阅读说明：本技术 制备丙丁无规共聚聚丙烯的方法 (Method for preparing polypropylene random copolymer of propane and butane ) 是由 李德展 宋文波 胡慧杰 邹发生 赵梦垚 刘振杰 于 2019-10-29 设计创作，主要内容包括：本发明涉及烯烃聚合和材料技术领域,公开了一种制备丙丁无规共聚聚丙烯的方法,该方法包括：将丙丁无规共聚聚丙烯基础料与降解剂、抗氧剂和卤素吸收剂进行混合；其中,相对于100重量份的丙丁无规共聚聚丙烯基础料,所述降解剂的用量为0.01-0.18重量份。通过上述技术方案,本发明的方法能够在较低含量降解剂的条件下有效降解丙丁无规共聚聚丙烯。(The invention relates to the technical field of olefin polymerization and materials, and discloses a method for preparing polypropylene random copolymer, which comprises the following steps: mixing the polypropylene base material with a degrading agent, an antioxidant and a halogen absorbent; wherein, the dosage of the degradation agent is 0.01 to 0.18 weight part relative to 100 weight parts of the polypropylene-random copolymer base material. Through the technical scheme, the method can effectively degrade the polypropylene random copolymer under the condition of lower content of the degradation agent.)

1. A process for preparing a polypropylene random copolymer comprising: mixing the polypropylene base material with a degrading agent, an antioxidant and a halogen absorbent; wherein, the dosage of the degradation agent is 0.01 to 0.18 weight part relative to 100 weight parts of the polypropylene-random copolymer base material.

2. The method according to claim 1, wherein the degrading agent is used in an amount of 0.03-0.055 parts by weight.

3. The method of claim 1 or 2, wherein the degradation agent is an organic peroxide.

4. The process according to claim 1 or 2, wherein the degradation agent is selected from at least one of benzoyl peroxide, tert-butyl peroxybenzoate, di-tert-butyl peroxide, tert-butyl peroxy-2-hexylhexanoate, tert-butyl hydroperoxide, 5-dimethyl-2, 5-di (tert-butyl) hexane peroxide, 6, 9-triethyl-3, 6, 9-trimethyl-1, 4, 7-triperoxonane, di-tert-amyl peroxide, 2, 5-dimethyl-2, 5 bis (tert-butylperoxy) hexane, dicumyl peroxide and 3,6, 9-triethyl-3, 6, 9-trimethyl-1, 4, 7-triperoxonane; more preferably at least one selected from the group consisting of 5-dimethyl-2, 5 bis (t-butylperoxy) hexane, dicumyl peroxide and 3,6, 9-triethyl-3, 6, 9-trimethyl-1, 4, 7-triperoxonane.

5. The method of claim 1, wherein the antioxidant is used in an amount of 0.04 to 0.4 parts by weight and the halogen absorbent is used in an amount of 0.03 to 0.2 parts by weight.

6. The method of claim 1 or 5, wherein the antioxidant is selected from at least one of antioxidant 1010, antioxidant 1790, antioxidant B501W, antioxidant 1076, antioxidant 1024, antioxidant CA, and antioxidant 168.

7. The method according to claim 1 or 5, wherein the halogen absorbent is hydrotalcite, a metal stearate, preferably at least one selected from calcium stearate, zinc stearate, sodium stearate and hydrotalcite.

8. The process according to claim 1, wherein the propylene-butylene random copolymer polypropylene base stock has a molecular weight distribution of < 4.5, a butylene content of 0.5 to 6 mol% and a melt index at 230 ℃ under a 2.16kg load of 0.5 to 10g/10 min.

9. The method of claim 1, wherein the mixing is by: and (3) putting the mixture containing the polypropylene random copolymer base material, the degrading agent, the antioxidant and the halogen absorbent into a double-screw extruder to enable the polypropylene random copolymer to generate free radical degradation reaction.

10. The process according to claim 1 or 9, wherein the temperature of each section of the twin-screw extruder is in the range of 180 ℃ and 220 ℃ and the rotation speed is 200 rpm and 600rpm, preferably 250 rpm and 400 rpm.

Technical Field

The invention relates to the technical field of olefin polymerization and materials, in particular to a method for preparing polypropylene random copolymer.

Background

The polypropylene fiber or the non-woven fabric has soft hand feeling and exquisite appearance, has the advantages of moisture resistance, air permeability, light weight, acid and alkali resistance and the like, and is widely applied to the fields of sanitary materials (such as masks), medical supplies, packaging, building materials and the like.

Such polypropylenes are generally required to have narrow molecular weight distribution widths (generally required < 4), suitable melt flow rates (melt index) MFR (> 30g/10min) and good flowability. There are currently two main processes for preparing such polypropylenes. One method is to control the melt flow rate of the polymer by adjusting the amount of chain transfer agent-hydrogen added during the polymerization process. The polymer obtained by adopting the Z-N catalyst has lower MFR and wider molecular weight distribution; the polymer MFR obtained by adopting the metallocene catalyst can be very large and has narrow molecular weight distribution, but the metallocene catalyst has strong hydrogen sensitivity, the polymer MFR can not be well stably controlled in the production process, and the catalyst cost is higher. The other method is to add a degrading agent (generally peroxide) into the low-melting-index polypropylene powder, so that the molecular chain of the polypropylene is broken in the granulation process, and the high-melting-index and narrow-molecular-weight-distribution polypropylene is obtained through degradation. The method has the advantages of low production cost, wide polymer MFR adjustable range and narrow molecular weight distribution, and is widely applied to the preparation of polypropylene fiber products.

The polypropylene degradation technology generally requires that the molecular weight distribution of a base material is narrow, so that a product with narrower molecular weight distribution can be prepared under the action of a degradation agent, and the processing performance of the product can be improved. In the traditional degradation method, the polypropylene fiber material adopts homo-polypropylene or propylene-ethylene random copolymerization polypropylene base material, and no report related to degradation of propylene-butylene random copolymerization polypropylene base material exists.

Disclosure of Invention

The invention aims to overcome the problems in the prior art and provide a method for preparing polypropylene random copolymer of propane and butane.

In order to achieve the above objects, the present invention provides a method for preparing a polypropylene random copolymer comprising: mixing the polypropylene base material with a degrading agent, an antioxidant and a halogen absorbent; wherein, the dosage of the degradation agent is 0.01 to 0.18 weight part relative to 100 weight parts of the polypropylene-random copolymer base material.

Through the technical scheme, the method can effectively degrade the polypropylene random copolymer under the condition of lower content of the degradation agent, the whole process can be carried out without using other components (such as a carrier of the degradation agent), and the method is simple and easy to implement.

The polypropylene random copolymer of propane and butane obtained by the invention has the characteristics of high melt index, narrow molecular weight distribution, low content of xylene soluble substances, high tensile strength and the like, and simultaneously has good processing performance and spinnability, and can be widely applied to the fields of polypropylene fiber materials, non-woven fabrics and the like. Specifically, the melt index of the degraded polypropylene random copolymer of the invention is 20-50g/10min (more than 35g/10min in a preferred embodiment), the molecular weight distribution is less than 3, the tensile strength is more than 26MPa, the flexural modulus is less than 1.1Gpa, and the xylene soluble content is less than 3 wt.%.

Detailed Description

The endpoints of the ranges and any values disclosed herein are not limited to the precise range or value, and such ranges or values should be understood to encompass values close to those ranges or values. For ranges of values, between the endpoints of each of the ranges and the individual points, and between the individual points may be combined with each other to give one or more new ranges of values, and these ranges of values should be considered as specifically disclosed herein.

The invention provides a method for preparing polypropylene random copolymer, which is characterized by comprising the following steps: mixing the polypropylene base material with a degrading agent, an antioxidant and a halogen absorbent; wherein, the dosage of the degradation agent is 0.01 to 0.18 weight part relative to 100 weight parts of the polypropylene-random copolymer base material.

According to the present invention, the process may be performed with a lower amount of the degradation agent used, and thus, it is preferable that the degradation agent is used in an amount of 0.03 to 0.055 parts by weight, such as 0.03 parts by weight, 0.032 parts by weight, 0.036 parts by weight, 0.038 parts by weight, 0.04 parts by weight, 0.05 parts by weight, 0.052 parts by weight, 0.054 parts by weight, 0.055 parts by weight, or any value therebetween, with respect to 100 parts by weight of the polypropylene random copolymer base material.

According to the invention, the degradation agent can be any of the various organic peroxides commonly used in the art, in particular of the general formula R₁-O-H or R₂—O—O—R₃Wherein R is₁、R₂And R₃Each independently is an organic group such as an alkyl group, an acyl group, or a carbonate group.

Preferably, the degradation agent is selected from one or more of benzoyl peroxide, tert-butyl peroxybenzoate, di-tert-butyl peroxide, tert-butyl peroxy-2-hexylhexanoate, tert-butyl hydroperoxide, 5-dimethyl-2, 5-di (tert-butyl) hexane peroxide, 6, 9-triethyl-3, 6, 9-trimethyl-1, 4, 7-triperoxonane, di-tert-amyl peroxide, 2, 5-dimethyl-2, 5-bis (tert-butylperoxy) hexane, dicumyl peroxide and 3,6, 9-triethyl-3, 6, 9-trimethyl-1, 4, 7-triperoxonane; more preferably at least one selected from the group consisting of 5-dimethyl-2, 5 bis (t-butylperoxy) hexane, dicumyl peroxide and 3,6, 9-triethyl-3, 6, 9-trimethyl-1, 4, 7-triperoxonane.

According to the present invention, the amount of the antioxidant is not particularly limited, and preferably, the antioxidant is used in an amount of 0.04 to 0.4 parts by weight, such as 0.04 parts by weight, 0.05 parts by weight, 0.08 parts by weight, 0.1 parts by weight, 0.2 parts by weight, 0.3 parts by weight, 0.4 parts by weight, or any value therebetween.

According to the present invention, the antioxidant may be an antioxidant conventionally used in the art, and preferably, the antioxidant is selected from at least one of antioxidant 1010(CAS number: 6683-19-8), antioxidant 1790(CAS number: 40601-76-1), antioxidant B501W (complex antioxidant), antioxidant 1076(CAS number: 2082-79-3), antioxidant 1024(CAS number: 32687-78-8), antioxidant CA (CAS number: 1843-03-4), and antioxidant 168(CAS number: 31570-04-4). More preferably, the antioxidant of the present invention is composed of a primary antioxidant and a secondary antioxidant, wherein the primary antioxidant is at least one selected from the group consisting of antioxidant 1010, antioxidant 1790, antioxidant 1076, antioxidant 1024 and antioxidant CA; the auxiliary antioxidant is antioxidant 168. The weight ratio of the primary antioxidant to the secondary antioxidant can be 1:5-5:1, preferably 1:2-3: 1. According to another preferred embodiment of the present invention, the antioxidant is antioxidant B501W.

According to the present invention, the amount of the halogen absorbent is not particularly limited, and is preferably 0.03 to 0.2 parts by weight, such as 0.03 parts by weight, 0.04 parts by weight, 0.05 parts by weight, 0.06 parts by weight, 0.1 parts by weight, 0.2 parts by weight, or any value therebetween.

According to the present invention, the halogen absorbent may be a halogen absorbent conventionally used in the art, preferably, the halogen absorbent is hydrotalcite, metal stearate, or the like, more preferably selected from calcium stearate, zinc stearate, sodium stearate, and hydrotalcite (e.g., aluminum magnesium hydrotalcite, mgal (oh))₃CO₃·H₂O).

The process of the present invention is particularly suitable for the degradation of polypropylene having a narrow molecular weight distribution, and therefore, according to a preferred embodiment of the present invention, the molecular weight distribution of the polypropylene matrix of random copolymer of propylene and butylene is < 4.5 (e.g., 2, 2.3, 2.4, 2.5, 3, 3.5, 4, 4.5 or any value therebetween). According to one embodiment of the present invention, the butene content of the propane-butene random copolymer polypropylene base may be 0.5 to 6 mol%, preferably 2 to 5.5 mol% (or 2.5 to 5 mol%). According to another embodiment of the present invention, the melt index of the polypropylene random copolymer base material at 230 ℃ under a load of 2.16kg may be 0.5-10g/10min, preferably 2-8g/10min (e.g., 2g/10min, 2.5g/10min, 3g/10min, 4g/10min, 4.5g/10min, 5g/10min, 6g/10min, 7g/10min, 8g/10min or any value therebetween).

According to the present invention, the propane-butene random copolymer polypropylene base may be obtained in a conventional manner, but according to a preferred embodiment of the present invention, the preparation of the propane-butene random copolymer polypropylene base according to the present invention comprises the steps of:

step A: the catalyst, the organic aluminum (cocatalyst) and the external electron donor are pre-contacted to obtain a catalyst system with an active center, and a prepolymerization reaction is carried out in the presence of a propylene monomer; or the catalyst, the organic aluminum and the external electron donor are directly subjected to prepolymerization reaction without precontacting;

and B: and (3) copolymerizing the catalyst particles after the prepolymerization reaction in the presence of a comonomer 1-butene to obtain the propylene-butene random copolymer polypropylene. Can be prepared by introducing H₂Controlling the polymer melt index.

The polypropylene catalyst in step a is a Ziegler-Natta catalyst having high stereoselectivity, which means a catalyst that can be used to prepare a propylene homopolymer having an isotactic index of greater than 96%. Such catalysts are generally titanium-containing solid catalysts, and the main components thereof are magnesium, titanium, halogen and an internal electron donor, wherein the internal electron donor can be at least one selected from diesters, ethers, succinates, 1, 3-alcohol esters and sulfonamides known in the art, and phosphoric acid esters and diether compounds are preferred.

The organoaluminum in step A is not limited to any organoaluminum commonly used in the polyolefin industry at present, and is preferably at least one member selected from the group consisting of trialkylaluminums (e.g., trimethylaluminum, triethylaluminum, triisobutylaluminum, tri-n-butylaluminum, trihexylaluminum, trioctylaluminum, etc.), diethylaluminum monochloride, diisobutylaluminum monochloride, ethylaluminum dichloride and ethylaluminum dichloride.

The external electron donor in step A is preferably an organosilicon compound having the general formula R_nSi(OR')_4-nWherein n is more than 0 and less than or equal to 3, R is selected from hydrogen atom, halogen, alkyl, cycloalkyl, aryl and halogenated alkyl, and R' is selected from alkyl, cycloalkyl, aryl and halogenated alkyl. Specifically, the method may include but is not limited to: cyclohexylmethyldimethoxysilane, diisopropyldimethoxysilane, tetramethoxysilane, tetraethoxysilane, trimethylmethoxysilane, trimethylethoxysilane, trimethylphenoxysilane, dimethyldimethyldimethyldimethoxysilaneOxysilane, dimethyl diethoxy silane, methyl tert-butyl dimethoxy silane, methyl isopropyl dimethoxy silane, diphenoxydimethoxy silane, diphenyl diethoxy silane, phenyl trimethoxy silane, phenyl triethoxy silane, vinyl trimethoxy silane, (1,1, 1-trifluoro-2-propyl) -2-ethylpiperidinyl dimethoxy silane, (1,1, 1-trifluoro-2-propyl) -methyl dimethoxy silane and the like.

In the step a, the amount of the catalyst, the organoaluminum and the external electron donor can be determined according to the need, and the weight ratio of the organoaluminum to the catalyst is preferably 1:4 to 50:1, more preferably 2:1 to 20: 1. The weight ratio of the organoaluminum to the external electron donor may be 0.1:1 to 150:1, preferably 2:1 to 150: 1.

The precontacting in step A can be continuous or batch operation and can be carried out by means of a reactor, and the precontacting reactor can be a kettle type reactor, a tubular type reactor and other reactors with mixing action. The pre-contact temperature can be controlled between-10 ℃ and 60 ℃, and the preferred temperature is 0 ℃ to 30 ℃. The pre-contact time is controlled to be 0.1-180min, and the preferable time is 5-30 min.

In the step A, the catalyst which is or is not pre-contacted is subjected to prepolymerization treatment, and the prepolymerization reactor can be in a kettle type, a loop type or other forms with mixing action. The prepolymerization can be carried out continuously under liquid phase bulk conditions or intermittently in an inert solvent. The temperature of the prepolymerization can be controlled between-10 ℃ and 60 ℃, preferably 0-40 ℃. The ratio of prepolymerization is controlled to 0.5-1000 times, preferably 1.0-500 times.

The copolymerization in step B may be carried out continuously or batchwise.

The copolymerization according to step B can be carried out in one or more reactors connected in series, preferably in a single reactor, in order to ensure a narrow molecular weight distribution. The polymerization reactor in step B may be a liquid phase reactor or a gas phase reactor.

The liquid phase reactor may be one of a loop type or a tank type reactor. The temperature of the liquid phase polymerization reaction is 30-150 ℃, and preferably 60-95 ℃; the reaction pressure is 1-8MPa, preferably 1.2-5.5 MPa; the reaction time is 10-180min, preferably 20-120 min; the molar concentration of the butene fed into the reactor is 0-35%, preferably 4-22%; the molar concentration of hydrogen is 0-4000ppm, preferably 300-2000 ppm.

The gas phase reactor may be in the form of a stirred tank reactor, a horizontal stirred reactor, a vertical stirred reactor, a fluidized bed reactor, or the like. The gas-phase polymerization temperature is 0-150 ℃, and preferably 40-100 ℃; the polymerization pressure is more than or equal to the normal pressure, and preferably 0.5-2.5 MPa; the reaction time is 10 to 180 minutes, preferably 20 to 120 minutes; the molar concentration of the butene fed into the reactor is 0-35%, preferably 4-22%; the molar concentration of hydrogen is 0-8000ppm, preferably 300-4000 ppm.

And D, transferring the polypropylene particles obtained by the reaction in the step B into a separation tank, and separating the polypropylene from the components such as propylene, comonomer, hydrogen and the like to obtain the polypropylene random copolymer base material. The separation may be by flash separation. The conditions for the flash separation include: the temperature is 40-100 ℃, preferably 50-85 ℃; the pressure is 0.1-2.5MPa, preferably 0.3-2 MPa.

According to one embodiment of the present invention, the process of the present invention further comprises preparing a polypropylene random copolymer base material according to the above process.

According to the invention, the mixing can be carried out in a twin-screw extruder, and therefore, the mixing is preferably carried out in the following manner: and (3) putting the mixture containing the polypropylene random copolymer base material, the degrading agent, the antioxidant and the halogen absorbent into a double-screw extruder to enable the polypropylene random copolymer to generate free radical degradation reaction.

Wherein the twin screw extruder comprises a plurality of temperature control sections. Generally, the temperature of each section of the twin-screw extruder is controlled within the range of 180-. The (main machine) rotation speed of the double-screw extruder is 200-600rpm, preferably 250-400 rpm.

The invention also relates to the propylene-butadiene random copolymerization polypropylene prepared by the method.

The present invention will be described in detail below by way of examples. In the following examples, antioxidant B501W is a Pasteur IRGANOX B501W product; the double-screw extruder is a GLS-30B plastic granulator of Suzhou Congrale rubber and plastic machinery Limited company;

the relevant data in the examples were obtained according to the following test methods:

content of butene and ethylene in the polymer: measuring by adopting an infrared spectrum method;

② polymer room temperature xylene soluble content (XS): measured according to astm d 5492;

(iii) melt index (melt index, MFR): measured according to GB/T3682-2000 with a melt index apparatus model 7026 from CEAST, at 230 ℃ under a load of 2.16 kg;

bending modulus: measured according to GB/T9341-2008;

tensile strength: measured according to GB/T1040.1-2006;

sixthly, molecular weight distribution (Mw/Mn): measured by PL-GPC 220 gel permeation chromatography of Polymer Laboratories, UK;

seventh, yellow index: measured according to GB/T2409-1980;

melting temperature: the measurement was carried out according to GB/T19466.3-2004 using a differential scanning calorimeter of the type DSC-7 from Perkin-Elmer company.

Example 1

A polymerization stage:

the base material of the propylene-butadiene copolymer polypropylene of the invention is carried out on a 25kg/h scale loop polypropylene pilot plant. The device mainly comprises a pre-complexing reactor, a pre-polymerization reactor, a loop reactor and a flash tank.

(1) Pre-complexing and pre-polymerizing

The flow rate of the main catalyst (HR catalyst, supplied by Beijing Odada division of China petrochemical catalyst Co.) was 0.8g/HR, the flow rate of the cocatalyst (triethylaluminum, TEA) was 6.3g/HR, the flow rate of the external electron donor (cyclohexylmethyldimethoxysilane, CHMMS) was 1.05g/HR, and the pre-complexing (contact) reaction was carried out at 6 ℃ for 8 min.

And continuously adding the catalyst system after the pre-complexation into a continuous stirring tank type prepolymerization reactor, and carrying out prepolymerization reaction under the environment of a propylene liquid phase body, wherein the temperature is 15 ℃, the retention time is about 12min, and the prepolymerization multiple of the catalyst is about 160 times under the condition.

(2) Propylene polymerization

Continuously introducing the prepolymerized catalyst into a loop reactor to perform propylene polymerization reaction, wherein the temperature of the loop polymerization reaction is 70 ℃, the reaction pressure is 4MPa, 1-butene and hydrogen are added into propylene feed of the loop reactor, the molar concentrations of the 1-butene and the hydrogen detected by online chromatography are respectively about 11.5 percent and 750ppm, the retention time is 1h, and the reactor discharges to a flash tank; the operating temperature of the flash tank is 70 ℃, the operating pressure is 1.8MPa, the polymer powder A (the low-melting-index polypropylene random copolymer base material) is finally obtained after separation, and the molecular weight distribution, the butene content and the melting index of the polymer powder A are tested.

The polymerization parameters and the data of the results of the tests are shown in Table 1.

And (3) a granulation stage:

100 parts by weight of polymer powder A, 0.053 part by weight of a degradation agent (2, 5-dimethyl-2, 5-bis (tert-butylperoxy) hexane), 0.2 part by weight of an antioxidant (1790:168 ═ 1:1(g/g)) and 0.05 part by weight of a halogen absorbent (calcium stearate) are blended, and then the blended mixture is extruded and granulated by a double-screw extruder to obtain polymer granules B (propylidene random copolymer polypropylene), and parameters such as molecular weight distribution and melt index of the polymer granules B are tested. The rotation speed of the screw extruder is 350rpm, and the temperatures of the first section to the sixth section are respectively 200 ℃, 210 ℃, 215 ℃ and 210 ℃.

The polymer pellet test results are shown in table 2.

Example 2

A polymerization stage: same as example 1

And (3) a granulation stage: 100 parts of polymer powder A, 0.051 part of degrading agent (dicumyl peroxide), 0.3 part of antioxidant (B501W) and 0.04 part of halogen absorbent (zinc stearate) are blended, and after blending, the polymer powder B (propylbutan random copolymer polypropylene) is obtained by extrusion and granulation through a double-screw extruder, and parameters such as molecular weight distribution, melt index and the like are tested. The rotation speed of the screw extruder is 350rpm, and the temperatures of the first section to the sixth section are respectively 200 ℃, 215 ℃, 205 ℃ and 210 ℃.

Example 3

A polymerization stage: same as example 1

And (3) a granulation stage: 100 parts by weight of polymer powder A, 0.05 part by weight of a degradation agent (3,6, 9-triethyl-3, 6, 9-trimethyl-1, 4, 7-triperoxonane), 0.25 part by weight of an antioxidant (1024:168 ═ 2:1) and 0.06 part by weight of a halogen absorbent (sodium stearate) are blended, and then the blended mixture is extruded and granulated by a double-screw extruder to obtain polymer granules B (polypropylene random copolymer) and parameters such as molecular weight distribution, melt index and the like of the polymer granules B are tested. The rotation speed of the screw extruder was 350rpm, and the temperatures of the first to sixth stages were 205 ℃, 210 ℃, 215 ℃, 210 ℃ respectively.

Example 4

A polymerization stage: same as example 1

And (3) a granulation stage: the same as example 1, except that antioxidant 1790 was changed to antioxidant 1010 in the granulation stage, and the addition amount and the mixture ratio were unchanged.

Example 5

A polymerization stage: the same as in example 1, except that the amount of 1-butene added was adjusted during the polymerization and the molar concentration of 1-butene measured by on-line chromatography was 7%.

And (3) a granulation stage: the same as in example 1.

Example 6

A polymerization stage: the same as in example 1, except that the amount of 1-butene added was adjusted during the polymerization and the molar concentration of 1-butene measured by on-line chromatography was 14%.

And (3) a granulation stage: the same as in example 1.

Example 7

A polymerization stage: the same as example 1, except that the amount of hydrogen added was adjusted in the course of polymerization to give a hydrogen molar concentration of 1050ppm by on-line chromatography.

And (3) a granulation stage: the same as in example 1, except that the amount of the degradation agent added was adjusted to 0.038 parts by weight.

Example 8

The preparation of propylene random copolymer polypropylene was carried out as described in example 1, except that the antioxidant was a mixture of antioxidant 3114, antioxidant 330 and antioxidant 168, in a weight ratio of 1: 1: 1.

comparative example 1

A polymerization stage: the same as example 1, except that the polymerization process was carried out by replacing 1-butene with ethylene and carrying out propylene ethylene random polymerization, the molar concentrations of ethylene and hydrogen measured by on-line chromatography were about 2.54% and 750ppm, respectively.

And (3) a granulation stage: the same as in example 1, except that the degrading agent was added in an amount of 0.062 parts by weight. In experiments, it is found that if the addition amount of the degradation agent is less than 0.062 parts by weight, the melt index of the propylene-ethylene random copolymer polypropylene is significantly less than 35.5g/10 min.

Comparative example 2

Homopolypropylene was prepared according to the method of comparative example 1, except that homopolymerization of propylene was carried out without adding 1-butene during polymerization and the amount of the degradation agent added during granulation was 0.062 parts by weight.

Comparative example 3

A comparative test was carried out on commercially available homo-polypropylene Y35 (Luoyang Branch of petrochemical Co., Ltd., China).

Comparative example 4

A comparison test was carried out on commercially available polypropylene Y35XB (Changjingtie, Inc., petrochemical Co., Ltd., China).

TABLE 1

TABLE 2

The molecular weight distribution of the degraded polypropylene is less than 2.8, which is obviously less than the molecular weight distribution of the commercially available Y35 and Y35XB materials, and the melting temperature is less than 150 ℃, which is lower than that of homopolymerization products such as Y35 and the like by more than 10 ℃, thus effectively reducing the energy consumption for processing.

As can be seen from the results of example 1 and comparative example 1, the tensile strength of the degraded polypropylene is more than 27MPa, which is significantly larger than that of the degraded polypropylene. The content of xylene solubles in the polypropylene random copolymer of propylene and ethylene is obviously lower than that of the polypropylene random copolymer of propylene and ethylene. Degrading to obtain the final product with the same melt index, wherein the dosage of the degrading agent used by the polypropylene random is 85.5 percent of that of the homo-polypropylene degrading agent, and the dosage of the degrading agent is obviously reduced.

Further spinning experimental results (not shown) show that the obtained polypropylene random copolymer fiber material has good spinnability, and under the same spinning process, the non-woven fabric produced by the polypropylene random copolymer fiber material has softer touch compared with a homopolymerization product and is equivalent to the performance of an ethylene propylene random product.

The preferred embodiments of the present invention have been described above in detail, but the present invention is not limited thereto. Within the scope of the technical idea of the invention, many simple modifications can be made to the technical solution of the invention, including combinations of various technical features in any other suitable way, and these simple modifications and combinations should also be regarded as the disclosure of the invention, and all fall within the scope of the invention.