A low-temperature viscosity-reducing plasticizer and its preparation method

Abstract

This invention relates to a low-temperature viscosity-reducing plasticizer and its preparation method, belonging to the field of plasticizer processing technology. The raw materials for preparing the plasticizer include 6-12 parts n-butanol, 5-10 parts citric acid, 23-26 parts modified lignin, 1-3 parts vegetable oil, 20-35 parts plant secretions, and 35-45 parts plant extracts. The plasticizer utilizes plant secretions, which contain a large amount of high-molecular-weight substances and possess excellent flexibility and adhesion. As a plasticizer base material, it is well-compatible with the polymer matrix. The addition of plant extracts ensures good compatibility with the lignin and citric acid system, forming a uniform and stable plasticizing system that is less prone to precipitation. Modified lignin is used as the core framework. The n-butanol and citric acid undergo an esterification reaction to generate a lignin-citric acid ester network structure. This structure is not only flexible itself but also forms strong hydrogen bonds and van der Waals forces with the polymer molecular chains.

Description

Technical Field

[0001] This invention belongs to the field of plasticizer processing technology, specifically relating to a low-temperature viscosity-reducing plasticizer and its preparation method. Background Technology

[0002] Plasticizers are polymer additives widely used in industrial production. Any substance added to polymer materials that increases the plasticity of the polymer is called a plasticizer. The use of plasticizers can improve the performance of polymer materials, reduce production costs, and increase production efficiency.

[0003] However, plasticizers are not bonded to plastic polymer molecules through strong chemical bonds, but rather through physical mixing. Over time, they gradually leach, volatilize, or precipitate from plastic products. Once these plasticizers are released from the products, they can cause irreversible and harmful effects on the appearance and physical properties of the plastics. They can also enter the soil, water, and air, where they are difficult to degrade naturally and can persist and accumulate in the environment for a long time. Summary of the Invention

[0004] The purpose of this invention is to provide a low-temperature viscosity-reducing plasticizer and its preparation method in order to solve the above-mentioned problems.

[0005] The present invention achieves the above objectives through the following technical solutions:

[0006] This invention provides a low-temperature viscosity-reducing plasticizer. By weight, the raw materials for preparing the plasticizer include 6-12 parts n-butanol, 5-10 parts citric acid, 23-26 parts modified lignin, 1-3 parts vegetable oil, 20-35 parts plant secretions, and 35-45 parts plant extracts.

[0007] As a further optimization of the present invention, the preparation process of plant secretions is as follows: (i) wash the vines, creeping grass, jade tree, dandelion and Euphorbia helioscopia to remove the surface soil, and air dry the surface moisture in a ventilated environment with 85% humidity; (ii) straighten and tie the vines, creeping grass, jade tree, dandelion and Euphorbia helioscopia after air drying the surface moisture; (iii) cut off the front end, tilt the cut end downward so that the secretion drips, and after 5 minutes, make a horizontal cut again 5 cm above the cut end, repeating this until the whole bundle is cut off, and collect the secretion.

[0008] As a further optimization of the present invention, the preparation process of the plant extract is as follows: (i) Collect the cut sections of *Gnaphalium affine*, *Gnaphalium affine*, *Gnaphalium affine*, *Taraxacum officinale*, and *Euphorbia helioscopia*, and pound them for 20-25 minutes using a pounder with an impact energy of 2.0 kJ and a pounding frequency of 40 bpm to pound the plant stems and leaves, and collect the solid-liquid mixture; (ii) Wash the solid-liquid mixture repeatedly with 65°C hot water for 30 minutes, sieve out the solids through a 60-mesh sieve, add 15% sodium carboxymethyl cellulose by weight to the liquid, stir at 65 r / min for 60-80 minutes to obtain a pre-prepared solution; (iii) Add 32% by weight of 90% ethanol to the pre-prepared solution, let it stand for 45 minutes to precipitate, remove the supernatant, and obtain the plant extract.

[0009] As a further optimization of the present invention, the mass ratio of *Gnaphalium affine*, *Gnaphalium affine*, *Gnaphalium affine*, dandelion, and *Euphorbia helioscopia* is 1:1:(1-3):1.2:0.2.

[0010] As a further optimization of the present invention, the vegetable oil includes: coconut oil and perilla seed oil in equal proportions.

[0011] As a further optimization of the present invention, the modified lignin is obtained by oxidative depolymerization of lignin followed by oxidase degradation and modification.

[0012] As a further optimization of the present invention, the specific process of lignin oxidation and depolymerization is as follows: lignin is immersed in hydrogen peroxide at 60°C and stirred at 80 r / min for 30 min. Oxygen is introduced during stirring, and the airflow speed is set at 2 m / s to oxidize and depolymerize the lignin. The specific process of lignin oxidase degradation and modification is as follows: the oxidized and depolymerized lignin is mixed with oxidase and cultured in a ventilated environment at 25°C and 95% humidity for 6 days. After that, modified lignin is obtained.

[0013] As a further optimization of the present invention, the mass ratio of lignin to oxidase is 1:0.1.

[0014] This invention also provides a method for preparing a low-temperature viscosity-reducing plasticizer, comprising the following steps:

[0015] S1. Add n-butanol to the reactor; under stirring at 45 r / min, slowly add modified lignin, slowly raise the temperature to 60-70℃, and continue stirring for 1-2 hours to allow the lignin to fully swell and disperse, forming a uniform and viscous slurry; then add citric acid and stir until it dissolves.

[0016] S2, slowly raise the temperature to 90-110℃, and reflux at this temperature for 3-6 hours;

[0017] S3. Cool the slurry system to 50-60℃, and add vegetable oil, plant secretion liquid and plant extract in sequence while stirring at 45r / min. Keep stirring at this temperature for 60-80h to obtain the plasticizer.

[0018] The beneficial effects of this invention are as follows: This invention utilizes plant secretions in the plasticizer. Plant secretions contain a large amount of high molecular weight substances and possess excellent flexibility and adhesion. As a plasticizer base material, it is well-compatible with the polymer matrix. The addition of plant extracts ensures good compatibility with the lignin and citric acid system, forming a uniform and stable plasticizing system that is less prone to precipitation. Modified lignin is used as the core framework, and n-butanol undergoes an esterification reaction with citric acid to generate a lignin-citric acid ester network structure. This structure is not only flexible but also forms strong hydrogen bonds and van der Waals forces with the polymer molecular chains, thereby greatly reducing the migration and volatilization loss of the plasticizer and achieving long-lasting plasticization. Detailed Implementation

[0019] The present application will now be described in further detail. It should be noted that the following specific embodiments are only used to further illustrate the present application and should not be construed as limiting the scope of protection of the present application. Those skilled in the art can make some non-essential improvements and adjustments to the present application based on the above application content.

[0020] Unless otherwise specified, all methods used in this invention are conventional methods known to those skilled in the art, and all reagents and materials used are commercially available products.

[0021] Example 1

[0022] The preparation process of plant secretions is as follows: (i) Wash the vines, creeping grass, jade tree, dandelion and Euphorbia helioscopia to remove the surface soil, and air dry the surface moisture in a ventilated environment with 85% humidity; (ii) Straighten and tie the dried vines, creeping grass, jade tree, dandelion and Euphorbia helioscopia; (iii) Cut off the front end, tilt the cut end downward so that the secretion drips, and after 5 minutes, make a horizontal cut again 5 cm above the cut end. Repeat this process until the whole bundle is cut off and collect the secretion.

[0023] The preparation process of the plant extract is as follows: (I) Collect the cut sections of *Gnaphalium affine*, *Gnaphalium affine*, *Gnaphalium affine*, dandelion, and *Euphorbia helioscopia*, and pound them for 20 minutes using a pounder with an impact energy of 2.0 kJ and a pounding frequency of 40 bpm. Pound the plant stems and leaves and collect the solid-liquid mixture; (II) Wash the solid-liquid mixture repeatedly with 65℃ hot water for 30 minutes, sieve out the solids through a 60-mesh sieve, add 15% sodium carboxymethyl cellulose by weight into the liquid, stir at 65 r / min for 60 minutes to obtain a pre-prepared solution; (III) Add 32% 90% ethanol by weight to the pre-prepared solution, let it stand for 45 minutes to precipitate, remove the supernatant, and obtain the plant extract;

[0024] The mass ratio of *Gnaphalium affine*, *Gnaphalium affine*, *Gnaphalium affine*, dandelion, and *Euphorbia helioscopia* is 1:1:1:1.2:0.2;

[0025] The vegetable oils include equal proportions of coconut oil and perilla seed oil;

[0026] Modified lignin is obtained by oxidative depolymerization of lignin followed by oxidase degradation and modification. The specific process of lignin oxidative depolymerization is as follows: lignin is immersed in hydrogen peroxide at 60℃ and stirred at 80r / min for 30min. Oxygen is introduced during stirring at a flow rate of 2m / s to oxidize and depolymerize the lignin. The specific process of lignin oxidase degradation and modification is as follows: the oxidized and depolymerized lignin is mixed with oxidase and cultured under ventilation at 25℃ and 95% humidity for 6 days. After that, modified lignin is obtained.

[0027] Add 6 parts of n-butanol to the reactor; while stirring at 45 r / min, slowly add 23 parts of modified lignin. Slowly raise the temperature to 60℃ and continue stirring for 1 hour to allow the lignin to fully swell and disperse, forming a homogeneous and viscous slurry; then add 5 parts of citric acid and stir until dissolved.

[0028] The temperature was slowly raised to 90°C, and the reflux reaction was carried out at this temperature for 3 hours.

[0029] The slurry system was cooled to 50°C, and 1 part of vegetable oil, 20 parts of plant secretion liquid and 35 parts of plant extract were added sequentially while stirring at 45 r / min. The mixture was stirred at this temperature for 60 h to obtain the plasticizer.

[0030] Example 2

[0031] The preparation process of plant secretions is as follows: (i) Wash the vines, creeping grass, jade tree, dandelion and Euphorbia helioscopia to remove the surface soil, and air dry the surface moisture in a ventilated environment with 85% humidity; (ii) Straighten and tie the dried vines, creeping grass, jade tree, dandelion and Euphorbia helioscopia; (iii) Cut off the front end, tilt the cut end downward so that the secretion drips, and after 5 minutes, make a horizontal cut again 5 cm above the cut end. Repeat this process until the whole bundle is cut off and collect the secretion.

[0032] The preparation process of the plant extract is as follows: (I) Collect the cut sections of *Gnaphalium affine*, *Gnaphalium affine*, *Gnaphalium affine*, dandelion, and *Euphorbia helioscopia*, and pound them for 23 minutes using a pounder with an impact energy of 2.0 kJ and a pounding frequency of 40 bpm. Pound the plant stems and leaves and collect the solid-liquid mixture; (II) Wash the solid-liquid mixture repeatedly with 65℃ hot water for 30 minutes, sieve out the solids through a 60-mesh sieve, add 15% sodium carboxymethyl cellulose by weight to the liquid, and stir at 65 r / min for 70 minutes to obtain a pre-prepared solution; (III) Add 32% 90% ethanol by weight to the pre-prepared solution, let it stand for 45 minutes to precipitate, remove the supernatant, and obtain the plant extract;

[0033] The mass ratio of *Gnaphalium affine*, *Gnaphalium affine*, *Gnaphalium affine*, dandelion, and *Euphorbia helioscopia* is 1:1:2:1.2:0.2.

[0034] The vegetable oils include equal proportions of coconut oil and perilla seed oil;

[0035] Modified lignin is obtained by oxidative depolymerization of lignin followed by oxidase degradation and modification. The specific process of lignin oxidative depolymerization is as follows: lignin is immersed in hydrogen peroxide at 60℃ and stirred at 80r / min for 30min. Oxygen is introduced during stirring at a flow rate of 2m / s to oxidize and depolymerize the lignin. The specific process of lignin oxidase degradation and modification is as follows: the oxidized and depolymerized lignin is mixed with oxidase and cultured under ventilation at 25℃ and 95% humidity for 6 days. After that, modified lignin is obtained.

[0036] Add 8 parts of n-butanol to the reactor; while stirring at 45 r / min, slowly add 25 parts of modified lignin. Slowly raise the temperature to 65℃ and continue stirring for 1.5 h to allow the lignin to fully swell and disperse, forming a uniform and viscous slurry; then add 7 parts of citric acid and stir until dissolved.

[0037] The temperature was slowly raised to 100°C, and the reflux reaction was carried out at this temperature for 4 hours.

[0038] The slurry system was cooled to 55°C, and 2 parts of vegetable oil, 28 parts of plant secretion liquid and 42 parts of plant extract were added sequentially while stirring at 45 r / min. The mixture was stirred at this temperature for 70 h to obtain the plasticizer.

[0039] Example 3

[0040] The preparation process of plant secretions is as follows: (i) Wash the vines, creeping grass, jade tree, dandelion and Euphorbia helioscopia to remove the surface soil, and air dry the surface moisture in a ventilated environment with 85% humidity; (ii) Straighten and tie the dried vines, creeping grass, jade tree, dandelion and Euphorbia helioscopia; (iii) Cut off the front end, tilt the cut end downward so that the secretion drips, and after 5 minutes, make a horizontal cut again 5 cm above the cut end. Repeat this process until the whole bundle is cut off and collect the secretion.

[0041] The preparation process of the plant extract is as follows: (I) Collect the cut sections of *Gnaphalium affine*, *Gnaphalium affine*, *Gnaphalium affine*, dandelion, and *Euphorbia helioscopia*, and pound them for 25 minutes using a pounder with an impact energy of 2.0 kJ and a pounding frequency of 40 bpm. Pound the plant stems and leaves and collect the solid-liquid mixture; (II) Wash the solid-liquid mixture repeatedly with 65℃ hot water for 30 minutes, sieve out the solids through a 60-mesh sieve, add 15% sodium carboxymethyl cellulose by weight to the liquid, and stir at 65 r / min for 80 minutes to obtain a pre-prepared solution; (III) Add 32% 90% ethanol by weight to the pre-prepared solution, let it stand for 45 minutes to precipitate, remove the supernatant, and obtain the plant extract;

[0042] The mass ratio of *Gnaphalium affine*, *Gnaphalium affine*, *Gnaphalium affine*, dandelion, and *Euphorbia helioscopia* is 1:1:3:1.2:0.2.

[0043] The vegetable oils include equal proportions of coconut oil and perilla seed oil;

[0044] Modified lignin is obtained by oxidative depolymerization of lignin followed by oxidase degradation and modification. The specific process of lignin oxidative depolymerization is as follows: lignin is immersed in hydrogen peroxide at 60℃ and stirred at 80r / min for 30min. Oxygen is introduced during stirring at a flow rate of 2m / s to oxidize and depolymerize the lignin. The specific process of lignin oxidase degradation and modification is as follows: the oxidized and depolymerized lignin is mixed with oxidase and cultured under ventilation at 25℃ and 95% humidity for 6 days. After that, modified lignin is obtained.

[0045] Add 12 parts of n-butanol to the reactor; while stirring at 45 r / min, slowly add 26 parts of modified lignin. Slowly raise the temperature to 70℃ and continue stirring for 2 hours to allow the lignin to fully swell and disperse, forming a homogeneous and viscous slurry; then add 10 parts of citric acid and stir until dissolved.

[0046] The temperature was slowly raised to 110°C, and the reflux reaction was carried out at this temperature for 6 hours.

[0047] The slurry system was cooled to 60°C, and 3 parts of vegetable oil, 35 parts of plant secretion liquid and 45 parts of plant extract were added sequentially while stirring at 45 r / min. The mixture was stirred at this temperature for 80 h to obtain the plasticizer.

[0048] Comparative Example 1

[0049] The preparation process of the plant extract is as follows: (I) Collect the cut sections of *Gnaphalium affine*, *Gnaphalium affine*, *Gnaphalium affine*, dandelion, and *Euphorbia helioscopia*, and pound them for 23 minutes using a pounder with an impact energy of 2.0 kJ and a pounding frequency of 40 bpm. Pound the plant stems and leaves and collect the solid-liquid mixture; (II) Wash the solid-liquid mixture repeatedly with 65℃ hot water for 30 minutes, sieve out the solids through a 60-mesh sieve, add 15% sodium carboxymethyl cellulose by weight to the liquid, and stir at 65 r / min for 70 minutes to obtain a pre-prepared solution; (III) Add 32% 90% ethanol by weight to the pre-prepared solution, let it stand for 45 minutes to precipitate, remove the supernatant, and obtain the plant extract;

[0050] The mass ratio of *Gnaphalium affine*, *Gnaphalium affine*, *Gnaphalium affine*, dandelion, and *Euphorbia helioscopia* is 1:1:2:1.2:0.2.

[0051] The vegetable oils include equal proportions of coconut oil and perilla seed oil;

[0052] Modified lignin is obtained by oxidative depolymerization of lignin followed by oxidase degradation and modification. The specific process of lignin oxidative depolymerization is as follows: lignin is immersed in hydrogen peroxide at 60℃ and stirred at 80r / min for 30min. Oxygen is introduced during stirring at a flow rate of 2m / s to oxidize and depolymerize the lignin. The specific process of lignin oxidase degradation and modification is as follows: the oxidized and depolymerized lignin is mixed with oxidase and cultured under ventilation at 25℃ and 95% humidity for 6 days. After that, modified lignin is obtained.

[0053] Add 8 parts of n-butanol to the reactor; while stirring at 45 r / min, slowly add 25 parts of modified lignin. Slowly raise the temperature to 65℃ and continue stirring for 1.5 h to allow the lignin to fully swell and disperse, forming a uniform and viscous slurry; then add 7 parts of citric acid and stir until dissolved.

[0054] The temperature was slowly raised to 100°C, and the reflux reaction was carried out at this temperature for 4 hours.

[0055] The slurry system was cooled to 55°C, and 2 parts of vegetable oil and 70 parts of plant extract were added sequentially while stirring at 45 r / min. The mixture was stirred at this temperature for 70 h to obtain the plasticizer.

[0056] Comparative Example 2

[0057] The preparation process of plant secretions is as follows: (i) Wash the vines, creeping grass, jade tree, dandelion and Euphorbia helioscopia to remove the surface soil, and air dry the surface moisture in a ventilated environment with 85% humidity; (ii) Straighten and tie the dried vines, creeping grass, jade tree, dandelion and Euphorbia helioscopia; (iii) Cut off the front end, tilt the cut end downward so that the secretion drips, and after 5 minutes, make a horizontal cut again 5 cm above the cut end. Repeat this process until the whole bundle is cut off and collect the secretion.

[0058] The mass ratio of *Gnaphalium affine*, *Gnaphalium affine*, *Gnaphalium affine*, dandelion, and *Euphorbia helioscopia* is 1:1:2:1.2:0.2.

[0059] The vegetable oils include equal proportions of coconut oil and perilla seed oil;

[0060] Modified lignin is obtained by oxidative depolymerization of lignin followed by oxidase degradation and modification. The specific process of lignin oxidative depolymerization is as follows: lignin is immersed in hydrogen peroxide at 60℃ and stirred at 80r / min for 30min. Oxygen is introduced during stirring at a flow rate of 2m / s to oxidize and depolymerize the lignin. The specific process of lignin oxidase degradation and modification is as follows: the oxidized and depolymerized lignin is mixed with oxidase and cultured under ventilation at 25℃ and 95% humidity for 6 days. After that, modified lignin is obtained.

[0061] Add 8 parts of n-butanol to the reactor; while stirring at 45 r / min, slowly add 25 parts of modified lignin. Slowly raise the temperature to 65℃ and continue stirring for 1.5 h to allow the lignin to fully swell and disperse, forming a uniform and viscous slurry; then add 7 parts of citric acid and stir until dissolved.

[0062] The temperature was slowly raised to 100°C, and the reflux reaction was carried out at this temperature for 4 hours.

[0063] The slurry system was cooled to 55°C, and 2 parts of vegetable oil and 70 parts of plant secretion were added sequentially while stirring at 45 r / min. Stirring was maintained at this temperature for 70 h to obtain the plasticizer.

[0064] Comparative Example 3

[0065] The preparation process of plant secretions is as follows: (i) Wash the vines, creeping grass, jade tree, dandelion and Euphorbia helioscopia to remove the surface soil, and air dry the surface moisture in a ventilated environment with 85% humidity; (ii) Straighten and tie the dried vines, creeping grass, jade tree, dandelion and Euphorbia helioscopia; (iii) Cut off the front end, tilt the cut end downward so that the secretion drips, and after 5 minutes, make a horizontal cut again 5 cm above the cut end. Repeat this process until the whole bundle is cut off and collect the secretion.

[0066] The preparation process of the plant extract is as follows: (I) Collect the cut sections of *Gnaphalium affine*, *Gnaphalium affine*, *Gnaphalium affine*, dandelion, and *Euphorbia helioscopia*, and pound them for 23 minutes using a pounder with an impact energy of 2.0 kJ and a pounding frequency of 40 bpm. Pound the plant stems and leaves and collect the solid-liquid mixture; (II) Wash the solid-liquid mixture repeatedly with 65℃ hot water for 30 minutes, sieve out the solids through a 60-mesh sieve, add 15% sodium carboxymethyl cellulose by weight to the liquid, and stir at 65 r / min for 70 minutes to obtain a pre-prepared solution; (III) Add 32% 90% ethanol by weight to the pre-prepared solution, let it stand for 45 minutes to precipitate, remove the supernatant, and obtain the plant extract;

[0067] The mass ratio of *Gnaphalium affine*, *Gnaphalium affine*, *Gnaphalium affine*, dandelion, and *Euphorbia helioscopia* is 1:1:2:1.2:0.2.

[0068] The vegetable oils include equal proportions of coconut oil and perilla seed oil;

[0069] Add 8 parts of n-butanol to the reactor; while stirring at 45 rpm, slowly add 25 parts of lignin. Slowly raise the temperature to 65°C and continue stirring for 1.5 hours to allow the lignin to fully swell and disperse, forming a uniform and viscous slurry; then add 7 parts of citric acid and stir until dissolved.

[0070] The temperature was slowly raised to 100°C, and the reflux reaction was carried out at this temperature for 4 hours.

[0071] The slurry system was cooled to 55°C, and 2 parts of vegetable oil, 28 parts of plant secretion liquid and 42 parts of plant extract were added sequentially while stirring at 45 r / min. The mixture was stirred at this temperature for 70 h to obtain the plasticizer.

[0072] Comparative Example 4

[0073] Dioctyl adipate was used as a plasticizer.

[0074] Comparative Example 5

[0075] Dioctyl sebacate was used as a plasticizer.

[0076] Comparative Example 6

[0077] Di-n-octyl adipate was used as a plasticizer.

[0078] Performance testing

[0079] Samples were prepared by mixing polyvinyl chloride (PVC) with plasticizers at a weight ratio of 10% as used in Examples 1-3 and Comparative Examples 1-6, respectively, and then injection molding, shaping, and cooling to form samples designated as Group A. Samples were prepared by mixing polypropylene with plasticizers from Examples 1-3 and Comparative Examples 1-6, respectively, and then injection molding, shaping, and cooling to form samples designated as Group B. Samples were prepared by mixing natural rubber with plasticizers from Examples 1-3 and Comparative Examples 1-6, respectively, and then injection molding, shaping, and cooling to form samples designated as Group C. The performance of each group of samples was tested according to GB / T 5470-2008 "Determination of Low-Temperature Embrittlement Temperature of Plastics", tensile properties "GB / T 1040.1-2018", and heat distortion temperature "GB / T1634.1-2019".

[0080] The test results are shown in the table below.

[0081]

[0082] As can be seen from the table above, comparing Examples 1-3 with Comparative Examples 1-6, the test results of Examples 1-3 are all better than those of Comparative Examples 1-6. Among them, comparing Example 2, which has the best values ​​among Examples 1-3, with Comparative Example 1, it can be found that the difference between Example 2 and Comparative Example 1 is that it uses plant secretions. Plant secretions contain a large amount of high molecular weight substances, which have good flexibility and adhesion. As a plasticizer base material, it can be well compatible with the polymer matrix. Therefore, the performance of Example 2 is better than that of Comparative Example 1 in all aspects.

[0083] Comparing Example 2 with Comparative Example 2, it can be found that the difference between Example 2 and Comparative Example 2 is that Example 2 uses plant extracts. The plant extracts are purified by ethanol, which removes most of the sugars, proteins and other easily moldy components, while retaining functional components such as terpenes and flavonoids. It has good compatibility with lignin and citric acid system, and together they form a uniform and stable plasticizing system that is not easy to precipitate, making the performance of Example 2 better than that of Comparative Example 2.

[0084] Comparing Example 2 with Comparative Example 3, it can be found that the difference between Example 2 and Comparative Example 3 is that Example 2 uses modified lignin as the core skeleton. With modified lignin as the core skeleton, n-butanol and citric acid undergo esterification reaction to generate a lignin-citric acid ester network structure. This structure is not only flexible itself, but can also form strong hydrogen bonds and van der Waals forces with the polymer molecular chains, thereby greatly reducing the migration and volatilization loss of plasticizers and achieving long-term plasticization. This makes the performance of Example 2 better than that of Comparative Example 3.

[0085] Comparative Examples 4-6 used commercially available plasticizers to sequentially produce plastics from polyvinyl chloride, polypropylene, and natural rubber. The resulting plastics were compared with those produced in Examples 1-3 using plasticizers to sequentially produce plastics from polyvinyl chloride, polypropylene, and natural rubber. It was found that the addition of plasticizers from Examples 1-3 to polyvinyl chloride, polypropylene, and natural rubber effectively increased the embrittlement temperature, tensile strength, and heat distortion temperature, resulting in better stability of the plastics in practical use.

[0086] The embodiments described above are merely examples of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention.

Claims

1. A low-temperature viscosity-reducing plasticizer, characterized in that, The plasticizer, by weight, comprises 6-12 parts n-butanol, 5-10 parts citric acid, 23-26 parts modified lignin, 1-3 parts vegetable oil, 20-35 parts plant secretions, and 35-45 parts plant extracts. The preparation process of the plant secretions is as follows: (i) Wash *Gnaphalium affine*, *Gnaphalium affine*, *Gnaphalium affine*, dandelion, and *Polygonum hydropiper* to remove surface soil and air-dry the surface moisture in a ventilated environment with 85% humidity; (ii) Straighten and bundle the dried *Gnaphalium affine*, *Gnaphalium affine*, *Gnaphalium affine*, dandelion, and *Polygonum hydropiper*; (iii) Cut off the front end, tilting the cut end downwards to allow the secretions to drip. After 5 minutes, make another horizontal cut 5 cm above the cut end, repeating this process until the bundle is completely cut. Collect the secretions. The preparation process of the plant extracts is as follows: (i) Collect the cut *Gnaphalium affine*, *Gnaphalium affine*, *Gnaphalium affine*, dandelion, and *Polygonum hydropiper*, using an impact energy of 2.0... (i) Use a tamping device with a tamping frequency of 40 bpm to tamp the plant stems and leaves for 20-25 minutes, and collect the solid-liquid mixture; (ii) Use 65℃ hot water to repeatedly wash the solid-liquid mixture for 30 minutes, sieve out the solids through a 60-mesh sieve, add 15% sodium carboxymethyl cellulose by weight to the liquid, stir at 65 r / min for 60-80 minutes to obtain the pre-prepared liquid; (iii) Add 32% 90% ethanol by weight to the pre-prepared liquid, let it stand for 45 minutes to settle, remove the supernatant, and obtain the plant extract; The mass ratio of the goose vine, creeping grass, green jade tree, dandelion and Euphorbia helioscopia is 1:1:(1-3):1.2:0.2; The modified lignin is obtained by oxidative depolymerization of lignin followed by oxidase degradation and modification. The specific process of lignin oxidative depolymerization is: immerse lignin in hydrogen peroxide at 60℃, stir at 80 r / min Stir for 30 minutes, during which oxygen is introduced and the airflow speed is set at 2 m / s to oxidize and depolymerize lignin; the specific process of lignin oxidase degradation and modification is as follows: the oxidized and depolymerized lignin is mixed with oxidase and cultured in a ventilated environment at 25℃ and 95% humidity for 6 days, and then the modified lignin is obtained.

2. The low-temperature viscosity-reducing plasticizer according to claim 1, characterized in that, The vegetable oils include equal proportions of coconut oil and perilla seed oil.

3. The low-temperature viscosity-reducing plasticizer according to claim 1, characterized in that, The mass ratio of lignin to oxidase is 1:0.

1.

4. A method for preparing a low-temperature viscosity-reducing plasticizer according to any one of claims 1-3, characterized in that, Includes the following steps: S1. Add n-butanol to the reactor; under stirring at 45 r / min, slowly add modified lignin, slowly raise the temperature to 60-70℃, and continue stirring for 1-2 hours to allow the lignin to fully swell and disperse, forming a uniform and viscous slurry; then add citric acid and stir until it dissolves. S2, slowly raise the temperature to 90-110℃, and reflux at this temperature for 3-6 hours; S3. Cool the slurry system to 50-60℃, and add vegetable oil, plant secretion liquid and plant extract in sequence while stirring at 45r / min. Keep stirring at this temperature for 60-80h to obtain the plasticizer.

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