Whisker masterbatch for polyolefin foamed material and preparation method thereof

Abstract

This invention discloses a method for preparing whisker masterbatch for polyolefin foam materials and the whisker masterbatch itself. The method includes: adding whiskers, lubricants, dispersants, and coupling agents in a set ratio to an air-blast powder activation machine, and activating them under set conditions until fully activated whisker semi-finished products are obtained; introducing the whisker semi-finished products and polyethylene resin into a twin-screw continuous internal mixing extruder with a grinding surface and hot cutting in a set ratio, mixing and extruding, and cutting into particles by grinding surface hot cutting; subjecting the particles extruded from the twin-screw continuous internal mixing extruder to three-stage air cooling and then to vibrating sieve sorting to finally obtain whisker masterbatch for polyolefin foam materials. This invention solves the problems of easy screen clogging when whisker masterbatch is used as a polyolefin foam material in the prior art, as well as the problems of uneven foaming, rapid softening speed, and insufficient cell stiffness in polyolefin foam materials.

Description

Technical Field

[0001] This invention relates to the field of chemical technology, and in particular to whisker masterbatches for polyolefin foaming materials and their preparation methods. Background Technology

[0002] Currently, in the domestic polyolefin foaming material field, such as pearl cotton polyethylene foam and EVA shoe sole foam, problems such as uneven foaming, rapid softening, and insufficient cell stiffness are widely present due to the influence of multiple factors such as equipment technology and formulation. Whiskers, on the other hand, are microcrystalline fibers that almost reach an ideal state, and their mechanical properties far exceed those of commonly used granular fillers such as wollastonite, silica, calcium carbonate powder, calcium sulfate powder, and talc. They combine the advantages of both reinforcing fibers and ultrafine inorganic fillers, making them a new type of inorganic chemical material with high comprehensive performance.

[0003] As an inorganic powder material in the form of columnar short fibers, whiskers, when applied to the extrusion foaming of polyolefins, not only have a reinforcing effect on polyolefin materials, but also act as a stirrer (nucleating agent). This makes the gas in the cells more uniform and fine under the action of whiskers during the extrusion and mixing process, thus effectively solving the problems of uneven foaming, rapid softening, and insufficient cell stiffness in polyolefin foamed materials.

[0004] However, when ordinary whisker powder or existing whisker masterbatch is used as a polyolefin foaming material, it is not uniform and extremely inconvenient to mix with polyolefin plastic particles. It is easy to generate dust, and the whiskers are prone to agglomeration during the mixing process, causing the mesh to clog. Moreover, the compatibility problem with polyolefin materials is difficult to solve, which further causes the mesh to clog. Summary of the Invention

[0005] In view of this, the purpose of this invention is to solve the problems of uneven foaming, rapid softening, and insufficient cell stiffness of whisker masterbatch in polyolefin foaming, and the problem of screen clogging when whisker masterbatch is applied to polyolefin foaming materials.

[0006] The embodiments of the present invention are implemented as follows:

[0007] A method for preparing whisker masterbatch for polyolefin foaming materials, the method comprising:

[0008] Whiskers, lubricants, dispersants, and coupling agents are added to an air-blast powder activator according to a set ratio, and activated under set conditions until fully activated whisker semi-finished products are obtained.

[0009] The whisker semi-finished product and polyethylene resin are fed into a twin-screw continuous internal mixing extruder with a grinding surface and hot cutting according to a set ratio, then mixed and extruded, and cut into particles by grinding surface and hot cutting.

[0010] The particles extruded from the twin-screw continuous internal mixing extruder are subjected to three-stage air cooling and then separated by a vibrating screen to finally obtain whisker masterbatch for polyolefin foaming materials.

[0011] Furthermore, in the above-mentioned method for preparing whisker masterbatch for polyolefin foaming materials, the extrusion temperature is 160℃-180℃ and the extrusion speed is 60HZ-80HZ.

[0012] Furthermore, in the above-mentioned method for preparing whisker masterbatch for polyolefin foaming materials, the activation rotation speed is 30HZ-50HZ and the activation temperature is 120℃-160℃.

[0013] Furthermore, in the above-mentioned method for preparing whisker masterbatch for polyolefin foaming materials, the polyethylene resin is one or a blend of two of high melt index linear low density polyethylene or high pressure low density polyethylene.

[0014] Furthermore, in the above-mentioned method for preparing whisker masterbatch for polyolefin foaming materials, the whiskers are one or more of calcium sulfate whiskers, calcium carbonate whiskers, and magnesium salt whiskers.

[0015] Furthermore, in the above-mentioned method for preparing whisker masterbatch for polyolefin foaming materials, the calcium sulfate whiskers, calcium carbonate whiskers, and magnesium salt whiskers are all inorganic short fibrous powders with a diameter of 1μm-5μm, a length of 5μm-10μm, and a length-to-diameter ratio of 5-10.

[0016] Furthermore, in the above-mentioned method for preparing whisker masterbatch for polyolefin foaming materials, the lubricant is one or more mixtures of PE wax, paraffin wax, and monoglyceride fatty acid ester.

[0017] Furthermore, in the above-mentioned method for preparing whisker masterbatch for polyolefin foaming materials, the dispersant is one or a mixture of zinc stearate, calcium stearate, EBS, and alkyl silicone oil.

[0018] Furthermore, in the above-mentioned method for preparing whisker masterbatch for polyolefin foaming materials, the coupling agent is one or more of titanate, aluminate, and borate coupling agents, or a mixture thereof.

[0019] Another object of the present invention is to provide a whisker masterbatch for polyolefin foaming materials, prepared by the method for preparing whisker masterbatch for polyolefin foaming materials described in any one of the above claims, wherein the whisker masterbatch for polyolefin foaming materials comprises the following components by mass percentage:

[0020] Polyethylene resin 8-16%, whiskers 70-85%, lubricant 5-10%, dispersant 0.5-1%, coupling agent 1-3%.

[0021] This invention utilizes whiskers of special fineness and length, and through suitable coupling and dispersing lubrication formulations, performs activation treatment through impregnation, mixing, and dispersion in an air-fluidized powder activation machine. The activated whiskers have a fully activated surface, avoiding agglomeration and bridging problems during stirring and extrusion. This results in whisker masterbatches that are highly compatible with plastics and less prone to screen clogging. Furthermore, extrusion granulation using a twin-screw continuous internal mixing extruder ensures the whisker structure remains intact, fundamentally altering whisker agglomeration. Simultaneously, the whisker masterbatches obtained by mixing high melt index polyethylene and activated whiskers in a twin-screw continuous internal mixing extruder exhibit fast melting speed and good dispersibility, further avoiding screen clogging and whisker breakage issues when used as polyolefin foaming materials. Attached Figure Description

[0022] Figure 1 This is a flowchart of a method for preparing whisker masterbatch for polyolefin foaming materials according to an embodiment of the present invention.

[0023] The following detailed description, in conjunction with the accompanying drawings, will further illustrate the present invention. Detailed Implementation

[0024] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.

[0025] Furthermore, the term "and / or" as used herein includes any and all combinations of one or more of the associated listed items. In the detailed description and claims, a list of items connected by the term "one of" may mean any of the listed items. For example, if items A and B are listed, then the phrase "one of A and B" means only A or only B. In another instance, if items A, B, and C are listed, then the phrase "one of A, B, and C" means only A; only B; or only C. Item A may contain a single element or multiple elements. Item B may contain a single element or multiple elements. Item C may contain a single element or multiple elements. In the detailed description and claims, a list of items connected by the terms "at least one of," "at least one of," or other similar terms may mean any combination of the listed items. For example, if items A and B are listed, then the phrase "at least one of A and B" or "at least one of A or B" means only A; only B; or A and B. In another instance, if items A, B, and C are listed, then the phrase "at least one of A, B, and C" or "at least one of A, B, or C" means only A; or only B; only C; A and B (excluding C); A and C (excluding B); B and C (excluding A); or all of A, B, and C. Item A may contain a single element or multiple elements. Item B may contain a single element or multiple elements. Item C may contain a single element or multiple elements.

[0026] This invention addresses the problems of easy clogging of the extrusion mesh and easy breakage of whiskers when used as polyolefin foaming materials. It proposes a method for preparing whisker masterbatches for polyolefin foaming materials, wherein the method includes:

[0027] Step S10: Add whiskers, lubricant, dispersant and coupling agent to the air-blast powder activator according to the set ratio, and perform activation treatment under the set conditions until the whisker semi-finished product is fully activated.

[0028] The whiskers can be one or more mixtures of calcium sulfate whiskers, calcium carbonate whiskers, and magnesium salt whiskers. In specific implementations, whiskers with special fineness and length are used. Specifically, calcium sulfate whiskers, calcium carbonate whiskers, and magnesium salt whiskers can all be inorganic short fibrous powders with a diameter of 1-5 μm, a length of 5-10 μm, and a length-to-diameter ratio of 5-10. In the embodiments of the present invention, the lubricant can be one or more mixtures of PE wax, paraffin wax, and monoglyceride fatty acid esters; the dispersant can be one or more of zinc stearate, calcium stearate, EBS, and alkyl silicone oil. The mixture; the coupling agent can be one or more of titanate, aluminate, and borate coupling agents; the set ratio can be whiskers 70-85% : lubricant 5-10% : dispersant 0.5-1% : coupling agent 1-3%. It is understandable that after activation treatment, the whiskers' surface is fully activated. However, general whisker masterbatches do not fundamentally solve the problem of sufficient surface activation of fibrous inorganic materials. This directly leads to agglomeration and bridging problems of whiskers during stirring and extrusion processing, making the resulting whisker masterbatches incompatible with plastics and prone to clogging. The activation speed is 30Hz-50Hz, and the activation temperature is 120℃-160℃. In some preferred embodiments of the present invention, whiskers and dispersant can be added to an air-blast powder activator first, and the whiskers can be fully dispersed at a speed of 30 Hz-50 Hz and a temperature of 140 ℃-160 ℃ for 3 min-5 min. Then, coupling agent is melted at 120 ℃-160 ℃ and sprayed into the air-blast powder activator through a spray device to perform coupling treatment on the whiskers. Finally, lubricant is melted at 120 ℃-160 ℃ and sprayed into the air-blast powder activator through a spray device to obtain a fully activated whisker semi-finished product.

[0029] Step S11: The whisker semi-finished product and polyethylene resin are introduced into a twin-screw continuous internal mixing extruder with a grinding surface and hot cutting according to a set ratio, and then extruded and cut into particles by grinding surface and hot cutting.

[0030] The polyethylene resin is one or a blend of high melt index linear low-density polyethylene or high-pressure low-density polyethylene. The mass percentage of the polyethylene resin is 8-16%, and the internal mixer is a twin-screw continuous internal mixer extruder with an extrusion temperature of 160℃-180℃ and an extrusion speed of 60HZ-80HZ.

[0031] Step S12: The particles extruded from the twin-screw continuous internal mixing extruder are subjected to three-stage air cooling and then separated by a vibrating screen to finally obtain whisker masterbatch for polyolefin foaming materials.

[0032] In this process, the extruded whisker masterbatch particles are sorted to obtain the final whisker masterbatch used for polyolefin foaming materials.

[0033] On the other hand, the whisker masterbatch for polyolefin foaming materials proposed in the embodiments of the present invention is prepared by the preparation method of whisker masterbatch for polyolefin foaming materials described in any one of the above-mentioned methods. The whisker masterbatch for polyolefin foaming materials comprises the following components by mass percentage: 8-16% polyethylene resin, 70-85% whiskers, 5-10% lubricant, 0.5-1% dispersant, and 1-3% coupling agent.

[0034] To facilitate understanding of the present invention, several embodiments are given below. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided so that the disclosure of the present invention will be more thorough and complete.

[0035] Example 1

[0036] Whiskers, lubricants, dispersants, and coupling agents are added to an air-blast powder activator according to a set ratio and activated at a speed of 30-50 Hz and a temperature of 120-160 ℃ until fully activated whisker semi-finished products are obtained.

[0037] The whisker semi-finished product and polyethylene resin are introduced into a twin-screw continuous internal mixing extruder with a grinding surface and hot cutting according to a set ratio. After mixing at a temperature of 150℃-170℃ and an extrusion speed of 60HZ-80HZ, the mixture is extruded and cut into particles by grinding surface and hot cutting.

[0038] The particles extruded from the twin-screw continuous internal mixing extruder are subjected to three-stage air cooling and then separated by a vibrating screen to finally obtain whisker masterbatch for polyolefin foaming materials.

[0039] The polyethylene resin accounts for 13% of the total mass. This polyethylene resin is a blend of two types of polyethylene: high melt index linear low density polyethylene (50 g / 10 min (2.16 kg) and high pressure low density polyethylene (5%). The high melt index linear low density polyethylene accounts for 8% of the total mass, and the high pressure low density polyethylene accounts for 5% of the total mass.

[0040] The whiskers have a mass percentage of 80%, and are a mixture of calcium sulfate whiskers and magnesium salt whiskers. The mass percentage of calcium sulfate whiskers is 75%, and the mass percentage of magnesium salt whiskers is 5%. Both types of whiskers have a diameter of 1-5 μm, a length of 5-10 μm, and a length-to-diameter ratio of 5-10.

[0041] The mass percentage of the lubricant is 6%, and the lubricant is a mixture of monoglyceride fatty acid ester and PE wax, with the monoglyceride fatty acid ester accounting for 5% by mass and the PE wax accounting for 1% by mass.

[0042] The dispersant has a mass percentage of 1%, and is a mixture of zinc stearate and calcium stearate, with zinc stearate having a mass percentage of 0.5% and calcium stearate having a mass percentage of 0.5%.

[0043] The coupling agent has a mass percentage of 2% and is an aluminate coupling agent.

[0044] Example 2

[0045] This embodiment also proposes a whisker masterbatch for polyolefin foaming materials and its preparation method. The whisker masterbatch for polyolefin foaming materials and its preparation method proposed in this embodiment are largely the same as those proposed in Example 1, except that:

[0046] The polyethylene resin has a mass percentage of 16%. This polyethylene resin is a blend of two types of polyethylene: high melt index linear low density polyethylene with a melt index of 50 g / 10 min (2.16 KG) and high pressure low density polyethylene. The mass percentage of high melt index linear low density polyethylene with a melt index of 50 g / 10 min (2.16 KG) is 10%, and the mass percentage of high pressure low density polyethylene is 6%.

[0047] The whiskers have a mass percentage of 70%, and are a mixture of calcium sulfate whiskers and magnesium salt whiskers, wherein the mass percentage of calcium sulfate whiskers is 65%, the mass percentage of magnesium salt whiskers is 5%, the diameter of both whiskers is 1-5μm, the length is 5-10μm, and the length-to-diameter ratio is 5-10.

[0048] The lubricant has a mass percentage of 10% and is a mixture of monoglyceride fatty acid ester and PE wax, wherein the monoglyceride fatty acid ester has a mass percentage of 5% and the PE wax has a mass percentage of 5%.

[0049] The dispersant has a mass percentage of 1%, and is a mixture of zinc stearate and calcium stearate, wherein the mass percentage of zinc stearate is 0.5% and the mass percentage of calcium stearate is 0.5%.

[0050] The coupling agent has a mass percentage of 3% and is a titanate coupling agent.

[0051] Example 3

[0052] This embodiment also proposes a whisker masterbatch for polyolefin foaming materials and its preparation method. The whisker masterbatch and its preparation method for polyolefin foaming materials proposed in this embodiment are largely the same as those proposed in Example 1, except that:

[0053] The polyethylene resin has a mass percentage of 8%. The polyethylene resin is a blend of two types of polyethylene: high melt index linear low density polyethylene with a melt index of 50 g / 10 min (2.16 KG) and high pressure low density polyethylene. The mass percentage of high melt index linear low density polyethylene with a melt index of 50 g / 10 min (2.16 KG) is 5%, and the mass percentage of high pressure low density polyethylene is 3%.

[0054] The whiskers have a mass percentage of 85%. These short whiskers are a mixture of calcium sulfate whiskers and magnesium salt whiskers, wherein the mass percentage of calcium sulfate whiskers is 70% and the mass percentage of magnesium salt whiskers is 15%. Both types of whiskers have a diameter of 1-5 μm, a length of 5-10 μm, and an aspect ratio of 5-10.

[0055] The lubricant has a mass percentage of 5% and is a mixture of monoglyceride fatty acid ester and PE wax, wherein the monoglyceride fatty acid ester has a mass percentage of 3% and the PE wax has a mass percentage of 2%.

[0056] The dispersant has a mass percentage of 0.8% and is a mixture of zinc stearate and calcium stearate, wherein the mass percentage of zinc stearate is 0.5% and the mass percentage of calcium stearate is 0.3%.

[0057] The coupling agent has a mass percentage of 1.2% and is a titanate coupling agent.

[0058] Example 4

[0059] The polyethylene resin comprises 12% by mass. This polyethylene resin is a blend of two materials: high melt index linear low-density polyethylene (LLDPE) with a melt index of 50 g / 10 min (2.16 kg) and high-pressure low-density polyethylene (HDPE). Specifically, the high melt index LLDPE comprises 8% by mass, and the HDPE comprises 4% by mass.

[0060] The whiskers have a mass percentage of 78%. The short whiskers are a mixture of calcium sulfate whiskers and calcium calcate whiskers, wherein the mass percentage of calcium sulfate whiskers is 70% and the mass percentage of magnesium salt whiskers is 8%. Both types of whiskers have a diameter of 1-5 μm, a length of 5-10 μm, and an aspect ratio of 5-10.

[0061] The lubricant has a mass percentage of 8% and is a mixture of monoglyceride fatty acid ester and PE wax, wherein the monoglyceride fatty acid ester has a mass percentage of 5% and the PE wax has a mass percentage of 3%.

[0062] The dispersant has a mass percentage of 0.8% and is a mixture of zinc stearate and calcium stearate, wherein the mass percentage of zinc stearate is 0.5% and the mass percentage of calcium stearate is 0.3%.

[0063] The coupling agent has a mass percentage of 1.2% and is a borate coupling agent.

[0064] Example 5

[0065] The polyethylene resin accounts for 10% by mass. This polyethylene resin is a blend of two types: high melt index linear low density polyethylene (MLPE) with a melt index of 50 g / 10 min (2.16 kg) and high-pressure low-density polyethylene (HDPE). Specifically, the high melt index linear low-density polyethylene with a melt index of 50 g / 10 min (2.16 kg) accounts for 6% by mass, and the HDPE accounts for 4% by mass.

[0066] The whiskers comprise 80% by mass. These short whiskers are a mixture of calcium sulfate whiskers and calcium calcate whiskers, wherein the calcium sulfate whiskers comprise 70% by mass and the magnesium salt whiskers comprise 10% by mass. Both types of whiskers have a diameter of 1-5 μm, a length of 5-10 μm, and an aspect ratio of 5-10.

[0067] The lubricant has a mass percentage of 8% and is a mixture of monoglyceride fatty acid esters and PE wax, wherein the monoglyceride fatty acid esters have a mass percentage of 5% and the paraffin wax has a mass percentage of 3%.

[0068] The dispersant has a mass percentage of 0.5% and is a mixture of zinc stearate and calcium stearate, wherein the mass percentage of zinc stearate is 0.3% and the mass percentage of EBS is 0.2%.

[0069] The coupling agent has a mass percentage of 1.5% and is a borate coupling agent.

[0070] Compare with Example 1

[0071] (1) Add calcium sulfate whiskers to a high-speed mixer, stir and add coupling agent, and stir at a speed of 1500 rpm for 4 to 10 minutes;

[0072] (2) Add polyolefin and wax to a high-speed mixer and mix at low speed for 1 to 4 minutes to obtain the mixture;

[0073] (3) The mixture is placed in a single screw extruder for melt extrusion and granulation to obtain calcium sulfate whisker masterbatch.

[0074] The composition includes 10-30% polyolefin by mass, 5-20% wax by mass, and 0.2-1.5% coupling agent by mass.

[0075] Please refer to Table 1 below, which shows the parameters corresponding to Embodiments 1-5 and Comparative Example 1 of the present invention, as shown in the table below:

[0076] Table 1

[0077]

[0078] In practical applications, data tests were conducted on the whisker aspect ratio distribution after burn-off at 350°C using Examples 1-5 and Comparative Example 1 of the present invention, respectively, to investigate the mesh blockage and the whisker masterbatch manufactured by different methods under the above-mentioned conditions. The test data are shown in Table 2 below.

[0079] Table 2

[0080]

[0081] In summary, based on the data in Tables 1 and 2 above, it is evident that this invention utilizes whiskers of special fineness and length, employing suitable coupling and dispersion lubrication formulations. These whiskers undergo impregnation, mixing, and dispersion treatment in an air-fluidized powder activation machine. The activated whiskers have a fully activated surface, preventing agglomeration and bridging during stirring and extrusion. This results in whisker masterbatches that are highly compatible with plastics and less prone to clogging. Furthermore, the use of a twin-screw continuous internal mixing extruder for extrusion granulation ensures the whisker structure remains intact, fundamentally altering the agglomeration phenomenon. Simultaneously, the whisker masterbatches obtained by mixing high melt index polyethylene and activated whiskers in a twin-screw continuous internal mixing extruder exhibit rapid melting and good dispersibility, further preventing clogging issues between the whisker masterbatches and polyolefin foaming materials.

[0082] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention. Therefore, the scope of protection of this patent should be determined by the appended claims.

Claims

1. A method for preparing whisker masterbatch for polyolefin foaming materials, characterized in that, The method includes: Whiskers, lubricants, dispersants, and coupling agents are added to an air-blast powder activator according to a set ratio, and activated under set conditions until fully activated whisker semi-finished products are obtained. The whisker semi-finished product and polyethylene resin are fed into a twin-screw continuous internal mixing extruder with a grinding surface and hot cutting according to a set ratio, then mixed and extruded, and cut into particles by grinding surface and hot cutting. The particles extruded from the twin-screw continuous internal mixing extruder are subjected to three-stage air cooling and then separated by a vibrating screen to finally obtain whisker masterbatch for polyolefin foam materials. The extrusion temperature is 160℃-180℃ and the extrusion speed is 60Hz-80Hz. The activation speed is 30Hz-50Hz, and the activation temperature is 120℃-160℃; The process involves first adding whiskers and dispersant to an air-blast powder activator, where the whiskers are fully dispersed at a speed of 30-50 Hz and a temperature of 140-160 ℃ for 3-5 minutes. Then, a coupling agent is melted at 120-160 ℃ and sprayed into the air-blast powder activator to couple the whiskers. Finally, a lubricant is melted at 120-160 ℃ and sprayed into the air-blast powder activator to obtain a fully activated semi-finished whisker product. The dispersant is one or a mixture of zinc stearate, calcium stearate, EBS, and alkyl silicone oil; The coupling agent is one or a mixture of titanate, aluminate, and borate coupling agents; Whiskers are inorganic short fibrous powders with a diameter of 1µm-5µm, a length of 5µm-10µm, and an aspect ratio of 5-10.

2. The method for preparing whisker masterbatch for polyolefin foaming materials according to claim 1, characterized in that, The polyethylene resin is one or a blend of two of high melt index linear low density polyethylene or high pressure low density polyethylene.

3. The method for preparing whisker masterbatch for polyolefin foaming materials according to claim 1, characterized in that, The whiskers are one or more of calcium sulfate whiskers, calcium carbonate whiskers, and magnesium salt whiskers.

4. The method for preparing whisker masterbatch for polyolefin foaming materials according to claim 1, characterized in that, The lubricant is one or more of PE wax, paraffin wax, and monoglyceride fatty acid esters.

5. A whisker masterbatch for use in polyolefin foam materials, characterized in that, The whisker masterbatch for polyolefin foaming materials is prepared by the method described in any one of claims 1 to 4, wherein the whisker masterbatch for polyolefin foaming materials comprises the following components by mass percentage: Polyethylene resin 8-16%, whiskers 70-85%, lubricant 5-10%, dispersant 0.5-1%, coupling agent 1-3%.

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