KR20230074967A - Manufacturing method of paper with film attached thereto and product using the same - Google Patents

Abstract

Disclosed is a method for manufacturing paper attached with a film, which comprises: a step of: (a) forming a pulp stock containing a miscible additive; (b) a papermaking step of manufacturing paper using a papermaking machine from the stock containing a miscible additive; (c) a step of drying the paper; and (d) a step of heat-pressing a film on the dried paper. The miscible additive is made of a material that is miscible with the film material. According to the present invention, it is possible to manufacture paper attached with a film through a simple process and excellent adhesion without using an adhesive.

Description

Method for manufacturing paper with film attached and product using the same {MANUFACTURING METHOD OF PAPER WITH FILM ATTACHED THERETO AND PRODUCT USING THE SAME}

The present invention relates to a method for manufacturing paper with a film attached thereto and a product using the same. Specifically, the paper is prepared by adding plastic powder or fibers miscible with the film in the paper stock process, and then the film is thermally compressed to form a film without an adhesive. It relates to a technique for producing this adhered paper.

As the use of plastic disposable products increases, the problem of environmental pollution due to the discharge of plastic waste has become a serious problem. Plastic disposables are mostly made of general-purpose polymers such as PE (Polyethylene), PP (Polypropylene), PC (Polycarbonate), etc. These materials do not rot even when buried in the ground and generate high heat or harmful gases even when burned, so it is difficult to dispose of them. there is Therefore, attention is being focused on the development of materials that can replace plastics.

Recently, paper molded products using paper (pulp), which has a faster natural decomposition rate than plastic, have been proposed as a technology to replace plastic products. However, paper is weak in mechanical properties, oxygen barrier properties, and moisture barrier properties compared to plastic, and thus is insufficient to replace plastic.

In order to compensate for the limitations of these physical properties of paper, a technique is known in which a film such as PE (Poly Ethylene) or PLA (Poly Lactic Acid) is attached and used after paper is manufactured. When a film is attached to paper, oxygen barrier properties or moisture barrier properties can be supplemented by the film.

On the other hand, an adhesive is required to attach the film to paper, and the use of the adhesive not only increases the manufacturing cost of paper products, but also acts as a factor in reducing the recyclability and eco-friendliness of the material.

Korean Patent Registration No. 1110423 discloses a technique of laminating a PLA film on paper without using an adhesive. However, the technology disclosed in the above prior literature uses a method of heating the paper stock in several steps, melting the PLA resin film, and then pressing and laminating, so that the process is complicated and the adhesive strength is limited.

Therefore, it is required to develop a technology for attaching a film to paper with a simple process and excellent adhesive strength without using an adhesive.

Korean Registered Patent Publication No. 1110423 (2012.01.19)

The present invention is to solve the problems of the prior art as described above, and an object of the present invention is to provide a paper attached to a film with a simple process and excellent adhesive strength without using an adhesive.

In addition, another object of the present invention is to provide a film to which a film is attached with excellent adhesive strength even when the attaching process is performed at a relatively low temperature to the extent that the film to be attached is not deformed or damaged.

The object of the present invention is not limited to the above, and other objects and advantages of the present invention not mentioned can be understood by the following description.

In order to achieve the above object, a method for manufacturing paper with a film attached thereto according to an embodiment of the present invention includes (a) forming a pulp stock containing a miscible additive, (b) including the miscible additive. A papermaking step of producing paper from stock using a papermaking machine, (c) drying the paper, and (d) thermally compressing a film on the dried paper, wherein the miscible additive is mixed with the film material. It is characterized by being made of a miscible material.

At this time, the step (a) includes (a-1) dissociating the pulp by adding the pulp to water, (a-2) mixing by adding a miscible additive, and (a-3) adding water to the stock A dilution step may be included to adjust the concentration.

In addition, after the step (a-1) and before the step (a-2), a beating step of beating the pulp may be further performed.

In an embodiment of the present invention, the miscible additive may be the same material as the film material or a material different from each other.

In addition, the miscible additive may be a material having a glass transition temperature lower than that of the film material, and the thermal compression bonding may be performed at a temperature equal to or higher than the glass transition temperature of the miscible additive.

In addition, the thermal compression bonding may be performed at a temperature below the glass transition temperature of the film material.

A paper product according to another aspect of the present invention is characterized in that it includes a paper product manufactured by any one of the above methods.

According to an embodiment of the present invention, there is an effect that can provide paper to which the film is attached without an adhesive by preparing paper by adding a miscible additive miscible with the film in the paper stock process and then thermally compressing the film.

In addition, according to an embodiment of the present invention, by using a miscible additive having a glass transition temperature lower than the glass transition temperature of the film material, even if the thermal compression bonding process is performed at a relatively low temperature to the extent that the film is not deformed or damaged, excellent There is an effect that can provide a film to which the film is attached by adhesive force.

However, the effects of the present invention are not limited to those mentioned above, and other effects not mentioned will be clearly understood by those skilled in the art from the description below.

1 is a flow chart of a method for manufacturing paper with a film attached thereto according to an embodiment of the present invention.
2 is an exemplary view of a film thermal compression bonding process according to an embodiment of the present invention.
3 is a diagram schematically illustrating the principle of attaching a film according to an embodiment of the present invention.

Hereinafter, preferred embodiments of the present invention will be described in detail, but the present invention is not limited or limited by the embodiments. In describing the present invention, if it is determined that a detailed description of related known technologies may unnecessarily obscure the subject matter of the present invention, the detailed description will be omitted. In addition, terms used in this specification should be interpreted as generally understood by those skilled in the art unless otherwise defined.

1 is a flow chart of a method for producing paper with a film attached thereto according to an embodiment of the present invention. Referring to Figure 1, the method for producing paper with a film attached according to an embodiment of the present invention, pulp dissociation step (S10), miscible additive mixing step (S20), dilution step (S30), papermaking step (S40) and drying It may include a step (S50) and a film thermal compression step (S60).

The pulp dissociation step (S10) is a step of dissociating the pulp by putting it into water to be 0.1 to 10 wt%, wherein the pulp may be cotton pulp or wood pulp.

After the pulp dissociation step, a step (S20) of adding and mixing miscible additives to the stock is performed. Here, the miscible additive means an additive that is miscible with the film material attached to the paper.

Miscible additives or film materials are resins with a melting point of 30 ~ 300 ℃, polyethylene (PE), polypropylene (PP), polystyrene (PS), polycarbonate (PC), polyethylene terephthalate ( Polyethylene Terephthalate (PET) may be selected as a material that is miscible with each other from materials including general-purpose polymers or biodegradable polymers such as PLA.

The miscible additive may be made of the same material as the film. For example, when the film adhered to paper is a PLA film, the miscible additive may include a PLA material.

Alternatively, the miscible additive and the film may be made of different materials. That is, even if it is a material different from the film, it can be used as a miscible additive in the case of a material that is miscible with the film material. Pairs of materials that are different from each other but are miscible include, for example, the following materials, but the present invention is not limited thereto.

- PC (Polycarbonate) and PET (Polyethylene terephthalate)

- PC (Polycarbonate) and PMMA (Polymethyl methacrylate)

- PC (Polycarbonate) and PU (Polyurethane)

- PC (Polycarbonate) and PVA (Polyvinyl acetate)

- PS (Polystyrene) and PMMA (Polymethyl methacrylate)

- PVC (Polyvinyl chloride) and PU (Polyurethane)

- PVC (Polyvinyl chloride) and PVA (Polyvinyl acetate)

Various methods of confirming miscibility between polymers have been proposed and studied, but it can be confirmed relatively simply by the following method. For example, when miscible materials are mixed, the glass transition temperature appears as one, A method of confirming that a single glass transition temperature is present through analysis may be used. In addition, when miscible materials are mixed, phase separation is not observed and a co-continuous structure is observed in morphological observation by a scanning electron microscope (SEM) or a transmission electron microscope (TEM).

Even materials that are incompatible with each other can become miscible with the addition of a compatibilizer. That is, in an embodiment of the present invention, the miscible additive may be a mixture of a material incompatible with the film material and a compatibilizer. Alternatively, the film material may be composed of a mixed material of a material miscible with a miscible additive and a compatibilizer.

Meanwhile, the miscible additive and the film may be made of materials having different glass transition temperatures. Even when the miscible additive and the film are made of the same material, there may be a difference in glass transition temperature depending on polymerization degree, molecular weight, purity, and the like. When the glass transition temperature of the miscible additive and the film are different, the higher glass transition temperature of the film is preferred. That is, the miscible additive may be selected from materials having a glass transition temperature lower than that of the film material while being miscible with the film material. By using a material with a glass transition temperature lower than that of the film material as the miscible additive, the film can be attached with strong adhesive force while minimizing deformation or damage of the film in the subsequent thermal compression process.

Miscible additives may be added in the form of polymer powder or fibers. When the miscible additive is added in the form of a polymer powder or fiber, the polymer powder or fiber may have a diameter of 1 to 1,000 μm and a length of 0.1 to 20 mm.

Miscibility additives may be added by 0.1 to 50 wt% based on the weight of the pulp.

After the mixing step (S20), a dilution step (S30) is performed in which water is added to adjust the stock concentration so that the papermaking step can be smoothly performed. Through the dilution step (S30), the pulp concentration in the stock may be adjusted to be in the range of 0.1 to 1 wt%.

Meanwhile, the dilution step (S30) may be performed before or simultaneously with the mixing step (S20). That is, after the dilution step (S30) is performed, the miscible additive may be added and mixed, or the miscible additive may be added and mixed while the dilution step (S30) is performed.

After the dilution step (S30), a papermaking step (S40) of preparing base paper using a paper machine such as a long net paper machine or a circle net paper machine from the diluted stock is performed, and a drying step (S50) is performed. The drying step (S50) may proceed for 2 to 500 seconds at a temperature of 75 to 350 °C.

Optionally, a surface treatment step of impregnating the paper into a surface treatment solution may be performed to further increase the strength of the dried paper. As the surface treatment solution for the first impregnation treatment, polyvinyl alcohol (PVA), which is a water-soluble polymer miscible with pulp, or a starch solution may be used. The concentration of the surface treatment liquid may be 0.1 to 6 wt%, and other additives may be further included in the surface treatment liquid.

The primary impregnated paper may be subjected to secondary impregnation in the curing liquid. Borax or boric acid may be used as a curing agent included in the curing liquid. The concentration of the curing liquid may be 0.1 to 5 wt%.

The step of first impregnating the surface treatment solution may be replaced with a step of surface treatment using a top-size method instead of an impregnation method. For example, while maintaining the surface treatment liquid at a temperature of 50 ~ 75 ° C, the previously manufactured paper undergoes a top size process using a rod or size press, and then passes through a compression press to remove excess surface treatment liquid. can At this time, a polyaminoamide epichlorohydrin (PAE)-based resin, urea, and a trihydric alcohol-based compound may be added to the surface treatment solution. By using a surface additive solution having such a composition, it is possible to improve properties such as high bending resistance of paper having appropriate flow properties and being suitable for the top-size method.

In addition, when the surface treatment step is performed, the drying step (S50) may proceed after the surface treatment step.

Optionally, a step of beating the pulp may be performed after the pulp dissociation step (S10). Beating can be carried out using a beating machine such as a Valley Beater, and the beating can also be carried out in the range of 45 to 60°SR. However, the beating step is preferably performed before mixing the miscible additives (S20). If the beating is performed after mixing the miscible additives, the fiber constituting the pulp and the miscible additive material have an even dispersibility due to the entanglement, whereas in the case of mixing the miscible additives after the beating, the papermaking step (S40) Since the miscible additives are mainly floating on the upper side of the stock, it is possible to obtain paper in which the miscible additives are located in a high concentration on the upper surface of the paper adhered to the film. Due to this, it is possible to further improve adhesion with the film in the subsequent film thermal compression step (S60).

Optionally, the paper manufacturing method according to an embodiment of the present invention may include adding other additives such as a sizing agent or a wet strength enhancer. Other additives may be added in at least one of the pulp dissociation step (S10), mixing step (S20), dilution step (30), papermaking step (S40), surface treatment step, or beating step, or added through a separate step. there is. By adding a sizing agent or a wet strength reinforcing agent, the strength of the paper molded product for use in a wet state can be further improved.

After the drying step (S50) is completed, a film thermal compression bonding step (S60) of thermally compressing the film to the dried paper is performed.

2 is an exemplary view of a film thermal compression bonding process according to an embodiment of the present invention. Referring to FIG. 2, the upper roller 21 and the lower roller 22 are moved while the dried paper P and the film F are moved between the rotating upper roller 21 and the lower roller 22, respectively. The paper 10 with the film attached thereto can be produced by pressing under conditions of a predetermined temperature and a predetermined pressure. The rotation speed of the upper roller 21 and the lower roller 22 and the moving speed of the dried paper P and film F can be synchronized with each other.

At this time, the temperature at which the thermal compression is performed may be set according to the glass transition temperature and/or melting point of the miscible additive added to the paper (P). For example, the predetermined temperature condition may be set in the range of 75°C to 350°C.

At this time, the thermal compression temperature may be set to a glass transition temperature or higher of the miscible additive. The miscible additive included in the paper (P) is easily deformed by thermal compression at a temperature equal to or higher than the glass transition temperature of the miscible additive, so that it can be easily adhered to the film (F).

In addition, the thermal bonding temperature may be set below the glass transition temperature of the material of the film (F). In the case of thermal compression at a temperature higher than the glass transition temperature of the material of the film (F), the film (F) may be deformed or damaged.

The temperature condition in which the thermal compression is performed can be realized by a method of heating the paper P and the film F by hot air or a lamp, or by heating the upper roller 21 and the lower roller 22 to raise the temperature. It may, but is not limited thereto.

The pressure at which thermal compression is performed (pressure for pressing the upper roller toward the lower roller) may be set according to the thickness of the paper P or the like. For example, the predetermined pressure condition may be set to 0 to 80 bar.

3 is a diagram schematically illustrating the principle of attaching a film according to an embodiment of the present invention. When the paper to which the miscible additive (A) is added is thermally compressed with the film, the miscible additive (A) included in the paper may function as an adhesive between the paper and the film. Since the miscible additive is a material that is miscible with the film material, it can be easily mixed with the film material during the thermal compression bonding process to obtain strong adhesive strength. In addition, since the miscible additive is not a material coated on the paper, but a material basically included in the paper, it can provide strong adhesion so that the film is not easily separated from the paper. However, FIG. 3 is a conceptual diagram to aid understanding of the invention, and the miscible additive is not limited to forming a separate layer between the paper and the film, as shown in FIG. 3 .

According to the above-described method for manufacturing paper with a film attached thereto according to an embodiment of the present invention, by adding a miscible additive to a stock from which pulp is dissociated, paper can be manufactured, thereby improving adhesion to the film without using an adhesive. . In addition, by using a miscible additive having a glass transition temperature lower than the glass transition temperature of the film material, it is possible to prevent the film from being deformed or damaged during the thermal compression bonding process.

Paper with a film manufactured according to an embodiment of the present invention has greatly improved oxygen barrier properties and moisture barrier properties compared to ordinary paper, so it is suitable for use as a material for disposable products instead of plastic.

Based on the following specific examples, the present invention will be described in more detail.

<Example>

The lintered cotton pulp was dissociated by adding it to water so that the stock concentration was 1 wt%. Then, it was beaten to 45 ° SR using a Valley Beater with a capacity of 23 L, and diluted by adding water so that the stock concentration was 0.3 wt%. Thereafter, PLA fibers (diameter: about 30 μm, length: 3 mm) were added in an amount of 5 wt% relative to the pulp weight, and then handsheets having a basis weight of 200 g / m ² were prepared using a circular handsheet machine through a mixing process. After drying at 105 ° C. for 4 minutes, it was left at 23 ° C. and 50% constant temperature and humidity conditions for more than 24 hours.

A PLA film having a thickness of 16 μm was thermally compressed on the dried paper using a thermal compression equipment. The thermocompression bonding process was carried out under conditions of 80°C and 20 bar.

After thermal compression, it was confirmed that the film and paper were strongly adhered. Attempts were made to separate the film from the paper, but it did not separate until the paper was torn. From this, it was confirmed that according to the embodiment of the present invention, the film can be strongly attached to the paper without an adhesive.

Although described above with reference to the limited embodiments and drawings, this is exemplary, and it will be apparent to those skilled in the art that various modifications and implementations are possible within the scope of the technical spirit of the present invention. In addition, the technical ideas described in each embodiment may be implemented independently or in combination with each other. Therefore, the protection scope of the present invention should be defined by the description of the claims and their equivalents.

10: paper with film attached
21: upper roller
22: lower roller
P: dried paper
F: film
A: miscible additives

Claims (9)

(a) forming a pulp furnish containing miscible additives;
(b) a papermaking step of producing paper from the stock containing the miscible additive using a papermaking machine;
(c) drying the paper; and
(d) thermally compressing a film on the dried paper;
including,
The miscible additive is a method for producing paper with a film, characterized in that made of a material miscible with the film material. According to claim 1,
In step (a),
(a-1) dissociating the pulp by introducing the pulp into water;
(a-2) adding and mixing a miscible additive;
(a-3) a dilution step of adjusting stock concentration by adding water;
Method for producing paper attached with a film, characterized in that it comprises a. According to claim 2,
A method for producing paper with a film, characterized in that a beating step of beating the pulp is further performed after step (a-1) and before step (a-2). According to claim 1,
The miscible additive is a method for producing paper with a film, characterized in that the same material as the film material. According to claim 1,
The miscible additive is a method for producing paper with a film, characterized in that the film material and a different material. According to claim 1,
The miscible additive is a method for producing paper with a film, characterized in that the glass transition temperature is lower than the film material. According to claim 1,
The thermal compression step is a paper manufacturing method with a film, characterized in that carried out at a temperature equal to or higher than the glass transition temperature of the miscible additive. According to claim 1,
The thermal compression step is a paper manufacturing method with a film, characterized in that carried out at a temperature below the glass transition temperature of the film material. A paper product comprising paper produced by the method according to any one of claims 1 to 8.

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