Polyolefin copolymer micronization and polyolefin copolymer dry micronization method

Abstract

The invention discloses a polyolefin copolymer micronization method which comprises the following steps: performing functional group reaction grafting on polyolefin resin particles to obtain polyolefin resin particles containing unsaturated carboxylic acid groups; putting the polyolefin resin particles containing unsaturated carboxylic acid groups into a co-rotating twin-screw extruder; the polyolefin resin particles are firstly heated to a molten state by the extruder in the heating section; dissolving an interface active agent in water, stirring until the interface active agent is dissolved, and injecting into an extruder through a high-pressure pump, so that the polyolefin resin and the water are continuously subjected to high shear mixing; the particle size of the polyolefin resin becomes smaller and smaller along with screw shearing, and finally extremely small particles are obtained and are uniformly dispersed in water to form a polyolefin aqueous dispersion; and finally, rapidly cooling the polyolefin aqueous dispersion.

Description

Technical Field

[0001] This invention relates to a method for polyolefin micronization, and more particularly to a method for processing polyolefin resin particles into a polyolefin aqueous dispersion or a dried polyolefin copolymer micro powder without using cryogenic grinding or solvent methods. Background Technology

[0002] Polyolefin is a type of olefin with the general formula (CH2CHR). n Polyolefins are polymers in which R is an alkyl group. They are typically derived from a group of simple olefins, forming different types of polyolefins depending on the olefin structure. Industrially, TPO (Thermoplastic polyolefin) is often used to refer to all such materials. Among polymer materials, polyolefins are widely used commercially due to their light weight, ease of processing, and excellent physical properties. Commercially available polyolefins are granular with a particle size of 3-5 mm and cannot be used at room temperature. They must be heated and melted to a flowable and plastic state (70-150℃ depending on the specifications). If polyolefins are to be used as a barrier layer in porous materials, it is difficult to achieve a low film thickness using melt coating processes. There are also application bottlenecks in coating processes.

[0003] Furthermore, due to their low polarity and low free radical content, polyolefins exhibit severely insufficient wettability, making them difficult to bond and adhere to other materials. This typically requires the assistance of toxic solvents (toluene, xylene) or halogenated polymers (chlorinated polyolefins) to achieve adhesion, which raises environmental and occupational safety concerns. The adhesives used may also limit the recycling and reuse of the finished product. The most common method for reducing polyolefin particle size is cryogenic milling. However, because polyolefins have a low melting point, room-temperature milling causes frictional heat, leading to melting and loss of particle size. Liquid nitrogen is sometimes used to cool the polyolefins and prevent melting. Even with cryogenic milling, uniform particle size and shape are difficult to achieve, and the equipment and production costs are extremely high, making it unsuitable for most commercial applications. In addition, while solvent methods can achieve micronization, solvents that can dissolve polyolefins are generally highly hazardous, leading to further environmental and cost issues.

[0004] Therefore, how to solve the problems and deficiencies of the existing technologies is the research topic that relevant industry players are eager to develop. Summary of the Invention

[0005] The purpose of this invention is to provide a method for micronizing polyolefin copolymers.

[0006] This invention provides a method for micronizing a polyolefin copolymer, particularly suitable for processing a polyolefin resin particle into a polyolefin aqueous dispersion without using cryogenic grinding. The method for micronizing the polyolefin copolymer includes: S110: grafting the polyolefin resin particle with functional groups to become a polyolefin resin particle containing unsaturated carboxylic acid groups; S120: feeding the polyolefin resin particle containing unsaturated carboxylic acid groups into a co-rotating twin-screw extruder; S130: dissolving a surfactant in water and stirring until dissolved, then injecting it into the co-rotating twin-screw extruder via a high-pressure pump; S140: subjecting the polyolefin resin particle containing unsaturated carboxylic acid groups to continuous high shear in water using the co-rotating twin-screw extruder, wherein the polyolefin resin particle containing unsaturated carboxylic acid groups is mixed with water in a molten state; S150: forming microparticles from the polyolefin resin particle containing unsaturated carboxylic acid groups to uniformly disperse in water, forming the polyolefin aqueous dispersion; and S160: rapidly cooling the polyolefin aqueous dispersion.

[0007] In one embodiment of the present invention, in the step of functionalizing the polyolefin resin particles by grafting, the polyolefin resin particles are grafted with maleic anhydride or methacrylic acid by functionalizing the resin particles.

[0008] In one embodiment of the present invention, the polyolefin resin particles are a copolymer of ethylene and propylene.

[0009] In one embodiment of the present invention, the polyolefin aqueous dispersion is composed of polyolefin microparticles dispersed in water, all with a particle size of less than 10 micrometers.

[0010] In one embodiment of the present invention, the polyolefin in the polyolefin aqueous dispersion has a solid content of 40-60 wt% and a viscosity of 300-80,000 centipoise (cP).

[0011] In one embodiment of the present invention, in step S140, under the continuous high shear environment of the co-rotating twin-screw extruder, a surfactant is used to prevent the formation of a continuous phase, thereby making the particle size smaller and smaller as the screw shears.

[0012] This invention provides a method for drying and micronizing polyolefin copolymers, particularly suitable for processing polyolefin resin particles into dry micronized polyolefin copolymers without using cryogenic grinding. The method includes: S210: grafting the polyolefin resin particles with functional groups to obtain polyolefin resin particles containing unsaturated carboxylic acid groups; S220: feeding the polyolefin resin particles containing unsaturated carboxylic acid groups into a twin-screw extruder; S230: dissolving a surfactant in water and stirring until dissolved, then injecting the solution via a high-pressure pump. The polyolefin resin particles containing unsaturated carboxylic acid groups are fed into the co-rotating twin-screw extruder; S240: The polyolefin resin particles containing unsaturated carboxylic acid groups are subjected to continuous high shear in water by the co-rotating twin-screw extruder, wherein the polyolefin resin particles containing unsaturated carboxylic acid groups are mixed with water in a molten state; S250: The polyolefin resin particles containing unsaturated carboxylic acid groups form microparticles and are uniformly dispersed in water to form the polyolefin aqueous dispersion; S260: The polyolefin aqueous dispersion is rapidly cooled; and S270: The water in the polyolefin aqueous dispersion is removed by a dehydration process to obtain the dried micro powder of the polyolefin copolymer.

[0013] In summary, the method for micronizing and drying polyolefin copolymers into micro-powders disclosed in this invention can achieve the following effects:

[0014] 1. It can achieve coatings with extremely low film thickness. Micronized polyolefins can penetrate deep into porous materials, and then form films through subsequent heating and pressurization processes, thereby overcoming their difficulty in bonding.

[0015] 2. Used in coating, impregnation, spraying and other processes, it can be regarded as a water-based coating or water-based adhesive;

[0016] 3. It retains the characteristics of thermoplastic resin, has flow plasticity at a specific temperature (resin melting point), has excellent film-forming properties, and has excellent compatibility with many common resins such as nylon and polyester with polar functional groups. Compared with cross-linking reactive adhesives, it makes the finished product easier to recycle in the future.

[0017] 4. The micronized polyolefin copolymer dry powder can be mixed with other powder materials, such as cement, ceramics, or metals, for applications such as waterproofing, sintering, or adhesion; and

[0018] 5. Micronized polyolefin copolymer dry powder mixed with natural fibers can be used as an adhesive, which can significantly reduce the resin content in the finished product.

[0019] The following detailed description through specific embodiments should make it easier to understand the purpose, technical content, features, and effects achieved by the present invention. Attached Figure Description

[0020] Figure 1 This is a flowchart of the method for micronizing polyolefin copolymers according to the present invention.

[0021] Figure 2 This is a diagram showing the particles of a polyolefin aqueous dispersion observed under a scanning electron microscope according to the present invention.

[0022] Figure 3 This is a flowchart of the method for drying and micronizing polyolefin copolymers according to the present invention.

[0023] Explanation of icon numbers:

[0024] 100: Methods for micronizing polyolefin copolymers;

[0025] S110, S120, S130, S140, S150, S160: Steps;

[0026] 200: A method for drying and micronizing polyolefin copolymers;

[0027] S210, S220, S230, S240, S250, S260, S270: Steps. Detailed Implementation

[0028] After years of research and development, the inventors have improved upon the shortcomings of existing products. The following will detail how this invention achieves the most efficient functional requirements through a method of micronizing and drying polyolefin copolymers into micro powder.

[0029] Please see Figure 1 and Figure 2 , Figure 1 This is a flowchart of the method for micronizing polyolefin copolymers according to the present invention. Figure 2This image shows the particle size distribution of a polyolefin aqueous dispersion observed under a scanning electron microscope, based on the present invention. The invention primarily involves micronizing polyolefins containing unsaturated carboxylic acid groups in water through continuous shearing, producing polyolefin microparticles dispersed in water with a particle size less than 10 micrometers (μm). Both the resulting polyolefin aqueous dispersion and the powder after water removal have commercial applications. Furthermore, the invention mainly involves micronizing and dispersing functionalized polyolefin materials in water, allowing polyolefin resins to be coated at room temperature. Due to the low viscosity of the aqueous solution, extremely thin film coatings can be achieved. The micronized polyolefins can penetrate deep into porous materials, and subsequent hot-pressing processes can be used to form a film, overcoming the difficulty in adhesion. This method preserves the thermoplastic properties of polyolefin materials, and polyolefins with polar functional groups have excellent compatibility with many common resins, such as nylon and polyester. Compared to cross-linking reactive adhesives, this makes the finished product easier to recycle in the future. In addition, the micronized polyolefin copolymer dry powder can be mixed with other powder materials, such as cement, ceramics or metals, for waterproofing, sintering or adhesive purposes.

[0030] In detail, such as Figure 1 As shown, in this embodiment of the invention, the method 100 for micronizing polyolefin copolymers is particularly suitable for processing polyolefin resin particles into a polyolefin aqueous dispersion without using cryogenic milling or solvent methods. The method for micronizing polyolefin copolymers includes the following steps. Step S110: The polyolefin resin particles are grafted with functional groups to become polyolefin resin particles containing unsaturated carboxylic acid groups; Step S120: The polyolefin resin particles containing unsaturated carboxylic acid groups are fed into a co-rotating twin-screw extruder; Step S130: An surfactant is dissolved in water and stirred until dissolved, and then injected into the co-rotating twin-screw extruder via a high-pressure pump; Step S140: The polyolefin resin particles containing unsaturated carboxylic acid groups are subjected to continuous high shear in water by the co-rotating twin-screw extruder, wherein the polyolefin resin particles containing unsaturated carboxylic acid groups are mixed with water in a molten state; Step S150: The polyolefin resin particles containing unsaturated carboxylic acid groups are formed into microparticles and uniformly dispersed in water to form the polyolefin aqueous dispersion; and Step S160: The polyolefin aqueous dispersion is rapidly cooled.

[0031] In the initial step S110, the polyolefin resin particles are grafted with maleic anhydride or methacrylic acid through a functional group reaction, thereby giving the polyolefin resin particles unsaturated carboxylic acid groups. The polyolefin resin particles are an ethylene-propylene copolymer. Next, in step S120, a co-rotating twin-screw extruder is used to feed the polyolefin resin particles containing unsaturated carboxylic acid groups into the extruder. Then, in steps S130 and S140, a surfactant and water are introduced into the co-rotating twin-screw extruder, where the polyolefin resin particles containing unsaturated carboxylic acid groups are mixed with water in a molten state. Subsequently, under the continuous high-shear environment of the co-rotating twin-screw extruder, the surfactant prevents the formation of a continuous phase, causing the particle size to decrease with screw shear, ultimately resulting in a uniform dispersion of the polyolefin in water, forming the polyolefin aqueous dispersion. It is worth mentioning that the particle size of the polyolefin particles in this polyolefin aqueous dispersion is all less than 10 micrometers. The solid content of the polyolefin aqueous dispersion obtained by the above method can be controlled between 40 and 60 wt%. Furthermore, the viscosity of this polyolefin aqueous dispersion varies with the polyolefin solid content. That is, if the polyolefin solid content of the produced polyolefin aqueous dispersion is 60 wt%, the viscosity of the polyolefin aqueous dispersion will be as high as about 80,000 centipoise (cP). This invention can easily change the polyolefin solid content by adding water to the polyolefin aqueous dispersion, thereby adjusting the viscosity of the polyolefin aqueous dispersion to meet different application requirements. If the application field requires low viscosity, simply dilute the polyolefin solid content with water to 45-50 wt%, and the viscosity can be reduced to 2000-3500 centipoise (cP), and so on. In this invention, the polyolefin aqueous dispersion is a polyolefin copolymer dispersed in water in spherical form with a particle size of 1-10 μm. The more uniform the particle size, the more stable the viscosity, which is crucial for the quality of the finished product. Next, proceeding to step S160, the polyolefin copolymer (ethylene-propylene copolymer or polyolefin resin particles) has been sheared into extremely small particles by a co-rotating twin-screw extruder. To prevent particle re-aggregation, the polyolefin aqueous dispersion needs to be rapidly cooled. The duration and temperature of this rapid cooling depend on the specific characteristics of the polyolefin aqueous dispersion, as the quantity of the dispersion also depends on the actual production situation, ensuring that the finished product is dispersed in water in spherical form with a particle size of 1-10 μm. Next, as... Figure 2 As shown, when the polyolefin aqueous dispersion was observed under a scanning electron microscope, it can be seen that the polyolefin particle size was processed to be reduced to 1-10 μm, which also shows that the method for micronizing polyolefin copolymers disclosed in this invention is indeed feasible.

[0032] The spirit of this embodiment is as follows: Micronizing the polyolefin material requires water as a medium. A reaction grafting process is first performed in a co-rotating twin-screw extruder to impart carboxylic acid groups to the polyolefin material. While the material is in a molten state, pure water and a surfactant are injected. Combined with the continuous high shear of the co-rotating twin-screw extruder and the assistance of the surfactant, the particle size of the polyolefin is rapidly and significantly reduced, resulting in a finished polyolefin aqueous dispersion. The micronized polyolefin aqueous dispersion of this invention can be used in coating, wetting, and spraying processes and can be considered a water-based coating or water-based adhesive. In addition to particle size reduction, it retains the characteristics of thermoplastic resin, exhibiting flow plasticity at a specific temperature (resin melting point) and possessing excellent film-forming properties.

[0033] Next, please refer to Figure 3 , Figure 3 This is a flowchart of the method for drying and micronizing polyolefin copolymers according to the present invention. As shown, the method for drying and micronizing polyolefin copolymers is particularly suitable for processing polyolefin resin particles into dried polyolefin copolymer powders without using cryogenic grinding or solvent methods. The method for drying and micronizing polyolefin copolymers includes the following steps. Step S210: The polyolefin resin particles are grafted with functional groups to become polyolefin resin particles containing unsaturated carboxylic acid groups; Step S220: The polyolefin resin particles containing unsaturated carboxylic acid groups are fed into a co-rotating twin-screw extruder; Step S230: An surfactant is dissolved in water and stirred until dissolved, then injected into the co-rotating twin-screw extruder via a high-pressure pump; Step S240: The polyolefin resin particles containing unsaturated carboxylic acid groups are subjected to continuous high shear in water by the co-rotating twin-screw extruder, wherein the polyolefin resin particles containing unsaturated carboxylic acid groups are mixed with water in a molten state; Step S250: The polyolefin resin particles containing unsaturated carboxylic acid groups are formed into microparticles and uniformly dispersed in water to form the polyolefin aqueous dispersion; Step S260: The polyolefin aqueous dispersion is rapidly cooled; and Step S270: The water in the polyolefin aqueous dispersion is removed by a dehydration process to obtain the dried micro powder of the polyolefin copolymer. It should be noted that... Figure 3 The embodiments are mainly a continuation Figure 1The embodiment mainly adds a dehydration process in step S270 to remove water from the polyolefin aqueous dispersion, forming a dried polyolefin copolymer micro powder. The dried polyolefin copolymer micro powder in this embodiment can have different advantages and applications. That is, by removing water through a dehydration process or drying procedure, a dried polyolefin copolymer micro powder with uniform and small particle size can be obtained. The dried polyolefin copolymer micro powder of this invention, when mixed with different powder materials, can meet a wider range of industrial applications, such as mixing with cement mortar to improve its waterproof performance. The dried polyolefin copolymer micro powder of this invention, when mixed with natural fibers, can act as an adhesive, significantly reducing the resin content in the finished product.

[0034] Furthermore, drying polyolefin aqueous dispersions yields dried polyolefin copolymer fine powder, which has a more concentrated particle size distribution and lower energy consumption and cost compared to cryogenic milling. In addition, polyolefin copolymer fine powder can be mixed with other non-resin materials for applications such as adhesion, barrier, and waterproofing.

[0035] In summary, the method for micronizing and drying polyolefin copolymers into micro-powders disclosed in this invention can achieve the following effects:

[0036] 1. It can achieve coatings with extremely low film thickness. Micronized polyolefins can penetrate deep into porous materials and then be film-formed through subsequent heating and pressurization processes, thereby overcoming their difficulty in bonding.

[0037] 2. Used in coating, impregnation, spraying and other processes, it can be regarded as a water-based coating or water-based adhesive;

[0038] 3. It retains the characteristics of thermoplastic resin, exhibiting flowability and plasticity at specific temperatures (resin melting points) and possessing excellent film-forming properties. Furthermore, the polar functional groups in the polyolefin have excellent compatibility with many common resins, such as nylon and polyester, making the finished product easier to recycle in the future compared to cross-linking reactive adhesives.

[0039] 4. The micronized polyolefin copolymer dry powder can be mixed with other powder materials, such as cement, ceramics, or metals, for applications such as waterproofing, sintering, or adhesion; and

[0040] 5. Dry micro powder of polyolefin copolymers mixed with natural fibers can be used as an adhesive, which can significantly reduce the resin content in the finished product.

[0041] The above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of the invention. Therefore, all equivalent variations or modifications made in accordance with the features and spirit described in the claims of the present invention should be included within the scope of the patent application of the present invention.

Claims

1. A method for micronizing polyolefin copolymers, characterized in that, This method is particularly suitable for processing polyolefin resin particles into a polyolefin aqueous dispersion without using cryogenic milling. The method for micronizing the polyolefin copolymer includes: S110: The polyolefin resin particle is grafted with a functional group reaction to become a polyolefin resin particle containing unsaturated carboxylic acid groups. S120: The polyolefin resin granules containing unsaturated carboxylic acid groups are fed into a twin-screw extruder. S130: Dissolve a surfactant in water and stir until dissolved, then inject it into the co-rotating twin-screw extruder via a high-pressure pump; S140: The polyolefin resin particles containing unsaturated carboxylic acid groups are subjected to continuous high shear in water by the co-rotating twin-screw extruder, wherein the polyolefin resin particles containing unsaturated carboxylic acid groups are mixed with water in a molten state. S150: The polyolefin resin containing unsaturated carboxylic acid groups forms tiny particles and is uniformly dispersed in water to form the polyolefin aqueous dispersion; and S160: Rapidly cool the polyolefin aqueous dispersion.

2. The method for micronizing polyolefin copolymers as described in claim 1, characterized in that, In the step of functionalizing the polyolefin resin particles, the polyolefin resin particles are grafted with maleic anhydride or methacrylic acid.

3. The method for micronizing polyolefin copolymers as described in claim 1, characterized in that, The polyolefin resin particles are copolymers of ethylene and propylene.

4. The method for micronizing polyolefin copolymers as described in claim 1, characterized in that, This polyolefin aqueous dispersion consists of polyolefin microparticles dispersed in water, with each particle size less than 10 micrometers.

5. The method for micronizing polyolefin copolymers as described in claim 1, characterized in that, The polyolefin solid content in this polyolefin aqueous dispersion is 40-60 wt%, and the viscosity is 300-80,000 centipoise (cP).

6. The method for micronizing polyolefin copolymers as described in claim 1, characterized in that, In step S140, under the continuous high-shear environment of the co-rotating twin-screw extruder, the surfactant is used to prevent the formation of a continuous phase, thereby making the particle size smaller and smaller as the screw shears.

7. A method for drying and micronizing a polyolefin copolymer, characterized in that, This method is particularly suitable for processing polyolefin resin particles into dry micro powder of a polyolefin copolymer without using cryogenic grinding. The method for drying and micro-powdering the polyolefin copolymer includes: S210: The polyolefin resin particle is grafted with a functional group reaction to become a polyolefin resin particle containing unsaturated carboxylic acid groups. S220: The polyolefin resin granules containing unsaturated carboxylic acid groups are fed into a twin-screw extruder. S230: Dissolve a surfactant in water and stir until dissolved, then inject it into the co-rotating twin-screw extruder via a high-pressure pump; S240: The polyolefin resin particles containing unsaturated carboxylic acid groups are subjected to continuous high shear in water by the co-rotating twin-screw extruder, wherein the polyolefin resin particles containing unsaturated carboxylic acid groups are mixed with water in a molten state. S250: The polyolefin resin containing unsaturated carboxylic acid groups forms tiny particles and is uniformly dispersed in water to form the polyolefin aqueous dispersion. S260: Rapidly cool the polyolefin aqueous dispersion; and S270: The water in the polyolefin aqueous dispersion is removed by a dehydration process to obtain the dried micro powder of the polyolefin copolymer.

8. The method for drying and micronizing polyolefin copolymers as described in claim 7, characterized in that, In the step of functionalizing the polyolefin resin particles, the polyolefin resin particles are grafted with maleic anhydride or methacrylic acid.

9. The method for drying and micronizing polyolefin copolymers as described in claim 7, characterized in that, The polyolefin resin particles are copolymers of ethylene and propylene.

10. The method for drying and micronizing polyolefin copolymers as described in claim 7, characterized in that, This polyolefin aqueous dispersion consists of polyolefin microparticles dispersed in water, with each particle size less than 10 micrometers.

11. The method for drying and micronizing polyolefin copolymers as described in claim 7, characterized in that, The polyolefin solid content in this polyolefin aqueous dispersion is 40-60 wt%, and the viscosity is 300-80,000 centipoise (cP).

12. The method for drying and micronizing polyolefin copolymers as described in claim 7, characterized in that, In step S140, under the continuous high-shear environment of the co-rotating twin-screw extruder, the surfactant is used to prevent the formation of a continuous phase, thereby making the particle size smaller and smaller as the screw shears.

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