Special composite lubricant for PE (polyethylene) and PP (polypropylene) wood plastic and preparation method of special composite lubricant

Abstract

The invention relates to the technical field of wood-plastic composite materials, and particularly discloses a special composite lubricant for PE and PP wood-plastic and a preparation method thereof, the special composite lubricant comprises the following components: EVA solid waste oligomer, polyethylene wax, pentaerythritol stearate, inorganic filler, alkyl quaternary ammonium salt and short-chain fatty acid ester; a residual coordination catalyst in an EVA solid waste oligomer is activated by alkyl quaternary ammonium salt under a heating condition, in-situ polymerization / grafting reaction is carried out through catalysis, nitrogen-containing polar chain segments are directionally introduced, hydroxyl sites are introduced through chain transfer reaction, and the like, so that the dispersity of the fiber is improved, and the interface adhesion is enhanced; by adding the modified polyethylene wax, the short-chain fatty acid ester and the pentaerythritol stearate, friction in a melt can be synergistically adjusted, interface layering can be reduced, the modified polyethylene wax can improve the dispersing performance of the wood flour, and the flame retardance of the wood flour can be improved. The prepared composite lubricant can be compatible with wood flour and PE resin, and is high in stability.

Description

Technical Field

[0001] This invention relates to the field of wood-plastic composite materials technology, specifically to a PE / PP wood-plastic composite lubricant and its preparation method. Background Technology

[0002] Common lubricants for wood-plastic composites include fatty acids and their salts, waxes, and amides, which are used to improve melt flowability, reduce melt viscosity, promote resin particle sliding, and facilitate demolding. Stearate lubricants have good compatibility with resins, but the extensive use of alkaline stearates can deplete the acidic maleic anhydride-grafted PE compatibilizer in the system, affecting the compatibility between wood flour and polymers. PE waxes are commonly used, but have poor compatibility with wood flour. Amides have good internal and external lubrication properties, improving the surface finish and demolding performance of products, but they may decompose at high temperatures, producing an odor, and have limited compatibility with some resins. The core pain point in wood-plastic processing is the poor compatibility between wood flour (containing a large number of hydroxyl groups and being highly polar) and thermoplastic resins (such as PE and PP, which are non-polar), resulting in high melt viscosity and high processing resistance (easily sticking to equipment and high energy consumption).

[0003] The sources of EVA solid waste oligomers mainly include the disposal of EVA products and waste materials generated during the production process. EVA materials are widely used in footwear, toys, packaging, and other fields. Due to their extensive use, the waste problem has gradually become prominent. Traditional treatment methods are mainly landfill or incineration, which not only wastes resources but also causes serious environmental pollution.

[0004] Therefore, there is a need for a lubricant for wood-plastic products to solve the problems of insufficient product stability of current lubricants and poor compatibility between previous lubrication systems and PE resin and wood powder. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a PE / PP wood-plastic composite lubricant and its preparation method, so as to solve the problem that the existing wood-plastic lubricants cannot be compatible with both wood powder and resin powder.

[0006] This invention solves the above-mentioned technical problems. The present invention provides a PE and PP wood-plastic composite lubricant, which contains the following components in parts by weight: 90-110 parts of EVA solid waste oligomer, 45-55 parts of modified polyethylene wax, 45-55 parts of pentaerythritol stearate, 3-5 parts of inorganic filler, and 4-7 parts of alkyl quaternary ammonium salt.

[0007] The inorganic filler is a compound of calcium carbonate (particle size 1-3μm) and wollastonite (length-to-diameter ratio 8-12) in a mass ratio of 1:1. Calcium carbonate and wollastonite can synergistically react with pentaerythritol stearate and modified polyethylene wax, respectively, to reduce viscosity, improve stability and provide directional lubrication.

[0008] The short-chain fatty acid ester is one of propylene glycol hexanoate, glyceryl monooctanoate, and dibutyl sebacate.

[0009] The alkyl quaternary ammonium salt is one of dodecyl dimethyl benzyl ammonium chloride, hexadecyl trimethyl ammonium chloride, and octadecyl trimethyl ammonium chloride;

[0010] The EVA solid waste oligomer contains the following components by mass percentage: 25-30% low molecular weight ethylene-vinyl acetate copolymer, 55-60% low molecular weight ethylene, ≤10% ethylene oil, and ≤0.4% catalyst residue.

[0011] The modified polyethylene wax is prepared by mixing polyethylene wax under vacuum at 70-90℃ with 10-14wt% of a composite unsaturated alcohol, and then purging with nitrogen gas at a flow rate of 0.1-0.3L / min for protection. The mixture is first premixed by heating to 130-140℃ and stirring for 10-20min, then heated to undergo gradient reflux reaction for 4-6h, cooled to 90-100℃, and precipitated with alcohol. The precipitate is then filtered and dried to obtain the final product.

[0012] Hydrophilic groups (-OH) and flexible aliphatic chains (C10-C18) are directionally introduced into the hydrophobic backbone (-CH2-CH2-) of polyethylene wax to form a three-dimensional molecular structure of "hydrophobic backbone-hydrophilic side chain-flexible spacer chain". The hydrophobic backbone can be tightly wrapped with the nonpolar resin molecular chain through van der Waals forces to achieve compatibility with the resin; the hydrophilic side chain (-OH) can undergo hydrogen bonding or dehydration condensation reaction with the hydroxyl groups (-OH) on the surface of wood flour. The hydroxyl groups are easy to form ether bonds, which increases hydrophilicity and can couple with the hydroxyl groups of wood flour.

[0013] The composite unsaturated alcohol is obtained by compounding 10-undecen-1-ol and hydroxystearyl alcohol in a mass ratio of 2-4:1.

[0014] The temperature of the gradient reflux is 160-170℃;

[0015] This invention also provides a method for preparing a PE / PP wood-plastic composite lubricant, comprising the following steps:

[0016] Step 1: Premix solid waste EVA oligomers with alkyl quaternary ammonium salts and inorganic fillers at a speed of 2000-3000 r / min for 5-8 min, then heat under low pressure;

[0017] Step 2: After complete melting, add modified polyethylene wax, short-chain fatty acid ester and pentaerythritol stearate, stir and heat to 150-170℃, and after complete melting and uniform mixing, keep the temperature constant for 1 hour.

[0018] Step 3: The product is processed into a solid powder or flake-like wood-plastic composite lubricant using a specialized liquid delivery device;

[0019] The low-pressure heating is heating at a pressure of 0.1-0.4 MPa and a temperature of 120-130℃ for 60-80 minutes.

[0020] The beneficial effects of the present invention are: (1) The present invention solves the problem of recycling and utilizing EVA solid waste oligomers and realizes the resource utilization of solid waste;

[0021] (2) In the composite lubricant of this invention, the residual coordination catalyst in EVA solid waste oligomers is activated by alkyl quaternary ammonium salts under heating conditions, catalyzing the in-situ polymerization / grafting reaction of unsaturated olefins in low molecular weight polyethylene and ethylene oil, directionally introducing nitrogen-containing polar segments of alkyl quaternary ammonium salts, and introducing hydroxyl sites through chain transfer reactions. Furthermore, the long-chain alkyl groups of the alkyl quaternary ammonium salts are entangled and compatible with the hydrophobic segments of low molecular weight ethylene-vinyl acetate copolymer and low molecular weight polyethylene, while the cationic groups form electrostatic attraction with the hydroxyl groups of wood flour. The VA polar segments and ester chains therein interact with plant fibers. The hydroxyl groups of the fibers form hydrogen bonds or undergo physical adsorption, improving fiber dispersibility and enhancing interfacial adhesion. This strengthens the compatibility between the PE matrix and the fibers, improves flowability and product surface gloss, and prevents product precipitation. Inorganic fillers bind to polar sites through hydrogen bonds, reducing the migration rate of small molecule components and improving compatibility. The addition of modified polyethylene wax, short-chain fatty acid esters, and pentaerythritol stearate synergistically regulates internal melt friction and reduces interfacial delamination. Modified polyethylene wax also improves the dispersibility of wood flour. The resulting composite lubricant is compatible with both wood flour and PE resin and exhibits high stability. Attached Figure Description

[0022] Figure 1 This is a rheological curve of the lubricant. Detailed Implementation

[0023] The present invention will be further described in detail below through specific implementation examples. It should be understood that these embodiments are only used to illustrate the present invention and are not intended to limit the scope of protection of the present invention. After reading the present invention, any modifications of the present invention in various equivalent forms by those skilled in the art fall within the scope of the appended claims.

[0024] Unless otherwise specified, all raw materials and reagents used in this invention are from the conventional market.

[0025] Example 1

[0026] A method for preparing a PE / PP wood-plastic composite lubricant includes the following steps:

[0027] Step 1: 110 parts of solid waste EVA oligomer, 5 parts of dodecyl dimethyl benzyl ammonium chloride, and 4 parts of inorganic filler were premixed at 2500 r / min for 6 min, and then heated at 0.3 MPa and 120℃ for 70 min; the inorganic filler was a mixture of calcium carbonate (particle size 1-3 μm) and wollastonite (aspect ratio 8-12) in a mass ratio of 1:1.

[0028] Step 2: After complete melting, add 50 parts of modified polyethylene wax, 2 parts of propylene glycol hexanoate, and 50 parts of pentaerythritol stearate. Stir and heat to 160°C, and after complete melting and uniform mixing, maintain the temperature for 1 hour. The modified polyethylene wax is prepared by vacuum mixing polyethylene wax at 80°C with 12 wt% of a composite unsaturated alcohol. Nitrogen gas is introduced at a flow rate of 0.2 L / min for protection. The mixture is first heated to 135°C and stirred for 15 min for premixing, then heated to 165°C for gradient reflux reaction for 5 h. The mixture is then cooled to 95°C for alcohol precipitation, filtered, and the precipitate is dried. The composite unsaturated alcohol is obtained by compounding 10-undecen-1-ol and hydroxystearyl alcohol in a mass ratio of 3:1.

[0029] Step 3: The product is made into a solid powder or flake-like wood-plastic composite lubricant using a special liquid delivery device.

[0030] Example 2

[0031] A method for preparing a PE / PP wood-plastic composite lubricant includes the following steps:

[0032] Step 1: 90 parts of solid waste EVA oligomer, 4 parts of hexadecyltrimethylammonium chloride, and 3 parts of inorganic filler were premixed at 2000 r / min for 5 min, and then heated at 0.1 MPa and 120℃ for 60 min; the inorganic filler was a mixture of calcium carbonate (particle size 1 μm) and wollastonite (aspect ratio 8-12) in a mass ratio of 1:1.

[0033] Step 2: After complete melting, add 45 parts of modified polyethylene wax, 1 part of glyceryl caprylate monoester, and 45 parts of pentaerythritol stearate. Stir and heat to 150°C, and after complete melting and uniform mixing, maintain the temperature for 1 hour. The modified polyethylene wax is prepared by vacuum mixing polyethylene wax at 70°C with 10 wt% of a composite unsaturated alcohol. Nitrogen gas is introduced at a flow rate of 0.1 L / min for protection. The mixture is first heated to 130°C and stirred for 10 min for premixing, then heated to 160°C for gradient reflux reaction for 4 h. The mixture is then cooled to 90°C for alcohol precipitation, filtered, and the precipitate is dried. The composite unsaturated alcohol is obtained by compounding 10-undecen-1-ol and hydroxystearyl alcohol in a mass ratio of 2:1.

[0034] Step 3: The product is made into a solid powder or flake-like wood-plastic composite lubricant using a special liquid delivery device.

[0035] Example 3

[0036] A method for preparing a PE / PP wood-plastic composite lubricant includes the following steps:

[0037] Step 1: 110 parts of solid waste EVA oligomer, 7 parts of octadecyltrimethylammonium chloride, and 5 parts of inorganic filler were premixed at 3000 r / min for 8 min, and then heated at 0.4 MPa and 130℃ for 80 min; the inorganic filler was a mixture of calcium carbonate (particle size 1-3 μm) and wollastonite (aspect ratio 8-12) in a mass ratio of 1:1.

[0038] Step 2: After complete melting, add 55 parts modified polyethylene wax, 3 parts dibutyl sebate, and 55 parts pentaerythritol stearate. Stir and heat to 170°C, and after complete melting and uniform mixing, maintain the temperature for 1 hour. The modified polyethylene wax is prepared by vacuum mixing polyethylene wax at 90°C with 14 wt% of a composite unsaturated alcohol. Nitrogen gas is introduced at a flow rate of 0.3 L / min for protection. The mixture is first heated to 140°C and stirred for 20 minutes for premixing, then heated to 160-170°C for gradient reflux reaction for 6 hours. The mixture is then cooled to 100°C for alcohol precipitation, filtered, and the precipitate is dried. The composite unsaturated alcohol is obtained by compounding 10-undecen-1-ol and hydroxystearyl alcohol in a mass ratio of 4:1.

[0039] Step 3: The product is made into a solid powder or flake-like wood-plastic composite lubricant using a special liquid delivery device.

[0040] Example 4

[0041] A method for preparing a PE / PP wood-plastic composite lubricant includes the following steps:

[0042] Step 1: 90 parts of solid waste EVA oligomer, 7 parts of hexadecyltrimethylammonium chloride, and 3 parts of inorganic filler were premixed at 3000 r / min for 5 min, and then heated at 0.4 MPa and 120℃ for 80 min; the inorganic filler was a mixture of calcium carbonate (particle size 1-3 μm) and wollastonite (aspect ratio 8-12) in a mass ratio of 1:1.

[0043] Step 2: After complete melting, add 46 parts of modified polyethylene wax, 3 parts of propylene glycol hexanoate, and 52 parts of pentaerythritol stearate. Stir and heat to 150°C, and after complete melting and uniform mixing, maintain the temperature for 1 hour. The modified polyethylene wax is prepared by vacuum mixing polyethylene wax at 70°C with 11 wt% of a composite unsaturated alcohol. Nitrogen gas is introduced at a flow rate of 0.1 L / min for protection. The mixture is first heated to 130°C and stirred for 10 min for premixing, then heated to 170°C for gradient reflux reaction for 4 h. The mixture is then cooled to 100°C for alcohol precipitation, filtered, and the precipitate is dried. The composite unsaturated alcohol is obtained by compounding 10-undecen-1-ol and hydroxystearyl alcohol in a mass ratio of 2:1.

[0044] Step 3: The product is made into a solid powder or flake-like wood-plastic composite lubricant using a special liquid delivery device.

[0045] Example 5

[0046] A method for preparing a PE / PP wood-plastic composite lubricant includes the following steps:

[0047] Step 1: 105 parts of solid waste EVA oligomer, 5 parts of octadecyltrimethylammonium chloride, and 4 parts of inorganic filler were premixed at 2000 r / min for 5 min, and then heated at 0.4 MPa and 130℃ for 70 min; the inorganic filler was a mixture of calcium carbonate (particle size 1-3 μm) and wollastonite (aspect ratio 8-12) in a mass ratio of 1:1.

[0048] Step 2: After complete melting, add 53 parts modified polyethylene wax, 2 parts propylene glycol hexanoate, and 47 parts pentaerythritol stearate. Stir and heat to 150°C, and after complete melting and uniform mixing, maintain the temperature for 1 hour. The modified polyethylene wax is prepared by vacuum mixing polyethylene wax at 70°C with 13 wt% of a composite unsaturated alcohol, and protecting it with nitrogen gas at a flow rate of 0.3 L / min. First, heat to 130°C and stir for 15 minutes for premixing, then heat to reflux for 5 hours, cool to 90°C, precipitate alcohol, filter, and dry the precipitate. The composite unsaturated alcohol is obtained by compounding 10-undecen-1-ol and hydroxystearyl alcohol in a mass ratio of 2:1.

[0049] Step 3: The product is made into a solid powder or flake-like wood-plastic composite lubricant using a special liquid delivery device.

[0050] Comparative Example 1

[0051] The difference between Comparative Example 1 and Example 1 is that Comparative Example 1 uses an equal amount of polyethylene wax instead of modified polyethylene wax, while everything else remains the same.

[0052] Comparative Example 2

[0053] The difference between Comparative Example 2 and Example 1 is that no inorganic filler was added in Comparative Example 2, while everything else remained the same.

[0054] Comparative Example 3

[0055] The difference between Comparative Example 3 and Example 1 is that no alkyl quaternary ammonium salt was added in Comparative Example 3, while everything else remained the same.

[0056] Comparative Example 4

[0057] The difference between Comparative Example 4 and Example 1 is that Comparative Example 4 does not contain short-chain fatty acids, while everything else remains the same.

[0058] 1. The composite lubricant prepared in Example 1 and a commercially available ordinary lubricant were tested using a torque rheometer. The test results are as follows: Figure 1 As shown, the composite lubricant of the present invention has lower balancing torque and balancing time, indicating that the composite lubricant prepared by the present invention has high processing stability and good lubrication effect.

[0059] II. Technical Specifications: The performance of wood-plastic composite products produced with lubricants prepared in the examples and comparative examples was tested in accordance with GB / T 29418-2012 "Testing of Physical and Mechanical Properties of Wood-Plastic Composite Products".

[0060] Softening point test: Determination standard: GB / T 2794-1995;

[0061] Viscosity test: Measurement standard: GB / T 4507-2014;

[0062] Surface gloss: The surface gloss of the product was measured using a gloss meter (60° angle);

[0063] Water absorption rate: The water absorption rate of the product after 24 hours was tested according to GB / T 17657;

[0064] Demolding performance: The demolding force was measured using standard injection molding specimens (the maximum force when the mold and the product are pulled apart at a constant speed using a tensile tester).

[0065] Table 1 Performance of Composite Lubricants

[0066]

[0067]

[0068] As shown in Table 1, the composite lubricant prepared by this invention has a high softening point, making it suitable for high-temperature processing environments. It also exhibits good flow properties at 104℃. The composite lubricant prepared by this invention can improve the gloss, demolding performance, and waterproof performance of wood-plastic products, indicating that the composite lubricant has good interfacial sealing with wood flour and PE powder and good compatibility.

[0069] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A composite lubricant specifically for PE and PP wood-plastic composites, characterized in that, It includes the following components by weight: 90-110 parts of EVA solid waste oligomer, 45-55 parts of modified polyethylene wax, 45-55 parts of pentaerythritol stearate, 3-5 parts of inorganic filler, 4-7 parts of alkyl quaternary ammonium salt, and 1-3 parts of short-chain fatty acid ester.

2. The PE / PP wood-plastic composite lubricant according to claim 1, characterized in that, The modified polyethylene wax is prepared by mixing polyethylene wax under vacuum at 70-90℃ with 10-14wt% of a composite unsaturated alcohol, and then purging with nitrogen gas at a flow rate of 0.1-0.3L / min for protection. The mixture is first premixed by heating to 130-140℃ and stirring for 10-20 minutes, then heated to undergo gradient reflux reaction for 4-6 hours, cooled to 90-100℃, and precipitated with alcohol. The precipitate is then filtered and dried to obtain the final product.

3. The PE / PP wood-plastic composite lubricant according to claim 2, characterized in that, The composite unsaturated alcohol is obtained by compounding 10-undecen-1-ol and hydroxystearyl alcohol in a mass ratio of 2-4:

1.

4. The PE / PP wood-plastic composite lubricant according to claim 2, characterized in that, The temperature of the gradient reflux is 160-170℃.

5. The PE / PP wood-plastic composite lubricant according to claim 1, characterized in that, The inorganic filler is a mixture of calcium carbonate (particle size 1-3 μm) and wollastonite (length-to-diameter ratio 8-12) in a mass ratio of 1:

1.

6. The PE / PP wood-plastic composite lubricant according to claim 1, characterized in that, The alkyl quaternary ammonium salt is one of dodecyl dimethyl benzyl ammonium chloride, hexadecyl trimethyl ammonium chloride, and octadecyl trimethyl ammonium chloride.

7. The PE / PP wood-plastic composite lubricant according to claim 1, characterized in that, The EVA solid waste oligomer contains the following components by mass percentage: 25-30% low molecular weight ethylene-vinyl acetate copolymer, 55-60% low molecular weight ethylene, ≤10% ethylene oil, and ≤0.4% catalyst residue.

8. The PE / PP wood-plastic composite lubricant according to claim 1, characterized in that, The short-chain fatty acid ester is one of propylene glycol hexanoate, glyceryl monooctanoate, and dibutyl sebacate.

9. A method for preparing a PE / PP wood-plastic composite lubricant, used to prepare a PE / PP wood-plastic composite lubricant as described in any one of claims 1-8, characterized in that, Includes the following steps: Step 1: Premix solid waste EVA oligomers with alkyl quaternary ammonium salts and inorganic fillers at a speed of 2000-3000 r / min for 5-8 min, then heat under low pressure; Step 2: After complete melting, add modified polyethylene wax, short-chain fatty acid ester and pentaerythritol stearate, stir and heat to 150-170℃, and after complete melting and uniform mixing, keep the temperature constant for 1 hour. Step 3: The product is made into a solid powder or flake-like wood-plastic composite lubricant using a special liquid delivery device.

10. A PE / PP wood-plastic composite lubricant according to claim 1, characterized in that, The low-pressure heating is heating at a pressure of 0.1-0.4 MPa and a temperature of 120-130℃ for 60-80 minutes.

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