JP2006118108A - Moisture-proof paper - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide moisture-proof paper which has excellent blocking resistance, excellent dissociability giving excellent waste paper recovery, reduces moisture permeability and water permeability from end bent portions in extents equal to those of polyethylene-laminated paper, when especially used as a packaging material, and can thereby be used for packaging products in widened uses. <P>SOLUTION: This moisture-proof paper produced by forming a moisture-proof layer comprising a pigment, a synthetic resin and a wax on at least one side of a paper substrate is characterized in that the synthetic resin has a coating film elongation in a range of 50 to 160% measured according to JIS K 7127. The pigment is preferably compounded in a solid amount of 0.1 to 50 pts.wt. per 100 pts.wt. of the synthetic resin, and the wax is preferably compounded in a solid amount of 1 to 20 pts.wt. per 100 pts.wt. of the synthetic resin. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an easily disintegrating moisture-proof paper excellent in blocking resistance and excellent in waste paper recoverability, and in particular when used as a packaging material, the moisture-proof property is suppressed to the same level as that of polyethylene laminated paper when used as a packaging material. Regarding paper.

  As a known technique for moisture-proofing / waterproofing and disintegration as wastepaper recovery and a method for producing the same, a mixture of flat pigment, inorganic pigment and synthetic resin latex is used for the moisture-proof composition layer Is common. Japanese Patent Application Laid-Open No. 2000-345494 (Patent Document 1) discloses a moisture-proof paper using an organic pigment, a synthetic resin and a wax in the moisture-proof composition layer. The moisture-proof / waterproof paper produced by these methods has the same performance as the existing moisture-proof paper in terms of moistureproof / waterproof and blocking resistance.

  However, after packaging, the moisture-proof performance declined by bending the corners, and the moisture-proof and waterproof properties of the folded parts were not sufficient compared to polyethylene laminated paper. Therefore, even when stored in a warehouse or the like, dew condensation occurs inside the warehouse or the like due to the effect of climate change (difference between temperature and humidity outside and inside), resulting in a phenomenon that the surface of the wrapping paper gets wet. Due to the influence of this wetting, deformation (rippling phenomenon) of the packing material occurs, which adversely affects printing workability.

JP 2000-345494 A

  An object of the present invention is to provide a moisture-proof paper that is excellent in blocking resistance while maintaining disaggregation and moisture-proof / waterproof properties of folded parts during packaging as used paper recoverability, and can be used for a wider range of product packaging applications. It is in.

  As a means for solving the above-mentioned problems, the present invention provides a moisture-proof paper having a moisture-proof layer comprising a pigment, a synthetic resin and a wax formed on at least one side of a paper base, and has a tensile fracture elongation measured according to JIS K 7127 of 50%. This was achieved by using a synthetic resin having a range of 160% or less.

  The moisture-proof paper obtained by the present invention has excellent anti-blocking properties as well as moisture-proof and waterproof properties and does not adversely affect the packaged products. Is possible.

  The moisture-proof layer of the moisture-proof paper of the present invention is composed of a synthetic resin, a wax and a pigment. The synthetic resin used in the present invention needs to have a tensile elongation at break measured in accordance with JIS K 7127 in the range of 50% to 160%. When the tensile elongation at break is less than 50%, the moisture-proof and waterproof properties of the bent portion are insufficient. In addition, it has a disintegrating property in water, and it is necessary to express a high moisture-proof property by blending wax.

  Examples of the synthetic resin having such performance include styrene / acrylic resins and styrene / butadiene resins. Specifically, styrene and styrene derivatives, butadiene and butadiene derivatives, acrylic acid (methacrylic acid), and acrylic acid esters such as methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, and methyl methacrylate, It is a resin obtained by copolymerizing methacrylic acid esters such as ethyl methacrylate and butyl methacrylate.

  The pigment used in the present invention is an organic pigment composed of styrene resin, acrylic resin, butadiene resin, etc., or heavy calcium carbonate, light calcium carbonate, clay, kaolin, white carbon, talc, mica, etc. An inorganic pigment can be used, but it is also possible to use a mixture of two or more pigments.

  As the wax used in the present invention, known waxes such as paraffin wax, polyethylene wax, microcrystalline wax and the like can be used, but two or more kinds of waxes can also be mixed and used.

  The blending ratio of the synthetic resin and the pigment needs to be 0.1 to 50 parts by weight of the pigment with respect to 100 parts by weight of the synthetic resin as a solid content ratio. When the blending ratio of the pigment is less than 0.1 parts by weight, the anti-blocking property is inferior. It is not preferable because it disappears.

  The blending ratio of the synthetic resin and the wax needs to be 1 part by weight or more and 20 parts by weight or less with respect to 100 parts by weight of the synthetic resin as a solid content ratio. When the blending ratio of the wax is less than 1 part by weight, the moisture-proof property is inferior, and when it exceeds 20 parts by weight, the moisture-proof property is good, but the slip caused by the wax increases, and the coating film forming property decreases. It is not preferable.

The coating amount of the moisture-proof layer of the present invention on the paper substrate is preferably 3 g / m ² or more and 30 g / m ² or less, particularly preferably 10 to ²⁰ g / m ² . If the coating amount is less than 3 g / m ² , the quality such as moisture resistance is not sufficient, and if it exceeds 30 g / m ² , the burden on the drying capacity and various costs increase, which is not preferable in production.

  As a coating method, a commonly used bar coater, air knife coater, blade coater, curtain coater or the like can be used. Moreover, although drying conditions are not specifically limited, It is preferable that it is the melting | fusing point of the wax to be used, or the temperature beyond it. In the present invention, the surface of the base paper opposite to the above coated surface may be coated using a known material for the purpose of anti-slip agent or curl prevention.

  As the base material, paper other than paper having extremely low wet strength such as tissue and toilet paper and not suitable for coating can be used. For packaging applications, strong kraft paper is suitable.

  EXAMPLES Hereinafter, although this invention is explained in full detail according to an Example, this invention is not a thing limited by these. The tensile fracture elongation and tensile fracture strength of the synthetic resins used in Examples and Comparative Examples were measured by the following methods. Moreover, about the moisture-proof paper obtained by the Example and the comparative example, moisture permeability, water permeability, blocking resistance, and disaggregation were measured and evaluated by the method shown below.

-Tensile elongation at break: measured according to JIS K 7127.
-Tensile fracture strength: Measured according to JIS K 7127.
-Moisture permeability: Based on JIS Z 0208 (cup method) B method, measured with the coated surface outside. The folding part is folded in half with the coated surface inside, and a crease is made with a load of 5 kg. Fold it in half again, fold it into a cross, and make a crease with a load of 5 kg. The flat portion is judged to be practically sufficient if the moisture permeability is 50 g / m ² · 24 hr or less. It is determined that the folded portion is practically sufficient if the moisture permeability is 50 g / m ² · 24 hr or less.
-Moisture absorption waving evaluation: A plain-size high-quality paper 64 g / m ² was packaged in moisture-proof paper, and after conditioning for 72 hours under 25 ° C. and 90% RH environmental conditions, the waving state of the high-quality paper inside the packaging was evaluated.
Evaluation criteria;
○: No undulation △: Slight waving ×: Large waving ・ Water permeability: Water is applied to the sample surface of the JIS moisture permeable cup assuming the coated surface is inside and the wrapping paper is wet due to condensation. The tension was measured based on JIS Z 0208 (cup method) B method. The folding part is folded in half with the coated surface inside, and a crease is made with a load of 5 kg. Fold it in half again, fold it into a cross, and make a crease with a load of 5 kg. The flat portion is judged to be practically sufficient if the water permeability is 80 g / m ² · 24 hr or less. If the water permeability is 80 g / m ² · 24 hr or less, the folded portion is judged to be practically sufficient.
Moisture absorption waving Rating: packaging the fine paper 64 g / m ² of A Tairaban moistureproof paper, 10 ° C., after 3 hour hold at 50% RH conditions, by condensing 25 ° C., by changing to 90% RH environmental conditions It was. After conditioning for 72 hours under these conditions, the wavy state of the fine paper inside the package was evaluated.
Evaluation criteria;
○: No undulation △: Slight undulation ×: Large undulation ・ Blocking resistance: Moisture-proof paper After conditioning at 23 ° C and 50% RH, anti-slip layer and coated paper of moisture-proof paper (trade name: NPi Coat, Japan) Papermaking (manufactured by Paper Manufacturing Co., Ltd.) was overlapped and passed once through a test calendar (linear pressure 50 kg / cm ² , paper feeding speed 10 m / min) and evaluated for the presence or absence of blocking when peeled immediately.
Evaluation criteria;
○: There is no resistance at the time of peeling, and there is no sound at the interface between the moisture-proof layer of the moisture-proof paper and the coated paper.
X: There is resistance at the time of peeling, and the moisture-proof layer of the moisture-proof paper and the coated paper are bonded together, so that a crisp sound is made at the interface between the moisture-proof layer of the moisture-proof paper and the coated paper.
-Disaggregation property: Using a standard disaggregator (Taapi standard disaggregator used: 3000 rpm) shown in JIS P 8222 (pulp test handmade paper adjustment method), cut into about 2.5 cm square in room temperature tap water. The moisture-proof paper was added in an amount to give a pulp concentration of 3% by weight and disaggregated for 15 minutes. The handmade paper produced from the raw material after disaggregation was evaluated visually.
Evaluation criteria;
(Double-circle): Undissolved material is not recognized at all and is disaggregated to the same extent as high-quality paper.
○: A fine undissolved bundling fiber can be confirmed.
Δ: Undissolved paper pieces can be confirmed.
X: A piece of paper, a film, a resin or the like that is not disaggregated remains as it is.

[Example 1]
Styrene / acrylic synthetic resin emulsion (trade name: Cybinol X-504-302E-1, manufactured by Seiden Chemical Co., Ltd.) 100 parts by weight (solid content weight) and wax emulsion (trade name: Cybinol SKP-W, Seiden Chemical) (Made by Co., Ltd.) 4 parts by weight (solid content weight) and 4 parts by weight of an organic pigment (trade name: G-200, manufactured by Negami Kogyo Co., Ltd.) were prepared. The tensile elongation at break of this styrene / acrylic synthetic resin was 155%. This mixed solution was applied to one side of unbleached kraft paper having a basis weight of 75 g / m ² with an air knife coater so that the coating amount was 16 g / m ² to provide a moisture-proof layer, and moisture-proof paper was produced. The obtained moisture-proof paper was evaluated by measuring moisture permeability, water permeability, moisture absorption waving, blocking resistance and disaggregation, and Table 1 shows the results. Each evaluation method was as shown below.

[Example 2]
A styrene / acrylic synthetic resin emulsion (trade name: Cybinol X-504-302E-4, manufactured by Seiden Chemical Co., Ltd.) having a tensile elongation at break of 143% was used for the moisture-proof layer. A moisture-proof paper was produced in the same manner as in Example 1 except that this styrene / acrylic synthetic resin was used. Each evaluation was performed and the results are shown in Table 1.

[Example 3]
A styrene / acrylic synthetic resin emulsion (trade name: Cybinol X-504-302E-5, manufactured by Seiden Chemical Co., Ltd.) having a tensile fracture elongation of 153% was used for the moisture-proof layer. A moisture-proof paper was produced in the same manner as in Example 1 except that this styrene / acrylic synthetic resin was used. Each evaluation was performed and the results are shown in Table 1.

[Comparative Example 1]
A styrene / acrylic synthetic resin emulsion (trade name: Cybinol N-4, manufactured by Seiden Chemical Co., Ltd.) having a tensile elongation at breakage of 40% was used for the moisture-proof layer. A moisture-proof paper was produced in the same manner as in Example 1 except that this styrene / acrylic synthetic resin was used. Each evaluation was performed and the results are shown in Table 1.

[Comparative Example 2]
A styrene / acrylic synthetic resin emulsion (trade name: Cybinol X-504-302E-2, manufactured by Seiden Chemical Co., Ltd.) having a tensile breaking elongation of 168% was used for the moisture-proof layer. A moisture-proof paper was produced in the same manner as in Example 1 except that this styrene / acrylic synthetic resin was used. Each evaluation was performed and the results are shown in Table 1.

[Comparative Example 3]
A styrene / acrylic synthetic resin emulsion (trade name: Cybinol X-504-302E-3, manufactured by Syden Chemical Co., Ltd.) having a tensile breaking elongation of 238% was used for the moisture-proof layer. A moisture-proof paper was produced in the same manner as in Example 1 except that this styrene / acrylic synthetic resin was used. Each evaluation was performed and the results are shown in Table 1.

[Comparative Example 4]
As the moisture-proof paper, polyethylene laminated paper (lamination thickness 15 μm) was used, and each evaluation was performed in the same manner as in Example 1, and the results are shown in Table 1.

表１に示したように、引張破壊伸びが50％以上160％以下の合成樹脂を使用した実施例１〜３の防湿紙は、透湿度、透水度、耐ブロッキング性、離解性において優れている。これに対して、引張破壊伸びが50％未満の合成樹脂を使用した比較例１は、十字折り部の透湿度、透水度が悪化し、包装折り部からの吸湿で吸湿波打ちが発生した。また、引張破壊伸びが160％を超えた合成樹脂を使用した比較例２、３は透湿度、透水度が悪化し、更に耐ブロッキング性も悪化した。また、比較例３は離解性も悪化した。比較例４はポリエチレンラミネート紙であるため離解性が劣る。

As shown in Table 1, the moisture-proof paper of Examples 1 to 3 using a synthetic resin having a tensile elongation at break of 50% or more and 160% or less is excellent in moisture permeability, water permeability, blocking resistance, and disaggregation. . On the other hand, in Comparative Example 1 using a synthetic resin having a tensile elongation at break of less than 50%, the moisture permeability and water permeability of the cross-folded portion deteriorated, and moisture absorption undulation occurred due to moisture absorption from the package folded portion. Further, Comparative Examples 2 and 3 using a synthetic resin having a tensile elongation at break exceeding 160% deteriorated moisture permeability and water permeability, and further deteriorated blocking resistance. Moreover, the comparative example 3 also deteriorated the disaggregation property. Since Comparative Example 4 is a polyethylene laminated paper, the disintegration property is inferior.

Claims (1)

In a moisture-proof paper having a moisture-proof layer comprising a pigment, a synthetic resin and a wax formed on at least one side of a paper substrate, the tensile fracture elongation of the synthetic resin measured in accordance with JIS K 7127 is in the range of 50% to 160%. Moisture-proof paper characterized by being.