JP6534248B2 - Epoxy resin composition for thermistor sensor casting and thermistor sensor - Google Patents

Description

  BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an epoxy resin composition for casting a thermistor and a thermistor sensor, and more particularly to an epoxy resin composition for casting a thermistor sensor that is excellent in color fastness, flexibility, and fall-off prevention.

  Thermister means a resistor sensitive to heat, and refers to a semiconductor whose resistance value changes extremely as temperature changes. It is widely used as a sensor utilizing this property, and is called a thermistor sensor.

  A resin casting type thermistor sensor is known as an example of this thermistor sensor. As a resin cast type thermistor sensor, for example, after inserting a thermistor sensor main body consisting of a thermistor element and an electric wire coated with an insulating covering material into a protective case, an epoxy resin composition is injected and the epoxy resin composition is heated What was hardened can be mentioned.

  Basic characteristics required for this epoxy resin composition include flexibility for relieving the stress generated between the coated wire and the casting resin when the sensor is installed, and the protective case of the thermistor sensor main body. Dropout prevention can be mentioned.

An epoxy resin composition containing an epoxy resin and an amine-based curing agent has been proposed as an epoxy resin composition for thermistor sensor casting (see, for example, Patent Document 1).
However, although this resin is excellent in flexibility, when a vinyl chloride resin is used as a wire covering material, the amine-based curing agent migrates to the surface of the vinyl chloride resin to cause a dehydrochlorination reaction, so that the vinyl chloride resin is It has the disadvantage of causing discoloration and deterioration.
For this reason, it is necessary to use a crosslinked polyethylene resin as a wire coating material, which leads to cost increase.

Moreover, the epoxy resin composition which used not an amine-type curing agent but an acid anhydride as a curing agent is also disclosed (for example, refer patent document 2).
However, this relates to an epoxy unit or the like used in a prefabricated joint (PJ) method, which is a type of connection method of a power cable. Since the epoxy unit is a molded product using a mold, it needs to be excellent in mold releasability from the mold. For this reason, when this thing is applied as it is for a thermistor sensor, it has the fault that the thermistor sensor body itself falls out of the protective case.

  For this reason, even when an inexpensive vinyl chloride resin is used as a wire covering material, it does not discolor, and furthermore, the thermistor sensor casting epoxy resin composition having excellent flexibility and falling-off prevention property, and this epoxy There has been a strong demand from the industry for thermistor sensors using resin compositions.

JP, 2012-059731, A Japanese Patent Application Laid-Open No. 09-324111

  The present invention is intended to provide a thermistor sensor casting epoxy resin composition and a thermistor sensor which are excellent in color fastness, flexibility, and fall-off prevention.

  MEANS TO SOLVE THE PROBLEM As a result of earnestly examining in order to solve the said subject, the present inventors find out that the said subject can be solved, when the epoxy resin composition containing an epoxy resin and acid anhydride which have a specific epoxy equivalent is used. The present invention has been completed.

That is, the present invention
[1] A thermistor sensor for casting, which is an epoxy resin composition for casting, which is used by casting between a protective case and a thermistor sensor body comprising a thermistor element and an electric wire coated with an insulation coating material, wherein the thermistor sensor The mold epoxy resin composition contains (A) an epoxy resin having an epoxy equivalent of 350 or more and a curing agent ,
The curing agent (B) uses only an acid anhydride curing agent ,
The above-mentioned (B) acid anhydride curing agent is phthalic anhydride, tetrahydrophthalic anhydride, methyltetrahydrophthalic anhydride, methyl nadic anhydride, hexahydrophthalic anhydride, methyl hexahydrophthalic anhydride, trimellitic anhydride, pyroanhydride The thermistor sensor casting epoxy resin composition which is 1 or more types selected from the group which consists of a meritic acid, a maleic anhydride, and a methyl-hydrogen anhydride anhydride .

[2] The thermistor sensor casting epoxy resin composition according to [1], wherein the component (A) is polyoxyalkylene bisphenol A diglycidyl ether.

[3] The thermistor sensor casting epoxy resin composition according to [1] or [2], further comprising (C) an inorganic filler.

The thermistor sensor using the epoxy resin composition for thermistor sensors casting in any one of [4] [1]-[3].
It consists of

  The present invention can provide a thermistor sensor casting epoxy resin composition and a thermistor sensor which are excellent in color fastness, flexibility, and fall-off prevention.

Hereinafter, embodiments of the present invention will be described in detail.
The present invention relates to an epoxy resin having a specific epoxy equivalent, an epoxy resin composition for thermistor sensor casting containing an acid anhydride, and a thermistor sensor.
Hereinafter, the thermistor sensor casting epoxy resin composition and the thermistor sensor will be described.

(Thermistor sensor casting epoxy resin composition)
The epoxy resin composition for thermistor sensor casting according to the present invention comprises (A) an epoxy resin having an epoxy equivalent of 350 or more and (B) an acid anhydride curing agent.

The component (A) used in the present invention needs to have an epoxy equivalent of 350 or more. By setting it as this range, flexibility and falling-off prevention property can be given to the epoxy resin composition obtained. The epoxy equivalent is more preferably 450 or more.
Further, from the viewpoint of reactivity and fluidity, the epoxy equivalent is preferably 700 or less, and more preferably 600 or less.

Examples of the epoxy resin corresponding to the component (A) include polyoxyalkylene bisphenol A diglycidyl ether, bisphenol A epoxy resin, bisphenol F epoxy resin, alicyclic epoxy resin, aliphatic epoxy resin, brominated bisphenol A Type epoxy resin, phenol-novolak type or brominated novolac type epoxy resin, hydrogenated bisphenol A type or AD type epoxy resin, aliphatic epoxy resin such as propylene glycol diglycidyl ether, pentaerythritol polyglycidyl ether, aliphatic or Epoxy resin obtained from aromatic amine and epichlorohydrin, epoxy resin obtained from aliphatic or aromatic carboxylic acid epichlorohydrin, heterocyclic epoxy resin, biphenyl type epoxy resin, Etc. may be used immersion acid type epoxy resin. Only one type of these (A) components may be used, or two or more types may be used. Among these, it is preferable to contain polyoxyalkylene bisphenol A diglycidyl ether because the moisture resistance can be improved.
Moreover, you may use the epoxy resin which does not correspond to (A) component if desired, unless the objective of this invention is impaired. It is preferable that the compounding quantity is the range of 35 mass% or less of all the epoxy resins.

  An acid anhydride curing agent is used as the component (B) used in the present invention. By using the acid anhydride curing agent, it is possible to prevent discoloration of the vinyl chloride resin even when using a vinyl chloride resin as the wire covering material, and to obtain a cured product having excellent electrical characteristics. As an acid anhydride curing agent, for example, phthalic anhydride, tetrahydrophthalic anhydride, methyltetrahydrophthalic anhydride, methyl nadic anhydride, hexahydrophthalic anhydride, methyl hexahydrophthalic anhydride, trimellitic anhydride, pyromellitic anhydride Acids, maleic anhydride, hydrogenated methyl nadic acid, trialkyltetrahydrophthalic anhydride and the like can be mentioned. Only one type of these (B) components may be used, or two or more types may be used. If these acid anhydride curing agents become liquid as a whole of the acid anhydride, those which are solid at normal temperature can be used. Among them, methyltetrahydrophthalic anhydride is preferable in view of low viscosity and easy availability.

  The compounding ratio of the component (B) used in the present invention is the functional group 1 contained in the entire epoxy resin which does not correspond to the component (A) or the component (A) and the component (A) optionally added. The lower limit of the equivalent ratio of the functional groups in the curing agent to the equivalent is preferably 0.6 or more, and more preferably 0.8 or more. The upper limit of the equivalent ratio of functional groups in the curing agent is preferably 1.1 equivalents or less, and more preferably 1.0 equivalents or less. By setting this range, it is possible to prevent insufficient curing and to improve the anti-falling property.

In the present invention, an inorganic filler may be further contained as component (C). Thermal conductivity can be improved by containing the component (C).
As the component (C), conventionally known inorganic fillers can be appropriately used. For example, it is possible to use fused silica, crystalline silica, metal hydroxides such as alumina and aluminum hydroxide, calcium carbonate, calcium silicate, mica, talc, clay, titanium white, silicon nitride, boron nitride, silicon carbide and the like. it can.
Among these (C) components, alumina, aluminum nitride, silicon nitride and boron nitride are preferable because of their high thermal conductivity.
Only one type of these (C) components may be used, or two or more types may be used.

  The lower limit of the average particle size of the component (C) is preferably 1 μm or more, and more preferably 2 μm. The upper limit of the average particle size of the component (C) is preferably 10 μm or less, and more preferably 8 μm. By setting it as this range, it can prevent that (C) component precipitates. There is no limitation on the shape, and any shape such as spherical, needle-like, indeterminate or scaly may be used. The average particle size refers to the particle size at which the cumulative volume is 50% in the cumulative distribution of the particle sizes of the component (C) obtained using the laser diffraction particle size distribution measuring device.

  It is preferable that it is 100 mass parts with respect to 100 mass parts of (A) epoxy resin, and, as for the minimum of the compounding quantity of (C) component, it is still more preferable that it is 200 mass parts. It is preferable that it is 400 mass parts with respect to 100 mass parts of (A) epoxy resins, and, as for the upper limit of the compounding quantity of (C) component, it is still more preferable that it is 300 mass parts. The fluidity of the epoxy resin composition obtained can be maintained by setting the amount of the component (C) to be in this range.

In the epoxy resin composition of the present invention, conventional auxiliary components such as a curing accelerator, a flow control agent, a flame retardant, a pigment, a coupling agent, an antifoaming agent and the like can be appropriately blended in addition to the above components.
As a curing accelerator, tertiary amines, imidazoles, dicyandiamide and the like can be mentioned.

  The viscosity of the epoxy resin composition of the present invention is preferably in the range of 100 to 10,000 mPa · s when measured at 25 ° C. and a speed of 50 rpm using a rotational viscometer. By setting the viscosity in this range, the epoxy resin composition can be easily cast in a protective case.

  It is preferable that the hardness of the hardened | cured material of the epoxy resin composition of this invention is 90 or less with a Shore hardness meter (type A). By setting it as this range, an epoxy resin composition will have flexibility. The measuring method will be described later.

  The thermal conductivity of the cured product of the epoxy resin composition of the present invention is preferably 0.5 W / (m · K) or more. By setting it as this range, the sensitivity as a thermistor sensor can be improved. The measuring method will be described later.

  The viscosity of the epoxy resin composition of the present invention and the hardness and thermal conductivity of the cured product of the epoxy resin composition depend on the kind of the component (A) and the compounding amount thereof, the kind of the component (B) and the compounding amount thereof and It can adjust with the kind of epoxy resin which does not correspond to (A) component and its compounding quantity, the kind of (C) component, its compounding quantity, etc.

(Production method)
The epoxy resin composition of the present invention is prepared by adding each of these components in any order at the time of use and mixing uniformly. If desired, a mixture of (B) an acid anhydride curing agent and an optionally added curing accelerator component is used as a second liquid, and a mixture of components other than the second liquid is previously prepared as a first liquid. It is advantageous in terms of working efficiency and the like to use the first and second liquids mixed in use.

(Thermistor sensor)
The thermistor sensor of the present invention refers to a resin-casting type thermistor sensor, and refers to one obtained by casting a thermistor sensor main body consisting of a thermistor element and an electric wire coated with an insulating coating material with a resin.
In the present invention, examples of the insulating covering material include vinyl chloride resin, crosslinked polyethylene resin, fluorine resin, polyester resin and the like.

(Method of manufacturing thermistor sensor)
In manufacturing the thermistor sensor of the present invention, the thermistor element main body is inserted into the protective case in which the epoxy resin composition for casting the thermistor sensor of the present invention is injected in advance, and then the epoxy resin composition for casting the thermistor sensor The epoxy resin composition may be injected and cured after the thermistor element body is inserted into the protective case. The curing conditions may be appropriately set according to the material of the insulating covering material, and in the case of a vinyl chloride resin, it is preferable that the temperature range of 100 to 105 ° C. is about 5 to 10 hours.

  Examples of applications of the thermistor sensor of the present invention include a temperature sensor for a refrigerant of a car air conditioner, a detection sensor for a cooling water temperature, a temperature detection sensor for a food processing machine and a cooking device, and a temperature sensor for an air conditioner for home appliances.

The following will specifically explain the thermistor sensor casting epoxy resin composition and the thermistor sensor of the present invention with reference to Examples, but the thermistor sensor casting epoxy resin composition and the thermistor sensor of the present invention may be embodied as such. It is not limited by the example.
In addition, flexibility, moisture resistance, and thermal conductivity are evaluated as evaluations of the epoxy resin composition for casting the thermistor sensor (hereinafter referred to as a sample) of the example and the comparative example. The drop prevention performance was evaluated.

(Flexibility)
The sample was placed in a cylindrical container having a diameter of 50 mm and a height of 3 mm, and subjected to heat curing at 100 ° C. for 5 hours, which was taken out as a test piece. The hardness of this test piece was measured according to JIS K-7215 using a Shore hardness tester (type A). The results are shown in Tables 1 and 2.

(Moisture resistance)
The sample was placed in a cylindrical container having a diameter of 50 mm and a height of 3 mm, and subjected to heat curing at 100 ° C. for 5 hours, which was taken out as a test piece. The surface condition of this test piece after 96 hours elapsed in an environment of 150 ° C., humidity 98%, 5 atm was evaluated by visual and palpation according to the following criteria.
○: There is no eluate on the surface of the test piece and no stickiness.
Δ: There is no eluted material on the surface of the test piece, but the edge is sticky.
×: There is eluted material on the surface of the test piece or it is sticky.

(Thermal conductivity)
The sample was placed in a container subjected to a release treatment, heat-cured at 100 ° C. for 5 hours, taken out, and then cut into 100 × 50 × 6 mm to obtain a test piece. The thermal conductivity was measured by a probe method using a rapid thermal conductivity meter (manufactured by Kyoto Denshi Kogyo Co., Ltd.). The results are shown in Tables 1 and 2.

(Color resistance)
A sample and a wire coated with a vinyl chloride resin were placed in a copper cylindrical container having a diameter of 15 mm and a height of 30 mm, and heat cured at 100 ° C. for 5 hours to obtain a test piece. The test piece was heated in a 105 ° C. environment for 100 hours, and the color change of the wire was visually evaluated according to the following criteria.
○: no discoloration ×: discoloration

(Anti-dropout)
The sample and a wire coated with a vinyl chloride resin were put in a cylindrical protective case made of copper and having a diameter of 15 mm and a height of 30 mm, and heat cured at 100 ° C. for 5 hours to obtain a test piece. After holding the test piece at -196 ° C for 1 minute, a heat cycle test was performed in which the treatment of holding at 130 ° C for 1 minute was one cycle. The wire was pulled for each cycle, and the number of cycles in which the wire dropped from the protective case was taken as the test result.

Example 1
Each component constituting the composition of the present invention is blended at a ratio (parts by mass) shown in Table 1 and uniformly mixed to obtain a sample, the viscosity of this sample is measured, and the results are shown in Table 1. Further, this sample was cured by heating at 100 ° C. for 5 hours. It measured about the flexibility of this cured | curing material, moisture resistance, heat conductivity, discoloration resistance, drop-off prevention property. The results are shown in Table 1.

(Examples 2 to 4)
The components shown in Table 1 were uniformly mixed in the proportion (parts by mass) shown in Table 1, samples were obtained, and the viscosity was measured. The results are shown in Table 1. Further, these samples were cured under the same conditions as in Example 1 to obtain a cured product. The cured product was measured for flexibility, moisture resistance, thermal conductivity, color fastness and anti-falling property. The results are shown in Table 1.

(Comparative Examples l and 2)
The components shown in Table 2 were uniformly mixed at the proportions (parts by mass) shown in Table 2, samples were obtained, and the viscosity was measured. The results are shown in Table 2. Further, these samples were cured under the same conditions as in Example 1 to obtain a cured product. It measured about the flexibility of these hardened | cured material, thermal conductivity, discoloration resistance, and drop-off prevention property. The results are shown in Table 2.

The following compounds were used in Examples and Comparative Examples described in Tables 1 and 2.
A1: Polyoxyalkylene bisphenol A diglycidyl ether (epoxy equivalent 510 g / eq, trade name Adeka Resin EP-4005, manufactured by Adeka)
A2: Dimer acid type epoxy resin (epoxy equivalent 430 g / eq, trade name jER 871, manufactured by Mitsubishi Chemical Corporation)
828: Bisphenol A epoxy resin (epoxy equivalent 190 g / eq, trade name jER 828, manufactured by Mitsubishi Chemical Corporation)
B1: Acid anhydride curing agent (methyltetrahydrophthalic anhydride, trade name HN-2000, manufactured by Hitachi Chemical Co., Ltd.)
B2: Acid anhydride curing agent (methyl hexahydrophthalic anhydride, trade name HN-5500, manufactured by Hitachi Chemical Co., Ltd.)
C: Inorganic filler (alumina, average particle size: 2.6 μm)
Curing accelerator: 2,4,6-tris (dimethylaminomethyl) phenol amine curing agent: polyalkylene oxypolyamine, trade name Jeffamine D-400, manufactured by Mitsui Chemicals Fine Co., Ltd.

(Evaluation)
In Examples 1 to 4 in Table 1, since an epoxy resin having an epoxy equivalent of 350 or more and an acid anhydride-based curing agent are used, the resin has color resistance and hardness of 90 or less. It can be understood that it is excellent. Moreover, in Example 2, since it contains (C) component, it can also be understood that heat conductivity is improving. In Example 4, since the dimer acid type epoxy resin is used without using polyoxyalkylene bisphenol A diglycidyl ether, it can be understood that the moisture resistance is slightly inferior.
On the other hand, in Comparative Example 1 in Table 2, since an amine curing agent is used, it can be understood that the color fastness is not satisfactory. In Comparative Example 2, since it is an epoxy resin having a low epoxy equivalent, its hardness is high and inferior in flexibility as compared with the case of Example 2 containing an inorganic filler, and it is extremely inferior also in falling-off prevention property It can be understood that

Claims (4)

A thermistor sensor casting epoxy resin composition used by casting between a protective case and a thermistor sensor body comprising a thermistor element and an electric wire coated with an insulating coating material, wherein the thermistor sensor casting epoxy The resin composition contains (A) an epoxy resin having an epoxy equivalent of 350 or more and a curing agent ,
The curing agent contains only (B) an acid anhydride curing agent ,
The above-mentioned (B) acid anhydride curing agent is phthalic anhydride, tetrahydrophthalic anhydride, methyltetrahydrophthalic anhydride, methyl nadic anhydride, hexahydrophthalic anhydride, methyl hexahydrophthalic anhydride, trimellitic anhydride, pyroanhydride The thermistor sensor casting epoxy resin composition which is 1 or more types selected from the group which consists of a meritic acid, a maleic anhydride, and a methyl-hydrogen anhydride anhydride . The thermistor sensor casting epoxy resin composition according to claim 1, wherein the component (A) is polyoxyalkylene bisphenol A diglycidyl ether. The thermistor sensor casting epoxy resin composition according to claim 1, further comprising (C) an inorganic filler. Thermistor sensor using the epoxy resin composition for thermistor sensor casting as described in any one of Claims 1-3.