JPS634489B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing photographic polyolefin resin-coated paper in which a film-like polyolefin resin composition containing titanium oxide is melt-extruded coated on at least one side of a paper or synthetic paper substrate. , defects due to die lip stains that occur when polyolefin resin-coated paper for photography is manufactured by melt-extrusion coating a polyolefin resin composition containing titanium oxide in the form of a film on at least one side of a paper or synthetic paper substrate. The present invention relates to a method for preventing surface roughness. The essential structure of photographic polyolefin resin-coated paper is already known; for example, as disclosed in U.S. Pat. This is a method of containing titanium oxide, blue pigment, fluorescent whitening agent, etc. However, when melt-extruding a polyolefin resin composition containing titanium oxide, especially a polyethylene resin composition, into a film from a slit die, needle-shaped or icicle-shaped deposits or stains (hereinafter simply referred to as die lip) are formed on the tip of the die lip during short extrusion. Die lip stains (referred to as die lip stains) tend to occur, and unfortunately, these die lip stains tend to grow larger and larger as the melt extrusion time progresses. If this die lip stain occurs during melt extrusion coating, vertical streaks may appear on the surface of photographic polyolefin resin coated paper manufactured as is, or streak-like unevenness may occur due to uneven coating amount. Sometimes, dirt adheres to the film and it is coated, causing foreign matter to appear. As a result, the surface quality of the produced polyolefin resin-coated paper is significantly impaired, making it unsuitable as a photographic support that requires excellent surface quality, and having no commercial value. Additionally, the only way to completely remove die lip stains that have occurred is to stop production and clean the die lip, which requires a great deal of effort and time and results in a significant drop in productivity. Therefore, an urgent solution was required. As a result of various studies conducted by the present inventors on preventing the generation of die lip stains, it has been found that although the mechanism of generation thereof is not well understood, there are two basic contradictions. The first is the slit die L/D.
(Here, L is the length of the die land of the slit die,
If the value (D is the slit opening diameter) is small, the surface quality will be poor, which is basically considered to be due to unevenness in melt extrusion, and a polyolefin-coated paper with good surface quality cannot be obtained, but there is little tendency for die lip stains to occur. On the other hand, if the L/D value of the slit die is large, polyolefin-coated paper with basically good surface quality can be obtained, but
It was found that the occurrence of die lip stains was significant.
Second, when the content of titanium oxide in polyolefin resin is low, die lip stains occur less;
It was found that the hiding power was so low that it could not be used as a photographic support, whereas when the content of titanium oxide was high, the hiding power was sufficient, but the generation of die lip stains was significant. Therefore, the object of the present invention is to overcome these two basic contradictions and to provide a resin layer with a good surface quality, which has no or significantly suppressed tendency to generate die lip stains, contains titanium oxide at a certain concentration or more in the resin layer. An object of the present invention is to provide a method for manufacturing a photographic polyolefin resin-coated paper. As a result of intensive research by the present inventors, the object of the present invention is to provide a photographic polyolefin in which a polyolefin resin composition containing titanium oxide is melt-extruded onto at least one side of a paper or synthetic paper substrate in the form of a film. In producing resin-coated paper, 0.01 to 5% by weight of a metal salt of a higher fatty acid is added to a polyolefin resin composition containing titanium oxide, and the titanium oxide is oxidized at 110°C for 2 hours. Use titanium oxide whose drying loss is 0.35% by weight or less based on the titanium oxide before drying, and whose L/D (where L is the length of the die land of the slit die and D is the slit opening diameter) value is 15 or more. It has been found that this can be achieved by melt extrusion coating using a melt extruder with a slit die. Simply adding a fatty acid metal salt to a polyolefin resin composition or using the specific titanium oxide in the present invention has little effect on preventing staining from Dairi Lip, but adding a fatty acid metal salt to a polyolefin resin composition and using the specific titanium oxide in the present invention By combining the use of titanium oxide, the die lip stain prevention effect is well exhibited, and this is thought to be due to their mutual mutual effects. Examples of the metal salts of fatty acids in the present invention include zinc stearate, calcium stearate, aluminum stearate, magnesium stearate, zirconium octylate, sodium palmitate, calcium palmitate, and sodium laurate. The amount added is based on the polyolefin resin composition containing titanium oxide.
If it is less than 0.01% by weight, the effect of preventing die lip staining will be low, and if it is more than 5% by weight, the resin composition will become slippery, making melt extrusion difficult. As the titanium oxide in the present invention, either rutile type or anatase type can be used as long as the loss on drying of titanium oxide at 110°C for 2 hours is 0.35% by weight or less based on the titanium oxide before drying. can. However, most commercially available titanium oxides have their particle surfaces modified by precipitating hydrated aluminum oxide and/or hydrated silicon dioxide (hereinafter simply referred to as alumina or/and silica surface treatment). Most of the alumina and/or titanium oxide surface-treated with silica have a loss on drying of 0.35% by weight or more in the present invention and cannot be used. On the other hand, titanium oxide useful in the present invention includes:
Preferably wet-classified, well-dried titanium oxide with no surface treatment and a loss on drying of 0.35% by weight or less, more preferably titanium oxide without the above inorganic treatment, silanol surface treatment, zinc stearate,
After organic treatment such as surface treatment with fatty acid metal salts such as calcium stearate, it is well dried to reduce drying loss.
Titanium oxide of 0.35% by weight or less is preferred. Also,
Even if titanium oxide is surface-treated with alumina and/or silica, for example, 350°C
If it is forcibly dehydrated and dried at a high temperature above and the loss on drying as defined in the present invention is 0.35% by weight or less,
Useful for the present invention. In addition, if the content of titanium oxide in the polyolefin resin is less than 5% by weight based on the polyolefin resin composition, the hiding power will be insufficient as a photographic support, while if it is more than 40% by weight, the fluidity will deteriorate. It is not preferable because the amount decreases, and particularly preferably it is in the range of 9% by weight to 25% by weight. As the polyolefin in the present invention, low-density polyethylene, high-density polyethylene, and polypropylene having various densities and melt viscosity indexes (hereinafter simply referred to as MI) can be used singly or in combination. In addition to titanium oxide and fatty acid metal salts, the polyolefin resin composition of the present invention further contains white pigments such as zinc oxide, talc, and calcium carbonate, fatty acid amides such as stearic acid amide and arachidic acid amide, and tetrakis [ Methylene-3
(3,5-di-tert-butyl-4-hydroxy-
Phenyl)propionate]methane, antioxidants such as 2,6-di-tert-butyl-4-methylphenol, coloring pigments such as ultramarine blue and pengara, and fluorescent whitening agents may be added. The polyolefin resin coated paper in the present invention is
It is usually manufactured by melt-extruding a polyolefin resin composition onto a paper or synthetic paper substrate (hereinafter simply referred to as base paper) that runs 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
Flat dies such as type dies, L-type dies, and fishtail dies are preferred, and the slit opening diameter is preferably 0.1 to 1 mm. In addition, before coating the resin composition on the base paper, the base paper is subjected to corona discharge treatment.
It is preferable to perform an activation treatment such as 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 polyolefin resin-coated paper in which both sides of the base paper are coated with resin, the resin surface containing titanium oxide (emulsion coated surface) can be glossy, matte, or silky depending on the application. The back surface is usually a matte surface, and the front surface or both the front and back surfaces can be subjected to activation treatment such as corona discharge treatment or flame treatment if necessary. 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 g/m ² to 250 g/m ² . 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, 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, etc.
Pigments include clay, kaolin, calcium carbonate, barium sulfate, titanium oxide, etc. Wet paper strength agents include melamine resin, urea resin, epoxidized polyamide resin, etc. Fixing agents include polyvalent metals such as aluminum sulfate and aluminum chloride. PH such as salts, cationic polymers such as cationized starches,
As regulators, caustic soda, soda carbonate, hydrochloric acid, etc., as inorganic electrolytes, salt, mirabilite, etc. In addition, dyes, fluorescent brighteners, latex, etc. can be contained in appropriate combinations. The photographic polyolefin-coated paper according to 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 and sulfuric ester compounds of polyvinyl alcohol polysaccharides can be used. Further, the above-mentioned silver halide emulsion layer can contain various additives. For example, as a sensitizing dye, cyanine dye, merocyanine dye, etc., as a chemical sensitizer,
Antifoggants or stabilizers such as water-soluble gold compounds and sulfur compounds; hydroxy-triazolopyrimidine compounds and mercapto-heterocyclic compounds; hardeners; coating aids such as formalin, vinyl sulfone compounds, and aziridine compounds; as benzene sulfonate, sulfosuccinic acid ester salt, etc., as anti-staining agent, as dialkylhydroquinone compound, as ultraviolet absorber, as benzotriazole compound, etc. In addition, fluorescent whitening agent, sharpness improving dye, antistatic agent, In addition to the PH regulator, water-soluble iridium, rhodium compounds, and the like can be contained in appropriate combinations during the production and dispersion of silver halide. Next, in order to explain the present invention more specifically,
An example will be described. Example 1 Low density polyethylene (MI=7, density 0.923) 70
Parts by weight, 30 parts by weight of titanium oxide, and fatty acid metal salts were thoroughly kneaded at 150° C. using a Banbury mixer in the combinations shown in Table 1 to obtain a titanium oxide masterbatch. 33 parts by weight of the titanium oxide masterbatch thus obtained and 37 parts by weight of low density polyethylene (MI = 5, density 0.918) and 30 parts by weight of high density polyethylene (MI = 5, density 0.968) as diluent resins were mixed in a dry process. Mix and apply to photographic base paper with a basis weight of 160 g/m ² using a melt extruder at a coating speed of 100 m/min and a melting temperature.
Melt extrusion coating was carried out at 320° C. to a coating weight of 30 g/m ² using the combinations of L/D values according to the present invention shown in Table 2. This melt extruder has a screw type extruder with an extrusion opening diameter of 65 mm and a T-die with a width of 750 mm, and the T-die portion can be replaced with a T-die having a different L/D value. In addition, the cast cooling roll had a smooth flat surface and was treated with hard chrome plating. Table 2 shows the number of die lip stains in each sample one hour after the start of melt extrusion.

【table】

【table】

[Table] (Note 3) The term titanium oxide masterbatch has the same meaning as in Table 1.
According to Table 2, when the L/D value in the present invention is large, a polyolefin-coated paper with a good area can be obtained, but die lip stains occur significantly. Certain titanium oxides, i.e. 2 at 110℃
For the first time, by combining the use of titanium oxide whose drying loss is 0.35% by weight or less based on the titanium oxide before drying under certain conditions, the generation of die lip stains can be significantly suppressed, and titanium oxide It is clearly understood that it is possible to provide photographic polyolefin-coated paper with good surface quality, which contains this in the resin layer. on the other hand,
It can be clearly seen that when the L/D value is low, die lip stains are less likely to occur, but the surface quality of the polyolefin-coated paper is poor, making it unsuitable as a photographic support. Example 2 In the same manner as in Example 1, a masterbatch as shown in Table 3 below was prepared, and a sample having the composition shown in Table 3 was melt-extruded using a slit die having an L/D value of 50 as defined in the present invention. The coating was melt-extruded using a machine in the same manner as in Example 1. The results obtained are shown in Table 4.

【table】

【table】

[Table] Represents lyethylene.
According to Table 4, by combining the addition of a fatty acid metal salt to the polyolefin composition and the specific titanium oxide of the present invention, the generation of die lip stains can be significantly suppressed, and a high concentration of titanium oxide can be used. It is clearly seen that it is possible to provide photographic polyolefin-covered paper containing good surface quality in the resin layer. On the other hand, when the content of titanium oxide in the polyolefin resin was low, die lip stains were less likely to occur, but the hiding power was low and the resin was unsuitable as a photographic support.

Claims (1)

[Claims] 1. A polyolefin resin composition containing titanium oxide is applied to at least one surface of a paper or synthetic paper substrate L/D (where L is the length of the die land of the slit die, and D is the slit opening diameter of the slit die. ) When manufacturing photographic polyolefin resin-coated paper coated by melt extrusion into a film using a melt extruder having a slit die with a value of 15 or more, higher fatty acids are added to the polyolefin resin composition containing titanium oxide. 0.01 to 5% by weight of metal salt is added, and as the titanium oxide, 2% at 110℃ is added.
1. A method for producing photographic polyolefin resin-coated paper, the method comprising using titanium oxide whose loss on drying under certain conditions is 0.35% by weight or less. 2. The method for producing photographic polyolefin resin-coated paper according to claim 1, wherein the polyolefin resin is a polyethylene resin. 3. The method for producing photographic polyolefin resin-coated paper according to claims 1 and 2, wherein the content of titanium oxide is 5 to 25% by weight based on the polyolefin resin composition.