CN105461971B - Nano-cellulose base oxidized starch compound bio latex and its preparation and application - Google Patents

Abstract

The invention discloses a nanocellulose-based oxidized starch composite biological latex and its preparation and application. The preparation method is as follows: treating the chemical pulp for papermaking with concentrated sulfuric acid, centrifuging and washing the suspension treated with concentrated sulfuric acid repeatedly, placing the obtained suspension in a dialysis bag, dialysis until neutral, and finally ultrasonic treatment , freeze-drying to obtain nanocellulose; oxidizing starch solution while performing microwave treatment to obtain oxidized starch; mixing nanocellulose and oxidized starch, and using ultrasonic treatment to obtain nanocellulose-based oxidized starch composite biological latex. This bio-latex uses starch as the main raw material, which has great advantages in terms of safety, environmental protection, and sustainability. And adding nanocellulose to oxidized starch, oxidized starch can better play the role of adhesive in papermaking coatings, and nanocellulose can also significantly improve the surface strength and smoothness of coated paper, which can be well applied To the field of paper coating.

Description

Nanocellulose-based oxidized starch composite biological latex and its preparation and application

technical field

The invention belongs to the technical field of light industry and chemical industry, and in particular relates to a nanocellulose-based oxidized starch composite biological latex and its preparation and application.

Background technique

Since the beginning of the 21st century, issues such as rising oil prices, environmental pollution, greenhouse gas emissions, and resource depletion caused by the exploitation and use of fossil resources have gradually become the focus of common concern around the world. Since most of the raw materials needed for synthetic latex are petroleum cracking products, latex production enterprises are also facing pressure from rising raw material costs and environmental protection, especially the concern that oil prices will remain high for a long time, driving researchers and production enterprises to actively Find a solution. At present, one of the world-recognized solutions is to transition from non-renewable fossil resources to renewable biomass resources, and partially replace or even completely replace petroleum with abundant, cheap, renewable and pollution-free natural biomass resources. Cracking products, in order to get rid of dependence on petroleum.

Starch is the main form of carbohydrate storage in plants. It has the characteristics of wide source, cheap, easy processing and biodegradability, and less environmental pollution. However, natural or unmodified starch has a high viscosity, which is difficult to be directly applied to the preparation of coatings, and the original starch after gelatinization has poor stability, is easy to age, retrogrades, etc., and is difficult to be used as an adhesive for coatings.

How to better apply starch to coatings for papermaking coating is an urgent problem to be solved in the application of starch in the field of papermaking coating. Therefore, it is necessary for us to develop a new type of bio-latex that is cheap, easy to process and biodegradable, and has little environmental pollution for the field of paper coating.

Contents of the invention

In order to solve the shortcomings and deficiencies of the prior art, the primary purpose of the present invention is to provide a method for preparing nanocellulose-based oxidized starch composite biological latex.

Another object of the present invention is to provide the nanocellulose-based oxidized starch composite biological latex obtained by the above preparation method.

Another object of the present invention is to provide the application of the nanocellulose-based oxidized starch composite biological latex.

The object of the invention is achieved through the following technical solutions:

A preparation method of nanocellulose-based oxidized starch composite biological latex, comprising the following steps:

(1) Mix chemical pulp for papermaking with sulfuric acid solution, react at 50-70°C for 1-3 hours; then centrifuge and wash; dialyze the obtained suspension until the suspension is neutral; perform ultrasonic treatment on the dialyzed suspension Finally, freeze-dry to obtain nanocellulose;

(2) Weigh a certain amount of starch and water and disperse into starch milk with a mass concentration of 30-40%, then microwave treatment under stirring conditions; adjust the pH value of the system to 3-5, add FeSO ₄ solution, and then carry out Microwave treatment, and drop hydrogen peroxide solution, react for 20-50 minutes, adjust the pH value of the system to 5-7, reduce unreacted hydrogen peroxide with sodium thiosulfate, and finally wash and dry to obtain oxidized starch ;

(3) Take a certain amount of nanocellulose prepared in step (1) and oxidized starch prepared in step (2) and water to disperse into a solution with a mass concentration of 30% to 50%, and then ultrasonically treat it to obtain nanocellulose-based oxidized starch. Starch complex biological latex.

The chemical pulp for papermaking described in the step (1) is one or more of needlewood chemical pulp, hardwood chemical pulp and grass chemical pulp.

The mass ratio of the absolute dry mass of the chemical pulp for papermaking described in step (1) to the sulfuric acid in the sulfuric acid solution is 1: (10-20).

The sulfuric acid solution described in step (1) is preferably a sulfuric acid solution with a mass fraction of 60 to 80%;

The centrifugation and washing in step (1) refer to repeated centrifugation and washing at 3000 to 5000 r/min for 6 to 12 times, each time for 4 to 6 minutes, until the pH value reaches 5 to 6;

The time for the ultrasonic treatment in step (1) is 2 to 6 minutes, and the output frequency is 1000 to 2000 Hz;

The freeze-drying time of step (1) is 46-50 hours.

The starch described in step (2) refers to one or more of corn starch, potato starch, tapioca starch and rice starch.

The power of the microwave treatment in step (2) is 400-700W, wherein the stirring can be magnetic stirring, mechanical stirring or manual stirring, more preferably mechanical stirring;

In step (2), the pH value of the system is adjusted to 3 to 5 with a HCl solution with a mass concentration of 2 to 4%;

In the step (2), the pH value of the system is adjusted to 5-7 with a NaOH solution having a mass concentration of 8-12%.

_The FeSO in the _FeSO solution added in step (2) is 0.04-0.12% of the dry starch mass.

The H ₂ O ₂ in the hydrogen peroxide solution added in step (2) is 3-5% of the absolute dry starch mass.

The mass ratio of nanocellulose to oxidized starch in step (3) is 1: (30-50).

The time for the ultrasonic treatment in step (3) is 2 to 6 minutes, and the output frequency is 1000 to 2000 Hz.

The nanocellulose-based oxidized starch composite biological latex obtained by the above preparation method.

The application of the nanocellulose-based oxidized starch composite biological latex in the field of papermaking coating.

The nanocellulose-based oxidized starch composite biological latex obtained by the above preparation method can be used directly as a coating adhesive, or can replace part of the styrene-butadiene latex in the coating adhesive.

Compared with the prior art, the present invention has the following advantages and beneficial effects:

The present invention uses starch as the main raw material, which has great advantages in safety, environmental protection, sustainability and the like. In the present invention, the nanocellulose is added to the oxidized starch, and the oxidized starch can better exert the effect of an adhesive in the papermaking coating, and at the same time, the nanocellulose can also significantly improve the surface strength and smoothness of the coated paper. The invention also adopts the method of microwave pretreatment of starch, which reduces the consumption of chemical reagents and is more in line with the concept of low-carbon and environmental protection.

Detailed ways

The present invention will be further described in detail below in conjunction with examples, but the embodiments of the present invention are not limited thereto. Each starting material in the preparation method of the present invention can be purchased from the market.

Example 1

A nanocellulose-based oxidized starch composite biological latex, the preparation steps are as follows:

(1) Mix the chemical pulp for papermaking with a sulfuric acid solution with a mass fraction of 60% (the mass ratio of the absolute dry mass of the chemical pulp for papermaking to the sulfuric acid in the sulfuric acid solution is 1:10, and the chemical pulp for papermaking is softwood pulp) , reacted in a shaking water bath (temperature 50° C.) for 1 h. Then, the suspension was repeatedly centrifuged at 3000r/min and washed 6 times, each time for 4min, until the pH value reached 5. The obtained suspension was placed in a dialysis bag and dialyzed until the suspension was neutral. Ultrasonic treatment was performed on the dialyzed pulp (time 2 min, output frequency 1000 Hz), and finally freeze-dried for 46 h to obtain nanocellulose.

(2) Take a certain amount of starch and water in a beaker and disperse it into starch milk with a mass concentration of 30%, then completely transfer it to the flask, put it into a microwave reactor (power 400W) and stir at a certain speed; Be that the pH value of 2% HCl solution regulation system is to 3 with mass concentration, add FeSO ₄ solution (FeSO ₄ is 0.04% of dry starch quality), start microwave reactor (power 400W) again and drop by constant pressure funnel Hydrogen oxide solution (H ₂ O ₂ is 3% of the dry starch mass), after reacting for 20min, adjust the pH value of the system to 5 with a NaOH solution with a mass concentration of 8%, and reduce unreacted hydrogen peroxide with sodium thiosulfate , and finally after washing and drying, the oxidized starch is obtained.

(3) Get a certain amount of nanocellulose in step (1) and oxidized starch in step (2) and water in a beaker and be dispersed into a solution that has a mass concentration of 30% (wherein the mass ratio of nanocellulose and oxidized starch is 1:30), and then completely transferred to the flask, ultrasonic treatment (time 2min, output frequency 1000Hz), to obtain nanocellulose-based oxidized starch composite biological latex.

Example 2

A nanocellulose-based oxidized starch composite biological latex, the preparation steps are as follows:

(1) Mix the chemical pulp for papermaking with a sulfuric acid solution with a mass fraction of 70% (the mass ratio of the absolute dry mass of the chemical pulp for papermaking to the sulfuric acid in the sulfuric acid solution is 1:15, and the chemical pulp for papermaking is softwood pulp) , reacted in a shaking water bath (temperature 60° C.) for 2 h. Then, the suspension was repeatedly centrifuged at 4000r/min and washed 8 times, each time for 5min, until the pH value reached 5.5. The obtained suspension was placed in a dialysis bag and dialyzed until the suspension was neutral. Ultrasonic treatment was performed on the dialyzed pulp (time 4 min, output frequency 1500 Hz), and finally freeze-dried for 48 h to obtain nanocellulose.

(2) Take a certain amount of starch and water in a beaker and disperse it into starch milk with a mass concentration of 35%, then completely transfer it to the flask, put it into a microwave reactor (power 500W) and stir at a certain speed; Be that the pH value of 3% HCl solution regulation system is to 4 with mass concentration, add FeSO ₄ solution (FeSO ₄ is 0.08% of absolute dry starch quality), start microwave reactor (power 500W) again and drop by constant pressure funnel Hydrogen oxide solution (H ₂ O ₂ is 4% of the dry starch mass), after reacting for 30min, adjust the pH value of the system to 6 with a NaOH solution with a mass concentration of 10%, and reduce unreacted hydrogen peroxide with sodium thiosulfate , and finally after washing and drying, the oxidized starch is obtained.

(3) Get a certain amount of nanocellulose in step (1) and oxidized starch in step (2) and water in a beaker and be dispersed into a solution that has a mass concentration of 40% (wherein the mass ratio of nanocellulose and oxidized starch is 1:35), and then completely transferred to the flask, ultrasonic treatment (time 4min, output frequency 1500Hz), to obtain nanocellulose-based oxidized starch composite biological latex.

Example 3

A nanocellulose-based oxidized starch composite biological latex, the preparation steps are as follows:

(1) Mix the chemical pulp for papermaking with a sulfuric acid solution with a mass fraction of 80% (the mass ratio of the absolute dry mass of the chemical pulp for papermaking to the sulfuric acid in the sulfuric acid solution is 1:20, and the chemical pulp for papermaking is softwood pulp) , reacted in a shaking water bath (temperature 70° C.) for 3 h. Then, the suspension was repeatedly centrifuged at 5000r/min and washed 12 times, each time for 6min, until the pH value reached 6. The obtained suspension was placed in a dialysis bag and dialyzed until the suspension was neutral. Ultrasonic treatment was performed on the dialyzed pulp (time 6 min, output frequency 2000 Hz), and finally freeze-dried for 50 h to obtain nanocellulose.

(2) Take a certain amount of starch and water in a beaker and disperse it into starch milk with a mass concentration of 40%, then completely transfer it to the flask, put it into a microwave reactor (power 700W) and stir at a certain speed; Be that the pH value of 4% HCl solution regulation system is to 5 with mass concentration, add FeSO ₄ solution (FeSO ₄ is 0.12% of dry starch quality), start microwave reactor (power 700W) again and drop by constant pressure funnel Hydrogen oxide solution (H ₂ O ₂ is 5% of the dry starch quality), after reacting for 50min, adjust the pH value of the system to 7 with a NaOH solution with a mass concentration of 12%, and reduce unreacted hydrogen peroxide with sodium thiosulfate , and finally after washing and drying, the oxidized starch is obtained.

(3) Get a certain amount of nanocellulose in step (1) and oxidized starch in step (2) and water in a beaker and be dispersed into a solution that the mass concentration is 50% (wherein the nanocellulose and oxidized starch mass ratio is 1:40), and then completely transferred to the flask, ultrasonic treatment (time 6min, output frequency 2000Hz), to obtain nanocellulose-based oxidized starch composite biological latex.

Example 4

A nanocellulose-based oxidized starch composite biological latex, the preparation steps are as follows:

(1) Mix the chemical pulp for papermaking with a sulfuric acid solution with a mass fraction of 60% (the mass ratio of the dry weight of the chemical pulp for papermaking to the sulfuric acid in the sulfuric acid solution is 1:10, and the chemical pulp for papermaking is hardwood pulp) , reacted in a shaking water bath (temperature 60° C.) for 2 h. Then, the suspension was repeatedly centrifuged at 4000r/min and washed 10 times, each time for 5min, until the pH value reached 6. The obtained suspension was placed in a dialysis bag and dialyzed until the suspension was neutral. Ultrasonic treatment was performed on the dialyzed pulp (time 5 min, output frequency 1000 Hz), and finally freeze-dried for 48 h to obtain nanocellulose.

(2) Take a certain amount of starch and water in a beaker and disperse it into starch milk with a mass concentration of 40%, then completely transfer it to the flask, put it into a microwave reactor (power 600W) and stir at a certain speed; Be that the pH value of 3% HCl solution regulation system is to 4 with mass concentration, add FeSO ₄ solution (FeSO ₄ is 0.12% of dry starch quality), start microwave reactor (power 400W) again and drop by constant pressure funnel Hydrogen oxide solution (H ₂ O ₂ is 5% of the dry starch mass), after reacting for 50min, adjust the pH value of the system to 7 with a NaOH solution with a mass concentration of 8%, and reduce unreacted hydrogen peroxide with sodium thiosulfate , and finally after washing and drying, the oxidized starch is obtained.

(3) Get a certain amount of nanocellulose in step (1) and oxidized starch in step (2) and water in a beaker and be dispersed into a solution that the mass concentration is 50% (wherein the nanocellulose and oxidized starch mass ratio is 1:45), and then completely transferred to the flask, ultrasonic treatment (time 5min, output frequency 1500Hz), to obtain nanocellulose-based oxidized starch composite biological latex.

Example 5

A nanocellulose-based oxidized starch composite biological latex, the preparation steps are as follows:

(1) The chemical pulp for papermaking is mixed with a sulfuric acid solution with a mass fraction of 80% (the mass ratio of the absolute dry mass of the chemical pulp for papermaking to the sulfuric acid in the sulfuric acid solution is 1:20, and the chemical pulp for papermaking is reed pulp), React in a shaking water bath (temperature 60° C.) for 3 h. Then, the suspension was repeatedly centrifuged at 4000r/min and washed 12 times, each time for 5min, until the pH value reached 6. The obtained suspension was placed in a dialysis bag and dialyzed until the suspension was neutral. Ultrasonic treatment was performed on the dialyzed pulp (time 6 min, output frequency 2000 Hz), and finally freeze-dried for 46 h to obtain nanocellulose.

(2) Take a certain amount of starch and water in a beaker and disperse it into starch milk with a mass concentration of 35%, then completely transfer it to the flask, put it into a microwave reactor (power 500W) and stir at a certain speed; Be that the pH value of 3% HCl solution regulation system is to 4 with mass concentration, add FeSO ₄ solution (FeSO ₄ is 0.06% of absolute dry starch quality), start microwave reactor (power 600W) again and drop by constant pressure funnel Hydrogen oxide solution (H ₂ O ₂ is 4% of the absolute dry starch quality), after reacting for 40min, adjust the pH value of the system to 6.5 with a NaOH solution with a mass concentration of 9%, and reduce unreacted hydrogen peroxide with sodium thiosulfate , and finally after washing and drying, the oxidized starch is obtained.

(3) Get a certain amount of nanocellulose in step (1) and oxidized starch in step (2) and water in a beaker and be dispersed into a solution that has a mass concentration of 40% (wherein the mass ratio of nanocellulose and oxidized starch is 1:45), and then completely transferred to the flask, ultrasonic treatment (time 4min, output frequency 1000Hz), to obtain nanocellulose-based oxidized starch composite biological latex.

Example 6

Directly replace the styrene-butadiene latex with the nanocellulose-based oxidized starch composite biological latex obtained in Examples 1 to 5 of the present invention, and apply it to paper coating as a coating adhesive. According to the sequence of Examples 1 to 5, they are respectively labeled as Samples 1, 2, 3, 4 and 5. The physical properties of the coated adhesive and the physical properties of the coated paper are shown in the following table:

sample 1 2 3 4 5 SBR Latex Nanocellulose: Oxidized Starch 1:30 1:35 1:40 1:45 1:50 none High shear viscosity mPa.s 66 70 78 73 74 54 BaiDu% 83.32 83.17 82.76 80.21 81.78 81.90 COBB value g/m ² 34.53 34.01 33.07 32.38 31.45 36.35 Dry pick strength m/s 4.13 4.25 4.44 4.67 4.69 3.18 Gloss% 66.9 67.1 66.7 64.9 64.3 69.5

It can be seen from the above table that the nanocellulose-based oxidized starch composite bio-latex provided by the present invention directly replaces styrene-butadiene latex, and its high-shear viscosity is slightly higher than that of styrene-butadiene latex, but it still has better rheology and runnability, and paper strength performance The improvement is obvious, and the printing adaptability is equivalent to that of synthetic styrene-butadiene latex. Although the glossiness is slightly reduced, it does not affect its application, and because the cost of starch-coated latex is lower than that of styrene-butadiene latex, the nanocellulose provided by the invention The composite biological latex based on oxidized starch has good application value and application prospect.

The above-mentioned embodiment is a preferred embodiment of the present invention, but the embodiment of the present invention is not limited by the above-mentioned embodiment, and any other changes, modifications, substitutions, combinations, Simplifications should be equivalent replacement methods, and all are included in the protection scope of the present invention.

Claims (8)

1. a preparation method of nanocellulose-based oxidized starch composite biological latex, is characterized in that, comprises the following steps: (1) Mix chemical pulp for papermaking with sulfuric acid solution, react at 50-70°C for 1-3 hours; then centrifuge and wash; dialyze the obtained suspension until the suspension is neutral; perform ultrasonic treatment on the dialyzed suspension Finally, freeze-dry to obtain nanocellulose; the mass ratio of the absolute dry mass of the chemical pulp for papermaking to the sulfuric acid in the sulfuric acid solution is 1: (10-20); (2) Weigh a certain amount of starch and water and disperse into starch milk with a mass concentration of 30-40%, then microwave treatment under stirring conditions; adjust the pH value of the system to 3-5, add FeSO ₄ solution, and then carry out Microwave treatment, and drop hydrogen peroxide solution, react for 20-50 minutes, adjust the pH value of the system to 5-7, reduce unreacted hydrogen peroxide with sodium thiosulfate, and finally wash and dry to obtain oxidized starch ; FeSO ₄ in the added FeSO ₄ solution is 0.04-0.12% of the dry starch mass; H ₂ O ₂ in the added hydrogen peroxide solution is 3-5% of the dry starch mass; (3) get the nanocellulose that a certain amount of step (1) makes and the oxidized starch that step (2) makes and water disperse into the solution of mass concentration 30～50%, described nanocellulose and oxidized starch mass ratio are 1: (30-50); and then ultrasonically treated to obtain nanocellulose-based oxidized starch composite biological latex. 2. the preparation method of nano-cellulose-based oxidized starch composite biological latex according to claim 1, is characterized in that, the papermaking chemical pulp described in step (1) is needle leaf chemical pulp, hardwood chemical pulp and grass One or more of chemical pulp. 3. the preparation method of nanocellulose-based oxidized starch composite biological latex according to claim 1, is characterized in that, the sulfuric acid solution described in step (1) is the sulfuric acid solution that mass fraction is 60～80%; The centrifugation and washing in step (1) refer to repeated centrifugation and washing at 3000 to 5000 r/min for 6 to 12 times, each time for 4 to 6 minutes, until the pH value reaches 5 to 6; The time for the ultrasonic treatment in step (1) is 2 to 6 minutes, and the output frequency is 1000 to 2000 Hz; The freeze-drying time of step (1) is 46-50 hours. 4. the preparation method of nanocellulose-based oxidized starch composite biological latex according to claim 1, is characterized in that, the starch described in step (2) refers to one of cornstarch, potato starch, tapioca starch and rice starch one or more species. 5. The preparation method of nanocellulose-based oxidized starch composite biological latex according to claim 1, characterized in that, the power of the microwave treatment in step (2) is 400～700W; In step (2), the pH value of the system is adjusted to 3 to 5 with a HCl solution with a mass concentration of 2 to 4%; In the step (2), the pH value of the system is adjusted to 5-7 with a NaOH solution having a mass concentration of 8-12%. 6 . The method for preparing nanocellulose-based oxidized starch composite biological latex according to claim 1 , characterized in that the ultrasonic treatment time in step (3) is 2 to 6 minutes, and the output frequency is 1000 to 2000 Hz. 7. A nanocellulose-based oxidized starch composite biological latex, characterized in that it is prepared by the preparation method of the nanocellulose-based oxidized starch composite biological latex according to any one of claims 1 to 6. 8. The application of the nanocellulose-based oxidized starch composite bio-latex according to claim 7 in the field of papermaking coating.