WO2020066886A1

WO2020066886A1 - Thread material, forgery prevention sheet, and production method therefor

Info

Publication number: WO2020066886A1
Application number: PCT/JP2019/036943
Authority: WO
Inventors: 謙一原井
Original assignee: 日本ゼオン株式会社
Priority date: 2018-09-28
Filing date: 2019-09-20
Publication date: 2020-04-02
Also published as: JPWO2020066886A1; JP7238899B2

Abstract

Provided is a thread material that is to be provided in forgery prevention sheets and comprises reflective polarizers and a first base film formed of a resin. The in-plane retardation of the first base film at a 590 nm measurement wavelength is not more than 10 nm, and the retardation in the thickness direction of the first base film at the 590 nm measurement wavelength is -10 nm to 10 nm.

Description

Thread material, forgery prevention paper, and method of manufacturing the same

The present invention relates to a thread material for anti-counterfeit paper, an anti-counterfeit paper, and a method of manufacturing the same.

Conventionally, various anti-counterfeit papers including a fibrous or strip-shaped thread material having an anti-counterfeit effect are known (see Patent Documents 1 and 2).

JP 2004-53870 A JP 2005-325482A

For example, anti-counterfeit paper containing an optical interference fiber which is a fibrous thread material excellent in pearl luster; anti-counterfeit paper including a thread material having a strip shape excellent in pearl luster; . These anti-counterfeit papers are not suitable for use in anti-counterfeit printing because the pearl luster of the thread material cannot be reproduced even when copied with a color copier or when data read by a scanner is printed with an inkjet printer. Available.

Further, for example, a thread material in the form of a round strip having a diameter of 1 mm to 2 mm, called planchettes, manufactured from a sheet-like material such as colored paper, fluorescent coloring paper that emits light by irradiation with ultraviolet light, and the like is also known. . The anti-counterfeit paper containing the thread material has been used in Canadian $ 50 bills.

Furthermore, for example, a special film called "multilayer light interference film" obtained by melting and extruding and stretching a plurality of polymer resins having different refractive indices into a strip shape called a glitter is obtained. Thread materials are also known. This thread material exhibits a forgery prevention function due to the interference color exhibited by the multilayer optical interference film.

では With the above-described technology, it is possible to easily recognize that the forgery prevention technology is used by the color change at the viewing angle that can be visually confirmed. However, recently, higher security is required. Therefore, attempts have been made to improve the security level using polarized light. Specifically, studies are being made on a thread material having a reflective polarizer.

Anti-counterfeit paper that includes a threaded material with a reflective polarizer can increase the security level because, in addition to the color change at the viewing angle, different images can be seen depending on the polarizer when observed using the polarizer. it can. For example, a threaded material provided with a reflective polarizer having a circularly polarized light separating function can be viewed using one of a right circularly polarizing plate and a left circularly polarizing plate, and can be observed using the other. If it does, the thread material cannot be seen. Therefore, the security level can be improved by utilizing the fact that different images are seen depending on the polarizing plate used in this way.

(4) Since the reflective polarizer is generally thin, it is easily broken or broken at the time of paper making. Then, in patent documents 1 and 2, in order to increase the rigidity of the thread material, it is proposed to provide a transparent resin base film in the thread material in combination with the reflective polarizer. As described above, the thread member including the base film has a self-supporting property and can suppress breakage and breakage during papermaking.

However, when the present inventor observed the anti-counterfeit paper obtained by making a stock including the thread material having the base film and the reflective polarizer as described above, different images depending on the polarizing plate were observed. It turned out that some thread materials could not be used. For example, when observing a thread material provided with a reflective polarizer having a circularly polarized light separating function, when using any of the right circularly polarizing plate and the left circularly polarizing plate, only the same image may be seen. .

The present invention has been made in view of the above problems, and is capable of suppressing deformation during papermaking, and suppressing the occurrence of a thread material in which a different image corresponding to a polarizing plate cannot be viewed. It is an object of the present invention to provide a thread material;

The present inventors have conducted intensive studies in order to solve the above-mentioned problems, and have obtained the following findings. When the stock containing the thread material is simply made, the thread material is arranged in a random direction on the obtained forgery prevention paper. Then, the thread material may be arranged with the base film on the outside and the reflective polarizer on the inside. The polarized light reflected by the reflective polarizer of the thread material thus arranged usually passes through the base film and enters the eyes of the observer. However, since a resin-made base film generally has a retardation, the polarization state of polarized light changes by transmitting through the base film. For example, even when the light reflected by the reflective polarizer includes only right-handed circularly polarized light, the reflected light transmits through the base film, and the polarization state of the reflected light includes both right-handed circularly polarized light and left-handed circularly polarized light. Changes. Therefore, at least a part of the reflected light can always pass through the polarizing plate used for observation, and as a result, different images depending on the polarizing plate cannot be seen in some cases.

Therefore, the present inventor further studied and found that a thread material using an optically isotropic base film having a small retardation did not depend on the orientation of the thread material while maintaining the shape of the forgery prevention paper. It has been found that different images can be seen depending on the polarizing plate. And, it has been found that when the thread material shows a different image corresponding to the polarizing plate regardless of the orientation of the thread material, it is possible to suppress the occurrence of a thread material in which a different image cannot be seen. Based on this finding, the present inventors have completed the present invention.
That is, the present invention includes the following.

[1] A thread material for providing forgery prevention paper,
The thread material, comprising a first base film formed of a resin, a reflective polarizer,
The in-plane retardation of the first base film at a measurement wavelength of 590 nm is 10 nm or less;
A thread material, wherein a retardation in a thickness direction of the first base film at a measurement wavelength of 590 nm is from -10 nm to 10 nm.
[2] The thread material according to [1], wherein the reflective polarizer is a circularly polarized light separating element.
[3] The thread material further includes a second base film,
The in-plane retardation of the second base film at a measurement wavelength of 590 nm is 10 nm or less,
The thread material according to [1] or [2], wherein a retardation in a thickness direction of the second base film at a measurement wavelength of 590 nm is from −10 nm to 10 nm.
[4] An anti-counterfeit paper containing the thread material according to any one of [1] to [3].
[5] A method for producing anti-counterfeit paper, which comprises making a paper stock containing the thread material according to any one of [1] to [3].

ADVANTAGE OF THE INVENTION According to this invention, the deformation | transformation at the time of papermaking can be suppressed, and the thread material for forgery prevention paper which can suppress generation | occurrence | production of the thread material which cannot see a different image according to a polarizing plate; And a method for producing the same.

FIG. 1 is a sectional view schematically showing a thread material according to one embodiment of the present invention. FIG. 2 is a cross-sectional view schematically illustrating an example of forgery prevention paper including a thread material. FIG. 3 is a cross-sectional view schematically showing a thread material according to another embodiment of the present invention.

Hereinafter, the present invention will be described in detail with reference to embodiments and examples. However, the present invention is not limited to the embodiments and examples described below, and can be arbitrarily modified and implemented without departing from the scope of the claims of the present invention and equivalents thereof.

において In the following description, the in-plane retardation Re of a film is a value represented by Re = (nx−ny) × d unless otherwise specified. The retardation Rth in the thickness direction of the film is a value represented by Rth = [{(nx + ny) / 2} −nz] × d unless otherwise specified. Here, nx represents a refractive index in a direction (in-plane direction) perpendicular to the thickness direction of the film and in a direction giving the maximum refractive index. ny represents a refractive index in the in-plane direction and a direction orthogonal to the direction of nx. nz represents the refractive index in the thickness direction. d represents the thickness of the film. The measurement wavelength is 590 nm unless otherwise specified.

[1. Embodiment of thread material]
FIG. 1 is a sectional view schematically showing a thread member 100 according to one embodiment of the present invention. As shown in FIG. 1, a thread material 100 according to one embodiment of the present invention includes a first base material film 110 and a reflective polarizer 120.

The first base film 110 is a resin film formed of a resin, and functions as a support film for supporting the reflective polarizer 120. Even if the rigidity of the reflective polarizer 120 is low, the thread material 100 has high mechanical strength as a whole, and thus can acquire self-supporting property, since the first base film 110 is unlikely to be broken or broken.

The first base film 110 is an optically isotropic resin film having a small in-plane retardation Re and a small thickness-direction retardation Rth. Therefore, the first base film 110 has a small ability to change the polarization state of light transmitted through the first base film 110. Therefore, the polarization state of the polarized light reflected by the reflective polarizer 120 has a small change due to transmission through the first base film 110.

The reflective polarizer 120 is a polarizer that can reflect only a part of the polarized light incident on the reflective polarizer 120. The reflective polarizer 120 may be, for example, a linearly polarized light separating element that reflects only linearly polarized light having a vibration direction in a certain direction. The vibration direction of the linearly polarized light indicates the vibration direction of the electric field of the linearly polarized light. Further, the reflective polarizer 120 may be, for example, a circularly polarized light separating element that reflects only one of the right circularly polarized light and the left circularly polarized light.

In the following description, a wavelength band in which the reflective polarizer 120 can exhibit a function of reflecting only a part of the polarized light incident on the reflective polarizer 120 may be referred to as a “reflection band”. The range and bandwidth of the reflection band of the reflective polarizer 120 are arbitrary. For example, the reflection band of the reflective polarizer 120 may include the entire visible region. The visible region usually refers to a wavelength region from 400 nm to 800 nm. Further, for example, the reflection band of the reflection polarizer 120 may be only a part of the visible region corresponding to a specific color.

The thread material 100 is a member provided on the forgery prevention paper. Specifically, the thread material 100 is used to make a stock containing the thread material 100 to produce forgery prevention paper. Therefore, the obtained forgery prevention paper contains the thread material 100. The security level of the anti-counterfeit paper is improved by utilizing the special appearance of the thread material 100 when viewed through the polarizing plate.

Hereinafter, a mechanism for preventing forgery using the thread material 100 will be described with reference to an example. FIG. 2 is a cross-sectional view schematically illustrating an example of the forgery prevention paper 200 including the

thread materials

100X and 100Y. FIG. 2 schematically shows a path of light reflected by the reflective polarizer 120 of the

thread members

100X and 100Y. In actual anti-counterfeit paper, various light absorptions and reflections may occur in addition to those described below, but in the following description, main light paths are schematically described for convenience of description of the operation. . In the example shown in FIG. 2, a part of the right circularly polarized light (specifically, light in the reflection band) is reflected in the visible region, and the remaining part of the right circularly polarized light and all of the left circularly polarized light are transmitted. The

thread members

100X and 100Y having the reflective polarizer 120 are employed.

Since the

thread materials

100X and 100Y have a self-supporting property by the first base film 110, when the stock containing the

thread materials

100X and 100Y is made, breakage and breakage of the

thread materials

100X and 100Y can be suppressed. Therefore, since the deformation of the

thread materials

100X and 100Y during papermaking can be suppressed, the

thread materials

100X and 100Y of the obtained forgery prevention paper 200 can maintain the shape before papermaking. However, in normal papermaking, it is difficult to adjust the front and back of the

thread members

100X and 100Y, so that the

thread members

100X and 100Y can be arranged in a random direction on the forgery prevention paper 200. Therefore, the forgery prevention paper 200 may include the thread material 100X arranged in one direction and the thread material 100Y arranged in another direction.

(4) When the light L including right circularly polarized light enters the anti-counterfeit paper 200, the light L passes through the gaps between the fibers of the anti-counterfeit paper 200 and enters the

thread members

100X and 100Y. Part of the right circularly polarized light of this light is reflected by the reflective polarizer 120 to become reflected light LR, and the rest becomes transmitted light LL. Here, the reflection can occur not only on the surface of the reflective polarizer 120 but also inside, but as a schematic expression, the reflection is illustrated as occurring on the surface of the reflective polarizer 120 in FIG.

(4) The reflected light LR of the one thread material 100X at the reflective polarizer 120 passes through the gap between the fibers of the forgery prevention paper 200 and proceeds to the outside of the forgery prevention paper 200. Since the reflected light LR is right circularly polarized light, it can pass through the right circularly polarizing plate 210 but cannot pass through the left circularly polarizing plate 220. Therefore, the observer who observes the thread material 100X can see different images between the observation using the right circularly polarizing plate 210 and the observation using the left circularly polarizing plate 220. Specifically, according to the observation through the right circularly polarized light 210, the observer can see the image by the reflected light LR, so that the observer can see the thread material 100X. However, according to the observation through the left circularly polarizing plate 220, the observer does not easily see the image by the reflected light LR, so the thread member 100X is difficult to see or cannot see.

Further, the reflected light LR of the other thread material 100Y on the reflective polarizer 120 passes through the first base film 110, and then passes through the gap between the fibers of the anti-counterfeit paper 200 to the outside of the anti-counterfeit paper 200. And proceed. Since the first base film 110 has optical isotropy, the change in the polarization state of the reflected light LR due to transmission through the first base film 110 is small. Therefore, the reflected light LR passes through the first base film 110 as right circularly polarized light, and thus can pass through the right circularly polarizing plate 210 but cannot pass through the left circularly polarizing plate 220. Therefore, the observer who observes the thread material 100Y sees different images between the observation using the right circular polarizer 210 and the observation using the left circular polarizer 220 as in the case of observing the thread material 100X. Can be.

Accordingly, the observer can see different images for all thread materials 100 </ b> X and 100 </ b> Y when viewed through the right circularly polarizing plate 210 and when viewed through the left circularly polarized light 220, regardless of the orientation of the front and back surfaces. Therefore, since different images can be seen for all the

thread materials

100X and 100Y, the occurrence of thread materials in which different images corresponding to the

polarizing plates

210 and 220 cannot be seen is suppressed.

場合 If different images can be seen depending on the

polarizing plates

210 and 220 as described above, the forgery prevention paper 200 can be determined to be genuine. If such different images corresponding to the

polarizing plates

210 and 220 cannot be seen, it can be determined that the forgery prevention paper is non-genuine. Then, by utilizing the fact that it is difficult to forge the forgery prevention paper 200 including the

thread members

100X and 100Y capable of identifying the authenticity, an improvement in security level can be achieved.

In the example shown above, the example in which the

thread materials

100X and 100Y are included inside the forgery prevention paper 200 is shown, but a part or the whole of the

thread materials

100X and 100Y is exposed on the surface of the forgery prevention paper 200. Is also good. Even when a part or the whole of the

thread members

100X and 100Y is exposed on the surface of the forgery prevention paper 200, the same advantages as in the above-described example can be obtained.

The thread material may further include an optional element in combination with the first base film and the reflective polarizer. For example, the thread material may include a second base film in combination with the first base film and the reflective polarizer. Hereinafter, the thread material including the second base film will be described.

FIG. 3 is a cross-sectional view schematically showing a thread material 300 according to another embodiment of the present invention. As shown in FIG. 3, the thread material 300 may further include a second base film 310 in combination with the first base film 110 and the reflective polarizer 120. As the second base film 310, a resin film formed of a resin is preferably used. By providing the second base film 310, both the first base film 110 and the second base film 310 can function as support films, so that the self-supporting property of the thread material 300 can be effectively improved. Thus, deformation of the thread material 300 during papermaking can be effectively suppressed. Further, the second base film 310 is preferably an optically isotropic resin film having a small in-plane retardation Re and a small thickness-direction retardation Rth. By employing the optically isotropic second base film 310, when the polarized light reflected by the reflective polarizer 120 passes through the second base film 310, the change in the polarization state of the polarized light can be reduced. Therefore, it is possible to obtain the thread material 310 that can see different images depending on the polarizing plate regardless of the front and back directions of the forgery prevention paper.

The position of the second base film 310 is arbitrary, but the thread material 300 preferably includes the first base film 110, the reflective polarizer 120, and the second base film 310 in this order in the thickness direction. The thread material 300 including the second base film 310 at such a position can protect both sides of the reflective polarizer 120 by the first base film 110 and the second base film 310, and thus can extend the life.

スレッド Moreover, the thread material may include an adhesive layer as an optional element. For example, the thread material may include an adhesive layer for bonding the first base film and the reflective polarizer, an adhesive layer for bonding the second base film and the reflective polarizer, and the like.

Furthermore, the thread material may have a hydrophilic layer. This hydrophilic layer is usually provided as the outermost surface layer of the thread material. When the first substrate film, the reflective polarizer, and the second substrate film have low hydrophilicity, the adhesive force between the fiber contained in the forgery prevention paper and the thread material may be low. On the other hand, if the hydrophilic layer is provided on the thread material, the adhesive force between the fiber and the thread material can be increased, so that the durability of the anti-counterfeit paper can be improved. Further, the hydrophilic layer preferably functions as an adhesive layer for adhering the thread material and the fibers of the anti-counterfeit paper.

任意 The optional layers such as the adhesive layer and the hydrophilic layer usually have the same optical isotropy as the first base film layer. Therefore, even if these optional layers are provided, it is possible to suppress the occurrence of a thread material in which a different image corresponding to the polarizing plate cannot be seen.

[2. First base film]
The in-plane retardation Re of the first base film is usually 10 nm or less, preferably 9 nm or less, more preferably 7 nm or less. With such a small in-plane retardation Re of the first base film, it is possible to suppress a change in the polarization state of light transmitted through the first base film in the thickness direction. Therefore, when observing the forgery prevention paper from the front direction, different images corresponding to the polarizing plates can be seen regardless of the front and back directions of the thread material on the forgery prevention paper. Therefore, it is possible to suppress the occurrence of a thread material in which a different image corresponding to the polarizing plate cannot be seen.

The retardation Rth in the thickness direction of the first base film is usually -10 nm or more, preferably -9 nm or more, more preferably -8 nm or more, and usually 10 nm or less, preferably 9 nm or less, more preferably 8 nm or less. . With such a small retardation Rth in the thickness direction of the first base film, it is possible to suppress a change in the polarization state of light transmitted through the first base film in an inclined direction that is neither parallel nor perpendicular to the thickness direction. Therefore, when observing the anti-counterfeit paper from the inclined direction, it is possible to see different images according to the polarizing plate regardless of the front and back directions of the thread material in the anti-counterfeit paper. Therefore, it is possible to suppress the occurrence of a thread material in which a different image corresponding to the polarizing plate cannot be seen.

任意 Any resin can be used as the resin forming the first base film. Among them, a thermoplastic resin is preferable as the resin from the viewpoint of facilitating the production of the first base film. The thermoplastic resin may include a polymer and, if necessary, any components.

As the polymer, for example, polycarbonate, polyether sulfone, polyethylene terephthalate, polyimide, polymethyl methacrylate, polysulfone, polyarylate, polyethylene, polyphenylene ether, polystyrene, polyvinyl chloride, cellulose diacetate, cellulose triacetate, and alicyclic And a structure-containing polymer. In addition, one kind of the polymer may be used alone, or two or more kinds may be used in combination at an arbitrary ratio. Above all, alicyclic structure-containing polymers are preferred from the viewpoints of transparency, low hygroscopicity, dimensional stability and processability. The alicyclic structure-containing polymer is a polymer having an alicyclic structure in a main chain and / or a side chain, and for example, those described in JP-A-2007-057971 can be used. The proportion of the polymer in the thermoplastic resin is preferably from 80% by weight to 100% by weight, more preferably from 90% by weight to 100% by weight, particularly preferably from 95% by weight to 100% by weight.

The optional components include, for example, antioxidants, ultraviolet absorbers, light stabilizers, bluing agents and the like. One of these may be used alone, or two or more thereof may be used in combination at an arbitrary ratio.

製造 As a method for producing the first base film, for example, a cast molding method, an inflation molding method, an extrusion molding method and the like can be mentioned, among which the extrusion molding method is preferable.

厚み The thickness of the first base material film is arbitrary as long as a thread material having a desired thickness can be obtained. From the viewpoint of increasing the self-supporting property of the thread material, the thickness of the first base film is preferably 5 μm or more, more preferably 7.5 μm or more, and particularly preferably 10 μm or more. From the viewpoint of reducing the thickness of the thread material, the thickness of the first base film is preferably 30 μm or less, more preferably 25 μm or less, and particularly preferably 20 μm or less.

[3. Reflective polarizer]
The reflective polarizer can exhibit a function of reflecting only a part of polarized light incident on the reflective polarizer in one or more reflection bands. The reflection band of the reflection polarizer preferably includes the visible region. The expression that the reflection band includes the visible region means that the reflection band includes at least a part of the visible region. As described above, the reflection polarizer having the reflection band in the visible region allows the reflected light of the reflection polarizer to be visually recognized by the naked eye. Therefore, the thread material provided with such a reflective polarizer can be applied to a wide range of applications.

When the reflective polarizer has a reflection band in the visible region, the number of reflection bands in the visible region may be one or two or more. For example, a reflection polarizer having only one reflection band with a narrow bandwidth in the visible region can obtain reflected light of a single color (for example, red, green, blue, or the like) corresponding to the reflection band. In addition, for example, a reflective polarizer having only one reflection band in the visible region that has a wider bandwidth so as to cover the entire visible region can obtain mixed-color (normally, silver) reflected light corresponding to the reflection band. . Further, for example, a reflective polarizer having two or more reflection bands in the visible region can obtain reflected light of mixed colors of colors corresponding to the respective reflection bands.

帯域 The bandwidth per reflection band is preferably 100 nm or more, preferably 200 nm or more, particularly preferably 400 nm or more. In particular, it is more preferable that the reflective polarizer has a reflection band having the above-mentioned bandwidth in the visible region. As a result, the amount of reflected light per thread material can be increased, and a thread material with more excellent design and visibility can be obtained.

直線 As the reflective polarizer, a linearly polarized light separating element or a circularly polarized light separating element may be used. As the linearly polarized light separating element, for example, a linearly polarized light separating element utilizing birefringence as described in Japanese Patent No. 3448626 can be used. However, it is preferable to use a circularly polarized light separating element as the reflective polarizer from the viewpoint of increasing the difficulty of forgery and facilitating the operation of determining the authenticity.

It is preferable to use a cholesteric resin layer as the circularly polarized light separating element. Cholesteric resin refers to a resin having cholesteric regularity. Cholesteric regularity means that the molecular axes are aligned in a certain direction on one plane, but the direction of the molecular axis is shifted at a slight angle in the next plane that overlaps it, and further deviated in the next plane As described above, the structure has a structure in which the angles of the molecular axes in the planes are shifted (twisted) as the light sequentially passes through the planes arranged in an overlapping manner. That is, when the molecules inside a certain layer have cholesteric regularity, the molecules are arranged such that the molecular axis is in a fixed direction on a certain first plane inside the layer. At the next second plane inside the layer, which overlaps the first plane, the direction of the molecular axis is slightly offset from the direction of the molecular axis in the first plane. In the next third plane that further overlaps the second plane, the direction of the molecular axis is further deviated from the direction of the molecular axis in the second plane. In this way, the angles of the molecular axes in the planes that overlap each other are sequentially shifted (twisted). Such a structure in which the direction of the molecular axis is twisted is usually a helical structure and an optically chiral structure.

Usually, the cholesteric resin layer can exhibit a circularly polarized light separating function of transmitting one of right circularly polarized light and left circularly polarized light and reflecting a part or all of the other circularly polarized light. The reflection in the cholesteric resin layer reflects circularly polarized light while maintaining its chirality. At this time, the reflection color of the cholesteric resin layer can be adjusted by adjusting the reflection band as a wavelength range that exhibits the circularly polarized light separating function.

The specific wavelength at which the cholesteric resin layer exerts the function of separating circularly polarized light generally depends on the pitch of the helical structure in the cholesteric resin layer. The pitch of the helical structure is the distance in the normal direction of the plane until the direction of the molecular axis in the helical structure gradually deviates as the plane progresses and returns to the original molecular axis direction again. By changing the pitch of the helical structure, it is possible to change the wavelength at which the circularly polarized light separating function is exhibited.

For example, in a cholesteric resin layer formed using a liquid crystal compound, a helical structure in which a helical axis representing a rotation axis when a molecular axis is twisted in a helical structure is parallel to a normal line of the cholesteric resin layer. The pitch p and the wavelength λ of the reflected circularly polarized light generally have the relationship of Expression (X) and Expression (Y).

Formula (X): λ _c = n × p × cos θ
Formula _{(Y): n o × p} × cosθ ≦ λ ≦ n e × p × cosθ

In formula (X) and formula (Y), lambda _c is the center wavelength of the reflection band (hereinafter sometimes referred to as "reflection center wavelength".) Represent, n _o denotes the refractive index along the short axis of the liquid crystal compound , n _e represents the refractive index of the long axis direction of the liquid crystal compounds, n represents an _{(n e + n o) /} 2, p represents the pitch of the helical structure, theta is a normal angle of incidence (the plane of the light And the angle between them.

Therefore, the reflection center wavelength λ _c depends on the pitch p of the helical structure of the polymer in the cholesteric resin layer. By changing the pitch p of the spiral structure, the reflection band can be changed. Therefore, it is preferable that the pitch p of the spiral structure is set according to the wavelength of circularly polarized light to be reflected on the cholesteric resin layer. As a method for adjusting the pitch p, for example, a method described in JP-A-2009-300662 can be used. As a specific example, in the cholesteric liquid crystal composition, a method of adjusting the kind of the chiral agent or adjusting the amount of the chiral agent is exemplified.

As the cholesteric resin layer, for example, (i) a cholesteric resin layer in which the pitch of the helical structure is changed stepwise, and (ii) a size of the helical structure in which the pitch is changed continuously. And a cholesteric resin layer.

(I) The cholesteric resin layer in which the spiral structure pitch is changed stepwise can be obtained, for example, by laminating a plurality of cholesteric resin layers having different spiral structure pitches. Lamination can be performed by preparing a plurality of cholesteric resin layers having different spiral structure pitches in advance, and then fixing each layer via an adhesive or an adhesive. Alternatively, the lamination can be performed by forming a certain cholesteric resin layer and then sequentially forming another cholesteric resin layer.

(Ii) The layer of the cholesteric resin in which the pitch of the helical structure is continuously changed includes, for example, one or more irradiation treatments with active energy rays and / or heating treatments on the liquid crystal composition layer. After performing the band broadening process, the liquid crystal composition layer can be obtained by curing. According to the above-described broadband processing, the pitch of the helical structure can be continuously changed in the thickness direction, so that the reflection band of the cholesteric resin layer can be expanded, and is therefore called broadband processing.

(4) The cholesteric resin layer may be a single-layer structure composed of only one layer or a multi-layer structure including two or more layers. The number of layers contained in the cholesteric resin layer is preferably from 1 to 100, more preferably from 1 to 20, from the viewpoint of ease of production.

製造 The method of manufacturing the reflective polarizer is optional. For example, as a method for producing a circularly polarized light separating film including a cholesteric resin layer as a circularly polarized light separating element, a layer of a cholesteric liquid crystal composition is provided on a suitable support, and the layer is cured to form a layer of a cholesteric resin. There is a method of obtaining. A material referred to as a “liquid crystal composition” for convenience includes not only a mixture of two or more substances but also a material composed of a single substance. In addition, a cholesteric liquid crystal composition refers to a composition in which, when a liquid crystal compound included in the liquid crystal composition is oriented, the liquid crystal compound can exhibit a liquid crystal phase having cholesteric regularity (cholesteric liquid crystal phase). .

(4) As the cholesteric liquid crystal composition, a liquid crystal composition containing a liquid crystal compound and, if necessary, further containing arbitrary components can be used. As the liquid crystal compound, a liquid crystal compound which is a polymer compound and a polymerizable liquid crystal compound can be used. In order to obtain high thermal stability, it is preferable to use a polymerizable liquid crystal compound. By polymerizing the polymerizable liquid crystal compound in a state of exhibiting cholesteric regularity, the layer of the cholesteric liquid crystal composition is cured, and a layer of a non-liquid crystalline cholesteric resin which is cured while exhibiting cholesteric regularity can be obtained. it can. As the cholesteric liquid crystal composition, for example, those described in WO 2016/002765 can be used.

As the support, any member having a flat support surface that can support the layer of the cholesteric liquid crystal composition can be used. Usually, a resin film is used as such a support. The support surface of the support may be subjected to a treatment for imparting an alignment regulating force in order to promote the alignment of the liquid crystal compound in the layer of the cholesteric liquid crystal composition. Here, the alignment regulating force of a certain surface refers to the property of the surface that can align the liquid crystal compound in the cholesteric liquid crystal composition. Examples of the treatment for imparting the alignment regulating force to the support surface include a rubbing treatment, an orientation film forming treatment, a stretching treatment, and an ion beam orientation treatment.

(4) Usually, a layer of the cholesteric liquid crystal composition is provided by coating the cholesteric liquid crystal composition on the support surface of the support. Examples of coating methods include curtain coating, extrusion coating, roll coating, spin coating, dip coating, bar coating, spray coating, slide coating, print coating, gravure coating, and die coating. Method, gap coating method, and dipping method.

(4) After the cholesteric liquid crystal composition layer is provided, the cholesteric liquid crystal composition layer may be subjected to an alignment treatment, if necessary. The alignment treatment is usually performed by heating a layer of the cholesteric liquid crystal composition to a predetermined alignment temperature. By performing such an alignment treatment, the liquid crystal compound contained in the cholesteric liquid crystal composition is aligned, and becomes a state exhibiting cholesteric regularity. The specific alignment temperature is adjusted according to the composition of the cholesteric liquid crystal composition, and may be, for example, in the range of 50 ° C. to 150 ° C. The processing time of the light distribution processing may be, for example, 0.5 minute to 10 minutes.

However, the orientation of the liquid crystal compound contained in the cholesteric liquid crystal composition may be immediately achieved by coating the cholesteric liquid crystal composition. Therefore, the alignment treatment does not necessarily have to be performed on the layer of the cholesteric liquid crystal composition.

After aligning the liquid crystal compound, the layer of the cholesteric liquid crystal composition is cured to obtain a layer of the cholesteric resin. In this step, usually, a polymer component such as a polymerizable liquid crystal compound contained in the cholesteric liquid crystal composition is polymerized to cure the layer of the cholesteric liquid crystal composition. As the polymerization method, a method suitable for the properties of the components contained in the cholesteric liquid crystal composition can be selected. Examples of the polymerization method include a method of irradiating active energy rays and a thermal polymerization method. Among them, a method of irradiating active energy rays is preferable because the polymerization reaction can proceed at room temperature. Here, the irradiated active energy rays may include light such as visible light, ultraviolet light, and infrared light, and arbitrary energy rays such as an electron beam. Further, when curing the layer of cholesteric liquid crystal composition by irradiation of an active energy ray, intensity of the active energy ray to be irradiated may be, for ^example, 50mJ / cm 2 ~ 10,000mJ / cm 2.

In addition, after the liquid crystal compound is aligned and before the cholesteric liquid crystal composition layer is cured, the layer of the cholesteric liquid crystal composition may be subjected to a band broadening treatment. Such a broadening process can be performed, for example, by a combination of one or more irradiation processes of active energy rays and a heating process. The irradiation process in the broadband process can be performed, for example, by irradiating light having a wavelength of 200 nm to 500 nm for 0.01 seconds to 3 minutes. At this time, the energy of the irradiated light may be, for example, 0.01 mJ / cm ² to 50 mJ / cm ² . The heat treatment can be performed, for example, by heating to a temperature of preferably 40 ° C. or higher, more preferably 50 ° C. or higher, preferably 200 ° C. or lower, and more preferably 140 ° C. or lower. The heating time at this time is preferably 1 second or more, more preferably 5 seconds or more, and usually 3 minutes or less, preferably 120 seconds or less. By performing such a broadening process, a large reflection band can be obtained by continuously and largely changing the magnitude of the pitch of the spiral structure.

The irradiation with the active energy ray may be performed in air, or a part or all of the process may be performed in an atmosphere in which the oxygen concentration is controlled (for example, in a nitrogen atmosphere).

工程 The steps of applying and curing the cholesteric liquid crystal composition are not limited to one time, and the application and curing may be repeated plural times. Thereby, a thick cholesteric resin layer including two or more layers is obtained.

In the above-described production method, the twist direction in the cholesteric regularity can be appropriately selected depending on the structure of the chiral agent used. For example, when the twist is to the right, a cholesteric liquid crystal composition containing a chiral agent imparting dextrorotation is used, and when the twisting direction is leftward, a cholesteric liquid containing a chiral agent imparting levorotation is used. A liquid crystal composition is used.

厚み The thickness of the reflective polarizer is not particularly limited and can be arbitrarily set according to the use and design of the forgery prevention paper. The specific thickness of the reflective polarizer is preferably 0.5 μm or more, more preferably 0.75 μm or more, and particularly preferably 1 μm or more, from the viewpoint of enhancing the visual visibility of polarized light reflected by the reflective polarizer. It is. The specific thickness of the reflective polarizer is preferably 10 μm or less, more preferably 7 μm or less, from the viewpoint of increasing the transparency of the thread material when observed through a polarizing plate capable of blocking the polarized light reflected by the reflective polarizer. 0.5 μm or less, particularly preferably 5 μm or less.

[4. Second base film]
The in-plane retardation Re of the second base film is usually in the same range as the in-plane retardation Re of the first base film. Thereby, the same advantages as described in the first base film can be obtained. The in-plane retardation Re of the first base film and the in-plane retardation Re of the second base film may be the same or different.

レター The retardation Rth in the thickness direction of the second base film is usually in the same range as the retardation Rth in the thickness direction of the first base film. Thereby, the same advantages as described in the first base film can be obtained. The retardation Rth in the thickness direction of the first base film and the retardation Rth in the thickness direction of the second base film may be the same or different.

樹脂 As the resin forming the second base film, the same resin as the resin in the range described as the resin forming the first base film can be used. The resin contained in the first base film and the resin contained in the second base film may be the same or different.

The second base film can be manufactured, for example, by the same method as the first base film.

厚み The thickness of the second base film is usually in the same range as the thickness of the first base film. Thereby, the same advantages as described in the first base film can be obtained. The thickness of the first base film and the thickness of the second base film may be different, but are preferably the same from the viewpoint of suppressing warpage of the thread material.

[5. Shape, size and manufacturing method of thread material]
The shape of the thread material is arbitrary, and may be, for example, a string shape, a column shape, a sheet shape, or the like. Among them, from the viewpoint of obtaining anti-counterfeit paper excellent in design, the thread material is preferably a sheet-like member. The planar shape of the sheet-like thread material viewed from the thickness direction is arbitrary, and may be, for example, a figure such as a circle, an ellipse, or a polygon, or a symbol such as a letter or a number. .

The size of the thread material in the surface direction is arbitrary. The size in the surface direction of the thread material indicates a size in a direction perpendicular to the thickness direction of the thread material. In order to enhance the visual visibility, the size of the thread material in the surface direction is preferably 1 mm to 10 mm, and is often about 5 mm.

The thickness of the thread material is preferably at least 10 µm, more preferably at least 15 µm, particularly preferably at least 20 µm, preferably at most 40 µm, more preferably at most 35 µm, particularly preferably at most 30 µm. When the thickness of the thread material is equal to or more than the lower limit of the above range, the self-supporting property of the thread material can be increased. When the thickness of the thread material is equal to or less than the upper limit of the above range, the thread material can be made thinner than general paper. Therefore, it is possible to suppress the thread material from protruding largely without being covered with the paper fibers, and to prevent the thread material from falling off from the forgery prevention paper.

The method for manufacturing the thread material is not particularly limited. For example, the thread material can be manufactured by a method including a step of preparing a first base film and a reflective polarizer, and a method of bonding the prepared first base film and the reflective polarizer. For bonding the first base film and the reflective polarizer, an adhesive may be used as necessary.

では In the above-described production method, by bonding the first base film and the reflective polarizer, an original sheet containing the first base film and the reflective polarizer is usually obtained. In order to increase industrial productivity, the raw sheet is often manufactured as a large-sized sheet. Therefore, the above manufacturing method may include a step of processing the raw sheet into a desired size and shape. For example, a desired thread material may be obtained by processing the raw sheet by a method such as a punching method or a cutting method.

The above-mentioned manufacturing method may further include an optional step. Examples of the optional step include a step of providing optional elements such as a second base film, an adhesive layer and a hydrophilic layer on the thread material; and a step of performing a surface treatment on the thread material.

[6. Anti-counterfeit paper]
The forgery prevention paper includes the thread material described above. Usually, the forgery prevention paper includes a base paper formed of paper fibers and a thread material provided on the base paper. The thread material is usually fixed to the base paper by including at least a part of the thread material in the base paper. Thus, the entire thread material may be in the base paper, or a part of the thread material may be in the base paper and the rest may be outside the base paper.

(4) Such anti-counterfeit paper can be manufactured by a manufacturing method including making a stock containing thread material. This production method may include, for example, a step of preparing a stock as a composition containing fibers such as pulp, a solvent such as water, and a thread material, and a step of paper-making the stock. The step of making the stock is, for example, forming a stock while dewatering as necessary to obtain a web containing the solid content of the stock, drying the web, stacking a plurality of webs, Forming unevenness, and the like.

用途 Use of forgery prevention paper includes any paper for which forgery avoidance is desired. Specific examples of the use of the forgery prevention paper include banknotes, securities, certificate stamps, passports, cash vouchers, wrapping paper, open seals, and the like.

Hereinafter, the present invention will be specifically described with reference to examples. However, the present invention is not limited to the embodiments described below, and can be arbitrarily modified and implemented without departing from the scope of the claims of the present invention and equivalents thereof.

In the following description, "CSF" indicates a Canadian standard freeness.
In the following description, “%” and “parts” representing amounts are based on weight unless otherwise specified. Further, the operations described below were performed in a normal temperature and normal pressure atmosphere unless otherwise specified.

[Method of measuring film retardation]
The in-plane retardation Re and the retardation Rth in the thickness direction of the base film were measured at a measurement wavelength of 590 nm using a birefringence meter ("Axoscan" manufactured by Axometrics).

[Evaluation method of anti-counterfeit paper in front direction]
The forgery prevention paper was observed through the right circularly polarizing plate. Further, the forgery prevention paper was observed through the left circularly polarizing plate. These observations were made in the front direction perpendicular to the paper surface of the anti-counterfeit paper. The observation results were evaluated according to the following criteria.

"A": The image seen through the right circularly polarizing plate and the image seen through the left circularly polarizing plate were clearly different in all thread materials.
"B": The image seen through the right circularly polarizing plate and the image seen through the left circularly polarizing plate were different for all thread materials.
“C”: The image viewed through the right circularly polarizing plate and the image viewed through the left circularly polarizing plate were different in some threads, but the same in the remaining thread materials.
"D": The image seen through the right circularly polarizing plate and the image seen through the left circularly polarizing plate were the same for all thread materials.

[Evaluation method of anti-counterfeit paper in inclined direction]
The forgery prevention paper was observed through the right circularly polarizing plate. Further, the forgery prevention paper was observed through the left circularly polarizing plate. These observations were made in a direction of inclination of a polar angle of 60 ° on the paper surface of the anti-counterfeit paper. The observation results were evaluated according to the following criteria.

[Comprehensive evaluation method]
From (i) the observation result in the front direction perpendicular to the paper surface of the anti-counterfeit paper and (ii) the observation result in the inclination direction at a polar angle of 60 ° with respect to the paper surface of the anti-counterfeit paper, , Comprehensive evaluation.
"A": The image viewed through the right circular polarizer and the image viewed through the left circular polarizer were clearly different in all thread materials in both the front direction and the tilt direction.
"B": The image seen through the right circularly polarizing plate and the image seen through the left circularly polarizing plate were different in all thread materials in both the front direction and the inclined direction.
“C”: The image viewed through the right circular polarizer and the image viewed through the left circular polarizer in one of the front direction and the tilt direction were different in some threads, but the same in the other thread materials. Was.
"D": The image viewed through the right circularly polarizing plate and the image viewed through the left circularly polarizing plate were different in at least some thread materials in both the front direction and the inclined direction.

[Production Example 1. Production of Cholesteric Liquid Crystal Composition]
25.5 parts of a compound represented by the following formula (X1), 11 parts of a polymerizable liquid crystal compound represented by the following formula (X2), 2.3 parts of a chiral agent (“LC756” manufactured by BASF), and polymerization initiation Cholesteric liquid crystal obtained by mixing 1.2 parts of an agent (“Irgacure OXE02” manufactured by Ciba Specialty Chemicals), 0.04 part of a surfactant (“Fergent 209F” manufactured by Neos), and 60 parts of cyclopentanone as a solvent. The composition was prepared.

化合物 As the compound represented by the formula (X1), a compound produced based on the method described in Japanese Patent No. 5365519 was used. As the compound represented by the formula (X2), a compound produced according to the method described in Japanese Patent No. 4054392 was used.

[Production Example 2: Production of circularly polarized light separating film a]
As a support, a polyester film ("Cosmoshine A4100" manufactured by Toyobo, having a film thickness of 100 µm and having an easily adhesive-treated surface on one side) was prepared. Rubbing treatment was performed on the surface of the support opposite to the surface on which easy adhesion treatment was performed. The cholesteric liquid crystal composition was applied to the rubbed surface of the support using a # 12 wire bar to form a layer of the liquid crystal composition. The liquid crystal composition layer was subjected to an alignment treatment of heating at 130 ° C. for 5 minutes. Thereafter, the liquid crystal composition layer is subjected to a process of irradiating a weak ultraviolet ray of 0.1 mJ / cm ² to 45 mJ / cm ² and a subsequent heating process at 100 ° C. for 1 minute. After performing the broadband treatment performed twice, it is cured by irradiating with ultraviolet rays of 200 mJ / cm ² under a nitrogen atmosphere to obtain a 5.2 μm-thick circularly polarized light separating film a as a cholesteric resin layer on the support. Was. The obtained circularly polarized light separating film a had a reflectance of about 50% in a wavelength range of about 380 nm to 780 nm. The film provided with the support and the circularly polarized light separating film a thus obtained may be referred to as “polarized light separating film a”.

[Production Example 3: Production of circularly polarized light separating film b]
As a support, a polyester film ("Cosmoshine A4100" manufactured by Toyobo, having a film thickness of 100 µm and having an easily adhesive-treated surface on one side) was prepared. Rubbing treatment was performed on the surface of the support opposite to the surface on which easy adhesion treatment was performed. The cholesteric liquid crystal composition was applied to the rubbed surface of the support using a # 10 wire bar to form a layer of the liquid crystal composition. The liquid crystal composition layer was subjected to an alignment treatment of heating at 130 ° C. for 5 minutes. Thereafter, the liquid crystal composition layer is cured by irradiating the layer with the liquid crystal composition with ultraviolet rays of 200 mJ / cm ² under a nitrogen atmosphere, and a circularly polarized light separating film b as a cholesteric resin layer having a thickness of 3.1 μm is formed on the support. Obtained. The obtained circularly polarized light separating film b had a reflectance of about 50% in a wavelength range of about 500 nm to 600 nm. The film provided with the support and the circularly polarized light separating film b thus obtained is sometimes referred to as “polarized light separating film b”.

[Production Example 4: Production of base film A]
Pellets of thermoplastic norbornene resin (“ZEONOR1420R” manufactured by Zeon Corporation, glass transition temperature: 137 ° C.) were dried at 90 ° C. for 5 hours. The dried pellets were supplied to an extruder and melted in the extruder. Thereafter, the molten resin is extruded through a polymer pipe and a polymer filter into a film shape from a T-die onto a casting drum, cooled, and cooled to a thickness of 25 μm, an in-plane retardation Re1.5 nm, and a thickness direction retardation Rth3.5 nm. A material film A was obtained.

[Production Example 5: Production of base film B]
A base film B having a thickness of 13 μm, an in-plane retardation Re of 0.8 nm, and a thickness direction retardation Rth of 1.8 nm was produced in the same manner as in Production Example 4, except that the film forming conditions were changed.

[Production Example 6: Production of base film C]
A base film C having a thickness of 35 μm, an in-plane retardation Re of 10 nm, and a thickness direction retardation Rth of 10 nm was obtained in the same manner as in Production Example 4, except that the film forming conditions were changed.

[Production Example 7: Production of base film D]
A base film D having a thickness of 25 μm, an in-plane retardation Re of 20 nm, and a retardation Rth in the thickness direction of 5 nm was obtained in the same manner as in Production Example 4 except that the film forming conditions were changed.

[Production Example 8: Production of base film E]
A base film E having a thickness of 25 μm, an in-plane retardation Re of 5 nm, and a thickness direction retardation Rth of 25 nm was obtained in the same manner as in Production Example 4 except that the film forming conditions were changed.

[Production Example 9: Production of base film F]
A base film F having a thickness of 25 μm, an in-plane retardation Re of 20 nm, and a thickness direction retardation Rth of 20 nm was obtained in the same manner as in Production Example 4 except that the film forming conditions were changed.

[Example 1]
(Manufacture of thread material A)
The surface of the circularly polarized light separating film a of the polarized light separating film a produced in Production Example 2 (the surface opposite to the support) was subjected to a corona discharge treatment. Further, both surfaces of the base film A manufactured in Production Example 4 were subjected to corona discharge treatment. A roller is connected between the corona discharge-treated surface of the circularly polarized light separating film a and one of the corona discharge-treated surfaces of the substrate film A via an ultraviolet curable adhesive (ADEKA ARKULS KRX-7007 manufactured by ADEKA). And bonded together. The adhesive is irradiated with ultraviolet rays of 200 mJ / cm ² under a nitrogen atmosphere and cured to obtain a laminate having a layer structure of “support / circularly polarized light separating film a / adhesive layer / base film A”. Was. The support was peeled from the laminate to obtain an intermediate film. The surface of the intermediate film on the side of the circularly polarized light separating film a (the surface of the circularly polarized light separating film a that appeared due to the peeling of the support) was subjected to a corona discharge treatment. A 5% by weight aqueous solution of polyvinyl alcohol was applied to both surfaces of the intermediate film using a # 2 wire bar, and the coating film was dried to form a 0.1 μm-thick hydrophilic layer. Polyvinyl alcohol softens or melts in the drying zone of the paper machine and functions as an adhesive capable of bonding the fiber and the thread material A. As a result, a raw sheet having a layer structure of “hydrophilic layer / circularly polarized light separating film a / adhesive layer / base film A / hydrophilic layer” was obtained.

(4) The raw sheet was punched out using a punch having a hexagonal shape with a tip of 2 mm on the opposite side to produce a hexagonal strip-shaped thread material A in large quantities.

(Manufacture of stock)
30 parts by weight of NBKP (softwood bleached kraft pulp) and 70 parts by weight of LBKP (hardwood bleached kraft pulp) were mixed with C.I. S. F. Was beaten into 360 mL of filtered water, and 15 parts by weight of kaolin, 0.5 part by weight of a paper strength agent (“Polystron 117” manufactured by Arakawa Chemical Industries, Ltd.), and a sizing agent (“Size Pine E” manufactured by Arakawa Chemical Industries, Ltd.) )) 1.0 part by weight and an appropriate amount of a sulfuric acid band (aluminum sulfate) were added to prepare a slurry. This slurry was mixed with the thread material A to obtain a first stock. The amount of the thread material A was adjusted so that the weight of the thread material A contained in the anti-counterfeit paper was 1.5% by weight with respect to the dry weight of the anti-counterfeit paper 100% by weight.
The slurry containing no thread material A was prepared as a second stock.

(Manufacture of anti-counterfeit paper)
A 4-tank round web paper machine was prepared. This paper machine was provided with a first tank, a second tank, a third layer, and a fourth tank in order from the upstream in the web flow direction.
The first stock containing the thread material A was supplied to the first tank and the fourth tank of the paper machine. Further, a second stock containing no thread material A was supplied to the second tank and the third tank of the paper machine. Then, a web having a four-layer structure is prepared from the stock according to a conventional method, and the web is dried with a first-group multi-cylinder cylinder drier and polyvinyl alcohol (manufactured by Kuraray Co., Ltd.) using a size press. Application of a 5% aqueous solution of "Kuraray PVA117") and drying using a multi-cylinder cylinder dryer of the second group were performed in this order to obtain a forgery prevention paper. This forgery prevention paper is a four-layered paper including the first paper layer to the fourth paper layer corresponding to the first tank to the fourth tank in this order in the thickness direction, and the basis weight of the whole paper is 100 g. / M ² , and the basis weight of each of the first to fourth paper layers was 25 g / m ² . The thread material A was included only in the first and fourth paper layers as outer layers, and was not included in the second and third paper layers as inner layers.
The anti-counterfeit paper thus obtained was evaluated by the method described above.

[Example 2]
Instead of the polarization separation film a manufactured in Production Example 2, the polarization separation film b manufactured in Production Example 3 was used. Further, the substrate film B manufactured in Production Example 5 was used instead of the substrate film A manufactured in Production Example 4. Except for the above, the same operation as in Example 1 was performed to produce a thread material B having a layer configuration of “hydrophilic layer / circularly polarized light separating film b / adhesive layer / base film B / hydrophilic layer”. In addition, manufacture and evaluation of forgery prevention paper containing the thread material B were performed.

[Example 3]
(Manufacture of thread material C)
The surface of the circularly polarized light separating film a of the polarized light separating film a produced in Production Example 2 (the surface opposite to the support) was subjected to a corona discharge treatment. Further, both surfaces of the base film B produced in Production Example 5 were subjected to corona discharge treatment. The corona discharge-treated surface of the circularly polarized light separating film a and one of the corona discharge-treated surfaces of the base film B are fixed with a roller via an ultraviolet curable adhesive (“ADEKA ARKULZ KRX-7007” manufactured by ADEKA). And bonded together. The adhesive is cured by irradiating it with ultraviolet rays of 200 mJ / cm ² under a nitrogen atmosphere to obtain a laminate having a layer structure of “support / circularly polarized light separating film a / adhesive layer / base film B”. Was. The support was peeled from the laminate to obtain a first intermediate film. The surface of the first intermediate film on the side of the circularly polarized light separating film a (the surface of the circularly polarized light separating film a that appeared due to the peeling of the support) was subjected to a corona discharge treatment.

Another base film B was prepared, and both surfaces of the base film B were subjected to corona discharge treatment. The one corona-discharge treated surface of the base film B and the corona-discharge treated surface of the circularly polarized light separating film a of the first intermediate film were bonded to each other with an ultraviolet-curable adhesive ("ADEKA ARKLES KRX-7007" manufactured by ADEKA). And bonded using a roller. The adhesive is irradiated with ultraviolet rays of 200 mJ / cm ² under a nitrogen atmosphere to be cured to form a layer structure of “base film B / adhesive layer / circularly polarized light separating film a / adhesive layer / base film B”. To obtain a second intermediate film.

(5) A 5% by weight aqueous solution of polyvinyl alcohol was applied to both surfaces of the second intermediate film using a # 2 wire bar, and the coating film was dried to form a 0.1 μm-thick hydrophilic layer. As a result, a raw sheet having a layer structure of “hydrophilic layer / base film B / adhesive layer / circularly polarized light separating film a / adhesive layer / base film B / hydrophilic layer” was obtained.

(4) The raw material sheet was punched out using a punch having a hexagonal shape with a tip of 2 mm on the opposite side to produce a hexagonal strip-shaped thread material C in large quantities.

(Manufacture of stock and forgery prevention paper)
The process (manufacture of stock) and the process (manufacture of anti-counterfeit paper) of Example 1 were performed except that the thread material C manufactured in this example was used instead of the thread material A manufactured in Example 1. The same operation was performed to manufacture and evaluate anti-counterfeit paper containing thread material C.

[Example 4]
Instead of the polarization separation film a manufactured in Production Example 2, the polarization separation film b manufactured in Production Example 3 was used. Further, the base film C manufactured in Preparation Example 6 was used instead of the base film A manufactured in Preparation Example 4. Except for the above, the same operation as in Example 1 was performed to produce a thread material D having a layer configuration of “hydrophilic layer / circularly polarized light separating film b / adhesive layer / base film C / hydrophilic layer”. In addition, manufacture and evaluation of forgery prevention paper containing the thread material D were performed.

[Comparative Example 1]
Instead of the polarization separation film a manufactured in Production Example 2, the polarization separation film b manufactured in Production Example 3 was used. Further, the base film D manufactured in Preparation Example 7 was used instead of the base film A manufactured in Preparation Example 4. Except for the above, the same operation as in Example 1 was performed to manufacture a thread material E having a layer configuration of “hydrophilic layer / circularly polarized light separating film b / adhesive layer / base film D / hydrophilic layer”. In addition, manufacture and evaluation of forgery prevention paper containing the thread material E were performed.

[Comparative Example 2]
The substrate film E manufactured in Production Example 8 was used instead of the substrate film A manufactured in Production Example 4. Except for the above, the same operation as in Example 1 was performed to produce a thread material F having a layer configuration of “hydrophilic layer / circularly polarized light separating film a / adhesive layer / base film E / hydrophilic layer”. In addition, manufacture and evaluation of forgery prevention paper containing the thread material F were performed.

[Comparative Example 3]
Instead of the polarization separation film a manufactured in Production Example 2, the polarization separation film b manufactured in Production Example 3 was used. Further, in place of the base film A manufactured in Preparation Example 4, the base film F manufactured in Preparation Example 9 was used. Except for the above, the same operation as in Example 1 was performed to produce a thread material G having a layer configuration of “hydrophilic layer / circularly polarized light separating film b / adhesive layer / base film F / hydrophilic layer”. In addition, manufacture and evaluation of anti-counterfeit paper containing the thread material G were performed.

[Comparative Example 4]
Instead of the polarization separation film a manufactured in Production Example 2, the polarization separation film b manufactured in Production Example 3 was used. Further, a polyethylene terephthalate film having a thickness of 25 μm (in-plane retardation Re = 263 nm, retardation in the thickness direction Rth = 761 nm) was used instead of the base film A produced in Production Example 4. Except for the above, the same operation as in Example 1 was performed to produce a thread material H having a layer configuration of “hydrophilic layer / circularly polarized light separating film b / adhesive layer / polyethylene terephthalate film / hydrophilic layer”, and The production and evaluation of anti-counterfeit paper containing the thread material H were performed.

[result]
The results of the above Examples and Comparative Examples are shown in the following table. Further, in each of the above Examples and Comparative Examples, all the thread members provided on the forgery prevention paper maintained the hexagonal shape before papermaking.

REFERENCE SIGNS LIST 100 thread material 110 first base film 120 reflective polarizer 200 anti-counterfeit paper 210 right circular polarizing plate 220 left circular polarizing plate 300 thread material 310 second base film

Claims

A thread material for providing on forgery prevention paper,
The thread material, comprising a first base film formed of a resin, a reflective polarizer,
The in-plane retardation of the first base film at a measurement wavelength of 590 nm is 10 nm or less;
A thread material, wherein a retardation in a thickness direction of the first base film at a measurement wavelength of 590 nm is from -10 nm to 10 nm.
The thread material according to claim 1, wherein the reflective polarizer is a circularly polarized light separating element.
The thread material further includes a second base film,
The in-plane retardation of the second base film at a measurement wavelength of 590 nm is 10 nm or less,
The thread material according to claim 1, wherein a retardation in a thickness direction of the second base film at a measurement wavelength of 590 nm is from -10 nm to 10 nm.
(4) Anti-counterfeit paper comprising the thread material according to any one of (1) to (3).
(4) A method for producing forgery-prevention paper, comprising papermaking the paper material containing the thread material according to any one of (1) to (3).