Flame retardant for PVC (polyvinyl chloride) wire and cable material and environment-friendly flame-retardant PVC wire and cable material

Abstract

The invention provides a flame retardant for a PVC (polyvinyl chloride) wire and cable material. The flame retardant is prepared from the following raw materials: urea, phosphoric acid, acidic lignin and pentaerythritol. The weight ratio of the urea to the phosphoric acid to the acidic lignin to the pentaerythritol is 1: (0.8-1): (0.1-0.5): (0.01-0.05). As the flame retardant for the PVC wire and cable material integrates an acid source, a gas source and a carbon source, the flame retardant has strong polarity; according to the embodiment of the invention, the acidic lignin and the pentaerythritol are used as carbon sources, the phosphoric acid is used as an acid source, and the urea is used as a gas source, so that the prepared flame retardant is a carbon-phosphorus-nitrogen ternary synergistic intumescent flame retardant, is high in flame retardant efficiency, and is green and environment-friendly. The flame-retardant PVC wire and cable material prepared based on the flame retardant has the advantages of high tensile strength, strong ultraviolet aging resistance, obvious intumescent flame-retardant effect, simple preparation process, greenness, environmental protection and easiness in industrial production.

Description

Technical Field

[0001] The invention relates to the field of wire and cable polymer materials, and in particular to a flame retardant for PVC wire and cable materials, an environmentally friendly flame-retardant PVC wire and cable material and a preparation method thereof. Background Art

[0002] Polyvinyl chloride (PVC) is relatively cheap. Because it has a high content of chlorine, which can be as high as 56%, it has high heat resistance and oxygen index, is not easy to burn, and has good comprehensive performance. Therefore, it is widely used in the field of wires and cables. However, when PVC burns, it will produce HCl gas, which is very toxic and corrosive, and produces a lot of smoke; and the existing flame-retardant PVC wire and cable materials do not meet the requirements of green economic development because the antimony trioxide flame retardant added is carcinogenic. Therefore, the development of green and environmentally friendly flame-retardant PVC wire and cable materials is the future development direction of PVC wire and cable. Summary of the invention

[0003] The object of the present invention is to provide a flame retardant for PVC wire and cable materials. Applying the flame retardant to PVC wire and cable materials can achieve green, environmentally friendly and flame retardant effects.

[0004] In order to achieve the above object, the technical solution of the present invention is as follows:

[0005] The first aspect of the present invention provides a flame retardant for PVC wire and cable materials, which is prepared from the following raw materials: urea, phosphoric acid, acidic lignin, and pentaerythritol.

[0006] Furthermore, the weight ratio of urea, phosphoric acid, acidic lignin and pentaerythritol is 1:(0.8-1):(0.1-0.5):(0.01-0.05).

[0007] Furthermore, the acidic lignin is obtained by the following steps: boiling crude acidic lignin in hot water at 70-90°C, stirring for 1-2 hours, filtering while hot, washing, and drying to obtain acidic lignin; further, the ratio of crude acidic lignin to water is (0-10) g: 100 ml.

[0008] The second aspect of the present invention provides a method for preparing a flame retardant for PVC wire and cable materials, comprising the following steps:

[0009] Step 1: Add phosphoric acid and urea into the reactor, stir at a low speed; heat up to 55-65°C, add acidic lignin and pentaerythritol after the urea is completely dissolved, stir, and add defoamer;

[0010] Step 2: Then, heat to 95-115℃ while stirring, and keep the temperature constant until bubbles appear, then stop the reaction;

[0011] Step 3: Transfer the product obtained in the second step into a porcelain container and react at 190-220° C. for 3-5 hours to obtain the flame retardant for PVC wire and cable materials.

[0012] The third aspect of the present invention provides an environmentally friendly flame-retardant PVC wire and cable material, which is prepared from the following raw materials in parts by weight: 100 parts of polyvinyl chloride (PVC), 5-15 parts of calcium zinc stabilizer, 40-50 parts of octyl phthalate, 40-80 parts of calcium carbonate, 15-70 parts of flame retardant for PVC wire and cable materials, 2-3 parts of zinc stearate, and 2-5 parts of antioxidant.

[0013] The amount of the flame retardant used for PVC wire and cable materials is preferably 25-55 parts.

[0014] Furthermore, the particle size of the flame retardant, calcium zinc stabilizer, octyl phthalate, calcium carbonate, zinc stearate and antioxidant mixture for PVC wire and cable materials after ball milling is 2-15 microns, preferably 5-10 microns.

[0015] A fourth aspect of the present invention provides a method for preparing an environmentally friendly flame-retardant PVC wire and cable material, comprising the following steps:

[0016] The flame retardant, calcium zinc stabilizer, octyl phthalate, calcium carbonate, zinc stearate and antioxidant for PVC wire and cable materials are mixed in a high-speed mixer for 1-3 minutes, and then the mixture is ball-milled at high speed in a ball mill to obtain a crushing and mixing aid; the particle size of the crushing and mixing aid after ball milling is 2-15 microns, preferably 5-10 microns;

[0017] Mix PVC and crushing and mixing aids in a high-speed mixer for 1-3 minutes to obtain a preliminary mixture;

[0018] The primary mixture is melt-blended, extruded and granulated through a twin-screw extruder.

[0019] Furthermore, the flame retardant, calcium zinc stabilizer, octyl phthalate, calcium carbonate, zinc stearate and antioxidant mixture for PVC wire and cable materials are ball-milled at high speed in a ball mill for 2-6 hours, preferably 3-4 hours.

[0020] Furthermore, the temperature parameter of the extruder is 110-185° C., and the screw speed of the extruder is 50 rpm-250 rpm.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] 1. The present invention provides a flame retardant for PVC wire and cable materials. Applying the flame retardant to PVC wire and cable materials can achieve green, environmentally friendly and flame retardant effects.

[0023] 2. Since the flame retardant used for PVC wire and cable materials integrates acid source, gas source and carbon source, it has strong polarity; the flame retardant prepared in the embodiment of the present invention is a carbon-phosphorus-nitrogen ternary synergistic intumescent flame retardant with high flame retardant efficiency and is green and environmentally friendly. The flame-retardant PVC wire and cable material prepared based on the flame retardant has high tensile strength, strong resistance to ultraviolet aging, obvious intumescent flame retardant effect, simple preparation process, green and environmentally friendly, and easy to industrialize.

[0024] 3. Lignin contains a large amount of aromatic structure, which has a good absorption effect on solar ultraviolet light and can play a role in ultraviolet aging resistance. Lignin has a three-dimensional structure and contains a large amount of hydroxyl groups, which has a binding effect on octyl phthalate, thereby inhibiting the outward migration of octyl phthalate and increasing the performance stability of PVC wires and cables.

[0025] 4. In the embodiments of the present invention, the particle size of the flame retardant, calcium zinc stabilizer, octyl phthalate, calcium carbonate, zinc stearate and antioxidant mixture used in PVC wire and cable materials is controlled within 2-15 microns to avoid reagglomeration due to their too small particles, or difficult dispersion due to their too large particle size, which has a negative impact on the performance of the PVC wire and cable materials. When their particle size is controlled within the range of 2-15 microns, their size is moderate, and they can not only be evenly dispersed in the PVC substrate, but also show a small size effect, which increases the mechanics of the material.

[0026] 5. Since the acidic lignin used in the present invention is derived from papermaking industrial waste, it has a wide source and is cheap. Therefore, its introduction can reduce the cost of PVC wire and cable materials and realize the high-value application of lignin, which has a good social and economic effect.

[0027] 6. Lignin molecules contain polar groups such as hydroxyl, ether bonds, unsaturated double bonds, etc., and have good reactivity and compatibility. Green flame retardants can be prepared by chemical methods with lignin as a carbon source, acid source and gas source. Green flame retardants with strong anti-aging ability can be prepared by melt blending with PVC materials and other additives.

[0028] 7. In the embodiment of the present invention, the flame retardant prepared by reacting acidic lignin with phosphoric acid, urea and pentaerythritol is compounded with PVC, a heat stabilizer, a plasticizer, an antioxidant and a filler. The green and environmentally friendly flame-retardant PVC wire and cable material prepared has high tensile strength, strong anti-aging ability, good flame retardancy, good dielectric properties, low carbon and environmental protection, and has a good application prospect. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0030] Figure 1 A schematic diagram of the reaction principle of a flame retardant for PVC wire and cable materials provided in an embodiment of the present invention;

[0031] Figure 2 A schematic diagram of a process flow for preparing an environmentally friendly flame-retardant PVC wire and cable material provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0032] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0033] Embodiments of the present invention:

[0034] Embodiment 1 of the present invention provides a method for preparing acidic lignin, wherein crude acidic lignin is stirred in hot water at 70-90° C. for 1-2 hours, filtered while hot, washed, and dried to obtain acidic lignin;

[0035] The ratio of crude acidic lignin to water is (0-10) g:100 ml.

[0036] Embodiment 2 of the present invention provides a flame retardant for PVC wire and cable materials, which is prepared from the following raw materials: urea, phosphoric acid, acidic lignin, and pentaerythritol. The weight ratio of urea, phosphoric acid, acidic lignin, and pentaerythritol is 1: (0.8-1): (0.1-0.5): (0.01-0.05).

[0037] Embodiment 3 of the present invention provides a method for preparing a flame retardant for PVC wire and cable materials, comprising the following steps:

[0038] a. Stir the crude acidic lignin in hot water at 70-90°C for 1-2 hours, filter while hot, wash, and dry to obtain acidic lignin;

[0039] The ratio of crude acidic lignin to water is (0-10) g: 100 ml;

[0040] b. Add phosphoric acid and urea to a reactor (a reactor can be used in the embodiment of the present invention), raise the temperature to 55-65°C while stirring at a low speed, add acidic lignin and pentaerythritol after the urea is completely dissolved; add an appropriate amount of defoamer after stirring; the defoamer in the embodiment of the present invention uses dimethyl silicone oil;

[0041] In the embodiment of the present invention, the high-speed mixer is divided into a low-speed gear and a high-speed gear, and the low-speed stirring is to adjust the high-speed mixer to the low-speed gear;

[0042] c. Heat to 95-115℃ while stirring, keep constant temperature until bubbles appear, then stop the reaction;

[0043] d. The product obtained in step c is transferred into a porcelain container and reacted at 190-220° C. for 3-5 hours to obtain the flame retardant for PVC wire and cable materials.

[0044] Embodiment 4 of the present invention provides an environmentally friendly flame-retardant PVC wire and cable material, which is prepared from the following raw materials in parts by weight: 100 parts of polyvinyl chloride (PVC), 5-15 parts of calcium zinc stabilizer, 40-50 parts of octyl phthalate, 40-80 parts of calcium carbonate, 25-55 parts of flame retardant for PVC wire and cable materials, 2-3 parts of zinc stearate, and 2-5 parts of antioxidant.

[0045] Embodiment 5 of the present invention provides a method for preparing an environmentally friendly flame-retardant PVC wire and cable material, comprising the following steps:

[0046] A. Mix the flame retardant, calcium zinc stabilizer, octyl phthalate, calcium carbonate, zinc stearate and antioxidant for PVC wire and cable materials in a high-speed mixer for 1-3 minutes, and then mill the mixture in a ball mill at high speed for 3-4 hours to obtain a crushing and mixing aid;

[0047] The particle size of the mixture of flame retardant, calcium zinc stabilizer, octyl phthalate, calcium carbonate, zinc stearate and antioxidant for PVC wire and cable materials after ball milling is 5-10 microns;

[0048] B. Mix PVC and crushing and mixing aids in a high-speed mixer for 1-3 minutes to obtain a primary mixture;

[0049] C. The primary mixture is melt-blended, extruded and granulated through a twin-screw extruder to obtain an environmentally friendly flame-retardant PVC wire and cable material; the temperature parameter of the extruder is 110-185° C., and the screw speed of the extruder is 50rpm-250rpm.

[0050] The following provides specific embodiments

[0051] Example 1

[0052] Preparation of flame retardant for PVC wire and cable materials:

[0053] The crude acidic lignin is boiled in hot water at 80°C for 1.5 hours, filtered while hot, washed, and dried to obtain purified acidic lignin; the concentration of the crude acidic lignin in water is 5g / 100ml.

[0054] Phosphoric acid and urea are added to a reactor, and the temperature is raised to 60°C and maintained at a constant temperature until the solid melts. Then, after 2 minutes, acidic lignin and pentaerythritol are added to the reactor, and after stirring for 1 minute, an appropriate amount of dimethyl silicone oil is added; the temperature is raised to 95°C and maintained at a constant temperature until fine bubbles are generated, the reactants in the reactor are transferred into a porcelain container, and the reaction is continued at 200°C for 4 hours, the reaction is stopped, and the flame retardant for PVC wire and cable materials is obtained by cooling and crushing; wherein the weight ratio of phosphoric acid, urea, acidic lignin and pentaerythritol is 1:1:0.2:0.05.

[0055] Preparation of PVC wire and cable materials:

[0056] 60 parts of the flame retardant for PVC wire and cable materials in Example 1, 10 parts of calcium zinc stabilizer, 40 parts of octyl phthalate, 50 parts of calcium carbonate, 2 parts of zinc stearate and 2 parts of antioxidant were mixed in a high-speed mixer for 2 minutes, and then the mixture was high-speed ball-milled in a ball mill for 4 hours to obtain a mixture with a particle size of 8 microns; 100 parts of PVC and a crushing and mixing aid were mixed at high speed in a high-speed mixer for 3 minutes to obtain a primary mixture; the primary mixture was melt-blended, extruded and granulated through a twin-screw extruder to obtain an environmentally friendly flame-retardant PVC wire and cable material; wherein the twin-screw extruder has a temperature of 110°C in zone 1, 135°C in zone 2, 155°C in zone 3, 165°C in zone 4, 175°C in zone 5, 180°C in zone 6, a die head of 175°C and a screw speed of 150rpm.

[0057] Example 2

[0058] Preparation of flame retardant for PVC wire and cable materials:

[0059] The crude acidic lignin is boiled in hot water at 90°C for 1 hour, filtered while hot, washed, and dried to obtain purified acidic lignin; the concentration of the crude acidic lignin in water is 10g / 100ml.

[0060] Phosphoric acid and urea are added to a reactor, and the temperature is raised to 65°C and kept constant until the solid melts. Then, after 2 minutes, acidic lignin and pentaerythritol are added to the reactor, and after stirring for 1 minute, an appropriate amount of dimethyl silicone oil is added; the temperature is raised to 100°C and kept constant until fine bubbles are generated, and the reactants in the reactor are transferred into a porcelain container, and the reaction is continued at 220°C for 3 hours, and the reaction is stopped, cooled, and crushed to obtain a flame retardant for PVC wire and cable materials; the weight ratio of phosphoric acid, urea, acidic lignin, and pentaerythritol is 0.8:1:0.1:0.01.

[0061] Preparation of PVC wire and cable materials:

[0062] 15 parts of the flame retardant for PVC wire and cable materials in Example 2, 12 parts of calcium zinc stabilizer, 50 parts of octyl phthalate, 80 parts of calcium carbonate, 3 parts of zinc stearate and 2 parts of antioxidant were mixed in a high-speed mixer for 1 minute, and then the mixture was high-speed ball-milled in a ball mill for 3.5 hours to obtain a mixture with a particle size of 10 microns; 100 parts of PVC and a crushing and mixing aid were mixed at high speed in a high-speed mixer for 2 minutes to obtain a primary mixture; the primary mixture was melt-blended, extruded and granulated through a twin-screw extruder to obtain an environmentally friendly flame-retardant PVC wire and cable material; wherein the twin-screw extruder has a temperature of 120°C in zone 1, 135°C in zone 2, 155°C in zone 3, 165°C in zone 4, 175°C in zone 5, 185°C in zone 6, a die head of 180°C, and a screw speed of 100rpm.

[0063] Example 3

[0064] Preparation of flame retardant for PVC wire and cable materials:

[0065] The crude acidic lignin is boiled in hot water at 70°C for 2 hours, filtered while hot, washed, and dried to obtain purified acidic lignin; the ratio of crude acidic lignin to water is 8g / 100ml.

[0066] Phosphoric acid and urea are added to a reactor, and the temperature is raised to 55° C. and maintained at a constant temperature until the solid melts. Then, after 2 minutes, acidic lignin and pentaerythritol are added to the reactor, and after stirring for 1 minute, an appropriate amount of dimethyl silicone oil is added; the temperature is raised to 110° C. and maintained at a constant temperature until fine bubbles are generated, and the reactants in the reactor are transferred into a porcelain container, and the reaction is continued at 190° C. for 5 hours, and the reaction is stopped, cooled, and crushed to obtain a flame retardant for PVC wire and cable materials; the weight ratio of phosphoric acid, urea, acidic lignin, and pentaerythritol is 1 / 1 / 0.5 / 0.01.

[0067] Preparation of PVC wire and cable materials:

[0068] 70 parts of the flame retardant for PVC wire and cable materials in Example 3, 15 parts of calcium zinc stabilizer, 45 parts of octyl phthalate, 40 parts of calcium carbonate, 2 parts of zinc stearate and 1 part of antioxidant were mixed in a high-speed mixer for 2 minutes, and then the mixture was high-speed ball-milled in a ball mill for 6 hours to obtain a mixture with a particle size of 2 microns; 100 parts of PVC and a crushing and mixing aid were mixed at high speed in a high-speed mixer for 3 minutes to obtain a primary mixture; the primary mixture was melt-blended, extruded and granulated through a twin-screw extruder to obtain an environmentally friendly flame-retardant PVC wire and cable material; wherein the twin-screw extruder has a temperature of 110°C in zone 1, 130°C in zone 2, 150°C in zone 3, 160°C in zone 4, 170°C in zone 5, 180°C in zone 6, a die head of 175°C, and a screw speed of 200rpm.

[0069] Comparative Example 1

[0070] The only difference from Example 1 is that in Comparative Example 1, PVC wire and cable materials are prepared without adding flame retardant, and the rest is the same as in Example 1;

[0071] Preparation of PVC wire and cable materials (without adding flame retardant):

[0072] Mix 10 parts of calcium zinc stabilizer, 40 parts of octyl phthalate, 50 parts of calcium carbonate, 2 parts of zinc stearate and 2 parts of antioxidant in a high-speed mixer for 2 minutes, and then high-speed ball-mill the mixture in a ball mill for 4 hours to obtain a mixture with a particle size of 8 microns; 100 parts of PVC and a crushing and mixing aid are mixed at high speed in a high-speed mixer for 3 minutes to obtain a primary mixture; the primary mixture is melt-blended, extruded and granulated through a twin-screw extruder to obtain a PVC wire and cable material; wherein, the twin-screw extruder has a zone of 110°C, a zone of 135°C, a zone of 155°C, a zone of 165°C, a zone of 175°C, a zone of 180°C, a die of 175°C, and a screw speed of 150rpm.

[0073] Comparative Example 2

[0074] The only difference from Example 1 is that the flame retardant in Comparative Example 2 does not use acidic lignin, and the rest is the same as Example 1;

[0075] Preparation of flame retardant (using phosphoric acid, urea, pentaerythritol):

[0076] Phosphoric acid and urea are added to a reactor, and the temperature is raised to 60°C and maintained at a constant temperature until the solid melts. Pentaerythritol is then added to the reactor after 2 minutes, and an appropriate amount of dimethyl silicone oil is added after stirring for 1 minute. The temperature is raised to 95°C and maintained at a constant temperature until fine bubbles are generated. The reactants in the reactor are transferred into porcelain, and the reaction is continued at 200°C for 4 hours. The reaction is stopped, and the flame retardant is obtained by cooling and crushing. The weight ratio of phosphoric acid, urea and pentaerythritol is 1:1:0.05.

[0077] Preparation of PVC wire and cable materials:

[0078] Mix 60 parts of the flame retardant of Comparative Example 2, 10 parts of calcium zinc stabilizer, 40 parts of octyl phthalate, 50 parts of calcium carbonate, 2 parts of zinc stearate and 2 parts of antioxidant in a high-speed mixer for 2 minutes, and then high-speed ball mill the mixture in a ball mill for 4 hours to obtain a mixture with a particle size of 8 microns; 100 parts of PVC and a crushing and mixing aid are mixed at high speed in a high-speed mixer for 3 minutes to obtain a primary mixture; the primary mixture is melt-blended, extruded and granulated through a twin-screw extruder to obtain a PVC wire and cable material; wherein, the twin-screw extruder has a temperature of 110°C in zone 1, 135°C in zone 2, 155°C in zone 3, 165°C in zone 4, 175°C in zone 5, 180°C in zone 6, a die head of 175°C, and a screw speed of 150rpm.

[0079] Comparative Example 3

[0080] The only difference from Example 1 is that the lignin used as the flame retardant in Comparative Example 3 is crude acidic lignin that has not been heated and boiled, and the rest is the same as Example 1;

[0081] Preparation of flame retardant (using phosphoric acid, urea, pentaerythritol, crude acidic lignin):

[0082] Phosphoric acid and urea are added to a reactor, and the temperature is raised to 60°C and maintained at a constant temperature until the solid melts. Then, crude acidic lignin and pentaerythritol are added to the reactor after 2 minutes, and an appropriate amount of dimethyl silicone oil is added after stirring for 1 minute. The temperature is raised to 95°C and maintained at a constant temperature until fine bubbles are generated. The reactants in the reactor are transferred into porcelain, and the reaction is continued at 200°C for 4 hours. The reaction is stopped, and the flame retardant is obtained by cooling and crushing. The weight ratio of phosphoric acid, urea, crude acidic lignin and pentaerythritol is 1:1:0.2:0.05.

[0083] Preparation of PVC wire and cable materials:

[0084] Mix 60 parts of the flame retardant of Comparative Example 3, 10 parts of calcium zinc stabilizer, 40 parts of octyl phthalate, 50 parts of calcium carbonate, 2 parts of zinc stearate and 2 parts of antioxidant in a high-speed mixer for 2 minutes, and then high-speed ball mill the mixture in a ball mill for 4 hours to obtain a mixture with a particle size of 8 microns; 100 parts of PVC and a crushing and mixing aid are mixed at high speed in a high-speed mixer for 3 minutes to obtain a primary mixture; the primary mixture is melt-blended, extruded and granulated through a twin-screw extruder to obtain a PVC wire and cable material; wherein, the twin-screw extruder has a temperature of 110°C in zone 1, 135°C in zone 2, 155°C in zone 3, 165°C in zone 4, 175°C in zone 5, 180°C in zone 6, a die head of 175°C, and a screw speed of 150rpm.

[0085] Comparative Example 4

[0086] The only difference from Example 1 is that the flame retardant in Comparative Example 4 does not use pentaerythritol, and the rest is the same as Example 1;

[0087] Preparation of flame retardant (using phosphoric acid, urea, acidic lignin):

[0088] The crude acidic lignin is boiled in hot water at 80°C for 1.5 hours, filtered while hot, washed, and dried to obtain purified acidic lignin; the concentration of the crude acidic lignin in water is 5g / 100ml.

[0089] Phosphoric acid and urea are added to a reactor, and the temperature is raised to 60°C and maintained at a constant temperature until the solid melts. Then, after 2 minutes, acidic lignin is added to the reactor, and after stirring for 1 minute, an appropriate amount of dimethyl silicone oil is added. The temperature is raised to 95°C and maintained at a constant temperature until fine bubbles are generated. The reactants in the reactor are transferred into porcelain, and the reaction is continued at 200°C for 4 hours. The reaction is stopped, and the flame retardant is obtained by cooling and crushing. The weight ratio of phosphoric acid, urea and acidic lignin is 1:1:0.2.

[0090] Preparation of PVC wire and cable materials:

[0091] 60 parts of the flame retardant of Comparative Example 4, 10 parts of calcium zinc stabilizer, 40 parts of octyl phthalate, 50 parts of calcium carbonate, 2 parts of zinc stearate and 2 parts of antioxidant were mixed in a high-speed mixer for 2 minutes, and then the mixture was ball-milled at high speed in a ball mill for 4 hours to obtain a mixture with a particle size of 8 microns; 100 parts of PVC and a crushing and mixing aid were mixed at high speed in a high-speed mixer for 3 minutes to obtain a primary mixture; the primary mixture was melt-blended, extruded and granulated through a twin-screw extruder to obtain a PVC wire and cable material; wherein, the twin-screw extruder has a zone of 110°C, a zone of 135°C, a zone of 155°C, a zone of 165°C, a zone of 175°C, a zone of 180°C, a die of 175°C, and a screw speed of 150rpm.

[0092] Comparative Example 5

[0093] The only difference from Example 1 is that the flame retardant in Comparative Example 5 does not use pentaerythritol and acidic lignin, and the rest is the same as Example 1;

[0094] Preparation of flame retardant (using phosphoric acid and urea):

[0095] Add phosphoric acid and urea into a reactor, raise the temperature to 60°C, keep the temperature constant until the solid melts, start stirring after 2 minutes, add an appropriate amount of dimethyl silicone oil after stirring for 1 minute; raise the temperature to 95°C, keep the temperature constant until small bubbles are generated, move the reactants in the reactor into porcelain, and continue to react at 200°C for 4 hours, stop the reaction, cool and crush to obtain a flame retardant; wherein, the weight ratio of phosphoric acid to urea is 1:1.

[0096] Preparation of PVC wire and cable materials:

[0097] Mix 60 parts of the flame retardant of Comparative Example 5, 10 parts of calcium zinc stabilizer, 40 parts of octyl phthalate, 50 parts of calcium carbonate, 2 parts of zinc stearate and 2 parts of antioxidant in a high-speed mixer for 2 minutes, and then high-speed ball mill the mixture in a ball mill for 4 hours to obtain a mixture with a particle size of 8 microns; 100 parts of PVC and a crushing and mixing aid are mixed at high speed in a high-speed mixer for 3 minutes to obtain a primary mixture; the primary mixture is melt-blended, extruded and granulated through a twin-screw extruder to obtain a PVC wire and cable material; wherein, the twin-screw extruder has a temperature of 110°C in zone 1, 135°C in zone 2, 155°C in zone 3, 165°C in zone 4, 175°C in zone 5, 180°C in zone 6, a die head of 175°C, and a screw speed of 150rpm.

[0098] Comparative Example 6

[0099] The only difference from Example 1 is that the powder additive of the PVC wire and cable material in Comparative Example 6 is not ball-milled, and the rest is the same as Example 1;

[0100] Preparation of flame retardant:

[0101] The crude acidic lignin is boiled in hot water at 80°C for 1.5 hours, filtered while hot, washed, and dried to obtain purified acidic lignin; the concentration of the crude acidic lignin in water is 5g / 100ml.

[0102] Phosphoric acid and urea are added to a reactor, and the temperature is raised to 60°C and maintained at a constant temperature until the solid melts. Then, after 2 minutes, acidic lignin and pentaerythritol are added to the reactor, and after stirring for 1 minute, an appropriate amount of dimethyl silicone oil is added; the temperature is raised to 95°C and maintained at a constant temperature until fine bubbles are generated, the reactants in the reactor are transferred into porcelain, and the reaction is continued at 200°C for 4 hours, the reaction is stopped, and the flame retardant is obtained by cooling and crushing; wherein, the weight ratio of phosphoric acid, urea, acidic lignin and pentaerythritol is 1:1:0.2:0.05.

[0103] Preparation of PVC wire and cable materials:

[0104] 100 parts of PVC and 60 parts of flame retardant of Comparative Example 6, 10 parts of calcium zinc stabilizer, 40 parts of octyl phthalate, 50 parts of calcium carbonate, 2 parts of zinc stearate and 2 parts of antioxidant were mixed in a high mixer for 2 minutes to obtain a precursor; the precursor was melt-blended, extruded and granulated through a twin-screw extruder to obtain a PVC wire and cable material; wherein, the twin-screw extruder has a zone of 110°C, a zone of 135°C, a zone of 355°C, a zone of 465°C, a zone of 175°C, a zone of 6180°C, a die of 175°C and a screw speed of 150rpm.

[0105] Experimental test:

[0106] The PVC wire and cable materials prepared in the embodiment and the comparative example were subjected to tensile strength (GB / T 1040-2006 standard), oxygen index (GB / T2406-93 standard) and ultraviolet light aging (GB / T 16422.3-2014 standard) tests, and the results are shown in Table 1. As can be seen from Table 1, the embodiment has higher tensile strength, elongation at break, and oxygen index than the comparative example, and the strength reduction rate after ultraviolet light radiation is lower, indicating that the environmentally friendly flame-retardant PVC wire and cable material prepared in the embodiment of the present invention well solves the problems of toxicity, poor ultraviolet light resistance, and weak mechanical strength of the existing PVC wire and cable materials.

[0107]

[0108] In summary:

[0109] Comparative Example 1, no flame retardant was added;

[0110] Comparative Example 2, acidic lignin was not used;

[0111] Comparative Example 3, using crude acidic lignin that was not boiled with water;

[0112] Comparative Example 4, pentaerythritol was not used;

[0113] Comparative Example 5, pentaerythritol and acidic lignin were not used;

[0114] In Comparative Example 6, the powder additive was not ball-milled.

[0115] Compared with Comparative Examples 1-6, the tensile strength, elongation at break, oxygen index, and tensile strength retention rate after 50 days of ultraviolet radiation in Example 1 are greatly improved. Therefore, it can be known that phosphoric acid, urea, pentaerythritol and acidic lignin are indispensable raw materials for the flame retardant of the present invention, and there are interactions, reactions and synergistic effects between them.

[0116] Comparative Example 6 was not ball-milled, and its tensile strength, elongation at break, oxygen index, and tensile strength retention rate after 50 days of ultraviolet radiation were greatly reduced. Example 1 ball-milled the powder additive and controlled the particle size, which also greatly improved its tensile strength, elongation at break, oxygen index, and retention rate.

[0117] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0118] The above-mentioned embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A flame retardant for PVC wire and cable materials, characterized in that: The invention is prepared from the following raw materials: urea, phosphoric acid, acidic lignin and pentaerythritol.

2. A flame retardant for PVC wire and cable materials according to claim 1, characterized in that: The weight ratio of the urea, phosphoric acid, acidic lignin and pentaerythritol is 1:(0.8-1):(0.1-0.5):(0.01-0.05).

3. A flame retardant for PVC wire and cable materials according to claim 2, characterized in that: The acidic lignin is obtained by the following steps: boiling crude acidic lignin in hot water, stirring, filtering, washing, and drying while hot to obtain the acidic lignin; The ratio of the crude acidic lignin to water is (0-10) g:100 ml.

4. The method for preparing a flame retardant for PVC wire and cable materials according to any one of claims 1 to 3, characterized in that: The steps include: Step 1: Add phosphoric acid and urea into the reactor, stir and heat, add acidic lignin and pentaerythritol after the urea is completely dissolved, stir, and add defoamer; Step 2: Heat to 95-115℃ while stirring, keep constant temperature until bubbles appear, then stop the reaction; Step 3: Transfer the product obtained in the second step into a porcelain container and react at 190-220° C. for 3-5 hours to obtain the flame retardant for PVC wire and cable materials.

5. An environmentally friendly flame-retardant PVC wire and cable material, characterized in that: The invention is prepared from the following raw materials in parts by weight: 100 parts of polyvinyl chloride (PVC), 5-15 parts of calcium zinc stabilizer, 40-50 parts of octyl phthalate, 40-80 parts of calcium carbonate, 15-70 parts of the flame retardant for PVC wire and cable materials according to any of claims 1-3, 2-3 parts of zinc stearate, and 2-5 parts of antioxidant.

6. The environmentally friendly flame-retardant PVC wire and cable material according to claim 5, characterized in that: The amount of the flame retardant used for PVC wire and cable materials is 25-55 parts.

7. The environmentally friendly flame-retardant PVC wire and cable material according to claim 5, characterized in that: The particle size of the mixture of flame retardant, calcium zinc stabilizer, octyl phthalate, calcium carbonate, zinc stearate and antioxidant used for PVC wire and cable materials is 2-15 microns, preferably 5-10 microns.

8. A method for preparing an environmentally friendly flame-retardant PVC wire and cable material as claimed in any one of claims 5 to 7, characterized in that: The steps include: The flame retardant, calcium zinc stabilizer, octyl phthalate, calcium carbonate, zinc stearate and antioxidant used for PVC wire and cable materials are mixed in a high-speed mixer, and then the mixture is ball-milled in a ball mill to obtain a grinding and mixing aid; Mix PVC and crushing and mixing aids in a high-speed mixer to obtain a primary mixture; The primary mixture is melt-blended, extruded and granulated through a twin-screw extruder to obtain the environmentally friendly flame-retardant PVC wire and cable material.

9. The method for preparing an environmentally friendly flame-retardant PVC wire and cable material according to claim 8, characterized in that: The flame retardant, calcium zinc stabilizer, octyl phthalate, calcium carbonate, zinc stearate and antioxidant mixture for PVC wire and cable materials are milled at high speed in a ball mill for 2-6 hours, preferably 3-4 hours.

10. The method for preparing an environmentally friendly flame-retardant PVC wire and cable material according to claim 8, characterized in that: The temperature parameter of the extruder is 110-185° C., and the screw speed of the extruder is 50 rpm-250 rpm.

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