JPH04344284A - Printing sheet - Google Patents

Abstract

PURPOSE:To provide a printing sheet having high printing properties. CONSTITUTION:The subject printing sheet consists of an undercoat layer formed on the surface of an unwoven cloth constituted by laminating continuous filaments and farther a coated layer formed on the undercoat layer. This unwoven cloth has spot deposition areas arranged at a epedified interval. The area of a single spot deposition area is 0.16mm<2> or lees. The total sum of all the spot deposition areas is equivalent to 2 to 40% of the surface area of unwoven cloth. The undercoat layer is formed by applying a foamed paint to the surface of the unwoven cloth. In addition, the coated layer is composed of white pigment and an adhesive. This printing sheet can be used suitably as special material for wrapping, bag and poster.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a printing sheet having excellent printability, and particularly to a printing sheet that can be suitably used as a material for packaging materials, bags, posters, etc.

0002

2. Description of the Related Art In recent years, so-called spunbond nonwoven fabrics have been widely used as materials for packaging materials, bags, etc. The reason for this is that spunbond nonwoven fabric is a sheet of continuous filaments, so it has tear resistance, burst resistance,
This is because it has excellent water resistance and tensile strength.

[0003] Spunbond nonwoven fabrics, which are generally used as materials for packaging materials, are made by accumulating continuous filaments into a sheet, and then bonding the continuous filaments together by intermittent thermocompression bonding with a textured roll. It has a large number of point fusion areas that caused self-fusion. Further, there are other areas where the continuous filaments are not bonded by heat and pressure and where the continuous filaments are not self-fused. This point fused area fixes the continuous filament and
And in other areas, bundles of continuous filaments are present, giving the spunbond nonwoven fabric good physical properties such as high tensile strength and tear resistance.

[0004] However, the thickness is different between the point welding area and the other areas, and relatively deep unevenness exists on the surface of the spunbond nonwoven fabric. In other words, in the point-fused area, the continuous filaments melt and soften and stick together to form a film, so the thickness is thin; in other areas, the continuous filaments remain in their original form, so the thickness is thick. It is. Therefore, when printing is applied to the surface of this spunbond nonwoven fabric, the printing ink is not applied uniformly between the point-fused area and other areas, making it difficult to perform beautiful printing. That is, white spots may occur in the point fused area, or uneven printing density may occur between the point fused area and other areas.

[0005] For this reason, attempts have been made to apply various coating liquids to the surface of spunbond nonwoven fabric to form a coating layer and to equalize the coverage of printing ink in the point fusion area and other areas. (Japanese Patent Application Laid-Open No. 61-41372 and Japanese Patent Publication No. 58-51551). However, it has been difficult to make the printing ink uniform by simply applying a coating liquid. The reason for this is thought to be as follows. In other words, the point-fused area of the spunbond nonwoven fabric is a film, and the other areas are fiber aggregates, and this is thought to be because the coating liquid itself is not applied uniformly because the surface conditions are different. . This was particularly noticeable in conventional spunbond nonwoven fabrics because the area of the point fusion area was relatively large.

[0006]

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to reduce the area of one point welding area formed in a spunbond nonwoven fabric as much as possible, and to remove foamed paint before applying a coating solution. By applying this, the surface condition of the point fusion area and other areas will be homogenized, and the coating liquid will be applied evenly, thereby making the printing ink evenly applied and improving printability. That is.

[0007]

[Means for Solving the Problems] That is, in the present invention, an undercoat layer is provided on the surface of a nonwoven fabric composed of a large number of continuous filaments, and a coating layer is further provided on the surface of the undercoat layer. a printing sheet comprising: a nonwoven fabric having a plurality of spaced apart dot-fused areas;
The area of one point fused area is 0.16 mm2 or less, the total area of all point fused areas is 2 to 40% of the surface area of the nonwoven fabric, and the undercoat layer transfers the foamed paint to the nonwoven fabric. The present invention relates to a printing sheet which is formed by coating the surface of the printing sheet, wherein the coating layer further comprises a white pigment and an adhesive.

[0008] The printing sheet according to the present invention comprises a nonwoven fabric,
It consists of an undercoat layer provided on the surface of this nonwoven fabric and a coating layer provided on the surface of this undercoat layer. Non-woven fabric is
It is constructed by integrating a large number of continuous filaments, and the aforementioned spunbond nonwoven fabric is a typical example. The spunbond nonwoven fabric is formed by a spunbond method, and the spunbond method is a method in which continuous filaments obtained by spinning a polymer stock solution and then drawing it are directly assembled. The continuous filaments constituting the nonwoven fabric obtained by this method are drawn, and the nonwoven fabric exhibits excellent tear resistance, burst resistance, and tensile strength.

[0009] The nonwoven fabric has a number of spaced point weld areas formed therein. In this point-fused area, the continuous filaments constituting the nonwoven fabric are softened or melted, and the continuous filaments are bonded to each other. The area of this one point fusion area is 0.
It is 16 mm2 or less. The area of one point fusion area is 0.
If it exceeds 16 mm2, it is not preferable because not only will the point fusion area not be sufficiently hidden by the paint, but it will also become difficult to apply the paint uniformly. Further, the total area of the point fusion areas, that is, the sum of the areas of the individual point fusion areas, is 2 to 40% of the surface area of the nonwoven fabric. Here, the surface area of the nonwoven fabric means the area of one side of the nonwoven fabric, and does not mean the area of both sides of the nonwoven fabric (that is, the sum of the areas of each single side). If the total area of the point-fused areas is less than 2%, it is not preferable because it becomes difficult to impart sufficient strength to the nonwoven fabric. Also,
If the total area of the point fused area exceeds 40%, the nonwoven fabric will have many filmed areas, and the flexibility of the nonwoven fabric will decrease.
This is not preferable because it becomes difficult to use as a material for packaging materials, etc.

[0010] Examples of methods for producing the above-mentioned nonwoven fabric include the following methods. first,
A thermoplastic resin such as polyethylene, polypropylene, polyester, polyacrylate, polyamide, etc. is prepared and melt-spun to obtain a large number of continuous filaments. This continuous filament group is pulled by an air sucker,
Stretching and transporting the continuous filament group. Then, the continuous filament group discharged from the air sucker is accumulated on a moving conveyor to obtain a nonwoven web. This nonwoven web is introduced between a heated embossing roll and a smooth roll. Then, the nonwoven web is intermittently heated and pressed (ie, thermocompression bonded) using a large number of convex portions provided on the embossing roll to provide point-fused areas and obtain the above-mentioned nonwoven fabric.

The continuous filaments constituting the nonwoven fabric may be commonly used filaments made of a single component, or composite filaments made of multiple components (in most cases, two components). As a complex type,
A side-by-side type or a core-sheath type is used. When composite filaments are used, the composite filaments may be bonded together by melting or softening only one component constituting the filaments when providing point-fused areas. Further, the thickness, basis weight, etc. of the nonwoven fabric may be appropriately determined as desired. In particular, the basis weight of nonwoven fabric is 20 to 150 g/
m2, preferably 30 to 100 g/m2. If the basis weight of the nonwoven fabric is less than 20 g/m2, there will be a tendency for transparency to increase and printability to decrease, and also for it to be too thin and difficult to handle. On the other hand, if the basis weight of the nonwoven fabric exceeds 150 g/m2, flexibility tends to decrease and packaging properties tend to decrease.

[0012] An undercoat layer is provided on the surface of this nonwoven fabric. The undercoat layer may be provided on one side or both sides of the nonwoven fabric. The undercoat layer is
It is formed by applying foamed paint to the surface of a nonwoven fabric. The paint contains an adhesive. As the adhesive, conventionally known adhesives may be used; specifically, polyacrylic ester, polymethacrylic ester, ethylene-vinyl acetate copolymer, styrene-butadiene copolymer, nitrile-butadiene copolymer. material, polyester resin, polyurethane, etc. are used. Copolymers of the above-mentioned materials may also be used in the same manner. Furthermore, starch, starch derivatives, polyvinyl alcohol, casein, carboxymethyl cellulose, etc. are also used. These adhesives may be present in the paint in the form of an emulsion, or may be present in a state dissolved in a solvent in the paint.

[0013] Furthermore, if necessary, a white pigment may be incorporated into the paint. Incorporation of a white pigment improves the opacity of the resulting sheet and further improves its printability. White pigments that can be used include calcium carbonate, magnesium carbonate, magnesium hydroxide, aluminum hydroxide, zinc hydroxide, zinc oxide, titanium dioxide, aluminum oxide, silicon dioxide, amorphous silica, barium sulfate, kaolinite, talc, etc. Inorganic pigments or organic pigments such as styrene and acrylic esters are used. When using or adding white pigment to the paint, the solid content of the adhesive should be 1
It is preferable to add about 40 parts by weight or less based on the weight part. When the amount of white pigment exceeds 40 parts by weight, the amount of adhesive becomes relatively small, the adhesion between the undercoat layer and the nonwoven fabric decreases, and the undercoat layer tends to fall off easily. Furthermore, auxiliary agents such as lubricants, antioxidants, ultraviolet absorbers, colored pigments, antistatic agents, and thickeners may be contained as necessary.

[0014] In the present invention, the above-mentioned coating material is applied to a nonwoven fabric in a foamed state. To foam the paint,
A conventionally known foaming machine may be used. For example, a continuous foaming machine, a shaking mixer, a cake mixer, etc. manufactured by Stork in the Netherlands may be used. The foaming ratio of the paint is preferably at least 2 times or more. If the expansion ratio is less than 2 times, the application tends to be uneven in the point-fused area (filmed area) and other areas (area composed of fiber aggregates) of the nonwoven fabric. The viscosity of the paint after foaming is 4000c.
It is preferable that it is p or more. This viscosity was measured using a BM type viscometer. If the viscosity of the paint is less than 4000 cp, the paint will easily penetrate into the nonwoven fabric, and the paint will tend to ooze out onto the back side of the nonwoven fabric. In order to improve the stability of the foamed state, it is preferable to add a foaming stabilizer (hereinafter referred to as "foam control agent") prior to the foaming treatment. As the foam control agent, higher fatty acids, modified higher fatty acids, alkali salts of higher fatty acids, etc. can be used. The amount of foam control agent added is based on 100 parts by weight of solid content in the paint.
It is appropriate to add about 30 parts by weight or less, preferably about 10 parts by weight or less. If the amount of the foam control agent exceeds 30 parts by weight, the stability of the coating material tends to decrease.

Any conventionally known means can be used to apply the paint to the nonwoven fabric. Specifically, coating means such as a Meyer bar, air knife, blade, slit die, comma coater, roll coater, lip coater, etc. can be employed, and furthermore, gravure,
It can also be applied by printing means such as a screen. The coating amount of the paint is 1 to 50 g/m2 in terms of solid content, preferably 2
~30g/m2 is appropriate. Coating amount is 1g/m2
When the amount is less than that, the undercoat layer becomes incomplete, and the surface condition between the point-fused area and other areas tends not to be homogenized, and there also tends to be some uncoated areas. Furthermore, if the coating amount exceeds 50 g/m2, the flexibility of the printing sheet decreases, making it unsuitable for use as a packaging material or the like. After applying the paint, dry it and apply pressure if necessary. Note that pressurization is preferably carried out using a calender machine such as a super calender or a machine calender.

A coating layer is provided on the surface of the undercoat layer. The coating layer is composed of a white pigment and an adhesive. As the white pigment, various kinds of pigments can be used, which are added to the paint as necessary when forming the undercoat layer. It is also used as an adhesive when forming the undercoat layer.
Various types can be used. The appropriate blending ratio of the white pigment is about 1 to 40 parts by weight, preferably about 2 to 20 parts by weight, per 1 part by weight of the adhesive (solid content). If the blending ratio of the white pigment is less than 1 part by weight, printability cannot be sufficiently improved, and in particular, offset printability tends to deteriorate. Moreover, when the blending ratio of the white pigment exceeds 40 parts by weight, the amount of adhesive becomes relatively small, the adhesion between the coating layer and the undercoat layer decreases, and the coating layer tends to fall off. Further, the amount of this coating layer is 3 to 50 g/m2, preferably 5 to 3 g/m2.
Approximately 0 g/m2 is appropriate. The amount of coating layer is 3g/m2
If it is less than that, there is a tendency that the printability cannot be sufficiently improved. On the other hand, if the amount of the coating layer exceeds 50 g/m2, the flexibility of the printing sheet decreases, making it unsuitable for use as a packaging material or the like.

The coating layer is formed by applying a coating liquid containing a white pigment and an adhesive. This coating liquid is applied to the surface of the undercoat layer either as it is without foaming or after foaming. In addition to the white pigment and adhesive, this coating solution also contains the ingredients used when forming the undercoat layer.
Various auxiliary agents and the like may be included. As a means for applying the coating liquid to the surface of the undercoat layer, various coating means used when applying the undercoat layer can be employed. The printing sheet according to the present invention can be obtained by applying the coating liquid to the surface of the undercoat layer, drying it, and applying pressure if necessary.

[0018]

【Example】

Example 1 A spunbond nonwoven fabric was prepared in which polyester continuous filaments were accumulated and had point-fused areas where the polyester continuous filaments were fixed by softening or melting the polyester continuous filaments. The area of one point fused area was 0.13 mm2, and the total area of each point fused area was 8% of the surface area of the nonwoven fabric. Note that the area of the point fusion area was measured using a scanning electron micrograph magnified 100 times. Also,
The basis weight of this spunbond nonwoven fabric was 60 g/m2. Next, 100 parts by weight of styrene-butadiene copolymer latex (manufactured by Japan Synthetic Rubber Co., Ltd., product number 0619, solid content concentration 48% by weight) was added to a foam regulating agent (manufactured by Dainippon Ink & Chemicals Co., Ltd., product number F- 1. Solid content concentration 33% by weight
) A paint containing 3 parts by weight was prepared. This paint was foamed using a hand mixer. The foaming ratio is 6 times,
The viscosity after foaming was 20,000 cp (measured with a BM viscometer). The paint foamed as described above was applied to the surface of the spunbond nonwoven fabric using a Meyer bar. Thereafter, it was dried to form an undercoat layer. Note that this undercoat layer had a weight of 15 g/m2. Next, styrene
Aqueous oxidized starch solution (manufactured by Oji Cornstarch Co., Ltd., trade name Oji Ace A, solid content concentration 10 parts by weight) was added to 10 parts by weight of butadiene copolymer latex (manufactured by Nippon Gosei Rubber Co., Ltd., product number 0619, solid content concentration 48% by weight). %) 5 parts by weight, and a kaolin clay dispersion (manufactured by J.M. Huber, trade name Hydragross, solid content concentration 50% by weight)
) 85 parts by weight and a calcium carbonate dispersion (manufactured by Nitto Funka,
A coating liquid containing 8 parts by weight of product number NS800 (solid content concentration 60% by weight) was prepared. Then, this coating solution was applied to the surface of the undercoat layer without foaming using a Mayer bar. Thereafter, it was dried and subjected to pressure treatment using a super calendar machine to form a coating layer, thereby obtaining a printing sheet. Note that this coating layer had a weight of 20 g/m2.

Example 2 A spunbond nonwoven fabric was prepared, which was made up of accumulated polyester continuous filaments and had point-fused areas where the polyester continuous filaments were fixed by softening or melting the polyester continuous filaments. The area of one point fused area was 0.10 mm2, and the total area of each point fused area was 8% of the surface area of the nonwoven fabric. In addition, the basis weight of this spunbond nonwoven fabric is 60
g/m2. Next, styrene-butadiene copolymer latex (manufactured by Japan Synthetic Rubber Co., Ltd., product number 061
9. After adding 20 parts by weight of titanium dioxide to 100 parts by weight (solid content concentration 48% by weight), foam regulator (manufactured by Dainippon Ink & Chemicals Co., Ltd., product number F-1, solid content concentration 33% by weight) 5
A paint was prepared in which parts by weight were added. This paint was foamed using a hand mixer. The foaming ratio was 6 times, and the viscosity after foaming was 22,000 cp (measured using a BM viscometer). The paint foamed as described above was applied to the surface of the spunbond nonwoven fabric using a Meyer bar. Thereafter, it was dried to form an undercoat layer. Note that this coating layer had a weight of 35 g/m2. Finally, a coating layer was formed in the same manner as in Example 1 using the coating liquid used in Example 1 to obtain a printing sheet.

Example 3 After adding 40 parts by weight of calcium carbonate (manufactured by Shiraishi Kogyo Co., Ltd., product number Brilliant 15) to 100 parts by weight of an acrylic emulsion (manufactured by Japan Synthetic Rubber Co., Ltd., product number AE513A, solid content concentration 40% by weight). A paint was prepared in which 10 parts by weight of a foam control agent (manufactured by Dainippon Ink & Chemicals Co., Ltd., product number F-1, solid content concentration 33% by weight) was added. This paint was foamed using a hand mixer. The foaming ratio was 7 times, and the viscosity after foaming was 28,000 cp (measured using a BM viscometer). The paint foamed as above is
It was applied to the surface of the spunbond nonwoven fabric prepared in Example 1 using a Mayer bar. Thereafter, it was dried to form an undercoat layer. This undercoat layer had a weight of 8 g/m2. Finally, using the coating liquid used in Example 1, Example 1
A coating layer was formed in the same manner as above to obtain a printing sheet.

Comparative Example 1 A printing sheet was obtained in the same manner as in Example 1, except that a spunbond nonwoven fabric in which the area of each point-fused area was 0.30 mm 2 was used.

Comparative Example 2 A printing sheet was obtained in the same manner as in Example 2, except that a spunbond nonwoven fabric in which the area of each point-fused area was 0.30 mm 2 was used, and the paint was not foamed.

Comparative Example 3 A printing sheet was obtained in the same manner as in Example 3, except that no coating layer was provided.

The printed sheets obtained in Examples 1 to 3 and Comparative Examples 1 to 3 were subjected to the following tests to evaluate their quality. The results are shown in Table 1. As is clear from Table 1, it can be seen that the printing sheets according to the examples have better printability than the printing sheets according to the comparative examples.

[Table 1] (1) Concealability of point fusion areas: The extent to which the point fusion areas on the surface of the nonwoven fabric were hidden by the undercoat layer and coating layer was visually evaluated on the following five scales. . 5...Extremely good hiding ability, 4...Good hiding ability, 3...
Concealability is normal, 2... Concealability is somewhat poor, 1
... Concealability is poor. (2) Printing blank spots and uneven printing density: Tested using a RI-II type printing tester (manufactured by Mei Seisakusho). The degree of white spots and density unevenness was visually evaluated in the following five grades. 5...Very little white spots and density unevenness, 4...Little white spots and density unevenness, 3...Some white spots and density unevenness, 2...Many white spots and density unevenness, 1...White spots and density unevenness Extremely common. (3) Offset printing suitability: Tested using a RI-II type printing tester (manufactured by Mei Seisakusho). Offset printability was visually evaluated on the following five scales. 5...Excellent offset printability, 4...Excellent offset printability, 3...Good offset printability, 2
...Offset printability is slightly poor; 1...Offset printability is poor. (4) Smoothness: Measured according to the method specified in JIS P-8119.

[0025]

[Operations and Effects of the Invention] As explained above, the printing sheet according to the present invention has an undercoat layer provided on the surface of a nonwoven fabric, and a coating layer further provided on the surface of the undercoat layer. The area of the point-fused area formed on the nonwoven fabric is less than a certain size, and a foamed paint is applied to the nonwoven fabric to provide an undercoat layer. Therefore, the combination of the fact that the foam-like paint is applied to the surface of the nonwoven fabric and the small area of the point welding area,
This paint is stably applied in approximately the same amount both in the point-fused area and in other areas, even though the surface conditions are different. Then, the surface of the nonwoven fabric is homogenized by the undercoat layer, and the coating liquid is applied to the homogenized surface. Therefore, the coating layer will be formed uniformly. For example, if the paint is not foamy or if the area of the point fusion area is larger than a certain size, the paint will flow easily and the amount of application will be uneven between the point fusion area and other areas. , the surface of the nonwoven fabric is not homogenized. Therefore, even if the coating liquid is applied to the surface of the undercoat layer,
The coating layer will not be formed uniformly. Therefore, in the printing sheet according to the present invention, the coating layer is uniformly formed, and when printing, white spots may occur in the point fusion area, or printing may occur in the point fusion area and other areas. This has the effect of preventing uneven density from occurring. In addition, since the printing sheet according to the present invention is made of a nonwoven fabric made of continuous filaments, it has excellent tear resistance and high tensile strength, and can be used as a material for packaging materials, bags, posters, etc. It can also be suitably used as

Claims (1)

[Claims] Claim 1: An undercoat layer is provided on the surface of a nonwoven fabric made up of a large number of continuous filaments,
Furthermore, a printing sheet is provided with a coating layer on the surface of the undercoat layer, the nonwoven fabric having a large number of point fused areas arranged at intervals, and the area of one point fused area is 0.
16 mm2 or less, the total area of all point fused areas is 2 to 40% of the surface area of the nonwoven fabric, and the undercoat layer is formed by applying foamed paint to the surface of the nonwoven fabric. . A printing sheet, further comprising a white pigment and an adhesive.