Environment-friendly fluororubber foaming composition for heater, preparation method and application thereof

Abstract

The present application relates to the technical field of fluororubber foaming composition, in particular to an environment-friendly fluororubber foaming composition for heater, a preparation method and application. The environment-friendly fluororubber foaming composition for heater is prepared from raw materials including perfluoroether rubber, amidine salt compound and metal hydroxide. The obtained environment-friendly fluororubber foaming composition for heater can be vulcanized and foamed during heating, and the foaming and vulcanization are carried out simultaneously, without the need to add new crosslinking agent. The foaming gas generated by foaming is H2O, which is environment-friendly. The present application belongs to the environment-friendly fluororubber foaming composition for heater.

Description

Technical Field

[0001] This invention relates to the field of fluororubber foam composition technology, specifically to an environmentally friendly fluororubber foam composition for heaters, its preparation method, and its application. Background Technology

[0002] There are two main foaming technologies for perfluororubber: physical foaming and chemical foaming. One type of physical foaming requires high pressure or supercritical conditions, resulting in higher costs. Another involves adding expandable microspheres composed of a thermoplastic polymer shell and encapsulated alkane gas; however, this leaves a residue after foaming and can generate pollutants at high temperatures. Chemical foaming uses N-nitroso foaming agents, azo foaming agents, and fluoroalkane foaming agents, requiring the addition of additives such as metal salts and metal oxides, which poses environmental pollution problems. Perfluororubber foam elastomers can be used in harsh chemical environments and high-temperature applications such as semiconductor piping heating, aerospace, and oil extraction. At high temperatures, perfluororubber foam elastomers must not produce polluting gases.

[0003] Chinese invention patent CN103492467B discloses a fluorinated elastomer composition and a fluorinated foamed rubber. Specifically, it discloses a fluorinated elastomer composition used in the manufacture of fluorinated foamed rubber. Relative to 100 parts by weight of the fluorinated elastomer, it contains 0.1-20 parts by weight of a blowing agent and 0.05-10 parts by weight of a crosslinking agent formed from a peroxide compound. It also contains the following crosslinking aids in an amount of more than 0.001 parts by weight and less than 0.3 parts by weight. The blowing agent is azodicarbonamide, barium azodicarboxylate, N,N-dinitrospentamethylenetetramine, benzenesulfonyl hydrazine, and biuret. However, the above-mentioned blowing agents do not produce gaseous water.

[0004] Therefore, providing an environmentally friendly fluororubber foam composition for heaters is a major technical problem that needs to be solved. Summary of the Invention

[0005] To solve the above-mentioned technical problems, the first aspect of the present invention provides an environmentally friendly fluororubber foaming composition for heaters, the raw materials of which include perfluoroether rubber, amidine salt compounds, and metal hydroxides;

[0006] The amidine salt compounds have the structure shown in Formula I:

[0007]

[0008] In Equation I, R is C n H 2n+1 The n is less than or equal to 3;

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

[0010] In one implementation, n is 0 and R is H.

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

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

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

[0014] In one embodiment, X is CH3COOH.

[0015] In one embodiment, X is HCl.

[0016] In one embodiment, X is H3PO4.

[0017] In one embodiment, X is H2SO4.

[0018] In one embodiment, X is HNO3.

[0019] In one embodiment, the amidine salt compound is formamidinium acetate.

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

[0021] In one embodiment, the amidine salt compound is formamidinium hydrochloride.

[0022] In one embodiment, 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.

[0023] In one embodiment, the heater uses an environmentally friendly fluororubber foam composition, which, by weight, comprises 100 parts of perfluoroether rubber, 1-3 parts of amidine salt compound, and 0.5-3 parts of metal hydroxide.

[0024] In one embodiment, the amount of the amidine salt compound added includes, but is not limited to, 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%, and 3.0 wt% of the perfluoroether rubber.

[0025] In one embodiment, the amount of the metal hydroxide added includes, but is 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%, and 3.0 wt% of the perfluoroether rubber.

[0026] In one embodiment, the perfluoroether rubber comprises a comonomer of tetrafluoroethylene and a perfluoroalkyl vinyl ether, and a combination of one or two of at least one cyano-based crosslinking monomer or cocrosslinking monomer.

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

[0028] During the experiment, the inventors discovered that when perfluoroether rubber, amidine salt compounds, and metal hydroxides are combined, especially when the perfluoroether rubber includes the comonomer tetrafluoroethylene and perfluoroalkyl vinyl ether, and at least one or two of the cyano crosslinking monomers or co-crosslinking monomers, the resulting fluororubber composition can undergo both vulcanization and foaming during heating. Foaming and vulcanization occur simultaneously without the need to add new crosslinking agents. Furthermore, the foaming gas produced is H2O, which is environmentally friendly and belongs to the category of environmentally friendly fluororubber foaming compositions for heaters.

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

[0030] In one embodiment, the cyano-perfluoroether rubber has a fluorine content of 72.6%, and the cyano-perfluoroether rubber is available from Solvay, Belgium, and is of the following model: 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 one or more combinations of Ca(OH)2, Mg(OH)2, and Ba(OH)2.

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

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

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

[0038] A second aspect of the present invention provides a method for preparing an environmentally friendly fluororubber foam composition for heaters, comprising the following steps:

[0039] Amidine salt compounds and metal hydroxides are added to perfluoroether rubber for compounding to obtain an environmentally friendly fluororubber foam composition for heaters.

[0040] In one embodiment, after the perfluoroether rubber is plasticized uniformly on a two-roll mill, an amidine salt compound and a metal hydroxide are added to the perfluoroether rubber. After being mixed uniformly by forming triangular bags on a two-roll mill, the mixture is sheeted to obtain an environmentally friendly fluororubber foam composition for heaters.

[0041] A third aspect of the present invention provides an application of an environmentally friendly fluororubber foam composition for heaters, which is used in the fields of semiconductors, automobile manufacturing, aerospace and chemical technology.

[0042] In one embodiment, the heater uses an environmentally friendly fluororubber foam composition that is heated and vulcanized for application in the fields of semiconductors, automobile manufacturing, aerospace, and chemical technology.

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

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

[0045] During the experiment, the inventors discovered that the foamed elastomer obtained by the environmentally friendly fluororubber foaming composition for heaters after one heating and two heating and vulcanization processes has a small pore size, a dense pore distribution, and a large foaming ratio.

[0046] Beneficial effects

[0047] This invention relates to a composition obtained by combining perfluoroether rubber, amidine salt compounds, and metal hydroxides. This composition can undergo both vulcanization and foaming during heating, with foaming and vulcanization occurring simultaneously. No new crosslinking agent is required, and the foaming gas produced is H2O. The foaming process is environmentally friendly, making it an environmentally friendly fluororubber foaming composition for heaters. Furthermore, the resulting foamed elastomer has small pore size, dense cell distribution, and a high foaming ratio. This allows the foamed elastomer to be used at high temperatures, meeting the application requirements for heat insulation and low pollution. Detailed Implementation

[0048] Example 1

[0049] The first aspect of this embodiment provides an environmentally friendly fluororubber foam composition for heaters, which, by weight, is composed of 100 parts of perfluoroether rubber, 1.2 parts of amidine salt compound, and 0.5 parts of metal hydroxide.

[0050] The amidine salt compounds have the structure shown in Formula I:

[0051]

[0052] In Equation I, R is H;

[0053] In Formula I, X is CH3COOH.

[0054] The amidine salt compound is formamidine acetate.

[0055] The CAS number for the formamidinacetate is 3473-63-0.

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

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

[0058] The metal hydroxide is an 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 this embodiment provides a method for preparing an environmentally friendly fluororubber foam composition for heaters, comprising the following steps:

[0062] After homogenizing cyano-perfluoroether rubber on a two-roll mill, amidine salt compounds and metal hydroxides are added to the cyano-perfluoroether rubber. After homogenizing by mixing in triangular bundles on a two-roll mill, the mixture is sheeted to obtain an environmentally friendly fluororubber foam composition for heaters.

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

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

[0065] Example 2

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

[0067] The amidine salt compounds have the structure shown in Formula I:

[0068]

[0069] In Equation I, R is H;

[0070] In Formula I, X is CH3COOH.

[0071] The amidine salt compound is formamidine acetate.

[0072] The CAS number for the formamidinacetate is 3473-63-0.

[0073] The perfluoroether rubber is a cyano-perfluoroether rubber.

[0074] The cyano-perfluoroether rubber was purchased from Solvay in Belgium, and the model number is [model number missing]. 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 this embodiment provides a method for preparing an environmentally friendly fluororubber foam composition for heaters, comprising the following steps:

[0079] After homogenizing cyano-perfluoroether rubber on a two-roll mill, amidine salt compounds and metal hydroxides are added to the cyano-perfluoroether rubber. After homogenizing by mixing in triangular bundles on a two-roll mill, the mixture is sheeted to obtain an environmentally friendly fluororubber foam composition for heaters.

[0080] The third aspect of this embodiment provides an application of an environmentally friendly fluororubber foam composition for heaters, which, after being heated and vulcanized, is used in the fields of semiconductors, automobile manufacturing, aerospace, and chemical technology.

[0081] The heating vulcanization includes primary heating vulcanization and secondary heating vulcanization; the temperature of the primary heating vulcanization is 180℃ and the time of the primary heating vulcanization is 10 min; the temperature of the secondary heating vulcanization is 290℃ and the time of the secondary heating vulcanization is 4 h.

[0082] Example 3

[0083] The first aspect of this embodiment provides an environmentally friendly fluororubber foam composition for heaters, which, by weight, is composed of 100 parts of perfluoroether rubber, 1.2 parts of amidine salt compound, and 2 parts of metal hydroxide.

[0084] The amidine salt compounds have the structure shown in Formula I:

[0085]

[0086] In Equation I, R is H;

[0087] In Formula I, X is CH3COOH.

[0088] The amidine salt compound is formamidine acetate.

[0089] The CAS number for the formamidinacetate is 3473-63-0.

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

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

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

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

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

[0095] The second aspect of this embodiment provides a method for preparing an environmentally friendly fluororubber foam composition for heaters, comprising the following steps:

[0096] After homogenizing cyano-perfluoroether rubber on a two-roll mill, amidine salt compounds and metal hydroxides are added to the cyano-perfluoroether rubber. After homogenizing by mixing in triangular bundles on a two-roll mill, the mixture is sheeted to obtain an environmentally friendly fluororubber foam composition for heaters.

[0097] The third aspect of this embodiment provides an application of an environmentally friendly fluororubber foam composition for heaters, which, after being heated and vulcanized, is used in the fields of semiconductors, automobile manufacturing, aerospace, and chemical technology.

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

[0099] Example 4

[0100] The first aspect of this embodiment provides an environmentally friendly fluororubber foam composition for heaters, which, by weight, is composed of 100 parts of perfluoroether rubber, 1.2 parts of amidine salt compound, and 3 parts of metal hydroxide.

[0101] The amidine salt compounds have the structure shown in Formula I:

[0102]

[0103] In Equation I, R is H;

[0104] In Formula I, X is CH3COOH.

[0105] The amidine salt compound is formamidine acetate.

[0106] The CAS number for the formamidinacetate is 3473-63-0.

[0107] The perfluoroether rubber is a cyano-perfluoroether rubber.

[0108] The cyano-perfluoroether rubber was purchased from Solvay in Belgium, and the model number is [model number missing]. PFR X1055B.

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

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

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

[0112] The second aspect of this embodiment provides a method for preparing an environmentally friendly fluororubber foam composition for heaters, comprising the following steps:

[0113] After homogenizing cyano-perfluoroether rubber on a two-roll mill, amidine salt compounds and metal hydroxides are added to the cyano-perfluoroether rubber. After homogenizing by mixing in triangular bundles on a two-roll mill, the mixture is sheeted to obtain an environmentally friendly fluororubber foam composition for heaters.

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

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

[0116] Example 5

[0117] The first aspect of this embodiment provides an environmentally friendly fluororubber foam composition for heaters, which, by weight, is composed of 100 parts of perfluoroether rubber, 1.2 parts of amidine salt compound, and 2 parts of metal hydroxide.

[0118] The amidine salt compounds have the structure shown in Formula I:

[0119]

[0120] In formula I, R is CH3;

[0121] In Formula I, X is CH3COOH.

[0122] The amidine salt compound is acetamidine acetate.

[0123] The CAS number of the acetamidine acetate is 36896-17-0.

[0124] The perfluoroether rubber is a cyano-perfluoroether rubber.

[0125] The cyano-perfluoroether rubber was purchased from Solvay in Belgium, and the model number is [model number missing]. PFR X1055B.

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

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

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

[0129] The second aspect of this embodiment provides a method for preparing an environmentally friendly fluororubber foam composition for heaters, comprising the following steps:

[0130] After homogenizing cyano-perfluoroether rubber on a two-roll mill, amidine salt compounds and metal hydroxides are added to the cyano-perfluoroether rubber. After homogenizing by mixing in triangular bundles on a two-roll mill, the mixture is sheeted to obtain an environmentally friendly fluororubber foam composition for heaters.

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

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

[0133] Example 6

[0134] The first aspect of this embodiment provides an environmentally friendly fluororubber foam composition for heaters, which, by weight, is composed of 100 parts of perfluoroether rubber, 1.2 parts of amidine salt compound, and 2 parts of metal hydroxide.

[0135] The amidine salt compounds have the structure shown in Formula I:

[0136]

[0137] In Equation I, R is H;

[0138] In Formula I, X is HCl.

[0139] The amidine salt compound is formamidine hydrochloride.

[0140] The CAS number for the formamidin hydrochloride is 6313-33-3.

[0141] The perfluoroether rubber is a cyano-perfluoroether rubber.

[0142] The cyano-perfluoroether rubber was purchased from Solvay in Belgium, and the model number is [model number missing]. 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 this embodiment provides an environmentally friendly fluororubber foaming composition for heaters, which, by weight, is composed of 100 parts of perfluoroether rubber, 2.0 parts of amidine salt compound, and 2 parts of metal hydroxide.

[0148] The amidine salt compounds have the structure shown in Formula I:

[0149]

[0150] In Equation I, R is H;

[0151] In Formula I, X is CH3COOH.

[0152] The amidine salt compound is formamidine acetate.

[0153] The CAS number for the formamidinacetate is 3473-63-0.

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

[0155] The cyano-perfluoroether rubber was purchased from Solvay in Belgium, and the model number is [model number missing]. 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 this embodiment provides an environmentally friendly fluororubber foam composition for heaters, which, by weight, is composed of 100 parts of perfluoroether rubber, 3.0 parts of amidine salt compound, and 2 parts of metal hydroxide.

[0161] The amidine salt compounds have the structure shown in Formula I:

[0162]

[0163] In Equation I, R is H;

[0164] In Formula I, X is CH3COOH.

[0165] The amidine salt compound is formamidine acetate.

[0166] The CAS number for the formamidinacetate is 3473-63-0.

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

[0168] The cyano-perfluoroether rubber was purchased from Solvay in Belgium, and the model number is [model number missing]. PFR X1055B.

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

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

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

[0172] The second aspect of this embodiment provides a method for preparing an environmentally friendly fluororubber foam composition for heaters, comprising the following steps:

[0173] After homogenizing cyano-perfluoroether rubber on a two-roll mill, amidine salt compounds and metal hydroxides are added to the cyano-perfluoroether rubber. After homogenizing by mixing in triangular bundles on a two-roll mill, the mixture is sheeted to obtain an environmentally friendly fluororubber foam composition for heaters.

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

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

[0176] Comparative Example 1

[0177] This comparative example provides a fluororubber composition, with the specific implementation method being the same as in Example 3, except that the amidine salt compound is pentamidine hydrochloride.

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

[0179] Comparative Example 2

[0180] This comparative example provides a fluororubber composition, with the specific implementation method being the same as in Example 3, except that the amidine salt compound is benzyl amidine hydrochloride.

[0181] The CAS number for the benzalkonium hydrochloride is 1670-14-0.

[0182] Comparative Example 3

[0183] This comparative example provides a fluororubber composition, and the specific implementation method is the same as in Example 3, except that there are no metal hydroxides in the raw materials.

[0184] Comparative Example 4

[0185] This comparative example provides a fluororubber composition, and the specific implementation method is the same as that in Example 5, except that there are no metal hydroxides in the raw materials.

[0186] Comparative Example 5

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

[0188] Comparative Example 6

[0189] This comparative example provides a fluororubber composition, with the specific implementation method being the same as that of Comparative Example 1, except that no metal hydroxides are used in the preparation raw materials.

[0190] Comparative Example 7

[0191] This comparative example provides a fluororubber composition, and the specific implementation method is the same as that of comparative example 2, except that there are no metal hydroxides in the raw materials used for preparation.

[0192] Performance testing

[0193] 1. Determination of sulfidation kinetics

[0194] The time process for the generation of torque [dNm] in the fluororubber foam composition and the fluororubber composition was determined according to ASTM D6601 Standard Test Method for Rubber Properties—Measurement of Cure and After-Cure Dynamic Properties Using a Rotorless Shear Rheometer. The reaction kinetics of the fluororubber foam composition and the fluororubber composition were determined using a rheometer. The upper and lower rotating plates of the rheometer were heated to 180°C, and 7g of the environmentally friendly fluororubber foam composition for heaters provided in Examples 1-8 or the fluororubber compositions provided in Comparative Examples 1-7 were taken out. Before placing the environmentally friendly fluororubber foam composition for heaters provided in Examples 1-8 or the fluororubber compositions provided in Comparative Examples 1-7 on the rheometer rotor, the sample was covered with a thin film. After placing the environmentally friendly fluororubber foaming compositions for heaters provided in Examples 1-8 or the fluororubber compositions provided in Comparative Examples 1-7 into the mixture, measurements were immediately taken to obtain measurement curves. The minimum torque was determined by the measurement curve as ML, and the maximum torque was determined by the measurement curve as MH. The difference Δ(MH-ML) was calculated from these curves. For each measurement curve, the minimum torque ML was defined as 0% of the maximum torque MH, and the maximum torque MH was normalized to 100%. The time periods from the minimum torque ML to the torque reaching 10% and 90% of the maximum torque MH were determined and designated as T10 and T90, respectively. The test results are shown in Table 1.

[0195] 2. Density

[0196] The density of the environmentally friendly fluororubber foaming compositions for heaters provided in Examples 1-8 or the fluororubber compositions provided in Comparative Examples 1-7 was tested after one heating vulcanization and two heating vulcanization. The test results are shown in Table 2.

[0197] The temperature for the first heating vulcanization is 180°C, and the time for the first heating vulcanization is 10 min. The temperature for the second heating vulcanization is 290°C, and the time for the second heating vulcanization is 4 h.

[0198] 3. Aperture size and aperture distribution

[0199] The environmentally friendly fluororubber foaming compositions for heaters provided in Examples 1-8, or the fluororubber compositions provided in Comparative Examples 1-7, were subjected to single-stage and double-stage heat curing. The uniformity of the pore size distribution of the foamed elastomers was tested, and the test results are shown in Table 2. When the proportion of the pore distribution area in the foamed elastomer to the total area is greater than 80%, it is recorded as A; when the proportion of the pore distribution area in the foamed elastomer to the total area is 20-80%, it is recorded as B; and when the proportion of the pore distribution area in the foamed elastomer to the total area is less than 20%, it is recorded as C. The test results are shown in Table 2. For the foamed elastomers recorded as A and B, the average diameter of their pores was tested, and the test results are shown in Table 2.

[0200] Table 1

[0201] Example ML(dNm) MH(dNm) Δ(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 amidine salt compounds and metal hydroxides are added to cyano-perfluoroether rubber, when R in the amidine salt compound is C n H 2n+1 When n is less than or equal to 3, Δ(MH-ML) is 3.13-5.86, indicating that cyano-perfluoroether rubber can be crosslinked without the addition of a vulcanizing agent, and the crosslinking reaction can be effectively promoted. The test results of Comparative Examples 1-7 in Table 1 show that when the fluororubber foam composition does not contain metal hydroxides and R in the amidine salt compound is C... n H 2n+1 When n is greater than 3, the Δ(MH-ML) of the obtained fluororubber foam composition is 0.28 to 0.1, indicating that the degree of vulcanization reaction of fluororubber is very low.

[0203] Table 2

[0204]

[0205]

[0206] The test results in Table 2 show that the environmentally friendly fluororubber foam compositions for heaters provided in Examples 1-8, after heat vulcanization, can obtain foam cells with an average pore size of 0.4-0.7 mm. The test results in Comparative Examples 1-7 in Table 2 show that when the fluororubber foam composition does not contain metal hydroxides and R in the amidine salt compound is C... n H 2n+1 When n is greater than 3, the pore size distribution of the obtained fluororubber foam composition reaches A and B; it can be seen that when amidine salt compounds and metal hydroxides are added to cyano-perfluoroether rubber, when R in the amidine salt compound is C n H 2n+1When n is less than or equal to 3, cyano-perfluoroether rubber can produce cells, and the cell distribution area accounts for more than 20% of the total area.

[0207] The test results in Tables 1 and 2 show that increasing the amount of amidine salt compounds increases the crosslinking density of the foamed elastomer. When amidine salt compounds are combined with metal hydroxides, if the amount of metal hydroxides added is not increased, the amount of water generated remains unchanged. Under these circumstances, the formed cells will become smaller, and the foaming will be worse.

Claims

1. An environmentally friendly fluororubber foam composition for heaters, characterized in that, Its raw materials include perfluoroether rubber, amidine salt compounds, and metal hydroxides; The amidine salt compounds have the structure shown in Formula I: Formula I, In Equation I, R is C n H 2n+1 The n is less than or equal to 3; In Formula I, X is selected from any one of CH3COOH, HCl, H3PO4, H2SO4, and HNO3; The perfluoroether rubber comprises a comonomer of tetrafluoroethylene and a perfluoroalkyl vinyl ether, and a combination of one or two of at least one cyano-based crosslinking monomer or cocrosslinking monomer.

2. The environmentally friendly fluororubber foam composition for heaters as described in 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 foam composition for heaters as described in claim 1, characterized in that, The metal hydroxides include alkaline earth metal hydroxides or amphoteric hydroxides.

4. The environmentally friendly fluororubber foam composition for heaters as described in claim 3, 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.

5. A method for preparing an environmentally friendly fluororubber foam composition for heaters as described in any one of claims 1-4, characterized in that, Includes the following steps: Amidine salt compounds and metal hydroxides are added to perfluoroether rubber for compounding to obtain an environmentally friendly fluororubber foam composition for heaters.

6. The method for preparing the environmentally friendly fluororubber foam composition for heaters as described in claim 5, characterized in that, After the perfluoroether rubber is uniformly plasticized on a two-roll mill, amidine salt compounds and metal hydroxides are added to the perfluoroether rubber. After uniform mixing by forming triangular bags on a two-roll mill, the mixture is sheeted to obtain an environmentally friendly fluororubber foam composition for heaters.

7. The application of an environmentally friendly fluororubber foam composition for heaters as described in any one of claims 1-4, characterized in that, The environmentally friendly fluororubber foam composition for heaters can be used in any of the fields of semiconductor, automotive manufacturing, aerospace and chemical technology.

8. The application of the environmentally friendly fluororubber foam composition for heaters as described in claim 7, characterized in that, The environmentally friendly fluororubber foam composition for heaters, after being heated and vulcanized, can be used in any of the fields of semiconductor, automotive manufacturing, aerospace and chemical technology.

9. The application of the environmentally friendly fluororubber foam composition for heaters as described in claim 8, characterized in that, The heating vulcanization includes primary heating vulcanization and secondary heating vulcanization; the temperature of primary heating vulcanization is 160-190℃ and the time of primary heating vulcanization is 5-15 min; the temperature of secondary heating vulcanization is 280-295℃ and the time of secondary heating vulcanization is 3-5 h.

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