CN112194848B

CN112194848B - Polypropylene composition containing nucleating agent, modified polypropylene and preparation method thereof

Info

Publication number: CN112194848B
Application number: CN202011024414.XA
Authority: CN
Inventors: 包璐璐; 郭晓东; 刘义; 韩李旺; 王勇; 张箭飞; 苟荣恒; 李国锋; 杜善明
Original assignee: Shenhua Xinjiang Chemical Co ltd; China Shenhua Coal to Liquid Chemical Co Ltd
Current assignee: Shenhua Xinjiang Chemical Co ltd; China Shenhua Coal to Liquid Chemical Co Ltd
Priority date: 2020-09-25
Filing date: 2020-09-25
Publication date: 2023-01-06
Anticipated expiration: 2040-09-25
Also published as: CN112194848A

Abstract

The invention relates to the technical field of polypropylene material preparation, and discloses a polypropylene composition containing a nucleating agent, modified polypropylene and a preparation method thereof. The polypropylene composition contains polypropylene, an antioxidant, a halogen absorbent and a nucleating agent; the nucleating agent contains an organic carboxylate nucleating agent and an optional sorbitol nucleating agent and/or an organic phosphate nucleating agent; wherein the organic carboxylate nucleating agent contains organic carboxylic acid calcium salt. The modified polypropylene provided by the invention has obviously improved properties in the aspects of transparency, high temperature resistance, flexural modulus, tensile yield strength and the like.

Description

Polypropylene composition containing nucleating agent, modified polypropylene and preparation method thereof

Technical Field

The invention relates to the technical field of polypropylene material preparation, in particular to a polypropylene composition containing a nucleating agent, a method for preparing modified polypropylene by applying the polypropylene composition containing the nucleating agent and the modified polypropylene prepared by the method.

Background

The polypropylene is one of five general-purpose plastics with the largest output and the widest application, and is widely applied to a plurality of fields of automobiles, packaging, textiles, medicine and health and the like due to the characteristics of low density, corrosion resistance, excellent mechanical property, easy processing and forming and the like. However, the domestic and foreign polypropylene capacity and consumption are continuously in a rapid growth situation in recent years, the domestic polypropylene capacity reaches 2500 million tons in 2019, new capacity is continuously put on the market in the next few years, and the capacity faces serious surplus. In addition, polypropylene is a semicrystalline polymer, and has large spherulites inside, which causes low impact strength of polypropylene, severe post-shrinkage of products, insufficient rigidity, dimensional stability or transparency in use, and the like, which seriously affects the use performance of polypropylene resin. Therefore, the development of high value-added polypropylene has become a trend in recent years.

Homopolymerized injection molding polypropylene is taken as one kind of polypropylene modified material, is widely applied to the fields of home decoration, packaging, building materials, medicines and the like, and is always well paid attention by people. The domestic petrochemical industry reports the production and application of V30G, Z S and other common homopolymerized polypropylene, the performance of the homopolymerized polypropylene has the defects of poor product transparency and relatively poor mechanical property and thermodynamic property, and the application range is limited to a certain extent.

Therefore, there is a need for a modified polypropylene excellent in transparency, high temperature resistance, flexural modulus, tensile yield strength and the like, and a method for producing the same.

Disclosure of Invention

The invention aims to improve the properties of the polypropylene composition products in the aspects of transparency, flexural modulus, tensile yield strength, high temperature resistance and the like.

In order to achieve the above objects, a first aspect of the present invention provides a polypropylene composition containing a nucleating agent, the composition containing polypropylene, an antioxidant, a halogen absorbent and the nucleating agent;

the nucleating agent contains an organic carboxylate nucleating agent and an optional sorbitol nucleating agent and/or an organic phosphate nucleating agent;

wherein the organic carboxylate nucleating agent contains organic carboxylic acid calcium salt.

A second aspect of the present invention provides a process for preparing a modified polypropylene, the process comprising:

the components of the polypropylene composition containing the nucleating agent in the first aspect are subjected to melt blending at 180-230 ℃, extrusion granulation and drying.

In a third aspect of the present invention, there is provided a modified polypropylene obtained by the process according to the second aspect of the present invention.

Wherein the melt index of the modified polypropylene is 20-35g/10min, the haze is less than or equal to 25%, the yellow index is less than or equal to-4, the flexural modulus is greater than or equal to 1800MPa, the tensile yield strength is greater than or equal to 40MPa, and the heat distortion temperature is greater than 100 ℃.

Compared with the prior art, the modified polypropylene provided by the invention has obviously improved properties in the aspects of transparency, high temperature resistance, flexural modulus, tensile yield strength and the like.

Specifically, the product of the modified polypropylene composition provided by the invention has the following advantages:

(1) Compared with the existing common V30G, Z S polypropylene resin, the polypropylene composition product (namely modified polypropylene) provided by the invention has obviously better transparency, for example, lower haze and yellow index and higher glossiness;

(2) In some preferred embodiments, compared with the existing ordinary V30G, Z S polypropylene resin, the polypropylene composition product provided by the invention has the advantages that the elastic modulus and the tensile yield strength are obviously improved while the appropriate melt index is ensured;

(3) In some preferred embodiments, the polypropylene composition product provided by the invention has outstanding heat resistance, specifically, the polypropylene composition product has higher crystallization temperature and heat distortion temperature, shorter semi-crystallization time and the like;

(4) In some preferred embodiments, the polypropylene composition product provided by the invention has substantially similar longitudinal and transverse shrinkage rates, so that the warping phenomenon of the product in the injection molding process is effectively avoided, and the quality stability of the product is further improved.

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 first aspect of the invention provides a polypropylene composition containing a nucleating agent, which contains polypropylene, an antioxidant, a halogen absorbent and the nucleating agent;

Preferably, the calcium organic carboxylate salt may be the nucleating agent HPN-900ei (available from Milliken (Millken)); wherein the nucleating agent HPN-900ei is blue free-flowing powder with bulk density of 0.4g/cm ³ The particle size D95 is less than 20 microns.

In the present invention, the polypropylene has a Melt Flow Rate (MFR) of 2 at 230 ℃ under a load of 2.16kg0-35g/10min, preferably 25-30g/10min; the density is 0.89-0.91g/cm ³ . The polypropylene is commercially available and may also be prepared by polymerization. For example, it can be obtained by a commercially available Z30S for marine refining, V30G for petrochemical refining, or a polymerization method as described below.

According to some embodiments of the present invention, in order to provide more excellent performance in various aspects of the product (modified polypropylene) of the polypropylene composition, the addition amount of each component in the polypropylene composition is required, and preferably, the antioxidant is 0.05 to 0.3 parts by weight, the halogen absorbent is 0.01 to 0.2 parts by weight, and the nucleating agent is 0.04 to 0.3 parts by weight, relative to 100 parts by weight of the polypropylene.

More preferably, the antioxidant is contained in an amount of 0.1 to 0.2 parts by weight, the halogen absorbent is contained in an amount of 0.02 to 0.1 parts by weight, and the nucleating agent is contained in an amount of 0.06 to 0.25 parts by weight, relative to 100 parts by weight of the polypropylene.

Further preferably, the content of the antioxidant is 0.08-0.15 parts by weight, the content of the halogen absorbent is 0.04-0.08 parts by weight, and the content of the nucleating agent is 0.08-0.2 parts by weight, relative to 100 parts by weight of the polypropylene.

According to some embodiments of the present invention, the polycarboxylate-type nucleating agent further comprises at least one of sodium benzoate (available from echiee (shanghai) chemical industry development limited), bis [ 4-tert-butylbenzoic acid ] aluminum hydroxide (available from shanghai cushing medicine technology limited, trademark AL-PTBBA), and bicyclo [2,2,1] heptane-2,3-dicarboxylate (available from Milliken (Millken), trademark HPN-68).

According to some embodiments of the present invention, preferably, the organic carboxylate-based nucleating agent further comprises bis [ 4-tert-butylbenzoic acid ] aluminum hydroxide (trade name AL-PTBBA, available from Shanghai Fuxin pharmaceutical science and technology Co., ltd.) and bicyclo [2,2,1] heptane-2,3-dicarboxylate (trade name HPN-68, available from Milliken (Millken) Co., ltd.).

According to some embodiments of the invention, the weight ratio of bis [ 4-tert-butylbenzoic acid ] aluminum hydroxide to bicyclo [2,2,1] heptane-2,3-dicarboxylate is preferably 1: (0.5-1.5), more preferably 1: (1-1.2).

According to some embodiments of the invention, the weight ratio of the organic calcium carboxylate salt, aluminum bis [ 4-tert-butylbenzoate ] hydroxide, and bicyclo [2,2,1] heptane-2,3-dicarboxylate salt is preferably 1: (0.1-0.8): (0.2-1.2); more preferably 1: (0.4-0.6): (0.5-0.8).

According to some embodiments of the invention, the nucleating agent comprises an organic carboxylate type nucleating agent and a sorbitol type nucleating agent.

Wherein the content weight ratio of the organic carboxylate nucleating agent to the sorbitol nucleating agent is 1: (0.4-2), preferably 1: (0.5-1).

Preferably, the sorbitol-based nucleating agent is selected from 1,3.

According to some embodiments of the invention, the nucleating agent comprises an organic carboxylate-based nucleating agent and an organic phosphate-based nucleating agent.

Preferably, the content weight ratio of the nucleating agent organic carboxylate nucleating agent to the nucleating agent organic phosphate can be 1: (0.2-2), more preferably 1: (0.5-1).

Preferably, the organophosphate-based nucleating agent is selected from at least one of 2,2 '-methylene bis (4,6-di-tert-butylphenyl) sodium phosphate (brand NA-11), 2,2' -methylene-bis (4,6-di-tert-butylphenyl) aluminum hydroxide (brand NA-21), and 2,2 '-methylene bis (4,6-di-tert-butylphenyl) sodium phosphate (brand NA-71), more preferably 2,2' -methylene bis (4,6-di-tert-butylphenyl) sodium phosphate (brand NA-71).

According to some embodiments of the present invention, the nucleating agent comprises an organic carboxylate-based nucleating agent, the sorbitol-based nucleating agent, and the organic phosphate-based nucleating agent;

wherein the weight content ratio of the organic carboxylate nucleating agent to the sorbitol nucleating agent to the organic phosphate nucleating agent can be 1: (0.5-2): (0.5-2), preferably 1: (0.7-1.5): (0.7-1.5).

According to an embodiment of the present invention, the antioxidant may be a hindered phenol antioxidant and a phosphite antioxidant;

preferably, the content weight ratio of the hindered phenol antioxidant to the phosphite antioxidant is 1: (1-2).

Preferably, the hindered phenolic antioxidant is selected from at least one of beta- (3,5-di-tert-butyl-4-hydroxyphenyl) octadecyl propionate (referred to as antioxidant 1076), pentaerythrityl tetrakis [ beta- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate (referred to as antioxidant 1010) and 2,6-di-tert-butyl-p-cresol (referred to as antioxidant 264), more preferably pentaerythrityl tetrakis [ beta- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate (referred to as antioxidant 1010).

Preferably, the phosphite antioxidant is selected from the group consisting of trisnonylphenyl phosphite (TNPP), pentaerythritol distearyl diphosphite (referred to as antioxidant 618), tris [ 2.4-di-tert-butylphenyl ] phosphite (referred to as antioxidant 168), and didodecyl thiodipropionate (antioxidant DLTP), more preferably tris [ 2.4-di-tert-butylphenyl ] phosphite (referred to as antioxidant 168).

According to some embodiments of the present invention, the halogen absorbent may be selected from at least one of hydrotalcite, calcium stearate, and zinc stearate, preferably calcium stearate.

In the second aspect of the present invention, the characteristics of the polypropylene composition containing a nucleating agent, such as the types and contents of the components, described in the first aspect, are not repeated, and are completely the same as the counterparts described in the first aspect, and those skilled in the art should not be construed as limiting the present invention.

In the present invention, preferably, the polypropylene, the antioxidant, the halogen absorbent and the nucleating agent are mixed, and the resulting mixture is fed into a twin-screw extruder, and the speed of the screws is adjusted to control the temperature of each zone separately; and melting, shearing, dispersing, compressing, exhausting and plasticizing the mixture in a screw and a cylinder of the extruder, extruding the mixture through a die head, cooling by water, drying (air drying) and granulating to obtain the modified polypropylene.

According to the preferred embodiment of the invention, the polypropylene, the hindered phenol antioxidant, the phosphite antioxidant, the halogen absorbent and the nucleating agent are mixed for 10-30min at room temperature, the rotating speed of a mixing roll is 10-30r/min, the secondary product and the obtained auxiliary agent mixture are fed into a double-screw extruder, the rotating speed of a screw is adjusted to be 100-200rpm, and the temperature of each section of a cylinder is respectively controlled to be 180-230 ℃; and melting, shearing, dispersing, compressing, exhausting and plasticizing the mixture in the extruder system, then extruding the mixture through a die head, cooling by water, drying (air drying) and granulating to obtain the modified polypropylene.

In the present invention, the polypropylene may be obtained commercially, or the polypropylene may be prepared by an operation comprising the steps of:

(1) In the presence of a catalyst and hydrogen, carrying out a first polymerization reaction on first liquid-phase propylene to obtain a polypropylene primary product;

(2) In the presence of a catalyst and hydrogen, carrying out a second polymerization reaction on the polypropylene primary product and second liquid-phase propylene to obtain a polypropylene secondary product;

(3) And (3) removing hydrocarbon substances (propylene, propane and ethane) dissolved in the polypropylene secondary product prepared in the step (2), and deactivating the residual catalyst to obtain the polypropylene.

Preferably, in the step (1), the catalyst comprises a main catalyst, a cocatalyst and a modifier;

preferably, the procatalyst is a ziegler-natta catalyst system selected from at least one of CDi, SAL and P100, more preferably, the ziegler-natta procatalyst is SAL with 30% mineral oil in the SAL.

Preferably, the cocatalyst is an aluminum alkyl compound selected from at least one of triethylaluminum, triisobutylaluminum, tri-n-butylaluminum, tri-n-hexylaluminum and tri-n-octylaluminum, more preferably, the aluminum alkyl is triethylaluminum;

preferably, the modifier is an organic alkyl modifier selected from at least one of diisobutyldimethoxysilane (DIBDMS), diisopropyldimethoxysilane (DIPDMS), and Tetraethoxysilane (TEOS), and more preferably, the organosilane modifier is diisobutyldimethoxysilane (DIBDMS).

Generally, in the first polymerization reaction, the main catalyst, the cocatalyst and the modifier can be added in a certain proportion for polymerization, and preferably, the main catalyst comprises active center TiCl ₄ Supported MgCl ₂ And an internal electron donor di-n-butyl phthalate; more preferably, the main catalyst has a titanium component content of 1.6 to 2.6wt% and a magnesium component content of 17.6 to 20.6wt%.

Preferably, the dosage ratio of the cocatalyst to the main catalyst is (3-6): 1, preferably (4-5): 1;

preferably, the dosage ratio of the cocatalyst to the modifier is (3-8) in terms of Al/Si molar ratio: 1, preferably (4-6): 1.

preferably, the conditions of the first polymerization reaction include: the feeding amount of the main catalyst is 2-10kg/h; the molar ratio of the hydrogen to the first liquid phase propylene is controlled to be 1-1.5 percent; the temperature of the first polymerization reaction is 55-80 ℃, and the pressure is 2-2.5MPa;

preferably, the feeding amount of the main catalyst is 4-6kg/h, and the molar ratio of the hydrogen to the first liquid phase propylene is controlled to be 0.8-1.2%; the temperature of the first polymerization reaction is 60-70 ℃; the pressure of the first polymerization reaction is 2.1-2.3MPa;

the conditions of the second polymerization reaction include: the molar ratio of the hydrogen to the second liquid phase propylene is controlled to be 1-1.5 percent; the temperature of the second polymerization reaction is 55-80 ℃, and the pressure of the second polymerization reaction is 2-2.5MPa;

preferably, the molar ratio of the hydrogen to the second liquid phase propylene is controlled to be 0.8% to 1.2%; the temperature of the second polymerization reaction is 60-70 ℃, and the pressure of the second polymerization reaction is 2.1-2.3MPa.

Preferably, the first polymerization reaction is carried out in a first gas-phase reactor and the second polymerization reaction is carried out in a second gas-phase reactor; more preferably, the first gas phase reactor and the second gas phase reactor are both horizontal reactors.

Preferably, the preparation of the polypropylene is carried out in series in two uniquely designed horizontal full mixed flow reactors, and T-shaped and gate-shaped stirrers are respectively designed in the two horizontal reactors, so that the sufficient stirring of a powder bed can be ensured, the temperature distribution of a bed layer is uniform, and the local stringing and caking of polymers are avoided.

Preferably, in the first polymerization reaction and the second polymerization reaction, the catalyst can be carried by liquid phase propylene to be sprayed into the reactor through the nozzle of the horizontal reactor, so that the feeding time is shortened, and the blockage of the nozzle and the equipment conveying pipeline by the catalyst is avoided.

Preferably, the first polymerization reaction and the second polymerization reaction can be carried out by introducing gas-phase propylene, H ₂ Can be carried into the reactor by the gas phase propylene.

Preferably, the level of the powder bed in the polymerization reactor is critical to the system stability production of propylene polymerization, the catalyst yield may be low due to the low level of the powder bed, and the catalyst is sprayed on the exposed metal surface of the reactor stirrer to form a strip material; the phenomenon that powder materials are entrained, catalysts and raw material propylene are locally agglomerated due to uneven distribution possibly caused by overhigh material level of a bed layer can ensure the stability of polymerization reaction by selecting proper material level of a polymerization reactor; therefore, preferably, the level of the first gas-phase reactor in the first polymerization reaction can be controlled to be 70 to 90%, preferably 75 to 85%, and the level of the second gas-phase reactor in the second polymerization reaction can be controlled to be 70 to 90%, preferably 75 to 85%.

Preferably, the polymerization load of the first polymerization reaction is from 20 to 50 tons, preferably from 25 to 40 tons; the polymerization load of the second polymerization reaction is 8 to 25 tons, preferably 10 to 20 tons.

Preferably, in the step (1), the melt index of the polypropylene primary product can be 20-35g/10min, and more preferably 25-30g/10min; and/or, in step (2), the polypropylene subproduct may have a melt index of 20 to 35g/10min, preferably 25 to 30g/10min.

According to the method of the present invention, preferably, before the step (3), the method further comprises: removing residual dissolved hydrocarbon in the secondary product obtained in the step (2), and simultaneously carrying out deactivation treatment on the residual catalyst in the polypropylene secondary product.

In the present invention, preferably, the dissolved hydrocarbon is low-concentration propane or ethane.

According to some embodiments of the present invention, preferably, the method of deactivating and devolatilizing residual catalyst and dissolved hydrocarbons in polypropylene sub-product comprises: mixing nitrogen and steam, entering through a distributor at the bottom of a degassing bin of secondary product (powder) collecting equipment, and contacting with a secondary product in the degassing bin; wherein the nitrogen acts as a stripping gas to facilitate removal of dissolved hydrocarbons from the polypropylene subforms, while water reacts with residual catalyst and cocatalyst to deactivate them.

In a third aspect of the present invention, there is provided a modified polypropylene obtainable by the process according to the second aspect of the present invention.

Preferably, the melt index of the modified polypropylene is 25-30g/10min, the haze is less than or equal to 23.98%, the yellow index is less than or equal to-5, the flexural modulus is greater than or equal to 1850MPa, the tensile yield strength is greater than or equal to 45MPa, and the thermal deformation temperature is greater than 110 ℃.

The present invention will be described in detail below by way of examples. In the following examples, various raw materials used are commercially available ones unless otherwise specified.

Nucleating agent: HPN-900ei (calcium organic carboxylate formulations) (hereinafter, referred to as nucleator 1 in the examples) was purchased from Milliken (Millken).

Nucleating agent: bis [ 4-tert-butylbenzoic acid ] aluminum hydroxide (brand AL-PTBBA) (in the examples below, referred to as nucleating agent 2) was purchased from shanghai kexin pharmaceutical science co.

Nucleating agent: bicyclo [2,2,1] heptane-2,3-dicarboxylate salt (designation HPN-68) (in the examples below, referred to as nucleator 3) was purchased from meleken (Millken).

Nucleating agent: 1,3, 2,4-bis (3,4-dimethylbenzylidene) -D-sorbitol (trade name Millad 3988) (in the examples below, referred to as nucleator 4) was purchased from Milliken (Millken).

Nucleating agent: 2,2' -sodium methylenebis (4,6-di-t-butylphenyl) phosphate (brand NA-71) (in the following examples, referred to as nucleating agent 5) was purchased from Ai Dike (Asahi Denka).

Nucleating agent: sodium benzoate (hereinafter, referred to as nucleating agent 6 in the examples) was purchased from Chishiai (Shanghai) chemical industry development Co., ltd.

Hindered phenol antioxidant: tetrakis [ beta- (3,5-di-tert-butyl-4-hydroxyphenyl) propanoic acid ] pentaerythritol ester (referred to as antioxidant 1010) (hereinafter, in the examples, referred to as antioxidant 1) was purchased from BASF corporation.

Hindered phenol antioxidant: octadecyl beta- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate (referred to as antioxidant 1076) (hereinafter, in the examples, antioxidant 2) was purchased from Bailingwei technologies, beijing.

Phosphite ester antioxidant: tris [2, 4-di-tert-butylphenyl ] phosphite (referred to as antioxidant 168) (hereinafter, referred to as antioxidant 3 in the examples) was obtained from BASF corporation.

Phosphite ester antioxidant: didecyl thiodipropionate (antioxidant DLTP) (hereinafter, referred to as antioxidant 4 in the examples) was purchased from Shanghai Shinetite chemical technology Co., ltd.

Halogen absorbent: calcium stearate (hereinafter, referred to as halogen absorbent 1 in the examples) was purchased from Jiangsu Taihu lake New materials, inc.

Halogen absorbent: hydrated talc (hereinafter, referred to as halogen absorber 2 in the examples) was purchased from Kyowa corporation under the trade designation DHT-6.

In the following examples and comparative examples,

the melt flow rate of the polypropylene is determined according to ISO1133, 230 ℃/2.16 kg;

flexural modulus measured according to ISO 178: the experimental speed is 2mm/min, the length of the sample is 80mm, the width is 10mm, and the thickness is 4mm;

the simple beam notched impact strength was measured according to ISO 179: the length of the sample is 80mm, the width is 10mm, and the thickness is 4mm;

tensile yield strength was tested according to ISO 527: the stretching speed is 50mm/min;

haze was measured according to ASTM D1003;

gloss measured according to ASTM D523;

the yellowness index is measured according to astm d 6290;

heat distortion temperature measured according to ISO 75: the load is 450KPa, the heating rate is 2 ℃/min, and the initial temperature is 25 ℃;

the crystallization temperature is measured according to ISO 11357;

the half-crystallization time is measured according to ISO 11357;

the longitudinal shrinkage and the transverse shrinkage were measured according to ISO 294-4.

Preparation example: preparation of Polypropylene

(1) Placing first liquid-phase propylene, a main catalyst (SAL), triethylaluminum (TEAL) and a silane modifier (DIBDMS) into a first gas-phase reactor for polymerization, wherein the feeding amount of the main catalyst (SAL) is 5kg/h, and Al/Mg is 4:1, al/Si is 4:1, controlling the molar ratio of hydrogen to first liquid phase propylene to be 0.8%, controlling the temperature of first polymerization reaction to be 60 ℃, the reaction pressure to be 2.2MPa, controlling the material level of a first gas phase reactor to be 78%, and preparing a polypropylene primary product with the MFR of 27g/10 min.

(2) Feeding the polypropylene primary product prepared in the step (1) into a second gas phase reactor, and carrying out second liquid phase propylene and H ₂ Under the combined action of the two components, the reaction is continued; wherein the molar ratio of the hydrogen to the second liquid phase propylene is controlled to be 0.8 percent, the temperature of the second polymerization reaction is 65 ℃, the reaction pressure is 2.2MPa, the material level of the second gas phase reactor is controlled to be 76 percent, and the polypropylene subproduct with the MFR of 26g/10min is prepared.

Example 1

Mixing the polypropylene, the hindered phenol antioxidant, the phosphite antioxidant, the halogen absorbent and the nucleating agent obtained in the preparation example at the content ratio shown in table 1 at 25 ℃ and 20r/min for 10min, feeding the obtained mixture into a double-screw extruder, adjusting the rotating speed of a screw to be 150rpm, and controlling the temperatures of all sections to be 180 ℃, 190 ℃, 230 ℃, 210 ℃ and 190 ℃ respectively; and melting, shearing, dispersing, compressing, exhausting and plasticizing the mixture in a screw and a cylinder of the extruder, extruding the mixture through a die head, and carrying out water cooling, drying (air drying) and grain cutting to obtain the modified polypropylene S1.

The remaining examples and comparative examples were conducted in the same procedures as in example 1 except that the compositions for producing modified polypropylene were formulated differently, unless otherwise specified, and the specific conditions are shown in Table 1.

TABLE 1

TABLE 1 (Continue 1)

Table 1 (continuation 2)

Table 1 (continuation 3)

The results of measuring the appearance (color, black, large, small), melt index MFR, isotacticity of the modified polypropylenes of the above examples (S1 to S16) and the modified polypropylenes of the comparative examples (DS 1 to DS 6) are shown in Table 2, and the results of optical (haze, gloss, yellowness index), mechanical (flexural modulus, notched Izod impact strength, tensile yield strength), thermal (crystallization temperature, heat distortion temperature, half crystallization time), and shrinkage rate properties are shown in Table 3.

TABLE 2

TABLE 3

Table 3 (continuation 1)

Table 3 (Continue 2)

Table 3 (continuation 3)

As can be seen from tables 2 and 3, compared with the prior art, the modified polypropylene obtained by the invention has good appearance performance, proper melt index, high isotacticity and low ash content; meanwhile, the modified polypropylene obtained by the invention also has the advantages of lower haze and yellow index, higher glossiness, higher flexural modulus, simple beam notch impact strength and tensile yield strength, higher crystallization temperature and thermal deformation temperature, shorter semicrystallization time, similar longitudinal and transverse shrinkage rates and better cost performance.

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.

Claims

1. The polypropylene composition containing the nucleating agent is characterized by comprising polypropylene, an antioxidant, a halogen absorbent and the nucleating agent;

relative to 100 parts by weight of the polypropylene, the content of the antioxidant is 0.05-0.3 part by weight, the content of the halogen absorbent is 0.01-0.2 part by weight, and the content of the nucleating agent is 0.04-0.3 part by weight;

the antioxidant is hindered phenol antioxidant and phosphite antioxidant;

the hindered phenol antioxidant is selected from pentaerythritol tetrakis [ beta- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate ];

and/or the phosphite antioxidant is selected from tris [2,4-di-tert-butylphenyl ] phosphite;

the halogen absorbent is selected from calcium stearate;

the nucleating agent contains organic carboxylate nucleating agent and organic phosphate nucleating agent or the combination of sorbitol nucleating agent and organic phosphate nucleating agent;

the organic carboxylate nucleating agent contains organic calcium carboxylate;

the weight ratio of the organic carboxylate nucleating agent to the organic phosphate nucleating agent is 1 (0.5-1);

and/or the weight ratio of the organic carboxylate nucleating agent to the sorbitol nucleating agent to the organic phosphate nucleating agent is 1 (0.7-1.5) to (0.7-1.5).

2. The composition as claimed in claim 1, wherein the antioxidant is contained in an amount of 0.1 to 0.2 parts by weight, the halogen absorbent is contained in an amount of 0.02 to 0.1 parts by weight, and the nucleating agent is contained in an amount of 0.06 to 0.25 parts by weight, relative to 100 parts by weight of the polypropylene.

3. The composition of claim 1 or 2, wherein the polycarboxylate-type nucleating agent further comprises at least one of sodium benzoate, bis [ 4-tert-butylbenzoic acid ] aluminum hydroxide, and bicyclo [2,2,1] heptane-2,3-dicarboxylate.

4. The composition of claim 3, wherein said organocarboxylate-based nucleating agent further comprises bis [ 4-tert-butylbenzoic acid ] aluminum hydroxide and bicyclo [2,2,1] heptane-2,3-dicarboxylate.

5. The composition of claim 4, wherein the weight ratio of bis [ 4-tert-butylbenzoic acid ] aluminum hydroxide to bicyclo [2,2,1] heptane-2,3-dicarboxylate is 1 (0.5-1.5).

6. The composition of claim 5, wherein the weight ratio of bis [ 4-tert-butylbenzoic acid ] aluminum hydroxide to bicyclo [2,2,1] heptane-2,3-dicarboxylate is 1 (1-1.2).

7. The composition of any one of claims 1, 2 or 4 to 6, wherein the organophosphate-based nucleating agent is selected from 2,2 '-sodium methylene bis (4,6-di-t-butylphenyl) phosphate or 2,2' -methylene-bis (4,6-di-t-butylphenyl phosphate) aluminum hydroxide.

8. The composition as claimed in claim 7, wherein the organophosphate-based nucleating agent is selected from sodium 2,2' -methylenebis (4,6-di-tert-butylphenyl) phosphate.

9. The composition of claim 3, wherein said organophosphate-based nucleating agent is selected from the group consisting of sodium 2,2 '-methylenebis (4,6-di-t-butylphenyl) phosphate and 2,2' -methylene-bis (4,6-di-t-butylphenyl phosphate) basic aluminum.

10. The composition as claimed in claim 9, wherein the organophosphate-based nucleating agent is selected from 2,2' -sodium methylenebis (4,6-di-tert-butylphenyl) phosphate.

11. A process for preparing a modified polypropylene, comprising:

the polypropylene composition containing a nucleating agent according to any one of claims 1 to 10, wherein the components are melt blended at 180 to 230 ℃ and then extruded, pelletized and dried.

12. A modified polypropylene obtained by the method of claim 11, wherein the modified polypropylene has a melt index of 20 to 35g/10min, a haze of 25% or less, a yellowness index of 4 or less, a flexural modulus of 1800MPa or more, a tensile yield strength of 40MPa or more, and a heat distortion temperature of 100 ℃ or more.