WO2018173767A1

WO2018173767A1 - Charge indicator

Info

Publication number: WO2018173767A1
Application number: PCT/JP2018/008933
Authority: WO
Inventors: 長谷部　浩史; 士朗谷口
Original assignee: Dic株式会社
Priority date: 2017-03-23
Filing date: 2018-03-08
Publication date: 2018-09-27
Also published as: JPWO2018173767A1; JP6607420B2; CN110300898A; JP2020008586A

Abstract

The present invention addresses the problem of providing a static electricity indicator for visualizing a charged location that spatially spreads and that changes moment by moment on a plane surface, and the charge amount of the location. As a result of various investigations, the inventors utilized a liquid crystal composition and used electrodes as necessary, thereby providing a static electricity indicator with which it is possible to visualize a charged position that spatially spreads and that changes moment by moment on a plane surface, and the charge amount of the position, without using a complicated mechanical mechanism.

Description

Charge indicator

The present invention relates to a charging indicator for visualizing a charged state.

∙ It is extremely important to always grasp the charged state over a wide range. For example, in the chemical industry, it is important from the viewpoint of ensuring safety to suppress ignition of organic solvent gas due to static electricity (Patent Documents 1 and 2). However, although it can be known whether or not these are charged, there are problems that the position cannot be specified and that electricity must always be supplied from the outside.

In the semiconductor manufacturing industry, it is important from the viewpoint of yield improvement to prevent damage to the semiconductor elements due to static electricity.

Although it is possible to measure the charged state at a fixed point using a measuring instrument using a commonly used electrode probe (potential sensor), it is difficult to measure over a wide area. In order to solve this problem, a method of measuring the surface charge distribution by scanning the probe in a plane (mechanically moved along the XY axes) has been proposed. However, it takes time to scan the plane. The shortcoming that measurement cannot be performed in an instant, the occurrence of sparks due to mechanical contact due to mechanical scanning, and the configuration becomes complicated, resulting in high costs and malfunctions. There is a drawback that the probability increases and the power consumption during measurement increases (Patent Document 3).

From the above background, there is a strong demand to be able to detect an ever-changing charging situation without using a complicated mechanical mechanism over a wide range.

JP 2004-225200 A JP-A-7-159467 JP-A-11-211771

The problem to be solved by the present invention is to provide a charged place that changes every moment on a wide plane and a static electricity indicator that visualizes the amount of charge.

As a result of various studies, the present inventors have found that by using a liquid crystal composition, it is possible to provide an electrostatic indicator that visualizes the charged position and the charged position that change every moment, The present invention has been completed.

The static electricity indicator using the liquid crystal composition of the present invention can visualize the charged state of the target substance on a wide flat surface and the charged amount and its charge amount which change every moment. Useful for.

The figure which shows an example of a structure of the static electricity indicator of this invention typically (when there is no charged object nearby) The figure which shows an example of a structure of the static electricity indicator of this invention typically (when there exists a charged object nearby) The figure which shows an example of a structure of the static electricity indicator of this invention typically (when the electrode by the side of a charging body is divided into plurality) The figure which shows typically an example of the structure of the static electricity indicator of this invention (the static electricity indicator which installed two or more in parallel) The static electricity indicator shown in FIG. 3 is seen from above (charged body side) ITO patterning diagram Liquid crystal composition and adhesive dripping position Position of ITO patterning substrate and ITO solid substrate (Substrate short side) Appearance of the electrostatic indicator of the present invention

The electrostatic indicator of the present invention can visualize the charged state of a target substance on a wide plane and the charged place and its charged position. The spread flat shape may be a shape of the static electricity indicator such as a triangle, a quadrangle, a disk shape, a rod shape, and the like. It means that it may be curved as well. It is one of the advantages of using a liquid crystal composition that the electrostatic indicator of the present invention can be curved.

The static electricity indicator may be a single device or a plurality of static electricity indicators may be combined into a single device. In addition, the static electricity indicator may be plate-shaped, sheet-shaped, or belt-shaped, and when they are installed, they can be installed as they are, but they are cut to adapt to the required range. It can also be installed. These include rolling and transporting a sheet-like or belt-like static electricity indicator and cutting it to a length suitable for the installation location when installing.

The static electricity indicator uses a liquid crystal composition. By utilizing the fact that the liquid crystal composition changes the alignment state due to static electricity, the electrostatic charge location and the charged position are visualized. As a method of visualizing the change in the alignment state of the liquid crystal composition, a change in refractive index anisotropy (Δn) may be used depending on the change in the alignment state, or a change in the polarization state may be used. What controls scattering may be used, and what is called a guest host system which adds a pigment to a liquid crystal composition may be used. The higher the charged position, the larger the change in the alignment state of the liquid crystal composition, so that the height of the charged position can be visually recognized.
(Liquid crystal composition)
The liquid crystal composition used is a so-called n-type liquid crystal composition having a negative Δε value, even if it is a so-called p-type liquid crystal composition having a positive dielectric anisotropy (Δε). Also good. These liquid crystal compositions are used by appropriately combining a compound represented by general formula (J), a compound represented by general formula (N-1), and a compound represented by general formula (L). I can do it.

The p-type liquid crystal composition preferably contains one or more compounds represented by the general formula (J). These compounds correspond to dielectrically positive compounds (Δε is greater than 2).

(Wherein R ^J1 represents an alkyl group having 1 to 8 carbon atoms, and one or two or more non-adjacent —CH ₂ — in the alkyl group are each independently —CH═CH—, — Optionally substituted by C≡C—, —O—, —CO—, —COO— or —OCO—,
n ^J1 represents 0, 1, 2, 3 or 4;
A ^J1 , A ^J2 and A ^J3 are each independently
(A) 1,4-cyclohexylene group (this is present in the group one -CH ₂ - or nonadjacent two or more -CH ₂ - may be replaced by -O-.)
(B) a 1,4-phenylene group (one —CH═ present in the group or two or more non-adjacent —CH═ may be replaced by —N═) and (c) Naphthalene-2,6-diyl group, 1,2,3,4-tetrahydronaphthalene-2,6-diyl group or decahydronaphthalene-2,6-diyl group (naphthalene-2,6-diyl group or 1,2 , 3,4-tetrahydronaphthalene-2,6-diyl group, one —CH═ or two or more non-adjacent —CH═ may be replaced by —N═.
The group (a), the group (b) and the group (c) are each independently selected from the group consisting of cyano group, fluorine atom, chlorine atom, methyl group, trifluoromethyl group or trifluoro May be substituted with a methoxy group,
Z ^J1 and Z ^J2 are each independently a single bond, —CH ₂ CH ₂ —, — (CH ₂ ) ₄ —, —OCH ₂ —, —CH ₂ O—, —OCF ₂ —, —CF ₂ O—, Represents —COO—, —OCO— or —C≡C—,
When n ^J1 is 2, 3 or 4 and a plurality of A ^J2 are present, they may be the same or different, and n ^J1 is 2, 3 or 4 and a plurality of Z ^J1 is present. If they are the same or different,
X ^J1 represents a hydrogen atom, a fluorine atom, a chlorine atom, a cyano group, a trifluoromethyl group, a fluoromethoxy group, a difluoromethoxy group, a trifluoromethoxy group, or a 2,2,2-trifluoroethyl group. )
The n-type liquid crystal composition preferably contains one or more compounds selected from the compounds represented by formula (N-1). These compounds correspond to dielectrically negative compounds (the sign of Δε is negative and the absolute value is greater than 2).

(Wherein R ^N11 and R ^N12 each independently represents an alkyl group having 1 to 8 carbon atoms, and one or non-adjacent two or more —CH ₂ — in the alkyl group are each independently Optionally substituted by —CH═CH—, —C≡C—, —O—, —CO—, —COO— or —OCO—,
^A ^N11, A ^N12, is one of -CH ₂ present in each in independently (a) 1,4-cyclohexylene group (this group - or nonadjacent two or more -CH ₂ - is - And (b) a 1,4-phenylene group (one —CH═ present in the group or two or more non-adjacent —CH═ represents —N = May be replaced.)
(C) Naphthalene-2,6-diyl group, 1,2,3,4-tetrahydronaphthalene-2,6-diyl group or decahydronaphthalene-2,6-diyl group (naphthalene-2,6-diyl group or One —CH═ present in the 1,2,3,4-tetrahydronaphthalene-2,6-diyl group or two or more non-adjacent —CH═ may be replaced by —N═. )
(D) represents a group selected from the group consisting of 1,4-cyclohexenylene groups, and the groups (a), (b), (c) and (d) are each independently a cyano group, It may be substituted with a fluorine atom or a chlorine atom,
Z ^N11 and Z ^N12 are each independently a single bond, —CH ₂ CH ₂ —, — (CH ₂ ) ₄ —, —OCH ₂ —, —CH ₂ O—, —COO—, —OCO—, —OCF _2- , -CF ₂ O-, -CH = NN-CH-, -CH = CH-, -CF = CF- or -C≡C-
n ^N11 and n ^N12 each independently represents an integer of 0 to 3, n ⁿ¹¹ + n ^N12 each independently represents 1, 2 or 3, and a plurality of A ^N11 to A ^N12 and Z ^N11 to Z ^N12 If present, they may be the same or different. )
The liquid crystal composition of the present invention preferably contains one or more compounds represented by formula (L). The compound represented by the general formula (L) corresponds to a dielectrically neutral compound (Δε value is −2 to 2).

(Wherein R ^L1 and R ^L2 each independently represents an alkyl group having 1 to 8 carbon atoms, and one or two or more non-adjacent —CH ₂ — in the alkyl group are each independently Optionally substituted by —CH═CH—, —C≡C—, —O—, —CO—, —COO— or —OCO—,
n ^L1 represents 0, 1, 2 or 3,
A ^L1 , A ^L2 and A ^L3 each independently represent (a) a 1,4-cyclohexylene group (one —CH ₂ — present in the group or two or more —CH ₂ — not adjacent to each other). May be replaced by —O—) and (b) a 1,4-phenylene group (one —CH═ present in this group or two or more —CH═ not adjacent to each other —N May be replaced by =.)
(C) Naphthalene-2,6-diyl group, 1,2,3,4-tetrahydronaphthalene-2,6-diyl group or decahydronaphthalene-2,6-diyl group (naphthalene-2,6-diyl group or One —CH═ present in the 1,2,3,4-tetrahydronaphthalene-2,6-diyl group or two or more non-adjacent —CH═ may be replaced by —N═. )
The group (a), the group (b) and the group (c) may be each independently substituted with a cyano group, a fluorine atom or a chlorine atom,
Z ^L1 and Z ^L2 are each independently a single bond, —CH ₂ CH ₂ —, — (CH ₂ ) ₄ —, —OCH ₂ —, —CH ₂ O—, —COO—, —OCO—, —OCF ₂ -, -CF ₂ O-, -CH = NN-CH-, -CH = CH-, -CF = CF- or -C≡C-
When n ^L1 is 2 or 3, and a plurality of A ^L2 are present, they may be the same or different, and when n ^L1 is 2 or 3, and a plurality of Z ^L2 are present, May be the same or different, but excludes the compounds represented by formulas (N-1) and (J). )
The composition preferably exhibits a liquid crystal phase at room temperature (25 ° C.), and more preferably exhibits a nematic phase.

There are no particular restrictions on the types of compounds that can be combined, but they are used in combination according to desired properties such as solubility at low temperatures, transition temperatures, electrical reliability, and birefringence. For example, in one embodiment of the present invention, there are one kind, two kinds, and three kinds of compounds to be used. Furthermore, in another embodiment of the present invention, there are four types, five types, six types, and seven or more types.

In order to improve the sensitivity, it is preferable to increase the absolute value of Δε of the liquid crystal composition and to reduce the viscosity (η) of the liquid crystal composition, and in order to increase the absolute value of Δε, the general formula (N It is preferable to increase the content of the compounds represented by -1) and (J). To reduce η, it is preferable to increase the content of the compound represented by the general formula (L).

In order to increase the speed of returning to the original alignment state when the charged potential of the detection target is lowered, it is preferable that the voltage holding ratio of the liquid crystal composition is not so high. In such a case, it is preferable to use a cyano group as the polar substituent of the groups (a), (b) and (c) in the general formulas (J) and (N-1). Specific values of the voltage holding ratio are 20 to 95 when injected into a liquid crystal cell with a cell gap of 5 μm and measured at room temperature (25 ° C.) with a drive voltage of 5 V, a frame time of 16.6 ms, and a voltage application time of 64 μs. %, Preferably 40 to 90%, more preferably 50 to 80%. It is also preferable that the specific resistance of the liquid crystal composition is not so high in order to increase the speed of returning to the original alignment state when the charged potential of the detection target is lowered. Even in such a case, it is preferable to use a cyano group as the polar substituent of the groups (a), (b) and (c) in the general formulas (J) and (N-1). Specifically, it is preferably in the range of 1 × 10 ⁷ to 1 × 10 ¹² cmΩ at 25 ° C., more preferably in the range of 1 × 10 ⁸ to 1 × 10 ¹¹ cmΩ, and 5 × 10 ⁸ to 5 A range of × 10 ¹⁰ cmΩ is particularly preferred.

Even if the charged potential of the object to be detected decreases, the voltage holding ratio of the liquid crystal composition is used for the purpose of analyzing the instantaneous charged state later by holding and storing the charged state. Is preferably increased. In such a case, a fluorine atom, a chlorine atom, a trifluoromethyl group, a fluoromethoxy group as a polar substituent of the groups (a), (b), and (c) in the general formulas (J) and (N-1), A difluoromethoxy group, a trifluoromethoxy group or a 2,2,2-trifluoroethyl group is preferably used, and a fluorine atom is more preferable. The specific value of the voltage holding ratio is 95% or more when injected into a liquid crystal cell with a cell gap of 5 μm and measured at room temperature (25 ° C.) with a drive voltage of 5 V, a frame time of 16.6 ms, and a voltage application time of 64 μs. Preferably, it is 97% or more, more preferably 99% or more. Even if the charged potential of the object to be detected decreases, the voltage holding ratio of the liquid crystal composition is used for the purpose of analyzing the instantaneous charged state later by holding and storing the charged state. Is preferably increased. Even in such a case, a fluorine atom, a chlorine atom, a trifluoromethyl group, a fluoromethoxy group, a polar substituent of the groups (a), (b), and (c) in the general formulas (J) and (N-1), A difluoromethoxy group, a trifluoromethoxy group or a 2,2,2-trifluoroethyl group is preferably used, and a fluorine atom is more preferable.
Specifically, it is preferably 1 × 10 ¹² cmΩ or more, more preferably 1 × 10 ¹³ cmΩ or more, and particularly preferably 1 × 10 ¹⁴ cmΩ or more.

It is preferable to adjust the sensitivity of the charging indicator according to the purpose. Sensitivity can be adjusted by the distance between the grounded electrode and the other electrode. In order to realize good sensitivity, the distance between the electrodes is preferably 20 μm or less, more preferably 10 μm or less, and particularly preferably 5 μm or less. It is also effective to increase the absolute value of the dielectric anisotropy of the liquid crystal composition. Specifically, it is preferably adjusted to 2 or more, more preferably 5 or more, and still more preferably 8 or more.

In the case of adding a dye to the liquid crystal composition, a dichroic dye that is usually used can be suitably used. As the dichroic dye, an azo dye or an anthraquinone dye is preferable. This method is preferable because it is not necessary to use a polarizing plate, which will be described later, and the configuration of the apparatus becomes simple. As dichroic dyes, SI-486 (yellow), SI-426 (red), M-483 (blue), M-412 (blue), M-811 (blue), S-of Mitsui Chemicals Fine Co., Ltd. 428 (black), M-1012 (black), Mitsubishi Chemical Corporation LSY-116 (yellow), LSR-401 (magenta), LSR-406 (red), LSR-426 (purple), LSB-278 ( Blue), LSB-350 (blue), LSR-426 (cyan), and the like.

In the method of controlling transmission / scattering, a so-called polymer dispersed liquid crystal is preferably used. By using a liquid crystal composition to which a polymerizable compound is added so that the liquid crystal composition is dispersed in the polymer chain and curing the polymerizable compound, a polymer dispersed liquid crystal can be obtained.
(Base material)
As the substrate used for the static electricity indicator in the present invention, a substrate usually used for a liquid crystal device, a display, an optical component or an optical film can be suitably used. Examples of such a substrate include organic materials such as a glass substrate, a metal substrate, a ceramic substrate, and a plastic substrate. In particular, when the substrate is an organic material, examples thereof include cellulose derivatives, polyolefins, polyesters, polyolefins, polycarbonates, polyacrylates, polyarylates, polyether sulfones, polyimides, polyphenylene sulfides, polyphenylene ethers, nylons, and polystyrenes. Of these, plastic substrates such as polyester, polystyrene, polyolefin, cellulose derivatives, polyarylate, and polycarbonate are preferable. As a shape of a base material, you may have a curved surface other than a flat plate. These base materials may have an electrode layer, an antireflection function, and a reflection function as needed. It is preferable that at least the substrate present between the liquid crystal composition and the observer is transparent.

The substrate is preferably flexible. Being flexible, it can be made into a roll shape when carrying the static electricity indicator, and can be bent according to the shape of the object to observe static electricity or the shape of the installation location.
(electrode)
Even if an electrode is individual, 2 or more may be 1 set. When it is single, the electrode is preferably grounded. In the case of using a plurality of electrodes, it is preferable that at least one of them is grounded. When using a plurality of electrodes, there may be a plurality of electrodes that are not grounded to the counter electrode for one electrode that is grounded, and a ground to the counter electrode for one electrode that is not grounded There may be a plurality of electrodes.

The electrode may have an electrode that is grounded on one base material and an electrode that is not grounded on the other base material when the static electricity indicator has a shape in which two base materials sandwich the liquid crystal composition. There may be both an electrode that is grounded only on one substrate and an electrode that is not grounded. More preferably, there is an embodiment in which there is an electrode grounded on one base material and an electrode not grounded on the other base material.

In a more preferred embodiment, one electrode is connected (grounded) to a potential reference to function as an electrostatic indicator. Further, in order to measure the potential distribution, the electrode on the side not connected to the potential reference is arranged on the grid (two-dimensionally). Thus, the charging position of the object can be specified by arranging a plurality of electrodes on the static electricity indicator.

In the electrostatic indicator of the present invention, a conductive metal oxide can be used as a material for the transparent electrode, and examples of the metal oxide include indium oxide (In ₂ O ₃ ), tin oxide (SnO ₂ ), and zinc oxide ( ZnO), indium tin oxide (In ₂ O ₃ —SnO ₂ ), indium zinc oxide (In ₂ O ₃ —ZnO), niobium-doped titanium dioxide (Ti _1-x Nb _x O ₂ ), fluorine-doped tin oxide, graphene nanoribbon Alternatively, metal nanowires or the like can be used, but zinc oxide (ZnO), indium tin oxide (In ₂ O ₃ —SnO ₂ ), or indium zinc oxide (In ₂ O ₃ —ZnO) is preferable. For patterning these transparent conductive films, a photo-etching method or a method using a mask can be used. It is preferable that at least the electrode existing between the liquid crystal composition and the observer is transparent.
(Alignment of liquid crystal composition)
As the alignment state of the liquid crystal composition, when the potential difference between the grounded electrode and the ungrounded electrode is approximately 0 V, the liquid crystal composition may be approximately vertically aligned with respect to the substrate, or may be approximately horizontally aligned. good. When the p-type liquid crystal composition is used, it is preferably horizontally aligned. When using an n-type liquid crystal composition, it is preferable that it is vertically aligned.
(Orientation treatment)
In order to control the alignment of the liquid crystal composition, the substrate may be subjected to an alignment treatment or may be provided with an alignment film. Examples of the alignment treatment include stretching treatment, rubbing treatment, polarized ultraviolet (visible?) Light irradiation treatment, ion beam treatment, and oblique deposition of SiO ₂ on the substrate. When the alignment film is used, a known and conventional alignment film is used. Such alignment films include polyimide, polysiloxane, polyamide, polyvinyl alcohol, polycarbonate, polystyrene, polyphenylene ether, polyarylate, polyethylene terephthalate, polyether sulfone, epoxy resin, epoxy acrylate resin, acrylic resin, coumarin compound, chalcone. Examples of the compound include compounds, cinnamate compounds, fulgide compounds, anthraquinone compounds, azo compounds, and arylethene compounds. The compound subjected to the alignment treatment by rubbing is preferably an alignment treatment or a compound in which crystallization of the material is promoted by inserting a heating step after the alignment treatment. Among the compounds that perform alignment treatment other than rubbing, it is preferable to use a photo-alignment material.

The alignment film is generally formed by applying the alignment film material on a substrate by a method such as spin coating to form a resin film, but a uniaxial stretching method, Langmuir-Blodgett method, or the like can also be used. .

Further, as the alignment film material, a polymerized optical anisotropic body (positive A plate) in a state where the polymerizable liquid crystal composition is homogeneously aligned may be used.
(Polarizer)
As a method for visualizing the change in the alignment state of the liquid crystal composition, a polarizing plate can be used in addition to using the dichroic dye. Depending on the alignment state of the liquid crystal composition and the installation method of the polarizing plate, the deflecting plate can be installed so as to be normally white or normally black in a normal liquid crystal element. Any polarizing plate used for a normal liquid crystal display element can be preferably used.
(Color filter)
The electrostatic indicator of the present invention may have a color filter. The color filter includes a black matrix and at least an RGB three-color pixel portion. Any method may be used for forming the color filter layer. According to an example, a color filter layer is formed by applying a color coloring composition containing a pigment carrier and a color pigment dispersed therein to form a predetermined pattern, and curing this to obtain a colored pixel, and a color filter layer. Can be formed. As the pigment contained in the color coloring composition, an organic pigment and / or an inorganic pigment can be used. The color coloring composition may contain one kind of organic or inorganic pigment, and may contain a plurality of kinds of organic pigments and / or inorganic pigments. The pigment preferably has high color developability and high heat resistance, particularly high heat decomposition resistance, and an organic pigment is usually used.
(ground)
In the electrostatic indicator of the present invention, the higher the charged potential of the object, the higher the induced charged potential appearing on the electrode that is not grounded. As a result, the change in the alignment state of the liquid crystal composition increases, Can be visualized.

For example, in the case of an embodiment having a pair of electrodes as shown in FIGS. 1 and 2, when one electrode is grounded and the other electrode is not grounded, the grounded electrode and the non-grounded electrode are targeted. Due to the potential difference caused by electrostatic induction according to the charged position of the object, the orientation state of the liquid crystal composition existing between the two electrodes changes, thereby enabling visualization of the charge amount (in FIGS. 1 and 2). An example using a liquid crystal composition with positive dielectric anisotropy was shown)
Grounding may be performed at a place where a reference potential is desired. Examples of the grounding method include a method in which the electrode is directly connected to the reference potential portion, and a method in which the electrode is connected to the reference potential portion with a conductor such as a copper wire.

¡By arranging a plurality of one set of electrodes in a one-dimensional manner, the charged potential at the portion where the electrodes are arranged can be known.

The wiring for grounding the electrodes may be provided for each electrode, but all may be grounded as the same wiring as shown in FIG. Moreover, it is preferable that the induction charging electrodes are insulated from each other.

If a plurality of such linear charge indicators arranged in one dimension are installed in parallel as shown in FIG. 4, a two-dimensional charge distribution can be visualized.

Furthermore, when there are a plurality of sets of electrodes, it is preferable that there are insulating layers (insulating walls) between the electrodes as shown in FIG. The insulating wall is preferably formed so as to connect the two substrates and so as to surround the liquid crystal. By doing so, the insulating wall serves to keep the distance between the two substrates constant, and at the same time serves as a partition that prevents the liquid crystal from leaking outside.

If the substrate is a foldable plastic substrate and the insulating wall is also made of plastic, the indicator can be easily cut to any length with scissors or a cutter. In particular, if cutting is performed along an assumed cutting line indicated by a one-point difference line in FIG. 5, there is no risk of liquid crystal leaking to the outside, so cutting at this position is preferable.

Also, it is preferable to cut the strip-shaped static electricity indicator so that it can be cut at the insulating wall portion.

Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples. Further, “%” in the compositions of the following Examples and Comparative Examples means “% by mass”.

In the examples, the measured characteristics are as follows.

T _ni : Nematic phase-isotropic liquid phase transition temperature (° C.)
Δn: Refractive index anisotropy at 298K Δε: Dielectric anisotropy at 298K η: Viscosity at 293K (mPa · s)
γ ₁ : rotational viscosity at 298 K (mPa · s)
VHR: Voltage holding ratio (%) at 333 K under conditions of frequency 60 Hz and applied voltage 5 V
In the examples, the following abbreviations are used for the description of compounds.
(Ring structure)

(Side chain structure and linking structure)

(Reference Example 1)
The composition P1 shown in the table below was prepared.

The composition P1 had a T _ni of 81 ° C., Δn of 0.098, Δε of 2.4, γ ₁ of 35 mPa · s, VHR of 99.1%, and a specific resistance of 1 × 10 ¹³ Ωcm or more.
Reference Example 2 Preparation of Composition P2 Composition P2 shown in the table below was prepared.

_{T ni} of the composition P2 is 100 ° C., [Delta] n is 0.100, [Delta] [epsilon] is 8.1, gamma ₁ is 72 MPa · s, VHR is 99.1%, the specific resistance was 1 × 10 ¹³ Ωcm or more.
Reference Example 3 Preparation of Composition P3 Composition P3 shown in the table below was prepared.

_{T ni} of the composition P3 is 78 ° C., [Delta] n is 0.102, [Delta] [epsilon] is 2.3, gamma ₁ is 38 mPa · s, VHR is 99.2%, the specific resistance was 1 × 10 ¹³ Ωcm or more.
Reference Example 4 Preparation of Composition P4 Composition P4 shown in the table below was prepared.

In composition P4, T _ni was 73 ° C., Δn was 0.107, Δε was 11.7, γ ₁ was 78 mPa · s, VHR was 98.0%, and the specific resistance was 1 × 10 ¹³ Ωcm or more.
(Reference Example 5) Preparation of Composition P5 Composition P5 shown in the table below was prepared.

_{T ni} of the composition P4 is 87 ° C., [Delta] n is 0.117, [Delta] [epsilon] is 6.3, gamma ₁ is 54 MPa · s, VHR is 99.3%, the specific resistance was 1 × 10 ¹³ Ωcm or more.
(Reference Example 6) Preparation of Composition N1 Composition N1 shown in the table below was prepared.

Composition N1 had a T _ni of 76 ° C., Δn of 0.098, Δε of −3.7, γ ₁ of 89 mPa · s, VHR of 99.0%, and a specific resistance of 1 × 10 ¹³ Ωcm or more.
Reference Example 7 Preparation of Composition N2 Composition N2 shown in the table below was prepared.

Composition N2 had a T _ni of 91 ° C., Δn of 0.115, Δε of −4.0, γ ₁ of 121 mPa · s, VHR of 99.3%, and a specific resistance of 1 × 10 ¹³ Ωcm or more.
Reference Example 8 Preparation of Composition N3 Composition N3 shown in the table below was prepared.

Composition N3 had a T _ni of 76 ° C., Δn of 0.114, Δε of −4.4, γ ₁ of 117 mPa · s, VHR of 99.5%, and a specific resistance of 1 × 10 ¹³ Ωcm or more.
Reference Example 9 Preparation of Composition N4 Composition N4 shown in the table below was prepared.

Composition N4 had T _ni of 73 ° C., Δn of 0.112, Δε of −4.4, γ ₁ of 103 mPa · s, VHR of 99.4%, and a specific resistance of 1 × 10 ¹³ Ωcm or more.
(Reference Example 10) Preparation of Composition N5 Composition N5 shown in the table below was prepared.

_{T ni} is 76 ° C. of the composition N5, [Delta] n is 0.101, [Delta] [epsilon] is -2.8, gamma ₁ is 74mPa · s, VHR was 99.5%.
Reference Example 11 Measurement of physical properties of 4-cyano-4′-pentylbiphenyl (P6) Δn of 4-cyano-4′-pentylbiphenyl is 0.185, Δε is 11.0, γ ₁ is 46 mPa · s, VHR Was 52% and the specific resistance was 3 × 10 ⁹ Ωcm.
Reference Example 12 Preparation of Composition N3R Composition N3R was prepared by adding 1% by mass of dichroic dye SI-426 manufactured by Mitsui Chemicals Fine Co., Ltd. to composition N3 prepared in Reference Example 8.
Example 1
Prepared as a reference example in a TN (twisted nematic: twisted nematic) glass liquid crystal cell with a pair of transparent electrodes facing each other, a polyimide alignment film rubbed on the transparent electrodes, and a distance between the transparent electrodes of 3 μm The liquid crystal composition P1 thus prepared was injected. A polarizing plate was affixed on both sides of the liquid crystal cell so that the transmission axes were parallel to each other, to produce an electrostatic indicator. Next, a copper wire was connected from one transparent electrode and grounded. This static electricity indicator was in a state of not transmitting light (black) when there was no charged object nearby. A bandegraph static electricity generator (charging part) was installed 15 cm away from the transparent electrode on the non-grounded side of this static electricity indicator. When the bandegraph static electricity generator was activated and charged to about 2 kV, the static electricity indicator changed slightly from being transparent to transmitting. When the vandegraph static electricity generator was turned off, it remained transparent for more than 3 minutes.

Next, a bandegraph static electricity generator (charging part) was installed 10 cm away from the transparent electrode on the non-grounded side of the static electricity indicator. When the bandegraph static electricity generator was activated and charged to about 2 kV, the static electricity indicator changed from not transmitting light to transmitting. When the vandegraph static electricity generator was turned off, it remained transparent for more than 3 minutes.
(Examples 2 to 6)
The same experiment as in Example 1 was performed by changing the liquid crystal composition. The electrostatic indicator was evaluated as Δ when the light was slightly transmitted, ○ when the light was transmitted, and ◎ when it was clearly transmitted.

From the results in the table below, it can be seen that the greater the dielectric anisotropy of the liquid crystal material, the higher the sensitivity to static electricity. In addition, it can be seen that the higher the voltage holding ratio and specific resistance of the liquid crystal material, there is a property indicating that there was static electricity for a certain period even when there were no charged objects around. It can be seen that when a cyano liquid crystal material having a low voltage holding ratio and specific resistance is used as the liquid crystal, the state quickly changes from the light transmitting state to the non-transmitting state when there is no charged object around.

(Example 7)
Prepared as a reference example in a VA (vertical alignment) glass liquid crystal cell having a pair of transparent electrodes facing each other, a polyimide alignment film rubbed on the transparent electrode, and a distance between the transparent electrodes of 3 μm. The liquid crystal composition N1 was injected. Polarizers were attached to both sides of the liquid crystal cell so that the transmission axes were perpendicular to each other, thereby producing an electrostatic indicator. Next, a copper wire was connected from one transparent electrode and grounded. This static electricity indicator was in a state of not transmitting light (black) when there was no charged object nearby. A bandegraph static electricity generator (charging part) was installed 15 cm away from the transparent electrode on the non-grounded side of this static electricity indicator. When the bandegraph static electricity generator was activated and charged to about 2 kV, the static electricity indicator changed slightly from being transparent to transmitting. When the vandegraph static electricity generator was turned off, it remained transparent for more than 3 minutes.

Next, a bandegraph static electricity generator (charging part) was installed 10 cm away from the transparent electrode on the non-grounded side of the static electricity indicator. When the bandegraph static electricity generator was activated and charged to about 2 kV, the static electricity indicator changed from not transmitting light to transmitting. When the vandegraph static electricity generator was turned off, it remained transparent for more than 3 minutes.
(Examples 8 to 11)
The same experiment as in Example 7 was performed by changing the liquid crystal composition. The electrostatic indicator was evaluated as Δ when the light was slightly transmitted, ○ when the light was transmitted, and ◎ when it was clearly transmitted.

From the results in the table below, it can be seen that the greater the absolute value of the dielectric anisotropy of the liquid crystal material, the higher the sensitivity to static electricity.

(Example 12)
A liquid crystal prepared in a reference example in a VA (Vertical Alignment: Vertical Alignment) liquid crystal cell having a pair of opposing transparent electrodes, a rubbed polyimide alignment film formed on the transparent electrodes, and a distance between the transparent electrodes of 3 μm Composition N3R was injected to produce an electrostatic indicator. A copper wire was connected from one transparent electrode and grounded. This electrostatic indicator was in a state of transmitting light (transparent) when there was no charged object nearby. A bandegraph static electricity generator (charging part) was installed 15 cm away from the transparent electrode on the non-grounded side of this static electricity indicator. When the bandegraph static electricity generator was activated and charged to about 2 kV, the static electricity indicator changed slightly from transparent to red. When the vandegraph static electricity generator was turned off, the red state was maintained for more than 2 minutes.

Next, a bandegraph static electricity generator (charging part) was installed 10 cm away from the transparent electrode on the non-grounded side of the static electricity indicator. When the bandegraph static electricity generator was activated and charged to about 2 kV, the static electricity indicator changed from transparent to red. When the vandegraph static electricity generator was turned off, the red state was maintained for more than 2 minutes.
(Example 13)
Prepare a PET film substrate with a thickness of 3 cm and a length of 7 cm with a solid ITO transparent electrode and a thickness of 50 μm, and a PET film substrate with a thickness of 3 cm and a length of 7 cm with a patterned ITO transparent electrode as shown in FIG. A polyimide vertical alignment film was formed on the transparent electrode substrate. As shown in FIG. 6, 0.8 mg of the composition N3R was dropped at 3 locations, and 3.1 mg of Three Bond UV curable adhesive 3052B was dropped at 8 locations. In this state, the PET film with a solid electrode was bonded so that the electrode surfaces face each other, and pressure was applied to the entire surface. At this time, as shown in FIG. 7, the film was shifted by 2 mm on the short side of the film and bonded without shifting on the long side of the film. The distance between the two film substrates was set to 10 μm. In this state, the ultraviolet curable adhesive was cured by irradiating ultraviolet light at 365 nm with 300 mJ / cm 2. In this way, a strip-shaped electrostatic indicator having an appearance as shown in FIG. 8 was produced. A copper wire was connected to the solid electrode side and grounded. A bandegraph static electricity generator (charging part) was installed 15 cm away from the static electricity indicator. When the bandegraph static electricity generator was not operated, all three liquid crystal parts were transparent. When the bandegraph static electricity generator was activated and charged to about 2 kV, the liquid crystal part with three static electricity indicators changed to a deeper red color near the charging part. The charge distribution could be visualized. When the vandegraph static electricity generator was turned off, it remained red for about 1 minute.

11 Substrate (charged material side)
12 Substrate (ground side)
13, 14

Electrodes

13A, 13B, 13C Electrodes 15 that are not electrically connected to each other 15 Liquid crystal composition (liquid crystal molecules)
16 Grounding (reference potential)
17 Charged material 20 A set of static electricity indicator 25 Liquid crystal composition dripping portion 26 Adhesive dripping portion 27 Liquid crystal composition region 28 Insulating wall with adhesive cured (made of resin)
31 Insulating

wall

33, 34, 35 Electrode 36, 37 Expected cutting line

Claims

Electrostatic indicator using liquid crystal composition.
The electrostatic indicator according to claim 1, wherein a liquid crystal composition is sandwiched between two opposing electrodes.
The electrostatic indicator according to claim 1, wherein the liquid crystal composition is sandwiched between two substrates having electrodes.
4. The static electricity indicator according to claim 2, wherein at least one electrode is grounded.
The electrostatic indicator according to claim 3 or 4, wherein at least one of the substrates has two or more electrodes that are not electrically connected to each other.
The electrostatic indicator according to any one of claims 3 to 5, wherein one or more electrodes on one substrate are equipotential.
The electrostatic indicator according to any one of claims 1 to 6, wherein the liquid crystal composition contains a dichroic dye.
The electrostatic indicator according to any one of claims 1 to 6, wherein a cured product of a polymerizable compound is used.