A kind of PVA bio-glue based on yellow spur moth cocoon shell and preparation method thereof

Abstract

A PVA bio-glue based on the cocoon shell of the yellow thorn moth and a preparation method thereof, the preparation method comprising the following steps: (1) extracting the cocoon shell glue liquid: peeling the overwintering cocoon of the yellow thorn moth, crushing the whole cocoon shell after removing the pupa, adding distilled water, placing it in a high-pressure steam sterilizer, and boiling it at 120°C for 2.5 hours to fully dissolve the sericin in the inner layer of the cocoon shell to form a cocoon shell glue crude extract; (2) filtering and concentrating the crude extract: after the cocoon shell glue crude extract is cooled, filtering it with gauze to remove impurities to obtain a cocoon shell sericin liquid, then washing the impurities with 100°C hot water for 3 times, combining the washing liquid with the cocoon shell sericin liquid, boiling and concentrating it, and obtaining a cocoon shell dilute glue liquid; (3) mixing the cocoon shell dilute glue liquid with polyvinyl alcohol crystals, boiling it at 100°C for 10 minutes in a high-pressure steam sterilizer to fully dissolve the polyvinyl alcohol crystals, and obtaining the PVA bio-glue. The invention is environmentally friendly, has simple preparation steps, and the prepared PVA bio-glue has excellent performance.

Description

Technical Field

[0001] The invention belongs to the technical field of bio-based adhesives, and particularly relates to a PVA bio-glue based on the cocoon shell of the yellow spur moth and a preparation method thereof. Background Art

[0002] At present, adhesives on the market are mainly divided into two categories: synthetic adhesives and natural adhesives. Synthetic adhesives such as polyvinyl acetate glue and epoxy resin glue have high bonding strength and stable performance, but they require the use of a large amount of chemical raw materials and additives in the production process, which poses an environmental pollution risk, and some synthetic adhesives perform poorly in terms of biocompatibility and degradability. Natural adhesives such as starch glue and animal glue are widely available, low in cost, and environmentally friendly. Although bio-based adhesives have many advantages, existing bio-based adhesives still have many problems in performance, such as insufficient bonding strength and poor performance stability. The production process of some bio-based adhesives is complicated, and it is difficult to meet the diverse performance requirements of industrial production and daily life.

[0003] As people's environmental awareness continues to increase and the concept of sustainable development deepens, the demand for green, environmentally friendly and renewable adhesives is increasing, and the research and development of bio-based adhesives has gradually become a hot area. Therefore, there is an urgent need in the prior art for a bio-based adhesive with excellent performance, environmental friendliness and simple preparation process and a preparation method thereof. Summary of the invention

[0004] The first purpose of the present invention is to overcome the shortcomings of the prior art and provide a method for preparing PVA bio-glue based on the cocoon shell of the yellow spur moth which is environmentally friendly and has simple preparation steps.

[0005] The first object of the present invention is achieved by the following technical scheme: a method for preparing PVA bio-glue based on the cocoon shell of the yellow spur moth, comprising the following steps:

[0006] (1) Extraction of cocoon shell glue: The overwintering cocoons of the yellow thorn moth are peeled open, the whole cocoon shell after the pupae are removed is broken into pieces, distilled water is added, and the cocoon shell is placed in a high-pressure steam sterilizer and steamed at 120°C for 2.5 hours to fully dissolve the sericin in the inner layer of the cocoon shell to form a cocoon shell glue extract;

[0007] (2) Filtration and concentration of crude extract: After the crude extract of cocoon shell rubber is cooled, it is filtered with gauze to remove impurities to obtain cocoon shell sericin liquid, and then the impurities are washed with hot water at 100°C for 3 times. The washing liquid and the cocoon shell sericin liquid are combined and boiled and concentrated to obtain cocoon shell dilute rubber liquid; the weight ratio of the whole cocoon shell to the water in the cocoon shell dilute rubber liquid is 5-9:20;

[0008] (3) Mixing the cocoon shell dilute glue liquid with polyvinyl alcohol crystals, and steaming them in a high-pressure steam sterilizer at 100°C for 10 minutes to fully dissolve the polyvinyl alcohol crystals to obtain PVA bio-glue; in the PVA bio-glue, the weight ratio of polyvinyl alcohol crystals to water is 1-2:125.

[0009] In the step (3), in the PVA bio-glue, the weight ratio of polyvinyl alcohol crystals to water is 2:125.

[0010] The second purpose of the present invention is to overcome the shortcomings of the prior art and provide a PVA bio-glue based on the cocoon shell of the yellow spur moth with excellent performance, environmental friendliness and simple preparation steps.

[0011] The second object of the present invention is achieved through the following technical scheme: a PVA bio-glue based on the cocoon shell of the yellow spur moth, which is prepared by the above method for preparing the PVA bio-glue based on the cocoon shell of the yellow spur moth.

[0012] The beneficial effects of the present invention are: first, the bonding strength of the PVA bioglue based on the cocoon shell of the yellow spur moth of the present invention is significantly higher than that of the traditional PVA adhesive, and can meet the application scenarios requiring high-strength bonding. Secondly, the setting time of the PVA bioglue based on the cocoon shell of the yellow spur moth of the present invention is significantly shortened with the increase in the amount of PVA added, which improves the production efficiency and is suitable for the demand for rapid solidification. Furthermore, the viscosity of the PVA bioglue based on the cocoon shell of the yellow spur moth of the present invention is significantly increased with the increase in the amount of PVA added, and it has better fluidity and coating properties, and is convenient for construction and application. In addition, the PVA bioglue based on the cocoon shell of the yellow spur moth of the present invention also exhibits excellent mildew resistance, prolongs the service life of the adhesive, and reduces maintenance costs.

[0013] From the perspective of environmental protection, the present invention is made of renewable yellow thorn moth cocoon shells, and the production process does not produce harmful chemicals, which meets environmental protection requirements and is a green and sustainable adhesive. In terms of cost, the raw material source is wide, the cost is low, the production process is simple, the production cost is low, and it has high economic efficiency. By adjusting the amount of PVA added and the concentration of the cocoon shell dilute glue solution, different application requirements can be flexibly met, and it has a wide range of application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is the overwintering cocoon of the yellow thorn moth;

[0015] Figure 2 It is the layered structure of the overwintering cocoon of the yellow thorn moth;

[0016] Figure 3 The effect of cocoon shell dilute glue concentration and PVA addition amount on the viscosity of PVA bio-glue;

[0017] Figure 4 The effect of cocoon shell dilute glue concentration and PVA addition amount on the bonding force of PVA bio-glue;

[0018] Figure 5 The effect of cocoon shell dilute glue concentration and PVA addition amount on the coagulation of PVA bio-glue;

[0019] Figure 6 The effect of cocoon shell dilute glue concentration and PVA addition amount on the mildew resistance of PVA bio-glue;

[0020] Figure 7 It is the effect of the concentration of cocoon shell dilute glue solution on the appearance color of PVA bio-glue. DETAILED DESCRIPTION

[0021] The present invention is described in detail below in conjunction with the accompanying drawings.

[0022] See Figure 1 The yellow spur moth wintering cocoon is a cocoon shell formed by the yellow spur moth larvae during the winter. It is known as the hardest insect cocoon in the world. It has unique structure and biological characteristics and is an ideal raw material for preparing bio-glue. Its specific characteristics are as follows:

[0023] 1. The structure of the cocoon: Figure 2 As shown in the figure, the cocoon is divided into a distinct silk fiber inner layer 2 and a mineral outer layer 1. The mineral outer layer 1 is mainly composed of calcium oxalate, and the silk fiber inner layer 2 is mainly composed of sericin and fibroin. Among them, sericin is a natural protein with good adhesion and biocompatibility. The sericin content of the yellow spur moth cocoon shell is relatively high, usually 25%-30%.

[0024] 2. Biological characteristics: The cocoon of the yellow thorn moth is a biological resource that is easy to obtain in the wild and can be cultivated indoors. It has a wide range of sources. Using the cocoon of the yellow thorn moth to make PVA bio-glue can reduce the dependence of adhesive preparation on non-renewable chemical raw materials, which meets the requirements of sustainable development.

[0025] 3. Environmentally friendly: The extraction and processing process of the yellow thorn moth cocoon shell is simple and has little impact on the environment. Compared with synthetic adhesives, its production process does not produce harmful chemicals and is more environmentally friendly.

[0026] 4. Versatility: The PVA bio-glue prepared from sericin extracted from the cocoon shell of the yellow thorn moth and polyvinyl alcohol (PVA) has anti-mildew and antibacterial functions, meeting the needs of different application scenarios. Example

[0027] 1. Materials and Methods

[0028] 1. Preparation of dilute glue solution from cocoon shells of yellow moth

[0029] (1) Crude extraction of cocoon shell glue: The inner layer of silk fibers of the overwintering cocoons of the yellow thorn moth is the source of glue extraction. The inner layer of silk fibers is tightly attached to the inner side of the mineral outer layer. After the overwintering cocoons of the yellow thorn moth are peeled open, the pupae are removed and 125 g, 250 g and 450 g of the whole cocoon shell are weighed and crushed. Then 2.5 L of distilled water are added to each of the pieces. The pieces are placed in a high-pressure steam sterilizer and steamed at 120 °C for 2.5 h to fully dissolve the sericin in the inner layer of the cocoon shell to form a crude extract of cocoon shell glue.

[0030] (2) Filtration and concentration of crude extract: After the cocoon glue crude extract was cooled, it was filtered through 6 layers of gauze to remove impurities to obtain cocoon shell sericin liquid. The impurities were then washed with 100°C hot water for 3 times. The washing liquid was combined with the cocoon shell sericin liquid and boiled until the volume of the liquid was 1L (1000g). This is the cocoon shell dilute glue liquid. The greater the weight of the cocoon shell, the greater the concentration of the dilute glue liquid. The cocoon shell dilute glue liquids obtained based on the weight of 125 g, 250 g, and 450 g of the whole cocoon shell were numbered Ⅰ, Ⅱ, and Ⅲ, respectively.

[0031] 2. Sample Preparation

[0032] The cocoon shell dilute glue liquid was mixed with polyvinyl alcohol (PVA) crystals, and then boiled at 100 °C for 10 min in a high-pressure steam sterilizer to fully dissolve the PVA crystals to prepare PVA bio-glue. The specific preparation ratio of cocoon shell dilute glue liquid and PVA is shown in Table 1. Three different concentrations of cocoon shell dilute glue liquid were used as control group 1, and different amounts of PVA crystals added with distilled water were mixed as control group 2. Different weights of PVA crystals were weighed and added to cocoon shell dilute glue liquids Ⅰ, Ⅱ and Ⅲ, respectively, to prepare PVA bio-glue, as test group Ⅰ, test group Ⅱ and test group Ⅲ, with a total of 19 test glue samples.

[0033]

[0034] 3. Sample performance measurement

[0035] (1) Viscosity measurement

[0036] The viscosity of different glue samples was measured using NDJ-5S rotational viscometer at room temperature (25±1℃). The viscometer rotor No. 1 was selected, and the speed range was (0.1~60) r / min. The viscosity data of each sample was recorded for 20s, 40s and 60s, and the average value was calculated.

[0037] (2) Adhesion strength measurement

[0038] Select two colors of hard cardboard, yellow and black, with a thickness of about 0.3 mm, and cut them into multiple pieces of 2 cm × 10 cm. Add 1 mL of PVA bioglue to one end of the yellow cardboard and place it in a 2 cm × 2 cm square area (4 cm 2), spread evenly and stick it to one end of the black cardboard to ensure close contact between the two. Place it at room temperature (25±1℃) for 24 hours, then remove the two colors of cardboard, observe and record the bonding effect, and measure the area of ​​the black paper part stuck on the yellow cardboard and the yellow paper part of the yellow cardboard with a nine-square paper (1 mm×1 mm) to compare the bonding degree (adhesion force) of different samples. Repeat 3 times for each sample.

[0039] Adhesion (%) = actual measured area / 4×100%;

[0040] (3) Coagulation test

[0041] Take 20 mL of the sample and pour it into a culture dish to ensure that the glue is evenly distributed. Place it in a constant temperature box and keep the temperature constant at 25±1℃. Use a Barcol hardness tester to test the colloid hardness every 2 hours. When the colloid hardness value remains unchanged for 2 consecutive times, it is completely solidified, and the final solidification time is recorded. Repeat 3 times for each sample.

[0042] (4) Determination of mildew resistance

[0043] Preparation of bio-gel culture medium: Add agar to PVA bio-gel to make agar gel solution, and ensure that the agar gel solution can solidify quickly when poured into the culture dish. The thickness of each culture medium is 5 mm. PDA culture medium is used as a control. Each culture medium is repeated 3 times. All culture media are uniformly exposed to the indoor environment, maintaining a temperature of 25±1℃ and a humidity of 70%. After 48 hours, the number of mold colonies on the surface of the culture medium is observed and counted under a stereomicroscope.

[0044] Antibacterial rate (%) = (n 0 -n i ) / n 0 ×100%;

[0045] Among them, n 0 and n i These are the colony counts on the surfaces of PDA medium and agar gel medium, respectively.

[0046] 2. Results and Analysis

[0047] 1. Sample viscosity results and analysis

[0048] Combining Table 2 and Figure 3 It can be seen that when the amount of PVA added was 4g and 8g respectively, as the concentration of cocoon shell dilute glue increased, the viscosity of PVA bio-glue gradually increased significantly ( P<0.05). When the amount of PVA added was 12g and 16g, respectively, the viscosity of the PVA bio-glue prepared from cocoon shell dilute glue solution II was significantly higher than that of the PVA bio-glue prepared from cocoon shell dilute glue solution I and cocoon shell dilute glue solution III, and the viscosity of the PVA bio-glue prepared from cocoon shell dilute glue solution II when the amount of PVA added was 16g was the largest, which was 794.90 mPa·s. At the same cocoon shell dilute glue concentration, with the increase of PVA addition, the viscosity value increased significantly ( P <0.05), especially when the cocoon shell dilute glue II was combined with PVA at an addition amount of 12g and 16g, the viscosity of the resulting PVA bio-glue increased most significantly, which were 6.34 times and 12.38 times of the viscosity of the PVA bio-glue prepared when the PVA addition amount was 8g, respectively, indicating that at this addition amount, the cocoon shell dilute glue and PVA have good compatibility.

[0049] like Figure 3 As shown, the viscosity value of control group 1 (cocoon shell dilute glue solution alone) was the lowest, while the viscosity values ​​of control group 2 (PVA crystals and distilled water) were lower than the viscosity values ​​of PVA bio-glue prepared with equal amounts of PVA crystals and cocoon shell dilute glue solution, which indicates that there is a synergistic effect between PVA crystals and cocoon shell dilute glue solution, which can effectively improve the viscosity performance of PVA bio-glue.

[0050]

[0051] 2. Sample adhesion results and analysis

[0052] Combining Table 3 and Figure 4 It can be seen that the cocoon shell dilute glue concentration and PVA addition amount have a significant effect on the bonding strength of the prepared PVA bio-glue. When the PVA addition amount is 8g, 12g and 16g respectively, at the same PVA addition amount, the greater the cocoon shell dilute glue concentration, the greater the bonding strength, and the bonding strength of the PVA bio-glue prepared from the cocoon shell dilute glue III is significantly the highest ( P <0.05); when the amount of PVA added was 16g, the bonding strength of all PVA bio-glue exceeded 90%, and the bonding strength of PVA bio-glue prepared from cocoon shell dilute glue solution III was the highest, reaching 98.59%, showing the best bonding performance; while when the amount of PVA added was 4g, the PVA bio-glue prepared from cocoon shell dilute glue solutions of different concentrations had no bonding strength. The bonding strength of PVA bio-glue prepared from cocoon shell dilute glue solution of the same concentration increased significantly with the increase of PVA addition amount ( P <0.05). This shows that the addition of PVA significantly improves the bonding strength of PVA bio-glue, and the increase in the bonding strength of PVA bio-glue increases with the increase in the amount of PVA added. When the amount of PVA added was 8g, 12g and 16g, the PVA bio-glue prepared from cocoon shell dilute glue solution III showed the highest bonding strength, indicating that cocoon shell dilute glue solution III has the best compatibility with PVA.

[0053] The bonding force of control group 1 was 0, and the bonding force of control group 2 was lower than the bonding force of PVA bio-glue prepared by equal amounts of PVA crystals and cocoon shell dilute glue in test groups I, II, and III. This indicates that there is a synergistic effect between PVA crystals and cocoon shell dilute glue, which can greatly enhance the bonding force.

[0054]

[0055] 3. Sample coagulation results and analysis

[0056] Combining Table 4 and Figure 5 It can be seen that the concentration of cocoon shell dilute glue and the amount of PVA added have an effect on the coagulation time of the prepared PVA bio-glue. When the PVA added amount was 8g, 12g and 16g respectively, the greater the concentration of the cocoon shell dilute glue, the shorter the coagulation time of the prepared PVA bio-glue, and the coagulation time of the PVA bio-glue prepared by cocoon shell dilute glue III was the shortest, the coagulation time of the PVA bio-glue prepared by cocoon shell dilute glue I was the longest, and the coagulation time of the PVA bio-glue prepared by cocoon shell dilute glue II was between the two. When the PVA added amount was 16g, the coagulation time of the PVA bio-glue prepared by cocoon shell dilute glue III was the shortest, which was 22 h. When the PVA added amount was 4g, there was no difference in the coagulation time of the PVA bio-glue prepared by different cocoon shell dilute glue concentrations. When the PVA added amounts were 8g, 12g and 16g respectively, the coagulation time of the PVA bio-glue prepared by the same concentration of cocoon shell dilute glue was significantly shortened with the increase of PVA added amount ( P <0.05). This indicates that the addition of PVA significantly improves the coagulation properties of bioglue.

[0057] The control group 1 could not be coagulated. Figure 5 As shown, the coagulation time of the control group 2 was higher than or equal to the coagulation time of the PVA bioglue prepared by the same amount of PVA crystals and cocoon shell dilute glue solution, and the higher the amount of PVA crystals added, the shorter the required coagulation time.

[0058]

[0059] 4. Sample antifungal results and analysis

[0060] Combining Table 5 and Figure 6It can be seen that the concentration of cocoon shell dilute glue and the amount of PVA added have an effect on the antibacterial rate of the prepared PVA bio-glue. Under the same amount of PVA added, the antibacterial rate of PVA bio-glue prepared from cocoon shell dilute glue solution Ⅰ is the highest, and the antibacterial rate of PVA bio-glue prepared from cocoon shell dilute glue solution Ⅲ is the lowest. When the amount of PVA added is 4g, the antibacterial rate of PVA bio-glue prepared from cocoon shell dilute glue solution Ⅰ reaches the highest, which is 91.65%. Although the antibacterial rate of PVA bio-glue prepared from cocoon shell dilute glue solution Ⅲ is the lowest, it still reaches 72.23%. Under other PVA addition amounts, the antibacterial rate of PVA bio-glue prepared from cocoon shell dilute glue solution Ⅲ is the lowest, but it is also higher than 66.67%.

[0061] During the observation period of the mildew resistance experiment, due to the high water content of the diluted glue in the control group 1, no mildew occurred. As time went by, the water content of the glue continued to evaporate. From the 8th day, mold colonies began to appear sporadically in the culture medium and gradually increased. However, after the water completely evaporated, the colonies also shrank and died. No mildew infection was found in the control group 2.

[0062]

[0063] 5. Appearance and color of cocoon shell-based PVA bioadhesive

[0064] Figure 7 The color changes of PVA bio-glue prepared from pure PVA and different cocoon shell dilute glue solutions Ⅰ (whole cocoon shell weight 125g), Ⅱ (whole cocoon shell weight 250g), and Ⅲ (whole cocoon shell weight 450g). PVA glue itself is colorless, but with the increase of cocoon shell dilute glue concentration, the color of PVA bio-glue gradually deepens, which is related to the content of pigment components in the cocoon shell dilute glue. The color change of cocoon shell-based PVA bio-glue has guiding significance for its use in certain specific application scenarios, especially in the packaging or decoration fields that have color requirements.

[0065] 6. Conclusion

[0066] From the above test results, it can be seen that the bonding force of PVA bio-glue is significantly higher than that of pure PVA. Under the same cocoon shell dilute glue concentration, with the increase of PVA addition, the bonding force of the prepared PVA bio-glue gradually increases; when the PVA addition amount is 8g, 12g and 16g respectively, under the same PVA addition amount, the PVA bio-glue prepared from cocoon shell dilute glue III has the highest bonding force. The coagulation time of PVA bio-glue is significantly shortened with the increase of PVA addition. Under the same cocoon shell dilute glue concentration, the coagulation time of PVA bio-glue is significantly shortened with the increase of PVA addition, indicating that the addition of PVA significantly improves the coagulation performance of bio-glue. The viscosity of PVA bio-glue increases significantly with the increase of PVA addition; when the PVA addition amount is 12g and 16g respectively, under the same PVA addition amount, the PVA bio-glue prepared from cocoon shell dilute glue II shows the highest viscosity, indicating that it has good compatibility with PVA. PVA bio-glue showed good anti-mildew performance. When the amount of PVA added was 4g, the antibacterial rate of PVA bio-glue prepared from cocoon shell dilute glue solution I was as high as 91.65%; at the same amount of PVA added, the PVA bio-glue prepared from cocoon shell dilute glue solution I showed the highest antibacterial rate. The color of the bio-glue gradually deepened with the increase of the concentration of cocoon shell dilute glue solution. The performance indicators of PVA bio-glue based on yellow spur moth cocoon shell and other colloids are shown in Table 6.

[0067]

[0068] As shown in Table 6, compared with other biological glues, the advantages of the present invention are manifested in the following aspects: 1. The present invention uses the cocoon shell of the yellow spur moth as raw material, which can be obtained by collecting in the wild or by artificial cultivation indoors, and has a high protein content, providing excellent bonding performance. 2. The preparation method of the present invention is simple and efficient, involving only boiling, filtering and concentration steps, with low production cost, and is suitable for large-scale industrial production. 3. The present invention has excellent performance in bonding strength, coagulation performance, viscosity and mildew resistance. By adjusting the amount of PVA added and the concentration of the cocoon shell dilute glue solution, different application requirements can be flexibly met, which provides more possibilities for the wide application of biological glue in the fields of packaging, decoration and construction. 4. The production process of the present invention does not produce harmful chemicals and is more environmentally friendly than traditional synthetic adhesives.

[0069] Finally, it should be noted that the above content is only used to illustrate the technical solution of the present invention, rather than to limit the scope of protection of the present invention. Simple modifications or equivalent substitutions of the technical solution of the present invention by ordinary technicians in this field do not deviate from the essence and scope of the technical solution of the present invention.

Claims

1. A method for preparing PVA bio-glue based on the cocoon shell of the yellow spur moth, characterized in that The steps include: (1) Extraction of cocoon shell glue: peel off the overwintering cocoons of the yellow thorn moth, crush the whole cocoon shell after removing the pupae, add distilled water, place it in a high-pressure steam sterilizer, and cook it at 120°C for 2.5 hours to fully dissolve the sericin in the inner layer of the cocoon shell to form a cocoon shell glue crude extract; (2) Filtration and concentration of the crude extract: After the crude extract of cocoon shell rubber is cooled, it is filtered with gauze to remove impurities to obtain cocoon shell sericin liquid, and then the impurities are washed with hot water at 100° C. for 3 times. The washing liquid and the cocoon shell sericin liquid are combined and boiled and concentrated to obtain a cocoon shell dilute rubber liquid; the weight ratio of the whole cocoon shell to the water in the cocoon shell dilute rubber liquid is 5-9:20; (3) The cocoon shell dilute glue solution was mixed with polyvinyl alcohol crystals, and the mixture was steamed in a high-pressure steam sterilizer at 100° C. for 10 min to fully dissolve the polyvinyl alcohol crystals, thereby obtaining PVA bio-glue; in the PVA bio-glue, the weight ratio of polyvinyl alcohol crystals to water was 2:

125.

2. A PVA bioadhesive based on the cocoon shell of the yellow spur moth, characterized in that: The PVA bio-glue is prepared by the preparation method of the PVA bio-glue based on the cocoon shell of the yellow spur moth as described in claim 1.

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