JPH05177635A - Method for collecting paper substrate from resin coated paper - Google Patents

Abstract

PURPOSE:To recover efficiently and continuously a coating layer and a substrate layer separately by boring holes reaching a paper substrate in at least one coating layer of resin-coated paper the both sides of which are coated with a thermoplastic resin and by penetrating a liquid having permeability to the paper substrate. CONSTITUTION:In a paper sheet the both side of which are coated with a resin, through holes reaching a paper substrate are bored using a boring jig having sharp needle pins. The boring jig of a die form or of a rotary boring type of a roller form can bore the through holes continuously. The coating layer is stripped and separated by penetrating a permeable liquid from the through holes by such a method of immersing in the permeable liquid. The permeation is accelerated by the radiation of an ultrasonic wave. A coated paper sheet, for example, is formed in a continuous sheet by jointing with a tape of the same kind with a coating layer, etc., to be treated continuously. As the permeable liquid, hot water, water soluble organic solvents such as methanol, or other organic solvents including benzene, toluene, and xylene can be used.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for peeling a thermoplastic resin coating layer from a paper base of a resin coated paper whose both sides are coated with a thermoplastic resin layer. More specifically, the resin coating layer is provided with a through hole reaching the paper base material, and hot water, steam or methanol, ethanol,
Water-soluble organic solvent such as propanol or organic solvent such as benzene, toluene, xylene is permeated into the paper substrate,
It is intended to provide a method for separating a paper base material layer and a resin coating layer to separate them.

[0002]

2. Description of the Related Art Generally, milk, fruit juice, liquor packs, photographic printing paper and the like are coated with a thermoplastic resin for waterproofing purposes. These are produced by melting and extruding a thermoplastic resin on both sides of the paper base material, but the adhesiveness between the resin coating layer, which is the waterproof layer, and the paper base material is important. Particularly, good adhesiveness is required during the development processing of photographic paper. For this reason, the adhesive strength has been improved by activating the paper base material such as corona treatment or flame treatment.

On the other hand, when the used resin-coated paper or the resin-coated paper that does not become a product in the process of producing the resin-coated paper is collected and reused, the paper base material and the resin-coated layer are separated from each other. Since the adhesive strength is strong, it becomes difficult to separate the paper base material and the resin coating layer, and the waste materials are usually discarded and incinerated, which is extremely uneconomical.

[0004]

In recent years, resin-coated paper has been separated from the resin-coated paper in the form of a paper substrate for easy handling, and the paper substrate and the resin-coated layer can be effectively reused. Is required.

Therefore, conventionally, a method of separating the resin coating layer from the paper base material and using the paper base material has been put into practical use. For example, there is one in which a milk carton is immersed in an alkaline solution for several hours to float and remove the resin coating layer, and the pulp dispersed in the solution is collected and collected (for example, JP-A-62-156).
No. 378).

This is because the resin coating layer and the paper base material are separated by permeation of the liquid into the paper base material from the periphery of the resin-coated paper, and therefore the time required for the liquid to permeate the paper base material. It is not efficient. Moreover, in order to eliminate the contamination between the resin coating layer and the paper layer, the floating separation operation in the solution is carried out for 2-3 times.
It is not efficient because it requires repetition. Further, it is not economically recovered because it is recovered in the form of pulp that has sufficiently absorbed the solution rather than being recovered in the form of a paper base material, and when reused as dry pulp, it requires a large amount of dry heat energy or When reused as wet pulp,
There is a drawback that the separation processing place is limited to the system arrangement linked to the papermaking process.

In the present invention, as a result of intensive studies aimed at improving the above-mentioned problems, a liquid having penetrability of a paper base material is used to reduce the adhesive strength between the resin coating layer and the adhesive surface of the paper base material. As a result, they have found that the resin coating layer and the paper substrate are easily separated from each other, and have reached the present invention. The present invention solves these problems,
It is an object of the present invention to provide a method for peeling a novel paper base material and a resin coating layer.

[0008]

DISCLOSURE OF THE INVENTION The present invention has been found as a result of diligent studies for easily peeling and separating a paper base material and a resin coating layer in a double-sided resin coated paper. Prior to the peeling of the layer, a hole penetrating at least one of the resin coating layers is formed, and a liquid having penetrability into the paper base material such as hot water, steam and a water-soluble organic solvent is applied to the paper base material through the through hole. It was found that the paper base material and the resin coating layer can be easily peeled and separated by permeation.

The resin-coated paper to which the present invention is applied is not particularly limited, such as a milk carton, but is particularly suitable for separating the paper base material and the resin layer in the photographic resin-coated paper.

Such resin-coated paper will be described below.

As the coating resin, polyolefin such as polyethylene, polypropylene, polyethylene copolymer, etc., and particularly preferably polyethylene is used. As the polyethylene, high density polyethylene, low density polyethylene, linear low density polyethylene and blends of these polyethylenes can be used. The melt flow rate (hereinafter referred to as MFR) of polyolefin resin before processing is JIS
1.2 g as measured under condition 4 of Table 1 of K 7210
/ 10 minutes to 30 g / 10 minutes.

The titanium dioxide (TiO ₂ ) which is the white pigment contained in the resin layer may be either anatase type or rutile type, but when priority is given to whiteness, anatase type TiO ₂ is used, and sharpness is When giving priority, rutile TiO ₂ is preferable. TiO ₂ is a metal salt of higher fatty acid,
The higher fatty acid ethyl, the higher fatty acid amide, the higher fatty acid and the like are used as a dispersion aid, and the mixture is kneaded into the resin with a kneading machine such as a two-roll, three-roll, kneader or Banbury mixer. The TiO ₂ concentration in the pellet is generally 3
It is about 0 wt% to 75 wt%. An antioxidant may be contained in the resin layer, and the content may be 50 ppm to 1000 ppm based on the amount of the water resistant resin.

The resin layer is obtained by diluting pellets containing titanium dioxide or the like with a heat-resistant resin as needed on paper or synthetic paper which is a running substrate, melting the pellets, and sequentially laminating or by using a foot block type or multi-layer. It is formed by coating by any one of a lamination method using a manifold type or a multi-slot type multilayer extrusion die. The shape of the multilayer extrusion die is generally a T die, a coat hanger die or the like, and is not particularly limited. The outlet temperature of the resin during heat melt extrusion is usually 280 ° C to 350 ° C, particularly preferably 310 ° C to 330 ° C. In addition, before coating the substrate with the resin, the substrate is subjected to corona discharge treatment, flame treatment,
Activation treatment such as glow discharge treatment is performed.

The surface of the outermost layer of the resin on which the emulsion is coated is
A glossy surface or a fine surface, a matte surface or a silk surface as described in JP-A-55-26507 is imprinted, and a back surface is matte. An activation treatment such as a corona discharge treatment or a fire treatment can be applied to the surface after molding, and after the activation treatment, an undercoating treatment as described in JP-A-61-84643 is performed.

The total thickness of the resin layer is generally 10 μm to 70 μm.
μm, and in the case of a multi-layered structure, each layer is 2 μm to
It is 30 μm.

The paper base material is a natural pulp paper containing natural pulp as a main component, a mixed paper consisting of natural pulp and synthetic fibers, a synthetic fiber paper containing synthetic fibers as a main component, a synthetic material such as polystyrene or polypropylene. Although any of so-called synthetic papers obtained by making a resin film into a pseudo paper may be used, natural pulp paper (hereinafter, simply referred to as base paper) is particularly preferably and advantageously used as a base material of the polyolefin resin-coated paper for photographic printing paper. As additive chemicals, in addition to alkyl ketene dimer, fillers such as clay, talc, calcium carbonate, urea resin fine particles, rosin, higher fatty acid salts, paraffin wax, sizing agents such as alkenyl succinic acid, paper strengthening agents such as polyacrylamide The one to which a fixing agent such as sulfuric acid band is added is used. In addition, dyes, fluorescent dyes, slime control agents, defoaming agents, etc. are added as necessary. Further, a softening agent is added if necessary.

The surface of the pulp can be surface-sized with a film-forming polymer such as gelatin, starch, carboxymethyl cellulose, polyacrylamide, polyvinyl alcohol, or a modified product of polyvinyl alcohol. In this case, as the polyvinyl alcohol modified product,
Examples thereof include carboxyl group-modified products, silanol-modified products and copolymers with acrylamide. Further, the coating amount of the film-forming polymer when the surface is sized by the film-forming polymer is 0.1 g / m ^{2 to} 5.0 g / m ² , preferably 0.5 g / m ^{2 to} 2.0 g / m ^2. Adjusted to.
Further, an antistatic agent, a fluorescent whitening agent, a pigment, an antifoaming agent and the like can be added to the film forming polymer at this time, if necessary.

The raw paper is prepared by pulp pulp slurry containing the above-mentioned pulp and additives such as fillers, sizing agents, paper-strengthening agents and fixing agents, which are optionally added, by a paper machine such as a Fourdrinier paper machine. Manufactured by paper making, drying and winding. The surface size treatment is performed before or after the drying, and the calender treatment is performed between the drying and the winding. When 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 preferable to carry out the calendering treatment in the final finishing step after various treatments have been carried out. .. In the calendering process, known metal rolls and elastic rolls which are commonly used in the production of paper are used. The base paper is calendered as described above and finally adjusted to a film thickness of 50 μm to 250 μm. The density of the base paper ^{0.8g / cm 3 ~1.3g / cm 3} , preferably from ^{1.0g / cm 3 ~1.2g / cm 3} .

Further, the resin coated paper for photography has antistatic property,
Various back coat layers are coated to prevent curling. In addition, as the back coat layer, Japanese Patent Publication No. 52-1802
No. 0, JP-B 57-9059, JP-B 57-5394
No. 0, JP-B-58-56859, JP-A-59-2
Inorganic antistatic agents, organic antistatic agents, hydrophilic binders, latexes, curing agents, pigments, surfactants and the like described or exemplified in JP-A No. 14849, JP-A-58-184144 and the like are contained in appropriate combination. be able to.

As the resin coated paper for photographic use, various photographic constituent layers are coated and used for color photographic photographic paper, black and white photographic photographic paper, typesetting photographic paper, transferred photographic paper, reversal photographic material, silver. Salt diffusion transfer method Used for various purposes such as negative and positive, printing materials, silver chloride, silver bromide, silver chlorobromide,
A silver iodobromide and silver chloroiodobromide emulsion layer is provided, and the silver halide photographic emulsion layer contains a color coupler to form a multilayer silver halide color photographic constituent layer.
Further, a silver salt diffusion transfer image-receiving layer is provided by containing a physical phenomenon nucleus.

According to the present invention, in such a double-sided resin-coated paper, a through hole that penetrates the resin coating layer and reaches the paper base material layer is punched by a punching jig having sharp needle-shaped pins. Penetration of liquid having permeability such as hot water, water-soluble organic solvent such as steam, methanol, ethanol, propanol or organic solvent such as benzene, toluene, xylene into the paper base layer A method for separating and separating a paper base material and a resin coating layer is provided.

The size of the holes penetrating the resin coating layer and the number of holes per unit area are such that the more the penetrating liquid penetrates the paper substrate layer, that is, the adhesive strength between the paper substrate and the thermoplastic resin coating layer. Is an important factor. This factor depends on the pulp type, sizing degree, density, etc. of the paper base material, and is greatly influenced by the size of the holes and the number per unit area.

On the other hand, the size of the hole also depends on the type of thermoplastic resin, viscoelasticity, Young's modulus, and the like. Moreover, when a hole is formed in the resin coating layer, the resin piece corresponding to the hole is peeled off,
There may be a problem of contamination such as peeling off of the resin coating layer and mixing of the peeled resin pieces on the separated paper substrate side.

Therefore, it is desirable to determine the perforation diameter and the perforation rate by an experiment under the conditions to be carried out, since it depends on the kind, the physical properties, the perforation rate and the like of the paper base material and the thermoplastic resin used for the peeling treatment.

The punching jig may be of a die shape and punched by vertical movement, or may be a roll-shaped rotary punching type, and in any case, continuous punching is possible. With respect to the through holes of the resin-coated paper, holes may be penetrated to the front and back resin coating layers, or holes may be separately formed on the front and back sides to penetrate the paper base layer or the resin coating layer on the opposite side. However, it depends on the number and size of the through holes, the permeation rate and the permeation amount of the paper base material of the liquid that has permeability to the paper base material, and is appropriate for the ease of peeling the paper base material from the resin coating layer. There seems to be a relationship. That is, since the paper base material and the resin coating layer are separated and separated from each other by a tensile force on the respective release surfaces, the paper base material is wet or the resin coating layer has through holes, so that the separation is performed. This is because there is a problem in that cutting cannot be performed against the tensile force of 1. Therefore, it depends on the thickness, wettability, and permeability of the resin-coated paper to be treated, and therefore it is desirable to determine how to make the through-holes by experiments under the conditions to be carried out.

Although depending on the type and thickness of the resin coating layer, it is also possible to generate the through holes by corona discharge treatment of the resin coating layer.

Further, for liquids that permeate through the through holes of the resin coating layer and reduce the adhesive strength between the paper base material and the resin coating layer, the permeation rate affects the peeling treatment speed, and the liquid coating layer and the paper base material are affected. Considering from the viewpoint of being greatly affected by the wetting property, it is preferable to break the hydrogen bond between the paper substrate and the resin coating layer. For example, water, a water-soluble compound having a carboxyl group and a hydroxyl group, a chloride thereof, or the like. Specifically, examples of compounds having a carboxyl group include acetic acid and salicylic acid. Examples of those having a hydroxyl group include water-soluble organic solvents such as methanol, ethanol and propanol. In addition, examples of a material that weakens the anchoring effect between the paper base material layer and the resin coating layer include organic solvents such as benzene, toluene, xylene, and a caustic soda aqueous solution, but are not limited to the above substances.

From another point of view, as a material to be applied to the paper base material, the resin coating layer is easily wetted and penetrates into the paper base material through the through holes, so that it is excellent in surface tension and penetration wetness to the paper base material. What is required is required. Furthermore, from another perspective,
The paper base material that has penetrated into the paper base material, peeled off from the resin coating layer, and separated from the paper base material is easily evaporated and dried, so that the surrounding environment of the treatment process is not affected and the economical efficiency must be considered.

As a method of supplying the penetrating liquid to the perforated resin-coated paper, the resin-coated paper having the through holes may be immersed in a container filled with the permeating liquid. You may supply by the nozzle which has a slit or a porous in the resin coating surface. In any case, it is important that the perforated portion of the resin coating layer be covered with the penetrant liquid.
In addition, the permeation rate at which the penetrant permeates the paper base material through the through-holes is further enhanced by ultrasonic irradiation.
The desirable knowledge that the time until peeling can be shortened and the peeling speed can be increased, and the peeling process step can be shortened and the efficiency can be improved was obtained.

The present invention is a method for peeling and separating the paper base material and the resin coating layer by reducing the adhesive strength between the paper base material and the coating resin layer due to liquid penetration from the perforated portion of the resin coating layer, The shape of the resin-coated paper to be used for, that is, the sheet-shaped or roll-shaped resin-coated paper is not affected,
It is possible to handle continuously. For sheet-like ones, one by one, for example, a thermoplastic resin tape-like one similar to the resin coating layer is used, and the resin-coated surfaces such as heat pressure fusion or ultrasonic fusion are joined together. Can be handled as a continuous sheet, and it is possible to continuously perforate, liquid-penetrate, and exfoliate including the spliced part. In addition, exfoliation, mixing of different materials into the separated resin coating layer, and contamination It can be recovered without.

[0031]

In the present invention, the detailed mechanism of facilitating the peeling of the paper base material and the resin coating layer has not yet been clarified. However, by increasing the number of perforations in the resin coating layer, hot water, steam, The water-soluble organic solvent such as methanol, ethanol, propanol, or the liquid having permeability such as organic solvent such as benzene, toluene, xylene, etc. increases the permeation rate and the permeation rate. As a result of the penetration of the liquid having the above-mentioned permeability, the adhesive strength related to the bonding and anchoring effect, the anchoring adhesive strength due to the wet expansion deformation of the paper substrate and the significant decrease in the adhesive strength due to the breaking of hydrogen bond is extremely weakened, It is considered that the paper base material and the resin coating layer are easily separated.

The present invention also makes it possible to bring the penetrant liquid contained in the paper base material into a low-humidity state by using an organic solvent as the penetrant liquid. Since the paper base material can contain water, the method of impregnating the liquid floating resin coating layer and the paper base material itself into the liquid for a long time by the specific gravity difference, which is a conventional method, and collecting and separating as pulp is essentially Differ.

The present invention will be described in detail below with reference to examples.

First, the constitution of the resin-coated paper used in the examples is shown in the table below.

[0035]

[Table 1]

In the figure, * a is a resin-coated paper for roll-shaped photographic printing paper that did not become a product in the production process before the application of the photosensitive emulsion, and * b is a hand size (8.3 × 10.8 mm) Color print paper.

In the table, LDPE in the surface layer is low density polyethylene having a melt flow rate of 3.5 (density of 0.
920 g / cm ³ ), the white pigment is Ishihara Sangyo Co., Ltd., trade name A-220), containing 15% by weight of white pigment, LBSP is hardwood beating sulfite pulp, LBK
P is hardwood beaten kraft pulp, paper base is LBSP6
0%, LBKP 40% mixed papermaking, and HDPE in the back surface layer is high density polyethylene (density 0.970 g / cm ³ ) having a melt flow rate of 15,
LDPE / HDPE = 2: 3 (weight ratio).

[0038]

Example 1 Peeling between the resin coating layer and the paper base layer of the two types of resin coated paper shown in Table 1 was tried as follows. This will be described with reference to FIGS. 1 and 2. In FIG. 1, 1 and 3 to 10 are transport rolls, 2 is a drive roll, 11 is a punching die, 12 is a die stand, 13 is a liquid tank, 14 is an ultrasonic vibrator, and 15 is a permeability to a paper substrate. Liquid, 20 is double-sided resin coated paper, 21,
Reference numeral 23 denotes a resin coating layer and 22 denotes a paper base material.
Among these, 31 is a sheet-shaped resin-coated paper, 32 and 33 are tapes obtained by cutting the peeled resin-coated layer, 34 is an ultrasonic bonding machine,
Denoted at 35 are the respective pedestals.

The roll-shaped resin-coated paper 20 for photographic printing paper of the resin-coated paper 1 in Table 1 is a vertical motion type punching die 11 and its pedestal 12 which are linked in speed with the driving roll 2 and has a resin coating on the back surface. Make a through hole in the layer. The resin coating layer perforated from the back side passes through the transport roll 4 and is introduced into the liquid layer 13.
In the liquid layer, hot water 15 is temperature-controlled at 95 to 100 ° C. In the liquid layer, the resin-coated paper is ultrasonically radiated through the liquid to the resin-coated surface that has been perforated by the ultrasonic vibrator 14 between the transport rolls 3 and 4. During this time, in the resin-coated paper, the penetration of hot water through the through holes into the paper base material and the penetration and diffusion of the liquid by ultrasonic irradiation are promoted, and the adhesive strength between the front and back resin coating layers and the paper base material is significantly weakened. As a result, the front and back resin coating layers and the paper base material can be completely peeled off easily. Subsequently, starting from the pressing rolls 6 and 7, the back resin coating layer, the paper base layer,
The surface resin coating layer and the transport rolls 21, 22 and 23 are separated and guided continuously. In this case, the peeling / separating speed was 8 m / min, and the peeling / separating treatment was completed.

However, at the first separation and separation start point of the resin coating layer, the separation blade and the resin layer after separation by the transfer rolls 6, 7, 8 and 9 and the paper base material layer passwork treatment, that is,
At the start, it is necessary to separate / separate the resin layer from the paper substrate and guide each layer to the winding machine. Also,
Although this operation is not explicitly shown, it goes without saying that the peeling and separation starting method can also be automated.

[0041]

Example 2 In Example 1, the liquid layer was filled with methanol (20 to 50 ° C.) instead of hot water, and the process of Example 1 was used otherwise, and a roll-shaped photographic printing of the resin-coated paper 1 was performed. An attempt was made to peel the resin-coated paper for paper. As a result, it was possible to completely peel and to peel and separate at a processing speed of 42 m / min which was about 5 times.

[0042]

[Third Embodiment] First, in FIG. 2, a tape 32 is prepared from the sheet-shaped color paper 31 of resin-coated paper shown in Table 1 by using the same kind as the front and back resin coating layers. While continuously joining one by one with the pedestal 35, with the back resin-coated surface facing up in FIG. 1 and being guided to the transport roll 20, the same punching treatment as in Example 1 was performed with a punching die.
The hot water layer was subjected to ultrasonic irradiation treatment, and the paper base material and the front and back resin coating layers were separated and separated. The processing speed was 8 m / min, which was the same as in Example 1, and peeling and separation were possible.
At this time, the paper base material was not properly conveyed between the pressing rolls 6 and 7 and the conveying roll 9. During this time, the paper base material that is peeled and separated into a sheet shape is driven at the same speed as the processing step. With the slight improvement that the paper substrate is conveyed while receiving it, the separation and conveyance after peeling the paper substrate can be processed without problems.

[0043]

Example 4 In Example 1, the liquid layer was filled with xylene (60 to 90 ° C.) instead of hot water, and the process of Example 1 was used otherwise, and resin-coated paper 1 roll-shaped photographic printing paper was used. Attempts were made to peel off the resin-coated paper for use in the production. As a result, it could be completely peeled off, and at the processing speed of 10 m / min, peeling and separation could be performed.

[0044]

INDUSTRIAL APPLICABILITY According to the present invention, a double-sided resin-coated paper which has not been economically and effectively reused up to now can be peeled efficiently, continuously and easily, and the resin-coated layer and the paper substrate can be separated from each other. Since it can be recovered independently, its industrial value is extremely large.

[Brief description of drawings]

FIG. 1 is a schematic explanatory view showing an example of an embodiment of the method of the present invention.

FIG. 2 is a schematic explanatory view for explaining a part of an embodiment of the method of the present invention.

[Short description of reference numerals] 1, 3 to 10 ... Conveying roll 2 ...
Drive roll 11 ... Drilling die 12 ... Die cradle 1
3 ... Liquid layer 14 ... Ultrasonic transducer 15 ... Penetrating liquid 2
0 ... Roll-shaped resin-coated paper 21 ... Resin coating layer 22 ... Paper base material 23 ... Resin coating layer 32, 33 ... Resin coating layer tape 34 ... Ultrasonic bonding machine 35 ... Ultrasonic bonding machine pedestal

Claims (1)

[Claims] 1. A resin-coated paper having a thermoplastic resin coated on both sides of a paper substrate, wherein at least one resin coating layer has a hole penetrating to the paper substrate, and then has permeability to the paper substrate. A method for collecting a paper base material from a resin-coated paper, which comprises allowing the liquid to permeate the paper base material through the holes and then peeling off the resin coating layer from the paper base material layer.