CN111484590A - Preparation method and application of feather keratin modified urea-formaldehyde resin - Google Patents
Preparation method and application of feather keratin modified urea-formaldehyde resin Download PDFInfo
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- A01—AGRICULTURE; FORESTRY; ANIMAL HUSBANDRY; HUNTING; TRAPPING; FISHING
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- A01G9/00—Cultivation in receptacles, forcing-frames or greenhouses; Edging for beds, lawn or the like
- A01G9/02—Receptacles, e.g. flower-pots or boxes; Glasses for cultivating flowers
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- C08G12/34—Condensation polymers of aldehydes or ketones with only compounds containing hydrogen attached to nitrogen of aldehydes with heterocyclic compounds and acyclic or carbocyclic compounds
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- C09J161/00—Adhesives based on condensation polymers of aldehydes or ketones; Adhesives based on derivatives of such polymers
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- C09J161/00—Adhesives based on condensation polymers of aldehydes or ketones; Adhesives based on derivatives of such polymers
- C09J161/20—Condensation polymers of aldehydes or ketones with only compounds containing hydrogen attached to nitrogen
- C09J161/32—Modified amine-aldehyde condensates
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Abstract
The invention discloses a preparation method and application of a livestock feather keratin modified urea-formaldehyde resin, which comprises the following steps: 1) extracting keratin from waste livestock and poultry feather by a urea hydrolysis method, and 2) graft copolymerization of the keratin and a toughening agent to prepare degradable urea-formaldehyde resin; the modified urea-formaldehyde resin can be applied to the preparation of straw flowerpots; the modified urea-formaldehyde resin is convenient to prepare and operate, has obvious effect, provides a new application approach for the waste feather, provides a new idea for the field utilization problem of the waste straw, and changes waste into valuable; meanwhile, the problems of difficult degradation and large brittleness of the urea-formaldehyde resin are solved, the environment is protected, and the manufacturing process applied to the straw flowerpot is provided.
Description
Technical Field
The invention belongs to the technical field of chemical adhesives, and particularly relates to preparation and application of a feather keratin modified urea-formaldehyde resin.
Background
The urea-formaldehyde resin adhesive is thermosetting polymer synthetic resin with amino groups and is widely applied to the wood processing industry. Urea-formaldehyde resin is used in large quantities due to its advantages of simple manufacturing process, low raw material price, high bonding strength and the like. However, after the urea-formaldehyde resin is cured, short chain segments (ether bonds, methine bonds and the like) are interwoven to form a body-type network structure, the structure is compact and small in porosity, the number of exposed biodegradable groups is small, and biological enzymes playing a role in decomposition are difficult to completely permeate into the body-type structure, so that the urea-formaldehyde resin is difficult to biodegrade naturally after being discarded.
At present, the process of applying waste crop straws to flowerpot preparation in China is a hot pressing process, wherein urea formaldehyde resin is mostly used as an adhesive or a main adhesive component. The urea-formaldehyde resin used as an adhesive for manufacturing the straw flowerpot is intended to prolong the service life of the straw flowerpot, but the straw itself belongs to herbaceous plants and is easily eroded by microorganisms, the small contact surface of the crushed particles is increased, and the straw is easy to absorb water and expand, so that the product mainly made of the straw has poor weather resistance and short service life, the product is usually treated in a composting or returning mode after being damaged, and the residual urea-formaldehyde resin which is difficult to degrade influences the overall degradation efficiency of the material. Meanwhile, the straw flowerpot prepared from the urea resin has large brittleness and small toughness, so that the further application of the straw flowerpot is limited.
Patent CN108530829A discloses a method for manufacturing straw flowerpots by using corn starch-soybean protein isolate modified urea-formaldehyde resin, which comprises the steps of preparing a corn starch adhesive, blending the corn starch adhesive with a mixed solution of urea-formaldehyde resin and soybean protein isolate to obtain the modified urea-formaldehyde resin, stirring the obtained adhesive and rice hulls, and injecting the mixture into a hydraulic press mold for hot press molding to obtain the straw flowerpots; patent CN104130732A discloses a cottonseed protein modified urea-formaldehyde resin adhesive powder, which is prepared by preforming cottonseed protein, powdered urea-formaldehyde resin adhesive and curing agent in a dry state to obtain modified urea-formaldehyde resin; patent CN102277114A discloses a preparation method of a mycoprotein urea-formaldehyde adhesive, wherein amino acid mycoprotein is added in the production process of urea-formaldehyde resin to reduce free formaldehyde in the adhesive; patent CN104745129A discloses a biodegradable modified urea-formaldehyde resin adhesive and application thereof, the method prepares degradable urea-formaldehyde resin by a method combining copolymerization and blending, and makes a seedling container for seedling growth. However, the proteins of the protein modified urea resin adhesive mainly comprise vegetable proteins, and the problem of high brittleness of products is not solved.
In the livestock and poultry raising and processing in China, about 140 million tons of waste feathers are produced every year, and most of the waste feathers are used as waste to cause resource waste and environmental pollution except for a small part of waste feathers used as animal feed. The keratin content in the feather is more than 90 percent, and the keratin is also a natural degradable polymer because of being rich in active groups such as amino, carboxyl and the like which are easy to be corroded by microorganisms, and can be directly used for preparing the adhesive. Patent CN102838967B discloses a method for preparing keratin adhesive by using feathers, which is characterized in that soluble feather keratin is obtained by immersing cleaned, dried and sheared feathers into a dissolving solution, but the viscosity of the keratin adhesive obtained by the method is 39000mpas, which belongs to the category of ultrahigh viscosity, is not beneficial to the ductility and permeability of the adhesive in the gluing process, and the gluing strength of the adhesive which is only keratin is not capable of meeting the performance requirements of flowerpots (the wet strength is about 1.0 MPa). Research on keratin-modified urea-formaldehyde resin adhesive (Jilin forestry science and technology, 2012 and 41(3)) shows that the keratin and urea-formaldehyde resin can be used for preparing environment-friendly modified urea-formaldehyde resin through copolymerization reaction, the free formaldehyde content of the urea-formaldehyde resin after the keratin is modified is reduced, and the formaldehyde released by a bonded product is reduced. The publications mainly use keratin modified urea-formaldehyde resin to reduce formaldehyde release in the wood-based panel industry, and do not solve the problem of brittleness of the adhesive. At present, no report is found in the related research of applying keratin modified urea resin to degradable straw flowerpots.
Disclosure of Invention
The invention aims to provide a feather keratin modified urea-formaldehyde resin adhesive for livestock and poultry, which is characterized in that hydrolyzed feather keratin is obtained in a mild chemical mode and is subjected to graft copolymerization with urea, formaldehyde and a toughening agent, so that the synthesized modified urea-formaldehyde resin adhesive has biodegradability and toughness required by straw flowerpots.
The invention aims to realize the following technical scheme, and the preparation method and the application of the feather keratin modified urea-formaldehyde resin comprise the following steps:
1) and (2) extracting the hydrolyzed keratin, namely drying the cut and cleaned livestock and poultry feathers in an oven at 30-40 ℃ for 48h, immersing the feathers in a petroleum ether solution for 24h to degrease and clean, immersing the feathers in a 1-3 g/L Cetrimide (CTAB) solution for 4h to remove microorganisms, cleaning, immersing the cleaned feathers in a 4-8 mol/L urea solution, wherein the mass ratio of the feathers to the urea solution is 1: 15-21, adding L-cysteine with the mass of 5-15% of the feathers, adjusting the pH of the mixed solution to 12 by using a 20% sodium hydroxide solution, stirring for 5h at the water bath temperature of 85 ℃ at the speed of 100-300 rpm, centrifuging for 10-20 min at the speed of 10000rpm, taking the supernatant, adjusting the pH to 4 by using an acid solution to precipitate dissolved protein, cleaning by using deionized water until the eluate is neutral (the cleaning solution becomes transparent and colorless), freezing and drying for 48h at the temperature of 40 ℃ in vacuum degree of 20pa, and freeze-drying to obtain the keratin powder.
The method adopts an ion extraction method, utilizes CTAB, urea and L-cysteine to extract the keratin in the feather, can reduce the influence of chemical reagents added in the extraction process on the grafted functional groups in the subsequent urea-formaldehyde resin synthesis step compared with the conventional extraction methods such as an acid-base method, an oxidation method and the like, and in addition, the commercial keratin is usually applied to feed processing, a thermal drying mode is adopted, and the product contains a polypeptide mixture and is not beneficial to the application of the subsequent keratin adhesive.
1) Preparing modified urea-formaldehyde resin: adding a formaldehyde solution with the concentration of 37% into a reaction kettle, heating to 40-45 ℃, adjusting the pH to 8.0-8.5 by using a sodium hydroxide solution with the concentration of 20%, then adding the keratin powder obtained in the step 1) and a first batch of urea particles (the adding amount of the first batch of urea accounts for 60% -80% of the total amount of the urea), reacting for 10min, heating to 60-65 ℃, adding a first batch of toughening agent, heating to 88-92 ℃, and keeping the temperature for 50 min; adjusting the pH value of the mixed solution to 5.0-5.5 by using a 10% ammonium chloride/formic acid solution, adding a second batch of urea particles and melamine, wherein the adding amount of the second batch of urea accounts for 15-25% of the total amount of the urea, and carrying out heat preservation reaction to the end point (adding cold water at 20 ℃ to obtain white water mist, wherein the reactant is in a wire-drawing state for about 30-60 min); adjusting the pH value to 7.5-8.5 by using sodium hydroxide with the concentration of 20%, adding a third batch of urea particles, wherein the adding amount of the third batch of urea accounts for 5% -15% of the total amount of the urea, and reacting for 20-30 min; and adding a second batch of toughening agent, wherein the addition amount of the second batch of toughening agent accounts for 1-5% of the total amount of urea, and finally naturally cooling to 35 ℃ for discharging to obtain the feather keratin modified urea-formaldehyde resin.
In the step, the toughening agent is added in two batches, the first stage and the third stage are mainly molecular addition stages under an alkaline condition, the addition in the first stage is mainly a polycondensation stage in which the prepolymer is synthesized in advance to participate in the second stage, and the macromolecular crosslinking formed in the third stage is that the prepolymer further generates a dehydration reaction of hydroxyl and amino and mainly expands a molecular chain to form a long-chain macromolecular structure.
Further, the feather type of the livestock and poultry in the step 1) is one or more of chicken feather, duck feather, goose feather and pigeon feather, and the feathers are generally from poultry farms.
Further, the solute in the acidic solution in the step 1) is sulfuric acid, nitric acid, ammonium sulfate or ammonium nitrate, and the concentration of the acidic solution is 0.1 mol/L.
Further, the molar ratio of the total amount of the formaldehyde and the urea in the step 2) is 1-1.5: 1, the addition amount of keratin accounts for 5-20% of the total mass of urea. The viscosity of the final modified urea-formaldehyde resin is not beneficial to sizing due to excessive protein content; too little is not favorable for the modification effect.
Further, the molar ratio of the melamine to the formaldehyde added in the step 2) is 1: 2-3, and the melamine is beneficial to improving the water resistance of the adhesive.
Further, the toughening agent in the step 2) is one of polyvinyl alcohol, polyvinyl acetate emulsion and polyethylene glycol diglycidyl ether.
The invention further provides an application of the feather keratin modified urea-formaldehyde resin in preparation of straw flowerpots. The preparation method of the straw flowerpot comprises the following steps: and (3) crushing the recovered waste straws to the particle size of 0.2-0.8 mm, and drying at the temperature of 60-80 ℃ until the water content is 9-12%. Weighing 10kg of crushed straws, and placing the modified urea-formaldehyde resin adhesive solution, ammonium chloride particles (curing agent) and paraffin wax (release agent) in a stirrer at the temperature of 30-60 ℃ to stir for 30 min; and injecting the stirred mixed material into a flowerpot forming die, wherein the hydraulic pressure is 20-30 MPa, the hot pressing temperature is 110-160 ℃, the hot pressing time is 30-60 s, and the prepared straw flowerpot is aged for 24-48 hours to completely eliminate the residual stress.
For the sizing of the adhesive, the more the curing agent and the release agent are, the better the performance is, but the curing agent and the release agent influence the strength of the adhesive too much; therefore, the mass ratio of the straw to the modified urea resin to the ammonium chloride to the paraffin is preferably 100: 50-70: 1-3: 3-6.
The waste straw is preferably one or more of rice straw, wheat straw and corn straw.
According to the invention, hydrolyzed feather keratin is obtained by a mild chemical mode, and is subjected to graft copolymerization with formaldehyde, a toughening agent and amino groups in urea, and the linearity of a body structure formed by urea and formaldehyde is prolonged after grafting, so that the synthesized modified urea-formaldehyde resin adhesive has biodegradability and toughness required by straw flowerpots. Compared with the straw flowerpot prepared by using the existing adhesive, the adhesive/flowerpot prepared by the method has the following beneficial effects:
1. the straw flowerpot prepared from the modified urea-formaldehyde resin synthesized by the method has the advantages that the physical and mechanical strength is in accordance with the basic use, the flowerpot is good in toughness and small in brittleness, the application is wider, the formaldehyde release amount in the urea-formaldehyde resin is greatly reduced, the damage to the root system of the plant is avoided, the flowerpot can be completely degraded by adopting a soil burying or composting mode after being used and damaged for a long time, the environmental protection effect is high, the environmental adaptability is strong, and the straw flowerpot has good cyclic ecological effect and social and economic effects.
2. The method adopts an ion extraction technology, effectively extracts keratin in the waste feather, realizes reasonable utilization of waste, and prevents chemical reagents used in the extraction process from influencing the subsequent urea resin modification step.
3. The method uses the keratin which is easy to degrade to modify the urea-formaldehyde resin which is difficult to degrade, endows the traditional urea-formaldehyde resin with high added value of degradability, and avoids environmental harm; the keratin belongs to insoluble fibrous protein, contains more cystine, has disulfide bond content of about 10-15 times compared with cysteine in vegetable protein, so that the disulfide bond content is particularly high, and the keratin has a crosslinking effect in a protein peptide chain, so that the keratin has stable chemical property and higher mechanical strength, and simultaneously provides a matched flowerpot preparation process, and meets the requirements on mechanical performance in use of flowerpots.
Detailed Description
The technical solutions of the present invention will be described more clearly below with reference to embodiments of the present invention, which are only some embodiments of the present invention, and not all embodiments, and the specific embodiments are not intended to limit the present invention.
In the examples, the reactor was purchased from Shanghai Shensheng technologies, Inc., model F5 HA;
urea was purchased from national pharmaceutical group chemical reagents ltd;
in the following examples, reagents and equipment to be referred to are commercially available unless otherwise specified.
Example 1
1) Extracting hydrolyzed keratin, namely drying 800g of cut and cleaned chicken feathers in an oven at 30 ℃ for 48h, immersing the chicken feathers in a petroleum ether solution for 24h to degrease and clean, immersing the chicken feathers in a 3 g/L Cetrimide (CTAB) solution for 4h to remove microorganisms, cleaning, immersing the cleaned chicken feathers in a 4 mol/L urea solution, wherein the mass ratio of the chicken feathers to the urea solution is 1: 15, adding L-cysteine accounting for 5 percent of the mass of the chicken feathers, adjusting the pH of the mixed solution to 12 by using a sodium hydroxide solution with the concentration of 20 percent, stirring for 5h at the speed of 100rpm in a water bath at 85 ℃, centrifuging for 10min at the speed of 10000rpm, taking supernatant, adjusting the pH to 4 by using a 0.1 mol/L sulfuric acid solution to precipitate dissolved protein, cleaning by using deionized water until the cleaning solution becomes transparent and colorless, carrying out vacuum freeze drying for 48h at the temperature of-40 ℃, and carrying out freeze drying at the vacuum degree of 20pa to obtain keratin powder.
2) Preparing modified urea-formaldehyde resin: adding 500g of formaldehyde solution with the concentration of 37% into a reaction kettle, heating to 40 ℃, adjusting the pH to 8.0 by using sodium hydroxide solution with the concentration of 20%, and then adding the keratin powder and urea particles obtained in the step 1), wherein the molar ratio of the total amount of formaldehyde to the total amount of urea is 1:1, the addition amount of keratin accounts for 5% of the total amount of urea, and the addition amount of a first batch of urea accounts for 60% of the total amount of urea. After reacting for 10min, heating to 60 ℃, adding a first batch of flexibilizer polyvinyl alcohol (the mass of the first batch of polyvinyl alcohol accounts for 15% of the total amount of the urea), heating to 88 ℃, and keeping the temperature for 50 min; adjusting the pH value of the mixed solution to 5.0 by using an ammonium chloride/formic acid solution with the concentration of 10%, adding a second batch of urea particles, wherein the adding amount of the second batch of urea accounts for 25% of the total amount of the urea, adding melamine, and reacting for 45min to the end point (adding cold water with the temperature of 20 ℃ to form white water mist, wherein the adhesive is in a wire-drawing state) at the temperature of 1: 2; adjusting the pH value to 7.5 by using sodium hydroxide with the concentration of 20 percent, adding a third batch of urea particles (the adding amount accounts for 15 percent of the total amount of the urea), and reacting for 20 min; adding a second batch of flexibilizer polyvinyl alcohol which accounts for 1% of the total amount of the urea, naturally cooling to normal temperature, and discharging to obtain the modified urea-formaldehyde resin.
3) Manufacturing a straw flowerpot: crushing the recovered waste rice straw into particles with the particle size of 0.2mm, and drying the particles at the temperature of 60 ℃ until the water content is 12%. Weighing 10kg of crushed straws and the modified urea-formaldehyde resin, the ammonium chloride particles and the solid paraffin obtained in the step 2), placing the straws and the modified urea-formaldehyde resin, the ammonium chloride particles and the solid paraffin in a stirrer at the temperature of 30 ℃, and stirring for 30min, wherein the mass ratio of the straw powder, the modified urea-formaldehyde resin, the ammonium chloride particles and the solid paraffin is 100: 50:3:6. Injecting the stirred mixed material (generally speaking, the mass ratio of the straw powder, the modified urea-formaldehyde resin, the ammonium chloride and the paraffin is 100: 50-70: 1-3: 3-6, and the purpose of the invention can be achieved) into a flowerpot forming mold (purchased from the same-force pneumatic hydraulic equipment limited company of Shandong Tengzhou, model YQ32-200T), preparing the straw flowerpot by hot press forming under the hydraulic pressure of 20MPa, the hot press temperature of 110 ℃ and the hot press time of 30s, and ageing the prepared straw flowerpot for 24 hours to completely eliminate the residual stress; meanwhile, the straw flowerpot prepared from the unmodified urea-formaldehyde resin is prepared by replacing the environment-friendly urea-formaldehyde resin prepared in the step 3) with the unmodified urea-formaldehyde resin (the preparation method is shown in Chinese patent 1461786A, application number: 02121076.4 and specification) to be used as a reference.
The physical and chemical properties of the modified urea-formaldehyde resin and the unmodified urea-formaldehyde resin prepared in this example are compared in table 1. In Table 1, "unmodified urea-formaldehyde resin" refers to "environmental-friendly urea-formaldehyde resin" prepared with reference to Chinese patent 1461786A (application No. 02121076.4).
The detection methods in table 1 are all conventional in the art: in table 1, the measurements of solid content, pH, free formaldehyde, viscosity and bond strength are taken for standard wood adhesives and their resin test methods: GB/T14074.5-1993, GB/T14074.4-1993, GB/T14074.16-1993, GB/T14074.3-1993 and GB/T17657-1999.
TABLE 1 Urea-formaldehyde resin physical and chemical Properties
It can be seen from table 1 that the content of free formaldehyde in the modified urea-formaldehyde resin obtained in example 1 is greatly reduced, the viscosity of the adhesive is increased, and the bonding strength is increased, which indicates that the adhesive has better toughness, is beneficial to improving the strength of the molded straw flowerpot in the later period, and is more suitable for crop growth.
The physical and chemical properties of the straw flowerpot prepared by using the urea resin obtained in the step 3) of the embodiment are shown in the table 2:
the detection methods in table 2 are all conventional in the art: in Table 2, the flexural strength, flexural modulus, impact toughness and detection methods are GB/T17657-2013 respectively, and the degradation rate after 180 days is BSENISO 14855-2009.
TABLE 2 straw flowerpot physicochemical properties
In table 2, the "straw flowerpot prepared from unmodified urea-formaldehyde resin" is a straw flowerpot prepared from urea-formaldehyde resin prepared in example 1 of chinese patent 1461786a (application number: 02121076.4) instead of the modified urea-formaldehyde resin prepared in step 3) of example 1.
As can be seen from table 2, the straw flowerpot prepared from the modified urea-formaldehyde resin has better mechanical properties than the straw flowerpot prepared from the unmodified urea-formaldehyde resin, the toughness of the straw flowerpot prepared from the urea-formaldehyde resin after the impact strength reaction modification is more excellent, and the degradation rate after 180 days is higher, so that the straw flowerpot prepared from the modified urea-formaldehyde resin is more easily corroded by microorganisms and is degraded.
In the specific implementation, the molar ratio of the added melamine to the added formaldehyde is within the range of 1: 2-3, and the molar ratio of the total amount of the formaldehyde to the total amount of the urea is 1-1.5: within the range of 1, the addition amount of the keratin accounts for 5-20% of the total mass of the urea, and the aim of the invention can be achieved.
Example 2
1) And (2) extracting the hydrolyzed keratin, namely drying 80g of cut and cleaned duck feathers in an oven at 40 ℃ for 48h, immersing the duck feathers in a petroleum ether solution for 24h to degrease and clean, immersing the duck feathers in a 3 g/L Cetrimide (CTAB) solution for 4h to remove microorganisms and clean, immersing the cleaned duck feathers in a 8 mol/L urea solution, wherein the mass ratio of the duck feathers to the urea solution is 1: 21, adding L-cysteine accounting for 15% of the mass of the duck feathers, adjusting the pH of the mixed solution to 12 by using a 20% sodium hydroxide solution, stirring the mixture for 5h at the water bath speed of 85 ℃, centrifuging the mixture for 20min at the speed of 10000rpm, taking supernatant, adjusting the pH to 4 by using a 0.1 mol/L nitric acid solution to precipitate dissolved protein, cleaning the mixture by using deionized water until the cleaning solution becomes transparent and colorless, and freeze-drying the mixture to obtain keratin powder.
2) Preparing modified urea-formaldehyde resin: adding 500g of formaldehyde solution with the concentration of 37% into a reaction kettle, heating to 45 ℃, adjusting the pH to 8.5 by using sodium hydroxide solution with the concentration of 20%, and then adding keratin powder and urea particles, wherein the molar ratio of the total amount of formaldehyde to the total amount of urea is 1.5:1, the addition amount of keratin accounts for 20% of the total amount of urea, and the addition amount of urea accounts for 70% of the total amount of urea. After reacting for 10min, heating to 65 ℃, adding a toughening agent polyvinyl acetate emulsion, wherein the mass of the toughening agent polyvinyl acetate emulsion accounts for 20% of the total mass of the urea, heating to 92 ℃, and keeping the temperature for 50 min; adjusting the pH value of the mixed solution to 5.5 by using a 10% ammonium chloride/formic acid solution, adding urea particles, wherein the adding amount of urea accounts for 25% of the total amount of urea, adding melamine, the molar ratio of the melamine to the formaldehyde is 1:3, and carrying out heat preservation reaction for 30min to the end point (adding cold water at 20 ℃ to form white water mist, wherein the adhesive is in a wire drawing state); adjusting the pH value to 8.5 by using sodium hydroxide with the concentration of 20%, adding urea particles, wherein the adding amount of the urea accounts for 5% of the total amount of the urea, and reacting for 30 min; adding a toughening agent polyvinyl acetate emulsion which accounts for 5 percent of the total amount of the urea, cooling to 35 ℃ and discharging;
3) manufacturing a straw flowerpot: crushing the recycled waste wheat straws to 0.8mm in particle size, and drying at 80 ℃ until the water content is 12%. After smashing, 10kg of straw is weighed, the modified urea-formaldehyde resin adhesive solution, ammonium chloride particles and solid paraffin are placed in a stirrer at the temperature of 30-60 ℃ to be stirred for 30min, and the mass ratio of the straw powder, the modified urea-formaldehyde resin, the ammonium chloride particles to the solid paraffin is 100: 70:1:3. And injecting the stirred mixed material into a flowerpot forming die, carrying out hot-press forming for 60s at the hot-press temperature of 160 ℃ under the hydraulic pressure of 30MPa to prepare the straw flowerpot, and ageing the prepared straw flowerpot for 48 hours to completely eliminate residual stress to obtain the straw flowerpot prepared from the modified urea-formaldehyde resin.
Meanwhile, the straw flowerpot prepared from the unmodified urea-formaldehyde resin is prepared and obtained by replacing the modified urea-formaldehyde resin in the step 3) (the other steps are the same as the step 3) with the unmodified urea-formaldehyde resin (the preparation method is shown in Chinese patent 1461786A, application number is 02121076.4, and the environment-friendly urea-formaldehyde resin prepared in the specification) as a reference.
The physical and chemical properties of the straw flowerpot are shown in Table 3.
TABLE 3 straw flowerpot
Example 3
1) And (2) extracting the hydrolyzed keratin, namely drying 80g of chopped and cleaned goose feathers and pigeon feathers in an oven at the temperature of 30-40 ℃ for 48h, immersing the feathers in a petroleum ether solution for 24h to degrease, cleaning, immersing in a 2 g/L Cetrimide (CTAB) solution for 4h to remove microorganisms, cleaning, immersing the cleaned goose feathers and pigeon feathers in a 6 mol/L urea solution, wherein the mass ratio of the goose feathers to the pigeon feathers to the urea solution is 1: 18, adding L-cysteine accounting for 10% of the mass of the goose feathers and the pigeon feathers, adjusting the pH of the mixed solution to 12 by using a 20% sodium hydroxide solution, stirring for 5h at the speed of 200rpm in a water bath at the temperature of 85 ℃, centrifuging for 15min at the speed of 10000rpm, taking supernatant, adjusting the pH to 4 by using a 0.1 mol/L ammonium sulfate solution to precipitate dissolved protein, cleaning by using deionized water until the cleaning solution becomes transparent and colorless, and freeze-drying to obtain the keratin powder.
2) Preparing modified urea-formaldehyde resin: adding 500g of formaldehyde solution with the concentration of 37% into a reaction kettle, heating to 43 ℃, adjusting the pH to 8.2 by using sodium hydroxide solution with the concentration of 20%, and then adding keratin powder and urea particles, wherein the molar ratio of the total amount of formaldehyde to the total amount of urea is 1.2: 1, the addition amount of keratin accounts for 10% of the total amount of urea, and the addition amount of urea accounts for 65% of the total amount of urea. After reacting for 10min, heating to 62 ℃, adding a toughening agent polyethylene glycol diglycidyl ether, wherein the mass of the toughening agent polyethylene glycol diglycidyl ether accounts for 17% of the total mass of urea, heating to 90 ℃, and keeping the temperature for 50 min; adjusting the pH value of the mixed solution to be 5.2 by using a 10% ammonium chloride/formic acid solution, adding urea particles, wherein the adding amount of urea accounts for 23% of the total amount of urea, adding melamine, the molar ratio of the melamine to the formaldehyde is 1:2.5, and carrying out heat preservation reaction for 60min to the end point (adding cold water at 20 ℃ to form white water mist, and the adhesive is in a wire drawing state); adjusting the pH value to 8.0 by using sodium hydroxide with the concentration of 20%, adding urea particles, wherein the adding amount of the urea accounts for 12% of the total amount of the urea, and reacting for 25 min; adding a toughening agent polyethylene glycol diglycidyl ether, wherein the toughening agent polyethylene glycol diglycidyl ether accounts for 3% of the total amount of urea, cooling to 35 ℃, and discharging;
3) manufacturing a straw flowerpot: crushing the recovered waste corn stalks to a particle size of 0.5mm, and drying at 70 ℃ until the water content is 11%. Weighing 10kg of crushed straws, and placing the modified urea-formaldehyde resin adhesive solution, ammonium chloride particles and solid paraffin in a 45 ℃ stirrer to stir for 30min, wherein the mass ratio of the straw powder, the modified urea-formaldehyde resin, the ammonium chloride particles and the solid paraffin is 100: 60:2:5. And injecting the stirred mixed material into a flowerpot forming die, carrying out hot-press forming for 45s at the hot-press temperature of 140 ℃ under the hydraulic pressure of 25MPa to prepare the straw flowerpot, and ageing the prepared straw flowerpot for 36 hours to completely eliminate residual stress to obtain the straw flowerpot prepared from the modified urea-formaldehyde resin. Meanwhile, the straw flowerpot prepared from the unmodified urea-formaldehyde resin is prepared by replacing the environment-friendly urea-formaldehyde resin prepared in the step 3) with the unmodified urea-formaldehyde resin (the preparation method is shown in Chinese patent 1461786A, application number: 02121076.4 and specification) to be used as a reference. The physical and chemical properties of the straw flowerpot are shown in Table 4.
TABLE 4 straw flowerpot physicochemical properties
The above description is only for the preferred embodiment of the present invention, and is not intended to limit the scope of the present invention. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention shall fall within the protection scope of the present invention.
Claims (10)
1. A preparation method of feather keratin modified urea resin is characterized by comprising the following specific steps:
1) degreasing feathers with petroleum ether, cleaning with cetrimide, soaking in urea solution of 4-8 mol/L, adding L-cysteine to adjust the pH value of the solution to 12, reacting for 5h at 85 ℃, centrifuging, taking supernatant, adjusting the pH value to =4 with acid solution, taking precipitate, cleaning, and freeze-drying to obtain keratin;
2) adjusting the pH value of a formaldehyde solution with the concentration of 37% to 8.0-8.5 at 40-45 ℃, adding the keratin powder obtained in the step 1) and the first batch of urea, reacting for 10min, heating to 60-65 ℃, adding the first batch of flexibilizer, heating to 88-92 ℃, and keeping the temperature for 50 min; adjusting the pH value to 5.0-5.5 by using an ammonium chloride/formic acid solution with the concentration of 10%, adding a second batch of urea and melamine, and carrying out heat preservation reaction until the reactant is in a wire-drawing state; then adjusting the pH value to 7.5-8.5, adding the rest urea, reacting for 20-30 min, adding a second batch of toughening agent, and naturally cooling to obtain the feather keratin modified urea-formaldehyde resin;
the adding amount of the first batch of urea accounts for 60-80% of the total amount of the urea, and the adding amount of the second batch of urea accounts for 15-25% of the total amount of the urea; the mass of the first batch of toughening agent accounts for 15-20% of the total amount of the urea, and the adding amount of the second batch of toughening agent accounts for 1-5% of the total amount of the urea.
2. The method for preparing the feather keratin-modified urea-formaldehyde resin as claimed in claim 1, wherein in step 1), the acidic solution is at least one of sulfuric acid, nitric acid, ammonium sulfate and ammonium nitrate, and the concentration of the acidic solution is 0.1 mol/L.
3. The method for preparing the feather keratin-modified urea-formaldehyde resin as claimed in claim 1, wherein in step 1), the mass ratio of the feathers to the urea solution is 1: 15 to 21 parts by weight.
4. The method for preparing the feather keratin-modified urea-formaldehyde resin as claimed in claim 1, wherein in step 1), L-cysteine is added in an amount of 5-15% by mass of the feathers.
5. The method of claim 1, wherein the feather keratin-modified urea-formaldehyde resin comprises at least one of chicken feather, duck feather, goose feather, and pigeon feather in step 1).
6. The method for preparing the feather keratin-modified urea-formaldehyde resin as claimed in claim 1, wherein in the step 2), the molar ratio of the added melamine to the added formaldehyde is 1: 2-3.
7. The method for preparing the feather keratin-modified urea-formaldehyde resin as claimed in claim 1, wherein in step 2), the toughening agent is at least one of polyvinyl alcohol, polyvinyl acetate emulsion and polyethylene glycol diglycidyl ether.
8. Use of a modified urea-formaldehyde resin obtained by the process according to any one of claims 1 to 7 for the preparation of straw pots.
9. The use of claim 8, wherein the straw pot is obtained by: crushing and drying the straws, adding modified urea-formaldehyde resin, ammonium chloride and paraffin, stirring for 30min at 30-60 ℃, injecting the mixture into a flowerpot forming die for hot pressing and forming, wherein the hydraulic pressure is 20-30 MPa, the hot pressing temperature is 110-160 ℃, and the hot pressing time is 30-60 s, so that the straw flowerpot is obtained.
10. The application of claim 9, wherein the mass ratio of the straw, the modified urea-formaldehyde resin, the ammonium chloride and the paraffin is 100: 50-70: 1-3: 3-6.
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| CN104745129A (en) * | 2015-04-20 | 2015-07-01 | 江苏省农业科学院 | Biodegradable modified urea resin adhesive and application thereof |
| CN106078947A (en) * | 2016-06-26 | 2016-11-09 | 周荣 | A kind of modified urea-formaldehyde resin glue plywood preparation method |
| CN108530829A (en) * | 2018-04-28 | 2018-09-14 | 芜湖市宝艺游乐科技设备有限公司 | A method of making straw flowerpot with cornstarch-soybean protein isolate modified urea-formaldehyde resin |
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| CN104745129A (en) * | 2015-04-20 | 2015-07-01 | 江苏省农业科学院 | Biodegradable modified urea resin adhesive and application thereof |
| CN106078947A (en) * | 2016-06-26 | 2016-11-09 | 周荣 | A kind of modified urea-formaldehyde resin glue plywood preparation method |
| CN108530829A (en) * | 2018-04-28 | 2018-09-14 | 芜湖市宝艺游乐科技设备有限公司 | A method of making straw flowerpot with cornstarch-soybean protein isolate modified urea-formaldehyde resin |
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