阅读说明：本技术 聚乙烯组合物及其制备方法 (Polyethylene composition and preparation method thereof ) 是由 刘少成 王栓 张超 陈宁 张广明 郭其 徐素兰 张涛 王跃平 胡军 于 2020-06-22 设计创作，主要内容包括：本发明涉及一种聚乙烯组合物及其制备方法,属于高分子化合物的组合物技术领域。所述的聚乙烯组合物,包括如下质量份数的原料：a聚乙烯100份；b易研磨母料0.2-5份；其中,所述的b易研磨母料由如下质量份数的原料制成：a聚乙烯100份、无机粉体25份、润滑剂0.5-5份、偶联剂1-5份；所述的无机粉体为层状膨润土、层状云母粉或层状硅酸盐粉体中的一种或几种。本发明所述的聚乙烯组合物提高了材料的研磨性,能够有效减少滚塑成型用聚乙烯粉体中脱尾及不规则粒子数量,提高了粉料的流动性,且保证了材料强度、冲击性能,所生产的滚塑制品,内外表面光滑,塑化时间明显缩短；其制备方法,科学合理、简单易行。(The invention relates to a polyethylene composition and a preparation method thereof, belonging to the technical field of compositions of high molecular compounds. The polyethylene composition comprises the following raw materials in parts by weight: 100 parts of polyethylene; b, 0.2-5 parts of easy-grinding master batch; the b easily-grinded master batch is prepared from the following raw materials in parts by mass: 100 parts of polyethylene, 25 parts of inorganic powder, 0.5-5 parts of lubricant and 1-5 parts of coupling agent; the inorganic powder is one or more of layered bentonite, layered mica powder or layered silicate powder. The polyethylene composition improves the grindability of materials, can effectively reduce the quantity of tail-removing and irregular particles in polyethylene powder for rotational molding, improves the fluidity of the powder, ensures the strength and impact property of the materials, and produces rotational molding products with smooth inner and outer surfaces and obviously shortened plasticizing time; the preparation method is scientific, reasonable, simple and feasible.)

1. A polyethylene composition characterized by: the composite material comprises the following raw materials in parts by weight:

100 parts of polyethylene;

b, 0.2-5 parts of easy-grinding master batch;

the b easily-grinded master batch is prepared from the following raw materials in parts by mass: 100 parts of polyethylene, 25 parts of inorganic powder, 0.5-5 parts of lubricant and 1-5 parts of coupling agent;

the inorganic powder is one or more of layered bentonite, layered mica powder or layered silicate powder.

2. The polyethylene composition according to claim 1, characterized in that: the polyethylene a is polyethylene for high-density rotational molding or metallocene rotational molding.

3. The polyethylene composition according to claim 2, characterized in that: the melt mass flow rate of the polyethylene for high-density rotational molding is2-5g/10min, and density of 0.945-0.955g/cm³。

4. The polyethylene composition according to claim 2, characterized in that: the melt mass flow rate of the polyethylene for metallocene rotational moulding is 3-6g/10min, and the density is 0.930-0.940g/cm³。

5. The polyethylene composition according to claim 1, characterized in that: the lubricant is one or more of polyethylene wax, liquid paraffin or zinc stearate.

6. The polyethylene composition according to claim 1, characterized in that: the coupling agent is a silane coupling agent.

7. The polyethylene composition according to claim 1, characterized in that: the polyethylene composition also comprises an additive, wherein the additive is one or more of a main antioxidant, an auxiliary antioxidant, a light stabilizer, an antistatic agent, an antibacterial agent, a color enhancer or a pigment.

8. A process for producing a polyethylene composition according to any of claims 1 to 7, characterized in that: the method comprises the following steps:

(1) b, preparing an easily-ground master batch: heating the inorganic powder to 120 ℃ below zero, adding the coupling agent, and stirring for 40-60min at the stirring speed of 300-; cooling to 20-40 ℃, adding polyethylene and lubricant a, stirring for 5-10min at a stirring speed of 600-; discharging, adding into a double-screw extruder, melting, plasticizing, extruding and granulating to obtain a master batch b easy to grind;

(2) and (3) adding the easily-ground master batch b into the polyethylene a, uniformly mixing, extruding by using a double-screw extruder, and granulating.

9. The method of producing a polyethylene composition according to claim 8, characterized in that: in the step (1), the double-screw extruder has a screw length-diameter ratio of not less than 30, smooth exhaust and a resin melt temperature of 170-200 ℃.

10. The method of producing a polyethylene composition according to claim 8, characterized in that: in the step (2), the double-screw extruder has a screw length-diameter ratio of not less than 28, smooth air exhaust and a resin melt temperature of 170-.

Technical Field

The invention relates to a polyethylene composition and a preparation method thereof, belonging to the technical field of compositions of high molecular compounds.

Background

Rotational molding is generally performed by adding ground polyethylene powder into a mold, melting and uniformly adhering the polyethylene powder to the inner surface of the mold under the action of gravity and heat, keeping the raw materials in a molten state for a certain time to reduce bubbles generated when the raw materials are melted and adhered together, cooling and shaping, and then demolding. The article is capable of perfectly replicating the shape of the inner surface of the mold and allows the addition of various inserts, designed in various configurations.

The rotational molding process is carried out under extremely low stress, so that the requirements on the quality of the grinding powder are high, the optimal powder particle shape is spherical and has no tail shedding, and the gaps among particles can be effectively reduced. The tail is removed more, the particles have irregular shapes, more bubbles are introduced into the wall of a product during rotational molding, more processing time is needed for removing the bubbles, and the processing efficiency is seriously reduced.

At present, there is no document or patent concerning the removal of the tail of the abrasive powder.

Disclosure of Invention

The technical problem to be solved by the invention is as follows: the polyethylene composition can effectively reduce the tail shedding phenomenon of polyethylene grinding powder, particularly high-density polyethylene and metallocene polyethylene grinding powder, improve the grinding efficiency of rotational molding polyethylene, improve the flowability of the powder and effectively reduce the rotational molding processing time; the invention also provides a preparation method of the composition, which is scientific, reasonable, simple and feasible.

The polyethylene composition comprises the following raw materials in parts by weight:

100 parts of polyethylene;

b, 0.2-5 parts of easy-grinding master batch;

the b easily-grinded master batch is prepared from the following raw materials in parts by mass: 100 parts of polyethylene, 25 parts of inorganic powder, 0.5-5 parts of lubricant and 1-5 parts of coupling agent;

the inorganic powder is lamellar inorganic powder, preferably one or more of lamellar bentonite, lamellar mica powder or lamellar silicate powder. After the inorganic powder with a layered structure is added, the resin is ground, the layers of the powder are destroyed to form sharp edges and corners, the friction effect between the grinding disc and the resin is increased, the particle shape of the ground powder is favorably controlled, the particle tail removal is reduced, and partial tail removal can be eliminated through the friction with the grinding disc.

The polyethylene a is polyethylene for high-density rotational molding or metallocene rotational molding. The melt Mass Flow Rate (MFR) of the polyethylene for high-density rotational molding_2.16kg) The load is 2-5g/10min, and the test is carried out according to GB/T3682.16 kg; the density is 0.945-0.955g/cm³The test was carried out according to GB/T1033.2, using the D method, after boiling for 30 minutes. The melt Mass Flow Rate (MFR) of the metallocene polyethylene for rotational moulding_2.16kg) The load is 3-6g/10min, and the test is carried out according to GB/T3682, and the load is 2.16 kg; the density is 0.930-0.940g/cm³The test was carried out according to GB/T1033.2, using the D method, after boiling for 30 minutes.

The lubricant is a low molecular substance with a lubricating effect, and is preferably one or more of polyethylene wax, liquid paraffin or zinc stearate.

The coupling agent is a silane coupling agent.

The polyethylene composition of the invention may also comprise other components, such as additives. The additive is one or more of a main antioxidant, an auxiliary antioxidant, a light stabilizer, an antistatic agent, an antibacterial agent, a color enhancer or a pigment. The polyethylene composition of the invention may contain any number of additives. For example, in order to prevent polyethylene from oxidative decomposition, one or more antioxidants with content of 0-0.5% can be added, wherein the antioxidant can be hindered phenol antioxidant, phosphite antioxidant, or mixture of both at any ratio.

The process for producing the polyethylene composition according to the instant invention comprises the steps of:

(1) b, preparing an easily-ground master batch: heating the inorganic powder to 120 ℃ below zero, adding the coupling agent, and stirring for 40-60min at the stirring speed of 300-; cooling to 20-40 ℃, adding polyethylene and lubricant a, stirring for 5-10min at a stirring speed of 600-; discharging, adding into a double-screw extruder, melting, plasticizing, extruding and granulating to obtain a master batch b easy to grind;

(2) and (3) adding the easily-ground master batch b into the polyethylene a, uniformly mixing, extruding by using a double-screw extruder, and granulating.

Wherein:

in the step (1), the double-screw extruder has a screw length-diameter ratio of not less than 30, smooth exhaust and a resin melt temperature of 170-200 ℃.

In the step (2), the double-screw extruder has a screw length-diameter ratio of not less than 28, smooth air exhaust and a resin melt temperature of 170-.

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

1. the invention provides a composition beneficial to grinding rotational molding polyethylene, which improves the grinding performance of materials, can effectively reduce the number of tail removal and irregular particles in polyethylene powder for rotational molding, improves the fluidity of the powder, ensures the strength and impact property of the materials, and ensures that the produced rotational molding products have smooth inner and outer surfaces and obviously shortened plasticizing time.

2. The preparation method is scientific, reasonable, simple and feasible.

Detailed Description

The present invention will be further described with reference to the following detailed description, but is not limited thereto.

Raw materials used in the examples:

the polyethylene 1 used in the examples was PE E502, MFR 2.8g/10min, density 0.951g/cm³Commercially available.

The polyethylene 2 used in the examples was mPE R335HL, MFR 5.4g/10min, density 0.934g/cm³Commercially available.

The inorganic powder used in the examples was layered bentonite with an average particle size of 600 mesh, calcium-based, commercially available.

The lubricant used in the examples was zinc stearate, commercially available.

The coupling agent used in the examples was a silane coupling agent KH550, commercially available.

The inorganic powder used in the comparative example was spherical calcium carbonate having an average particle size of 1200 mesh and commercially available.

The execution standard is as follows:

melt Mass Flow Rate (MFR): the test is carried out according to GB/T3682, the test temperature is 190 ℃, and the load is 2.16 kg.

Density: the test was carried out according to GB/T1033.2.

Tensile property: the test specimens were compression-moulded and tested according to GB/T1040.2, type I bars, with a tensile speed of 50 mm/min.

Impact strength of the simply supported beam notch: the specimens were compression molded and tested according to GB/T1043.

Powder flowability: the test is carried out according to GB/T21060, the raw material is 100g, an a-type funnel is selected, and the outlet size is 1.5 cm.

Bubble free time of the product wall: and rotationally molding the ground powder into a square box with the wall thickness of 4mm by adopting an FD1-1000 rotational molding machine, wherein the heating temperature is 270 ℃, and the rotational molding time is set to be 40min, 45min, 50min and 55min for observing whether bubbles exist on the wall of the product.

Easy-to-grind masterbatch 1 preparation

(1) Heating 100g of bentonite to 120 ℃, adding 6g of KH550, stirring for 50min, and stirring at the rotating speed of 600 r/min;

(2) cooling the powder (1) to 40 ℃, adding 400g a polyethylene 1 and 8g zinc stearate in proportion, mixing for 5min at a low speed, stirring at the rotating speed of 1000 rpm, and discharging;

(3) and (3) adding the uniformly mixed material obtained in the step (2) into a double-screw extruder, and carrying out melting, plasticizing, extruding and granulating to obtain the easily-ground master batch 1. The length-diameter ratio of the screw of the extruder is 33, the air is exhausted, and the temperature of the resin melt is 190 ℃.

Examples 1 to 4 preparation

And (3) adding the easily-ground master batch 1 into the polyethylene 1 a in proportion, fully mixing, extruding by using a double-screw extruder, and granulating. The extruder screw length was 28 deg.C, vented, and the resin melt temperature was 190 deg.C.

The compositions of examples 1-4 are shown in Table 1.

Easy-to-grind masterbatch 2 preparation

(1) Heating 100g of bentonite to 100 ℃, adding 8g of KH550, stirring for 60min, and stirring at the rotating speed of 800 r/min;

(2) cooling the powder (1) to 40 ℃, adding 400g a polyethylene 2 and 4g zinc stearate in proportion, mixing at low speed for 8min, stirring at the rotating speed of 600 rpm, and discharging;

(3) and (3) adding the uniformly mixed material obtained in the step (2) into a double-screw extruder, and carrying out melting, plasticizing, extruding and granulating to obtain the easily-ground master batch 2. The length-diameter ratio of the screw of the extruder is 33, the air is exhausted, and the temperature of the resin melt is 180 ℃.

Examples 5 to 6 preparation

And (3) adding the easily-ground master batch 2 into the polyethylene 2 a in proportion, fully mixing, extruding by using a double-screw extruder, and granulating. The extruder screw length was 28 deg.C, vented, and the resin melt temperature was 180 deg.C.

The compositions of examples 5-6 are shown in Table 1.

Comparative examples 1 to 2 preparation

Comparative examples 1-2 are pure polyethylene resins. Comparative example 1 is a polyethylene 1 and comparative example 2 is a polyethylene 2.

Comparative examples 3 to 6 preparation

Comparative examples 3 to 6 were prepared by directly adding each component in proportion to polyethylene resin, sufficiently mixing, extruding with a twin-screw extruder, and granulating. The extruder screw length was 28 deg.C, vented, and the resin melt temperature was 180 deg.C.

The composition ratios of comparative examples 3-6 are shown in Table 2.

Comparative example 7 preparation

(1) Heating 100g of calcium carbonate to 100 ℃, adding 8g of KH550, stirring for 60min, and stirring at the rotating speed of 800 r/min; (2) cooling the powder (1) to 40 ℃, adding 400g of polyethylene 2 and 4g of zinc stearate in proportion, mixing at a low speed for 8min, stirring at a rotating speed of 600 rpm, and discharging; (3) and (3) adding the uniformly mixed material obtained in the step (2) into a double-screw extruder, and carrying out melting, plasticizing, extruding and granulating to obtain the calcium carbonate master batch. The length-diameter ratio of the screw of the extruder is 33, the air is exhausted, and the temperature of the resin melt is 190 ℃.

The composition was prepared as in examples 1-4.

The properties of the compositions prepared in examples 1 to 6 are shown in Table 1, and the properties of the compositions prepared in comparative examples 1 to 7 are shown in Table 2.

TABLE 1 compositions proportions and Properties of the examples

TABLE 2 comparative example composition ratio and Properties

It can be seen from the data of the examples that after the master batch is prepared, compared with the master batch directly added with the auxiliary agent, the tensile strength, tensile breaking strain, impact strength and powder flowability of the raw materials are improved to a great extent, and the rotational molding time can be reduced by 10-15 minutes according to different base resins. The non-layered calcium carbonate is added into resin after being treated according to the process of the master batch of the embodiment, so that the resin performance is reduced, and no contribution is made to grinding.

Of course, the foregoing is only a preferred embodiment of the invention and should not be taken as limiting the scope of the embodiments of the invention. The present invention is not limited to the above examples, and equivalent changes and modifications made by those skilled in the art within the spirit and scope of the present invention should be construed as being included in the scope of the present invention.