JP2008000897A - Laminated paper for data recording medium - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide laminated paper for a data recording medium, which is free from warpage and the deterioration of surface smoothness under a high temperature and high pressure preservation condition. <P>SOLUTION: The laminated paper for the data recording medium has a structure wherein the surface and back of thick paper, which is formed by laminating n (n=2 or above) layers thin papers, each of which has a resin layer constituted of a thermoplastic resin not melted at a room temperature but melted at 80°C under constant pressure, on its surface are held between plastic films by an adhesive layer. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention has a structure in which a thin paper having a thermoplastic resin layer on the surface is laminated in n layers (n = 2 or more), and a structure in which the front and back sides are sandwiched by plastic films with an adhesive layer, so that a high temperature, high The present invention relates to a laminated paper for information recording media characterized by suppressing warpage and surface smoothness deterioration under storage of humidity.

  In accordance with the recent increase in awareness of environmental problems including garbage problems and resource depletion problems, it is desired to convert information recording media that have been configured with plastic substrates to paper or biodegradable plastics. In particular, optical discs are attracting particular attention. When paper is used as the base of optical discs, the recording layer can be read at room temperature. There is a problem that reading is impossible.

  In general, it is known that paper is warped due to expansion or contraction due to water absorption due to expansion or contraction of fibers due to increase or decrease of moisture. As means for reducing warpage, there are examples of relaxation of warpage by application of a water-resistant resin layer (for example, Patent Document 1) and lamination including a paper layer as a decorative material for building materials (for example, Patent Document 2).

  Further, the surface smoothness decreases at high temperatures. This is thought to be due to the fact that stress during calendering remains, resulting in expansion and contraction in the thickness direction, resulting in cocoon skin and a reduction in surface smoothness.

Patent documents are as follows.
JP 2000-110097 A Japanese Patent Laid-Open No. 11-333985 Japanese Patent Application No. 2006-22056

  The problem to be solved by the present invention has a structure in which a thin paper having a thermoplastic resin layer on the surface is laminated on an n layer (n = 2 or more), and the front and back surfaces of the paper are sandwiched between plastic layers with an adhesive layer. Accordingly, it is an object of the present invention to provide a laminated paper for information recording media that suppresses warpage and surface smoothness deterioration under storage at high temperature and high humidity.

  The invention according to claim 1, which has been made to achieve the above object, is a thin paper having a thermoplastic resin layer formed on a surface of a thermoplastic resin that does not melt at room temperature but melts at a constant pressure of 80 ° C. Is a laminated paper for information recording media, characterized in that it has a structure in which cardboard laminated on n layers (n = 2 or more) is sandwiched between plastic layers with an adhesive layer.

  The invention according to claim 2 is the laminated paper for information recording medium according to claim 1, wherein the resin layer has a surface hardness of 10 [A] or more.

  Further, the invention according to claim 3 is that the resin layer is at least one side or both sides of the thin paper, and in the lamination for constituting the cardboard, the resin type and the film thickness are the same. The laminated paper for an information recording medium according to claim 1 or 2, wherein the laminated paper is for an information recording medium.

The invention according to claim 4 is the laminated paper for information recording medium according to any one of claims 1 to 3, wherein the moisture permeability of the thin paper is 210 g / m ² · 24 h or less. .

  In the invention according to claim 5, when the cardboard has at least three layers, the thin paper is laminated and laminated with a soft paper (A) having a density d1 on the inside and a hard paper (B) having a density d2 on the outside. 5. The laminated paper for information recording medium according to claim 1, wherein the density difference (D = d2−d1) is 0.1 or more.

  The invention according to claim 6 is the laminated paper for information recording medium according to any one of claims 1 to 5, wherein the thin paper is a low density paper having a density d = 0.7 or less. is there.

  The invention according to claim 7 is the laminated paper for information recording medium according to any one of claims 1 to 6, wherein the adhesive layer has the same resin type and the same film thickness on both sides. is there.

  The invention according to claim 8 is the laminated paper for information recording medium according to any one of claims 1 to 7, characterized in that the plastic film has the same film type and the same film thickness.

  According to the present invention, information recording is performed by having a structure in which a thin paper having a thermoplastic resin layer on the surface is laminated on an n layer (n = 2 or more), and the front and back sides are sandwiched between plastic layers by an adhesive layer. The laminated paper for media not only has the effect of suppressing warpage and surface smoothness deterioration under storage at high temperature and high humidity, but also the resin layer of the laminated paper for information recording media is kept at a constant pressure of 80 ° C. at room temperature. Because it is composed of a thermoplastic resin that melts in, it can be processed under mild conditions in the processing of the laminate, and therefore warpage and surface smoothness degradation under high temperature and high humidity storage due to thermal history and stress relaxation. There is an inhibitory effect.

  In addition, when the lamination of the information recording medium laminated paper is performed by hot pressing or hot roll, heat is bonded from both sides, and therefore, there is an effect of suppressing warpage under storage at high temperature and high humidity.

  Further, when the surface hardness of the resin layer of the laminated paper for information recording medium is 10 [A] or more, there is an effect of suppressing the surface smoothness deterioration under storage at high temperature and high humidity.

  Further, when the resin of the laminated paper for information recording medium has the same kind and film thickness, there is an effect of suppressing warpage and surface smoothness deterioration under storage at high temperature and high humidity.

Further, when the moisture permeability of the thin paper in the laminated paper for information recording media is 210 g / m ² · 24 h or less, there is an effect of suppressing warpage and surface smoothness deterioration under storage at high temperature and high humidity.

  Further, the thick paper in the information recording medium laminated paper is at least three layers or more, the thin paper is laminated and laminated with the soft paper (A) having the density d1 on the inside and the hard paper (B) having the density d2 on the outside, and the density difference When (D = d2-d1) is 0.1 or more, there is an effect of suppressing warpage and surface smoothness deterioration under storage at high temperature and high humidity.

  Further, when the thin paper in the information recording medium laminated paper is a low density paper having a density d = 0.7 or less, there is an effect of suppressing warpage and surface smoothness deterioration under storage at high temperature and high humidity.

  Moreover, when the adhesive layer in the laminated paper for information recording media has the same resin type and the same film thickness on both sides, there is an effect of suppressing warpage under storage at high temperature and high humidity.

  Moreover, when the plastic film in the laminated paper for information recording media has the same film type and the same film thickness, there is an effect of suppressing warpage under storage at high temperature and high humidity.

  The present invention is characterized by having a structure in which a thin paper having a thermoplastic resin layer on the surface according to the present invention is laminated with n layers (n = 2 or more) and the adhesive layer is sandwiched between the front and back by a plastic film. The laminated paper for information recording media will be described. FIG. 1 shows a configuration example.

  Since the resin layer has a front / back symmetrical structure for warping, both the front and back have the same thickness and the same composition. Also, acrylic compounds, EVA (ethylene-vinyl acetate copolymer) compounds, olefin compounds, ester compounds, ether compounds, urethane compounds, PVA compounds, thiol compounds, acetal compounds, alcohol compounds It is a thermoplastic resin composed of rubber compounds, epoxy compounds, latex and the like.

  The resin used for the resin layer may be in any form, such as an emulsion or hot melt, regardless of the presence or absence of a solvent, oiliness, or water.

  The resin layer preferably has a surface hardness of 10 [A] or more in order to prevent paper deformation due to scratches or temperature and humidity.

As a method for laminating thin paper, a hot press or a hot roll using air pressure or hydraulic pressure is used. Since the heating temperature is desirably 100 ° C. or less at which paper does not foam, the resin layer does not melt at room temperature but needs to be melted at a constant pressure of 100 ° C. or less. In addition, in order to mitigate warpage and surface smoothness deterioration of the laminated paper for information recording media, it must be melted without applying a temperature as much as possible.
It is best to melt at a constant pressure of 80 ° C. in consideration of storage and handling in other processes.

  At that time, in order to eliminate unevenness of adhesion in the width direction and the flow direction, a uniform temperature and pressure are applied to the bonded base material. Also, the mirror roll or mirror plate that performs hot pressing is sufficiently polished and has no scratches, there is no inclination in the height direction in the width direction, and there is no eccentricity in the case of a roll. desirable.

The moisture permeability of the thin paper is preferably 210 g / m ² · 24 h or less, surface roughness (centerline average roughness) Ra 0.5 μm or less, Beck smoothness 3600 s or more, and density d = 0.7 or less. .

  When the thick paper has at least three layers, the thin paper is laminated and laminated with the soft paper (A) having the density d1 on the inside and the hard paper (B) having the density d2 on the outside, and the density difference (D = d2-d1) Is preferably 0.1 or more.

  Adhesive layer is acrylic compound, EVA (ethylene-vinyl acetate copolymer) compound, olefin compound, ester compound, ether compound, urethane compound, PVA compound, thiol compound, acetal compound, alcohol It is composed of a system compound, a rubber compound, an epoxy compound, and the like.

  The adhesive used for the adhesive layer may be in any form such as emulsion, hot melt, etc., regardless of whether or not it contains a solvent, oiliness, and water.

  The adhesive layer may be formed in any form such as die coating, roll coating, gravure coating, kiss coating, blade coating, rod coating, comma coating, reverse coating, lip coating, jet coating, and air knife.

  The lamination of the plastic film may be in any form such as dry lamination, non-solation lamination, and extrusion. Moreover, about a nip, forms, such as a press plate and a roll, are not ask | required.

  The plastic film is made of polyester, polyethylene naphthalate, polycarbonate, cyclic polyolefin, polypropylene, polyethylene, nylon, or the like.

  It is preferable that the adhesive layer and the plastic film have the same type and composition, the same film thickness, and are symmetrical, and at least the same type and composition are desirable.

A thin paper having a thickness of 350 μm having an acrylic thermoplastic resin with a coating amount of 15 g / cm ^{2 on} both front and back surfaces (moisture permeability (ZIS Z0208): 170 g / m ² · 24 h, surface hardness (TAPPI
Wax pick method): 14 [A], density: 1.12 g / cm ³ ) are bonded together by a flat press machine with air pressure under the conditions of 80 ° C., 1.0 MPa, 1 minute, and the layer thickness is 700 μm. A two-layer paper was prepared. At that time, in order to alleviate the warpage, symmetry was given to the front and back of the paper. In addition, a PET film was placed between the press plate and the thin paper so that the resin was not attached to the press plate during pressing.

  The produced cardboard was coated with 50 μm of moisture-curable hot melt using a roll coater (reverse coating. Two hot rolls were applied at 120 ° C. Coating roll: diameter 8.0 cm, speed 12.0 m / Min, feeding roll: diameter 8.0 cm, speed 10.0 m / min), a polycarbonate film having a thickness of 150 μm was laminated at a pressure of 0.3 MPa. The same work was done on the back side.

  The laminated body bonded with the film is punched into a circular shape (outer diameter 120 mm, center diameter 15 mm), temperature 80 ° C., humidity 85%, temperature 80 ° C., humidity 20% in 4 days, temperature 23 ° C., humidity 50% in 1 day. Stored for 3 days.

A thin paper (thickness of water vapor: 170 g / m ² · 24 h, surface hardness: 13 [A], density: 1.12 g / cm 3) having a coating amount of 15 g / cm ² acrylic resin on both front and back surfaces ^Two thin sheets of 175 μm (moisture permeability: 210 g / m ² · 24 h, surface hardness 14 [A], density: 1.18 g / cm ³ ) were applied at 80 ° C. and 1.0 MPa for 1 minute by a flat press machine using air pressure. Three sheets were bonded together under the conditions described above to prepare a paper composed of three layers having a layer thickness of 700 μm. The structure was 175 μm / 350 μm / 175 μm in order to provide symmetry in order to alleviate warpage, and the paper was also symmetrical on the front and back sides. In addition, a PET film was placed between the press plate and the thin paper so that the resin was not attached to the press plate during pressing. In the same manner as in Example 1, the produced cardboard was laminated with a polycarbonate film on the front and back, punched out into a circular shape, and stored at a constant temperature and humidity.

Thin paper with a thickness of 175 μm having an acrylic thermoplastic resin with a coating amount of 15 g / cm ^{2 on} both sides (moisture permeability: 210 g / m ² · 24 h, surface hardness 14 [A], density: 1.18 g / cm ³ ) 4 sheets were bonded together by a flat press machine with air pressure under the conditions of 80 ° C. and 1.0 MPa for 1 minute to prepare a paper having 4 layers with a layer thickness of 700 μm. At that time, in order to alleviate the warpage, symmetry was given to the front and back of the paper. In addition, a PET film was placed between the press plate and the thin paper so that the resin was not attached to the press plate during pressing. In the same manner as in Example 1, the produced cardboard was laminated with a polycarbonate film on the front and back, punched out into a circular shape, and stored at a constant temperature and humidity.

  Thin paper with a thickness of 350μm with thermoplastic resin on both sides (surface hardness: 10 [A]) 2 layers are bonded together using a flat press machine with air pressure at 80 ° C, 1.0 MPa for 1 minute. A two-layer paper having a thickness of 700 μm was produced, and in order to provide a symmetry to reduce warpage, the paper was provided with symmetry on the front and back sides. A PET film was placed between the press plate and thin paper.

  The produced cardboard was coated with 50 μm of moisture-curable hot melt using a roll coater (reverse coating. Two hot rolls were coated at 120 ° C. Coating roll: diameter 8.0 cm, speed 8.0 m / Min, feed roll: diameter 8.0 cm, speed 3.8 m / min), a polycarbonate film having a thickness of 150 μm was laminated at a pressure of 0.3 MPa. The same work was done on the back side. In the same manner as in Example 1, the produced cardboard was punched into a circular shape and stored at a constant temperature and humidity.

Paper (Density: 0.95g / cm ³⁾ having a thickness of 350μm with a thermoplastic resin on both surfaces and a thickness of 175μm thin paper (density: 1.05g / cm ³⁾ 80 ℃ two by a flat press by air pressure, Three sheets of paper having a layer thickness of 700 μm were prepared by laminating three sheets at 1.0 MPa for 1 minute. In order to provide a symmetry for warping relaxation, the configuration was set to 175 μm / 350 μm / 175 μm, and the paper was symmetrical on both sides. In addition, a PET film was placed between the press plate and the thin paper so that the resin was not attached to the press plate during pressing. In the same manner as in Example 1, the produced cardboard was laminated with a polycarbonate film on the front and back, punched out into a circular shape, and stored at a constant temperature and humidity.

Two sheets of 350μm thick paper (density: 0.6g / cm ³ ) with 20μm thick PE on both sides were bonded together at 100 ° C, 1.0MPa for 5 minutes using a flat press machine with air pressure. A two-layer paper having a layer thickness of 700 μm was prepared. In order to provide warping relief, symmetry was given to the front and back of the paper. In addition, a PET film was placed between the press plate and the thin paper so that the resin was not attached to the press plate during pressing. In the same manner as in Example 1, the produced cardboard was laminated with a polycarbonate film on the front and back, punched out into a circular shape, and stored at a constant temperature and humidity.

(Comparative Example 1)
A 700 μm-thick thin paper having an acrylic thermoplastic resin with a coating amount of 15 g / cm ^{2 on} both front and back surfaces (moisture permeability: 180 g / m ² · 24 h, surface hardness: 13 [A], density: 1.02 g / cm ³ In the same manner as in Example 1, the produced cardboard was laminated with a polycarbonate film on the front and back, punched out into a circular shape, and stored at constant temperature and humidity.

(Comparative Example 2)
700 μm-thick thin paper having acrylic thermoplastic resin with a coating amount of 15 g / cm ^{2 on} both front and back surfaces (moisture permeability: 180 g / m ² · 24 h, surface hardness: 13 [A], density: 1.02 g / c
m ³ ) was pressed under conditions of 80 ° C., 1.0 MPa, and 1 minute by a flat press machine using air pressure. During pressing, a PET film was placed between the press plate and thin paper so that the resin did not adhere to the press plate. In the same manner as in Example 1, the produced cardboard was laminated with a polycarbonate film on the front and back, punched out into a circular shape, and stored at a constant temperature and humidity.

(Comparative Example 3)
Two layers with a thickness of 700 μm by bonding two sheets of thin paper with a thickness of 350 μm with acrylic resin of 20 μm thickness on both sides using a flat press machine with air pressure at 120 ° C. and 1.0 MPa for 1 minute. Attempts were made to make a paper consisting of the following: foaming due to evaporation of water inside the paper, and peeling between the papers.

(Comparative Example 4)
Thin paper with a thickness of 350μm with thermoplastic resin on both sides (surface hardness: 8 [A]) 2 layers are bonded together using a flat press machine with air pressure at 80 ° C, 1.0 MPa for 1 minute A two-layer paper having a thickness of 700 μm was produced, and in order to provide a symmetry to reduce warpage, the paper was provided with symmetry on the front and back sides. A PET film was placed between the press plate and thin paper, and the produced cardboard was laminated with a polycarbonate film on the front and back, punched out into a circular shape, and stored at constant temperature and humidity.

(Comparative Example 5)
Two sheets of 350μm thick paper with PE of 20μm thickness on one side and 350μm thick paper with no PE on both front and back sides are attached by air flat press at 100 ° C, 1.0MPa for 5 minutes. In addition, a two-layer paper having a layer thickness of 700 μm was produced. In order to provide warping relief, symmetry was given to the front and back of the paper. In addition, a PET film was placed between the press plate and the thin paper so that the resin was not attached to the press plate during pressing. In the same manner as in Example 1, the produced cardboard was laminated with a polycarbonate film on the front and back, punched out into a circular shape, and stored at a constant temperature and humidity.

(Comparative Example 6)
A thin paper (moisture permeability: 820 g / m ² · 24 h) having an acrylic thermoplastic resin with a coating amount of 15 g / cm ^{2 on} both the front and back sides is applied at 80 ° C. and 1.0 MPa for 1 minute by a flat press machine using air pressure. Two sheets were bonded together under the conditions described above to produce a two-layer paper having a layer thickness of 700 μm. At that time, in order to alleviate the warpage, symmetry was given to the front and back of the paper. In addition, a PET film was placed between the press plate and the thin paper so that the resin was not attached to the press plate during pressing. In the same manner as in Example 1, the produced cardboard was laminated with a polycarbonate film on the front and back, punched out into a circular shape, and stored at a constant temperature and humidity.

(Comparative Example 7)
Two sheets of 350 μm thick paper (density: 0.8 g / cm ³ ) with 20 μm thick PE on both sides were bonded together at 100 ° C. and 1.0 MPa for 5 minutes using a flat press machine with air pressure. A two-layer paper having a layer thickness of 700 μm was prepared. In order to provide warping relief, symmetry was given to the front and back of the paper. In addition, a PET film was placed between the press plate and the thin paper so that the resin was not attached to the press plate during pressing. In the same manner as in Example 1, the produced cardboard was laminated with a polycarbonate film on the front and back, punched out into a circular shape, and stored at a constant temperature and humidity.

(Comparative Example 8)
Similar to Example 1, cardboard was prepared by laminating two thin sheets. The produced cardboard was coated with 50 μm of moisture-curable hot melt using a roll coater (reverse coating. Two hot rolls were applied at 120 ° C. Coating roll: diameter 8.0 cm, speed 12.0 m / Min, feeding roll: diameter 8.0 cm, speed 10.0 m / min), a polycarbonate film having a thickness of 150 μm was laminated at a pressure of 0.3 MPa. Subsequently, a moisture-curable hot melt was applied to the back surface under the same mechanical conditions at 80 μm, and a polycarbonate film having a thickness of 150 μm was bonded under the same conditions. Further, in the same manner as in Example 1, it was punched into a circular shape and stored at a constant temperature and humidity.

(Comparative Example 9)
Similar to Example 1, cardboard was prepared by laminating two thin sheets. The produced cardboard was coated with 50 μm of moisture-curable hot melt using a roll coater (reverse coating. Two hot rolls were applied at 120 ° C. Coating roll: diameter 8.0 cm, speed 12.0 m / Min, feeding roll: diameter 8.0 cm, speed 10.0 m / min), a polycarbonate film having a thickness of 150 μm was laminated at a pressure of 0.3 MPa. Subsequently, a moisture-curable hot melt was similarly applied to the back surface, and a polycarbonate film having a thickness of 100 μm was bonded under the same conditions. Further, in the same manner as in Example 1, it was punched into a circular shape and stored at a constant temperature and humidity.

  Table 1 shows the warpage and surface properties after storage at constant temperature and humidity. The warpage was calculated by the maximum height-minimum height in the sample. About the surface property, the value of the surface waviness was measured at a wavelength of Wd3-10 mm using a WAVE SCAN measuring instrument manufactured by Gardner (the smaller the value, the smoother).

  The laminated paper for information recording media according to the present invention is suitable as a base for optical disks and IC cards for applications that need not be deformed even under high temperature and high room temperature. It is expected to be an alternative to the current plastic because of the improved environmental aspects through the use of paper.

It is a conceptual sectional view showing the case of n = 2 of the present invention. It is a conceptual sectional view showing the case of n = 4 of the present invention.

Explanation of symbols

1. 1. Plastic film 2. Adhesive layer 3. Thermoplastic resin Thin paper

Claims (8)

  Adhesive layer is a cardboard that is laminated with n layers (n = 2 or more) of thin paper having a thermoplastic resin layer composed of a thermoplastic resin that does not melt at room temperature and melts at a constant pressure of 80 ° C. A laminated paper for information recording media, characterized by having a structure in which the front and back are sandwiched between plastic films.   The laminated paper for information recording media according to claim 1, wherein the resin layer has a surface hardness of 10 [A] or more.   3. The resin layer according to claim 1 or 2, wherein the resin layer is at least on one side or both sides of the thin paper, and in the lamination for constituting the cardboard, the resin type and the film thickness are the same. Laminated paper for information recording media. The laminated paper for information recording media according to any one of claims 1 to 3, wherein the moisture permeability of the thin paper is 210 g / m ² · 24 h or less.   When the thick paper has at least three layers, the thin paper is laminated and laminated with the soft paper (A) having the density d1 on the inside and the hard paper (B) having the density d2 on the outside, and the density difference (D = d2−d1). ) Is 0.1 or more, the laminated paper for information recording media according to any one of claims 1 to 4.   6. The laminated paper for information recording medium according to claim 1, wherein the thin paper is a low-density paper having a density d = 0.7 or less.   The laminated paper for an information recording medium according to any one of claims 1 to 6, wherein the adhesive layer has the same resin type and the same film thickness on both sides.   The laminated paper for an information recording medium according to any one of claims 1 to 7, wherein the plastic film has the same film type and the same film thickness.