Bacterial cellulose sheet and its preparation method and application

Abstract

The application provides a bacterial cellulose sheet and a preparation method and application thereof, and the preparation method comprises the following steps: modifying bacterial cellulose homogenate by using a modifier to obtain modified bacterial cellulose homogenate; mixing the modified bacterial cellulose homogenate with fiber pulp to obtain on-loom pulp, and forming by papermaking to obtain the bacterial cellulose sheet; and the dry weight content of bacterial cellulose in the bacterial cellulose sheet is 30-90%. The bacterial cellulose sheet is prepared by regulating the particle size and content of bacterial cellulose, the performance indexes of the compounded fiber pulp and the parameters of the forming net material, so that the problem of poor water filtration and strong adhesion of the compounded pulp in the papermaking process and the problem of inability to release paper are solved, the papermaking process is suitable for continuous production equipment such as a paper machine, and the continuous and industrial production of the bacterial cellulose sheet is realized.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of cellulose membrane preparation, in particular to a bacterial cellulose sheet and a preparation method and application thereof. BACKGROUND

[0002] Bacterial cellulose is a porous network nanoscale biopolymer synthesized by microbial fermentation, which is one of the most abundant natural biopolymer in the world. It has high specific surface area, biodegradability, green environmental protection, excellent properties, high purity and other characteristics, and is widely used in papermaking, food, biology, medicine, sound and other fields. The chemical structure of bacterial cellulose is a straight-chain polysaccharide formed by D-glucopyranose connected by β-1, 4 glycosidic bond, and the chemical formula is (C6H 10 O5) n The chemical structure of bacterial cellulose is the same as that of plant cellulose, both of which have abundant hydroxyl structure and natural advantages of excellent combination performance, and have great use value in the papermaking industry.

[0003] Bacterial cellulose has high specific surface area and space network structure as well as a large number of active sites of effective hydroxyl groups. It can be modified by biological modification, physical modification, chemical modification and other ways, and combined with other organic or inorganic molecules to obtain various new functions.

[0004] The current production of bacterial cellulose is mainly produced by shallow plate one-time fermentation. The obtained bacterial cellulose membrane is discontinuous, the dry membrane is strong in brittleness, the post-processing is difficult, the utilization rate is low, the direct modification uniformity is poor, the efficiency is low and other problems, so it is not suitable for direct and large-scale use, and the technical method of regenerating bacterial cellulose membrane to form continuous and industrialized sheet needs to be developed.

[0005] Chinese patent CN111118947A adsorbs rare earth luminescent element ions to bacterial cellulose to form a complex, and then the complex is compounded with plant fiber pulp to prepare fluorescent paper with high fluorescence performance and high durability. However, in the papermaking process, more than 1% of bacterial cellulose addition amount can only be formed by suction filtration due to difficulty in dehydration. SUMMARY

[0006] To solve the above technical problems, the purpose of the present application is to provide a bacterial cellulose sheet and a preparation method and application thereof, and to realize the continuous and industrialized production of bacterial cellulose membrane.

[0007] To achieve the above purpose, the present application provides a preparation method of bacterial cellulose sheet, comprising the following steps:

[0008] The bacterial cellulose homogenate is modified by using a modifier to obtain a modified bacterial cellulose homogenate;

[0009] mixing the modified bacterial cellulose homogenate with a fiber slurry to obtain a wire-approaching slurry, and forming the wire-approaching slurry to obtain the bacterial cellulose sheet;

[0010] The dry weight content of the bacterial cellulose in the bacterial cellulose sheet is 30-90%.

[0011] The average size of the bacterial cellulose particles in the bacterial cellulose homogenate is 0.5-1.5 mm, and the mass fraction of the bacterial cellulose particles with a size of ≤0.2 mm in the total amount of particles is <60%.

[0012] The beating degree of the fiber slurry is 20-60°SR, and the fiber length is 0.6-2 mm.

[0013] The forming wire material used in the forming has the following parameters: air permeability 5500-6600 m 3 / m 2 h, fiber support index 150-200 fsi, support point 1300-1500 sp / cm 2 .

[0014] According to a specific embodiment of the present application, in the above preparation method, preferably, the dry weight content of the bacterial cellulose in the bacterial cellulose sheet is 50-70%.

[0015] According to a specific embodiment of the present application, in the above preparation method, preferably, the bacterial cellulose homogenate is obtained by cutting and homogenizing or grinding the bacterial cellulose fermentation product. Specifically, the preparation method of the bacterial cellulose homogenate is as follows: the bacterial cellulose fermentation product in the form of particles or film is cut into particles by a cutting machine, and then the bacterial cellulose particles are ground into a bacterial cellulose homogenate by a homogenizer, a colloid mill or a grinding machine.

[0016] According to a specific embodiment of the present application, in the above preparation method, preferably, the modifier is selected from one or more of the following: anti-counterfeiting substances, antibacterial and bacteriostatic materials, and papermaking aids selected from wet or dry strength agents.

[0017] According to a specific embodiment of the present application, in the above preparation method, preferably, the modifier is modified to the bacterial cellulose homogenate by biological, chemical or physical methods.

[0018] Specifically, the addition of the modifier is optionally in the following three ways:

[0019] (1) Biological method: adding a modifier to the culture solution of bacterial cellulose, and grafting or adsorbing it onto the bacterial cellulose by biological modification;

[0020] (2) Physical method: slowly add the water dispersion of the modifier into the bacterial cellulose homogenate, and stir to make it uniformly adsorbed on the bacterial cellulose;

[0021] (3) Chemical method: graft the modifier onto the bacterial cellulose through chemical reaction.

[0022] According to the specific embodiments of the present application, in the above preparation method, preferably, the equipment used for papermaking is selected from the group consisting of a cylinder paper machine, a fourdrinier paper machine, an inclined wire paper machine or a kiss coater. Thus, the preparation method of the bacterial cellulose sheet of the present application can realize continuous and industrial production.

[0023] According to the specific embodiments of the present application, in the above preparation method, preferably, the fiber is selected from the group consisting of plant fiber and / or chemically synthesized fiber; the plant fiber is selected from one or more of cotton, hemp, wood and bamboo. The addition of the fiber component makes the sheet more flexible in dry state and less likely to break, facilitating diversified post-processing and application.

[0024] The present application also provides a bacterial cellulose sheet obtained by the above preparation method, which is prepared from the following raw materials in the following weight percentage: bacterial cellulose 30-90%, modifier 0.5%-30%, and the balance being fiber.

[0025] According to the specific embodiments of the present application, preferably, the bacterial cellulose sheet is prepared from the following raw materials in the following weight percentage: bacterial cellulose 50-70%, modifier 0.5%-30%, and the balance being fiber.

[0026] According to the specific embodiments of the present application, preferably, the bacterial cellulose sheet has a basis weight of 10-40 g / m 2 and a thickness of 15-60 μm.

[0027] The present application also provides the use of the above bacterial cellulose sheet in the preparation of anti-counterfeiting articles and / or antibacterial and bacteriostatic paper.

[0028] According to the specific embodiments of the present application, in the above use, preferably, the anti-counterfeiting article is anti-counterfeiting paper, anti-counterfeiting fiber or anti-counterfeiting label.

[0029] The technical solution provided by the present application has the following beneficial effects:

[0030] (1) The present application overcomes the problem that bacterial cellulose cannot be removed from the papermaking machine due to its poor drainage and strong adhesion in the papermaking process by regulating the particle size and content of bacterial cellulose, the performance indicators of the compounded fiber slurry and the parameters of the forming web, so that the papermaking process is suitable for continuous production equipment such as paper machines, realizing continuous and industrial production of bacterial cellulose sheets.

[0031] (2) The content of the bacterial cellulose in the bacterial cellulose sheet of the present application is 30%-90%, which can fully exert the characteristics of high specific surface area and space network structure of the bacterial cellulose, and strengthen the carrying effect of the bacterial cellulose on the modifier, so that the additional functions of the sheet can be better exerted;

[0032] (3) The bacterial cellulose sheet of the present application has an ultra-high content of bacterial cellulose, is easy to wet, has high toughness in wet state, has many free hydroxyl groups, and is convenient to process into a marker and add to anti-fake paper, and has good bonding strength; in addition, the bacterial cellulose sheet has high wet strength, and after being cut and processed, can adapt to the papermaking process to make anti-fake paper;

[0033] (4) The bacterial cellulose sheet of the present application has low requirements for the shape of the bacterial cellulose wet film and particles, and can use the edge and corner scraps to produce, so as to optimize the industrial structure and reduce the production cost. DETAILED DESCRIPTION

[0034] In order to have a clearer understanding of the technical features, objects and beneficial effects of the present application, the technical solutions of the present application are described in detail as follows, but cannot be understood as limiting the implementable scope of the present application.

[0035] The bacterial cellulose wet film used in the embodiment of the present application is prepared by the method disclosed in Example 1 of Chinese Invention Patent CN96100534.3, and the specific process is as follows: 1000g of coconut water is filtered and heated to 100℃, then 100g of sugar and 4.5g of ammonium sulfate are added, dissolved and stirred, and cooled to room temperature, then 3g of yeast, 10g of acetic acid bacteria and 5g of lactic acid bacteria are inoculated, and fermented for 5 days to become a white translucent solid, which is cut and sterilized.

[0036] The present application is described below in combination with specific embodiments.

[0037] Example 1

[0038] The present embodiment provides a preparation method of a bacterial cellulose sheet, which specifically comprises the following steps:

[0039] (1) The bacterial cellulose wet film is cut into 5mm-sized particles by a granulator, and then the particles are ground into a bacterial cellulose homogenate with an average particle size of 0.93mm by a colloid mill, and the mass fraction of the particles with a size lower than 0.2mm (based on the total weight of the particles) is 45%;

[0040] (2) 3.2% of a wet strength agent and 1.8% of a dry strength agent are added to the bacterial cellulose homogenate based on the dry weight of the bacterial cellulose to modify, and the mixture is stirred uniformly to obtain a modified bacterial cellulose homogenate;

[0041] (3) the obtained modified bacterial cellulose homogenate is mixed with a fiber slurry at a dry weight ratio (dry weight ratio of bacterial cellulose to fiber) of 6:4 to form a web forming slurry; wherein the fiber length of the fiber slurry is 1.72 mm, the fibrillation degree is 35°SR, and the fiber in the fiber slurry is composed of cotton and PA66 fiber at a mass ratio of 3:1;

[0042] (4) the papermaking is performed using a Fourdrinier former, and a polyester net (air permeability 6600 m 3 / m 2 h, fiber support index 197 fsi, support point 1365 sp / cm 2 ) is used as a forming net to obtain a bacterial cellulose sheet with a basis weight of 30.63 g / m 2 .

[0043] The bacterial cellulose sheet prepared in this embodiment includes the following components by weight percentage: bacterial cellulose 57%, wet strength agent 1.92%, dry strength agent 1.08%, cotton 30%, and PA66 fiber 10%.

[0044] It is tested that the thickness of the sheet is 41 μm, the air permeability is 11 mL / min, the breaking length is 6098 m, the elongation is 2.28%, and the wet strength is 38.7%. The sheet is cut into a square of 4*4 mm, added into a high-frequency defibrator (frequency 3000 r / min), soaked for 24 h, and still intact after defibration for 360000 r.

[0045] Embodiment 2

[0046] This embodiment provides a preparation method of a bacterial cellulose sheet, specifically including the following steps:

[0047] (1) the bacterial cellulose wet film is cut into 5 mm particles using a granulator, and then the particles are ground into a bacterial cellulose homogenate with an average size of 0.97 mm, and the mass percentage (based on the total weight of the particles) of particles with a size less than 0.2 mm is 51%;

[0048] (2) 3% of a wet strength agent and 2% of a dry strength agent are added to the bacterial cellulose homogenate based on the dry weight of the bacterial cellulose for modification, and the mixture is stirred uniformly to obtain a modified bacterial cellulose homogenate;

[0049] (3) the obtained modified bacterial cellulose homogenate is mixed with a bamboo fiber slurry at a dry weight ratio (dry weight ratio of bacterial cellulose to bamboo fiber) of 6:5 to form a web forming slurry; wherein the fiber length of the bamboo fiber slurry is 1.52 mm, and the fibrillation degree is 42°SR;

[0050] (4) the papermaking is performed using a Fourdrinier former, and a polyester net (air permeability 6600 m 3 / m 2h, fiber support index 197 fsi, support points 1365 sp / cm 2 ), a bacterial cellulose sheet with a basis weight of 27.64 g / m 2 was prepared.

[0051] The bacterial cellulose sheet prepared in this example comprises the following components by weight percentage: bacterial cellulose 51.82%, wet strength agent 1.64%, dry strength agent 1.09%, Dendrocalamus latiflorus 45.45%.

[0052] The sheet has a thickness of 38 μm, air permeability of 1.8 mL / min, breaking length of 6128 m, elongation of 1.98%, and wet strength of 36.6%. The sheet was cut into 4x4 mm squares, added to a high-frequency defibrator (frequency 3000 rpm), soaked for 24 h, and still intact after defibration for 360000 revolutions.

[0053] Example 3

[0054] This example provides a method for preparing a bacterial cellulose sheet, specifically comprising the following steps:

[0055] (1) The bacterial cellulose wet film was cut into 5 mm particles using a granulator, and the particles were ground to an average size of 0.93 mm using a colloid mill, and the mass percentage of particles with a size of less than 0.2 mm (based on the total weight of the particles) was 45% of the bacterial cellulose homogenate;

[0056] (2) 5% of near-infrared upconversion fluorescent anti-counterfeiting powder (average particle size 713 nm) was added to the bacterial cellulose homogenate based on the dry weight of the bacterial cellulose, stirred for 30 min, and then 3% of a wet strength agent and 2% of a dry strength agent were added and stirred uniformly to obtain a modified bacterial cellulose homogenate;

[0057] (3) The modified bacterial cellulose homogenate was mixed with a cotton fiber slurry at a dry weight ratio of 7:3 (dry weight ratio of bacterial cellulose to cotton fiber) to form a wire-forming slurry; wherein the cotton fiber slurry has a fiber length of 1.45 mm and a degree of beating of 48°SR;

[0058] (4) A long wire paper machine was used for papermaking, and the forming wire was a polyester wire (air permeability 6600 m 3 / m 2 h, fiber support index 197 fsi, support points 1365 sp / cm 2 ), a bacterial cellulose sheet with a basis weight of 29.32 g / m 2 was prepared.

[0059] The bacterial cellulose sheet prepared in the embodiment comprises the following components by weight percentage: bacterial cellulose 63%, near-infrared up-conversion fluorescent anti-counterfeiting substance 3.5%, wet strength agent 2.1%, dry strength agent 1.4%, and cotton 30%.

[0060] The sheet has a thickness of 35 μm, air permeability of 7.8 mL / min, breaking length of 5850 m, elongation of 1.71%, wet strength of 35.3%, and strong fluorescence under excitation light at a wavelength of 980 nm.

[0061] The sheet is cut into 4×4 mm squares, added to a high-frequency defibrator (frequency 3000 rpm), soaked for 24 h, and still intact and with satisfactory fluorescence after defibration for 360000 revolutions, and can be adapted to a papermaking system. The sheet is cut into a specific shape and added to a papermaking process to obtain anti-counterfeiting paper.

[0062] Embodiment 4

[0063] The embodiment provides a preparation method of a bacterial cellulose sheet, specifically comprising the following steps:

[0064] (1) The bacterial cellulose wet film is cut into 5 mm particles by a granulator, and the particles are ground into a bacterial cellulose homogenate with an average size of 0.93 mm, and the mass percentage (based on the total weight of the particles) of particles with a size less than 0.2 mm is 45%;

[0065] (2) 0.5% of nano-silver (average particle size 5-7 nm) is added to the bacterial cellulose homogenate based on the dry weight of the bacterial cellulose, stirred for 10 min, and then 3% of a wet strength agent and 2% of a dry strength agent are added and stirred uniformly to obtain a modified bacterial cellulose homogenate;

[0066] (3) The obtained modified bacterial cellulose homogenate is mixed with a cotton fiber slurry at a dry weight ratio of 6:4 (dry weight ratio of bacterial cellulose to cotton fiber) to form a wire feeding slurry; wherein the fiber length of the cotton fiber slurry is 1.45 mm, and the beating degree is 48°SR;

[0067] (4) The wire feeding slurry is used for papermaking by using a long net paper machine, and a polyester net (air permeability 6600 m 3 / m 2 h, fiber support index 197 fsi, and support point 1365 sp / cm 2 ) is used as a forming net to obtain a bacterial cellulose sheet with a basis weight of 35 g / m 2 and a thickness of 32 μm.

[0068] The bacterial cellulose sheet prepared in the embodiment comprises the following components by weight percentage: bacterial cellulose 56.7%, nano-silver 0.3%, wet strength agent 1.8%, dry strength agent 1.2%, and cotton 40%

[0069] The sheet passes the ISO22196 antibacterial test standard requirement.

[0070] Comparative Example 1

[0071] The comparative example provides a preparation method of a bacterial cellulose sheet, which is the same as that of Example 1, except that the dry weight ratio (dry weight ratio of bacterial cellulose to fiber) of the modified bacterial cellulose homogenate to the bamboo fiber slurry in the comparative example is 95:5. Specifically comprising the following steps:

[0072] (1) cutting the bacterial cellulose wet film into 5mm size particles with a granulator, and then grinding them into a bacterial cellulose homogenate with an average particle size of 0.93mm, and the mass percentage (based on the total weight of the particles) of the particles with a size less than 0.2mm is 45%;

[0073] (2) adding 3.2% of a wet strength agent and 1.8% of a dry strength agent to the bacterial cellulose homogenate based on the dry weight of the bacterial cellulose for modification, and stirring uniformly to obtain a modified bacterial cellulose homogenate;

[0074] (3) mixing the obtained modified bacterial cellulose homogenate with the fiber slurry at a dry weight ratio (dry weight ratio of bacterial cellulose to fiber) of 95:5 to form a web forming slurry; wherein the fiber length of the fiber slurry is 1.72mm, the beating degree is 35°SR, and the fiber in the fiber slurry is composed of cotton and PA66 fiber with a mass ratio of 3:1;

[0075] (4) using a Keeser sheet former for papermaking, and the forming net is a polyester net (air permeability 6600m 3 / m 2 h, fiber support index 197fsi, support point 1365sp / cm 2 ), and the result is that: due to the high content of bacterial cellulose and the low content of plant fiber in the web forming slurry during the papermaking process, the adhesion of the web forming slurry is too strong, and the paper cannot be normally removed.

[0076] Comparative Example 2

[0077] The comparative example provides a preparation method of a bacterial cellulose sheet, which is the same as that of Example 2, except that the average particle size of the bacterial cellulose homogenate in the comparative example is 0.3mm, and the mass percentage (based on the total weight of the particles) of the particles with a size less than 0.2mm is 77%. Specifically comprising the following steps:

[0078] (1) The bacterial cellulose wet film is cut into 5mm size particles by a granulator, and then the particles are ground into an average size of 0.3mm by a colloid mill, and the mass percentage (based on the total weight of the particles) of the bacterial cellulose homogenate with a size of less than 0.2mm is 77%;

[0079] (2) 3% of a wet strength agent and 2% of a dry strength agent are added to the bacterial cellulose homogenate based on the dry weight of the bacterial cellulose to modify the bacterial cellulose homogenate, and the mixture is stirred uniformly to obtain a modified bacterial cellulose homogenate;

[0080] (3) The obtained modified bacterial cellulose homogenate is mixed with a bamboo fiber slurry at a dry weight ratio (dry weight ratio of bacterial cellulose to bamboo fiber) of 6:5 to form a web forming slurry; wherein the fiber length of the bamboo fiber slurry is 1.52mm, and the beating degree is 42°SR;

[0081] (4) The web forming slurry is used for web forming by a long net paper machine, and the forming net is a polyester net (air permeability 6600m 3 / m 2 h, fiber support index 197fsi, support point 1365sp / cm 2 ), and the result is that the bacterial cellulose homogenate is difficult to dewater by the paper machine due to the inappropriate size, and it is still difficult to release the paper after adjusting the basis weight.

Claims

1. A method for preparing a bacterial cellulose sheet, comprising the following steps: modifying a bacterial cellulose homogenate using a modifier to obtain a modified bacterial cellulose homogenate; mixing the modified bacterial cellulose homogenate with a fiber pulp to obtain a wire pulp, and forming the wire pulp into a shape to obtain the bacterial cellulose sheet; the dry weight content of bacterial cellulose in the bacterial cellulose sheet is 50-70%; in the bacterial cellulose homogenate, the average size of bacterial cellulose particles is 0.5-1.5mm, and the mass fraction of bacterial cellulose particles with a size of ≤0.2mm in the total amount of particles is 45-51%; the beating degree of the fiber pulp is 20-60°SR, and the fiber length is 0.6-2mm; the bacterial cellulose homogenate is obtained by cutting and homogenizing or grinding a bacterial cellulose fermentation product. 2.The method according to claim 1, wherein the modifier is selected from one or more of an anti-counterfeiting substance, an antibacterial and bacteriostatic material, and a papermaking aid selected from a wet strength agent or a dry strength agent. 3.The method according to claim 1 or 2, wherein the modifier modifies the bacterial cellulose homogenate by biological, chemical or physical means. wherein 4.The method according to any one of claims 1-3, wherein the equipment used for forming is selected from a cylinder paper machine, a long net paper machine, an inclined net paper machine or a Kesy sheet former. 5.The method according to any one of claims 1-4, wherein the fiber is selected from plant fiber and / or chemically synthesized fiber; and the plant fiber is selected from one or more of cotton, hemp, wood and bamboo. 6.The method according to any one of claims 1-5, wherein the bacterial cellulose homogenate is obtained by cutting and homogenizing or grinding a bacterial cellulose fermentation product. The forming wire used in the papermaking has the following parameters: air permeability 5500-6600 m 3 / m 2 h, fiber support index 150-200 fsi, support points 1300-1500 sp / cm 2 .

2. The production method according to claim 1, wherein 7.A bacterial cellulose sheet prepared by the method according to any one of claims 1-6, which is prepared from the following raw materials by weight percentage: bacterial cellulose 50-70%, modifier 0.5%-30%, and the balance being fiber.

3. The production method according to claim 1, wherein 9.The use of the bacterial cellulose sheet according to claim 7 or 8 in the preparation of an anti-counterfeiting substance and / or an antibacterial and bacteriostatic paper.

4. The production method according to claim 1, wherein 10.The use according to claim 9, wherein the anti-counterfeiting substance is anti-counterfeiting paper, anti-counterfeiting fiber or anti-counterfeiting label.

5. The production method according to claim 1, wherein ​ 6. The production method according to claim 1, wherein ​ ​ 8. The bacterial cellulose sheet according to claim 7, wherein, The amount thereof is 10-40 g / m 2 2, and the thickness is 15-60 μm. ​ ​