JPS6035064Y2 - photographic support - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a support for waterproof photographic paper, which is formed by coating both sides of a paper layer with polyolefin. The present invention relates to a support for waterproof photographic paper provided with a polyolefin layer containing a white pigment.

For photographic materials that use paper as a support, especially photographic paper, research has been conducted to make the support waterproof paper for the purpose of speeding up the development process, and it has already been reported that both sides of the paper are coated with polyolefin, a hydrophobic resin. A waterproof support for photographic paper has been developed.

As shown in the figure, the structure of the above-mentioned support for waterproof photographic paper is that both sides of the paper layer are coated with polyolefin, and the polyolefin layer on the side coated with photographic emulsion contains a layer of polyolefin for the purpose of increasing the sharpness of the image. , contains white pigment.

The surface of the polyolefin layer on the emulsion-coated side of the support is a smooth surface, a grained surface, or a surface of various other shapes depending on the use, and the surface of the polyolefin layer on the back side is a surface with the purpose of giving an appearance similar to paper. It has a so-called matte surface with minute irregularities.

The hue of the emulsion-coated surface of the support is preferably pure white; if this hue leans toward yellow or red, the image formed on the photographic paper will be completely dull.

However, titanium oxide, zinc oxide, etc., which are normally used as white pigments, have a slightly yellowish hue, and gelatin, one of the main components of photographic emulsions, is sensitive to visible light. It has absorption in the short wavelength region and exhibits a pale yellow color.

For the above two reasons, adding a blue-based color, which is a complementary color to yellow, to the emulsion-coated surface of the support for waterproof photographic paper increases the visual whiteness and produces favorable results for photographic paper. bring.

The most common method for imparting a blue tint to the emulsion-coated surface is to add an appropriate amount of a blue colorant to the emulsion-coated polyolefin layer.

Among the blue coloring agents, blue dye, which is an organic substance, is classified by its type,
Although there is an extremely rich variety of hues, they all have poor heat resistance.
Discoloration occurs under high temperature conditions during melt molding of the polyolefin layer.
Discoloration is significant and it cannot be used for practical use.

On the other hand, inorganic blue pigments such as ultramarine and cobalt blue have excellent heat resistance, but the variety of hues is limited, and the best color that corresponds to the color of the white pigment or the color of the emulsion layer is used. The best hues are not obtained with inorganic blue pigments.

As a result of studying various methods for adjusting the hue of the surface of the support mentioned above, the inventor of the present invention found that by coloring the surface of the paper layer of the support for waterproof photographic paper blue, the hue of the surface of the support becomes closer to blue. We found that the hue of the surface of the paper layer of the support provided with the polyolefin layer containing at least one of titanium oxide and zinc oxide as a white pigment was determined by the measurement method and display specified in JIS Z8722 and JIS Z8730. L = 80 or more a = 0 as a value according to the law
．． 5 to 6. It has been found that when Ob=-3.0 to -13.0, the surface of the support visually appears whitest.

According to JIS Z8730, L represents lightness, and the larger the value, the higher the lightness.

a represents redness, and the larger the value, the stronger the redness; b is an index of yellowness; the higher the value, the stronger the yellowness.

A negative value of b indicates that a complementary color to yellow, that is, blue, appears.

If the values of at and b are both zero, it means colorless.

On the other hand, L, which represents lightness, has no direct relationship with hue, but L
When the value is low, the whiteness of the support surface becomes dull and the image on the photographic paper becomes dark.

The a value of the surface of the paper layer is 6.0 or more or the b value is -13.0
In the following cases, the color density on the surface of the paper layer becomes excessive, and even if a polyolefin layer containing a white pigment is provided on the surface of the paper layer, the hue on the surface of the waterproof photographic paper support will not be visually white;
It becomes blue or bluish-purple, making it unsuitable for photographic paper applications, while the a value is 0 to 0.5 and the b value is 0 to -3.0.
In this case, the blue tint on the surface of the paper layer is insufficient, and the hue on the surface of the support becomes visually yellowish, making it impossible to fully expect the effects of the present invention.

The L value of the surface of the paper layer needs to be 80 or more in order to obtain the above-mentioned sharpness of the image.

That is, in this invention, the paper layer is colored with blue dye, and its JISZ
-8722 Oyohi JIsZ-8730 Ni standard Sareta measurement method and display method surface reflection characteristics L = 80 or more,
The present invention relates to a photographic support in which a polyolefin layer containing a white pigment is provided on the surface of a paper layer in which a=0.5 to 6.0 and b=-3.0 to -13.0.

The pulp used in the paper layer of the present invention may be either hardwood pulp or softwood pulp, or may be kraft pulp or sulfide pulp, but it is preferable that any of them be bleached.

In addition to the pulp, there is no problem even if the paper layer contains a sizing agent, a paper strength enhancer, or a filler such as talc or clay.

The polyolefin used in this invention is polyethylene, polypropylene, and ethylene, and has a carbon number of 3 to 6.
It is a copolymer with monoolefin.

The thickness of the paper layer in the support for photographic paper according to the present invention is not particularly limited, but is preferably 100 to 180 microns.

The thickness of the polyolefin layer on the emulsion layer coating side is 20 to 35
microns, and the amount of leached pigment contained in the polyolefin layer is 5 to 2 percent by weight, based on the polyolefin.

Although there are no particular restrictions on the composition of the back polyolefin layer, it is usually preferable to use one that does not contain pigment and has a thickness of 15 to 40 microns.

Various water-soluble blue dyes can be used to color the paper layer depending on the required hue, and the dyeing methods include internal addition to the paper stock, dyeing according to surface size, or dyeing on the paper surface after paper making. Examples include application to.

The coloring of the paper layer according to the present invention does not necessarily have to be carried out on both sides of the paper, and it is sufficient to color only one surface of the paper for emulsion measurement.

Examples of white pigments added to the polyolefin layer include the above-mentioned titanium oxide and zinc oxide, and those used in combination with these include zinc sulfide, calcium sulfate, aluminum oxide, silicon oxide, barium sulfate, etc. .

Addition of white pigment to polyolefin involves heating and melting the polyolefin resin and white pigment powder in a kneader.
This is carried out by kneading using a Banbury mixer or the like.

Further, if necessary, an appropriate amount of a blue colorant may be contained in the polyolefin layer.

The surface of the paper layer is coated with the polyolefin layer by a so-called extrusion lamination method in which a molten resin is dropped onto the surface of the running paper layer and is pressure-bonded.

The numerical values of L, a, and b described in the specification of the present invention were measured using an automatic colorimeter AU-CH-1 manufactured by Toyo Rika Kogyo ■.

EXAMPLE A base paper (2) for a water-resistant support having a basis weight of 185 g/- and a thickness of 180 microns was produced, consisting of 3% by weight of softwood pulp and 7% by weight of hardwood pulp.

Next, using a size press, the base paper (■) was dyed blue with an aqueous solution of a dye containing a 1:1 mixture of methyl violet and phthalocyanine.

The concentration of the dye aqueous solution was set to 0.0005.0.0015.0.
The blue base paper obtained by dyeing with these three levels of 00 species amount percent was bound to the base paper ■, ■, and ■, respectively.

Base paper I, II, III by extrusion lamination method
, a transparent polyethylene layer with a density of 0.926 g/CC melt index 2.0 and a thickness of 40 microns on the back surface of the IV, and a density 0.926 g/CCs melt index 2.0 and rutile type titanium oxide pigment 1 on the emulsion coating side surface. A white polyethylene layer having a thickness of 35 microns containing a saliva content percentage was provided to form waterproof supports A, B, and C9D, respectively.

Furthermore, on the back surface of the base paper I, a transparent polyethylene layer with a density of 0.926 g/CC1 melt index of 2.0 and a thickness of 40 microns as described above is applied, and on the emulsion coating side surface, a transparent polyethylene layer for use with rutile-type titanium oxide pigment is applied. Density including weight percent and blue pigment Ultramarine 1500'IO, heel weight percent 0.926 g/CC Melt Index2.
0, Thickness 35, Micron white polyethylene layer was used as water-resistant support E.

The emulsion-coated surface adhesive of the four types of base papers mentioned above and the five types of waterproof supports manufactured using these, aSb
The values were measured and were as shown in the table.

Furthermore, when the visual whiteness was compared and examined, the water-resistant supports A1 and B listed in the table had a strong yellow tinge, and D had a strong blue tinge, and both had insufficient visual whiteness.

On the other hand, the water-resistant supports C and E were white in appearance, but when comparing them, the visual whiteness of the support C according to the present invention was significantly superior.

[Brief explanation of drawings]

The drawing is a sectional view of a support for waterproof photographic paper. In the figure, 1 is a paper layer colored with a blue dye, 2 is an emulsion-coated polyolefin layer containing a white pigment, and 2 is a back polyolefin layer.

Claims (1)

[Scope of utility model registration request] The paper layer is colored with a blue dye, and the surface reflection characteristics according to the measurement and display methods specified in JISZ-8722 and JISZ-8730 are L = 80 or more, a = 0.5 to 6.0, b = - A photographic support comprising a polyolefin layer containing a white pigment provided on the surface of a paper layer having a particle size of 3,0 to -13,0.