Method for preparing composite film from biomass cellulose and composite film

Abstract

The invention provides a method for preparing a composite film from biomass cellulose and the composite film, and relates to the technical field of chemical film new materials. Comprising the following steps: S1, taking 70wt%-95wt% of forage grass cellulose, 0wt%-10wt% of lignocellulose and 5wt%-25wt% of TPU (Thermoplastic Polyurethane), crushing, and uniformly mixing for later use; s2, adding a super-alkali derived ionic liquid and a cosolvent into the biomass cellulose solution, and dissolving the biomass cellulose and TPU mixed material at the temperature lower than 80 DEG C to prepare a cellulose mixed dissolving solution; s3, adding a cosolvent to reduce the interfacial tension of the dissolving solution; s4, filtering and defoaming the cellulose mixed solution to obtain a cellulose mixed glue solution; and S5, pressing the cellulose composite glue solution in film preparation equipment to obtain the high-performance biomass cellulose composite film. By means of the scheme, the high-performance biomass cellulose composite film can be obtained through forage grass.

Description

Technical Field

[0001] The invention relates to the technical field of new chemical film materials, and in particular to a method for preparing a composite film using biomass cellulose and the composite film. Background Art

[0002] At present, the utilization rate of biomass resources is low, and a large amount of heat, water and other resources are consumed during the processing process, and the physical properties of the prepared related products need to be improved. The domestic production of wood pulp and cotton pulp is limited, and finding biomass cellulose to prepare composite biomass films has become a difficult problem facing the membrane material industry. Pasture has many advantages such as drought and waterlogging resistance and rich in biomass cellulose. How to comprehensively utilize the biomass resources in pasture to high value and process them into film products and meet the application requirements of membrane materials is a hot topic in current research.

[0003] Grass is a typical C4 plant with high photosynthetic rate and short growth cycle. The annual output of biomass raw materials is quite abundant, and a large amount of surplus biomass cellulose causes waste of biomass resources. In addition, grass biomass cellulose is still in the low-value utilization stage, and the value given to biomass materials is low. Therefore, it is necessary to develop new ways and applications for high-value utilization of grass biomass cellulose. At present, the efficiency and quality of composite films prepared by grass are relatively poor, and it is difficult to meet the requirements. Summary of the invention

[0004] The invention discloses a method for preparing a composite film by using biomass cellulose, aiming at developing a new way of high-value utilization of forage biomass cellulose and preparing a biomass cellulose film.

[0005] The present invention adopts the following scheme: A method for preparing a composite film using biomass cellulose comprises the following steps: S1, take 70wt%~95wt% of grass cellulose, 0wt%~10wt% of wood cellulose, and 5wt%~25wt% of TPU, grind them and mix them evenly for later use; S2, adding a superbase-derived ionic liquid and a co-solvent thereto, wherein the superbase-derived ionic liquid is a synthesis of 1,8-diazabicyclo[5.4.0]undec-7-ene and levulinic acid, dissolving the biomass cellulose and TPU mixture at a temperature below 80° C. to prepare a cellulose mixed solution; S3. In the process of preparing the cellulose mixed solution, a co-solvent is added to reduce the interfacial tension of the solution to achieve a homogeneous dispersion effect of the molecules of the solution; S4, filtering and degassing the cellulose mixed solution to obtain a cellulose mixed glue solution; S5. Place the cellulose composite glue solution into a film preparation device for pressing to obtain a high-performance biomass cellulose composite film.

[0006] Furthermore, the TPU includes 30wt%-50wt% of diphenylmethane diisocyanate, 30wt%-50wt% of polytetramethylene ether glycol, and 10wt%-30wt% of butanediol.

[0007] Furthermore, in step S1, 80wt%~95wt% of forage cellulose, 0wt%~5wt% of wood cellulose, and 5wt%~15wt% of TPU are used.

[0008] Furthermore, in step S2, in the superbase derivative ionic liquid reagent, the concentrations of 1,8-diazabicyclo[5.4.0]undec-7-ene and levulinic acid are both 99%, and the proportion of 1,8-diazabicyclo[5.4.0]undec-7-ene is 50wt%~80wt%, and the proportion of levulinic acid is 20wt%-50wt%.

[0009] Furthermore, in step S2, the proportion of 1,8-diazabicyclo[5.4.0]undec-7-ene is 50wt%-65wt%, and the proportion of levulinic acid is 35wt%-50wt%.

[0010] Furthermore, in step S2, the co-solvent is a polar aprotic solvent, and the polar aprotic solvent is 99% dimethyl sulfoxide, or 99% dimethyl imidazolidinone, or 99% hexamethylphosphoramide, or 99% dimethylacetamide.

[0011] Furthermore, in step S3, a cosolvent of an aromatic polyoxyethylene ether compound is added to reduce the interfacial tension of the dissolving solution, and the addition of the cosolvent can improve the quality of the cellulose dissolving solution, reduce the interfacial tension of the dissolving solution, and reduce the number of gel particles in the dissolving solution, thereby improving the adhesion performance of the dissolving solution.

[0012] Furthermore, in step S3, an aromatic polyoxyethylene ether compound with a degree of polymerization of 10 is added during the dissolution process, and the amount used is 0.05% to 2.0% of the total weight of the forage cellulose raw material, TPU and solvent.

[0013] Furthermore, in step S4, the filtration includes pre-filtration and final glue solution filtration, the pre-filtration pressure is lower than 0.75 MPa, and the final glue solution filtration pressure is lower than 1.25 MPa.

[0014] The present invention also provides a composite film formed by any one of the above methods for preparing a composite film using biomass cellulose.

[0015] Beneficial effects: 1. The present invention uses forage cellulose raw materials, which are widely available and inexpensive, effectively alleviating the predicament of insufficient raw materials for existing natural cellulose production, reducing production costs, and meeting the production needs of film manufacturing companies.

[0016] 2. The present invention adds an organic solvent as a co-solvent during the cellulose dissolution process, which effectively reduces the interfacial tension of the dissolving solution, reduces the number of gel particles in the biomass fiber, and improves the performance indicators of the cellulose composite film.

[0017] 3. In the process of cellulose dissolution, the present invention adds a co-solvent of a polar aprotic solvent to effectively reduce the temperature required for the dissolving liquid to dissolve the cellulose and TPU mixture. DETAILED DESCRIPTION

[0018] Example 1 This embodiment provides a method for preparing a composite film using biomass cellulose, comprising the following steps: S1, take 70wt%~95wt% of grass cellulose, 0wt%~10wt% of wood cellulose, and 5wt%~25wt% of TPU, grind them and mix them evenly for later use; wherein the TPU comprises 30wt%-50wt% of diphenylmethane diisocyanate, 30wt%-50wt% of polytetramethylene ether glycol, and 10wt%-30wt% of butanediol; preferably, the grass cellulose is 80wt%~95wt%, the wood cellulose is 0wt%~5wt%, and the TPU is 5wt%~15wt%; S2, adding superbase derived ionic liquid and co-solvent thereto, dissolving the biomass cellulose and TPU mixture at a temperature below 80°C to prepare a cellulose mixed solution; here, the superbase derived ionic liquid is a synthesis of 1,8-diazabicyclo[5.4.0]undec-7-ene and levulinic acid, the concentrations of 1,8-diazabicyclo[5.4.0]undec-7-ene and levulinic acid are both 99%, and the ratio of 1,8-diazabicyclo[5.4.0]undec-7-ene is 50w t%~80wt%, the proportion of levulinic acid is 20wt%-50wt%; preferably, the proportion of 1,8-diazabicyclo[5.4.0]undec-7-ene is 50wt%-65wt%, and the proportion of levulinic acid is 35wt%-50wt%; the co-solvent adopts a polar aprotic solvent, and the polar aprotic solvent can be 99% dimethyl sulfoxide, or 99% dimethylimidazolidinone, or 99% hexamethylphosphoramide, or 99% dimethylacetamide; including but not limited to this; S3. In the process of preparing the cellulose mixed solution, a cosolvent is added to reduce the interfacial tension of the solution to achieve a uniform dispersion of the molecules of the solution; the cosolvent added is an aromatic polyoxyethylene ether compound reagent, which is purchased from Shenyang Haobo Industrial Co., Ltd., model HB3803; adding a cosolvent can improve the quality of the cellulose solution, reduce the interfacial tension of the solution, and reduce the number of gel particles in the solution, thereby improving the adhesion performance of the solution; further, an aromatic polyoxyethylene ether compound with a degree of polymerization of 10 is added during the dissolution process, and the amount used is 0.05% to 2.0% of the total weight of the forage cellulose raw material, TPU and solvent; S4, filtering and degassing the cellulose mixed solution to obtain a cellulose mixed glue solution; the filtration includes pre-filtration and final glue solution filtration, the pre-filtration pressure is lower than 0.75 MPa, and the final glue solution filtration pressure is lower than 1.25 MPa; S5. Place the cellulose composite glue solution into a film preparation device for pressing to obtain a high-performance biomass cellulose composite film.

[0019] Through the scheme of this embodiment, it is possible to prepare high-performance biomass cellulose composite films using forage grass.

[0020] Example 2 The present invention also provides a composite film, which is formed by the method for preparing a composite film using biomass cellulose. Specifically, 85wt% of forage cellulose, 2wt% of wood cellulose, and 13wt% of TPU are taken, crushed and mixed evenly for standby use, wherein the TPU contains 35wt%-45wt% of MDI (diphenylmethane diisocyanate), 35wt%-45wt% of PTMG (polytetramethylene glycol), and 15wt%-25wt% of BDO (butanediol); superbase-derived ionic liquid and cosolvent are added to the materials, and in the superbase-derived ionic liquid reagent, the proportion of 1,8-diazabicyclo[5.4.0]undec-7-ene is 55wt%-60wt%, and the proportion of levulinic acid is 40wt%-45wt%. The co-solvent polar aprotic solvent is 35wt%-45wt% of the superbase derivative ionic liquid / co-solvent / co-solvent ternary system, wherein the co-solvent is dimethyl sulfoxide or dimethyl imidazolinone; the co-solvent aromatic polyoxyethylene ether compound is 0.5% of the total weight of the forage cellulose raw material / TPU and solvent. The biomass cellulose and TPU mixture is dissolved at an ambient temperature of 45-75°C to prepare a cellulose mixed solution; the pre-filtration pressure of the cellulose solution is 0.65MPa, and the secondary filtration pressure is 1.05MPa; the final processed forage cellulose composite solution can be formed into a membrane by hot pressing.

[0021] Example 3 Take 85wt% of grass cellulose, 2wt% of wood cellulose, and 13wt% of TPU, grind and mix them evenly for use, wherein the TPU contains 35-45wt% of MDI (diphenylmethane diisocyanate), 35wt%-45wt% of PTMG (polytetramethylene glycol), and 15wt%-25wt% of BDO (butanediol); add superbase-derived ionic liquid and co-solvent to the materials, and in the superbase-derived ionic liquid reagent, the proportion of 1,8-diazabicyclo[5.4.0]undec-7-ene is 55wt%-60wt%, and the proportion of levulinic acid is 40wt%-45wt%. The co-solvent polar aprotic solvent is 35wt%-45wt% of the superbase-derived ionic liquid / co-solvent / co-solvent ternary system, wherein the co-solvent is dimethyl sulfoxide or dimethyl imidazolinone; the co-solvent aromatic polyoxyethylene ether compound is 0.75% of the total weight of grass cellulose raw material / TPU and solvent. The biomass cellulose and TPU mixture is dissolved at an ambient temperature of 45°C to 75°C to prepare a cellulose mixed solution; the pre-filtration pressure of the cellulose solution is 0.65MPa, and the secondary filtration pressure is 1.05MPa; the final treated forage cellulose composite solution can be formed into a membrane by hot pressing.

[0022] Example 4 Take 85wt% of grass cellulose, 2wt% of wood cellulose, and 13wt% of TPU, grind and mix them evenly for use, wherein the TPU contains 35-45wt% of MDI (diphenylmethane diisocyanate), 35-45wt% of PTMG (polytetramethylene glycol), and 15-25wt% of BDO (butanediol); add superbase-derived ionic liquid and co-solvent to the materials, and in the superbase-derived ionic liquid reagent, the proportion of 1,8-diazabicyclo[5.4.0]undec-7-ene is 55wt%-60wt%, and the proportion of levulinic acid is 40wt%-45wt%. The co-solvent polar aprotic solvent is 35wt%-45wt% of the superbase-derived ionic liquid / co-solvent / co-solvent ternary system, wherein the co-solvent is dimethyl sulfoxide or dimethyl imidazolinone; the co-solvent aromatic polyoxyethylene ether compound is 1.0% of the total weight of grass cellulose raw material / TPU and solvent. The biomass cellulose and TPU mixture is dissolved at an ambient temperature of 45°C to 75°C to prepare a cellulose mixed solution; the pre-filtration pressure of the cellulose solution is 0.65MPa, and the secondary filtration pressure is 1.05MPa; the final treated forage cellulose composite solution can be formed into a membrane by hot pressing.

[0023] Example 5 Take 85wt% of grass cellulose, 2wt% of wood cellulose, and 13wt% of TPU, grind and mix them evenly for use, wherein the TPU contains 35-45wt% of MDI (diphenylmethane diisocyanate), 35-45wt% of PTMG (polytetramethylene glycol), and 15-25wt% of BDO (butanediol); add superbase-derived ionic liquid and co-solvent to the materials, wherein the proportion of 1,8-diazabicyclo[5.4.0]undec-7-ene in the superbase-derived ionic liquid reagent is 55wt%-60wt%, and the proportion of levulinic acid is 40wt%-45wt%. The co-solvent polar aprotic solvent is 35wt%-45wt% of the superbase-derived ionic liquid / co-solvent / co-solvent ternary system, wherein the co-solvent is dimethyl sulfoxide or dimethyl imidazolinone; the co-solvent aromatic polyoxyethylene ether compound is 1.25% of the total weight of grass cellulose raw material / TPU and solvent. The biomass cellulose and TPU mixture is dissolved at an ambient temperature of 45°C to 75°C to prepare a cellulose mixed solution; the pre-filtration pressure of the cellulose solution is 0.65MPa, and the secondary filtration pressure is 1.05MPa; the final treated forage cellulose composite solution can be formed into a membrane by hot pressing.

[0024] Comparative Example 1 Take 85wt% of grass cellulose, 2wt% of wood cellulose, and 13wt% of TPU, grind and mix them evenly for use, wherein the TPU contains 35wt%-45wt% of MDI (diphenylmethane diisocyanate), 35wt%-45wt% of PTMG (polytetramethylene glycol), and 15wt%-25wt% of BDO (butanediol); add superbase derivative ionic liquid and co-solvent to the materials, in which the proportion of 1,8-diazabicyclo[5.4.0]undec-7-ene is 55wt%-60wt% and the proportion of levulinic acid is 40wt%-45wt%. The polar aprotic solvent of the co-solvent is 35wt%-45wt% of the superbase derivative ionic liquid / co-solvent / co-solvent ternary system, wherein the co-solvent is dimethyl sulfoxide or dimethyl imidazolinone; the co-solvent aromatic polyoxyethylene ether compound is 0.05% of the total weight of the grass cellulose raw material, TPU and solvent. The biomass cellulose and TPU mixture is dissolved at an ambient temperature of 45°C to 75°C to prepare a cellulose mixed solution; the pre-filtration pressure of the cellulose solution is 0.65MPa, and the secondary filtration pressure is 1.05MPa; the final treated forage cellulose composite solution can be formed into a membrane by hot pressing.

[0025] Comparative Example 2 Take 85wt% of grass cellulose, 2wt% of wood cellulose, and 13wt% of TPU, grind and mix them evenly for use, wherein the TPU contains 35wt%-45wt% of MDI (diphenylmethane diisocyanate), 35wt%-45wt% of PTMG (polytetramethylene glycol), and 15wt%-25wt% of BDO (butanediol); add superbase derivative ionic liquid and co-solvent to the materials, and in the superbase derivative ionic liquid reagent, the proportion of 1,8-diazabicyclo[5.4.0]undec-7-ene is 55wt%-60wt%, and the proportion of levulinic acid is 40wt%-45wt%. The co-solvent polar aprotic solvent is 35-45wt% of the superbase derivative ionic liquid / co-solvent / co-solvent ternary system, wherein the co-solvent is dimethyl sulfoxide or dimethyl imidazolinone; the co-solvent aromatic polyoxyethylene ether compound is 0.05% of the total weight of grass cellulose raw material, TPU and solvent. The biomass cellulose and TPU mixture is dissolved at an ambient temperature of 45°C to 75°C to prepare a cellulose mixed solution; the pre-filtration pressure of the cellulose solution is 0.65MPa, and the secondary filtration pressure is 1.05MPa; the final treated forage cellulose composite solution can be formed into a membrane by hot pressing.

[0026] Performance Testing: The dry breaking strength and dry breaking elongation of the biomass fibers obtained in Examples 2 to 5 and Comparative Examples 1 to 2 were tested. The results are shown in Table 1.

[0027] Table 1

[0028] It can be seen from Table 1 that when the cellulose composite material is dissolved, when the aromatic polyoxyethylene ether compound is not added to prepare the cellulose film, the prepared biomass cellulose film has a poor dry breaking elongation. As the content of the aromatic polyoxyethylene ether compound increases during dissolution, the fiber dry breaking strength and elongation first increase and then decrease. The best effect is achieved when the content of the aromatic polyoxyethylene ether compound is 0.45wt%.

[0029] It should be understood that the above are only preferred implementations of the present invention, and the protection scope of the present invention is not limited to the above embodiments. All technical solutions under the concept of the present invention belong to the protection scope of the present invention.

Claims

1. A method for preparing a composite film using biomass cellulose, characterized in that: The following steps are involved: S1, take 70wt%~95wt% of grass cellulose, 0wt%~10wt% of wood cellulose, and 5wt%~25wt% of TPU, grind them and mix them evenly for later use; S2, adding a superbase-derived ionic liquid and a co-solvent thereto, wherein the superbase-derived ionic liquid is a synthesis of 1,8-diazabicyclo[5.4.0]undec-7-ene and levulinic acid, dissolving the biomass cellulose and TPU mixture at a temperature below 80° C. to prepare a cellulose mixed solution; S3. In the process of preparing the cellulose mixed solution, a co-solvent is added to reduce the interfacial tension of the solution to achieve a homogeneous dispersion effect of the molecules of the solution; S4, filtering and degassing the cellulose mixed solution to obtain a cellulose mixed glue solution; S5. Place the cellulose composite glue solution into a film preparation device for pressing to obtain a high-performance biomass cellulose composite film.

2. The method for preparing a composite film using biomass cellulose according to claim 1, characterized in that: The TPU comprises 30wt%-50wt% of diphenylmethane diisocyanate, 30wt%-50wt% of polytetramethylene ether glycol, and 10wt%-30wt% of butanediol.

3. The method for preparing a composite film using biomass cellulose according to claim 1, characterized in that: In step S1, 80wt%~95wt% of forage cellulose, 0wt%~5wt% of wood cellulose, and 5wt%~15wt% of TPU are used.

4. The method for preparing a composite film using biomass cellulose according to claim 1, characterized in that: In step S2, in the superbase derivative ionic liquid reagent, the concentrations of 1,8-diazabicyclo[5.4.0]undec-7-ene and levulinic acid are both 99%, and the proportion of 1,8-diazabicyclo[5.4.0]undec-7-ene is 50wt%-80wt%, and the proportion of levulinic acid is 20wt%-50wt%.

5. The method for preparing a composite film using biomass cellulose according to claim 4, characterized in that: In step S2, the proportion of 1,8-diazabicyclo[5.4.0]undec-7-ene is 50wt%-65wt%, and the proportion of levulinic acid is 35wt%-50wt%.

6. The method for preparing a composite film using biomass cellulose according to claim 1, characterized in that: In step S2, the co-solvent is a polar aprotic solvent, and the polar aprotic solvent is 99% dimethyl sulfoxide, or 99% dimethyl imidazolidinone, or 99% hexamethylphosphoramide, or 99% dimethylacetamide.

7. The method for preparing a composite film using biomass cellulose according to claim 1, characterized in that: In step S3, a co-solvent of the aromatic polyoxyethylene ether compound is added to reduce the interfacial tension of the solution.

8. The method for preparing a composite film using biomass cellulose according to claim 7, characterized in that: In step S3, an aromatic polyoxyethylene ether compound with a degree of polymerization of 10 is added during the dissolution process, and the amount used is 0.05% to 2.0% of the total weight of the forage cellulose raw material, TPU and solvent.

9. The method for preparing a composite film using biomass cellulose according to claim 1, characterized in that: In step S4, the filtration includes pre-filtration and final glue solution filtration, the pre-filtration pressure is lower than 0.75 MPa, and the final glue solution filtration pressure is lower than 1.25 MPa.

10. A composite film, characterized in that: The composite film is formed by the method for preparing a composite film using biomass cellulose as described in any one of claims 1 to 9.

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