CN115947978B

CN115947978B - Compound agent granulating method with melt finger control for polyolefin

Info

Publication number: CN115947978B
Application number: CN202211601563.7A
Authority: CN
Inventors: 郭骄阳
Original assignee: Jiangsu Jiyi New Material Co ltd
Current assignee: Jiangsu Jiyi New Material Co ltd
Priority date: 2022-12-13
Filing date: 2022-12-13
Publication date: 2023-07-14
Anticipated expiration: 2042-12-13
Also published as: CN115947978A

Abstract

The invention provides a granulating method of a compound agent with melt finger control for polyolefin, which is characterized in that dicumyl peroxide powder is mixed with 3,6, 9-triethyl-3, 6, 9-trimethyl-1, 4, 7-triperoxonane liquid and granulated at normal temperature to obtain compound agent particles; the melt index of polyolefin can be obviously improved, and the fluidity of the polyolefin can be improved; and the degradation of mechanical properties is less. The granulating method is simple and convenient to operate, does not need to be carried out at high temperature, and does not cause peroxide deterioration; the obtained particles have uniform particle size, smooth appearance, no crack and high compressive strength.

Description

Compound agent granulating method with melt finger control for polyolefin

Technical Field

The invention relates to the field of polyolefin additives, in particular to a granulating method of a compound agent with melt finger control for polyolefin.

Background

Polyolefin is the most demanding and most costly product of high molecular materials, and generally comprises polyethylene, polypropylene, etc. Among them, polypropylene has excellent strength, chemical stability and impact resistance, and low production cost, and has been widely used in the fields of home appliances, packaging, pipes, etc., and is one of the most demanded general plastics. In recent years, along with the deep development and application of polypropylene in the military field, the automobile industry and the like, research and development of high-performance polypropylene with good fluidity, quick mold filling, low energy consumption and production efficiency are attracting attention of researchers.

There are generally two methods for preparing high flowability, i.e., high melt index, polyolefins. One is to adopt a novel catalyst, means for regulating the molecular weight and the distribution of polypropylene and the like in the polymerization process of polyolefin to directly polymerize to obtain high-fluidity polyolefin. However, the method has extremely high requirements on the performance of the catalyst system, the control of the reaction conditions and the like, and is difficult to produce polyolefin with narrow relative molecular weight distribution and high fluidity. Another method is a controlled rheology technique, in which a modifier is added to the polyolefin base resin to degrade the polyolefin to some extent, thereby reducing the molecular weight and improving the flowability of the resin. The technology adopts organic peroxide to break the macromolecule chain in the polyolefin resin, so that the molecular weight of the resin is reduced, the distribution is narrowed, the fluidity is improved, and other properties of the material are not obviously affected. Therefore, the technology has simple process and easy reaction control, and thus becomes a research hot spot in recent years.

Organic peroxides generally may be used as chain scission agents in controlled rheology techniques, including solid organic peroxides (e.g., DCP) or liquid organic peroxides (e.g., 2, 5-dimethyl-2, 5-di (t-butylperoxy) hexane (DTBPH)), and the like. Dust-like solid organic peroxide is easy to cause dust to fly, so that the environment pollution is serious, the working condition of operators is poor, the fluidity of products is poor, automatic feeding is easy to block when the product is used, and metering and dosing are inaccurate; the liquid organic peroxide is not easy to be uniformly mixed with the polyolefin resin.

Therefore, it is necessary to develop a chain scission agent for polyolefin in the form of particles to meet the requirement for adjusting the melt index of polyolefin.

Disclosure of Invention

Aiming at the problems in the prior art, the invention provides a granulating method of a compound agent with melt finger control for polyolefin, which can meet the demand of granular polyolefin chain scission agent in the market.

A first aspect of the present invention is to provide a granulating method of a compound agent, comprising:

and uniformly mixing dicumyl peroxide and 3,6, 9-triethyl-3, 6, 9-trimethyl-1, 4, 7-triperoxonane, granulating in a tooth rolling granulator, and sieving the product to remove unshaped solids to obtain the compound agent particles.

In one embodiment, the mass ratio of dicumyl peroxide to 3,6, 9-triethyl-3, 6, 9-trimethyl-1, 4, 7-triperoxonane is 5-9: 5 to 1; preferably, it is 6 to 8:4 to 2, more preferably 6.5 to 7:3.5 to 3.

In one embodiment, the particle size of the compounding agent particles is 2 to 6mm, preferably 3 to 5mm; the compressive strength is greater than 15N, preferably greater than 20N.

In a second aspect, the present invention provides a granule formulation comprising dicumyl peroxide and 3,6, 9-triethyl-3, 6, 9-trimethyl-1, 4, 7-triperoxonane.

Preferably, the granules of the compounding agent are obtained by the granulation process according to the invention.

A third aspect of the present invention is to provide the use of the compounding agent particles for controlling the melt index of a polyolefin.

In one embodiment, the compounding agent particles are used to increase the melt index of the polyolefin.

In one embodiment, the polyolefin is selected from at least one of polyethylene, polypropylene, ethylene propylene copolymer resin.

A third aspect of the present invention is to provide a method of controlling the melt index of a polyolefin, the method comprising:

the polyolefin and the compound agent particles of the invention are uniformly mixed and then are subjected to coextrusion granulation.

Specifically, a certain amount of polyolefin is taken to be added into the compound agent particles, fully and uniformly mixed in a high-speed mixer, and then the mixture is transferred to a double-screw extruder for coextrusion granulation.

In one embodiment, the compounding agent particles are used in an amount of 0.03 to 1%, preferably 0.05 to 0.5%, more preferably 0.1 to 0.3% of the polyolefin.

In one embodiment, the temperature of each zone of the twin screw extruder is 145 to 160 ℃, 165 to 180 ℃, 180 to 190 ℃, 192 to 197 ℃ in sequence.

In one embodiment, the controlling the melt index of the polyolefin comprises increasing the melt index of the polyolefin.

The invention has the beneficial effects that:

the invention provides a granulating method of a compound agent with melt finger control for polyolefin, which has the following advantages:

1. the dicumyl peroxide powder is mixed with 3,6, 9-triethyl-3, 6, 9-trimethyl-1, 4, 7-triperoxonane liquid and granulated at normal temperature, so that peroxide deterioration and discoloration caused by high-temperature granulation are avoided, and the effect and the performance of polyolefin are influenced during use.

2. The dicumyl peroxide and 3,6, 9-triethyl-3, 6, 9-trimethyl-1, 4, 7-triperoxynonane are compounded and granulated in a specific proportion, and good balance is achieved between two effects of breaking long-chain polyolefin and crosslinking short-chain polyolefin, and the synergistic effect of the dicumyl peroxide and the 3,6, 9-triethyl-3, 6, 9-trimethyl-1, 4, 7-triperoxynonane ensures that the modified polyolefin has obviously increased melt index and greatly improves the fluidity; the degradation of mechanical properties is less.

3. Dicumyl peroxide and 3,6, 9-triethyl-3, 6, 9-trimethyl-1, 4, 7-triperoxonane have poor effects when used alone, and even if used in a compound way, the effects are affected due to uneven dispersion of a chain scission agent and the like when no granulation is carried out.

4. The granulating method of the invention is simple and convenient to operate, does not need to be carried out at high temperature, and does not cause peroxide deterioration. The obtained particles have uniform particle size, smooth appearance, no crack and high compressive strength.

In a word, the granulating method of the invention can obtain the polyolefin compound agent with good performance.

Drawings

FIG. 1 shows the melt index of the polyolefin according to the melt index of the examples and comparative examples with different amounts of chain scission agent;

FIG. 2 shows the change in tensile strength of the polyolefin according to the amount of the chain-scission agent used in the examples and comparative examples;

FIG. 3 shows the impact strength of the polyolefin according to the examples and comparative examples with different amounts of chain scission agent.

Detailed Description

Hereinafter, preferred examples of the invention will be described in detail. The examples are presented for better understanding of the invention and are not intended to limit the invention to the examples. Insubstantial modifications and adaptations of the embodiments in accordance with the summary of the invention remain within the scope of the invention.

The experimental methods in the following examples are conventional methods unless otherwise specified. The specific techniques or conditions are not identified in the examples and are described in the literature in this field or are carried out in accordance with the product specifications.

Preparation example 1:

the mass ratio is 6.5:3.5 dicumyl peroxide (DCP) and 3,6, 9-triethyl-3, 6, 9-trimethyl-1, 4, 7-triperoxonane (301) are uniformly mixed, and are granulated in a tooth rolling granulator, and the product is sieved to remove unshaped solids, so as to obtain compound granules with the diameter of 3-4 mm; the appearance is smooth and has no crack, and the compressive strength reaches 21.2N.

Preparation example 2:

the mass ratio is 7:3 dicumyl peroxide (DCP) and 3,6, 9-triethyl-3, 6, 9-trimethyl-1, 4, 7-triperoxonane (301) are uniformly mixed, and are granulated in a tooth rolling granulator, and the product is sieved to remove unshaped solids, so as to obtain compound agent particles with the diameter of 3-4 mm. The appearance is smooth and has no crack, and the compressive strength reaches 23.4N.

Examples 1-2 and comparative examples 1-3:

taking a certain amount of polypropylene (brand 230, purchased from the Ming's petrochemical Shihua Co., ltd.), adding different amounts of chain scission agents respectively, fully mixing in a high-speed mixer for 10 min, discharging, transferring to a double-screw extruder, setting the temperatures of all areas of the double-screw extruder to be 155 ℃, 175 ℃, 185 ℃, 195 ℃ and 195 ℃ in sequence, extruding and granulating, and preparing the granulated particles into standard experimental sample bars by an injection molding machine.

The chain scission agents of the examples and comparative examples are shown in the following table:

performance test:

1) Melt index determination

According to GB/T3682-2018 determination of melt Mass Flow Rate (MFR) and melt volume flow Rate (MVR) of plastics thermoplastics, a volumetric melt index tester is used to determine the melt index of a sample of material under the following test conditions: the temperature is 190 ℃ and the weight is 2.16kg.

2) Mechanical property test

According to GB/T1040.1-2018 general rule of measuring tensile properties of plastics, section 1 and GB/T1040.2-2018 test conditions of measuring tensile properties of plastics, section 2, molded and extruded plastics, a universal tensile tester is used for measuring tensile strength of a material sample. According to GB/T1843-2008 "determination of impact Strength of Plastic cantilever beam", an impact tester is used to determine the impact strength of a material sample.

The results are shown in FIGS. 1-3. As can be seen from fig. 1, for each of the chain scission agents, the melt index of polypropylene changes approximately linearly as the content thereof in the polypropylene resin increases, i.e., as the amount of the chain scission agent increases, the melt index of polypropylene becomes larger and the flowability increases; whereas examples 1 and 2 according to the invention show a more pronounced tendency to increase the melt index due to the use of the compounded granules according to the invention. As can be seen from fig. 2, each chain scission agent gives rise to a post-rising decrease in tensile strength of polypropylene in tensile strength; in the case of the impact strength of FIG. 3, the impact strength of polypropylene was reduced by the chain scission agent except for the impact strength of example 2 at a low concentration. This is because peroxide chain scission agents not only can cause chain scission of long-chain polypropylene, but also have the effect of crosslinking short polypropylene chains, the two effects being mutually affected depending on the type and amount of the chain scission agent. The chain scission agent of the invention has less deterioration of mechanical properties of polypropylene while improving the melt index, while the chain scission agents of comparative examples 1-3 have poorer effect of improving the melt index and more obvious deterioration of mechanical properties of polypropylene resin.

Finally, it is noted that the above-mentioned preferred embodiments illustrate rather than limit the invention, and that, although the invention has been described in detail with reference to the above-mentioned preferred embodiments, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the scope of the invention as defined by the appended claims.

Claims

1. A method of granulating a compounding agent, comprising:

uniformly mixing dicumyl peroxide and 3,6, 9-triethyl-3, 6, 9-trimethyl-1, 4, 7-triperoxonane, granulating in a tooth rolling granulator, and sieving the product to remove unshaped solids to obtain compound agent particles;

wherein the mass ratio of the dicumyl peroxide to the 3,6, 9-triethyl-3, 6, 9-trimethyl-1, 4, 7-triperoxonane is 6.5-7: 3.5 to 3;

the particle size of the compound agent particles is 3-5 mm; the compressive strength is greater than 20N.

2. A granule of a compound formulation obtainable by the granulation process according to claim 1.

3. Use of the compounding agent particles of claim 2 for controlling the melt index of a polyolefin.

4. Use according to claim 3, wherein the compounding agent particles are used to increase the melt index of a polyolefin.

5. The use according to claim 3, wherein the polyolefin is selected from at least one of polyethylene, polypropylene, ethylene propylene copolymer resin.

6. A method of controlling the melt index of a polyolefin, the method comprising:

blending polyolefin with the compounding agent granules according to claim 2, and then carrying out coextrusion granulation.

7. The method of claim 6, wherein the compounding agent particles are used in an amount of 0.03 to 1% of the polyolefin.

8. The method of claim 7, wherein the compounding agent particles are used in an amount of 0.05 to 0.5% of the polyolefin.

9. The method of claim 7, wherein the compounding agent particles are used in an amount of 0.1 to 0.3% of the polyolefin.