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Timestamp: 2017-10-19 00:12:25
Document Index: 699902669

Matched Legal Cases: ['art 90', 'art 90', 'art 90', 'art 90', 'art 90', 'art 90']

Synthetic paper for writing and printing - Oji Yuka Goseishi Co., Ltd.
United States Patent 5233924
Pencil writable and printable synthetic paper comprising a finely porous polyolefin film layer having an opacity of at least 80% obtained by stretching a polyolefin film containing from 8 to 65% by weight of an inorganic fine powder having on one or both sides thereof a stretched ethylene-vinyl alcohol copolymer film layer, at least one of the stretched ethylene-vinyl alcohol copolymer film layers having a coat layer thereon. When printed, the stretched ethylene-vinyl alcohol copolymer film layer prevents hydrocarbon solvents present in printing inks from penetrating into the polyolefin film layer to eliminate local surface unevenness and curling.
Ohba, Yozo (Ibaraki, JP)
Akimoto, Akira (Ibaraki, JP)
Chiba, Tokumi (Ibaraki, JP)
07/841540
Oji Yuka Goseishi Co., Ltd. (Tokyo, JP)
101/491, 428/315.5, 428/315.7, 428/315.9, 428/317.9, 428/516
B29C55/02; B32B5/18; B32B7/02; B32B27/00; B32B27/28; B32B27/32; B41M5/00; C08J7/04; C08J9/00; C09D11/02; B29K23/00; B29L7/00; (IPC1-7): B32B3/26; B41F31/00
101/483, 101/491, 428/315.5, 428/315.7, 428/315.9, 428/317.9, 428/516, 428/910
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4927695 Microporous marking structures 1990-05-22 Ooms et al. 428/315.9
4582753 Polymer laminate possessing an intermediate water vapor transmission barrier layer 1986-04-15 Duncan 428/317.9
4318950 Synthetic papers and method of making the same 1982-03-09 Takashi et al. 428/143
GB2161723A 1986-01-22
1. A synthetic paper comprising
(a) a finely porous polyolefin film layer having an opacity of at least 80% obtained by stretching a polyolefin film containing from 8 to 65% by weight of an inorganic fine powder;
(b) a stretched ethylene-vinyl alcohol copolymer film layer on one or both sides of the polyolefin film layer (a); and
2. The synthetic paper as claimed in claim 1, wherein said ethylene-vinyl alcohol copolymer has an ethylene content of from 30 to 70% by weight and a degree of saponification of at least 90%.
This invention relates to a synthetic paper with excellent pencil writability and printability. More particularly, it relates to a synthetic paper which has sufficient opaqueness for writing with a pencil and which, when printed by offset printing or gravure printing and piled one on another, does not become uneven or curl due to penetration of solvents of printing inks.
A synthetic paper obtained by stretching a polypropylene film containing from 8 to 65% by weight of an inorganic fine powder has recently been developed and is in practical use as disclosed in JP-B-46-40794 (corresponding to U.S. Pat. Nos. 4,318,950 and 4,075,050), JP-A-56-141339 and JP-A-57-181829 (the term "JP-B" as used herein means an "examined published Japanese patent application", and the term "JP-A" as used herein means an "unexamined published Japanese patent application").
Offset Ink for Non-absorbing GP Offset Ink Materials Component (parts by weight) (parts by weight)
Pigment 15 to 50 (20)
Resin 25 to 30 (30)
Drying oil 10 to 15 (10)
20 to 45 (35)
Dryer 0.5 to 2 (1) (2)
Others 2 to 5 (4) (4)
An object of the present invention is to provide synthetic paper where unevenness or overall curling when offset printed in multicolor even with a GP offset ink hardly occurs and which also has excellent pencil writability.
FIGS. 1 and 2 each illustrate an enlarged cross section of the synthetic paper according to the present invention.
The synthetic paper having excellent printability according to the present invention may have a five-, six-, seven-, eight-, nine-, ten- or even more multi-layered structure and includes a laminate film as shown in FIG. 1 comprising base layer 1 comprising a finely porous polyolefin film having an opacity of at least 80% which is obtained by stretching a polyolefin film containing from 8 to 65% by weight of an inorganic fine powder, stretched ethylene-vinyl alcohol copolymer film 3 laminated on one or both sides of base layer 1 via an adhesive or by fusion bonding, and coat layer 4 laminated on at least one of the stretched ethylene-vinyl alcohol copolymer films; a laminate film as shown in FIG. 2 comprising a composite film support which comprises base layer 1 comprising a biaxially stretched thermoplastic resin film containing from 3 to 40% by weight of an inorganic fine powder having laminated on one or both sides thereof paper-like surface layer 2a and/or a paper-like back layer 2b comprising a uniaxially stretched polyolefin resin film containing from 8 to 65% by weight of an inorganic fine powder, uniaxially stretched ethylene-vinyl alcohol copolymer surface layer 3a or layers 3a and 3b laminated on paper-like layer 2a or both of paper-like layers 2a and 2b via adhesive resin layer 3a' or layers 3a' and 3b', and coat layer 4a or layers 4a and 4b laminated on at least one of stretched ethylene-vinyl alcohol copolymer films 3 a and 3b; a laminate film of FIG. 2 additionally having another resin layer 5 between paper-like layer 2a or 2b and base layer 1; and a laminate film of FIG. 1 or 2 additionally having another resin layer 6 between the stretched ethylene-vinyl alcohol copolymer film and the coat layer.
The coating composition can be coated using any known coating method. After the coated polyolefin film is dried at the temperature of 70° to 120° C., the above-described coat layer is formed on at least one side thereof.
A polyolefin composition comprising from 35 to 92% by weight of a polyolefin and from 8 to 65% by weight of an inorganic fine powder and an ethylene-vinyl alcohol copolymer are separately melt-kneaded in each extruder, supplied to the same extrusion die, and co-extruded into a two layer laminate film, and the extruded laminate film is stretched in both longitudinal and transverse directions at temperatures lower than the melting point of the polyolefin.
A polyolefin composition comprising a polyolefin and from 8 to 65% by weight of an inorganic fine powder and an ethylene-vinyl alcohol copolymer are separately melt-kneaded in each extruder, supplied to the same extrusion die, and co-extruded together and laminated with a uniaxially oriented film (base layer) obtained by unidirectionally stretching a thermoplastic resin film containing from 3 to 40% by weight of an inorganic fine powder at a stretching temperature lower than the melting point of the thermoplastic resin, to obtain a fusion-laminated film composed of the uniaxially oriented thermoplastic resin film having laminated on one or both sides thereof the polyolefin film and the ethylene-vinyl alcohol copolymer film in this order. The resulting laminate film is then stretched in the direction perpendicular to the stretching direction of the unidirectionally oriented thermoplastic resin film at a temperature lower than the melting point of the polyolefin. A laminate base film in which the paper-like layer(s) are uniaxially oriented and have a number of microvoids, the ethylene-vinyl alcohol copolymer layer is uniaxially oriented, and the base layer is biaxially oriented is obtained.
A polyolefin composition comprising a polyolefin and from 8 to 65% by weight of an inorganic fine powder, an adhesive resin, and an ethylene-vinyl alcohol copolymer are separately melt-kneaded in each extruder, supplied to the same extrusion die, and co-extruded together with a uniaxially oriented film (base layer) obtained by unidirectionally stretching a thermoplastic resin film containing from 3 to 40% by weight of an inorganic fine powder at a stretching temperature lower than the melting point of the thermoplastic resin to obtain a fusion-laminated film composed of the uniaxially oriented thermoplastic resin film having laminated on one or both sides thereof the polyolefin film, the adhesive resin layer, and the ethylene-vinyl alcohol copolymer film in this order. The resulting laminate film is then stretched in the direction perpendicular to the stretching direction of the unidirectionally oriented thermoplastic resin film at a temperature lower than the melting point of the polyolefin. There is obtained a laminate base film in which the paper-like layer(s) are uniaxially oriented and have a number of microvoids, the ethylene-vinyl alcohol copolymer layer is uniaxially oriented, and the base layer is biaxially oriented.
A stretched ethylene-vinyl alcohol copolymer film having a stretch ratio of, preferably, from 3.5 to 10 is adhesion-laminated on one or both sides of commercially available finely porous polyolefin type synthetic paper (e.g., Yupo FPG, KPK, GFG or SGG all produced by Oji Yuka Goseishi Co., Ltd.) via a polyurethane or polyester type primer.
The stretching in Processes (1) to (3) is preferably carried out at a stretch ratio of from 4 to 10 in either direction. The stretching temperature ranges from 150° to 162° C. for a propylene homopolymer (melting point: 164°-167° C.) as a polyolefin resin, or from 110° to 120° C. for high-density polyethylene (melting point: 121°-124° C.) as a polyolefin resin. The stretching speed usually ranges from 50 to 350 m/min.
It is preferable that the stretch ratio, stretching temperature, and stretching speed, and the inorganic fine powder content of the polyolefin composition is so selected that the microvoid volume (%) of the finely porous polyolefin film as represented by the following equation falls within a range of from 20 to 60%, and preferably from 25 to 45% and that the finely porous polyolefin film may have a degree of smoothness (JIS P-8119; Bekk's index) of not more than 2,000 seconds. Microvoid volume (%)={(V0 -V1)/V0 }×100
Synthetic paper was offset printed using an RI printing machine (manufactured by Akira Seisakusho) and an offset ink "TK Newmark V" (indigo blue) manufactured by Toyo Ink Mfg. Co., Ltd to an ink coating amount of 2.0 g/m2 (wet basis) and allowed to stand at room temperature for 24 hours to dry. The printed sheet was cut to a size of 10 cm× 10 cm, and the cut piece was placed on a horizontal plate. The total height of the four corners of the sheet from the plate was measured.
Further, the synthetic paper was printed with a screen ink "Sericol CG" (produced by Teikoku Ink Seizo K.K.) using a bar coater #10 to an ink coating amount of 8 g/m2 (solid basis) and allowed to stand at room temperature to dry. The printed sheet was cut to a size of 10 cm×10 cm, and the cut piece was placed on a horizontal plate. The total height of the four conrers of the sheet from the plate was measured.
(1) Preparation of Base Layer
A mixture of 80% of polypropylene having a melt flow ratio (MFR) of 0.8 g/10 min, 8% of high-density polyethylene, and 12% of calcium carbonate having an average particle size of 1.5 μm was kneaded in an extruder at 270° C., extruded into sheeting, and cooled by a cooling apparatus to prepare an unstretched sheet. The sheet was heated at 140° C. and longitudinally stretched at a stretch ratio of 5. The resulting stretched sheet was designated Base Layer 1.
A mixture of 51% of polypropylene having an MFR of 4.0 g/10 min and 49% of calcium carbonate having an average particle size of 1.5 μm was melt-kneaded in an extruder at 270° C. to obtain Compound (A). Separately, a maleic acid-modified polypropylene resin having a maleic acid content of 0.6% (MFR: 5.5 g/10 min) was melt-kneaded in an extruder at 270° C. to obtain Compound (B). Further, an ethylene-vinyl alcohol copolymer resin having an ethylene content of 46 mol % and an MFR of 6.0 g/10 min (melting point: 165° C.; degree of saponification: 96%) was melted in a separate extruder at 25° C. to obtain Compound (C). Compounds (A), (B), and (C) were fed to a three-layered die with Compound (B) as an intermediate layer and co-extruded on both sides of Base Layer 1 prepared as described above with the ethylene-vinyl alcohol copolymer as an outermost layer to obtain a 7-layered laminate sheet.
The resulting laminate was heated to 155° C. and transversely stretched at a stretch ratio of 7.5 to obtain a 7-layered stretched laminate base film having a total thickness of 150 μm, with the inorganic powder-containing polypropylene paper-like layers (2a, 2b) each being 20 μm thick, the ethylene-vinyl alcohol copolymer surface layers (3a, 3b) each being 15 μm thick, and the adhesive resin layers (3a', 3b') each being 10 μm thick. The resulting synthetic paper base film had an overall density of 0.80 g/cm3, an opacity of 90%, and a surface smoothness (Bekk's index) of 8,000 seconds.
A primer providing antistatic properties "Saftomer 3100" (produced by Mitsubishi Petrochemical Co., Ltd.) was coated on each side of the laminate base film obtained in (2) above to a thickness of 1 μm (solid), followed by drying at room temperature (about 20° to 30° C.) to form an anchor coat on each side. Then, a coating composition having the following formulation was coated on the anchor coat on each side to a thickness of 8 μm (solid) and dried at 70° C. for 1 minute to form a coat layer.
Starch 10 parts
Calcium Carbonate 30 parts
Clay 60 parts
Dispersing Agent (sodium tripolyphosphate)
Defoaming Agent (San-Nopco SN-DF-113)
Synthetic paper was produced in the same manner as in Example 1, except that the laminate base film did not include either the layer of Compound B (maleic acid-modified polypropylene film) or the layer of Compound C ethylene-vinyl alcohol copolymer film).
Synthetic paper was produced in the same manner as in Example 1, except that the layer of Compound B (maleic acid-modified polypropylene film) and the layer of Compound C (ethylene-vinyl alcohol copolymer film) were replaced with an extruded film of molten polypropylene having an MFR of 4.0 g/10 min (Compound D).
Synthetic paper was produced in the same manner as in Example 1, except that the extrusion rates of Compound B (maleic acid-modified polypropylene film) and Compound C (ethylene-vinyl alcohol copolymer film) were varied to achieve the layer thicknesses as shown in Table 2 below.
Synthetic paper was produced in the same manner as in Example 1, except the thickness of the ethylene-vinyl alcohol copolymer film (Compound C) was changed to 3 μm.
Base Layer 1 was prepared in the same manner as in Example 1. A mixture of 51% of polypropylene having an MFR of 4.0 g/10 min and 49% of calcium carbonate having an average particle size of 1.5 μm was melt-kneaded in an extruder at 270° C. to obtain Compound (E). Compound (E) was extruded on one side of Base Layer 1 and, at the same time, the three layers of Compounds (A), (B) and (C) as described in Example 1 were co-extruded through a three-layered die on the other side of Base Layer 1 to obtain a five-layered laminate base film with the ethylene-vinyl alcohol copolymer film as the outermost layer.
The laminate was heated to 155° C. and transversely stretched at a stretch ratio of 7.5 to obtain a stretched 5-layered laminate base film. The resulting laminate base film had a total thickness of 125 μm, with the layer (3a') (Compound B) being 10 μm thick, and the layer (3a) (Compound C) being 15 μm thick.
Synthetic Paper Layer Structure and Thickness (μm) Laminate Base Film Paper-Like Layer (2) Anchor Inorganic Top Layer (3) Coat Total Fine Powder- Surface Back Layer Thickness Base Containing PP Adhesive EVAlc Adhesive EVAlc Saftomer PP Example Laminate Layer Surface Back Layer Layer Layer Layer 3100 Layer No. Base Film (1) (2a) (2b) (3a') (3a) (3b') (3b) (4) (5)
150 60 20 20 10 15 10 15 1 --
100 60 20 20 -- -- -- -- 1 --
120 60 20 20 -- -- -- -- 1 surface: 10
Example 2 back: 10
150 60 20 20 5 20 5 20 1 --
150 60 20 20 20 5 20 5 1 --
130 60 20 20 10 5 10 5 1 --
126 60 20 20 10 3 10 3 1 --
125 60 20 20 10 15 -- -- 1 --
Height of Curling Offset Printability Offset Screen Ink Printing Printing Drying Surface Number of Pencil Example Opacity Ink Ink Properties Uneven- Back Stain- Writ- No. Appearance (%) (mm) (mm) (minutes) ness Free Prints ability
art 90 0 0 20 good 480 good
matte 90 25 15 20 poor 50 good
art 90 19 10 20 poor 50 good
art 90 0 0 20 good 490 good
art 90 0 0 20 good 400 good
art 90 0 0 20 good 430 good
art 90 3 3 20 medium
90 0 0 20 poor 100 good
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