JPS62212650A - Production of photographic paper base - Google Patents

Abstract

PURPOSE:To obtain a photographic base which obviates generation of microgrit and has improved hiding power by melt-extruding and coating a polyolefin compd. contg. a specific bisamide onto a paper base body. CONSTITUTION:The polyolefin resin compsn. contg. the bisamide expressed by the formula is melt-extruded and coated on the paper base body. In the formula, R<1> and R<3> denote an alkyl group of 1-30C, R<2> denotes an alkylene group of 2-12C, the numbers of carbon atoms of R<1> and R<3> are particularly preferably 15-27, and the number of carbon atoms of R<2> is particularly preferably 2-6. The amt. of the bisamide to be used is preferably 0.01-2.0wt% per the total amt. of the polyolefin resin compsn. and more particularly preferably 0.05-1.0wt%. A fatty acid metallic salt, etc. which are generally used as a dispersant for titanium dioxide may be mixed with the bisamide and the amt. of the titanium dioxide pigment to be added to the polyolefin resin is particularly preferably in a 9-50wt% range.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to a method for producing a support for photographic paper, and more particularly, a polyolefin resin containing titanium dioxide is applied to at least one surface of a paper or synthetic paper substrate. The present invention relates to a method for producing paper coated with nine polyolefin resins by melt extrusion coating a composition into a film.

(Prior Art) A method for manufacturing photographic polyolefin resin-coated paper is already known. For example, in U.S. Pat. A method is disclosed in which the layer contains titanium dioxide, a true color pigment, a fluorescent whitening agent, and the like.

In the first place, the method of incorporating pigments into polyolefin resin is to create a so-called masterbatch in which the pigments are contained in the resin at a high concentration in advance, and then dilute and mix them with a diluent resin to the desired ratio. It is usual to prepare and use a so-called compound in which a desired composition ratio of the compound is contained in a resin from the beginning.

However, especially when preparing a masterbatch or compound by melt-kneading using a Banbury mixer, kneader, etc., relatively coarse pigment particles may be mixed in the resin.
There is a tendency for pigment particles to be dispersed as they are rather than being dispersed in a fine state, thus resulting in the presence of undispersed pigment particles in the masterbatch or compound. the result,
On the resin surface of a photographic support, at least one surface of a paper or synthetic paper substrate is coated with a resin composition consisting of a pigment and sesame oil produced using the masterbatch or compound, This results in the generation of foreign matter or microgrit, which is minute particles.

The occurrence of microgrit in a photographic support causes serious photographic defects, i.e., when a person is photographed on a photographic paper that has a resin-coated paper with microgrit as a support for photographic paper, % of the face, etc. When microgrit appears in a product, its commercial value completely disappears.

Furthermore, the hiding power of photographic paper supports containing microgrit is greatly reduced.

(Purpose of the invention) The object of the present invention is to eliminate the generation of microgrit.

An object of the present invention is to provide a photographic support with greatly improved hiding power.

(Structure of the Invention) The object of the present invention is to provide a support for photographic paper in which a resin composition comprising at least a titanium dioxide pigment and a polyolefin resin is melt-extruded and coated on at least one side of a paper or synthetic paper substrate. Achieved by a method for producing a support for photographic paper, which method comprises melt-extruding and coating a polyolefin resin composition containing a bisamide represented by the following general formula (I) onto a paper base. It was done.

R'-NHCO-R2-CONH-R' (I)
In the above formula, R1 and Rs represent an alkyl group having 1 to 30 carbon atoms, and B2 represents an alkylene group having 2 to 12 carbon atoms.

In the general formula (I), R1 and Rs may be the same or different, and may be linear or branched. The alkylene group represented by B2 may be linear or branched. But it's okay.

R1 and R in the bisamide represented by the general formula (I)
The carbon number of 6 is 15 to 27, and that of R2 is 2 to 6
Particularly preferred are those.

In the present invention, the amount of bisamide (I) used is 0.01 to 2.0% by weight based on the total amount of the polyolefin resin composition.
% is preferable, and 0.05 to 1.0 weight is particularly preferable.

The bisamide (I) of the present invention may be used in combination with a fatty acid metal salt or the like that is generally used as a dispersant for titanium dioxide.

The amount of titanium dioxide pigment added to polyolefin resin is
If the amount is less than 5% by weight of the polyolefin resin composition, the hiding power will be insufficient as a photographic support, while if it is more than 60% by weight, the fluidity will decrease, which is undesirable. Particularly preferably, 9- The range is 50 double needles.

As the polyolefin in the present invention, low-density polyethylene, medium-density polyethylene, and high-density polyethylene with various densities and melt viscosity indexes can be used alone or in combination.

In addition to titanium dioxide, the polyolefin resin composition of the present invention further contains white pigments such as zinc oxide, Merck and calcium carbonate, fatty acid amides such as stearic acid amide and alaxic acid amide, and 2゜6-sheet tart- Antioxidants such as butyl-4-methylphenol, group! , a coloring pigment such as red iron oxide, a fluorescent whitening agent, etc. may be added.

The polyolefin resin-coated paper according to the present invention is produced by melt-extruding a polyolefin resin composition onto a paper or synthetic paper substrate (hereinafter simply referred to as base paper) that runs normally through a slit die in the form of a film. At that time, the melt extrusion temperature is preferably 200°C to 350°C. As a slit die.

T-type dies, LfJ dies, and fishtail dies are preferred, and the slit opening diameter is preferably 0.1 to 1 m. Further, before coating the resin composition on the base paper, it is preferable to subject the base paper to an activation treatment such as a corona discharge treatment or a flame treatment. The thickness of the resin layer of the resin-covered paper is not particularly limited, but it is generally advantageous to extrude coat it to a thickness of about 5 microns to 50 microns. In addition, in ordinary polyolefin resin-coated paper in which both sides of the base paper are coated with resin, the resin surface containing titanium dioxide (emulsion coated surface) can be glossy, matte, or silky depending on the purpose. The back surface is usually a matte surface, and activation treatments such as corona discharge treatment and flame treatment can be performed on the front surface or both the front and back surfaces as necessary.

The base paper used in the practice of the present invention may be ordinary natural pulp, paper, synthetic fiber paper, or so-called synthetic paper made of agglomerated synthetic resin film, but may include softwood pulp, hardwood pulp, and mixed softwood and hardwood pulp. Natural pulp paper based on wood pulp is advantageously used. There is no particular restriction on the thickness of the base paper, but a base paper with good surface smoothness is preferred, and its basis weight is 50 f/d to 250 f/nl.
is preferred.

The base paper mainly composed of natural pulp, which is advantageously used in carrying out the present invention, can contain various polymeric compounds and additives.For example, cationized starch, cationized Polyacrylamide, anionized polyacrylamide, carboxy-modified polyvinyl alcohol, gelatin, etc., as a sizing agent, fatty acid salt, rosin derivative, dialkyl ketene dimer emulsion, petroleum resin emulsion, styrene-maleic anhydride'IR co-M combined alkyl ester. Ammonium salts, etc., as pigments,
Clay, kaolin, return limit calcium, barium sulfate, titanium dioxide, etc., as wet paper strength enhancers, melamine resin,
Urea resin, epoxidized polyamide resin, etc., polyvalent metal salts such as aluminum sulfate and aluminum chloride as fixing agents,
As a PH regulator for cationic polymers such as cationized teaching powder.

As an inorganic electrolyte, such as caustic soda, charcoal soda, hydrochloric acid, etc.
In addition to salt, mirabilite, etc., dyes, fluorescent brighteners, latex, etc. can be contained in appropriate combinations.

The photographic support according to the present invention can have various silver halide photographic emulsion layers and gold films. For example, a silver chloride, silver bromide, silver chlorobromide, silver ambush, or silver chloroiodobromide emulsion layer can be provided. Furthermore, a multilayer silver halide photographic constituent layer can be provided by containing a color coupler in the silver halide photographic emulsion layer. As the binder for these silver halide emulsion layers, in addition to usual gelatin, hydrophilic polymeric substances such as polyvinylpyrrolidone, polyvinyl alcohol, and polyvinyl nitrate ester compounds can be used. Further, the above-mentioned silver halide emulsion layer can contain various additives. For example, sensitizing dyes include cyanine dyes and merocyanine dyes, chemical sensitizers include water-soluble gold compounds and sulfur compounds, and anti-capri agents or stabilizers include human axy-triazolopyrimidine compounds,
Mercapto-heterocyclic compounds, etc., as hardening agents, formalin, vinyl sulfone compounds, aziridine compounds, etc., as coating aids, benzenesulfonate, sulfosuccinate salts, etc., as anti-staining agents, dialkylhydroquinone compounds, etc., ultraviolet absorption Agents include benzotriazole compounds, other fluorescent whitening agents, sharpness-enhancing dyes, antistatic agents, PH regulators, and silver halide formation and
At the time of dispersion, a suitable combination of water-soluble iridium, rhodium compounds, etc. can be contained.

(Example of the invention) Next, Mizumoto Meikin will be explained in more detail with examples.

Low density poly x chi v y (M I = 5, density f0.
918) A titanium dioxide masterbatch was obtained by kneading 50 doublets and titanium dioxide according to the recipe shown in Table 1 using a Banbury mixer at 1501:.

The masterbatch obtained in this way is made up of 13 times more titanium dioxide than polyethylene! It was diluted with polyethylene to give Ik%, and melt-extruded onto a polyester film with a basis weight of 105 P/m' at a coating speed of 80 m/min.
Melt extrusion coating was performed at a melting temperature of 320° C. and a coating time of 30 f/bat.

(The following is a margin) The opacity in Table 1 shows the results measured using a Hunter whiteness meter (using a CG filter). The larger the number, the
Hiding power increases. Also shown are the results of visually counting the number of microgrits generated on the polyethylene resin surface of each sample.

These results show that the manufacturing method according to the present invention provides a product with good p1 opacity and microgrit.

Claims (1)

[Claims] In a method for producing a support for photographic paper in which a film-like melt extrudate made of a polyolefin resin composition in which titanium dioxide is dispersed is coated on a paper base, 1. A method for producing a support for photographic paper, which comprises melt-extrusion coating a polyolefin composition containing a bisamide in a paper substrate. R^1NHCO-R^2-CONH-R^3 (I) In the above formula, R^1 and R^3 are an alkyl group having 1 to 30 carbon atoms, and R^2 is an alkylene group having 2 to 12 carbon atoms. represents.