JPH0364599A - Laminated water-resistant paper and its production - Google Patents

Abstract

PURPOSE:To obtain the title paper excellent in water resistance, printability, writability, ink adherability, dimensional stability. etc., by making an extrusion forming using a T-die so as to make up the outermost layer corresponding to the surface to be printed with a special thermoplastic resin. CONSTITUTION:(A) A molten resin containing 0-80wt.% of inorganic filler, consisting of (a) a copolymer from (1) 60-97wt.% of ethylene and (2) a compound of the formula (R is H or CH3; X is OCH3, OC2H5, etc.) (pref. ethyl acrylate) and (b) a thermoplastic resin such as polyolefin and (B) an inorganic filler-free thermoplastic resin, are extruded in a two-layer filmy form through a T-die so that, within said T-die, the resin B is located so as to come into contact with the surface of a paper substrate and the resin A is located at the outermost layer of the substrate, followed by laminating the surface of said paper substrate with the thermoplastic resin layers with at least the outermost layer consisting of the resin A, thus obtaining the objective paper.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention provides water resistance, writability, printability, low chargeability, ink adhesion, ink drying property, weather resistance, tear strength, dimensional stability, and lamination resistance with excellent opacity (3) (4) Concerning water paper.

[Conventional technology]

A two-layer structure in which a paper sheet is used as a base layer and the surface thereof is coated with polyethylene containing an inorganic pigment such as titanium dioxide, zinc oxide, or zinc sulfide, or an inorganic pigment-free polyethylene layer is interposed between the two layers. A support for photographic paper having a three-layer structure is known. (Tokuko Showa 49-3044
Publication No. 6) In these laminated papers, the fact that the resin layer is made opaque by the inorganic pigment has sufficiently improved the practicality of the paper. However, for more advanced requirements, three-layer laminated paper with an inorganic pigment-containing layer between both layers not only makes the resin layer opaque by containing the inorganic pigment, but also improves the surface of the paper base layer caused by the inorganic pigment content. A non-pigmented resin layer is interposed to prevent a decrease in adhesive strength between the resin layer and the resin layer.

[Problem to be solved by the invention]

In the support for photographic paper described above, a polyethylene resin layer is laminated on the surface of the paper in order to smooth the surface of the photographic paper for printing minute photographic images. The surface became transparent.

Therefore, a pigment is contained in the resin layer to form a white background, so that a clear photographic image can be obtained. In other words, in photographic supports, it is desirable to incorporate inorganic pigments into the polyethylene resin layer on the surface;
On the other hand, the blending of inorganic pigments must not impair the smoothness of the surface of the resin layer. Due to this relationship, the amount of compounding is restricted, and practically 7% by weight.
It is said that there is a limit to the degree.

In contrast, the laminated waterproof paper according to the present invention has excellent printability and
Must be writable.

For this purpose, the surface of the laminated waterproof paper needs to have an appropriate level of roughness, so if the amount of inorganic pigments used in photographic supports is about 7% by weight, the surface roughness is insufficient, and water-based or Oil-based printing ink or water-based writing ink (5) (6) It interferes with the fixing and drying of the ink. Furthermore, even if one attempts to write with a ballpoint pen or pencil, the problem arises that it is virtually impossible to write on the film, just as with the smooth film itself.

For this reason, the applicant of the present application not only provided a means to solve the above-mentioned problems in the prior art, but also incorporated a large amount of titanium dioxide or zinc oxide, which is used for opacification in photographic paper supports, into the resin layer. However, the disadvantage arises from the fact that the high chargeability of the resin layer cannot be reduced even when the high chargeability of the resin layer is maintained. In addition, a means for solving the problem of feeding two or more sheets in a stacked state due to mutual bow absorption force due to static electricity between the sheets, which causes troubles such as paper jams, has been provided. (Patent Application No. 18374/1983) However, printing paper for book covers and packaging is often required to not peel off the ink due to friction or scratches on the ink printed area after printing, but this is still not the case. No suitable improvement method has been found for this point.

[Means for Solving the Problems] The present inventors have developed a laminated waterproof paper that has printability, writability, and adhesiveness that are different from existing photographic paper supports. The outermost layer of resin corresponding to the surface is 6
A copolymer consisting of 0 to 97% by weight of ethylene and one or more compounds represented by the following formula (A) (wherein, R is H or CI+3, and X is OCH3,0C
21(SOCzl14N(CH3)z, 0Czll
J(Cztls)z, 0(C1ls)aυ and a thermoplastic resin, and has a content of 0 to 80 with respect to the resin.
It has been found that it is beneficial to include % by weight of inorganic filler, preferably 30-50% by weight.

The average particle diameter of the inorganic filler used is usually 0.01 to 10 μm, preferably 0.061 to 10 μm, from the viewpoint of dispersibility in the resin layer and the writability and printability that the inorganic filler imparts to the resin layer. It is about 5 μm.

(7) (8) Furthermore, the attributes of the inorganic filler include specific surface area and oil absorption. For example, titanium dioxide is a rutile type with a specific surface area of 1 to 50 n(/)z and an oil absorption of 10 to 5.
0mff1/100 g, for calcium carbonate,
Average particle size 0.5-10 marks, specific surface area 0.5-70n (7
g, preferably 1 to 30 n/g (BET method), oil absorption 5 to 100 m/100 g, preferably 10 to 10
It is preferable that it is heavy with m/100g.

Other effective inorganic fillers include talc, clay, kaolin, barium sulfate, calcium carbonate, calcium silicate, magnesium carbonate, titanium oxide, zinc oxide,
Examples include magnesium oxide, silicon oxide, diatomaceous earth, magnetic iron oxide, etc., and mixtures thereof.

Note that a small amount of organic filler such as carbon black, phenol resin, melamine resin, or urea resin may be mixed in, and fatty acid salts, tackifiers, and hydrophilized polyolefins may be added as auxiliary means to improve the dispersibility of the inorganic filler. It is also possible to add wax or the like as appropriate, or to perform surface treatment on the inorganic filler with them.

In practice, it is not easy to incorporate 20% by weight or more of an inorganic filler into a resin layer and produce a thin layer with a thickness of about 10 μIn. In order to form a thin film with a thickness of 20 parts or less even though the inorganic filler is incorporated in the resin layer at a high content of 20% by weight or more, it is preferable to control the moisture content of the inorganic filler to 500 ppm or less.

The thermoplastic resin forming the resin layer for producing the laminated paper of the present invention is preferably a polyethylene resin, a polypropylene resin, or a polyester resin.

Here, the polyolefin resin is not limited to a 1-olefin homopolymer, but also includes compositions of different types of polymers or copolymers, including copolymers of 1-olefins.

(1) Polyethylene resin has a melt flow rate (MFR(190'C) ) of 3 to 20 g/
10m1n, melt tension (-melt tension, 190
°C1 extruder orifice L/D=3.8, extrusion speed 1
5mm/min.

It is preferable that the weight is 0.3 to 11 g (take-up speed 15 m/m1n) (9) (10).

(2) As the polypropylene resin, MeltFlowy 1-(MFR(230°C)) 15-50
g / 10 m1n, melt tension (230 ° C1 extruder orifice L / D = 3.8, extrusion speed 15 mm
/min, take-up speed 15 m/m1n) is preferably 0.3 to 3.3.

(3) A copolymer consisting of 60 to 97% by weight of ethylene and one or more compounds represented by the following formula (A) (where R is ■4 or C1h, X is 0CIh,
OC,! llr.

0C2114N(CI+3)2, 0C2114N(C
2115)2,0(C113)3 means ethylene-
(Meta) ethylene-(meth)acryethylene-(meth)acryethylene-(meth)acryamino)ethyl copolymer, acrylic acid copolymer, methyl ruate copolymer, ethyl ruate copolymer, ruic acid- 2-(dimethylethylene-(meth)acrylate-2-(diethylamino)ethyl copolymer, ethylene-glycidyl (meth)acrylate copolymer, ethylene-hydroxyethyl (meth)acrylate copolymer,
Ethylene-isobutyl acrylate copolymer or ethylene-(meth)acrylic acid amide copolymer.

The preferred ethylene content of this copolymer is 65-95% by weight.

Particularly preferred are ethylene-ethyl acrylate copolymer and ethylene-methyl methacrylate copolymer.

In a copolymer consisting of ethylene and a compound represented by formula (A), the compound unit of formula (A) is in the outermost layer of the resin, that is, 1 to 40% by weight, preferably in the blend of the copolymer and thermoplastic resin. Both are blended at a weight of 1.5 to 30% by weight of 7%. The scope of the present invention also includes cases where the copolymer alone contains 1 to 40% by weight of the compound unit of formula (A) without blending a thermoplastic resin with the copolymer.

The method for producing the laminated paper of the present invention is to extrude a polyolefin resin layer containing no inorganic filler on at least one surface of the paper base layer (11) (12) using a T-die film forming machine, and then Then, an ethylene-(A) formula compound copolymer and an inorganic filler-containing polyolefin resin layer (hereinafter simply referred to as an inorganic filler-containing layer) are extruded from a T-die film machine, and the three are laminated and bonded. A method of doing so is preferred.

Here, the thickness of each resin layer is usually 3 to 20 gn, preferably 5 to 10 μm in the inorganic filler-containing layer, and usually 3 to 25 μm, preferably 5 to 20 μm in the layer in contact with the paper base material.
Let it be μm. There is no problem in making the inorganic filler-containing layer thicker or thinner than the inorganic filler-containing layer.

The outermost layer and the resin layer in contact with the paper must be made of the same type of material, such as a combination of low-density polyethylene resins, high-density polyethylene resins, polypropylene resins, and poly-1-butene resins. is preferred. Even when these polymers are composed of a composition of two or more types of polymers, it is preferable that the breakdown of the constituent polymers of each layer and the blending ratio of the two are the same between both layers.

As a method for producing the laminated paper of the present invention, a method of laminating and adhering the paper base layer while extruding a thermoplastic resin layer containing an inorganic filler on at least one surface from a T-die film forming machine is preferred.

The laminated paper obtained by this method has sufficient interlayer adhesive strength for normal use.

A more preferred manufacturing method is a method in which an inorganic filler-free resin layer is interposed between the paper base layer and the inorganic filler-containing resin layer, as described below. According to this method, even if the inorganic filler layer is made thinner, it becomes easier to suppress the occurrence of film breakage and perform stable molding.

Of course, the inorganic filler-containing resin layer may be laminated and bonded directly on both sides of the paper base layer, or after laminating the inorganic filler-incompatible resin layer on both sides of the paper base layer, or simultaneously with the lamination. There is no problem even if an inorganic filler-containing resin layer is further laminated and adhered to the surface of the resin layer.

Furthermore, in order to improve adhesion to paper, the surface of the paper base layer before extrusion coating is subjected to flame treatment, corona discharge treatment, and preheating treatment, or laminated (process 3) (14). It is desirable to perform treatment such as ozone treatment on the surface of the resin layer that is to be in contact with the paper. As a result, low-temperature adhesion becomes possible, reducing the frequency of occurrence of eye stains from the resin, and preventing resin deterioration and tear strength reduction.

The surface roughness of waterproof paper obtained by laminating a resin layer on a paper base layer can be changed by appropriately selecting the content of inorganic filler, average particle size, and thickness of the outermost layer. However, pencil writing ability can be improved by changing the cooling roll pattern of the laminator to give the product a matte finish. Pama here)
・It means that the gloss at the 60' angle of incidence is 30% or less.If necessary, antistatic agents, ink adhesion improvers, ultraviolet absorbers, etc. are added to at least one layer of the resin. Alternatively, it may be applied to the surface of the outermost layer.

In the present invention, by combining specific types of inorganic fillers, it is possible to impart "adhesive" writability and printability to the resin layer without substantially increasing chargeability.

In particular, the outermost thermoplastic resin layer contains 30 to 5 inorganic fillers.
Furthermore, the inorganic filler mainly consists of calcium carbonate and titanium dioxide, and the ratio of the two is 99:] to 55:45, preferably 80:20 to 6.
A ratio of 0:40 is most desirable. In the case of such a configuration, the surface resistance value of the outermost layer is IXIO”~9×1
The resistance was 0'5Ω, and both the writability and printability were extremely good.

The surface resistance of the laminate of the present invention is a value measured at 23°C1 relative humidity (RH) of 60%.

Printing papers for book covers and packaging are often required to have no ink peeling even when the ink printing area is smeared or scratched after printing.

The present invention provides a means for solving this problem by incorporating a copolymer consisting of ethylene and a compound represented by formula (A) into the resin layer to improve chemical adhesion.

〔Example〕

Examples of the present invention and comparative examples thereof are shown below.

The following physical properties were measured for the laminated waterproof paper (15) (16) obtained in Examples and Comparative Examples, and the results are shown in Tables 1 and 2.
It was shown to.

[Measurement properties] [Measurement method] 1) Thickness: JIS P-81182) Writability: A pencil test was conducted under constant pressure using a pencil with a hardness of 2B.

The judgment criteria are as follows.

◎ Can write very well ○ Can write well × Not at all 3) Surface resistance value
Using 601VE-30, 23°CX60%R11
(7) Measured in atmosphere.

4) Printing suitability: Roland offset lithographic printing i
(202B) was used. The dimensions of the printing paper are 297
The paper size was 420 mm (A3), the paper feeding speed was 8000 sheets/hour, and the atmosphere in the printing room was 20°C x 50% R11. Incidentally, the ink used was Dainippon Ink Chemical Industry ■ POP-S.

5) Adhesion of ink: 24 hours after printing is finished, firmly stick a 24 mm wide cellophane tape (manufactured by Chiban) on the ink-printed surface and peel it off vigorously.

If no ink is removed by the sellotape at this time, ◎ Slightly ○ If it is removed, × 6) Ink drying properties: 1 hour after printing, if you touch the printed surface lightly with your finger and the ink does not stick to your finger at all, ◎ 〃 Somewhat sticky ○ 〃 If stuck × (Example 1) 20 parts by weight of ethylene-ethyl acrylate copolymer (MFR5, ethyl acrylate content 9%) and low density polyethylene L
/7 (npR11g/10min, density 0.916g
/cl.

75% by weight of a resin consisting of 80 parts by weight (melt tension 1.3 g) was melted, and calcium carbonate (average particle size 2 μm) and titanium oxide (average particle size 0.2
μm) at a weight ratio of 95:5 and 25% by weight (1
7) (18) Add and mix. This mixture was extruded through a T-die at a temperature of 290°C, and while blowing ozone-containing air to the surface of the molten film to be bonded to the paper, it was laminated on both sides of waterproof copying paper with a thickness of 60 μm and a width of 500 mm. get.

At this time, the ozone treatment conditions were as follows: the lamination speed of the molten film was 10
0m7min, air gap 130mm, ozone concentration 40
g/r&, the ozone flow rate is 2n (/h).The waterproof copying paper used in this example has a basis weight of 48 g/nf.
Using high-quality paper as the base paper, starch/polyvinyl alcohol = 8
0/20 coating liquid at a coating amount of 1 to 2 g/n (Size Press Coated with a Styzkicht-reinforcement degree of 30 seconds.
This is xerographic copy paper. The results are shown in Table 1.

(Example 2) 30 parts by weight of ethylene-methyl methacrylate copolymer (MFR methyl methacrylate content 30%) and Example 1
25% by weight of the resin consisting of 70 parts by weight of the low-density polyethylene used in the above is melted, and 75% by weight of calcium carbonate and titanium oxide are added and mixed in a weight ratio of 60:40. Separately, prepare the above-mentioned low-density polyethylene that does not contain an inorganic filler, and use this resin that does not contain an inorganic filler as the lower layer in contact with the paper.
Co-extrusion T using the above inorganic filler-containing resin as the outermost layer
The mixture was extruded from a die at a temperature of 290° C. and pressed onto both sides of the same waterproof copying paper as in Example 1 to obtain a laminated waterproof paper.

(Example 3) 80 overlapping parts of ethylene-ethyl acrylate copolymer (ethyl acrylate content 35%) and polypropylene (MFR2
5g/10min, density 0.91g/cIIY, melt tension 0.5g) 65% by weight of resin consisting of 20 parts by weight was melted, and calcium carbonate and titanium oxide were added to it in a weight ratio of 95:5. 35% by weight
Add and mix. Separately, prepare the above-mentioned polypropylene that does not contain an inorganic filler, use this inorganic filler-free resin as the lower layer in contact with the paper, and use the above inorganic filler-containing resin as the outermost layer. At a temperature of 290"C from a coextrusion T-die, the same method as in Example 1 is used to extrude and press-bond onto both sides of waterproof copying paper to obtain a laminated waterproof paper. During coextrusion, the lower layer in contact with the paper is melted. The surface of the resin film to be bonded to the paper (19) and (20) is subjected to the same ozone treatment as in Example 1.

(Example 4) In Example 3, titanium oxide and silica were added in addition to calcium carbonate, and the mixing ratio was 70:20:10.
A laminated waterproof paper was obtained in the same manner except that high-quality paper (basis weight 70 g/r4) was used as the paper base layer.

(Example 5) Example 3 was repeated except that the blending ratio of calcium carbonate and titanium oxide in Example 3 was changed to 75:25, and the co-extrusion and pressure bonding was carried out only on one side of the waterproof copying paper instead of on both sides.
Obtain laminated waterproof paper.

(Examples 6, 7 and 8) In Example 3, the blending ratio of calcium carbonate and titanium oxide used as inorganic fillers and the film thickness were changed as shown in Table 1 to obtain laminated waterproof paper.

(21)

Claims (1)

[Scope of Claims] 1. Paper is used as a base material layer, and at least one layer of thermoplastic resin is laminated on the surface thereof, and at least the outermost resin layer is made of 60 to 97% by weight of ethylene and Copolymer consisting of one or more compounds represented by formula (A) ▲ Numerical formulas, chemical formulas, tables, etc. are available ▼ (A) (However, R is H or CH_3, X is OCH_3, O
C_2H_5, OC_2H_4N(CH_3)_2, O
C_2H_4N(C_2H_5)_2▲Mathematical formula, chemical formula,
There are tables, etc. ▼, OC(CH_3)_3, OCH_2
It is CH_2OH. ) and polyolefin, and 0 to 80% by weight of an inorganic filler based on the resin, a laminated waterproof paper with good printability and low chargeability. 2. Paper is used as a base material layer, and at least one thermoplastic resin layer containing no inorganic filler is laminated on the surface thereof, and 60-97% by weight of ethylene and the following formula (A) are further laminated on the surface of the resin layer.
) A copolymer consisting of one or more compounds represented by ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (A) (However, R is H or CH_3, X is OCH_3, O
C_2H_5, OC_2H_4N(CH_3)_2, O
C_2H_4N(C_2H_5)_2▲Mathematical formula, chemical formula,
There are tables, etc. ▼, OC(CH_3)_3, OCH_2
It is CH_2OH. ) and a polyolefin, and at least one resin layer containing 0 to 80% by weight of an inorganic filler based on the resin is laminated, and has good printability and low chargeability. 3. At least the outermost layer of the resin contains 30 to 50% by weight of an inorganic filler, and the inorganic filler mainly consists of calcium carbonate and titanium dioxide, and the ratio of the two is 80:20 to 60 on a weight basis. 40. The laminated waterproof paper according to claim 1 or 2, characterized in that the paper has a molecular weight of 40. 4. In a copolymer consisting of ethylene and a compound represented by formula (A), the compound unit of formula (A) is 1 to 4 in the resin in the outermost layer.
The laminated waterproof paper according to any one of claims 1 to 3, characterized in that the content is 0% by weight. 5. A copolymer consisting of 60 to 97% by weight of ethylene in a molten state containing 0 to 80% by weight of an inorganic filler and one or more compounds represented by the following formula (A) ▲ Numerical formula, chemical formula, There are tables etc.▼(A) (However, R is H or CH_3, X is OCH_3, O
C_2H_5, OC_2H_4N(CH_3)_2, O
C_2H_4N(C_2H_5)_2, ▲There are mathematical formulas, chemical formulas, tables, etc.▼, OC(CH_3)_3, OCH_
It is 2CH_2OH. ), the outermost layer of thermoplastic resin, and the thermoplastic resin containing no inorganic filler are laminated in the T-die so that the latter resin is located on the side in contact with the surface of the paper base layer. A method for producing laminated waterproof paper, which comprises extruding it into a two-layer film and laminating and adhering it to the surface of a paper base material. 6. Using paper as a base layer, at least one polyolefin resin layer containing no inorganic filler is extruded and laminated in a molten state on the surface thereof, and then 99 to 55% by weight of calcium carbonate and 1% of titanium oxide are added to the surface of the resin layer. -45% by weight of an inorganic filler based on the resin, and 60-97% by weight of ethylene and one or more compounds represented by the following formula (A). Copolymer▲There are mathematical formulas, chemical formulas, tables, etc.▼(A) (However, R is H or CH_3, X is OCH_3, O
C_2H_5, OC_2H_4N(CH_3)_2, O
C_2H_4N(C_2H_5)_2, ▲There are mathematical formulas, chemical formulas, tables, etc.▼, OC(CH_3)_3, OH_2
It is CH_2OH. ) and a thermoplastic resin, the outermost layer is extruded and laminated in a molten state.