1. The flame-retardant radiation cross-linked polyethylene foam material is characterized by comprising the following components in parts by weight:

35-45 parts of low-density polyethylene

5-15 parts of linear low-density polyethylene

5-15 parts of high-density polyethylene

10-15 parts of polyolefin elastomer

2-10 parts of foaming agent

2-10 parts of foaming auxiliary agent

0.5-5 parts of cross-linking agent

5-20 parts of decabromodiphenylethane

1-10 parts of antimony trioxide

4-8 parts of magnesium hydroxide

1-10 parts of talcum powder

1-5 parts of a compatibilizer;

wherein, under the condition of 190 ℃ multiplied by 2.16kg, the melt index of the low-density polyethylene is 1-3g/10min, the melt index of the linear low-density polyethylene is 2-6g/10min, and the melt index of the high-density polyethylene is 7-22g/10 min.

2. The foamed flame-retardant radiation crosslinked polyethylene material of claim 1, wherein the polyolefin elastomer is a copolymer of ethylene and octene, and the octene content is 20-30%, and the density is 0.865-0.895g/cm³。

3. The flame retardant radiation crosslinked polyethylene foam material according to claim 1, wherein said blowing agent is azodicarbonamide, diisopropyl azodicarboxylate or azobisisobutyronitrile.

4. The flame-retardant radiation crosslinked polyethylene foam material according to claim 1, wherein the foaming auxiliary agent is one or two of zinc oxide and stearic acid.

5. The flame-retardant radiation crosslinked polyethylene foam material according to claim 4, wherein the mass ratio of the zinc oxide to the stearic acid in the compound is 1: 1-10.

6. The flame retardant radiation crosslinked polyethylene foam material according to claim 1, wherein the crosslinking agent is one or more of TAIC, TAC and TMPTMA.

7. The flame-retardant radiation crosslinked polyethylene foam material as claimed in claim 1, wherein the compatibilizer is ethylene-octene copolymer grafted maleic anhydride, and the grafting ratio is 0.8-1.5%.

8. The method for preparing the flame-retardant radiation crosslinked polyethylene foam material according to any one of claims 1 to 7, characterized by comprising the steps of:

s1: uniformly mixing low-density polyethylene, linear low-density polyethylene, high-density polyethylene, polyolefin elastomer, foaming agent, foaming auxiliary agent, crosslinking agent and compatibilizer in a banbury mixer, adding decabromodiphenylethane, antimony trioxide, magnesium hydroxide and talcum powder, and heating and banburying;

s2: adding the banburying materials in the step S1 into an extruder, and extruding to obtain a master slice;

s3: irradiating the master slice obtained in the step S2 according to the irradiation dose of 6-14Mrad to obtain a cross-linked sheet;

s4: and (4) heating and foaming the crosslinked sheet obtained in the step S3 to obtain the flame-retardant irradiation crosslinked polyethylene foam material.

9. The method for preparing the flame-retardant radiation crosslinked polyethylene foam material according to claim 8, wherein in step S1, the temperature for heating and banburying is 120-130 ℃.

10. The method for preparing the flame-retardant radiation crosslinked polyethylene foam material according to claim 8, wherein in the step S4, the temperature of the heating foaming is 230-260 ℃.

Background

The polyethylene foam material is plastic which contains countless micropores in the whole body, has the advantages of low density, heat insulation, sound absorption, shock resistance and the like due to the existence of gas phase, is widely used in various fields of automobiles, navigation, buildings, heat insulation, packaging, civil use and the like, and has good market prospect due to the characteristics of low cost, good performance, wide application and the like.

Adding flame retardant into polyethylene foam material is the most common method for improving the flame retardant property. Most of the existing flame retardants are halogen-containing flame retardants, which not only remarkably improves the flame retardant effect of the polyethylene foam material, but also causes the problems of toxic gas release during material combustion, secondary damage to human bodies and the like, so that the use is limited. In addition, the flame retardant has many types and different performances, and a single flame retardant has poor flame retardant effect and cannot meet the actual demand, so the research on a high-performance compound flame retardant system is more and more concerned in recent years.

Chinese patent publication No. CN104592554A discloses a magnesium hydroxide compounded flame retardant crosslinked polyethylene foam plastic composite material, which uses a compounded flame retardant system mainly containing magnesium hydroxide to avoid the problem that a halogen-containing flame retardant system generates toxic gas during combustion to harm human health, but the scheme is not perfect and still has the following two problems: 1. the modified nano magnesium hydroxide needs to be prepared in advance, and the process flow is complex; 2. the comprehensive performance of the prepared flame-retardant crosslinked polyethylene foam plastic is poorer than that of a radiation crosslinked product without adopting a radiation crosslinking technology, and the high-temperature resistant grade is lower.

Disclosure of Invention

The technical problem to be solved by the invention is to provide a flame-retardant irradiation crosslinking polyethylene foam material and a preparation method thereof, the preparation process of the flame-retardant irradiation crosslinking polyethylene foam material is simple, and the obtained product has the advantages of good size stability, cell compactness and uniformity, no toxicity, no peculiar smell and excellent flame retardant property.

In order to solve the technical problems, the invention provides the following technical scheme:

the invention provides a flame-retardant irradiation crosslinked polyethylene foam material which comprises the following components in parts by weight:

35-45 parts of low-density polyethylene

5-15 parts of linear low-density polyethylene

5-15 parts of high-density polyethylene

10-15 parts of polyolefin elastomer

2-10 parts of foaming agent

2-10 parts of foaming auxiliary agent

0.5-5 parts of cross-linking agent

5-20 parts of decabromodiphenylethane

1-10 parts of antimony trioxide

4-8 parts of magnesium hydroxide

1-10 parts of talcum powder

1-5 parts of a compatibilizer;

wherein, under the condition of 190 ℃ multiplied by 2.16kg, the melt index of the low-density polyethylene is 1-3g/10min, the melt index of the linear low-density polyethylene is 2-6g/10min, and the melt index of the high-density polyethylene is 7-22g/10 min.

In the invention, in order to ensure the tensile elasticity of the irradiation crosslinking polyethylene foam material after molding, the low-density polyethylene, the linear low-density polyethylene and the high-density polyethylene are selected to be matched for use, so that the good processing performance can be ensured, the good foaming state can be maintained, and meanwhile, the quality of the irradiation crosslinking polyethylene foam material is higher.

Further, the polyolefin elastomer (POE) is a copolymer of ethylene and octene, wherein the content of octene is 20-30%, and the density is 0.865-0.895g/cm³Further preferably, the density is 0.870 to 0.885g/cm³. The addition of POE is favorable for increasing the elasticity of the material, absorbing the addition of flame retardant filling with high proportion, simultaneously endowing the product with better compression set recovery and wider applicable temperature range of the product, and is favorable for maintaining better mechanical property and good processability of the product.

Further, the foaming agent is azodicarbonamide, diisopropyl azodicarboxylate, or azobisisobutyronitrile. Preferably, the blowing agent is azodicarbonamide. The content of the foaming agent can be adjusted according to the different foaming ratios, and the smaller the foaming ratio is, the smaller the addition amount of the foaming agent is.

Further, the foaming auxiliary agent is one or two of zinc oxide and stearic acid. Preferably, the mass ratio of the zinc oxide to the stearic acid in the compound is 1: 1-10.

Further, the crosslinking agent is one or more of triallyl isocyanurate (TAIC), triallyl cyanurate (TAC), and trimethylolpropane trimethacrylate (TMPTMA). In the invention, the cross-linking agent is added, so that the irradiation dose and the irradiation cost are reduced, and the damage of irradiation to the material performance is reduced.

Further, the compatibilizer is ethylene-octene copolymer grafted maleic anhydride, and the grafting rate is 0.8-1.5%, preferably 1.2%. The addition of the compatibilizer improves the compatibility among the polyolefin elastomer, the polyethylene and the flame retardant and improves the performance of the foam material.

The invention also provides a preparation method of the flame-retardant irradiation crosslinked polyethylene foam material, which comprises the following steps:

s1: uniformly mixing low-density polyethylene, linear low-density polyethylene, high-density polyethylene, polyolefin elastomer, foaming agent, foaming auxiliary agent, crosslinking agent and compatibilizer in a banbury mixer, adding decabromodiphenylethane, antimony trioxide, magnesium hydroxide and talcum powder, and heating and banburying;

s2: adding the banburying materials in the step S1 into an extruder, and extruding to obtain a master slice;

s3: irradiating the master slice obtained in the step S2 according to the irradiation dose of 6-14Mrad to obtain a cross-linked sheet;

s4: and (4) heating and foaming the crosslinked sheet obtained in the step S3 to obtain the flame-retardant irradiation crosslinked polyethylene foam material.

Further, in step S1, the heating and banburying temperature is 120-130 ℃.

Further, in step S4, the heating and foaming temperature is 230-260 ℃.

The flame-retardant irradiation crosslinking polyethylene foam material can be prepared into a master slice to be crosslinked by molding the raw materials in one step, and the master slice is subjected to radiation crosslinking and high-temperature foaming to obtain a flame-retardant irradiation crosslinking polyethylene foam material molded product. Compared with the irradiation crosslinking polyethylene foaming material in the prior art, the preparation method of the invention does not need to prepare master batches, and the master batches are obtained by one-step forming, so that the granulating and re-extruding process is simplified, the processing cost is saved, and the production efficiency is improved.

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

1. according to the flame-retardant irradiation crosslinking polyethylene foam material, the low-density polyethylene, the linear low-density polyethylene and the high-density polyethylene with different melt indexes are selected and matched, so that the good processing performance can be guaranteed, the good foaming state can be maintained, and meanwhile, the quality of the irradiation crosslinking polyethylene foam material is higher.

2. Decabromodiphenylethane is a novel plastic flame retardant, has good flame retardant effect, high thermal stability, small influence on the physical properties of flame retardant materials and low toxicity, and is widely applied to various thermosetting and thermoplastic plastics. Antimony trioxide is used in combination with decabromodiphenylethane, which can promote decomposition of decabromodiphenylethane to release nonflammable gas and form a gas isolation layer to play a flame retardant role. In addition, the magnesium hydroxide can absorb smoke and harmful gases generated when high polymer materials such as plastics, rubber and the like are burnt, and the flame-retardant and smoke-suppression effects of the materials are further improved. The decabromodiphenylethane, the antimony trioxide and the magnesium hydroxide are compounded into the flame retardant, so that the flame retardant is high-temperature resistant, the flame retardance of the product can be remarkably improved, the addition amount is relatively small, and the influence on other properties of the product is small.

3. The flame-retardant irradiation cross-linked polyethylene foaming material disclosed by the invention is simple in production process, and the obtained product is good in size stability, cell compactness and uniformity, non-toxic, free of peculiar smell and excellent in flame retardant property.

Drawings

FIG. 1 is a schematic diagram of a preparation process of the flame-retardant irradiation crosslinked polyethylene foam material of the present invention.

Detailed Description

The present invention is further described below in conjunction with the following figures and specific examples so that those skilled in the art may better understand the present invention and practice it, but the examples are not intended to limit the present invention.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used in the description of the invention herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.

The experimental methods used in the following examples are conventional methods unless otherwise specified, and materials, reagents and the like used therein are commercially available without otherwise specified.

Examples 1 to 3: preparation of flame-retardant irradiation crosslinked polyethylene foam material

The embodiment provides an anti-static irradiation crosslinked polyethylene foam material and a preparation method thereof, and the preparation method comprises the following steps:

the method comprises the following steps: mixing material

According to the formula of table 1, the low density polyethylene, the linear low density polyethylene, the high density polyethylene, the polyolefin elastomer, the foaming agent, the foaming auxiliary agent, the crosslinking agent and the compatibilizer are firstly stirred for 1 minute in an internal mixer, are uniformly mixed, are added with decabromodiphenylethane, antimony trioxide, magnesium hydroxide and talcum powder, and are heated and internally mixed to 120 ℃.

Step two: one-step forming to obtain master slice

And D, directly putting the internally mixed material in the step I into a main feeding hopper of a single-screw extruder, installing a die head meeting the requirement at the end part of the extruder, and extruding the master slice.

Step three: crosslinking by irradiation

And (4) irradiating the master slice obtained in the step two according to the irradiation dose of 12Mrad to obtain the crosslinked sheet.

Step four: high temperature foaming

And (3) carrying out high-temperature foaming on the crosslinked sheet obtained in the third step in a foaming furnace, wherein the foaming ratio is 20 times, and obtaining the flame-retardant foaming material molding product with the thickness of 3 mm.

TABLE 1 formulation of flame retardant radiation crosslinked polyethylene foam of examples 1-3

Components	Example 1	Example 2	Example 3	Comparative example 1	Comparative example 2	Comparative example 3
							Low density polyethylene	35	40	45	40	40	40
Linear low density polyethylene	10	10	15	10	10	10
							High density polyethylene	10	10	15	10	10	10
Polyolefin elastomer	5	5	8	5	5	5
							Foaming agent	2	5	8	5	5	5
Foaming aid	4	10	8	10	10	10
							Crosslinking agent	2.5	2.5	3	2.5	2.5	2.5
Decabromodiphenylethane	5	5	8	6	6	0
							Antimony trioxide	2	3	3	6	0	6
Magnesium hydroxide	2	4	5	0	6	6
							Talcum powder	6	6	8	6	6	6
Compatibilizer	3	3	3	3	3	3

In the above examples and comparative examples:

in example 1:

the melt flow rate MI of the low density polyethylene =1.5g/10min, the melt flow rate MI of the linear low density polyethylene =2.5g/10min, the melt flow rate MI of the high density polyethylene =8.6g/10 min; the foaming auxiliary agent is stearic acid; the cross-linking agent is TAIC; the compatibilizer is ethylene-octene copolymer grafted maleic anhydride, and the grafting rate is 1.2 percent.

In example 2:

the melt flow rate MI of the low density polyethylene =2.0g/10min, the melt flow rate MI of the linear low density polyethylene =3.6/10min, the melt flow rate MI of the high density polyethylene =12.4g/10 min; the foaming auxiliary agent is zinc oxide; the cross-linking agent is TAC; the compatibilizer is ethylene-octene copolymer grafted maleic anhydride, and the grafting rate is 1.2 percent.

In example 3:

the melt flow rate MI of the low density polyethylene =2.3g/10min, the melt flow rate MI of the linear low density polyethylene =5.2g/10min, the melt flow rate MI of the high density polyethylene =20.3g/10 min; the foaming auxiliary agent is a mixture of zinc oxide and stearic acid, and the mass ratio is 1: 4; the cross-linking agent is TMPTMA; the compatibilizer is ethylene-octene copolymer grafted maleic anhydride, and the grafting rate is 1.2 percent.

In comparative examples 1 to 3:

the melt flow rate MI of the low density polyethylene =1.5g/10min, the melt flow rate MI of the linear low density polyethylene =2.5g/10min, the melt flow rate MI of the high density polyethylene =8.6g/10 min; the foaming auxiliary agent is stearic acid; the cross-linking agent is TAIC; the compatibilizer is ethylene-octene copolymer grafted maleic anhydride, and the grafting rate is 1.2 percent.

And (3) performance testing:

the polyethylene foams prepared in examples and comparative examples were subjected to a performance test, and the results are shown in Table 2.

TABLE 2 results of performance test of polyethylene foams prepared in examples 1 to 3 and comparative examples 1 to 3

Test items	Example 1	Example 2	Example 3	Comparative example 1	Comparative example 2	Comparative example 3
							Tensile Strength (MPa)	0.26	0.28	0.26	0.28	0.27	0.26
Elongation at Break (%)	76	96	84	87	88	92
							Flame-retardant effect	Meets GB8410-2006	Meets GB8410-2006	Meets GB8410-2006	After leaving the fire, the smoke continues to burn Obvious fog	Violent combustion after leaving fire, flame smoke Obvious fog	Violent combustion after leaving the fire, flame smoke Is more obvious

From the results in table 2, it can be seen that compared with comparative examples 1-3, the irradiation crosslinked polyethylene foam material prepared in the examples has little change in tensile strength and elongation at break, but the flame retardant property of the foam material is significantly improved due to the compound use of decabromodiphenylethane, antimony trioxide and magnesium hydroxide, so that the flame retardant property meets GB 8410-2006; the foam material prepared by the comparative example can be continuously combusted after being away from the fire, and the smoke is obvious.

The above-mentioned embodiments are merely preferred embodiments for fully illustrating the present invention, and the scope of the present invention is not limited thereto. The equivalent substitution or change made by the technical personnel in the technical field on the basis of the invention is all within the protection scope of the invention. The protection scope of the invention is subject to the claims.