Paper product, coating, biological adhesive and preparation method thereof

Abstract

The invention provides a paper product, a coating, a biological adhesive and a preparation method thereof. The preparation method of the biological adhesive comprises the following steps: adding starch and dextrin into water, and stirring to obtain first mixed slurry; adding a composite plasticizer into the first mixed slurry, and stirring to obtain second mixed slurry; and heating the second mixed slurry to obtain the biological adhesive. According to the preparation method of the biological adhesive provided by the embodiment of the invention, a non-digestion conversion process is adopted, renewable resources, namely dextrin and starch, are taken as main bodies, dextrin plays a role in improving the stability of a glue solution, and then the high-performance biological adhesive is obtained by adding a composite plasticizer and controlling the viscosity parameter of the glue solution; the adhesive can be used in pre-coating and top-coating coatings, the prepared coating has high strength, and the defect of low strength of an enzymatically converted starch adhesive is overcome.

Description

Technical Field

[0001] The present application relates to the technical field of papermaking, and specifically to a paper product, a coating, a bio-type adhesive and a preparation method thereof. Background Art

[0002] Enzyme-converted starch has low production costs and low equipment requirements. Large papermakers basically use automated continuous conversion processes, and small companies also use intermittent processes to prepare enzyme-converted starch. Currently, enzyme-converted starch has been widely used in paper surface sizing and coating.

[0003] Enzymatic conversion of starch is the process of hydrolyzing the α-1,4 glycosidic bonds in starch molecules by α-amylase, reducing viscosity and improving fluidity, and is suitable for use in papermaking surface sizing and coating.

[0004] With fierce competition in the papermaking industry, mills are reducing costs by using large amounts of APMP pulp and increasing ash content. This places increasingly stringent demands on coatings, leading to a significant increase in coating adhesives and a significant increase in coating costs. When starch chains are long, the intermolecular interactions are strong, making them more susceptible to entanglement, resulting in higher coating viscosity and poor fluidity. Enzymatic cleavage, however, reduces the length of the starch chains and weakens the intermolecular interactions, reducing the coating's viscosity and improving fluidity. Enzymatic conversion of starch requires a high degree of cleavage, resulting in shorter chains. Shorter chains, during the drying process, are unable to form the same extensive and dense network structure as longer chains. This results in insufficient cohesion in the cured adhesive film, which in turn affects its bond strength to the adherend. Summary of the Invention

[0005] A first aspect of the present application provides a method for preparing a bio-based adhesive, the method comprising:

[0006] Adding starch and dextrin into water and stirring to obtain a first mixed slurry;

[0007] adding a composite plasticizer to the first mixed slurry and stirring to obtain a second mixed slurry;

[0008] The second mixed slurry is subjected to a heat treatment to obtain a bio-type adhesive.

[0009] In some optional embodiments, in the step of adding starch and dextrin into water and stirring to obtain a first mixed slurry, the weight ratio of the starch to the dextrin is: starch accounts for 70-90%, and dextrin accounts for 10-30%.

[0010] In some optional embodiments, the starch is selected from a mixture of any one or more of tapioca starch, corn starch, potato starch and wheat starch; the paste is selected from a starch dextrin of any one of tapioca starch, corn starch, potato starch and wheat starch, or a mixture of multiple starch dextrins.

[0011] In some optional embodiments, in the step of adding a composite plasticizer to the first mixed slurry and stirring to obtain a second mixed slurry, the composite plasticizer includes glycerol, ethylene glycol and formamide.

[0012] In some optional embodiments, based on 100 parts of the first mixed slurry, the amount of glycerol added is 10-20 parts, the amount of ethylene glycol added is 5-15 parts, and the amount of formamide added is 0.5-1 part.

[0013] In some optional embodiments, the step of heating the second mixed slurry to obtain a bio-based adhesive includes: heating the second mixed slurry to a first preset temperature and keeping it warm for a preset time, and then heating it to a second preset temperature for steaming; wherein the first preset temperature is 80-85 degrees, the preset time is 15-30 minutes, and the second preset temperature is 130-140 degrees.

[0014] In some optional embodiments, the physical properties of the bio-adhesive are as follows: solid content of 35-45%, viscosity of 500-2000 cps, and pH of 7.5-8.5.

[0015] In a second aspect, an embodiment of the present application provides a bio-based adhesive, which is prepared using the preparation method described in the above embodiment.

[0016] In a third aspect, an embodiment of the present application provides a coating comprising calcium carbonate, latex, and the bio-based adhesive of the above embodiment.

[0017] In a fourth aspect, an embodiment of the present application provides a paper product, comprising base paper and the coating described in the above embodiment coated on the surface of the base paper.

[0018] The preparation method of the bio-based adhesive provided in the embodiment of the present application adopts an enzyme-free conversion process, with renewable resources dextrin and starch as the main components. Dextrin plays a role in improving the stability of the adhesive solution. Then, by adding a composite plasticizer, the viscosity parameters of the adhesive solution are controlled to obtain a high-performance bio-based adhesive. The adhesive can be used in both pre-coating and topcoating coatings. The prepared coating has high-strength performance, which solves the low strength disadvantage of enzyme-converted starch adhesives. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0020] Figure 1 This is a flow chart of an embodiment of a method for preparing a bio-based adhesive according to the present application;

[0021] Figure 2 It is a schematic diagram of the stacking structure of an embodiment of the paper product of the present application. DETAILED DESCRIPTION

[0022] The present application will be further described in detail below in conjunction with the accompanying drawings and examples. It is particularly noted that the following examples are only intended to illustrate the present application and are not intended to limit the scope of the present application. Similarly, the following examples are only some examples of the present application and not all examples. All other examples obtained by those of ordinary skill in the art without creative work are intended to fall within the scope of protection of this application.

[0023] The terms "first", "second" and "third" in the embodiments of the present application are used only for descriptive purposes and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, a feature defined as "first", "second" and "third" may explicitly or implicitly include at least one of such features. In the description of the present application, "multiple" means at least two, for example, two, three, etc., unless otherwise clearly and specifically defined. All directional indications in the embodiments of the present application (such as up, down, left, right, front, back...) are only used to explain the relative positional relationship, movement, etc. between the components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication also changes accordingly. The terms "including" and "having" in the embodiments of the present application and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device that includes a series of steps or units is not limited to the listed steps or units, but optionally also includes steps or units that are not listed, or optionally also includes other steps or components inherent to these processes, methods, products or devices.

[0024] References herein to "embodiments" mean that a particular feature, structure, or characteristic described in connection with the embodiments may be included in at least one embodiment of the present application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor does it constitute an independent or alternative embodiment that is mutually exclusive of other embodiments. It is understood, both explicitly and implicitly, by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0025] The technical solution of the present application adopts renewable resources dextrin and starch as the main body, adds a composite plasticizer, and plasticizes and modifies to obtain a high-strength bio-type adhesive. No amylase and oxidant are added during the preparation process, the starch molecular chains are not cut and the long starch molecular chains are maintained. The long molecular chains form an extensive and tight network structure. The adhesive film formed after the adhesive is cured has high cohesion and high bonding strength to the adherend, thereby improving the strength of the paper after coating.

[0026] See also Figure 1 , Figure 1 1 is a flow chart of an embodiment of a method for preparing a bio-based adhesive according to the present invention, and the method includes but is not limited to the following steps.

[0027] Step S100: Add starch and dextrin into water and stir to obtain a first mixed slurry.

[0028] In this step, the solid content of the first mixed slurry is 35%-45%; the weight ratio of starch and dextrin is: starch accounts for 70-90%, and dextrin accounts for 10-30%. Among them, starch can be selected from a mixture of any one or more of cassava starch, corn starch, potato starch and wheat starch; dextrin can be selected from any one of cassava starch, corn starch, potato starch and wheat starch starch dextrin or a mixture of multiple starch dextrins. That is, it is not limited to the same starch and the dextrin corresponding to the starch. It can be a dextrin of cassava starch and corn starch, a mixture of corn starch + potato starch and wheat starch dextrin, a combination of cassava starch + corn starch + potato starch and corn starch dextrin + potato starch dextrin + wheat starch dextrin, etc., which is not specifically limited here.

[0029] What needs to be explained here is that dextrin: when starch is decomposed and hydrolyzed under the action of heating, acid or amylase, the large-molecule starch is first converted into a small-molecule intermediate substance. At this time, the intermediate small-molecule substance is called dextrin.

[0030] Please continue reading Figure 1 The preparation method in this embodiment further includes step S200 of adding a composite plasticizer to the first mixed slurry and stirring to obtain a second mixed slurry.

[0031] In step S200, the composite plasticizer includes a mixture of propylene glycol, ethylene glycol and formamide. The first mixed slurry is 100 parts, the added amount of propylene glycol is 10-20 parts, the added amount of ethylene glycol is 5-15 parts, and the added amount of formamide is 0.5-1 part; the mixture is evenly mixed to obtain a second mixed slurry.

[0032] Please continue reading Figure 1The preparation method in this embodiment further includes step S300, heating the second mixed slurry to obtain a bio-based adhesive.

[0033] This step includes heating the second mixed slurry to a first preset temperature and holding it for a preset time, then heating it to a second preset temperature for steaming. The first preset temperature is 80-85 degrees Celsius, the preset holding time is 15-30 minutes, and the second preset temperature is 130-140 degrees Celsius. Specifically, the mixture can be heated to 130-140 degrees Celsius using a jet cooker for steaming, then cooled and pumped to a storage tank to obtain the enzyme-free bio-adhesive product.

[0034] The physical properties of the non-enzymatically converted bio-adhesive in the examples of the present application are as follows: solid content of 35-45%, viscosity of 500-2000 cps, and pH of 7.5-8.5.

[0035] Several specific embodiments will be introduced below.

[0036] Example 1: Weigh a certain amount of cassava starch, add water and mix evenly, then add dextrin, the absolute dry weight ratio of cassava starch to dextrin is 90:10, and after thorough mixing, a slurry with a solid content of 40% is prepared. To the above starch slurry, 20 parts of glycerol, 5 parts of ethylene glycol, and 0.5 parts of formamide are added, with the total amount of starch and dextrin being 100 parts. After stirring evenly, the mixed slurry is heated to 85 degrees and kept warm for 20 minutes, then heated to 135 degrees by jet cooker for cooking, and pumped to a storage tank to obtain a bio-type adhesive sample 1.

[0037] Example 2: Weigh a certain amount of corn starch, add water and mix evenly, then add dextrin, the absolute dry weight ratio of corn starch to dextrin is 80:20, and after thorough mixing, the slurry is prepared with a solid content of 45%. With the total amount of starch and dextrin as 100 parts, 15 parts of glycerol, 10 parts of polyethylene glycol, and 1 part of formamide are added to the above starch slurry. After stirring evenly, the mixed slurry is heated to 85 degrees and kept warm for 15 minutes, then heated to 130 degrees by JETCOOKER for steaming, and pumped to a storage tank to obtain a bio-adhesive sample 2.

[0038] Example 3: Weigh a certain amount of potato starch, add water and mix evenly, then add dextrin, the absolute dry weight ratio of potato starch to dextrin is 70:30, and after thorough mixing, the slurry is prepared with a solid content of 35%. With the total amount of starch and dextrin as 100 parts, 10 parts of glycerol, 15 parts of ethylene glycol, and 0.8 parts of formamide are added to the above starch slurry. After stirring evenly, the mixed slurry is heated to 85 degrees and kept warm for 30 minutes, then heated to 140 degrees by JETCOOKER for cooking, and pumped to a storage tank to obtain bio-adhesive sample three.

[0039] The preparation method of the bio-based adhesive in the embodiment of the present application uses renewable resources dextrin and starch as the main body, adds a composite plasticizer, and plasticizes and modifies to obtain a high-strength bio-based adhesive. No amylase and oxidant are added during the preparation process, the starch molecular chains are not cut and the long starch molecular chains are maintained. The long molecular chains form an extensive and tight network structure. The adhesive film formed after the adhesive is cured has high cohesion and high bonding strength to the adherend, thereby improving the strength of the paper after coating.

[0040] Next, the application examples of the bio-based adhesive in the embodiments of the present application will be introduced.

[0041] A pre-coating coating for coating, wherein the pre-coating coating contains the enzyme-free conversion bio-type adhesive described in any one of the present invention; the pre-coating coating for coating comprises the following raw materials in parts by weight: a total of 100 parts of ground calcium carbonate C65, 6 parts of styrene-butadiene latex, 8 parts of starch-type adhesive, 0.2 parts of alkali solution, 0.2 parts of dispersant, and 0.05 parts of defoamer, wherein the ground calcium carbonate C65 has a particle size of less than 2 μm and accounts for more than 65%; according to the above weight ratios, the ground calcium carbonate C65, styrene-butadiene latex, bio-type adhesive / starch, dispersant and defoamer are added in sequence and stirred, and the alkali solution needs to be added while stirring. After sufficient stirring, a thickener is used to adjust the viscosity to a solid content of 65-68% and a viscosity of 1000-2000 cps, and the pH is adjusted to 9.0 to obtain the pre-coating coating for coating.

[0042] The topcoat for coating includes the following raw materials in parts by weight: 100 parts of ground calcium carbonate C98, 10 parts of styrene-butadiene latex, 0.2 parts of alkali solution, 0.2 parts of dispersant, 0.05 parts of defoaming agent, and 0.4 parts of water-resistance agent, wherein the ground calcium carbonate C98 has a particle size of less than 2 μm and accounts for more than 98%; according to the above weight ratio, the ground calcium carbonate C98, styrene-butadiene latex, bio-type adhesive, dispersant, defoaming agent and water-resistance agent are added in sequence and stirred, and the alkali solution needs to be added while stirring. After sufficient stirring, the viscosity is adjusted to 67-71% of the solid content and 1600-3000 cps with a thickener, and the pH is adjusted to 9.0 to obtain the topcoat for coating.

[0043] In addition, this embodiment of the application also provides a paper product, please refer to Figure 2 , Figure 2 1 is a schematic diagram of the stacking structure of an embodiment of the paper product of the present application, wherein the paper product in this embodiment may include a base paper 110 and a pre-coating layer 120 and a top coating layer 130 stacked on the surface of the base paper 110. This embodiment only uses the stacking structure of one paper product as an example for explanation. In some other embodiments, it may include only one coating layer or multiple coating layers, etc., which will not be listed and described in detail here.

[0044] The following table compares the parameters of several coatings used in paper.

[0045]

[0046] From the comparison in the above table, it can be seen that the enzyme-converted starch adhesive (control group) has the disadvantage of poor strength due to the shorter starch chains after enzymatic cleavage. The bio-type adhesive in the embodiment of the present application is significantly better than the enzyme-converted starch adhesive in terms of strength, and the printing quality of the paper meets the requirements.

[0047] The above descriptions are only some embodiments of the present application and do not limit the scope of protection of the present application. Any equivalent device or equivalent process transformation made using the contents of the description and drawings of this application, or directly or indirectly applied in other related technical fields, are also included in the scope of patent protection of this application.

Claims

1. A method for preparing a bio-adhesive, characterized in that: The preparation method comprises: Adding starch and dextrin into water and stirring to obtain a first mixed slurry; adding a composite plasticizer to the first mixed slurry and stirring to obtain a second mixed slurry; The second mixed slurry is subjected to a heat treatment to obtain a bio-type adhesive.

2. The preparation method according to claim 1, characterized in that In the step of adding starch and dextrin into water and stirring to obtain a first mixed slurry, the weight ratio of the starch to the dextrin is: starch accounts for 70-90%, and dextrin accounts for 10-30%.

3. The preparation method according to claim 2, characterized in that The starch is selected from a mixture of any one or more of cassava starch, corn starch, potato starch and wheat starch; the paste is selected from a starch dextrin of any one of cassava starch, corn starch, potato starch and wheat starch or a mixture of multiple starch dextrins.

4. The preparation method according to claim 1, characterized in that In the step of adding a composite plasticizer to the first mixed slurry and stirring to obtain a second mixed slurry, the composite plasticizer includes glycerol, ethylene glycol and formamide.

5. The preparation method according to claim 4, characterized in that Taking the first mixed slurry as 100 parts, the added amount of glycerol is 10-20 parts, the added amount of ethylene glycol is 5-15 parts, and the added amount of formamide is 0.5-1 part.

6. The preparation method according to claim 1, characterized in that The step of heating the second mixed slurry to obtain a bio-based adhesive includes: heating the second mixed slurry to a first preset temperature and keeping it warm for a preset time, and then heating it to a second preset temperature for steaming; wherein the first preset temperature is 80-85 degrees, the preset time is 15-30 minutes, and the second preset temperature is 130-140 degrees.

7. The preparation method according to claim 1, characterized in that The physical properties of the bio-adhesive are as follows: solid content of 35-45%, viscosity of 500-2000 cps, and pH of 7.5-8.

5.

8. A bio-adhesive, characterized in that: The bio-adhesive is prepared by the preparation method according to any one of claims 1 to 7.

9. A coating, characterized in that: The coating comprises calcium carbonate, latex and the bio-adhesive according to claim 8.

10. A paper product, characterized in that: The paper product comprises base paper and the coating according to claim 9 coated on the surface of the base paper.

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