JPH04500745A - electric heater - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] conductive polymer composition Background of the invention Industrial applications The present invention provides electrically conductive polymer compositions and electricity using the electrically conductive polymer compositions. Regarding equipment.

- and electrical devices such as circuit protection devices are known. For example, something like can be referenced. United States Patent No. 3.793.716.3.823,217 ．． 3,858,144.3.861.029.3.914.363.4,017 ,715.4,177.376.4.188.276.4.237.441.4 , 242.573.4.246.468.4.286.376.4, 304.9 87.4.318.881.4.330.703.4.334.148.4.3 34.351.4.388.607.4.400.614.4.425.497 ．． 4.426.339.4, 435.639.4.459, 473.4.514 ,620.4,520.417.4,529,866.4,534.889.4 , 543,474.4.545.926.4.547.659.4, 560.4 98.4.571.481.4, 574, 188.4, 582.983.4, 6 31.392.4,638,150.4.654.511.4,658,121 ．． 4,659,913.4.661,687.4,667.194.4,673 , 801.4, 698.583.4, 719, 335.4.722.758 and and 4.761.541, as well as European Patent Application Publication No. 38,718 (F). Oora et al., published October 28, 1981), 158.410 (Batriwala et al. , published October 16, 1985) and No. 231.068 (Verma et al., 198 (Released on August 5, 2009).

Conductive polymer compositions exhibiting PTC (Positive Temperature Coefficient Resistance) behavior are particularly suitable for self-regulating speeds. Useful in trip heaters and circuit protectors.

These appliances have a PTC property, i.e. an abnormally rapid increase in resistance as a function of temperature. It is used to limit the heat generated by the heater or the current flowing through the circuit. P Many compositions exhibit TC properties and contain carbon black as a conductive filler. Disclosed in the references. U.S. Patent No. 4,237,441 (Co. Ninenburg et al.) is used for PTC compositions with resistivities less than 7 ohms/0 m. discloses carbon black suitable for. United States Patent No. 4°388 ．． No. 607 (Toy et al.) describes a carton suitable for use in compositions for strip heaters. Disclosing bomb black. United States Patent No. 4.277.673 (K. Lee) discloses self-regulating articles using high-resistivity carbon black. child These carbon blacks can be used alone or in combination with low resistivity carbon blacks. to form a PTC composition that significantly shortens annealing time.

Many carbon blacks are suitable for use in conductive compositions, as shown in Ref. suitable for The selection of a particular carbon black depends on the physical properties of the carbon black. and electrical properties as well as the desired properties of the resulting composition, such as flexibility or conductivity. Depends on gender. The properties of carbon black are determined by particle size, surface area, structure and is influenced by factors such as surface chemistry. This chemical property is e.g. by thermal or chemical treatment during the manufacture of blanks or in post-manufacturing processes. For example, it changes due to oxidation. The surface pH value of oxidized carbon black is low ( i.e. less than 5.0) and may have a relatively high volatile content.Similar particles Oxidized carbon when compared to non-oxidized carbon black in dimensions and structure Black has high resistivity. The oxidized carbon blank reduces the flow of printing ink. Improved dynamics, improved wettability of certain polymers, and improved rubber strength. This is known.

Summary of the invention The present inventors found that when the conductive filler comprises carbon black with a low pH, We have discovered that it is possible to produce conductive polymer compositions with improved thermal stability. Ta. The inventors have found that using such carbon blacks, similar non-oxidized to compensate for the composition's higher resistivity when compared to dark carbon black. Even when more highly reinforced due to increased filler content, PT It was found that the C property increased. Accordingly, according to one aspect, the present invention provides: (1) exhibits PTC behavior and has a resistivity R− at 20°C; (a) at least 5% an organic polymer having crystallinity and melting point T, and (b) a conductive polymer comprising carbon black having a pH of less than 4.0; (2) a PTC element that is capable of being connected to a power source to provide electrical current to the PTC element; An electrical appliance comprising two electrodes that allow current to flow, With resistance R1 at 20°C, the apparatus is kept at a temperature equal to T, for 50 hours, and then When the temperature is cooled to 20℃, the resistance RISO at 20℃ is 0.25R, ~ We provide electrical appliances with a capacity of 175R□.

In determining suitable fillers for use in the compositions of the present invention, we It has been found that the physical and electrical properties of black can be used. Therefore, the second According to the gist of the present invention, the present invention exhibits PTC behavior; (1) an organic polymer having a crystallinity and melting aTm of at least 5%, and (2) pH less than 4.0, particle size in D (nanometers) and (Rc, /D) Carbon black having a dry resistivity RcIl of 0.1 or less A conductive polymer composition comprising:

Detailed description of the invention Carbon black useful in the conductive polymer compositions of the present invention preferably has a carbon black of less than 5° or have a pH of less than 4.0, especially less than 3.0. pH is carbon black A measure of the acidity or alkalinity of a surface. pH 7.0 is chemically neutral table A value below 7.0 means acidic, and a value higher than 7.0 means basicity. p Carbon black with a low H value generally has a fairly high volatile content; is an indicator of the amount of chemically adsorbed oxygen present on the surface of carbon black. . The amount of oxygen can be increased by oxidation during post-manufacturing processes.

The resulting carbon black has higher surface activity. In this specification, “low "pH carbon black" and "oxidized carbon black" The terms shall be used as synonymous terms. The pH of carbon black is was measured before mixing with the polymer.

The low pH carbon black of the present invention can be used within a useful temperature range when connected to a power source. It is used in conductive polymer compositions that exhibit PTC (Positive Temperature Coefficient) behavior.

The terms "rPTC behavior" and "compositions exhibiting rPTc behavior" are used herein to refer to and an RI4 value of at least 2.5 or an R7° of at least 10. value, preference or both, especially compositions having an R3° value of at least 6. means. where R14 is the ratio of resistivity at the end and beginning of the 14°C range; R,oo is the ratio of resistivity at the end of the 100°C range and at the beginning, and R8° is the resistivity at the end of the 100°C range. It is the ratio of the resistivity at the end and the beginning of the circle. In contrast, the ``rZTC behavior'' up to 6 times, preferably 2 times, in any 30°C temperature range within the operating temperature range of It means a composition that exhibits the following resistivity increase:

PTC compositions having dimensions, surface areas and structures suitable for use in PTC compositions is known. Guidelines for selecting such carbon blacks are provided by the United States Patents No. 4.237.441 (Koninenburg et al.) and No. 4.388.607 No. (Toy et al.). Generally, it is quite large, e.g. 18 nm or more. Particle size D (in 2 nanometers) and quite high, e.g. about 70 cc/1 Carbon blacks having a structure of 00 g or more are preferred for PTC compositions.

A particularly preferred carbon blank for the composition of the invention is a carbon blank. The ratio of resistivity (powder) to particle size (unit: nanometer) is 01 or less, It satisfies the criterion of preferably 0.09 or less, particularly 0.08 or less. mosquito -Bon blank resistance $ (ohm cm) is from Columbian Chemicals Kan. Punny Guide [The Dry Resistance of Carbon Blacks] ” (Columbian Chemicals Company bullet in “The Dry Re5istivity of Carbon Bla cks") (AD 1078). It will be done. In this test, a 3 gram carbon blank was inserted into two brass plans. Place in a glass tube between jars.

A 5 kg weight is used to compress the carbon black. compressed carbon Record both the height of the black and the resistance (in ohms) between the brass plunger electrodes. , calculate the resistivity. This ratio is for carbs that are tested in powder form rather than pellets. Can be used with respect to Most unoxidized carbon black has this ratio However, carbon blacks particularly useful in the present invention satisfy this ratio. and has a pH of less than 5.0.

Other conductive fillers can be used in combination with certain carbon blacks. . These fillers include non-oxidized carbon black, graphite, metal, and metal oxidized consisting of things or a combination of these. Non-oxidized carbon black, i.e. less If carbon black with a pH of at least 5.0 is present, this non-oxidized carbon The pH of the carbon black is at least 1.0 points lower than the pH of the oxidized carbon black. It is preferable that the H unit is larger. Low pH carbon black has less overall conductive filler at least 5% by weight, preferably at least 10% by weight, especially at least 20% by weight e.g. 20-100% by weight of the total conductive filler. is preferable. In most compositions of the invention, the low pH carbon black is at least 4%, preferably at least 6%, especially at least It is also 8% by weight. In compositions containing inks, the presence of solvents is ignored and the solid The content of body components, e.g. carbon black and polymers, is taken into account as a whole composition. It will be done.

Commercially available carbon blacks with low pH values may also be used. Or non-oxidized The carbon black is treated with heat or a suitable oxidizing agent to obtain a suitable surface. Carbon black with chemical properties can be produced.

The conductive polymer composition contains at least 5%, preferably less (both 10% and especially comprising an organic polymer having a crystallinity of at least 15%, such as 20-30%; Become. Suitable crystalline polymers are polymers of one or more olefins, especially polyesters. Tylene: polyalkenamer such as polyoctenamer; at least one olefin A copolymer of at least one monomer copolymerizable therewith, such as ethylene. Coatings of ethylene/acrylic acid, ethylene/ethyl acrylate and ethylene/vinyl acetate Polymer: Melt-formable fluoropolymer, e.g. polyvinylidene fluorite ethylene/tetrafluoroethylene copolymer, and vinylidene fluora Terpolymer of hydride/hexafluoropropylene/tetrafluoroethylene; and mixtures of two or more such polymers. (This specification The term "fluoropolymer" as used in is a polymer containing at least 25% by weight of fluorine, or two or more such means a mixture of polymers. ) specific physical or thermal To achieve these properties, one crystalline polymer must be combined with another (crystalline) polymer. (either crystalline or amorphous). 2 in the composition If more than one species of polymer is present, the crystallinity of the blend must be at least 5%. do not have. The crystallinity and melting point T are determined by DSC (differential scanning calorimetry) of the conductive polymer composite acid. cT, determined from the trace (cT), is defined as the temperature at the peak of the melting curve. Ru. When the composition consists of a blend of two or more polymers, 'r5 the lowest melting point measured for (often corresponding to the melting point of the lowest melting component) and It is defined as

The composition may contain additional ingredients such as inert fillers, antioxidants, flame retardants, prorad, It may also contain stabilizers and dispersants. Mixing can be done by any suitable demi-method, e.g. This can be done by processing, filling, solvent blending, etc. Solvent v/t method is a conductive This is particularly preferred when the polymeric composition forms a polymeric plate/top. Composition may be administered by irradiation or chemical means.

Conductor iI of the present invention! acid;=, electrical appliances, such as heaters, sensors or circuits; Used in PTC elements as a component of road protection equipment.

The resistivity of the composition depends on the functionality of the appliance, the dimensions of the PTC element, and the power source that should be used. Depends on. Resistivity is, for example, a circuit powered by a voltage between 15 and 600 volts. For road protection equipment, the voltage is 0.01 to 100 ohm cm and 5 to 60 volts. For powered heaters 170-1000 ohm-cm or less 1000-1 for heaters powered with a voltage of at least 110 volts 0000 or more. Is there a PTC element that meets the requirements of the application? It may also be in the form of Circuit protectors and layered heaters have layered PTC elements. Strip heaters can be rectangular, oval or dazzling, although often It may be in the shape of a dog bone. Conductive polymer composition forms ink If the PTC element is screen printed or painted in any suitable shape. You can use cloth. The appropriate electrodes suitable for connecting to the power supply depend on the shape of the PTC element. selected. The electrodes can be made of gold, for example for attachment to or embedding in PTC elements. It may consist of metal wire or braid, or it may consist of metal wire, metal wire, conductive wire, etc. (e.g. metal-filled or carbon-filled) paint, or any other suitable It may be made of materials.

The appliance of the present invention exhibits improved stability under thermal aging and electrical stress.

measured after aging if the instrument was kept at a temperature equal to T, for 50 hours. The resistance at 20°C, i.e. RI50, is 75% or more of the initial resistance at 20°C, i.e. R5. The difference is preferably 60% or less, especially 50% or less, and R+50 is 0.25R, ~1.75R, preferably 0.4OR, ~1.6OR, especially 0.5OR, ~ It becomes 1.5OR+. When a similar test was conducted for 300 hours, the change in resistance was 5 0% or less, preferably 40% or less, especially 30% or less, at 20°C after 300 hours. resistance, R+3°. is 0.5OR, ~1.50R1, preferably 0°6OR1~ 1.4OR, especially 0.7OR to 1.3OR. Tested at a higher temperature than T. T, if the instrument meets the resistance requirement when tested.

It is considered that the requirements would also be met if tested with by applying voltage to the appliance. Similar results can be seen with effective power supply. A change in resistance is an increase in the resistance of the instrument. Reflects an increase or decrease. During the test, the resistance may initially decrease and then increase. , which reflects mechanically induced stress relaxation and subsequent oxidation of the polymer. There is a possibility that it is. Particularly preferred compositions comprising fluoropolymers have a resistance to shows better stability than a 30% change in temperature.

The invention is illustrated by the following examples.

Examples 1 to 10 For each example, a given weight % (solids content) of the appropriate carbon black was added to dimethic acid. The ink was prepared by blending with formamide in a high shear mixer.

The solution was then filtered and an amount of powdered Kyna equal to (100-% carbon black) (Kynar) 9301 (trademark) (vinylidene phthalate with a melting point of approximately 88°C) A ternary combination of fluoride, hexafluoropropylene and tetrafluoroethylene Polymer, obtained from Pennwalt) was added to the filtrate and It was allowed to dissolve for 72 hours. (Approximately 60% solvent and 40% solids to make ink) ). Silver-based ink electrode [Electrodag 4 61. S S (trademark), Acheson Co11 (obtained from oids)) is printed on ethylene-tetrafluoroethylene base Murakami, A sample of each ink was applied. 65.85.107 Samples of each ink were placed in an oven. and 21 zinc at a temperature of 149°C. Periodically, remove the sample from the oven. The resistance R1 at room temperature (nominally 20° C.) was measured. R1 is the initial room temperature resistance R The standardized resistance R9 was determined by dividing by 1. More unstable than the difference between R≧1.00 I measured the level of sexuality. Inks containing carbon black with a pH less than 5 have higher Generally more stable than inks containing carbon black with pH.

No. 1 schedule Stability of electrically conductive inks after two-seeding for 300 hours at high temperature (resistance measured at room temperature) 1 Konodacte 7x SC7, 03, 01, 221, 755, 616, 392 Raven 1500 6.0 3.0 1.01 1.92 11.88 20. 03 Raven 890 6.5 6.0 1.27 1,77 2,92 6.0 74 Raven 850 7.0 4.0 1.32 2.05 4.08 8.4 85 Raven 1000 6.0 4.0 1.18 1,43 1.94 4. 406 Raven 16 7.0 5.6 1,11 1.89' -7 Raven 5750 2. + 8.1 0,87 0.92 0,97 0.568 Rave 1040 2.8 9.1 0,96 1.15 1,47 1.349 lei Bun 1255 2.5 6.0 1.04 1.26 1.12 0.6510 Raven 14 3.0 7.0 0.82 1.00 Note (1) Fundactex and Raven are obtained from Columbian Chemicals. It is a trademark of carbon black.

(25% by weight CB indicates the weight% of carbon black used in each ink.

(3) Using the carbon blacks of Examples 1.2 and 3, ink having ZTC properties I got the key.

As a result of measuring two samples at 93°C (i.e. T, +5°C), the actual results after 50 hours were determined. R7 of Example 6' (pH=7.0) is 2.53, and R7 of Example 10 (pH=3.0) Rゎ was 1.48.

Regarding the R values of Examples 1 to 6 and Examples 7 to 10, the average of each time at the test temperature was I got even. From the results shown in Table 1I, carbon black with a higher pH value has been shown to be significantly more unstable than carbon blacks with lower pH values. Ta.

Table ■ Average R6 value Further tests were conducted on the samples of Examples 6 and 10 to determine the composition under voltage application. I wanted the stability of things. After measuring the initial room temperature resistance, the sample was placed in a ring kept at 20 or 65°C. Place in the chamber and apply the appropriate voltage to each sample to obtain the watt density. Voltage periodically The resistance of each sample was measured. Rn was calculated as described above. Table 1II As is clear from the results shown in , the sample containing oxidized carbon black is More stable than those containing oxidized carbon black.

Table ■ Rn of samples after activity test (time (hours)) Examples 11 to 14 Kynar as a binder according to the procedure of Examples 1-10. 9301 (trademark) and mixed with the carbon black listed in Table 1V. prepared. Samples of each ink were subjected to temperature cycles from 20°C to 82°C. The resistance versus temperature characteristics were measured.

By dividing the resistance at 82°C (R82) by the resistance at 20°C (R20), the PT Highly valued for its C properties. At comparable resistivity values, the PTC properties are similar to that of non-oxidized carbon. It is clear that the value is higher for oxidized carbon black than for carbon black. Ru.

1] Raven 10006.028 95 63 2.460.08g4.0 750 3.1x12 Raven 10402.828 90 99 19. 2 (10,6959,172013,0x13 Raven 450 8.062 33 67 1.360.0215. O15023x14 Raven 14 3.059 45 111 4.360.07412.0 100 42x Note: (1) D represents the particle size (nm) of carbon black.

(2) S, A, are the surface areas of carbon black measured by BET nitrogen test ( m2/g).

(3) DBP is a measure of the structure of carbon black. By measuring the amount of dibutyl phthalate (Cm”) absorbed by the rack. can be obtained.

(4) wt% represents the total solids content (weight%) of the ink, which is carbon black. vinegar.

(5) Rho is the resistivity (oharca+) of the ink.

(5) PTC height is the height of PTC properties determined by R8□/R0.

(7) Rci is the dry resistivity of carbon black in powder form under a load of 5 kg. It is.

(8) Rc1/D is the ratio of carbon black dry resistivity to particle size.

Example 15 Using a Brabender(TM) mixer, mix Kynar ( Kynar) 9301 (trademark) 85% by weight Raven 16 (Trademark) 15% by weight. [Raven 16 (trademark) has a pH of 7.0, a particle size of 61n1, a surface area of 25m2/g, and a DB. P 105cc/100g and dry resistivity 1.92. ] Beret the formulation. strand and then extruded through a strand die to a diameter of approximately 0.070 inches (0.1 A fiber of 8 cm) was obtained. Silver paint [Electrodag 50 4 (trademark) from Acheson Colloids Electrodes were applied to the fibers using the following method. The fibers were then processed according to the procedures of Examples 1-10. Tests were conducted at 85°C, 107°C, and 149°C. The results are shown in Table V. child Testing on these samples ended after 743 hours.

Example 16 Raven 14™ 20% by weight according to the procedure of Example 15 is mixed with Kynar 9301(TM) and extruded into fibers, thermally aged. According to the results shown in Table V, this oxidized carbon black is more stable with respect to aging than similar carbon blacks with higher pH. I understand that there is something. Example 1 when tested at 93°C, i.e. (T, +5)°C. The fiber of Example 5 had an R1 of 2.76 after 50 hours, and the Rゎ of the fiber of Example 16 was 1.73. there were.

Table V Rn value of extruded fiber time (hour) 85℃.

Implementation f! A115 (Ray 7) 16) 2,61 3.13 3.12 - - - Example 116 (Raibuno 14) 1,40 1.23 1,05 1. 15 1.1+ 1.16107℃・ Implementation full15 (Ray 1) 16) 3,95 4.40 101 - - 1 Example 16 (Raibuno 14) 0.78 0.98 1,12 0,80 1,16 1.05149℃: Example 115 (Raibuno 16) 27.6 137 604 - - - Real Example 116 (Ray 1) 14) 0.65 1.07 1.52 1.43 1.91 2.83 Example 17 According to the procedure of Example 15, Elvax 250 (trademark) 5 5% by weight (ethylene/vinyl acetate copolymer, melting point 60°C, from Dot) Raven 22 (trademark) 45% by weight (pH 7.0, Particle size 62r+m, surface area 25tb"/gs and DBP 113cc /100g of carbon black, Columbian Chemicals Fibers were prepared by blending (obtained from ian chemicals) did. An ink was prepared by dissolving this fiber in xylene. 813 hours at 52℃ After the test, the Rゎ value was 0.94.

Example 18 in Elvlx 250 (trademark) according to the procedure of Example 17. Fibers were first prepared using 50% by weight Raven 14™ and then dissolved in xylene. After 813 hours at 52°C, the R0 value of the ink was 0. ．． It was 88.

Example 19 PFA340 (trademark) 76% by weight (T, tetrafluoroethylene at 307°C) and perfluorovinyl ether copolymer, duPont ) and Raven 600 (trademark) 24% by weight (pH 8 ,3, particle size 55nm1DBP82cc/100g1 and surface area 34m2/ Carbon black, Columbian Chemicals Fibers were prepared as in Example 15 from A.

The R0 value of the sample tested at 311° C. for 50 hours was 0.55.

Example 20 Raven 14 (trademark) 17 weight according to the procedure of Example 19 % was used to prepare the fibers. The R value after 50 hours at 311°C was 0.93. Ta.

international search report m″″′″′bar’-PCT/US 89104010 International Search Report

Claims (1)

[Claims] 1. (1) exhibits PTC behavior and has a resistivity Rcp at 20°C; (a) at least an organic polymer with a crystallinity of 5% and a melting point Tm, and (b) a conductive polymer comprising carbon black having a pH of less than 4.0; (2) a PTC element that is capable of being connected to a power source to provide electrical current to the PTC element; An electrical appliance comprising two electrodes that allow current to flow, Having a resistance Ri at 20°C, the instrument is kept at a temperature equal to Tm for 50 hours, then When the temperature is cooled to 20℃, the resistance R150 at 20℃ is 0.25Ri~1 ．． Electric appliances that are 75Ri. 2. If the apparatus is kept at a temperature equal to Tm for 300 hours and then brought to 20°C, The electric current according to claim 1, having a resistance R1300 at 20° C. of 0.5 Ri to 1.5 Ri. Qi equipment. 3. The electric appliance according to claim 1 or 2, wherein the carbon black has a pH of less than 3.0. Ingredients. 4. 4. The electrically conductive material of claim 1, 2 or 3, wherein the electrically conductive polymer comprises a polymer thick film ink. Qi equipment. 5. Claims 1 to 4, wherein the electrical appliance is a heater or a circuit protection device. Electric appliances included. 6. The electrical appliance according to any one of claims 1 to 5, wherein the conductive polymer is crosslinked. . 7. Any of claims 1 to 6, wherein at least 4% by weight of carbon black is present. Electrical appliances listed. 8. The composition is further (1) Carbon black with a pH of at least 5.0 or (2) Graphite to An electrical appliance according to any one of claims 1 to 7, comprising: 9. The electric appliance according to any one of claims 1 to 8, wherein the polymer is a fluoropolymer. Ingredients. 10. The carbon black has a particle size of D nanometers and (Rc5/D) of 0. ．． Claims 1 to 9 have a dry resistivity Rc5 of 1 or less. electrical appliances.