JPH042175B2 - - Google Patents

Description

[Detailed description of the invention]

A. Industrial Application Field The present invention relates to a method for producing a photographic support with improved whiteness on the side on which an image is formed. In addition, the present invention appropriately combines a blue pigment and a red pigment,
A technology that neutralizes the yellowing tendency caused by titanium oxide contained in a high concentration in the resin layer on the same side as the image forming side of a resin-coated paper-type photographic support and improves visual whiteness. Regarding. In recent years, photographic supports coated on both sides with paper and resin, particularly polyethylene, have come into widespread use. The resin layer on the side on which the image is formed contains a titanium oxide pigment at a high concentration in view of image sharpness and other photographic performance requirements. Since the titanium oxide pigment has a yellowish tinge, if used as is, the whiteness of the white background of the photographic image will be insufficient. Particularly in recent years, when used for color photographic paper, which has been widely used, faithful color reproduction and vivid colors are required. required. B. Related Prior Art (a) In Examples 1 to 5 of U.S. Patent No. 3501298, in addition to titanium oxide in the resin, ultramarine, cobalt blue, etc. are used as blue pigments, and cobalt oxide phosphate (Ferro Colors Corp.) is used as a red pigment. Made by Raspberry
V-6260), the inclusion of quinacridone red. (b) In addition to the above, Examples 6 and 7 of the same patent include
It is disclosed that an optical brightener called Uvitex OB (manufactured by Ciba Gaiki Co., Ltd.) is included in the resin. (c) In the example of JP-A No. 53-19021, in addition to titanium oxide in the resin, ultramarine was used as a blue pigment, and Daiichi Pink DP-1 and Daiichi Violet DV-1 were used as red pigments (both Daiichi (manufactured by Kasei Kogyo)
It has been disclosed to include a cosmetic ultramarine called . C. Disadvantages of the prior art) Although the technique of a) allows obtaining a visually balanced support with high whiteness,
Among the red pigments used, cobalt oxidized phosphate has weak coloring power, and a large amount is required to obtain a desirable color tone. In addition, since this pigment usually has a high water content, it tends to cause cracks in the resin film due to water vapor blowing out during hot melt extrusion coating. Furthermore, a high water content promotes the tendency for degraded resin compositions to adhere and accumulate at the die lip opening of an extrusion coating machine and grow in an icicle shape. (Such dirt that adheres to and grows at the lip opening is hereinafter referred to as die lip dirt.) When this die lip dirt occurs, it causes streak-like scratches on the resin film, significantly reducing the value of the product, and eventually completely destroying it. It becomes worthless. The only way to remove die lip stains that have occurred is to temporarily stop production and clean the die lip, which requires a great deal of effort and time.
Significantly reduces productivity. It is very difficult to use a large amount of pigments with such high water content. ) Quinacridone Red, the other red pigment disclosed in the technique (a), has strong coloring power and can be added in a small amount, so there are no harmful effects caused by moisture. However, because the primary and secondary particles of the pigment are hard, the pigment is called microgrit. Foreign matter tends to appear as particles on the resin surface. If this microgrit is generated, the value as a photographic support is completely lost. ) Fluorescent brightener disclosed in the technology of (b)
Uvitex OB has a tendency to bleed out from the resin, and not only does it have problems with color stability, but it also has problems with adhesion to the photographic emulsion layer. Furthermore, when applied to color photographic paper, the whitening effect is also limited due to the presence of an ultraviolet absorbing layer in the layers constituting the multilayer emulsion. ) The red pigments Daiichi Pink DP-1 and Daiichi Violet disclosed in the technology of c)
DV-1 both have weak coloring power and high water content. Therefore, the harmful effects caused by moisture as described in item () are significant. D. Object of the present invention Therefore, the object of the present invention is to use a quinacridone-based support that does not have the adverse effects of moisture and does not bleed out from the resin layer when producing a resin-coated paper-type photographic support with high visual whiteness. The purpose is to improve the dispersibility of red pigments and prevent the generation of microgrit. E Structure of the present invention The purpose of the present invention is to manufacture a resin-coated paper-type photographic support in which both sides of paper are coated with a film-forming resin. The resin A to be coated by hot melt extrusion coating contains at least a) titanium oxide, b) an inorganic bluish pigment, and c) a low molecular weight thermoplastic resin that has a softening temperature lower than that of the resin A and is solid at room temperature. This is achieved by including a premixed quinacridone red pigment in B. F. Effects of the present invention By carrying out the present invention, the generation of microgrit in quinacridone red pigments can be significantly reduced, and there is no adverse effect due to moisture, and the visual appearance of the side on which an image is formed can be improved. It is possible to produce a resin-coated paper-type photographic support with improved whiteness. G Detailed explanation of structure and effects The titanium oxide pigment used in the practice of the present invention may be of the rutile type or the anatase type, but if visual whiteness is important, the anatase type is preferable. Preferably used. Titanium oxide may be modified by precipitating hydrated aluminum oxide or hydrated silicon dioxide on its surface, singly, sequentially, or simultaneously. Treatment with an organic compound such as siloxane treatment or fatty acid metal salt treatment such as zinc stearate or calcium stearate may be performed. Furthermore, titanium oxide that has not been subjected to any surface treatment can also be used. Further, it is particularly preferable that the titanium oxide pigment has undergone a wet classification process. If the amount used is too small, there are problems such as insufficient hiding power and insufficient image sharpness. If added to the resin at too high a concentration, fluidity during melting will deteriorate, significantly impairing processing suitability. Particularly preferably from 7% by weight in the resin composition.
It is good to include 20%. Inorganic blue pigments used in the practice of the present invention include ultramarine blue, navy blue, cobalt blue, etc., and ultramarine blue is preferably used. The amount used is usually 0.025-0.5% by weight. Quinacridone red pigments used in the practice of the present invention include quinacridone yellow, quinacridone blue, quinacridone violet, quinacridone scarlet, quinacridone magenta, etc.
Preferably, the quinacridone red type, for example, the trade name Hoster Palm Pink E (manufactured by Hoechst) is used. The amount used is usually 0.001-0.01% by weight. If the amount is less than 0.001% by weight, the reddishing effect will be insufficient and the white appearance will not be improved. On the other hand, if it exceeds 0.01% by weight, it will give an excessive reddish tinge, which will even lead to a decrease in whiteness. As the resin A used in carrying out the present invention, polyolefin resins such as polyethylene and polypropylene are preferable, and polyethylene resins are particularly preferable. Low-density polyethylene, medium-density polyethylene, high-density polyethylene, etc. can all be used as the polyethylene resin, and these two
You may use a combination of more than one species. Further, polyethylene resins having various melting indexes (MI) can be used, and two or more of these resins having various MIs can be used in combination. The low molecular weight thermoplastic resin B used in the practice of the present invention is, for example, a low molecular weight polyalkylene having a molecular weight of about 1500 to 5000 and a softening temperature of about 80 to 115°C. Low molecular weight polyethylenes known by trade names such as A Wax (BASF), Sun Wax (Sanyo Chemical), etc. are suitable. As mentioned above, quinacridone red pigments have hard primary particles and secondary particles, so microgrits tend to appear. Therefore, it is important to premix it with the above-mentioned low molecular weight thermoplastic resin B in advance. Preferably, the preliminary mixing method is carried out by a roll kneading method, a heating kneader method, a Banbury mixer method, or the like. Furthermore, these can also be used in combination. The mixing ratio of the quinacridone red pigment and the low molecular weight thermoplastic resin is preferably 3:7 to 7:3, particularly preferably 4:6 to 6:4, by weight. A mixture having such a compounding ratio is kneaded at a temperature higher than the softening temperature, for example, 90 to 180°C, using a heated kneader, etc., and then subjected to a dispersion treatment using a hot triple roll, etc., and then cooled to form flakes. A premix of the following is obtained. A desired masterbatch can be obtained by adding the premix, the resin A, the titanium oxide pigment, and the inorganic blue pigment used in the practice of the present invention into, for example, a Banbury mixer, heating and kneading. In the resin layer of the photographic support in the present invention,
A fatty acid metal salt may also be included. Examples of these fatty acid metal salts include zinc stearate, calcium stearate, aluminum stearate, magnesium stearate, zirconium octylate, sodium palmitate, calcium palmitate, and sodium laurate. The amount added is preferably in the range of 0.01 to 5% by weight based on the resin composition containing the titanium oxide pigment. White pigments such as zinc oxide, talc, calcium carbonate, antioxidants, etc. may be added to the photographic resin composition of the present invention, if necessary. The photographic support of the present invention is manufactured by melt-extruding a heated and melted resin composition onto at least one surface of a paper or synthetic paper substrate (hereinafter simply referred to as base paper) that is normally run in the form of a film using a slit die. Ru. Usually melt extrusion temperature is 200℃~350℃
It is preferable that Furthermore, 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. There is no particular limit to the thickness of the resin layer of the resin-coated paper, but it is generally advantageous to extrude coat it to a thickness of about 5 microns to 50 microns. In addition, in ordinary resin-coated paper in which both sides of the base paper are coated with resin, the resin surface containing titanium oxide pigment is
Depending on its use, it has a glossy surface, matte surface, silky surface, etc., and the opposite back side is usually a matte surface. can be processed. The base paper used in the practice of the present invention may be ordinary natural pulp paper, synthetic fiber, or so-called synthetic paper made from synthetic resin film.
Natural pulp paper based on wood pulp of softwood pulp, hardwood pulp, softwood hardwood mixed pulp is advantageously used. Further, 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 preferably 50 to 250 g/m ² . The base paper mainly composed of natural pulp, which is advantageously used in the practice of the present invention, can contain various polymer compound additives. For example, dry paper strength enhancers include cationized starch, cationized polyacrylamide, anionized polyacrylamide, carboxy-modified polyvinyl alcohol, gelatin, etc. Sizing agents include fatty acid salts, rosin derivatives, dialkyl ketene dimer emulsions, petroleum resin emulsions, etc. , ammonium salt of styrene-maleic anhydride copolymer alkyl ester, clay, kaolin, calcium carbonate,
Wet paper strength enhancers such as barium sulfate and titanium oxide; melamine resins, urea resins, and epoxidized polyamide resins; fixing agents such as polyvalent metal salts such as aluminum sulfate and aluminum chloride; and cationically modified polymers such as cationized starch. , PH regulators such as caustic soda, soda carbonate, and hydrochloric acid; inorganic electrolytes such as common salt and mirabilite; in addition, dyes, optical brighteners, latex, and the like may be contained in appropriate combinations. The photographic support in the present invention can be provided with various silver halide photographic emulsion layers. For example, silver chloride, silver bromide, silver chlorobromide, silver iodobromide, and silver chloroiodobromide emulsion layers can be provided. Furthermore, a multilayer silver halide photographic constituent layer can be provided by incorporating a color coupler in the silver halide photographic emulsion layer. As the binder for these silver halide emulsion layers, in addition to ordinary gelatin, hydrophilic polymeric substances such as polyvinylpyrrolidone, polyvinyl alcohol, and polysaccharide sulfate 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; antifoggants and stabilizers include hydroxy-triazolopyrimidine compounds and mercapto-heterocyclic compounds. Hardeners such as formalin, vinyl sulfone compounds, aziridine compounds, coating aids such as benzene sulfonate, sulfosuccinate salts, anti-staining agents, dialkylhydroquinone compounds, etc., development accelerators, etc. Hydroquinone, phenidone, etc., as ultraviolet absorbers, benzotriazole compounds, etc., as well as optical brighteners, sharpness-improving dyes, antistatic agents, PH regulators, and water-soluble iridium compounds and water-soluble iridium compounds during the production and dispersion of silver halide. Rhodium compounds and the like can be contained in appropriate combinations. Further, on the back side of the photographic support in the present invention, that is, on the support surface opposite to the side on which the photographic constituent layer, often the silver halide photographic constituent layer, is coated,
A coating layer consisting of a hydrophilic colloid layer called a back coat layer can be provided for the purpose of preventing curling, preventing static electricity, preventing adhesion, and preventing slipping. Such a back coat layer may contain a binder, a protective colloid, a curing agent, an antistatic agent, a surfactant, a matting agent, a latex, etc. Next, examples will be described in order to explain the present invention more specifically. Example 1 Hoster Palm Pink E50 part, Sunwax
50 parts of 171-P (molecular weight: about 1500, softening temperature: 105 DEG C.) were melt-kneaded in a heated kneader and further dispersed in a hot three-roll mill to obtain a fluke-like colored premix. In a Banbury mixer, low density polyethylene (density 0.92 g/cm ³ , MI=8), titanium oxide, zinc stearate, ultramarine blue and color premix were added in Table 1.
The amounts described in Note 1) were added and thoroughly kneaded at 150°C to obtain masterbatches containing pigments, etc. (No. 1 to No. 7). Separately, as a comparison masterbatch, instead of the colored premix, Hoster Palm Pink E.
The above master batch (hereinafter,
(sometimes abbreviated as MB) was obtained using the same procedure as MB. (No. 8). On the other hand, a mixed stock of 50 parts by weight of bleached hardwood kraft pulp and 50 parts by weight of bleached softwood sulfite pulp was prepared using Canadian Standard Freeness 310.
ml, and further added 3 parts by weight of cationized starch, 0.2 parts by weight of anionized polyacrylamide, 0.4 parts by weight of alkyl ketene dimer emulsion (as ketene dimer content), and 0.4 parts by weight of polyaminopolyamide epichlorohydrin resin per 100 parts by weight of pulp. A paper with a basis weight of 160 g/m ² was made.
The obtained wet paper was dried at 110°C, followed by 3 parts by weight of carboxy-modified polyvinyl alcohol, 0.05 parts by weight of a fluorescent whitener (Blancophor ZP, sold by Bayer Japan), and a blue dye (Diamir Turquoise B: Mitsubishi Kasei Co., Ltd.). Co., Ltd.), 0.2 parts by weight of citric acid, and 97 parts by weight of water.
After impregnating the paper with g/m ² and drying with hot air at 110° C. and calendering at a linear pressure of 90 kg/cm, both sides of the paper were subjected to corona discharge treatment to produce a base paper for photographic resin-coated paper. Next, apply high-density polyethylene (density
A 1:1 mixture of 0.96 g/cm ³ , MI=5) and low-density polyethylene (density 0.92 g/cm ³ , MI=5) was coated at a resin temperature of 330°C using a melt extrusion coating machine to a thickness of 30μ. Coated. Next, write Table 1 on the surface of the base paper.
After thoroughly mixing a resin composition consisting of 20 parts by weight of MB described in Note 1) and 80 parts by weight of low-density polyethylene for dilution (density 0.92 g/cm ² , MI=5), a screw type extruder with an extrusion opening diameter of 65 mm was used. Using a melt extruder with a 750mm wide T-die, the resin temperature was 320℃.
The resin-coated paper containing titanium oxide pigment, etc. was manufactured by coating the resin to a thickness of 30 μm. At that time, the surface resin layer containing titanium oxide pigment etc. was processed into a flat glossy surface, and the back resin layer was processed into a paper-like matte surface. The number of microgrits was determined by visually counting the number of microgrits generated on the resin surface containing titanium oxide pigment, etc. of the photographic support produced by the method described above. The results obtained are shown in Table 1.

【table】

[Table] Example 2 Quinacridone Magenta 10-90 parts and Sanwax 161-P (molecular weight approximately 5000, softening temperature 111°C) 90-90 parts
10 parts were combined as shown in Table 2, Note 3), melted and kneaded in a heated kneader, and further dispersed in a heated three-roll mill to obtain a flaky blue premix. Add low density polyethylene (density 0.92 g/cm ³ , MI = 5), titanium oxide, magnesium stearate, ultramarine blue and blue premix to a Banbury mixer in the amounts listed in Table 2, Note 2) and Note 3). ,
The mixture was thoroughly kneaded at 150°C to obtain MBs containing pigments, etc., respectively. After that, the resin layer composition on the surface of the base paper was changed to MB20.
Parts by weight, low density polyethylene for dilution (density 0.92
g/cm ² , MI=5) 50 parts by weight, and high-density polyethylene for dilution (density 0.96 g/cm ³ , MI=5) 30 parts by weight, except for melt extrusion coating. I went there by The results obtained are shown in Table 2.

[Table] From the results in Table 2, the weight ratio of Quinacridone Magenta to Sunwax 161-P was 3:7, 4:6,
MB was prepared by premixing 6:4 and 7:3 as a colored premix (No. 13 to No. 16)
It can be seen that the occurrence of microgrids is small in both cases. Furthermore, it can be seen that in the case of 4:6 and 6:4, the generation of micro grit is even smaller. On the other hand, those with a weight ratio of 1:9, 2:8, 8:2, and 9:1 (No. 11, 12, 17, and 18) generate a lot of microgrit and are unsuitable as photographic supports. I understand.

Claims (1)

[Claims] 1. In a method for manufacturing a resin-coated paper-type photographic support in which both sides of paper are coated with a film-forming resin, the same side of the paper as the side on which the image will be formed is hot-melt extruded. The resin composition to be coated by coating contains at least resin A, from 7% by weight based on the resin composition.
20% by weight titanium oxide pigment, from 0.025% by weight
0.5% by weight of an inorganic blue pigment, and 0.001% to 0.01% by weight of a quinacridone red pigment premixed in a low molecular weight thermoplastic resin B that has a lower softening temperature than the resin A and is solid at room temperature. A method for producing a photographic support, characterized in that: 2. The method for producing a photographic support according to claim 1, wherein the resin A is a polyolefin resin. 3. The method for producing a photographic support according to claim 2, wherein the polyolefin resin is polyethylene. 4. The method for producing a photographic support according to claim 1, 2, or 3, wherein resin B is low molecular weight polyethylene. 5 The molecular weight of low molecular weight polyethylene is from 1500
5000 and a softening temperature of 80°C to 115°C. 6. The method for producing a photographic support according to claim 5, wherein the weight ratio of the quinacridone red pigment to the low molecular weight polyethylene is from 3:7 to 7:3.