阅读说明：本技术 阻燃滚塑聚烯烃组合物及其制备方法 (Flame-retardant rotational molding polyolefin composition and preparation method thereof ) 是由 刘少成 张超 张广明 徐素兰 胡军 王晓蕾 于 2018-07-16 设计创作，主要内容包括：本发明涉及一种聚烯烃组合物,具体涉及一种阻燃滚塑聚烯烃组合物及其制备方法。所述的组合物,包括如下原料：聚乙烯100份；阻燃母料10-25份；其中,所述的聚乙烯为乙烯与1-己烯的共聚物,熔体质量流动速率为4-7g/10min,密度为0.930-0.940g/cm<Sup>3</Sup>,重均分子量为7-9万,共聚单体含量>1mol％,连续自成核退火热分级所测重均序列长度分布指数<1.18；所述的阻燃母料由如下原料制成：阻燃剂100份；不饱和硅烷1.0-5.0份；引发剂0.05-0.2份；分散剂0.5-2份；抗氧剂0.5-5份。本发明组合物具有良好的阻燃性与物理机械性能,能够用于滚塑制品的生产；所述的制备方法简单易行。(The invention relates to a polyolefin composition, in particular to a flame-retardant rotational molding polyolefin composition and a preparation method thereof. The composition comprises the following raw materials: 100 parts of polyethylene; 10-25 parts of flame-retardant master batch; wherein the polyethylene is a copolymer of ethylene and 1-hexene, the melt mass flow rate is 4-7g/10min, and the density is 0.930-0.940g/cm 3 Weight average molecular weight of 7-9 ten thousand and comonomer content>1 mol%, continuous self-nucleation annealing thermal grading measured weight average sequenceColumn length distribution index<1.18; the flame-retardant master batch is prepared from the following raw materials: 100 parts of a flame retardant; 1.0-5.0 parts of unsaturated silane; 0.05-0.2 part of initiator; 0.5-2 parts of a dispersing agent; 0.5-5 parts of antioxidant. The composition has good flame retardance and physical and mechanical properties, and can be used for producing rotational molding products; the preparation method is simple and feasible.)

1. A flame retardant rotomoulding polyolefin composition characterized by: the composite material comprises the following raw materials in parts by weight:

100 parts of polyethylene;

10-25 parts of flame-retardant master batch;

wherein the polyethylene is a copolymer of ethylene and 1-hexene, the melt mass flow rate is 4-7g/10min, and the density is 0.930-0.940g/cm³Weight average molecular weight of 7-9 ten thousand and comonomer content>1 mol%, weight average sequence length distribution index measured by continuous self-nucleation annealing thermal classification<1.18；

The flame-retardant master batch is prepared from the following raw materials in parts by weight:

2. the flame retardant rotomolding polyolefin composition according to claim 1, characterized in that: the flame retardant is a mixture of red phosphorus, magnesium hydroxide and aluminum hydroxide, wherein the particle size of the red phosphorus is 800-1500 meshes, the particle size of the magnesium hydroxide is 800-2500 meshes, and the particle size of the aluminum hydroxide is 800-2500 meshes.

3. The flame retardant rotomolding polyolefin composition according to claim 2, characterized in that: the mass ratio of the red phosphorus to the magnesium hydroxide to the aluminum hydroxide is 1: 2: 2.

4. the flame retardant rotomolding polyolefin composition according to claim 1, characterized in that: the unsaturated silane is liquid unsaturated siloxane.

5. The flame retardant rotomolding polyolefin composition according to claim 1, characterized in that: the initiator is a peroxide initiator, and the temperature with the half-life of 1min is 170-270 ℃.

6. The flame retardant rotomolding polyolefin composition according to claim 1, characterized in that: the dispersant is a mixture of methacrylate copolymer containing quaternary ammonium salt groups and microcrystalline paraffin.

7. The flame retardant rotomolding polyolefin composition according to claim 6, characterized in that: the mass ratio of the methacrylate copolymer containing the quaternary ammonium salt group to the microcrystalline paraffin is 1: 1.

8. the flame retardant rotomolding polyolefin composition according to claim 1, characterized in that: the antioxidant is a mixture of hindered phenol antioxidant and phosphite antioxidant.

9. The flame retardant rotomolding polyolefin composition according to claim 8, characterized in that: the mass ratio of the hindered phenol antioxidant to the phosphite antioxidant is 1: 1.

10. a process for the preparation of a flame retardant rotomoulded polyolefin composition according to any one of claims 1 to 9, characterized in that: the method comprises the following steps:

(1) uniformly mixing unsaturated silane, an initiator, a dispersant and an antioxidant to obtain a mixture;

(2) adding a flame retardant into a powder stirrer, then adding the mixture obtained in the step (1), mixing for 5-10min, and discharging for later use to obtain a flame-retardant master batch;

(3) adding polyethylene into a high-speed stirrer, then adding the flame-retardant master batch obtained in the step (2), and stirring at the stirring speed of 600-;

(4) adding the material obtained in the step (3) into a double-screw extruder, melting, plasticizing, extruding and granulating, wherein the length-diameter ratio of the screw of the extruder is not less than 30, and the temperature of the resin melt is 190-.

Technical Field

The invention relates to a polyolefin composition, in particular to a flame-retardant rotational molding polyolefin composition and a preparation method thereof.

Background

In rotational molding, the rotating speed of the mold is relatively low, and the shearing action of the raw materials is almost zero. At such low rotational speeds, rotomoulding feedstocks are required to have higher MFR than blowing, extrusion, etc. feedstocks. Although the product performance can be improved by the modification mode, the heating and cooling rates of the raw materials are slow because the rotational molding process has almost no shear, and any resin and inorganic filler with different melt viscosity and different crystallization temperature from the raw material matrix can have negative effects on the matrix resin. Therefore, the key of the method for improving the performance of the rotational molding product by adopting the modification mode is as follows: the choice of the foreign component and how to resolve the compatibility of the matrix resin with the foreign component.

Just because the rotational molding process has such specificity and the raw materials have higher fluidity, the development is slow in the aspect of rotational molding raw material functionalization, only a small amount of raw materials such as crosslinking and foaming are available at present, and with the increasing related fields of rotational molding products, the rotational molding industry needs to wait for flame retardant raw materials to meet the requirements of certain industries on the flame retardancy of products, such as packaging cases, electric equipment shells and the like, but related researches are few,

the traditional polyolefin flame-retardant mode has the disadvantages of large dosage of added flame retardant, more product performance reduction, no suitability for rotational molding raw materials and no suitability for rotational molding product production.

Patent CN201710160737.3 discloses a halogen-free flame-retardant antistatic polyethylene composition special for rotational molding and a preparation method thereof, the composition is composed of LLDPE, LDPE and halogen-free flame-retardant antistatic master batch, and the halogen-free flame-retardant antistatic master batch is composed of conductive carbon black, expandable graphite, phosphorus-nitrogen expansion type flame retardant, antistatic agent, coupling agent, toughening agent, PE wax and antioxidant. The disclosed composition selects resin which is not suitable for rotational molding and is added with a large amount of inorganic components, so that the strength of the composition is reduced, and rotational molding cannot be carried out, and the technical scheme is different from that of the invention.

Patent CN201710154262.7 discloses a composite material special for military rotational molding ammunition packaging and a preparation method thereof, wherein the composite material consists of LLDPE, HDPE, melamine formaldehyde resin MF, a cross-linking agent, nano reinforcing particles and a nucleating agent. The basic resin of the invention is LLDPE and HDPE, the flame retardant is melamine formaldehyde resin, and the technical scheme is different from the patent.

Disclosure of Invention

The invention aims to provide a flame-retardant rotational molding polyolefin composition which has less flame retardant addition amount, good flame retardance and physical and mechanical properties, and can be used for producing rotational molding products, and the produced rotational molding products have smooth inner and outer surfaces and good plasticization; the invention also provides a preparation method of the composition, which is scientific, reasonable, simple and feasible.

The flame-retardant rotational molding polyolefin composition comprises the following raw materials in parts by weight:

100 parts of polyethylene;

10-25 parts of flame-retardant master batch;

the polyethylene is a copolymer of ethylene and 1-hexene, has good rotational molding performance and grafting performance, has narrow molecular weight distribution, moderate branched chain number and uniform branched chain distribution, and can effectively reduce the content of an initiator used for grafting. The melt mass flow rate is 4-7g/10min, and the density is 0.930-0.940g/cm³Weight average molecular weight of 7-9 ten thousand and comonomer content>1 mol%, weight average sequence length distribution index measured by continuous self-nucleation annealing thermal fractionation (SSA)<1.18；

The flame-retardant master batch is prepared from the following raw materials in parts by weight:

wherein:

the flame retardant is a mixture of red phosphorus, magnesium hydroxide and aluminum hydroxide, wherein the particle size of the red phosphorus is 800-1500 meshes, the particle size of the magnesium hydroxide is 800-2500 meshes, and the particle size of the aluminum hydroxide is 800-2500 meshes.

The mass ratio of the red phosphorus to the magnesium hydroxide to the aluminum hydroxide is 1: 2: 2.

the unsaturated silane is liquid unsaturated siloxane, such as vinyl triethoxysilane, vinyl trimethoxysilane or their mixture at any ratio.

The initiator is a peroxide initiator, the temperature with the half-life of 1min is 170-.

The dispersant is a mixture of methacrylate copolymer containing quaternary ammonium salt groups and microcrystalline paraffin.

The mass ratio of the methacrylate copolymer containing the quaternary ammonium salt group to the microcrystalline paraffin is 1: 1.

the weight average molecular weight of the microcrystalline wax is 350-450.

The antioxidant is a mixture of hindered phenol antioxidant and phosphite antioxidant.

The mass ratio of the hindered phenol antioxidant to the phosphite antioxidant is 1: 1.

the formula can also be added with proper amount of assistants such as ultraviolet absorbent, processing aid, colorant and the like, and the effect of the invention is not influenced.

The preparation method of the flame-retardant rotational molding polyolefin composition comprises the following steps:

(1) uniformly mixing unsaturated silane, an initiator, a dispersant and an antioxidant to obtain a mixture;

(2) adding a flame retardant into a powder stirrer, then adding the mixture obtained in the step (1), mixing at a low speed for 5-10min, and discharging for later use to obtain a flame-retardant master batch;

(3) adding polyethylene into a high-speed stirrer, then adding the flame-retardant master batch obtained in the step (2), and stirring at the stirring speed of 600-;

(4) adding the material obtained in the step (3) into a double-screw extruder, melting, plasticizing, extruding and granulating, wherein the length-diameter ratio of the screw of the extruder is not less than 30, the air exhaust is smooth, and the temperature of the resin melt is 190-.

The invention has the following beneficial effects:

1. the invention improves the dispersion of the flame retardant in the polyethylene resin and the compatibility of the flame retardant and the polyethylene by the technical means of optimizing the resin and prefabricating the flame retardant master batch, thereby ensuring that the composition has good rotational molding performance and excellent flame retardance. The initiator and the unsaturated silane can react with the matrix resin to generate grafted polyethylene in the processing process, so that the compatibility of the flame retardant and the matrix resin is improved; the initiator and the unsaturated silane are premixed with the flame retardant powder, so that the position of a graft can be controlled, the compatibility can be improved, and the using amount of the initiator can be reduced to the greatest extent; the preferable dispersing agent and the proportion can effectively reduce the agglomeration of the flame retardant powder, and are beneficial to the dispersion of the flame retardant in the matrix resin; the synergistic effect of the unsaturated silane and the dispersing agent can greatly reduce the using amount of the dispersing agent and the dispersion of the dispersing agent in the flame retardant powder.

2. The composition has good flame retardance and physical and mechanical properties, and can be used for producing various products with flame retardance by a rotational molding process, and the produced rotational molding products have smooth inner and outer surfaces and good plasticization.

3. The preparation method is simple and easy to implement and is easy to realize.

Detailed Description

The present invention is further described below with reference to examples.