Identification element, identification object containing the identification element, and identification method

Abstract

The present invention relates to the field of identification media, and more specifically, to an identification element, an identification object comprising the identification element, and an identification method. An identification element comprises a stacked phase difference layer and an ink layer, wherein the ink layer comprises a cholesteric liquid crystal ink layer, wherein the phase difference layer and the ink layer are at least partially stacked. The present invention provides a phase difference layer on the identification element, thereby reducing the difficulty of identification, thereby providing an identification element that can be switched and changed in brightness or color simply by being illuminated by a mobile phone screen and when the mobile phone screen is rotated; and further improving the security of the identification element, thereby providing an identification element that can be identified simply by being illuminated by a mobile phone screen, has a graphic design, and can switch in brightness or color and pattern when the mobile phone screen is rotated.

Description

Technical Field

[0001] The present invention relates to the field of identification media, and more particularly, to an identification element, an identification object comprising the identification element, and an identification method. Background Art

[0002] Patent 202080053840.8 provides a composite pigment, an identification medium, and a method for determining authenticity, wherein the identification medium includes a resin containing a binder and a pigment, and is identified by left-handed circular polarizers and right-handed circular polarizers, etc., but there is a certain degree of identification difficulty. Similarly, patent 201921427502.7 provides an optical film that can be identified by a smartphone, including a liquid crystal film layer group, an absorption layer, and a substrate layer, and the difficulty of identification needs to be improved. Patent CN100416312C discloses a two-layer medium in which left-handed and right-handed cholesteric liquid crystals are stacked on each other. This invention has the following shortcomings, which weakens the ease of identification: First, only one color can be observed in a single identifier window; second, the color displayed in the identifier window is constant; third, the identifier is not easy to obtain, which limits the convenience and popularity of identification.

[0003] In order to increase the convenience of identification, the present invention proposes a new security and anti-counterfeiting solution. Summary of the Invention

[0004] In response to some problems existing in the prior art, the first aspect of the present invention provides an identification element comprising a stacked phase difference layer and an ink layer, wherein the ink layer comprises a cholesteric liquid crystal ink layer, wherein the phase difference layer and the ink layer are at least partially stacked.

[0005] Preferably, the optical delay range of the phase difference layer is ( to ), n is an integer greater than or equal to 0, and λ is the wavelength of the reflected light. Further preferably, the optical delay range of the phase difference layer is

[0006] ( to ).

[0007] In the cholesteric liquid crystal ink layer of the present application, the cholesteric liquid crystal exists in the ink in the form of a pigment and is attached to the substrate by printing.

[0008] The method for preparing the cholesteric liquid crystal pigment in the present invention is not particularly limited and can be conventionally selected by those skilled in the art. For example, the method described in US Patent No. 5,942,030A. In one embodiment, the method for preparing the cholesteric liquid crystal pigment includes: 1) applying a polymerizable cholesteric liquid crystal to a substrate surface; 2) orienting the liquid crystal; 3) polymerizing the liquid crystal; 4) optionally, repeating steps 1-3 to complete the formation of more cholesteric liquid crystal layers; 5) separating the polymer film from the substrate surface and crushing the polymer film to form pigment particles, thereby completing the preparation of the cholesteric liquid crystal pigment.

[0009] In addition, the preparation method of the ink in this application is not particularly limited, and those skilled in the art can make conventional selections, such as the method mentioned in patent US9840632B2.

[0010] In the present invention, the method of printing ink onto the identification object is not particularly limited, and those skilled in the art can make conventional choices, such as silk screen printing, offset printing, gravure printing, embossing, and inkjet printing.

[0011] In one embodiment, the ink layer further includes a non-cholesteric liquid crystal ink layer, which is disposed on the left and right sides of the cholesteric liquid crystal ink layer. When a light source emitting polarized light is used to illuminate the identification element, and the polarized light source or the identification element is rotated, the brightness of the light reflected by the cholesteric liquid crystal ink layer changes, while the brightness of the light reflected by the non-cholesteric liquid crystal ink layer remains unchanged, resulting in a sharp contrast in the brightness of the light reflected from different areas.

[0012] Preferably, the color difference between the cholesteric liquid crystal ink layer and the non-cholesteric liquid crystal ink layer is ΔE ≤ 6.5, more preferably ΔE ≤ 3.2, and even more preferably ΔE ≤ 1.6. The smaller the color difference between the cholesteric liquid crystal ink layer and the non-cholesteric liquid crystal ink layer, the closer the apparent colors of the two regions. When observed with the naked eye, ink regions with consistent apparent colors are observed. When a light source capable of emitting polarized light is used to illuminate the identification element, and the polarized light source or the identification element is rotated, the brightness of the light reflected from the cholesteric liquid crystal ink layer changes, while the brightness of the light reflected from the non-cholesteric liquid crystal ink layer remains unchanged, resulting in a clear contrast in the brightness of the light reflected from the two regions.

[0013] Preferably, the cholesteric liquid crystal ink layer comprises a left-handed cholesteric liquid crystal ink layer and a right-handed cholesteric liquid crystal ink layer. When a light source emitting polarized light is used to illuminate the identification element, and the polarized light source or the identification element is rotated, the brightness of the light reflected by the left-handed cholesteric liquid crystal ink layer and the right-handed cholesteric liquid crystal ink layer alternately changes from bright to dark.

[0014] Preferably, the cholesteric liquid crystal ink layer comprises a left-handed cholesteric liquid crystal stacked ink layer composed of liquid crystal pigments formed by stacking a left-handed cholesteric liquid crystal layer and a right-handed cholesteric liquid crystal layer.

[0015] When a left-handed cholesteric liquid crystal layer and a right-handed cholesteric liquid crystal layer are stacked to form a liquid crystal pigment, the number of left-handed cholesteric liquid crystal layers and right-handed cholesteric liquid crystal layers is not particularly limited. In one embodiment, the left-handed cholesteric liquid crystal layer comprises at least two left-handed cholesteric liquid crystal layers and two right-handed cholesteric liquid crystal layers. The color difference ΔE between the left-handed cholesteric liquid crystal layer and the right-handed cholesteric liquid crystal layer is ≥ 6.5, preferably ≥ 13, and more preferably ≥ 25.

[0016] When the left-handed cholesteric liquid crystal layer and the right-handed cholesteric liquid crystal layer are stacked up and down, the preparation method can be to first coat the left-handed cholesteric liquid crystal layer or the right-handed cholesteric liquid crystal layer on the substrate, dry and cross-link and solidify, and then coat the right-handed cholesteric liquid crystal layer or the left-handed cholesteric liquid crystal layer thereon, dry and cross-link and solidify to form a left-handed cholesteric liquid crystal stack.

[0017] When the left-handed cholesteric liquid crystal layer and the right-handed cholesteric liquid crystal layer are stacked up and down, the color of the reflected light after the left-handed cholesteric liquid crystal reflective layer and the right-handed cholesteric liquid crystal reflective layer are superimposed is a mixture of the colors of their respective reflected light, which conforms to the addition rule. For example, the color of the reflected light after the red left-handed liquid crystal layer is superimposed on the green right-handed liquid crystal layer is yellow. From the perspective of recognition, without the help of tools, the human eye cannot distinguish which specific colors the stacked color is composed of. However, with the help of a circular polarizer, the additive color can be restored, that is, only the red left-handed liquid crystal layer can be observed through the left-handed circular polarizer, and only the green right-handed liquid crystal layer can be observed through the right-handed circular polarizer. In view of this, in order to enable the observer to identify more easily with the help of tools, the color contrast between the left-handed liquid crystal layer and the right-handed liquid crystal layer should be as large as possible. The inventors discovered that when the color difference between the left-handed and right-handed liquid crystal layers is ΔE ≥ 6.5, a slightly noticeable color difference can be discerned. When ΔE ≥ 13, a more noticeable color difference can be discerned. When ΔE ≥ 25, a very noticeable color difference can be discerned. When a light source emitting polarized light is used to illuminate the identification element, and the polarized light source or the identification element is rotated, the color of the ink layer changes. The greater the color difference, the more noticeable the color change between the left-handed and right-handed liquid crystal layers.

[0018] Preferably, the left-handed cholesteric liquid crystal ink layer and the right-handed cholesteric liquid crystal ink layer are distributed left and right.

[0019] When the left-handed cholesteric liquid crystal ink layer and the right-handed cholesteric liquid crystal ink layer are distributed on the left and right sides, the color difference between the left-handed cholesteric liquid crystal ink layer and the right-handed cholesteric liquid crystal ink layer is ΔE≤6.5, preferably, ΔE≤3.2, and more preferably, ΔE≤1.6. The smaller the color difference between the left-handed cholesteric liquid crystal ink layer and the right-handed cholesteric liquid crystal ink layer, the closer the appearance colors of the two regions are. When observed with the naked eye, when the color difference between the left-handed cholesteric liquid crystal ink layer and the right-handed cholesteric liquid crystal ink layer is ΔE≤6.5, preferably, ΔE≤3.2, and more preferably, ΔE≤1.6, ink regions with consistent appearance colors are observed. When a light source capable of emitting polarized light is used to illuminate the identification element, and the polarized light source or the identification element is rotated, the brightness of the light reflected by the left-handed cholesteric liquid crystal ink layer and the right-handed cholesteric liquid crystal ink layer changes alternately between bright and dark.

[0020] In one embodiment, the cholesteric liquid crystal ink layer includes a left-handed cholesteric liquid crystal stacked ink layer and a second cholesteric liquid crystal ink layer disposed to the left and right of the left-handed cholesteric liquid crystal stacked ink layer. The cholesteric liquid crystals contained in the second cholesteric liquid crystal ink layer can be either left-handed or right-handed cholesteric liquid crystals. The apparent colors of different regions can be similar or identical, or they can differ significantly. The color difference ΔE between the left-handed cholesteric liquid crystal stacked ink layer and the second cholesteric liquid crystal ink layer is ≤ 6.5, preferably ≤ 3.2, and more preferably ≤ 1.6.

[0021] In one embodiment, in the identification element of the present invention, the cholesteric liquid crystal ink of the cholesteric liquid crystal layer in the ink layer includes a left-handed cholesteric liquid crystal pigment and a right-handed cholesteric liquid crystal pigment. The weight ratio of the left-handed cholesteric liquid crystal pigment to the right-handed cholesteric liquid crystal pigment is in the range of 1:100 to 100:1. The ink layer includes at least two cholesteric liquid crystal ink regions, at least one of which includes a left-handed cholesteric liquid crystal pigment and a right-handed cholesteric liquid crystal pigment. Preferably, the two cholesteric liquid crystal inks include a left-handed cholesteric liquid crystal pigment and a right-handed cholesteric liquid crystal pigment, and the weight ratios of the left-handed cholesteric liquid crystal pigment to the right-handed cholesteric liquid crystal pigment in the two regions are different.

[0022] In one embodiment, the identification element further comprises a background substrate, and the cholesteric liquid crystal ink layer is printed on the background substrate.

[0023] It should be noted that when the identification element does not include a background substrate, the ink layer is printed on the phase difference layer.

[0024] In one embodiment, the color difference between the cholesteric liquid crystal ink layer and the background substrate is ≥13, preferably ≥25. In the present invention, when the color difference between the cholesteric liquid crystal ink layer and the background substrate is ≥13, the color difference between the cholesteric liquid crystal and the background substrate can be clearly discerned. When a polarized light source is used to illuminate the identification element from the phase difference layer side and the polarized light source or the identification element is rotated, the contrast between light reflected from the cholesteric liquid crystal ink layer is more pronounced. When ΔE is ≥25, the color difference between the cholesteric liquid crystal ink layer and the background substrate can be very clearly discerned. When a polarized light source is used to illuminate the identification element from the phase difference layer side and the polarized light source or the identification element is rotated, the contrast between light reflected from the cholesteric liquid crystal ink region is very pronounced.

[0025] Preferably, the background substrate is a colored background substrate with a significant color difference from the cholesteric liquid crystal ink layer. Further preferably, the background substrate is a dark background substrate that absorbs light transmitted through the cholesteric liquid crystal ink layer. The background substrate can be a phase-difference polymer film that can be printed on the ink layer, or a background substrate that absorbs light transmitted through the cholesteric liquid crystal ink as part of an identification object. Phase-difference polymer films are typically highly transparent substrates. When used as a printing substrate, the phase-difference polymer film is further coated with an ink layer that absorbs light transmitted through the cholesteric liquid crystal ink, or a polymer film printed with a cholesteric liquid crystal ink layer is overlaid on the background substrate that absorbs light transmitted through the cholesteric liquid crystal ink.

[0026] The material of the phase difference layer in the present invention is not particularly limited, and those skilled in the art can make conventional selections. In one embodiment, the material of the phase difference layer is a polymer film and / or a liquid crystal polymer film.

[0027] Examples of the high molecular polymer film in the present invention include polypropylene (PP), polyurethane (PU), thermoplastic polyurethane (TPU), polyvinyl chloride (PVC), polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyvinyl alcohol (PVA), polycarbonate (PC), triacetyl cellulose (TAC), polymethyl methacrylate (PMMA), polyimide (PI), etc. Preferably, the high molecular polymer film is selected from any one of polypropylene (PP), polyethylene terephthalate (PET), polyethylene naphthalate (PEN), more preferably polypropylene (PP).

[0028] When the material of the phase difference layer in the present invention is a polymer film, the phase delay caused by the polymer film comes from the unidirectional or bidirectional stretching during the production process. Under a suitable stretching ratio and a suitable thickness, the phase delay of the polymer film can meet the above constraints. The specific stretching ratio and thickness can be obtained by those skilled in the art based on existing technology or limited experiments.

[0029] The method for preparing the recognition element in the present invention is not particularly limited and can be conventionally selected by those skilled in the art.

[0030] When the material of the phase difference layer is a liquid crystal polymer film, a person skilled in the art can make a conventional selection of the preparation method of the liquid crystal polymer film, for example, nematic liquid crystal is formed by photo-alignment, or obtained by the method described in patent US20080291389.

[0031] When the phase difference layer is a polymer film, the method for preparing the identification element includes: directly printing a cholesteric liquid crystal ink layer onto the polymer film. Specifically, the polymer film serves as both a phase difference layer to adjust the polarization state of light reflected by the cholesteric liquid crystal and a substrate for printing the cholesteric liquid crystal ink, thereby forming an identification object with the identification element. In this case, the identification object has dual-sided identification capabilities. That is, the identification element exhibits different optical characteristics when viewed through the substrate and when viewed directly, further enhancing the security of the identification element.

[0032] In one embodiment, the retardation layer is made of a laminated high molecular polymer film and a liquid crystal polymer film. Preferably, the retardation layer has a patterned optical axis orientation, with the angle between the optical axes being 90°. When the identification element is illuminated by a light source emitting polarized light, without rotating the polarized light source or the identification element, different areas of the ink layer exhibit different colors and / or intensities.

[0033] The identification element of the present invention, the polymer film is used as an outer packaging material. The phase difference of the polymer film is ( to ), n is an integer of 0, 1, 2, 3, 4, etc., and λ is the wavelength of the reflected light. to ) range.

[0034] A second aspect of the present invention provides an identification object comprising the identification element.

[0035] The third aspect of the present invention provides a method for identifying the identification element of the present invention, which comprises irradiating the identification element from one side of the phase difference layer with a polarized light source, rotating the polarized light source or the identification element, and observing changes in brightness and / or appearance color of the identification element.

[0036] The polarized light source in the present invention includes a bright mobile phone screen or a bright computer screen.

[0037] The present invention also provides a method for identifying the identification object using a left-handed circular polarizer or a right-handed circular polarizer identifier, specifically placing the left-handed circular polarizer or the right-handed circular polarizer identifier above the identification object, and observing the changes in the brightness and / or appearance color of the identification element in the identification object through the identifier.

[0038] The present invention also provides a method for identifying the identification object using a dual-window identifier composed of a left-handed circular polarizer and a right-handed circular polarizer. Specifically, the dual-window identifier composed of a left-handed circular polarizer and a right-handed circular polarizer is placed above the identification object, and the changes in the brightness and / or appearance color of the identification elements in the identification object under different windows are observed through the identifier.

[0039] Compared with the prior art, the present invention has the following beneficial effects:

[0040] 1. The present invention provides a phase-difference layer on the identification element, which reduces the difficulty of identification, thereby providing an identification element that can switch brightness or color when the phone screen is rotated and illuminated by the phone screen;

[0041] 2. The present invention adds a graphic phase difference layer to the identification element, further improving the security of the identification element, thereby providing an identification element that can be identified simply by illuminating it with a mobile phone screen, and that has a graphic design and can switch brightness, color, and pattern when the mobile phone screen is rotated. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 This is a schematic structural diagram of the identification element of Example 1;

[0043] Figure 2 This is a schematic diagram of the structure of the identification element of Example 2;

[0044] Figure 3 This is a schematic diagram of the structure of the identification element of Example 3;

[0045] Figure 4 This is a schematic diagram of the structure of the identification element of Example 4;

[0046] Figure 5 This is a schematic diagram of the structure of the identification element of Example 5;

[0047] Figure 6 This is a schematic diagram of the structure of the identification element of Example 6;

[0048] Among them, 1-ink layer; 2-phase difference layer; 1L-R-left-handed cholesteric liquid crystal layer with a red appearance color; 1NLC-R is a red non-cholesteric ink layer; 1R-G is a right-handed cholesteric liquid crystal layer with a green appearance color; 1R-R is a right-handed cholesteric liquid crystal layer with a red appearance color; 1R-Y is a right-handed cholesteric liquid crystal layer with a yellow appearance color. DETAILED DESCRIPTION

[0049] The present invention is described below by way of specific embodiments, but is not limited to the specific embodiments given below.

[0050] Example 1

[0051] An identification element, such as Figure 1 As shown, it includes a cholesteric liquid crystal ink layer 1 and a phase difference layer 2 stacked up and down. The material of the phase difference layer 2 is a polymer film. Specifically, TORAYFAN TM A 30μm PP film was used as a phase difference film. The Axoscan test showed that the phase retardation at different positions was between 75-87nm. This PP film was used as a substrate for cholesteric liquid crystal ink, and the cholesteric liquid crystal ink was printed directly on the PP surface.

[0052] The manufacturing method of the identification element is as follows:

[0053] (1) Preparation of cholesteric liquid crystal pigments:

[0054] The PET substrate was coated with a red L-cholesteric liquid crystal coating liquid using a gravure coating method, with a wet coating amount of 10-12 g / sqm. After drying and orientation at 80°C, the coating was cross-linked and cured under a high-pressure mercury lamp with a curing energy of 0.6 J / cm. 2 The liquid crystal film was peeled off from the PET surface, ground using a grinder, and sieved through a 400-mesh sieve to obtain a cholesteric liquid crystal pigment with an average particle size of 50 μm.

[0055] (2) Preparation of cholesteric liquid crystal ink:

[0056] The formula of liquid crystal ink is as follows:

[0057]

[0058] Firstly, the cholesteric liquid crystal pigment is dispersed in a dispersant, a solvent, and a UV active diluent, and then the remaining materials are added and fully mixed to obtain a cholesteric liquid crystal ink.

[0059] (3) Fabrication of identification elements

[0060] The cholesteric liquid crystal ink was printed onto the TORAYFAN screen using a screen printer and a 300 mesh screen. TM The printed product was then UV-cured in a drying unit, achieving a dry film thickness of 15 microns. The cholesteric liquid crystal ink side of the identification element was placed in contact with blue paper, with the PP film positioned toward the viewing surface. The color difference between the cholesteric liquid crystal ink layer and the blue paper background was 17.

[0061] Example 2

[0062] An identification element, such as Figure 2As shown, the left-handed cholesteric liquid crystal layer 1L-R and the phase difference layer 2 are stacked on top of each other, and the left-handed cholesteric liquid crystal layer 1L-R and the phase difference layer 2 are partially stacked.

[0063] The cholesteric liquid crystal ink obtained in Example 1 was printed onto 120 g / sqm black coated paper using a screen printer and a 300 mesh screen. The printed product was dried and then UV cured to obtain a dry film thickness of 15 μm. A two-component polyurethane composite adhesive was used to partially laminate the ink layer. TM 50μm PP film (optical retardation between 125-134nm). The color difference between cholesteric liquid crystal ink and black paper is 54.

[0064] Example 3

[0065] An identification element, such as Figure 3 As shown, it includes an ink layer 1 and a phase difference layer 2 stacked on top of each other, and the ink layer 1 and the phase difference layer 2 are completely stacked. The ink layer 1 includes a red non-cholesteric ink layer 1NLC-R and a left-handed cholesteric liquid crystal layer 1L-R with a red appearance color.

[0066] The cholesteric liquid crystal ink obtained in Example 1 and the red screen UV ink commonly used on the market were printed using a screen printer with an overprint function and an ultraviolet curing unit. The substrate was 120g / sqm blue paper, and the printed pattern was the word "30", of which 3 was printed with cholesteric liquid crystal ink and pattern 0 was printed with red screen UV ink. The printed product was rapidly UV-cured after passing through the drying unit, and the dry film thickness was 15 microns. The color difference value ΔE between the color of the cholesteric liquid crystal ink area and the color of the red ink area was 2.7. The printed product printed with the ink layer was used as a packaging box material. The outer surface of the packaging box, i.e., the surface of the ink layer, was covered with TORAYFAN TM 50μm PP film (optical retardation is between 125-134nm) (PP film is used as the protective film of the packaging box).

[0067] Example 4

[0068] An identification element, such as Figure 4 As shown, the ink layer 1 and the phase difference layer 2 are stacked one on top of the other, and the ink layer 1 and the phase difference layer 2 are completely stacked. The ink layer 1 is a left-handed cholesteric liquid crystal stacked ink layer composed of yellow liquid crystal pigments formed by stacking a right-handed cholesteric liquid crystal layer 1R-G with a green appearance and a left-handed cholesteric liquid crystal layer 1L-R with a red appearance.

[0069] The PET substrate was coated with a red L-cholesteric liquid crystal coating liquid using a gravure coating method, with a wet coating amount of 10-12 g / sqm. After drying and orientation at 80°C, the coating was cross-linked and cured under a high-pressure mercury lamp with a curing energy of 0.6 J / cm. 2 A green dextrorotatory cholesteric liquid crystal coating with a wet coating weight of 10-12 g / sqm was applied to the surface of the left-handed cholesteric liquid crystal layer; after drying and alignment at 80°C, cross-linking and curing were performed under a high-pressure mercury lamp with a curing energy of 0.6 J / cm 2 The color difference between the red left-handed cholesteric liquid crystal layer and the green right-handed cholesteric liquid crystal layer was ΔE = 39. The cholesteric liquid crystal laminate had a yellow appearance. The liquid crystal film was peeled off from the PET surface, ground using a grinder, and sieved through a 400-mesh sieve to obtain a cholesteric liquid crystal pigment with an average particle size of 50 μm.

[0070] Cholesteric liquid crystal ink was prepared according to the method described in Example 1.

[0071] The phase difference layer 2 of this embodiment is made of a liquid crystal polymer film. The preparation method of the liquid crystal polymer film is as follows: a nematic liquid crystal coating liquid is applied to the PET surface after being rubbed with a flannel cloth, with a wet coating amount of 5 g / sqm (dry coating amount of 1.15 g / sqm); after drying and orientation at 80°C, the film is cross-linked and cured under a high-pressure mercury lamp at a curing energy of 0.6 J / cm 2 The optical retardation measured by Axoscan was 125 nm.

[0072] The left-handed and right-handed cholesteric liquid crystal stack inks described in this example were printed onto 120 g / sq m black coated paper using a screen printer and a 300-mesh screen. The printed products were then UV-cured in a drying unit to a dry film thickness of 15 μm. The liquid crystal polymer retardation layer was then transferred to the surface of the ink layer using a two-component polyurethane composite adhesive.

[0073] Example 5

[0074] An identification element, such as Figure 5 As shown, it includes an ink layer 1 and a phase difference layer 2 stacked on top of each other, and the ink layer 1 and the phase difference layer 2 are completely stacked. The ink layer 1 includes a right-handed cholesteric liquid crystal layer 1R-R with a red appearance color and a left-handed cholesteric liquid crystal layer 1L-R with a red appearance color.

[0075] A red L-cholesteric liquid crystal ink and a red D-cholesteric liquid crystal ink were prepared according to the method described in Example 1. The L-cholesteric liquid crystal ink and the D-cholesteric liquid crystal ink were printed using a screen printer equipped with an overprint function and a UV curing unit. The color difference ΔE between the L-cholesteric and D-cholesteric liquid crystal regions was 1.2.

[0076] The PET surface was coated with a photo-alignment coating liquid with a wet coating amount of 5 g / sqm; after drying and alignment at 80°C, a patterned exposure was performed under a linear polarized high-pressure mercury lamp. The pattern was composed of small five-pointed stars and the exposure energy was 0.1 J / cm 2 Subsequently, a nematic liquid crystal coating liquid was applied on the surface of the substrate, with a wet coating amount of 5 g / sqm (dry coating amount of 1.15 g / sqm); after drying and orientation at 80°C, cross-linking and curing were carried out under a high-pressure mercury lamp with a curing energy of 0.6 J / cm 2 Axoscan measurements showed a phase retardation of 125 nm for the nematic liquid crystal layer. Polarizing microscope analysis revealed an 89° angle between the optical axes of the different regions of patterned phase difference. The patterned liquid crystal polymer phase difference layer was transferred to the surface of the ink layer using a two-component polyurethane composite adhesive.

[0077] Example 6

[0078] An identification element, such as Figure 6 As shown, the ink layer 1 and the phase difference layer 2 are stacked one on top of the other, and the ink layer 1 and the phase difference layer 2 are completely stacked. The ink layer 1 is a left-handed cholesteric liquid crystal stacked ink layer composed of a yellow liquid crystal pigment formed by stacking a right-handed cholesteric liquid crystal layer 1R-G with a green appearance and a left-handed cholesteric liquid crystal layer 1L-R with a red appearance, and a right-handed cholesteric liquid crystal layer 1R-Y with a yellow appearance is distributed to the left and right of the right-handed cholesteric liquid crystal layer 1R-G and the left-handed cholesteric liquid crystal layer 1L-R.

[0079] A yellow-colored left-handed cholesteric liquid crystal stacked pigment and corresponding ink were prepared using the method described in Example 4. A yellow-colored right-handed cholesteric liquid crystal stacked pigment and corresponding ink were prepared using the method described in Example 1. The color difference between the yellow left-handed cholesteric liquid crystal stack and the yellow right-handed cholesteric liquid crystal was ΔE = 1.6.

[0080] The above-mentioned yellow left-right cholesteric liquid crystal stacking ink layer and yellow right-handed cholesteric liquid crystal ink were printed using a screen printing machine with an overprinting function and a UV curing unit. The substrate was 120g / sqm black paper. The printed pattern was the word "30", where 3 was printed using yellow left-right cholesteric liquid crystal stacking ink, and pattern 0 was printed using yellow right-handed cholesteric liquid crystal ink. The printed product was rapidly UV-cured after passing through a drying unit, and the dry film thickness was 15 microns. The color difference ΔE between the color of the cholesteric liquid crystal ink area and the color of the red ink area was 1.6. The printed product printed with the ink layer was used as a packaging box material. The outer surface of the packaging box, i.e., the surface of the ink layer, was covered with a TORAY 19μm PET film (phase delay of 395-407nm) (the PET film was used as a protective film for the packaging box).

[0081] Comparative Example

[0082] The cholesteric liquid crystal ink surface of the identification element described in Example 1 was placed in contact with red paper, with the PP film close to the observation surface. The color difference between the cholesteric liquid crystal ink and the red paper was 6.

[0083] Identification method

[0084]

[0085] It can be seen that the identification elements and identification methods in this application reduce the difficulty of identification and facilitate identification.

Claims

1. An identification element, characterized in that: The invention comprises a phase difference layer and an ink layer stacked together, wherein the ink layer comprises a cholesteric liquid crystal ink layer, wherein the phase difference layer and the ink layer are at least partially stacked together, and the optical delay range of the phase difference layer is ( to ), n is an integer greater than or equal to 0, λ is the wavelength of the reflected light, the identification element further comprises a background substrate, the cholesteric liquid crystal ink layer is printed on the background substrate, and the color difference between the cholesteric liquid crystal ink layer and the background substrate is ≥25; The cholesteric liquid crystal ink layer comprises a left-handed cholesteric liquid crystal ink layer and a right-handed cholesteric liquid crystal ink layer; when the left-handed cholesteric liquid crystal ink layer and the right-handed cholesteric liquid crystal ink layer are arranged on the left and right sides, the color difference ΔE between the colors of the left-handed cholesteric liquid crystal ink layer and the right-handed cholesteric liquid crystal ink layer is ≤6.5; When the liquid crystal pigment of the cholesteric liquid crystal ink layer is formed by stacking a left-handed cholesteric liquid crystal layer and a right-handed cholesteric liquid crystal layer, the color difference ΔE between the left-handed cholesteric liquid crystal layer and the right-handed cholesteric liquid crystal layer is ≥6.

5.

2. The identification element according to claim 1, characterized in that The ink layer further includes a non-cholesteric liquid crystal ink layer, which is distributed left and right with the cholesteric liquid crystal ink layer or at least partially overlapped with the upper and lower layers.

3. The identification element according to claim 1, characterized in that The color difference ΔE between the colors of the cholesteric liquid crystal ink layer and the non-cholesteric liquid crystal ink layer is ≤6.

5.

4. An identification object comprising the identification element according to any one of claims 1 to 3.

5. A recognition method, characterized in that: A method of illuminating the identification element according to any one of claims 1 to 3 with a polarized light source from one side of the phase difference layer, rotating the polarized light source or the identification element, and observing changes in the brightness and / or appearance color of the identification element; or using an identifier to identify the identification object according to any one of claims 1 to 3.

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