CN111364284B

CN111364284B - Modified sizing starch, surface sizing liquid and preparation method and application thereof

Info

Publication number: CN111364284B
Application number: CN202010120342.2A
Authority: CN
Inventors: 施晓旦; 潘航; 金霞朝
Original assignee: Shanghai Changfa New Materials Co Ltd
Current assignee: Shanghai Changfa New Materials Co Ltd
Priority date: 2020-02-26
Filing date: 2020-02-26
Publication date: 2023-06-09
Anticipated expiration: 2040-02-26
Also published as: CN111364284A

Abstract

The invention discloses modified sizing starch, a surface sizing solution, a preparation method and application thereof. The preparation method of the modified sizing starch comprises the following steps: (1) Mixing and gelatinizing pulping waste liquid and starch in sequence to obtain a material A; (2) Mixing the material A with a catalyst and an aqueous hydrogen peroxide solution, and preserving heat to obtain a material B; (3) Mixing the material B with a reducing agent to prepare modified sizing starch; in the step (2), the catalyst contains Fe ²⁺ 、Cr ²⁺ 、V ²⁺ 、Ti ³⁺ 、Co ²⁺ And Cu ⁺ One or more of the compounds of (a); in the step (2), the weight ratio of the dry weight of the pulping waste liquid to the weight of the hydrogen peroxide aqueous solution is 1:0.04-1.6 percent of hydrogen peroxide aqueous solution with the mass percent of 24-35 percent. The prepared surface sizing solution can effectively improve the water resistance of paper, reduce the Cobb value of the paper, and has mechanical properties equivalent to those of the existing surface sizing solution, and the raw materials are degradable.

Description

Modified sizing starch, surface sizing liquid and preparation method and application thereof

Technical Field

The invention particularly relates to modified sizing starch, a surface sizing solution, and a preparation method and application thereof.

Background

In recent years, the extraction and application of biomass resources are important research points in academic and industrial fields at home and abroad, mainly refine and modify agriculture, forestry and marine product wastes, convert a large amount of wasted environmental pollutants into high-added-value products, have the characteristics of wide sources, low cost and biodegradability, and provide a new idea for replacing non-renewable resources and high-cost raw materials. Patent CN105018011B reports a method for preparing phenolic adhesive by using bagasse papermaking waste liquid concentrate to replace phenol partially, the obtained adhesive has strong adhesive force, and is used for preparing artificial wood fiber board, the formaldehyde residue is low, and the method is a successful case for changing biomass resources into valuable. How to use these huge amounts of biomass resources in papermaking chemicals remains to be explored. Therefore, research on the preparation of papermaking chemicals by using biomass resources is a significant work, which further reduces the production cost, widens the variety of surface sizing liquid, and plays a beneficial demonstration role in comprehensive utilization of biomass resources and reduction of environmental pollution.

Surface sizing is a common mode for treating base paper in paper factories, a layer of sizing solution is coated on the surface of paper, and a layer of uniform film is formed after drying, so that the problems of rough surface, easy hair and powder falling and difficult printing and writing of the base paper can be solved. It can be seen that surface sizing is one of the important papermaking chemicals. Meanwhile, the paper subjected to surface sizing has certain surface or internal strength and delayed penetration capacity, has better water resistance, and can improve the performances of tensile strength, tearing strength, folding endurance, paper internal bonding strength and the like.

The Chinese patent ZL201310724587.6 provides a corrugated paper surface sizing agent prepared by compounding and modifying APMP pulping waste liquid and polyacrylamide, and the surface sizing agent is prepared by compounding APMP pulping waste liquid, aluminum sulfate, gelatinized starch and high-molecular polyacrylamide, but the polyacrylamide used in the scheme is difficult to biodegrade, causes environmental pollution and has relatively high cost.

At present, the more economical surface sizing method is to carry out enzyme treatment and re-sizing on corn starch, and the total cost reaches the limit level which is difficult to reduce because the starch treatment in paper factories requires corresponding workshop cost and the starch consumption cannot be reduced. Therefore, there is a need in the art to develop a surface sizing agent that is low in sizing cost and can enhance sizing effect.

Disclosure of Invention

The invention aims to overcome the defects of complex preparation process, high preparation cost, undegraded raw materials and the like of surface sizing liquid in the prior art and provides modified sizing starch, surface sizing liquid, a preparation method and application thereof. Compared with the existing preparation method of sizing starch, the preparation method of the modified sizing starch uses pulping waste liquid to replace part of starch, so that the total consumption of starch is reduced, and the cost is reduced; during the use process, the starch does not need to be subjected to enzymolysis, so that the workshop cost is saved; the surface sizing solution prepared by compounding the modified sizing starch, a surface sizing agent SAE and aluminum sulfate can effectively improve the water resistance of paper, reduce the Cobb value of the paper, and has the performances of equivalent ring crush strength, ring crush index, folding endurance, burst index and the like to the effects of the existing surface sizing solution, and the raw materials are degradable.

The invention adopts the following technical scheme to solve the technical problems:

the invention provides a preparation method of modified sizing starch, which comprises the following steps:

(1) Mixing and gelatinizing pulping waste liquid and starch in sequence to obtain a material A;

(2) Mixing the material A with a catalyst and a hydrogen peroxide water solution, and preserving heat to obtain a material B;

(3) Mixing the material B with a reducing agent to prepare modified sizing starch;

wherein in the step (2), the catalyst contains Fe ²⁺ 、Cr ²⁺ 、V ²⁺ 、Ti ³⁺ 、Co ²⁺ And Cu ⁺ One or more of the compounds of (a);

in the step (2), the weight ratio of the aqueous hydrogen peroxide solution to the dry weight of the pulping waste liquid is more than 0.04:1, the mass fraction of the hydrogen peroxide in the hydrogen peroxide aqueous solution relative to the hydrogen peroxide aqueous solution is 24-35%.

In steps (1) - (3), the mixing conditions and methods may be conventional in the art, preferably with stirring.

In the step (1), the pulping waste liquid may be pulping waste liquid generated in the process of preparing straw pulp and/or wood pulp in the field, and is generally one or more liquid materials of humic pulp, pulp residue and waste liquid except finished pulp after insoluble substances are filtered, for example, pulping waste liquid generated in the process of preparing straw pulp and/or wood pulp by Jining Ming's new material Co., ltd.

Wherein the method of preparing the straw pulp and/or wood pulp may be conventional in the art, such as one or more of a mechanical pulping process, a chemimechanical pulping process, and a chemical pulping process.

Wherein the mechanical pulp process may be conventional in the art, such as a millstone process or a thermomechanical process.

The chemimechanical pulping process may be conventional in the art, such as chemimechanical, neutral sulfite semi-chemical, or alkaline hydrogen peroxide mechanical.

The chemical pulping process may be conventional in the art, such as caustic soda, sulfate or sulfite.

In a preferred embodiment, the pulping waste liquid can be prepared by referring to the invention patent CN102587179B, specifically: a, selecting eucalyptus pieces and performing pre-steaming; b, pumping the aqueous solution of eucalyptus chips to the top of an independent continuous hydrolysis tower by a pump according to the mass ratio of the eucalyptus chips to water of 1:3-1:10, carrying out hydrolysis reaction on the eucalyptus chips for 1-4h at the temperature of 120-180 ℃, and extracting hydrolysis liquid from the lower part of the hydrolysis tower after the pre-hydrolysis reaction; c, steaming the hydrolyzed eucalyptus pieces by a sulfate method, wherein the steaming conditions are as follows: the hydrolyzed eucalyptus pieces are added at a constant speed at the top of a digester, the sulfidation degree of the effective alkali is 20-40% based on 16-24% of the absolute dry quantity of the eucalyptus pieces calculated by NaOH, the cooking temperature is 140-170 ℃, the mass ratio of the eucalyptus pieces to water is 1:3-1:6, the cooking time is 1-4h, and after dissolving pulp is collected, the residual substances in a hydrolysis tower are filtered, so that pulping waste liquid is obtained.

Preferably, the preparation method of the pulping waste liquid comprises the steps of a, selecting eucalyptus pieces and performing pre-steaming; b, the mass ratio of eucalyptus pieces to water is 1:5, enabling the aqueous solution of eucalyptus chips to reach the top of an independent continuous hydrolysis tower by using a pump, enabling the hydrolysis reaction time of the eucalyptus chips to be 2 hours, enabling the reaction temperature to be 165 ℃, and extracting hydrolysis liquid from the lower part of the hydrolysis tower after the pre-hydrolysis reaction; and c, steaming the hydrolyzed eucalyptus pieces by a sulfate method under the following conditions, wherein the hydrolyzed eucalyptus pieces are uniformly added at the top of a steaming pot, the effective alkali based on the absolute dry quantity of the eucalyptus pieces is 18 percent calculated by NaOH, the vulcanizing degree of the effective alkali is 28 percent, the steaming temperature is 150 ℃, the mass ratio of the eucalyptus pieces to water is 1:5, the steaming time is 2 hours, and after dissolving pulp is collected, the residual substances in a hydrolysis tower are filtered, so that pulping waste liquid is obtained.

In step (1), the solids content of the pulping effluent may be conventional in the art, preferably from 10% to 60%, more preferably 50%.

In step (1), the starch may be one or more of starch conventionally used in the art for preparing modified sizing starches, preferably tapioca starch, corn starch, potato starch and wheat starch, such as tapioca starch, corn starch, potato starch or wheat starch.

In step (1), the ratio of the dry weight of the pulping effluent to the weight of the starch may be conventional in the art, preferably 1: (0.4-10), more preferably 1: (0.625-3.75), for example 1:1.33, 1:1.6, 1:1.87 or 1:2.2.

in step (1), preferably, the pulping waste liquor, the starch and water are mixed.

Wherein the ratio of the dry weight of the pulping waste liquor to the weight of the water may be conventional in the art, preferably 1: (2-14), more preferably 1: (3.125-8.75), for example 1:4. 1:4.67, 1:5 or 1:1.56.

in the step (1), the solid content in the mixed material obtained after the mixing can be 8% -32%.

In step (1), the temperature of the gelatinization may be conventional in the art for such operations, preferably 70-90 ℃, more preferably 75-82 ℃, still more preferably 80 ℃.

In step (1), the time for the gelatinization may be a time conventional in this type of operation in the art, preferably 0.5 to 2 hours, more preferably 0.75 to 1.5 hours, still more preferably 1 hour.

In step (1), the pH of the gelatinization may be a conventional gelatinization pH in the art, preferably 2-12, more preferably 11.

In the step (2), the alloy contains Fe ²⁺ Preferably, the compound is one or more of ferrous sulfide, ferrous chloride and ferrous sulfate, more preferably ferrous sulfide.

In the step (2), the Cr-containing alloy contains ²⁺ Preferably one or more of chromium monoxide, chromia acetate and chromia sulphide, more preferably chromium monoxide.

In the step (2), the catalyst contains V ²⁺ The compound of (c) is preferably vanadium dichloride and/or vanadium sulphate, more preferably vanadium dichloride.

In the step (2), the alloy contains Ti ³⁺ Preferably titanium trichloride.

In the step (2), the catalyst contains Co ²⁺ Preferably one or more of cobalt oxide, cobalt dichloride and cobalt sulphide.

In the step (2), the Cu-containing alloy contains ⁺ Preferably one or more of cuprous oxide, cuprous bromide and cuprous sulfide, more preferably cuprous bromide.

In step (2), the ratio by weight of the pulping effluent to the weight of the catalyst may be conventional in the art, preferably 1: (0.0008-0.02), more preferably 1: (0.0025-0.01), for example, 1:0.0044, 1:0.0048, 1:0.005 or 1:0.0053.

in step (2), the mass fraction of hydrogen peroxide in the aqueous hydrogen peroxide solution is preferably 28% with respect to the aqueous hydrogen peroxide solution.

In step (2), the weight of the aqueous hydrogen peroxide solution to the dry weight of the pulping waste liquid is preferably (0.04-1.6): 1, more preferably (0.13-0.63): 1, for example, 0.28: 1. 0.3: 1. 0.32:1 or 0.33:1. when the amount of the aqueous hydrogen peroxide solution is too low, the gelatinization effect is poor and the product stability is lowered.

In the step (2), the aqueous hydrogen peroxide solution may be added in a manner conventional in the art, preferably in a manner of dropwise addition.

In step (2), the aqueous hydrogen peroxide solution may be added for a period of time ranging from 10 to 30 minutes, preferably from 20 to 25 minutes.

In step (2), the temperature of the incubation may be at a temperature conventional in the art for such operations, preferably 70-90 ℃, more preferably 75-85 ℃, for example 75-78 ℃, 78-81 ℃, 80-83 ℃ or 82-85 ℃.

In step (2), the incubation time may be a time conventional in the art for such operations, preferably 0.5 to 2 hours, more preferably 1 to 1.5 hours.

In step (2), the incubation pH may be conventional in the art, preferably from 4 to 6, more preferably from 4.2 to 5, even more preferably from 4.5 to 4.7.

Wherein the pH is 4-6, can be adjusted by adding acidic solution as is conventional in the art.

Wherein the acidic solution may be an acidic solution conventionally used in the art, preferably one or more of hydrochloric acid, sulfuric acid and acetic acid.

Wherein the mass fraction of hydrogen chloride in the hydrochloric acid relative to the hydrochloric acid may be conventional in the art, preferably 36% -38%, more preferably 36%.

Wherein the weight ratio of the dry weight of the pulping waste liquor to the weight of the acidic solution can be conventional in the art, preferably 1: (0.2-4), more preferably 1: (0.5-1.88), for example, 1:0.85, 1:0.89, 1:0.93 or 1:1.2.

in step (3), the reducing agent may be a reducing agent conventionally used in the art, preferably one or more of sodium bisulphite, sodium azide, sodium nitrite, sodium thiosulfate, potassium iodide, methanol, t-butanol, salicylic acid, benzoic acid and phenol, more preferably sodium azide, methanol or salicylic acid.

In the step (3), the weight ratio of the dry weight of the pulping waste liquid to the weight of the reducing agent may be 1: (0.004-0.2), preferably 1: (0.019-0.1), for example, 1:0.033, 1:0.04, 1:0.048 or 1:0.053. when the amount of the reducing agent is less than the range defined in the present application, retrogradation of the resulting modified sizing starch occurs.

In step (3), preferably, the material B, the reducing agent and water are mixed.

Wherein, the weight ratio of the pulping waste liquid to the water is 1: (0.12-30), preferably 1: (0.1875-18.25), for example, 1:0.2, 1:2.56, 1:6.6 or 1:16.22.

in the step (3), the solid content in the mixed material obtained after the mixing can be 8% -32%.

In the step (3), the mixed materials can further comprise cooling treatment.

Wherein the cooling conditions and methods may be conventional in the art, preferably cooling to room temperature.

In the present invention, the room temperature may be 10 to 30℃as conventionally considered by those skilled in the art.

The invention also provides the modified sizing starch prepared by the preparation method.

In the present invention, the solids content of the modified sizing starch may be conventional in the art, preferably from 8 to 32%, more preferably from 10 to 31%, still more preferably from 20 to 25%.

The invention also provides a surface sizing comprising a modified sizing starch as described above.

The surface sizing may also include one or more of starch, surface sizing agent SAE, and aluminum sulfate.

In the surface sizing solution, the ratio of the dry mass of the modified sizing starch to the mass of the starch may be 1: (0.8-5), for example 1:1.

wherein the starch is preferably used in a form configured as an aqueous starch solution, the starch may have a solids content of 8% -18%, for example 10%.

In the surface sizing solution, the starch can be corn starch and/or tapioca starch.

In the surface sizing solution, the ratio of the dry mass of the modified sizing starch to the mass of the surface sizing agent SAE may be (5 to 11.25): 1, preferably 8.9:1.

in the surface sizing solution, the dry mass of the modified sizing starch to the mass of the aluminum sulfate may be (100-150): 1, preferably 133.3:1.

the aluminum sulfate is preferably used in a form configured as an aqueous aluminum sulfate solution, and the mass percentage of aluminum sulfate in the aqueous aluminum sulfate solution may be 25% -40%, for example, 30%.

In a preferred embodiment of the present invention, the surface sizing liquid comprises the modified sizing starch, corn starch, surface sizing agent SAE and aluminum sulfate; the ratio of the dry mass of the modified sized starch to the mass of the corn starch may be 1:1, a step of; the ratio of the dry mass of the modified sizing starch to the mass of the surface sizing agent SAE may be 8.9:1, a step of; the modified sizing starch may have a dry mass to aluminum sulfate mass ratio of 133.3:1.

the invention also provides an application of the surface sizing agent as the sizing agent in the paper making and sizing process.

Wherein the paper making sizing process may be a surface sizing process conventionally employed in the art, preferably by coating the paper with a surface sizing solution as described above.

In the invention, the solid content is the percentage of the mass of the residual part of the adhesive or coating after being dried under the specified conditions, which is known by the person skilled in the art.

In the invention, the dry mass is the mass of the rest part of the adhesive or coating which is known to the person skilled in the art after being dried under the specified conditions.

On the basis of conforming to the common knowledge in the field, the above preferred conditions can be arbitrarily combined to obtain the preferred examples of the invention.

The reagents and materials used in the present invention are commercially available.

The invention has the positive progress effects that: according to the technical scheme, pulping waste liquid and starch of a paper mill are used as raw materials for gelatinization, starch particles are expanded and chain segments are stretched in the gelatinization process, interaction is generated between the starch particles and substances in the pulping waste liquid, and the modified sizing starch based on biomass is obtained through oxidation modification, so that the waste is changed into valuable. Compared with the traditional sizing starch preparation method, the preparation process provided by the invention uses pulping waste liquid to replace part of starch, so that the total consumption of starch is reduced. In addition, the starch does not need to be subjected to enzymolysis in the use process, so that the workshop cost is saved. The prepared modified sizing starch can partially replace the existing surface sizing starch, effectively improves the water resistance of paper, reduces the Cobb value, ring crush strength, ring crush index, folding endurance, burst index and other performances of the paper, and has the same effect as the existing surface sizing starch.

Detailed Description

The invention is further illustrated by means of the following examples, which are not intended to limit the scope of the invention. The experimental methods, in which specific conditions are not noted in the following examples, were selected according to conventional methods and conditions, or according to the commercial specifications.

The sources of the raw materials used in the examples and comparative examples of the present invention are as follows:

the pulping waste liquid in the following examples is pulping waste liquid generated in the preparation process of eucalyptus dissolving pulp, and the preparation method of the eucalyptus dissolving pulp comprises the following steps: a, selecting eucalyptus pieces and performing pre-steaming; b, the mass ratio of eucalyptus pieces to water is 1:5, enabling the aqueous solution of eucalyptus chips to reach the top of an independent continuous hydrolysis tower by using a pump, enabling the hydrolysis reaction time of the eucalyptus chips to be 2 hours, enabling the reaction temperature to be 165 ℃, and extracting hydrolysis liquid from the lower part of the hydrolysis tower after the pre-hydrolysis reaction; and c, steaming the hydrolyzed eucalyptus pieces by a sulfate method under the following conditions, wherein the hydrolyzed eucalyptus pieces are uniformly added at the top of a steaming pot, the effective alkali based on the absolute dry quantity of the eucalyptus pieces is 18 percent calculated by NaOH, the vulcanizing degree of the effective alkali is 28 percent, the steaming temperature is 150 ℃, the mass ratio of the eucalyptus pieces to water is 1:5, the steaming time is 2 hours, after dissolving pulp is collected, the residue in a hydrolysis tower is filtered and concentrated to obtain pulping waste liquid, and the pH value of the pulping waste liquid is 11.

The tapioca starch used in the examples and comparative examples of the present invention was purchased from wuwen agricultural energy limited; corn starch was purchased from Shandong Baisheng Biotechnology Co., ltd; potato starch was purchased from atanan Ming Yuan chemical Co., ltd; wheat starch was purchased from cereal technologies limited in the county of Shaanxi; corn starch stock solution was purchased from Shandong Sun Honghe paper Co., ltd; the surface sizing agent SAE was purchased from Jining Ming New Material Co.

Example 1

1. Preparation of modified sizing starch

Step (1): under the condition of stirring, adding 30g of pulping waste liquid with the solid content of 50% (15 g of dry mass), 70g of water and 28g of tapioca starch into a glass reaction kettle, uniformly mixing, starting to heat after mixing, and gelatinizing for 1.5h at the temperature of 75 ℃ to obtain a material A.

Step (2): after gelatinization, uniformly mixing the prepared material A with 0.08g of ferrous sulfide under the condition of stirring, and regulating the pH of a system to 4.5 by using hydrochloric acid with the mass fraction of 36%, wherein the adding amount of the hydrochloric acid is 14g; then 5g of 28% hydrogen peroxide aqueous solution is dripped into the system for 30min, and after the dripping is finished, the temperature is kept for 2h at 75-78 ℃ to prepare a material B.

Step (3): and (3) uniformly mixing the prepared material B with 0.8g of sodium azide and 3g of water under the condition of stirring, cooling to room temperature after mixing, and discharging to obtain the modified sizing starch with the solid content of 31%.

2. Preparation of surface sizing solution

The prepared modified sizing starch and corn starch aqueous solution with the solid content of 10 percent are mixed according to the dry mass ratio of 1:1, mixing to obtain mixed sizing starch, diluting the mixed sizing starch to a solid content of 10%, and mixing with a surface sizing agent SAE and an aluminum sulfate aqueous solution to obtain a surface sizing solution. Wherein the mass fraction of aluminum sulfate in the aluminum sulfate aqueous solution is 30%. The dry mass of the modified sizing starch in the surface sizing solution, the mass of the surface sizing agent SAE and the mass ratio of the aluminum sulfate aqueous solution are 40:4.5:1.

example 2

1. Preparation of modified sizing starch

Step (1): under the condition of stirring, 25g of pulping waste liquid (the dry mass is 12.5 g) with the solid content of 50%, 50g of water and 20g of corn starch are added into a glass reaction kettle, uniformly mixed, started to be heated, and gelatinized for 0.75h at the temperature of 80 ℃ to prepare a material A.

Step (2): after the gelatinization is finished, uniformly mixing the prepared material A with 0.06g of chromium monoxide under the condition of stirring, and regulating the pH of the system to 5 by using 36% hydrochloric acid with the mass fraction, wherein the addition amount of the hydrochloric acid is 10.6g; then 4g of 28% hydrogen peroxide aqueous solution is dripped into the system for 20min, and after the dripping is finished, the temperature is kept for 1.5h at 78-81 ℃ to prepare a material B.

Step (3): and (3) uniformly mixing the prepared material B with 0.6g of methanol and 32g of water under the condition of stirring, cooling to room temperature, and discharging to obtain the modified sizing starch with the solid content of 25%.

2. Preparation of surface sizing solution

example 3

1. Preparation of modified sizing starch

Step (1): under the condition of stirring, 18g of pulping waste liquid (the dry mass is 9 g) with the solid content of 50%, 50g of water and 12g of potato starch are added into a glass reaction kettle, uniformly mixed, then the mixture is started to be heated, and the mixture is gelatinized for 1h at the temperature of 80 ℃ to prepare a material A.

Step (2): after the gelatinization is finished, uniformly mixing the prepared material A with 0.04g of vanadium dichloride under the condition of stirring, and regulating the pH value of the system to 4.7 by using hydrochloric acid with the mass fraction of 36%, wherein the adding amount of the hydrochloric acid is 8g; then 2.5g of 28% hydrogen peroxide aqueous solution is dripped into the system for 10min, and after the dripping is finished, the temperature is kept for 1h at 80-83 ℃ to prepare a material B.

Step (3): and (3) uniformly mixing the prepared material B with 0.3g of salicylic acid and 146g of water under the condition of stirring, cooling to room temperature, and discharging to obtain the modified sizing starch with the solid content of 10%.

2. Preparation of surface sizing solution

example 4

1. Preparation of modified sizing starch

Step (1): under the condition of stirring, adding 20g of pulping waste liquid with the solid content of 50% (the dry mass is 10 g), 50g of water and 22g of wheat starch into a glass reaction kettle, uniformly mixing, starting heating after mixing, and gelatinizing for 1h at the temperature of 82 ℃ to obtain a material A.

Step (2): after gelatinization, uniformly mixing the prepared material A with 0.05g of cuprous bromide under the condition of stirring, and regulating the pH of the system to 4.2 by using 36% hydrochloric acid with the mass fraction of 12g; then 3g of 28% hydrogen peroxide aqueous solution is dripped into the system for 25min, and after the dripping is finished, the temperature is kept for 1.5h at 82-85 ℃ to prepare a material B.

Step (3): and (3) uniformly mixing the prepared material B with 0.4g of methanol and 66g of water under the condition of stirring, cooling to room temperature, and discharging to obtain the modified sizing starch with the solid content of 20%.

2. Preparation of surface sizing solution

comparative example 1

Adding amylase into a corn starch aqueous solution with the mass fraction of 10%, wherein the mass of the amylase is 0.05% of that of the corn starch stock solution, stirring in a water bath with the temperature of 70-80 ℃ for a period of time, adding copper sulfate for inactivation after the viscosity is reduced to 40cPs, wherein the dosage of the copper sulfate is 2% of that of the corn starch stock solution, obtaining enzyme-converted starch solution, and preserving the temperature of the enzyme-converted starch solution at 65 ℃ for later use.

The prepared enzymatic starch solution is diluted to 10 percent and then is mixed with a surface sizing agent SAE and aluminum sulfate to prepare a surface sizing solution, wherein the dry mass of the enzymatic starch solution, the mass ratio of the surface sizing agent SAE to the aluminum sulfate is 40:4.5:1.

comparative example 2 adjustment of the order of addition of pulping effluent

Compared with example 1, the only difference is that when the modified sizing starch is prepared, the tapioca starch is gelatinized in the step (1) and then mixed with the pulping waste liquid, and the other condition parameters are the same as in example 1.

The prepared modified sizing starch is easy to coagulate and sink, discharge or form gel after being placed for a period of time, and the prepared modified sizing starch is unstable and cannot be used continuously.

Comparative example 3

Compared with the example 1, the difference is that when the modified sizing starch is prepared, the hydrogen peroxide aqueous solution is dripped in the step (2), the heat preservation treatment is not carried out, the step 3 is immediately carried out, namely, 0.8g of sodium azide and 3g of water are immediately added, the mixture is uniformly mixed, the mixture is cooled to room temperature and then discharged, and the other condition parameters are the same as the example 1.

The addition time of the reducing agent is adjusted, so that the prepared modified sizing starch is coagulated and precipitated after being cooled or placed overnight, and can not be used continuously. When the prepared surface sizing solution is used for sizing, the Cobb value, the ring crush strength, the ring crush index, the folding endurance and the bursting index of the paper are poor.

Comparative example 4

The only difference compared to example 1 is that when preparing the modified sizing starch, the oxidant in step 2 is sodium hypochlorite, the remaining condition parameters are the same as in example 1.

Due to the change of the oxidant, the obtained modified sizing starch has a gel phenomenon in the cooling process and cannot be used.

Comparative example 5

The only difference compared to example 1 is that the catalyst of step 2 is catalase and the remaining condition parameters are the same as in example 1 when preparing the modified sizing starch.

Effect examples

Sizing scheme: the corrugated paper base paper is used as raw material, and the surface sizing solutions prepared in examples 1-4, comparative example 1 and comparative example 3 are used for single-sided sizing on a sizing machine, wherein the single-sided sizing amount is 2.8g/m ² And drying the sized paper sample at 150 ℃ for 20s. The Cobb value, ring crush strength, ring crush index, folding endurance and burst index at 120s of the paper sample is measured, and the results are shown in table 1. Wherein, the Cobb value is measured according to national standard GB/T1540-2002; the ring pressure strength and the ring pressure index are measured according to national standard GB/T2679.8-2016; the folding endurance is measured according to national standard GB/T457-2002; the burst index is measured according to national standard GB/T454-2002.

TABLE 1

The surface sizing solution prepared in comparative example 5 is used for single-sided sizing of corrugated paper base paper, and the test Cobb value is 116.7g/m ² The paper is fully saturated and has little resistance to water absorption, and subsequent performance cannot be tested.

From the effect data, the method for preparing the modified sizing starch has the advantages of low-cost and easily available raw materials, simple reaction operation, green and environment-friendly process and the like, and the modified sizing starch prepared by the method reduces the consumption of starch, can be used after being directly diluted, and saves the workshop cost of enzymolysis steps. Compared with the sizing starch prepared in the comparative example 1, the surface sizing solution prepared by using the modified sizing starch can effectively improve the water absorption resistance of paper, maintain the indexes such as ring crush strength, ring crush index, folding endurance, burst index and the like to be basically stable, and can reduce the sizing cost while maintaining the paper quality.

Claims

1. The preparation method of the modified sizing starch is characterized by comprising the following steps of:

(1) Mixing and gelatinizing pulping waste liquid and starch in sequence to obtain a material A; the weight ratio of the dry weight of the pulping waste liquid to the weight of the starch is 1: (1.33-2.2); the gelatinization temperature is 70-90 ℃, and the gelatinization time is 0.5-2h;

(2) Mixing the material A with a catalyst and a hydrogen peroxide water solution, and preserving heat to obtain a material B; the adding time of the hydrogen peroxide water solution is 10-30min, the temperature of the heat preservation is 70-90 ℃, the time of the heat preservation is 1-1.5h, and the pH of the heat preservation is 4-6;

(3) Mixing the material B with a reducing agent to obtain modified sizing starch, wherein the weight ratio of the dry weight of the pulping waste liquid to the weight of the reducing agent is 1: (0.004-0.2);

in the step (2), the weight ratio of the aqueous hydrogen peroxide solution to the dry weight of the pulping waste liquid is (0.13-0.63): 1, the mass fraction of hydrogen peroxide in the hydrogen peroxide aqueous solution relative to the hydrogen peroxide aqueous solution is 24% -35%;

the pulping waste liquid is prepared by the following steps: a, selecting eucalyptus pieces and performing pre-steaming; b, pumping the aqueous solution of eucalyptus chips to the top of an independent continuous hydrolysis tower by a pump according to the mass ratio of the eucalyptus chips to water of 1:3-1:10, carrying out hydrolysis reaction on the eucalyptus chips for 1-4h at the temperature of 120-180 ℃, and extracting hydrolysis liquid from the lower part of the hydrolysis tower after the pre-hydrolysis reaction; c, steaming the hydrolyzed eucalyptus pieces by a sulfate method, wherein the steaming conditions are as follows: the hydrolyzed eucalyptus pieces are added at a constant speed at the top of a digester, the sulfidation degree of the effective alkali is 20-40% based on 16-24% of the absolute dry quantity of the eucalyptus pieces calculated by NaOH, the cooking temperature is 140-170 ℃, the mass ratio of the eucalyptus pieces to water is 1:3-1:6, the cooking time is 1-4h, and after dissolving pulp is collected, the residual substances in a hydrolysis tower are filtered, so that the pulping waste liquid is obtained.

2. The process for preparing a modified sizing starch as claimed in claim 1, wherein,

in the step (1), the starch is one or more of tapioca starch, corn starch, potato starch and wheat starch;

and/or, in step (1), the temperature of the gelatinization is 75-82 ℃;

and/or, in the step (1), the gelatinization time is 0.75-1.5h.

3. The method of producing a modified sizing starch as defined in claim 1, wherein in step (1), said pulping waste liquor, said starch and water are mixed, the ratio by weight of the pulping waste liquor to the weight of said water being 1: (2-14).

4. A method of preparing a modified sizing starch as claimed in claim 3, wherein the ratio of the dry weight of the pulping effluent to the weight of the water is 1: (3.125-8.75).

5. The process for preparing a modified sizing starch as claimed in claim 1, wherein,

in the step (1), the starch is tapioca starch, corn starch, potato starch or wheat starch;

and/or, in the step (1), the weight ratio of the dry weight of the pulping waste liquid to the weight of the starch is 1:1.6 or 1:1.87;

and/or, in step (1), the temperature of the gelatinization is 80 ℃;

and/or, in the step (1), the gelatinization time is 1h.

6. The method of producing a modified sizing starch as claimed in claim 1, wherein in the step (2), the Fe-containing component is ² ⁺ The compound is one or more of ferrous sulfide, ferrous chloride and ferrous sulfate;

and/or, in the step (2), the Cr-containing alloy ²⁺ Is one or more of chromium monoxide, chromia acetate and chromia sulfide;

and/or, in step (2), the catalyst contains V ²⁺ The compound of (a) is vanadium dichloride and/or vanadium sulfate;

and/or, in the step (2), the alloy containing Ti ³⁺ The compound of (a) is titanium trichloride;

and/or, in the step (2), the catalyst contains Co ²⁺ The compound of (a) is one or more of cobaltous oxide, cobaltous dichloride and cobalt sulfide;

and/or, in the step (2), the Cu-containing alloy ⁺ The compound of (2) is one or more of cuprous oxide, cuprous bromide and cuprous sulfide;

and/or, in the step (2), the weight ratio of the dry weight of the pulping waste liquid to the weight of the catalyst is 1: (0.0008-0.02);

and/or, in step (2), the mass fraction of hydrogen peroxide in the aqueous hydrogen peroxide solution relative to the aqueous hydrogen peroxide solution is 28%;

and/or in the step (2), the aqueous hydrogen peroxide solution is added in a dropwise manner.

7. The method of producing a modified sizing starch as claimed in claim 6, wherein in the step (2), the Fe-containing component is ² ⁺ The compound of (2) is ferrous sulfide;

and/or, in the step (2), the Cr-containing alloy ²⁺ The compound of (2) is chromium oxide;

and/or, in step (2), the catalyst contains V ²⁺ The compound of (2) is vanadium dichloride;

and/or, in the step (2), the Cu-containing alloy ⁺ The compound of (2) is cuprous bromide;

and/or, in the step (2), the weight ratio of the dry weight of the pulping waste liquid to the weight of the catalyst is 1: (0.0025-0.01);

and/or, in the step (2), the adding time of the hydrogen peroxide water solution is 20-25min;

and/or, in the step (2), the temperature of the heat preservation is 75-85 ℃;

and/or, in the step (2), the pH of the heat preservation is 4.2-5.

8. The method of producing a modified sizing starch as defined in claim 7, wherein in step (2), the ratio by weight of the dry weight of the pulping waste liquor to the weight of the catalyst is 1:0.0044, 1:0.0048, 1:0.005 or 1:0.0053;

and/or, in the step (2), the weight ratio of the aqueous hydrogen peroxide solution to the dry weight of the pulping waste liquid is 0.28: 1. 0.3: 1. 0.32:1 or 0.33:1, a step of;

and/or, in the step (2), the temperature of the heat preservation is 75-78 ℃, 78-81 ℃, 80-83 ℃ or 82-85 ℃;

and/or, in the step (2), the pH of the heat preservation is 4.5-4.7.

9. The method for producing a modified sizing starch according to any one of claims 6 to 8, wherein in the step (2), the pH of the heat preservation is adjusted by adding an acidic solution.

10. The method of preparing a modified sizing starch of claim 9, wherein the acidic solution is one or more of hydrochloric acid, sulfuric acid and acetic acid.

11. The method of preparing a modified sizing starch as claimed in claim 9, wherein the ratio of the dry weight of the pulping effluent to the weight of the acidic solution is 1:0.2-4.

12. The method of producing a modified sizing starch as claimed in claim 10, wherein when the acidic solution is hydrochloric acid, the mass fraction of hydrogen chloride in the hydrochloric acid relative to the hydrochloric acid is 36% to 38%.

13. The method of producing modified sizing starch as claimed in claim 11, wherein the ratio of the dry weight of the pulping waste liquor to the weight of the acidic solution is 1:0.5-1.88.

14. The method of producing a modified sizing starch as claimed in claim 12, wherein the mass fraction of hydrogen chloride in the hydrochloric acid relative to the hydrochloric acid is 36%.

15. The method of preparing a modified sizing starch according to claim 1, wherein in step (3), the reducing agent is one or more of sodium bisulfite, sodium azide, sodium nitrite, sodium thiosulfate, potassium iodide, methanol, t-butanol, salicylic acid, benzoic acid and phenol;

and/or in the step (3), the solid content of the mixed material obtained after the mixing is 8% -32%;

and/or, in the step (3), the mixed materials further comprise cooling treatment.

16. The method of producing a modified sizing starch as defined in claim 1, wherein in step (3), said material B, said reducing agent and water are mixed, and the weight ratio of said pulping waste liquid to said water is 1: (0.12-30).

17. The method of producing modified sizing starch as claimed in claim 16, wherein in step (3), said material B, said reducing agent and water are mixed, and the weight ratio of said pulping waste liquid to said water is 1: (0.1875-18.25).

18. The method of producing modified sizing starch as claimed in claim 17, wherein said material B, said reducing agent and water are mixed, and the weight ratio of said pulping waste liquid to said water is 1:0.2, 1:2.56, 1:6.6 or 1:16.22.

19. the method of producing a modified sizing starch as claimed in claim 15, wherein in step (3), the reducing agent is sodium azide, methanol or salicylic acid.

20. The method of producing a modified sizing starch as claimed in claim 1, wherein in step (3), the ratio by weight of the pulping waste liquor to the reducing agent is 1: (0.019-0.1).

21. The method of producing modified sizing starch as claimed in claim 20, wherein in step (3), the ratio by weight of the pulping waste liquor to the reducing agent is 1:0.033, 1:0.04, 1:0.048 or 1:0.053.

22. a modified sizing starch, characterized in that it is produced by the method for producing a modified sizing starch according to any one of claims 1 to 21.

23. The modified sizing starch of claim 22, wherein the modified sizing starch has a solids content of 8 to 32%.

24. The modified sizing starch of claim 23, wherein the modified sizing starch has a solids content of 10 to 31%.

25. The modified sizing starch of claim 24, wherein the modified sizing starch has a solids content of 20 to 25%.

26. A surface sizing solution, characterized in that it comprises a modified sizing starch according to any one of claims 22 to 25.

27. The surface sizing of claim 26, wherein the surface sizing further comprises starch, surface sizing agent SAE, and aluminum sulfate.

28. The surface sizing solution of claim 27, wherein the modified sizing starch has a dry mass to mass ratio of 1: (0.8-5);

and/or, the starch is corn starch and/or tapioca starch;

and/or the ratio of the dry mass of the modified sizing starch to the mass of the surface sizing agent SAE is (5-11.25): 1, a step of;

and/or the dry mass of the modified sizing starch to the mass of the aluminum sulfate is (100-150): 1.

29. the surface sizing solution of claim 27, wherein the aluminum sulfate is used in a form configured as an aqueous aluminum sulfate solution, the aqueous aluminum sulfate solution comprising 25-40% aluminum sulfate by mass.

30. The surface sizing solution of claim 29, wherein the aluminum sulfate in the aqueous aluminum sulfate solution comprises 30% by mass.

31. A surface sizing solution according to claim 27, wherein the starch is used in the form of an aqueous starch solution, the starch having a solids content of 8% to 18%.

32. The surface sizing solution of claim 31, wherein the starch in the aqueous starch solution has a solids content of 10%.

33. The surface sizing solution of claim 28, wherein the modified sizing starch has a dry mass to mass ratio of 1:1, a step of;

and/or the ratio of the dry mass of the modified sizing starch to the mass of the surface sizing agent SAE is 8.9:1, a step of;

and/or the dry mass of the modified sizing starch to the mass ratio of the aluminum sulfate is 133.3:1.

34. use of a surface sizing agent according to any one of claims 26 to 33 as a sizing agent in a paper making and sizing process.