Nippon Paper Industries Co., Ltd.

Jujo Thermal Oy

Yuri Oishi

Hiroshi Koyamoto

Masashi Okamoto

Masatsugu Kato

Kenta Watanabe

Masaaki Fukunaga

Satoshi Tsuda

Akio Miyajima

A method for manufacturing a paper barrier base material includes a step of applying a water vapor barrier layer coating liquid that contains at least a water vapor barrier resin and a pigment onto a paper base material by a curtain coating method to form a water vapor barrier layer. The water vapor barrier layer coating liquid has a spinnability of 0.07 seconds or more and 0.4 seconds or less at a solid content concentration of 32% by weight and a temperature of 25° C. The method is intended to achieve good stability of a coating liquid and good continuous operability.

Method for manufacturing paper barrier base material

An object is to provide a paper barrier material resistant to fractures due to water vapor expansion when heated. As a solution, a paper barrier material is provided, which is characterized in that it comprises a gas barrier layer, a seal layer, a paper base material, and a pigment coating layer, being stacked in this order, wherein the laminate consisting only of the paper base material and pigment coating layer has an air permeation resistance of 2,500 seconds or lower as measured based on JAPAN TAPPI No. 5-2: 2000.

Paper barrier material

A method for manufacturing a paper barrier base material includes a step of applying a water vapor barrier layer coating liquid that contains at least a water vapor barrier resin and a pigment onto a paper base material by a curtain coating method to form a water vapor barrier layer, and a step of applying a gas barrier layer coating liquid that contains at least one polymer selected from water-soluble polymers and water-dispersible polymers onto the water vapor barrier layer by a curtain coating method without a drying step interposed between the two steps to form a gas barrier layer. The gas barrier layer coating liquid has a B-type viscosity equal to or higher than a B-type viscosity of the water vapor barrier layer coating liquid. The method is intended to suppress the occurrence of coating unevenness in wet-on-wet coating by a curtain coating method.

An object is to provide a paper barrier material having excellent gas barrier property as well as excellent water vapor barrier property, wherein such paper barrier material is suitable for packaging applications such as food packaging materials, containers, and cups. The means for achieving the object is to provide a paper barrier material characterized in that it meets the conditions in (1) to (3) below: (1) the water vapor permeability at 40&#xb1;0.5&#xb0; C. in temperature and 90&#xb1;2% in relative humidity is 3 g/m&#xb7;day or below; (2) the oxygen permeability at 23&#xb0; C. in temperature and 0% in relative humidity is 3 ml/m&#xb7;day&#xb7;atm or below; and (3) the oxygen permeability at 23&#xb0; C. in temperature and 85% in relative humidity is 3 ml/m&#xb7;day&#xb7;atm or below.

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Tokyo, Japan

Yuri Oishi