Rubber composition, processing method thereof, and flame-retardant product using the same

Abstract

The present invention discloses a rubber composition, a processing method for obtaining the rubber composition, and application of the composition in processing of flame-retardant products. The rubber composition includes a rubber matrix and essential components. The rubber matrix includes a branched polyethylene with a content represented as A, in which 0<A≤100, and an EPM and an EPDM with a total content represented as B, in which 0≤B<100. The essential components include 1.5 to 10 parts of a crosslinking agent and 40 to 300 parts of a flame-retardant agent. The rubber composition can be applied to production of flame-retardant products, such as flame-retardant cable, flame-retardant cool air hose for automobile, flame-retardant sealing strip, high-temperature-resistant flame-retardant conveyor belt, and flame-retardant waterproof coil. The products have good flame-retardant effects and mechanical properties.

Claims

1. A rubber composition, comprising a rubber matrix and essential components, wherein, based on 100 parts by weight of said rubber matrix, the rubber matrix comprises: a branched polyethylene with a content represented as A, in which 0<A≤100 parts, and an EPM and/or an EPDM with a total content represented as B, in which 0≤B<100 parts; wherein the essential components comprise, based on 100 parts by weight of the rubber matrix, 1.5 to 10 parts of a crosslinking agent and 40 to 300 parts of a flame-retardant agent; and wherein the branched polyethylene comprises an ethylene homopolymer having a degree of branching of from 60 to 105 branches/1000 carbon atoms, a weight average molecular weight of from 268,000 to 518,000, and a Mooney viscosity ML(1+4) at 125° C. of from 42 to 102.

2. The rubber composition according to claim 1, wherein 10≤A≤100 parts, and wherein 0≤B≤90 parts.

3. The rubber composition according to claim 1, wherein, the crosslinking agent comprises at least one of a peroxide crosslinking agent and sulfur, and the peroxide crosslinking agent comprises at least one of di-tert-butyl peroxide, dicumyl peroxide, tert-butyl cumyl peroxide, 1,1-di-tert-butyl peroxide-3,3,5-trimethylcyclohexane, 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane, 2,5-dimethyl-2,5-di(tert-butylperoxy)hexyne-3, bis(tert-butylperoxyisopropyl)benzene, 2,5-dimethyl-2,5-bis(benzoylperoxy)hexane, tert-butyl peroxybenzoate, and tert-butylperoxy-2-ethylhexyl carbonate.

4. The rubber composition according to claim 1, wherein, based on 100 parts by weight of the rubber matrix, the content of the flame-retardant agent is 60 to 200 parts.

5. The rubber composition according to claim 1, wherein, the flame-retardant agent comprises at least one of aluminum hydroxide, magnesium hydroxide, zinc borate, antimonous oxide, zinc stearate, titanate, decabromodiphenyl oxide, silane coupling agent modified hydroxide, and red phosphorus.

6. The rubber composition according to claim 1, wherein the flame-retardant agent comprises at least one of nano aluminum oxide, nano magnesium hydroxide, silane coupling agent modified nano hydroxide, and microencapsulated red phosphorus.

7. The rubber composition according to claim 1, further comprising auxiliary components, wherein, based on 100 parts by weight of the rubber matrix, the auxiliary components comprise 0.2 to 10 parts of an auxiliary crosslinking agent, 10 to 150 parts of a reinforcing filler, 5 to 80 parts of a plasticizer, 1 to 3 parts of a stabilizer, 2 to 10 parts of a metal oxide, 1 to 2 parts of a silane coupling agent, 1 to 100 parts of unsaturated carboxylic acid, and 0 to 3 parts of a vulcanization accelerator.

8. The rubber composition according to claim 7, wherein, the auxiliary crosslinking agent comprises at least one of triallyl cyanurate, triallyl isocyanurate, ethylene glycol dimethacrylate, triethylene glycol dimethacrylate, triallyl trimellitate, trimethylolpropane trimethacrylate, N,N′-m-phenylene bismaleimide, N,N′-bis(furfurylidene)acetone, 1,2-polybutadiene, a metal salt of unsaturated carboxylic acid, and sulfur; the reinforcing filler comprises at least one of carbon black, silica, calcium carbonate, talcum powder, calcined clay, and magnesium carbonate, and the calcined clay is zinc stearate or titanate or silane coupling agent modified calcined clay; the plasticizer comprises at least one of pine tar, engine oil, naphthenic oil, paraffin oil, coumarone, stearic acid, and paraffin; the stabilizer comprises at least one of 2,2,4-trimethyl-1,2-dihydroquinoline polymer (RD), 6-ethoxy-2,2,4-trimethyl-1,2-dihydroquinoline (AW), and 2-mercaptobenzimidazole (MB); the metal oxide comprises at least one of zinc oxide, magnesium oxide, and calcium oxide; the silane coupling agent comprises at least one of vinyl tris(2-methoxyethoxy)silane (A-172), γ-glycidyloxypropyl trimethoxysilane (A-187), and γ-mercaptopropyl trimethoxysilane (A-189); the unsaturated carboxylic acid comprises at least one of methacrylic acid, acrylic acid, and undecylenic acid; the vulcanization accelerator comprises at least one of 2-mercaptobenzothiazole, dibenzothiazyl disulfide, tetramethylthiuram monosulfide, tetramethylthiuram disulfide, tetraethylthiuram disulfide, N-cyclohexyl-2-benzothiazolesulfenamide, N,N-dicyclohexyl-2-benzothiazolesulfenamide, bismaleimide, and ethylene thiourea.

9. A flame-retardant wire, comprising a conductor and an insulating layer, wherein, the rubber compound used for the insulating layer comprises the rubber composition according to claim 1.

10. A flame-retardant cable, comprising a conductor, an insulating layer, and a sheath layer, wherein, the rubber compound used for at least one of the insulating layer and the sheath layer comprises the rubber composition according to claim 1.

11. A flame-retardant rubber product, wherein, the rubber compound used for said flame-retardant rubber product comprises the rubber composition according to claim 1.

12. The flame-retardant rubber product according to claim 11, wherein, said flame-retardant rubber product is a flame-retardant cool air hose for automobiles, wherein, the rubber compound used comprises said rubber composition.

13. The flame-retardant rubber product according to claim 11, wherein, said flame-retardant rubber product is a flame-retardant sealing strip, wherein, the rubber compound used for said flame-retardant sealing strip comprises said rubber composition.

14. The flame-retardant rubber product according to claim 11, wherein, said flame-retardant rubber product is a flame-retardant conveyor belt with working surface covering rubber and non-working surface covering rubber, the rubber compound used for at least one of which comprises said rubber composition.

15. The flame-retardant rubber product according to claim 11, wherein, said flame-retardant rubber product is a flame-retardant waterproof coil, wherein, the rubber compound used for said flame-retardant waterproof coil comprises said rubber composition.

16. The flame-retardant rubber product according to claim 1, wherein, the flame-retardant agent comprises zinc stearate.

17. The flame-retardant rubber product according to claim 1, wherein, the flame-retardant agent comprises silane coupling agent modified hydroxide.

18. The flame-retardant rubber product according to claim 1, wherein, the flame-retardant agent comprises silane coupling agent modified aluminum hydroxide.

19. The flame-retardant rubber product according to claim 1, wherein, the flame-retardant agent comprises red phosphorus.

20. The flame-retardant rubber product according to claim 1, wherein, the flame-retardant agent comprises decabromodiphenyl oxide.

Description

DETAILED DESCRIPTION

(1) The present invention is further described through embodiments, but such embodiments are not intended to limit the scope of the present invention. Some non-essential improvements and adjustments made by those skilled in the art to the present invention shall also fall within the protection scope of the present invention.

(2) In order to more clearly describe the embodiments of the present invention, the materials involved in the present invention are defined below.

(3) The crosslinking system includes a crosslinking agent and can also include at least one of an auxiliary crosslinking agent and a vulcanization accelerator.

(4) The Mooney viscosity ML(1+4) at 125° C. of the used EPM is preferably 20 to 50, and the ethylene content is preferably 45% to 60%. The Mooney viscosity ML(1+4) at 125° C. of the used EPDM is preferably 20 to 100 and further preferably 30 to 80, the ethylene content is preferably 55 to 75%, the third monomer is 5-ethylidene-2-norbornene, 5-vinyl-2-norbornene or dicyclopentadiene, and the content of the third monomer is 1% to 7%.

(5) The used branched polyethylene can be obtained by catalyzing ethylene homopolymerization by an (α-diimine) nickel catalyst under the action of a co-catalyst.

(6) The structure and synthesis method of the used (α-diimine) nickel catalyst and the method for preparing the branched polyethylene by the (α-diimine) nickel catalyst are disclosed in the prior art, and can use but are not limited to the following literatures: CN102827312A, CN101812145A, CN101531725A, CN104926962A, U.S. Pat. Nos. 6/103,658, 6/660,677.

(7) The used branched polyethylene has the characteristics that the degree of branching is 60 to 130 branches/1000 carbon atoms, the weight average molecular weight is 66,000 to 518,000, and the Mooney viscosity ML(1+4) at 125° C. is 6 to 102. The degree of branching is measured by means of nuclear magnetic hydrogen spectroscopy, and the molar percentages of various branches are measured by means of nuclear magnetic carbon spectroscopy.

(8) Specific details are as follows:

(9) TABLE-US-00001 Weight Mooney Branched average Molecular viscosity ML polyethylene Degree of Hexyl or molecular weight (1 + 4) No. branching Methyl/% Ethyl/% Propyl/% Butyl/% Pentyl/% higher/% weight/10,000 distribution 125° C. PER-1 130 46.8 18.3 8.3 6.7 5.2 14.7 6.6 2.2 6 PER-2 116 51.2 17.6 8.2 5.8 5.1 12.1 20.1 2.1 23 PER-3 105 54.0 13.7 6.4 5.3 5.1 15.5 26.8 2.1 42 PER-4 102 56.2 12.9 6.2 5.2 4.9 14.6 27.9 2.1 52 PER-5 99 59.6 11.6 5.8 4.9 5.1 13.0 28.3 1.8 63 PER-6 90 62.1 9.4 5.4 4.6 4.5 14.0 32.1 2.1 77 PER-7 82 64.2 8.7 5.3 4.2 3.9 13.7 35.6 1.7 80 PER-8 70 66.5 7.2 4.6 3.2 3.2 15.3 43.6 2.1 93 PER-9 60 68.1 7.1 4.2 2.7 2.8 15.1 51.8 2.2 102 PER-10 87 61.8 10.3 5.4 4.6 4.9 12.0 40.1 1.8 101 PER-11 94 60.5 10.8 5.7 4.7 4.9 13.3 37.8 2.0 85 PER-12 102 56.8 12.7 6.1 5.2 5.1 13.9 34.8 1.9 66

(10) Rubber performance test method:

(11) 1. Hardness test: the test is performed by using a hardness tester in accordance with the national standard GB/T 531.1-2008, wherein the test temperature is room temperature.

(12) 2. Tensile strength and elongation at break performance test: the test is performed by using an electronic tensile tester in accordance with the national standard GB/T528-2009, wherein the tensile speed is 500 mm/min, the test temperature is 23±2° C., and the sample is a type 2 dumbbell-shaped sample.

(13) 3. Mooney viscosity test: the test is performed by using a Mooney viscosity tester in accordance with the national standard GB/T1232.1-2000, wherein the test temperature is 125° C., the preheating time is 1 min, and the test time is 4 min.

(14) 4. Hot air accelerated aging test: the test is performed in a heat aging test box in accordance with the national standard GB/T3512-2001, wherein the test condition is 150° C.*72 h.

(15) 5. Volume resistivity test: the test is performed by using a megger in accordance with the national standard GB/T1692-2008.

(16) 6. The oxygen index is tested in accordance with the national standard GB/T2046.2-2009.

(17) The specific embodiment of the rubber composition provided by the present invention is as follows: the rubber composition includes a rubber matrix and essential components. The rubber matrix includes: A parts of branched polyethylene, in which 0<A≤100, wherein the degree of branching is 60 to 130 branches/1000 carbon atoms, the weight average molecular weight is 66,000 to 518,000, and the Mooney viscosity ML(1+4) at 125° C. is 6 to 102; and

(18) B parts of EPM and EPDM, in which 0≤B<100, wherein the Mooney viscosity ML(1+4) at 125° C. is 20 to 50, and the ethylene content is 55% to 75%.

(19) The essential components include 1.5 to 10 parts of a crosslinking agent and 40 to 300 parts of a flame-retardant agent, and preferably, 60 to 200 parts of a flame-retardant agent.

(20) The rubber composition also includes auxiliary components. The auxiliary components include 0.2 to 10 parts of an auxiliary crosslinking agent, 10 to 150 parts of a reinforcing filler, 5 to 80 parts of a plasticizer, 1 to 3 parts of a stabilizer, 2 to 10 parts of a metal oxide, 1 to 2 parts of a silane coupling agent, 1 to 100 parts of unsaturated carboxylic acid, and 0 to 3 parts of a vulcanization accelerator. The flame-retardant agent includes at least one of aluminum hydroxide, magnesium hydroxide, zinc borate, antimonous oxide, zinc stearate, titanate, silane coupling agent modified hydroxide, and red phosphorus.

(21) In a preferred embodiment, the aluminum hydroxide, the magnesium hydroxide, and the silane coupling agent modified hydroxide are respectively nano aluminum oxide, nano magnesium hydroxide, and silane coupling agent modified nano hydroxide, and the red phosphorus is microencapsulated red phosphorus.

(22) The silane coupling agent includes at least one of vinyl tris(2-methoxyethoxy)silane (A-172), γ-glycidyloxypropyl trimethoxysilane (A-187), and γ-mercaptopropyl trimethoxysilane (A-189).

(23) The unsaturated carboxylic acid includes at least one of methacrylic acid, acrylic acid, and undecylenic acid.

(24) The stabilizer includes at least one of 2,2,4-trimethyl-1,2-dihydroquinoline polymer (RD), 6-ethoxy-2,2,4-trimethyl-1,2-dihydroquinoline (AW), and 2-mercaptobenzimidazole (MB).

(25) The auxiliary crosslinking agent includes at least one of triallyl cyanurate, triallyl isocyanurate, ethylene glycol dimethacrylate, triethylene glycol dimethacrylate, triallyl trimellitate, trimethylolpropane trimethacrylate, N,N′-m-phenylene bismaleimide, N,N′-bis(furfurylidene)acetone, 1,2-polybutadiene, zinc acrylate, zinc methacrylate, magnesium methacrylate, calcium methacrylate, aluminum methacrylate, and sulfur.

(26) The plasticizer includes at least one of pine tar, engine oil, naphthenic oil, paraffin oil, coumarone resin, RX-80, stearic acid, and paraffin. The metal oxide includes at least one of zinc oxide, magnesium oxide, and calcium oxide.

(27) The reinforcing filler includes at least one of carbon black, silica, calcium carbonate, talcum powder, calcined clay, and magnesium carbonate, and the calcined clay is zinc stearate or titanate or silane coupling agent modified calcined clay. The crosslinking agent includes at least one of a peroxide crosslinking agent and sulfur.

(28) The peroxide crosslinking agent includes at least one of di-tert-butyl peroxide, dicumyl peroxide, tert-butyl cumyl peroxide, 1,1-di-tert-butyl peroxide-3,3,5-trimethylcyclohexane, 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane, 2,5-dimethyl-2,5-di(tert-butylperoxy)hexyne-3, bis(tert-butylperoxyisopropyl)benzene, 2,5-dimethyl-2,5-bis(benzoylperoxy)hexane, tert-butyl peroxybenzoate, and tert-butylperoxy-2-ethylhexyl carbonate.

(29) The vulcanization accelerator includes at least one of 2-mercaptobenzothiazole, dibenzothiazyl disulfide, tetramethylthiuram monosulfide, tetramethylthiuram disulfide, tetraethylthiuram disulfide, N-cyclohexyl-2-benzothiazolesulfenamide, N,N-dicyclohexyl-2-benzothiazolesulfenamide, bismaleimide, and ethylene thiourea.

(30) In order to test the performance of the rubber composition, the specific embodiment of the present invention also provides examples of processing methods of the rubber composition. The examples are as follows:

Example 1

(31) Branched polyethylene No. PER-9 was used.

(32) The processing steps of the rubber composition were as follows:

(33) (1) rubber mixing: the temperature of an internal mixer was set to be 90° C. and the rotor speed was set to be 50 r/min, 90 parts of EPDM and 10 parts of branched polyethylene were added, and pre-pressing and mixing were performed for 90 s; 5 parts of zinc oxide and 3 parts of an anti-aging agent RD were added, and mixing was performed for 1 min; then, 170 parts of zinc stearate modified aluminum hydroxide, 5 parts of zinc borate, 10 parts of antimonous oxide, 2 parts of a silane coupling agent (A-172), 30 parts of calcined clay, and 20 parts of paraffin oil SUNPAR2280 were added to the rubber compound, and mixing was performed for 3 min; finally, 3 parts of a crosslinking agent dicumyl peroxide (DCP) and 2 parts of an auxiliary crosslinking agent triallyl isocyanurate (TAIC) were added, mixing was performed for 2 min, and then, the rubber was discharged; the rubber mix was plasticated on an open mill of which the roller temperature was 60° C. to obtain a sheet of which the thickness was about 2.5 mm, the sheet was unloaded, and the sheet was allowed to stand for 20 h;

(34) (2) vulcanization was performed, the vulcanized product was allowed to stand for 16 h, and then, various tests were performed.

Example 2

(35) Branched polyethylene No. PER-2 was used.

(36) The processing steps of the rubber composition were as follows:

(37) (1) rubber mixing: the temperature of an internal mixer was set to be 90° C. and the rotor speed was set to be 50 r/min, 20 parts of EPM, 50 parts of EPDM, and 30 parts of branched polyethylene were added, and mixing was performed for 90 s; then, 10 parts of zinc oxide and 3 parts of an anti-aging agent RD were added, and mixing was performed for 1 min; 180 parts of aluminum hydroxide, 10 parts of methacrylic acid, 2 parts of a silane coupling agent (A-172), and 20 parts of magnesium carbonate were added to the rubber compound, and mixing was performed for 3 min; finally, 3 parts of a crosslinking agent dicumyl peroxide (DCP) and 2 parts of an auxiliary crosslinking agent triallyl isocyanurate (TAIC) were added, mixing was performed for 2 min, and then, the rubber was discharged; the rubber mix was plasticated on an open mill of which the roller temperature was 60° C. to obtain a sheet of which the thickness was about 2.5 mm, the sheet was unloaded, and the sheet was allowed to stand for 20 h;

(38) (2) vulcanization was performed, the vulcanized product was allowed to stand for 16 h, and then, various tests were performed.

Example 3

(39) Branched polyethylene No. PER-4 was used.

(40) The processing steps of the rubber composition were as follows:

(41) (1) rubber mixing: the temperature of an internal mixer was set to be 90° C. and the rotor speed was set to be 50 r/min, 30 parts of EPM and 70 parts of branched polyethylene were added, and pre-pressing and mixing were performed for 90 s; 5 parts of zinc oxide and 3 parts of an anti-aging agent RD were added, and mixing was performed for 1 min; then, 250 parts of silane coupling agent modified aluminum hydroxide, 30 parts of zinc borate, 20 parts of antimonous oxide, and 5 parts of paraffin oil were added to the rubber compound, and mixing was performed for 3 min; finally, 3 parts of a crosslinking agent dicumyl peroxide (DCP) and 2 parts of an auxiliary crosslinking agent triallyl isocyanurate (TAIC) were added, mixing was performed for 2 min, and then, the rubber was discharged; the rubber mix was plasticated on an open mill of which the roller temperature was 60° C. to obtain a sheet of which the thickness was about 2.5 mm, the sheet was unloaded, and the sheet was allowed to stand for 20 h;

(42) (2) vulcanization was performed, the vulcanized product was allowed to stand for 16 h, and then, various tests were performed.

Example 4

(43) Branched polyethylene No. PER-5 was used.

(44) The processing steps of the rubber composition were as follows:

(45) (1) rubber mixing: the temperature of an internal mixer was set to be 90° C. and the rotor speed was set to be 50 r/min, 100 parts of branched polyethylene was added, and pre-pressing and mixing were performed for 90 s; 5 parts of zinc oxide and 3 parts of an anti-aging agent RD were added, and mixing was performed for 1 min; then, 200 parts of silane coupling agent modified aluminum hydroxide and 5 parts of paraffin oil SUNPAR2280 were added to the rubber compound, and mixing was performed for 3 min; finally, 3 parts of a crosslinking agent dicumyl peroxide (DCP), 8 parts of an auxiliary crosslinking agent liquid 1,2-polybutadiene, and 2 parts of an auxiliary crosslinking agent triallyl isocyanurate (TAIC) were added, mixing was performed for 2 min, and then, the rubber was discharged; the rubber mix was plasticated on an open mill of which the roller temperature was 60° C. to obtain a sheet of which the thickness was about 2.5 mm, the sheet was unloaded, and the sheet was allowed to stand for 20 h;

(46) (2) vulcanization was performed, the vulcanized product was allowed to stand for 16 h, and then, various tests were performed.

Example 5

(47) Branched polyethylene No. PER-3 was used.

(48) The processing steps of the rubber composition were as follows:

(49) (1) rubber mixing: the temperature of an internal mixer was set to be 90° C. and the rotor speed was set to be 50 r/min, 100 parts of branched polyethylene was added, and pre-pressing and mixing were performed for 90 s; then, 200 parts of silane coupling agent modified aluminum hydroxide and 10 parts of paraffin oil SUNPAR2280 were added to the rubber compound, and mixing was performed for 3 min; finally, 1 part of a crosslinking agent dicumyl peroxide (DCP), 0.3 part of an auxiliary crosslinking agent triallyl isocyanurate (TAIC), 0.5 part of a crosslinking agent sulfur, 1 part of N-cyclohexyl-2-benzothiazole sulfenamide (CZ), and 0.8 part of tetramethylthiuram disulfide (TMTD) were added, mixing was performed for 2 min, and then, the rubber was discharged; the rubber mix was plasticated on an open mill of which the roller temperature was 60° C. to obtain a sheet of which the thickness was about 2.5 mm, the sheet was unloaded, and the sheet was allowed to stand for 20 h;

(50) (2) vulcanization was performed, the vulcanized product was allowed to stand for 16 h, and then, various tests were performed.

Example 6

(51) Branched polyethylene No. PER-3 was used.

(52) The processing steps of the rubber composition were as follows:

(53) (1) rubber mixing: the temperature of an internal mixer was set to be 90° C. and the rotor speed was set to be 50 r/min, 100 parts of branched polyethylene was added, and pre-pressing and mixing were performed for 90 s; 2 parts of an anti-aging agent RD was added, and mixing was performed for 1 min; then, 200 parts of silane coupling agent modified aluminum hydroxide and 30 parts of methacrylic acid were added to the rubber compound, and mixing was performed for 3 min; finally, 3 parts of a crosslinking agent dicumyl peroxide (DCP) and 2 parts of an auxiliary crosslinking agent triallyl isocyanurate (TAIC) were added, mixing was performed for 2 min, and then, the rubber was discharged; the rubber mix was plasticated on an open mill of which the roller temperature was 60° C. to obtain a sheet of which the thickness was about 2.5 mm, the sheet was unloaded, and the sheet was allowed to stand for 20 h;

(54) (2) vulcanization was performed, the vulcanized product was allowed to stand for 16 h, and then, various tests were performed.

Comparative Example 1

(55) The processing steps of the rubber composition were as follows:

(56) (1) rubber mixing: the temperature of an internal mixer was set to be 90° C. and the rotor speed was set to be 50 r/min, 100 parts of EPDM was added, and pre-pressing and mixing were performed for 90 s; 5 parts of zinc oxide and 3 parts of an anti-aging agent RD were added, and mixing was performed for 1 min; then, 200 parts of silane coupling agent modified aluminum hydroxide and 10 parts of paraffin oil SUNPAR2280 were added to the rubber compound, and mixing was performed for 3 min; finally, 3 parts of a crosslinking agent dicumyl peroxide (DCP) and 2 parts of an auxiliary crosslinking agent triallyl isocyanurate (TAIC) were added, mixing was performed for 2 min, and then, the rubber was discharged; the rubber mix was plasticated on an open mill of which the roller temperature was 60° C. to obtain a sheet of which the thickness was about 2.5 mm, the sheet was unloaded, and the sheet was allowed to stand for 20 h;

(57) (2) vulcanization was performed, the vulcanized product was allowed to stand for 16 h, and then, various tests were performed.

(58) Performance test data of Examples 1 to 6 and Comparative example 1

(59) TABLE-US-00002 Comparative Example Example Example Example Example Example Test item example 1 1 2 3 4 5 6 Hardness 75 81 74 77 72 73 77 Tensile strength/MPa 6.6 7.6 9.8 10.6 12.5 11.6 14.5 Elongation at break/% 230 218 256 214 288 292 234 Oxygen index/% 32 35 31 36 32 32 33 Volume resistivity/Ω .Math. cm 4.1 × 10{circumflex over ( )}14 4.0 × 10{circumflex over ( )}14 6.8 × 10{circumflex over ( )}14 4.9 × 10{circumflex over ( )}14 5.8 × 10{circumflex over ( )}14 2.6 × 10{circumflex over ( )}14 7.1 × 10{circumflex over ( )}14 After aging (150° C.*72 h) Hardness 77 83 76 75 74 75 78 Retention rate of tensile strength/% 105 104 105 103 101 93 103 Retention rate of elongation at break/% 95 96 94 95 96 91 101

(60) Data analysis: comparing Examples 1 to 4 with Comparative example 1, it can be found that as the proportion of the branched polyethylene replacing the ethylene propylene rubber increased, the mechanical strength and volume resistivity of the vulcanized rubber were obviously improved, and the aging resistance and the flame resistance have no obvious change, indicating that the new rubber composition provided by the present invention was suitable for producing flame-retardant cables.

Example 7

(61) Branched polyethylene No. PER-5 was used.

(62) The processing steps of the rubber composition were as follows:

(63) (1) rubber mixing: the temperature of an internal mixer was set to be 90° C. and the rotor speed was set to be 50 r/min, 50 parts of EPDM and 50 parts of branched polyethylene were added, and pre-pressing and mixing were performed for 90 s; 5 parts of zinc oxide, 2 parts of stearic acid, and 2 parts of an anti-aging agent RD were added, and mixing was performed for 1 min; then, 160 parts of silane coupling agent modified aluminum hydroxide, 40 parts of carbon black N550, 20 parts of calcined clay, and 20 parts of paraffin oil SUNPAR2280 were added to the rubber compound, and mixing was performed for 3 min; finally, 3 parts of a crosslinking agent dicumyl peroxide (DCP), 1 part of an auxiliary crosslinking agent triallyl isocyanurate (TAIC), and 0.2 part of sulfur were added, mixing was performed for 2 min, and then, the rubber was discharged; the rubber mix was plasticated on an open mill of which the roller temperature was 60° C. to obtain a sheet of which the thickness was about 2.5 mm, the sheet was unloaded, and the sheet was allowed to stand for 20 h;

(64) (2) vulcanization was performed, the vulcanized product was allowed to stand for 16 h, and then, various tests were performed.

Example 8

(65) Branched polyethylene No. PER-5 was used.

(66) The processing steps of the rubber composition were as follows:

(67) (1) rubber mixing: the temperature of an internal mixer was set to be 90° C. and the rotor speed was set to be 50 r/min, 100 parts of branched polyethylene was added, and pre-pressing and mixing were performed for 90 s; 5 parts of zinc oxide, 2 parts of stearic acid, and 2 parts of an anti-aging agent RD were added, and mixing was performed for 1 min; then, 160 parts of silane coupling agent modified aluminum hydroxide, 40 parts of carbon black N550, 20 parts of calcined clay, and 20 parts of paraffin oil SUNPAR2280 were added to the rubber compound, and mixing was performed for 3 min; finally, 3 parts of a crosslinking agent dicumyl peroxide (DCP), 1 part of an auxiliary crosslinking agent triallyl isocyanurate (TAIC), and 0.2 part of sulfur were added, mixing was performed for 2 min, and then, the rubber was discharged; the rubber mix was plasticated on an open mill of which the roller temperature was 60° C. to obtain a sheet of which the thickness was about 2.5 mm, the sheet was unloaded, and the sheet was allowed to stand for 20 h;

(68) (2) vulcanization was performed, the vulcanized product was allowed to stand for 16 h, and then, various tests were performed.

Example 9

(69) Branched polyethylene No. PER-6 was used.

(70) The processing steps of the rubber composition were as follows:

(71) (1) rubber mixing: the temperature of an internal mixer was set to be 90° C. and the rotor speed was set to be 50 r/min, 70 parts of EPM and 30 parts of branched polyethylene were added, and pre-pressing and mixing were performed for 90 s; 5 parts of zinc oxide, 2 parts of stearic acid, and 2 parts of an anti-aging agent RD were added, and mixing was performed for 1 min; then, 60 parts of silane coupling agent modified aluminum hydroxide, 80 parts of carbon black N550, 30 parts of calcined clay, and 15 parts of paraffin oil SUNPAR2280 were added to the rubber compound, and mixing was performed for 3 min; finally, 3 parts of a crosslinking agent dicumyl peroxide (DCP), 1 part of an auxiliary crosslinking agent triallyl isocyanurate (TAIC), and 0.2 part of sulfur were added, mixing was performed for 2 min, and then, the rubber was discharged; the rubber mix was plasticated on an open mill of which the roller temperature was 60° C. to obtain a sheet of which the thickness was about 2.5 mm, the sheet was unloaded, and the sheet was allowed to stand for 20 h;

(72) (2) vulcanization was performed, the vulcanized product was allowed to stand for 16 h, and then, various tests were performed.

Example 10

(73) Branched polyethylene No. PER-8 was used.

(74) The processing steps of the rubber composition were as follows:

(75) (1) rubber mixing: the temperature of an internal mixer was set to be 90° C. and the rotor speed was set to be 50 r/min, 20 parts of EPM, 30 parts of EPDM, and 50 parts of branched polyethylene were added, and pre-pressing and mixing were performed for 90 s; 5 parts of zinc oxide, 2 parts of stearic acid, and 2 parts of an anti-aging agent RD were added, and mixing was performed for 1 min; then, 160 parts of silane coupling agent modified aluminum hydroxide, 2 parts of a silane coupling agent (A-172), 80 parts of carbon black N550, 40 parts of calcined clay, and 40 parts of paraffin oil SUNPAR2280 were added to the rubber compound, and mixing was performed for 3 min; finally, 10 parts of a crosslinking agent dicumyl peroxide (DCP) and 5 parts of an auxiliary crosslinking agent triallyl isocyanurate (TAIC) were added, mixing was performed for 2 min, and then, the rubber was discharged; the rubber mix was plasticated on an open mill of which the roller temperature was 60° C. to obtain a sheet of which the thickness was about 2.5 mm, the sheet was unloaded, and the sheet was allowed to stand for 20 h;

(76) (2) vulcanization was performed, the vulcanized product was allowed to stand for 16 h, and then, various tests were performed.

Example 11

(77) Branched polyethylene Nos. PER-1 and PER-7 were used.

(78) The processing steps of the rubber composition were as follows:

(79) (1) rubber mixing: the temperature of an internal mixer was set to be 90° C. and the rotor speed was set to be 50 r/min, 100 parts of branched polyethylene was added, and pre-pressing and mixing were performed for 90 s; 5 parts of zinc oxide, 2 parts of stearic acid, and 2 parts of an anti-aging agent RD were added, and mixing was performed for 1 min; then, 150 parts of silane coupling agent modified aluminum hydroxide, 5 parts of zinc borate, 10 parts of antimonous oxide, 20 parts of methacrylic acid, 100 parts of carbon black N550, 30 parts of calcined clay, and 70 parts of paraffin oil SUNPAR2280 were added to the rubber compound, and mixing was performed for 3 min; finally, 8 parts of a crosslinking agent dicumyl peroxide (DCP) and 4 parts of an auxiliary crosslinking agent triallyl isocyanurate (TAIC) were added, mixing was performed for 2 min, and then, the rubber was discharged; the rubber mix was plasticated on an open mill of which the roller temperature was 60° C. to obtain a sheet of which the thickness was about 2.5 mm, the sheet was unloaded, and the sheet was allowed to stand for 20 h;

(80) (2) vulcanization was performed, the vulcanized product was allowed to stand for 16 h, and then, various tests were performed.

Example 12

(81) Branched polyethylene No. PER-3 was used.

(82) The processing steps of the rubber composition were as follows:

(83) (1) rubber mixing: the temperature of an internal mixer was set to be 90° C. and the rotor speed was set to be 50 r/min, 100 parts of branched polyethylene was added, and pre-pressing and mixing were performed for 90 s; 3 parts of zinc oxide, 1 part of stearic acid, and 2 parts of an anti-aging agent RD were added, and mixing was performed for 1 min; then, 160 parts of silane coupling agent modified aluminum hydroxide, 5 parts of zinc borate, 10 parts of antimonous oxide, 40 parts of carbon black N550, 20 parts of calcined clay, and 10 parts of paraffin oil SUNPAR2280 were added to the rubber compound, and mixing was performed for 3 min; finally, 3 parts of a crosslinking agent dicumyl peroxide (DCP), 1 part of an auxiliary crosslinking agent triallyl isocyanurate (TAIC), and 0.2 part of sulfur were added, mixing was performed for 2 min, and then, the rubber was discharged; the rubber mix was plasticated on an open mill of which the roller temperature was 60° C. to obtain a sheet of which the thickness was about 2.5 mm, the sheet was unloaded, and the sheet was allowed to stand for 20 h;

(84) (2) vulcanization was performed, the vulcanized product was allowed to stand for 16 h, and then, various tests were performed.

Comparative Example 2

(85) The processing steps of the rubber composition were as follows:

(86) (1) rubber mixing: the temperature of an internal mixer was set to be 90° C. and the rotor speed was set to be 50 r/min, 100 parts of EPDM was added, and pre-pressing and mixing were performed for 90 s; 5 parts of zinc oxide, 2 parts of stearic acid, and 2 parts of an anti-aging agent RD were added, and mixing was performed for 1 min; then, 160 parts of silane coupling agent modified aluminum hydroxide, 40 parts of carbon black N550, 20 parts of calcined clay, and 20 parts of paraffin oil SUNPAR2280 were added to the rubber compound, and mixing was performed for 3 min; finally, 2 parts of a crosslinking agent dicumyl peroxide (DCP), 1 part of an auxiliary crosslinking agent triallyl isocyanurate (TAIC), and 0.2 part of sulfur were added, mixing was performed for 2 min, and then, the rubber was discharged; the rubber mix was plasticated on an open mill of which the roller temperature was 60° C. to obtain a sheet of which the thickness was about 2.5 mm, the sheet was unloaded, and the sheet was allowed to stand for 20 h;

(87) (2) vulcanization was performed, the vulcanized product was allowed to stand for 16 h, and then, various tests were performed.

(88) TABLE-US-00003 Comparative Example Example Example Laboratory Example Example Test item example 2 7 8 9 10 11 12 Hardness 66 65 64 65 74 73 68 Tensile strength/MPa 8.9 11.4 14.8 11.3 12.5 13.8 10.6 Elongation at break/% 325 347 389 356 259 278 335 Oxygen index/% 34 34 34 30 33 29 35 Compression set/%(70° C.*22 h) 18 16 13 15 14 11 12 After aging (150° C.*72 h) Hardness 68 66 65 69 75 74 69 Retention rate of tensile strength/% 102 103 102 104 104 99 105 Retention rate of elongation at break/% 91 93 94 97 98 97 94

(89) Data analysis: comparing Examples 7 to 12 with Comparative example 2, it can be found that as the proportion of the branched polyethylene replacing the ethylene propylene rubber increased, the mechanical strength of the vulcanized rubber was obviously improved, the compression set was obviously reduced, and the aging resistance and the flame resistance have no obvious change, indicating that the new rubber composition provided by the present invention was suitable for application occasions having requirements for mechanical strength and compression set, such as production of flame-retardant sealing strips, flame-retardant rubber hoses, flame-retardant conveyor belts, flame-retardant rubber plates, and the like.

(90) The embodiment of the present invention also provides an application of the rubber composition. The application refers to production and processing of flame-retardant products. The flame-retardant products include flame-retardant cables, flame-retardant cool air hoses for automobiles, flame-retardant sealing strips, high-temperature-resistant flame-retardant conveyor belts, and flame-retardant waterproof coil.

(91) The examples of production and processing methods of the flame-retardant products were as follows:

Example 13

(92) The present example is a flame-retardant cable. A production process thereof was as follows:

(93) (1) stranding was performed; (2) a rubber insulating layer was extruded; (3) vulcanization was performed; (4) a spark high-pressure test was performed; (5) the cable was formed; (6) a rubber sheath was extruded; (7) vulcanization was performed; (8) lettering was performed; (9) a finished product was obtained. The rubber compound used for extruding the rubber insulating layer was obtained by the following steps: the temperature of an internal mixer was set to be 90° C. and the rotor speed was set to be 50 r/min, 100 parts of branched polyethylene PER-5 was added, and pre-pressing and mixing were performed for 90 s; 5 parts of zinc oxide and 3 parts of an anti-aging agent RD were added, and mixing was performed for 1 min; then, 200 parts of silane coupling agent modified aluminum hydroxide and 5 parts of paraffin oil SUNPAR2280 were added to the rubber compound, and mixing was performed for 3 min; finally, 3 parts of a crosslinking agent dicumyl peroxide (DCP) and 2 parts of an auxiliary crosslinking agent triallyl isocyanurate (TAIC) were added, mixing was performed for 2 min, and then, the rubber was discharged.

Example 14

(94) The present example is a flame-retardant cable and a production method thereof comprises the following steps:

(95) (1) stranding was performed; (2) a rubber insulating layer was extruded; (3) vulcanization was performed; (4) a spark high-pressure test was performed; (5) the cable was formed; (6) a rubber sheath was extruded; (7) vulcanization was performed; (8) lettering was performed; (9) a finished product was obtained. The rubber compound used for extruding the rubber sheath was obtained by the following processes: the temperature of an internal mixer was set to be 90° C. and the rotor speed was set to be 50 r/min, 100 parts of branched polyethylene PER-5 was added, and pre-pressing and mixing were performed for 90 s; 5 parts of zinc oxide and 3 parts of an anti-aging agent RD were added, and mixing was performed for 1 min; then, 200 parts of silane coupling agent modified aluminum hydroxide, 5 parts of carbon black N550, and 5 parts of paraffin oil SUNPAR2280 were added to the rubber compound, and mixing was performed for 3 min; finally, 3 parts of a crosslinking agent dicumyl peroxide (DCP) and 2 parts of an auxiliary crosslinking agent triallyl isocyanurate (TAIC) were added, mixing was performed for 2 min, and then, the rubber was discharged.

Example 15

(96) The present example is a flame-retardant cool air hose for automobiles, which is an all rubber hose and formed by only one layer of rubber. The used rubber composition and production processes were as follows: the temperature of an internal mixer was set to be 90° C. and the rotor speed was set to be 50 r/min, 100 parts of branched polyethylene PER-5 was added, and pre-pressing and mixing were performed for 90 s; 5 parts of zinc oxide, 2 parts of stearic acid, and 2 parts of an anti-aging agent RD were added, and mixing was performed for 1 min; then, 150 parts of silane coupling agent modified aluminum hydroxide, 5 parts of zinc borate, 10 parts of antimonous oxide, 20 parts of methacrylic acid, 100 parts of carbon black N550, 30 parts of calcined clay, and 30 parts of paraffin oil SUNPAR2280 were added to the rubber compound, and mixing was performed for 3 min; finally, 8 parts of a crosslinking agent dicumyl peroxide (DCP), 4 part of an auxiliary crosslinking agent triallyl isocyanurate (TAIC), and 0.2 part of sulfur were added, mixing was performed for 2 min, and then, the rubber was discharged; the rubber mix was put into an extruder so as to be extruded, and then, the extruded product was vulcanized in a nitrogen-filled vulcanization tank to obtain the flame-retardant cool air hose for automobiles.

Example 16

(97) The present example is a flame-retardant sealing strip, and a production method thereof comprises the following steps:

(98) (1) mixing: the temperature of an internal mixer was set to be 90° C. and the rotor speed was set to be 50 r/min, 100 parts of branched polyethylene PER-3 was added, and pre-pressing and mixing were performed for 90 s; 3 parts of zinc oxide, 1 part of stearic acid, and 2 parts of an anti-aging agent RD were added, and mixing was performed for 1 min; then, 160 parts of silane coupling agent modified aluminum hydroxide, 5 parts of zinc borate, 10 parts of antimonous oxide, 40 parts of carbon black N550, 20 parts of calcined clay, and 20 parts of paraffin oil SUNPAR2280 were added to the rubber compound, and mixing was performed for 3 min; finally, 3 parts of a crosslinking agent dicumyl peroxide (DCP), 1 part of an auxiliary crosslinking agent triallyl isocyanurate (TAIC), and 0.2 part of sulfur were added, mixing was performed for 2 min, and then, the rubber was discharged; the rubber mix was automatically discharged to a double screw extruder so as to be extruded into a sheet, the rubber mix was continuously cooled in a rubber sheet cooling machine, and the rubber mix was automatically discharged to a pallet so as to be packaged and formed after the rubber mix was cooled to room temperature;

(99) (2) extrusion and vulcanization: in extrusion and vulcanization processes, a vacuumizing extruder was preferably used, wherein the head temperature of the extruder was set to be 90 to 100° C., the screw temperature was set to be 70 to 80° C., the head pressure was controlled at 15 to 20 MPa, and the rotation speed of the extruder was 25 to 30 r/min; a salt bath vulcanization process was used, wherein the temperature of a spraying section was 250° C., the temperature of a steeping section was 220° C., the temperature of a steeping press section was 220° C., the transmission speed was 35 to 45 m/min, and the temperature of a cooling section was 25 to 30° C.; the flame-retardant sealing strip was obtained.

Example 17

(100) For a high-temperature-resistant flame-retardant conveyor belt, a belt core tensile canvas is arranged between the working surface covering rubber and the non-working surface covering rubber, and the working surface covering rubber, the belt core tensile canvas, and the non-working surface covering rubber were formed into a firm whole by means of forming and vulcanization processes. The components and proportions of the working surface covering rubber in the examples of the present invention were metered by parts:

(101) (1) rubber mixing process:

(102) the temperature of an internal mixer was set to be 90° C. and the rotor speed was set to be 50 r/min, 100 parts of branched polyethylene PER-5 was added, and pre-pressing and mixing were performed for 90 s; 5 parts of zinc oxide, 2 parts of stearic acid, and 2 parts of an anti-aging agent RD were added, and mixing was performed for 1 min; then, 60 parts of silane coupling agent modified aluminum hydroxide, 80 parts of carbon black N550, 30 parts of calcined clay, and 15 parts of paraffin oil SUNPAR2280 were added to the rubber compound, and mixing was performed for 3 min; finally, 3 parts of a crosslinking agent dicumyl peroxide (DCP), 1 part of an auxiliary crosslinking agent triallyl isocyanurate (TAIC), and 0.2 part of sulfur were added, mixing was performed for 2 min, and then, the rubber was discharged;

(103) (2) calendering process:

(104) the rubber mix was put into a screw extruder so as to be subjected to hot milling, then, the rubber mix was conveyed into a calender so as to be calendered, and then, a sheet was discharged for later use; the thickness of the rubber sheet was controlled to be 4.5 to 12 mm in the processes of calendering and discharging the sheet; after the sheet was discharged, the temperature of the sheet was kept for later use;

(105) (3) forming process:

(106) the rubber sheet and a preformed rubberized canvas belt blank were closely attached together on a forming machine to form a belt blank of a high-temperature-resistant flame-retardant conveyor belt, the belt blank was coiled, and after 4 h, the coiled belt blank was vulcanized;

(107) (4) vulcanization process:

(108) the formed belt blank of the conveyor belt was put into a press vulcanizer so as to be vulcanized in sections, wherein for each plate, the vulcanization time was 25 min, the vulcanization pressure was 3 MPa, and the vulcanization temperature was 160° C.;

(109) (5) trimming and inspecting:

(110) after vulcanization, trimming and inspecting were performed, and then, packaging and warehousing were performed.

Example 18

(111) The present example is a flame-retardant waterproof coil, and a production method thereof comprises the following steps:

(112) (1) mixing: the temperature of an internal mixer was set to be 90° C. and the rotor speed was set to be 50 r/min, 100 parts of branched polyethylene PER-4 was added, and pre-pressing and mixing were performed for 90 s; 5 parts of zinc oxide, 2 parts of stearic acid, and 2 parts of an anti-aging agent RD were added, and mixing was performed for 1 min; then, 40 parts of silane coupling agent modified aluminum hydroxide, 40 parts of carbon black N550, 30 parts of calcined clay, and 15 parts of paraffin oil SUNPAR2280 were added to the rubber compound, and mixing was performed for 3 min; finally, 3 parts of a crosslinking agent dicumyl peroxide (DCP), 1 part of an auxiliary crosslinking agent triallyl isocyanurate (TAIC), and 0.2 part of sulfur were added, mixing was performed for 2 min, and then, the rubber was discharged; a blocky rubber compound was conveyed into an open mill so as to be mixed, the roller temperature was controlled to be between 85° C. and 95° C., the roller spacing was controlled to be less than 1 mm, the rubber compound was plasticated at least four times until the surface of the rubber compound was smooth, uniform and glossy, then, the rubber compound was further mixed and plasticated at least four times, the roller spacing was adjusted to be not greater than 8 mm, mixing was performed three times to obtain a uniformly-mixed rubber compound rough sheet of which the thickness was less than 8 mm, the sheet was cooled to 50° C. or below, and then, the sheet was discharged and stacked;

(113) (2) hot milling: hot milling was performed on the uniformly-mixed rubber compound rough sheet on an open mill, the roller temperature was controlled to be between 85° C. and 95° C., the roller spacing was controlled to be less than 6 mm until the rubber compound sheet was smooth and uniform, and then, the sheet was preliminarily coiled;

(114) (3) calendering: the rubber compound sheet which was preliminarily coiled by means of hot milling was put on a calender, and the roller spacing was adjusted according to the thickness requirement of a finished product to perform calendering so as to obtain a semi-finished coil meeting the thickness specification requirement of the finished product;

(115) (4) coiling: an isolation liner layer was sandwiched according to the specification length requirement of the finished coil, and the semi-finished coil was tidied into a coil;

(116) (5) vulcanization: the coil which was tidied into a coil was put into a vulcanization kettle so as to be vulcanized, the temperature of the vulcanization kettle was controlled to be between 155° C. and 165° C., the pressure of the vulcanization kettle was controlled to be 20 MPa and 50 MPa, and vulcanization was performed for 25 to 30 min;

(117) (6) recoiling: the vulcanized coil was uncoiled again, the isolation liner layer was taken out, and then, the coil was recoiled and packaged to obtain a product.

Example 19

(118) The present example is a flame-retardant damping rubber gasket, and a production method thereof comprises the following steps:

(119) (1) mixing: the temperature of an internal mixer was set to be 100° C. and the rotor speed was set to be 50 r/min, 100 parts of branched polyethylene PER-10 was added, and pre-pressing and mixing were performed for 90 s; 8 parts of zinc oxide, 1.5 parts of stearic acid, 1 part of an anti-aging agent RD, and 1 part of an anti-aging agent MB were added, and mixing was performed for 1 min; then, 100 parts of zinc stearate modified aluminum hydroxide, 5 parts of zinc borate, 10 parts of antimonous oxide, 2 parts of a silane coupling agent (A-172), 30 parts of calcined clay, and 35 parts of paraffin oil SUNPAR2280 were added to the rubber compound, and mixing was performed for 3 min; finally, 3 parts of a crosslinking agent dicumyl peroxide (DCP), 0.3 part of sulfur, and 1.2 parts of an auxiliary crosslinking agent triallyl isocyanurate (TAIC) were added, mixing was performed for 2 min, and then, the rubber was discharged; the rubber mix was plasticated on an open mill of which the roller temperature was 75° C. to obtain a sheet of which the thickness was about 2.5 mm, the sheet was unloaded, and the sheet was allowed to stand for 20 h;

(120) (2) forming: the mixed rubber sheet was calendered and attached to obtain a semi-finished product of which the thickness was slightly higher than the required specification;

(121) (3) vulcanization: mold pressing vulcanization was performed for 15 min at 170° C., and the mold was opened to take out vulcanized rubber;

(122) (4) the vulcanized rubber was trimmed, and then, was packaged and warehoused.

Example 20

(123) The present example is a flame-retardant sealing strip and a production method thereof comprises the following steps:

(124) (1) mixing: the temperature of an internal mixer was set to be 90° C. and the rotor speed was set to be 50 r/min, 100 parts of branched polyethylene PER-11 was added, and pre-pressing and mixing were performed for 90 s; 3 parts of zinc oxide, 1 part of stearic acid, 1 part of an anti-aging agent RD, and 1 part of an anti-aging agent MB were added, and mixing was performed for 1 min; then, 160 parts of silane coupling agent modified aluminum hydroxide, 5 parts of zinc borate, 10 parts of antimonous oxide, 40 parts of carbon black N550, 20 parts of calcined clay, and 60 parts of paraffin oil SUNPAR2280 were added to the rubber compound, and mixing was performed for 3 min; finally, 3 parts of a crosslinking agent dicumyl peroxide (DCP), 1 part of an auxiliary crosslinking agent triallyl isocyanurate (TAIC), and 0.2 part of sulfur were added, mixing was performed for 2 min, and then, the rubber was discharged; the rubber mix was automatically discharged to a double screw extruder so as to be extruded into a sheet, the rubber mix was continuously cooled in a rubber sheet cooling machine, and the rubber mix was automatically discharged to a pallet so as to be packaged and formed after the rubber mix was cooled to room temperature;

(125) (2) extrusion and vulcanization: in extrusion and vulcanization processes, a vacuumizing extruder was preferably used, wherein the head temperature of the extruder was set to be 90 to 100° C., the screw temperature was set to be 70 to 80° C., the head pressure was controlled at 15 to 20 MPa, and the rotation speed of the extruder was 25 to 30 r/min; a salt bath vulcanization process was used, wherein the temperature of a spraying section was 250° C., the temperature of a steeping section was 220° C., the temperature of a steeping press section was 220° C., the transmission speed was 35 to 45 m/min, and the temperature of a cooling section was 25 to 30° C.; the flame-retardant sealing strip was obtained.

Example 21

(126) For a high-temperature-resistant flame-retardant conveyor belt, a belt core tensile canvas is arranged between the working surface covering rubber and the non-working surface covering rubber, and the working surface covering rubber, the belt core tensile canvas, and the non-working surface covering rubber were formed into a firm whole by means of forming and vulcanization processes. The components and proportions of the working surface covering rubber in the examples of the present invention were metered by parts:

(127) (1) rubber mixing process:

(128) the temperature of an internal mixer was set to be 90° C. and the rotor speed was set to be 50 r/min, 100 parts of branched polyethylene PER-12 was added, and pre-pressing and mixing were performed for 90 s; 5 parts of zinc oxide, 2 parts of stearic acid, 1 part of an anti-aging agent RD, and 1 part of an anti-aging agent MB were added, and mixing was performed for 1 min; then, 70 parts of silane coupling agent modified aluminum hydroxide, 40 parts of carbon black N550, 20 parts of calcined clay, and 25 parts of paraffin oil SUNPAR2280 were added to the rubber compound, and mixing was performed for 3 min; finally, 3 parts of a crosslinking agent dicumyl peroxide (DCP), 1 part of an auxiliary crosslinking agent triallyl isocyanurate (TAIC), and 0.2 part of sulfur were added, mixing was performed for 2 min, and then, the rubber was discharged;

(129) (2) calendering process:

(130) the rubber mix was put into a screw extruder so as to be subjected to hot milling, then, the rubber mix was conveyed into a calender so as to be calendered, and then, a sheet was discharged for later use; the thickness of the rubber sheet was controlled to be 4.5 to 12 mm in the processes of calendering and discharging the sheet; after the sheet was discharged, the temperature of the sheet was kept for later use;

(131) (3) forming process:

(132) the rubber sheet and a preformed rubberized canvas belt blank were closely attached together on a forming machine to form a belt blank of a high-temperature-resistant flame-retardant conveyor belt, the belt blank was coiled, and after 4 h, the coiled belt blank was vulcanized;

(133) (4) vulcanization process:

(134) the formed belt blank of the conveyor belt was put into a press vulcanizer so as to be vulcanized in sections, wherein for each plate, the vulcanization time was 25 min, the vulcanization pressure was 3 MPa, and the vulcanization temperature was 160° C.;

(135) (5) trimming and inspecting:

(136) after vulcanization, trimming and inspecting were performed, and then, packaging and warehousing were performed.