CN117757106A - Lignin-based photoinitiator, preparation method thereof and application thereof in elastomer - Google Patents
Lignin-based photoinitiator, preparation method thereof and application thereof in elastomer Download PDFInfo
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- CN117757106A CN117757106A CN202311781960.1A CN202311781960A CN117757106A CN 117757106 A CN117757106 A CN 117757106A CN 202311781960 A CN202311781960 A CN 202311781960A CN 117757106 A CN117757106 A CN 117757106A
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- Prior art keywords
- lignin
- photoinitiator
- solvent
- elastomer
- based photoinitiator
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- 229920005610 lignin Polymers 0.000 title claims abstract description 182
- 229920001971 elastomer Polymers 0.000 title claims abstract description 52
- 239000000806 elastomer Substances 0.000 title claims abstract description 52
- 238000002360 preparation method Methods 0.000 title claims abstract description 28
- WFDIJRYMOXRFFG-UHFFFAOYSA-N Acetic anhydride Chemical compound CC(=O)OC(C)=O WFDIJRYMOXRFFG-UHFFFAOYSA-N 0.000 claims abstract description 119
- 239000000178 monomer Substances 0.000 claims abstract description 25
- -1 2-bromoisobutyl acyl bromide Chemical class 0.000 claims abstract description 23
- 238000005886 esterification reaction Methods 0.000 claims abstract description 18
- 239000002904 solvent Substances 0.000 claims abstract description 14
- 239000003153 chemical reaction reagent Substances 0.000 claims abstract description 13
- 230000032050 esterification Effects 0.000 claims abstract description 11
- WAKFRZBXTKUFIW-UHFFFAOYSA-N 2-bromo-2-phenylacetic acid Chemical compound OC(=O)C(Br)C1=CC=CC=C1 WAKFRZBXTKUFIW-UHFFFAOYSA-N 0.000 claims abstract description 9
- DVECBJCOGJRVPX-UHFFFAOYSA-N butyryl chloride Chemical compound CCCC(Cl)=O DVECBJCOGJRVPX-UHFFFAOYSA-N 0.000 claims abstract description 9
- 150000002148 esters Chemical class 0.000 claims abstract description 9
- RZWZRACFZGVKFM-UHFFFAOYSA-N propanoyl chloride Chemical compound CCC(Cl)=O RZWZRACFZGVKFM-UHFFFAOYSA-N 0.000 claims abstract description 7
- 230000000977 initiatory effect Effects 0.000 claims abstract description 5
- 238000003848 UV Light-Curing Methods 0.000 claims description 21
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims description 20
- 238000006243 chemical reaction Methods 0.000 claims description 17
- OMIGHNLMNHATMP-UHFFFAOYSA-N 2-hydroxyethyl prop-2-enoate Chemical compound OCCOC(=O)C=C OMIGHNLMNHATMP-UHFFFAOYSA-N 0.000 claims description 12
- 238000000034 method Methods 0.000 claims description 11
- 238000006116 polymerization reaction Methods 0.000 claims description 11
- 238000005286 illumination Methods 0.000 claims description 10
- 229910052757 nitrogen Inorganic materials 0.000 claims description 10
- XEKOWRVHYACXOJ-UHFFFAOYSA-N Ethyl acetate Chemical compound CCOC(C)=O XEKOWRVHYACXOJ-UHFFFAOYSA-N 0.000 claims description 9
- YXFVVABEGXRONW-UHFFFAOYSA-N Toluene Chemical compound CC1=CC=CC=C1 YXFVVABEGXRONW-UHFFFAOYSA-N 0.000 claims description 9
- ZMANZCXQSJIPKH-UHFFFAOYSA-N Triethylamine Chemical compound CCN(CC)CC ZMANZCXQSJIPKH-UHFFFAOYSA-N 0.000 claims description 9
- JUJWROOIHBZHMG-UHFFFAOYSA-N Pyridine Chemical compound C1=CC=NC=C1 JUJWROOIHBZHMG-UHFFFAOYSA-N 0.000 claims description 8
- NIXOWILDQLNWCW-UHFFFAOYSA-M Acrylate Chemical compound [O-]C(=O)C=C NIXOWILDQLNWCW-UHFFFAOYSA-M 0.000 claims description 7
- NQGIJDNPUZEBRU-UHFFFAOYSA-N dodecanoyl chloride Chemical compound CCCCCCCCCCCC(Cl)=O NQGIJDNPUZEBRU-UHFFFAOYSA-N 0.000 claims description 7
- ZDQNWDNMNKSMHI-UHFFFAOYSA-N 1-[2-(2-prop-2-enoyloxypropoxy)propoxy]propan-2-yl prop-2-enoate Chemical compound C=CC(=O)OC(C)COC(C)COCC(C)OC(=O)C=C ZDQNWDNMNKSMHI-UHFFFAOYSA-N 0.000 claims description 6
- VHYFNPMBLIVWCW-UHFFFAOYSA-N 4-Dimethylaminopyridine Chemical compound CN(C)C1=CC=NC=C1 VHYFNPMBLIVWCW-UHFFFAOYSA-N 0.000 claims description 6
- WYURNTSHIVDZCO-UHFFFAOYSA-N Tetrahydrofuran Chemical compound C1CCOC1 WYURNTSHIVDZCO-UHFFFAOYSA-N 0.000 claims description 6
- HVVWZTWDBSEWIH-UHFFFAOYSA-N [2-(hydroxymethyl)-3-prop-2-enoyloxy-2-(prop-2-enoyloxymethyl)propyl] prop-2-enoate Chemical compound C=CC(=O)OCC(CO)(COC(=O)C=C)COC(=O)C=C HVVWZTWDBSEWIH-UHFFFAOYSA-N 0.000 claims description 6
- 239000003054 catalyst Substances 0.000 claims description 6
- 230000035484 reaction time Effects 0.000 claims description 6
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical compound O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 5
- 239000008367 deionised water Substances 0.000 claims description 4
- 229910021641 deionized water Inorganic materials 0.000 claims description 4
- 238000002156 mixing Methods 0.000 claims description 4
- 239000003960 organic solvent Substances 0.000 claims description 4
- 230000001376 precipitating effect Effects 0.000 claims description 4
- UMJSCPRVCHMLSP-UHFFFAOYSA-N pyridine Natural products COC1=CC=CN=C1 UMJSCPRVCHMLSP-UHFFFAOYSA-N 0.000 claims description 4
- 238000005406 washing Methods 0.000 claims description 4
- PSGCQDPCAWOCSH-UHFFFAOYSA-N (4,7,7-trimethyl-3-bicyclo[2.2.1]heptanyl) prop-2-enoate Chemical compound C1CC2(C)C(OC(=O)C=C)CC1C2(C)C PSGCQDPCAWOCSH-UHFFFAOYSA-N 0.000 claims description 3
- SMZOUWXMTYCWNB-UHFFFAOYSA-N 2-(2-methoxy-5-methylphenyl)ethanamine Chemical compound COC1=CC=C(C)C=C1CCN SMZOUWXMTYCWNB-UHFFFAOYSA-N 0.000 claims description 3
- NIXOWILDQLNWCW-UHFFFAOYSA-N 2-Propenoic acid Natural products OC(=O)C=C NIXOWILDQLNWCW-UHFFFAOYSA-N 0.000 claims description 3
- ZMXDDKWLCZADIW-UHFFFAOYSA-N N,N-Dimethylformamide Chemical compound CN(C)C=O ZMXDDKWLCZADIW-UHFFFAOYSA-N 0.000 claims description 3
- 239000002202 Polyethylene glycol Substances 0.000 claims description 3
- QAOWNCQODCNURD-UHFFFAOYSA-L Sulfate Chemical compound [O-]S([O-])(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-L 0.000 claims description 3
- 150000001335 aliphatic alkanes Chemical group 0.000 claims description 3
- 239000003513 alkali Substances 0.000 claims description 3
- 238000007664 blowing Methods 0.000 claims description 3
- CQEYYJKEWSMYFG-UHFFFAOYSA-N butyl acrylate Chemical compound CCCCOC(=O)C=C CQEYYJKEWSMYFG-UHFFFAOYSA-N 0.000 claims description 3
- 125000004386 diacrylate group Chemical group 0.000 claims description 3
- 238000001035 drying Methods 0.000 claims description 3
- 230000007071 enzymatic hydrolysis Effects 0.000 claims description 3
- 238000006047 enzymatic hydrolysis reaction Methods 0.000 claims description 3
- 230000005496 eutectics Effects 0.000 claims description 3
- 239000002608 ionic liquid Substances 0.000 claims description 3
- UUORTJUPDJJXST-UHFFFAOYSA-N n-(2-hydroxyethyl)prop-2-enamide Chemical compound OCCNC(=O)C=C UUORTJUPDJJXST-UHFFFAOYSA-N 0.000 claims description 3
- 229920001223 polyethylene glycol Polymers 0.000 claims description 3
- 238000003756 stirring Methods 0.000 claims description 3
- YLQBMQCUIZJEEH-UHFFFAOYSA-N tetrahydrofuran Natural products C=1C=COC=1 YLQBMQCUIZJEEH-UHFFFAOYSA-N 0.000 claims description 3
- 229930195735 unsaturated hydrocarbon Chemical group 0.000 claims description 3
- 238000000016 photochemical curing Methods 0.000 abstract description 8
- 239000003999 initiator Substances 0.000 abstract description 6
- 230000007613 environmental effect Effects 0.000 abstract description 4
- 125000004185 ester group Chemical group 0.000 abstract 1
- 238000007711 solidification Methods 0.000 abstract 1
- 230000008023 solidification Effects 0.000 abstract 1
- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical compound OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 description 12
- 238000010521 absorption reaction Methods 0.000 description 12
- 239000000463 material Substances 0.000 description 9
- 239000000243 solution Substances 0.000 description 7
- 238000005516 engineering process Methods 0.000 description 6
- 239000000203 mixture Substances 0.000 description 6
- 239000007787 solid Substances 0.000 description 6
- 238000002835 absorbance Methods 0.000 description 5
- 125000003118 aryl group Chemical group 0.000 description 5
- 238000001723 curing Methods 0.000 description 5
- 125000002887 hydroxy group Chemical group [H]O* 0.000 description 5
- 229920001343 polytetrafluoroethylene Polymers 0.000 description 5
- 239000004810 polytetrafluoroethylene Substances 0.000 description 5
- 238000010926 purge Methods 0.000 description 5
- 238000005481 NMR spectroscopy Methods 0.000 description 4
- HFBMWMNUJJDEQZ-UHFFFAOYSA-N acryloyl chloride Chemical compound ClC(=O)C=C HFBMWMNUJJDEQZ-UHFFFAOYSA-N 0.000 description 4
- 230000015572 biosynthetic process Effects 0.000 description 4
- 238000002329 infrared spectrum Methods 0.000 description 4
- 239000007788 liquid Substances 0.000 description 4
- 238000002791 soaking Methods 0.000 description 4
- 238000003786 synthesis reaction Methods 0.000 description 4
- 239000011248 coating agent Substances 0.000 description 3
- 238000000576 coating method Methods 0.000 description 3
- 238000005227 gel permeation chromatography Methods 0.000 description 3
- 238000003541 multi-stage reaction Methods 0.000 description 3
- 238000006303 photolysis reaction Methods 0.000 description 3
- 230000015843 photosynthesis, light reaction Effects 0.000 description 3
- 150000003254 radicals Chemical class 0.000 description 3
- 238000001228 spectrum Methods 0.000 description 3
- 239000000126 substance Substances 0.000 description 3
- 238000009281 ultraviolet germicidal irradiation Methods 0.000 description 3
- XMLYCEVDHLAQEL-UHFFFAOYSA-N 2-hydroxy-2-methyl-1-phenylpropan-1-one Chemical compound CC(C)(O)C(=O)C1=CC=CC=C1 XMLYCEVDHLAQEL-UHFFFAOYSA-N 0.000 description 2
- GAWIXWVDTYZWAW-UHFFFAOYSA-N C[CH]O Chemical group C[CH]O GAWIXWVDTYZWAW-UHFFFAOYSA-N 0.000 description 2
- 238000000862 absorption spectrum Methods 0.000 description 2
- 239000000853 adhesive Substances 0.000 description 2
- 230000001070 adhesive effect Effects 0.000 description 2
- 230000007423 decrease Effects 0.000 description 2
- 230000007547 defect Effects 0.000 description 2
- 238000004090 dissolution Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 239000011521 glass Substances 0.000 description 2
- 238000001802 infusion Methods 0.000 description 2
- ISWSIDIOOBJBQZ-UHFFFAOYSA-N phenol group Chemical group C1(=CC=CC=C1)O ISWSIDIOOBJBQZ-UHFFFAOYSA-N 0.000 description 2
- 229920000058 polyacrylate Polymers 0.000 description 2
- 238000007639 printing Methods 0.000 description 2
- 238000010526 radical polymerization reaction Methods 0.000 description 2
- 238000002211 ultraviolet spectrum Methods 0.000 description 2
- 239000012855 volatile organic compound Substances 0.000 description 2
- YOCIJWAHRAJQFT-UHFFFAOYSA-N 2-bromo-2-methylpropanoyl bromide Chemical compound CC(C)(Br)C(Br)=O YOCIJWAHRAJQFT-UHFFFAOYSA-N 0.000 description 1
- 238000010146 3D printing Methods 0.000 description 1
- QTBSBXVTEAMEQO-UHFFFAOYSA-M Acetate Chemical compound CC([O-])=O QTBSBXVTEAMEQO-UHFFFAOYSA-M 0.000 description 1
- QTBSBXVTEAMEQO-UHFFFAOYSA-N Acetic acid Chemical group CC(O)=O QTBSBXVTEAMEQO-UHFFFAOYSA-N 0.000 description 1
- 238000005033 Fourier transform infrared spectroscopy Methods 0.000 description 1
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 1
- 150000004075 acetic anhydrides Chemical class 0.000 description 1
- 239000002671 adjuvant Substances 0.000 description 1
- 238000004220 aggregation Methods 0.000 description 1
- 230000002776 aggregation Effects 0.000 description 1
- 210000002421 cell wall Anatomy 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 230000021615 conjugation Effects 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 238000013461 design Methods 0.000 description 1
- 238000001514 detection method Methods 0.000 description 1
- 238000001914 filtration Methods 0.000 description 1
- 150000002430 hydrocarbons Chemical group 0.000 description 1
- 239000001257 hydrogen Substances 0.000 description 1
- 229910052739 hydrogen Inorganic materials 0.000 description 1
- 239000000976 ink Substances 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- QSHDDOUJBYECFT-UHFFFAOYSA-N mercury Chemical compound [Hg] QSHDDOUJBYECFT-UHFFFAOYSA-N 0.000 description 1
- 229910052753 mercury Inorganic materials 0.000 description 1
- 125000002496 methyl group Chemical group [H]C([H])([H])* 0.000 description 1
- 230000005012 migration Effects 0.000 description 1
- 238000013508 migration Methods 0.000 description 1
- 239000011259 mixed solution Substances 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- 238000006552 photochemical reaction Methods 0.000 description 1
- 239000003211 polymerization photoinitiator Substances 0.000 description 1
- 230000008569 process Effects 0.000 description 1
- 238000007712 rapid solidification Methods 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 150000003384 small molecules Chemical class 0.000 description 1
- 230000003381 solubilizing effect Effects 0.000 description 1
- 238000003860 storage Methods 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- 238000012360 testing method Methods 0.000 description 1
- 230000001988 toxicity Effects 0.000 description 1
- 231100000419 toxicity Toxicity 0.000 description 1
- 230000009466 transformation Effects 0.000 description 1
- 238000000844 transformation Methods 0.000 description 1
- 238000000870 ultraviolet spectroscopy Methods 0.000 description 1
- 238000001291 vacuum drying Methods 0.000 description 1
- 238000001429 visible spectrum Methods 0.000 description 1
Classifications
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P20/00—Technologies relating to chemical industry
- Y02P20/50—Improvements relating to the production of bulk chemicals
- Y02P20/54—Improvements relating to the production of bulk chemicals using solvents, e.g. supercritical solvents or ionic liquids
Landscapes
- Polymerisation Methods In General (AREA)
Abstract
The invention provides a preparation method and photocuring application of a lignin-based photoinitiator, which are characterized in that lignin is dissolved in a good solvent system, and esterification reaction is carried out with esterification reagents such as acetic anhydride, propionyl chloride, butyryl chloride, 2-bromoisobutyl acyl bromide, alpha-bromophenylacetic acid and the like, and ester functional groups are introduced into lignin molecular structures to obtain lignin ester derivatives. The lignin ester derivative can be used as a photoinitiator to be compounded with acrylic ester monomers, and the UV-cured solvent-free elastomer is synthesized under a photoinitiation system. The lignin ester derivative can be used as a UV photoinitiator, so that the added value of lignin is improved, and the application range of the lignin is widened. The lignin ester derivative has the advantages of high initiation efficiency, low mobility and the like when being used as an initiator, and is used for preparing an elastomer to meet the requirements of environmental protection, no solvent, quick solidification and the like.
Description
Technical Field
The invention relates to a lignin-based photoinitiator, in particular to a lignin-based photoinitiator, a preparation method thereof and a photo-curing application.
Background
The photo-curing technology is a process that can rapidly cure materials such as coating, ink, adhesive, etc. from a liquid or semi-solid state to a solid state by initiating chemical reaction using ultraviolet light or visible light. The technology is mainly applied to the fields of printing, coating, adhesives, 3D printing and the like, and has the advantages of rapid solidification, low Volatile Organic Compounds (VOCs) emission, environmental protection and high-efficiency production.
The photo-curing system is a polymerization reaction initiated by ultraviolet light or visible light, and rapidly cures materials such as coating or printing ink from a liquid state or a semi-solid state to a solid state. Such systems typically include components such as photoactive monomers, photoinitiators, and adjuvants. Where the photoinitiator is a key component of the photo-curing technology, it is typically a substance capable of absorbing light in a specific wavelength range, for example, a compound containing an aromatic ring structure or other photo-sensitive groups. However, conventional photoinitiators are usually small molecule compounds and are easily volatilized, which may lead to volatilization loss of the initiator during storage or use, reduce the photocuring efficiency, and even make the photocuring performance of the system unstable. In addition, problems of toxicity, environmental impact, and high cost during their synthesis have raised the need for more environmentally sustainable alternatives.
Lignin, which is a main component of plant cell walls, has natural oxidation resistance and renewable characteristics, and is rich in aromatic rings and hydroxyl functional groups, so that lignin can absorb light in ultraviolet and visible spectrum ranges and undergo photochemical reactions when irradiated by light. Further, more new functions can be imparted by modifying techniques such as biology, physics, and chemistry. Therefore, the preparation of lignin-based macromolecular photoinitiators by modifying lignin is of great importance in exploring the potential application of the lignin-based macromolecular photoinitiators in the field of photocuring.
In order to overcome the defects of the traditional initiator, chinese patent CN 110746523A discloses a lignin-based macromolecular photoinitiator, a preparation method and application thereof, and the technology simultaneously modifies and grafts a solubility-assisting group and a cleavage-type photoinitiator group on the lignin structure through multi-step reaction so as to endow the lignin with new structure and performance; chinese patent CN 110857336A discloses a polymerizable lignin-based macroinitiator, a preparation method and application thereof, and the technology introduces a solubilizing group, a photoinitiator group and an unsaturated double bond group into a lignin structure simultaneously through multi-step reaction. Both of the above-mentioned two invented techniques can make them possess solubility in water and conventional organic solvent and photoinitiation activity, and can trigger unsaturated double bond to produce free radical polymerization reaction under the condition of UV-visible light source. In the design and synthesis of the lignin-based photoinitiator, the lignin compatibility is solved, and a proper photosensitive group is selected and introduced into a lignin structure, so that the method is a key step. However, these methods described above may involve the selection of expensive photoactive groups, multi-step reactions, and complex synthetic routes, resulting in increased complexity and cost of the preparation process. Therefore, one of the key points of current research is to simplify the preparation steps to increase the synthesis efficiency while maintaining precise control of photoinitiator properties.
Disclosure of Invention
In order to solve the defects in the prior art, the invention aims to provide a lignin-based photoinitiator, and a preparation method and application thereof.
In order to achieve the above object, the present invention adopts the following technical scheme:
a lignin-based photoinitiator, lignin esterified derivative, having the structural formula:
r is an alkane or unsaturated hydrocarbon group.
The preparation method of the lignin-based photoinitiator comprises the following steps:
a1, fully dissolving lignin in a good solvent;
a2, adding an esterification reagent and a catalyst in a certain molar ratio into the lignin solution to perform esterification reaction, and after the reaction is finished, precipitating, washing and drying in excessive deionized water to obtain lignin ester derivatives.
Further, in the step A1, the mass ratio of lignin to good solvent is 1: 5-20; the dissolution temperature is room temperature;
the good solvent is any one of tetrahydrofuran, ethyl acetate, toluene, N-dimethylformamide, ionic liquid and eutectic solvent.
Further, in the step A2, the molar ratio of lignin to the esterifying reagent is 1:1 to 2; the reaction temperature is 0-120 ℃ and the reaction time is 1-8 h;
the lignin is any one of lignin sulfate, alkali lignin, enzymatic hydrolysis lignin and organic solvent lignin;
the esterifying reagent is any one of acetic anhydride, propionyl chloride, butyryl chloride, dodecanoyl chloride, 2-bromoisobutyl acyl bromide, alpha-bromophenylacetic acid and the like;
the catalyst is any one of pyridine, triethylamine, 4-dimethylaminopyridine and the like;
a UV light-cured solvent-free lignin-based elastomer, the preparation method comprises the following steps:
adding the initiator to a certain mass of acrylic ester, mixing, stirring, blowing nitrogen, initiating polymerization of monomers by using ultraviolet irradiation, and reacting for a certain time to obtain the solvent-free lignin-based elastomer;
further, the mass ratio of the acrylate monomer to the photoinitiator is 100:0.1 to 1;
further, the acrylic ester monomer is any one of N-butyl acrylate, isobornyl acrylate, hydroxyethyl acrylate, acrylic acid, pentaerythritol triacrylate, tripropylene glycol diacrylate, N-hydroxyethyl acrylamide, polyethylene glycol diacrylate and the like;
further, the illumination intensity of the ultraviolet light curing in the step is 50-100 mW cm -2 The illumination reaction time is 1-10 min.
Further, the thickness of the elastomer is 0.5 to 1mm.
The invention has the advantages that:
the lignin ester derivative provided by the invention has better solubility in conventional solvents and acrylate monomers, and can be used as a free radical polymerization photoinitiator, so that the added value of lignin is further improved, and the application range of the lignin is enlarged.
The method for preparing the photoinitiator is simple, mild, green and efficient, effectively solves the problems of long time consumption, non-reproducibility, high mobility and the like of the existing preparation of the macromolecular photoinitiator, and has strong practicability and wide applicability.
The UV ultraviolet curing solvent-free elastomer is prepared by using the lignin-based photoinitiator, integrates the advantages of acrylic ester, solvent-free, UV ultraviolet curing and low mobility, improves the stress, strain and toughness of the elastomer compared with the traditional photoinitiator, and can meet the requirements of daily elastomers on environmental protection, solvent-free, rapid curing, high strength and low mobility of the initiator.
Drawings
FIG. 1 is an infrared spectrum of lignin, acetic anhydride esterified lignin, butyryl chloride esterified lignin and dodecanoyl chloride esterified lignin.
FIG. 2 is an ultraviolet spectrum of lignin, acetic anhydride esterified lignin, butyryl chloride esterified lignin and dodecanoyl chloride esterified lignin.
FIG. 3 is a schematic illustration of lignin and acetic anhydride esterified lignin 1 H NMR chart.
FIG. 4 is a graph of gel permeation chromatography effluent time for lignin and acetic anhydride esterified lignin.
FIG. 5 is an ultraviolet photolysis curve of lignin and acetic anhydride esterified lignin.
FIG. 6 is a graph comparing the mechanical properties of 1173 and different esterified lignin-based elastomers.
FIG. 7 is a graph of digital photographs and an infrared spectrogram of the 2-bromoisobutyryl bromoesterified lignin system before and after UV illumination.
FIG. 8 is a graph of digital photographs and an infrared spectrogram of an alpha-bromophenylacetic acid esterified lignin system before and after UV illumination.
FIG. 9 is a graph showing the relationship between UV cure time and double bond conversion of acetic anhydride esterified lignin free radical polymerized PTGDA.
FIG. 10 is a graph showing UV cure time versus double bond conversion for acetic anhydride esterified lignin radical polymerized PETA.
FIG. 11 is a graph of the ultraviolet absorption spectrum of 1173 and acetic anhydride esterified lignin-based elastomers immersed in methanol solution for 5 h.
Detailed Description
The invention is described in detail below with reference to the drawings and the specific embodiments.
The reagents used in this example are all commercially available.
The instrument and the detection method used for the test are as follows:
infrared equipment: nicolet iS10 Fourier infrared spectrometer (FT-IR), simer Feier science and technology;
nuclear magnetic device: bruker 400MHz nuclear magnetic resonance NMR spectrometer, bruker Germany;
ultraviolet equipment: HT-2600 ultraviolet-visible spectrophotometer; shanghai, instrument and meter Inc.;
mechanical equipment: INSTRON 4466 universal tensile tester, shenzhen Meist Co., china;
gel permeation chromatography apparatus: viscotek VE3580 RI gel permeation chromatograph, malvern instruments inc.
A lignin-based photoinitiator is lignin esterified derivative, and has the following structural formula:
r is an alkane or unsaturated hydrocarbon group
The preparation method of the lignin-based photoinitiator comprises the following steps:
a1, fully dissolving lignin in a good solvent;
a2, adding an esterification reagent and a catalyst in a certain molar ratio into the lignin solution to perform esterification reaction, and after the reaction is finished, precipitating, washing and drying in excessive deionized water to obtain lignin ester derivatives.
The mass ratio of lignin to good solvent in the step A1 is 1: 5-20; the dissolution temperature is room temperature; the good solvent is any one of tetrahydrofuran, ethyl acetate, toluene, N-dimethylformamide, ionic liquid and eutectic solvent.
The lignin is any one of lignin sulfate, alkali lignin, enzymatic hydrolysis lignin and organic solvent lignin;
the esterification reagent is any one of acetic anhydride, propionyl chloride, butyryl chloride, dodecanoyl chloride, 2-bromoisobutyl acyl bromide, alpha-bromophenylacetic acid and the like, and the molar ratio of lignin to the esterification reagent is 1:1 to 2; the reaction temperature is 0-120 ℃ and the reaction time is 1-8 h;
the catalyst is any one of pyridine, triethylamine, 4-dimethylaminopyridine and the like;
a UV light-cured solvent-free lignin-based elastomer, the preparation method comprises the following steps:
adding the photoinitiator into acrylic ester with certain mass, mixing, stirring, blowing nitrogen, initiating monomer polymerization by using ultraviolet irradiation, and reacting for a certain time to obtain the UV-cured solvent-free lignin-based elastomer; the mass ratio of the acrylate monomer to the photoinitiator is 100:0.1 to 1; the acrylic ester monomer is any one of N-butyl acrylate, isobornyl acrylate, hydroxyethyl acrylate, acrylic acid, pentaerythritol triacrylate, tripropylene glycol diacrylate, N-hydroxyethyl acrylamide, polyethylene glycol diacrylate and the like; the illumination intensity of the ultraviolet light curing is 50-100 mW cm -2 The illumination reaction time is 1-10 min, and the thickness of the prepared elastomer is 0.5-1 mm.
Example 1
Preparation of lignin-based photoinitiator:
(1) 1g of dealkalized lignin is dissolved in 5mL of pyridine, 10mL of acetic anhydride is added into the mixed solution, and the temperature is raised to 50 ℃ for reaction for 6h. And after the reaction is finished, precipitating a product in excessive deionized water, further washing, filtering, and obtaining the acetic anhydride esterified lignin under the vacuum drying condition, wherein the esterified lignin is used as a lignin-based photoinitiator for standby.
Wherein the infrared spectrogram of lignin and acetic anhydride esterified lignin is shown in figure 1, and 3340cm of lignin -1 Is the vibration absorption peak of hydroxyl (-OH), and after esterification by acetic anhydride, lignin hydroxyl (-OH) esterified by acetic anhydride is 3340cm -1 The vibration absorption peak was drastically reduced, and a strong vibration absorption peak of an ester bond (c=o) appeared, indicating that the lignin esterification reaction was successful, whereby the successful synthesis of acetic anhydride esterified lignin could be preliminarily judged.
The uv spectra of lignin and acetic anhydride esterified lignin are shown in fig. 2, with the lignin absorption peak at 218nm being related to unsaturated c=c or c=o bonds, and the absorption peak at 280nm being related to phenolic hydroxyl groups and aromatic groups. The spectrum of acetic anhydride esterified lignin showed a smaller blue shift (210 nm) compared to lignin, indicating a reduced degree of aggregation of aromatic groups due to the introduction of acetate chains. In addition, the peak at 280nm of the lignin esterified with acetic anhydride was reduced due to the consumption of phenolic hydroxyl groups by the esterification reaction. FIG. 3 is a graph of gel permeation chromatography effluent time of lignin and acetic anhydride esterified lignin, showing an increase in number average molecular weight from 710 to 840 after lignin has undergone an acetic anhydride esterification reaction.
To further verify the structure of the acetic anhydride esterified lignin, use was made of 1 The structure was analyzed by H NMR and fig. 4 shows nuclear magnetic hydrogen spectra of lignin and acetic anhydride esterified lignin. As can be seen from FIG. 2, the chemical shift of protons on unsaturated double bonds on lignin aromatic ring structure is mainly between peaks of 6.1-7.0. And the new shift peak appearing at 1.9-2.3 in the acetic anhydride esterified lignin spectrogram is proton chemical shift of methyl on acetate, which further confirms successful preparation of acetic anhydride esterified lignin.
To further verify the photoinitiating effect of acetic anhydride esterified lignin, at 50mW/cm -2 The light intensity mercury lamp irradiates the photolysis curves at different times. As can be seen from FIG. 5, after 8min of illumination, the absorbance of lignin and acetic anhydride esterified lignin decreased by 9.7% and 18.6% of absorbance before no illumination, respectively, and acetic anhydride esterified ligninThe rate of photolysis of the element is significantly faster than that of lignin, indicating that the degree of conjugation of the initiator is destroyed faster than that of lignin under the same conditions, meaning that it can generate living radicals faster.
Preparation of UV light-cured solvent-free lignin-based elastomer:
taking hydroxyethyl acrylate monomer as an example, 5g of hydroxyethyl acrylate and 0.025g of photoinitiator (acetic anhydride esterified lignin) are mixed and poured into a polytetrafluoroethylene mould, and after 20min of nitrogen purging, the mixture is subjected to light intensity of 50mW/cm -2 The UV light source of (2) is irradiated to initiate monomer polymerization for 5min, and the UV light curing solvent-free lignin-based elastomer material is obtained.
In example 1, the mechanical properties of the hydroxyethyl polyacrylate elastomer prepared with acetic anhydride esterified lignin as a photoinitiator are shown in fig. 6. From the figure, it can be seen that the elastomer 1173-HEA prepared using the small molecule photoinitiator 2-hydroxy-2-methyl-1-phenyl-1-propanone (1173) had stresses and strains of 2.85MPa and 553%, respectively, while the elastomer prepared using the series of acetic anhydride esterified lignin as the photoinitiator had improved mechanical properties, corresponding to stresses and strains of 3.94MPa and 890%, respectively.
TABLE 1 composition of different elastomers
a 1173 as photoinitiation to prepare hydroxyethyl acrylate elasticity; b acetic anhydride esterified lignin is used as a photoinitiator; c propionyl chloride esterified lignin is used as a photoinitiator; d butyryl chloride esterified lignin is used as a photoinitiator; e lauroyl chloride esterified lignin is used as a photoinitiator; f the lignin modified by acrylic chloride esterification is used as a photoinitiator; g 2-bromoisobutyryl bromoesterified lignin as a photoinitiator; h alpha-bromophenylacetic acid esterified lignin is used as a photoinitiator.
Example 2
As shown in example 1, except in the preparation step of lignin-based photoinitiator. Lignin is esterified with propionyl chloride, butyryl chloride, dodecanoyl chloride or acryloyl chloride, respectively. FIG. 1 is an infrared spectrum of different lignin esterified derivatives, and FIG. 2 is an ultraviolet absorption spectrum of lignin and different lignin esterified derivatives.
Preparation of UV light-cured solvent-free lignin-based elastomer:
taking hydroxyethyl acrylate monomer as an example, 5g of hydroxyethyl acrylate and 0.025g of photoinitiator (propionyl chloride, butyryl chloride, dodecanoyl chloride ester or acrylyl chloride esterified lignin) are mixed and poured into a polytetrafluoroethylene mould, and after 20min of nitrogen purging, the mixture is subjected to light intensity of 50mW/cm -2 The UV light source of (2) is irradiated to initiate monomer polymerization for 5min, and the UV light curing solvent-free lignin-based elastomer material is obtained.
In example 2, the mechanical properties of the hydroxyethyl polyacrylate elastomer prepared from different esterified lignin as photoinitiator are shown in fig. 6. From the graph, it can be seen that the 1173-HEA stress strain prepared by using the small molecular photoinitiator 1173 is 2.85MPa and 553%, respectively, while the mechanical properties of the elastomer prepared by using the series lignin esterification derivative as the photoinitiator are improved, wherein the ACL-HEA stress and strain of the elastomer prepared by using the acryl chloride esterification lignin system are improved to 6.17MPa and 930%, respectively.
Example 3
As shown in example 1, except in the preparation step of lignin-based photoinitiator. And (3) esterifying lignin by using 2-bromoisobutyryl bromide as an esterifying reagent to obtain 2-bromoisobutyryl bromoesterified lignin.
Preparation of UV light-cured solvent-free lignin-based elastomer:
as shown in Table 1, using hydroxyethyl acrylate monomer as an example, 5g of hydroxyethyl acrylate and 0.025g of a photoinitiator (2-bromoisobutyryl bromoesterified lignin) were mixed in a glass bottle, and after purging with nitrogen for 20 minutes, the mixture was subjected to a light intensity of 50mW/cm -2 The UV light source of (2) is irradiated to initiate monomer polymerization for 5min, and the UV light curing solvent-free lignin-based elastomer material is obtained. Fig. 7a is a digital photograph of the elastomer before and after UV curing, and fig. 7b is an infrared spectrogram of the elastomer before and after UV curing. As can be seen from the figure, the UV cured system is fromThe liquid state is changed into the solid state, and an infrared spectrogram shows 1638cm before and after UV light curing -1 C=c of (C) is significantly reduced.
Example 4
As shown in example 1, except in the preparation step of lignin-based photoinitiator. And (3) using the alpha-bromophenylacetic acid as an esterification reagent to esterify lignin to obtain the alpha-bromophenylacetic acid esterified lignin.
Preparation of UV light-cured solvent-free lignin-based elastomer:
as shown in Table 1, using hydroxyethyl acrylate monomer as an example, 5g of hydroxyethyl acrylate and 0.025g of a photoinitiator (. Alpha. -bromophenylacetic acid esterified lignin) were mixed in a glass bottle, and after purging with nitrogen for 20 minutes, the mixture was subjected to a light intensity of 50mW/cm -2 The UV light source of (2) is irradiated to initiate monomer polymerization for 5min, and the UV light curing solvent-free lignin-based elastomer material is obtained. Fig. 8a is a digital photograph of the elastomer before and after UV curing, and fig. 8b is an infrared spectrogram of the elastomer before and after UV curing. As can be seen from the figure, the system changes from liquid state to solid state after UV light curing, and an infrared spectrogram shows 1638cm before and after UV light curing -1 C=c of (C) is significantly reduced.
Example 5
As shown in example 1, except in the preparation step of UV light-cured solvent-free lignin-based elastomer.
Uniformly mixing 5g of tripropylene glycol diacrylate and 0.025g of photoinitiator (acetic anhydride esterified lignin), pouring the mixture into a polytetrafluoroethylene die, and purging with nitrogen for 20min to obtain 50mW/cm -2 The UV light source of (2) is irradiated to initiate monomer polymerization for 5min, and the UV light curing solvent-free lignin-based elastomer material is obtained. Fig. 9a is an infrared spectrum of a tripropylene glycol diacrylate elastomer at different UV curing times, and fig. 9b is a relationship between the UV curing time and the double bond conversion of the tripropylene glycol diacrylate elastomer. 1633cm as shown in FIG. 9a -1 Where c=c is the double bond absorption peak, the intensity of the double bond absorption peak gradually decreases after UV irradiation, and as can be seen from the graph of the relationship between UV curing time and double bond conversion (fig. 9 b), the double bond conversion in the prepolymer reached 65.3% after UV lamp irradiation for 15 min.
Example 6
As shown in example 1, except in the preparation step of UV light-cured solvent-free lignin-based elastomer.
After 5g of pentaerythritol triacrylate and 0.025g of photoinitiator (acetic anhydride esterified lignin) were uniformly mixed, poured into a polytetrafluoroethylene mold, and purged with nitrogen for 20 minutes, 50mW/cm -2 The UV light source irradiation of (2) initiates monomer polymerization for 90s, and the UV light curing solvent-free lignin-based elastomer material is obtained.
Fig. 10a is an infrared spectrum of an elastomer at different UV curing times, and fig. 10b is a relationship between UV curing time and double bond conversion rate of an elastomer. As shown in the figure, 1634cm -1 Where c=c is the double bond absorption peak, the intensity of the double bond absorption peak gradually decreases after UV irradiation, and as can be seen from the graph of the relationship between the UV curing time and the double bond conversion rate (fig. 10 b), the double bond conversion rate reaches 61.2% after UV irradiation for 90 s.
Example 7
As shown in example 4, except that in the preparation step of the UV light cured solvent free lignin-based elastomer, the mobility was further compared with the photoinitiator 1173.
After 5g pentaerythritol triacrylate, 0.025g photoinitiator (acetic anhydride esterified lignin) or 1173 were mixed uniformly, poured into a polytetrafluoroethylene mold, purged with nitrogen for 20min, and then 50mW/cm -2 The UV light source of (2) is irradiated to initiate monomer polymerization for 5min, and the UV light curing solvent-free lignin-based elastomer material is obtained.
When mobility is studied, the acetic anhydride esterified lignin and 1173 photoinitiation systems are used for obtaining the UV solvent-free elastomer, 2g of dried samples are weighed and soaked in 20mL of methanol solution, 5 groups of samples with soaking time of 1, 2, 3, 4 and 5 hours are prepared for each system, and the change rule of ultraviolet absorbance of the soaking solution along with the soaking time is explored.
FIG. 11a is an ultraviolet absorption curve of 1173-PETA infusion and FIG. 11b is an ultraviolet absorption curve of AL-PETA infusion. From the graph, the absorbance at the maximum absorption wavelengths of 1173-PETA and AL-PETA systems gradually increased with the increase of the soaking time of the elastomer in methanol solution, indicating that the migration amounts of the photoinitiator 1173 and the acetic anhydride esterified lignin gradually increased. When methanol is soaked for 5 hours, the mobility of the photoinitiator in 1173-PETA and AL-PETA systems is 2.34% and 0.61%, the absorbance of the AL-PETA system and the mobility of the photoinitiator are obviously lower than those of the 1173-PETA system, and the mobility of the photoinitiator grows slowly, which shows that the mobility of the photoinitiator acetic anhydride esterified lignin is obviously lower than that of the small molecular photoinitiator 1173.
The foregoing has shown and described the basic principles, principal features and advantages of the invention. It will be appreciated by persons skilled in the art that the above embodiments are not intended to limit the invention in any way, and that all technical solutions obtained by means of equivalent substitutions or equivalent transformations fall within the scope of the invention.
Claims (8)
1. A lignin-based photoinitiator is a lignin-based ester derivative and is characterized by having the following structural formula:
r is alkane or unsaturated hydrocarbon.
2. A method of preparing the lignin-based photoinitiator according to claim 1 comprising the steps of:
a1, dissolving lignin in a good solvent;
a2, adding an esterification reagent and a catalyst in a certain molar ratio into the lignin solution to perform esterification reaction, and after the reaction is finished, precipitating, washing and drying in excessive deionized water to obtain lignin ester derivatives.
3. The method for preparing lignin-based photoinitiator according to claim 2 wherein the molar ratio of lignin to esterifying reagent in step A2 is 1:1 to 2; the reaction temperature is 0-120 ℃ and the reaction time is 1-8 h;
the lignin is any one of lignin sulfate, alkali lignin, enzymatic hydrolysis lignin and organic solvent lignin;
the esterifying reagent is any one of acetic anhydride, propionyl chloride, butyryl chloride, dodecanoyl chloride, 2-bromoisobutyl acyl bromide and alpha-bromophenylacetic acid;
the catalyst is any one of pyridine, triethylamine and 4-dimethylaminopyridine;
the solution is any one of tetrahydrofuran, ethyl acetate, toluene, N-dimethylformamide, ionic liquid and eutectic solvent.
4. Use of the lignin-based photoinitiator according to claim 1 in UV-curing solventless elastomers.
5. The use according to claim 4, characterized in that: the UV-curable solvent-free elastomer comprises: lignin-based photoinitiator and acrylate hard monomer, wherein the mass ratio of the acrylate hard monomer to the lignin-based photoinitiator is 100:0.1 to 1.
6. The preparation method of the UV light-cured solvent-free lignin-based elastomer is characterized by comprising the following steps of:
(B1) Preparing a lignin-based photoinitiator using the method of claim 2;
(B2) Adding a certain mass of acrylic ester into the lignin-based photoinitiator, mixing, stirring, blowing nitrogen, initiating monomer polymerization by using ultraviolet irradiation, and reacting for a certain time to obtain the solvent-free lignin-based elastomer.
7. The method for preparing the UV light-curable solventless lignin-based elastomer according to claim 6, wherein the mass ratio of the acrylate hard monomer to the lignin-based photoinitiator in the step B2 is 100:0.1 to 1;
the acrylate hard monomer is any one of N-butyl acrylate, isobornyl acrylate, hydroxyethyl acrylate, acrylic acid, pentaerythritol triacrylate, tripropylene glycol diacrylate, N-hydroxyethyl acrylamide and polyethylene glycol diacrylate.
8. The method for preparing a UV-curable solventless lignin-based elastomer according to claim 7, wherein the UV-curable illumination intensity in the step is 50-100 mW cm -2 The illumination reaction time is 3-10 min.
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