JP3484650B2 - Support for imaging materials - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a support for an image material which is excellent in rigidity and surface smoothness after resin coating.

[0002]

2. Description of the Related Art Usually, an image material is composed of a support for image material and an image forming layer provided on the support. For example, a silver halide photographic material, an ink jet recording material, a heat transfer type thermal transfer recording image receiving material, a heat sensitive recording material and a light and heat sensitive recording material are a silver halide photographic constituent layer, an ink image receiving layer, a heat receiving layer and a heat sensitive recording layer, respectively. An image forming layer such as a transfer type thermal transfer recording image-receiving layer, a thermosensitive color forming layer and a light and heat sensitive color forming layer, and if necessary an undercoat layer and a protective layer are coated.

Conventionally, a resin-coated paper type support having a base paper surface coated with a thermoplastic resin for a support for an image material is well known. Examples of the support for photographic materials for use in silver halide photographic materials include, for example, Japanese Patent Publication No. 55-1258.
Japanese Unexamined Patent Publication (Kokai) No. 4 discloses a technique for a support for photographic materials in which a base paper is coated with a resin capable of forming a film, preferably a polyolefin resin. US Patent 3,50
No. 1,298 discloses a technique for a support for photographic material in which both sides of a base paper are coated with a polyolefin resin. Since the application of the rapid photographic processing method for silver halide photographic materials, supports for photographic materials in which both sides of the base paper are coated with polyethylene resin have been mainly put into practical use for photographic paper. If necessary, the resin layer on the side on which one of the image forming layers is provided usually contains a titanium dioxide pigment in order to impart sharpness.

Further, US Pat. No. 4,774,224 discloses a resin-coated paper having a surface roughness of the resin coating of not more than a predetermined value, particularly a polyethylene resin coating in which the surface of a base paper is coated with a polyethylene resin. Thermal transfer recording image receiving elements having paper as a support have been proposed. Also, JP-A-63-30
Japanese Patent No. 7979 discloses a technique relating to an inkjet recording sheet having a resin-coated paper as a support.

However, a resin-coated paper-type support for image material, in which the surface of the base paper, especially the base paper mainly composed of natural pulp, on which the image forming layer is provided, is covered with a resin layer, is still serious. However, the actual situation is that satisfactory results have not yet been obtained.

The side of the base paper on which the image forming layer is provided (hereinafter, the side on which the image forming layer is provided is the front side, the resin layer coated on the front side is the front resin layer, the opposite side is the back side, and the resin layer coated on the back side is the back side). The backside resin layer (sometimes abbreviated as "reverse resin layer") is coated with a resin layer containing a thermoplastic resin, especially a polyethylene-based resin. Using a melt extrusion machine, the resin composition is cast in a film form from its slit die to be coated, pressure-bonded between a pressure roll and a cooling roll, and a series of steps of peeling from the roll after cooling. Manufactured. At that time, in the case of producing a resin-coated paper for image material for glossy, as a cooling roll, a cooling roll having a mirror surface or a glossy surface or a finely rough surface described in JP-B-62-19732 and having an extremely smooth surface. Is used. Thus, the surface resin layer of the resin-coated paper is pressed against a cooling roll having an extremely smooth surface in its molten state so that it is processed into a surface having a good smoothness. Therefore, the image material having the resin-coated paper as a support has an apparent appearance. It should be possible to obtain a smooth surface. However, it has not been possible to obtain an image material having an actually manufactured resin-coated paper as a support and having a sufficiently good smooth surface.

As is clear from the constituent elements of the image material support, the support is used by coating a base paper with a resin layer containing a resin capable of forming a film, for example, a polyolefin resin. The surface smoothness and rigidity, which are the above-mentioned problems, have been variously studied in terms of the properties of the resin to be used, the type, and the conditions of the coating layer provided on the base paper. Not done.

The support for image materials is required to have a high degree of smoothness that is incomparable to so-called general paper such as printing paper in terms of appearance and resolution of images. In the photographic printing paper support, which is a typical support for image materials, in order to prevent the processing solution from penetrating into the base paper layer and to enable rapid development processing, both sides of the base paper are made of polyolefin etc. The resin is used for coating. The printing paper that uses this type of support is different from the conventional baryta paper,
When drying after development, the smoothness of the support for photographic printing paper is directly reflected on the smoothness of the printing paper after development and drying, because the ferrotype treatment for transferring the mirror surface is not performed.

As described above, the support for image material coated with a polyolefin resin or the like is required to have a high degree of smoothness, but since the resin coats the surface of the base paper according to the unevenness of the surface of the base paper, the smoothness of the surface is suppressed. The property is strongly influenced by the smoothness of the base paper. For this reason, the base paper is required to have higher smoothness than the conventional baryta paper.

As a technique for improving the smoothness of the base paper, a technique relating to a support for photographic printing paper is well known and is disclosed in JP-A-58-68037 and JP-A-62-542.
As disclosed in Japanese Patent Publication No. 52-52, a method of adjusting the fiber length distribution of pulp used for base paper within a certain range, and as disclosed in Japanese Patent Publication No. 59-42295.
Methods are known for defining the optical properties of pulp.

Further, as disclosed in Japanese Patent Application Laid-Open No. 64-20541 and the like, a method of press-pressing a wet paper having a predetermined water content and a method described in Japanese Patent Application Laid-Open No. 64-59229 and the like. As described above, one side of the wet paper is brought into close contact with a heating mirror surface dryer to dry it, or JP-A-6-36
As disclosed in JP-A-4-59230, JP-A-2-203335, etc., various methods for calendering base paper have been attempted for the purpose of improving smoothness.

As described above, various attempts have been made for the purpose of improving the smoothness of the support in which both sides of the base paper are coated with a resin such as polyolefin. However, it is not possible to simultaneously improve both of the large irregularities mainly due to the factors of the papermaking process. Further, even if the smoothness of the base paper is improved, there is a problem that the smoothness as a support for an image material is not improved because the smoothness is changed in the post-process, and any of the methods is used. No support for an image material having extremely good smoothness has been obtained.

For example, a wet paper having a water content of 30 to 50% as disclosed in JP-A-64-20541, which is a surface smoothing method involving a press or a heating roll, is pressed tightly. According to the method and the method of calendering wet paper having a moisture content of 20 to 40% by weight as described in JP-A-3-120539, smooth base paper is obtained but smoothness after resin coating is obtained. It was insufficient. Further, the method of adhering one side of a wet paper to a heating mirror surface dryer to dry it as described in JP-A-64-59229 has a problem in that large irregularities cannot be smoothed.

[0014]

That is, an object of the present invention is to provide a support for an image material in which both sides of a base paper mainly composed of natural pulp are coated with a resin capable of forming a film. However, it is to provide a support for an image material excellent in rigidity after resin coating and smoothness of the surface by being subjected to a press treatment by a shoe press during a papermaking process.

[0015]

SUMMARY OF THE INVENTION With respect to the above-mentioned problems, the present inventors have been improving the smoothness of a base paper and a support for image material coated with a resin capable of forming a film, for example, a polyolefin resin, preferably a polyethylene resin. As a result of examination, it was found that the pressing method can have a great influence on the selection of raw pulp, the preparation and final calender conditions, and the base paper used as a support for image materials,
The above problems have been solved by applying a pressing process using a shoe press device capable of avoiding a high peak pressure with a long nip stay time.

1. The present invention is a support for image materials, wherein both sides of a base paper containing natural pulp as a main component are coated with a resin capable of forming a film, the base paper comprising at least one closed type paper during a papermaking process. It is an invention of a support for an image material, which is a base paper obtained by being subjected to a press treatment by a shoe press device.

2. Further, in the above-mentioned invention 1, the nip pressure of the shoe press is 1500 kN / m or less .

3. Further, in the invention 1 or 2, the wet paper moisture content at the shoe press inlet is 60 to 80%.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION The support for image material of the present invention will be described in detail below.

The inventors of the present invention have studied the improvement of the smoothness of the support for image material, and as a result, in the papermaking process, the base paper used for the support for image material is pressed by a shoe press machine to The present invention has been made by discovering that both relatively small unevenness where the contribution of the raw material is large and relatively large unevenness where the influence of factors of the papermaking process such as formation are large are improved at the same time.

Since the press device used to make the base paper of the image material support has a narrow nip width (20 to 50 mm) due to its structure, it is necessary to sufficiently perform the press treatment. However, it was necessary to extremely reduce the machine speed or increase the nip pressure applied to the base paper. However, when the nip pressure is increased, the pressure rapidly increases in a narrow nip width, and the high peak pressure easily causes the paper to be broken. Therefore, the total weight applied is limited.

On the other hand, in the shoe press, since the nip width can be made extremely wide as 200 to 310 mm by using the shoe, the nip stay time becomes long, and sufficient press treatment is performed while avoiding a high peak pressure for dehydration. Can be strengthened. In this way, when using a shoe press with high water squeezing efficiency, sufficient pressing is possible, so the water content at the press outlet of the paper is
It can be reduced by about 5%. Therefore, it is considered that not only the smoothness of the surface of the base paper but also the formation of interfiber bond is improved, and the rigidity and strength are improved.

The shoe press used in the production of the base paper for the support for image materials in the present invention may be an open type, but for example, "Paper and Pulp Technology Times: September 1996 Prospects for a new paper machine- The closed type as described in "Direction of next-generation machines seen from the latest trend of papermaking technology" is advantageously used. At this time, at least one shoe press may be provided, but two or more shoe presses may be installed. In the image material support of the present invention, particularly when quality with little difference between front and back sides is required, the shoe press device is composed of at least two units, and the first stage treatment and the second stage treatment, or after that, You may use what provided the multistage shoe press which arrange | positioned in combination so that the front surface of a base paper and the back surface could be processed uniformly, such as processing.

The nip pressure of the shoe press of the present invention varies depending on the type and beating degree of pulp, the speed of papermaking, the number of press stages, mechanical restrictions, etc., but is usually in the range of 1500 kN / m or less. Moisture content of wet paper at the shoe press entrance is 60
-80% is preferable. If it is 60% or less, the sufficient effect is not exhibited, and if it exceeds 80%, the smoothness tends to deteriorate. The moisture content of the wet paper in the present invention means J
It is a value calculated by the following formula based on ISP 8127. (Moisture content of wet paper,%) = (Mass content of wet paper / Weight of wet paper before drying) x 100

The pulp used in the present invention is NBK.
P, LBKP, NBSP, LBSP, various non-wood pulp, etc. are mentioned. As a beater for beating pulp,
Beaters usually used for beating pulp, such as beaters,
A conical refiner, a disc refiner, etc. can be used.

As the base paper used for the support for image material of the present invention, in addition to the natural pulp used in the present invention, mixed paper using synthetic fibers and the like are used.

The base paper of the support for image materials of the present invention may contain various additives when preparing a stock slurry. As a sizing agent, a fatty acid metal salt or fatty acid, an alkyl ketene dimer emulsion or an epoxidized higher fatty acid amide, an alkenyl or alkyl succinic anhydride emulsion, a rosin derivative, etc. described in Japanese Patent Publication No. 62-7534 or dried. As a paper strength enhancer, anionic, cationic or amphoteric polyacrylamide, polyvinyl alcohol, cationized starch, vegetable galactomannan, etc., as a wet paper strength enhancer, polyamine polyamide epichlorohydrin resin, etc., as a filler, clay, kaolin, Calcium carbonate,
Titanium oxide, etc., as a fixing agent, aluminum chloride, water-soluble aluminum salts such as vanadium sulfate, etc., as a pH adjusting agent, caustic soda, sodium carbonate, sulfuric acid, etc., and others, such as JP-A-63-204251 and JP-A-1-204251. 2665
It is advantageous to incorporate a coloring pigment, a coloring dye, a fluorescent whitening agent, etc. described or exemplified in JP-A-37, etc. in an appropriate combination.

The base paper of the image material support of the present invention may contain various water-soluble polymers, antistatic agents and additives by spraying, size press or tab size press. As water-soluble polymers, starch-based polymers, polyvinyl alcohol-based polymers, gelatin-based polymers, polyacrylamide-based polymers, cellulose-based polymers, etc. described or exemplified in JP-A-1-266537, sodium chloride, potassium chloride as antistatic agents Alkaline metal salts such as, alkaline earth metal salts such as calcium chloride and barium chloride, colloidal metal oxides such as colloidal silica, organic antistatic agents such as polystyrene sulfonate, etc. as emulsions and latexes, petroleum resin Emulsion, ethylene-vinyl acetate copolymer, JP-A-55
-4027, ethylene and acrylic acid (or methacrylic acid) described or exemplified in JP-A-1-180538.
Emulsion or latex of a copolymer having at least as a constituent, as a pigment, clay, kaolin, talc, barium sulfate, titanium oxide, etc., as a pH adjuster, hydrochloric acid, phosphoric acid, citric acid, caustic soda, etc.
In addition, it is advantageous that the above-mentioned coloring pigment, coloring dye, fluorescent brightening agent and the like are appropriately combined and contained.

Examples of the film-forming resin used for the support for image materials in the present invention include various polyethylene, polypropylene, polybutylene, polyethylene terephthalate and their copolymers, homopolymers such as polybutene and polypentene, and the like. Examples thereof include copolymers composed of two or more α-olefins such as ethylene-butylene copolymers, and the like, alone or in combination.

A polyolefin resin is preferably used as the resin capable of forming a film in the present invention. A polyethylene resin is particularly preferred, and a low density polyethylene resin is most preferred.

Examples of the resin contained in the polyolefin resin composition containing titanium dioxide in the present invention include the above various resins capable of forming a film.

Titanium dioxide is contained in the polyolefin resin layer, but rutile type or anatase type is used, and surface treated products with alumina or silica and organic substances such as fatty acid metal salts can be preferably used. Generally, titanium dioxide is added to the polyolefin resin layer in an amount of 5 to 30.
Contains by weight%.

In the polyolefin resin composition,
Various additives can be contained. For example, as white pigments, in addition to rutile-type or anatase-type titanium dioxide, zinc oxide, talc, etc., as release agents, fatty acid amides such as stearic acid amide and arachidic acid amide, fatty acids such as zinc stearate and magnesium stearate. Metal salts, organosilicon compounds such as polyorganosiloxane, antioxidants, hindered phenol compounds, etc., color pigments, cobalt blue,
A brightening agent such as ultramarine can be appropriately contained.

The polyolefin resin layer in the present invention is
It is manufactured by melt extrusion coating a polyolefin resin composition into a film from a slit die. The melt extrusion temperature at that time is appropriately selected in the range of 200 to 350 ° C. depending on the polyolefin resin composition. As a slit die, T
A die, an L die, a fish-til type die and the like are preferably used. Before applying the resin composition to the base paper, it is preferable to subject the base paper to an activation treatment such as corona discharge or flame treatment. The thickness of the polyolefin resin layer is not particularly limited,
It is generally about 10 to 50 μm.

In the present invention, generally, immediately after the polyolefin resin composition is applied to the base paper by melt extrusion, the surface of the base paper is 5
9.8 to 4 between the cooling roll and the pressure roll at about 25 ° C
The resin surface is cooled by adhering the resin surface to the surface of the chill roll by passing it under a pressure of about 9 kN / m to improve the smoothness of the resin layer surface and the adhesion between the resin layer and the base paper.

The backing layer for image materials of the present invention may be provided with various back coat layers for the purpose of preventing electrification and curling. As the material of the back coat layer, colloidal silica, colloidal synthetic hectorite, sodium chloride, polystyrene sulfonate, hydrophilic binder, latex polymer, pigment, surfactant and the like can be used.

[0037]

EXAMPLES Hereinafter, the present invention will be described in detail with reference to Examples. The present invention is not limited to the examples. All parts and% in the following are by weight.

Example 1 and Example 2 A double disc refiner with a freeness of 300 ml and cs
0.3 parts of anionic polyacrylamide (Stargum A15, manufactured by Seikou Kagaku) to 100 parts of mixed pulp having a weight ratio of LBKP beaten to f of 380 ml and NBSP beaten to csf of 6: 4, cation. Starch (C
2.0 parts of ATO F, manufactured by NSC Japan, and alkyl ketene dimer sizing agent (AS263, PMC Japan)
0.4 parts) and polyamide-polyamine-epichlorohydrin resin (WS525, manufactured by Japan PMC Co.).
Using a stock with 3 parts added, use a Fourdrinier paper machine to produce paper at a speed of 30
A base paper having a basis weight of 170 g / m ² was produced at 0 m / min (Example 1) or at a machine speed of 500 m / min (Example 2).

In this paper machine, a closed shoe press (shoe width 275 mm) is installed in the second press. The press treatment conditions after the second press were the press conditions shown in Table 1. At this time, the wet paper moisture content at the press entrance was 65%. The press impulse in the table is a value calculated by the following mathematical formula 1 and is an index of the degree of press processing.

[0040]

[Formula 1] PI = ΣP / V × 60 PI: Press impulse (kPa · sec) ΣN: Total press nip pressure after the 2nd press (kN /
m) V: Machine speed (m / min)

After the press treatment, the paper after drying with a multi-cylinder dryer is size press-treated with a 3% aqueous solution of polyvinyl alcohol, and then the density is 1.0 with a super calender.
Smoothing treatment was performed so as to obtain 1 g / cm ³ . After that, low-density polyethylene containing 10% titanium dioxide was used for the front surface of the base paper, and low-density polyethylene was used for the back surface with 32
Extrusion coating was carried out at a resin temperature of 320 ° C. to a thickness of μm to obtain a support for image materials. At this time, the surface of the resin layer containing the titanium dioxide pigment of the image material support is a mirror surface,
The surface quality of the back resin layer was processed into a matte surface such as paper. These samples were designated as Example 1 and Example 2.

Comparative Example 1 and Comparative Example 2 In Example 1, a normal roll press was used for the No. 2 press and the No. 3 press instead of the shoe press (Comparative Example 1), or the normal roll press was No. 2. Used in press, No. 3 press and No. 4 press (Comparative Example 2), Table 1
A support for an image material was obtained in the same manner as in Example 1 and Example 2, except that the press conditions were used. This sample was designated as Comparative Example 1 and Comparative Example 2.

Examples 3 to 7 Samples of Examples 3 to 7 were obtained under the same press conditions and working conditions as in Example 1 except that the water content at the press inlet was changed as shown in Table 2 by the No. 1 press. It was

For each sample thus obtained,
The results measured by the following test methods are shown in Tables 1 and 2.

<Rigidity> The rigidity was determined in accordance with the stiffness test method of the Taber stiffness tester of JIS P 8125 for the support for image material coated with resin. <Smoothness of Surface> The smoothness of the surface is the result of visual evaluation of a standard sample performed on a support for an image material coated with a resin. The one with the best smoothness was rated A, and the one with the poorest smoothness was rated D. The support for image materials having excellent surface smoothness requires C or higher (A, B, C), preferably B or higher.

[0046]

[Table 1] 1) SP indicates a shoe press. 2) RP indicates a roll press. 3) -indicates that the press is not used.

[0047]

[Table 2]

<Evaluation> From the results of Tables 1 and 2, the following can be understood.

Table 1 shows that the wet paper moisture content at the shoe press inlet is 65% and the press impulses are 60 and 9 respectively.
At 6 kPa · sec, the base paper of the support for image material was made into paper, and the support for image material obtained as described above was used as Example 1 and Example 2, respectively. The result of having tested the smoothness of No. 3 is shown. A comparative example was prepared in the same manner as in Examples 1 and 2, except that a normal roll press was used instead of the shoe press to press at 60 and 90 kPa · sec. 1 and Comparative Example 2
And From the results shown in Table 1, Example 1 had good surface smoothness, and particularly excellent rigidity. Further, in Example 2, the rigidity was good, and particularly excellent results were obtained in the smoothness of the surface. On the other hand, in Comparative Example 1 in which a normal roll press was used, the rigidity was relatively good, but the surface smoothness was remarkably inferior. Further, in Comparative Example 2, although the surface smoothness was in the practical range, the rigidity was remarkably inferior.

Table 2 shows that the second press is a shoe press, the press impulse is set to 60 kPa · sec, the wet paper moisture at the inlet of the shoe press is changed, and the base paper of the support for the image material is made into paper. The images obtained by obtaining the support for image material as described above are referred to as Examples 3 to 7, and the results of testing the rigidity and surface smoothness of this sample are shown. From the results of Table 2, all of Examples 3 to 7, the rigidity and the surface smoothness are in the level of the practical range or more, and among them, Examples 4 to 6 are excellent, and in particular, Example 5 has both characteristics. In, extremely excellent results were obtained.

Example 8 and Comparative Example 3 An ink jet recording material was prepared by coating a predetermined ink image-receiving layer on the image material support used in Example 2 and Comparative Example 2 to prepare a predetermined ink jet recording apparatus. Printed by. As a result, the ink jet recording paper (Example 8 corresponding to the support) having the support for image material (of Example 2) in the present invention has good rigidity, and particularly, the surface smoothness is extremely high. On the other hand, an ink jet recording paper having a good support for image materials (comparative example 2) other than the present invention (comparative example 3 corresponding to the support) was used.
Had a problem that the surface smoothness was inferior and the rigidity was particularly inferior.

Example 9 and Comparative Example 4 A heat transfer type thermal transfer recording image receiving material was prepared by coating a predetermined heat transfer type thermal transfer recording image receiving layer on the image material support used in Example 2 and Comparative Example 2. It was prepared and printed by a predetermined heat transfer type thermal transfer recording device. As a result, the heat transfer type thermal transfer recording image-receiving paper (Example 9 corresponding to the support) having the support for image material (the one of Example 2) in the present invention has good rigidity, especially the surface. Although the smoothness was extremely good, on the other hand, a heat transfer type thermal transfer recording image-receiving paper (Comparative Example 4 corresponding to the support) having a support for image material (comparative example 2) other than the present invention was used. ), The surface was inferior in smoothness, and especially the rigidity was inferior, and there was a problem.

[0053]

EFFECT OF THE INVENTION The image material support of the present invention produced by using a base paper produced by using a shoe press during the paper making process is an image material support excellent in rigidity and surface smoothness. Is obtained. In particular, by specifying the moisture content of the wet paper at the entrance of the shoe press, it is possible to obtain a support for an image material having extremely good rigidity and surface smoothness.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI // D21H 27/00 B41M 5/26 B (56) References JP-A-5-232627 (JP, A) JP-A-8- 3888 (JP, A) JP 61-174494 (JP, A) JP 8-296187 (JP, A) JP 7-109689 (JP, A) JP 8-190170 (JP, A) JP-A-6-282038 (JP, A) JP-A-3-200139 (JP, A) JP-A-7-295140 (JP, A) JP-A-7-189159 (JP, A) JP-A-7-70969 (JP, A) Special Table HEI 11-500792 (JP, A) (58) Fields surveyed (Int.Cl. ⁷ , DB name) D21H 11/00-27/42 G03C 1/00-1/95 B41M 5 / 00-5/26

Claims (3)

(57) [Claims] 1. On both sides of a base paper whose main component is natural pulp,
A support for an image material coated with a resin capable of forming a film, wherein the base paper is at least 1 in a papermaking process.
A support for image material, which is a base paper obtained by being subjected to a press treatment by a base closed shoe press device. 2. The nip pressure of the shoe press is 1500 k.
The support for image material according to claim 1, wherein the support is N / m or less . 3. The wet paper moisture content at the shoe press inlet is 60 to 8.
It is 0%, The support for image materials of Claim 1 or 2 characterized by the above-mentioned.