JP2021161583A - Hot press sheet, laminate, and manufacturing method thereof - Google Patents

Abstract

To provide a hot press sheet having good adhesion with a film on hot pressing and exhibiting watermark visibility after hot press bonding, suitable for design and counterfeit prevention technique, etc.SOLUTION: A hot press sheet includes a cellulosic fiber and a thermoplastic resin fiber and has a watermark having different light transmittance as compared to a peripheral part, wherein the thermoplastic resin fiber comprises at least two kinds including a first thermoplastic resin fiber and an unstretched second thermoplastic resin fiber. A laminate is formed by bonding the hot press sheet with a film.SELECTED DRAWING: None

Description

The present invention relates to a heat-pressurizing sheet and a laminate that can be suitably used for various functions and applications such as anti-counterfeiting and designability with a watermark pattern.

Conventionally, a watermark is known as a technique for preventing counterfeiting of printed matter such as gift certificates. The watermark is a pattern that appears when you look through the paper on which it is applied. The "white watermark" that allows the pattern to be seen through, and the "black watermark" that allows the pattern to appear darker than the peripheral area. Is known. These watermark patterns are usually formed by partially changing the basis weight of constituent fibers such as pulp fibers at the stage of forming wet paper (wire part) in wet papermaking. Further, as a kind of watermark pattern, a pseudo watermark (chemical watermark) or the like is known. The pseudo-watermark is formed by printing on a sheet using a substance that penetrates a sheet such as paper to increase the light transmittance, for example, an ink in which a transparent synthetic resin is dissolved in a solvent, and the ink is formed. The added printed portion becomes a watermark pattern and has the same visual effect as a white watermark.

Further, a film is often attached to the watermarked sheet for the purpose of further imparting functions such as water resistance, water permeability resistance, surface protection, anti-counterfeiting effect, designability, and strength. For example, Patent Document 1 describes an anti-counterfeit paper characterized by laminating a plastic film having excellent water permeability on both sides of a watermarked paper manufactured by an off-machine embossing method. The effect of not blurring the watermark when immersed in water has been disclosed.

Japanese Unexamined Patent Publication No. 2011-246832

However, when the anti-counterfeit paper described in Patent Document 1 is bonded to the film by a dry laminating method via an adhesive layer, the watermark formed by the difference in fiber density (so-called unevenness) is formed. The visibility of the watermark is reduced because the light transmittance of the watermark changes due to the addition of the adhesive in the subsequent process, or the light transmission is lost due to the air bubbles caused by the adhesive. Further, the dry laminating method requires an adhesive coating process and a drying process, and depending on the adhesive, aging may be required, resulting in poor production efficiency and uneconomical efficiency.

Further, when the watermarked paper and the film are bonded without providing the adhesive layer as described in Patent Document 1, there is a problem that the adhesion at the interface between the paper and the film is poor and the film cannot be laminated.

An object of the present invention is to provide a heat-pressurizing sheet that has good adhesion to a film during heating and pressurization, exhibits visibility of a watermark even after thermocompression bonding, and is suitable for designability, anti-counterfeiting technology, and the like. do.

As a result of diligent studies, the present inventors have made a sheet containing a cellulosic fiber and a specific thermoplastic resin fiber as a sheet having a watermark portion, and if this is bonded to a film by heating and pressurizing, the above object The present invention was completed by finding that is achievable.

That is, the present invention
A heating and pressurizing sheet that is bonded to the film by heating and pressurizing.
Contains cellulosic fibers and thermoplastic resin fibers
It has a watermark part with a different light transmittance than the peripheral part,
The thermoplastic resin fiber is characterized in that it is composed of at least two or more types of a first thermoplastic resin fiber and an undrawn second thermoplastic resin fiber.

The total weight of the first thermoplastic resin fiber and the second thermoplastic resin fiber is preferably 50% by mass to 90% by mass with respect to the total weight of the sheet.

The content of the first thermoplastic resin fiber is preferably 50% by mass to 95% by mass with respect to the total weight of the first thermoplastic resin fiber and the second thermoplastic resin fiber.

It is preferable that the melting temperature of the first thermoplastic resin is lower than the melting temperature of the second thermoplastic resin.

It is preferable that the temperature at the time of heating and pressurizing is between the melting temperature of the first thermoplastic resin and the melting temperature of the second thermoplastic resin.

It is preferable that the temperature at the time of heating and pressurizing is higher than the glass transition temperature (Tg) of the second thermoplastic resin.

It is preferable that the first thermoplastic resin is made of polycarbonate. Further, it is preferable that the second thermoplastic resin is made of polyethylene terephthalate.

It is preferable that the film is light transmissive.

The film is preferably made of a thermoplastic resin.

It is preferable that the thermoplastic resin is made of polycarbonate.

The present invention also relates to at least one film and a laminate comprising the heating and pressurizing sheet attached to the film.

It is preferable that at least a part of the interface between the film and the heating / pressurizing sheet is fused.

The laminate of the present invention is suitable for an anti-counterfeit sheet.

The present invention also relates to a method for producing a laminated body, which comprises laminating at least one film and the above-mentioned heating and pressurizing sheet and heating and pressurizing.

The heat-pressurized sheet of the present invention can be efficiently manufactured by fusing the first thermoplastic resin fiber with the resin constituting the film by heat-pressurization so that the sheet can be bonded without using an adhesive. Can be done.

The heating and pressurizing sheet of the present invention does not impair the visibility of the watermark because the second thermoplastic resin fiber becomes flexible during heating and pressurizing and exhibits a binder effect, but does not melt itself.

The heating and pressurizing sheet and laminate of the present invention can be used for various purposes, and can be suitably used for, for example, anti-counterfeiting or decorative applications.

[Sheet for heat processing]
The first aspect of the present invention is
A heating and pressurizing sheet that is bonded to the film by heating and pressurizing.
Contains cellulosic fibers and thermoplastic resin fibers
It has a watermark part with a different light transmittance than the peripheral part,
The thermoplastic resin fiber is a heating and pressurizing sheet, characterized in that it is composed of at least two or more types of a first thermoplastic resin fiber and an undrawn second thermoplastic resin fiber.

The heat processing sheet of the present invention contains cellulosic fibers. Known cellulose fibers can be used without particular limitation, but mainly wood bleaching chemical pulps such as coniferous bleached kraft pulp (NBKP), broadleaf bleached kraft pulp (LBKP), and coniferous bleached sulphite pulp (NBSP) are used. Used and, if necessary, mechanical pulp such as crushed wood pulp (GP), thermomechanical pulp (TMP), chemical thermomechanical pulp (BCTMP); non-wood pulp such as hemp, bamboo, straw, kenaf, sansho, 楮, cotton, etc. Use used paper pulp. One of these cellulosic fibers can be used alone or in combination of two or more.

The heat processing sheet of the present invention contains a thermoplastic resin fiber. The thermoplastic resin fiber is composed of at least two types of a first thermoplastic resin fiber and a second thermoplastic resin fiber.

The first thermoplastic resin fiber is made of a thermoplastic resin that is melted by heating and pressurizing at the time of bonding with the film and fused with the interface of the film. As long as it is such a thermoplastic resin, there is no particular limitation and known ones can be used. For example, polyolefin resins such as polyethylene and polypropylene; polyester resins such as polyethylene terephthalate, polybutylene terephthalate and polytrimethylene terephthalate; polyamide resins such as polyamide 6, polyamide 66 and polyamide 46; and polyacetal resins such as polyoxymethylene; Polycarbonate resin; polyether resin such as polyether ketone, polyether ether ketone, polyether glycol, polypropylene glycol, polytetramethylene ether glycol; polyether sulfone; polyphenylene sulfide; thermoplastic polyetherimide; tetrafluoroethylene-ethylene Thermoplastic fluororesins such as copolymers; acrylic resins and modified thermoplastic resins obtained by modifying them can be mentioned.

As the first thermoplastic resin fiber, polyethylene, polypropylene, polyethylene terephthalate, polybutylene terephthalate, polyamide, polycarbonate and acrylic resin are more preferable from the viewpoint of versatility, and polycarbonate has strength, heat resistance, moldability and light transmission. More preferable in terms of sex. The fiber diameter is preferably 0.1 dtex to 10 dtex, more preferably 1 dtex to 9 dtex, even more preferably 3 dtex to 8 dtex, and particularly preferably 6 dtex to 8 dtex. The fiber length is preferably 1 to 10 mm, more preferably 3 to 7 mm.

The second thermoplastic resin fiber is unstretched. The thermoplastic resin fiber is not particularly limited as long as it is unstretched, but one that crystallizes at the temperature of heating and pressurization is preferable. For example, known undrawn fibers such as polyester fibers such as unstretched polyethylene terephthalate and polyolefin fibers such as polyethylene and polypropylene can be mentioned. In particular, polyethylene terephthalate fiber is preferable because of its versatility and heat resistance. The fiber diameter is preferably 0.05 dtex to 10 dtex, more preferably 0.1 dtex to 8 dtex, even more preferably 0.1 dtex to 5 dtex, and preferably 0.1 dtex to 3 dtex. More preferred. The fiber length is preferably 2 to 10 mm, more preferably 2 to 6 mm.

The total weight of the first thermoplastic resin fiber and the second thermoplastic resin fiber is preferably 50% by mass to 90% by mass with respect to the total weight of the sheet.

The content of the first thermoplastic resin fiber is preferably 50% by mass to 95% by mass with respect to the total weight of the first thermoplastic resin fiber and the second thermoplastic resin fiber.

The heat processing sheet may contain fibers other than the cellulose fiber, the first thermoplastic resin fiber, and the second thermoplastic resin fiber. Hereinafter, although not particularly limited, carbon fiber, graphite fiber, aramid fiber, glass fiber, alumina fiber and the like may be added as the reinforcing fiber.

The melting temperature of the first thermoplastic resin is preferably lower than the melting temperature of the second thermoplastic resin, and the temperature at the time of heating and pressurizing is the melting temperature of the first thermoplastic resin and the melting of the second thermoplastic resin. It is even more preferably between the temperatures, and it is particularly preferable that the temperature during heating and pressurization is higher than the glass transition temperature (Tg) of the second thermoplastic resin. The effect of the present invention can be obtained because the first thermoplastic resin fiber melts at the temperature at the time of heating and pressurizing, and the second thermoplastic resin fiber does not melt at the same temperature. The melting temperature is the crystal melting temperature, the so-called melting point, for the crystalline thermoplastic resin, and the glass transition temperature (Tg) for the amorphous thermoplastic resin.

Therefore, the melting temperature of the first thermoplastic resin fiber is not particularly limited as long as it is lower than the temperature of heating and pressurizing, but is preferably 120 to 490 ° C, more preferably 140 to 240 ° C, for example. The melting point of the second thermoplastic resin fiber is not particularly limited as long as it is lower than the temperature of heating and pressurizing, but is preferably 150 to 530 ° C, more preferably 180 to 280 ° C, for example. .. Further, the glass transition temperature (Tg) of the second thermoplastic resin fiber is preferably 100 to 490 ° C, more preferably 120 to 240 ° C.

The method for producing the heat processing sheet using the cellulosic fiber, the first thermoplastic resin fiber and the second thermoplastic resin fiber is not particularly limited, and a known method is used. For example, a long net paper machine, a circle. A paper machine such as a net paper machine, an inclined short net paper machine, or a combination thereof can be used. Cellulose-based fibers may be beaten with a beater, refiner, or the like before papermaking, and the fiber slurry in which the fibers are mixed and dispersed in a dispersion medium such as water has a paper strength agent, a sizing agent, and a dispersant. , Various chemicals such as thickeners and antifoaming agents and auxiliaries may be added.

The heat processing sheet has a watermark portion having a different light transmission than the peripheral portion. The formation of the watermark portion is not particularly limited, and a known one is adopted. For example, in the wet paper forming stage (wire part) in wet papermaking, the basis weight of constituent fibers such as pulp fibers is partially changed. It is formed. Specifically, when a papermaking net in which the wire mesh is embedded in a pattern is used in the wire part, the portion corresponding to the pattern portion in which the wire mesh is embedded in the wet paper is charged as compared with the peripheral portion. A thin type is made without riding, and the typed part becomes a white watermark in the paper obtained by drying the wet paper, and when a papermaking net with a concave pattern is used, it is wet. The portion of the paper corresponding to the concave pattern portion is molded with a thickness thicker than that of the peripheral portion, and the typed portion becomes a black watermark in the paper obtained by drying the wet paper.

The pattern and shape of the watermark portion are not particularly limited, and may be formed continuously or discontinuously. Further, the heat processing sheet may be formed entirely or partially in a plan view.

Further, the formation of the watermark portion may be a pseudo watermark (chemical watermark). This is formed by printing on a sheet using a substance that permeates a sheet such as paper or non-woven fabric to increase the light transmittance, for example, an ink in which a transparent synthetic resin is dissolved in a solvent. The printed portion to which is added becomes a watermark pattern, and has the same visual effect as a white watermark. The method for producing the non-woven fabric is not particularly limited, and the non-woven fabric may be produced by a conventionally known method. Depending on the fiber used, any known technique such as chemical bond method, fiber lock method, air array method, stitch bond method, spun bond method, melt blow method, spun lace method, thermal bond method, needle punch method, wet method, etc. can be used. Can also be adopted.

The heat processing sheet may be a single layer or a plurality of layers. The thickness of the heat processing sheet is preferably 50 μm to 2000 μm, more preferably 100 μm to 1000 μm, even more preferably 200 to 800 μm, and particularly preferably 300 μm to 500 μm.

The film to be bonded to the heating and pressurizing sheet is not particularly limited, but is preferably made of a polymer resin composition, and the constituent material thereof may be the same as or different from that of the first thermoplastic resin fiber. Are preferably the same or have similar compositions. Therefore, it is preferable that it is made of a thermoplastic resin or that the thermoplastic resin is the main component. Further, the film is preferably light-transmitting in order to obtain the visibility of the watermark portion of the heating and pressurizing sheet. In the present invention, the "light transmissive" is a property of transmitting light, and means a state in which the watermark portion can be easily visually recognized when observing the laminated body. Therefore, "light transmission" does not necessarily have to be transparent, and may be translucent if the watermark portion is easily visible.

The thermoplastic resin is particularly preferably a synthetic resin, and the types thereof are polycarbonate, polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polyethylene, polypropylene, polyimide, polystyrene, polyacrylonitrile, and poly (meth) acrylate and polymonochlorotri. Examples thereof include combining at least one or more of celluloses such as fluoroethylene, polyvinyl chloride, polyvinylidene fluoride, tetrafluoroethylene, cellophane, cellulose triacetate, and diacetate. In particular, polycarbonate having excellent moldability, light transmission, heat resistance, and strength is more preferable. The content of the synthetic resin with respect to the total mass of the film can be, for example, 80% by mass or more and 100% by mass or less.

The film may be a single layer or a plurality of layers. The thickness of the film is preferably 10 μm to 3000 μm, more preferably 30 μm to 2000 μm, and even more preferably 50 μm to 1000 μm.

A second aspect of the present invention is
At least one film and
It is a laminate provided with a heating and pressurizing sheet attached to the film.

For the film and the heat / pressurizing sheet, the above description in the first aspect of the present invention also applies to the second aspect.

In the laminated body, at least one film and a heating / pressurizing sheet are laminated, and it is sufficient that the film is laminated on at least one side of the heating / pressurizing sheet, and even if the heating / pressurizing sheet has films on both sides. It may have an additional layer.

An adhesive, a layer containing an adhesive, or another layer may be interposed between the film and the heating / pressurizing sheet as long as the effect of the laminated body is not affected. It is preferable that no adhesive or other layer is interposed between them. That is, it is preferable that the film and the heating / pressurizing sheet come into direct contact with each other.

It is preferable that at least a part of the interface between the film and the heating / pressurizing sheet is fused. The term "fusion" as used herein means a state in which molecules are entangled with each other by melting by heating and pressurizing.

The thickness of the laminate is not particularly limited, but is preferably 50 μm to 5000 μm, more preferably 80 μm to 3000 μm, and even more preferably 100 μm to 2000 μm.

The laminated body of the present invention can exhibit the visual effect of the watermark portion, and can be suitably used for anti-counterfeiting.

[Manufacturing method of laminated body]
A third aspect of the present invention is
A method for producing a laminated body, which comprises laminating at least one film and the above-mentioned heating and pressurizing sheet and heating and pressurizing the film.

Regarding the film, the sheet for heating and pressurizing, and the laminate, the above description in the first aspect and the second aspect of the present invention also applies to the third aspect.

In the present invention, at least one film and a heating / pressurizing sheet are laminated to heat and pressurize.

The equipment for heating and pressurizing is not particularly limited, and known equipment is used. Examples thereof include a calendar device in which a metal roll and a metal roll are combined as pressurization, a calendar device in which a metal roll and a resin roll are combined, a calendar device in which a metal roll and a cotton roll are combined, and the like. The heating and pressurization is not limited to one time, and may be performed a plurality of times, and the apparatus and conditions may be different for each time.

The pressurization involves heating. The heating temperature is not particularly limited, and is usually preferably 130 ° C. or higher and 500 ° C. or lower, and more preferably 150 ° C. or higher and 250 ° C. or lower. By setting the heating temperature within the above range, the effect of the present invention tends to be exhibited. If the heating temperature exceeds the above upper limit, the second thermoplastic resin fiber may be melted and the visibility of the watermark may be impaired. If the heating temperature is less than the above lower limit, the bonding between the heating and pressurizing sheet and the film may be insufficient.

The pressure for heating and pressurizing is not particularly limited, and is usually 10 kgf / cm ² or more and 500 kgf / cm ² or less, preferably 20 kgf / cm ² or more and 100 kgf / cm ² or less.

According to the method for producing a laminate of the present invention, the adhesion between the film and the heating and pressurizing sheet is good, and good visibility of the watermark can be exhibited even after thermocompression bonding, and it has designability and anti-counterfeiting technology. It is possible to produce a laminate suitable for applications requiring a sheet.

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the scope of the present invention is not limited to the Examples.

[Example 1]
As a cellulosic fiber, a double disc refiner has a beating degree of 300 mLc. s. f. 20 parts by mass of NBKP beaten until
As the first thermoplastic resin fiber, 65 parts by mass of a polycarbonate fiber (manufactured by Daiwabo Polytec Co., Ltd., 6.8 dtex × 5 mm) having a melting point of 150 ° C. and
As the second thermoplastic resin fiber, 15 parts by mass of unstretched polyethylene terephthalate fiber (manufactured by Teijin Corporation, product name "TA07N", 1.2 dtex × 5 mm) having a melting point of 256 ° C. is prepared, mixed and dispersed in water. To prepare a fiber slurry. Next, as a two-tank circular net paper machine, we prepared a paper machine in which a paper machine with uneven parts corresponding to the low fiber deposition part (corresponding to the watermark part of the heating and pressurizing sheet) was installed in the cylinder in the first tank. By making paper using the fiber slurry, a heating and pressurizing sheet containing a watermark portion having ^{a basis weight of 90 g / m 2 was obtained.}

[Comparative Example 1]
A heating and pressurizing sheet was obtained in the same manner as in Example 1 except that unstretched polyethylene terephthalate fibers were not used.

[Example 2]
The heating and pressurizing sheet obtained in Example 1 was placed between two polycarbonate resin films (manufactured by Teijin Corporation, product name "Panlite Film D-100", thickness 100 μm), and placed at 180 ° C. and 30 kgf /. A laminate was obtained by heating and pressurizing for 2 minutes under the condition of ^{cm 2.}

[Comparative Example 2]
The heating and pressurizing sheet obtained in Comparative Example 1 was placed between two polycarbonate resin films and ^{heated and pressurized at 180 ° C. and 30 kgf / cm 2} for 2 minutes to obtain a laminate.

When the laminates obtained in Example 2 and Comparative Example 2 were compared and observed, the watermark portion of the laminate of Example 2 could be visually recognized without any problem, but the laminate of Comparative Example 2 was inferior in light transmission and the watermark portion. The visibility was poor.

[Comparative Example 3]
A sheet for heating and pressurizing was obtained in the same manner as in Example 1 except that the polycarbonate fiber was not used in Example 1, but this was laminated with the film even when heated and pressed in the same manner as in Example 2. The interface between the two was hardly fused and easily peeled off, and a laminate could not be formed.

The heating and pressurizing sheet of the present invention has a watermark portion and can be thermocompression-bonded to a film by heating and pressurizing to form a laminate.

The laminate of the present invention does not impair the visibility of the watermark even after heating and pressurizing. Then, the laminate of the present invention can be produced by a simple method.

Therefore, the present invention can exhibit good visibility of the watermark, and can be effectively used in applications and fields requiring a sheet having designability and anti-counterfeiting technology, and in particular, a decorative sheet and counterfeiting. Suitable as a preventive sheet.

Claims (15)

A heating and pressurizing sheet that is bonded to the film by heating and pressurizing.
Contains cellulosic fibers and thermoplastic resin fibers
It has a watermark part with a different light transmittance than the peripheral part,
The thermoplastic resin fiber is a sheet for heating and pressurizing, which comprises at least two kinds of a first thermoplastic resin fiber and an undrawn second thermoplastic resin fiber. The heating and pressurizing sheet according to claim 1, wherein the total weight of the first thermoplastic resin fiber and the second thermoplastic resin fiber is 50% by mass to 90% by mass with respect to the total weight of the sheet. .. The content of the first thermoplastic resin fiber is 50% by mass to 95% by mass with respect to the total weight of the first thermoplastic resin fiber and the second thermoplastic resin fiber, claim 1 or The heating and pressurizing sheet according to 2. The heating and pressurizing sheet according to any one of claims 1 to 3, wherein the melting temperature of the first thermoplastic resin is lower than the melting temperature of the second thermoplastic resin. The heating and pressurizing sheet according to claim 4, wherein the temperature at the time of heating and pressurizing is between the melting temperature of the first thermoplastic resin and the melting temperature of the second thermoplastic resin. The heating and pressurizing sheet according to claim 5, wherein the temperature during heating and pressurizing is higher than the glass transition temperature (Tg) of the second thermoplastic resin. The heating and pressurizing sheet according to any one of claims 1 to 6, wherein the first thermoplastic resin is made of polycarbonate. The heating and pressurizing sheet according to any one of claims 1 to 7, wherein the second thermoplastic resin is polyethylene terephthalate. The heating and pressurizing sheet according to any one of claims 1 to 8, wherein the film is light transmissive. The heating and pressurizing sheet according to any one of claims 1 to 9, wherein the film is made of a thermoplastic resin. The heating and pressurizing sheet according to claim 10, wherein the thermoplastic resin is made of polycarbonate. At least one film and
A laminate comprising the heating and pressurizing sheet according to any one of claims 1 to 11 attached to the film. The laminate according to claim 12, wherein at least a part of the interface between the film and the heating / pressing sheet is fused. The laminate according to claim 12 or 13, which is an anti-counterfeit sheet. At least one film and
A method for producing a laminated body, which comprises laminating the heating and pressurizing sheets according to any one of claims 1 to 11 and heating and pressurizing the sheets.