CN115232353A - A kind of low-odor and scratch-resistant polypropylene composition, foamed beads and preparation method thereof, and polypropylene foamed bead molded body - Google Patents

Abstract

The invention relates to a low-odor scratch-resistant polypropylene composition, a polypropylene expanded bead, a preparation method thereof and a polypropylene expanded bead molded body in the field of expanded polypropylene. The low-odor scratch-resistant polypropylene composition comprises the following blended components in parts by weight: 100 parts of polypropylene base resin, 1-15 parts of hydrophobic fumed silica, 1-20 parts of polypropylene graft polymer and 0.04-1.8 parts of aliphatic siloxane, wherein the polypropylene base resin is polypropylene random copolymer and/or propylene, ethylene and butylene terpolymer. The odor of the polypropylene resin composition can be remarkably reduced and can reach below 3.5 grade, the scratch resistance of a foaming forming body is greatly improved, the impact resistance is improved, meanwhile, the rigidity is increased, the operation process is simple and reliable, the investment cost is low, and the polypropylene resin composition is suitable for popularization and application.

Description

A low-odor and scratch-resistant polypropylene composition, expanded beads and preparation method thereof, and polypropylene olefin expanded bead molding

technical field

The invention relates to the field of foamed polypropylene, and more particularly, to a low-odor and scratch-resistant polypropylene composition, polypropylene foamed beads and a preparation method thereof, and a polypropylene foamed bead molded body.

Background technique

Compared with traditional polystyrene expanded beads (EPS), polypropylene expanded beads (EPP) have the characteristics of stiffness, resilience, peeling resistance and good thermal stability. pieces. In recent years, the demand for EPP has grown, and it is widely used in automotive interiors, packaging materials, children's entertainment equipment and other impact energy absorption fields. Due to the residual monomers in the polypropylene polymerization process, the volatile organic compound (VOC) substances produced by thermal decomposition during processing and granulation seriously affect the application of EPP in fields with high requirements on odor and health. With the emergence of national mandatory standards for air quality in transportation vehicles, the odor requirements for lightweight materials have become very strict. Correspondingly, under the premise of similar basic physical properties, EPP manufacturers are more willing to use products with lower odor. Therefore, low-odor or odor-free polypropylene products are more favored by the high-end market. The polypropylene produced by the Innovene gas phase unit as expanded beads has a higher modulus and the comonomer content is easy to adjust, but the VOC level of the gas phase unit has been higher. The odor is mainly caused by the volatilization of small molecular hydrocarbons, which are mainly generated in the following ways: one is polymerization in the reactor to generate catalyst residues and short-chain alkanes, and the other is degradation in the extrusion granulation unit; in addition, Residual catalysts in the product and additives added will also affect the odor to a certain extent. Therefore, during the molding process, under the action of high temperature and strong shearing, several types of substances react or volatilize, and aldehydes and ketones will be released in the product, which will produce peculiar smell. The more oligomers contained in the polyolefin, the easier it is to become VOCs with low molecular weight due to oxidative degradation.

In addition, the popularization of new energy vehicles requires the continuous improvement of the cruising range, and the lightweighting of structural and functional parts is a necessary approach. EPP moldings are widely used in sun visors, tool boxes and other application scenarios. During the whole life cycle of automobile use, scratches are prone to occur and affect the appearance. When the EPP molded body is used in large children's amusement facilities, it also needs to meet a certain scratch resistance and scratch resistance to prolong the service life. Therefore, the development of a low-odor and scratch-resistant polypropylene composition, polypropylene expanded beads and molded bodies is an urgently needed product and technology in the market.

Chinese patent CN112080076A discloses a low odor, low VOC microcellular foamed modified polypropylene material, which is composed of polypropylene resin, elastomer, filler, deodorant, auxiliary masterbatch and foaming agent, which can ensure the material Low odor and low VOC characteristics meet the lightweight requirements of microcellular foamed plastic parts for the whole vehicle. However, the patent does not fully disclose the formula of the deodorant, which is a chemical foaming process. In addition, the patent mainly completes the preparation of low-odor polypropylene foaming materials by adjusting the screw combination and other mechanical devices.

SUMMARY OF THE INVENTION

In order to solve the above problems existing in the prior art, the present invention proposes a low-odor and scratch-resistant polypropylene composition. Specifically, it relates to a low-odor and scratch-resistant polypropylene composition, polypropylene expanded beads and a preparation method thereof, and a polypropylene expanded bead molded body.

A first aspect of the present invention provides a low odor scratch resistant polypropylene composition. The low-odor and scratch-resistant polypropylene composition may comprise the following components blended in parts by weight:

in,

The polypropylene base resin is a random copolymerized polypropylene, and the polypropylene base resin is propylene-butyl random copolymerized polypropylene and/or propylene, ethylene and butene terpolymer.

Specifically, propylene-butylene random copolymerization polypropylene and/or propylene, ethylene and butene terpolymer commonly used in the art can be selected. For example, in the propylene random copolymerized polypropylene, the butene content can be selected but not limited to 2-8 mol%, and the rest can be propylene. In the propylene, ethylene and butene terpolymer, the ethylene content can be selected but not limited to 0.5-3 mol%, the butene content can be selected but not limited to 3-8 mol%, and the rest is propylene.

The melting point of the polypropylene base resin may be 139-145° C.; the melt index MFR of the polypropylene base resin may be 6-9 g/10min (2.16 kg, 230° C.); and the molecular weight distribution Mw/Mn may be 3.5-5.8. The polypropylene base resin can be obtained using the Innovene, Spheripol or Spherizone processes. The polypropylene base resin described in the present application has a low melting point, low pressure and temperature during molding, can reduce energy consumption, and has a high modulus, which can be applied to fields that have certain requirements on mechanical strength.

Preferably,

In some implementations, the low-odor, scratch-resistant polypropylene composition may further comprise a nucleating agent;

With respect to 100 parts by weight of the polypropylene base resin, the amount of the nucleating agent may be 0.02-0.5 part by weight; preferably 0.02-0.2 part by weight;

Preferably, the nucleating agent can be selected from alpha nucleating agents and/or beta nucleating agents;

Wherein the α nucleating agent can be a substituted aryl heterocyclic phosphate; preferably, the substituted aryl heterocyclic phosphate can be selected from bis(p-tert-butylphenyl) sodium phosphate, 2,2'- At least one of sodium methylenebis(4,6-di-tert-butylphenyl)phosphate, 2,2'-methylenebis(4,6-di-tert-butylphenyl)aluminum phosphate; preferably 2 , 2'-methylenebis(4,6-di-tert-butylphenyl)aluminum phosphate;

The β nucleating agent can be selected from at least one of aryl dicarboxylic acid amides, N,N'-dicyclohexyl terephthalamide and calcium cyclohexanedicarboxylate; among them, N,N'- At least one of dicyclohexyl terephthalamide and calcium cyclohexanedicarboxylate.

The aliphatic siloxane can be selected from at least one of the following substances: octa(isobutylsilsesquioxane) (CAS: 221326-46-1), trimethylsilyl cage polysesquioxane Siloxane (CAS: 51777-38-9), dimethylsilyl clathrate silsesquioxane (CAS: 125756-69-6), 1,1,3,3-tetramethyl-1, 3 Bis[3-(Epoxyethylmethoxy)propyl]disiloxane (CAS: 126-80-7), Eicosanmethylnonanesiloxane (CAS: 2652-13-3); preferred At least one of the following substances: octa(isobutylsilsesquioxane) (CAS: 221326-46-1), dimethylsilyl clathrate polysilsesquioxane (CAS: 125756-69- 6), trimethylsilyl cage polysilsesquioxane (CAS: 51777-38-9).

The hydrophobic fumed silica has a BET specific surface area of 30-500 m/g and a particle size of 10-500 nm.

The hydrophobic fumed silica and aliphatic siloxane can also be used as cell nucleating agents for polypropylene expanded beads.

The polypropylene graft polymer can be a polypropylene graft modified by a polar monomer, and the polar monomer can be selected from one of glycidyl methacrylate, maleic anhydride and methyl acrylate, etc. or more, preferably at least one of glycidyl methacrylate and methyl acrylate, more preferably glycidyl methacrylate; preferably, in the graft-modified polypropylene of the polar monomer, The graft ratio of the polar monomer may be 0.5-2 wt%, preferably 0.8-1.2 wt%.

In some more preferred embodiments of the present invention, the polar monomer graft-modified polypropylene is a glycidyl methacrylate graft-modified polypropylene, and the glycidyl methacrylate graft-modified polypropylene is In the polypropylene of high quality, the graft ratio of glycidyl methacrylate is 0.8 to 1.2 wt%.

The polypropylene graft polymer can be prepared by solid phase grafting. The polypropylene graft polymer can also be specifically selected from commercially available products, such as glycidyl methacrylate (GMA) grafted PP, Jiayirong, CMG1801R, with a graft ratio of 0.8-1.2%, and the like.

In a specific implementation, the polypropylene in the polypropylene graft polymer can be selected to be the same type as the polypropylene base resin, that is, it is the same as that used in the polypropylene expanded beads, for example, both of them can be random copolymerized polypropylene .

In some specific implementations of the invention, the low-odor and scratch-resistant polypropylene composition may further comprise an antioxidant;

With respect to 100 parts by weight of the polypropylene base resin, the amount of the antioxidant may be 0.05 to 1 part by weight;

Preferably, the antioxidant can be selected from at least one of hindered phenolic antioxidants, phosphite antioxidants, and sulfur lipid antioxidants; more preferably, the hindered phenolic antioxidants Can be selected from at least one of monophenols, bisphenols and polyphenols; the phosphite antioxidants can be selected from alkyl phosphites and/or aryl phosphites; The oxidant can be selected from at least one of thiolipid antioxidants, thioetherphenol antioxidants, and thiobisphenol antioxidants; more preferably, the antioxidants can be hindered phenolic antioxidants, A mixture of two or more of phosphite antioxidants and sulfur lipid antioxidants.

Specifically, the antioxidant described in the present invention may be hindered phenolic antioxidant 1098, antioxidant 1076, antioxidant 2246, antioxidant CA, antioxidant 168, antioxidant 626 or antioxidant One or both of the 636. The antioxidant may be used in an amount of 0.05-1 part by weight relative to 100 parts by weight of the polypropylene. Preferably, the composition of antioxidant 1098 and antioxidant 168 is in a mass ratio of 10:1 to 1:10. It is preferably 1:1.

In some specific implementations, the low-odor and scratch-resistant polypropylene composition may comprise glycerol monostearoyl ester, and the molecular formula is: C ₂₁ H ₄₂ O ₄ . The substance can be dispersed into polypropylene during processing; in order to advantageously improve the dispersibility of hydrophobic fumed silica and octaisobutylsilsesquioxane in polypropylene base resin, preferably the monoglyceride The addition amount of stearoyl ester may be 0.1-1% by weight of the hydrophobic fumed silica, preferably 0.2-0.8%.

According to the composition of the present invention, preferably, the composition may further contain other adjuvants. The other adjuvants will not adversely affect the properties of polypropylene, including but not limited to at least one of slip agents, antistatic agents, lubricants, plasticizers, and the like. In addition, the dosages of the other auxiliary agents are all conventional choices in the art, which are known to those skilled in the art.

The second purpose of the present invention is to provide the preparation method of the described low-odor and scratch-resistant polypropylene composition, which may include the following steps:

Mix the components including the polypropylene base resin, nucleating agent, hydrophobic fumed silica, polypropylene graft polymer, aliphatic siloxane, antioxidant and other additives, and then melt blending to obtain the polypropylene resin composition.

According to a specific embodiment, the preparation method may include the following steps:

(1) uniformly mixing the components including the nucleating agent, hydrophobic fumed silica, aliphatic siloxane and antioxidant to obtain a mixture;

(2) uniformly mixing the components including the mixture, the polypropylene base resin and the polypropylene graft polymer to obtain a premix;

(3) The premix is melt-blended, extruded and pelletized to obtain the polypropylene resin composition pellets.

According to the present invention, in step (2), the polypropylene base resin is preferably dried polypropylene. The mixing in both steps (1) and (2) is preferably dry mixing.

In order to better remove odor, it is preferable to keep the vacuum degree of the vacuum system of the equipment above -0.05MPa, more preferably above -0.08MPa during the melt blending.

In the preparation method of the present invention, the material melt blending temperature is the blending temperature usually used in polypropylene processing, and should be selected within the range that ensures complete melting of the matrix resin without decomposing it, generally 180°C to 230°C °C, the preferred processing temperature is 190-220 °C; the screw speed of the melt blending equipment is 300-450 rpm; the extrusion temperature can be 180-230 °C.

In the preparation method of the present invention, the mixing equipment of each material can adopt various mixing equipment used in the prior art, such as a mixer, a kneader, etc.; Mixing equipment can be twin-screw extruder, BUSS mixing unit, etc. The dicing method can be either underwater dicing or string dicing.

The third object of the present invention is to provide a polypropylene expanded bead, the polypropylene expanded bead is prepared from the low-odor and scratch-resistant polypropylene composition described in one of the objects of the present invention; preferably, the The density of the polypropylene expanded beads is less than 0.9g/cm ³ , preferably 0.01-0.49g/cm ³ ; the cell density can be 3.3×10 ⁷ ～8.0×10 ⁷ ; the 50% compressive strength can be 0.7-1.2MPa . The polypropylene foamed beads have dense cells, uniform pore size, complete morphology without rupture, and low density.

The silicon dioxide and aliphatic siloxane prepared by the gas phase method have high specific surface area, and the method used as the cell nucleating agent to prepare the foamed beads in the present invention is not only simple and easy to operate, easy to promote industrially, and has good economic and social benefits.

The fourth purpose of the present invention is to provide the preparation method of the described polypropylene expanded beads, which may include the following steps:

After pelletizing and cutting the low-odor and scratch-resistant polypropylene composition, the obtained polypropylene resin particles are expanded.

Preferably, the foaming method is a reaction kettle immersion foaming method.

According to the method for preparing polypropylene expanded beads of the present invention, the granulation can be carried out in various existing ways. For example, the polypropylene composition can be passed through one or more of a twin-screw or single-screw extruder. A die is extruded into a wire and cut to obtain polypropylene particles. An underwater particle cutting system can also be used, and the specific operation process is well known to those skilled in the art. In specific use, a twin-screw extruder and an underwater pelletizing process can be selected, and the length-diameter ratio of the obtained micro-particles can be controlled at 0.9-1.1:1, which is more conducive to foaming.

According to a specific embodiment of the method for preparing polypropylene expanded beads of the present invention, the pelletizing process may include:

(a) adding the above-mentioned low-odor and scratch-resistant polypropylene composition and optional other common auxiliary agents into a high-speed mixer according to a certain proportion, and mixing uniformly;

(b) Extruding the above-mentioned mixture (for example, it can be extruded by a twin-screw extruder), heat-cutting, and then introducing it into water at a temperature of 75°C or lower, preferably 70°C or lower, more preferably 55 to 65°C, and finely dicing each particle. The length/diameter ratio is 0.5 to 2.0, preferably 0.8 to 1.3, more preferably 0.9 to 1.1, and the average weight is 0.1 to 20 mg, preferably 0.2 to 10 mg, and more preferably 1 to 3 mg. The length/diameter ratios stated here are the average of 200 randomly selected particles of the polypropylene composition.

The steps of the granulation method can be adjusted according to the actual situation.

According to the method for preparing polypropylene foamed beads of the present invention, the foaming can also be carried out by various existing methods, for example, the extrusion foaming method can be used, or the reaction kettle immersion foaming method can be used. It is preferably carried out by the reaction kettle immersion foaming method. The foamed beads obtained in this way have a non-crosslinked structure, so that they can be recycled as polypropylene modified materials without causing secondary pollution, which meets the requirements of circular economy. .

According to the method for preparing polypropylene foamed beads according to the present invention, preferably, the foaming is carried out by a reaction kettle immersion foaming method, and more preferably, the reaction kettle immersion foaming method may include the following steps:

(1) In the autoclave, the polypropylene resin particles are uniformly mixed with auxiliary agents such as dispersion medium, surfactant, dispersant and dispersion enhancer;

(2) Tighten the lid of the autoclave first, use the blowing agent to discharge the residual air in the autoclave by the air exhaust method, then continue to feed the blowing agent into the autoclave, start heating and preliminarily adjust the pressure until it is stable, then Stir the autoclave at a stirring speed of 50 to 150 rmp, preferably 90 to 110 rmp, and heat it at a constant speed to a temperature that is 0.1 to 5°C lower than the expansion stability, preferably 0.5 to 1°C lower;

(3) Adjust the pressure in the autoclave to reach the pressure required for foaming, the pressure is 1 to 10 MPa, preferably 3 to 5 MPa, and the temperature is raised to the foaming temperature with an average heating rate of 0.1 ° C/min, and the foaming temperature is higher than the foaming temperature. The melting temperature of the microparticles is 0.1-5°C lower, preferably 0.5-1°C lower, and under the conditions of foaming temperature and pressure, stirring is continued for 0.1-2 hours, preferably 0.25-0.5 hours;

(4) Open the discharge port of the autoclave, so that the material in the autoclave is discharged into the collection tank to obtain polypropylene expanded beads, and carbon dioxide gas is fed while discharging, so that all the particles are completely released. The pressure in the autoclave was maintained near the foaming pressure before foaming and entering the collection tank.

The steps of the foaming method can be adjusted according to the actual situation.

In this article, unless otherwise specified, the pressure refers to gauge pressure.

According to the method for preparing polypropylene expanded beads of the present invention, the dispersion medium may be any existing dispersion medium capable of dispersing polypropylene resin particles therein without dissolving its components, for example, water may be used , at least one of ethylene glycol, glycerol, methanol, ethanol, etc., particularly preferably water. Preferably, with respect to 100 parts by weight of polypropylene resin particles, the amount of the dispersion medium used is 1000-5000 parts by weight, preferably 2500-3500 parts by weight.

According to the method for preparing polypropylene expanded beads of the present invention, the surfactant can be various existing components that can promote the dispersion of polypropylene resin particles in the dispersion medium, for example, can be stearic acid, At least one of sodium dodecylbenzenesulfonate, quaternary ammonium compound, lecithin, amino acid, betaine, fatty acid glyceride, fatty acid sorbitan, polysorbate, etc., particularly preferably sodium dodecylbenzenesulfonate . Preferably, relative to 100 parts by weight of polypropylene resin particles, the amount of the surfactant is 0.001-10 parts by weight, preferably 0.01-5 parts by weight, more preferably 0.1-0.5 parts by weight.

According to the method for preparing polypropylene expanded beads of the present invention, the dispersant may be an organic dispersant or an inorganic dispersant, preferably an inorganic dispersant. The inorganic dispersants may be natural or synthetic clay minerals (eg, kaolin, mica, pyrope, clay, etc.), alumina, titanium dioxide, basic magnesium carbonate, basic zinc carbonate, calcium carbonate, silica , at least one of zinc borate, iron oxide, etc., particularly preferably kaolin. In order to effectively prevent the polypropylene resin particles from being melt-bonded to each other during foaming, preferably, the dispersant is used in an amount of 0.01-20 parts by weight, preferably 0.1-10 parts by weight, relative to 100 parts by weight of the polypropylene resin particles parts, more preferably 0.5 to 5 parts by weight.

According to the method for preparing polypropylene expanded beads of the present invention, the purpose of adding the dispersion enhancer is to improve the dispersion efficiency of the dispersant, that is, to reduce the amount of the dispersant while retaining its function of preventing fusion bonding between particles . The dispersion enhancer can be various existing inorganic compounds that have a solubility of 1 mg in 100 mL of water at 40° C. and provide divalent or trivalent anions or cations. Examples of the dispersion enhancer include, but are not limited to, at least one of magnesium nitride, magnesium nitrate, aluminum phosphate, magnesium sulfate, aluminum nitride, aluminum nitrate, aluminum sulfate, ferric chloride, ferric sulfate, ferric nitrate, and the like, Aluminum sulfate is preferred. In order to obtain polypropylene expanded beads with an apparent density of 100 g/L or more, preferably, the amount of the dispersion enhancer is 0.0001-1 part by weight, preferably 0.01 part by weight, relative to 100 parts by weight of polypropylene composition particles ~0.2 parts by weight.

According to the method for preparing polypropylene expanded beads of the present invention, the foaming agent may be an organic physical foaming agent or an inorganic physical foaming agent. Among them, examples of the organic physical blowing agent include, but are not limited to, aliphatic hydrocarbons such as propane, butane, pentane, hexane and heptane, alicyclic hydrocarbons such as cyclobutane and cyclohexane, and Halogenated hydrocarbons such as at least one of chlorofluoromethane, trifluoromethane, 1,2-difluoroethane, 1,2,2,2-tetrafluoroethane, methyl chloride, ethyl chloride and dichloromethane, etc. kind. Examples of the inorganic-based physical blowing agent include, but are not limited to, at least one of air, nitrogen, carbon dioxide, oxygen, and water. In order to ensure good stability (uniformity) of the apparent density of the obtained polypropylene expanded beads, low cost and environmental friendliness, the blowing agent is preferably a physical blowing agent, such as carbon dioxide and/or nitrogen, particularly preferably carbon dioxide. In addition, the amount of the foaming agent can be determined according to the specific type of the foaming agent, the foaming temperature and the apparent density of the polypropylene expanded beads to be produced. For example, when nitrogen is used as the foaming agent and water is used as the dispersion medium, the pressure in the airtight container (that is, the pressure (gauge pressure) in the upper space in the airtight container) when the foaming device is depressurized is controlled at 1-12MPa ; When using carbon dioxide as the foaming agent, the above gauge pressure is controlled at 1-7MPa. In general, the desired pressure in the headspace within the closed vessel increases as the apparent density of the polypropylene composition particles to be obtained decreases.

The fifth object of the present invention is to provide the low-odor and scratch-resistant polypropylene composition or the application of the polypropylene expanded beads.

The sixth object of the present invention is to provide a polypropylene expanded bead molded body, the polypropylene expanded bead molded body is composed of the polypropylene expanded beads described in the third object of the present invention and/or the polypropylene expanded beads of the present invention The polypropylene foam beads prepared by the preparation method described in the fourth purpose are obtained by molding.

According to the present invention, the molding can be performed in various existing molding machines, and the molding conditions can be selected conventionally in the field. I won't go into details.

Compared with the prior art, the present invention has the following beneficial effects:

1. The polypropylene graft polymer used in the present invention is prepared by a solid-phase grafting method, with low odor and less volatile organic content, without additional odor. The polypropylene graft polymer has good compatibility with polypropylene and fillers, so that silica can be uniformly dispersed in the polypropylene matrix, and it can improve the performance of polypropylene base resin and silica and aliphatic siloxane. At the same time, the large specific surface area structure of fumed silica can also effectively absorb polypropylene odor.

2. The cage structure of fumed silica and aliphatic siloxane used in the present invention has a good synergistic adsorption and barrier effect, and the high specific surface area of silica provides a loading position for aliphatic siloxane and improves dispersibility. At the same time, it can further inhibit the generation of odor in polypropylene, and in addition, uniformly dispersed silicon-containing silica and octaisobutyl silsesquioxane can effectively improve the scratch resistance of polypropylene foamed moldings.

3. The anti-scratch and low odor auxiliary system containing hydrophobic fumed silica and aliphatic siloxane used in this application can also be used as a cell nucleating agent for polypropylene expanded beads.

4. The compounding of the aliphatic siloxane and the antioxidant used in the present invention can effectively improve the dispersion effect of the two in the polypropylene resin, improve the efficiency of the antioxidant, and effectively inhibit the production of the polypropylene composition during the processing. odor.

5. The odor of the polypropylene resin composition of the present invention can be significantly reduced, the odor can reach below grade 3.5, the scratch resistance of the foamed molded body is greatly improved, the impact performance is improved and the rigidity is increased, which is a good solution to the current situation. There are technical deficiencies, and the operation process is simple and reliable, and the input cost is low. It is suitable for the field of polypropylene expanded beads, and can be widely used in vehicle interiors, children's toys and other fields with high requirements for odor and scratch resistance. .

Description of drawings

FIG. 1 is a cross-sectional photograph of the expanded beads described in Example 2. FIG.

FIG. 2 is a cross-sectional photograph of the expanded beads described in Comparative Example 2. FIG.

Detailed ways

The present invention will be specifically described below in conjunction with specific embodiments. It is necessary to point out that the following embodiments are only used to further illustrate the present invention, and should not be construed as limitations on the protection scope of the present invention. Some non-essential improvements and adjustments made by the invention still belong to the protection scope of the present invention.

The endpoints of ranges and any values disclosed herein are not limited to the precise ranges or values, which are to be understood to encompass values proximate to those ranges or values. For ranges of values, the endpoints of each range, the endpoints of each range and the individual point values, and the individual point values can be combined with each other to yield one or more new ranges of values that Ranges should be considered as specifically disclosed herein.

Source of raw materials

The raw materials used in embodiment, comparative example are as follows:

Random copolymer polypropylene B5008M, MFR 8+1g/10min (230℃, 2.16kg), purchased from Sinopec Yanshan Branch;

Random copolymer polypropylene 5608, MFR 8 ± 1g/10min (230℃, 2.16kg), purchased from Sinopec Yanshan Branch;

Random copolymer polypropylene E680E, MFR 8 ± 1.5g/10min (230°C, 2.16kg), purchased from Sinopec Shanghai Petrochemical;

R974，购自赢创公司；比表面积150～190m/g，粒径为10～15nm；Hydrophobic fumed silica

R974, purchased from Evonik; specific surface area 150-190m/g, particle size 10-15nm;

Octaisobutyl silsesquioxane MS0825, purchased from American Hybridplastic Company;

Dimethylsilyl clathrate polysilsesquioxane, purchased from Beijing Bailingwei Technology Co., Ltd.;

Trimethylsilyl clathrate polysilsesquioxane, purchased from Beijing Bailingwei Technology Co., Ltd.;

The polypropylene graft polymer is glycidyl methacrylate (GMA) grafted polypropylene, the model is Jiayirong, CMG1801R, and the grafting rate is 0.8-1.2%;

Calcium cyclohexanedicarboxylate, nucleating agent HPN-20e, purchased from Milliken, USA;

Glycerol monostearoyl ester, purchased from Croda, ATMER129V;

Antioxidant 1098 and Antioxidant 168 were purchased from BASF, Germany.

In the following examples and comparative examples, relevant data are obtained by the following test methods:

(1) Melt index MI: measured according to the method specified in GB/T3682-2000, wherein the test temperature is 230°C and the load is 2.16kg;

(2) Density of polypropylene and composition: measured according to the method specified in GB/T1033.2-2010 and by density gradient column method; the density of expanded polypropylene beads is measured according to ASTMD792;

(3) Surface resistivity of the foamed bead molding: measured according to the method of GB/T1410-2006;

(4) Compressive strength test of the molded body: A sample of 50×50×25 mm was cut out from the expanded bead molded body, and the compressive strength test was performed based on the American ASTM standard D3575-08, using a compression speed of 10 mm/min Carry out a compression test to obtain the compressive strength when the molded body is compressed by 50%;

(5) The cell density is tested according to the following method:

First, use a scanning electron microscope to observe the cross-section of the polypropylene expanded beads, and select a certain area from the obtained electron microscope photos to obtain information such as the area and the number of cells in the region. The cell density of the beads can be obtained by the following formula:

是聚丙烯发泡珠粒的发泡倍率。Where: n is the number of cells in the SEM photo, M is the magnification, A is the area of the selected area on the SEM photo (unit: cm ² ),

is the expansion ratio of polypropylene expanded beads.

(6) The scratch resistance is tested according to PV3952;

(7) The smell is tested according to the standard VDA270 of the German Automobile Industry Association.

Examples 1 to 9

Nucleating agent, aliphatic siloxane, hydrophobic fumed silica and antioxidant (hindered phenol antioxidant 1098: phosphite antioxidant 168=1:1 (weight ratio), the amount of antioxidant All are 0.2 parts by weight (100 parts by weight relative to the base resin consumption), glycerol monostearoyl ester (the consumption is fixed as five thousandths of the weight part consumption of hydrophobic fumed silica) into the high-speed mixer, Stir for 2 minutes at a speed of 300 rpm to fully mix the components to obtain the mixture; then mix the obtained mixture with the random copolymer polypropylene sample and the polypropylene graft polymer uniformly, and then mix The above mixture is extruded and granulated through a BUSS mixing unit (MKD-30, BUSS, Switzerland) in the range of 190 ℃ ~ 220 ℃ under the condition of maintaining a vacuum degree of -0.08MPa. With the LabLine100 microparticle preparation system, the torque is controlled at 65%, the rotating speed is 300rpm, and the polypropylene resin microparticles are obtained by underwater cutting, and the average aspect ratio of the obtained microparticles is 1:1.

First, in an autoclave, 100 parts by weight of polypropylene resin particles were mixed with 3000 parts by weight of dispersion medium (deionized water), 0.3 parts by weight of surfactant (sodium dodecylbenzenesulfonate), and 3 parts by weight of dispersant (kaolin). Parts by weight and 0.2 parts by weight of dispersion enhancer (aluminum sulfate) are added and mixed at one time; secondly, cover the kettle tightly, and use an inert foaming agent ( _CO2 or nitrogen, see Table 3). The residual air is discharged through the exhaust valve and pipeline to remove the air in the reactor; the inert foaming agent is fed into the autoclave, and the pressure is initially adjusted until it is stable; then the dispersion in the autoclave is stirred at a constant speed Heating heats it 0.5-1°C below the expansion temperature. Then, adjust the pressure in the kettle to reach the pressure required for foaming; increase the temperature to the foaming temperature at an average heating rate of 0.1 °C/min, and the foaming temperature is 0.5-1 °C lower than the melting temperature of the particles; at the foaming temperature and pressure Continue stirring for 0.25-0.5 hours under conditions. Finally, the discharge port of the autoclave is opened, so that the materials in the reactor are discharged into the collection tank to obtain polypropylene expanded beads; carbon dioxide gas is fed while discharging, so that all the particles are completely released. The pressure in the autoclave was maintained near the foaming pressure before foaming and entering the collection tank. The obtained expanded bead density was measured by ASTM D792, and the specific data are shown in Table 1.

Comparative Examples 1 to 5

Comparative Example 1

The random copolymer polypropylene B5008M sample was extruded and granulated under the condition of maintaining the vacuum degree of -0.08MPa through the BUSS mixing unit (MKD-30, Switzerland BUSS company) in the range of 190 ℃ ~ 220 ℃, and prepared with LabLine100 microparticles system, the torque is controlled at about 65%, the rotating speed is 300rpm, and the polypropylene resin particles are obtained by underwater pelletizing. The specific method steps of the subsequent foaming process are the same as those in Example 2. The obtained expanded bead density was measured by ASTM D792, and the specific data are shown in Table 1.

Comparative Example 2

Except that no aliphatic siloxane is added, other components and preparation method steps are the same as those of Example 2. The obtained expanded bead density was measured by ASTM D792, and the specific data are shown in Table 1.

Comparative Example 3

Except that hydrophobic fumed silica is not added, other components and preparation method steps are the same as in Example 2. The obtained expanded bead density was measured by ASTM D792, and the specific data are shown in Table 1.

Comparative Example 4

Except that the polypropylene graft polymer is not added, other components and the steps of the preparation method are the same as those of Example 2. The obtained expanded bead density was measured by ASTM D792, and the specific data are shown in Table 1.

Comparative Example 5

Except that polypropylene graft polymer is not added, other components and preparation method steps are the same as those in Example 1. The obtained expanded bead density was measured by ASTM D792, and the specific data are shown in Table 1.

From the data shown in Table 1, it can be seen that the polypropylene foam beads using aliphatic siloxane and hydrophobic fumed silica have lower color difference ΔE (color difference refers to the difference between the scratched part and the original one after scratching). The difference in the color of the pieces, the smaller the better the scratch resistance) and the odor (VDA270).

From the comparison of Comparative Example 4 and Comparative Example 1, it can be seen that without adding polypropylene graft copolymer, the involved polypropylene expanded beads also exhibit relatively low color difference ΔE and odor (VDA270). After adding the polypropylene graft copolymer (see Example 2), the combination and dispersion of silica, siloxane and the polypropylene matrix can be improved, and the color difference and odor can be further reduced.

It can be seen from the comparison between Comparative Example 2 and Example 2 that the scratch resistance is poor when no aliphatic siloxane is added. Addition of aliphatic siloxane can further improve scratch resistance by utilizing its lubricity. At the same time, the aliphatic siloxane has the effect of preventing the rupture of the cell growth, while the comparative example 2 mainly has broken pores, and the closed cell ratio is low, which affects the mechanical properties. The compressive strength of the comparative example 2 decreases by about 10%.

It can be seen from the cross-sectional photos of the foamed beads of Comparative Example 2 and Comparative Example 2 (see Figures 1 and 2) that the foamed beads obtained in Comparative Example 2 have obvious ruptures, while the foamed beads obtained in Example 2 particles, no cracking phenomenon, more uniform cells, and better cell morphology.

The preferred embodiments of the present invention have been described above in detail, however, the present invention is not limited thereto. Within the scope of the technical concept of the present invention, a variety of simple modifications can be made to the technical solutions of the present invention, including the combination of various technical features in any other suitable manner. These simple modifications and combinations should also be regarded as the content disclosed in the present invention. All belong to the protection scope of the present invention.

Claims (13)

1. A low-odor scratch-resistant polypropylene composition comprises the following components in parts by weight:

100 parts by weight of a polypropylene base resin,

1 to 15 parts by weight, preferably 4 to 15 parts by weight,

1 to 20 parts by weight, preferably 4 to 20 parts by weight,

0.04 to 1.8 parts by weight of aliphatic siloxane, preferably 0.1 to 1.5 parts by weight;

the polypropylene base resin is polypropylene random copolymer, and is polypropylene random copolymer and/or propylene, ethylene and butylene terpolymer.

2. The low odor, scratch resistant polypropylene composition of claim 1, wherein:

the melt index MFR of the polypropylene base resin is 6 to 9g/10min.

3. The low odor, scratch resistant polypropylene composition of claim 1, characterized by comprising a nucleating agent;

the nucleating agent is used in an amount of 0.02 to 0.5 parts by weight relative to 100 parts by weight of the polypropylene base resin; preferably 0.02 to 0.2 parts by weight;

preferably, ,

the nucleating agent is selected from at least one of alpha nucleating agent and beta nucleating agent;

the alpha nucleating agent is substituted aryl heterocyclic phosphate; preferably, the substituted aryl heterocyclic phosphate is selected from at least one of sodium bis (p-tert-butylphenyl) phosphate, sodium 2,2 '-methylenebis (4, 6-di-tert-butylphenyl) phosphate, aluminum 2,2' -methylenebis (4, 6-di-tert-butylphenyl) phosphate;

the beta nucleating agent is selected from at least one of aryl dicarboxylic acid amide, N' -dicyclohexyl terephthalamide and calcium cyclohexanedicarboxylate; among them, at least one of N, N' -dicyclohexylterephthalamide and calcium cyclohexanedicarboxylate is preferable.

4. The low odor, scratch resistant polypropylene composition of claim 1, wherein:

the aliphatic siloxane is at least one selected from octa (isobutyl silsesquioxane), trimethylsilyl cage polysilsesquioxane, dimethylsilyl cage polysilsesquioxane, 1, 3-tetramethyl-1, 3 bis [3- (epoxyethylmethoxy) propyl ] disiloxane and eicosyl nonane siloxane; preferably at least one of octa (isobutyl silsesquioxane), dimethylsilyl cage polysilsesquioxane and trimethylsilyl cage polysilsesquioxane.

5. The low odor, scratch resistant polypropylene composition of claim 1, wherein:

the BET specific surface area of the hydrophobic fumed silica is 30-500 m/g, and the particle size is 10-500 nm.

6. The low odor, scratch resistant polypropylene composition of claim 1, characterized by comprising an antioxidant;

the antioxidant is used in an amount of 0.05 to 1 part by weight per 100 parts by weight of the polypropylene base resin;

preferably, the antioxidant is selected from at least one of hindered phenol antioxidants, phosphite antioxidants and thioester antioxidants; more preferably, the hindered phenol antioxidant is selected from at least one of monophenols, bisphenols and polyphenols; the phosphite antioxidant is selected from alkyl phosphite and/or aryl phosphite; the thioester antioxidant is at least one selected from thioester antioxidant, thioether phenol antioxidant and thiobisphenol antioxidant; more preferably, the antioxidant is a mixture of two or more of hindered phenol antioxidants, phosphite antioxidants and thioester antioxidants.

7. The low odor, scratch resistant polypropylene composition according to claim 1, characterized by comprising glycerol monostearate;

the addition amount of the glycerol monostearate is 0.1 to 1 percent of the weight of the hydrophobic fumed silica, and preferably 0.2 to 0.8 percent.

8. The low-odor scratch-resistant polypropylene composition according to any one of claims 1 to 7, wherein:

the polypropylene graft polymer is polypropylene grafted and modified by polar monomers;

the polar monomer is selected from one or more of glycidyl methacrylate, maleic anhydride and methyl acrylate, and is preferably glycidyl methacrylate;

preferably, in the polar monomer graft-modified polypropylene, the grafting ratio of the polar monomer is 0.5 to 2wt%, preferably 0.8 to 1.2wt%.

9. Method for preparing a low-odor scratch-resistant polypropylene composition according to any one of claims 1 to 8, characterized in that it comprises the steps of:

mixing components including the polypropylene base resin, hydrophobic fumed silica, a polypropylene graft polymer and aliphatic siloxane, and then carrying out melt blending to obtain the polypropylene resin composition; preferably, the vacuum degree is kept above-0.05 MPa during the melt blending.

10. A polypropylene expanded bead prepared from the low-odor scratch-resistant polypropylene composition according to any one of claims 1 to 8; preferably, the density of the polypropylene expanded beads is less than 0.9g/cm ³ Preferably 0.01 to 0.49g/cm ³ 。

11. The method for producing polypropylene expanded beads according to claim 10, comprising the steps of:

pelletizing and cutting the low-odor scratch-resistant polypropylene composition as defined in any one of claims 1 to 8, and foaming the resulting polypropylene resin fine particles; preferably, the foaming method is a reaction kettle dipping foaming method.

12. Use of the low-odor scratch-resistant polypropylene composition according to any one of claims 1 to 8 or the polypropylene expanded beads according to claim 10.

13. A molded article of polypropylene expanded beads obtained by molding the polypropylene expanded beads according to claim 10 and/or the polypropylene expanded beads obtained by the method according to claim 11.

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