PVC wood-plastic foaming floor and forming process thereof

Abstract

The invention relates to the technical field of production of wood-plastic foaming floors, in particular to a PVC wood-plastic foaming floor and a forming process thereof. The process comprises wood powder modification; heating the modified wood flour to 100 DEG C, then adding PVC resin, a foaming agent, a modifier and a lubricant into the modified wood flour, uniformly mixing, and cooling to obtain a mixture; the PVC wood-plastic foaming floor with the length being 1000 mm, the width being 120 mm and the thickness being 12 mm is finally prepared through the steps that the PVC wood-plastic foaming floor and the PVC wood-plastic foaming floor are mixed through a double-screw extruder in a melting mode, and a plate is pressed through a plate vulcanizing machine. The obtained PVC wood-plastic foaming floor has certain tensile strength and impact strength, and meets various requirements for producing the wood-plastic foaming floor.

Description

Technical Field

[0001] The present invention relates to the technical field of the production of wood-plastic foamed floors, and particularly relates to a PVC wood-plastic foamed floor and its forming process. Background Art

[0002] Wood-plastic materials, i.e., substituting wood with plastics, have the advantages of the wood texture, beauty and corrosion resistance of wood, and also have the advantages of protecting forest resources and reducing production costs. The production process of wood-plastic materials has always been a research hotspot in the plastic market. Among them, the wood-plastic foamed material has a good cell structure inside, which can blunt the crack tip and further prevent crack propagation, overcoming the disadvantages of large brittleness, weak impact strength and low elongation at break of ordinary wood-plastic materials. In addition, the mechanical properties of wood-plastic foamed materials exceed those of wood, but the resin dosage is greatly reduced, saving production costs.

[0003] The wood-plastic foamed material has a low density, has the effects of sound insulation and heat insulation. At the same time, the foaming process endows the product with accurate appearance dimensions and excellent surface texture, which is convenient for installation and is widely used in fields such as building materials for houses, imitation wood floors, exterior wall insulation and logistics packaging. Among wood-plastic foamed materials, PVC wood-plastic foamed materials have high strength, excellent quality and low price, and also have a certain flame retardancy. At present, there are still many problems in the composite molding of wood fibers and thermoplastic plastics, and the most important one is the interfacial compatibility problem. At the same time, the production process of PVC wood-plastic foamed materials has disadvantages such as high melt viscosity, poor fluidity, and easy occurrence of melt fracture and poor foaming. Summary of the Invention

[0004] In view of the problems existing in the background art, the present invention provides a forming process for a PVC wood-plastic foamed floor, which includes the following steps:

[0005] Step a: The wood powder is dried in a forced-air drying oven at 100°C for 3 to 4 hours, taken out and sealed for standby;

[0006] Step b: Deionized water is added to the dried wood powder in a ratio of 1:2, stirred evenly, and then citric acid is added under stirring, reacted at 25°C for 2 hours, then slowly heated to 100°C and reacted for 3 to 5 hours, and after cooling, filtered by suction and dried to obtain preliminarily modified wood powder;

[0007] Step c: Maleic anhydride grafted polypropylene is added to the preliminarily modified wood powder in a ratio of 10:3 by mass to the wood powder, and stirred evenly to obtain modified wood powder;

[0008] Step d: The modified wood powder is heated to 100°C, and then PVC resin, foaming agent, modifier and lubricant are added thereto. After mixing evenly, it is cooled to obtain a mixed material;

[0009] Step e: Add the mixed materials into a twin-screw extruder for melt mixing, press with a flat vulcanizing machine, and perform hot pressing and cold pressing for 2 minutes respectively to form a PVC wood-plastic foamed floor with a length, width, and thickness of 1000 mm, 120 mm, and 12 mm respectively.

[0010] Preferably, in step b, the mass ratio of the addition amounts of wood powder and citric acid is selected from one or more of 10:1; 11:1; 10.5:1.

[0011] Preferably, in step d, the blowing agent is an AC blowing agent, and the co-blowing agent is selected from one or more of zinc fatty acid soap, lead oxide, stearic acid, and ethanolamine.

[0012] More preferably, the preparation method of the modified blowing agent is as follows: Dissolve the AC blowing agent in ethanolamine, heat to 60 °C to ensure complete dissolution; filter while it is hot to remove insoluble impurities to prevent impurities from affecting the crystallization purity; slowly cool the filtrate to precipitate the AC blowing agent for recrystallization; filter the recrystallized AC blowing agent, and the ratio of the addition amounts of the blowing agent to the co-blowing agent is 8:1.

[0013] Preferably, in step d, the modifiers include a stabilizer, an impact modifier, and a lubricant.

[0014] More preferably, the mass ratio of the stabilizer, impact modifier, and lubricant is 4:0.8:0.3.

[0015] Preferably, in step d, the mixing conditions are high-speed stirring at 1000 r / min for 0.5 hours and then low-speed stirring at 200 r / min for 0.5 hours, followed by cooling.

[0016] Preferably, in step e, the main motor speed of the twin-screw extruder is 15 r / min, the feeding speed is 2 r / min, the extrusion processing temperature is 150 °C, the die temperature is 175 °C, and hot pressing is performed for 5 minutes.

[0017] Compared with the prior art, the present invention has the following beneficial effects:

[0018] Since the main components of wood fiber, such as cellulose, hemicellulose, and lignin, contain a large number of hydroxyl groups, the adhesion between the hydrophilic wood fiber filler and the hydrophobic thermoplastic matrix interface is poor, further resulting in a significant decrease in the tensile strength and impact strength of the composite material. After heating and drying the wood powder in the present invention, further treatment is carried out to remove hydroxyl groups by reacting with excessive citric acid, and a PVC-based wood-plastic foamed floor is prepared with the modified wood powder. The interfacial compatibility between the modified wood powder and the PVC resin is improved, and at the same time, the hygroscopicity of the wood powder is reduced, and the dispersibility of the wood powder in the plastic matrix is improved.

[0019] In addition, in the preparation of foamed sheets, the formulation of the foaming agent has a great influence on the quality and cost of the product. For wood-plastic foamed floors, during the foaming process, affected by the agglomeration of wood powder, phenomena such as uneven cell distribution and incomplete cell structure will occur. Dissolving the AC foaming agent in ethanolamine and then recrystallizing it by cooling can obtain AC foaming agent with smaller and more uniform particle size. The average pore diameter of the cells in the wood-plastic foamed floor decreases, the distribution becomes narrower, and the uniformity of the cells is improved. Therefore, the tensile and impact strengths of the PVC foamed floor are increased, thereby improving the mechanical properties of the wood-plastic composite material. Detailed implementation mode

[0020] The embodiments of the technical solutions of the present invention will be described in detail below in conjunction with the embodiments. The following embodiments are only used to more clearly illustrate the technical solutions of the present invention, so they are only examples and cannot be used to limit the protection scope of the present invention.

[0021] It should be noted that the experimental methods used in the implementation examples are all conventional methods unless otherwise specified; the materials, reagents, etc. used can be obtained from commercial channels unless otherwise specified.

[0022] In the present invention, unless otherwise specified, all the technical features and preferred features mentioned in this article can be combined with each other to form a new technical solution.

[0023] In the present invention, unless otherwise specified, all the steps mentioned in this article can be carried out in sequence or randomly, but preferably in sequence; for example, the method includes steps (a) and (b), which means that the method can include steps (a) and (b) carried out in sequence, or can also include steps (b) and (a) carried out in sequence; for example, it is mentioned that the method may further include step (c), which means that step (c) can be added to the method in any order. For example, the method can include steps (a), (b) and (c), or can also include steps (a), (c) and (b), or can also include steps (c), (a) and (b), etc.

[0024] In the present invention, unless otherwise specified, the specific numerical values and specific substances in the embodiments in this article can be combined with other features in the description part of this article; for example, if the specification mentions that the reaction temperature is 10-100 °C, and the reaction temperature mentioned in the embodiment is 20 °C, then it can be considered that the range of 10-20 °C, or the range of 20-100 °C has been specifically disclosed in this article, and this range can be combined with other features in the description part to form a new technical solution.

[0025] Example 1;

[0026] Dry 200 g of wood powder in a forced-air drying oven at 100 °C for 3-4 hours, take it out and seal it for later use;

[0027] Add 400 ml of deionized water to the dried wood powder, stir evenly, then add 20 g of citric acid under stirring, react at 25 °C for 2 hours, then slowly raise the temperature to 100 °C and react for 3 - 5 hours. After cooling, filter by suction and dry to obtain preliminarily modified wood powder;

[0028] Add 60 g of maleic anhydride grafted polypropylene to the preliminarily modified wood powder and stir evenly to obtain modified wood powder;

[0029] Heat the modified wood powder to 100 °C, then add 200 g of PVC resin, 20 g of AC foaming agent, 2.5 g of fatty acid zinc soap, 20 g of stabilizer, 4 g of impact modifier, and 1.5 g of lubricant thereto. Stir at a high speed of 1000 r / min for 0.5 hour and then switch to a low speed of 200 r / min and stir for 0.5 hour. After mixing evenly, cool to obtain a mixed material;

[0030] Set the main machine speed of the twin-screw extruder to 15 r / min, the feeding speed to 2 r / min, the extrusion processing temperature to 150 °C, and the die temperature to 175 °C. Add the mixed material to the twin-screw extruder for melt mixing, and use a flat vulcanizing machine to press the plate, and hot press for 5 min and cold press for 2 min respectively to form a PVC wood-plastic foamed floor with a length, width, and thickness of 1000 mm, 120 mm, and 12 mm respectively.

[0031] Example 2;

[0032] Blast-dry 220 g of wood powder in a blast drying oven at 100 °C for 3 - 4 hours, take it out and seal it for standby;

[0033] Add 400 ml of deionized water to the dried wood powder, stir evenly, then add 20 g of citric acid under stirring, react at 25 °C for 2 hours, then slowly raise the temperature to 100 °C and react for 3 - 5 hours. After cooling, filter by suction and dry to obtain preliminarily modified wood powder;

[0034] Add 60 g of maleic anhydride grafted polypropylene to the preliminarily modified wood powder and stir evenly to obtain modified wood powder;

[0035] Heat the modified wood powder to 100 °C, then add 200 g of PVC resin, 20 g of AC foaming agent, 2.5 g of fatty acid zinc soap, 20 g of stabilizer, 4 g of impact modifier, and 1.5 g of lubricant thereto. Stir at a high speed of 1000 r / min for 0.5 hour and then switch to a low speed of 200 r / min and stir for 0.5 hour. After mixing evenly, cool to obtain a mixed material;

[0036] Set the main machine speed of the twin-screw extruder to 15 r / min, the feeding speed to 2 r / min, the extrusion processing temperature to 150 °C, and the die temperature to 175 °C. Add the mixed material into the twin-screw extruder for melting and mixing, and use a flat vulcanizing machine to press the plate, hot press for 5 min and cold press for 2 min respectively to form a PVC wood-plastic foamed floor with a length, width and thickness of 1000 mm, 120 mm and 12 mm respectively.

[0037] Example three;

[0038] Dry 200 g of wood powder in a blast drying oven at 100 °C for 3 - 4 hours, take it out and seal it for later use;

[0039] Add 400 ml of deionized water to the dried wood powder, stir evenly, then add 20 g of citric acid under stirring, react at 25 °C for 2 hours, then slowly heat up to 100 °C and react for 3 - 5 hours, cool and then filter and dry to obtain preliminarily modified wood powder;

[0040] Add 60 g of maleic anhydride grafted polypropylene to the preliminarily modified wood powder and stir evenly to obtain modified wood powder;

[0041] Heat the modified wood powder to 100 °C, then add 200 g of PVC resin, 20 g of AC foaming agent, 2.5 g of ethanolamine, 20 g of stabilizer, 4 g of impact modifier, 1.5 g of lubricant, stir at high speed of 1000 r / min for 0.5 hour and then change to low speed of 200 r / min and stir for 0.5 hour, cool after mixing evenly to obtain a mixed material;

[0042] Set the main machine speed of the twin-screw extruder to 15 r / min, the feeding speed to 2 r / min, the extrusion processing temperature to 150 °C, and the die temperature to 175 °C. Add the mixed material into the twin-screw extruder for melting and mixing, and use a flat vulcanizing machine to press the plate, hot press for 5 min and cold press for 2 min respectively to form a PVC wood-plastic foamed floor with a length, width and thickness of 1000 mm, 120 mm and 12 mm respectively.

[0043] Example four;

[0044] Dry 200 g of wood powder in a blast drying oven at 100 °C for 3 - 4 hours, take it out and seal it for later use;

[0045] Add 400 ml of deionized water to the dried wood powder, stir evenly, then add 19 g of citric acid under stirring, react at 25 °C for 2 hours, then slowly heat up to 100 °C and react for 3 - 5 hours, cool and then filter and dry to obtain preliminarily modified wood powder;

[0046] Add 60 g of maleic anhydride grafted polypropylene to the preliminarily modified wood powder and stir evenly to obtain modified wood powder;

[0047] Heat the modified wood powder to 100 °C, then add 200 g of PVC resin, 20 g of AC foaming agent, 2.5 g of zinc soap of fatty acid, 20 g of stabilizer, 4 g of impact modifier, 1.5 g of lubricant thereto, stir at a high speed of 1000 r / min for 0.5 hour and then change to stir at a low speed of 200 r / min for 0.5 hour, and cool after mixing evenly to obtain a mixed material;

[0048] Set the main machine speed of the twin-screw extruder to 15 r / min, the feeding speed to 2 r / min, the extrusion processing temperature to 150 °C, and the die temperature to 175 °C. Add the mixed material into the twin-screw extruder for melt mixing, use a flat vulcanizing machine press plate, hot press for 5 min and cold press for 2 min respectively for molding to obtain a PVC wood-plastic foamed floor with a length, width and thickness of 1000 mm, 120 mm and 12 mm respectively.

[0049] Example Five;

[0050] Blast-dry 200 g of wood powder in a blast drying oven at 100 °C for 3 - 4 hours, take it out and seal it for standby;

[0051] Add 400 ml of deionized water to the dried wood powder, stir evenly, then add 20 g of citric acid under stirring, react at 25 °C for 2 hours, then slowly raise the temperature to 100 °C and react for 3 - 5 hours, and filter and dry by suction after cooling to obtain preliminarily modified wood powder;

[0052] Add 60 g of maleic anhydride grafted polypropylene to the preliminarily modified wood powder and stir evenly to obtain modified wood powder;

[0053] Heat the modified wood powder to 100 °C, then add 200 g of PVC resin, 20 g of AC foaming agent, 2.5 g of lead oxide, 20 g of stabilizer, 4 g of impact modifier, 1.5 g of lubricant thereto, stir at a high speed of 1000 r / min for 0.5 hour and then change to stir at a low speed of 200 r / min for 0.5 hour, and cool after mixing evenly to obtain a mixed material;

[0054] Set the main machine speed of the twin-screw extruder to 15 r / min, the feeding speed to 2 r / min, the extrusion processing temperature to 150 °C, and the die temperature to 175 °C. Add the mixed material into the twin-screw extruder for melt mixing, use a flat vulcanizing machine press plate, hot press for 5 min and cold press for 2 min respectively for molding to obtain a PVC wood-plastic foamed floor with a length, width and thickness of 1000 mm, 120 mm and 12 mm respectively.

[0055] Example Six;

[0056] Blast-dry 200 g of wood powder in a blast drying oven at 100 °C for 3 - 4 hours, take it out and seal it for standby;

[0057] Add 400 ml of deionized water to the dried wood powder, stir evenly, then add 20 g of citric acid under stirring, react at 25 °C for 2 hours, then slowly raise the temperature to 100 °C and react for 3 - 5 hours. After cooling, filter by suction and dry to obtain preliminarily modified wood powder;

[0058] Add 60 g of maleic anhydride grafted polypropylene to the preliminarily modified wood powder and stir evenly to obtain modified wood powder;

[0059] Heat the modified wood powder to 100 °C, then add 200 g of PVC resin, 20 g of AC foaming agent, 2.5 g of stearic acid, 20 g of stabilizer, 4 g of impact modifier, and 1.5 g of lubricant thereto. Stir at a high speed of 1000 r / min for 0.5 hours and then switch to a low speed of 200 r / min and stir for 0.5 hours. After mixing evenly, cool to obtain a mixed material;

[0060] Set the main machine speed of the twin - screw extruder to 15 r / min, the feeding speed to 2 r / min, the extrusion processing temperature to 150 °C, and the die temperature to 175 °C. Add the mixed material to the twin - screw extruder for melt mixing, and use a flat vulcanizing machine to press the plate, hot - press for 5 min and cold - press for 2 min respectively to form a PVC wood - plastic foamed floor with a length, width, and thickness of 1000 mm, 120 mm, and 12 mm respectively.

[0061] Performance testing

[0062] Flexural strength testing

[0063] The flexural strength test is carried out by using a three - point loading simply - supported beam, that is, placing the specimen on two supports and applying a concentrated load on the specimen between the two supports to deform the specimen until the strength at the time of failure is the flexural strength.

[0064] Table 1 Flexural strength test results

[0065] Serial number Flexural strength (MPa) Example 1 70 Example 2 71 Example 3 68 Example 4 70 Example 5 71 Example 6 69

[0066] Tensile strength testing

[0067] The tensile property test is carried out according to the large - specimen tensile test method in the plastic tensile test method in ASTM D 938 - 03. The test instrument is an RGT - 20A electronic universal mechanical testing machine, and the tensile speed is 5 mm / min.

[0068] Table 2 Tensile strength test results

[0069] Serial number Tensile strength (MPa) Example 1 45 Example 2 48 Example 3 44 Example 4 46 Example 5 49 Example 6 46

[0070] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than limiting them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the various embodiments of the present invention, and they should all be covered by the scope of the claims and the description of the present invention.

Claims

1. A molding process for PVC wood plastic foam floor, characterized in that: The following steps are involved: Step a: drying the wood powder in a 100°C blast drying oven for 3-4 hours, taking it out, and sealing it for later use; Step b: adding deionized water to the dried wood powder in a ratio of 1:2, stirring evenly, then adding citric acid under stirring, reacting at 25°C for 2 hours, then slowly heating to 100°C and reacting for 3 to 5 hours, cooling, filtering and drying to obtain preliminary modified wood powder; Step c: adding maleic anhydride grafted polypropylene to the preliminary modified wood powder at a mass ratio of 10:3 to the wood powder, and stirring evenly to obtain modified wood powder; Step d: heating the modified wood powder to 100° C., then adding PVC resin, foaming agent, modifier and lubricant thereto, mixing evenly and cooling to obtain a mixture; Step e: adding the mixed material into a twin-screw extruder for melt mixing, and using a flat vulcanizing press to perform hot pressing and cold pressing for 2 minutes to form a PVC wood-plastic foamed floor with a length, width and thickness of 1000 mm, 120 mm and 12 mm respectively.

2. The molding process of a PVC wood plastic foam floor according to claim 1, characterized in that: In the step b, the mass ratio of wood powder to citric acid added is selected from one or more of 10:1; 11:1; 10.5:

1.

3. The molding process of a PVC wood plastic foam floor according to claim 1, characterized in that: In the step d, the foaming agent is a modified AC foaming agent, and the auxiliary foaming agent is selected from one or more of fatty acid zinc soap, lead oxide, stearic acid and ethanolamine.

4. The molding process of a PVC wood plastic foam floor according to claim 3, characterized in that: The modified foaming agent preparation method comprises: dissolving the AC foaming agent in ethanolamine, heating to 60°C to ensure complete dissolution; filtering while hot to remove insoluble impurities to prevent the impurities from affecting the crystal purity; slowly cooling the filtrate to allow the AC foaming agent to recrystallize and precipitate; and filtering the recrystallized AC foaming agent.

5. The molding process of a PVC wood plastic foam floor according to claim 3, characterized in that: The ratio of the modified foaming agent to the auxiliary foaming agent added is 8:

1.

6. The molding process of a PVC wood plastic foam floor according to claim 1, characterized in that: The modifier in step d comprises a stabilizer, an impact modifier and a lubricant.

7. The molding process of a PVC wood plastic foam floor according to claim 5, characterized in that: The mass ratio of the stabilizer, the impact modifier and the lubricant is 4:0.8:0.

3.

8. The molding process of a PVC wood plastic foam floor according to claim 1, characterized in that: The mixing conditions in step d are: high-speed stirring at 1000 r / min for 0.5 hour, then switching to low-speed stirring at 200 r / min for 0.5 hour, and cooling.

9. The molding process of the PVC wood plastic foam floor according to claim 1, characterized in that: In the step e, the main engine speed of the twin-screw extruder is 15r / min, the feed speed is 2r / min, the extrusion processing temperature is 150°C, the mold temperature is 175°C, and the hot pressing is 5min.

10. A molding process for PVC wood plastic foam floor, characterized in that: The PVC wood plastic foam floor is prepared by the method described in any one of claims 1 to 9.