JP6273920B2 - Conductive resin composition for resistance type pressure sensor and resistance type pressure sensor - Google Patents

Description

  The present invention relates to a conductive resin composition for a resistance type pressure sensor and a resistance type pressure sensor using the same.

  In recent years, many resistance-type pressure-sensitive sensors using polymers have been reported (for example, see Patent Documents 1 to 4 below). Sensors using polymers are highly flexible and can give shape-following, and are lightweight and have a high degree of freedom in design, such as downsizing or large area, and are expected to be applied to healthcare and medical fields. Yes.

JP 2012-103273 A JP 2012-208038 A JP2013-61208A JP 2013-68562 A

  The present invention has been made in view of such circumstances, and a resistance pressure sensor having a sufficient sensitivity in which a resin component is used in a pressure-sensitive portion, and a conductive resin for a resistance-type pressure sensor used therein. An object is to provide a composition.

In order to solve the above-mentioned problems, the present invention is a conductive resin composition for a resistance-type pressure-sensitive sensor containing a resin component and a conductive filler, which is 25 ° C. of the conductive resin layer formed from the conductive resin composition. When the unloaded resistance value in A is A ₂₅ and the resistance value when a load of 300 kPa at 25 ° C. is applied is B ₂₅ , the following formula (1), the following formula (2), and the following formula (3) are satisfied. A conductive resin composition for a first resistance type pressure sensitive sensor is provided.
A ₂₅ ≧ 1 kΩ (1)
1000 kΩ ≧ B ₂₅ ≧ 0.01 kΩ (2)
A ₂₅ / B ₂₅ ≧ 10 (3)

From the viewpoint that the first conductive resin composition for resistance-type pressure-sensitive sensors according to the present invention can operate stably even under high-temperature conditions, the conductive resin layer formed from the conductive resin composition at 80 ° C. When the resistance value when no load is A ₈₀ and the resistance value when a load of 300 kPa at 80 ° C. is applied is B ₈₀ , the following formula (4), the following formula (5), and the following formula (6) are satisfied. Is preferred.
A ₈₀ ≧ 1kΩ (4)
1000 kΩ ≧ B ₈₀ ≧ 0.01 kΩ (5)
A ₈₀ / B ₈₀ ≧ 10 (6)

  In order to solve the above problems, the present invention is also a conductive resin composition for a resistance-type pressure-sensitive sensor containing a resin component and a conductive filler, wherein the resin component contains a polyvinyl butyral resin. A conductive resin composition for a sensor is provided.

In order to solve the above problems, the present invention also includes a pair of electrodes and a conductive resin layer containing a resin component and a conductive filler provided between the electrodes, and the conductive resin layer at 25 ° C. When the no-load resistance value is A ₂₅ and the resistance value when a load of 300 kPa at 25 ° C. is applied is B ₂₅ , the following values satisfy the following formula (1), the following formula (2), and the following formula (3). 1 resistance type pressure sensitive sensor is provided.
A ₂₅ ≧ 1 kΩ (1)
1000 kΩ ≧ B ₂₅ ≧ 0.01 kΩ (2)
A ₂₅ / B ₂₅ ≧ 10 (3)

The first resistance-type pressure-sensitive sensor according to the present invention has a no-load resistance value at 80 ° C. of the conductive resin layer of A ₈₀ and a load of 300 kPa at 80 ° C. from the viewpoint that it can operate stably even under high temperature conditions. when the B ₈₀ the resistance value when adding the following formula (4), preferably satisfies the following formula (5) and the following formula (6).
A ₈₀ ≧ 1kΩ (4)
1000 kΩ ≧ B ₈₀ ≧ 0.01 kΩ (5)
A ₈₀ / B ₈₀ ≧ 10 (6)

  In order to solve the above problems, the present invention also includes a pair of electrodes and a conductive resin layer containing a resin component and a conductive filler provided between the electrodes, and the resin component includes a polyvinyl butyral resin. A second resistance type pressure sensitive sensor is provided.

  ADVANTAGE OF THE INVENTION According to this invention, the resin component is used for a pressure sensitive part, and the resistance type pressure sensor which has sufficient sensitivity, and the conductive resin composition for resistance type pressure sensitive sensors used therefor can be provided.

It is a figure which shows one Embodiment of the resistance type pressure-sensitive sensor which concerns on this invention, (1) is a perspective view of a sensor, (2) is sectional drawing which follows the II line in (1).

  DESCRIPTION OF EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings.

  As shown in FIG. 1, the resistance-type pressure-sensitive sensor 1 includes a pair of electrodes 10 and 20 and a conductive resin layer 30 including a resin component 32 and a conductive filler 34 provided between the electrodes. Prepare.

  Examples of the electrodes 10 and 20 include those formed from metals such as aluminum, copper, silver, gold, and platinum. Specifically, for example, copper foil, aluminum foil, gold-plated foil, platinum wire, and resin paste containing conductive metal filler such as silver powder, copper powder, and aluminum powder can be used. About the area and thickness of an electrode, although it can set suitably according to the use of a resistance-type pressure-sensitive sensor, thickness is preferable 1 micrometer-1000 micrometers from a viewpoint of a softness | flexibility and durability.

  As the resin component 32, (meth) acrylic polymer, polyimide resin, urethane resin, polyphenylene ether resin, epoxy resin, phenol resin, polyethylene resin, polyvinyl chloride resin, polyethylene terephthalate resin, nylon resin, polyvinylidene fluoride resin, Polysulfone resin, polyether sulfone resin, nitrile butadiene resin, ABS resin, melamine resin, urea resin, polycarbonate resin, polyacetal resin, silicone resin, polyetherimide resin, phenoxy resin, modified polyphenylene ether resin, polyamide resin, polyvinyl butyral resin , Fluororesin, various modified resins and the like. Moreover, you may use the peptide whose weight average molecular weight is 5000 or more. These can be used alone or in combination of two or more.

  The resin component preferably contains a resin having a glass transition temperature (Tg) of 15 to 250 ° C. from the viewpoint of durability, and contains a resin having a Tg of 40 to 250 ° C. from the viewpoint of durability and heat resistance. It is more preferable.

  Furthermore, in this embodiment, it is preferable that a resin component contains polyvinyl butyral resin from a viewpoint of a sensitivity, durability, heat resistance, the dispersibility of a conductive filler, and film forming property.

  In addition to the above resin, the resin component can also contain a thermosetting resin for the purpose of suppressing heat flow at high temperatures. Such a thermosetting resin can use the component which consists of a reactive compound which raise | generates a crosslinking reaction with a heat | fever, without being specifically limited. Examples of reactive compounds that cause a crosslinking reaction by heat include epoxy resins, bismaleimide resins, cyanate ester resins, phenol resins, urea resins, melamine resins, alkyd resins, acrylic resins, unsaturated polyester resins, silicone resins, and resorcinol formaldehyde. Resin, xylene resin, furan resin, polyurethane resin, ketone resin, triallyl cyanurate resin, polyisocyanate resin, resin containing tris (2-hydroxyethyl) isocyanurate, resin containing triallyl trimellitate, cyclohexane Thermosetting resin synthesized from pentadiene, thermosetting resin by trimerization of aromatic dicyanamide, copolymer of isobutylene / maleic anhydride, acid dianhydride, isocyanate compound, polyfunctional acrylate and / or Is a methacrylate compound, a compound having a styryl group, diallyl bisphenol A, bisallyl nadiimide, diallyl phthalate or diallyl phthalate prepolymer, diallyl melamine, triallyl isocyanurate, allyl modified phenol novolak, 1,3-diallyl-5-glycidyl Examples include isocyanurate. Among these, an epoxy resin is preferable in that excellent thermal fluidity suppression at a high temperature can be imparted. In addition, these thermosetting resins can be used individually by 1 type or in combination of 2 or more types.

  As an epoxy resin which is one of the preferable thermosetting resins, those containing at least two epoxy groups in the molecule are more preferable, and phenol glycidyl ether type epoxy resins are extremely preferable from the viewpoint of curability and cured product characteristics. preferable. Examples of such resins include bisphenol A type (or AD type, S type, and F type) glycidyl ether, water-added bisphenol A type glycidyl ether, ethylene oxide adduct bisphenol A type glycidyl ether, and propylene oxide adduct. Trifunctional type (or tetrafunctional type) such as bisphenol A type glycidyl ether, phenol novolac resin glycidyl ether, cresol novolac resin glycidyl ether, bisphenol A novolac resin glycidyl ether, naphthalene resin glycidyl ether, trisphenolmethane type Glycidyl ether, glycidyl ether of dicyclopentadienephenol resin, heterocycle-containing epoxy resin, alicyclic epoxy resin, glycidyl ester of dimer acid, trifunctional type Or glycidyl amine tetrafunctional) glycidyl amine naphthalene resin, diallyl bisphenol A diglycidyl ether or its polycondensate, and the like. These can be used individually by 1 type or in combination of 2 or more types.

  As the curing agent for the epoxy resin, known curing agents that are usually used can be used. For example, amines, polyamides, acid anhydrides, polysulfides, boron trifluoride, bisphenol A, bisphenol F, bisphenol. Bisphenols having two or more phenolic hydroxyl groups in one molecule such as S, phenol novolac resin, xylylene-modified phenol resin, bisphenol A novolac resin or cresol novolac resin, phenol novolac resin, phenol aralkyl resin, cresol Examples thereof include novolak resin, naphthol aralkyl resin, triphenolmethane resin, terpene-modified phenol resin, dicyclopentadiene-modified phenol resin. As content of a hardening | curing agent, it is preferable to mix | blend by 0.5-2 as an equivalent ratio of the number of epoxy groups of all the epoxy resins, and the number of hydroxyl groups of all the hardening | curing agents.

  As the conductive filler, any material and shape can be used as long as they are conductive. For example, metal fillers such as aluminum particles, copper particles, silver particles, gold particles and platinum particles, carbon fillers such as carbon powder and carbon nanotubes (CNT), and the like can be used. Carbon nanotubes are preferred from the viewpoints of dispersibility, electrical conductivity retention during expansion / contraction or bending, and light weight.

  The blending amount of the conductive filler is preferably set so that the conductive resin layer satisfies a resistance value described later. In the present embodiment, it is preferable that the conductive filler is included in the conductive resin layer at a ratio of 5 to 55% by volume from the viewpoint of securing the pressure sensing property (change in the pressure resistance value).

  The conductive resin layer can be formed from a conductive resin composition for resistance-type pressure-sensitive sensors containing the resin component and the conductive filler.

  The conductive resin composition can be prepared by adding a conductive filler to a resin solution in which a resin is dissolved in a solvent, and stirring and mixing. At this time, a coupling agent may be added to improve the dispersibility of the filler. For example, cyclohexanone, 1-methyl-2-pyrrolidone, toluene or the like is used as the solvent. Cyclohexanone is preferred because the handleability becomes poor when the volatility of the solvent is too high.

  The blending amount of the conductive filler in the conductive resin composition is preferably such that the conductive filler is 5 to 55% by volume when the conductive resin layer is formed. For example, the blending amount of the conductive filler can be set to a ratio of 5 to 55% by volume based on the total volume of the resin component and the conductive filler.

  Although the area and thickness of the conductive resin layer 32 can be appropriately set according to the application of the resistance type pressure sensitive sensor, the thickness is preferably 1 μm to 1000 μm from the viewpoint of flexibility and durability.

In this embodiment, the conductive resin layer 30 has the following formula (1) when the no-load resistance value at 25 ° C. is A ₂₅ and the resistance value when a load of 300 kPa at 25 ° C. is applied is B _25. The following formula (2) and the following formula (3) are preferably satisfied.
A ₂₅ ≧ 1 kΩ (1)
1000 kΩ ≧ B ₂₅ ≧ 0.01 kΩ (2)
A ₂₅ / B ₂₅ ≧ 10 (3)

Resistance of the conductive resin layer in the resistive-type pressure sensor is a conductive resin layer having a thickness of 50 [mu] m, the area having a laminated structure sandwiched between a copper foil having a thickness of 20μm is the sensor element of 1 cm ² and the measurement sample, the The value measured by an electrical resistance measuring device at a predetermined temperature for a sample. The humidity is set to 60%.

As for the resistance value when a load is applied, a load is gradually applied to the sensor element from 0 N to 30 N per cm ² over 15 seconds using a pressure gauge. And the resistance value of the sensor element which added the load of 30N per cm < ² > is measured similarly to the above.

From the viewpoint that the conductive resin layer 30 can operate stably even under high temperature conditions, the resistance value at no load of the conductive resin layer formed from the conductive resin composition at 80 ° C. is set to A ₈₀ and 300 kPa at 80 ° C. the resistance value when a load is applied when the B ₈₀ in the following formula (4), preferably satisfies the following formula (5) and the following formula (6).
A ₈₀ ≧ 1kΩ (4)
1000 kΩ ≧ B ₈₀ ≧ 0.01 kΩ (5)
A ₈₀ / B ₈₀ ≧ 10 (6)

  Moreover, it is preferable that the conductive resin composition for resistance type pressure sensitive sensors which concerns on this embodiment mentioned above satisfies the conditions of said resistance value for the conductive resin layer formed from a composition.

  EXAMPLES Hereinafter, although an Example and a comparative example demonstrate this invention further more concretely, this invention is not limited to a following example.

<Synthesis of polyimide resin>
(Polyimide A)
1,3-bis (3-aminopropyl) tetramethyldisiloxane (manufactured by Shin-Etsu Chemical Co., Ltd., trade name: LP-7100) in a 300 mL flask equipped with a thermometer, stirrer, condenser, and nitrogen inflow pipe 12.42 g, polyoxypropylene diamine (manufactured by BASF Corporation, trade name: D400, molecular weight: 452.4) 22.62 g and N-methyl-2-pyrrolidone 140 g were charged and stirred to prepare a reaction solution. did. After the diamine was dissolved, 32.62 g of 4,4′-oxydiphthalic dianhydride purified in advance by recrystallization from acetic anhydride was added to the reaction solution little by little while the flask was cooled in an ice bath. After reacting at room temperature (25 ° C.) for 8 hours, 80.5 g of xylene is added and heated at 180 ° C. while blowing nitrogen gas to azeotropically remove xylene together with water to contain a polyimide resin (polyimide A). A varnish was obtained. When the molecular weight of the obtained polyimide resin (polyimide A) was measured by GPC, it was number average molecular weight Mn = 14000 and weight average molecular weight Mw = 35000 in terms of polystyrene. Moreover, Tg of the obtained polyimide resin (polyimide A) was 45 degreeC.

(Polyimide B)
In a 300 mL flask equipped with a thermometer, stirrer, condenser, and nitrogen inlet tube, 20.52 g of 2,2-bis (4-aminophenoxyphenyl) propane, 4,9-dioxadecane-1,12-diamine. 20 g and 193.5 g of N-methyl-2-pyrrolidone were charged and stirred to obtain a reaction solution in which each diamine was dissolved in N-methyl-2-pyrrolidone as an organic solvent. To this reaction solution, 52.20 g of 1,10- (decamethylene) bis (trimellitate dianhydride) was added little by little and the reaction was allowed to proceed by heating at 180 ° C. for 5 hours while blowing nitrogen gas. The water generated at this time was removed from the system to obtain a varnish containing a polyimide resin (polyimide B). When the molecular weight of the obtained polyimide resin (polyimide B) was measured by GPC, it was number average molecular weight Mn = 28900 and weight average molecular weight Mw = 88600 in terms of polystyrene. Moreover, Tg of the obtained polyimide resin (polyimide B) was 73 degreeC.

(Polyimide C)
In a 300 ml flask equipped with a thermometer, stirrer, condenser, and nitrogen inlet tube was added 13.67 g (0.1 mol) of 2,2-bis (4-aminophenoxyphenyl) propane and 124 g of N-methyl-2-pyrrolidone. Were stirred. After dissolution of the diamine, 17.40 g (0.1 mol) of decamethylene bistrimellitate dianhydride recrystallized and purified in advance with acetic anhydride was added little by little while the flask was cooled in an ice bath. After reacting at room temperature for 8 hours, 83 g of xylene was added and heated at 180 ° C. while blowing nitrogen gas to azeotropically remove xylene together with water. The reaction solution was poured into a large amount of water, and the precipitated polymer was collected by filtration and dried to obtain a polyimide resin (Polyimide C). As a result of measuring GPC of the obtained polyimide resin (polyimide C), it was Mw = 121000 and Mn = 22800 in terms of polystyrene. Moreover, Tg of the obtained polyimide resin (polyimide C) was 120 degreeC.

<Production of pressure-sensitive sensor element>
(Examples 1-14, Comparative Examples 1-20)
The resin component and conductive filler shown in Tables 1 to 5 are mixed with cyclohexanone as a solvent so that the blending amount (volume%) of the conductive filler is a ratio shown in the table based on the total volume of the resin component and conductive filler. The mixture was added and mixed with a kneading deaerator to obtain a resin composition.

  The above resin composition was coated on a 18 μm thick copper foil and dried at 120 ° C. for 20 minutes to form a 50 μm thick resin film. A copper foil having a thickness of 18 μm was attached to the produced film, and this was cut into a size of 1 cm × 1 cm to obtain a pressure-sensitive sensor element.

The resin components and conductive fillers in the table are as follows.
Acrylic rubber A: manufactured by Nagase ChemteX Corporation, trade name HTR-3CSP (weight average molecular weight = 800,000, Tg = 20 ° C.)
Acrylic rubber B: manufactured by Nagase ChemteX Corporation, trade name SG-280-EK23 (weight average molecular weight = 900,000, Tg = −30 ° C.)
Acrylic rubber C: manufactured by Nagase ChemteX Corporation, trade name SG-708-6 (weight average molecular weight = 700,000, Tg = 0 ° C.)
Polyimide A: synthesized by the above method.
Polyimide B: synthesized by the above method.
Polyimide C: synthesized by the above method.
Polyvinyl butyral A: manufactured by Kuraray Co., Ltd., trade name Mowital B16H (weight average molecular weight = 20,000, Tg = 70 ° C.)
Carbon nanotube A: Showa Denko, trade name VGCF-H (carbon nanotube, 150 nm diameter)

<Evaluation of pressure-sensitive sensor element>
The following evaluation was performed about the pressure-sensitive sensor element provided with the resin layer of 50 micrometers in thickness obtained by the said Example and comparative example. The obtained results are shown in Tables 1-5.

(Measurement of resistance value at no load)
At a temperature of 25 ° C. or 80 ° C., the resistance value of the resin layer of the pressure sensitive sensor element was measured using a pressure gauge and an electric resistance measuring device. The humidity was fixed at 60%.

(Measurement of resistance at 300 kPa load)
A load was gradually applied from 0 N to 30 N per cm ² over 15 seconds using a pressure gauge. With a load of 300 kPa, the resistance value of the resin layer of the pressure-sensitive sensor element was measured using an electric resistance measuring device at a temperature of 25 ° C. or 80 ° C. The humidity was fixed at 60%.

(Evaluation of resistance value (25 ° C))
When the no-load resistance value at 25 ° C. of the resin layer is A ₂₅ and the resistance value when a load of 300 kPa at 25 ° C. is applied is B ₂₅ , the following formula (1), the following formula (2), and the following formula Regarding (3), a case where the condition is satisfied is indicated by “◯”, and a case where the condition is not satisfied is indicated by “×”.
A ₂₅ ≧ 1 kΩ (1)
1000 kΩ ≧ B ₂₅ ≧ 0.01 kΩ (2)
A ₂₅ / B ₂₅ ≧ 10 (3)

(Evaluation of resistance value (80 ° C))
When the no-load resistance value at 80 ° C. of the resin layer is A ₈₀ and the resistance value when a load of 300 kPa at 80 ° C. is applied is B ₈₀ , the following formula (4), the following formula (5), and the following formula Regarding (6), a case where the condition is satisfied is indicated by “◯”, and a case where the condition is not satisfied is indicated by “×”.
A ₈₀ ≧ 1kΩ (4)
1000 kΩ ≧ B ₈₀ ≧ 0.01 kΩ (5)
A ₈₀ / B ₈₀ ≧ 10 (6)

DESCRIPTION OF SYMBOLS 1 ... Resistance type pressure-sensitive sensor 10, 20 ... Electrode, 30 ... Conductive resin layer, 32 ... Resin component, 34 ... Conductive filler.

Claims (6)

A conductive resin composition for a resistance-type pressure-sensitive sensor containing a resin component and a conductive filler,
When the no-load resistance value at 25 ° C. of the conductive resin layer formed from the conductive resin composition is A ₂₅ and the resistance value when a load of 300 kPa at 25 ° C. is applied is B ₂₅ , the following formula A conductive resin composition for a resistance-type pressure-sensitive sensor that satisfies (1), the following formula (2), and the following formula (3).
A ₂₅ ≧ 1 kΩ (1)
1000 kΩ ≧ B ₂₅ ≧ 0.01 kΩ (2)
A ₂₅ / B ₂₅ ≧ 10 (3) When the no-load resistance value at 80 ° C. of the conductive resin layer formed from the conductive resin composition is A ₈₀ and the resistance value when a load of 300 kPa at 80 ° C. is applied is B ₈₀ , the following formula The conductive resin composition for resistance-type pressure-sensitive sensors according to claim 1, wherein (4), the following formula (5), and the following formula (6) are satisfied.
A ₈₀ ≧ 1kΩ (4)
1000 kΩ ≧ B ₈₀ ≧ 0.01 kΩ (5)
A ₈₀ / B ₈₀ ≧ 10 (6) The conductive resin composition for resistance-type pressure-sensitive sensors according to claim 1 , wherein the resin component includes a polyvinyl butyral resin. A pair of electrodes, and a conductive resin layer containing a resin component and a conductive filler provided between the electrodes,
When the no-load resistance value at 25 ° C. of the conductive resin layer is A ₂₅ and the resistance value when a load of 300 kPa at 25 ° C. is applied is B ₂₅ , the following formula (1) and the following formula (2) And a resistance-type pressure-sensitive sensor that satisfies the following formula (3).
A ₂₅ ≧ 1 kΩ (1)
1000 kΩ ≧ B ₂₅ ≧ 0.01 kΩ (2)
A ₂₅ / B ₂₅ ≧ 10 (3) When the no-load resistance value at 80 ° C. of the conductive resin layer is A ₈₀ and the resistance value when a load of 300 kPa at 80 ° C. is applied is B ₈₀ , the following formula (4) and the following formula (5) And the resistance type pressure-sensitive sensor of Claim 4 which satisfy | fills following formula (6).
A ₈₀ ≧ 1kΩ (4)
1000 kΩ ≧ B ₈₀ ≧ 0.01 kΩ (5)
A ₈₀ / B ₈₀ ≧ 10 (6) The resistance-type pressure-sensitive sensor according to claim 4 or 5, wherein the resin component includes a polyvinyl butyral resin.

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