Paper product, sizing starch and method for retarding aging of sizing starch

Abstract

The invention provides a paper product, sizing starch and a method for slowing down aging of the sizing starch. The method for slowing down aging of sizing starch comprises the following steps: putting gelatinized sizing starch into a storage tank; the sizing starch in the storage tank is conveyed to a sizing feeding tank; wherein in the conveying process, water is used for diluting the sizing starch, and the temperature of the sizing starch is controlled between 60 DEG C and 80 DEG C. According to the method for slowing down aging of sizing starch provided by the embodiment of the invention, corn starch in surface sizing can be applied in a large proportion mainly by controlling the temperature and the PH value of the glue solution, and the stability of the glue solution is enhanced.

Description

Technical Field

[0001] The present application relates to the technical field of preparation of sizing starch for papermaking, and in particular to a paper product, sizing starch and a method for slowing down aging of sizing starch. Background Art

[0002] In recent years, due to the sluggish market and great pressure to reduce costs, the domestic papermaking industry has gradually promoted the use of corn starch in the industry. Compared with potato and cassava starch, corn starch has a high content of amylose, high fat content, and high protein content, which will have some adverse effects on the gelatinization, paste properties and industrial application of starch. Starch exists in plants as tiny particles, with particles as small as 5-100um. Starch is easily dispersed in water to form a suspension. At present, the cooking process of cassava starch and corn starch is basically the same, as follows: starch is dispersed in water to form a suspension; a certain amount of amylase is added, and the temperature is heated to 85-90 degrees, so that it absorbs water and expands to form a translucent viscous paste (called pre-gelatinization); the starch paste is heated and cooked by steam jet, and the temperature is instantly raised to 130-160 degrees and under strong mechanical shear, the starch particles are broken to obtain a starch solution. Therefore, it is very important to master the key factors in the starch cooking process for the use and characteristics of starch. At the same time, since the content of amylose in corn starch is 24%, which is high and has a low degree of polymerization, while the content of amylose in cassava starch is 17%, and the degree of polymerization of amylose is high, in the application of corn starch, it is more inclined to be linked to each other to form crystalline aggregates (starch precipitation). In order to enable corn starch to be widely used in the papermaking industry and reduce unfavorable factors that affect production operations, such as stick sticking and uneven feeding, it is necessary to develop or invent a process to slow down the aging of corn starch to ensure continuous and normal production operations. Summary of the invention

[0003] The first aspect of the embodiment of the present application provides a method for slowing down the aging of sizing starch, the method comprising:

[0004] placing the gelatinized sizing starch in a storage tank;

[0005] The sizing starch in the storage tank is transported to the sizing feeding tank; during the transportation process, the sizing starch is diluted with water, and the temperature of the sizing starch is controlled between 60° C. and 80° C.

[0006] In some embodiments, the step of diluting the sizing starch with water includes diluting the sizing starch with clean water at room temperature.

[0007] In some embodiments, the step of diluting the sizing starch with water further comprises: using room temperature clean water and warm water to mix and adjust the diluted sizing starch to a concentration (solid content) of 12-20%.

[0008] In some embodiments, the temperature of the warm water is 45±5°C.

[0009] In some embodiments, during the conveying process, the sizing starch is diluted with water, and the temperature of the sizing starch is controlled between 65° C. and 75° C.

[0010] In some embodiments, the method further comprises: adding citric acid during the conveying process so that the pH value of the sizing starch is 3.5±0.5.

[0011] In some embodiments, the amount of citric acid added is 0.4±0.1% of the absolute dry starch amount.

[0012] In some embodiments, the sizing starch placed in the storage tank after gelatinization includes: the ratio of corn starch to cassava starch ranges from 50%:50% to 100%:0%; the solid content of the sizing starch after gelatinization is 28-32%, and the temperature is 95-98°C.

[0013] In a second aspect, an embodiment of the present application provides a sizing starch, and the sizing starch is prepared by the method described in the above embodiment.

[0014] In a third aspect, an embodiment of the present application provides a paper product, which is prepared using the sizing starch described in the above embodiment.

[0015] The method for slowing down the aging of sizing starch provided in the embodiment of the present application mainly controls the temperature and pH value of the glue solution, so that corn starch can be used in a large proportion in surface sizing and the stability of the glue solution is enhanced. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the description of the embodiments will be briefly introduced below. 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 creative work.

[0017] Figure 1 This is a flow chart of an embodiment of a method for slowing down aging of sizing starch of the present application;

[0018] Figure 2 It is a structural schematic diagram of an embodiment of the storage and transmission process of sizing starch;

[0019] Figure 3 This is a flow chart of another embodiment of the method for slowing down the aging of sizing starch of the present application;

[0020] Figure 4 It is a structural schematic diagram of another embodiment of the storage and transportation process of sizing starch. DETAILED DESCRIPTION

[0021] The present application is further described in detail below in conjunction with the accompanying drawings and examples. It is particularly noted that the following examples are only used to illustrate the present application, but are not intended to limit the scope of the present application. Similarly, the following examples are only some embodiments of the present application rather than all embodiments, and all other embodiments obtained by ordinary technicians in the field without making creative work are within the scope of protection of the present application.

[0022] The terms "first", "second", and "third" in the embodiments of the present application are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of indicated technical features. Thus, the features defined as "first", "second", and "third" can expressly or implicitly include at least one of the features. In the description of the present application, the meaning of "multiple" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined. In the embodiments of the present application, all directional indications (such as up, down, left, right, front, back...) are only used to explain the relative position 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 of their variations 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.

[0023] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0024] When a large amount of corn starch is used for papermaking surface sizing, the sizing material in the feeding system is prone to coagulation (also known as aging), resulting in problems such as sticking or uneven feeding, thereby causing paper defects and affecting quality and operation. Without solving the above problems, the embodiments of the present application first provide a method for slowing down the aging of sizing starch.

[0025] Please also read Figure 1 and Figure 2 , Figure 1 This is a flow chart of an embodiment of the method for slowing down the aging of sizing starch in the present application. Figure 2It is a structural schematic diagram of an embodiment of the storage and transmission process of sizing starch; the method includes but is not limited to the following steps.

[0026] Step S100, placing the gelatinized sizing starch in a storage tank.

[0027] Among them, the ratio of starch including corn starch and cassava starch ranges from 50%:50% to 100%:0%. Specifically, the starch is dispersed in water to form a suspension, and then a certain amount of amylase is added, and the temperature is heated to 85-90 degrees, so that it absorbs water and expands to form a translucent viscous paste (called pre-gelatinization); the starch paste is heated and cooked by steam jet, and the temperature is instantly raised to 130-160 degrees and under strong mechanical shear, the starch particles are broken to obtain a starch solution. The detailed process and parameters of gelatinization are within the understanding of those skilled in the art and will not be repeated here.

[0028] The solid content of the formed gelatinized sizing starch is 28-32%, and the specific values ​​of the solid content can be 28%, 28.3%, 28.5%, 29%, 29.2%, 29.6%, 30%, 31.4%, 32% and the like; the temperature of the gelatinized sizing starch is 95-98° C. The gelatinized sizing starch solution is placed in the storage tank 110 .

[0029] Please continue reading Figure 1 The method for slowing down the aging of sizing starch in this embodiment also includes step S200, transporting the sizing starch in the storage tank to the sizing feeding tank, wherein during the transportation process, the sizing starch is diluted with water and the temperature of the sizing starch is controlled between 60°C and 80°C.

[0030] Optionally, see Figure 2 In this step, the sizing starch is diluted with clean water at room temperature (pure water at 20±10°C) at the outlet of the storage tank 110, and the sizing starch is diluted with clean water at room temperature (pure water at 20±10°C) and warm water in the transmission pipeline 120 to a concentration (solid content) of 12-20%, and then transported to the sizing feed tank 130. The specific value of the solid content of the sizing starch after dilution can be 12%, 12.3%, 13.5%, 14%, 15.2%, 16.6%, 17%, 18.4%, 20%, etc. The temperature of the warm water is 45±5°C.

[0031] In this step, the sizing starch is first diluted with clean water, and then the clean water (20±10℃) and warm water (45±5℃) are used to mix and adjust the dilution to achieve automatic control. Not only can the concentration of the secondary dilution be controlled, but also the temperature of the sizing material during the feeding process can be controlled at 70±10℃, specifically, the temperature can be controlled at 70±5℃, such as 65℃, 66℃, 68.5℃, 69℃, 70℃, 72℃, 73℃, 75℃ and other values. Because if the temperature is lower than 60℃, the sizing material will "reverse", also known as aging, regeneration or coagulation (settling), which will increase the viscosity, resulting in the risk of paper surface not absorbing sizing material easily, uneven sizing, and sticking during surface sizing. If the temperature is higher than 80℃, the starch will continue to be thermochemically denatured, the long-chain starch will become shorter, and the viscosity will continue to decrease, affecting the feeding and paper strength.

[0032] The method for slowing down the aging of sizing starch provided in the embodiment of the present application mainly controls the temperature and solid content of the glue solution, so that a large proportion of corn starch can be used in surface sizing and the stability of the glue solution is enhanced.

[0033] Please also read Figure 3 and Figure 4 , Figure 3 This is a flow chart of another embodiment of the method for slowing down the aging of sizing starch of the present application. Figure 4 It is a structural schematic diagram of another embodiment of the storage and transmission process of sizing starch; the method for slowing down the aging of sizing starch in this embodiment includes but is not limited to the following steps.

[0034] Step S100, placing the gelatinized sizing starch in a storage tank.

[0035] The starch includes corn starch and tapioca starch in a ratio ranging from 50%:50% to 100%:0%. Specifically, the starch is dispersed in water to form a suspension, and then a certain amount of amylase is added and heated to 85-90 degrees to make it swell by absorbing water and form a translucent viscous paste (called pre-gelatinization); the starch paste is heated and cooked by steam jet, and the temperature is instantly raised to 130-160 degrees and under strong mechanical shearing, the starch particles are broken to obtain a starch solution.

[0036] The solid content of the formed gelatinized sizing starch is 28-32%, and the specific values ​​of the solid content can be 28%, 28.3%, 28.5%, 29%, 29.2%, 29.6%, 30%, 31.4%, 32% and the like; the temperature of the gelatinized sizing starch is 95-98° C. The gelatinized sizing starch solution is placed in the storage tank 110 .

[0037] Please continue reading Figure 3The method for slowing down the aging of sizing starch in this embodiment also includes step S200, transporting the sizing starch in the storage tank to the sizing feeding tank, wherein during the transportation process, the sizing starch is diluted with water and the temperature of the sizing starch is controlled between 60°C and 80°C.

[0038] Optionally, see Figure 4 In this step, the sizing starch is diluted with clean water at room temperature (pure water at 20±10°C) at the outlet of the storage tank 110, and the sizing starch is diluted with clean water at room temperature (pure water at 20±10°C) and warm water in the transmission pipeline 120 to a concentration (solid content) of 12-20%, and then transported to the sizing feed tank 130. The specific value of the solid content of the sizing starch after dilution can be 12%, 12.3%, 13.5%, 14%, 15.2%, 16.6%, 17%, 18.4%, 20%, etc. The temperature of the warm water is 45±5°C.

[0039] In this step, the sizing starch is first diluted with clean water, and then the clean water (20±10℃) and warm water (45±5℃) are used to mix and adjust the dilution to achieve automatic control. Not only can the concentration of the secondary dilution be controlled, but also the temperature of the sizing material during the feeding process can be controlled at 70±10℃, specifically, the temperature can be controlled at 70±5℃, such as 65℃, 66℃, 68.5℃, 69℃, 70℃, 72℃, 73℃, 75℃ and other values. Because if the temperature is lower than 60℃, the sizing material will "reverse", also known as aging, regeneration or coagulation (settling), which will increase the viscosity, resulting in the risk of paper surface not absorbing sizing material easily, uneven sizing, and sticking during surface sizing. If the temperature is higher than 80℃, the starch will continue to be thermochemically denatured, the long-chain starch will become shorter, and the viscosity will continue to decrease, affecting the feeding and paper strength.

[0040] Please continue reading Figure 3 Different from the above-mentioned embodiment, the method for slowing down the aging of sizing starch in this embodiment further includes step S300, adding citric acid during the conveying process to make the pH value of the sizing starch at 3.5±0.5, so as to slow down the aging of corn starch in the glue solution.

[0041] The citric acid is added in the following manner: dissolving the citric acid particles in normal temperature water to a concentration of 4±2%, and then adding the citric acid particles continuously. This is because the carboxyl groups on the citric acid are more likely to produce hydrogen bonds with the hydroxyl groups on the starch, thereby hindering the hydrogen bonding between the starch molecules and causing them to aggregate, thus slowing down or preventing starch aging.

[0042] Optionally, in this step, the pH value of the sizing starch after adding citric acid can be 3.0, 3.1, 3.22, 3.4, 3.54, 3.6, 3.78, 3.85, 3.9, 4.0, etc. The amount of citric acid added is 0.4±0.1% of the absolute dry starch amount, and can be 0.3%, 0.32%, 0.33%, 0.35%, 0.38%, 0.40%, 0.41%, 0.45%, 0.48%, 0.50%, etc. of the absolute dry starch amount.

[0043] Please refer to the table below, which compares the experimental data of several different added drugs.

[0044]

[0045]

[0046] From the table above, it can be seen that the effect is better when the amount of the sizing agent is increased to 3%. Citric acid can also be used at the same time, which is also significantly helpful in resisting aging crusting. Sodium trimetaphosphate is also effective, but the pH of the reaction is too high, which is not conducive to the stability of the sizing agent, and acid needs to be used to adjust the pH.

[0047] The method for slowing down the aging of sizing starch provided in the embodiment of the present application mainly controls the temperature (70±10°C), solid content (12-20%) and pH value (adding citric acid to control the pH value of the loading sizing solution to 3.5±0.5) of the sizing solution, which can not only stably control the temperature of the sizing solution, prevent the "retrograde" of the sizing material, and slow down the aging of corn starch in the sizing solution, but also control the pH value of the sizing solution by citric acid, further enhance the stability of the sizing solution, and slow down the aging. The method has the characteristics of low cost and significant effect, so that corn starch can be used in a large proportion in surface sizing.

[0048] Several specific embodiments are described below.

[0049] Example 1

[0050] The ratio of corn starch to cassava starch is 80:20, and they are heated for pre-gelatinization. After gelatinization, the solid content of the sizing starch is 28%, the temperature is 95°C, and it enters the storage tank. At the outlet of the storage tank, it is first diluted with clean water (20±10°C pure water), and then diluted with clean water (20±10°C) and warm water (45±5°C) to a concentration (solid content) of 12%. The temperature of the sizing starch is controlled at 60°C to 80°C, citric acid is added (the amount added is 0.3% of the amount of absolute dry starch), and the pH of the feeding glue is controlled to be around 3.0 before entering the sizing feeding tank.

[0051] Example 2

[0052] The ratio of corn starch to cassava starch is 100:0, and they are heated for pre-gelatinization. After gelatinization, the solid content of the sizing starch is 30%, the temperature is 96°C, and it enters the storage tank. At the outlet of the storage tank, it is first diluted with clean water (20±10°C pure water), and then diluted with clean water (20±10°C) and warm water (45±5°C) to a concentration (solid content) of 18%. The temperature of the sizing starch is controlled at 60°C to 80°C, citric acid is added (the amount added is 0.4% of the amount of absolute dry starch), and the pH of the feeding glue is controlled to be around 3.5 before entering the sizing feeding tank.

[0053] Example 3

[0054] The ratio of corn starch to cassava starch is 80:20, and they are heated for pre-gelatinization. After gelatinization, the solid content of the sizing starch is 32%, and the temperature is 98°C. It enters the storage tank and is first diluted with clean water (20±10°C pure water) at the outlet of the storage tank. Then, it is diluted with clean water (20±10°C) and warm water (45±5°C) to a concentration (solid content) of 20%. The temperature of the sizing starch is controlled at 60°C to 80°C, and citric acid is added (the amount added is 0.5% of the amount of absolute dry starch). The pH of the feeding glue is controlled to be around 4.0 before entering the sizing feeding tank.

[0055] In addition, the present application also provides a sizing starch for papermaking and a paper product, wherein the sizing starch is prepared by the method in the above embodiment; the paper product is prepared by the sizing starch in the above embodiment. The detailed structure of the paper product and other process are within the scope of understanding of those skilled in the art and will not be described in detail here.

[0056] The method for slowing down the aging of sizing starch provided in the embodiment of the present application mainly controls the temperature and pH of the glue solution, so that corn starch can be used in a large proportion in surface sizing and the stability of the glue solution is enhanced.

[0057] The above descriptions are only some embodiments of the present application, and do not limit the protection scope of the present application. Any equivalent device or equivalent process transformation made using the contents of the present application specification and drawings, or directly or indirectly used in other related technical fields, are also included in the patent protection scope of the present application.

Claims

1. A method for slowing down the aging of sizing starch, characterized in that: The method comprises: placing the gelatinized sizing starch in a storage tank; The sizing starch in the storage tank is transported to the sizing feeding tank; during the transportation process, the sizing starch is diluted with water, and the temperature of the sizing starch is controlled between 60° C. and 80° C.

2. The method according to claim 1, characterized in that The step of diluting the sizing starch with water includes diluting the sizing starch with clean water at room temperature.

3. The method according to claim 2, characterized in that The step of diluting the sizing starch with water also includes: mixing and adjusting the sizing starch with normal temperature clean water and warm water to a concentration (solid content) of 12-20%.

4. The method according to claim 3, characterized in that The temperature of the warm water is 45±5°C.

5. The method according to claim 1, characterized in that During the transportation process, the sizing starch is diluted with water and the temperature of the sizing starch is controlled between 65°C and 75°C.

6. The method according to claim 1, characterized in that The method further comprises: adding citric acid during the conveying process so that the pH value of the sizing starch is 3.5±0.

5.

7. The method according to claim 6, characterized in that The added amount of citric acid is 0.4±0.1% of the absolute dry starch amount.

8. The method according to claim 1, characterized in that The sizing starch placed in the storage tank after gelatinization includes corn starch and cassava starch in a ratio ranging from 50%:50% to 100%:0%; the solid content of the sizing starch after gelatinization is 28-32% and the temperature is 95-98°C.

9. A sizing starch, characterized in that: The sizing starch is prepared by the method according to any one of claims 1 to 8.

10. A paper product, characterized in that: The paper product is prepared by using the sizing starch according to claim 9.

Images