Preparation method and application of multifunctional bio-based waterborne polyurethane emulsion

Abstract

The invention discloses a preparation method and application of a multifunctional bio-based waterborne polyurethane emulsion, and relates to the field of paints.The preparation method comprises the steps that epoxidized soybean oil and ricinoleic acid are mixed, triphenylphosphine is added, and after heating and stirring reaction, epoxidized soybean oil polyol is obtained; the preparation method comprises the following steps: stirring epoxidized soybean oil polyol, bio-based dimer alcohol, polyisocyanate and a catalyst to react under the protection of nitrogen; adding a hydrophilic chain extender, a macromolecular chain extender and a silane coupling agent, sequentially reacting, and cooling to normal temperature; adding a neutralizing agent to continuously react to obtain a bio-based polyurethane prepolymer; and adding the bio-based polyurethane prepolymer into deionized water, and carrying out emulsification reaction at normal temperature to obtain the multifunctional bio-based waterborne polyurethane emulsion. According to the invention, different bio-based polyols are introduced to reduce the use of petroleum-based raw materials, and different properties of the cured film are obtained by adjusting the ratio of different polyols to polyisocyanates.

Description

Technical Field

[0001] The invention relates to the field of coatings, and in particular to a preparation method and application of a multifunctional bio-based waterborne polyurethane emulsion. Background Art

[0002] With the increasing emphasis on environmental protection and sustainable development, the use of traditional petroleum-based raw materials has put increasing pressure on the environment. Therefore, bio-based materials that replace traditional petrochemical products have received widespread attention. Polyurethane coatings are widely used due to their excellent mechanical properties and wide range of applications, but their traditional solvent-based polyurethane coatings may cause environmental pollution due to the use of solvents. In order to reduce the emission of volatile organic compounds (VOC) in coatings, water-based polyurethane has become an ideal choice to replace solvent-based coatings.

[0003] The preparation of bio-based waterborne polyurethane emulsions uses renewable resources such as bio-based polyols and natural vegetable oils, reduces dependence on petroleum resources, and has environmentally friendly characteristics such as low volatility and low toxicity. However, the existing technology still faces problems such as raw material selection, production process, and performance adjustment in the preparation process of bio-based waterborne polyurethane emulsions. It is urgent to provide a new method to improve its performance and make it more widely used in coatings. Summary of the invention

[0004] In view of this, the present invention aims to provide a preparation method and application of a multifunctional bio-based waterborne polyurethane emulsion, wherein the bio-based waterborne polyurethane emulsion is prepared by using epoxy soybean oil acrylate polyol, dimer and polyisocyanate as raw materials, and the use of petroleum-based raw materials can be reduced by introducing different bio-based polyols, and different properties of the cured film can be obtained by adjusting the ratio of different polyols to polyisocyanates; biomass macromolecular chain extenders (1,3-propylene glycol, 1,4-butanediol) are used to replace the use of organic solvents to reduce the release of VOCs, thereby reducing the use of petrochemical resources in waterborne polyurethane.

[0005] To achieve the above object, the present invention provides the following technical solutions:

[0006] In a first aspect, the present invention provides a method for preparing a multifunctional bio-based waterborne polyurethane emulsion, comprising the following steps:

[0007] Step S10, preparation of epoxy soybean oil polyol: mixing epoxy soybean oil and ricinoleic acid, adding triphenylphosphine, heating and stirring to react, to obtain epoxy soybean oil polyol;

[0008] Step S20, preparation of bio-based polyurethane prepolymer: stirring and reacting epoxy soybean oil polyol, bio-based dimer, polyisocyanate, and catalyst under nitrogen protection; adding hydrophilic chain extender, macromolecular chain extender, and silane coupling agent in sequence, reacting and cooling to room temperature; adding neutralizer and continuing reaction to obtain bio-based polyurethane prepolymer;

[0009] Step S30, emulsification reaction: adding the bio-based polyurethane prepolymer to deionized water to carry out an emulsification reaction at room temperature to obtain a multifunctional bio-based waterborne polyurethane emulsion.

[0010] As a further embodiment of the present invention, in step S10, the molar ratio of epoxidized soybean oil to ricinoleic acid is (1-3): (1-3), triphenylphosphine is used as a catalyst, accounting for 1-5% of the total mass of epoxidized soybean oil and ricinoleic acid; when heating and stirring the reaction, stirring is performed at 65-85° C. and the temperature is increased for reaction for 3-8 hours.

[0011] As a further embodiment of the present invention, the bio-based dimer alcohol is used as a raw material for synthesizing polyurethane, and the bio-based dimer alcohol is Priplast purchased from Cargill Company. TM 2030、Priplast TM 2033, Priplast TM 2043.

[0012] As a further embodiment of the present invention, the polyisocyanate includes isophorone diisocyanate (IPDI), toluene diisocyanate (TDI), hexamethylene diisocyanate (HDI), and diphenylmethane diisocyanate (MDI).

[0013] As a further embodiment of the present invention, in step S20, the catalyst is dibutyltin dilaurate, N,N-dimethylcyclohexylamine or organic bismuth; the epoxy soybean oil polyol, bio-based dimer, polyisocyanate and catalyst are stirred and reacted for 3-8 hours under nitrogen protection at a temperature of 65-85°C.

[0014] As a further embodiment of the present invention, in step S20, the hydrophilic chain extender is 2,2-dihydroxymethylpropionic acid DMPA or 2,2-dihydroxymethylbutyric acid DMABA, and after the reaction is continued at 65-85° C. for 1-5 hours, a macromolecular chain extender is added.

[0015] As a further embodiment of the present invention, in step S20, the macromolecular chain extender is 1,4-butanediol BDO and 1,3-propylene glycol PDO, the silane coupling agent is KH-550 coupling agent, the reaction is continued for 1-5 hours and then cooled to room temperature, the added neutralizing agent is triethanolamine, triethylamine or ethylenediamine, and the bio-based polyurethane prepolymer is obtained after the reaction for 0.5-3 hours.

[0016] As a further embodiment of the present invention, in step S30, the bio-based polyurethane prepolymer is subjected to an emulsification reaction at room temperature for 0.5-3 hours.

[0017] As a further embodiment of the present invention, in the raw materials for preparing the multifunctional bio-based waterborne polyurethane emulsion, the mass fraction of the epoxy soybean oil polyol is 10-80 parts, the mass fraction of the bio-based dimer is 1-50 parts, the mass fraction of the polyisocyanate is 30-50 parts, the mass fraction of the catalyst is 0.1-1 parts, the mass fraction of the hydrophilic chain extender is 1-10 parts, the mass fraction of the macromolecular chain extender is 1-10 parts, and the mass fraction of the silane coupling agent is 1-10 parts.

[0018] In a second aspect, the present invention further provides an application of a multifunctional bio-based waterborne polyurethane emulsion in a wood coating, wherein the wood coating comprises the following components in parts by weight:

[0019] 30-80 parts of multifunctional bio-based waterborne polyurethane emulsion; 0.5-1.5 parts of defoamer; 8-12 parts of color paste; 3-10 parts of curing agent;

[0020] The multifunctional bio-based waterborne polyurethane emulsion is prepared according to the above-mentioned preparation method of the multifunctional bio-based waterborne polyurethane emulsion.

[0021] Compared with the prior art, the preparation method and application of a multifunctional bio-based waterborne polyurethane emulsion of the present invention have the following beneficial effects:

[0022] The invention discloses a method for preparing a multifunctional bio-based waterborne polyurethane emulsion and an application thereof in a wood coating. The bio-based waterborne polyurethane emulsion is prepared by using epoxy soybean oil acrylate polyol, dimer and polyisocyanate as raw materials. The invention can reduce the use of petroleum-based raw materials by introducing different bio-based polyols, and obtain different properties of a cured film by adjusting the ratio of different polyols to polyisocyanates. Biomass macromolecular chain extenders (1,3-propylene glycol and 1,4-butanediol) are used to replace the use of organic solvents to reduce the release of VOCs, thereby reducing the use of petrochemical resources in waterborne polyurethane.

[0023] In order to more clearly illustrate the structural features and effects of the present invention, the present invention is described in detail below in conjunction with specific embodiments. DETAILED DESCRIPTION

[0024] The technical solution of the present invention is further described in detail below in conjunction with specific implementation methods.

[0025] Example 1

[0026] The present embodiment provides a method for preparing a multifunctional bio-based waterborne polyurethane emulsion, comprising the following steps:

[0027] (1) Preparation of epoxy soybean oil polyol: 16 g of epoxy soybean oil, 15 g of ricinoleic acid and 4 g of triphenylphosphine were mixed and stirred at 85° C. for 5 hours to form epoxy soybean oil polyol. After the reaction was completed, the mixture was cooled to room temperature and the reaction residue was removed by filtration to obtain epoxy soybean oil polyol.

[0028] (2) Synthesis of bio-based polyurethane prepolymer: 40 parts by weight of epoxy soybean oil polyol and 7 parts of bio-based dimer (Priplast TM 2030), 40 parts of isophorone diisocyanate, 1 part of dibutyltin dilaurate, mixed and stirred at 75°C for 4 hours to ensure that the isocyanate group is completely reacted; after the reaction is completed, cool to 75°C, add 8 parts of 2,2-dimethylolpropionic acid, and continue to stir and react for 2 hours. After the reaction is completed, cool to 70°C, add 3 parts of 1,4-butanediol and 1 part of KH-550 (silane coupling agent), and continue to react for 1 hour. After the reaction is completed, place it at room temperature, add triethylamine in an amount equimolar to 2,2-dimethylolpropionic acid for neutralization reaction, continue for 0.5 hours, and then cool. After completing the above steps, filter to remove impurities to obtain a bio-based polyurethane prepolymer.

[0029] (3) Preparation of emulsion: Take 50 g of bio-based polyurethane prepolymer, add 116 g of deionized water under high-speed stirring (1500-3000 rpm / min), and continue stirring and emulsifying for 1 hour until a stable multifunctional bio-based waterborne polyurethane emulsion is formed.

[0030] After the preparation of the above-mentioned multifunctional bio-based waterborne polyurethane emulsion is completed, the coating is prepared and applied: 10 parts of the multifunctional bio-based waterborne polyurethane emulsion are taken, 5 parts of the curing agent, 1.5 parts of the defoaming agent and 8 parts of the color paste are added, and stirred evenly; the coating is evenly applied on the surface of the polished wooden board using an applicator; the coated wooden board is placed in an oven at 40°C to dry until the surface is dry, and the coating is completed.

[0031] Example 2

[0032] The present embodiment provides a method for preparing a multifunctional bio-based waterborne polyurethane emulsion, comprising the following steps:

[0033] (1) Preparation of epoxidized soybean oil polyol: The preparation method of epoxidized soybean oil polyol is the same as that in Example 1.

[0034] (2) Synthesis of bio-based polyurethane prepolymer: 30 parts by weight of epoxy soybean oil polyol, 17 parts by weight of bio-based dimer (Priplast TM2033), 40 parts of toluene diisocyanate and 1 part of N,N-dimethylcyclohexylamine, mixed and stirred at 75°C for 4 hours to ensure that the isocyanate group is completely reacted. After the reaction is completed, cool to 75°C, add 8 parts of 2,2-dihydroxymethylbutyric acid, and continue to stir and react for 2 hours. After the reaction is completed, cool to 70°C, add 3 parts of 1,3-propylene glycol and 1 part of KH-550, and continue to react for 1 hour. After leaving to room temperature, add triethanolamine in an amount equimolar to 2,2-dihydroxymethylbutyric acid for neutralization reaction, which lasts for 0.5 hours, then cool and filter to remove impurities to obtain a bio-based polyurethane prepolymer.

[0035] (3) Preparation of emulsion: Take 50 g of bio-based polyurethane prepolymer, add 116 g of deionized water under high-speed stirring (1500-3000 rpm / min), and continue stirring and emulsifying for 1 hour to form a stable multifunctional bio-based waterborne polyurethane emulsion.

[0036] After the multifunctional bio-based waterborne polyurethane emulsion is prepared, the coating is prepared and applied: 10 parts of the multifunctional bio-based waterborne polyurethane emulsion are taken, 5 parts of curing agent, 1.5 parts of defoaming agent and 8 parts of color paste are added, and stirred evenly. The coating is evenly applied on the polished wooden surface using an applicator. The coated wooden board is placed in a 40°C oven for drying to complete the coating.

[0037] Example 3

[0038] The present embodiment provides a method for preparing a multifunctional bio-based waterborne polyurethane emulsion, comprising the following steps:

[0039] (1) Preparation of epoxidized soybean oil polyol: The preparation method of epoxidized soybean oil polyol is the same as that in Example 1.

[0040] (2) Synthesis of bio-based polyurethane prepolymer: By weight, 20 parts of epoxy soybean oil polyol, 27 parts of bio-based dimer (Priplast TM 2043), 40 parts of hexamethylene diisocyanate and 1 part of organic bismuth were mixed and stirred at 75°C for 4 hours, then cooled to 75°C, 8 parts of 2,2-dihydroxymethylbutyric acid were added and the reaction continued for 2 hours, then cooled to 70°C, 3 parts of 1,4-butanediol and 1 part of KH-550 were added, the reaction continued for 1 hour, and then allowed to stand at room temperature, and triethylamine in an amount equal to the molar amount of 2,2-dihydroxymethylbutyric acid was added for neutralization. After reacting for 0.5 hour, the material was cooled and filtered to obtain a bio-based polyurethane prepolymer.

[0041] (3) Preparation of emulsion: 50 g of bio-based polyurethane prepolymer was taken, and 116 g of deionized water was added under high-speed stirring (1500-3000 r / min) for emulsification for 1 h to obtain a multifunctional bio-based waterborne polyurethane emulsion.

[0042] After the preparation of the above-mentioned multifunctional bio-based waterborne polyurethane emulsion is completed, the coating is prepared and applied: 10 parts of multifunctional bio-based waterborne polyurethane emulsion, 5 parts of curing agent, 1.5 parts of defoaming agent and 8 parts of color paste are mixed evenly, and it is evenly applied on the polished wooden board with an applicator, and then placed in a 40°C oven for drying.

[0043] Example 4

[0044] The present embodiment provides a method for preparing a multifunctional bio-based waterborne polyurethane emulsion, comprising the following steps and process conditions:

[0045] (1) Preparation of epoxidized soybean oil polyol: The preparation method of epoxidized soybean oil polyol is the same as that in Example 1.

[0046] (2) Synthesis of bio-based polyurethane prepolymer: By weight, 10 parts of epoxy soybean oil polyol, 37 parts of bio-based dimer (Priplast TM 2030), 40 parts of diphenylmethane diisocyanate and 1 part of dibutyltin dilaurate are mixed and stirred at 75°C for 4 hours, then cooled to 75°C, 8 parts of 2,2-dihydroxymethylbutyric acid are added, and the reaction is continued for 2 hours. Then, the temperature is cooled to 70°C, 3 parts of 1,4-butanediol and 1 part of KH-550 are added, and the reaction is continued for 1 hour. After being allowed to stand at room temperature, triethylamine in an amount equal to the molar amount of 2,2-dihydroxymethylbutyric acid is added for neutralization. After reacting for 0.5 hours, the material is cooled and filtered to obtain a bio-based polyurethane prepolymer.

[0047] (3) Preparation of emulsion: 50 g of bio-based polyurethane prepolymer was taken, and 116 g of deionized water was added under high-speed stirring (1500-3000 r / min) for emulsification for 1 h to obtain a multifunctional bio-based waterborne polyurethane emulsion.

[0048] After the preparation of the above-mentioned multifunctional bio-based waterborne polyurethane emulsion is completed, the coating is prepared and applied: 10 parts of multifunctional bio-based waterborne polyurethane emulsion, 5 parts of curing agent, 1.5 parts of defoaming agent and 8 parts of color paste are mixed evenly, and it is evenly applied on the polished wooden board with an applicator, and then placed in a 40°C oven for drying.

[0049] Example 5

[0050] A method for preparing a multifunctional bio-based waterborne polyurethane emulsion, comprising the following steps and process conditions

[0051] (1) Preparation of epoxidized soybean oil polyol: The preparation method of epoxidized soybean oil polyol is the same as that in Example 1.

[0052] (2) Synthesis of bio-based polyurethane prepolymer: 47 parts by weight of bio-based dimer (PriplastTM 2030), 40 parts of isophorone diisocyanate and 1 part of dibutyltin dilaurate are mixed and stirred at 75°C for 4 hours, then cooled to 75°C, 8 parts of 2,2-dihydroxymethylbutyric acid are added and the reaction is continued for 2 hours, then cooled to 70°C, 3 parts of 1,4-butanediol and 1 part of KH-550 are added, the reaction is continued for 1 hour, and then allowed to stand at room temperature, and ethylenediamine in an amount equal to the molar amount of 2,2-dihydroxymethylbutyric acid is added for neutralization reaction for 0.5 hours, and the material is cooled and filtered to obtain a bio-based polyurethane prepolymer.

[0053] (3) Preparation of emulsion: 50 g of bio-based polyurethane prepolymer was taken, and 116 g of deionized water was added under high-speed stirring (1500-3000 r / min) for emulsification for 1 h to obtain a multifunctional bio-based waterborne polyurethane emulsion.

[0054] After the preparation of the above-mentioned multifunctional bio-based waterborne polyurethane emulsion is completed, the coating is prepared and applied: 10 parts of multifunctional bio-based waterborne polyurethane emulsion, 5 parts of curing agent, 1.5 parts of defoaming agent and 8 parts of color paste are mixed evenly, and it is evenly applied on the polished wooden board with an applicator, and then placed in a 40°C oven for drying.

[0055] Performance Test:

[0056] The multifunctional bio-based waterborne polyurethane emulsions prepared in Examples 1-5 were tested for pencil hardness, adhesion, water absorption, glossiness, and pencil hardness. The test methods are:

[0057] Pencil hardness: Pencil hardness, also known as the pencil hardness determination method for coating hardness. It is a test method and measurement system for calibrating coating hardness. According to industrial standards, the hardness of pencil leads is divided into 13 levels. From the hardest 6H, it gradually decreases through 5H, 4H, 3H, 2H, H, then through HB with moderate hardness, and then from B, 2B to the softest 6B. Among them, H represents hardness and B represents blackness.

[0058] 1) Place the test piece upward and fix it, and scratch it with a pencil at a 45° angle to the test piece. Do not break the lead, and scratch about 1 cm in front of the tester at a constant speed. The scratching speed is 1mm / s. After scratching once, the tip of the lead should be re-grinded, and the test should be repeated 5 times with a pencil of the same hardness mark.

[0059] 2) When evaluating by observing the damage of the coating, if the substrate or primer coating is visible in only 2 or less tests out of 5, a pencil with a larger hardness mark should be used to conduct the same test. When the coating is damaged more than 2 times (for every 5 tests), the hardness mark of the pencil at this time can be read, and the hardness mark next to this pencil hardness mark can be recorded.

[0060] Adhesion test: Standard GB / T9286-2021 / ISO2409:2020 "Scratch test for paints and varnishes".

[0061] Water resistance test: GBT1733-1993 "Determination of water resistance of paint films".

[0062] Gloss: Directly tested using a gloss instrument.

[0063] The test results of pencil hardness, adhesion test, water absorption test, glossiness and pencil hardness of the multifunctional bio-based waterborne polyurethane emulsion prepared in Examples 1-5 are shown in Table 1:

[0064] Table 1 Test results of multifunctional bio-based waterborne polyurethane emulsion

[0065]

[0066] Test results: The multifunctional bio-based waterborne polyurethane emulsions prepared in Examples 1-5 are prepared using epoxy soybean oil acrylate polyols, dimer and polyisocyanates as raw materials. The present invention can reduce the use of petroleum-based raw materials by introducing different bio-based polyols, and obtain different properties of the cured film by adjusting the ratio of different polyols to polyisocyanates; biomass macromolecular chain extenders (1,3-propylene glycol, 1,4-butanediol) are used to replace the use of organic solvents to reduce the release of VOCs, thereby reducing the use of petrochemical resources in waterborne polyurethanes.

[0067] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited to the above embodiments. Various changes can be made within the knowledge scope of ordinary technicians in this field without departing from the purpose of the present invention.

Claims

1. A method for preparing a multifunctional bio-based waterborne polyurethane emulsion, characterized in that: The following steps are involved: Step S10, preparation of epoxy soybean oil polyol: mixing epoxy soybean oil with ricinoleic acid, adding triphenylphosphine, heating and stirring to react, and obtaining epoxy soybean oil polyol; Step S20, preparation of bio-based polyurethane prepolymer: stirring and reacting epoxy soybean oil polyol, bio-based dimer, polyisocyanate, and catalyst under nitrogen protection; adding hydrophilic chain extender, macromolecular chain extender, and silane coupling agent in sequence, reacting and cooling to room temperature; adding neutralizer and continuing reaction to obtain bio-based polyurethane prepolymer; Step S30, emulsification reaction: adding the bio-based polyurethane prepolymer to deionized water to carry out an emulsification reaction at room temperature to obtain a multifunctional bio-based waterborne polyurethane emulsion.

2. The method for preparing a multifunctional bio-based aqueous polyurethane emulsion according to claim 1, characterized in that: In step S10, the molar ratio of epoxidized soybean oil to ricinoleic acid is (1-3): (1-3), triphenylphosphine is used as a catalyst, accounting for 1-5% of the total mass of the epoxidized soybean oil and ricinoleic acid; when heating and stirring the reaction, stirring is performed at 65-85° C. and the temperature is increased for 3-8 hours.

3. The method for preparing a multifunctional bio-based aqueous polyurethane emulsion according to claim 1, characterized in that: The bio-based dimer alcohol is used as a raw material for synthesizing polyurethane. The bio-based dimer alcohol is Priplast TM 2030、Priplast TM 2033, Priplast TM 2043.

4. The method for preparing a multifunctional bio-based aqueous polyurethane emulsion according to claim 3, characterized in that: The polyisocyanate includes isophorone diisocyanate, toluene diisocyanate, hexamethylene diisocyanate, and diphenylmethane diisocyanate.

5. The method for preparing a multifunctional bio-based waterborne polyurethane emulsion according to claim 1, characterized in that: In step S20, the catalyst is dibutyltin dilaurate, N,N-dimethylcyclohexylamine or organic bismuth; epoxy soybean oil polyol, bio-based dimer, polyisocyanate and catalyst are stirred and reacted for 3-8 hours under nitrogen protection at a temperature of 65-85°C.

6. The method for preparing a multifunctional bio-based aqueous polyurethane emulsion according to claim 5, characterized in that: In step S20, the hydrophilic chain extender is 2,2-dihydroxymethylpropionic acid DMPA or 2,2-dihydroxymethylbutyric acid DMABA. After the reaction is continued at 65-85° C. for 1-5 hours, the macromolecular chain extender is added.

7. The method for preparing a multifunctional bio-based waterborne polyurethane emulsion according to claim 6, characterized in that: In step S20, the macromolecular chain extender is 1,4-butanediol BDO and 1,3-propylene glycol PDO, the silane coupling agent is KH-550 coupling agent, the reaction is continued for 1-5 hours and then cooled to room temperature, the added neutralizing agent is triethanolamine, triethylamine or ethylenediamine, and the bio-based polyurethane prepolymer is obtained after the reaction for 0.5-3 hours.

8. The method for preparing a multifunctional bio-based waterborne polyurethane emulsion according to claim 1, characterized in that: In step S30, the bio-based polyurethane prepolymer is subjected to an emulsification reaction at room temperature for 0.5-3 hours.

9. The method for preparing a multifunctional bio-based waterborne polyurethane emulsion according to claim 1, characterized in that: In the raw materials for preparing the multifunctional bio-based waterborne polyurethane emulsion, the mass fraction of the epoxy soybean oil polyol is 10-80 parts, the mass fraction of the bio-based dimer is 1-50 parts, the mass fraction of the polyisocyanate is 30-50 parts, the mass fraction of the catalyst is 0.1-1 parts, the mass fraction of the hydrophilic chain extender is 1-10 parts, the mass fraction of the macromolecular chain extender is 1-10 parts, and the mass fraction of the silane coupling agent is 1-10 parts.

10. Application of a multifunctional bio-based waterborne polyurethane emulsion in wood coatings, characterized in that: The wood coating comprises the following components by weight: 30-80 parts of multifunctional bio-based waterborne polyurethane emulsion; 0.5-1.5 parts of defoamer; 8-12 parts of color paste; 3-10 parts of curing agent; Wherein, the multifunctional bio-based waterborne polyurethane emulsion is prepared by the preparation method of the multifunctional bio-based waterborne polyurethane emulsion according to any one of claims 1-9.

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