JPH0341226B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a method for simultaneously drying both sides of an object to be dried, such as a strip of material having a coating layer to be dried on both the front and back sides of a photographic light-sensitive material. The present invention relates to a double-sided simultaneous drying method that controls the chemical and physical properties of coating layers such as photosensitive emulsion layers to prevent coating failures. [Prior Art] Conventionally, in drying the coated surface of photographic film,
When drying a film that has a coated surface on only one side, the coated surface must be heated to a predetermined dry bulb temperature (hereinafter referred to as DB).
The drying process is carried out by blowing wind at a temperature of It would have been better if he had done it only for himself. However, recently, Japanese Patent Application Publication Nos. 57-63163 and 57-
As shown in Japanese Patent No. 63164, a double-sided coating method using a non-contact supporting and conveying means has been developed, and the need for double-sided drying has arisen in drying the coated surface. Looking at conventional double-sided drying methods, the air from one air conditioner was divided into the front and back sides, so the front and back sides were dried under the same drying conditions. However, when drying under the same drying conditions, the coating film thickness on the front and back sides will differ, or the gelatin concentration will differ, so if the drying load is different, the drying end points on the front and back sides will differ greatly. There was a problem that serious failure occurred in the chemical and physical properties of the coating layer. Furthermore, even if the drying end points of the front and back surfaces are substantially the same, the moisture content and temperature of the coating layer in each process cannot be controlled arbitrarily, so the chemical and physical properties of the coating layer cannot be controlled. This caused malfunctions such as poor photographic characteristics. [Purpose of the Invention] The present invention was made to solve the above-mentioned problems, and its purpose is to provide a uniform coating on both sides at the end of drying, even if the coating film thickness, gelatin concentration, etc. on the front and back sides are different during coating. It is an object of the present invention to provide a method for simultaneously drying both sides of a strip-shaped object, etc., which does not cause failures such as drying failure or deterioration of photographic characteristics in the coated layer. [Summary of the Invention] The above-mentioned object of the present invention is to simultaneously dry both sides of an object to be dried, such as a belt-shaped material having coated layers to be dried such as photographic light-sensitive materials on both the front and back sides, by blowing wind from both sides of the object. In the method, air conditioning means for blowing wind on one side and air conditioning means for blowing wind on the other side are separately provided, and the drying conditions of dry bulb temperature, dew point, heat transfer coefficient, and heat transfer area are determined for each of the front and back surfaces. Achieved by a simultaneous drying method for both sides of a belt-shaped object, etc., which is set separately and has substantially the same drying end point of the front and back surfaces of the object to be dried, and also controls the moisture content separately and independently. be done. According to a preferred embodiment of the present invention, the drying process comprises a plurality of divided zones, and the drying in the process is carried out in zones corresponding to the constant rate drying period and the beginning of the decreasing rate drying period. [Structure of the Invention] The contents of the present invention will be explained in detail below. In the present invention, the term "belt-shaped material" refers to a strip-shaped material such as a photographic film or a continuously conveyed sheet-shaped material. Such a belt-like material is disclosed in, for example, Japanese Patent Application Laid-open No. 1986-
Both sides are coated by the non-contact coating method described in Publication No. 63163, etc., and if necessary, JP-A-57-87868.
After being gelled by the gelling method described in the above publication, in the drying step of the present invention, the coated layers on both sides are dried by blowing air onto both sides. The air conditioner used for drying has two functions: a means for blowing air on the front surface and a means for blowing air on the back surface. Although these two functions can be performed by one air conditioner, separate air conditioners may be provided for the front surface and the back surface. These air conditioners have dry conditions DB, DP, and heat transfer coefficient h.
It has a configuration that allows it to vary. Note that the heat transfer coefficient h can be changed by changing the blowing wind speed, changing the porosity, etc. Further, the heat transfer area can be changed by changing the conveyance route of the strip. In the present invention, the drying conditions for the front and back surfaces are as follows:
Each is set separately and independently. Examples of the drying conditions to be set include DB, DP, heat transfer coefficient h, and heat transfer area s. In the present invention, the means for conveying the dried object is
No. 57-63163 and No. 57-16164, non-contact conveyance used for double-sided coating is suitable, and the present invention is suitable for drying in such a non-contact conveyance process or in drying that also uses non-contact conveyance. used effectively. In the present invention, the object to be dried, which is a strip-like material such as a photographic light-sensitive material, is set so that the drying end points of the coating layers on the front and back surfaces thereof are substantially at the same position. Here, "substantially" means that even if the end points of the drying process of the front and back coating layers are different in form, it is sufficient as long as it does not affect the chemical and physical properties of the photographic light-sensitive material, etc. do. That is, when drying of the object to be dried is carried out alternately on the front and back sides as shown in the gelling method described in the above-mentioned Japanese Patent Publication No. 57-87868, although the positions are not formally the same, such The present invention also includes the case of drying means. In the present invention, the water-containing layers of the coating layers on both the front and back sides are controlled separately and independently, but at the end of drying,
The moisture content is controlled to be the same. For example, when the drying process of the main coating is divided into two or more parts, the moisture content of the front and back coating layers may be adjusted in any of the divided drying processes, but at the end of drying, the moisture content of the front and back coating layers is considered to be equivalent. However, depending on the coating layer, in order to cope with deterioration of its physical properties and chemical properties, it is necessary to control the drying rate in accordance with a certain moisture content. In this case, it is necessary not only to make the drying end points of both sides substantially the same, but also to control the moisture content and speed separately for the front and back sides. According to a preferred embodiment of the present invention, the drying step is divided into two or more, and the drying in this step is carried out in zones corresponding to the constant rate drying period and the early decreasing rate drying period. For example 1p~3p
In the case of a drying process divided into 1 and 2, in the final 3p process, DB, DP, heat transfer coefficient, and heat transfer area are set to be equal on the front and back surfaces, and in the previous 1p and 2p processes, DB, DP,
The heat transfer coefficient and heat transfer area are set separately for the front and back surfaces. In some cases, in the first 1p process,
In order to make the drying end points of the front and back sides substantially the same, DB, DP, heat transfer coefficient, and heat transfer area are controlled separately for the front and back sides, and in the 2p process, the physical and chemical properties of the front and back sides are controlled. DB, DP,
The heat transfer coefficient and heat transfer area may be controlled. The present invention relates to a photographic light-sensitive material, particularly for direct X-ray use, which has a silver halide gelatin emulsion layer coated on both sides of a plastic base, and has a light-sensitive emulsion layer and other photographic constituent layers on the surface, and a packing layer on the back surface. Drying of gelled or semi-gelled coating layers on both sides of a very thin base (including polyethylene terephthalate, cellulose triacetate and paper), such as photographic materials Ideal for EXAMPLES Specific examples of the present invention are given below to illustrate the effects of the present invention. In a non-contact drying device consisting of three drying processes, 1p, 2p, and 3p, shown in Table 1 below, each process cell is equipped with equipment that allows drying conditions to be set independently for the front and back surfaces. Using this apparatus, photographic film was dried at a transport speed of 20 m/min. This photographic film was produced by applying a photosensitive emulsion coating solution to a thickness of 110 μm on the surface of a long polyethylene terephthalate film base using the apparatus disclosed in the above-mentioned Japanese Patent Application Laid-open No. 57-63163, and applying a packing layer coating solution to the back surface. was applied to a thickness of 95μ. The drying conditions were as shown in Table 1 below.

[Table] Under the above conditions, DB and DP were set so that the WB of the air blowing conditions was the same for both the front and back surfaces in order to maintain the same coating layer temperature on the front and back sides as a physical property measure. The heat transfer coefficient h was determined by changing the speed of wind blowing onto the photographic film. Furthermore, the heat transfer area was the same on the front and back surfaces. Under the above conditions, a photographic film with the same drying end point and stable chemical and physical properties without any defects was obtained.

Claims (1)

[Scope of Claims] 1. In a double-sided simultaneous drying method in which an object to be dried, such as a strip of a photographic light-sensitive material or the like having coating layers to be dried on both the front and back sides, is dried by blowing wind from both sides, one Separate air conditioning means are provided to blow wind on one surface and air conditioning means are used to blow wind on the other surface, and drying conditions such as dry bulb temperature, dew point, heat transfer coefficient, and heat transfer area are set separately and independently for each of the front and back surfaces. A method for simultaneously drying both sides of a strip-shaped article, etc., characterized in that the drying end points of the front and back surfaces of the object to be dried are made substantially the same, and the moisture content thereof is controlled separately and independently. 2. Claim 1, characterized in that the drying process comprises a plurality of divided zones, and the drying in the process is carried out in zones corresponding to the constant rate drying period and the initial period of the decreasing rate drying period. Simultaneous drying method on both sides of strips, etc.