Starch-based adhesive for paper adhesive tape as well as preparation method and application of starch-based adhesive

Abstract

The invention provides a starch-based adhesive for a paper adhesive tape as well as a preparation method and application of the starch-based adhesive, and relates to the technical field of adhesives. The starch-based adhesive for the paper adhesive tape comprises a main component and water, wherein the mass percentage of the main component is 5-10%; the main component is prepared from starch, polyvinyl alcohol and sodium carboxymethyl cellulose in a weight ratio of (25-75): (75-25): (3-7). The starch, the polyvinyl alcohol (PVA) and the carboxymethyl cellulose (CMC) form a blending system, and hydrogen bonds and chains among the three components are entangled to form a physical cross-linked network, so that the prepared starch-based adhesive simultaneously realizes dry-state dormancy (non-adhesion) and wet-state rapid activation (high initial adhesion).

Description

Technical Field

[0001] This invention provides a starch-based adhesive for paper tape, its preparation method, and its application, belonging to the field of adhesive technology. Background Technology

[0002] Traditional petroleum-based adhesives have many drawbacks in practical applications. For example, they use petroleum as a raw material, which is non-renewable, thus limiting their development to some extent. Furthermore, traditional petroleum-based adhesives are non-recyclable, not only impossible to recover but also highly polluting to the environment. Currently, most wet-type paper tapes use starch-based adhesives. Starch is abundant, inexpensive, biodegradable, and renewable. Adhesives made from starch are non-toxic and release no formaldehyde, making them promising for applications in the packaging industry.

[0003] Currently, starch adhesives face numerous challenges in the application of wet-type paper tapes: on the one hand, to ensure non-stickiness during dry storage, the adhesive layer needs to be "non-sticky in the dry state"; on the other hand, to ensure rapid adhesion after wetting, the adhesive layer needs to have "high initial tack in the wet state." Conventional starch adhesives often fail to achieve both, either being sticky in the dry state, leading to storage difficulties, or exhibiting slow tack activation or insufficient strength after wetting.

[0004] For example, Chinese patent CN201810863542.X discloses an environmentally friendly coating adhesive and its preparation method. This environmentally friendly coating adhesive is prepared from the following components: a starch emulsion with a mass concentration of 30%-60%, a plasticizer, a PVA solution with a mass concentration of 20-30%, a crosslinking agent, an initiator, and modified monomers. This technology involves many components, including starch, PVA, two modified monomers, a crosslinking agent, an initiator, and a plasticizer, making raw material management and quality control complex. Furthermore, the preparation process involves multi-step chemical synthesis (plasticization, crosslinking, graft copolymerization), requiring precise reaction conditions (temperature, dropping time, pH), resulting in high energy consumption, a long production cycle, and higher requirements for equipment and control systems.

[0005] Therefore, developing a starch-based adhesive that can simultaneously achieve dry dormancy (non-sticking) and wet rapid activation (high initial tack) is currently a hot research topic in the industry. Summary of the Invention

[0006] Based on this, the present invention provides a starch-based adhesive for paper tape, its preparation method, and its application. The present invention uses a blend system composed of starch, polyvinyl alcohol (PVA), and carboxymethyl cellulose (CMC). The hydrogen bonds and chain entanglements between the three components form a physical cross-linked network, thereby enabling the prepared starch-based adhesive to simultaneously achieve dry-state dormancy (non-adhesive) and wet-state rapid activation (high initial tack).

[0007] The present invention is specifically implemented using the following technical solutions: A starch-based adhesive for paper tape, comprising a main component and water, wherein the main component is 5-10% by mass; The main components consist of starch, polyvinyl alcohol, and sodium carboxymethyl cellulose in a weight ratio of 25-75:75-25:3-7.

[0008] Preferably, the starch is selected from at least one of cassava starch, waxy cassava starch, corn starch, potato starch, and high straight cassava starch.

[0009] Preferably, the polyvinyl alcohol is one of PVA1799, PVA1797, PVA2488 or PVA1788.

[0010] The present invention also provides a method for preparing the starch-based adhesive for paper tape, comprising the following steps: (1) Mix starch with water and heat and stir to gelatinize, so as to obtain a uniform starch paste; (2) Mix polyvinyl alcohol with water, heat and stir to dissolve, and obtain a polyvinyl alcohol solution; (3) Mix sodium carboxymethyl cellulose with water, heat and stir to dissolve, and obtain sodium carboxymethyl cellulose solution; (4) Add the polyvinyl alcohol solution to the starch paste, stir evenly at 70~80℃, and then add the sodium carboxymethyl cellulose solution, stirring to fully disperse the sodium carboxymethyl cellulose and form a thickening system; (5) Adjust the pH of the thickening system to neutral, add the remaining water, stir evenly, and cool to room temperature to obtain starch-based adhesive.

[0011] Preferably, the heating temperature in steps (1) to (3) is 90 to 95°C.

[0012] Preferably, the gelatinization time in step (1) is 20-30 minutes; the dissolution time in step (2) is 40-50 minutes; and the dissolution time in step (3) is 10-20 minutes.

[0013] The present invention further provides the application of the starch-based adhesive for paper tape, wherein the starch-based adhesive is coated on the surface of kraft paper and dried to form a wet-type paper tape.

[0014] Preferably, the coating amount of the starch-based adhesive is 10~30 g / m². 2 .

[0015] Compared with the prior art, the present invention has the following beneficial effects: The starch-based adhesive of this invention uses starch, PVA, and CMC—three renewable bio-based materials—as its core. It is biodegradable, significantly reducing dependence on petroleum resources. This invention achieves adhesion through physical cross-linking, is completely free of formaldehyde and other harmful chemicals, and meets the safety requirements of high-end packaging such as food and children's products. Paper tape made using the adhesive of this invention achieves a smart triggering characteristic of being "non-adhesive when dry, and adhesive upon contact with water." It is stable and easy to store when dry, and rapidly activates to produce high adhesion upon contact with water, making it particularly suitable for bonding cardboard.

[0016] The raw materials used in this invention are readily available, avoiding complex chemical reactions and expensive crosslinking agents. The production process is relatively simple, which is conducive to large-scale production and cost control. This invention has broad application prospects, especially suitable for packaging fields with high environmental protection and safety requirements, such as corrugated box sealing and express logistics, and has great market potential. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the starch-based adhesive preparation process of the present invention. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of this invention clearer, the preferred embodiments of this invention will be described in further detail below with reference to the examples. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without inventive effort are within the scope of protection of this invention.

[0019] A starch-based adhesive for paper tape, comprising a main component and water, wherein the main component comprises 8.6 g by mass in 100 g of the starch-based adhesive; The main component consists of 2 g of waxy tapioca starch, 6 g of PVA1788 and 0.6 g of sodium carboxymethyl cellulose.

[0020] The preparation method of the starch-based adhesive of the present invention comprises the following steps: (1) Mix the weighed starch with 20 g of water and heat to 90°C. Stir and gelatinize for 30 min to obtain a uniform starch paste. (2) Mix the weighed polyvinyl alcohol with 60 g of water and heat to 95°C and stir for 50 min to dissolve, to obtain a polyvinyl alcohol solution; (3) Mix the weighed sodium carboxymethyl cellulose with 10 g of water and heat to 95°C and stir to dissolve for 20 min to obtain sodium carboxymethyl cellulose solution; (4) Add the polyvinyl alcohol solution to the starch paste, stir evenly at 80°C, and then add the sodium carboxymethyl cellulose solution. Stir to fully disperse the sodium carboxymethyl cellulose and form a thickening system. (5) Adjust the pH of the thickening system to neutral, add the remaining water, stir evenly, and cool to room temperature to obtain a starch-based adhesive with a viscosity of 2886 mPa·s.

[0021] Example 2 A starch-based adhesive for paper tape, comprising a main component and water, wherein the main component comprises 8.6 g by mass in 100 g of starch-based adhesive; The main component consists of 2.7 g of waxy tapioca starch, 5.4 g of PVA1788 and 0.5 g of sodium carboxymethyl cellulose.

[0022] The preparation method of the starch-based adhesive of the present invention comprises the following steps: (1) Mix the weighed starch with 30 g of water and heat to 90°C. Stir and gelatinize for 30 min to obtain a uniform starch paste. (2) Mix the weighed polyvinyl alcohol with 50 g of water and heat to 95°C and stir for 50 min to dissolve, so as to obtain a polyvinyl alcohol solution; (3) Mix the weighed sodium carboxymethyl cellulose with 10 g of water and heat to 95°C and stir to dissolve for 20 min to obtain sodium carboxymethyl cellulose solution; (4) Add the polyvinyl alcohol solution to the starch paste, stir evenly at 80°C, and then add the sodium carboxymethyl cellulose solution. Stir to fully disperse the sodium carboxymethyl cellulose and form a thickening system. (5) Adjust the pH of the thickening system to neutral, add the remaining water, stir evenly, and cool to room temperature to obtain a starch-based adhesive with a viscosity of 2308 mPa·s.

[0023] Example 3 A starch-based adhesive for paper tape, comprising a main component and water, wherein the main component comprises 8.6 g by mass in 100 g of starch-based adhesive; The main component consists of 4.1 g of waxy tapioca starch, 4.1 g of PVA1788 and 0.4 g of sodium carboxymethyl cellulose.

[0024] The preparation method of the starch-based adhesive of the present invention comprises the following steps: (1) Mix the weighed starch with 40 g of water and heat to 90°C. Stir and gelatinize for 30 min to obtain a uniform starch paste. (2) Mix the weighed polyvinyl alcohol with 40 g of water and heat to 95°C and stir to dissolve for 50 min to obtain a polyvinyl alcohol solution; (3) Mix the weighed sodium carboxymethyl cellulose with 10 g of water and heat to 95°C and stir to dissolve for 20 min to obtain sodium carboxymethyl cellulose solution; (4) Add the polyvinyl alcohol solution to the starch paste, stir evenly at 80°C, and then add the sodium carboxymethyl cellulose solution. Stir to fully disperse the sodium carboxymethyl cellulose and form a thickening system. (5) Adjust the pH of the thickening system to neutral, add the remaining water, stir evenly, and cool to room temperature to obtain a starch-based adhesive with a viscosity of 2235 mPa·s.

[0025] Example 4 A starch-based adhesive for paper tape, comprising a main component and water, wherein the main component comprises 8.6 g by mass in 100 g of starch-based adhesive; The main component consists of 6 g of waxy tapioca starch, 2.3 g of PVA1788 and 0.3 g of sodium carboxymethyl cellulose.

[0026] The preparation method of the starch-based adhesive of the present invention comprises the following steps: (1) Mix the weighed starch with 60 g of water and heat to 90°C. Stir and gelatinize for 30 min to obtain a uniform starch paste. (2) Mix the weighed polyvinyl alcohol with 20 g of water and heat to 95°C and stir to dissolve for 50 min to obtain a polyvinyl alcohol solution; (3) Mix the weighed sodium carboxymethyl cellulose with 10 g of water and heat to 95°C and stir to dissolve for 20 min to obtain sodium carboxymethyl cellulose solution; (4) Add the polyvinyl alcohol solution to the starch paste, stir evenly at 80°C, and then add the sodium carboxymethyl cellulose solution. Stir to fully disperse the sodium carboxymethyl cellulose and form a thickening system. (5) Adjust the pH of the thickening system to neutral, add the remaining water, stir evenly, and cool to room temperature to obtain a starch-based adhesive with a viscosity of 2063 mPa·s.

[0027] Example 5 A starch-based adhesive for paper tape, comprising a main component and water, wherein the main component comprises 8.6 g by mass in 100 g of starch-based adhesive; The main component consists of 2.7 g of waxy tapioca starch, 5.4 g of PVA1797 and 0.5 g of sodium carboxymethyl cellulose.

[0028] The preparation method of the starch-based adhesive of the present invention comprises the following steps: (1) Mix the weighed starch with 30 g of water and heat to 90°C. Stir and gelatinize for 30 min to obtain a uniform starch paste. (2) Mix the weighed polyvinyl alcohol with 50 g of water and heat to 95°C and stir for 50 min to dissolve, so as to obtain a polyvinyl alcohol solution; (3) Mix the weighed sodium carboxymethyl cellulose with 10 g of water and heat to 95°C and stir to dissolve for 20 min to obtain sodium carboxymethyl cellulose solution; (4) Add the polyvinyl alcohol solution to the starch paste, stir evenly at 80°C, and then add the sodium carboxymethyl cellulose solution. Stir to fully disperse the sodium carboxymethyl cellulose and form a thickening system. (5) Adjust the pH of the thickening system to neutral, add the remaining water, stir evenly, and cool to room temperature to obtain a starch-based adhesive with a viscosity of 2063 mPa·s.

[0029] Example 6 A starch-based adhesive for paper tape, comprising a main component and water, wherein the main component comprises 8.6 g by mass in 100 g of starch-based adhesive; The main component consists of 2 g of waxy tapioca starch, 6 g of PVA1797 and 0.6 g of sodium carboxymethyl cellulose.

[0030] The preparation method of the starch-based adhesive of the present invention comprises the following steps: (1) Mix the weighed starch with 20 g of water and heat to 90°C. Stir and gelatinize for 30 min to obtain a uniform starch paste. (2) Mix the weighed polyvinyl alcohol with 60 g of water and heat to 95°C and stir for 50 min to dissolve, to obtain a polyvinyl alcohol solution; (3) Mix the weighed sodium carboxymethyl cellulose with 10 g of water and heat to 95°C and stir to dissolve for 20 min to obtain sodium carboxymethyl cellulose solution; (4) Add the polyvinyl alcohol solution to the starch paste, stir evenly at 80°C, and then add the sodium carboxymethyl cellulose solution. Stir to fully disperse the sodium carboxymethyl cellulose and form a thickening system. (5) Adjust the pH of the thickening system to neutral, add the remaining water, stir evenly, and cool to room temperature to obtain a starch-based adhesive with a viscosity of 2694 mPa·s.

[0031] Example 7 A starch-based adhesive for paper tape, comprising a main component and water, wherein the main component comprises 8.6 g by mass in 100 g of starch-based adhesive; The main component consists of 6 g of waxy tapioca starch, 2.3 g of PVA1797 and 0.3 g of sodium carboxymethyl cellulose.

[0032] The preparation method of the starch-based adhesive of the present invention comprises the following steps: (1) Mix the weighed starch with 60 g of water and heat to 90°C. Stir and gelatinize for 30 min to obtain a uniform starch paste. (2) Mix the weighed polyvinyl alcohol with 20 g of water and heat to 95°C and stir to dissolve for 50 min to obtain a polyvinyl alcohol solution; (3) Mix the weighed sodium carboxymethyl cellulose with 10 g of water and heat to 95°C and stir to dissolve for 20 min to obtain sodium carboxymethyl cellulose solution; (4) Add the polyvinyl alcohol solution to the starch paste, stir evenly at 80°C, and then add the sodium carboxymethyl cellulose solution. Stir to fully disperse the sodium carboxymethyl cellulose and form a thickening system. (5) Adjust the pH of the thickening system to neutral, add the remaining water, stir evenly, and cool to room temperature to obtain a starch-based adhesive with a viscosity of 2050 mPa·s.

[0033] Comparative Example 1 A starch-based adhesive for paper tape, comprising a main component and water, wherein the main component comprises 8.6 g by mass in 100 g of starch-based adhesive; The main component consists of 8.2 g of waxy cassava starch and 0.4 g of sodium carboxymethyl cellulose.

[0034] The preparation method of the starch-based adhesive of the present invention comprises the following steps: (1) Mix the weighed starch with 80 g of water and heat to 90°C. Stir and gelatinize for 30 min to obtain a uniform starch paste. (2) After mixing the weighed sodium carboxymethyl cellulose with 10 g of water, heat to 95°C and stir to dissolve for 20 min to obtain a sodium carboxymethyl cellulose solution; (3) Add the sodium carboxymethyl cellulose solution to the starch paste and stir to fully disperse the sodium carboxymethyl cellulose and form a thickening system; (4) Adjust the pH of the thickening system to neutral, add the remaining water, stir evenly, and cool to room temperature to obtain a starch-based adhesive with a viscosity of 3708 mPa·s.

[0035] Comparative Example 2 A starch-based adhesive for paper tape, comprising a main component and water, wherein the main component comprises 8.6 g by mass in 100 g of starch-based adhesive; The main component consists of 2.8 g of waxy tapioca starch and 5.8 g of PVA1788.

[0036] The preparation method of the starch-based adhesive of the present invention comprises the following steps: (1) Mix the weighed starch with 30 g of water and heat to 90°C. Stir and gelatinize for 30 min to obtain a uniform starch paste. (2) Mix the weighed polyvinyl alcohol with 60 g of water and heat to 95°C and stir for 50 min to dissolve, to obtain a polyvinyl alcohol solution; (3) Add the polyvinyl alcohol solution to the starch paste and stir evenly at 80°C to obtain starch-PVA adhesive; (4) Adjust the pH of the adhesive system to neutral, add the remaining water, stir evenly, and cool to room temperature to obtain a starch-based adhesive with a viscosity of 1274 mPa·s.

[0037] Comparative Example 3 A starch-based adhesive for paper tape, comprising a main component and water, wherein the main component comprises 8.6 g by mass in 100 g of starch-based adhesive; The main components consist of 2.7 g of corn starch, 5.4 g of PVA1788 and 0.5 g of sodium carboxymethyl cellulose.

[0038] The preparation method of the starch-based adhesive of the present invention comprises the following steps: (1) Mix the weighed starch with 35 g of water and heat to 90°C. Stir and gelatinize for 30 min to obtain a uniform starch paste. (2) Mix the weighed polyvinyl alcohol with 52 g of water and heat to 95°C and stir to dissolve for 50 min to obtain a polyvinyl alcohol solution; (3) Mix the weighed sodium carboxymethyl cellulose with 10 g of water and heat to 95°C and stir to dissolve for 20 min to obtain sodium carboxymethyl cellulose solution; (4) Add the polyvinyl alcohol solution to the starch paste, stir evenly at 80°C, and then add the sodium carboxymethyl cellulose solution. Stir to fully disperse the sodium carboxymethyl cellulose and form a thickening system. (5) Adjust the pH of the thickening system to neutral, add the remaining water, stir evenly, and cool to room temperature to obtain a starch-based adhesive with a viscosity of 3094 mPa·s.

[0039] Performance Experiment Paper tapes were prepared by coating kraft paper with the examples, comparative examples, and commercially available adhesives, wherein the adhesive coating was 20 g / m². 2 The resulting paper tape has a width of 48mm and a length of 60mm. Commercially available adhesive 1 is a 380A resin adhesive produced by Dongwan City Wanjiang Jianda Adhesive Products Co., Ltd.; commercially available adhesive 2 is an AP7001H starch-based adhesive produced by Yingchuang Technology (Guangdong) Co., Ltd.

[0040] The properties of the prepared paper tapes were tested separately and are shown in Table 1.

[0041] Table 1 The measurement of initial tack of the tape is based on GB / T 4852-2002; the measurement of peel strength of the tape is based on GB / T2790-1995.

[0042] A comparison of the data in Table 1 shows that: 1. Comparative Example 1 (without PVA) had an initial tack of only 5# and a peel strength of only 3.12 N / cm, which was much lower than that of the other examples, proving that PVA is the key component that provides initial tack and peel strength.

[0043] 2. Although the initial tack of Comparative Example 2 (without CMC) reached 8#, the peel strength decreased to 5.45 N / cm, and delamination occurred after 1 day of storage. This proves that CMC not only plays a thickening role, but more importantly, it acts as an "interfacial bridge" between starch and PVA, improving the stability and wet strength of the system.

[0044] 3. In Comparative Example 3, after replacing waxy cassava starch with ordinary corn starch, although it remained non-sticky in the dry state, the initial tack decreased to #4 and the peel strength decreased to 4.86 N / cm, and delamination occurred after 2 days of storage. This is because ordinary corn starch has a high amylose content, which easily leads to crystal retrogradation during drying, disrupting the uniformity of the ternary network structure formed with PVA and CMC. This results in a weakened synergistic effect between starch and PVA in the wet state, significantly reducing adhesive performance. This demonstrates that only by using waxy cassava starch with a high branched-chain content can a stable ternary network structure be formed, achieving a balance between non-stickiness in the dry state and high strength in the wet state.

[0045] 4. Examples 1, 2, and 6, when the ratio of PVA to starch was moderate (1:2 to 1:3) and the CMC content was 6-7%, simultaneously achieved high initial tack (9# or 10#) and high peel strength (>6.0 N / cm), and were completely non-sticky in the dry state. Comparative Examples 1-3, however, failed to achieve all three indicators simultaneously, demonstrating a synergistic effect among the three components, rather than a simple physical mixture.

[0046] The paper tape made from the adhesive of this invention has advantages such as high initial tack, high peel strength, no stickiness when dry, no formaldehyde production, and environmental friendliness. It meets the national requirements for sealing tape and has broad market prospects in the packaging field.

[0047] The embodiments described above are some, but not all, embodiments of the present invention. The detailed description of the embodiments of the present invention is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

Claims

1. A starch-based adhesive for paper tape, characterized in that, It includes a main component and water, wherein the main component has a mass percentage of 5-10%; The main components consist of starch, polyvinyl alcohol, and sodium carboxymethyl cellulose in a weight ratio of 25-75:75-25:3-7.

2. The starch-based adhesive for paper tape as described in claim 1, characterized in that, The starch is selected from at least one of cassava starch, waxy cassava starch, corn starch, potato starch, and high straight cassava starch.

3. The starch-based adhesive for paper tape as described in claim 1, characterized in that, The polyvinyl alcohol is one of PVA1799, PVA1797, PVA2488 or PVA1788.

4. The method for preparing the starch-based adhesive for paper tape as described in any one of claims 1 to 3, characterized in that, Includes the following steps: (1) Mix starch with water and heat and stir to gelatinize, so as to obtain a uniform starch paste; (2) Mix polyvinyl alcohol with water, heat and stir to dissolve, and obtain a polyvinyl alcohol solution; (3) Mix sodium carboxymethyl cellulose with water, heat and stir to dissolve, and obtain sodium carboxymethyl cellulose solution; (4) Add the polyvinyl alcohol solution to the starch paste, stir evenly at 70~80℃, and then add the sodium carboxymethyl cellulose solution, stirring to fully disperse the sodium carboxymethyl cellulose and form a thickening system; (5) Adjust the pH of the thickening system to neutral, add the remaining water, stir evenly, and cool to room temperature to obtain starch-based adhesive.

5. The preparation method according to claim 4, characterized in that, The heating temperature in steps (1) to (3) is 90 to 95°C.

6. The preparation method according to claim 4, characterized in that, Step (1) gelatinization time is 20-30 minutes; Step (2) dissolution time is 40-50 minutes; Step (3) dissolution time is 10-20 minutes.

7. The application of the starch-based adhesive for paper tape as described in any one of claims 1 to 3, characterized in that, The starch-based adhesive is coated onto the surface of kraft paper and dried to produce a wet-type paper tape.

8. The application as described in claim 7, characterized in that, The starch-based adhesive has a coating amount of 10~30 g / m². 2 .

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