JPH0481836A - Production of base for photographic paper - Google Patents

Abstract

PURPOSE:To produce the bright surface photographic paper which has sufficient smoothness, is free from troubles in appearance and is advantageous in terms of cost by coating raw paper with polyolefin right after the raw paper is subjected to a calender treatment between metallic rolls and synthetic resin rolls. CONSTITUTION:Both surfaces of the raw paper are coated with the polyolefin right after the raw paper is subjected to the calender treatment between the metallic rolls and the synthetic resin rolls. The term 'right after the calender treatment' refers to the time within 300 seconds after the calender treatment. The generation of crater-like fine pores liable to arise on the surface of the resin at the time of extrusion coating of the polyolefin resin is prevented in this way and the thickness of the polyolefin layer is decreased. The influence by moisture, etc., appears and the prevention of the generation of the crater-like fine pores is imperfect if the paper is rested for >=300 seconds. The moisture of the raw paper at the time of the calender treatment is preferably 6.0 to 9.0% and the surface temp. of the synthetic resin rolls is preferably set at 50 to 250 deg.C.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a support for photographic paper, and particularly to a support for photographic paper with good surface smoothness.

(Prior Art) In recent years, for the purpose of rapid development of photographic paper, water-resistant photographic paper supports in which both sides of the paper are coated with polyolefin such as polyethylene have been preferably used.

Among photographic paper supports made of base paper coated on both sides with polyolefin, there are those whose surfaces are glossy and those whose surfaces are patterned, such as matte or silky. Among these, those with no patterns at all and a smooth, glossy surface are said to be good, and in particular, those with as few fine irregularities as possible on both sides and a mirror-like smooth surface are said to be good.

In order to obtain such a smooth support, for example, the amount of voids with pores of 0.4 μm or less in the base paper constituting the support is 0.0
Use pulp of 4d1g or more (Japanese Patent Application Laid-Open No. 60-6
7940), using wood pulp with an average fiber length of 0.4 to 0.9 mm, an average fiber content of 13.5 pm or more and an average fiber thickness of 4 μm or less (Japanese Patent Application Laid-Open No. 60-69649), hydrophobic to natural pulp. Use a mixture of 5 to 60% fiber (Japanese Patent Application Laid-Open No. 61-275752), or limit the dehydration conditions when obtaining wet paper from pulp slurry using a two-wire paper machine (Japanese Patent Application Laid-open No. 61-284762). Some other ideas have been proposed. Additionally, the density of the base paper used as a support for photographic printing paper is increased by calendering the base paper between metal rolls and increasing the pressure at this time, that is, the pressure of the machine calender. There is. On the other hand, for coating polyolefins such as polyethylene, an extrusion coating method, in which polyolefin melted at high temperature is cast onto the surface of base paper, is generally used. In order to improve smoothness, measures have been taken such as increasing the thickness of the polyolefin coating layer or increasing the pressure applied during the polyolefin coating.

However, the above-mentioned measures when coating polyolefin have a small effect and are also disadvantageous in terms of cost. On the other hand, the above-mentioned method of increasing the density of the base paper by machine calendering also has the disadvantage that appearance defects such as blanking and paper curls are likely to occur, and it is not possible to obtain a satisfactorily smooth photograph using either method. A support for photographic paper has not been obtained.

・In other words, if the base paper has irregularities, it goes without saying that there are irregularities on the front side of the base paper, but even if the front side of the base paper is smooth, if the back side has irregularities, the unevenness on the back side will occur. Depending on the extent of this, the influence of these irregularities on the back surface appears on the front surface when extrusion coating the polyolefin, and there is a problem that a smooth surface that can be used as a support for photographic printing paper cannot be obtained.

By the way, recently it has been discovered that there are two types of irregularities on base paper: large wave-like irregularities with a period of around 5cm, and small dot-like irregularities with a period of around 0.5 - and that the base paper is simply rolled with a metal roll. - When machine calendering is performed between metal rolls, the above-mentioned wavy irregularities can be removed, but it is difficult to remove dotted irregularities without causing blacking, etc. - It was found that when supercalendering was performed between cotton rolls, it was possible to remove dotted irregularities, but it was difficult to remove wavy irregularities.

Furthermore, since the rolls of supercalenders are easily damaged, it is difficult to use them on-machine, and it is disadvantageous in terms of cost.

(Problems to be Solved by the Invention) The above-mentioned problems with water-resistant photographic Inzai paper can be greatly improved by using base paper that has been calendered with metal rolls/synthetic resin rolls instead of the conventional supercalender. (Japanese Patent Application No. 1-22284), however, even if the surface smoothness of the base paper is improved by the calender treatment using the metal roll/synthetic resin roll, crater-shaped pores are formed on the resin surface when coated with polyolefin. This may occur and cause an appearance failure.

The inventor of the present invention has solved the above drawbacks (as a result of intensive studies, it has been found that if the polyolefin is coated immediately after calendering with a metal roll/synthetic resin roll, the above appearance failure does not occur, and the thickness of the coated polyolefin layer is The present invention was achieved by discovering that the taste can be reduced.

Therefore, an object of the present invention is to provide a support for photographic paper that has sufficient smoothness, is free from defects in appearance, and is advantageous in terms of manufacturing cost.

(Means for Solving the Problems) The above object of the present invention is to provide a method for producing a support for photographic paper in which both sides of base paper are coated with polyolefin.
This was achieved by a method for producing a support for photographic paper, characterized in that the base paper is coated with polyolefin immediately after calendering between a metal roll and a synthetic resin roll.

The present invention will be explained in more detail below.

The base paper used for the support for photographic paper according to the present invention is obtained by making paper from a paper stock containing natural bulbs obtained from coniferous trees, hardwood trees, etc. as the main raw material and various chemicals described below added thereto. Generally, by using valves made from coniferous trees such as NBKP, the internal bonding strength of the base paper increases and L
By using valves made from hardwoods such as BSP and LDP, the internal bonding strength of the base paper can be reduced.

In the present invention, a synthetic valve may be used in place of the natural valve, or a base paper prepared by mixing natural pulp and synthetic pulp in an arbitrary ratio may be used.

Further, in order to make the present invention more effective, it is preferable to use bulbs having an α-cellulose content of 90% or more in an amount of 25% by weight or more, especially 50% by weight or more.

Also, the freeness of the valve is 200 to 500cc.

S, F, are preferred, especially 250-350ccC,
S and F are preferred.

Additive chemicals include clay, talc, calcium carbonate, fillers such as urea resin particles, rosin, alkyl ketene dimers, higher fatty acid salts, paraffin wax, sizing agents such as alkenylsuccinic acid, paper strength agents such as polyacrylamide, and sulfuric acid bands. , a fixing agent such as aluminum chloride, etc. are used.

In addition, dyes, fluorescent dyes, slime control agents, antifoaming agents, etc. are added as necessary. Furthermore, the following softeners may be added as necessary.

Softeners are described, for example, in the New Paper Processing Handbook (edited by Shigyo Times), pages 554-555, published in 1980. Among these, those having a molecular weight of 200 or more are preferable, and those having a hydrophobic group having a carbon number of 10 or more, or having an amine salt or a quaternary ammonium salt that self-fixes with cellulose are particularly preferable. Specific examples include reaction products of maleic anhydride copolymer and polyalkylene polyamine, reaction products of higher fatty acid and polyalkylene polyamine, reaction products of urethane alcohol and alkylating agent, and quaternary ammonium salts of higher fatty acids. etc. Among these, particularly preferred are reaction products of maleic anhydride copolymer and polyalkylene polyamine, and reaction products of urethane alcohol and alkylating agent.

The surface of the base paper can also be subjected to surface size treatment using a film-forming polymer such as gelatin, starch, carboxymethyl cellulose, polyacrylamide, polyvinyl alcohol, or a modified product of polyvinyl alcohol. Examples of polyvinyl alcohol modified products in this case include carboxyl group modified products, silanol modified products, and copolymers with acrylamide. In addition, when surface size treatment is performed using a film-forming polymer, the coating amount of the film-forming polymer is as follows:
O, 1 to 5.0 g/nf, preferably 0°5 to 2.0
g/nf. Furthermore, an antistatic agent, a fluorescent whitening agent, a pigment, etc. can be added to the film-forming polymer at this time, if necessary.

Among these various additives, paper strength enhancers or surface sizing agents are used to increase the internal bonding strength of the base paper, while sizing agents, softeners, fillers, etc. are used to reduce the internal bonding strength of the base paper. You can force it.

In the present invention, the internal bonding strength of the base paper is 1.2 to 1.8.
Preferably, a kg-cm base paper is used.

If the internal bonding force is less than 1.2 kg-am, not only will the paper be easy to cut, but when the paper is coated with polyolefin resin and peeled off from the cooling roll, minute breaks will occur on the surface of the base paper layer (blister failure). This causes appearance failures.

Furthermore, if the internal bonding force is greater than 1.8 kg-am, an effective flatness improvement effect cannot be obtained when calendering is performed using metal rolls/synthetic resin rolls, which will be described later.

The base paper is made by making a valve slurry containing the above-mentioned valves and additives such as filler, sizing agent, paper strength reinforcing agent, fixing agent, etc., added as necessary, using a paper machine such as a Fourdrinier paper machine, and then drying the slurry. , produced by observing. The surface size treatment is performed either before or after this drying, and the calendering treatment described below is performed after drying or between winding.

If the surface sizing treatment is performed after drying, this calendering treatment can be carried out either before or after the surface sizing treatment, but it is particularly preferably carried out in the final finishing step after various treatments have been carried out.

The calendering process according to the present invention is carried out between a metal roll and a synthetic resin roll (soft [4 calendering process)].
This is what we do.

Instead of the above calender treatment, Jllk was subjected to machine calender treatment only, and the density of the base paper was reduced to 1606 g/c.
If an attempt is made to obtain sufficient smoothness by carrying out this treatment until yi& or more, blacking occurs and the appearance 6 of the obtained base paper is impaired. Also, the density of the base paper is 1゜0
If the treatment is less than 6 g/cffl, the above-mentioned point-like irregularities cannot be removed, and photographic paper with good smoothness, which is the object of the present invention, cannot be obtained. Further, when only super-calendering is performed, there is a limit to the thickness of the base paper that can be adjusted, and the above-mentioned wavy irregularities cannot be removed.

In contrast to the dirt V, in the case of calender treatment using the synthetic resin roll employed in the present invention, ζl:! :, J-, both the wave-like irregularities and the point-like irregularities can be removed.

In this case, from the viewpoint of adjusting the thickness and further enhancing the effect of removing dots and wavy irregularities, calendering is performed between the metal roll and the metal roll in advance. It is preferable to do each io.

stomach.

The material of the synthetic 411 resin roll used in the present invention is appropriately selected from synthetic resins such as urethane, ebonite, nylon, amide, isocyanurate, and polyether. Among these, it is particularly preferable to use polyether synthetic resins.

As for the hardness, it is preferable that the hardness (■) is 60 to 9 days, and 75 to 93 is especially preferable.
The moisture content of the base paper during calendering is preferably 6.0% to 9.0%, and the surface temperature of the synthetic resin roll is 25% to 50°C.
It is preferable to cool down to 0°C, especially 70'C and 150'C.

Also, the base paper density is 069 between metal rolls.
Calendar treatment is performed so that the concentration is 0 to 1.05 g/cd, and then 1.00 g/cd is applied between the metal roll and the synthetic resin roll.
- It is preferable to carry out a toothpick calendering process to achieve a rate of 1.20 g/cd.In addition, it should be applied not only after performing outside calendering between the metal rolls and the metal rolls, but also between the metal rolls and the metal rolls. It is more preferable to perform calender treatment between the metal compound and the synthetic #i1 resin before calendering.

The base paper used for the photographic paper supporting body of the present invention is calendered as described above and has a density of 50 to 250 μm in terms of dose.
is adjusted to

Invent this! 9. After the calendaring process described in 1., both sides of the base paper must be coated with polyolefin.
Manufactures holders for photographic paper. Calendar
- Immediately after processing and U, meaning within 300 seconds after processing, but 1, special l':, I prefer J' to be within 100 seconds.This?,: Therefore, when polyolefin resin is extruded (,=1-Ting 4, 1, the resin surface?S 41:: 1,,,, !, the diameter of the dark spot is several 10...several 100 zt glue) The thickness of the polyolefin layer can be reduced, and the thickness of the polyolefin layer can be reduced.・If the treatment is left for more than 300 seconds, the effects of moisture etc. will appear and the prevention of silk pores in the form of a re-coup will be incomplete.

2! , eyes, 7i mm immediately after ~ 1. Extrusion of the metal 1:te--
Lou synthetic tree IN tl - Louie: Soft power used 1be/
The polyol resin 2'1. Examples include homopolymers of α-1st nophine such as polyethylene and polypropylene, and mixtures of these polymers. Especially preferred 1. Polyolefins are made of high-density polyethylene (, -''/, low-density polyethylene and mixtures thereof). As long as the
Usually, a polyol/fin with a molecular weight of 2 (J in the range of 1,000-200,000) is used. There is no limit to this.
:r, *L,r Determination: 7 Toka T is possible, but usually 15-50 μm is preferable.

Polio 1.・M in the fin resin layer, Act, self-colored tortoise,
It is possible to add known additives such as ready-to-color materials, optical brighteners, acids (tJIFj inhibitors, etc.6), especially photographic emulsions! White pigments and Preferably, colored baits are added.

The photographic paper support of the present invention is further coated with a photographic opalescent layer on one side and dried to obtain a photographic paper. Various types of M keyaki are possible, such as the ability to provide layers.

(Effects of the Invention) According to the present invention, irregularities of various sizes on the surface of the base paper used as a support for photographic Inzai paper are removed and the surface of the base paper is made sufficiently smooth. A support for photographic paper with excellent smoothness can be easily obtained even when coated with a thin layer of polyolefin, and the resulting support for photographic paper has no visual defects, and the thickness of the polyolefin layer is also reduced. Since the manufacturing cost can be reduced, the present invention is most suitable for the manufacturing method of glossy photographic paper.

EXAMPLES Hereinafter, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited by these Examples.

(Example) A wood pulp consisting of 70 parts LBKP, LBSPIO parts, and NB5P2O parts was refined to Canadian freeness of 260 cc using a disc refiner, and 0.5 parts of epoxidized behenic acid amide and 1.5 parts of anionic polyacrylamide were added.
0 parts of aluminum sulfate, 1.0 parts of cationic polyacrylamide, 0.5 parts of cationic polyacrylamide, and 0.1 parts of polyamide polyamine epichlorohydrin, all in the absolute dry weight ratio to the wood bulb, were added, and the basis weight was 180 g/m2 using a Fourdrinier paper machine. , a paper with a moisture content of 7.8% was made. After that, 10% titanium oxide
% polyethylene was extrusion coated onto the surface of the paper to a thickness of 30 μm.

Further, the back side of the paper was extruded and coated with polyethylene not containing titanium oxide to a thickness of 28 μm.

The relationship between the paper calendering conditions, the density of the finished paper, and the elapsed time from calendering to extrusion coating is shown below.

Sample Nα1. Calendered to a density of 1.03 g/cm'' using a bimetal roll-metal roll machine calender. Time to extrusion coating was 28 hours.

Sample Nα2. : Calender treatment was performed to a density of 1.03 g/cm' using a machine calender consisting of metal rolls and metal rolls. Time to extrusion coating was 41 hours.

Sample floor 3. : Calendered to a density of 1.03 g/cm" using a machine calender consisting of a metal roll and a metal roll, and then calendered to a density of 1.07 g using a soft calender consisting of a polyether synthetic resin roll and a metal roll.
/cm''. Time to extrusion coating was 23 hours.

Sample NcL4. : Calendered to a density of 1.02 g/cm" using a machine calender consisting of a metal roll and a metal roll. After waiting for 22 hours, a soft calender consisting of a polyether synthetic resin roll and a metal roll was used to achieve a density of 1. Calendered to 0.07 g/cm'' and immediately (20 seconds later) extrusion coated.

Sample floor 5. : Density 0°90g/c by soft calender consisting of polyether synthetic resin roll-metal roll
m'' and then calendered to a density of 1.04 g using a metal roll-to-metal roll machine calender.
/cm'. After waiting for 30 hours, it was calendered to a density of 1.08 g/cm'' using a soft calender consisting of a polyether synthetic resin roll and a metal roll, and immediately thereafter (15 seconds later) extrusion coating was performed.

Table 1 shows the results of evaluating the degree of occurrence of crater-like holes on the surface of the polyolefin coated paper thus obtained.

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

Observe the surface of the polyolefin resin-coated paper in an Icm square area magnified 20 times using a Nippon Kogaku Co., Ltd. universal projector ■-16 model, count the holes with a diameter of 1 mrn (actual measurement: 50 μm) or more, and calculate the average number of craters in the 5 fields of view. Evaluation was made as the degree of occurrence of --shaped holes. If the average number is 20 or more, problems in appearance such as a decrease in gloss will occur when printed on photographic paper.

View-1-Table The results of Table 1 are as follows. In the polyolefin coated paper according to the present invention, the number of crater-like holes is significantly reduced.
．． Photographic printing paper, support for paper, and 7 are very good.

Claims (1)

[Scope of Claims] 1) A method for producing a support for photographic paper in which both sides of base paper are coated with polyolefin, wherein the base paper is coated with polyolefin immediately after calendering between a metal roll and a synthetic resin roll. A method for producing a support for photographic paper, characterized in that: 2) The method for producing a support for photographic paper according to claim 1, wherein the material of the synthetic resin roll used in the calendering process is a polyether resin. 3) The moisture content of the base paper during calendering is 6.0% to 9%, and the surface temperature of the synthetic resin roll is 50°C to 25°C.
The method for producing a support for photographic paper according to claim 1, wherein the temperature is 0°C.