JP3238176B2 - Production method of photographic thermoplastic resin composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a thermoplastic resin composition for photography, and more particularly to a method for producing a thermoplastic resin composition for photography in which titanium dioxide is finely and uniformly dispersed. It is.

[0002]

2. Description of the Prior Art Photo-resin-coated paper is already known. For example, as disclosed in U.S. Pat. No. 3,501,298, both sides of a paper substrate are coated with a polyolefin resin, especially a polyethylene resin. It is known that the polyolefin resin on the emulsion coated side contains a titanium dioxide pigment, a coloring pigment, a fluorescent whitening agent and the like. Another type of photographic resin-coated paper is disclosed in JP-A-57-30830.
As disclosed in Japanese Patent Application Laid-Open Publication No. H10-264, a photographic resin-coated paper is known in which a paper substrate is coated with a resin composition containing a white pigment such as titanium dioxide polymerized and cured by electron beam irradiation.

[0003] Incidentally, titanium dioxide pigment is usually used as a pigment to be contained in the resin layer on the emulsion-coated side of a resin-coated paper as a photographic support. This is because the whiteness, hiding power, resolution, etc. are excellent.

Further, as a photographic thermoplastic resin composition used for photographic resin-coated paper, for example, JP-A-59-164
No. 550, the thermoplastic resin is a polyolefin resin, especially a polyethylene resin,
Further, there are known inorganic surface treating agents, particularly those containing a titanium dioxide pigment surface-treated with hydrous aluminum hydroxide or the like as a main component. And micro grit (micro gri
Photothermographic resin compositions with very low t) are also known. The micro grit referred to herein means, in a photographic resin-coated paper in which at least one surface of a paper or synthetic paper substrate is coated with a resin composition, fine foreign matter or fine particles appearing on the surface of the coated resin. .

[0005] The occurrence of microgrit on resin-coated paper as a photographic support causes serious photographic impairments.
For example, when a person is photographed on a photographic paper having a resin coated paper having microgrit as a photographic support, the appearance of microgrit loses its commercial value at all.

There are various causes of microgrit. For example, microgrit appearing on photographic resin-coated paper manufactured by melt-extrusion coating a photographic thermoplastic resin on at least one surface of a paper or synthetic paper substrate with a melt extruder. The causes of the grit are as follows: (1) When a large amount of gel is generated in the thermoplastic resin used (2) When the molten resin is extruded into a film from a melt extruder through a die, it cannot be maintained at an appropriate temperature and is not uniform (3) The screen attached to the breaker plate in the melt extruder is dirty. (4) The barrel liner in the melt extruder has cracks. However, these are often relatively easily resolved by skilled technicians.

However, the most difficult countermeasures against micro grit are cases in which micro grit is generated because the resin composition coated on the paper or synthetic paper base comprises at least a thermoplastic resin and a pigment. In a photographic resin-coated paper in which at least one surface of a paper or synthetic paper substrate is coated with a resin composition comprising at least a titanium dioxide pigment and a thermoplastic resin, coarse pigment particles remain undispersed. When the photographic resin-coated paper is manufactured using a master batch or a compound of such a titanium dioxide pigment, there is a tendency that microgrit caused by an undispersed substance of the titanium dioxide pigment tends to frequently occur on the resin surface. is there.

As a usual method of incorporating a pigment into a thermoplastic resin, preferably a polyolefin resin, a so-called masterbatch in which the pigment is contained in a high concentration in the resin is prepared in advance, and the resulting mixture is diluted with a diluting resin to a desired ratio. There are a method of diluting and mixing, and a method of preparing a so-called compound in which a pigment is initially contained in a resin in a desired composition ratio. These masterbatches or compounds are
It can be obtained using a batch kneader such as a Banbury mixer or a kneader, or a single-screw or twin-screw extruder.

In the case of producing using a Banbury mixer or a kneader, the effect of melt-kneading is high, but productivity is inferior due to a discontinuous batch process. In addition, when a normal single-screw or twin-screw extruder is used, relatively coarse pigment particles tend to remain undispersed in the thermoplastic resin, and thus the pigment not dispersed in the masterbatch or compound is dispersed. Particles will be present. Also,
A twin-screw extruder having a plurality of kneading disks is also a rule.

[0010]

In order to solve the above problems,
For example, in the production method disclosed in JP-A-64-46749, a high-dispersion and high-quality thermoplastic resin composition for photography is continuously used by using a twin-screw extruder in which a kneading disk is arranged. Is obtained. However, although a twin-screw extruder having a plurality of kneading disks can be manufactured continuously, there is a problem that relatively coarse pigment particles still exist in an undispersed state.

As described above, a production method that satisfies both productivity and product quality, that is, a product having a high melt-kneading effect like a Banbury mixer and having the same quality as a continuous extruder is continuously produced. There has been a demand for a manufacturing method capable of performing the above.

According to the present invention, there is provided a process for producing a photographic thermoplastic resin composition in which the use of a production method having a high melt-kneading effect and a high productivity does not cause or significantly suppresses the generation of coarse undispersed materials. The purpose is to provide.

[0013]

Means for Solving the Problems As a result of diligent studies of various kneading systems, the present inventors have found a method that not only can be dispersed efficiently and with high performance, but also can greatly reduce microgrit, and have led to the present invention. Things.

The present invention relates to a photographic thermoplastic resin composition comprising at least a polyolefin resin and a titanium dioxide pigment capable of obtaining a photographic thermoplastic resin composition having a resin pressure of less than 20 kg / cm ² as defined in the specification. In producing the product, a plurality of rotating disks and a fixed disk provided alternately between a feed portion and an outflow portion of the thermoplastic resin composition for photography, and at least the rotating disk and the fixed disk are provided. There is a pattern in which peaks and valleys are alternately radially formed on the surface facing the fixed disk.
And the patterns of the rotating disk and the fixed disk facing each other are the same.
The rotating disk and the fixed disk are arranged so that the porosity formed by the pattern decreases from the feed portion toward the outflow portion. By using a continuous kneading single-screw extruder provided with a mechanism for kneading with a disc, it is possible to produce a photographic thermoplastic resin composition with no or no significant generation of microgrit. It is possible.

Further, in the present invention, the continuous kneading single-screw extruder has a rotating disk with respect to a rotating shaft having a screw formed on an outer peripheral portion so as to rotate in a cylinder and transfer a fluid in the axial direction. Peaks and valleys are alternately radially formed on at least one surface of the rotating disk, and a fixed disk is fixed to the cylinder coaxially opposite to this surface, and the rotating shaft is Are arranged so that a gap is formed between them, and peaks and valleys are alternately radially formed on the surface of the fixed disk facing the rotating disk, and the fixed disk and the rotating disk are alternately formed. Fluid sent between the shaft and the outer periphery of the rotating disk and the inner surface of the cylinder is pushed out by the boundary between the two disks in the valley of the two disks and pushed out in the outer peripheral direction. Is configured.

Furthermore, the continuous kneading single screw extruder is
Crests and valleys are alternately radially formed on the other surface of the rotating disk, and a fixed disk similar to the fixed disk is disposed opposite to this surface, and between the two surfaces. Fluid from the outer periphery of the rotating disk is sent toward the center by the boundary between the peaks and valleys, and is pushed out from the gap between the rotating shaft and the fixed disk .

According to the method of the present invention, a photographic resin-coated paper in which at least one surface of a paper or synthetic paper substrate is coated with a resin composition comprising at least a titanium dioxide pigment and a thermoplastic resin is obtained. The concentration (% by weight) of the titanium dioxide pigment with respect to the thermoplastic resin in the resin composition, so-called masterbatch or compound, is about 5 to 80%, preferably 5 to 60%. Of course, if necessary at the time of kneading, a lubricant, a stabilizer, an antioxidant, a coloring agent and the like may be added.

[0018]

The present invention will be described in more detail. The resin used in the practice of the present invention is a resin film coated on a base paper.
Any resin that can be covered can be used, but polyolefin
Resin is used for extrusion coating and adhesion to base paper.
This is particularly advantageous in terms of goodness, cost, and the like.

The polyolefin resin in the present invention is:
Low-density polyethylene, high-density polyethylene, a homopolymer such as polypropylene, or a copolymer composed of two or more olefins such as an ethylene-propylene copolymer and a mixture thereof, and various density and melt viscosity index (melt index; (Hereinafter simply abbreviated as MI) can be used alone or as a mixture thereof.

The titanium dioxide pigment used in the practice of the present invention has a resin pressure defined below of 20 kg / cm ^2.
Any pigment may be used as long as it is a titanium dioxide pigment having a good dispersion such that a photographic thermoplastic resin composition of less than 10% can be obtained. That is,
Any of rutile type, anatase type, chlorine method and sulfuric acid method can be used.

The above resin pressure is defined as follows. First,
The titanium dioxide pigment is added to the thermoplastic resin using a usual melt kneader, for example, a Banbury mixer, and the mixture is sufficiently kneaded to obtain a master batch or a compound having a predetermined concentration (% by weight).

An extruder having four zones of heating control (this extruder has a barrel having an inner diameter of 20 mm and a length of 420 mm,
1 pitch 20mm, flight apex width 3.1mm, groove depth 3.9mm, 8 pitch feed zone, straight slope, 8
The screw comprises a pressure zone having a pitch, a groove depth of 1.6 mm and a metering zone having a pitch of 5, and a strand die having a breaker plate and a resin discharge port having a diameter of 3 mm and a length of 20 mm. )), The temperature of the extruder is set to 180 ° C., 180 ° C., 18 ° C. from the resin supply side.
Set to 0 ° C and 180 ° C. Then, when the temperature values of all four regions reached 180 ° C., the same thermoplastic resin used for the master batch or the compound manufactured previously was put into the resin supply port (hopper) on this extruder, and the screw was screwed. Extrusion at 100 rpm. Next, the temperature values of the four regions were set to 200 ° C.
Set to 50 ° C, 320 ° C, 320 ° C. When all of the temperature values in the four regions reached the set values, a stainless steel 100 mesh screen and a 325 mesh screen were sequentially attached to the prepared breaker plate, and the screw rotation speed of the extruder was lowered to the lowest value. The 325 mesh screen is mounted in the extruder with the screw facing. Thereafter, the screw rotation speed was reduced to 60 rpm.
And melt-extrude 500 g of the thermoplastic resin in the hopper. At this time, the resin pressure in the stable region is set to Akg / cm ² .

Next, a master batch or a compound having the above-mentioned predetermined concentration is added to a titanium dioxide pigment content of 75%.
It is collected so as to be 0 g, put into a hopper, and melt-extruded. At this time, almost all of the thermoplastic resin in the hopper is melt-extruded, then a master batch or a compound is added, and the thermoplastic resin is continuously melt-extruded. The value of the maximum resin pressure at the time when the master batch or the compound equivalent to 750 g as the titanium dioxide pigment content has passed through the outlet of the extruder is Bkg / c.
and m ^2. Here, (BA) kg / cm ² is defined as the resin pressure of the masterbatch or compound.

Titanium dioxide pigments are preferably those which have been surface-treated with an inorganic surface treating agent, in particular, hydrous aluminum hydroxide, and those which have been surface-treated by a conventionally known method are advantageously used. For example, a water-soluble aluminum salt and other water-soluble metal salts are added to a titanium dioxide slurry, and then a sparingly soluble oxide hydrate or the like is surface-treated on a titanium dioxide pigment by subsequently changing the pH in the slurry. Can be used.

The water-soluble aluminum salt includes, for example, sodium aluminate, and the surface of the titanium dioxide pigment can be treated with hydrous aluminum hydroxide by adding sulfuric acid or hydrochloric acid.

In addition to the aluminate, those which have been surface-treated with another inorganic surface treating agent or those which have been surface-treated with an inorganic surface treating agent other than the aluminate can also be used. In this case, those in which an inorganic surface treating agent other than the aluminate is added at any stage of the surface treatment can be used. In particular, when other inorganic surface treatment agents are used, those added at any stage before, during, or after the addition of the aluminate can be used. What is done is advantageous. As surface treatment agents other than aluminates used for these surface treatments, various compounds such as metal compounds such as zirconium, zinc and magnesium, and phosphorus compounds can be used in addition to silicon compounds and titanium compounds.

The photographic thermoplastic resin composition of the present invention may contain an aliphatic metal salt. Examples of fatty acid metal salts include zinc stearate, calcium stearate, and magnesium stearate. The amount of addition is 0.0 with respect to the resin composition.
A range of 1 to 5% by weight is desirable.

The photographic thermoplastic resin composition of the present invention may further contain, if necessary, white pigments such as zinc oxide, talc and calcium carbonate, fatty acid amides such as stearamide and arachidic amide, and antioxidants. Agents, coloring pigments such as cobalt blue and ultramarine blue, fluorescent whitening agents and the like may be added.

In the present invention, a continuous kneading single screw extruder ( hereinafter referred to as a single kneader extruder ) provided with a mechanism for kneading at least a mixture of a thermoplastic resin and a titanium dioxide pigment between a rotating disk and a fixed disk.
The thermoplastic resin composition is manufactured through at least one melt-kneading step using a continuous kneading extruder . The continuous kneading extruder is disclosed in JP-B-55-411.
No. 39, JP-B No. 54-24743 and "Plastic Age", June, 1982, p. 104.

This continuous kneading extruder has a cylinder provided with a heating means, and a rotating disk and a fixed disk which are arranged in the cylinder and are parallel to each other. Generally, in the kneading operation mechanism, the dispersion is completed by repeatedly performing the operations of “compression”, “shear”, and “replacement” in three directions in multiple directions. In a Banbury mixer having a relatively strong kneading action, the kneading effect is high, but the productivity is inferior due to the discontinuous batch type. Further, in the single-screw and twin-screw extruders, even if a portion provided with a kneader is provided, three functions and effects are inferior, and a large amount of micro grit is generated.

Therefore, the apparatus of the present invention is formed on the surface of each disk while passing material between a disk fixed to a shaft rotating in a cylinder and a fixed disk opposed to the disk. The compression, shear, and displacement actions are performed by the interaction between the peaks and the valleys, and the action is performed very efficiently because the area where the action is performed is effectively formed. The transfer of the material between the inner peripheral surface of the fixed disk and the outer peripheral surface of the rotating shaft, which is a problem at this time, is solved by providing the grooves and the screws opposite to each other.

[0032]

The apparatus used to obtain the thermoplastic resin composition for photography of the present invention will be described below with reference to the drawings. In the example of the continuous kneading extruder shown in FIG. 1, the continuous kneading extruder 22 is roughly composed of a feed screw 10, a kneading unit 12, a vent 14, a metering unit 16, an outflow unit 18, and a fixed-quantity feeder 20. A drive spindle 24 is disposed in the continuous kneading extruder 22, and an end (right end in the figure) of the drive spindle 24 is connected to a drive motor (not shown).
Note that a gear or the like is interposed between the drive spindle 24 and the drive motor as needed. A screw (not shown) for feeding the material is formed on the outer periphery of the drive spindle 24, and rotating disks 26, 26, 26,... Are fixed at regular intervals.
A screw is formed between the rotating disks 26, 26,.... The material is supplied from the fixed amount feeder 20, kneaded, and discharged from the outlet 18. Further, as shown in FIG. 2, the kneading section 12 includes respective rotating disks 26, 26,.
Are formed at the positions of the kneading portions, and fixed between the respective rotating disks 26, 26,... Opposed to the respective rotating disks 26, 26,. Disk 30,3
.. Are arranged.

Reference numeral 32 denotes fixed disks 30, 30,.
The temperature control pipe is a fixed disk 3
., The drive main shaft 24, and the like.
, The rotating discs 26, 26,..., And the temperature of the kneading extruder as well as the kneading extruder as well as the kneading unit 12 can be adjusted.

To use this continuous kneading extruder 22,
First, the drive main shaft 24 is rotated while maintaining the respective parts of the continuous kneading extruder 22 at a predetermined temperature. Therefore, the material is supplied from the fixed-quantity feeder 20. The supplied material is fed from the feed screw 10 to the kneading unit 12. In the kneading unit 12, a compressive force and a shear force are generated by the relative movement of the opposing surfaces of the rotating disk 26 and the fixed disk 30.

FIG. 3 shows an example of the fixed disk 30 and the rotating disk 26 used in the kneading section 12. In FIG.
(A) is a sector fixed disk, (B) is a sector rotating disk, (C)
Is a chrysanthemum-shaped fixed disc, (D) is a chrysanthemum-shaped rotating disc, (E) is a mortar-shaped fixed disc, and (F) is a mortar-shaped rotating disc. The porosity is a fan shape, a chrysanthemum shape, and a mortar shape in the descending order. When the resin material flows in a fan shape, a chrysanthemum shape, and a mortar shape, the internal pressure reaches a maximum at the mortar shape position. This is the compression action of this continuous kneading extruder. Also, the shearing action occurs at the point where the peaks of the rotating disk and the fixed disk meet. Then, the material in the valley receives the resistance of the rotation due to the rotation of the disk, and a high pressure is generated on the inclined surface. Then, it is sheared between the mountains and bites. The basic action of the dispersing operation is the displacement action, in which the material is displaced in the groove of each disc by the rotation of the disc.

Further, the conventional kneading extruder requires the kneading mechanism to be parallel to the axis, that is, on the outer periphery of the rotating body, but the continuous kneading extruder of the present invention is a mechanism capable of achieving the maximum kneading effect in a minimum space. have. That is, the maximum kneading effect can be exhibited by forming the kneading function between the discs having a plane intersecting the rotating main shaft at right angles. In this continuous kneading extruder, a powerful action is performed on the entire opposing surface of the rotating disc and the fixed disc, and the transfer of the material between the next discs is performed smoothly by forming grooves. Kneading is performed.

The number of rotating disks is plural. The shapes (patterns) and the number of steps of the peaks and valleys of the rotating disk and the fixed disk can be changed in type, and may be set according to the type and ratio of the combination. However, the opposite rotating disk and fixed disk
The patterns are the same. Further, it goes without saying that the above-described operation may be performed only on one side surface of the rotating disk. Depending on the material used, gas may be generated during processing. In this case, a gas vent may be formed at an appropriate position. Such a kneading method is not known at all as a method for producing a thermoplastic resin composition for photography, and a drastic reduction in microgrit is a breakthrough.

In the method of the present invention, a masterbatch or a compound of a resin composition containing about 5 to 80% by weight of a titanium dioxide pigment is adjusted using the continuous kneading extruder, and a resin is added to the mixture to prepare a pigment-containing composition. The rate may be adjusted to a predetermined ratio. At this time, since the continuous kneading extruder of the method of the present invention stably performs continuous operation, it is necessary to continuously and accurately supply raw materials. As such a supply device, a usual quantitative feeder can be used, and there are a screw type feeder, a table type feeder, a vibration type feeder and the like. When using these supply devices, there is a method of supplying a titanium dioxide pigment and a thermoplastic resin or the like in advance using a blender and a single feeder, but each material is supplied at a predetermined ratio using a plurality of feeders. It is also possible. At this time, in order to make the supply amount stable and accurate, these supply devices control the feeder so that the accumulated weight discharged from the weighing hopper from the start-up matches the set value in order to make the supply amount stable and accurate. It is effective to adopt a method or the like. When a plurality of feeders are used, a ratio control operation is also effective.

The photographic resin-coated paper containing the photographic thermoplastic resin composition in the resin layer according to the present invention is a titanium dioxide pigment which is heated and melted on a normally running paper or a synthetic paper base (hereinafter simply referred to as a base paper). Is produced by melt-extrusion coating a resin composition containing When the thermoplastic resin is a polyolefin resin, the melt extrusion temperature is preferably from 200 to 350 ° C.

Before applying the resin composition to the base paper,
Preferably, the base paper is subjected to an activation treatment such as a corona discharge treatment or a flame treatment. The thickness of the resin layer of the resin-coated paper is not particularly limited, but it is generally advantageous that the resin layer is extrusion-coated to a thickness of about 5 to 50 μm. Further, in a normal resin-coated paper in which both sides of the base paper are coated with a resin, the resin surface containing the titanium dioxide pigment has a glossy surface depending on its use,
It has a matte surface, a silk surface, etc., and the back surface on the opposite side is usually matte, and the front surface or both front and back surfaces are subjected to activation treatment such as corona discharge treatment, flame treatment, etc. and / or subbing treatment. be able to.

The base paper used in the practice of the present invention may be any of ordinary natural pulp paper, synthetic fiber, and so-called synthetic paper in which synthetic resin film is simulated paper, but may be softwood pulp, hardwood pulp, or softwood pulp mixed pulp. Natural pulp paper containing wood pulp as a main component is preferably used.
Although there is no particular limitation on the thickness of the base paper, the base paper has good surface smoothness, and preferably has a basis weight of 50 g / m2.
What is ² to 250 g / m ² is preferred.

The base paper mainly composed of natural pulp suitably used in the practice of the present invention can contain various polymer compounds and additives. For example, cationized starch, cationized polyacrylamide, anionized polyacrylamide, gelatin and the like can be contained as a dry paper strength enhancer. As sizing agents, fatty acid salts, rosin derivatives, dialkyl ketene dimer emulsion,
It can contain a petroleum resin emulsion and the like. Clay, kaolin, calcium carbonate, titanium oxide and the like can be contained as pigments. A melamine resin, a urea resin, or an epoxidized polyamide resin can be contained as a wet paper strength enhancer. As a fixing agent, polyvalent metal salts such as aluminum sulfate and aluminum chloride, and cation-modified polymers such as cationized starch can be contained. As a pH adjuster, caustic soda, sodium carbonate, hydrochloric acid, and the like can be added. As an inorganic electrolyte, salt or the like can be contained. Further, other dyes, optical brighteners, latexes and the like and the above-mentioned additives can be combined and contained.

Various silver halide photographic emulsion layers can be provided on the photographic resin-coated paper containing the photographic thermoplastic resin composition in the resin layer in the present invention. For example,
Silver chloride, silver bromide, silver chlorobromide, silver iodobromide and the like can be provided. Further, a multilayer silver halide photographic component layer can be provided by incorporating a color coupler into the silver halide photographic emulsion layer. As a binder for these silver halide emulsion layers, hydrophilic polymers such as polyvinylpyrrolidone, polyvinyl alcohol and polysaccharide sulfate compounds can be used in addition to ordinary gelatin.

The silver halide emulsion layer may contain various additives. For example, as sensitizing dyes, cyanine dyes, merocyanine dyes, etc., as chemical sensitizers, water-soluble gold compounds, sulfur compounds, etc., as antifoggants or stabilizers, hydroxy-triazolopyrimidine compounds, mercapto-heterocyclic compounds, etc. ,
As hardeners, formalin, vinyl sulfone compounds,
Aziridine compounds, etc., as coating aids, benzenesulfonate, sulfosuccinate salts, etc., as a stain inhibitor, dialkyl hydroquinone compounds, etc., as a development accelerator, hydroquinone, phenidone, etc., as an ultraviolet absorber, benzotriazole compounds, etc. In addition, fluorescent brightener, sharpness improving dye, antistatic agent, PH
A water-soluble iridium compound, a water-soluble rhodium compound, and the like can be incorporated in combination when forming and dispersing a silver halide.

Further, on the back side of the photographic resin-coated paper containing the photographic thermoplastic resin composition in the resin layer of the present invention, that is, the surface on which the photographic constituent layers, mostly silver halide photographic constituent layers, are coated. On the opposite side of the support surface, curl prevention,
A coating layer composed of a hydrophilic colloid layer called a back coat layer can be disposed for the purpose of preventing static charge, preventing adhesion, preventing slip, and the like. Such a back coat layer may contain a binder or a protective colloid, a curing agent, an antistatic agent, a surfactant, a matting agent, a latex, and the like.

Example 1 A titanium dioxide slurry (rutile type titanium dioxide powder “Super Titania G” (average particle size: 0.2 μm) manufactured by Showa Titanium Co., Ltd.) was prepared, and this titanium dioxide was used as an alumina. 0.8
An amount of aqueous sodium aluminate solution corresponding to% by weight was added. Thereafter, since the slurry exhibited an alkaline reaction, the pH was adjusted by adding dilute sulfuric acid, and the titanium dioxide powder was surface-treated with hydrous aluminum hydroxide.

The slurry thus surface-treated with hydrous aluminum oxide is filtered and washed with a filter press,
Subsequently, drying and crushing were performed to obtain a titanium dioxide pigment. 50 parts by weight of the titanium dioxide pigment thus obtained, 50 parts by weight of low-density polyethylene ("Showrex L-170" manufactured by Showa Denko KK), and 2 parts by weight of zinc stearate were mixed for 5 minutes using a Henschel mixer. Dry mixed.

The dry mixture was quantitatively supplied to a continuous kneading extruder by a screw type quantitative feeder to produce a master batch. As the continuous kneading extruder, the screw diameter of the feed section is 80 mmφ, and the screw diameter of the metering section is 3 mm.
5mmφ, 6 sets of kneading units (6 rotating disks), 98.5mmφ of rotating disks, 101.5mmφ inner diameter of kneading unit cylinder
It was used. Extrusion rate is 15kg / h, rotation speed is 70rpm
m, the kneading temperature was 110 ° C. in the kneading section and 150 ° C. in the latter half of the die section to obtain a master batch.

Further, the rotating disk of the kneading section is formed from the feed section in the form of a sector, a sector, a chrysanthemum, a chrysanthemum, a chrysanthemum, a chrysanthemum, a mortar, a mortar, a mortar, and a mortar. The rotating disk of the vent screw was attached. The fixed disk facing the rotating disk was a fixed disk having the same pattern as the rotating disk.

On the other hand, a mixed stock of 50 parts by weight of hardwood bleached kraft pulp and 50 parts by weight of softwood bleached sulphite pulp was mixed with Canadian Standard Freeness 310 m
and 3 parts by weight of cationized starch and 0.2 parts of anionic polyacrylamide per 100 parts by weight of pulp.
Parts by weight, 0.4 parts by weight of an alkyl ketene dimer emulsion (as a ketene dimer component) and 0.4 parts by weight of a polyaminopolyamide epichlorohydrin resin were added.
g / m ² paper was made.

The obtained wet paper was dried at 110 ° C., and subsequently 3 parts by weight of carboxy-modified polyvinyl alcohol, 0.05 parts by weight of fluorescent whitening agent, 0.002 parts by weight of blue dye, 0.2 parts by weight of citric acid and 2 parts of impregnating liquid consisting of 97 parts by weight of water
It was impregnated with 5 g / m ² , dried with hot air at 110 ° C., and further subjected to a super calendar treatment at a linear pressure of 90 kg / cm to produce a resin-coated paper base paper for photography.

Next, after the back surface of the base paper was subjected to corona discharge treatment, high density polyethylene (density 0.96 g / cm ² , MI
= 5) and low density polyethylene (density 0.92 g / cm ² ,
A 1: 1 mixture of MI = 5) was coated at a resin temperature of 320 ° C. to a thickness of 30 μm using a melt extrusion coater. Next, after subjecting the surface of the base paper to corona discharge treatment, the titanium dioxide pigment comprises 30 parts by weight of a master batch, 30 parts by weight of high density polyethylene (MI = 5) and 40 parts by weight of low density polyethylene (MI = 5). The blended resin composition was coated at a resin temperature of 320 ° C. to a thickness of 30 μm to produce a polyethylene resin-coated paper containing a titanium dioxide pigment. At that time, the surface of the polyethylene containing the titanium dioxide pigment was processed into a completely flat glossy surface, and the surface quality of the back polyethylene was processed into a matte surface such as paper.

The number of microgrids appearing on the surface of the polyethylene resin-coated paper containing the photographic thermoplastic resin composition thus obtained was visually counted. Table 1 shows the obtained results.

Example 2 The same operation as in Example 1 was performed except that the number of kneading units of the continuous kneading extruder was four. That is,
From the feed part, a rotating disk of chrysanthemum-chrysanthemum, chrysanthemum-mortar, mortar-mortar, mortar-vent screw was attached. The fixed disk facing the rotating disk was a fixed disk having the same pattern as the rotating disk. Table 1 shows the obtained results.

Example 3 A continuous kneading extruder has 6 kneading units, an extruding rate of 10 kg / h, and a rotation speed of 50 rpm.
The same operation as in Example 1 was performed except that the above operation was performed. Table 1 shows the obtained results.

Example 4 A continuous kneading extruder had 6 kneading units, an extrusion rate of 20 kg / h, and a rotation speed of 95 rpm.
The same operation as in Example 1 was performed except that the above operation was performed. Table 1 shows the obtained results.

Example 5 The kneading temperature of the continuous kneading extruder was 150 ° C. in the kneading section and 180 ° C. in the latter half of the die section.
The same operation as in Example 1 was performed except that the vehicle was operated. Table 1 shows the obtained results.

Example 6 The same operation as in Example 1 was performed except that the raw material was supplied to the continuous kneading extruder quantitatively by two feeders for resin pellets and other powders. . Table 1 shows the obtained results.

(Comparative Example 1) A dry mixture mainly composed of the same titanium dioxide pigment and low-density polyethylene as in Example 1 was kneaded using a Banbury mixer. Kneading time is 10 minutes, kneading temperature is 150 ° C
And a master batch was obtained. Others are the same as the first embodiment. Table 1 shows the obtained results.

(Comparative Example 2) A masterbatch was obtained by using a twin-screw extruder from the same dry mixture mainly composed of the titanium dioxide pigment and low-density polyethylene as in Example 1. The twin-screw extruder used here is L / D
= 30, and an extruder having a screw diameter of 40 mmφ further has two kinds of kneading disks in the middle of the screw.
On the supply side, three 3-lobe 1D kneading disks (lobe angle 90 °, segment type) are placed at 3/7 of the screw length, and on the outlet side, three lobes are used.
9 kneading disks of 0.25D (lobe angle 3
(0 degree, segment method) was mounted at a position 5/5 of the screw length. The extrusion rate is 30 kg / h and the rotation speed is 120
rpm, co-rotation, kneading temperature 110 in the first half
The master batch was obtained at 150 ° C. in the die section in the second half. Other results are shown in Table 1 in the same manner.

(Comparative Example 3) The twin-screw extruder used was the same as in Comparative Example 2, and only the extrusion temperature was 150 ° C in the first half and 180 ° C in the second half. Table 1 shows the obtained results.

[0062]

[Table 1]

From the results shown in Table 1, in the case of the thermoplastic resin composition containing the titanium dioxide pigment obtained without using the continuous kneading extruder of this example, a large amount of microgrit was generated on the resin surface. However, it is apparent that this is inferior to the thermoplastic resin composition containing the titanium dioxide pigment of this example.

[0064]

According to the present invention , at least the polyolefin resin of the present invention.
The method for producing a thermoplastic resin composition for photographic use comprising a titanium dioxide pigment and a titanium dioxide pigment has a mechanism for kneading between a rotating disk having a specific structure and a fixed disk , and a model of the rotating disk and the fixed disk facing each other.
In this method, the same continuous kneading single-screw extruder is used, and it is possible to continuously and effectively obtain a photographic thermoplastic resin composition having no so-called microgrit and causing no photographic trouble. .

[0065]

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of a continuous kneading extruder of the present embodiment.

FIG. 2 is a schematic sectional view of a kneading section of the present embodiment.

FIG. 3 is a plan view of each disk used in this embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Feed part screw 12 Kneading part 14 Vent part 22 Continuous kneading extruder 24 Drive spindle 26 Rotating disk 28 Kneading part cylinder 30 Fixed disk

 ──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Katsura Ito 1 Soka, Oji, Shiojiri-shi, Nagano Showa Denko KK Fine Powder Research Center (56) References JP-A-3-111842 (JP, A) JP-A-58- 98128 (JP, A) JP-A-59-164550 (JP, A) JP-A-64-46749 (JP, A) JP-A-61-129032 (JP, A) JP-B-54-24743 (JP, B2) JP-B-55-41139 (JP, B2) "Plastic Age" vol. 28, 1982, No. 6, dispersing mechanism of kneading apparatus and (KCK) continuous kneading extruder P104-109

Claims (3)

(57) [Claims] In producing a photographic thermoplastic resin composition comprising at least a polyolefin resin and a titanium dioxide pigment capable of obtaining a photographic thermoplastic resin composition having a resin pressure of less than 20 kg / cm ² as defined in the specification, A plurality of rotating disks and a fixed disk provided alternately between the feed portion and the outflow portion of the thermoplastic resin composition for photography, and at least the rotating disk and the fixed disk face each other. The surface of the rotating disk has a pattern in which peaks and valleys are alternately formed radially, and the pattern of the rotating disk and the fixed disk facing each other is the same.
The rotating disc and the fixed disc are arranged such that the porosity formed by the pattern decreases from the feed section toward the outflow section, whereby the rotating disc and the fixed disc are arranged. A method for producing a thermoplastic resin composition for photography, comprising using a continuous kneading single screw extruder provided with a mechanism for kneading with a plate. 2. The method for producing a thermoplastic resin composition for photography according to claim 1, wherein the continuous kneading single-screw extruder is provided with a screw at an outer peripheral portion thereof so as to rotate in a cylinder and transfer a fluid in the axial direction. A rotating disk is fixed to the formed rotating shaft at the center thereof, and peaks and valleys are alternately formed radially on at least one surface of the rotating disk, and coaxially opposed to this surface. A fixed disk is fixed to the cylinder and arranged so as to form a gap between the rotating shaft and the fixed disk.
Crests and valleys are alternately formed radially on the surface of the fixed disk facing the rotating disk, and the fluid fed through between the fixed disk and the rotating shaft is used for the two disks. Photographic thermoplastic resin composition characterized in that it is extruded in the outer peripheral direction by the boundary between the two discs in the valley of the disc, and is sent out between the outer peripheral portion of the rotating disc and the inner surface of the cylinder. The manufacturing method of things. 3. The method for producing a thermoplastic resin composition for photography according to claim 2, wherein the continuous kneading single screw extruder further has peaks and valleys alternately radially formed on the other surface of the rotating disk. In addition, a fixed disk similar to the fixed disk is disposed opposite to this surface, and between the two surfaces, fluid from the outer periphery of the rotating disk is separated by a boundary line between peaks and valleys of each other. A method for producing a thermoplastic resin composition for photography, wherein the thermoplastic resin composition is fed in a center direction and extruded from a gap between a rotating shaft and a fixed disk.