a low-density polyethylene layer having a thickness of 20 μm was provided on one side of the base paper.

  The peel strength between the base paper and the laminate layer was evaluated by the following method.

(1) The laminate sheet is cut into a rectangle of 20 cm or more (length) in the MD direction and 15 mm (width) in the CD direction, and a part of the end in the MD direction is formed between the base paper and the laminate layer. Peel at the interface.

(2) After reinforcing the laminate layer peeled off from the base paper with tape, peel about 2 cm further from the end in the MD direction, and measure the tensile strength of the laminate layer reinforced with tape and the end in the MD direction of the base paper. Fix to a machine (Tensilon meter) and peel at a speed of 100 mm / min.

(3) The state of peeling after peeling was observed with the naked eye, and the results were evaluated according to the following criteria.

Peeling occurs at the interface between the base paper and the laminate layer ×
(Adhesive strength between base paper and laminate layer <In-layer peel strength of base paper)
Peeling (breaking) occurs in some of the base paper, but the rest is peeling at the interface between the base paper and the laminate layer.
All peeling (destruction) occurs inside the base paper.
(Adhesive strength between base paper and laminate layer> In-layer peel strength of base paper)

<Gravure printing aptitude>
A laminate layer was provided in the same manner as described above on a single-side coated surface of a base paper provided with a binder or a coating layer containing a binder and a pigment obtained in Examples and Comparative Examples. Printing is performed at a printing speed of 20 m / min and a printing pressure of 30 kgf / cm using a printing gravure printing machine, and the number of missing dots is counted for a halftone dot portion of the obtained printed matter with an area ratio of 40%. Was calculated and evaluated according to the following criteria.

◯: The dot missing rate is 2 . 5% or less ×: Halftone dot loss rate is over 2.5%

<Heat seal suitability>
On the single-side coated surface of the base paper provided with the coating layer containing the binder or the binder and the pigment obtained in the examples and comparative examples, a laminate sheet is prepared in the same manner as described above, and a laminate sheet is created. About this laminate sheet, a heat seal tester (TP-701S manufactured by Tester Sangyo Co., Ltd.) was used, and a simulation test of surface peeling during heat sealing was performed by the following method.

(1) The laminate sheet and the polyethylene terephthalate (PET) film are cut so as to be about 30 cm in the MD direction and 5 cm in the CD direction.

(2) Set the temperature of the upper heater of the heat seal tester to 200 ° C. and the temperature of the lower heater to room temperature.

(3) The PET film is laminated on the laminate layer side of the sample, and this sample is set on the heat seal tester so that the base paper side faces the upper heater and the PET film side faces the lower heater. That is, in this simulation test, the PET film corresponds to the surface material of the heat seal device in the actual machine.

(4) In this state, the sample is pressed for 7 seconds at an air pressure display of 4.5 kg / cm ² .

(5) Immediately after the pressing, the laminate sheet and the PET film are quickly peeled off by hand.

(6) The peeling part of the said laminate sheet and PET film was observed with the naked eye, and the following references | standards evaluated. At this time, when visual observation was difficult, the peeled portion was cut in the thickness direction, and the cross section was observed with an optical microscope or an electron microscope for evaluation.

The inside of the base paper peels off (breaks in the base paper layer) ○
Break in the laminate layer ○
All peeling at the interface between the base paper and the laminate layer ×

[Example 1]
A low Tg binder A (styrene / butadiene copolymer, Tg: −20 ° C.) and a high Tg binder D (styrene / butadiene copolymer, Tg: 40 ° C.) as a binder have a solid content ratio of 95/5. A coating liquid containing 20% by weight of a binder component formulated so as to have a solid content of 150 g / m ^{2 on} a single surface of a high-quality paper having a basis weight of 150 g / m ² and a thickness of 210 μm with an air knife coater at a coating speed of 100 m / min. After the coating amount of 4 g / m ² was applied to obtain the water-resistant paper base paper of the present invention, the base paper was manually subjected to a soft calendar process. At this time, the soft calender process uses a test calendar manufactured by Yuri Roll Co., Ltd., and the above base paper cut into A4 size is composed of a metal roll having a diameter of 200 mm and a temperature of 75 ° C., a soft roll having a diameter of 300 mm and a Shore D hardness of 88. In the meantime, it was performed by passing it once at a speed of 8.6 m / min and a linear pressure of 20 kN / m with the coated surface facing the metal roll.

  For water-resistant paper after soft calendering, the results of measurement of cobb water absorption, end face water absorption, and laminate sheets provided with a laminate layer on the coated surface after the soft calendering are suitable for gravure printing, laminating adhesion, heat Table 1 shows the results of evaluation of seal suitability. As is clear from Table 1, the obtained base paper has low cobb water absorbency and end face water absorbency, and a laminate sheet provided with a laminate layer has excellent gravure printability, laminate adhesiveness, and heat sealability. there were.

[Example 2]
As a binder component, a low Tg binder C (ethylene / vinyl acetate copolymer, Tg: 30 ° C.) and a high Tg binder F (styrene / maleic acid copolymer, Tg: 130 ° C.) with a solid content ratio of 55 The water-resistant paper base paper of the present invention was produced in the same manner as in Example 1 except that the composition was blended so as to be / 45, subjected to soft calendering treatment, Cobb water absorption, end face water absorption The laminate sheet obtained from this base paper was evaluated for gravure printability, laminate adhesiveness, and heat sealability.

  The results are shown in Table 1. As is clear from Table 1, the base paper obtained at this time has low Cobb water absorbency and end face water absorbency, and a laminate sheet provided with a laminate layer has gravure printability, laminate adhesiveness, and heat sealability. It was good.

[Example 3]
As binder components, a low Tg binder B (styrene / butadiene copolymer, Tg: 0 ° C.) and a high Tg binder E (styrene / acrylic acid copolymer, Tg: 80 ° C.) with a solid content ratio of 80 / Except for using what was blended to be 20, the water-resistant paper base paper of the present invention was produced in the same manner as in Example 1 and subjected to soft calendering, and the Cobb water absorption and end face water absorption were determined. The laminate sheet obtained from this base paper was evaluated for gravure printability, laminate adhesiveness, and heat sealability.

  The results are shown in Table 1. As is clear from Table 1, the base paper obtained at this time has low Cobb water absorbency and end face water absorbency, and a laminate sheet provided with a laminate layer has gravure printability, laminate adhesiveness, and heat sealability. It was good.

[Example 4]
A water-resistant paper base paper of the present invention was produced in the same manner as in Example 1 except that the coating amount was 0.7 g / m ² so that the solid content was 0.7 g / m ^2. The water absorption and end face water absorption were measured, and the laminate sheet obtained from this base paper was evaluated for gravure printability, laminate adhesion, and heat sealability.

  The results are shown in Table 1. As is clear from Table 1, the base paper obtained at this time has low Cobb water absorbency and end face water absorbency, and a laminate sheet provided with a laminate layer has gravure printability, laminate adhesiveness, and heat sealability. It was good.

[Example 5]
A coating liquid containing a binder component in which a low Tg binder C and a high Tg binder F are blended so that the solid content ratio is 55/45 is applied so that the solid content is 9 g / m ^2. The water-resistant paper base paper of the present invention was manufactured in the same manner as in Example 1 except that the processing was performed, the soft calendering treatment was performed, and the Cobb water absorption and the end face water absorption were measured. The obtained laminate sheet was evaluated for gravure printability, laminate adhesiveness, and heat sealability.

  The results are shown in Table 1. As is clear from Table 1, the base paper obtained at this time has low Cobb water absorbency and end face water absorbency, and a laminate sheet provided with a laminate layer has gravure printability, laminate adhesiveness, and heat sealability. It was good.

[Example 6]
To a pigment slurry having the composition shown below containing 100 parts by weight of pigment, 20 parts by weight of a binder component prepared by blending a low Tg binder B and a high Tg binder E so that the solid content ratio is 80/20 is added to the aqueous solvent. dispersed to prepare a concentration of 58 wt% of the coating liquid, coating of the coating liquid at a coating speed 400 meters / minute at a blade coater, a each 10 g / m ² at a time 2 Kainuriko the (binder component The amount is 3.3 g / m ² ). Other than that, the water-resistant paper base paper of the present invention was produced in the same manner as in Example 1 and subjected to soft calender treatment to measure the Cobb water absorbency and the end face water absorbency. The laminated sheets were evaluated for gravure printing suitability, laminate adhesiveness, and heat seal suitability.

  The results are shown in Table 1. As is clear from Table 1, the base paper obtained at this time has low Cobb water absorbency and end face water absorbency, and a laminate sheet provided with a laminate layer has gravure printability, laminate adhesiveness, and heat sealability. It was good.

<Pigment slurry composition>
Solid content by weight
First grade kaolin ("UW90" manufactured by Engelhard) 20 parts
2nd grade kaolin ("Caob Light" manufactured by Seal) 50 parts
30 parts of heavy calcium carbonate (Fimatic "FMT90")
Dispersant ("Aron T40" manufactured by Toa Gosei Chemical Industry Co., Ltd.) 0.2 part NaOH 0.1 part

[Example 7]
A water-resistant paper base paper of the present invention was produced in the same manner as in Example 6 except that the coating liquid 12 g / m ^{2 was} applied once (the coating amount as the binder component was 2 g / m ² ). Then, soft calender treatment was performed to measure the Cobb water absorption and the end surface water absorption, and the laminate sheet obtained from the base paper was evaluated for gravure printability, laminate adhesion, and heat sealability.

  The results are shown in Table 1. As is clear from Table 1, the base paper obtained at this time has low Cobb water absorbency and end face water absorbency, and a laminate sheet provided with a laminate layer has gravure printability, laminate adhesiveness, and heat sealability. It was good.

[Comparative Example 1]
A sample obtained by subjecting the fine paper used in Example 1 to soft calender treatment alone was measured for Cobb water absorption and end surface water absorption, and this sample was provided with a laminate layer in the same manner as described above. The sheet was evaluated for gravure printability, laminate adhesion, and heat sealability.

  The results are shown in Table 2. As is clear from Table 2, the samples obtained at this time had high cobb water absorption and end surface water absorption, and the laminate sheet provided with a laminate layer was excellent in gravure printing suitability. The heat sealability was poor.

[Comparative Example 2]
Except for using only the low Tg binder C as the binder component, a water-resistant paper base paper was produced in the same manner as in Example 1, subjected to soft calender treatment, and the Cobb water absorption and end surface water absorption were measured. Further, the laminate sheet obtained from the base paper was evaluated for gravure printing suitability, laminate adhesiveness, and heat seal suitability.

  The results are shown in Table 2. As is apparent from Table 2, the base paper obtained at this time has high Cobb water absorbency and end surface water absorbency, and the laminate sheet provided with a laminate layer on this has excellent gravure printability and laminate adhesiveness. The heat sealability was inferior.

[Comparative Example 3]
As binder component, except for using only the high Tg binder D is in the same manner as in Example 1, to produce a base paper resistant water paper, performs soft calender processing, Cobb water absorption, the end face water absorbing measurements Further, the laminate sheet obtained from the base paper was evaluated for gravure printability, laminate adhesiveness, and heat sealability.

  The results are shown in Table 2. As is apparent from Table 2, the base paper obtained at this time had low Cobb water absorption and low end surface water absorption, and the laminate sheet provided with the laminate layer had excellent laminate adhesion and heat sealability. The gravure printability was poor.

[Comparative Example 4]
As a binder component, the low Tg binder C and high Tg binder F, except that the proportion of solid content was used as the blended so that 30/70, in the same manner as in Example 1, resistance to water feeding groups Paper was manufactured, soft calender treatment was performed, and Cobb water absorption and edge surface water absorption were measured, and the laminate sheet obtained from this base paper was evaluated for gravure printability, laminate adhesiveness, and heat sealability. .

  The results are shown in Table 2. As is apparent from Table 2, the base paper obtained at this time had low Cobb water absorption and low end surface water absorption, and the laminate sheet provided with the laminate layer had excellent laminate adhesion and heat sealability. The gravure printability was poor.

[Comparative Example 5]
As binder component, except for using only the low Tg binder A is in the same manner as in Example 6, to manufacture the base paper resistant water paper, performs soft calender processing, Cobb water absorption, the end face water absorbing measurements Further, the laminate sheet obtained from the base paper was evaluated for gravure printability, laminate adhesiveness, and heat sealability.

The results are shown in Table 2. As is apparent from Table 2, the base paper obtained at this time had high cobb water absorbency and end surface water absorbency, and the laminate sheet provided with the laminate layer had excellent gravure printability and laminate adhesiveness. The heat sealability was inferior.

Claims (4)

On one or both surfaces of the base paper mainly composed of wood pulp fibers, at least the coating layer provided containing a binder component on top of the coating layer, further provided a laminate layer made of a thermoplastic resin by extrusion lamination The binder component is at least one of a styrene / butadiene copolymer, a styrene / acrylic acid copolymer and a styrene / maleic acid copolymer having a glass transition temperature (Tg) of 35 ° C. or higher. And a styrene / butadiene copolymer or an ethylene / vinyl acetate copolymer having a glass transition temperature (Tg) of less than 35 ° C. in a ratio of 3:97 to 50:50. Water-resistant paper characterized by that.   The water-resistant paper according to claim 1, wherein the coating layer further contains a pigment.   The water-resistant paper according to claim 2, wherein the pigment is a flat pigment. The waterproof paper according to claim 1, 2, or 3, wherein the coating amount of the binder component of the coating layer is 0.5 g / m ² or more and 10 g / m ² or less.