An environmentally friendly bio-based polyurethane reaction injection molding composition and a method of making the same

Abstract

This invention discloses an environmentally friendly bio-based polyurethane reaction injection molding composition and its preparation method. The environmentally friendly bio-based polyurethane reaction injection molding composition comprises, by mass fraction: Component A: 60-90% modified polyol, 3-10% autocatalytic chain extender, 4-15% alcohol chain extender and / or alkanolamine chain extender, 1-8% carbon black, 1-5% anti-aging agent, and 0.05-2% composite catalyst; Component B: 60-90% diphenylmethane diisocyanate or 4,4'-dicyclohexylmethane diisocyanate, 10-40% jojoba oil polyol; isocyanate (NCO) content 16%-30%; the modified polyol includes 500-1000 parts by weight of polyether polyol, 40-70 parts by weight of jojoba oil polyol, and 25 parts by weight of isocyanate. The prepared composition can shorten the demolding time by 10-25% while keeping the gel time constant, which can meet the requirements of rapid injection and demolding. At the same time, it shortens the production cycle and improves production efficiency. Its performance is comparable to that of existing technologies, and it enables renewable bio-based polyols to partially replace petrochemical-derived polyols.

Description

TECHNICAL FIELD

[0001] The present application relates to a polyurethane reaction injection molding (RIM) material and process, in particular to an environmentally friendly bio-based polyurethane reaction injection molding composition and a preparation method thereof. BACKGROUND

[0002] The raw materials of polyurethane, oligomeric polyols and polyisocyanates, are mostly derived from non-renewable fossil resources, and the large consumption of fossil resources has led to energy crisis and environmental pollution. Finding renewable raw materials to replace traditional raw materials has become an inevitable trend and urgent requirement for the development of polyurethane material technology. Bio-based polyols prepared from plant oils, bio-fermentation products and other plant and animal extracts are a relatively widely used bio-based polyurethane material technology.

[0003] Patent document CN109642046A obtains a bio-based hybrid polyol containing natural oil by copolymerizing or grafting a traditional polyester polyol onto a natural oil polyol, thereby improving the bio-renewable content of the product. However, the hybrid polyol prepared by the copolyester method has problems such as long process route, high equipment requirements, poor hydrolysis resistance, etc.

[0004] Patent document CN113717372A discloses a preparation method of a modified polyether polyol. Epoxy soybean oil reacts with alcohol amine under the action of an alkaline catalyst to undergo ring-opening reaction to obtain modified epoxy soybean oil; a composite initiator and an epoxy olefin compound are added to react to obtain a plant-based raw material modified polyether polyol. Patent document CN113858376A discloses a preparation method of a fluorine-containing soybean oil polyol. The fluorine-containing plant oil polyol is prepared by reacting epoxy plant oil and a strong acid cation exchange resin. The above-mentioned method of preparing a bio-based polyol by epoxy ring-opening requires first modifying the plant oil by epoxidation, which has a long technical route. In addition, due to the low content of primary hydroxyl groups in the bio-based polyol, the activity is too low for application in reaction injection molding process, and the curing is slow, which cannot achieve rapid demolding within 1 min, and post-curing is required after demolding, which does not meet the requirements of actual application.

[0005] CN107189028A discloses an environmentally friendly, high-performance, fast-release polyurethane reactive injection molding composition and its preparation method with a self-catalytic chain extender. This reduces catalyst usage, improves environmental friendliness, and achieves a faster reaction rate. However, this composition does not contain bio-based polyols. Directly adding bio-based polyols to the composition, either wholly or partially replacing the original bio-based polyols, leads to problems such as demolding deformation, low material performance, and poor aging resistance due to differences in activity and incoordination between different types of polyols. This necessitates significantly increasing the demolding time to ensure complete material reaction. However, in the industrial application of PU-RIM materials, production cycles are extremely tight, and the length of the demolding time directly affects production efficiency. Therefore, extending the demolding time is unacceptable to manufacturers. Summary of the Invention

[0006] To address the problems existing in the prior art, this invention provides a bio-based polyurethane composition and its preparation method. The method involves hydroxylating vegetable oil via a thiol-olefin coupling method, and then introducing the hydroxylated vegetable oil into the composition through urethane modification. The polymerization rate is optimized using a composite catalyst and a self-catalytic chain extender. The prepared composition can shorten the demolding time by 10-25% while maintaining the same gel time, meeting the requirements for rapid injection and demolding. This also shortens the production cycle and improves production efficiency. The prepared material exhibits hardness, density, tensile strength, and tear strength comparable to existing technologies, allowing renewable bio-based polyols to partially replace petrochemical-derived polyols.

[0007] The first aspect of this invention provides an environmentally friendly bio-based polyurethane reaction injection molding composition, comprising the following components by mass fraction:

[0008] Component A: 60-90% modified polyol, 3-10% autocatalytic chain extender, 4-15% alcohol chain extender and / or alkanolamine chain extender, 1-8% carbon black, 1-5% anti-aging agent, and 0.05-2% composite catalyst;

[0009] Component B: 60-90% diphenylmethane diisocyanate or 4,4'-dicyclohexylmethane diisocyanate, 10-40% jojoba oil polyol; isocyanate (NCO) content 16%-30%;

[0010] The modified polyol comprises 500-1000 parts by weight of polyether polyol, 40-70 parts by weight of jojoba oil polyol, and 25 parts by weight of isocyanate. The modified polyol is prepared by reacting jojoba oil polyol, polyether polyol, and isocyanate. The preparation method of the modified polyol includes: weighing a certain amount of jojoba oil polyol and isocyanate into a reaction vessel, stirring and controlling the reaction temperature at 85±5℃, reacting for 100-120 min, then adding the polyether polyol, controlling the reaction temperature at 80±5℃ and continuing the reaction for another 100-120 min, cooling to room temperature and discharging. The polyether polyol is preferably one or more of ethylene oxide-propylene oxide copolyether triols with a primary hydroxyl content >70% and a number average molecular weight of 3000-5000. The isocyanate is one or more of diphenylmethane diisocyanate (MDI), 4,4-dicyclohexylmethane diisocyanate, and isophthalic dimethyl isocyanate (XDI).

[0011] The preparation method of the jojoba oil polyol is as follows: jojoba oil, 2-mercaptoethanol, initiator 1173, and azobisisobutyronitrile (AIBN) are weighed into a reaction vessel, stirred, and the reaction temperature is controlled at 58-62℃. The reaction is carried out under ultraviolet light irradiation for 2-2.5 hours, followed by post-treatment to obtain the jojoba oil polyol. The preferred post-treatment step is: dissolving the product with dichloromethane, washing the product with sodium chloride solution, drying and filtering with anhydrous magnesium sulfate, and removing the organic solvent using a rotary evaporator to obtain the jojoba oil polyol. In the preparation method of the jojoba oil polyol, the proportions are: 600-800 parts by weight of jojoba oil, 280-320 parts by weight of 2-mercaptoethanol, 1-2 parts by weight of initiator 1173, and 3-4 parts by weight of azobisisobutyronitrile (AIBN).

[0012] The preferred alcohol chain extender and / or alkanolamine chain extender is one or more of ethylene glycol, 1,4-butanediol, 1,3-butanediol, diethylene glycol, and diethanolamine.

[0013] The autocatalytic chain extender is prepared by alkoxylation reaction of piperazine and epoxide, with a molar ratio of piperazine to epoxide of 1:2-10. A preferred preparation method for the autocatalytic chain extender is as follows: anhydrous piperazine is heated to 60-65°C in a reaction vessel equipped with a reflux condenser. While maintaining a constant temperature, epoxide is slowly added dropwise to the reaction vessel according to the specified molar ratio. After the addition is complete, the temperature is raised to 80-85°C and the reaction continues for 5-6 hours. The mixture is then cooled to room temperature and discharged. Compared to ethylene oxide and propylene oxide, epoxide exhibits greater steric hindrance due to the presence of the ethyl group in its structure, resulting in more stable autocatalytic activity and better activity matching with plant oil polyols. The reaction formula is:

[0014]

[0015] Where n = 1 to 5.

[0016] The composite catalyst is directly composed of bismuth neodecanoate, zinc isooctanoate, bicycloamidine and glycerol without adding solvent, wherein 10 parts of bismuth neodecanoate, 2-6 parts of zinc isooctanoate, 4-8 parts of bicycloamidine and 10 parts of glycerol.

[0017] The anti-aging agent includes one or more of 2-(2ˊ-hydroxy-3ˊ,5ˊ-di-tert-butylphenyl)-5-chlorobenzotriazole, 2-(2ˊ-hydroxy-5ˊ-methylphenyl)benzotriazole, 2-hydroxy-4-n-octyloxybenzophenone, bis(3,5-tert-butyl-4-hydroxyphenyl) sulfide, bis(1,2,2,6,6-pentamethyl-4-piperidinyl) sebacate, and trioctyl phosphite.

[0018] A second aspect of this invention provides a method for preparing an environmentally friendly bio-based polyurethane reactive injection molding composition, comprising the following steps:

[0019] (1) Component A: Add the modified polyol, autocatalytic chain extender, alcohol chain extender and / or alcohol amine chain extender, composite catalyst, carbon black and anti-aging agent into the reaction vessel and mix evenly;

[0020] (2) Component B: Diphenylmethane diisocyanate or 4,4'-dicyclohexylmethane diisocyanate and jojoba oil are added to the reaction vessel at the same time, heated with stirring and the temperature is controlled at 85±5℃, reacted for 2 to 3 hours, and then cooled to room temperature before being discharged.

[0021] The compositions of the present invention have the following advantages over the prior art:

[0022] (1) Bio-based polyols are introduced into components A and B of the composition, partially replacing petroleum-based polyols, which meets the requirements of the RIM process while improving the environmental sustainability of the materials. Jojoba oil polyols are introduced into the polyol components through urethane modification, which solves the problems of uncoordinated reactions and poor hydrolysis resistance of copolymer grafting in the prior art. The modified polyols of the present invention have low unsaturation, and the polyurethane materials prepared have better water resistance and aging resistance.

[0023] (2) Jojoba oil was modified by thiol-olefin coupling method. By adding 1173 initiator, a bio-based polyol with low unsaturation of two functionalities was obtained by using a shorter process route.

[0024] (3) By synergistic effect of self-catalytic chain extender and composite catalyst, the problem of low reactivity of bio-based polyols is solved. The composition of the present invention has high reactivity, the demolding time can be shortened by 10-25%, no post-curing is required, and the production efficiency of users can be improved.

[0025] (4) By using urethane modification, composite catalyst and self-catalytic chain extender in combination, the reaction activity of the feed liquid is enhanced, which solves the problems of low reaction activity and poor mechanical properties of bio-based polyols and meets the requirements of rapid production of RIM products. Detailed Implementation

[0026] The present invention will be further illustrated by specific implementation examples below, where the numbers mentioned below refer to parts by weight.

[0027] The raw materials used in Examples 1-2 and Comparative Examples 3-4 are as follows:

[0028] Synthesis of jojoba oil polyol: 700 parts of jojoba oil, 300 parts of 2-mercaptoethanol, 1 part of 1173 initiator, and 4 parts of azobisisobutyronitrile (AIBN) were weighed into a reaction vessel. The mixture was stirred and the reaction temperature was controlled at 60±2℃. The reaction was carried out under ultraviolet light for 2 hours. The product was dissolved in dichloromethane, washed with sodium chloride solution, dried with anhydrous magnesium sulfate, and filtered. Finally, the organic solvent was removed by rotary evaporation to obtain jojoba oil polyol with a hydroxyl value of 130 mgKOH / g.

[0029] Synthesis of modified polyol: Weigh 43 parts of jojoba oil polyol and 25 parts of MDI into a reaction vessel, stir and control the reaction temperature at 85±5℃. After reacting for 2 hours, add 600 parts of EP-551C (ethylene oxide-propylene oxide copolyether triol, hydroxyl value 33.5~36.5mgKOH / g), control the reaction temperature at 80±5℃ and continue the reaction for 2 hours. Cool to room temperature and discharge to obtain the self-made modified polyol.

[0030] Synthesis of autocatalytic chain extenders: Anhydrous piperazine was heated to 65°C in a reaction vessel equipped with a reflux condenser. While maintaining a constant temperature, the starting materials were added according to the molar ratio n... 哌嗪 :n 环氧丁烷 The solution was added dropwise to the reaction vessel at a ratio of 1:2. After the addition was complete, the temperature was raised to 80-85℃ and the reaction was continued for 4 hours. After cooling to room temperature, the product was discharged. The structure of the reaction and the obtained product is shown in the figure below:

[0031]

[0032] Preparation of composite catalyst: 10 parts bismuth neodecanoate, 4 parts zinc isooctanoate, 4 parts bicycloamidine, and 10 parts glycerol are thoroughly mixed and set aside for use.

[0033] Example 1

[0034] Component A: 84.0 parts modified polyol, 8.6 parts autocatalytic chain extender, 4.3 parts ethylene glycol, 1 part carbon black, 0.6 parts 2-(2'-hydroxy-5'-methylphenyl)benzotriazole, 0.4 parts bis(1,2,2,6,6-pentamethyl-4-piperidinyl) sebacate, 1.1 parts composite catalyst;

[0035] Component B: Diphenylmethane diisocyanate, 80.4 parts; Jojoba oil polyol, 19.6 parts. NCO mass fraction: 25.0%.

[0036] The process for preparing PU-RIM material from components A and B using a high-pressure injection molding machine is as follows:

[0037] ① Adding: Add component A to tank A of the high-pressure machine, and add component B of the composition to tank B;

[0038] ②Injection: Set the material temperature to 30~45℃ for component A and 30~45℃ for component B, with an A / B mixing ratio of 100:50±2, and an injection pressure of 14±1MPa. Inject into a mold that has been heated to 110~120℃.

[0039] ③ Demolding: Demold 30 seconds after injection; if cracking or deformation occurs during the 30-second demolding period, extend the demolding time.

[0040] Example 2

[0041] Component A: 83.1 parts modified polyol, 8.2 parts autocatalytic chain extender, 4.7 parts ethylene glycol, 1.0 part carbon black, 0.7 parts 2-(2ˊ-hydroxy-3ˊ,5ˊ-di-tert-butylphenyl)-5-chlorobenzotriazole, 0.3 parts bis(3,5-tritert-butyl-4-hydroxyphenyl) sulfide, and 2.0 parts composite catalyst;

[0042] Component B: 83.5 parts of 4,4'-dicyclohexylmethane diisocyanate and 16.5 parts of jojoba oil polyol. NCO mass fraction: 25.0%.

[0043] The process for preparing PU-RIM material from components A and B using a high-pressure injection molding machine is the same as in Example 1.

[0044] Comparative Example 1

[0045] The composition adopts the formulation of the embodiment in the comparative patent CN107189028A, and the material manufacturing process is the same as that in Example 1 of the present invention.

[0046] Comparative Example 2

[0047] The composition is based on the formulation of comparative patent CN107189028A, with the addition of commercially available soybean oil polyol SD-250 (Shanghai Zhongke Hechen Co., Ltd., hydroxyl value 250±20mgKOH / g) to partially replace the traditional polyol. The material manufacturing process is the same as in Example 1 of this invention. The components are as follows:

[0048] Component A: 330N, 67.5 parts; SD-250, 10 parts; self-made chain extender (patent CN107189028A), 8 parts; ethylene glycol, 4 parts; trimethylolpropane, 8 parts; carbon black, 0.5 parts; 2-(2'-hydroxy-5'-methylphenyl)benzotriazole, 0.6 parts; bis(3,5-tributyl-4-hydroxyphenyl) sulfide, 0.4 parts; composite catalyst, 1 part.

[0049] Component B: 83.8 parts of 4,4'-dicyclohexylmethane diisocyanate, 16.2 parts of SD-250. NCO mass fraction is 25.0%.

[0050] Comparative Example 3

[0051] The modified polyol in Example 1 of this invention was replaced with jojoba oil polyol and EP-551C, and the material preparation process was the same as in Example 1 of this invention. The composition is as follows:

[0052] Component A: 5.4 parts jojoba oil polyol, 75.8 parts EP-551C, 8.6 parts autocatalytic chain extender, 4.3 parts ethylene glycol, 1 part carbon black, 0.6 parts 2-(2'-hydroxy-5'-methylphenyl)benzotriazole, 0.4 parts bis(1,2,2,6,6-pentamethyl-4-piperidinyl) sebacate, and 1.1 parts composite catalyst;

[0053] Component B: 80.4 parts diphenylmethane diisocyanate, 19.6 parts jojoba oil polyol. NCO mass fraction is 25.0%.

[0054] Comparative Example 4

[0055] The composite catalyst consists of 10 parts bismuth isooctanoate, 4 parts potassium isooctanoate, 4 parts DBU, and 10 parts glycerol. The rest is the same as in Example 1.

[0056] Comparative Example 5

[0057] Synthesis of jojoba oil polyol: 700 parts of jojoba oil, 300 parts of 2-mercaptoethanol, and 5 parts of azobisisobutyronitrile (AIBN) were weighed into a reaction vessel. The mixture was stirred and the reaction temperature was controlled at 60±2℃. The reaction was carried out under ultraviolet light for 2 hours. The product was dissolved in dichloromethane, washed with sodium chloride solution, dried with anhydrous magnesium sulfate, and filtered. Finally, the organic solvent was removed by rotary evaporation to obtain the jojoba oil polyol. The hydroxyl value was 66.5 mgKOH / g, which differed significantly from the theoretical value, indicating incomplete reaction.

[0058] The test results for the examples and comparative examples are shown in the table below:

[0059] Example 1 Example 2 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Gel time / (s) 8 10 8 10 10 8 Demoulding time / (s) 30 35 40 60 60 45 State of the sample after demoulding Good initial strength, flexibility, high gloss of the cross section Good initial strength, flexibility, high gloss of the cross section Good initial strength, flexibility, high gloss of the cross section Poor initial strength, tacky, low gloss of the cross section Poor initial strength, tacky, delamination of the cross section Good initial strength, flexibility, low gloss of the cross section Density GB / T 1033 / (g / cm 3 )]]> 1.02 1.01 1.02 1.00 0.98 1.00 Hardness GB / T 2411 / (Shore A) 90 90 87 85 86 88 Tensile strength GB / T 528 / (MPa) 13.1 12.3 12.0 7.8 6.4 10.9 Tear strength GB / T 529 / (N / mm) 36.6 35.0 37.5 22.6 20.2 33.5 Hardness after 48h boiling in water at 100°C 87 89 82 80 80 86 Colour difference (ΔΕ) after xenon light accelerated ageing (SAE J2527) 500h 1.2 0.8 2.5 3.8 2.3 3.0

[0060] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. An environmentally friendly bio-based polyurethane reactive injection molding composition, comprising, by mass fraction: Component A: 60-90% modified polyol, 3-10% autocatalytic chain extender, 4-15% alcohol chain extender and / or alkanolamine chain extender, 1-8% carbon black, 1-5% anti-aging agent, and 0.05-2% composite catalyst; Component B: 60-90% diphenylmethane diisocyanate or 4,4'-dicyclohexylmethane diisocyanate, 10-40% jojoba oil polyol; isocyanate (NCO) content 16%-30%; The modified polyol comprises 500-1000 parts by weight of polyether polyol, 40-70 parts by weight of jojoba oil polyol, and 25 parts by weight of isocyanate. The preparation method of the jojoba oil polyol is as follows: weigh jojoba oil, 2-mercaptoethanol, initiator 1173 and azobisisobutyronitrile (AIBN) into a reaction vessel, stir and control the reaction temperature at 58~62℃, react under ultraviolet light for 2~2.5h, and obtain jojoba oil polyol after post-treatment. The composite catalyst is composed of bismuth neodecanoate, zinc isooctanoate, bicycloamidine, and glycerol.

2. The environmentally friendly bio-based polyurethane reaction injection molding composition according to claim 1, characterized in that, The modified polyol is prepared by reacting jojoba oil polyol, polyether polyol and isocyanate.

3. The environmentally friendly bio-based polyurethane reaction injection molding composition according to claim 1, characterized in that, The polyether polyol is one or more of ethylene oxide-propylene oxide copolyether triols with a primary hydroxyl content >70% and a number average molecular weight of 3000-5000.

4. The environmentally friendly bio-based polyurethane reaction injection molding composition according to claim 1, characterized in that, The isocyanate is one or more of diphenylmethane diisocyanate (MDI), 4,4-dicyclohexylmethane diisocyanate, and isophthalic dimethyl isocyanate (XDI).

5. The environmentally friendly bio-based polyurethane reaction injection molding composition according to claim 1, characterized in that, The alcohol chain extender and / or alcohol amine chain extender is one or more of ethylene glycol, 1,4-butanediol, 1,3-butanediol, diethylene glycol, and diethanolamine.

6. The environmentally friendly bio-based polyurethane reaction injection molding composition according to claim 1, characterized in that, The autocatalytic chain extender is prepared by alkoxylation reaction of piperazine and epoxide butane.

7. The environmentally friendly bio-based polyurethane reaction injection molding composition according to claim 6, characterized in that, The molar ratio of piperazine to epoxide is 1:2-10.

8. The environmentally friendly bio-based polyurethane reactive injection molding composition according to claim 1, characterized in that, The composite catalyst consists of 10 parts bismuth neodecanoate, 2-6 parts zinc isooctanoate, 4-8 parts bicycloamidinium, and 10 parts glycerol.

9. The environmentally friendly bio-based polyurethane reaction injection molding composition according to claim 1, characterized in that, The anti-aging agent is one or more of 2-(2ˊ-hydroxy-3ˊ,5ˊ-di-tert-butylphenyl)-5-chlorobenzotriazole, 2-(2ˊ-hydroxy-5ˊ-methylphenyl)benzotriazole, 2-hydroxy-4-n-octyloxybenzophenone, bis(3,5-tert-butyl-4-hydroxyphenyl) sulfide, bis(1,2,2,6,6-pentamethyl-4-piperidinyl) sebacate, and trioctyl phosphite.

10. A method for preparing the environmentally friendly bio-based polyurethane reaction injection molding composition according to any one of claims 1-9, comprising the following steps: (1) Component A: Add the modified polyol, autocatalytic chain extender, alcohol chain extender and / or alkanolamine chain extender, composite catalyst, carbon black and anti-aging agent into the reaction vessel and mix evenly; (2) Component B: Diphenylmethane diisocyanate or 4,4'-dicyclohexylmethane diisocyanate and jojoba oil polyol are added to the reaction vessel, heated with stirring and the temperature is controlled at 85±5℃, reacted for 2-3 hours, and then cooled to room temperature before being discharged.

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