JPH05220747A - Method of removing paper basic material from resin coated paper - Google Patents

Abstract

PURPOSE:To recover independently a resin coated layer and a paper basic material by making holes on the resin coated layer and subsequently irradiating ultrasonic wave thereon while being dipped in liquid having permeability. CONSTITUTION:Resin coated paper 17 is supplied to an up-and-down impulsive punching roller 10 at the same speed as that of a driving roller 2, and a receiving table 11, and it is provided with holes which pierces the paper 17 from the resin coated layer on its back surface to the resin coated layer on its front surface. Next, the punched resin coated paper passes through a forwarding roller 4 and is directed into a water tank 21 filled with liquid 22 having permeability to the paper base material, and then subjected to ultrasonic wave irradiation by an ultrsonic wave oscillator. Then, in the water tank 21 between forwarding rollers 5, 6, ultrasonic irradiation to the separating interfaces of the inside and outside resin coated layers and paper base layer is effected via water by means of ultrasonic oscillators 13, 14, and thereby liquid 22 permeation is promoted from the adhesive interfaces between the resin coated layer and the paper base layer, with result that the inside and outside resin coated layer and paper base material layer become a completely easily separable condition, and also the separating speed is increased.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of peeling a coating layer from a paper coated with a thermoplastic resin on both sides of the paper.

[0002]

2. Description of the Related Art A resin-coated paper such as a photographic printing paper is coated with a thermoplastic resin on both sides for waterproofing. These are processed by applying molten thermoplastic resin to both sides of a paper base material by extrusion coating. Therefore, the resin coating layer, which is a waterproof layer, and the paper substrate should not be peeled off, for example, during the development processing of photographic printing paper, and it is required that the adhesiveness be good.

For this reason, the adhesive strength between the paper base material and the resin layer has been improved by performing activation treatment such as corona treatment or flame treatment in advance. In addition, during the development process, there is also a problem that the developer penetrates from the edge surface of the photographic printing paper, which impairs the beauty of the photographic printing paper. It is also required to have less penetration, and development is performed by adding paraffin wax, rosin, sodium stearate, alkyl ketene dimer (AKD), alkenyl succinic acid (ASA), epoxidized fatty acid amide, polyacrylamide, etc. to paper base materials. Suppresses liquid penetration.

On the other hand, in the process of producing resin-coated paper, when the resin-coated paper that does not become a product is to be recovered and reused, the resin-coated paper itself has high adhesive strength and is difficult for liquid to penetrate. Since it is devised, it is difficult to separate the paper base material and the resin coating layer, and usually, the resin coated paper that is used or does not become a product is often discarded or incinerated,
It is extremely uneconomical.

[0005]

Therefore, attempts have been made to remove the resin coating layer from the paper base material to collect the paper base material. For example, in a milk carton or the like, after soaking in an alkaline solution for several hours, The resin coating layer is peeled off and floated, and the pulp dispersed in the solution is collected and separated (for example, JP-A-62-156368). However, since the resin layer and the paper base material are separated by the permeation of the liquid from the periphery of the resin-coated paper, it takes a long time for the separation, which is not efficient. Further, since it is recovered as pulp dispersed in a solution instead of being recovered in the form of a paper base material, it is limited to a system connected to a papermaking process.

In recent years, in resin-coated paper, it has been demanded to separate and peel the resin-coated paper from the resin-coated layer in the form of a paper substrate to effectively reuse each of the paper substrate and the resin-coated layer. The present inventor has conducted diligent studies to improve such problems, and as a result, when separating the resin coating layer and the paper base material, the adhesive strength of the adhesive surface between the resin coating layer and the paper base material is reduced, and therefore the adhesion thereof is reduced. It has been found that the surface can be easily separated and separated by the presence of a liquid having a permeability to a paper substrate.

[0007]

A method of collecting a paper base material from a resin-coated paper according to the present invention comprises: a resin-coated paper having thermoplastic resin coated on both sides of the paper base material; After piercing a hole penetrating to the paper base, the resin-coated paper is immersed in a liquid having permeability to the paper base while being irradiated with ultrasonic waves, and further, the paper base layer and the resin coating layer are superposed in the liquid. It is characterized by separating while applying a sound wave.

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

Such a 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 a 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 as a running substrate, melting the pellets, and sequentially laminating or by foot block type, 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.

As the paper base material, ordinary natural pulp paper whose main component is natural pulp, mixed paper made of natural pulp and synthetic fiber, synthetic fiber paper whose main component is synthetic fiber, polystyrene, polypropylene and the like are synthesized. 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, and modified products 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 base paper is prepared by using a pulp machine, such as a Fourdrinier paper machine, from a pulp slurry containing the above-mentioned pulp and additives such as a filler, a sizing agent, a paper-strengthening agent, and a fixing agent, which are optionally added. 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} .

The photographic resin-coated paper has antistatic properties,
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 to form color photographic photographic paper, black and white photographic photographic paper, typesetting photographic paper, copy 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.

In the present invention, such a resin-coated paper is prepared by first forming a hole in the resin-coating layer so as to penetrate to the paper base material, and then the resin-coated paper is a liquid having permeability to the paper base material. It is characterized in that it is irradiated with ultrasonic waves while being dipped in.

The size of the pins penetrating the resin coating layer and the number of pins per unit area are involved in promoting the permeation of the liquid into the paper base material, that is, reducing the adhesive strength between the paper base material and the thermoplastic resin. Is an important factor. This factor depends on the water immersion speed and size of the paper substrate, and the hole diameter also depends on the viscoelasticity of the thermoplastic resin used, the melt index, and the Young's modulus. In addition, when a hole is punched, the resin piece corresponding to the hole is peeled off from the resin coating layer, and after peeling and separating the paper base material and the resin coating layer, there is a risk that the peeled piece may contaminate the paper base material side. There is also a nature. Therefore,
Since the number depends on the type of paper base material and thermoplastic resin used, perforation speed, etc., it is desirable to determine the number of perforations and the diameter of perforations by experiments under the conditions of implementation. The drilling jig is
It is better to use one with many sharp needle-shaped pins,
A pinhole that penetrates through the resin coating layer to reach the paper base material layer is punched, and may be of a die type that is punched by vertical movement, or may be a roll-shaped rotary punching type that is continuous in any case. Those that can be perforated are preferred.

Further, a liquid having penetrability into the paper base material that permeates through the perforated portion of the resin cover layer and reduces the adhesive strength between the paper base material layer and the resin cover layer, the permeation speed affects the separation treatment speed. Since it greatly affects the wettability of the resin coating layer and the paper base layer, it is preferable to cut the hydrogen bond between the paper base and the resin coating layer. Examples thereof include water, hot water, steam, organic compounds having a carboxyl group or a hydroxyl group, or salt compounds thereof. Specific examples of those having a carboxyl group include acetic acid and salicylic acid.
Further, those having a hydroxyl group are water-soluble organic solvents such as methanol, ethanol, propanol and glycerin. In addition, there are organic solvents such as benzene, toluene, xylene, etc., caustic soda aqueous solution, etc. that weaken the anchoring effect between the paper base material and the resin coating layer. Not limited to.

Considering from another point of view, as a material to be applied to a paper base material, the resin coating layer is easily wetted and penetrates into the paper base material through the perforations, so that it is excellent in surface tension and penetration wetness to the paper base material. Things are required. Further, from another point of view, it penetrates into the paper base material, easily evaporates, and separates from the resin coating layer,
It is necessary to facilitate the drying of the paper base material after peeling, have no influence on the surrounding environment of the processing step of the present invention, and consider the economical efficiency.

As a method of supplying the permeating liquid to the perforated resin-coated paper, the perforated resin-coated paper may be immersed in a container filled with the permeating liquid, or the perforated resin-coated surface may be slit or porous. You may supply by the nozzle which has. In any case, it is important that the perforated part of the resin coating layer be covered with the penetrant liquid. When the permeation treatment step is carried out under ultrasonic irradiation, the permeation rate is further promoted, and the time required for easy separation can be shortened and the permeation treatment step can be shortened.

However, in order to completely prevent the paper base material from remaining in the resin film layer, it is necessary to sufficiently permeate and diffuse the liquid into the paper base material layer, and the liquid is perforated. It takes some time to penetrate further, diffuse into the paper substrate, and reach the adhesive interface. For this reason, in order to separate the paper base material without remaining in the resin coating layer, it is necessary to lengthen the time for immersing the resin coated paper in the liquid, which makes the dipping device itself longer and After separating and peeling the layers, there is a problem that extra energy is required to dry the liquid that has penetrated into the paper base layer.

Therefore, in the present invention, the step of separating the paper base material layer and the resin coating layer subsequent to the above-mentioned step is performed by irradiating with ultrasonic waves in a liquid having permeability to the paper base material. This makes it possible to promote penetration into the adhesive interface between the paper base material layer and the resin coating layer, further increase the peeling speed, and increase the length of the dipping device and the amount of penetrating liquid. We have found that it can be improved.

The ultrasonic irradiation at this stage is performed at a frequency of 10 to 10.
The frequency is preferably 40 KHz and the amplitude of the ultrasonic transducer is 5 to 50 μm, but the condition is not limited to this. The strength of the ultrasonic wave and the irradiation time are important factors for promoting the penetration of the liquid. Therefore, the frequency, amplitude, and
Since it largely depends on the clearance between the ultrasonic oscillator and the peeling interface, it is desirable to determine it by experiments under the conditions under which it is carried out.

Since the method of the present invention is a method of lowering the adhesive strength between the paper base material and the resin coating layer due to liquid permeation through the perforated portion of the resin coating layer and separating and peeling the paper base material and the resin coating layer, The shape of the resin-coated paper to be treated, that is, sheet-shaped or roll-shaped resin-coated paper is not affected,
It is possible to handle continuously. For sheet-like ones, use one by one, for example, the same type of thermoplastic resin tape as the resin coating layer, and splice it with the same type of tape as the resin coated surface by heat welding or ultrasonic welding. , Continuous handling in continuous sheet form, continuous perforation, liquid penetration, and peeling are possible, including the spliced part. In addition, contamination of dissimilar materials on the separated and peeled resin coating layer is also possible. Not recoverable.

[0029]

In the present invention, the detailed mechanism by which the adhesive force between the paper base material and the resin coating layer is lowered to enable easy separation is not clarified, but the number of perforations in the resin coating layer is increased. As a result, the permeation of the liquid having penetrability into the paper substrate is promoted thereafter, and the ultrasonic irradiation to the adhesive interface promotes the permeation of the adhesive interface between the paper substrate layer and the resin coating layer into the paper substrate. It is considered that, as a result of the permeation of the liquid, the adhesive force related to the hydrogen bond between the material layer and the resin coating layer is significantly reduced due to the breaking of the hydrogen bond, and the adhesive force is easily peeled off.

Further, the separation rate can be increased by separating the paper base material and the resin coating layer in a liquid having permeability to the paper base material while irradiating with ultrasonic waves.

Although the detailed mechanism thereof is still unknown, the micro fluid motion of the liquid having the permeability to the paper base material from the vicinity of the adhesive interface is promoted, and the adhesion between the paper base material layer and the resin coating layer is promoted. It is considered that the hydrogen bond, which is increasing the force, is broken by the increase of the permeation rate due to the kinetic energy of the liquid, the adhesive force between the paper base layer and the resin coating layer is reduced, and the peeling is easily and quickly performed.

In the present invention, the use of an organic solvent as the penetrant liquid makes it possible to make the penetrant liquid contained in the paper base material in a low-wetting state. Since it is possible to make the water content of the paper base material equivalent to that of the conventional method, like the conventional method, the resin coating layer floated due to the difference in specific gravity and the paper base material itself are dispersed in a solution, and the conventional method of collecting and separating as a pulp liquid is Essentially different.

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

[0034]

Example 1 The resin-coated paper used in the separation of the paper base material and the resin coating layer in this example was a roll having a width of 35.6 cm, which did not become a product in the production process before the application of the photosensitive emulsion. It is a resin-coated paper for photographic printing paper, and its constitution is shown in [Table 1] below.

[0035]

[Table 1]

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 10% by weight of the white pigment, LBSP is hardwood beaten sulfite pulp, LBK
P is hardwood beaten kraft pulp, paper base is LBSP6
HDPE in the back side layer is a high density polyethylene (density 0.970 g / cm ³ ) with a melt flow rate of 15%, and LDP is LDP 40%.
E / HDPE = 2: 3 (weight ratio).

The peeling of the resin coating layer and the paper base layer in this resin coated paper will be described with reference to FIG. In the figure, 1, 3 ~
9 is a transport roll, 2 is a drive roll, 10 is a perforation roll,
11 is the pedestal, 12 to 14 are ultrasonic transducers, 15 to 1
6 is a peeling blade, 17 is double-sided resin coated paper, 18, 2
Reference numeral 0 denotes a resin coating layer, 19 denotes a paper base material, 21 denotes a water tank, and 22 denotes a liquid having penetrability into the paper base material.

First, the resin-coated paper 17 is composed of a vertical sliding perforation roll 10 whose speed is linked with the driving roll 2 and its pedestal 1.
1 and a hole penetrating from the resin coating layer on the back surface to the resin coating layer on the front surface is drilled. Next, the perforated resin-coated paper passes through the transport roll 4 and is guided into the water tank 21 containing the water 22.

While being conveyed by the conveying rolls 4 and 5 in the water tank, the surface of the resin-coated paper is ultrasonically irradiated by the ultrasonic vibrator 12 through water. The ultrasonic vibrator here had a frequency of 20 KHz and an amplitude of 20 μm, and was irradiated with ultrasonic waves. In this step, the water 22 permeates the paper base material through the through-holes through the resin coating layer, and further the ultrasonic irradiation accelerates the permeation and diffusion of the water into the paper base material. The adhesive strength with is significantly weakened.

Next, the water tank 21 between the transfer rolls 5 and 6
In the inside, the peeling interface between the front and back resin coating layers and the paper base material layer is ultrasonically irradiated with ultrasonic waves by the ultrasonic transducers 13 and 14 from the adhesive interface between the resin coating layer and the paper base material layer. The penetration of the water 22 is promoted, the front and back resin coating layers and the paper base material layer are completely in a state of easy peeling, and the peeling speed can be increased.

By the peeling blades 15 and 16, the peeling angle between the resin coating layer and the paper base layer can be made constant,
In addition, the clearance between the ultrasonic transducer and the peeling interface can be maintained at a set value of 5 mm, and uniform peeling can be achieved. Subsequently, the back resin coating layer 18, the paper base material layer 19, and the front resin coating layer 20 are separated from the peeling blades 15 and 16 as starting points and continuously guided to the transport rolls 6, 7, 8 and 9, respectively. The resin coating layer had no paper, and the separation and peeling speed was 30 m / min, and the peeling and separation treatment could be performed.

However, at the first separation and peeling start point of the resin coating layer, at the start point of the peeling, the resin layer and the paper base material layer after the peeling by the peeling blades and the transport rolls 6, 7, 8 and 9 are performed, that is, at the start. It is necessary to separate and separate the paper base layer and the resin coating layer and to guide each layer to the winding machine. In addition, although this operation is not explicitly shown, it goes without saying that the peeling and separation starting method can also be automated.

[0043]

[Example 2] In Example 1, the water tank was filled with methanol (20 to 50 ° C) instead of water, and the others were used in Example 1
Using the above process, an attempt was made to peel the same resin-coated paper as in Example 1. As a result, the resin layer and the paper substrate can be completely peeled off,
The treatment speed is about 2 as compared with the method using water in Example 1.
It could be peeled and separated at a double speed of 60 m / min.

[0044]

EXAMPLE 3 In Example 1, the water tank was filled with xylene (60 to 90 ° C.) instead of water, and the process of Example 1 was used otherwise, and the same resin-coated paper as in Example 1 was peeled off. .. As a result, the resin layer and the paper base material could be completely peeled off, and could be peeled off and separated at a processing speed of 40 m / min.

[0045]

According to the present invention, the resin layer and the paper substrate can be efficiently, continuously and easily peeled from the double-sided resin-coated paper which cannot be reused economically and effectively in the past. The resin coating layer and the paper substrate can be recovered independently,
The industrial value is extremely large.

[Brief description of drawings]

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

[Simple explanation of symbols]

In the figure, 1, 3 to 9 ... Conveying rolls, 2 ... Driving rolls, 10
... perforation roll, 11 ... perforation roll pedestal, 12-14 ... ultrasonic transducer, 15-16 ... peeling blade, 17 ... double-sided resin-coated paper, 18,20 ... resin coating layer, 19 ... paper base material,
21 ... Water tank, 22 ... Liquid having permeability to paper base material.

Claims (1)

[Claims] 1. A resin-coated paper having a thermoplastic resin coated on both sides of the paper substrate is preliminarily provided with a hole through the resin-coated layer to reach the paper substrate, and then the resin-coated paper is penetrated into the paper substrate. While irradiating with ultrasonic waves while immersing in a liquid having a property,
A method for collecting a paper base material from a resin-coated paper, characterized in that the paper base material layer and the resin coating layer are separated in the liquid while being irradiated with ultrasonic waves.