Environment-friendly flame-retardant plastic as well as preparation method and application thereof

Abstract

The invention relates to the technical field of environment-friendly flame-retardant plastics, in particular to an environment-friendly flame-retardant plastic as well as a preparation method and application thereof. The environment-friendly flame-retardant plastic is prepared from the following raw materials in parts by weight: 65 to 70 parts of polyethylene, 26 to 31 parts of environment-friendly flame retardant, 0.8 to 2 parts of lubricant, 0.1 to 1 part of antioxidant and 0.5 to 2 parts of functional additive. The raw materials are mixed, and the mixed material is subjected to melt extrusion and granulation by using a twin-screw extruder to obtain the environment-friendly flame-retardant plastic master batch which is further applied to a polyethylene pipeline material. According to the technical scheme, the technical problem that the mechanical property, apparent property and the like of a polyethylene pipeline material in the prior art are seriously influenced due to the introduction of a large amount of an environment-friendly flame retardant can be solved. The polyethylene pipeline material provided by the invention has excellent mechanical property, good appearance quality and flame retardant property, so that the application scene and field of plastic pipes are widened, and the polyethylene pipeline material has ideal popularization and application prospects.

Description

Technical Field

[0001] The invention relates to the technical field of environmentally friendly flame-retardant plastics, and in particular to an environmentally friendly flame-retardant plastic and a preparation method and application thereof. Background Art

[0002] Pipeline materials are indispensable materials in the fields of construction engineering, power plants, chemical plants, etc. With the rapid development of science and technology, pipeline materials have gone through a development process from cast iron pipes to steel pipes, and then to aluminum-plastic composite pipes and plastic pipes.

[0003] Plastic pipes are an ideal choice to replace traditional cast iron pipes, galvanized steel pipes and cement pipes due to their advantages of energy saving and material saving, light weight, high strength, strong corrosion resistance, simple construction and maintenance, and long service life. They are widely used in many fields such as construction, municipal administration, industry and agriculture, such as heating pipes, wire conduits, gas pipes, power and optical cable protection sleeves, and industrial fluid delivery pipelines. The main types of plastic pipes include polyethylene (PE) pipes, polyvinyl chloride (PVC) pipes and polypropylene (PP) pipes.

[0004] Although PVC pipes have good flame retardant properties, they may release toxic chemicals during production, disposal and combustion, and they have poor performance in terms of temperature resistance, aging resistance and chemical stability, which limits their scope of application. In recent years, PE pipes have been widely promoted by the industry due to their environmental protection, non-toxicity, excellent mechanical properties and chemical corrosion resistance. However, since they do not have flame retardant properties, they need to be flame retardant modified. At present, some high-quality plastic pipes have reached the international UL-94V-0 level flame retardant standard, which is more stringent than the B1 level (flame-retardant material) requirements and can provide a higher level of fire protection.

[0005] As the public's awareness of safety and environmental protection increases, the requirements for flame retardant properties of plastic pipes have become more stringent. The oxygen index of PE material is about 17%, which is a flammable material. By adding environmentally friendly flame retardants, PE materials can reach the UL-94V-0 level, but the large-scale use of environmentally friendly flame retardants will significantly affect the mechanical properties and appearance quality of the material, and increase the melt viscosity, which will bring difficulties to processing and make it difficult to meet the application requirements of PE pipes. Therefore, it is particularly important to develop an environmentally friendly and non-toxic pipe formula that can maintain excellent flame retardant properties and have good mechanical properties and appearance quality. Summary of the invention

[0006] The purpose of the present invention is to provide an environmentally friendly flame-retardant plastic for the preparation of polyethylene pipe materials, so as to solve the technical problem that the mechanical properties and surface properties of polyethylene pipe materials in the prior art are seriously affected by the introduction of a large amount of environmentally friendly flame retardants. Polyethylene pipe materials containing traditional environmentally friendly flame retardants usually have the problem that the flame retardant properties are difficult to be compatible with other properties, and their surface is rough and difficult to process, making it difficult to meet the application requirements of polyethylene pipes.

[0007] To achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0008] An environmentally friendly flame-retardant plastic composition comprises, by weight, 65-70 parts of polyethylene, 26-31 parts of an environmentally friendly flame retardant, 0.8-2 parts of a lubricant, 0.1-1 parts of an antioxidant and 0.5-2 parts of a functional additive.

[0009] Furthermore, the polyethylene includes at least a first polyethylene and a second polyethylene; the melt index of the first polyethylene is 0.1-1 g / 10 min at 190° C. and 5 kg; the melt index of the second polyethylene is 1.1-4 g / 10 min at 190° C. and 5 kg.

[0010] Furthermore, the mass ratio of the first polyethylene to the second polyethylene is (2.0-2.5):(1.0-1.3).

[0011] Furthermore, the lubricant includes a first lubricant and a second lubricant; the first lubricant and the second lubricant are each independently selected from at least one of silicone powder, polyethylene wax, pentaerythritol stearate, and YY-503A, and the first lubricant and the second lubricant are different; the mass ratio of the first lubricant to the second lubricant is (0.4-1): (0.4-1.5).

[0012] Furthermore, the first lubricant is pentaerythritol stearate; the second lubricant includes at least one of silicone powder, polyethylene wax, and YY-503A.

[0013] Furthermore, the functional additive is a silicon-containing compound; the silicon-containing compound includes at least one of silicon dioxide, glass fiber powder, white carbon black, and montmorillonite.

[0014] Furthermore, the silicon-containing compound is silicon dioxide and / or white carbon black; the particle size of silicon dioxide is 10-60 μm, and the particles are spherical; the particle size of white carbon black is 20-100 nm, and the particles are spherical or quasi-spherical.

[0015] Furthermore, the environmentally friendly flame retardant is a phosphorus-nitrogen halogen-free flame retardant; and the antioxidant includes at least one of antioxidant 168, antioxidant 1010 and antioxidant 1330.

[0016] The technical scheme also provides a preparation process of an environmentally friendly flame-retardant plastic composition, which comprises mixing polyethylene, an environmentally friendly flame retardant, a lubricant, an antioxidant, and a functional additive; using a twin-screw extruder to melt-extrude and granulate the mixed material to obtain an environmentally friendly flame-retardant plastic masterbatch.

[0017] The technical solution also provides an application of an environmentally friendly flame-retardant plastic in the preparation of a flame-retardant polyethylene pipe.

[0018] The technical principle and beneficial effects of this technical solution are:

[0019] The present invention provides an environmentally friendly flame-retardant plastic and a preparation process thereof, particularly for polyethylene (PE) pipe materials. In order to overcome the negative impact of the large-scale use of traditional environmentally friendly flame retardants on the mechanical properties and appearance quality of PE materials, the present invention achieves a high-performance balance by optimizing the formula ingredients. The first and second polyethylenes with different melt indexes are mixed in a specific ratio to ensure the good processability and physical properties of the base material. The composition and proportion of specific different types of polyethylene also have a positive promoting effect on improving the mechanical properties, flame retardant properties and product appearance of the product. Phosphorus and nitrogen halogen-free flame retardants are used to ensure that the material meets the UL-94V-0 level flame retardant standard while avoiding the release of toxic substances. Lubricants (such as pentaerythritol stearate, silicone powder, etc.) are used to improve the fluidity of the material, reduce the difficulty of processing, and improve the surface finish. In addition, lubricants with specific compositions and proportions also have a significant effect on the flame retardant effect and mechanical properties of the product. Functional additives (containing silicon compounds) enhance the strength and durability of the material, as well as the flame retardant properties, and improve the surface finish. Antioxidants protect the material from oxidative degradation and extend its service life. These ingredients work together to be melt-extruded and granulated through a twin-screw extruder, ultimately obtaining an environmentally friendly, non-toxic pipe that has excellent flame retardant properties while maintaining good mechanical properties and appearance quality.

[0020] The technical effects of the present invention are mainly reflected in the following aspects:

[0021] Improve flame retardant performance: By using phosphorus and nitrogen halogen-free environmentally friendly flame retardants, the polyethylene pipe material reaches the UL-94V-0 level, providing a higher level of fire protection and meeting the current market demand for increasingly stringent safety requirements.

[0022] Optimizing mechanical properties: Without affecting or even improving the strength of the material, the problem of decreased mechanical properties due to the addition of flame retardants is solved, thanks to the reasonable ratio of functional additives, lubricants and polyethylene.

[0023] Improve appearance quality: Lubricants and functional additives are used to reduce friction during processing, reduce surface defects, and improve the appearance quality of the finished product.

[0024] Environmental friendliness: The use of environmentally friendly halogen-free flame retardants not only avoids the emission of harmful substances, but also conforms to the modern society's pursuit of green buildings and sustainable development.

[0025] Simplify the production process: By optimizing the formula design, the problems that may occur in the production process are reduced, the stability and efficiency of production are improved, and it is conducive to large-scale industrial applications. DETAILED DESCRIPTION

[0026] The present invention is further described in detail below in conjunction with the examples, but the embodiments of the present invention are not limited thereto. Unless otherwise specified, the technical means used in the following examples and experimental examples are conventional means well known to those skilled in the art, and the materials, reagents, etc. used can be obtained from commercial channels. Unless otherwise specified, the technical means used in the following examples are conventional means well known to those skilled in the art.

[0027] Embodiment 1:

[0028] An environmentally friendly flame-retardant plastic for preparing polyethylene pipe materials, the raw materials of which include: 65-70 parts of polyethylene, 26-31 parts of environmentally friendly flame retardant, 0.8-2 parts of lubricant, 0.1-1 parts of antioxidant and 0.5-2 parts of functional additive.

[0029] Preferably, the mass ratio of the environmentally friendly flame retardant to the functional additive is (26-31): (0.5-2). The functional additive is a silicon-containing compound. The silicon-containing compound is selected from at least one of silica powder, glass fiber powder, white carbon black, and montmorillonite. More specifically, the silica powder has a particle size of 10-60 μm and a regular spherical shape; the white carbon black has a particle size of 20-100 nm and a spherical or quasi-spherical shape; the glass fiber powder has a diameter of 10-15 μm and a particle size of 40-100 μm. Silica powder and white carbon black are preferred.

[0030] The lubricant includes at least a first lubricant and a second lubricant, and the first lubricant and the second lubricant are each independently selected from at least one of silicone powder, polyethylene wax, pentaerythritol stearate, and YY-503A, and the first lubricant and the second lubricant are different. The mass ratio of the first lubricant to the second lubricant is (0.4-1): (0.4-1.5). Preferably, the first lubricant is pentaerythritol stearate, and the second lubricant includes at least one of silicone powder, polyethylene wax, and YY-503A.

[0031] The antioxidant includes at least one of the antioxidant 168 , the antioxidant 1010 , and the antioxidant 1330 .

[0032] The polyethylene includes at least two polyethylenes (a first polyethylene and a second polyethylene), the first polyethylene has a melt index of 0.1-1 g / 10 min (190° C., 5 kg); the second polyethylene has a melt index of 1.1-4 g / 10 min (190° C., 5 kg). Preferably, the first polyethylene is selected from at least one of HDPE-HMCRP100N, HDPE-23050, and HDPE-HD7000H; the second polyethylene is selected from at least one of HDPE-5000S, HDPE-5502W, and HDPE-B5703. The mass ratio of the first polyethylene to the second polyethylene is (2.0-2.5):(1.0-1.3).

[0033] The environmentally friendly flame retardant includes phosphorus-nitrogen halogen-free flame retardant, which is selected from at least one of FR1420, FR1430, FR1520, and FR1530 (specific models of phosphorus-nitrogen halogen-free flame retardants, Chongqing Kejufu New Materials Co., Ltd.).

[0034] A method for preparing an environmentally friendly flame-retardant plastic for preparing polyethylene pipe materials is to prepare a masterbatch by a conventional twin-screw extrusion method, as follows:

[0035] (1) Polyethylene, environmentally friendly flame retardant, lubricant, antioxidant and functional additive are mixed by a low-speed stirring mixer at 10 rpm-100 rpm (preferably 50 rpm) until mixed evenly;

[0036] (2) A parallel twin-screw extruder is used for melting and extrusion granulation, wherein the screw diameter is 35 cm-75 cm (preferably 50 cm), the aspect ratio is 30-40:1 (preferably 35:1), and the melting temperature is 185-215°C (called the second melting temperature, preferably 190-200°C), thereby obtaining an environmentally friendly flame-retardant plastic masterbatch.

[0037] After obtaining the masterbatch, the environmentally friendly flame-retardant plastic masterbatch is prepared into a test specimen (for testing flame retardancy and mechanical properties) by an injection molding machine, and the injection molding temperature is 180-200°C (preferably 190°C). The UL-94 (2.0mm, 1.2mm) test method refers to the standard GB / T 2408-2021; the limiting oxygen index (LOI) test refers to the standard ASTM-D2863. The tensile property test method refers to the standard GB / T 1040.2-2022.

[0038] The granulated pellets (environmentally friendly flame-retardant plastic masterbatch) are put into a sheet drawing machine for melt injection molding, and the molding of the plastic sheet is observed. The inlet temperature is 175-185°C (preferably 175-185°C), and the melting temperature is 190-210°C (called the first melting temperature, preferably 190-200°C). The environmentally friendly flame-retardant plastic is thus prepared as a polyethylene sheet. The molding appearance of the polyethylene sheet is observed, with emphasis on the smoothness of its surface. In order to better observe the surface condition (apparent state) of the material after molding, this test prepares the environmentally friendly flame-retardant plastic masterbatch into a sheet. In actual application, the environmentally friendly flame-retardant plastic masterbatch can be melt-injected into a pipe form.

[0039] Experimental Example 1

[0040] According to the formula in Table 1 and Table 2, and in accordance with the optimal method of Example 1, environmentally friendly flame retardant plastic masterbatch, test specimens, and polyethylene sheets were prepared, and then the performance indicators of the above products were tested.

[0041] Table 1: Recipe and process parameters

[0042]

[0043] Table 2: Formulation and process parameters (continued from the previous table)

[0044]

[0045] The flame retardant effect and mechanical property tests were carried out on the test specimens, and the appearance of the polyethylene sheet was observed. The experimental results are shown in Tables 3 and 4.

[0046] Table 3: Mechanical properties and flame retardant properties

[0047]

[0048] Table 4: Mechanical properties and flame retardant properties (continued from the previous table)

[0049]

[0050]

[0051] According to the above experimental data, it can be seen that in tests 1-6, the flame retardant properties and mechanical strength of the environmentally friendly flame retardant plastics prepared by the environmentally friendly flame retardant plastic formula of this scheme are relatively ideal, and the extrusion state of the polyethylene sheet prepared by using the environmentally friendly flame retardant plastic is stable, and the surface touch is smooth (or there is a slight granular feel). In tests 1-6, tests 1, 3, and 4 are better formulas. The flame retardant performance of test 2 is slightly poor, and the inventor analyzes that the reason is that the amount of environmentally friendly flame retardant added is too little. The flame retardant properties of the environmentally friendly flame retardant plastics of tests 5 and 6 are slightly poor and the appearance of the polyethylene sheet is slightly poor. The flame retardant performance of test 5 is slightly poor, and the inventor analyzes that the reason is that the amount of flame retardant additive added is too little; the appearance of the polyethylene sheet is slightly poor, and the inventor analyzes that the reason is that the total amount of lubricant added is too little. The flame retardant performance of test 6 is slightly poor, and the inventor analyzes that the reason is that the amount of environmentally friendly flame retardant added is too little; the appearance of the polyethylene sheet is slightly poor, and the inventor analyzes that the reason is that the total amount of lubricant added is too little.

[0052] Therefore, more preferably, the amount of polyethylene is in the range of 65-67 parts (the mass ratio of the first polyethylene to the second polyethylene is (40-44): (23-25), i.e. (2.0-2.2): (1.2-1.3)); the amount of environmentally friendly flame retardant is in the range of 29-31 parts; the amount of lubricant is 2 parts (and the mass ratio of the first lubricant to the second lubricant is (0.5-1): (1.0-1.5)); the amount of functional additive is 1.5 parts, and the amount of antioxidant is 0.5 parts. And the mass ratio of environmentally friendly flame retardant to flame retardant additive is preferably (29-31): 1.5.

[0053] In addition, the polyethylene material of this scheme uses two polyethylenes with different melt indexes (first polyethylene and second polyethylene), which is very critical to improving the flame retardant properties, mechanical properties and appearance of the material after molding of the environmentally friendly flame retardant plastic. Referring to the experimental data of Comparative Test 1, Comparative Test 2 and Test 1, the three experimental groups used the first polyethylene as the entire polyethylene raw material, the second polyethylene as the entire polyethylene raw material, and the first polyethylene and the second polyethylene as the entire polyethylene raw material. The experimental results show that the tensile strength of the environmentally friendly flame retardant plastics prepared by Comparative Test 1 and Comparative Test 2 is significantly lower than that of Test 1. The LOI value of the environmentally friendly flame retardant plastics prepared by Comparative Test 1 and Comparative Test 2 is also significantly lower than that of Test 1. The LOI value parameter reflects the flame retardant properties of the material. The higher the LOI value, the more difficult it is for the material to burn and the better the flame retardancy. In addition, using the second polyethylene alone as the entire polyethylene raw material will directly result in a flame retardant grade of V-1. In addition, the appearance of the polyethylene sheet prepared by Comparative Test 1 and Comparative Test 2 is not ideal, and the surface is rough and has obvious lines and burrs on the cross section. Therefore, in the formula composition environment of this scheme, the co-addition of the first polyethylene and the second polyethylene is very critical to ensure the mechanical properties and flame retardant properties of the environmentally friendly flame retardant plastic, and at the same time improves the appearance of the sheet prepared with the environmentally friendly flame retardant plastic. The inventor analyzed that the reason is that the single polyethylene has poor compatibility with the flame retardant, and the flame retardant is more likely to agglomerate, resulting in a decrease in the mechanical, apparent and flame retardant properties of the flame retardant polyethylene material obtained; while the combination of polyethylene with different melt indices in a specific proportion is more likely to provide binding sites for the flame retardant due to the difference in molecular structure, improve the dispersibility of the flame retardant, and thus improve its mechanical, apparent and flame retardant properties.

[0054] In addition, the addition ratio of the first polyethylene and the second polyethylene is also critical to the improvement of product performance. In comparative test 3, the ratio of the first polyethylene to the second polyethylene is 50:17. Compared with the ratio of the two polyethylenes of 44:23 in test 1, the mechanical properties of the obtained product are reduced and the flame retardant properties are reduced. After being prepared into polyethylene sheets, it can be observed that the surface is visible to the naked eye. Roughness and obvious lines, burrs on the cross section, and the extrusion process is unstable and there is a phenomenon of pulling and breaking. The inventor analyzed that the reason is that the amount of the second polyethylene added is too small, not only does it not trigger the synergistic effect, but because a small amount of the second polyethylene is mixed in a relatively large amount of the first polyethylene, the two polyethylenes cannot be completely mixed evenly, and at the same time, the dispersion effect of the flame retardant is affected, resulting in the above-mentioned adverse consequences.

[0055] In addition to the need for the co-addition of the first polyethylene and the second polyethylene, this solution also requires the control of the addition form and amount of the lubricant. In comparative test 4, the ratio of pentaerythritol stearate and silicone powder E525 is 0.3:1.7, which is lower than the ratio in test 1 (0.5:1.5), resulting in a significant decrease in the mechanical properties and flame retardant properties of the environmentally friendly flame retardant plastic, and the appearance of the sheet prepared by the environmentally friendly flame retardant plastic is visibly rough. In comparative test 6, only pentaerythritol stearate is used (i.e., accounting for 100% of the lubricant dosage), which is lower than the ratio in test 1, resulting in a significant decrease in the mechanical properties and flame retardant properties of the environmentally friendly flame retardant plastic, and the appearance of the sheet prepared by the environmentally friendly flame retardant plastic is visibly rough. In addition to comparative test 6, the inventor also tried to add silicone powder E525 alone, and found that the mechanical properties and flame retardant properties of the environmentally friendly flame retardant plastic were not much different from those in comparative test 6, which also shows that the effect of using a single lubricant is not ideal. When the two lubricants are added in a specific ratio, the performance of the obtained environmentally friendly flame retardant plastic is significantly improved (test 1), which shows that the combined use of pentaerythritol stearate and silicone powder E525 in a specific ratio and under the formulation conditions of this scheme can synergize and enhance the performance of environmentally friendly flame retardant plastics, and obtain unexpected technical effects. The inventor analyzed that the reason is that a single compatibilizer cannot completely solve the interface problem between the flame retardant and polyethylene, and specific types of compatibilizers may have a synergistic effect, such as pentaerythritol stearate and silicone powder E525 in the ratio range of (0.4-1): (0.4-1.5) (especially (0.5-1): (1.0-1.5)) can better exert a synergistic effect, effectively improve the interfacial compatibility between the flame retardant and polyethylene through chemical bonds or hydrogen bonds, reduce interfacial tension, etc., and improve its mechanical, apparent and flame retardant properties.

[0056] In addition, the type of functional additives in the formula also has a significant impact on the mechanical properties, flame retardant properties, and appearance of the formed sheet of environmentally friendly flame retardant plastics. In comparative test 5, the flame retardant additive used was glass fiber powder. Compared with test 1 (using regular silica as a flame retardant additive), the mechanical properties and flame retardant properties of the environmentally friendly flame retardant plastic obtained were greatly reduced, and the appearance of the sheet prepared in this way (used to characterize the appearance of the material after molding) was as follows: the surface was visibly rough and striped.

[0057] The above is only an embodiment of the present invention, and the common knowledge such as the known specific structure and characteristics in the scheme is not described in detail here. It should be pointed out that for those skilled in the art, several deformations and improvements can be made without departing from the structure of the present invention, which should also be regarded as the protection scope of the present invention, and these will not affect the effect of the implementation of the present invention and the practicality of the patent. The scope of protection required by this application shall be based on the content of its claims, and the specific implementation methods and other records in the specification can be used to interpret the content of the claims.

Claims

1. An environmentally friendly flame retardant plastic composition, characterized in that: The raw materials include, by weight: 65-70 parts of polyethylene, 26-31 parts of environmentally friendly flame retardant, 0.8-2 parts of lubricant, 0.1-1 parts of antioxidant and 0.5-2 parts of functional additive; The polyethylene includes at least a first polyethylene and a second polyethylene; the melt index of the first polyethylene is 0.1-1 g / 10 min at 190° C. and 5 kg; the melt index of the second polyethylene is 1.1-4 g / 10 min at 190° C. and 5 kg.

2. The environmentally friendly flame-retardant plastic composition according to claim 1, characterized in that: The mass ratio of the first polyethylene to the second polyethylene is (2.0-2.5):(1.0-1.3).

3. The environmentally friendly flame-retardant plastic composition according to claim 2, characterized in that: The lubricant includes a first lubricant and a second lubricant; the first lubricant and the second lubricant are each independently selected from at least one of silicone powder, polyethylene wax, pentaerythritol stearate, and YY-503A, and the first lubricant and the second lubricant are different; the mass ratio of the first lubricant to the second lubricant is (0.4-1): (0.4-1.5).

4. The environmentally friendly flame-retardant plastic composition according to claim 3, characterized in that: The first lubricant is pentaerythritol stearate; the second lubricant includes at least one of silicone powder, polyethylene wax and YY-503A.

5. The environmentally friendly flame-retardant plastic composition according to claim 4, characterized in that: The functional additive is a silicon-containing compound; the silicon-containing compound includes at least one of silicon dioxide, glass fiber powder, white carbon black and montmorillonite.

6. The environmentally friendly flame-retardant plastic composition according to claim 5, characterized in that: The silicon-containing compound is silicon dioxide and / or white carbon black; the particle size of silicon dioxide is 10-60 μm, and the particles are spherical; the particle size of white carbon black is 20-100 nm, and the particles are spherical or quasi-spherical.

7. An environmentally friendly flame-retardant plastic composition according to claim 6, characterized in that: The environmentally friendly flame retardant is a phosphorus-nitrogen halogen-free flame retardant; the antioxidant includes at least one of antioxidant 168, antioxidant 1010 and antioxidant 1330.

8. A process for preparing an environmentally friendly flame-retardant plastic composition according to any one of claims 1 to 7, characterized in that: Polyethylene, environmentally friendly flame retardant, lubricant, antioxidant and functional additive are mixed; a twin-screw extruder is used to melt-extrude and granulate the mixed materials to obtain environmentally friendly flame retardant plastic masterbatch.

9. Use of an environmentally friendly flame-retardant plastic composition according to any one of claims 1 to 7 in the preparation of flame-retardant polyethylene pipes.

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