JPH04367B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a heat-sensitive element used to control the temperature of heating appliances such as electric blankets and electric carpets. More specifically, the present invention relates to a novel polymeric thermosensitive material that has high temperature detection sensitivity even at high frequencies and whose characteristics change little due to moisture absorption. It has been well known for a long time to utilize the temperature dependence of the electrical properties of polymeric materials to use them as temperature sensors, that is, heat-sensitive elements, as seen in the case of electric blankets and electric carpets. ing. In these heating appliances, any one of the properties of the polymeric material incorporated in the circuit as a temperature sensor, such as the dielectric constant, DC resistance, and impedance, or a combination of two or more properties, is selected as the control factor, and these The temperature control circuit operates by taking advantage of the fact that the characteristics of The properties required of such heat-sensitive element materials include (1) the electrical properties of the polymer change greatly with temperature, especially when alternating current is applied;
The electrical properties have a large temperature dependence even in the high frequency range of 1000Hz or higher, (2) the electrical properties change little due to moisture absorption, and (3) it has excellent heat resistance. In general, polyamides have electrical properties that are highly temperature dependent, and are also excellent in heat resistance, mechanical properties, and moldability.
Compositions containing electrical property improvers such as alkali metal halides are in practical use as suitable heat-sensitive element materials. However, among polyamides, even nylon 11 and nylon 12, which have a low amide group concentration and relatively low hygroscopicity, cannot avoid the effects of moisture absorption. There is a need for new materials that can exhibit temperature sensing functions. There have been several studies on such heat-sensitive element materials with low moisture absorption and high sensitivity.
54-37640), a method using N-substituted nylon (for example, JP-A-55-128202), a method using polyether ester amide (for example, JP-A-57-76054), higher polyamide and modified polyolefin. A method using a blend of
48-1438), etc.
However, as the circuits of heating appliances that use heat-sensitive elements become more diverse, the demand for lower moisture absorption becomes stronger, and as high-frequency alternating current of 1000 Hz or higher is applied to control circuits, Sensitivity is also required, and the reality is that conventional materials cannot satisfy all of these requirements. Therefore, the present inventors conducted intensive studies to obtain a highly sensitive heat-sensitive element material that has even lower hygroscopicity than conventional materials and whose electrical properties have a large temperature dependence even in the high frequency range of 1000 Hz or higher.As a result, (A)
A heat-sensitive element made of a resin composition obtained by mixing a specific aliphatic polyester amide, (B) a specific modified polyolefin and/or polybutylene terephthalate, and (C) an electrical property improver satisfies the above required properties. The present invention was achieved by discovering that the present invention is possible. That is, the present invention comprises (A) (a) 90 to 60% by weight of polyamide units represented by the following formula () and (b) 10 to 40% by weight of polyester units represented by the following formula () and/or (). (B) a modified polyolefin having at least one functional group selected from a carboxylic acid group, a carboxylic acid metal base, a carboxylic acid ester group, an acid anhydride group, and an epoxy group; or polybutylene terephthalate (PBT)
5 to 40 parts by weight, and (C) 0.01 to 5 parts by weight of at least one selected from copper halides, complex salts of copper halides, alkali metal halides, and surfactants.
The object of the present invention is to provide a high-performance heat-sensitive element comprising a resin composition obtained by mixing parts by weight. (Here, k is 10 or 11, m is 3 to 11, and n is 4.
an integer of 10 to 10; R represents a divalent aliphatic or alicyclic group; ) The heat-sensitive element of the present invention is essentially composed of polyester amide, which has low hygroscopicity, and modified polyolefin and/or PBT, which also has little hygroscopicity, so it has a higher temperature than heat-sensitive elements made of conventionally known materials. It absorbs only a small amount of moisture and exhibits a stable temperature control function with little variation in electrical characteristics due to moisture absorption. In addition, by combining specified polyesteramide, modified polyolefin and/or PBT, and an electrical property improver, the dispersibility of the electrical property improver is good and the effect of improving electrical properties is large, and the electrical properties are improved even in the high frequency region of 1000Hz or higher. It is possible to obtain a heat-sensitive element with high practical value and extremely high temperature dependence. The polyesteramide (A) used in the present invention is a copolymer obtained by copolymerizing a polyamide-forming component and a polyester-forming component. The polyamide unit (a) constituting this polyesteramide is an undecane amide unit or a dodecan amide unit represented by the above-mentioned formula (), and each is derived from the corresponding amino acid or lactam. On the other hand, among the polyester units (b), those represented by the formula () are:
It is derived from lactones, and examples of monomer raw materials include butyrolactone, caprolactone, etc. In addition, as the diol component forming the polyester unit represented by the formula (), ethylene glycol, 1,3-propanediol, 2,2-dimethyl-1,3-propanediol, 1,4-butanediol, 1,5- Pentanediol, 1,6-hexanediol, 1,4
Examples of dicarboxylic acids include adipic acid, azelaic acid, sebacic acid, and dodecanedioic acid. A typical method for producing the polyester amide of the present invention includes a method in which an amino acid or lactam as a raw material for the amide component, a lactone or diol as an ester component, and a dicarboxylic acid are mixed, and the mixture is subjected to heat-reduced compression polymerization in the presence of a catalyst. However, the manufacturing method is not limited to this, and for example, a method can also be adopted in which one or both of the amide component and the ester component is made into an oligomer having an appropriate molecular weight, and then this is used as a raw material. The copolymerization ratio of polyesteramide is (a) 90 to 60% by weight of polyamide units
On the other hand, (b) 10 to 40% by weight of polyester units is appropriate; if the polyester units are less than 10% by weight, the effect of reducing moisture absorption is insufficient, while if it exceeds 40% by weight, The melting point of the polymer becomes too low and lacks practical heat resistance. There are no particular restrictions on the degree of polymerization of the above polyesteramide, and the relative viscosity of orthochlorophenol (0.5 g of polymer is mixed with 100 ml of orthochlorophenol).
(measured at 25°C) of 1.2 to 2.5 can be used. One of the (B) components used in the present invention
PBT is obtained by polycondensing 1,4-butanediol with terephthalic acid and terephthalic acid derivatives by a commonly known method, and the degree of polymerization is not particularly limited, and the relative viscosity of orthochlorophenol is 1.2 to 2.5.
can be used. (B) A modified polyolefin having at least one functional group selected from a carboxylic acid group, a carboxylic acid metal base, a carboxylic ester group, an acid anhydride group, and an epoxy group belonging to another category of component Representative examples include ethylene/acrylic acid copolymer, ethylene/methacrylic acid copolymer, ethylene/fumaric acid copolymer, ethylene/methacrylic acid, zinc methacrylate copolymer, ethylene/acrylic acid /
Sodium methacrylate copolymer, ethylene/
Isobutyl acrylate/methacrylic acid/zinc methacrylate copolymer, ethylene/methyl methacrylate/methacrylic acid/magnesium methacrylate copolymer, ethylene/ethyl acrylate copolymer, ethylene/vinyl acetate copolymer copolymer, ethylene/glycidyl methacrylate copolymer, ethylene/vinyl acetate/glycidyl methacrylate copolymer, ethylene-g-maleic anhydride copolymer (“g” represents graft, the same applies hereinafter), ethylene/ propylene-g-maleic anhydride copolymer,
Ethylene/propylene-g-acrylic acid copolymer, ethylene/1-butene-g-fumaric acid copolymer, ethylene/1-hexene-g-itaconic acid copolymer, ethylene/propylene-g-endobicyclo[2 , 2,1]-5-heptene-2,3-dicarboxylic anhydride copolymer, ethylene/propylene-g-glycidyl methacrylate copolymer, ethylene/propylene/1,4-hexadiene-g-
Maleic anhydride copolymer, ethylene/propylene/dicyclopentadiene-g-fumaric acid copolymer, ethylene/propylene/norbornadiene-
Examples include g-maleic acid copolymer and ethylene/vinyl acetate-g-acrylic acid copolymer, and it is also possible to use two or more of these modified polyolefins in combination. The above-mentioned modified polyolefin can be produced by a known method.
For example, Special Publication No. 39-6810, Special Publication No. 46-
Publication No. 27527, Special Publication No. 1972-2630, Special Publication No. 1972
-43677 Publication, Special Publication No. 53-5716, Special Publication Sho
It can be produced according to the method disclosed in Japanese Patent Publication No. 53-19037, Japanese Patent Publication No. 53-41173, Japanese Patent Publication No. 56-9925, etc. As for the ethylene ionomer, various grades commercially available under the trade names of "Surlyn,""Hylamin," and "Copolene" can be used. The degree of polymerization of the modified polyolefin used in the present invention is not particularly limited, but usually has a melt index of 0.01 to 50.
You can arbitrarily select anything within the g/10min range. In addition, in the present invention, it is also possible to mix a small amount of other polyolefins with the above-mentioned modified polyolefin, and the polyolefins include polyethylene, polypropylene, ethylene/propylene copolymer, ethylene/butene-1 copolymer, ethylene/propylene/ Dicyclopentadiene copolymer, ethylene/propylene/5-ethylidene norbornene copolymer and ethylene/propylene/
A 1,4-hexane diene copolymer or the like can be used. The mixing ratio of (A) polyesteramide and (B) modified polyolefin and/or PBT is 95:5 to 60:40
(weight ratio) is preferably within the range. If the polyesteramide content exceeds 95 parts by weight, the moisture resistance of the polymer will decrease, which is undesirable.On the other hand, if the polyesteramide content is less than 60 parts by weight, components (A) and (B) may not be compatible. It has low solubility and cannot withstand normal extrusion molding. Examples of the electrical property improving additive (C) used in the present invention include halogenated additives such as cuprous chloride, cupric chloride, cuprous bromide, cupric bromide, and cuprous iodide. Copper, complex salts of these copper halides with organic compounds such as xylylene diamine, 2-mercaptobenzimidazole, benzimidazole, potassium iodide, sodium iodide, lithium fluoride,
Alkali metal halides such as lithium chloride,
Alkylamide type polyoxyethylene glycol type nonionic surfactant, phosphate ester type nonionic surfactant, sorbitan ester type nonionic surfactant, imidazoline type amphoteric surfactant, amidoamine type carboxylate type amphoteric surfactant Surfactants such as sorbitan, mannitrate, or combinations of ethylene oxide adducts thereof and quaternary ammonium halide salts such as tetradecyldimethylbenzylammonium chloride, esters such as dialkyl phthalates, and tricresyl phosphates. Combinations of system compounds and quaternary ammonium halide salts such as tetrabutylammonium bromide, dioctyl mono[(2-methyl-3-benzyl-3-chloroimidazonyl)methyl cophosphate, 1-poly(ethylene glycol terephthalate)- 2-methyl-
These include imidazole derivatives such as 3-benzyl-imidazolium chloride. These additives can be used alone or in combination. The appropriate amount of the electrical property improver is 0.01 to 5 parts by weight per 100 parts by weight of the base polymer, and 0.01 to 5 parts by weight.
If it is less than part by weight, the effect of improving electrical properties will not be sufficient;
On the other hand, if the amount exceeds 5 parts by weight, problems such as poor dispersion and bleed-out of the electrical property improving agent will become apparent, making it unsuitable. There are no particular restrictions on the method of mixing (A) polyesteramide, (B) modified polyolefin and/or PBT, and (C) electrical property improver. A method of dry blending using a Henschel mixer or the like, and then melt-kneading with an extruder, the polyester amide, either one of the polymers of component (B) and the electrical property improver are melt-kneaded in advance, and then the remaining polymer and An appropriate method can be selected from among a method of melt-kneading again, a method of adding an electrical property improver during polymerization of the polyesteramide, and a method of melt-kneading the obtained polymer and the polymer of component (B). The resin composition of the present invention may contain antioxidants, thermal decomposition stabilizers, light stabilizers, hydrolysis resistance improvers, colorants, etc. during polymerization or after polymerization and before molding, as long as the mechanical properties and electrical properties are not impaired. Flame retardants, various molding aids, etc. can be used as appropriate. Supply the above resin composition to a normal extruder etc.
By molding it into the shape of a heating wire or sheet, it can be made into a heat-sensitive element. The present invention will be described in more detail with reference to Examples below. Evaluation of various properties in Examples and Comparative Examples was performed as follows. (1) Relative viscosity of solution: Relative viscosity at 25°C of a solution of 0.5 g of polymer dissolved in 100 ml of orthochlorophenol. (2) Melting point: Melting peak temperature measured using a Parkin-Elmer DSC-1B differential calorimeter at a heating rate of 20°C/min. (3) Moisture absorption rate: Calculated from the weight increase when the polymer was placed in an atmosphere of 25°C and 65% RH and the equilibrium weight was reached. (4) Thermistor characteristics: After drying the resin composition, a sheet with a thickness of about 0.2 mm is formed by melt pressing, and conductive paint is applied circularly on both sides of this sheet to form an electrode. After measuring the AC resistance at the frequency, the volume specific impedance (Zsp) was calculated from the electrode area and sheet thickness. 50
The Bz constant, which is a parameter of thermistor characteristics, was calculated from the volume specific impedance at ℃ and 110℃ according to the following formula. The larger this value is, the more sensitive the thermal element becomes. Bz=lnZsp( _T1 )/Zsp( _T2 )/1/ _T1-1 / _{T2 T1} : 323K _T2 : 383K Example 1 87.3 parts by weight of 12-aminododecanoic acid, 16.2 parts by weight of dodecanedioic acid, A mixture of 11.4 parts by weight of 1,4-butanediol and an esterification catalyst was reacted by heating at a temperature of 230°C for 3 hours under _N2 range, then a polymerization catalyst was added, and the reaction was carried out at 250°C for about 1 hour at a temperature of 1 Torr or less. By carrying out the polymerization reaction for about 2 hours, a polyesteramide was obtained in which the weight ratio of the polyamide (N-12) part and the polyester (PBD) part was 80:20, the relative viscosity was 1.65, and the melting point was 157°C. Ta. Next, 70 parts by weight of this polyesteramide, 30 parts by weight of PBT resin (Toray Industries, Inc. PBT1100) and 0.3 parts by weight of sodium iodide were mixed in a Henschel mixer, and then melt-kneaded at 250°C in an extruder to obtain a product. A sheet with a thickness of 0.2 mm is created from the resin composition, its volume specific impedance is determined, and 50
The Bz constant at ~110°C was calculated, and the moisture absorption rate of the resin composition was measured, and the results shown in Table 1 were obtained. The heat-sensitive element obtained here was found to be extremely high-performance with good sensitivity and low hygroscopicity. Examples 2 to 5 Resin compositions obtained in exactly the same manner as in Example 1 except for changing the type and amount of the electrical property improver.
The Bz constant and moisture absorption rate are shown in Table 1. All of these heat-sensitive elements were found to be excellent, having low hygroscopicity and high sensitivity. Examples 6 to 8 Polyesteramide obtained by polymerizing a mixture of 11-aminoundecanoic acid, dodecanedioic acid and 1,4-butanediol in the same manner as in Example 1 (N-11/PBD = 75/25 wt% , relative viscosity 1.68, melting point 161°C) 80 parts by weight, ionomer resin consisting of ethylene/methacrylic acid/zinc methacrylate copolymer (Mitsui Polychemical Co., Ltd. "Himiran")
1706) The Bz constant and moisture absorption rate of the resin composition obtained by melt-kneading 20 parts by weight and some electrical property improvers were measured in the same manner as in Example 1, and the results shown in Table 1 were obtained. Ta. The heat-sensitive element obtained here was also found to have good sensitivity, low moisture absorption, and high reliability. Comparative Example 1 Polyesteramide obtained in Example 1 (N-
The Bz constant and moisture absorption amount of the resin composition obtained by melt-kneading 100 parts by weight of 12/PBD=80/20wt%) and 0.3 parts by weight of sodium iodide were determined, and the results are shown in Table 1. The heat-sensitive element obtained here had a high moisture absorption rate and had insufficient properties. Comparative Example 2 Table 1 shows the Bz constant and moisture absorption rate of a polyesteramide/PBT:7030 resin composition obtained in exactly the same manner as in Example 1 except that no electrical property improver was added. The heat-sensitive element obtained here had a small Bz constant and insufficient sensitivity. Comparative example 3 80 parts by weight of nylon 12 resin (Toray Industries, Inc. CM5051F),
20 parts by weight of ionomer resin (Mitsui Polychemical Co., Ltd. “Himilan” 1706) and 0.4 parts by weight of potassium iodide
The characteristics of the heat-sensitive element consisting of the mixture of parts by weight are determined as follows:
It is listed in the table. This heat-sensitive element also had insufficient moisture resistance.

【table】 /
complex 4) 〓C ₇ H ₁₅ CONHCH ₂ CH ₂ N
〓 − ₂ Zn 5) Composition ratio of N−12 and 〓HIMILAN〓 1706

\
CH ₂ COO

Claims (1)

[Scope of Claims] 1 (A) (a) 90 to 60% by weight of polyamide units represented by the following formula () and (b) the following formula () and/or
or 10 polyester units represented by the formula ()
Polyesteramide composed of ~40% by weight
95 to 60 parts by weight, (B) modified polyolefin and/or polybutylene terephthalate having at least one functional group selected from carboxylic acid groups, carboxylic acid metal bases, carboxylic ester groups, acid anhydride groups and epoxy groups ( PBT) 5 to 40 parts by weight and (C) 0.01 to 5 parts by weight of at least one selected from copper halides, complex salts of copper halides, alkali metal halides, and surfactants. A heat-sensitive element comprising the obtained resin composition. (Here, k is 10 or 11, m is 3 to 11, n is an integer of 4 to 10, and R represents a divalent aliphatic or alicyclic group.)