JP2017084164A - Insulation film for fingerprint authentication device, laminate, and fingerprint authentication device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an insulation film for a fingerprint authentication device made of a material which has a high dielectric constant and can be inexpensively supplied in large quantities.SOLUTION: The insulation film for the fingerprint authentication device is for covering the surface of a substrate on a side on which an electrode is provided of the surface of the substrate constituting the fingerprint authentication device. The insulation film for the fingerprint authentication device includes a cellulose fiber.SELECTED DRAWING: None

Description

  The present invention relates to an insulating film for a fingerprint authentication device including a cellulose fiber, a laminate, and a fingerprint authentication device.

  In recent years, materials using reproducible natural fibers have attracted attention due to the substitution of petroleum resources and the growing environmental awareness. Among natural fibers, cellulose fibers having a fiber diameter of 10 to 50 μm, especially wood-derived cellulose fibers (pulp) have been widely used as paper products so far. As the cellulose fiber, fine fibrous cellulose having a fiber diameter of 1 μm or less is also known. Sheets and composites containing fine fibrous cellulose significantly increase the tensile strength because the contact points between fibers are remarkably increased. Moreover, transparency is greatly improved because the fiber width is shorter than the wavelength of visible light.

  As an insulating material using fine fibrous cellulose, Patent Document 1 includes a fiber assembly mainly composed of cellulose nanofibers, and a conductive metal material supported on the fiber assembly. Insulating materials are described.

  On the other hand, for example, a fingerprint authentication device has recently attracted attention as a personal authentication device for permitting access to an information device only for a specific individual. As an example of a fingerprint authentication device, a capacitive fingerprint authentication device that collects a fingerprint by sensing the capacitance between an electrode in the device and a finger is known. For example, Patent Document 2 discloses a fingerprint sensor device that collects a fingerprint by sensing electrostatic capacitance with a finger, wherein the surface of the protective film of the sensor unit is flattened. Is described. In the fingerprint sensor device described in Patent Document 2, an interlayer insulating film is provided on a Si substrate, a detection electrode is provided thereon, and a protective film is provided so as to cover the detection electrode.

Japanese Patent Laid-Open No. 2015-18696 JP 2000-194825 A

  In a protective film for use in the above-described fingerprint authentication device, a high dielectric constant is required in order to achieve a sufficient capacitance. For example, sapphire glass is known as a material for the protective film, but it is more desirable if the protective film can be made of a material that can be supplied in a large amount at a lower cost. For example, various plastics or glass can be considered as an alternative material for sapphire glass, but all of them have a low dielectric constant, and are not satisfactory as a material for a protective film of a fingerprint authentication device.

  An object of the present invention is to provide an insulating film for a fingerprint authentication device that has a high dielectric constant and is made of a material that can be supplied in large quantities at low cost. Furthermore, this invention makes it the subject which should be solved to provide the laminated body containing said insulating film for fingerprint authentication apparatuses, and the fingerprint authentication apparatus containing said insulating film for fingerprint authentication apparatuses.

  As a result of intensive studies to solve the above problems, the present inventors have found that a film containing cellulose fibers has a high dielectric property and has excellent properties as an insulating film for a fingerprint authentication device. It came to be completed.

That is, according to the present invention, the following inventions are provided.
(1) An insulating film for a fingerprint authentication device for covering a surface of a substrate on which an electrode is provided among the surfaces of a substrate constituting the fingerprint authentication device, the insulating film for a fingerprint authentication device including cellulose fibers .
(2) The insulating film for a fingerprint authentication device according to (1), wherein an average fiber width of the cellulose fibers is 1000 nm or less, and an aspect ratio of the cellulose fibers is 30 or more.
(3) The insulating film for a fingerprint authentication device according to (1) or (2), wherein the insulating film has a thickness of 100 μm or less.
(4) The insulating film for a fingerprint authentication device according to any one of (1) to (3), wherein a relative dielectric constant of the insulating film is 6 or more.
(5) The insulating film for a fingerprint authentication device according to any one of (1) to (4), wherein the insulating film has a capacitance of 400 pF or more.
(6) The insulating film for a fingerprint authentication device according to any one of (1) to (5), wherein a tensile elastic modulus of the insulating film is 7.0 GPa or more.
(7) The insulating film for a fingerprint authentication device according to any one of (1) to (6), wherein a linear thermal expansion coefficient of the insulating film is 30 ppm / ° C. or less.
(8) The insulating film for a fingerprint authentication device according to any one of (1) to (7), wherein the total light transmittance of the insulating film is 85% or more.
(9) The insulating film for a fingerprint authentication device according to any one of (1) to (8), wherein the haze of the insulating film is 5% or less.
(10) A laminate comprising the fingerprint authentication device insulating film according to any one of (1) to (9) and an inorganic layer laminated on at least one surface of the fingerprint authentication device insulating film.
(11) A laminate including the fingerprint authentication device insulating film according to any one of (1) to (9) and a resin layer laminated on at least one surface of the fingerprint authentication device insulating film.
(12) (a) Support substrate;
(B) A sensor circuit board provided with an electrode on one surface; and (c) any one of (1) to (9) provided to cover the electrode on the one surface of the sensor circuit board. Insulating film for fingerprint authentication device or laminate according to (10) or (11):
In this order.

  The insulating film for a fingerprint authentication device of the present invention is made of a material that can be supplied in a large amount at a low cost and has a high dielectric constant.

FIG. 1 shows three regions in the substituent content measurement by the conductivity titration method. FIG. 2 shows an example of a fingerprint authentication device and its principle. FIG. 3 shows another example of the fingerprint authentication device and its principle. FIG. 4 shows still another example of the fingerprint authentication device and its principle.

[Insulating film for fingerprint authentication device]
An insulating film for a fingerprint authentication device according to the present invention is an insulating film for a fingerprint authentication device for covering the surface of a substrate on the side on which an electrode is provided among the surfaces of a substrate constituting the fingerprint authentication device. This is an insulating film for a fingerprint authentication device.
The insulating film in this specification is a film having insulating properties, and means, for example, a film having a function of electrically insulating metal wiring that conducts electricity from other members.

<Cellulose fiber>
The cellulose fiber in this invention can be obtained by processing a cellulose raw material (for example, chemical treatment, fibrillation treatment, etc.).
Examples of the cellulose raw material include paper pulp, cotton pulp such as cotton linter and cotton lint, non-wood pulp such as hemp, straw, and pagas, cellulose isolated from sea squirts and seaweed, etc., but are not particularly limited. . Among these, paper pulp is preferable in terms of availability, but is not particularly limited. Examples of the pulp for papermaking include, but are not limited to, non-wood pulp made from chemical pulp, semi-chemical pulp, mechanical pulp, cocoon, cocoon, hemp, kenaf and the like, and deinked pulp made from waste paper. Examples of the chemical pulp include hardwood kraft pulp, softwood kraft pulp, sulfite pulp (SP), dissolved pulp (DP), and soda pulp (AP). Examples of hardwood kraft pulp include bleached kraft pulp (LBKP), unbleached kraft pulp (LUKP), and oxygen bleached kraft pulp (LOKP). Examples of softwood kraft pulp include bleached kraft pulp (NBKP), unbleached kraft pulp (NUKP), and oxygen bleached kraft pulp (NOKP). Semi-chemical pulp includes semi-chemical pulp (SCP), chemiground wood pulp (CGP), and the like. Examples of the mechanical pulp include groundwood pulp (GP) and thermomechanical pulp (TMP, BCTMP). Among these, kraft pulp, deinked pulp, and sulfite pulp are preferable because they are more easily available, but are not particularly limited. A cellulose raw material may be used individually by 1 type, and may be used in mixture of 2 or more types.

  The number average fiber width of the cellulose fibers is generally 2 nm or more and 100 μm or less, but is not particularly limited. The number average fiber width of the cellulose fibers is preferably 2 nm or more and less than 1000 nm, more preferably 2 nm or more and 500 nm or less, 2 nm or more and 100 nm or less, and further preferably 2 nm or more and 50 nm or less. The number average fiber width of the cellulose fibers is more preferably 2 nm or more and 20 nm or less, and particularly preferably 2 nm or more and 10 nm or less. Cellulose fibers having a number average fiber width of less than 1000 nm are also referred to as fine fibrous cellulose.

  A cellulose fiber is an aggregate of cellulose molecules including a crystal part, and its crystal structure is type I (parallel chain). The number average fiber width of the cellulose fibers can be measured by observing with an electron microscope. When the average fiber width of the cellulose fibers is less than 2 nm, the physical properties (strength, rigidity, dimensional stability) as the fine fibrous cellulose are not expressed because the cellulose molecules are dissolved in water. Here, the fact that the fine fibrous cellulose has the I-type crystal structure is typical in two positions in the diffraction profile, ie, 2θ = 14 ° to 17 ° and 2θ = 22 ° to 23 °. It can be identified from having a strong peak. The above-mentioned diffraction profile is a diffraction profile obtained from a wide-angle X-ray diffraction photograph using CuKα (λ = 1.5418Å) monochromatized with graphite.

  Measurement of the average fiber width of the cellulose fibers by electron microscope observation is performed as follows. An aqueous suspension of cellulose fibers having a concentration of 0.05% by mass or more and 0.1% by mass or less is prepared, and the suspension is cast on a carbon film-coated grid subjected to a hydrophilic treatment to obtain a sample for TEM observation. When a wide fiber is included, an SEM image of the surface cast on glass may be observed. Observation with an electron microscope image is performed at a magnification of 1000 times, 5000 times, 10000 times, or 50000 times depending on the width of the constituent fibers. However, the sample, observation conditions, and magnification are adjusted to satisfy the following conditions.

(1) One straight line X is drawn at an arbitrary location in the observation image, and 20 or more fibers intersect the straight line X.
(2) A straight line Y perpendicular to the straight line is drawn in the same image, and 20 or more fibers intersect the straight line Y.

  The width of the fiber that intersects with the straight line X and the straight line Y is visually read from the observation image that satisfies the above conditions. In this way, at least three sets of images of the surface portion that do not overlap each other are observed, and the width of the fiber intersecting with the straight line X and the straight line Y is read for each image. Thus, at least 20 × 2 × 3 = 120 fiber widths are read. The average fiber width of the cellulose fibers is the average value of the fiber widths read in this way.

  Although the fiber length of a cellulose fiber is not specifically limited, 0.1 micrometer or more is preferable, 1 micrometer or more and 1000 micrometers or less are more preferable, 5 micrometers or more and 800 micrometers or less are more preferable, and 10 micrometers or more and 600 micrometers or less are especially preferable. When the fiber length is less than 0.1 μm, it is difficult to form a film (sheet). If it exceeds 1000 μm, the slurry viscosity of the cellulose fiber becomes very high, making it difficult to handle. The fiber length can be obtained by image analysis using TEM, SEM, or AFM.

  The aspect ratio (axial ratio) (fiber length / fiber width) of the fiber is not particularly limited, but is preferably in the range of 20 or more and 10,000 or less, preferably in the range of 30 or more and 10,000 or less, and 50 or more and 10,000 or less. A range is more preferable. An aspect ratio of 20 or more is preferable in that a film can be easily formed during production. When the aspect ratio is 10,000 or less, it is preferable in that the slurry viscosity during the production of the film is lowered.

  The cellulose fiber may have an ionic substituent, but is not particularly limited. The ionic substituent facilitates the refinement (defibration) of the cellulose fiber when the cellulose fiber is made into a sheet to produce an insulating film. The ionic substituent may be either anionic or cationic.

Examples of the anionic substituent include a phosphate group or a substituent derived from a phosphate group (hereinafter, a phosphate group and a substituent derived from a phosphate group are also referred to as a phosphate-derived group), a carboxy group, or Substituents derived from carboxy groups (hereinafter, carboxy groups and substituents derived from carboxy groups are also referred to as carboxylic acid-derived groups), sulfate groups or substituent groups derived from sulfate groups (hereinafter referred to as sulfate groups and sulfate groups). The substituent derived from the above is also referred to as a group derived from sulfuric acid), a sulfonic acid group or a substituent derived from a sulfonic acid group (hereinafter, the substituent derived from a sulfonic acid group and a sulfonic acid group is referred to as a group derived from a sulfonic acid Also called). The phosphoric acid group is a divalent functional group equivalent to the phosphoric acid obtained by removing the hydroxyl group. Specifically, it is a group represented by —PO ₃ H ₂ . The substituent derived from the phosphate group includes a substituent such as a group obtained by polycondensation of a phosphate group, a salt of a phosphate group, and a phosphate ester group. Moreover, the substituent derived from a phosphoric acid group or a phosphoric acid group may be represented by the following formula (1).

In formula (1), a, b, m and n each independently represent an integer (where a = b × m); α ⁿ (n = 1 to n) and α ′ are each independently R or OR is represented. R represents a hydrogen atom, a saturated-linear hydrocarbon group, a saturated-branched hydrocarbon group, a saturated-cyclic hydrocarbon group, an unsaturated-linear hydrocarbon group, an unsaturated-branched hydrocarbon group. , An aromatic group, or a derivative group thereof; β is a monovalent or higher cation composed of an organic substance or an inorganic substance.

  The anionic substituent is at least one selected from the group consisting of a group derived from phosphoric acid, a group derived from carboxylic acid, and a group derived from sulfuric acid, from the viewpoint of ease of handling and reactivity with fibers during production. It is preferable. These groups preferably form an ester or ether with the fiber, but are not particularly limited.

  Examples of the cationic substituent include groups derived from onium salts such as ammonium salts, phosphonium salts, and sulfonium salts. Specific examples include groups containing ammonium, phosphonium and sulfonium such as primary ammonium salt, secondary ammonium salt, tertiary ammonium salt and quaternary ammonium salt. The cationic substituent is preferably at least one of a group derived from a quaternary ammonium salt and a group derived from a phosphonium salt in view of ease of handling and reactivity with fibers during production.

[Method of manufacturing insulating film for fingerprint authentication device]
The insulating film for a fingerprint authentication device of the present invention can be manufactured by a step of preparing a sheet from cellulose fibers.
Moreover, when using a fine fibrous cellulose as a cellulose fiber, you may perform the process of introduce | transducing an ionic substituent into a cellulose fiber raw material and obtaining an ionic substituent introduction | transduction cellulose fiber. Then, the process of preparing a sheet | seat may be performed after performing the process of refinement | miniaturizing an ionic substituent introduction | transduction cellulose fiber and obtaining the ionic substituent introduction | transduction fine fibrous cellulose. Each of the above steps will be described below.

<Step of obtaining ionic substituent-introduced cellulose fiber by introducing ionic substituent into cellulose fiber raw material>
A method for introducing an ionic substituent to the cellulose fiber is not particularly limited, and examples thereof include an oxidation treatment and a treatment with a compound capable of forming a covalent bond with a functional group in the cellulose fiber. The oxidation treatment is a treatment for converting a hydroxy group in cellulose fiber into an aldehyde group or a carboxy group, and examples thereof include a TEMPO oxidation treatment and treatment using various oxidizing agents (sodium chlorite, ozone, etc.).

  An example of the oxidation treatment is a method described in Biomacromolecules 8, 2485-2491, 2007 (Saito et al.), But is not particularly limited.

  The treatment with the compound capable of forming a covalent bond with the functional group in the cellulose fiber is performed by mixing the cellulose fiber raw material with a compound that reacts with the cellulose fiber raw material in the dry or wet fiber raw material. Can be implemented. In order to promote the reaction at the time of introduction, a heating method is particularly effective. The heat treatment temperature for introducing the substituent is not particularly limited, but it is preferably a temperature range in which thermal decomposition or hydrolysis of the fiber raw material hardly occurs. For example, the temperature is preferably 250 ° C. or lower from the viewpoint of the thermal decomposition temperature of the fiber, and is preferably heat-treated at 100 ° C. or higher and 170 ° C. or lower from the viewpoint of suppressing the hydrolysis of the fiber.

The compound that reacts with the cellulose fiber raw material is not particularly limited as long as it introduces an ionic substituent.
When a compound having a phosphoric acid-derived group is used as a compound that reacts with the cellulose fiber raw material, it is not particularly limited, but is composed of phosphoric acid, polyphosphoric acid, phosphorous acid, phosphonic acid, polyphosphonic acid, or a salt or ester thereof. It is at least one selected from the group. Among these, a compound having a phosphate-derived group is preferable because it is low-cost, easy to handle, and can further improve the refinement (defibration) efficiency by introducing a phosphate-derived group into the cellulose fiber raw material. However, it is not particularly limited.

  The compound having a phosphoric acid-derived group is not particularly limited, but phosphoric acid, lithium dihydrogen phosphate, dilithium hydrogen phosphate, trilithium hydrogen phosphate, trilithium phosphate, lithium pyrophosphate, lithium polyphosphate Can be mentioned. Furthermore, sodium dihydrogen phosphate, disodium hydrogen phosphate, trisodium phosphate, sodium pyrophosphate and sodium polyphosphate which are sodium salts of phosphoric acid are mentioned. Furthermore, potassium dihydrogen phosphate, dipotassium hydrogen phosphate, tripotassium phosphate, potassium pyrophosphate, and potassium polyphosphate which are potassium salts of phosphoric acid are mentioned. Further examples include ammonium dihydrogen phosphate, diammonium hydrogen phosphate, triammonium phosphate, ammonium pyrophosphate, and ammonium polyphosphate, which are ammonium salts of phosphoric acid.

  Of these, phosphoric acid, phosphoric acid sodium salt, phosphoric acid potassium salt, and phosphoric acid ammonium salt are preferred from the viewpoint of high efficiency of introduction of phosphoric acid-derived groups and easy industrial application. It is not limited. Among these, sodium dihydrogen phosphate and disodium hydrogen phosphate are more preferable, but not particularly limited.

  In addition, the compound is preferably used as an aqueous solution because of the uniformity of the reaction and the introduction efficiency of the group derived from phosphoric acid, but it is not particularly limited. The pH of the aqueous solution of the compound is not particularly limited, but is preferably 7 or less because of the high efficiency of introducing a phosphoric acid-derived group. From the viewpoint of suppressing the hydrolysis of the fiber, pH 3 or more and pH 7 or less are more preferable, but not particularly limited.

  The compound having a phosphate-derived group reacts with the fiber raw material together with one or more selected from urea, thiourea, biuret, phenylurea, benzylurea, dimethylurea, diethylurea, tetramethylurea, benzoleinurea, or hydantoin. You may let them. However, the present invention is not limited to this.

  When a compound having a carboxylic acid-derived group is used as the compound that reacts with the fiber raw material, the compound having a carboxylic acid-derived group, an acid anhydride of the compound having a carboxylic acid-derived group, and the like are not particularly limited. And at least one selected from the derivatives of

  The compound having a carboxylic acid-derived group is not particularly limited, but a dicarboxylic acid compound such as maleic acid, succinic acid, phthalic acid, fumaric acid, glutaric acid, adipic acid or itaconic acid, or a tricarboxylic acid compound such as citric acid or aconitic acid. Is mentioned.

  The acid anhydride of the compound having a carboxylic acid-derived group is not particularly limited, but acid anhydrides of dicarboxylic acid compounds such as maleic anhydride, succinic anhydride, phthalic anhydride, glutaric anhydride, adipic anhydride, itaconic anhydride, etc. Things.

  The derivative of the compound having a carboxylic acid-derived group is not particularly limited, and examples thereof include an acid anhydride imidized compound having a carboxylic acid-derived group and an acid anhydride derivative of a compound having a carboxylic acid-derived group. . The acid anhydride imidized compound having a carboxylic acid-derived group is not particularly limited, and examples thereof include imidized dicarboxylic acid compounds such as maleimide, succinimide, and phthalimide.

  The acid anhydride derivative of the compound having a carboxylic acid-derived group is not particularly limited. For example, at least some of the hydrogen atoms of the acid anhydride of the compound having a carboxylic acid-derived group, such as dimethylmaleic acid anhydride, diethylmaleic acid anhydride, diphenylmaleic acid anhydride, are substituted (for example, alkyl group, And those substituted with a phenyl group or the like.

  Among the compounds having a group derived from a carboxylic acid, maleic anhydride, succinic anhydride, and phthalic anhydride are preferred because they are easily applied industrially and easily gasified, but are not particularly limited.

  When a compound having a group derived from sulfuric acid is used as the compound that reacts with the cellulose fiber raw material, it is not particularly limited, but it is at least one selected from the group consisting of sulfuric anhydride, sulfuric acid and salts and esters thereof. Among these, sulfuric acid is preferable, but is not particularly limited because it is low cost and can improve the refinement (defibration) efficiency by introducing a sulfate group into the cellulose fiber raw material.

  The amount of the ionic substituent introduced when the ionic substituent is introduced is not particularly limited, but can be determined in consideration of the amount of the substituent introduced as a sheet. In the case of an anionic substituent, the amount of substituent introduced (by titration method) is preferably 0.005α to 0.11α, more preferably 0.01α to 0.08α per 1 g (mass) of fiber. If the introduction amount of the substituent is 0.005α or more, the fiber raw material can be easily refined (defibration). If the introduction amount of the substituent is 0.11α or less, dissolution of the fiber can be suppressed. However, (alpha) is the quantity (unit: mmol / g) by which the functional group which the compound which reacts with a fiber material can react, for example, a hydroxyl group and an amino group, is contained per 1 g of fiber materials.

The amount of ionic substituent introduced can be measured by a conductivity titration method. Specifically, after the cellulose fiber-containing slurry is treated with an ion exchange resin, the amount introduced can be measured by determining the change in electrical conductivity while adding an aqueous sodium hydroxide solution.
In conductivity titration, when alkali is added, the curve shown in FIG. 1 is given. Initially, the electrical conductivity rapidly decreases (hereinafter referred to as “first region”). Thereafter, the conductivity starts to increase slightly (hereinafter referred to as “second region”). Thereafter, the conductivity increment increases (hereinafter referred to as “third region”). That is, three areas appear. Among these, the amount of alkali required in the first region is equal to the amount of strongly acidic groups in the slurry used for titration, and the amount of alkali required in the second region is the amount of weakly acidic groups in the slurry used for titration. Will be equal. When the phosphoric acid group undergoes condensation, apparently weakly acidic groups are lost, and the amount of alkali required in the second region is reduced compared to the amount of alkali required in the first region. On the other hand, the amount of strongly acidic groups coincides with the amount of phosphorus atoms regardless of the presence or absence of condensation, so that the amount of phosphate groups introduced (or the amount of phosphate groups) or the amount of substituent introduced (or the amount of substituents) is simply When said, it represents the amount of strongly acidic group. That is, the alkali amount (mmol) required in the first region of the curve shown in FIG. 1 is divided by the solid content (g) in the titration target slurry to obtain the substituent introduction amount (mmol / g).

  When the introduced substituent is at least one selected from the group consisting of a phosphoric acid-derived group, a carboxylic acid-derived group and a sulfuric acid-derived group, the amount of substituent introduction is not particularly limited, but 0 It can be set to 0.001 mmol / g or more and 5.0 mmol / g or less. It may be 0.05 mmol / g or more and 4.0 mmol / g or less, and may be 0.1 mmol / g or more and 2.0 mmol / g or less.

  The cationic substituent can be introduced into the fiber raw material, for example, by adding a cationizing agent and an alkali compound to the cellulose fiber raw material and reacting them. As the cationizing agent, one having a quaternary ammonium group and a group that reacts with a hydroxy group of cellulose can be used. Examples of the group that reacts with the hydroxy group of cellulose include an epoxy group, a functional group having a halohydrin structure, a vinyl group, and a halogen group.

  Specific examples of the cationizing agent include glycidyltrialkylammonium halides such as glycidyltrimethylammonium chloride and 3-chloro-2-hydroxypropyltrimethylammonium chloride or halohydrin type compounds thereof.

  The alkali compound used in the cationization step contributes to the promotion of the cationization reaction. The alkali compound may be an inorganic alkali compound or an organic alkali compound.

Examples of inorganic alkali compounds include alkali metal hydroxides or alkaline earth metal hydroxides, alkali metal carbonates or alkaline earth metal carbonates, alkali metal phosphates or alkaline earth metal phosphoric acids. Salt.
Examples of the alkali metal hydroxide include lithium hydroxide, sodium hydroxide, and potassium hydroxide. Examples of the alkaline earth metal hydroxide include calcium hydroxide.
Examples of the alkali metal carbonate include lithium carbonate, lithium hydrogen carbonate, potassium carbonate, potassium hydrogen carbonate, sodium carbonate, and sodium hydrogen carbonate. Examples of the alkaline earth metal carbonate include calcium carbonate.
Examples of the alkali metal phosphate include lithium phosphate, potassium phosphate, trisodium phosphate, and disodium hydrogen phosphate. Examples of alkaline earth metal phosphates include calcium phosphate and calcium hydrogen phosphate.

Examples of the organic alkali compounds include ammonia, aliphatic amines, aromatic amines, aliphatic ammoniums, aromatic ammoniums, heterocyclic compounds and their hydroxides, carbonates, and phosphates. For example, ammonia, hydrazine, methylamine, ethylamine, diethylamine, triethylamine, propylamine, dipropylamine, butylamine, diaminoethane, diaminopropane, diaminobutane, diaminopentane, diaminohexane, cyclohexylamine, aniline, tetramethylammonium hydroxide, Tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, benzyltrimethylammonium hydroxide, pyridine, N, N-dimethyl-4-aminopyridine, ammonium carbonate, ammonium hydrogen carbonate, diammonium hydrogen phosphate, etc. Can be mentioned.
The said alkali compound may be single 1 type, and may combine 2 or more types.

  Among the above alkali compounds, sodium hydroxide and potassium hydroxide are preferable because the cationization reaction is more likely to occur and the cost is low. The amount of the alkali compound varies depending on the type of the alkali compound, and is, for example, in the range of 1% by mass or more and 10% by mass or less with respect to the pulp dry mass.

  Since the cationizing agent and the alkali compound can be easily added to the pulp, it is preferable to form a solution. The solvent used for the solution may be either water or an organic solvent, but a polar solvent (polar organic solvent such as water or alcohol) is preferable, and an aqueous solvent containing at least water is more preferable.

  In the present invention, it is preferable that the amount of solvent substance per 1 g of the pulp dry mass at the start of the cationization reaction is 5 mmol or more and 150 mmol or less. The substance amount of the solvent is more preferably 5 mmol or more and 80 mmol or less, and further preferably 5 mmol or more and 60 mmol or less. In order to bring the pulp content during the cationization reaction into the above range, for example, a pulp having a high content (that is, having a low water content) may be used. Moreover, it is preferable to reduce the amount of solvent contained in the solution of the cationizing agent and the alkali compound.

  The reaction temperature in the cationization step is preferably in the range of 20 ° C. or higher and 200 ° C. or lower, and more preferably in the range of 40 ° C. or higher and 100 ° C. or lower. If the reaction temperature is not less than the lower limit, sufficient reactivity can be obtained, and if the reaction temperature is not more than the upper limit, the reaction can be easily controlled. In addition, there is an effect of suppressing coloring of the pulp after the reaction. The time of the cationization reaction varies depending on the type of pulp and cationizing agent, pulp content, reaction temperature, and the like, but is usually in the range of 0.5 hours to 3 hours.

  The cationization reaction may be performed in a closed system or an open system. Further, the solvent may be evaporated during the reaction, and the amount of the solvent substance per 1 g of the pulp dry mass at the end of the reaction may be lower than that at the start of the reaction.

<Acid treatment or alkali treatment>
If necessary, an acid treatment or an alkali treatment can be performed after the step of obtaining the ionic substituent-introduced fiber. The acid treatment can be performed using, for example, one or more selected from the group consisting of hydrochloric acid, nitric acid and sulfuric acid. The alkali treatment can be performed using, for example, one or more selected from the group consisting of sodium hydroxide, potassium hydroxide, barium hydroxide, and calcium hydroxide.

  The acid treatment or alkali treatment method can be carried out, for example, by immersing the ionic substituent-introduced cellulose fiber in an acid solution or an alkali solution. As the solvent in the acid solution or the alkali solution, at least one of water and an organic solvent can be used. A polar one (polar organic solvent such as water or alcohol) is preferable, and an aqueous solvent containing water is more preferable. A particularly preferred example of the acid solution is hydrochloric acid, and a particularly preferred example of the alkaline solution is an aqueous sodium hydroxide solution or an aqueous potassium hydroxide solution.

  In the case of acid treatment, the pH of the acid solution at 25 ° C. can be appropriately determined, but is preferably 4 or less, more preferably 3.5 or less, and even more preferably 3 or less. In the case of the alkali treatment, the pH of the base solution at 25 ° C. can be appropriately determined, but is preferably 9 or more, more preferably 10 or more, and further preferably 11 or more.

  In order to reduce the amount of acid or alkali used, cellulose fibers having an ionic substituent may be washed before the acid treatment or alkali treatment step. For washing, at least one of water and an organic solvent can be used. In addition, after the acid treatment or the alkali treatment, the treated cellulose fiber having an ionic substituent may be washed with at least one of water and an organic solvent. In either case, the washing operation can be repeated.

<Step of obtaining ionic substituent-introduced fine fibrous cellulose by refining ionic substituent-introducing cellulose fiber>
The cellulose fiber raw material may be refined by subjecting to a defibrating treatment, and fine fibrous cellulose having a number average fiber width of 2 nm or more and less than 1000 nm can be obtained by the refinement treatment. In the defibrating process, the fine fiber dispersion can be obtained by defibrating the raw material using a defibrating apparatus.

  During the refinement (defibration) process, the fibers are dispersed in a solvent. The type of the solvent is not particularly limited as long as it can be appropriately refined (sometimes referred to as defibration), but an aqueous solvent (water or a mixture of water and an organic solvent) can be used. Examples of the organic solvent include alcohols such as methanol, ethanol, n-propanol, isopropanol, n-butanol, and tbutyl alcohol. Further, ketones such as acetone and methyl ethyl ketone (MEK), ethers such as diethyl ether and tetrahydrofuran (THF), dimethyl sulfoxide (DMSO), dimethylformamide (DMF), dimethylacetamide (DMAc) and the like can be mentioned. Only one organic solvent may be used, or two or more organic solvents may be used.

  The dispersion concentration is preferably 0.1% by mass or more and 20% by mass or less, and more preferably 0.5% by mass or more and 10% by mass or less. This is because if the dispersion concentration is equal to or higher than the lower limit value, the processing efficiency is improved, and if the dispersion concentration is equal to or lower than the upper limit value, blockage in the defibrating apparatus can be prevented.

  The defibrating apparatus is not particularly limited. Examples include a high-speed defibrator, a grinder (stone mortar-type pulverizer), a high-pressure homogenizer, an ultra-high-pressure homogenizer, a CLEARMIX, a high-pressure collision-type pulverizer, a ball mill, a bead mill, a disk refiner, and a conical refiner. In addition, a wet pulverizing apparatus such as a twin-screw kneader, a vibration mill, a homomixer under high-speed rotation, an ultrasonic disperser, and a beater can be used as appropriate.

  The refinement treatment can be performed until a fiber having a desired average fiber width is obtained. A fine fiber dispersion (slurry) is obtained by the refining treatment. The obtained fine fiber dispersion may contain fibers having a fiber width of more than 1000 nm, but preferably does not contain fibers having a fiber width of more than 1000 nm. The density | concentration of a fine fiber here is 0.1 to 20 mass%, for example, and may be 0.5 to 10 mass%.

<Process for preparing a sheet from cellulose fibers>
In the present invention, an insulating film for a fingerprint authentication device can be produced by preparing a sheet from a dispersion (slurry) of cellulose fibers. Although the preparation method of a sheet | seat is not specifically limited, Typically, the following papermaking method and the coating method can be mentioned.

(Paper making method)
In addition to continuous paper machines such as long-mesh type, circular net type, and inclined type that use cellulose fiber-containing slurry in ordinary paper making, multi-layered paper making machines combining these, and well-known paper making methods such as hand-making Paper is made and can be made into a sheet in the same manner as ordinary paper. That is, the cellulose fiber-containing slurry is filtered and dehydrated on a wire to obtain a wet paper sheet, and then the sheet can be obtained by pressing and drying. The concentration of the slurry is not particularly limited, but it is preferably 0.05% by mass or more and 5% by mass or less. If the concentration is too low, it takes a long time for filtration. Conversely, if the concentration is too high, a uniform sheet cannot be obtained. It is not preferable. When the slurry is filtered and dehydrated, the filter cloth at the time of filtration is not particularly limited, but it is important that the cellulose fibers do not pass through and the filtration rate is not too slow. Although it does not specifically limit as such a filter cloth, The sheet | seat, fabric, and porous film which consist of organic polymers are preferable. The organic polymer is not particularly limited, but non-cellulosic organic polymers such as polyethylene terephthalate, polyethylene, polypropylene, polytetrafluoroethylene (PTFE) and the like are preferable. Specific examples include a porous film of polytetrafluoroethylene having a pore size of 0.1 μm to 20 μm, for example, 1 μm, polyethylene terephthalate or polyethylene woven fabric having a pore size of 0.1 μm to 20 μm, for example, 1 μm, but is not particularly limited.

(Coating method)
The coating method is a method for obtaining a sheet by coating a cellulose fiber-containing slurry on a base material and drying the cellulose fiber-containing layer from the base material. By using a coating apparatus and a long base material, sheets can be continuously produced. The quality of the substrate is not particularly limited, but the one with higher wettability to the cellulose fiber-containing slurry may be able to suppress the shrinkage of the sheet during drying, but the sheet formed after drying is more easily peeled off It is preferable to select what can be done. Among them, a resin plate or a metal plate is preferable, but is not particularly limited. Among them, suitable ones are preferably used alone or laminated. For example, resin plates such as acrylic plates, polyethylene terephthalate plates, vinyl chloride plates, polystyrene plates, polyvinylidene chloride plates, metal plates such as aluminum plates, zinc plates, copper plates, iron plates, etc., and those whose surfaces are oxidized are used. can do. Alternatively, a stainless plate, a brass plate, or the like can be used, but is not particularly limited. In order to apply the cellulose fiber-containing slurry onto the base material, various coaters that can apply a predetermined amount of slurry to the base material may be used. Although not particularly limited, for example, a roll coater, a gravure coater, a die coater, a curtain coater, a spray coater, a blade coater, a rod coater, an air doctor coater and the like can be used. Among the above, coating methods such as a die coater, curtain coater, spray coater, and air doctor coater are effective for uniform coating. As will be described later, when a sheet is used as a laminate, it may not be necessary to peel off the substrate.

(Dehydration and drying)
After papermaking or coating, if necessary, at least one of dehydration and drying is performed to form a sheet. Although it does not specifically limit as a dehydration method, The dehydration method normally used by manufacture of paper is mentioned, The method of dehydrating with a roll press after dehydrating with a long net, a circular net, an inclined wire, etc. is preferable. Further, the drying method is not particularly limited, and examples thereof include methods used in paper production. For example, methods such as a cylinder dryer, a Yankee dryer, hot air drying, and an infrared heater are preferable. The drying method is not particularly limited, and may be a non-contact drying method, a method of drying while restraining the sheet, or a combination thereof.

  The non-contact drying method is not particularly limited, but a method of drying by heating with hot air, infrared rays, far infrared rays or near infrared rays (heating drying method) or a method of drying in vacuum (vacuum drying method) is applied. Can do. Although the heat drying method and the vacuum drying method may be combined, the heat drying method is usually applied. Although drying by infrared rays, far infrared rays, or near infrared rays can be performed using an infrared device, a far infrared device, or a near infrared device, it is not particularly limited. The heating temperature in the heat drying method is not particularly limited, but is preferably 40 ° C. or higher and 120 ° C. or lower, and more preferably 40 ° C. or higher and 105 ° C. or lower. If the heating temperature is at least the lower limit value, the dispersion medium can be volatilized quickly, and if it is at most the upper limit value, the cost required for heating and the discoloration due to the heat of the fine fibers can be suppressed.

(Flattening process)
The fine fibrous cellulose-containing sheet produced as described above may be further subjected to a flattening treatment. The flattening process can be performed using, for example, a calendar. The calendar may be either a super calendar or a soft calendar, but a super calendar can be preferably used. For example, the flattening process can be performed by inserting a sheet into a super calendar set to a predetermined temperature and a predetermined speed and passing the sheet under pressure for an appropriate number of times.

(Hydrophilic polymer)
Moreover, you may add a hydrophilic polymer in the case of preparation of a sheet | seat. Examples of hydrophilic polymers include polyethylene glycol, cellulose derivatives (hydroxyethyl cellulose, carboxyethyl cellulose, carboxymethyl cellulose, etc.), casein, dextrin, starch, modified starch, polyvinyl alcohol, modified polyvinyl alcohol (acetoacetylated polyvinyl alcohol, etc.), Polyethylene oxide, polyvinyl pyrrolidone, polyvinyl methyl ether, polyacrylic acid salts, polyacrylamide, acrylic acid alkyl ester copolymer, urethane copolymer and the like can be mentioned, but are not particularly limited.

  A hydrophilic low molecular weight compound can also be used in place of the hydrophilic polymer. Examples of hydrophilic low molecular weight compounds include, but are not limited to, glycerin, erythritol, xylitol, sorbitol, galactitol, mannitol, ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, and butylene glycol.

  The mixing of the hydrophilic polymer or the hydrophilic low molecular compound is not particularly limited. For example, before the paper making or coating, the hydrophilic polymer or the hydrophilic low molecular compound is added to the cellulose fiber-containing slurry. Can be done by. The addition amount in the case of adding a hydrophilic polymer or a hydrophilic low molecular compound is preferably 1 part by mass or more and 200 parts by mass or less, more preferably 1 part by mass or more and 150 parts by mass with respect to 100 parts by mass of the solid content of the cellulose fiber. Although it is below mass parts, it is not particularly limited. The addition amount is more preferably 2 parts by mass or more and 120 parts by mass or less, and particularly preferably 3 parts by mass or more and 100 parts by mass or less, but is not particularly limited.

[Characteristics of insulating film for fingerprint authentication device]
Although the characteristic of the insulating film for fingerprint authentication devices of the present invention is not particularly limited as long as it is useful in the application of an insulating film for fingerprint authentication devices, it preferably has the following characteristics.

<Thickness>
The thickness of the insulating film can be measured by an ordinary method, for example, it can be measured by a stylus type thickness meter. The thickness of the insulating film is preferably 200 μm or less, more preferably 150 μm or less, further preferably 100 μm or less, and particularly preferably 50 μm or less, but is not particularly limited. The lower limit of the thickness of the insulating film is not particularly limited, but is generally 3 μm or more, 5 μm or more, or 10 μm or more.

<Relative permittivity>
The dielectric constant of the insulating film refers to a value measured under measurement conditions of a frequency of 1 MHz, a temperature of 23 ° C., and a relative humidity of 50% using an LCR meter in accordance with ASTM standard D150. The dielectric constant of the insulating film is preferably 6 or more, more preferably 7 or more, more preferably 8 or more, more preferably 9 or more, and still more preferably 10 or more. However, it is not particularly limited. The upper limit of the dielectric constant of the insulating film is not particularly limited, but is generally 20 or less, and may be 15 or less.

<Capacitance>
The capacitance of the insulating film is a value calculated according to the formula (1) from the area S and the dielectric constant ε _{0 of} vacuum, where d is the thickness of the insulating film, ε _r is the relative dielectric constant of the insulating film. In the calculation of the capacitance, it is assumed that a parallel plate capacitor having an area of 2 cm × 1 cm is inserted between the electrodes, and the dielectric constant ε _{0 of} vacuum is 8.85 × 10 ⁻¹² F / m.
Formula (1): C = (ε ₀ · ε _r · S) / d
The capacitance of the insulating film is preferably 400 pF or more, more preferably 450 pF or more, and further preferably 500 pF or more, but is not particularly limited. The upper limit of the capacitance of the insulating film is not particularly limited, but is generally 5000 pF or less and may be 3000 pF or less.

<Tensile modulus>
The tensile elastic modulus of the insulating film refers to a value measured at a temperature of 23 ° C. and a relative humidity of 50% using a tensile tester in accordance with JIS standard P8113. The tensile elastic modulus of the insulating film of the present invention is preferably 7.0 GPa or more, and more preferably 6.5 GPa or more. Although an upper limit is not specifically limited, For example, it is 25.0 GPa or less, or is 20.0 GPa or less.

<Linear thermal expansion coefficient>
The linear thermal expansion coefficient of the insulating film refers to a value measured by the following method. A test piece having a width of 3 mm and a length of 30 mm is measured in a tensile mode using a thermomechanical analyzer. In the measurement, the distance between chucks is set to 20 mm, the load is set to 10 g, the temperature is increased from room temperature to 180 ° C. at 5 ° C./min, the temperature is decreased from 180 ° C. to 25 ° C. at 5 ° C./min, and the temperature is decreased from 25 ° C. to 180 ° C. The temperature is raised at 5 ° C./min. The linear thermal expansion coefficient is calculated from the measured value from 60 ° C. to 100 ° C. at the time of the second temperature increase. The linear thermal expansion coefficient of the insulating film is preferably 30 ppm / ° C. or less, more preferably 20 ppm / ° C. or less, and further preferably 10 ppm / ° C. or less.

<Total light transmittance>
The total light transmittance of the insulating film refers to a value measured using a haze meter in accordance with JIS standard K7361. The insulating film of the present invention preferably has high transparency, and the total light transmittance thereof is preferably 85% or more, more preferably 88% or more, and further preferably 90% or more.

<Haze>
The haze of the insulating film refers to a value measured using a haze meter in accordance with JIS standard K7136. The insulating film of the present invention preferably has high transparency, and its haze is preferably 5% or less, more preferably 3% or less, and further preferably 2% or less.

[Laminate]
The insulating film for a fingerprint authentication device of the present invention can be used as a single-layer insulating film, but at least one of a resin layer and an inorganic layer is formed on at least one surface of the insulating film and used as a laminate. You can also By lamination, water resistance (water resistance, moisture resistance, water repellency) can be further imparted. When laminating the inorganic layer and the resin layer, the order is not particularly limited, but first laminating the resin layer on the surface of the insulating film smoothes the surface for forming the inorganic layer, This is preferable in that the defect can be reduced. Further, other constituent layers other than the resin layer and the inorganic layer, for example, an easy adhesion layer for facilitating adhesion of the upper layer may be included. In the case of lamination, when used for applications in which transparency is particularly important, it is preferable not to include a heating step or a UV irradiation step that promotes yellowing of the sheet. The laminate obtained by lamination preferably includes at least one inorganic layer and at least one resin layer formed on at least one side of the fingerprint authentication device insulating film. The number of layers such as an inorganic layer and a resin layer is not particularly limited. From the viewpoint of sufficient moisture resistance while maintaining flexibility and transparency, for example, it is preferable to laminate two or more and 15 layers or less alternately with an inorganic layer and a resin layer on one side, for example. It is more preferable to stack 7 layers or less.

  The material constituting the inorganic layer is not particularly limited, but for example, aluminum, silicon, magnesium, zinc, tin, nickel, titanium; these oxides, carbides, nitrides, oxycarbides, oxynitrides, or oxycarbonitrides Or a mixture thereof. From the viewpoint that high moisture resistance can be stably maintained, silicon oxide, silicon nitride, silicon oxide carbide, silicon oxynitride, silicon oxycarbonitride, aluminum oxide, aluminum nitride, aluminum oxide carbide, aluminum oxynitride, or these Mixtures are preferred.

  The resin used as the main component for forming the resin layer is not particularly limited, but epoxy resin, acrylic resin, oxetane resin, silsesquioxane resin, phenol resin, urea resin, melamine resin, unsaturated polyester resin, Silicon resin, polyurethane resin, silsesquioxane resin, diallyl phthalate resin, or the like can be given. In order to obtain a low water-absorbing laminate, the resin preferably has few hydrophilic functional groups such as a hydroxy group, a carboxyl group, or an amino group.

The resin layer may include a compound that forms a covalent bond with a functional group (such as a phosphate group) introduced into the cellulose fiber. As a compound which forms a covalent bond, the compound containing at least 1 sort (s) selected from a silanol group, an isocyanate group, a carbodiimide group, an epoxy group, and an oxazoline group is mentioned, for example. Of the above compounds, compounds containing a silanol group or an isocyanate group, which are excellent in reactivity with the functional group introduced into the cellulose fiber, are more preferable. By containing such a compound in the main component constituting the resin layer, the adhesion between the sheet and the resin layer can be further strengthened.

[Fingerprint authentication device]
The fingerprint authentication device of the present invention is a device having the above-described insulating film or laminate for the fingerprint authentication device of the present invention. Specifically, the fingerprint authentication device of the present invention includes (a) a supporting substrate, (b) a sensor circuit board provided with an electrode on one side, and (c) the electrode on the one side of the sensor circuit board. The insulating film or laminate for a fingerprint authentication device of the present invention provided so as to cover is provided in this order.

<Configuration of fingerprint authentication device>
An example of the configuration of the fingerprint authentication apparatus is shown in FIG.
In FIG. 2, the support substrate 1 may be a chip-like substrate on which a signal detection circuit or the like is formed. The support substrate 1 can be formed from silicon (Si) or the like, but is not particularly limited.
A sensor circuit board 2 is provided on the upper surface of the support substrate 1, and electrodes 3 are provided on the sensor circuit board 2 in a two-dimensional array. A sensor circuit 4 is configured by the sensor circuit board 2 and the electrodes 3 provided thereon. Further, an insulating film 5 is provided so as to cover the electrode 3. The insulating film for a fingerprint authentication device of the present invention can be used as the insulating film 5 described above. The insulating film 5 can come into contact with the user's finger 6.

  In the sensor circuit board, a plurality of scanning lines formed in parallel with each other at a predetermined interval, and a plurality of signal lines formed in parallel with each other at a predetermined interval so as to be orthogonal to the scanning lines. And may be provided. A switching element formed of a transistor or the like may be provided at a position corresponding to each of the intersections of the plurality of scanning lines and the plurality of signal lines. An active matrix array may be configured by these scanning lines, signal lines, and switching elements, but is not particularly limited. As the active matrix array, a MOS transistor array formed on a semiconductor substrate, a thin film transistor (TFT) formed on an insulating substrate, or the like can be used, but is not particularly limited. On this active matrix array, the electrodes 3 may be provided in a matrix at positions corresponding to the switching elements.

  A fingerprint authentication device as shown in FIG. 2 can be manufactured using a standard CMOS process.

<Principle of capacitive fingerprint authentication device>
The principle of the capacitive fingerprint authentication device shown in FIG. 2 is as follows. An insulating film 5 is provided on the surface of the fingerprint authentication device, and a large number of electrodes 3 (one of capacitor electrodes) are provided on the sensor circuit board 2 below the insulating film 5. When a finger 6 is placed on the surface of the insulating film 5 and a current is applied, the electrode 3 and the surface of the finger 6 form a capacitor 7 and charges corresponding to the unevenness of the finger 6 are accumulated. When the distance between the electrode 3 and the surface of the finger 6 is short, a large amount of charge is accumulated, and when the distance is long, a small amount of charge is accumulated. A fingerprint image can be acquired by reading out the electric charge for each electrode and A / D converting it to, for example, 8-bit (= 256) light / dark gradation. Note that the capacitance fingerprint authentication device described above can be easily reduced in thickness because it does not require a light source.

<Principle of other fingerprint authentication devices>
3 and 4 show another principle of the fingerprint authentication device.
In FIG. 3, a finger 6 is placed on the surface of the insulating film 5 and an electric field is applied between the stainless steel detection ring 8 and the electrode 3 to detect the inner skin layer 9, thereby recognizing the shape of the fingerprint. Is done. An example of this system can be referred to WO2013 / 173773.

  In FIG. 4, a finger 6 is placed on the surface of the insulating film 5 and an electric field is applied between the emission electrode 10 and the detection electrode 11 to detect the inner skin layer 9, thereby recognizing the shape of the fingerprint. The

<Authentication method>
Examples of the authentication method using the above-described fingerprint authentication device include a pattern matching method and a feature point extraction method, but are not particularly limited. The pattern matching method is a method for directly comparing fingerprint images. In the feature point extraction method, for the fingerprint image information read by the fingerprint authentication device, the coordinates and positional relationship of the fingerprint endpoints (points where the ridges are cut) and branch points (points where the ridges are separated) are extracted, Register as very small fingerprint data of tens to hundreds of bytes. Similarly, at the time of authentication, a feature point is extracted, and authentication can be performed by using only the feature point data and comparing it with registered data.

<Application of fingerprint authentication device>
Applications of the fingerprint authentication device of the present invention can be used in applications that require personal authentication. For example, the following applications can be mentioned, but there is no particular limitation.
• Install the fingerprint authentication device on a personal computer or computer peripherals and log in using fingerprint authentication.
・ Use a fingerprint authentication device to lock data and folders to prevent information leakage.
-The fingerprint authentication device is combined with various IC cards to identify the user and prevent unauthorized use.
・ Install fingerprint authentication device on mobile phones and mobile terminals to prevent others from seeing privacy information.
・ A fingerprint authentication device will be installed at the door entrance / exit gate to prevent outsiders from entering.
・ Use the fingerprint authentication device to identify and set individuals for opening and closing of automobile doors and engine control.
・ Personal recognition for amusement and other users of devices are limited using fingerprint authentication devices.
-Approve electronic approval using a fingerprint authentication device.
・ Verify the identity of electronic commerce using a fingerprint authentication device.
・ Identification of person when accessing network database

  EXAMPLES Hereinafter, although an Example demonstrates this invention, the scope of the present invention is not limited by an Example.

<Example 1>
[Preparation of phosphorylation reagent]
265 g of sodium dihydrogen phosphate dihydrate and 197 g of disodium hydrogen phosphate were dissolved in 538 g of water to obtain an aqueous solution of a phosphoric acid compound (hereinafter referred to as “phosphorylation reagent”).

[Phosphorylation]
Softwood bleached kraft pulp (manufactured by Oji Holdings Corporation, moisture 50% by mass, Canadian standard freeness (CSF) 700 ml measured according to JIS P8121) is diluted with ion-exchanged water so that the water content is 80% by mass, A pulp suspension was obtained. 210 g of the phosphorylating reagent was added to 500 g of this pulp suspension, and the mixture was dried until the mass reached a constant weight while kneading occasionally with a blast dryer (Yamato Scientific Co., Ltd. DKM400) at 105 ° C. Subsequently, heat treatment was performed for 1 hour while occasionally kneading with a blow dryer at 150 ° C. to introduce phosphate groups into the cellulose. The amount of phosphate groups introduced at this time was 0.98 mmol / g.

  The amount of phosphate groups introduced was measured by diluting cellulose with ion-exchanged water so that the content was 0.2% by mass, and then treating with ion-exchange resin and titration with alkali. In the treatment with an ion exchange resin, 1/10 by volume of a strongly acidic ion exchange resin (Amberjet 1024: Organo Co., Ltd., conditioned) is added to a 0.2 mass% cellulose-containing slurry, followed by shaking treatment for 1 hour. It was. Thereafter, the mixture was poured onto a mesh having an opening of 90 μm to separate the resin and the slurry. In titration using an alkali, a change in the value of electrical conductivity exhibited by the slurry was measured while adding a 0.1N sodium hydroxide aqueous solution to the fibrous cellulose-containing slurry after ion exchange. That is, the alkali amount (mmol) required in the first region of the curve shown in FIG. 1 was divided by the solid content (g) in the titration target slurry to obtain the substituent introduction amount (mmol / g).

[Alkali treatment, washing]
Next, 5000 ml of ion-exchanged water was added to the cellulose into which the phosphate group was introduced, and the mixture was dehydrated after washing with stirring. The pulp after dehydration was diluted with 5000 ml of ion-exchanged water, and while stirring, a 1N sodium hydroxide aqueous solution was added little by little until the pH became 12 or more and 13 or less to obtain a pulp dispersion. Thereafter, this pulp dispersion was dehydrated and washed by adding 5000 ml of ion exchange water. This dehydration washing was repeated once more.

[Machine processing]
Ion exchange water was added to the pulp obtained after washing and dewatering to obtain a pulp dispersion having a solid content of 1.0% by mass. This pulp dispersion was passed through a homogenizing chamber 5 times with a high-pressure homogenizer (“Panda Plus 2000” manufactured by NiroSoavi) at an operating pressure of 1200 bar to obtain a fine fibrous cellulose dispersion. Furthermore, it was passed through the treatment chamber 5 times at a pressure of 245 MPa with a wet atomizer ("Ultimizer" manufactured by Sugino Machine Co., Ltd.) to obtain a fine fibrous cellulose dispersion. The average fiber width of the fine fibrous cellulose contained in the fine fibrous cellulose dispersion (A) was 4 nm. The aspect ratio of the fine fibrous cellulose was 315.

[Sheet]
The concentration was adjusted so that the solid content concentration of the fine fibrous cellulose dispersion was 0.5% by mass. Thereafter, 20 parts by mass of a 0.5% by mass aqueous solution of polyethylene oxide (“PEO-18” manufactured by Sumitomo Seika) was added to 100 parts by mass of the fine fibrous cellulose dispersion. Next, the dispersion was weighed so that the finished basis weight of the sheet was 45.0 g / m ² , developed on a commercially available acrylic plate, and dried in a constant temperature and humidity chamber at 35 ° C. and a relative humidity of 15%. In addition, a metal frame for damming (a metal frame having an inner dimension of 180 mm × 180 mm) was disposed on the acrylic plate so as to have a predetermined basis weight. By the above procedure, a fine fibrous cellulose-containing sheet was obtained.

[Planarization]
The fine fibrous cellulose-containing sheet was inserted into a super calender (“Mini Super Calender” manufactured by Marukyo Giken Co., Ltd.) set at a temperature of 50 ° C. and a speed of 1 m / min, and passed 5 times under a pressure of 5 MPa. By the above procedure, an insulating film for a fingerprint authentication device was obtained.

<Example 2>
In forming the sheet of Example 1, the dispersion was weighed so that the finished basis weight of the sheet was 22.5 g / m ² and developed on a commercially available acrylic plate. Other procedures were the same as in Example 1, and an insulating film for a fingerprint authentication device was obtained.

<Example 3>
[Lamination of resin layer]
The resin layer was laminated | stacked in the following procedure on the fine fibrous cellulose containing flattened sheet obtained in Example 1. FIG. Silsesquioxane resin (Arakawa Chemical Industries "Composeran SQ107") 10 parts by weight, curing agent (Arakawa Chemical Industries "HBSQ202") 30 parts by weight, isopropyl alcohol 60 parts by weight are mixed, coating liquid Obtained. Subsequently, the coating liquid was applied to one side of the planar sheet containing fine fibrous cellulose with a Mayer bar. Thereafter, after drying at 100 ° C. for 3 minutes, UV coating of 300 mJ / cm ² was irradiated using a UV conveyor device (“ECS-4011GX” manufactured by Eye Graphics) to cure the coating solution, and the thickness was 4 μm. The resin layer was formed. Further, a resin layer was formed on the other surface of the planar sheet containing fine fibrous cellulose using the same procedure. By the above procedure, an insulating film for a fingerprint authentication device having a resin layer laminated on both sides was obtained.

<Comparative Example 1>
A polyethylene terephthalate film ("Lumirror S10" manufactured by Toray Industries, Inc.) was used as an insulating film for a fingerprint authentication device and subjected to the following evaluation.

<Comparative example 2>
A thin glass ("OA-10G" manufactured by Nippon Electric Glass Co., Ltd.) was used as an insulating film for a fingerprint authentication device and subjected to the following evaluation.

<Evaluation>
[thickness]
The thickness of the insulating film for a fingerprint authentication device was measured with a stylus type thickness meter (“Millitron 1202D” manufactured by Marl).

[Relative permittivity]
In accordance with ASTM standard D150, the relative dielectric constant was measured using an LCR meter (“HP4284A” manufactured by Agilent Technologies). The measurement conditions were a frequency of 1 MHz, a temperature of 23 ° C., and a relative humidity of 50%. Before the measurement, the condition was adjusted for 40 hours in an environment of a temperature of 23 ° C. and a relative humidity of 50%.

[Capacitance]
The measured thickness is d, the measured relative dielectric constant is ε _r , and the insulating film for fingerprint authentication device obtained in Examples 1 to 3 and Comparative Examples 1 and 2 is obtained from the area S and the dielectric constant ε _{0 of} vacuum. Was calculated according to the equation (1). In the calculation of the capacitance, it was assumed that a parallel plate capacitor having an area of 2 cm × 1 cm was inserted between the electrodes, and the dielectric constant ε _{0 of} vacuum was 8.85 × 10 ⁻¹² F / m.
Formula (1): C = (ε ₀ · ε _r · S) / d

[Tensile modulus]
In accordance with JIS standard P8113, the tensile modulus at a temperature of 23 ° C. and a relative humidity of 50% was measured using a tensile tester (“Tensile Tester CODE SE-064” manufactured by L & W).

[Linear thermal expansion coefficient]
A test piece having a width of 3 mm and a length of 30 mm was produced by a laser cutter. The test piece was measured in a tensile mode using a thermomechanical analyzer (“TMA7100” manufactured by Hitachi High-Tech). In the measurement, the distance between chucks is set to 20 mm, the load is set to 10 g, the temperature is increased from room temperature to 180 ° C. at 5 ° C./min, the temperature is decreased from 180 ° C. to 25 ° C. at 5 ° C./min, and the temperature is decreased from 25 ° C. to 180 ° C. The temperature was raised to 5 ° C./min. The linear thermal expansion coefficient was calculated from the measured value from 60 ° C. to 100 ° C. during the second temperature increase.

[Total light transmittance]
Based on JIS standard K7361, the total light transmittance was measured using a haze meter ("HM-150" manufactured by Murakami Color Research Laboratory Co., Ltd.).

[Haze]
Based on JIS standard K7136, haze was measured using a haze meter (“HM-150” manufactured by Murakami Color Research Laboratory Co., Ltd.).

[result]
As is clear from Table 1, in Examples 1 to 3 using the fine fibrous cellulose-containing sheet, an insulating film for a fingerprint authentication device having a small thickness and a large relative dielectric constant was obtained. Due to the above characteristics, the calculated capacitance was also large, and it was confirmed that this was a suitable insulating film from the viewpoint of authentication sensitivity when configuring a fingerprint authentication device. In addition, since the insulating film for fingerprint authentication device obtained in Examples 1 to 3 has a large tensile elastic modulus and a small coefficient of linear thermal expansion, it is suitable from the viewpoint of dimensional stability in configuring the fingerprint authentication device. It was confirmed that it was a proper insulating film. Furthermore, the insulating films for fingerprint authentication devices obtained in Examples 1 to 3 have a high total light transmittance and a low haze, and thus are excellent in transparency. The high transparency of the insulating film suggests the possibility of applying a method such as freely coloring the insulating film or applying a design to the insulating film.

In Comparative Example 1 in which polyethylene terephthalate was used as the insulating film for the fingerprint authentication device, although the thickness was small, the relative permittivity was small, so that the capacitance was inferior to Examples 1-3. Moreover, it became a result inferior to Examples 1-3 also from the surface of dimensional stability and transparency.
In Comparative Example 2 in which thin glass was used as the insulating film for the fingerprint authentication device, although the relative dielectric constant was relatively large, the capacitance was inferior to that of Examples 1 to 3 due to the large thickness.

<Example 4 (Manufacture example 1 of a laminated body)>
Using the insulating film for a fingerprint authentication device obtained in any of Examples 1 to 3, a laminate is obtained by the following procedure.
An aluminum oxide film is formed on the insulating film for the fingerprint authentication apparatus by an atomic layer deposition apparatus (“SUNALE R-100B” manufactured by Picosun). As an aluminum raw material, trimethylaluminum (TMA) and H ₂ O are used for the oxidation of TMA. The chamber temperature is set to 150 ° C., the TMA pulse time is 0.1 seconds, the purge time is 4 seconds, the H ₂ O pulse time is 0.1 seconds, and the purge time is 4 seconds. By repeating this cycle for 405 cycles, a laminate in which an aluminum oxide film having a thickness of 30 nm is laminated on both surfaces of the insulating film for fingerprint authentication device is obtained.

<Example 5 (Manufacturing Example 2 of laminate)>
Using the insulating film for a fingerprint authentication device obtained in any of Examples 1 to 3, a laminate is obtained by the following procedure.
A silicon oxynitride film is formed on the insulating film for the fingerprint authentication device by a plasma CVD device (“ICP-CVD roll-to-roll device” manufactured by Celbach). An insulating film for a fingerprint authentication device is bonded to the upper surface of a carrier film (PET film) with a double-sided tape and placed in a vacuum chamber. The temperature in the vacuum chamber is set to 50 ° C., and the inflow gas is silane, ammonia, oxygen, and nitrogen. Plasma discharge is generated and film formation is performed for 45 minutes to obtain a stacked body in which a silicon oxynitride film having a thickness of 500 nm is stacked on one surface of an insulating film for a fingerprint authentication device. Further, by performing film formation on the opposite surface in the same procedure, a laminated body in which a silicon oxynitride film having a thickness of 500 nm is laminated on both surfaces of the insulating film for a fingerprint authentication device can also be obtained.

DESCRIPTION OF SYMBOLS 1 Support substrate 2 Sensor circuit board 3 Electrode 4 Sensor circuit 5 Insulating film 6 Finger 7 Capacitor 8 Stainless steel detection ring 9 Inner skin layer 10 Release electrode 11 Detection electrode

Claims (12)

An insulating film for a fingerprint authentication device for covering a surface of a substrate on which an electrode is provided among the surfaces of a substrate constituting the fingerprint authentication device, the insulating film for a fingerprint authentication device including cellulose fibers. The insulating film for a fingerprint authentication device according to claim 1, wherein an average fiber width of the cellulose fibers is 1000 nm or less, and an aspect ratio of the cellulose fibers is 30 or more. The insulating film for a fingerprint authentication device according to claim 1, wherein the insulating film has a thickness of 100 μm or less. The insulating film for a fingerprint authentication device according to any one of claims 1 to 3, wherein the dielectric constant of the insulating film is 6 or more. The insulating film for a fingerprint authentication device according to any one of claims 1 to 4, wherein the insulating film has a capacitance of 400 pF or more. The insulating film for a fingerprint authentication device according to any one of claims 1 to 5, wherein a tensile elastic modulus of the insulating film is 7.0 GPa or more. The insulating film for a fingerprint authentication device according to any one of claims 1 to 6, wherein a linear thermal expansion coefficient of the insulating film is 30 ppm / ° C or less. The insulating film for a fingerprint authentication device according to any one of claims 1 to 7, wherein the total light transmittance of the insulating film is 85% or more. The insulating film for a fingerprint authentication device according to any one of claims 1 to 8, wherein the haze of the insulating film is 5% or less. A laminate comprising the fingerprint authentication device insulating film according to claim 1 and an inorganic layer laminated on at least one surface of the fingerprint authentication device insulation film. A laminate comprising the fingerprint authentication device insulating film according to claim 1 and a resin layer laminated on at least one surface of the fingerprint authentication device insulating film. (A) a supporting substrate;
The sensor circuit board provided with an electrode on one side; and (c) the electrode on the one side of the sensor circuit board provided so as to cover the electrode. An insulating film for a fingerprint authentication device or a laminate according to claim 10 or 11:
In this order.

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