CN116925468A - Syndiotactic polypropylene composite material with high crystallization temperature and high crystallization rate and preparation method thereof - Google Patents

Abstract

The invention discloses a syndiotactic polypropylene composite material with high crystallization temperature and high crystallization rate and a preparation method thereof; the composite material comprises the following components in parts by weight: syndiotactic polypropylene 82-98; 2-5 parts of polylactic acid; 0 to 10 percent of polyethylene; 0 to 10 portions of isotactic polypropylene; 0 to 15 percent of random copolymer polypropylene; 0 to 5 portions of ethylene-vinyl alcohol copolymer. The syndiotactic polypropylene composite material can be obtained by premixing the components and then mixing and granulating. Because the polylactic acid as the crystallization promoting component is added, if necessary, the compound components such as high-density polyethylene, isotactic polypropylene, atactic polypropylene, ethylene-vinyl alcohol copolymer and the like are added, the prepared composite material has higher crystallization temperature and crystallization rate, can solve a series of problems caused by lower crystallization temperature and crystallization rate of syndiotactic polypropylene in the process of processing and forming, and can keep better optical performance of the syndiotactic polypropylene by adding the crystallization promoting component consisting of the isotactic polypropylene or the atactic polypropylene and the polylactic acid.

Description

Syndiotactic polypropylene composite material with high crystallization temperature and high crystallization rate and preparation method thereof

Technical Field

The invention relates to the technical field of polymer composite materials, in particular to a syndiotactic polypropylene composite material with high crystallization temperature and high crystallization rate and a preparation method thereof.

Background

In 1987, after Fina petrochemical company developed a metallocene catalyst, it was used to catalyze propylene polymerization, and syndiotactic polypropylene (sPP) with a degree of syndiotacticity of more than 80% was also marketed later. While sPP has excellent toughness, optical properties, and radiation resistance, its industrialization process has encountered unprecedented difficulties. The main reason for this is that syndiotactic polypropylene has a different molecular structure compared to isotactic polypropylene (iPP), and ordered folding-crystallization of macromolecular chains due to temperature gradient driving is very difficult at the shaping stage of the processing. Even if the ambient temperature is reduced to room temperature, the entire non-isothermal crystallization process of sPP may last for 72 hours or even longer. The sPP crystallization property information obtained by this method is that the non-isothermal crystallization temperature of sPP with about 80% of syndiotactic degree is about 70 ℃ and the crystallization rate is far lower than that of iPP. Therefore, even if the forced cooling device sPP is used in the processing cycle of the conventional extrusion and injection molding processing equipment, the crystallization process is difficult to complete, and the dimensional stability of the product is poor.

In order to improve the crystallization properties of sPP, a great deal of research has been conducted in the industry. The main measures include adding nucleating agents suitable for isotactic polypropylene, blending with other types of polypropylene (including homo-polypropylene iPP and random copolymer polypropylene rPP), blending with High Density Polyethylene (HDPE), blending with crystalline copolymers (EAA, EVOH) containing ethylene segments. However, studies have found that, to date, the industry has not screened a highly effective nucleating agent for sPP to significantly improve the crystallization properties (crystallization temperature and crystallization rate) of sPP. The total isotactic polypropylene can raise the crystallization temperature of sPP to 80 ℃ or higher and improve the crystallization rate, but the addition ratio is required to be 10% or higher. Whereas iPP or rPP and sPP are partially compatible polymers, the addition ratio of more than 10% of iPP or rPP has significantly affected the optical and mechanical properties of sPP. HDPE can be added in a proportion of about 2% to raise the crystallization temperature of sPP to above 90 ℃, but the crystallization rate is rather lower than that of pure sPP due to the special crystallization mechanism of sPP, and HDPE is less compatible with sPP and the transparency of sPP added with HDPE is less. The crystalline copolymer (EAA, EVOH) containing ethylene chain segments is blended, the crystallization temperature of sPP can be increased to more than 80 ℃, and the crystallization rate of sPP is obviously improved, so that sPP can be processed by adopting conventional extrusion and injection molding processing equipment. The only adverse result is that even the addition of crystalline copolymers of 2% ethylene segments (EAA or EVOH) affects the transparency of the sPP.

Theoretical research and exploring experiments show that polylactic acid with certain crystallization performance (the main component is L-polylactic acid PLLA) can also promote the crystallization of sPP to a certain extent, and improve the crystallization performance of the sPP. Meanwhile, the PLA and the iPP or rPP are added in a compounding way to obtain the modified sPP with better transparency, and a certain breakthrough is achieved in the field of sPP crystallization promotion.

Disclosure of Invention

The invention aims to overcome the defects and the shortcomings of the prior art and provide a syndiotactic polypropylene composite material with high crystallization temperature and high crystallization rate and a preparation method thereof.

The composite material prepared by the preparation process has higher crystallization temperature and crystallization rate, so that a series of problems caused by lower crystallization temperature and crystallization rate of syndiotactic polypropylene in the process of processing and forming can be solved, the composite material has higher transparency, the optical performance advantage of sPP is maintained, the application of the composite material in the related field is hopefully expanded, and the high performance of syndiotactic polypropylene products is promoted.

The invention is realized by the following technical scheme:

the syndiotactic polypropylene composite material with high crystallization temperature and high crystallization rate comprises the following components in parts by weight:

the melt flow rate of the syndiotactic polypropylene is 1-20 g/10min (230 ℃,2.16 kg), and the syndiotactic degree is more than 80%.

The polylactic acid is polylactic acid with certain crystallization property (D-content is less than 1%), and the melt flow rate is 5-80 g/10min (190 ℃ C., 2.16 kg).

The polyethylene is preferably high density polyethylene with a melt flow rate of 0.5-10 g/10min (190 ℃ C., 2.16 kg).

The isotactic polypropylene has a melt flow rate of 2-30 g/10min (230 ℃ C., 2.16 kg) and an isotacticity of over 95%.

The melt flow rate of the random copolymer polypropylene is 2-20 g/10min (230 ℃,2.16 kg), and the ethylene content is 1-8%.

The melt flow rate of the ethylene-vinyl alcohol copolymer is 3-15 g/10min (210 ℃,2.16 kg), and the ethylene content is less than or equal to 50%.

The preparation method of the syndiotactic polypropylene composite material with high crystallization temperature and high crystallization rate comprises the following steps:

(1) Premixing: sequentially adding syndiotactic polypropylene, polylactic acid, polyethylene, isotactic polypropylene, random copolymer polypropylene, ethylene-vinyl alcohol copolymer and the like into a high-speed mixer according to a certain proportion for premixing, wherein the mixing temperature is 20-40 ℃, the rotating speed is 200-500 rpm, and the mixing time is 3-5 minutes, so as to obtain a premix of the syndiotactic polypropylene composite material;

(2) Mixing and granulating by a double-screw extruder: extruding and granulating the premix obtained in the step (1) by using a parallel co-rotating double-screw extruder with the length-diameter ratio of 42:1 and the screw diameter of 35 mm; the rotating speed of the feeding machine is set to be 10-50 rpm, and the rotating speed of the screw is set to be 100-300 rpm; the temperature of each section of the extruder is 160-200 ℃, and the syndiotactic polypropylene composite material is obtained.

The principle of the invention is as follows: polylactic acid (the main component is PLLA, the D-content is less than 1%) has certain crystallization performance, the non-isothermal crystallization temperature of the polylactic acid is obviously higher than that of syndiotactic polypropylene (the crystallization peak temperature is about 70 ℃), a certain proportion of PLA is doped into the syndiotactic polypropylene, and the PLA is crystallized first under the set processing condition to become a crystallization nucleation center, so that the syndiotactic polypropylene macromolecular chain is induced to be orderly folded under the drive of temperature gradient, and a crystal structure is formed. Meanwhile, because the crystallinity of PLA is not too high and the compatibility with syndiotactic polypropylene is not good, the PLA is dispersed in the syndiotactic polypropylene melt in a large amount of spherical phase-splitting structures (caused by thermodynamic incompatibility) under the strong shearing action of a double-screw extruder, and a large amount of nucleation centers are arranged at the cooling stage of the processing process to induce the syndiotactic polypropylene to form crystals, thereby being more beneficial to improving the crystallization rate of the syndiotactic polypropylene. Meanwhile, in the presence of isotactic polypropylene or atactic copolymerized polypropylene which is partially compatible with syndiotactic polypropylene, PLA may be dispersed more finely, and excellent transparency may be imparted to the syndiotactic polypropylene.

Compared with the prior art, the invention has the following advantages and effects:

(1) The addition of PLA in syndiotactic polypropylene can obviously improve the crystallization performance of syndiotactic polypropylene and increase the crystallization temperature and crystallization rate of syndiotactic polypropylene;

(2) When PLA is added, a syndiotactic polypropylene composite material with improved crystallization property can be obtained by adding HDPE, iPP, rPP or EVOH as an appropriate auxiliary. The improvement of the crystallization temperature of the syndiotactic polypropylene by the HDPE is more prominent, but the improvement of the crystallization rate of the syndiotactic polypropylene is not facilitated, and the transparency of the product is not ideal; when EVOH is added in an auxiliary way, the crystallization temperature of the syndiotactic polypropylene is improved over that of PLLA which is added singly, the crystallization rate is improved over that of HDPE which is added in an auxiliary way, and the transparency of the product is still not ideal; the crystallization temperature improvement of the syndiotactic polypropylene is basically equivalent to that of the syndiotactic polypropylene which is added with the auxiliary additive of the iPP or the rPP, the crystallization rate improvement is superior to that of the syndiotactic polypropylene which is added with the auxiliary additive of the HDPE and the EVOH, and most importantly, the optical performance of the obtained product is better, namely, the combination promotes the improvement of the comprehensive performance of the syndiotactic polypropylene.

Detailed Description

The present invention will be described in further detail with reference to specific examples.

In the embodiment of the invention, the syndiotactic polypropylene resin is polypropylene resin with the syndiotactic degree of more than 80mol percent, which is obtained by polymerization of propylene under the action of a metallocene catalyst, and has the melt flow rate of 2-10 g/10min (230 ℃ and 2.16 kg), and the product mPP6006 which is an industrial test product of the middle petroleum institute can be selected, and has the actual melt flow rate of 5.2g/10min (230 ℃ and 2.16 kg);

the melt flow rate of the polylactic acid is 5-80 g/10min (190 ℃,2.16 kg), and FY601 (D-content < 1%) of Anhuifengyuan can be selected, and the melt flow rate is 9g/10min (190 ℃,2.16 kg);

the melt flow rate of the high-density polyethylene is 0.3-10 g/10min (190 ℃,2.16 kg), and the high-density polyethylene HHM5502LW with the melt flow rate of about 0.35g/10min produced by the petrochemical industry can be selected;

the melt flow rate of the isotactic polypropylene is 2-30 g/10min (230 ℃,2.16 kg), the isotacticity is above 95%, and the isotactic polypropylene Z30S produced by the petrochemical industry under the name of China can be selected, and the actual melt flow rate is 24g/10min (230 ℃,2.16 kg);

the melt flow rate of the random copolymer polypropylene is 2-20 g/10min (230 ℃,2.16 kg), the ethylene content is 1-8%, B4908 produced by Yanshan petrochemical industry can be selected, and the actual melt flow rate is 8.9g/10min (230 ℃,2.16 kg);

the ethylene-vinyl alcohol copolymer E105B has a melt flow rate of 3 to 15g/10min (210 ℃,2.16 kg), an ethylene content of 50% or less, and optionally an ethylene content of 44% by weight of Japanese cola, and a melt flow rate of 13g/10min (210 ℃,2.16 kg).

The results of the test for crystallization properties in the examples and comparative examples of the present invention were all from a relaxation-resistant DSC214 thermal analyzer. The sample is melted and pressed into tablets to 1 Xphi 50mm, and the light transmittance and the haze of the sample are measured by adopting an SGW-80 haze meter according to the national standard of determination of light transmittance and haze of transparent plastics-GB/T2410-2008.

Example 1:

weighing the following raw materials in proportion: the syndiotactic polypropylene is 98 parts by mass and the polylactic acid is 2 parts by mass. The syndiotactic polypropylene and the polylactic acid are premixed, the mixing temperature is 20 ℃, the rotating speed is 200 revolutions per minute, and the mixing is carried out for 5 minutes. Then, the pre-mixed material is added into a parallel double-screw extruder from a feeding machine, and is melted, extruded and granulated. The process conditions are set as follows: the rotating speed of the screw is 200 revolutions per minute, the rotating speed of the feeding machine is 30 revolutions per minute, and the temperature of each section of the extruder is 16-200 ℃. And (5) water-passing and granulating the braces.

DSC test is carried out on the dried syndiotactic polypropylene composite material, all experiments are carried out in nitrogen atmosphere, the mass of the sample is 5-8 mg, the heating and cooling rates are 10K/min, and the test temperature ranges from 0 ℃ to 200 ℃. The test results are shown in Table 1.

The dried syndiotactic polypropylene composite material was melted at 200 ℃ and then pressed into a 1 xPhi 50mm wafer, and the light transmittance and haze thereof were measured by an SGW-80 haze meter according to the national standard "determination of light transmittance and haze of transparent plastics-GB/T2410-2008", and the results are shown in Table 1.

Example 2:

weighing the following raw materials in proportion: the syndiotactic polypropylene is 95 parts by mass and the polylactic acid is 5 parts by mass. The syndiotactic polypropylene and the polylactic acid are premixed, the mixing temperature is 30 ℃, the rotating speed is 300 revolutions per minute, and the mixing is carried out for 4 minutes. Then, the pre-mixed material is added into a parallel double-screw extruder from a feeding machine, and is melted, extruded and granulated. The process conditions are set as follows: the rotation speed of the screw is 300 revolutions per minute, the rotation speed of the feeder is 25 revolutions per minute, and the temperature of each section of the extruder is 160-200 ℃. And (5) water-passing and granulating the braces.

DSC test is carried out on the dried syndiotactic polypropylene composite material, all experiments are carried out in nitrogen atmosphere, the mass of the sample is 5-8 mg, the heating and cooling rates are 10K/min, and the test temperature ranges from 0 ℃ to 200 ℃. The test results are shown in Table 1.

The dried syndiotactic polypropylene composite material was melted at 200 ℃ and then pressed into a 1 xPhi 50mm wafer, and the light transmittance and haze thereof were measured by an SGW-80 haze meter according to the national standard "determination of light transmittance and haze of transparent plastics-GB/T2410-2008", and the results are shown in Table 1.

Example 3:

weighing the following raw materials in proportion: the syndiotactic polypropylene is 92 parts by mass, the polylactic acid is 2 parts by mass and the high-density polyethylene is 5 parts by mass. The syndiotactic polypropylene, polylactic acid and high density polyethylene are premixed, the mixing temperature is 40 ℃, the rotating speed is 500 revolutions per minute, and the mixing is carried out for 3 minutes. Then, the pre-mixed material is added into a parallel double-screw extruder from a feeding machine, and is melted, extruded and granulated. The process conditions are set as follows: the rotating speed of the screw is 250 revolutions per minute, the rotating speed of the feeding machine is 40 revolutions per minute, and the temperature of each section of the extruder is 160-200 ℃. And (5) water-passing and granulating the braces.

DSC test is carried out on the dried syndiotactic polypropylene composite material, all experiments are carried out in nitrogen atmosphere, the mass of the sample is 5-8 mg, the heating and cooling rates are 10K/min, and the test temperature ranges from 0 ℃ to 200 ℃. The test results are shown in Table 1.

The dried syndiotactic polypropylene composite material was melted at 200 ℃ and then pressed into a 1 xPhi 50mm wafer, and the light transmittance and haze thereof were measured by an SGW-80 haze meter according to the national standard "determination of light transmittance and haze of transparent plastics-GB/T2410-2008", and the results are shown in Table 1.

Example 4:

weighing the following raw materials in proportion: the syndiotactic polypropylene is 87 parts by mass, the polylactic acid is 3 parts by mass, and the isotactic polypropylene is 10 parts by mass. The syndiotactic polypropylene, polylactic acid and isotactic polypropylene are premixed, the mixing temperature is 25 ℃, the rotating speed is 500 revolutions per minute, and the mixing time is 5 minutes. Then, the pre-mixed material is added into a parallel double-screw extruder from a feeding machine, and is melted, extruded and granulated. The process conditions are set as follows: the rotation speed of the screw is 300 revolutions per minute, the rotation speed of the feeder is 50 revolutions per minute, and the temperature of each section of the extruder is 160-200 ℃. And (5) water-passing and granulating the braces.

DSC test is carried out on the dried syndiotactic polypropylene composite material, all experiments are carried out in nitrogen atmosphere, the mass of the sample is 5-8 mg, the heating and cooling rates are 10K/min, and the test temperature ranges from 0 ℃ to 200 ℃. The test results are shown in Table 1.

The dried syndiotactic polypropylene composite material was melted at 200 ℃ and then pressed into a 1 xPhi 50mm wafer, and the light transmittance and haze thereof were measured by an SGW-80 haze meter according to the national standard "determination of light transmittance and haze of transparent plastics-GB/T2410-2008", and the results are shown in Table 1.

Example 5:

weighing the following raw materials in proportion: the syndiotactic polypropylene is 82 parts by mass, the polylactic acid is 3 parts by mass, and the random copolymer polypropylene is 15 parts by mass. The syndiotactic polypropylene, polylactic acid and random copolymer polypropylene are premixed, the mixing temperature is 35 ℃, the rotating speed is 230 r/min, and the mixing time is 4 min. Then, the pre-mixed material is added into a parallel double-screw extruder from a feeding machine, and is melted, extruded and granulated. The process conditions are set as follows: the rotation speed of the screw is 280 rpm, the rotation speed of the feeder is 25 rpm, and the temperature of each section of the extruder is 160-200 ℃. And (5) water-passing and granulating the braces.

DSC test is carried out on the dried syndiotactic polypropylene composite material, all experiments are carried out in nitrogen atmosphere, the mass of the sample is 5-8 mg, the heating and cooling rates are 10K/min, and the test temperature ranges from 0 ℃ to 200 ℃. The test results are shown in Table 1.

The dried syndiotactic polypropylene composite material was melted at 200 ℃ and then pressed into a 1 xPhi 50mm wafer, and the light transmittance and haze thereof were measured by an SGW-80 haze meter according to the national standard "determination of light transmittance and haze of transparent plastics-GB/T2410-2008", and the results are shown in Table 1.

Example 6:

weighing the following raw materials in proportion: the syndiotactic polypropylene is 96 parts by mass, the polylactic acid is 2 parts by mass, and the ethylene-vinyl alcohol copolymer is 2 parts by mass. The syndiotactic polypropylene, polylactic acid and ethylene-vinyl alcohol copolymer are premixed, the mixing temperature is 30 ℃, the rotating speed is 400 rpm, and the mixing time is 3.5 minutes. Then, the pre-mixed material is added into a parallel double-screw extruder from a feeding machine, and is melted, extruded and granulated. The process conditions are set as follows: the rotation speed of the screw is 300 revolutions per minute, the rotation speed of the feeder is 40 revolutions per minute, and the temperature of each section of the extruder is 160-200 ℃. And (5) water-passing and granulating the braces.

DSC test is carried out on the dried syndiotactic polypropylene composite material, all experiments are carried out in nitrogen atmosphere, the mass of the sample is 5-8 mg, the heating and cooling rates are 10K/min, and the test temperature ranges from 0 ℃ to 200 ℃. The test results are shown in Table 1.

The dried syndiotactic polypropylene composite material was melted at 200 ℃ and then pressed into a 1 xPhi 50mm wafer, and the light transmittance and haze thereof were measured by an SGW-80 haze meter according to the national standard "determination of light transmittance and haze of transparent plastics-GB/T2410-2008", and the results are shown in Table 1.

Example 7:

weighing the following raw materials in proportion: the syndiotactic polypropylene is 90 parts by mass, the polylactic acid is 5 parts by mass, and the ethylene-vinyl alcohol copolymer is 5 parts by mass. The syndiotactic polypropylene, polylactic acid and ethylene-vinyl alcohol copolymer are premixed, the mixing temperature is 30 ℃, the rotating speed is 500 revolutions per minute, and the mixing is carried out for 3 minutes. Then, the pre-mixed material is added into a parallel double-screw extruder from a feeding machine, and is melted, extruded and granulated. The process conditions are set as follows: the rotating speed of the screw is 250 revolutions per minute, the rotating speed of the feeding machine is 35 revolutions per minute, and the temperature of each section of the extruder is 160-200 ℃. And (5) water-passing and granulating the braces.

DSC test is carried out on the dried syndiotactic polypropylene composite material, all experiments are carried out in nitrogen atmosphere, the mass of the sample is 5-8 mg, the heating and cooling rates are 10K/min, and the test temperature ranges from 0 ℃ to 200 ℃. The test results are shown in Table 1.

The dried syndiotactic polypropylene composite material was melted at 200 ℃ and then pressed into a 1 xPhi 50mm wafer, and the light transmittance and haze thereof were measured by an SGW-80 haze meter according to the national standard "determination of light transmittance and haze of transparent plastics-GB/T2410-2008", and the results are shown in Table 1.

Comparative example 1:

for comparison, syndiotactic polypropylene was weighed to be 100 parts by mass. Syndiotactic polypropylene was added to a high speed mixer and subjected to premixing at 20℃at a rotational speed of 200 rpm for 5 minutes. The syndiotactic polypropylene thus pre-blended was then fed from a feeder into a co-rotating twin-screw extruder and melt extruded into pellets. The process conditions are set as follows: the rotating speed of the screw is 200 revolutions per minute, the rotating speed of the feeding machine is 30 revolutions per minute, and the temperature of each section of the extruder is 16-200 ℃. And (5) water-passing and granulating the braces.

DSC test is carried out on the dried syndiotactic polypropylene, all experiments are carried out in nitrogen atmosphere, the mass of the sample is 5-8 mg, the heating and cooling rates are 10K/min, and the test temperature is 0-200 ℃. The test results are shown in Table 1.

The dried syndiotactic polypropylene was melted at 200℃and pressed into a 1 Xphi 50mm wafer, the light transmittance and haze of which were measured by SGW-80 haze meter according to national standard measurement of light transmittance and haze of transparent plastics-GB/T2410-2008, and the results are shown in Table 1.

Comparative example 2:

for comparison, the following raw materials are weighed according to the following proportion: the syndiotactic polypropylene was 90 parts by mass and the isotactic polypropylene was 10 parts by mass. The syndiotactic polypropylene, polylactic acid and isotactic polypropylene are premixed, and the mixing temperature is 20 ℃, the rotating speed is 200 revolutions per minute, and the mixing time is 5 minutes. Then, the pre-mixed material is added into a parallel double-screw extruder from a feeding machine, and is melted, extruded and granulated. The process conditions are set as follows: the rotating speed of the screw is 200 revolutions per minute, the rotating speed of the feeding machine is 30 revolutions per minute, and the temperature of each section of the extruder is 160-200 ℃. And (5) water-passing and granulating the braces.

DSC test is carried out on the dried syndiotactic polypropylene composite material, all experiments are carried out in nitrogen atmosphere, the mass of the sample is 5-8 mg, the heating and cooling rates are 10K/min, and the test temperature ranges from 0 ℃ to 200 ℃. The test results are shown in Table 1.

The dried syndiotactic polypropylene composite material was melted at 200 ℃ and then pressed into a 1 xPhi 50mm wafer, and the light transmittance and haze thereof were measured by an SGW-80 haze meter according to the national standard "determination of light transmittance and haze of transparent plastics-GB/T2410-2008", and the results are shown in Table 1.

Comparative example 3:

weighing the following raw materials in proportion: the syndiotactic polypropylene is 85 parts by mass and the random copolymer polypropylene is 15 parts by mass. The syndiotactic polypropylene and the random copolymer polypropylene are premixed at a mixing temperature of 20 ℃ and a rotating speed of 200 revolutions per minute for 5 minutes. Then, the pre-mixed material is added into a parallel double-screw extruder from a feeding machine, and is melted, extruded and granulated. The process conditions are set as follows: the rotating speed of the screw is 200 revolutions per minute, the rotating speed of the feeding machine is 25 revolutions per minute, and the temperature of each section of the extruder is 160-200 ℃. And (5) water-passing and granulating the braces.

DSC test is carried out on the dried syndiotactic polypropylene composite material, all experiments are carried out in nitrogen atmosphere, the mass of the sample is 5-8 mg, the heating and cooling rates are 10K/min, and the test temperature ranges from 0 ℃ to 200 ℃. The test results are shown in Table 1.

The dried syndiotactic polypropylene composite material was melted at 200 ℃ and then pressed into a 1 xPhi 50mm wafer, and the light transmittance and haze thereof were measured by an SGW-80 haze meter according to the national standard "determination of light transmittance and haze of transparent plastics-GB/T2410-2008", and the results are shown in Table 1.

TABLE 1 syndiotactic polypropylene and composite materials obtained in examples and comparative examples

As described above, the present invention can be preferably realized.

The embodiments of the present invention are not limited to the above examples, and any other changes, modifications, substitutions, combinations, and simplifications that do not depart from the spirit and principles of the invention should be made and equivalents should be construed as falling within the scope of the invention.

Claims (8)

1. The syndiotactic polypropylene composite material with high crystallization temperature and high crystallization rate is characterized by comprising the following components in parts by weight:

2. the high crystallization temperature and high crystallization rate syndiotactic polypropylene composite material according to claim 1, wherein said syndiotactic polypropylene has a melt flow rate of 1 to 20g/10min (230 ℃,2.16 kg) and a degree of syndiotactic of 80% or more.

3. The high crystallization temperature and high crystallization rate syndiotactic polypropylene composite material as defined in claim 2, wherein said polylactic acid is polylactic acid (D-content < 1%) having a melt flow rate of 5 to 80g/10min (190 ℃ c., 2.16 kg).

4. A syndiotactic polypropylene composite material having a high crystallization temperature and a high crystallization rate according to claim 3, wherein said polyethylene is a high density polyethylene having a melt flow rate of 0.5 to 10g/10min (190 ℃ c., 2.16 kg).

5. The high crystallization temperature and high crystallization rate syndiotactic polypropylene composite material as defined in claim 2, wherein said isotactic polypropylene has a melt flow rate of 2-30 g/10min (230 ℃,2.16 kg) and an isotacticity of 95% or more.

6. The high crystallization temperature and high crystallization rate syndiotactic polypropylene composite material as defined in claim 2, wherein said atactic polypropylene has a melt flow rate of 2 to 20g/10min (230 ℃,2.16 kg) and an ethylene content of 1 to 8%.

7. The high crystallization temperature and high crystallization rate syndiotactic polypropylene composite material according to claim 2, wherein said ethylene vinyl alcohol copolymer has a melt flow rate of 3 to 15g/10min (210 ℃,2.16 kg) and an ethylene content of <50%.

8. A process for the preparation of a syndiotactic polypropylene composite material having a high crystallization temperature and a high crystallization rate as defined in any one of claims 1 to 7, comprising the steps of:

(1) Premixing: adding syndiotactic polypropylene, polylactic acid, polyethylene, isotactic polypropylene, atactic polypropylene and ethylene-vinyl alcohol copolymer into a high-speed mixer in sequence according to the proportion for premixing, wherein the mixing temperature is 20-40 ℃, the rotating speed is 200-500 rpm, and the mixing time is 3-5 minutes, so as to obtain a premix of the syndiotactic polypropylene composite material;

(2) Mixing and granulating by a double-screw extruder: extruding and granulating the premix obtained in the step (1) by using a parallel co-rotating double-screw extruder with the length-diameter ratio of 42:1 and the screw diameter of 35 mm; the rotating speed of the feeding machine is set to be 10-50 rpm, and the rotating speed of the screw is set to be 100-300 rpm; the temperature of each section of the extruder is 160-200 ℃, and the syndiotactic polypropylene composite material is obtained.