Polyolefin copolymer microparticulation method and polyolefin copolymer drying and micronization method

Abstract

Disclosed in the present invention is a polyolefin copolymer microparticulation method, which comprises: carrying out functional group reaction grafting on polyolefin resin granules, so as to form polyolefin resin granules containing an unsaturated carboxyl group; putting the polyolefin resin granules containing the unsaturated carboxyl group into a co-rotating twin-screw extruder; first heating the polyolefin resin granules to a molten state in a heating section of the extruder; then dissolving a surfactant in water with stirring until the surfactant is dissolved, and injecting same into the extruder by means of a high-pressure pump; carrying out continuous high-shear mixing on the polyolefin resin and water, such that under the shear of the screws, the particle size of the polyolefin resin become smaller and smaller, and finally, the polyolefin resin becomes extremely fine particles and is uniformly dispersed in water, so as to form a polyolefin aqueous dispersion; and finally, rapidly quenching the polyolefin aqueous dispersion.

Description

Method for polyolefin copolymer micronization and polyolefin copolymer dry powderization TECHNICAL FIELD

[0001] The present invention relates to a method for polyolefin copolymer micronization and polyolefin copolymer dry powderization, and more particularly, to a method for processing and manufacturing a polyolefin resin particle into a polyolefin aqueous dispersion or a polyolefin copolymer dry powder without using a freeze grinding method or a solvent method. BACKGROUND

[0002] Polyolefin is a polymer with the general formula (CH2CHR) n wherein R is an alkyl group, which is usually derived from a group of simple olefins, and different polyolefin species are formed according to different olefin structures. In industry, TPO (thermoplastic polyolefin) is used to refer to all such materials. Among high molecular materials, polyolefin materials are widely used in commercial applications due to their light weight, easy processing, and excellent physical properties. Commercially available polyolefin materials are in the form of particles with a particle size of 3-5 mm, and cannot be used at room temperature. They must be heated to a molten state (70-150°C depending on the specification) to achieve plasticity. If polyolefin is used as a porous barrier material, it is difficult to achieve low film thickness using the melt coating process. There are application bottlenecks in the coating process.

[0003] In addition, due to the low polarity and low free radical of polyolefin in chemical structure, the wettability is seriously insufficient, and it is difficult to adhere to other materials. Usually, toxic solvents (toluene, xylene) or halogen polymers (chlorinated polyolefin) materials are used to achieve adhesion, but this also causes environmental and labor safety problems. The use of adhesives may limit the recycling of finished products after use. The most common way to reduce the particle size of polyolefin is freeze grinding. Since the melting point of polyolefin material is relatively low, grinding at room temperature will cause the material to melt due to friction heat, making it difficult to maintain particles. Liquid nitrogen is used to avoid melting of polyolefin, but even with freeze grinding, the particle size and shape are difficult to unify, and the equipment and production cost are extremely high, making it difficult to meet most commercial applications. In addition, although the solvent method can achieve micronization, the solvents that can dissolve polyolefin are highly dangerous and will cause more environmental and cost problems.

[0004] Therefore, how to solve the problems and deficiencies of the prior art is an urgent research and development issue for relevant persons in the industry.

[0005] SUMMARY

[0006] The purpose of the present invention is to provide a method for polyolefin copolymer micronization,

[0007] The present application provides a method for microparticulating a polyolefin copolymer, which is particularly suitable for manufacturing a polyolefin aqueous dispersion from polyolefin resin particles without using a freeze-milling method. The method for microparticulating a polyolefin copolymer includes: S110, grafting functional groups to the polyolefin resin particles to obtain polyolefin resin particles containing unsaturated carboxylic acid groups; S120, feeding the polyolefin resin particles containing unsaturated carboxylic acid groups into a co-rotating twin-screw extruder; S130, dissolving an interfacial agent in water and stirring until the interfacial agent is dissolved, and then injecting the interfacial agent into the co-rotating twin-screw extruder through a high-pressure pump; S140, continuously high-shearing the polyolefin resin particles containing unsaturated carboxylic acid groups 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, forming the polyolefin resin particles containing unsaturated carboxylic acid groups into small particles to uniformly disperse in water, thereby obtaining the polyolefin aqueous dispersion; and S160, rapidly cooling the polyolefin aqueous dispersion.

[0008] In an embodiment of the present application, in the step of grafting functional groups to the polyolefin resin particles, the polyolefin resin particles are grafted with maleic anhydride or methacrylic acid.

[0009] In an embodiment of the present application, the polyolefin resin particles are ethylene-propylene copolymer.

[0010] In an embodiment of the present application, the polyolefin aqueous dispersion is a polyolefin microparticle dispersion in water, and the particle size of the polyolefin microparticles is less than 10 microns.

[0011] In an embodiment of the present application, the solid content of the polyolefin in the polyolefin aqueous dispersion is 40-60 wt%, and the viscosity is 300-80,000 centipoise (cP).

[0012] In an embodiment of the present application, in the step S140, the interfacial agent is used to prevent the continuous phase from being reformed in the environment of continuous high shearing by the co-rotating twin-screw extruder, so that the particle size becomes smaller and smaller with the shearing of the screw.

[0013] The present application provides a method for producing a polyolefin copolymer dry powder, which is particularly suitable for producing a polyolefin copolymer dry powder from polyolefin resin particles without using a freeze grinding method. The method comprises the following steps: S210, performing a functional group reaction grafting on the polyolefin resin particles to obtain polyolefin resin particles containing unsaturated carboxyl groups; S220, feeding the polyolefin resin particles containing unsaturated carboxyl groups into a co-rotating twin-screw extruder; S230, dissolving an interfacial agent in water and stirring until dissolved, and then injecting the interfacial agent into the co-rotating twin-screw extruder through a high-pressure pump; S240, continuously high-shearing the polyolefin resin particles containing unsaturated carboxyl groups in water by the co-rotating twin-screw extruder, wherein the polyolefin resin particles containing unsaturated carboxyl groups are mixed with water in a molten state; S250, forming small particles of the polyolefin resin particles containing unsaturated carboxyl groups and uniformly dispersing the small particles in water to obtain a polyolefin aqueous dispersion; S260, rapidly cooling the polyolefin aqueous dispersion; and S270, removing water from the polyolefin aqueous dispersion by a dehydration process to obtain the polyolefin copolymer dry powder.

[0014] In summary, the method for producing a polyolefin copolymer dry powder disclosed in the present application can achieve the following effects:

[0015] 1. A coating layer with an extremely low film thickness can be achieved. The microparticulated polyolefin can penetrate into a porous material, and then a film is formed by a subsequent heating and pressurizing process, thereby making up for the poor adhesion of the polyolefin.

[0016] 2. The microparticulated polyolefin can be used in coating, impregnation, spraying, etc., and can be regarded as a water-based paint or a water-based adhesive.

[0017] 3. The microparticulated polyolefin still retains the properties of a thermoplastic resin, has flow plasticity at a specific temperature (resin melting point), has excellent film-forming properties, and has excellent compatibility with various common resins such as nylon and polyester. Compared with a cross-linking reaction type adhesive, the microparticulated polyolefin can make the finished product easier to recycle in the future.

[0018] 4. The microparticulated polyolefin dry powder can be mixed with other powder materials, such as cement, ceramic, or metal, for waterproofing, sintering, or adhesion.

[0019] 5. The microparticulated polyolefin dry powder can be mixed with natural fibers to serve as an adhesive, which can greatly reduce the content of resin in the finished product.

[0020] The purposes, technical contents, characteristics, and effects of the present application can be better understood through the following specific embodiments. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 is a flow chart of the method of the present application for the micronization of polyolefin copolymer.

[0022] Figure 2 is a display of the particles of the polyolefin aqueous dispersion observed under a scanning electron microscope.

[0023] Figure 3 is a flow chart of the method of the present application for the dry micronization of polyolefin copolymer.

[0024] BRIEF DESCRIPTION OF DRAWINGS

[0025] 100: method of the micronization of polyolefin copolymer;

[0026] S110, S120, S130, S140, S150, S160: steps;

[0027] 200: method of the dry micronization of polyolefin copolymer;

[0028] S210, S220, S230, S240, S250, S260, S270: steps. DETAILED DESCRIPTION

[0029] The present application is the result of years of research and development by the inventor to improve the shortcomings of existing products. The present application is a method of the micronization of polyolefin copolymer and a method of the dry micronization of polyolefin copolymer.

[0030] Referring to Figures 1 and 2, Figure 1 is a flow chart of the method of the present application for the micronization of polyolefin copolymer. Figure 2 is a display of the particles of the polyolefin aqueous dispersion observed under a scanning electron microscope. The present application is mainly the micronization of polyolefin containing unsaturated carboxylic acid groups in water by continuous shearing to achieve a micronized state. The polyolefin microparticles dispersed in water can be produced, with a particle size of less than 10 microns (pm). The polyolefin aqueous dispersion or the powder after removing the water has commercial applications. Further, the present application is mainly the micronization of polyolefin materials with functional groups and dispersion in water. The polyolefin resin can be coated at room temperature. The viscosity of the aqueous solution is low, and a coating with an extremely low film thickness can be achieved. The micronized polyolefin can penetrate into porous materials, and then be formed into a film by subsequent hot pressing process, which makes up for the difficulty of adhesion. This method retains the thermoplastic properties of the polyolefin material, and the polar functional group of the polyolefin has excellent compatibility with various common resins, such as nylon and polyester. Compared with cross-linking reaction type adhesives, the finished product is easier to recycle. In addition, the dry micronized polyolefin copolymer powder can be mixed with other powder materials, such as cement, ceramics or metals, for waterproofing, sintering or adhesion.

[0031] In detail, as shown in FIG. 1, in the embodiment of the present application, the polyolefin copolymer microparticulation method 100 is particularly suitable for processing and manufacturing polyolefin resin particles into a polyolefin aqueous dispersion without using a freeze-grinding method and without using a solvent method. The polyolefin copolymer microparticulation method includes the following steps. Step S110: functional group reaction grafting is performed on the polyolefin resin particles to become polyolefin resin particles containing unsaturated carboxyl groups; Step S120: the polyolefin resin particles containing unsaturated carboxyl groups are put into a co-rotating twin-screw extruder; Step S130: an interfacial agent is dissolved in water and stirred until dissolved, and then injected into the co-rotating twin-screw extruder through a high-pressure pump; Step S140: the polyolefin resin particles containing unsaturated carboxyl groups are continuously subjected to high shear in water by the co-rotating twin-screw extruder, wherein the polyolefin resin particles containing unsaturated carboxyl groups are mixed with water in a molten state; Step S150: the polyolefin resin particles containing unsaturated carboxyl groups form small particles and are uniformly dispersed in water to form the polyolefin aqueous dispersion; and Step S160: the polyolefin aqueous dispersion is rapidly cooled.

[0032] In the first step S110, the polyolefin resin particles are grafted with maleic anhydride or methacrylic acid to have unsaturated carboxylic acid groups on the polyolefin resin particles, which are ethylene-propylene copolymers. Then, the process enters step S120, which requires a co-rotating twin-screw extruder. The polyolefin resin particles with unsaturated carboxylic acid groups are fed into the co-rotating twin-screw extruder. Then, the process enters steps S130 and S140, in which surfactant and water are introduced into the co-rotating twin-screw extruder, and the polyolefin resin particles with unsaturated carboxylic acid groups are mixed with water in a molten state. In the continuous high-shear environment of the co-rotating twin-screw extruder, the surfactant prevents the formation of a continuous phase, and the particle size of the polyolefin resin particles becomes smaller and smaller under the shear of the screw, and finally the polyolefin resin particles are uniformly dispersed in water to form a polyolefin aqueous dispersion. It is worth mentioning that the particle size of the polyolefin particles in the polyolefin aqueous dispersion is less than 10 microns. The solid content of the polyolefin aqueous dispersion obtained by the above method can be controlled between 40-60 wt%. Further, the viscosity of the polyolefin aqueous dispersion changes with the solid content of the polyolefin. That is, if the solid content of the polyolefin in the polyolefin aqueous dispersion produced is 60 wt%, the viscosity of the polyolefin aqueous dispersion will be as high as about 80,000 centipoise (cP). The present application can simply change the solid content of the polyolefin in the polyolefin aqueous dispersion by adding water, and thus adjust the viscosity of the polyolefin aqueous dispersion to meet the different requirements of the application field. If the application field is low viscosity, only the solid content of the polyolefin needs to be diluted to 45-50 wt% by adding water, and the viscosity can be reduced to 2000-3500 centipoise (cP), and so on. In the present application, the polyolefin aqueous dispersion is a spherical dispersion of polyolefin copolymers with a particle size of 1-10 microns in water. The more uniform the particle size, the more stable the viscosity, which is very important for the quality of the finished product. Then, the process enters step S160, at which point the polyolefin copolymers (ethylene-propylene copolymers or polyolefin resin particles) have been sheared into very small particles by the co-rotating twin-screw extruder. To prevent the particles from re-fusing, the polyolefin aqueous dispersion needs to be rapidly cooled. The rapid cooling time and temperature are determined according to the specific conditions of the polyolefin aqueous dispersion, and the amount of polyolefin aqueous dispersion is determined according to the actual production conditions, so that the finished product can be dispersed in water in the form of spherical particles with a particle size of 1-10 microns. Next, as shown in Figure 2, the polyolefin aqueous dispersion is observed under a scanning electron microscope, and it can be seen that the particle size of the polyolefin has been reduced to 1-10 microns, which shows that the method for micronizing the polyolefin copolymers disclosed in the present application is indeed feasible.

[0033] The spirit of the present embodiment is as follows: Micronized polyolefin material requires water as a medium, first reaction grafting in a co-rotating twin-screw extruder, to give the polyolefin material carboxylic acid groups. When the material is in a molten state, pure water and 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 greatly reduced, and the finished product of the polyolefin aqueous dispersion is obtained. The micronized polyolefin aqueous dispersion of the present invention can be used in coating, impregnation, spraying and other processes, and can be considered as a water-based paint or water-based adhesive. In addition to particle size reduction, the thermoplastic properties are still retained, and the flow plasticity is obtained at a certain temperature (resin melting point), which has excellent film forming property.

[0034] Next, please refer to FIG. 3, which is a flow chart of the method for drying and micronizing the polyolefin copolymer of the present invention. As shown in the figure, the method for drying and micronizing the polyolefin copolymer is particularly suitable for processing and manufacturing a polyolefin resin particle into a polyolefin copolymer dry micron powder without using a freeze grinding method and without using a solvent method. The method for drying and micronizing the polyolefin copolymer includes the following steps. Step S210: functional group reaction grafting is performed on the polyolefin resin particle to become a polyolefin resin particle containing unsaturated carboxylic acid groups; Step S220: the polyolefin resin particle containing unsaturated carboxylic acid groups is put into a co-rotating twin-screw extruder; Step S230: a surfactant is dissolved in water and stirred until dissolved, and then injected into the co-rotating twin-screw extruder through a high-pressure pump; Step S240: the polyolefin resin particle containing unsaturated carboxylic acid groups is subjected to continuous high shear in water by the co-rotating twin-screw extruder, wherein the polyolefin resin particle containing unsaturated carboxylic acid groups is mixed with water in a molten state; Step S250: the polyolefin resin particle containing unsaturated carboxylic acid groups forms small particles to uniformly disperse in water, thereby forming the polyolefin aqueous dispersion; Step S260: the polyolefin aqueous dispersion is rapidly cooled; and Step S270: water is removed from the polyolefin aqueous dispersion by a dehydration process to obtain the polyolefin copolymer dry micron powder. It should be noted that the embodiment of FIG. 3 mainly continues the embodiment of FIG. 1, and mainly adds the dehydration process of Step S270 to remove water from the polyolefin aqueous dispersion to form the polyolefin copolymer dry micron powder. The polyolefin copolymer dry micron powder in the embodiment of the present invention can have different advantages and application scenarios. That is, after removing water by the dehydration process or drying procedure, a polyolefin copolymer dry micron powder with uniform and small particle size can be obtained. The polyolefin copolymer dry micron powder of the present invention can be mixed with different powder materials to meet more extensive industrial applications, for example, mixed with cement mortar to improve its waterproof performance. The polyolefin copolymer dry micron powder of the present invention can be mixed with natural fibers to serve as an adhesive, which can greatly reduce the content of resin in the finished product.

[0035] In addition, the polyolefin copolymer fine powder obtained after drying the polyolefin aqueous dispersion has a more concentrated particle size distribution than that of the freeze-milled powder, and has lower energy consumption and cost. Furthermore, the polyolefin copolymer fine powder can be mixed with other non-wood materials and used as an adhesive, a barrier, a waterproof material, etc.

[0036] In summary, the method for micronization and drying of the polyolefin copolymer fine powder disclosed in the present application can achieve the following effects:

[0037] 1. A coating with an extremely low film thickness can be achieved. The micronized polyolefin can penetrate into a porous material, and then be film-formed by subsequent heating and pressurization processes, thereby compensating for the difficulty in adhesion.

[0038] 2. The process can be used for coating, impregnation, spraying, etc., and can be considered as a water-based paint or a water-based adhesive.

[0039] 3. The thermoplastic properties are still retained. The polyolefin with a polar functional group has excellent compatibility with various common resins, such as nylon and polyester. Compared with cross-linking reaction type adhesives, the product is easier to recycle in the future.

[0040] 4. The micronized polyolefin copolymer fine powder can be mixed with other powder materials, such as cement, ceramics or metals, for waterproof, sintering or adhesion purposes.

[0041] 5. The polyolefin copolymer fine powder mixed with natural fibers can be used as an adhesive, which can greatly reduce the content of resins in the finished product.

[0042] The above description is only a preferred embodiment of the present application, and is not intended to limit the scope of the present application. Therefore, any equivalent changes or modifications made in accordance with the features and spirit of the present application described in the claims should be included in the scope of the patent application.

Claims

1. A process for the microparticulation of a polyolefin copolymer, characterized in that, The method for manufacturing a polyolefin aqueous dispersion from a polyolefin resin particle without using a freeze-grinding method includes: S110: performing a functional group reaction grafting on the polyolefin resin particle to become a polyolefin resin particle containing an unsaturated carboxylic acid group; S120: putting the polyolefin resin particle containing an unsaturated carboxylic acid group into a co-rotating twin-screw extruder; S130: dissolving a surfactant in water and stirring until dissolved, and then injecting the co-rotating twin-screw extruder via a high-pressure pump; S140: continuously high-shearing the polyolefin resin particle containing an unsaturated carboxylic acid group in water by the co-rotating twin-screw extruder, wherein the polyolefin resin particle containing an unsaturated carboxylic acid group is mixed with water in a molten state; S150: the polyolefin resin particle containing an unsaturated carboxylic acid group forms small particles and is uniformly dispersed in water to form the polyolefin aqueous dispersion; and S160: rapidly cooling the polyolefin aqueous dispersion.

2. The process for microparticulating a polyolefin copolymer according to claim 1, characterized in that, In the step of performing a functional group reaction grafting on the polyolefin resin particle, the polyolefin resin particle is grafted with maleic anhydride or methacrylic acid.

3. The process for microparticulating a polyolefin copolymer as claimed in claim 1, characterized in that, The polyolefin resin particle is an ethylene-propylene copolymer.

4. The process for microparticulating a polyolefin copolymer as claimed in claim 1, characterized in that, The polyolefin aqueous dispersion is polyolefin microparticles dispersed in water, and the particle size is less than 10 microns.

5. The process for microparticulating a polyolefin copolymer as claimed in claim 1, characterized in that, The solid content of the polyolefin in the polyolefin aqueous dispersion is 40-60 wt%, and the viscosity is 300-80,000 centipoise (cP).

6. The process for microparticulating a polyolefin copolymer as claimed in claim 1, characterized in that, In step S140, under the continuous high-shearing environment of the co-rotating twin-screw extruder, the surfactant prevents the formation of a continuous phase, and the particle size becomes smaller and smaller with the shearing of the screw.

7. A method of drying and micronizing a polyolefin copolymer characterized in that, The method for manufacturing a polyolefin copolymer dry powder from a polyolefin resin particle without using a freeze-grinding method includes: S210: performing a functional group reaction grafting on the polyolefin resin particle to become a polyolefin resin particle containing an unsaturated carboxylic acid group; S220: putting the polyolefin resin particle containing an unsaturated carboxylic acid group into a co-rotating twin-screw extruder; S230: dissolving a surfactant in water and stirring until dissolved, and then injecting the co-rotating twin-screw extruder via a high-pressure pump; S240: continuously high-shearing the polyolefin resin particle containing an unsaturated carboxylic acid group in water by the co-rotating twin-screw extruder, wherein the polyolefin resin particle containing an unsaturated carboxylic acid group is mixed with water in a molten state; S250: the polyolefin resin particle containing an unsaturated carboxylic acid group forms small particles and is uniformly dispersed in water to form the polyolefin aqueous dispersion; S260: rapidly cooling the polyolefin aqueous dispersion; and S270: removing the water of the polyolefin aqueous dispersion by a dehydration process to obtain the polyolefin copolymer dry powder.

8. The method of drying and micronizing a polyolefin copolymer of claim 7, wherein, In the step of performing a functional group reaction grafting on the polyolefin resin particle, the polyolefin resin particle is grafted with maleic anhydride or methacrylic acid.

9. The method of drying and micronizing a polyolefin copolymer of claim 7, wherein, The polyolefin resin particle is an ethylene-propylene copolymer.

10. The method of drying and micronizing a polyolefin copolymer of claim 7, wherein, The polyolefin aqueous dispersion is polyolefin microparticles dispersed in water, and the particle size is less than 10 microns.

11. The method of drying and micronizing a polyolefin copolymer of claim 7, wherein, The solid content of the polyolefin in the aqueous polyolefin dispersion is 40-60 wt%, and the viscosity is 300-80,000 centipoise (cP).

12. The method of drying and micronizing a polyolefin copolymer of claim 7, wherein, In step S140, under the continuous high shear environment of the co-rotating twin-screw extruder, the formation of a continuous phase is hindered by the surfactant, and the particle size becomes smaller and smaller with the screw shearing.

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