JPS5950974B2 - Photographic base material made of cellulose - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to photographic base materials consisting of cellulose.

The use of cellulose in the form of paper or cardboard as raw material for photographic base materials has been known for a long time.

Paper as a photographic base has many advantages and is inseparable from the concept of the photographic image.

Due to the lack of suitable types of cellulose and the ever-increasing price of cellulose, efforts have already been made for a long time to find substitutes and additives for cellulose. It is known, for example, to produce photographic bases consisting entirely of fibrous plastic, but this is difficult to use for a number of reasons, such as the appearance, feel, mechanical properties and price being significantly different from paper bases. I couldn't do it. The object of the present invention is therefore to correspond approximately to conventional photographic base materials made of cellulose or paper, i.e. to have the opacity, tear strength and flexibility normal to this type of paper, but better than the conventional photographic paper base. The object is to obtain a photographic base material containing only a small amount of cellulose. This objective was achieved by adding foamed, partially foamed or unfoamed microspheres to the cellulose used in the production of photographic paper at a concentration of 0.5 to 5% by weight relative to the cellulose. I'm going to be killed.

Such microspheres, hereinafter abbreviated as MK, are known per se and are produced, for example, by Tau Chemical (Dow Chemical Comp).

This MK consists of a vinylidene chloride-acrylonitrile copolymer with about 12% isobutane as a blowing agent. The average diameter of this type of sphere in the unfoamed state is 5 .mu.m, and upon heat treatment the diameter increases to 30 .mu.ml.
This heat treatment can be performed either before use or in situ. However, when such MK is used for xerographic copying paper, for example, the MK has an areal weight of up to 120 g/
It has become clear that this method is only effective for light paper up to M2.

If the areal weight is large and therefore the paper thickness is large, the MK will not relax the already developed fibrous structure of the paper on the drying cylinder of the paper machine and will therefore have only a small effect on the specific volume increase and flexibility of the paper. Unhelpfully large temperature gradients result.
It has also been found that papers containing MK have a strong tendency towards water absorption associated with peeling, curling, electrostatic charging and low surface gloss. This type of paper also generates a large amount of dust during subsequent processing. Strong water absorption, low gloss and significant dust. MK on photo paper due to its tendency to generate
Moreover, photographic paper is often a heavy paper with an areal weight of 160-200 g/m2. In addition to this disadvantageous property of MK-containing papers, the gloss cannot be produced by producing a strong gloss afterwards as usual. It must be pointed out that improvements cannot be made by This is because MK disintegrates at a line pressure of about 35 kg/Cm at 200 flies, reducing the desired high specific volume of the paper. An increase in the calender roll temperature increases the gloss by fusing the MK present on the surface, but in this case there is a risk that the MK within the paper structure will disintegrate. This is because the softening temperature of MK is about 90°C. For photographic paper, a smooth surface finish and low water absorption are important to prevent the bath liquid from penetrating into the interior of the paper through the cut edges, and sufficient flexibility is necessary, as well as all our experience in the industry. Although they are against the use of MK in photo paper, this problem was solved completely unexpectedly.

This is because the base material produced in this way surprisingly exhibited a relatively smooth surface and a rather lower water absorption than conventional paper. In the case of 140 g/m paper, a flexibility corresponding to approximately 170 g/M2 paper is obtained.

Particularly good properties of the photographic base material are the addition of unfoamed or prefoamed MK in an amount of 1-2% based on cellulose, as well as 0.1-1% by weight of a water repellent and 1-2% by weight of a retention agent to the paper. It can be obtained by Particularly for heavy papers, it is possible to start with unfoamed or partially foamed MK, which is mixed with cellulose, formed into a sheet and then foamed in situ in the first drying section of the paper machine under the action of high-frequency energy. can. However, care must be taken that the high frequency treatment is carried out before the final fixation and bonding of the cellulose fibers to each other has begun. The invention will now be explained by way of example.

Example: 70% softwood sulfate pulp and 30% hardwood sulfite pulp
% of the cellulose mixture at approximately 35°SR
SchOpper-Riegler, u
1% of the retention agent known under the name Kymene 557 and Aquapel 360 with a value of 7.
Size by 0.5% of water repellent agent known under the name of ×Z,
8% starch and a water soluble conductive agent such as Na.

Mechanically coat with SO, etc. This paper was packed with pre-foamed MKI in a shipping box. Add % O by weight. The data for the photo paper obtained from this is shown in the following table in comparison with regular photo paper without MK: From this table, the photo paper containing MKI weight % and having a weight of 144 g/M2 with the above sizing has a flexibility of 144 g/M2. It is clear that this is higher than that of photographic paper of 172 g/m.

The gloss remained constant within the measurement accuracy, and the penetration of the bath liquid was rather reduced. Unfoamed or partially foamed M as described in the examples
The K-containing paper is treated by microwave dielectric heating at a frequency of 27 MHz as described above, thereby improving the thickness of the paper.

Claims (1)

[Scope of Claims] 1. Area weight 1 made of cellulose in the form of paper or cardboard.
For photographic base materials exceeding 20 g/m^2, fully or partially foamed microspheres of thermoplastic material or unfoamed microspheres are added to the pulp used for the manufacture of the base paper to cellulose. A photographic base material comprising cellulose, characterized in that cellulose is added at a concentration of 5 to 5% by weight. 2. The photographic base material according to claim 1, wherein 0.1 to 1% by weight of a water repellent and 1 to 2% by weight of a retention agent are additionally added to the pulp. 3. The photographic base material according to claim 2, which uses an alkyl ketene dimer as a water repellent and a cationic polyamide resin as a retention agent.