Environment-friendly fluororubber foaming composition for heater as well as preparation method and application of environment-friendly fluororubber foaming composition

Abstract

The invention relates to the technical field of fluororubber foaming compositions, in particular to an environment-friendly fluororubber foaming composition for a heater and a preparation method and application of the environment-friendly fluororubber foaming composition. The environment-friendly fluororubber foaming composition for the heater is prepared from the following raw materials: perfluoroether rubber, an amidine salt compound and metal hydroxide, the obtained environment-friendly fluororubber foaming composition for the heater can be vulcanized and can also be foamed in the heating process, foaming and vulcanization are carried out at the same time, a new cross-linking agent does not need to be added, and the environment-friendly fluororubber foaming composition for the heater is environment-friendly and energy-saving. And the foaming gas generated by foaming is H2O, so that the fluororubber foaming composition is environment-friendly and belongs to the environment-friendly fluororubber foaming composition for the heater.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of fluororubber foaming composition, in particular to an environmentally friendly fluororubber foaming composition for a heater, a preparation method and application thereof. BACKGROUND

[0002] The foaming technology of perfluorinated rubber mainly includes physical foaming and chemical foaming. Among them, one mode of physical foaming needs to be carried out under high pressure or supercritical state, which has high cost; the other mode is to add expanded microspheres composed of a thermoplastic polymer shell and enclosed alkane gas, and the shell remains after foaming, which will produce pollutants at high temperature. Chemical foaming uses N-nitroso foaming agent, azo foaming agent, and fluoroalkane foaming agent, and needs to add metal salt, metal oxide and other additives, which has environmental pollution problem. Perfluorinated rubber foaming elastomer can be applied to semiconductor pipeline heating, aerospace, oil exploitation and other places with harsh chemical environment and high temperature, and the perfluorinated rubber foaming elastomer needs to generate no gas that pollutes the environment at high temperature.

[0003] Chinese patent CN103492467B discloses a fluorine-containing elastomer composition and a fluorine-containing foaming rubber, specifically discloses a fluorine-containing elastomer composition for manufacturing a fluorine-containing foaming rubber, which contains 0.1-20 mass parts of a foaming agent and 0.05-10 mass parts of a crosslinking agent formed by a peroxide compound, and contains a crosslinking aid in an amount of 0.001 mass parts or more and 0.3 mass parts or less, and uses azodicarbonamide, barium salt of azodicarboxylic acid, N,N-dinitrosopentamethylene tetramine, benzenesulfonyl hydrazide and biurea as the foaming agent; but the above foaming agent cannot generate water.

[0004] Therefore, it is a main technical problem to be solved at present to provide an environmentally friendly fluororubber foaming composition for a heater. SUMMARY

[0005] In order to solve the above technical problems, the first aspect of the present application provides an environmentally friendly fluororubber foaming composition for a heater, which is prepared from perfluoroether rubber, amidine salt compound and metal hydroxide.

[0006] The amidine salt compound has a structure as shown in Formula I:

[0007]

[0008] R in the Formula I is C n H 2n+1 , and n is less than or equal to 3.

[0009] X in the Formula I is selected from any one of CH3COOH, HCl, H3PO4, H2SO4 and HNO3.

[0010] In an embodiment, the n is 0 and the R is H.

[0011] In an embodiment, the n is 1 and the R is CH3.

[0012] In an embodiment, the n is 2 and the R is C2H5.

[0013] In an embodiment, the n is 3 and the R is C3H7.

[0014] In an embodiment, the X is CH3COOH.

[0015] In an embodiment, the X is HCl.

[0016] In an embodiment, the X is H3PO4.

[0017] In an embodiment, the X is H2SO4.

[0018] In an embodiment, the X is HNO3.

[0019] In an embodiment, the amidine salt compound is formamidine acetate.

[0020] In an embodiment, the amidine salt compound is acetamidine acetate.

[0021] In an embodiment, the amidine salt compound is formamidine hydrochloride.

[0022] In an embodiment, the amidine salt compound is added in an amount of 1-3 wt% of the perfluoroether rubber, and the metal hydroxide is added in an amount of 0.5-3 wt% of the perfluoroether rubber.

[0023] In an embodiment, the environmentally friendly fluorine rubber foaming composition for the heater is prepared from the following raw materials in parts by weight: perfluoroether rubber 100 parts, amidine salt compound 1-3 parts, and metal hydroxide 0.5-3 parts.

[0024] In an embodiment, the amidine salt compound is added in an amount of 1 wt%, 1.1 wt%, 1.2 wt%, 1.3 wt%, 1.4 wt%, 1.5 wt%, 1.6 wt%, 1.7 wt%, 1.8 wt%, 1.9 wt%, 2.0 wt%, 2.1 wt%, 2.2 wt%, 2.3 wt%, 2.4 wt%, 2.5 wt%, 2.6 wt%, 2.7 wt%, 2.8 wt%, 2.9 wt%, 3.0 wt% of the perfluoroether rubber.

[0025] In one embodiment, the metal hydroxide is added in an amount including but not limited to 0.5 wt%, 0.6 wt%, 0.7 wt%, 0.8 wt%, 0.9 wt%, 1 wt%, 1.1 wt%, 1.2 wt%, 1.3 wt%, 1.4 wt%, 1.5 wt%, 1.6 wt%, 1.7 wt%, 1.8 wt%, 1.9 wt%, 2.0 wt%, 2.1 wt%, 2.2 wt%, 2.3 wt%, 2.4 wt%, 2.5 wt%, 2.6 wt%, 2.7 wt%, 2.8 wt%, 2.9 wt%, 3.0 wt% of the perfluoroelastomer.

[0026] In one embodiment, the perfluoroelastomer includes a combination of the copolymerization monomers tetrafluoroethylene and perfluoroalkyl vinyl ether and at least one of a cyano-based crosslinking monomer or a co-crosslinking monomer.

[0027] In one embodiment, the co-crosslinking monomer includes a monomer containing carboxyl or diene.

[0028] The inventors have found that when the perfluoroelastomer, the amidine salt compound and the metal hydroxide are combined, especially when the perfluoroelastomer includes a combination of the copolymerization monomers tetrafluoroethylene and perfluoroalkyl vinyl ether and at least one of a cyano-based crosslinking monomer or a co-crosslinking monomer, the resulting fluororubber composition can both cure and foam during heating, the foaming and curing occur simultaneously, no new crosslinking agent needs to be added, and the foaming gas produced by the foaming is H2O, which is environmentally friendly, and the composition is an environmentally friendly fluororubber foaming composition for a heater.

[0029] In one embodiment, the perfluoroelastomer is a cyano-perfluoroelastomer.

[0030] In one embodiment, the cyano-perfluoroelastomer has a fluorine content of 72.6%, and the cyano-perfluoroelastomer is commercially available from Solvay, Belgium, under the trade designation PFR X1055B.

[0031] In one embodiment, the metal hydroxide includes an alkaline earth metal hydroxide or an amphoteric hydroxide.

[0032] In one embodiment, the amphoteric hydroxide includes Al(OH)3.

[0033] In one embodiment, the metal hydroxide is an alkaline earth metal hydroxide.

[0034] In one embodiment, the alkaline earth metal hydroxide is selected from a combination of one or more of Ca(OH)2, Mg(OH)2, Ba(OH)2.

[0035] In an embodiment, the alkaline earth metal hydroxide is Ca(OH)2.

[0036] In an embodiment, the alkaline earth metal hydroxide is Mg(OH)2.

[0037] In an embodiment, the alkaline earth metal hydroxide is Ba(OH)2.

[0038] The second aspect of the present application provides a preparation method of an environmentally friendly fluororubber foaming composition for a heater, comprising the following steps:

[0039] The amidine salt compound and the metal hydroxide are added to the perfluoroether rubber for mixing to obtain the environmentally friendly fluororubber foaming composition for a heater.

[0040] In an embodiment, after the perfluoroether rubber is uniformly plasticized on a two-roll open mill, the amidine salt compound and the metal hydroxide are added to the perfluoroether rubber, and the environmentally friendly fluororubber foaming composition for a heater is obtained after the perfluoroether rubber is uniformly mixed by triangle bag mixing on the two-roll open mill and then sheeting.

[0041] The third aspect of the present application provides an application of the environmentally friendly fluororubber foaming composition for a heater, which is applied in the fields of semiconductors, automobile manufacturing, aerospace, and chemical technology.

[0042] In an embodiment, the environmentally friendly fluororubber foaming composition for a heater is applied in the fields of semiconductors, automobile manufacturing, aerospace, and chemical technology after being heated and vulcanized.

[0043] In an embodiment, the heating and vulcanization includes primary heating and vulcanization and secondary heating and vulcanization; the temperature of the primary heating and vulcanization is 160-190℃, the time of the primary heating and vulcanization is 5-15min, the temperature of the secondary heating and vulcanization is 280-295℃, and the time of the secondary heating and vulcanization is 3-5h.

[0044] In an embodiment, the heating and vulcanization includes primary heating and vulcanization and secondary heating and vulcanization; the temperature of the primary heating and vulcanization is 180℃, the time of the primary heating and vulcanization is 10min, the temperature of the secondary heating and vulcanization is 290℃, and the time of the secondary heating and vulcanization is 4h.

[0045] The inventors found in the experimental process that the environmentally friendly fluororubber foaming composition for a heater obtained after primary heating and vulcanization and secondary heating and vulcanization has a small pore size of the foamed elastomer, a dense bubble hole distribution, and a large foaming ratio of the foamed elastomer.

[0046] Advantages

[0047] The application is a kind of environmental protection type fluorine rubber foaming composition for heater, which is prepared by compounding perfluoroether rubber, amidine salt compound and metal hydroxide, and can be vulcanized and foamed during heating, and the foaming and vulcanization are carried out simultaneously, and no new cross-linking agent is needed to be added, and the foaming gas generated by foaming is H2O, and the foaming process is environmental protection, and the environmental friendliness is achieved. DETAILED DESCRIPTION

[0048] Embodiment 1

[0049] The first aspect of the embodiment provides a kind of environmental protection type fluorine rubber foaming composition for heater, and its preparation raw material is composed of perfluoroether rubber 100 parts, amidine salt compound 1.2 parts, metal hydroxide 0.5 parts by weight.

[0050] The amidine salt compound has the structure shown in formula I:

[0051]

[0052] R in formula I is H;

[0053] X in formula I is CH3COOH.

[0054] The amidine salt compound is formamidine acetate.

[0055] The CAS number of the formamidine acetate is 3473-63-0.

[0056] The perfluoroether rubber is cyano-perfluoroether rubber.

[0057] The cyano-perfluoroether rubber is purchased from Solvay in Belgium, and the model is PFR X1055B.

[0058] The metal hydroxide is alkaline earth metal hydroxide.

[0059] The alkaline earth metal hydroxide is Ca (OH) 2.

[0060] The CAS number of the Ca (OH) 2 is 1305-62-0.

[0061] The second aspect of the embodiment provides a kind of preparation method of environmental protection type fluorine rubber foaming composition for heater, including the following steps:

[0062] After the cyanide-perfluoroether rubber is plasticized evenly on a two-roll open mill, the amidine salt compound and the metal hydroxide are added to the cyanide-perfluoroether rubber, and the environmentally friendly fluororubber foaming composition for heaters is obtained by mixing evenly on the two-roll open mill and then sheeting after triangle bag mixing.

[0063] The third aspect of the embodiment provides an application of the environmentally friendly fluororubber foaming composition for heaters, which is applied in the fields of semiconductors, automobile manufacturing, aerospace and chemical technology after being heated and vulcanized.

[0064] The heating and vulcanization includes primary heating and vulcanization and secondary heating and vulcanization; the temperature of the primary heating and vulcanization is 180℃, the time of the primary heating and vulcanization is 10min, the temperature of the secondary heating and vulcanization is 290℃, and the time of the secondary heating and vulcanization is 4h.

[0065] Example 2

[0066] The first aspect of the embodiment provides an environmentally friendly fluororubber foaming composition for heaters, which is prepared from 100 parts of perfluoroether rubber, 1.2 parts of amidine salt compound and 1 part of metal hydroxide by weight.

[0067] The amidine salt compound has a structure as shown in Formula I:

[0068]

[0069] R in the Formula I is H;

[0070] X in the Formula I is CH3COOH.

[0071] The amidine salt compound is formamidine acetate.

[0072] The CAS number of the formamidine acetate is 3473-63-0.

[0073] The perfluoroether rubber is cyanide-perfluoroether rubber.

[0074] The cyanide-perfluoroether rubber is purchased from Solvay, Belgium, and the model number is PFR X1055B.

[0075] The metal hydroxide is an alkaline earth metal hydroxide.

[0076] The alkaline earth metal hydroxide is Ca(OH)2.

[0077] The CAS number of the Ca(OH)2 is 1305-62-0.

[0078] The second aspect of the embodiment provides a preparation method of the environment-friendly fluororubber foaming composition for a heater, comprising the following steps:

[0079] After the cyano-perfluoroether rubber is uniformly plasticized on a two-roll open mill, the amidine salt compound and the metal hydroxide are added to the cyano-perfluoroether rubber, and the environment-friendly fluororubber foaming composition for a heater is obtained by uniformly mixing on the two-roll open mill and then sheeting.

[0080] The third aspect of the embodiment provides an application of the environment-friendly fluororubber foaming composition for a heater, which is applied in the fields of semiconductors, automobile manufacturing, aerospace and chemical technology after being heat-vulcanized.

[0081] The heat-vulcanization comprises primary heat-vulcanization and secondary heat-vulcanization; the temperature of the primary heat-vulcanization is 180℃, the time of the primary heat-vulcanization is 10 min, the temperature of the secondary heat-vulcanization is 290℃, and the time of the secondary heat-vulcanization is 4 h.

[0082] Embodiment 3

[0083] The first aspect of the embodiment provides an environment-friendly fluororubber foaming composition for a heater, which is prepared from 100 parts of perfluoroether rubber, 1.2 parts of amidine salt compound and 2 parts of metal hydroxide by weight.

[0084] The amidine salt compound has a structure as shown in Formula I:

[0085]

[0086] R in the Formula I is H;

[0087] X in the Formula I is CH3COOH.

[0088] The amidine salt compound is formamidine acetate.

[0089] The CAS number of the formamidine acetate is 3473-63-0.

[0090] The perfluoroether rubber is cyano-perfluoroether rubber.

[0091] The cyano-perfluoroether rubber is purchased from Solvay, Belgium, and the model number is PFR X1055B.

[0092] The metal hydroxide is an alkaline earth metal hydroxide.

[0093] The alkaline earth metal hydroxide is Ca(OH)2.

[0094] The Ca(OH)2 has a CAS number of 1305-62-0.

[0095] The second aspect of the embodiment provides a preparation method of the environmentally friendly fluororubber foaming composition for a heater, including the following steps:

[0096] After the cyano-perfluoro ether rubber is uniformly plasticized on a double roller mill, the amidine salt compound and the metal hydroxide are added to the cyano-perfluoro ether rubber, and the environmentally friendly fluororubber foaming composition for a heater is obtained after uniform mixing on the double roller mill.

[0097] The third aspect of the embodiment provides an application of the environmentally friendly fluororubber foaming composition for a heater, which is applied in the fields of semiconductors, automobile manufacturing, aerospace and chemical technology after being heat vulcanized.

[0098] The heat vulcanization includes primary heat vulcanization and secondary heat vulcanization; the temperature of the primary heat vulcanization is 180℃, the time of the primary heat vulcanization is 10min, the temperature of the secondary heat vulcanization is 290℃, and the time of the secondary heat vulcanization is 4h.

[0099] Embodiment 4

[0100] The first aspect of the embodiment provides an environmentally friendly fluororubber foaming composition for a heater, which is prepared from 100 parts of perfluoro ether rubber, 1.2 parts of amidine salt compound and 3 parts of metal hydroxide by weight.

[0101] The amidine salt compound has a structure as shown in Formula I:

[0102]

[0103] R in the Formula I is H;

[0104] X in the Formula I is CH3COOH.

[0105] The amidine salt compound is formamidine acetate.

[0106] The formamidine acetate has a CAS number of 3473-63-0.

[0107] The perfluoro ether rubber is cyano-perfluoro ether rubber.

[0108] The cyano-perfluoro ether rubber is purchased from Solvay, Belgium, and the model number is PFR X1055B.

[0109] The metal hydroxide is an alkaline earth metal hydroxide.

[0110] The alkaline earth metal hydroxide is Ca(OH)2.

[0111] The Ca(OH)2 has a CAS number of 1305-62-0.

[0112] The second aspect of the embodiment provides a preparation method of the environmentally friendly fluororubber foaming composition for a heater, including the following steps:

[0113] After the cyano-perfluoro ether rubber is uniformly plasticized on a double roller mill, the amidine salt compound and the metal hydroxide are added to the cyano-perfluoro ether rubber, and the environmentally friendly fluororubber foaming composition for a heater is obtained after uniform mixing on the double roller mill.

[0114] The third aspect of the embodiment provides an application of the environmentally friendly fluororubber foaming composition for a heater, which is applied in the fields of semiconductors, automobile manufacturing, aerospace and chemical technology after being heated and vulcanized.

[0115] The heating and vulcanization includes primary heating and vulcanization and secondary heating and vulcanization; the temperature of the primary heating and vulcanization is 180℃, the time of the primary heating and vulcanization is 10 min, the temperature of the secondary heating and vulcanization is 290℃, and the time of the secondary heating and vulcanization is 4 h.

[0116] Embodiment 5

[0117] The first aspect of the embodiment provides an environmentally friendly fluororubber foaming composition for a heater, which is prepared from 100 parts of perfluoro ether rubber, 1.2 parts of amidine salt compound and 2 parts of metal hydroxide by weight.

[0118] The amidine salt compound has a structure as shown in Formula I:

[0119]

[0120] R in the Formula I is CH3;

[0121] X in the Formula I is CH3COOH.

[0122] The amidine salt compound is ethylamidine acetate.

[0123] The ethylamidine acetate has a CAS number of 36896-17-0.

[0124] The perfluoro ether rubber is cyano-perfluoro ether rubber.

[0125] The cyano-perfluoro ether rubber is purchased from Solvay, Belgium, and the model number is PFR X1055B.

[0126] The metal hydroxide is an alkaline earth metal hydroxide.

[0127] The alkaline earth metal hydroxide is Ca(OH)2.

[0128] The Ca(OH)2 has a CAS number of 1305-62-0.

[0129] The second aspect of the embodiment provides a preparation method of an environmentally friendly fluororubber foaming composition for a heater, comprising the following steps:

[0130] After the cyano-perfluoro ether rubber is uniformly plasticized on a two-roll open mill, the amidine salt compound and the metal hydroxide are added to the cyano-perfluoro ether rubber, and the environmentally friendly fluororubber foaming composition for a heater is obtained after uniform mixing by triangle bag mixing on the two-roll open mill.

[0131] The third aspect of the embodiment provides an application of an environmentally friendly fluororubber foaming composition for a heater, which is applied in the fields of semiconductors, automobile manufacturing, aerospace and chemical technology after being heated and vulcanized.

[0132] The heating and vulcanization includes primary heating and vulcanization and secondary heating and vulcanization; the temperature of the primary heating and vulcanization is 180℃, the time of the primary heating and vulcanization is 10min, the temperature of the secondary heating and vulcanization is 290℃, and the time of the secondary heating and vulcanization is 4h.

[0133] Embodiment 6

[0134] The first aspect of the embodiment provides an environmentally friendly fluororubber foaming composition for a heater, which is prepared from 100 parts of perfluoro ether rubber, 1.2 parts of amidine salt compound and 2 parts of metal hydroxide by weight.

[0135] The amidine salt compound has a structure as shown in Formula I:

[0136]

[0137] R in Formula I is H;

[0138] X in Formula I is HCl.

[0139] The amidine salt compound is formamidine hydrochloride.

[0140] The formamidine hydrochloride has a CAS number of 6313-33-3.

[0141] The perfluoro ether rubber is cyano-perfluoro ether rubber.

[0142] The manufacturer of the cyano-perfluoroether rubber is Solvay, Belgium, and the model number is PFR X1055B.

[0143] The metal hydroxide is an alkaline earth metal hydroxide.

[0144] The alkaline earth metal hydroxide is Ca(OH)2.

[0145] The CAS number of the Ca(OH)2 is 1305-62-0.

[0146] Example 7

[0147] The first aspect of the embodiment provides an environmentally friendly fluororubber foaming composition for a heater, which is prepared from 100 parts by weight of perfluoroether rubber, 2.0 parts by weight of amidine salt compound, and 2 parts by weight of metal hydroxide.

[0148] The amidine salt compound has a structure as shown in Formula I:

[0149]

[0150] R in Formula I is H;

[0151] X in Formula I is CH3COOH.

[0152] The amidine salt compound is formamidine acetate.

[0153] The CAS number of the formamidine acetate is 3473-63-0.

[0154] The perfluoroether rubber is cyano-perfluoroether rubber.

[0155] The manufacturer of the cyano-perfluoroether rubber is Solvay, Belgium, and the model number is PFR X1055B.

[0156] The metal hydroxide is an alkaline earth metal hydroxide.

[0157] The alkaline earth metal hydroxide is Ca(OH)2.

[0158] The CAS number of the Ca(OH)2 is 1305-62-0.

[0159] Example 8

[0160] The first aspect of the embodiment provides an environmentally friendly fluororubber foaming composition for a heater, which is prepared from 100 parts by weight of perfluoroether rubber, 3.0 parts by weight of amidine salt compound, and 2 parts by weight of metal hydroxide.

[0161] The amidine salt compound has a structure as shown in Formula I:

[0162]

[0163] R in Formula I is H;

[0164] X in Formula I is CH3COOH.

[0165] The amidine salt compound is formamidine acetate.

[0166] The formamidine acetate has a CAS number of 3473-63-0.

[0167] The perfluoroether rubber is cyano-perfluoroether rubber.

[0168] The cyano-perfluoroether rubber is purchased from Solvay, Belgium, with model number of PFR X1055B.

[0169] The metal hydroxide is an alkaline earth metal hydroxide.

[0170] The alkaline earth metal hydroxide is Ca(OH)2.

[0171] The Ca(OH)2has a CAS number of 1305-62-0.

[0172] The second aspect of the embodiment provides a preparation method of the environmentally friendly fluororubber foaming composition for a heater, comprising the following steps:

[0173] After the cyano-perfluoroether rubber is uniformly plasticized on a two-roll open mill, the amidine salt compound and the metal hydroxide are added to the cyano-perfluoroether rubber, and the environmentally friendly fluororubber foaming composition for a heater is obtained after uniform mixing by triangle bag mixing on the two-roll open mill.

[0174] The third aspect of the embodiment provides an application of the environmentally friendly fluororubber foaming composition for a heater, which is applied in the fields of semiconductors, automobile manufacturing, aerospace and chemical technology after being heated and vulcanized.

[0175] The heating and vulcanization includes primary heating and vulcanization and secondary heating and vulcanization; the temperature of the primary heating and vulcanization is 180°C, the time of the primary heating and vulcanization is 10 min, the temperature of the secondary heating and vulcanization is 290°C, and the time of the secondary heating and vulcanization is 4 h.

[0176] Comparative Example 1

[0177] The comparative example provides a fluororubber composition, and the specific implementation manner is the same as that of Example 3, except that the amidine salt compound is valeric amidine hydrochloride.

[0178] The CAS number of the pentamidine hydrochloride is 18257-46-0.

[0179] Comparative Example 2

[0180] This comparative example provides a fluororubber composition, and the specific implementation manner is the same as that of Example 3, except that the amidine salt compound is benzamidine hydrochloride.

[0181] The CAS number of the benzamidine hydrochloride is 1670-14-0.

[0182] Comparative Example 3

[0183] This comparative example provides a fluororubber composition, and the specific implementation manner is the same as that of Example 3, except that no metal hydroxide is contained in the preparation raw materials.

[0184] Comparative Example 4

[0185] This comparative example provides a fluororubber composition, and the specific implementation manner is the same as that of Example 5, except that no metal hydroxide is contained in the preparation raw materials.

[0186] Comparative Example 5

[0187] This comparative example provides a fluororubber composition, and the specific implementation method is the same as that of Example 6, except that no metal hydroxide is contained in the preparation raw materials.

[0188] Comparative Example 6

[0189] This comparative example provides a fluororubber composition, and the specific implementation manner is the same as that of comparative example 1, except that no metal hydroxide is contained in the preparation raw materials.

[0190] Comparative Example 7

[0191] This comparative example provides a fluororubber composition, and the specific implementation manner is the same as that of comparative example 2, except that no metal hydroxide is contained in the preparation raw materials.

[0192] Performance Testing

[0193] 1. Determination of vulcanization dynamics

[0194] The time course of torque [dNm] generation of the fluororubber foamed composition and the fluororubber composition was determined according to the "ASTM D6601 Standard Test Method for Rubber Properties—Measurement of Cure and After-Cure Dynamic Properties Using a Rotorless Shear Rheometer", and the reaction kinetics of the fluororubber foamed composition and the fluororubber composition was determined using a rheometer. The upper and lower rotating plates of the rheometer were heated to 180°C, and 7 g of the heater-use environment-friendly fluororubber foamed composition provided in Examples 1 to 8 or the fluororubber composition provided in Comparative Examples 1 to 7 was taken out. The heater-use environment-friendly fluororubber foamed composition provided in Examples 1 to 8 or the fluororubber composition provided in Comparative Examples 1 to 7 was covered with a film before being placed on the rheometer rotor. Immediately after the heater-use environment-friendly fluororubber foamed composition provided in Examples 1 to 8 or the fluororubber composition provided in Comparative Examples 1 to 7 was placed, measurement was started, and a measurement curve was obtained, which determined the minimum torque as ML, and the maximum torque as MH, and from which the difference Δ(MH-ML) was calculated; for each measurement curve, the minimum torque ML was defined as 0% of the maximum torque MH, which was normalized to 100%; the time periods from the minimum torque ML at which the torque reached 10% and 90% of the maximum torque MH were determined, and were designated as T10 and T90, respectively. The test results are shown in Table 1.

[0195] 2. Density

[0196] The heater-use environment-friendly fluororubber foamed composition provided in Examples 1 to 8 or the fluororubber composition provided in Comparative Examples 1 to 7 was subjected to primary heat vulcanization and secondary heat vulcanization, and the density thereof was tested. The test results are shown in Table 2.

[0197] The temperature of the primary heat vulcanization was 180°C, the time of the primary heat vulcanization was 10 min, the temperature of the secondary heat vulcanization was 290°C, and the time of the secondary heat vulcanization was 4 h.

[0198] 3. Pore size and degree of pore size distribution

[0199] The environmental-friendly fluororubber foaming composition provided by Examples 1-8 or the fluororubber composition provided by Comparative Examples 1-7 was subjected to primary heat vulcanization and secondary heat vulcanization, and then the uniformity of the pore size distribution of the foamed elastomer was tested, and the test results are shown in Table 2. When the proportion of the pore distribution area in the total area of the foamed elastomer is greater than 80%, it is recorded as A; when the proportion of the pore distribution area in the total area of the foamed elastomer is 20-80%, it is recorded as B; and when the proportion of the pore distribution area in the total area of the foamed elastomer is less than 20%, it is recorded as C. For the foamed elastomers recorded as A and B, the average diameter of the pores was tested, and the test results are shown in Table 2.

[0200] Table 1

[0201] Example ML (dNm) MH (dNm) (MH-ML) T10 (min) T90 (min) Example 1 2.27 8.13 5.86 0.29 0.56 Example 2 2.67 7.89 5.22 0.28 0.53 Example 3 3.48 8.2 4.72 0.28 0.49 Example 4 2.51 7.31 4.8 0.26 0.48 Example 5 4.67 7.8 3.13 0.27 0.52 Example 6 3.6 7.74 4.14 0.42 0.9 Example 7 2.54 7.68 5.14 0.25 0.56 Example 8 2.50 7.79 5.29 0.23 0.45 Comparative Example 1 4.56 8.21 3.65 0.27 18.07 Comparative Example 2 1.14 5.96 4.82 0.94 6.91 Comparative Example 3 1.95 8.35 6.4 0.5 0.68 Comparative Example 4 1.86 8.01 6.15 0.64 0.86 Comparative Example 5 0.69 6.96 6.27 2.27 16.72 Comparative Example 6 0.58 0.86 0.28 10.9 28.9 Comparative Example 7 0.65 0.75 0.1 1.13 28.35

[0202] As can be seen from the test results of Examples 1-8 in Table 1, when the amidine salt compound and the metal hydroxide are added to the cyano-perfluoro ether rubber, and R in the amidine salt compound is C n H 2n+1 , and n is less than or equal to 3, Δ(MH-ML) is 3.13-5.86, which indicates that the cyano-perfluoro ether rubber can be crosslinked without adding a vulcanizing agent, and the crosslinking reaction can be effectively promoted. As can be seen from the test results of Comparative Examples 1-7 in Table 1, when the fluororubber foaming composition does not contain a metal hydroxide, and R in the amidine salt compound is C n H 2n+1 , and n is greater than 3, Δ(MH-ML) of the fluororubber foaming composition obtained is 0.28-0.1, which indicates that the vulcanization reaction of the fluororubber is very low.

[0203] Table 2

[0204]

[0205]

[0206] As can be seen from the test results in Table 2, the environmental-friendly fluororubber foaming composition provided by Examples 1-8 for the heater can obtain pores with an average pore size of 0.4-0.7 mm after heat vulcanization. As can be seen from the test results of Comparative Examples 1-7 in Table 2, when the fluororubber foaming composition does not contain a metal hydroxide, and R in the amidine salt compound is C n H 2n+1 , and n is greater than 3, the degree of pore size distribution of the fluororubber foaming composition obtained reaches A and B. Therefore, it can be seen that when the amidine salt compound and the metal hydroxide are added to the cyano-perfluoro ether rubber, and R in the amidine salt compound is C n H 2n+1, the n being equal to or less than 3, can make the cyan group-perfluoroether rubber produce bubbles, and the bubble distribution area accounts for more than 20% of the total area.

[0207] As can be seen from the test results in Tables 1 and 2, increasing the amount of the amidine salt compound can increase the crosslinking density of the foamed elastomer. When the amidine salt compound is combined with the metal hydroxide, the amount of water generated is unchanged if the amount of the metal hydroxide is not increased. In this case, the bubbles formed will be smaller, and the foaming will be poorer.

Claims

1. An environmentally friendly fluororubber foaming composition for heater, characterized in that: The raw materials for its preparation include perfluoroether rubber, amidine salt compound and metal hydroxide; The amidine salt compound has a structure as shown in Formula I: In the formula I, R is C n H 2n+1 , the n is less than or equal to 3; In the formula I, X is selected from any one of CH3COOH, HCl, H3PO4, H2SO4 and HNO3.

2. The environmentally friendly fluororubber foaming composition for heater according to claim 1, characterized in that: The amount of the amidine salt compound added is 1-3 wt % of the perfluoroether rubber, and the amount of the metal hydroxide added is 0.5-3 wt % of the perfluoroether rubber.

3. The environmentally friendly fluororubber foaming composition for heater according to claim 1, characterized in that: The perfluoroether rubber comprises a combination of comonomers tetrafluoroethylene and perfluoroalkyl vinyl ether and at least one cyano-type crosslinking monomer or a co-crosslinking monomer or both.

4. The environmentally friendly fluororubber foaming composition for heater according to claim 1, characterized in that: The metal hydroxide includes an alkaline earth metal hydroxide or an amphoteric hydroxide.

5. The environmentally friendly fluororubber foaming composition for heater according to claim 4, characterized in that: The alkaline earth metal hydroxide is selected from one or more combinations of Ca(OH)2, Mg(OH)2, and Ba(OH)2.

6. A method for preparing the environmentally friendly fluororubber foaming composition for heaters according to any one of claims 1 to 5, characterized in that: The following steps are involved: An amidine salt compound and a metal hydroxide are added into perfluoroether rubber and kneaded to obtain an environmentally friendly fluororubber foaming composition for a heater.

7. The method for preparing the environmentally friendly fluororubber foaming composition for heater according to claim 6, characterized in that: After the perfluoroether rubber is uniformly plasticized on a double-roll mill, an amidine salt compound and a metal hydroxide are added to the perfluoroether rubber, and the mixture is uniformly mixed by triangular packing on the double-roll mill and then sheeted to obtain an environmentally friendly fluororubber foaming composition for heaters.

8. An application of the environmentally friendly fluororubber foaming composition for heaters according to any one of claims 1 to 5, characterized in that: The environmentally friendly fluororubber foaming composition for heaters is used in the fields of semiconductors, automobile manufacturing, aerospace and chemical technology.

9. The use of the environmentally friendly fluororubber foaming composition for heaters according to claim 8, characterized in that: The environmentally friendly fluororubber foaming composition for heaters is applied in the fields of semiconductor, automobile manufacturing, aerospace and chemical technology after being heated and vulcanized.

10. The use of the environmentally friendly fluororubber foaming composition for heaters according to claim 9, characterized in that: The heating vulcanization includes primary heating vulcanization and secondary heating vulcanization; the temperature of the primary heating vulcanization is 160-190° C., the time of the primary heating vulcanization is 5-15 minutes, and the temperature of the secondary heating vulcanization is 280-295° C., the time of the secondary heating vulcanization is 3-5 hours.

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