Polypropylene resin composition and preparation method thereof

Abstract

The invention relates to the technical field of plastics, and discloses a polypropylene resin composition and a preparation method thereof, the molecular chain orientation degree of the polypropylene resin composition is not higher than-0.2, and the mass crystallinity is not lower than 55%. The polypropylene resin composition has relatively high crystallinity and strong molecular chain orientation degree, and due to the synergistic effect, the polypropylene resin composition has both high modulus and high thermal deformation temperature and can keep relatively good impact resistance. The high melt index can meet the requirement of a rapid thin-wall injection molding process, and energy consumption is reduced.

Description

Technical Field

[0001] The invention relates to the technical field of plastics, and in particular to a polypropylene resin composition and a preparation method thereof. Background Art

[0002] Polypropylene (PP) has excellent physical and mechanical properties, chemical stability and processing performance. Thanks to its safety, non-toxicity, high rigidity, high heat deformation temperature and other advantages, it is widely used in packaging, medical treatment, small household appliances and toys. It is generally believed that the rigidity and heat deformation temperature of polypropylene are closely related to its crystallinity. That is, the higher the crystallinity, the higher the modulus. However, high crystallinity will lead to a decrease in the toughness and impact resistance of polypropylene. The balance and regulation of the rigidity, heat deformation resistance and toughness of polypropylene is the key to broadening the application scenarios of polypropylene and improving its value.

[0003] For polypropylene used in heat-resistant parts of household appliances and in the field of blending and modification, its melt index needs to meet the requirements of the injection molding process, and also has high modulus, high heat deformation temperature and good toughness. CN104592632A discloses the physical blending of polypropylene matrix, high-density polyethylene, polyolefin elastomer and nano-modified particles to prepare a polypropylene composite material with high toughness and high modulus, but its polypropylene matrix only accounts for about 50-60% of the matrix component, there are more fillers, the modification steps are cumbersome, the application cost increases, and it is not suitable for use in scenes with high requirements for gloss, precipitates and appearance. CN107383584A discloses a method for preparing a high-rigidity, high-modulus, thin-walled injection molding polypropylene material using a rigid nucleating agent, but the impact strength and heat deformation temperature of its injection molded products need to be improved. US20110020625A1 discloses improving the rigidity and impact strength of products by controlling the crystal structure of polypropylene-based resins and the degree of orientation of molecular chains, but does not pay attention to the heat deformation temperature of products. The method calculates the long period of the lamellae by a small-angle X-ray scattering instrument and determines the molecular chain orientation by an infrared dichroic ratio method. This method is relatively cumbersome because the small-angle X-ray scattering test time is long and the infrared test is non-in-situ. In addition, the melt index of the polypropylene-based resin in this method is low, which is not conducive to meeting the needs of fast thin-wall injection molding. Summary of the invention

[0004] The purpose of the present invention is to overcome the problem that the impact strength and heat deformation resistance of the polypropylene resin composition in the prior art cannot be taken into account at the same time, and to provide a polypropylene resin composition and a preparation method thereof. The polypropylene resin composition has both high modulus and high heat deformation temperature and can maintain good impact resistance.

[0005] In order to achieve the above object, the present invention provides a polypropylene resin composition in one aspect, wherein the molecular chain orientation degree of the polypropylene resin composition is not higher than -0.2 and the mass crystallinity is not lower than 55%.

[0006] Preferably, the polypropylene resin composition comprises a polypropylene base resin, a nucleating agent, a halogen absorber, an antioxidant and an optional antistatic agent;

[0007] Preferably, based on 100 parts by weight of the polypropylene base resin, the content of the nucleating agent is 0.02-0.3 parts by weight, the content of the halogen absorber is 0.02-0.1 parts by weight, the content of the antioxidant is 0.1-0.5 parts by weight, and the content of the antistatic agent is 0-0.06 parts by weight;

[0008] Preferably, the nucleating agent is one of a composite nano-powder rubber nucleating agent, an organic phosphate nucleating agent, and a substituted aromatic phosphate nucleating agent.

[0009] Preferably, the composite nano-powder rubber nucleating agent comprises nano-powder rubber and an α-crystal nucleating agent.

[0010] Another aspect of the present invention provides a method for preparing the polypropylene resin composition, comprising: mixing a polypropylene base resin, a nucleating agent, a halogen absorber, an antioxidant and an optional antistatic agent, and then performing melt extrusion and granulation.

[0011] The polypropylene resin composition provided by the present invention has high crystallinity and strong molecular chain orientation, and the synergistic effect enables the polypropylene resin composition to have both high modulus and high heat-resistant deformation temperature, and can maintain good impact resistance. The high melt index can meet the requirements of fast thin-wall injection molding process and save energy. At the same time, the preparation process is simple and reliable, the investment cost is low, and it is suitable for plastic products such as home appliance parts, trays, toys, etc., especially suitable for heat-resistant parts and blending modification fields. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 It is a schematic diagram of the size and sample position of an injection molded sample in a wide-angle X-ray diffraction experiment in one embodiment of the present invention. DETAILED DESCRIPTION

[0013] The endpoints and any values ​​of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

[0014] In one aspect, the present invention provides a polypropylene resin composition, wherein the molecular chain orientation degree of the polypropylene resin composition is not higher than -0.2 and the mass crystallinity is not lower than 55%.

[0015] In the current prior art, the improvement of the modulus and heat deformation temperature of polypropylene is often achieved by increasing the crystallinity of polypropylene, but high crystallinity will lead to a decrease in the toughness and impact resistance of polypropylene. Therefore, it is difficult to have both high modulus and high heat deformation temperature while maintaining good impact resistance, and thus cannot meet the application requirements of heat-resistant components of household appliances and blending and modification. The inventors of the present invention have found in their research that by controlling the crystallization behavior and the orientation structure of the molecular chain of the polypropylene resin composition, the flexural modulus and heat deformation temperature of the polypropylene resin composition can be improved, and the room temperature simply supported beam notched impact does not significantly decrease.

[0016] In the present invention, the mass crystallinity of the polypropylene resin composition is not less than 55%, preferably 55-65%. In the present invention, the mass crystallinity of the polypropylene resin composition is measured by differential scanning calorimetry. The mass crystallinity calculation method is the ratio of the enthalpy value when the composition is completely melted to the enthalpy value corresponding to the 100% crystallization of polypropylene. Specifically comprising: using the Diamond differential scanning calorimeter of Perkin-Elmer Company for measurement. Take about 5-6 mg of sample and place it in a crucible. In a nitrogen atmosphere, heat the sample to 200°C at 10°C / min, which is recorded as the first section of the temperature rise melting curve. Keep at 200°C for 5 minutes. Cool down to 25°C at 10°C / min, which is recorded as the first section of the temperature drop crystallization curve. Keep at 25°C for 5 minutes. Heat up to 200°C at 10°C / min again, which is recorded as the second section of the temperature rise melting curve. Compare the area of ​​the melting peak in the second section of the melting curve with the enthalpy value corresponding to the 100% crystallization of polypropylene, and calculate its ratio. The enthalpy value corresponding to 100% crystallization of polypropylene refers to the value disclosed by WR Krigbaum et al. in Journal Polymer Science E, 3, 767 (1965), which is 208 J / g.

[0017] According to the present invention, the molecular chain orientation of the polypropylene resin composition is not higher than -0.2, preferably -0.2 to -0.5. Controlling the molecular chain orientation and mass crystallinity of the polypropylene resin composition within the above preferred range is conducive to further improving the flexural modulus and heat deformation temperature of the polypropylene resin composition, as well as the impact resistance.

[0018] In the present invention, the molecular chain orientation of the polypropylene resin composition is determined by a wide-angle X-ray diffractometer. The Cu Ka ray (wavelength 0.542nm) transmission mode test is adopted, the tube current is 5mA, the tube voltage is 20kV, the resolution is 1024*1024, the distance between the sample and the detector is 98.6mm, and the exposure time is 180s. In the present invention, the test specimen is a standard bending / impact test injection molding specimen. Preferably, the size of the test specimen in GB / T9341-2008 or GB / T 1634-2004 is referred to. The size of the injection molding specimen of the preferred composition is 80±2mm in length, 10.0±0.2mm in width, and 4.0±0.2mm in thickness. The present invention uses a standard test specimen to test the degree of orientation, which can avoid repeated sampling, and the wide-angle X-ray diffraction can perform in-situ testing.

[0019] In the present invention, the wide-angle X-ray diffraction test is the orientation degree at the center of the spline. Because during the injection molding process, due to the shearing effect, a skin-core structure will be formed in the spline, and the molecular chains will also be oriented along the melt flow direction. The orientation degree of the skin structure is greater than that of the core structure. The orientation degree of the core layer is affected by the molecular weight of the polypropylene resin, the nucleating agent, the injection molding conditions, etc., and the orientation degree is closely related to the mechanical properties of the spline. Under the same injection molding conditions, by testing the orientation degree of the core layer of the spline, it represents the orientation degree of the molecular chains in the spline, which can be correlated with the mechanical properties of the spline. In the present invention, preferably, when performing the wide-angle X-ray diffraction test, the incident X-ray and the spline position are such as Figure 1 As shown, MD, TD and ND represent melt flow direction, transverse direction and thickness direction, respectively.

[0020] By integrating the azimuth angle of the characteristic diffraction rings on a certain crystal plane, the degree of orientation S of the molecular chains in this crystal plane can be calculated using the Hermans equation. hkl Calculate as shown in formula (1):

[0021]

[0022] Among them, φ hkl Represents the angle between the stretching direction and the (hkl) crystal plane normal direction.

[0023] Orientation factor cos 2 φ hkl It can be calculated by formula (2):

[0024]

[0025] Among them, I hkl (φ) represents the diffraction intensity along φ. φ can be calculated by the Polanyi formula, as shown in formula (3):

[0026] cosφ hkl = cosθ hkl cosψ (3)

[0027] where θ hkl represents the Bragg diffraction angle, and ψ represents the azimuth angle on the Debye ring.

[0028] In the present invention, the calculation of orientation degree is mainly based on the polypropylene α crystal (040) plane, where θ hkl According to the above calculation method, the degree of orientation S hkl The value of S is between 0 and -0.5. hkl When it is 0, it indicates that the molecular chain is completely randomly oriented. hkl The closer it is to -0.5, the stronger the orientation of the molecular chain is.

[0029] According to the present invention, preferably, at a temperature of 230° C. and a test load of 2.16 Kg, the melt index of the polypropylene resin composition is 1-40 g / 10 min, preferably 4-40 g / 10 min.

[0030] In the present invention, the melt index of the polypropylene resin composition is measured according to GB / T3682-2000 using a 7026 melt indexer from CEAST at 230° C. and a load of 2.16 kg.

[0031] According to the present invention, preferably, the flexural modulus of the polypropylene resin composition is not less than 2000 MPa, preferably 2000-3500 MPa. In the present invention, the flexural modulus is measured according to GB / T 9341-2008.

[0032] According to the present invention, preferably, the heat deformation temperature of the polypropylene resin composition is not less than 115° C., preferably 115-135° C. In the present invention, the heat deformation temperature is measured according to GB / T 1634.2-2004.

[0033] In the present invention, by controlling the crystallization behavior and molecular chain orientation structure of the polypropylene resin composition, the polypropylene resin composition can have a higher flexural modulus and heat deformation temperature, and the room temperature simply supported beam notch impact does not significantly decrease.

[0034] The present invention has no particular limitation on the composition of the polypropylene composition, as long as the crystallization behavior and the orientation structure of the molecular chains of the polypropylene resin composition are satisfied.

[0035] According to some preferred embodiments of the present invention, the polypropylene resin composition comprises a polypropylene base resin, a nucleating agent, a halogen absorber, an antioxidant and an optional antistatic agent.

[0036] Preferably, based on 100 parts by weight of the polypropylene base resin, the content of the nucleating agent is 0.02-0.3 parts by weight, the content of the halogen absorber is 0.02-0.1 parts by weight, the content of the antioxidant is 0.1-0.5 parts by weight, and the content of the antistatic agent is 0-0.06 parts by weight. Further preferably, based on 100 parts by weight of the polypropylene base resin, the content of the nucleating agent is 0.05-0.3 parts by weight, the content of the halogen absorber is 0.04-0.08 parts by weight, the content of the antioxidant is 0.15-0.35 parts by weight, and the content of the antistatic agent is 0.02-0.05 parts by weight.

[0037] In the present invention, the polypropylene base resin has a wide range of choices, and can be homopolypropylene or copolymer polypropylene, or a mixture of homopolypropylene and copolymer polypropylene. Preferably, the polypropylene resin is homopolypropylene.

[0038] Preferably, the melt index of the polypropylene base resin measured at a temperature of 230° C. and a test load of 2.16 kg is 1-40 g / 10 min, preferably 4-40 g / 10 min. The method for measuring the melt index is the same as above and will not be repeated here.

[0039] Preferably, the isotactic index of the polypropylene base resin is greater than 95%, preferably greater than 97%. A high isotactic index of polypropylene is more conducive to improving the crystallinity of polypropylene. The isotactic index is the isotacticity, and its meaning and test method are well known to those skilled in the art.

[0040] The present invention has no particular limitation on the source of the polypropylene base resin, which can be purchased from a commercial source or prepared by a conventional preparation method in the art, and which satisfies the above-mentioned melt index and isotactic index. For example, it can be prepared by a ring tube, multi-zone, gas phase, and other polymerization processes.

[0041] In the present invention, the nucleating agent, halogen absorber, antioxidant and antistatic agent can be any conventional compounding auxiliary agent that can be used for polypropylene resin composition in the art, so as to meet the crystallization behavior and molecular chain orientation structure of the polypropylene resin composition.

[0042] According to some preferred embodiments of the present invention, the nucleating agent is a polypropylene rigidification nucleating agent, preferably at least one of a sorbitol nucleating agent, an organic carboxylate nucleating agent, an organic phosphate nucleating agent, a substituted aryl phosphate ester nucleating agent, and a composite nano powder rubber nucleating agent, preferably a composite nano powder rubber nucleating agent, an organic phosphate nucleating agent, and a substituted aryl phosphate ester nucleating agent. The inventors have found that the addition of such preferred nucleating agents can further improve the crystallization rate and crystallinity of polypropylene resin on the one hand; on the other hand, it can help the orientation of the molecular chain of the polypropylene composition injection molded product along the melt flow direction. The increase in crystallization rate is conducive to shortening the injection molding time, improving the efficiency of injection molding processing, and saving energy consumption. The simultaneous increase in crystallinity and orientation gives the product a high modulus and a high heat deformation temperature while maintaining a certain toughness.

[0043] The present invention has no particular limitation on the source of the nucleating agent, which can be purchased from a commercial source or prepared by a method known in the art. For example, the composite nano powder rubber nucleating agent can be commercial nucleating agents VP101B, VP101E, etc. purchased from Sinopec (Beijing) Chemical Research Institute Co., Ltd., and the organic phosphate nucleating agent can be commercial product RY2007 purchased from Shanghai Qirun New Materials Co., Ltd. The organic carboxylate nucleating agent can be commercial product Hyperform HPN-68L purchased from Milliken.

[0044] The present invention has no particular limitation on the composition of the composite nano-powder rubber nucleating agent. Preferably, the composite nano-powder rubber nucleating agent comprises nano-powder rubber and an α-crystal nucleating agent.

[0045] Preferably, based on the total weight of the composite nano-powder rubber nucleating agent, the content of the nano-powder rubber is 10-99% by weight, preferably 20-90% by weight; the content of the α-crystal nucleating agent is 1-90% by weight, preferably 10-80% by weight.

[0046] In the present invention, the nano powder rubber may be selected from vulcanized powder rubber and / or non-vulcanized powder rubber.

[0047] According to some preferred embodiments of the present invention, the vulcanized powdered rubber is selected from at least one of vulcanized natural rubber, vulcanized styrene-butadiene rubber, vulcanized nitrile rubber, vulcanized chloroprene rubber, vulcanized polybutadiene rubber, vulcanized polyacrylate rubber, vulcanized styrene-butadiene rubber, vulcanized isoprene rubber, vulcanized ethylene-propylene rubber and vulcanized polyurethane rubber, further preferably vulcanized styrene-butadiene rubber, and more preferably vulcanized carboxylated styrene-butadiene rubber.

[0048] In a further preferred embodiment, the gel content in the vulcanized powder rubber is preferably 60% by weight or more. In the present invention, the gel content refers to the ratio of the weight of the cross-linked vulcanized rubber to the total weight of the vulcanized powder rubber.

[0049] Preferably, the particle diameter of the vulcanized powdered rubber is 30-1500 nm, more preferably 50-100 nm.

[0050] The present invention has no particular requirements for the source of the vulcanized powder rubber, which can be purchased from a commercial source or prepared by any method known in the art. Preferably, the preparation method of the vulcanized powder rubber can include adding or not adding a crosslinking aid to rubber latex, then irradiating and then drying to obtain the vulcanized powder rubber. Specifically, the method disclosed in CN1402752A can be referred to.

[0051] According to other preferred embodiments of the present invention, the non-vulcanized powder rubber is preferably selected from at least one of cross-linked styrene butadiene powder rubber, cross-linked polybutadiene powder rubber, cross-linked chloroprene powder rubber and cross-linked acrylate powder rubber, preferably cross-linked styrene butadiene powder rubber, and more preferably cross-linked carboxy styrene butadiene powder rubber.

[0052] Preferably, the gel content in the non-vulcanized powder rubber is more than 85% by weight, and the particle diameter is preferably 50-300nm. The present invention has no special requirements for the source of the non-vulcanized powder rubber, which can be purchased from a market or prepared by any method known in the art. Preferably, the preparation method of the non-vulcanized powder rubber can include: using a cross-linked rubber latex as a raw material and obtaining it after drying. Specifically, it can be carried out with reference to the method disclosed in CN1353131A.

[0053] According to the present invention, the type of the α-crystal nucleating agent can be a conventional choice in the art. Preferably, the α-crystal nucleating agent is an aromatic phosphate nucleating agent, preferably selected from 2,2'-methylene-bis(4,6-di-tert-butylphenyl) sodium phosphate, 2,2'-ethylidene-bis(4,6-di-tert-butylphenyl) sodium phosphate, 2,2'-methylene-bis(4,6-di-tert-butylphenyl) lithium phosphate, 2,2'-ethylidene-bis(4-isopropyl-6-di-tert-butylphenyl) sodium phosphate, 2,2'-methylene-bis(4-methyl-6-di-tert-butylphenyl) lithium phosphate, 2,2'-methylene-bis(4-ethyl-6-di-tert-butylphenyl) lithium phosphate, bis[2,2'-thiobis(4- 6-di-tert-butylphenyl) phosphate], bis[2,2'-thiobis(4-ethyl-6-di-tert-butylphenyl) phosphate], bis[2,2'-thiobis(4,6-di-tert-butylphenyl) phosphate], bis[2,2'-thiobis(4,6-di-tert-butylphenyl) phosphate], magnesium bis[2,2'-thiobis(4,6-di-tert-butylphenyl) phosphate], magnesium bis[2,2'-thiobis(4,6-di-tert-octylphenyl) phosphate], sodium 2,2'-butylidene-bis(4,6-dimethylphenyl) phosphate, sodium 2,2'-tert-octylmethylene-bis(4,6-di-tert-butylphenyl) phosphate, sodium 2,2'-tert-octylmethylene-bis(4,6-di-tert-butylphenyl) phosphate, bis[2,2'-methylene-bis(4,6-di-tert-butylphenyl) phosphate Calcium], bis[2,2'-methylene-bis(4,6-di-tert-butylphenyl) magnesium phosphate], bis[2,2'-methylene-bis(4,6-di-tert-butylphenyl) barium phosphate], 2,2'-methylene-bis(4-methyl-6-tert-butylphenyl) sodium phosphate, 2,2'-methylene-bis(4-ethyl-6-tert-butylphenyl) sodium phosphate, bis[4,4'-dimethyl-6,6'-di-tert-butyl-2,2'-biphenyl) calcium phosphate], 2,2'-ethylidene-bis(4-m-butyl-6-tert-butylphenyl) sodium phosphate, 2,2'-methylene-bis(4,6-dimethylphenyl) sodium phosphate, 2,2'-methylene-bis(4,6-diethylphenyl) sodium phosphate, 2,2' -Ethylene-bis(4,6-di-tert-butylphenyl)potassium phosphate, bis[2,2'-ethylidene-bis(4,6-di-tert-butylphenyl)calcium phosphate], bis[2,2'-ethylidene-bis(4,6-di-tert-butylphenyl)magnesium phosphate], bis[2,2'-ethylidene-bis(4,6-di-tert-butylphenyl)barium phosphate], hydroxy-bis[2,2'-ethylidene-bis(4,6-di-tert-butylphenyl)aluminum phosphate], tris-bis[2,2'-ethylidene-bis(4,6-di-tert-butylphenyl)aluminum phosphate], hydroxy-bis[2,4,8,10-tetrakis(1,1'-dimethylethyl)-6-hydroxy-12H-dibenzo[d,g]dioxaphosphat-6-oxo]aluminum.Preferably, the aromatic phosphate nucleating agent is preferably at least one of sodium 2,2'-methylene-bis(4,6-di-tert-butylphenyl) phosphate, hydroxy-bis[2,2'-ethylidene-bis(4,6-di-tert-butylphenyl)aluminum phosphate] and hydroxy-bis[2,4,8,10-tetra(1,1'-dimethylethyl)-6-hydroxy-12H-dibenzo[d,g]dioxaphosphocene-6-oxide]aluminum and sodium 2,4,8,10-tetra-tert-butyl-12H-dibenzo[d,g][1,3,2]dioxaphosphocene-6-oxide 6-oxide.

[0054] The use of the above preferred nucleating agent is beneficial to improving the crystallization rate and crystallinity of the polypropylene resin, improving the orientation of the molecular chain, and is beneficial to further shortening the injection molding time, improving the injection molding processing efficiency, and saving energy consumption.

[0055] According to some particularly preferred embodiments of the present invention, the nucleating agent is a composite nano-powder rubber nucleating agent including nano-powder rubber and an α-crystalline nucleating agent, wherein the nano-powder rubber is selected from vulcanized carboxylated styrene-butadiene rubber and / or cross-linked carboxylated styrene-butadiene rubber powder, and the α-crystalline nucleating agent is selected from at least one of 2,2'-methylene-bis(4,6-di-tert-butylphenyl) sodium phosphate, hydroxy-bis[2,2'-ethylidene-bis(4,6-di-tert-butylphenyl) aluminum phosphate] and hydroxy-bis[2,4,8,10-tetra(1,1'-dimethylethyl)-6-hydroxy-12H-dibenzo[d,g]dioxaphosphooctane-6-oxy]aluminum and sodium 2,4,8,10-tetra-tert-butyl-12H-dibenzo[d,g][1,3,2]dioxaphosphooctane-6-acid salt 6-oxide.

[0056] The present invention has no particular limitation on the type of the halogen absorbent, and any halogen absorbent in the art that can be used to eliminate halogens and residual catalysts in resins can be applied to the present invention, such as calcium stearate and / or hydrated talc.

[0057] In the present invention, the antioxidant can be a conventional choice in the art, for example, it can be a hindered phenol antioxidant or a phosphite antioxidant, or an antioxidant formed by compounding a hindered phenol antioxidant and a phosphite antioxidant in any proportion, the phosphite antioxidant can be, for example, tris[2,4-di-tert-butylphenyl]phosphite, and the hindered phenol antioxidant can be, for example, pentaerythritol tetrakis[b-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate. Preferably, the mass ratio of the hindered phenol antioxidant to the phosphite antioxidant is 1:10-10:1, for example, it can be 7:3, 8:2, 1:1, 3:7, 2:8, etc., or any range between the two.

[0058] Those skilled in the art may add or not add an antistatic agent to the polypropylene resin composition according to actual needs. The present invention has no special requirements for the specific type of the antistatic agent. Preferably, the antistatic agent is an ester antistatic agent, more preferably a glyceryl monostearate antistatic agent.

[0059] Another aspect of the present invention provides a method for preparing the polypropylene resin composition, comprising: mixing a polypropylene resin, a nucleating agent, a halogen absorber, an antioxidant and an optional antistatic agent, and then performing melt extrusion and granulation.

[0060] The polypropylene resin, nucleating agent, halogen absorber, antioxidant and antistatic agent are the same as defined above and will not be described in detail here.

[0061] In the present invention, there is no particular requirement for the specific method and conditions of the mixing, as long as the components including the polypropylene resin, the nucleating agent, the halogen absorber, the antioxidant and the optional antistatic agent can be fully mixed and uniform. For example, the mixing can be carried out in a high-speed mixer. The mixing process can be carried out continuously or intermittently.

[0062] According to the present invention, the melt extrusion granulation can be carried out on conventional equipment in the art. Preferably, the preparation method preferably comprises: mixing a polypropylene resin, a nucleating agent, a halogen absorber, an antioxidant and an optional antistatic agent, and then melt-extruding on a twin-screw extruder, and then granulating through a pelletizer to obtain the polypropylene resin composition.

[0063] According to the present invention, the mixed material is placed in a twin-screw extruder for melt extrusion, and the melt extrusion can be performed under conventional operating conditions in the art. Preferably, the screw speed is set to 220-280 r / min and the processing temperature is 210-230°C.

[0064] Preferably, the extruded strips obtained by the twin-screw extruder are cooled and dried before the granulation is performed. The present invention has no special requirements for the conditions of the cooling and drying method, and the method can be performed in a conventional manner in the art.

[0065] The present invention will be described in detail below through examples.

[0066] The testing methods of the parameters involved in the following examples and comparative examples are as follows:

[0067] (1) Melt index (MFR, unit: g / 10 min): measured according to GB / T3682-2000 using a CEAST 7026 melt indexer at 230°C and a load of 2.16 kg.

[0068] (2) Tensile modulus (unit: MPa): The prepared polymer was pelletized by screw extruder and injection molded to obtain specimens. The injection molded specimens were measured according to ASTM D638.

[0069] (3) Flexural modulus (unit: MPa): The prepared polymer was granulated by screw extruder and injection molded to obtain specimens, which were measured in accordance with GB / T 9341-2008.

[0070] (4) Simply supported beam notched impact strength (unit: kJ / m 2 ): The prepared polymer was granulated by screw and injection molded to obtain specimens, which were measured at 23°C according to GB / T 1043.1-2008.

[0071] (5) Heat deformation temperature (unit: °C): The prepared polymer was granulated by screw extruder and injection molded into specimens, which was measured according to GB / T1634.2-2004.

[0072] (6) Orientation calculation: The orientation of the sample was measured using a D8 DISCOVER wide-angle X-ray diffractometer from Bruker, Germany. The Cu Ka ray (wavelength 0.542 nm) transmission mode test was used, with a tube current of 5 mA, a tube voltage of 20 kV, a resolution of 1024*1024, a distance between the sample and the detector of 98.6 mm, and an exposure time of 180 s. The incident X-ray and the spline position are as follows: Figure 1 shown.

[0073] (7) Mass crystallinity (unit %): Determined using a Perkin-Elmer Diamond differential scanning calorimeter. Take about 5-6 mg of the sample and place it in a crucible. In a nitrogen atmosphere, heat the sample to 200°C at a rate of 10°C / min, which is recorded as the first stage of the temperature rise melting curve. Keep at 200°C for 5 minutes. Cool down to 25°C at a rate of 10°C / min, which is recorded as the first stage of the temperature drop crystallization curve. Keep at 25°C for 5 minutes. Heat up to 200°C at a rate of 10°C / min, which is recorded as the second stage of the temperature rise melting curve. Compare the area of ​​the melting peak in the second stage melting curve with the thermal enthalpy value corresponding to 100% crystallization of polypropylene, and calculate their ratio. The thermal enthalpy value corresponding to 100% crystallization of polypropylene is 208 J / g.

[0074] (8) Melting temperature (T m ) and crystallization temperature (T c ): The test procedure is the same as the mass crystallinity. The melting temperature is the peak point of the second melting curve, and the crystallization temperature is the peak point of the first crystallization curve.

[0075] In the following examples and comparative examples,

[0076] The polypropylene base resins were all produced on a 25 kg / h loop polypropylene pilot plant. The melt index and all-through stereo index of each polypropylene base resin are shown in Table 1.

[0077] VP101B is a composite nano-powder rubber nucleating agent purchased from Sinopec (Beijing) Chemical Research Institute Co., Ltd., with the trade name VP101B. VP101B contains 56wt% cross-linked styrene-butadiene powder rubber, 20wt% α-crystalline nucleating agent (sodium 2,4,8,10-tetra-tert-butyl-12H-dibenzo[d,g][1,3,2]dioxaphosphooctadiene-6-acid salt 6-oxide), and 24wt% sodium benzoate;

[0078] VP101E is a composite nano-powder rubber nucleating agent purchased from Sinopec (Beijing) Chemical Research Institute Co., Ltd., including cross-linked styrene-butadiene rubber powder and α-crystal nucleating agent ((1R,2S)-rel-1,2-cyclohexanedicarboxylic acid calcium salt (1:1) type);

[0079] RY2007 is an organic phosphate nucleating agent purchased from Shanghai Qirun New Materials Co., Ltd.;

[0080] HPN-68L is an organic carboxylate nucleating agent purchased from Milliken Company under the trade name Hyperform HPN-68L;

[0081] The main antioxidant was antioxidant 1010, the chemical name of which was pentaerythritol tetrakis[b-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, which was purchased commercially;

[0082] The auxiliary antioxidant was antioxidant 168, chemically named tris[2,4-di-tert-butylphenyl]phosphite, commercially available;

[0083] The halogen absorber was calcium stearate, commercially available;

[0084] The antistatic agent is commercially available monostearate.

[0085] Examples 1-6 and Comparative Examples 1-5

[0086] (1) According to the composition formulas provided in Table 1 and Table 2, the raw materials were weighed and then added into a high-speed mixer in sequence to mix the materials uniformly.

[0087] (2) The uniformly mixed premix is ​​placed in a twin-screw extruder for melt blending. The screw speed of the twin-screw extruder is set to 260 r / min and the heating temperature is set to 220° C.

[0088] (3) The blend extruded strips are cooled and dried and then pelletized in a pelletizer to obtain the high modulus and high heat-resistant deformation polypropylene resin composition pellets.

[0089] Table 1 Component distribution ratio of the embodiment (parts by weight)

[0090]

[0091]

[0092] Table 2 Component distribution ratio of comparative example (parts by weight)

[0093]

[0094]

[0095] The polypropylene resin compositions obtained in the above examples and comparative examples were tested for physical properties, and the results are shown in Tables 3 and 4.

[0096] Table 3

[0097]

[0098] Table 4

[0099]

[0100]

[0101] It can be seen from the results of Tables 1-4 that by controlling the crystallization behavior of the polypropylene resin composition and the orientation structure of the molecular chain, the flexural modulus and heat deformation temperature of the polypropylene resin composition can be improved, and the room temperature simply supported beam notch impact does not significantly decrease. Preferably, by adding the auxiliary agent system of the present invention to the isotactic polypropylene resin with a high isotactic index, the crystallization temperature and crystallinity of the polypropylene composition can be significantly improved. In addition, the orientation degree of the molecular chain in the injection molded part along the melt flow direction is greatly increased, thereby making the injection molded part of the polypropylene composition of the present invention have a high flexural modulus and a high heat deformation temperature.

[0102] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims

1. A polypropylene resin composition, characterized in that The molecular chain orientation degree of the polypropylene resin composition is not higher than -0.2, and the mass crystallinity is not lower than 55%.

2. The polypropylene resin composition according to claim 1, wherein The molecular chain orientation degree of the polypropylene resin composition is -0.2 to -0.5; Preferably, the mass crystallinity of the polypropylene resin composition is 55-65%.

3. The polypropylene resin composition according to claim 1 or 2, wherein At a temperature of 230° C. and a test load of 2.16 Kg, the melt index of the polypropylene resin composition is 1-40 g / 10 min, preferably 4-40 g / 10 min.

4. The polypropylene resin composition according to any one of claims 1 to 3, wherein The flexural modulus of the polypropylene resin composition is not less than 2000 MPa, preferably 2000-3500 MPa; and / or, The heat deformation temperature of the polypropylene resin composition is not less than 115°C, preferably 115-135°C.

5. The polypropylene resin composition according to any one of claims 1 to 4, wherein The polypropylene resin composition comprises a polypropylene base resin, a nucleating agent, a halogen absorber, an antioxidant and an optional antistatic agent; Preferably, based on 100 parts by weight of the polypropylene base resin, the content of the nucleating agent is 0.02-0.3 parts by weight, the content of the halogen absorber is 0.02-0.1 parts by weight, the content of the antioxidant is 0.1-0.5 parts by weight, and the content of the antistatic agent is 0-0.06 parts by weight.

6. The polypropylene resin composition according to claim 5, wherein The polypropylene base resin is homopolypropylene and / or copolymer polypropylene, preferably homopolypropylene; Preferably, the melt index of the polypropylene base resin measured at a temperature of 230° C. and a test load of 2.16 Kg is 1-40 g / 10 min, preferably 4-40 g / 10 min; Preferably, the isotactic index of the polypropylene base resin is greater than 95%, preferably greater than 97%.

7. The polypropylene resin composition according to claim 5 or 6, wherein The nucleating agent is a polypropylene reinforced nucleating agent, preferably at least one of a sorbitol nucleating agent, an organic carboxylate nucleating agent, an organic phosphate nucleating agent, a substituted aryl phosphate ester nucleating agent, and a composite nano powder rubber nucleating agent, preferably at least one of a composite nano powder rubber nucleating agent, an organic phosphate nucleating agent, and a substituted aryl phosphate ester nucleating agent; Preferably, the composite nano-powder rubber nucleating agent comprises nano-powder rubber and α-crystal nucleating agent; Preferably, based on the total weight of the composite nano-powder rubber nucleating agent, the content of the nano-powder rubber is 10-99% by weight, preferably 20-90% by weight; the content of the α-crystal nucleating agent is 1-90% by weight, preferably 10-80% by weight.

8. The polypropylene resin composition according to claim 7, wherein The nano powder rubber is selected from vulcanized powder rubber and / or non-vulcanized powder rubber; the vulcanized powder rubber is preferably selected from at least one of vulcanized natural rubber, vulcanized styrene butadiene rubber, vulcanized nitrile rubber, vulcanized chloroprene rubber, vulcanized polybutadiene rubber, vulcanized polyacrylate rubber, vulcanized styrene butadiene rubber, vulcanized isoprene rubber, vulcanized ethylene propylene rubber and vulcanized polyurethane rubber; the non-vulcanized powder rubber is preferably selected from at least one of cross-linked styrene butadiene powder rubber, cross-linked polybutadiene powder rubber, cross-linked chloroprene powder rubber and cross-linked acrylate powder rubber; Preferably, the α-crystalline nucleating agent is an aromatic phosphate nucleating agent, preferably selected from 2,2'-methylene-bis(4,6-di-tert-butylphenyl) sodium phosphate, 2,2'-ethylidene-bis(4,6-di-tert-butylphenyl) sodium phosphate, 2,2'-methylene-bis(4,6-di-tert-butylphenyl) lithium phosphate, 2,2'-ethylidene-bis(4-isopropyl-6-di-tert-butylphenyl) sodium phosphate, 2,2'-methylene-bis(4-methyl-6-di-tert-butylphenyl) lithium phosphate, 2,2'-methylene-bis(4-ethyl-6-di-tert-butylphenyl) lithium phosphate, bis[2,2'-thiobis(4-methyl-6-di-tert-butylphenyl) calcium phosphate], bis[2,2'-thiobis(4-ethyl-6-di-tert-butylphenyl) calcium phosphate] tert-butylphenyl) calcium phosphate], bis[2,2'-thiobis(4,6-di-tert-butylphenyl) calcium phosphate], bis[2,2'-thiobis(4,6-di-tert-butylphenyl) magnesium phosphate], bis[2,2'-thiobis(4,6-di-tert-butylphenyl) magnesium phosphate], bis[2,2'-thiobis(4,6-di-tert-octylphenyl) magnesium phosphate], 2,2'-butylidene-bis(4,6-dimethylphenyl) sodium phosphate, 2,2'-tert-octylmethylene-bis(4,6-dimethylphenyl) sodium phosphate, 2,2'-tert-octylmethylene-bis(4,6-di-tert-butylphenyl) sodium phosphate, bis[2,2'-methylene-bis(4,6-di-tert-butylphenyl) calcium phosphate], bis[2,2'-methylene-bis(4,6-di-tert-butylphenyl) magnesium phosphate], bis[2,2'-methylene -bis(4,6-di-tert-butylphenyl) phosphate barium], 2,2'-methylene-bis(4-methyl-6-tert-butylphenyl) phosphate sodium, 2,2'-methylene-bis(4-ethyl-6-tert-butylphenyl) phosphate sodium, bis[4,4'-dimethyl-6,6'-di-tert-butyl-2,2'-biphenyl) phosphate calcium], 2,2'-ethylidene-bis(4-m-butyl-6-tert-butylphenyl) phosphate sodium, 2,2'-methylene-bis(4,6-dimethylphenyl) phosphate sodium, 2,2'-methylene-bis(4,6-diethylphenyl) phosphate sodium, 2,2'-ethylidene-bis(4,6-di-tert-butylphenyl) phosphate potassium, bis[2,2'-ethylidene-bis(4,6-di-tert-butylphenyl) phosphate At least one of bis[2,2'-ethylidene-bis(4,6-di-tert-butylphenyl)phosphate], bis[2,2'-ethylidene-bis(4,6-di-tert-butylphenyl)phosphate], bis[2,2'-ethylidene-bis(4,6-di-tert-butylphenyl)phosphate], hydroxy-bis[2,2'-ethylidene-bis(4,6-di-tert-butylphenyl)aluminum phosphate], tris[2,2'-ethylidene-bis(4,6-di-tert-butylphenyl)phosphate], hydroxy-bis[2,4,8,10-tetra(1,1'-dimethylethyl)-6-hydroxy-12H-dibenzo[d,g]dioxaphosphocene-6-oxide]aluminum, and sodium 2,4,8,10-tetra-tert-butyl-12H-dibenzo[d,g][1,3,2]dioxaphosphocene-6-oxide 6-oxide.

9. The polypropylene resin composition according to any one of claims 5 to 8, wherein The halogen absorber is calcium stearate and / or hydrated talc; and / or, The antioxidant is a hindered phenol antioxidant and / or a phosphite antioxidant; and / or, The antistatic agent is an ester antistatic agent, preferably a glyceryl monostearate antistatic agent.

10. A method for preparing a polypropylene resin composition according to any one of claims 1 to 9, comprising: The polypropylene base resin, the nucleating agent, the halogen absorber, the antioxidant and the optional antistatic agent are mixed, and then melt-extruded and pelletized; Preferably, the melt extrusion is carried out on a twin-screw extruder, the screw speed is set to 220-280 r / min, and the processing temperature is 210-230°C.

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