JPS59198451A - Manufacture of photographic support - Google Patents

Abstract

PURPOSE:To prevent small pores by twice coating paper with molten polyolefin. CONSTITUTION:In executing successive extrusion coating of the surface of paper with two layers of a molten polyolefin resin, a layer thickness ratio (ta/tb) of its upper layer thickness (ta) to its lower layer thickness (tb) on the side of the paper is controlled to 0.35-4.0. From the points of view of curl balance and adhesion to the paper, etc., the thickness of the polyolefin layer has so far been controlled to 15-50mum, but sometimes small pores like crators occur on the surface of the resin, resulting in lowering the luster of the printed surface after development, but it is prevented by said twice extrusion coating.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to photographic supports, and more particularly to supports for photographic paper.

Conventionally, baryta paper has been used as a support for photographic paper, but it has disadvantages such as processing liquids penetrating the paper during processing such as development and fixing, reducing processing speed and yellowing over time. Recently, resin-coated paper, which is a base paper whose both sides are extrusion coated with a resin such as polyethylene to make it waterproof, has come to be used.

Generally, an extrusion coating method is used to make such resin-coated paper.

However, when extrusion coating a molten polyolefin resin onto a base paper, crater-shaped pores may be generated on the resin surface.

In the support for Toku & C and Photo X, the thickness of the polyolefin layer is preferably from /j to 10μ in terms of curl balance, adhesion to base paper, pinholes, etc., but the thickness within this range is When the polyolefin layer is formed by extrusion coating, the above-mentioned pores are likely to occur, and if these pores occur frequently, the gloss of the printed surface of the photographic paper after development will be reduced, and the commercial value will be significantly reduced.

Therefore, an object of the present invention is to provide a method for manufacturing a photographic support coated with a polyolefin layer by extrusion coating a molten polyolefin resin onto a base paper, in which the generation of crater-like pores on the resin surface is minimized. An object of the present invention is to provide a method for producing a photographic support that can produce an excellent support for photography.

The present inventors did not extrude coat the molten polyolefin resin at once, but divided it into two layers and extruded coated them sequentially, and the ratio of the thickness of the upper layer and the lower layer (layer close to the base paper surface) of the polyolefin layer was It has been found that the object of the present invention can be achieved by setting .

That is, the object of the present invention is to provide a method for producing a photographic support coated with a polyolefin layer by extrusion coating a molten polyolefin resin onto a base paper, in which the polyolefin layer is divided into two layers and successively coated; And the ratio between the thickness of the polyolefin upper layer (ta) and the thickness of the polyolefin lower layer on the base paper side (tb) (ta / t)
b) was achieved by a light manufacturing method for a photographic support, which is characterized in that it is 0.35 to 0.35 g.O.

The polyolefin used in the present invention has a density of 0.9
/ J'~00730g/mouse low density polyethylene, density 00730~0. Suitable materials include high density polyethylene, polypropylene, etc., with a melt index of /. Particularly preferred are those having a length of 0 to 309710 minutes. You can also use a blend of each.

Either or both of these polyolefin layers include
White pigments such as lead oxide, titanium oxide, and titanium phosphate are mixed in with the aim of preventing blurring or improving the resolution of the above-mentioned printed image 1, and the filling acid is approximately Approximately 30 needles are preferably placed.

Among these white pigments, titanium oxide is most preferably used because of its excellent whiteness and hiding power. In addition, the polyolefin layer may contain known fluorescent brighteners, antioxidants,
Antistatic agents, release agents, colorants, dispersants, etc. may be added and used.

The effects of the present invention are as follows:
This is not achieved by methods of extrusion coating two layers at the same time (coextrusion coating method), or by simply sequentially coating polyolefins J and Δ on No. 111, one layer at a time. This is achieved by successive extrusion coating layer by layer at a thickness ratio (ta/lb) of .

Its thickness ratio (ta/tb) is 0°3! It is necessary that ≠, O, especially 0.4 to 3
．． 0 is preferred. Further KO0g to 1. Evening is most preferable.

ta/tb is O03! Less than or ≠.

If it is larger than 0, many crater-like holes occur. Why does a proper deposit area exist at t3/tb?(C is still unclear.)

In the present invention, extrusion coating refers to a method of coating a traveling base paper substrate with a polyolefin melt-extruded into a film from an extruder through a slit die. The melting temperature of polyolefin in the die is approximately 2! rO to 3jO0C, preferably 210 to 3
200C, and the running speed of the paper substrate is about ro to about 30
Approximately 0m/min, preferably 10m/min! ; Om/min is used.

In order to improve the adhesion between the polyolefin layer and the base paper,
The surface of the base paper may be subjected to a physical treatment such as corona discharge or a chemical treatment such as an anchoring agent. In order to improve the adhesion between the upper layer and the lower layer of polyolefin, it is also possible to apply a physical treatment such as corona discharge to the surface of the lower layer as described above, and then extrusion coat the upper layer.

Furthermore, after the upper and lower polyolefin layers are laminated and extrusion coated, adhesion to the photographic emulsion can be improved by coating the surface of the polyolefin with a coating containing gelatin as a main component or immediately after coating with a corona coating.

The base paper used as a support in the present invention includes natural pulp,
Synthetic, organic, or mixtures thereof are available. The thickness is about -20 to 700μ, particularly preferably 70 to 2θμ. Its designation ranges from about 100 g/m2 to 3jOg/rIL2, and 7 cylinders from 2009/m2 are particularly good.

Also, for these dislikes, 1. Additionally, known paper strength enhancers, sizing agents, coloring agents, fluorescent whitening agents, and the like may be added and used.

The photographic emulsion layer refers to all the so-called silver halide emulsion layers, diffusion transfer image-receiving layers, and organic or inorganic photosensitive agent layers other than silver halide.

The superiority of the method according to the invention will be explained in more detail below with reference to examples, but the invention is of course not limited to the examples.

The method for measuring crater-shaped holes in the examples is as follows.

A 1 cm square area of the surface of the polyolefin resin-coated paper was observed under 20 times magnification using a universal projector V-/& manufactured by Nippon Kogaku Co., Ltd., and holes with a diameter of 7 mm or more (actually measured 0μ) were counted. and j
The average number of visual fields was evaluated as the degree of occurrence of crater-like holes. If the average number is 20 or more, it will cause problems in appearance such as a decrease in gloss when printed on photographic paper.

Example LBKP10θ%, Tsubo 51/7 j jq 7'm
2. Density Q, ri 2017 /CC on base paper of thickness /IOμ
, Melt Index! , Og/10 min polyethylene extrusion coating. The polyethylene contained 10% by weight (based on polyethylene) of titanium oxide, and the thickness and coating method of the polyethylene layer were as shown in Table 1.

When evaluating the degree of occurrence of crater-like pores on the surface of the polyolefin resin coated paper obtained in this way,
As shown in Table 1, samples (F), (G), (
JXK), the number of crater-shaped holes is drastically reduced, and the Hiro effect is observed. When this support was used to produce a photographic paper print, no problems such as a decrease in gloss were observed.

Chapter/Table

Claims (1)

[Claims] In a method for manufacturing a photographic support coated with a polyolefin layer by extrusion coating a molten polyolefin resin onto a base paper surface, the polyolefin layer is divided into two layers and coated sequentially, and the thickness of the upper polyolefin layer is ta). Thickness of the lower layer of polyon fins on the base paper side t
b) ratio (t a / t b ) of 0.3! ~G. 1. A method for producing a photographic support, characterized in that: