VULCANIZING AGENT AND USE THEREOF

Abstract

A vulcanizing agent is added during the processing of a polymer, and can form a crosslinking structure network in the polymer, thereby improving the mechanical properties of the material. Furthermore, the crosslinking agent can also de-crosslink the polymer material at a high temperature, and after being cooled, same can be crosslinked again to produce a network structure, thus endowing the polymer material with thermoplasticity for repeated processing.

Claims

1. A vulcanizing agent, having at least two α-olefin structures and comprising a structure selected from any one of formulas (I) to (VI): ##STR00022## wherein, R.sup.1 and R.sup.2 are the same or different, and each of R.sup.1 and R.sup.2 is selected from acrylate groups, styryl, vinyl silane groups, and substitutes of acrylate groups, styryl and vinyl silane groups that contain 1 to 12 carbon atoms substituent group; R.sup.3 and R.sup.4 are the same or different, and each of R.sup.3 and R.sup.4 is selected from —O—, —NH—, —N(CH.sub.3)—, and —N(C.sub.2H.sub.5)—; R.sup.5 is selected from aliphatic groups, aromatic groups, ester groups, and ether groups, wherein, in case that R.sup.5 is selected from aliphatic groups, the formula (I) or formula (II) is —C.sub.mH.sub.2m—, the formula (IV) or formula (V) is ##STR00023## (when n is 3) or ##STR00024## (when n is 4); in case that R.sup.5 is selected from aromatic groups, the formula (I) or formula (II) is —(C.sub.6H.sub.4).sub.xC.sub.mH.sub.2m—, the formula (IV) or formula (V) is ##STR00025## (when n is 3) or ##STR00026## (when n is 4); in case that R.sup.5 is selected from ester groups, the formula (I) or formula (II) is —(C.sub.6H.sub.4).sub.y(C.sub.mH.sub.2m)(COO).sub.x—, the formula (IV) or formula (V) is ##STR00027## (when n is 3) or ##STR00028## (when n is 4); in case that R.sup.5 is selected from ether groups, the formula (I) or formula (II) is —(C.sub.6H.sub.4).sub.yC.sub.mH.sub.2mO.sub.x—, the formula (IV) or formula (V) is ##STR00029## (when n is 3) or ##STR00030## (when n is 4); wherein, m is an integer ranging from 1 to 18, x is an integer ranging from 1 to 8, and y is an integer ranging from 1 to 8; R.sup.6 and R.sup.7 are the same or different, and each of R.sup.6 and R.sup.7 is selected from —H and —CH.sub.3; and n is 3 or 4.

2. An application of the vulcanizing agent in claim 1 for polymer vulcanization crosslinking.

3. The application according to claim 2, wherein a polymer vulcanization crosslinking reaction is carried out by reacting a polymer with a vulcanizing agent, an initiator and a heat stabilizer by means of melting method, wherein a mass ratio of the polymer to the vulcanizing agent is 100:0.01 to 100:10, a mass ratio of the polymer to the initiator is 100:0.01 to 100:1, and a mass ratio of the polymer to the heat stabilizer is 100:0 to 100:1.

4. The application according to claim 3, wherein the polymer is selected from at least one of polyolefin resins and polyolefin rubbers.

5. The application according to claim 3, wherein the initiator is selected from organic peroxides and azo initiators.

6. The application according to claim 3, wherein the heat stabilizer is selected from at least one of hindered phenolic macromolecular antioxidants, phosphite antioxidants and alkyl ester antioxidants.

7. The application according to claim 3, wherein the polymer vulcanization crosslinking method comprises the following steps of: S1. mixing the polymer, the vulcanizing agent, the initiator and the heat stabilizer to obtain a premixed raw material; S2. adding the premixed raw material into a reactive processing equipment to react at a temperature above 120° C.; and S3. extruding a product followed by cooling to crosslink.

8. The application according to claim 7, wherein the reactive processing equipment is one of single-screw extruder, twin-screw extruder, open mill, and internal mixer.

Description

DETAILED DESCRIPTION OF DRAWINGS

[0039] FIG. 1 shows the crosslinking rubber product prepared in Embodiment 4, which is hot-pressed moulding again after being cut into fragments, wherein

[0040] FIG. 1 (1) shows the crosslinking rubber sample added with the vulcanizing agent of the present disclosure,

[0041] FIG. 1 (2) shows that the crosslinking rubber sample was cut into fragments,

[0042] FIG. 1 (3) shows that the properties were recovered after the fragments were processed and moulded again.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[0043] The following non-limiting embodiments can enable those ordinary in the art to understand the present disclosure more comprehensively, but do not limit the present disclosure in any way.

Embodiment 1

[0044] Preparation of New Vulcanizing Agent

[0045] 1. Vulcanizing agent having the structure of formula (I)

[0046] Structural formula of the vulcanizing agent A:

##STR00010##

[0047] The synthesis method is shown as chemical equation 1.

[0048] Synthesis of reactant-1: Furfuryl alcohol (6.43 g, 0.07 mol) was added into 20 mL of aqueous sodium hydroxide (40 wt. %) to react with stirring for 1 hour, and a reaction solution was obtained. Then, 10 mL of toluene, 5 g of 4-vinylbenzyl chloride and 4.25 g of aqueous tetrabutylammonium hydroxide (40 wt. %) were added into the reaction solution as catalysts to react for 48 hours at room temperature. After completion of the reaction, the reaction solution was added with excess water and extracted with ether. The organic phase was dried with anhydrous magnesium sulfate followed by filtration, and then the organic solvent was removed by rotary evaporation to obtain the reactant-1, with a yield of 76%.

[0049] The reactant-2 of N,N′-(4,4′-methylene diphenyl) bismaleimide (CAS No.: 13676-54-5) was purchased from Energy Chemical Limited Company.

[0050] Synthesis of vulcanizing agent A: the reactant-1 (8.00 g, 0.04 mol) and the reactant-2 (7.14 g, 0.02 mol) were dissolved in 50 mL of tetrahydrofuran to react at 60° C. for 24 hours under nitrogen. After completion of the reaction, the reaction solution was cooled to room temperature and then was added into excess ether to extract the organic phase. The organic phase was subjected to reduced pressure distillation to remove the solvent. The obtained viscous liquid was the vulcanizing agent A.

##STR00011##

[0051] 2. Vulcanizing agent having the structure of formula (II)

[0052] Structural formula of the vulcanizing agent B:

##STR00012##

[0053] The synthesis method is shown as chemical equation 2.

[0054] The reactant-1 of furfuryl alcohol (CAS No.: 98-00-0) was purchased from Energy Chemical Limited Company.

[0055] The reactant-2 of 1,4-butanediol diacrylate (CAS No.: 13676-54-5) was purchased from Energy Chemical Limited Company.

[0056] Synthesis of vulcanizing agent B: the reactant-1 (3.92 g, 0.04 mol) and the reactant-2 (3.96 g, 0.02 mol) were dissolved in 50 mL of tetrahydrofuran to react at room temperature for 72 hours under nitrogen. After completion of the reaction, the liquid having a low boiling point was removed by reduced pressure distillation to obtain an intermediate M. The intermediate M was dissolved in dichloromethane followed by addition of 3 mL of triethylamine, and then 0.04 mol of methacryloyl chloride was added under nitrogen to react with stirring at room temperature for 4 hours. After completion of the reaction, the liquid having a low boiling point in the reaction product was removed by reduced pressure distillation, and then the remaining triethylamine in the product was neutralized with aqueous hydrochloric acid until the pH of the product solution was neutral. The neutral solution was stood for layer separation followed by removing the water layer to obtain the vulcanizing agent B.

##STR00013##

[0057] 3. Vulcanizing agent having the structure of formula (III)

[0058] Structural formula of the vulcanizing agent C is

##STR00014##

[0059] The synthesis method is shown as chemical equation 3.

[0060] Synthesis of reactant: in an ice-water bath, 2 mL of newly distilled cyclopentadiene (1.6 g, 24.3 mmol) was dropwise added into n-hexane solution (100 mL) containing n-butyl lithium (24.2 mmol). The mixed solution was reacted for 3 hours at room temperature. After that, the solvent was removed from the mixed solution followed by washing the mixed solution with n-pentane (3×50 mL), and then the mixed solution was dried in vacuum to obtain Li (C.sub.5H.sub.5). At a temperature of −78° C., the above prepared Li (C.sub.5H.sub.5) was dissolved in tetrahydrofuran (75 mL), and then the mixture was dropwise added into the tetrahydrofuran solution with dimethyl vinyl chlorosilane (2.7 g, 22.0 mmol) dissolved therein to react at 0° C. for half an hour followed by reacting at room temperature overnight. The volatile components were removed from the reaction solution by vacuum distillation, and then the reaction solution was extracted with n-pentane (3×50 mL) followed by filtration and dry, and finally the reactant with a yield of 60% was obtained.

[0061] Synthesis of vulcanizing agent C: the reactant (12.0 g, 0.08 mol) was dissolved in 50 mL of tetrahydrofuran to react at room temperature for 48 hours. After completion of the reaction, the reaction solution was cooled to room temperature followed by reduced pressure distillation to obtain the vulcanizing agent C.

##STR00015##

[0062] 4. Vulcanizing agent having the structure of formula (IV)

[0063] Structural formula of the vulcanizing agent D is

##STR00016##

[0064] The synthesis method is shown as chemical equation 4.

[0065] Synthesis of reactant-1: under nitrogen, TMEDA (14.33 g, 0.123 mol) and 1-methylpyrrole (10 g, 0.123 mol) were dissolved in 80 mL of anhydrous tetrahydrofuran, and then 77 mL of n-hexane solution containing n-butyl lithium (1.6 M) was dropwise added to the anhydrous tetrahydrofuran to obtain a mixed solution. After stirring for half an hour, 0.123 mol of dimethyl vinyl chlorosilane was added to the mixed solution to react at room temperature for 12 hours to obtain a product solution. After washing with water, the product solution was extracted with ether followed by reduced pressure distillation to obtain the reactant-1 with a yield of 70%.

[0066] Synthesis of reactant-2: 30 g of maleic anhydride and 25 g of furan were dissolved in 300 mL of toluene with stirring at room temperature for 36 hours followed by filtration to obtain a white solid powder of furan protected maleic anhydride with a yield of 79%. 150 mL of methanol was added into a 500 mL flask with a stirrer, a constant pressure funnel and a reflux pipe. The prepared furan protected maleic anhydride (5.66 g, 34 mmol) was added into the flask and was completely dissolved with stirring. Then, at a temperature of 0° C., 50 mL of methanol with 4,4′,4″-methanetriyltrianiline (1.98 g, 6.85 mmol) dissolved therein was dropwise added into the flask by the constant pressure funnel within 30 minutes. The mixed solution was reacted under reflux for 3 hours to obtain a yellow reaction mixture. The yellow reaction mixture was concentrated to 75 mL and then was crystallized at 4° C., followed by filtration to obtain light yellow crystals. The light yellow crystals were washed with 50 mL of ethyl acetate and then were dried in vacuum to obtain an intermediate M with a yield of 24%. 30 mL of toluene and the intermediate M (0.5 g, 0.85 mmol) were added into a 100 mL flask with a stirrer and a reflux pipe. The stirrer was turned on to completely dissolve the intermediate M. The mixture was reacted under condensation reflux for 7 hours to obtain a product. The product was dried in rotary dryer to obtain the reactant-2 with a yield of 84%.

[0067] Synthesis of vulcanizing agent D: the reactant-1 (4.96 g, 0.03 mol) and the reactant-2 (3.86 g, 0.01 mol) were dissolved in 50 mL of tetrahydrofuran to react at 60° C. for 48 hours under nitrogen. After completion of the reaction, the reaction solution was cooled to room temperature followed by reduced pressure distillation to remove the liquid having a low boiling point to obtain the vulcanizing agent D.

##STR00017##

[0068] 5. Vulcanizing agent having the structure of formula (V)

[0069] Structural formula of the vulcanizing agent E:

##STR00018##

[0070] The synthesis method is shown as chemical equation 5.

[0071] Synthesis of vulcanizing agent E: pentaerythritol tetraacrylate (3.52 g, 0.01 mol) and furfuryl alcohol (3.92 g, 0.04 mol) were dissolved in 50 mL of tetrahydrofuran to react at room temperature for 72 hours under nitrogen. After completion of the reaction, the liquid having a low boiling point was removed from the reaction solution by reduced pressure distillation to obtain an intermediate M. The intermediate M was dissolved in methylene chloride followed by addition of 3 mL of triethylamine, and 0.04 mol of methylacryloyl chloride was added under nitrogen to obtain a mixed solution. The mixed solution was reacted with stirring at room temperature for 4 hours. After completion of the reaction, the liquid having a low boiling point was removed from the solution by reduced pressure distillation, and then the remaining triethylamine in the product was neutralized with aqueous hydrochloric acid until the pH of the solution was neutral. The neutral solution was stood for layer separation followed by removing the water layer to obtain the vulcanizing agent E.

##STR00019##

[0072] 6. Vulcanizing agent having the structure of formula (VI)

[0073] Structural formula of the vulcanizing agent F:

##STR00020##

[0074] The synthesis method is shown as chemical equation 6.

[0075] Synthesis of reactant-1: furfuryl alcohol (6.43 g, 0.07 mol) was added into 20 mL of aqueous sodium hydroxide (40 wt. %) to react with stirring for 1 hour, and a reaction solution was obtained. Then, 10 mL of toluene, 5 g of 4-vinylbenzyl chloride and 4.25 g of aqueous tetrabutylammonium hydroxide (40 wt. %) were added into the reaction solution as catalysts to react at room temperature for 48 hours. After completion of the reaction, the reaction solution was added with excess water and extracted with ether. The organic phase was dried with anhydrous magnesium sulfate followed by filtration, and then the organic solvent was removed by rotary evaporation to obtain the reactant-1, with a yield of 76%.

[0076] Synthesis of reactant-2: maleic anhydride and p-vinyl aniline were dissolved in ethyl acetate to react with stirring at 0° C. for 1 hour, and a reaction solution was obtained. Then, acetic anhydride and triethylamine were added into the reaction solution to react at 55° C. for 1 hour followed by cooling to obtain the reactant-2, with a yield of 80%.

[0077] Synthesis of vulcanizing agent F: the reactant-1 (8.00 g, 0.04 mol) and the reactant-2 (7.95 g, 0.04 mol) were dissolved in 50 mL of tetrahydrofuran under nitrogen to react at 60° C. for 24 hours, and a reaction mixture was obtained. After completion of the reaction, the reaction mixture was cooled to room temperature, and then was added into excess ether to extract the organic phase. The organic phase product was subjected to reduced pressure distillation to remove the solvent. The obtained viscous liquid was the vulcanizing agent F.

##STR00021##

Embodiment 2

[0078] In parts by mass, 100 parts of polypropylene (MFR is 2.0 g/10 min, 230° C., the same below), 0.1 parts of antioxidant 1010, 0.1 parts of antioxidant 168, 0.1 parts of 2,5-dimethyl-2,5-bis(tert-butyl peroxy)hexane (initiator), and 2 parts of the vulcanizing agent A of the present invention were mixed, and then the mixture was added to a 35-type double-screw extruder (from Coperion Keya (Nanjing) Machinery Co., Ltd.) for melting. The melt section temperature of the extruder is 160° C., the reaction section temperature is 190° C., the melt conveying section temperature is 200° C., the outlet temperature is 180° C., and the screw speed is 150 rpm. The extruded product was cooled by circulating water bath followed by cut to obtain the final product polymer.

Embodiment 3

[0079] In parts by mass, 100 parts of polypropylene, 0.1 parts of antioxidant 1010, 0.1 parts of antioxidant 168, 0.1 parts of 2,5-dimethyl-2,5-bis(tert-butyl peroxy)hexane (initiator), and 5 parts of the vulcanizing agent A of the present disclosure were mixed, and then the mixture was added to a 35-type double-screw extruder for melting. The melt section temperature of the extruder is 160° C., the reaction section temperature is 190° C., the melt conveying section temperature is 200° C., the outlet temperature is 180° C., and the screw speed is 150 rpm. The extruded product was cooled by circulating water bath followed by cut to obtain the final product polymer.

Embodiment 4

[0080] In parts by mass, 100 parts of ethylene propylene rubber (Mooney viscosity of ML.sub.1+4 is 40, 100° C., the same below), 0.1 parts of antioxidant 1010, 0.1 parts of antioxidant 168, 0.2 parts of dicumyl peroxide (initiator), and 5 parts of the vulcanizing agent B of the present disclosure were mixed. The mixture was added to an opening mill (X(S)K-160, produced by Shanghai Shuangying Rubber & Plastic Machinery Co., Ltd.) with a roll distance of 0.7 mm at a roll temperature of 60° C., and then the mixture was passed through the rolls and folded into a triangle bag for 5 times followed by placing for 2 hours to obtain the final product polymer.

Embodiment 5

[0081] In parts by mass, 100 parts of ethylene propylene rubber, 0.1 parts of antioxidant 1010, 0.1 parts of antioxidant 168, 0.1 parts of dicumyl peroxide (initiator), and 8 parts of the vulcanizing agent C of the present disclosure were mixed. The mixture was added to an opening mill (X(S)K-160) with a roll distance of 0.7 mm at a roll temperature of 60° C., and then the mixture was passed through the rolls and folded into a triangle bag for 5 times followed by placing for 2 hours to obtain the final product polymer.

Embodiment 6

[0082] In parts by mass, 100 parts of ethylene propylene rubber, 0.1 parts of antioxidant 1010, 0.1 parts of antioxidant 168, 0.2 parts of dicumyl peroxide (initiator), and 5 parts of the vulcanizing agent E of the present disclosure were mixed. The mixture was added to an opening mill (X(S)K-160) with a roll distance of 0.7 mm at a roll temperature of 60° C., and then the mixture was passed through the rolls and folded into a triangle for 5 times followed by placing for 2 hours to obtain the final product polymer.

Embodiment 7

[0083] In parts by mass, 50 parts of polypropylene, 50 parts of polyethylene (MFR is 3.0 g/10 min, 230° C., the same below), 0.1 parts of antioxidant 1010, 0.1 parts of antioxidant 168, 0.2 parts of 2,5-dimethyl-2,5-bis(tert-butyl peroxy)hexane (initiator), and 4 parts of the vulcanizing agent C of the present disclosure were mixed, and then the mixture was added to a 35-type double-screw extruder for melting. The melt section temperature of the extruder is 160° C., the reaction section temperature is 190° C., the melt conveying section temperature is 200° C., the outlet temperature is 180° C., and the screw speed is 150 rpm. The extruded product was cooled by circulating water bath followed by cut to obtain the final product polymer.

Embodiment 8

[0084] In parts by mass, 50 parts of polypropylene, 50 parts of polyethylene, 0.1 parts of antioxidant 1010, 0.1 parts of antioxidant 168, 0.2 parts of 2,5-dimethyl-2,5-bis(tert-butyl peroxy)hexane (initiator), and 5 parts of the vulcanizing agent D of the present disclosure were mixed, and then the mixture was added to a 35-type double-screw extruder for melting. The melt section temperature of the extruder is 160° C., the reaction section temperature is 190° C., the melt conveying section temperature is 200° C., the outlet temperature is 180° C., and the screw speed is 150 rpm. The extruded product was cooled by circulating water bath followed by cut to obtain the final product polymer.

Embodiment 9

[0085] In parts by mass, 80 parts of polypropylene, 20 parts of ethylene propylene rubber, 0.1 parts of antioxidant 1010, 0.1 parts of antioxidant 168, 0.15 parts of 2,5-dimethyl-2,5-bis(tert-butyl peroxy)hexane (initiator), and 3 parts of the vulcanizing agent D of the present disclosure were mixed, and then the mixture was added to a 35-type double-screw extruder for melting. The melt section temperature of the extruder is 160° C., the reaction section temperature is 190° C., the melt conveying section temperature is 200° C., the outlet temperature is 180° C., and the screw speed is 150 rpm. The extruded product was cooled by circulating water bath followed by cut to obtain the final product polymer.

Embodiment 10

[0086] In parts by mass, 100 parts of polyethylene, 0.1 parts of antioxidant 1010, 0.1 parts of antioxidant 168, 0.2 parts of 2,5-dimethyl-2,5-bis(tert-butyl peroxy)hexane (initiator), and 2 parts of the vulcanizing agent E of the present disclosure were mixed, and then the mixture was added to a 35-type double-screw extruder for melting. The melt section temperature of the extruder is 160° C., the reaction section temperature is 190° C., the melt conveying section temperature is 200° C., the outlet temperature is 180° C., and the screw speed is 150 rpm. The extruded product was cooled by circulating water bath followed by cut to obtain the final product polymer.

Embodiment 11

[0087] In parts by mass, 100 parts of butyl rubber (Mooney viscosity of ML.sub.1+4 is 75, 100° C.), 0.1 parts of antioxidant 1010, 0.1 parts of antioxidant 168, 0.1 parts of dicumyl peroxide, and 5 parts of the vulcanizing agent C of the present disclosure were mixed. The mixture was added to an opening mill (X(S)K-160) with a roll distance of 0.7 mm at a roll temperature of 60° C., and then the mixture was passed through the rolls and folded into a triangle for 5 times followed by placing for 2 hours to obtain the final product polymer.

Embodiment 12

[0088] In parts by mass, 40 parts of polypropylene, 40 parts of polyethylene, 20 parts of ethylene propylene rubber, 0.1 parts of antioxidant 1010, 0.1 parts of antioxidant 168, 0.2 parts of 2,5-dimethyl-2,5-bis(tert-butyl peroxy)hexane (initiator), and 5 parts of the vulcanizing agent A of the present disclosure were mixed, and then the mixture was added to a 35-type double-screw extruder for melting. The melt section temperature of the extruder is 160° C., the reaction section temperature is 190° C., the melt conveying section temperature is 200° C., the outlet temperature is 180° C., and the screw speed is 150 rpm. The extruded product was cooled by circulating water bath followed by cut to obtain the final product polymer.

Embodiment 13

[0089] The product polymer obtained in Embodiment 9 was again added to the 35-type double-screw extruder for melting. The melt section temperature of the extruder is 160° C., the reaction section temperature is 190° C., the melt conveying section temperature is 200° C., the outlet temperature is 180° C., and the screw speed is 150 rpm. The extruded product was cooled by circulating water bath followed by cut to obtain the final polymer.

Embodiment 14

[0090] The product polymer obtained in Embodiment 13 was again added to the 35-type double-screw extruder for melting. The melt section temperature of the extruder is 160° C., the reaction section temperature is 190° C., the melt conveying section temperature is 200° C., the outlet temperature is 180° C., and the screw speed is 150 rpm. The extruded product was cooled by circulating water bath followed by cut to obtain the final polymer.

Embodiment 15

[0091] In parts by mass, 80 parts of polypropylene, 20 parts of ethylene propylene rubber, 0.1 parts of antioxidant 1010, 0.1 parts of antioxidant 168, 0.15 parts of 2,5-dimethyl-2,5-bis(tert-butyl peroxy)hexane (initiator), and 8 parts of the vulcanizing agent F of the present disclosure were mixed, and then the mixture was added to a 35-type double-screw extruder for melting. The melt section temperature of the extruder is 160° C., the reaction section temperature is 190° C., the melt conveying section temperature is 200° C., the outlet temperature is 180° C., and the screw speed is 150 rpm. The extruded product was cooled by circulating water bath followed by cut to obtain the final product polymer.

Comparative Example 1

[0092] In parts by mass, 100 parts of polypropylene (MFR is 2.0 g/10 min, 230° C., the same below), 0.1 parts of antioxidant 1010, 0.1 parts of antioxidant 168, and 0.1 parts of 2,5-dimethyl-2,5-bis(tert-butyl peroxy)hexane (initiator) were mixed, and then the mixture was added to a 35-type double-screw extruder (from Coperion Keya (Nanjing) Machinery Co., Ltd.) for melting. The melt section temperature of the extruder is 160° C., the reaction section temperature is 190° C., the melt conveying section temperature is 200° C., the outlet temperature is 180° C., and the screw speed is 150 rpm. The extruded product was cooled by circulating water bath followed by cut to obtain the final product polymer.

Comparative Example 2

[0093] In parts by mass, 100 parts of ethylene propylene rubber (Mooney viscosity of ML.sub.1+4 is 40, 100° C., the same below), 0.1 parts of antioxidant 1010, 0.1 parts of antioxidant 168, and 0.2 parts of dicumyl peroxide were mixed. The mixture was added to an opening mill (X(S)K-160 produced by Shanghai Shuangying Rubber & Plastic Machinery Co., Ltd.) with a roll distance of 0.7 mm at a roll temperature of 60° C., and then the mixture was passed through the rolls and folded into a triangle for 5 times followed by placing for 2 hours to obtain the final product polymer.

Comparative Example 3

[0094] In parts by mass, 50 parts of polypropylene, 50 parts of polyethylene (MFR is 3.0 g/10 min, 230° C., the same below), 0.1 parts of antioxidant 1010, 0.1 parts of antioxidant 168, and 0.2 parts of 2,5-dimethyl-2,5-bis(tert-butyl peroxy)hexane (initiator) were mixed, and then the mixture was added to a 35-type double-screw extruder for melting. The melt section temperature of the extruder is 160° C., the reaction section temperature is 190° C., the melt conveying section temperature is 200° C., the outlet temperature is 180° C., and the screw speed is 150 rpm. The extruded product was cooled by circulating water bath followed by cut to obtain the final product polymer.

Comparative Example 4

[0095] In parts by mass, 80 parts of polypropylene, 20 parts of ethylene propylene rubber, 0.1 parts of antioxidant 1010, 0.1 parts of antioxidant 168, and 0.15 parts of 2,5-dimethyl-2,5-bis (tert-butyl peroxy)hexane (initiator) were mixed, and then the mixture was added to a 35-type double-screw extruder for melting. The melt section temperature of the extruder is 160° C., the reaction section temperature is 190° C., the melt conveying section temperature is 200° C., the outlet temperature is 180° C., and the screw speed is 150 rpm. The extruded product was cooled by circulating water bath followed by cut to obtain the final product polymer.

Comparative Example 5

[0096] The product polymer obtained in Comparative Example 4 was again added to the 35-type double-screw extruder for melting. The melt section temperature of the extruder is 160° C., the reaction section temperature is 190° C., the melt conveying section temperature is 200° C., the outlet temperature is 180° C., and the screw speed is 150 rpm. The extruded product was cooled by circulating water bath followed by cut to obtain the final product polymer.

[0097] Performance test results of the modified polypropylene resins prepared by the above embodiments are listed in Table 1.

TABLE-US-00001 TABLE 1 Polymer performance Notched impact Flexural Young Tensile Elongation MFR or strength (kJ/m.sup.2) modulus modulus strength at Embodiment ML.sub.1+4 23° C. −20° C. (MPa) (MPa) (MPa) break (%) Comparative MFR = 2.1 0.55 1256 659 44.1 500 Example 1 2.7 (230° C.) Comparative ML.sub.1+4 = / / / / 8.1 450 Example 2 33 (100° C.) Comparative MFR = 2.0 1.1 970 455 33.4 206 Example 3 2.4 (230° C.) Comparative MFR = 23.2 5.1 656 428 31.9 330 Example 4 2.1 (230° C.) Comparative MFR = 15.1 2.9 554 317 23.8 182 Example 5 2.7 (230° C.) Embodiment 2 MFR = 21.8 2.0 1348 691 49.8 760 (Compared 2.5 with (230° C.) Comparative Example 1) Embodiment 3 MFR = 39.4 3.3 1392 924 52.5 544 (Compared 2.3 with (230° C.) Comparative Example 1) Embodiment 4 ML.sub.1+4 = / / / / 16.1 318 (Compared 36 with (100° C.) Comparative Example 2) Embodiment 5 ML.sub.1+4 = / / / / 18.4 213 (Compared 38 with (100° C.) Comparative Example 2) Embodiment 6 ML.sub.1+4 = / / / / 20.6 89 (Compared 37 with (100° C.) Comparative Example 2) Embodiment 7 MFR = 32.0 4.7 1140 685 44.2 358 (Compared 2.1 with (230° C.) Comparative Example 3) Embodiment 8 MFR = 46.0 7.1 1120 714 48.7 227 (Compared 2.0 with (230° C.) Comparative Example 3) Embodiment 9 MFR = Not 22.8 710 555 37.8 502 (Compared 2.1 broken with (230° C.) Comparative Example 4) Embodiment 10 MFR = 1.9 Not 7.8 1250 877 50.9 660 (230° C.) broken Embodiment 11 ML.sub.1+4 = / / / / 20.8 178 66 (100° C.) Embodiment 12 MFR = Not 34.7 910 487 35.9 577 1.9 broken (230° C.) Embodiment 13 MFR = Not 31.5 866 520 34.0 530 2.1 broken (230° C.) Embodiment 14 MFR = Not 29.2 882 505 33.5 499 2.3 broken (230° C.) Embodiment 15 MFR = Not 19.5 774 681 40.0 340 2.3 broken (230° C.)

[0098] Table 1 lists the performance data of the modified polypropylene resins.

[0099] Firstly, compared with the comparative examples, the prepared modified polymer forms a crosslinking network structure due to the addition of the vulcanizing agent of the present disclosure. It can be confirmed by the significant improvement of the mechanical performances of the modified polymers. By comparing Embodiment 2 with Comparative Example 1, Embodiment 4 with Comparative Example 2, Embodiment 7 with Comparative Example 3, and Embodiment 9 with Comparative Example 4, etc., it can be seen that the performances of material including strength and modulus are significantly improved after addition of the vulcanizing agent. It shows that the vulcanizing agent of the present disclosure plays obvious crosslinking effect.

[0100] Secondly, the vulcanizing agent of the present disclosure is a new type vulcanizing agent having a reversible crosslinking function, and the prepared crosslinking polymer thereof has a thermally reversible crosslinking structure, that is, the crosslinking network can be de-crosslinked in the melt processing state (due to the reverse Diels-Alder reaction mechanism), so that enable the material to have thermoplastictiy. Melting index of the crosslinking polymer samples of all embodiments can be determined, indicating that the materials have thermoplasticity. For example, comparing Comparative Example 4 with Embodiment 9, it can be seen that the performance of polymer prepared in Embodiment 9 is significantly better than that of Comparative Example 4 due to its crosslinking structure. Meanwhile, the melt index of the two polymers is similar (that is, the processing performance is similar), indicating that the vulcanizing agent of the present disclosure has the performance of forming a network by cooling and removing the network by warming to a high temperature, which is completely different from the permanent crosslinking network formed by the traditional vulcanizing agent. The vulcanizing agent of the present disclosure enables the crosslinking polymer to have excellent property of thermoplasticity, thereby realizing the repeated processing of the crosslinking polymer. FIG. 1 shows the crosslinking rubber product prepared in Embodiment 4, which can be hot-pressed again after being cut into fragments.

[0101] Thirdly, the performance of the crosslinking polymer prepared by the present disclosure can be well maintained after repeated processing. The sample of Comparative Example 5 is obtained by reprocessing the product in Comparative Example 4. It can be seen that the performance of sample of Comparative Example 5 has been obviously weakened and the strength has been reduced (one reason is that the polymer is partially degraded due to reprocessing, and another reason is that the performance is weakened due to two-phase separation). However, the sample of Embodiment 13 is obtained by reprocessing the product in Embodiment 12, and the sample of Embodiment 14 is obtained by further reprocessing the product in Embodiment 13. After continuous processing for many times, the performances of the material are hardly weakened, which is due to the thermally reversible crosslinking function of the vulcanizing agent of the present disclosure. After repeated processing, the crosslinking structure can still be stably recovered, and the crosslinking structure between the two phases can also make up the problems caused by the separation of the two phases, so that the performance can be maintained.

[0102] In conclusion, the vulcanizing agent of the present disclosure is a new type vulcanizing agent having a reversible crosslinking function. When used in polymer processing, the vulcanizing agent of the present disclosure has such characteristics as de-crosslinking at high temperature (during processing) and easy to process, and crosslinking at low temperature (after molding) and having high performance. The vulcanizing agent can also be used to strengthen the performance of waste plastics and rubber in recycling.