Cellulose acetate modified PVC wood-plastic material and preparation method thereof

Abstract

The invention provides a cellulose acetate modified PVC wood-plastic material and a preparation method thereof, and relates to the technical field of PVC wood-plastic composite materials. The cellulose acetate modified PVC wood-plastic material comprises the following materials in parts by weight: 80-120 parts of PVC resin, 30-50 parts of wood flour, 15-30 parts of calcium carbonate, 15-20 parts of cellulose acetate, 1-6 parts of a foaming agent, 5-10 parts of a stabilizer, 1-2 parts of a coupling agent, 5-10 parts of a processing aid and 1-4 parts of a lubricant. Cellulose acetate is generally applied to the field of porous membrane preparation, while cellulose acetate is applied to the field of PVC wood-plastic material systems in order to improve the thermal stability, processing convenience and mechanical properties of the PVC wood-plastic material.

Description

Technical Field

[0001] The invention relates to the technical field of wood-plastic composite materials, and in particular to a cellulose acetate modified PVC wood-plastic material and a preparation method thereof. Background Art

[0002] Wood-plastic composite materials are a new type of green and environmentally friendly composite materials developed in recent years in response to social and environmental needs. It organically combines the advantages of two different materials and has the dual characteristics of wood and thermoplastic resin. It can have a wood-like appearance, surface gluing, painting, and sawing performance like wood, and can be formed and processed like thermoplastic resin, with good processing performance and mechanical properties. PVC wood-plastic material is the main type of wood-plastic composite material, that is, a wood-plastic composite material formed by processing polyvinyl chloride (PVC) and plant fiber materials (usually wood powder).

[0003] PVC wood-plastic materials can be used in architectural decoration such as wall panels, door panels, and floors; furniture manufacturing such as cabinets, bookcases, and wardrobes; packaging and transportation such as packaging boxes and pallets; medical treatment; agriculture and other fields. When PVC wood-plastic materials are used in specific fields such as architectural decoration, higher requirements are placed on their mechanical properties and thermal stability.

[0004] Based on this, the present invention discloses a cellulose acetate modified PVC wood-plastic material and a preparation method thereof, which improves the mechanical properties and thermal stability of the PVC wood-plastic material. Summary of the invention

[0005] 1. Technical issues to be solved

[0006] In view of the deficiencies in the prior art, the present invention provides a cellulose acetate modified PVC wood-plastic material and a preparation method thereof, which improves the mechanical properties and thermal stability of the PVC wood-plastic material.

[0007] (II) Technical solution

[0008] To achieve the above objectives, the present invention is implemented through the following technical solutions:

[0009] The cellulose acetate modified PVC wood-plastic material comprises the following materials in parts by weight: 80-120 parts of PVC resin, 30-50 parts of wood flour, 15-30 parts of calcium carbonate, 15-20 parts of cellulose acetate, 1-6 parts of foaming agent, 5-10 parts of stabilizer, 1-2 parts of coupling agent, 5-10 parts of processing aid and 1-4 parts of lubricant.

[0010] Preferably, before the cellulose acetate is added into the system, the cellulose acetate is modified to introduce acetal cross-linking units, and the specific method is as follows:

[0011] 1) dissolving cellulose acetate in tetrahydrofuran;

[0012] 2) mixing styrene, 2-hydroxyethyl methacrylate and 1,4-cyclohexanedimethanol divinyl ether uniformly;

[0013] 3) adding cellulose acetate dissolved in tetrahydrofuran to the above mixture, and then adding dibenzoyl peroxide to the mixture and stirring evenly;

[0014] 4) Pre-curing in an oven at 90-100° C. for 4-5 hours to obtain a pre-cured sample, and then curing the sample to obtain modified cellulose acetate.

[0015] Preferably, the modified cellulose acetate is a covalent polymer network with acetal as a cross-linking unit.

[0016] Preferably, the mass ratio of styrene, 2-hydroxyethyl methacrylate and 1,4-cyclohexanedimethanol divinyl ether is (15-30):2:1.

[0017] Preferably, the added amount of the cellulose acetate is 35-45 times the total mass of the styrene, 2-hydroxyethyl methacrylate, and 1,4-cyclohexanedimethanol divinyl ether.

[0018] Preferably, the specific method of the curing treatment in step 4) is: post-curing at 110° C. for 2 h, curing at 140° C. for 2 h, and curing at 170° C. for 2 h.

[0019] Preferably, the foaming agent is azodicarbonamide or calcium bicarbonate.

[0020] Preferably, the coupling agent is titanate or aluminate.

[0021] Preferably, the lubricant is paraffin or silicone oil.

[0022] Preferably, the stabilizer is a calcium zinc stabilizer or an organic tin stabilizer.

[0023] The preparation method of cellulose acetate modified PVC wood-plastic material is specifically as follows:

[0024] The wood powder with a particle size of 100-120 mesh is screened, and after the wood powder is dried, it is first mixed evenly with PVC resin, calcium carbonate, cellulose acetate, and lubricant, and then a stabilizer, a foaming agent, a coupling agent, and a processing aid are added. After the materials are evenly mixed, they are taken out and added into an extruder for granulation to obtain a finished product.

[0025] (III) Beneficial effects

[0026] The present invention provides a cellulose acetate modified PVC wood plastic material and a preparation method thereof. Compared with the prior art, the present invention has the following beneficial effects:

[0027] The technical solution of the present invention is to add cellulose acetate to the PVC wood-plastic material system. Cellulose acetate is usually used in the field of porous film preparation, and the present invention applies it to the field of PVC wood-plastic material system to improve the thermal stability, processing convenience and mechanical properties of the PVC wood-plastic material. DETAILED DESCRIPTION

[0028] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention are clearly and completely described. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. 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.

[0029] The embodiment of the present invention improves the mechanical properties and thermal stability of the PVC wood-plastic material by providing a cellulose acetate-modified PVC wood-plastic material and a preparation method thereof.

[0030] In order to better understand the above technical solution, the above technical solution will be described in detail below in conjunction with specific implementation methods.

[0031] The raw materials used in the technical solution of the present invention are all purchased from cooperative manufacturers.

[0032] Embodiment 1:

[0033] The cellulose acetate modified PVC wood-plastic material comprises the following materials in parts by weight: 80 parts of PVC resin, 30 parts of wood flour, 15 parts of calcium carbonate, 15 parts of cellulose acetate, 1 part of azodicarbonamide, 5 parts of calcium zinc stabilizer, 1 part of titanate, 5 parts of processing aid and 1 part of paraffin.

[0034] The preparation method of cellulose acetate modified PVC wood-plastic material is specifically as follows:

[0035] S1. Cellulose acetate modification:

[0036] 1) dissolving cellulose acetate in tetrahydrofuran;

[0037] 2) mixing styrene, 2-hydroxyethyl methacrylate and 1,4-cyclohexanedimethanol divinyl ether in a molar ratio of 15:2:1;

[0038] 3) adding cellulose acetate dissolved in tetrahydrofuran to the mixture, wherein the amount of cellulose acetate added is 35 times the total mass of the mixture, and further adding dibenzoyl peroxide to the mixture, and stirring evenly;

[0039] 4) Pre-curing in an oven at 90° C. for 5 h to obtain a pre-cured sample, and then curing the sample, specifically: post-curing at 110° C. for 2 h, curing at 140° C. for 2 h, and curing at 170° C. for 2 h, to obtain a covalent polymer network with acetal as a cross-linking unit.

[0040] S2.PVC wood plastic material preparation:

[0041] The wood powder with a particle size of 100-120 mesh is screened, and after the wood powder is dried, it is first mixed evenly with PVC resin, calcium carbonate, modified cellulose acetate, and paraffin, and then calcium zinc stabilizer, azodicarbonamide, titanate and processing aid are added. After the materials are evenly mixed, they are taken out and added into an extruder for granulation to obtain a finished product.

[0042] Embodiment 2:

[0043] The cellulose acetate modified PVC wood-plastic material comprises the following materials in parts by weight: 100 parts of PVC resin, 40 parts of wood flour, 22 parts of calcium carbonate, 17 parts of cellulose acetate, 4 parts of azodicarbonamide, 7 parts of organic tin stabilizer, 1 part of titanate, 7 parts of processing aid and 3 parts of paraffin.

[0044] The preparation method of cellulose acetate modified PVC wood-plastic material is specifically as follows:

[0045] S1. Cellulose acetate modification:

[0046] 1) dissolving cellulose acetate in tetrahydrofuran;

[0047] 2) mixing styrene, 2-hydroxyethyl methacrylate and 1,4-cyclohexanedimethanol divinyl ether in a molar ratio of 25:2:1;

[0048] 3) adding cellulose acetate dissolved in tetrahydrofuran to the mixture, wherein the amount of cellulose acetate added is 40 times the total mass of the mixture, and then adding dibenzoyl peroxide to the mixture and stirring evenly;

[0049] 4) Pre-curing in an oven at 90° C. for 4 h to obtain a pre-cured sample, and then curing the sample, specifically: post-curing at 110° C. for 2 h, curing at 140° C. for 2 h, and curing at 170° C. for 2 h, to obtain a covalent polymer network with acetal as a cross-linking unit.

[0050] S2.PVC wood plastic material preparation:

[0051] The wood powder with a particle size of 100-120 mesh is screened, and after the wood powder is dried, it is first mixed evenly with PVC resin, calcium carbonate, modified cellulose acetate, and paraffin, and then an organic tin stabilizer, titanate, azodicarbonamide and a processing aid are added. After the materials are evenly mixed, they are taken out and added into an extruder for granulation to obtain a finished product.

[0052] Example 3

[0053] The cellulose acetate modified PVC wood-plastic material comprises the following materials in parts by weight: 120 parts of PVC resin, 50 parts of wood flour, 30 parts of calcium carbonate, 20 parts of cellulose acetate, 6 parts of calcium bicarbonate, 10 parts of calcium zinc stabilizer, 2 parts of aluminate, 10 parts of processing aid, and 4 parts of silicone oil.

[0054] The preparation method of cellulose acetate modified PVC wood-plastic material is specifically as follows:

[0055] S1. Cellulose acetate modification:

[0056] 1) dissolving cellulose acetate in tetrahydrofuran;

[0057] 2) mixing styrene, 2-hydroxyethyl methacrylate and 1,4-cyclohexanedimethanol divinyl ether in a molar ratio of 30:2:1;

[0058] 3) adding cellulose acetate dissolved in tetrahydrofuran to the mixture, wherein the amount of cellulose acetate added is 45 times the total mass of the mixture, and then adding dibenzoyl peroxide to the mixture and stirring evenly;

[0059] 4) Pre-curing in an oven at 100° C. for 4 h to obtain a pre-cured sample, and then curing the sample, specifically: post-curing at 110° C. for 2 h, curing at 140° C. for 2 h, and curing at 170° C. for 2 h, to obtain a covalent polymer network with acetal as a cross-linking unit.

[0060] S2.PVC wood plastic material preparation:

[0061] The wood powder with a particle size of 100-120 mesh is screened, and after the wood powder is dried, it is first mixed evenly with PVC resin, calcium carbonate, modified cellulose acetate, and silicone oil, and then calcium zinc stabilizer, calcium bicarbonate, aluminate and processing aid are added. After the materials are evenly mixed, they are taken out and added into an extruder for granulation to obtain a finished product.

[0062] Embodiment 4 is different from Embodiment 2 in that:

[0063] Cellulose acetate is not modified.

[0064] Comparative Example 1 is different from Example 2 in that:

[0065] Do not add cellulose acetate to the PVC wood-plastic material system.

[0066] Comparative Example 2 is different from Example 2 in that:

[0067] The molar ratio of styrene, 2-hydroxyethyl methacrylate and 1,4-cyclohexanedimethanol divinyl ether is 12:2:1.

[0068] Comparative Example 3 is different from Example 2 in that:

[0069] The molar ratio of styrene, 2-hydroxyethyl methacrylate and 1,4-cyclohexanedimethanol divinyl ether is 32:2:1.

[0070] Comparative Example 4 is different from Example 2 in that:

[0071] The added amount of cellulose acetate is 30 times the total mass of styrene, 2-hydroxyethyl methacrylate, and 1,4-cyclohexanedimethanol divinyl ether.

[0072] Comparative Example 5 is different from Example 2 in that:

[0073] The added amount of cellulose acetate is 50 times the total mass of styrene, 2-hydroxyethyl methacrylate, and 1,4-cyclohexanedimethanol divinyl ether.

[0074] Comparative Example 6 is different from Example 2 in that:

[0075] Before cellulose acetate is added into the system, cellulose acetate is modified to introduce borate cross-linking units. The specific introduction method is as follows:

[0076] Dissolve cellulose acetate in tetrahydrofuran; dissolve polyvinyl alcohol and boric acid in water, add the solution into tetrahydrofuran solution, stir the solution by machine for 30 minutes until the viscosity increases, then stir manually for 10 minutes; dry the obtained viscous solution in an oven at 45°C for 48 hours to complete the preparation.

[0077] Among them, m(cellulose acetate):m(polyvinyl alcohol):m(boric acid)=100:2:2.

[0078] Performance test data

[0079] The following performance tests were performed on the samples prepared by the preparation methods in Examples 1-4 and Comparative Examples 1-5:

[0080] 1. Mechanical properties test:

[0081] The PVC wood-plastic material samples were tensile tested and analyzed at room temperature using a universal material testing machine (model: 5567) from Instron, UK, to obtain the tensile strength and elongation at break data. The sample size was 60 mm (length) × 5 mm (width) × 0.3 mm (thickness), the gauge length was 20 mm, and the crosshead speed was 2 mm min -1 .

[0082] 2. High temperature tensile performance retention rate

[0083] According to ISO 527-2-2012 standard, the initial tensile strength of the sample at room temperature was tested (tensile rate 50mm / min), and then the sample was subjected to high temperature treatment at a temperature of 120°C for a test time of 2000h. If powdering occurred during the test, it was recorded as "powdering". If powdering did not occur, the high temperature treated sample was tested for aging tensile strength according to the above method after the temperature dropped to room temperature. The retention rate was recorded statistically. If it exceeded 100%, it was uniformly recorded as ">100%", where the retention rate was greater than 100%, indicating that the material performance did not significantly decay after aging, and the material had excellent heat resistance. The calculation formula for the high temperature tensile performance retention rate is: (tensile strength after aging / initial tensile strength) × 100%.

[0084] Table 1 - Sample test data of Examples 1-4 and Comparative Examples 1-5

[0085] sample Tensile strength(MPa) Elongation at break (%) High temperature tensile properties retention rate (%) Example 1 63.2 24.8 ＞100 Example 2 65.4 25.0 ＞100 Example 3 64.5 24.1 ＞100 Example 4 55.6 18.3 ＞100 Comparative Example 1 44.7 10.7 85 Comparative Example 2 59.4 22.4 98 Comparative Example 3 61.5 23.0 97 Comparative Example 4 60.8 22.1 93 Comparative Example 5 60.3 21.9 ＞100 Comparative Example 6 60.9 22.2 ＞100

[0086] From the test data in Table 1, we can see that:

[0087] 1. The experimental data of the samples of Examples 1-3 and Comparative Example 1 show that the technical solution of the present invention adds cellulose acetate to the PVC wood-plastic material system, which is beneficial to improving the mechanical properties and heat resistance stability of the system.

[0088] 2. The experimental data of Examples 2 and 4 show that the modification of cellulose acetate by introducing acetal bond cross-linking units is beneficial to further enhance the mechanical properties and heat resistance of the material system. This is because cellulose acetate itself has the defects of narrow thermal processing window and difficult melt processing. After modification, the processing stability can be improved, thereby improving the overall performance of the PVC wood-plastic material system.

[0089] 3. The experimental data of Example 2 and Comparative Examples 2-3 show that the addition amount of styrene, 2-hydroxyethyl methacrylate, and 1,4-cyclohexanedimethanol divinyl ether will affect the mechanical properties and heat stability of cellulose acetate, and further affect the mechanical properties and heat stability of the PVC wood-plastic material system. Therefore, it is necessary to control the addition ratio of the three components within an appropriate range to maximize their effectiveness.

[0090] 4. The experimental data of Example 2 and Comparative Examples 4-5 show that the amount of cellulose acetate added during modification, that is, the amount of cross-linking of acetal cross-linking units, will affect the modification performance of cellulose acetate, and further affect the mechanical properties and heat stability of the PVC wood-plastic material system. Therefore, it is necessary to reasonably control the amount of cross-linking units.

[0091] 5. The experimental data of Example 2 and Comparative Example 6 show that cellulose acetate can be modified by other means, that is, by introducing other cross-linking units such as borate. The performance of the modified cellulose acetate is also greatly improved, but its performance improvement is not as good as the performance improvement by introducing acetal cross-linking units.

[0092] In summary, compared with the prior art, the present invention has the following beneficial effects:

[0093] 1. The technical solution of the present invention is to add cellulose acetate to the PVC wood-plastic material system. Cellulose acetate is generally used in the field of porous film preparation, and the present invention applies it to the field of PVC wood-plastic material system to improve the thermal stability, processing convenience and mechanical properties of PVC wood-plastic materials.

[0094] 2. Since cellulose acetate itself has certain processing defects, in order to improve this defect, cellulose acetate is further modified by introducing acetal cross-linking units to reduce the processing difficulty of cellulose acetate, improve the compatibility of cellulose acetate in the system and other properties, and at the same time improve the mechanical properties and heat resistance of cellulose acetate, thereby further improving the mechanical properties and heat resistance stability of the PVC wood-plastic material system.

[0095] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the existence of other identical elements in the process, method, article or device including the elements.

[0096] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A cellulose acetate modified PVC wood-plastic material, characterized in that: The invention comprises the following materials in parts by weight: 80-120 parts of PVC resin, 30-50 parts of wood flour, 15-30 parts of calcium carbonate, 15-20 parts of cellulose acetate, 1-6 parts of foaming agent, 5-10 parts of stabilizer, 1-2 parts of coupling agent, 5-10 parts of processing aid and 1-4 parts of lubricant.

2. The cellulose acetate modified PVC wood-plastic material according to claim 1, characterized in that: Before the cellulose acetate is put into the system, the cellulose acetate is modified to introduce acetal cross-linking units. The specific method is as follows: 1) dissolving cellulose acetate in tetrahydrofuran; 2) mixing styrene, 2-hydroxyethyl methacrylate and 1,4-cyclohexanedimethanol divinyl ether uniformly; 3) adding cellulose acetate dissolved in tetrahydrofuran to the above mixture, and then adding dibenzoyl peroxide to the mixture and stirring evenly; 4) Pre-curing in an oven at 90-100° C. for 4-5 hours to obtain a pre-cured sample, and then curing the sample to obtain modified cellulose acetate.

3. The cellulose acetate modified PVC wood-plastic material according to claim 2, characterized in that: The modified cellulose acetate is a covalent polymer network with acetal as a cross-linking unit.

4. The cellulose acetate modified PVC wood-plastic material according to claim 2, characterized in that: The mass ratio of styrene, 2-hydroxyethyl methacrylate and 1,4-cyclohexanedimethanol divinyl ether is (15-30):2:

1.

5. The cellulose acetate modified PVC wood-plastic material according to claim 1, characterized in that: The added amount of the cellulose acetate is 35-45 times the total mass of the styrene, 2-hydroxyethyl methacrylate and 1,4-cyclohexanedimethanol divinyl ether.

6. The cellulose acetate modified PVC wood-plastic material according to claim 2, characterized in that: The specific method of the curing treatment in step 4) is: post-curing at 110° C. for 2 hours, curing at 140° C. for 2 hours, and curing at 170° C. for 2 hours.

7. The cellulose acetate modified PVC wood-plastic material according to claim 1, characterized in that: The foaming agent is azodicarbonamide or calcium bicarbonate.

8. The cellulose acetate modified PVC wood-plastic material according to claim 1, characterized in that: The coupling agent is titanate or aluminate.

9. The cellulose acetate modified PVC wood-plastic material according to claim 1, characterized in that: The lubricant is paraffin or silicone oil, and the stabilizer is a calcium zinc stabilizer or an organic tin stabilizer.

10. The method for preparing the cellulose acetate modified PVC wood-plastic material according to any one of claims 1 to 9, characterized in that: Specifically: The wood powder with a particle size of 100-120 mesh is screened, and after the wood powder is dried, it is first mixed evenly with PVC resin, calcium carbonate, cellulose acetate, and lubricant, and then a stabilizer, a foaming agent, a coupling agent, and a processing aid are added. After the materials are evenly mixed, they are taken out and added into an extruder for granulation to obtain a finished product.