CN117801627A - Reversible thermochromic epoxy powder coating and preparation method thereof - Google Patents
Reversible thermochromic epoxy powder coating and preparation method thereof Download PDFInfo
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- CN117801627A CN117801627A CN202311784407.3A CN202311784407A CN117801627A CN 117801627 A CN117801627 A CN 117801627A CN 202311784407 A CN202311784407 A CN 202311784407A CN 117801627 A CN117801627 A CN 117801627A
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- 238000000576 coating method Methods 0.000 title claims abstract description 104
- 239000011248 coating agent Substances 0.000 title claims abstract description 97
- 239000000843 powder Substances 0.000 title claims abstract description 73
- 230000002441 reversible effect Effects 0.000 title claims abstract description 45
- 239000004593 Epoxy Substances 0.000 title claims abstract description 44
- 238000002360 preparation method Methods 0.000 title claims abstract description 16
- 239000000049 pigment Substances 0.000 claims abstract description 46
- 239000003795 chemical substances by application Substances 0.000 claims abstract description 42
- 239000003822 epoxy resin Substances 0.000 claims abstract description 34
- 229920000647 polyepoxide Polymers 0.000 claims abstract description 34
- 239000002994 raw material Substances 0.000 claims abstract description 25
- 239000007822 coupling agent Substances 0.000 claims abstract description 13
- 238000009736 wetting Methods 0.000 claims abstract description 6
- 239000013530 defoamer Substances 0.000 claims abstract description 5
- ISAOCJYIOMOJEB-UHFFFAOYSA-N benzoin Chemical group C=1C=CC=CC=1C(O)C(=O)C1=CC=CC=C1 ISAOCJYIOMOJEB-UHFFFAOYSA-N 0.000 claims description 14
- IISBACLAFKSPIT-UHFFFAOYSA-N bisphenol A Chemical class C=1C=C(O)C=CC=1C(C)(C)C1=CC=C(O)C=C1 IISBACLAFKSPIT-UHFFFAOYSA-N 0.000 claims description 14
- 238000001125 extrusion Methods 0.000 claims description 12
- -1 glycidyl ester Chemical class 0.000 claims description 11
- 239000000155 melt Substances 0.000 claims description 10
- 235000010489 acacia gum Nutrition 0.000 claims description 8
- 239000000839 emulsion Substances 0.000 claims description 8
- 244000215068 Acacia senegal Species 0.000 claims description 7
- 229920000084 Gum arabic Polymers 0.000 claims description 7
- 244000028419 Styrax benzoin Species 0.000 claims description 7
- 235000000126 Styrax benzoin Nutrition 0.000 claims description 7
- 235000008411 Sumatra benzointree Nutrition 0.000 claims description 7
- 239000000205 acacia gum Substances 0.000 claims description 7
- 229960002130 benzoin Drugs 0.000 claims description 7
- 239000004841 bisphenol A epoxy resin Substances 0.000 claims description 7
- 229920001577 copolymer Polymers 0.000 claims description 7
- 235000019382 gum benzoic Nutrition 0.000 claims description 7
- 238000000034 method Methods 0.000 claims description 7
- QGBSISYHAICWAH-UHFFFAOYSA-N dicyandiamide Chemical compound NC(N)=NC#N QGBSISYHAICWAH-UHFFFAOYSA-N 0.000 claims description 6
- 238000010438 heat treatment Methods 0.000 claims description 6
- 239000003094 microcapsule Substances 0.000 claims description 6
- 238000007873 sieving Methods 0.000 claims description 6
- 235000014113 dietary fatty acids Nutrition 0.000 claims description 4
- 239000000194 fatty acid Substances 0.000 claims description 4
- 229930195729 fatty acid Natural products 0.000 claims description 4
- 150000004665 fatty acids Chemical class 0.000 claims description 4
- 238000002156 mixing Methods 0.000 claims description 4
- 230000008569 process Effects 0.000 claims description 4
- PQAMFDRRWURCFQ-UHFFFAOYSA-N 2-ethyl-1h-imidazole Chemical compound CCC1=NC=CN1 PQAMFDRRWURCFQ-UHFFFAOYSA-N 0.000 claims description 3
- LXBGSDVWAMZHDD-UHFFFAOYSA-N 2-methyl-1h-imidazole Chemical compound CC1=NC=CN1 LXBGSDVWAMZHDD-UHFFFAOYSA-N 0.000 claims description 3
- BKCCAYLNRIRKDJ-UHFFFAOYSA-N 2-phenyl-4,5-dihydro-1h-imidazole Chemical compound N1CCN=C1C1=CC=CC=C1 BKCCAYLNRIRKDJ-UHFFFAOYSA-N 0.000 claims description 3
- 239000006087 Silane Coupling Agent Substances 0.000 claims description 3
- 150000004645 aluminates Chemical class 0.000 claims description 3
- 229920001519 homopolymer Polymers 0.000 claims description 3
- NIXOWILDQLNWCW-UHFFFAOYSA-M Acrylate Chemical compound [O-]C(=O)C=C NIXOWILDQLNWCW-UHFFFAOYSA-M 0.000 claims description 2
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 claims description 2
- GYZLOYUZLJXAJU-UHFFFAOYSA-N diglycidyl ether Chemical compound C1OC1COCC1CO1 GYZLOYUZLJXAJU-UHFFFAOYSA-N 0.000 claims description 2
- 150000003918 triazines Chemical class 0.000 claims description 2
- 239000011353 cycloaliphatic epoxy resin Substances 0.000 claims 1
- 230000001804 emulsifying effect Effects 0.000 claims 1
- 229920001296 polysiloxane Polymers 0.000 claims 1
- 238000003756 stirring Methods 0.000 claims 1
- 239000003513 alkali Substances 0.000 abstract description 7
- 238000009826 distribution Methods 0.000 abstract description 7
- 238000003860 storage Methods 0.000 abstract description 7
- 239000002253 acid Substances 0.000 abstract description 6
- 239000000853 adhesive Substances 0.000 abstract description 5
- 230000001070 adhesive effect Effects 0.000 abstract description 5
- 230000008859 change Effects 0.000 description 17
- 239000003973 paint Substances 0.000 description 10
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 9
- 239000000463 material Substances 0.000 description 9
- ZWEHNKRNPOVVGH-UHFFFAOYSA-N 2-Butanone Chemical compound CCC(C)=O ZWEHNKRNPOVVGH-UHFFFAOYSA-N 0.000 description 8
- 239000000126 substance Substances 0.000 description 8
- GWEVSGVZZGPLCZ-UHFFFAOYSA-N Titan oxide Chemical group O=[Ti]=O GWEVSGVZZGPLCZ-UHFFFAOYSA-N 0.000 description 7
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 6
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 description 6
- 238000009863 impact test Methods 0.000 description 6
- 238000005336 cracking Methods 0.000 description 5
- 230000007547 defect Effects 0.000 description 5
- 238000006243 chemical reaction Methods 0.000 description 4
- 238000002844 melting Methods 0.000 description 4
- 230000008018 melting Effects 0.000 description 4
- 229920005989 resin Polymers 0.000 description 4
- 239000011347 resin Substances 0.000 description 4
- 238000012360 testing method Methods 0.000 description 4
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 3
- 125000002723 alicyclic group Chemical group 0.000 description 3
- 230000000052 comparative effect Effects 0.000 description 3
- 238000007590 electrostatic spraying Methods 0.000 description 3
- 238000005538 encapsulation Methods 0.000 description 3
- 229910052742 iron Inorganic materials 0.000 description 3
- 238000004519 manufacturing process Methods 0.000 description 3
- 229910052751 metal Inorganic materials 0.000 description 3
- 239000002184 metal Substances 0.000 description 3
- 239000004570 mortar (masonry) Substances 0.000 description 3
- 239000003960 organic solvent Substances 0.000 description 3
- 229920001225 polyester resin Polymers 0.000 description 3
- 239000004645 polyester resin Substances 0.000 description 3
- 238000007665 sagging Methods 0.000 description 3
- 239000002904 solvent Substances 0.000 description 3
- 239000002966 varnish Substances 0.000 description 3
- 239000012856 weighed raw material Substances 0.000 description 3
- WYRGOSDNPFGZFG-UHFFFAOYSA-K [bis(2-ethylhexoxy)-oxidophosphaniumyl] dihydrogen phosphate [bis(2-ethylhexoxy)-oxidophosphaniumyl] hydrogen phosphate [bis(2-ethylhexoxy)-oxidophosphaniumyl] phosphate propan-2-olate titanium(4+) Chemical compound [Ti+4].CC(C)[O-].CCCCC(CC)CO[P+]([O-])(OCC(CC)CCCC)OP(O)(O)=O.CCCCC(CC)CO[P+]([O-])(OCC(CC)CCCC)OP(O)([O-])=O.CCCCC(CC)CO[P+]([O-])(OCC(CC)CCCC)OP([O-])([O-])=O WYRGOSDNPFGZFG-UHFFFAOYSA-K 0.000 description 2
- TZCXTZWJZNENPQ-UHFFFAOYSA-L barium sulfate Chemical compound [Ba+2].[O-]S([O-])(=O)=O TZCXTZWJZNENPQ-UHFFFAOYSA-L 0.000 description 2
- 238000004132 cross linking Methods 0.000 description 2
- 230000001627 detrimental effect Effects 0.000 description 2
- TVIDDXQYHWJXFK-UHFFFAOYSA-N dodecanedioic acid Chemical compound OC(=O)CCCCCCCCCCC(O)=O TVIDDXQYHWJXFK-UHFFFAOYSA-N 0.000 description 2
- 125000002887 hydroxy group Chemical group [H]O* 0.000 description 2
- 239000001038 titanium pigment Substances 0.000 description 2
- OUPZKGBUJRBPGC-UHFFFAOYSA-N 1,3,5-tris(oxiran-2-ylmethyl)-1,3,5-triazinane-2,4,6-trione Chemical compound O=C1N(CC2OC2)C(=O)N(CC2OC2)C(=O)N1CC1CO1 OUPZKGBUJRBPGC-UHFFFAOYSA-N 0.000 description 1
- SMZOUWXMTYCWNB-UHFFFAOYSA-N 2-(2-methoxy-5-methylphenyl)ethanamine Chemical compound COC1=CC=C(C)C=C1CCN SMZOUWXMTYCWNB-UHFFFAOYSA-N 0.000 description 1
- NIXOWILDQLNWCW-UHFFFAOYSA-N 2-Propenoic acid Natural products OC(=O)C=C NIXOWILDQLNWCW-UHFFFAOYSA-N 0.000 description 1
- 239000004925 Acrylic resin Substances 0.000 description 1
- 229920000178 Acrylic resin Polymers 0.000 description 1
- MZZSDCJQCLYLLL-UHFFFAOYSA-N Secalonsaeure A Natural products COC(=O)C12OC3C(CC1=C(O)CC(C)C2O)C(=CC=C3c4ccc(O)c5C(=O)C6=C(O)CC(C)C(O)C6(Oc45)C(=O)OC)O MZZSDCJQCLYLLL-UHFFFAOYSA-N 0.000 description 1
- GLLRIXZGBQOFLM-UHFFFAOYSA-N Xanthorin Natural products C1=C(C)C=C2C(=O)C3=C(O)C(OC)=CC(O)=C3C(=O)C2=C1O GLLRIXZGBQOFLM-UHFFFAOYSA-N 0.000 description 1
- 239000001785 acacia senegal l. willd gum Substances 0.000 description 1
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 1
- 239000002518 antifoaming agent Substances 0.000 description 1
- 238000003556 assay Methods 0.000 description 1
- 239000012752 auxiliary agent Substances 0.000 description 1
- 230000004888 barrier function Effects 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000009529 body temperature measurement Methods 0.000 description 1
- 238000005282 brightening Methods 0.000 description 1
- 239000004566 building material Substances 0.000 description 1
- 239000000470 constituent Substances 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- ZWLIYXJBOIDXLL-UHFFFAOYSA-N decanedihydrazide Chemical compound NNC(=O)CCCCCCCCC(=O)NN ZWLIYXJBOIDXLL-UHFFFAOYSA-N 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000002845 discoloration Methods 0.000 description 1
- 239000002270 dispersing agent Substances 0.000 description 1
- 239000012153 distilled water Substances 0.000 description 1
- 238000005265 energy consumption Methods 0.000 description 1
- 239000003623 enhancer Substances 0.000 description 1
- 125000003700 epoxy group Chemical group 0.000 description 1
- 239000000945 filler Substances 0.000 description 1
- 239000007888 film coating Substances 0.000 description 1
- 238000009501 film coating Methods 0.000 description 1
- 239000012847 fine chemical Substances 0.000 description 1
- 235000013305 food Nutrition 0.000 description 1
- 238000009472 formulation Methods 0.000 description 1
- LNEPOXFFQSENCJ-UHFFFAOYSA-N haloperidol Chemical compound C1CC(O)(C=2C=CC(Cl)=CC=2)CCN1CCCC(=O)C1=CC=C(F)C=C1 LNEPOXFFQSENCJ-UHFFFAOYSA-N 0.000 description 1
- 231100000206 health hazard Toxicity 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 239000011159 matrix material Substances 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012544 monitoring process Methods 0.000 description 1
- 238000000465 moulding Methods 0.000 description 1
- 239000004482 other powder Substances 0.000 description 1
- ISWSIDIOOBJBQZ-UHFFFAOYSA-N phenol group Chemical group C1(=CC=CC=C1)O ISWSIDIOOBJBQZ-UHFFFAOYSA-N 0.000 description 1
- 238000006116 polymerization reaction Methods 0.000 description 1
- 229920001343 polytetrafluoroethylene Polymers 0.000 description 1
- 239000004810 polytetrafluoroethylene Substances 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 239000006254 rheological additive Substances 0.000 description 1
- 239000011257 shell material Substances 0.000 description 1
- 239000002356 single layer Substances 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 238000005507 spraying Methods 0.000 description 1
- 239000000758 substrate Substances 0.000 description 1
- 229920001187 thermosetting polymer Polymers 0.000 description 1
- 239000004408 titanium dioxide Substances 0.000 description 1
- 239000002699 waste material Substances 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical compound O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
- 238000004383 yellowing Methods 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
- C09D163/00—Coating compositions based on epoxy resins; Coating compositions based on derivatives of epoxy resins
-
- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
- C09D5/00—Coating compositions, e.g. paints, varnishes or lacquers, characterised by their physical nature or the effects produced; Filling pastes
- C09D5/03—Powdery paints
- C09D5/033—Powdery paints characterised by the additives
- C09D5/035—Coloring agents, e.g. pigments
Landscapes
- Chemical & Material Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Wood Science & Technology (AREA)
- Organic Chemistry (AREA)
- Paints Or Removers (AREA)
Abstract
The invention relates to a reversible thermochromic epoxy powder coating and a preparation method thereof, wherein the reversible thermochromic epoxy powder coating comprises the following raw material components in parts by weight: 40 to 80 parts of epoxy resin, 5 to 15 parts of curing agent, 0.1 to 5 parts of curing agent accelerator, 1 to 5 parts of leveling agent, 1 to 5 parts of coupling agent, 0.2 to 0.8 part of defoamer and 0.1 to 0.8 part of wetting accelerator; 5 to 20 parts of thermochromic pigment and 5 to 20 parts of other pigments. The thermochromic epoxy powder coating provided by the invention has good leveling property, no pinholes, uniform color distribution and a function of reversibly indicating temperature after being formed into a film; the hardness is high, the scratch resistance is good, the adhesive force is strong, and the acid and alkali resistance is strong; the storage stability is good; no VOC is emitted.
Description
Technical Field
The invention belongs to the field of powder coatings, and particularly relates to a reversible thermochromic epoxy powder coating and a preparation method thereof.
Background
The traditional solvent-based paint has the problem of volatilization of the organic solvent in the baking and curing process, so that the atmospheric pollution and the waste of the organic solvent resource are caused, the health hazard is brought to paint production personnel and coating personnel, and meanwhile, the fire hazard exists in the production, storage, transportation and coating processes of the solvent-based paint. The powder coating is a novel coating which is completely free of organic solvents, is coated in a powder form, is subjected to high-temperature melting, leveling and curing to form a coating, is a 4E type coating product which is recognized to be in line with high production efficiency (efficiency), excellent coating performance (excellence), ecological environment protection (ecology) and economic (ecoom), and is widely applied to various industries such as building materials, automobiles, furniture, ships, household appliances and the like, and is the variety with the fastest development in various coating varieties.
As the functional requirements of powder coatings have increased, thermochromic powder coatings have grown which are capable of producing a color change due to a temperature change. The principle of the thermochromic coating is that when the coating is heated to a certain temperature, substances sensitive to heat in the coating undergo certain physical or chemical changes, so that the molecular structure and the molecular morphology are changed, and even the substances are decomposed into other substances, thereby causing the color change of a coating to indicate the temperature change, and the thermochromic coating can be applied to the fields of temperature measurement and overtemperature alarm of dynamic parts such as aeroengines, shells and the like, heating monitoring of electrical equipment, food fresh-keeping and refrigerating temperature indication, thermochromatic anti-counterfeiting labels, color-changing clothing and the like, and is a fine chemical product with high added value.
The thermochromic powder coating industry faces the challenges of raw material price fluctuation, foreign technical barriers and the like, and related researches are relatively few at present:
1. patent CN201310600785.1 discloses a reversible temperature-indicating powder coating, its preparation method and application method, its formula includes: 70-80 parts of GMA type acrylic resin; 15-25 parts of dodecanedioic acid; 0.6-1 part of leveling agent; 0.2-0.4 part of anti-yellowing benzoin; 2-13 parts of reversible thermochromic pigment; 0.01-5 parts of pigment except reversible thermochromic pigment. The powder coating in the patent shows a specific color at a certain temperature, and instantly changes color when reaching the color changing temperature, and can be used outdoors or indoors, but the acrylic acid powder coating is easy to interfere when being applied in construction, has higher price, and is limited in industrialized popularization and application.
2. Patent CN202111660691.4 discloses a thermochromic powder coating and a preparation method thereof, wherein the formulation comprises: 50.0 to 60.0 percent of carboxyl-terminated polyester resin, 3.3 to 3.8 percent of triglycidyl isocyanurate, 0.1 to 0.2 percent of alumina, 20.0 to 30.0 percent of thermochromic material, 1.0 to 1.5 percent of dispersing agent, 10.0 to 15.0 percent of modified precipitated barium sulfate, 0.5 to 1.0 percent of leveling agent, 0.2 to 0.3 percent of rheological additive, 0 to 0.5 percent of brightening agent, 0.2 to 0.5 percent of benzoin, 0.2 to 1.0 percent of polytetrafluoroethylene and 0 to 3.0 percent of pigment. The formula of the patent has excellent overall compatibility, is not easy to damage the thermochromic material, has obvious color-changing stability and usability, but the storage stability of the polyester resin powder coating is inferior to that of the epoxy powder coating, and the alkali resistance of the coating film is inferior to that of the epoxy powder coating due to ester bonds of the polyester resin, so that the application field of the coating film is limited.
The epoxy resin-based thermochromic powder coating has the problems of poor thermal stability of the thermochromic pigment, easy loss of reversibility of color change at high temperature and incompatibility with other raw materials in the preparation process, unstable color change, uneven color distribution, poor leveling property, pinholes and the like after being cured into a film, so that the preparation of the reversible thermochromic powder coating with excellent performance becomes an urgent market demand.
Disclosure of Invention
The invention aims to overcome the technical defects, and provides a reversible thermochromic epoxy powder coating and a preparation method thereof, which solve the technical problems of poor leveling property and poor storage stability of the epoxy powder coating in the prior art.
In order to achieve the technical purpose, the technical scheme provided by the invention is as follows:
in a first aspect, the invention provides a reversible thermochromic epoxy powder coating, which comprises the following raw material components in parts by weight: 40 to 80 parts of epoxy resin, 5 to 15 parts of curing agent, 0.1 to 5 parts of curing agent accelerator, 1 to 5 parts of leveling agent, 1 to 5 parts of coupling agent, 0.2 to 0.8 part of defoamer and 0.1 to 0.8 part of wetting accelerator; 5 to 20 parts of thermochromic pigment and 5 to 20 parts of other pigments except the thermochromic pigment.
Preferably, the epoxy resin is one or more of phenolic modified epoxy resin, alicyclic epoxy resin, bisphenol a type epoxy resin, hydrogenated bisphenol a type epoxy resin, brominated bisphenol a type epoxy resin, alicyclic glycidyl ether type epoxy resin and alicyclic glycidyl ester type epoxy resin. Among them, epoxy resins are the main film-forming substances of powder coatings, and are the most important components determining the properties and film-coating properties of powder coatings.
Preferably, the curing agent is one or more of dicyandiamide, substituted dicyandiamide, sebacylic dihydrazide and cyclic amidine SPI, and has active groups capable of carrying out crosslinking reaction with active reactive groups such as epoxy groups, hydroxyl groups and the like in the epoxy resin. The epoxy resin is thermosetting resin, so that the epoxy resin and the curing agent are matched with the curing agent, and the resin and the curing agent rapidly undergo a crosslinking curing reaction at a certain baking temperature and time to obtain a coating film with certain physical and mechanical properties and mechanical strength. In the baking and curing process, the curing agent only needs to perform chemical reaction with the resin, but does not perform chemical reaction with the components of other powder coatings such as pigment, filler, auxiliary agent and the like. If too much curing agent is added into the powder coating, the curing speed of the coating is too high, so that defects such as bubbles, cracks and the like appear on the surface of the coating, and the toughness and the adhesive force of the coating are reduced. If too little curing agent is added into the powder coating, the curing speed of the coating is too slow, so that the surface of the coating is not smooth, sagging, dripping and other defects occur, meanwhile, the hardness, the wear resistance and the weather resistance of the coating are reduced, the service life of the coating is influenced, and the energy consumption is high.
Preferably, the curing agent accelerator is one or more of 2-phenylimidazoline, 2-methylimidazole, 2-ethylimidazole, cyclic amidine and triazine compounds.
Preferably, the leveling agent is one or more of acrylate homopolymer, acrylate copolymer, fatty acid leveling agent and organosilicon leveling agent. The leveling agent can form an extremely thin monolayer on the surface of the molten paint to provide uniform surface tension, and simultaneously, the leveling agent also enables the powder paint to have good wettability with a workpiece, so that the defects of pinholes, shrinkage cavities and the like on the surface of a coating film due to uneven local surface tension are overcome. If too little leveling agent is added into the powder coating, the surface of the coating is not smooth, and sagging, dripping and other defects occur; too much leveling agent added to the powder coating material may reduce the storage stability of the powder coating material.
Preferably, the coupling agent is one or more of aluminate coupling agent, silane coupling agent and titanate coupling agent. The coupling agent is more preferably DL411, NDZ-201 or KH-171.
Preferably, the antifoaming agent is benzoin.
Preferably, the wetting enhancer is an acrylate copolymer.
Preferably, the thermochromic pigment is a microcapsule type in which the thermochromic pigment is encapsulated by an Arabic gum emulsion and a bisphenol A type epoxy resin solution.
Further preferably, the purchased thermochromic pigment is emulsified with 6-10% of gum arabic emulsion (distilled water as solvent) at a rotational speed of 200-600 r/min for 0.5-1.5 hours, and then is subjected to intermittent heating and curing with 8-12% of butanone solution of bisphenol A epoxy resin (CYD-011), curing for 3-5 hours at 80-100 ℃ and curing for 1-3 hours at 110-130 ℃ to realize the encapsulation of the thermochromic component by the microcapsule. The mass ratio of the thermochromic pigment to the gum arabic emulsion to the butanone solution of the bisphenol A epoxy resin (CYD-011) is (18-22): 10-15): 100. The thermochromic component is encapsulated by the microcapsule, so that the active component can be isolated, and the stability of the substance is improved.
Further preferably, the thermochromic pigment includes a violet powder type, a brown green type, a red yellow type, or the like; other types of thermochromic pigments can be selected according to the situation, so that multi-color reversible thermochromic can be realized.
Preferably, the other pigment is rutile titanium dioxide.
In a second aspect, the invention also provides a preparation method of the reversible thermochromic epoxy powder coating, which comprises the following steps:
adding all the raw materials into a pulverizer, and fully mixing for 30 seconds to 1 minute to obtain a mixed raw material;
carrying out melt extrusion on the mixed raw materials to obtain a melt extrudate;
and crushing and sieving the melt extrudate to obtain the reversible thermochromic epoxy powder coating.
Preferably, the melt extrusion is performed by adding the mixed raw materials into a twin-screw extruder, and the heating temperature conditions of the twin-screw extruder are as follows: the temperature of the first area is 95-100 ℃, and the temperature of the second area is 85-90 ℃. The first zone is a melting mixing zone of the double-screw extruder, the temperature is higher, the melting of raw materials is facilitated, the fluidity of materials is enhanced, and the materials are fully mixed, so that the color distribution of the powder coating is more uniform, and the materials are conveyed to the second zone. The second area is an extrusion molding area of the double-screw extruder, and the temperature is slightly lower than that of the first area, so that the molding extrusion of the melt is facilitated, and the phenomenon that the extrusion is difficult or the extrusion process is unstable due to excessive melting is avoided.
Preferably, the reversible thermochromic epoxy powder coating can be obtained by crushing the melt extrudate through a crusher and sieving the crushed melt extrudate through a 200-mesh screen.
The curing temperature of the reversible thermochromic epoxy powder coating obtained by the invention is 135+/-5 ℃ and the curing time is 40 minutes.
Compared with the prior art, the invention has the beneficial effects that:
the thermochromic epoxy powder coating provided by the invention has good leveling property, no pinholes, uniform color distribution and a function of reversibly indicating the temperature (reversible color change is more than 500 times) after being formed into a film; the hardness is high, the scratch resistance is good, the adhesive force is strong, and the acid and alkali resistance is strong; the storage stability is good; no VOC is discharged, and the environment is protected.
Drawings
FIG. 1 is a physical diagram of the reversible thermochromic epoxy powder coating prepared in example 1 of the present invention after curing to form a film.
Detailed Description
The present invention will be described in further detail with reference to the drawings and examples, in order to make the objects, technical solutions and advantages of the present invention more apparent. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the scope of the invention.
The epoxy powder coating has low melt viscosity and good leveling property; the epoxy resin has hydroxyl in the molecule, so that the adhesive force to the metal and other substrates is good; the resin matrix has low interference on the color of the powder coating, and the color matching property and powder matching property of the coating are good; the coating adaptability is good, and the application range is wide. However, the thermochromic pigment has poor thermal stability, high-temperature reversibility of easy loss of color change and incompatibility with other raw materials in the preparation process of the epoxy resin-based thermochromic powder coating, so that the problems of unstable color change, uneven color distribution, poor leveling property, pinholes and the like occur after the epoxy resin-based thermochromic powder coating is cured to form a film.
The invention solves the problems by selecting proper raw materials such as thermochromic pigment, epoxy resin, curing agent and the like and optimizing the proportion of the constituent components of the raw materials.
The invention is further illustrated by the following specific examples. The test criteria of the invention are as follows:
impact resistance was tested according to GB/T1732-2020 paint film impact resistance assay;
acid and alkali resistance was tested according to GB 9274-88 determination of liquid Medium resistance of paints and varnishes;
the adhesion was tested according to GB/T9286-2021 cross-hatch test for paint and varnish;
the hardness of the coating was tested according to GB/T6739-2022 paint film hardness determination by the paint and varnish pencil method.
The thermochromic pigment adopted in the invention is microcapsule type. The specific preparation method of the thermochromic pigment in the following examples is as follows: after the purchased thermochromic pigment is emulsified for 1 hour with 8% of gum arabic emulsion at the rotating speed of 400r/min, the thermochromic pigment is subjected to discontinuous heating and curing by using a butanone solution of 10% of bisphenol A epoxy resin (CYD-011), curing for 4 hours at 90 ℃ and curing for 2 hours at 120 ℃ to realize the encapsulation of the thermochromic component by the microcapsule. The mass ratio of the thermochromic pigment to the gum arabic emulsion to the butanone solution of the bisphenol A epoxy resin (CYD-011) is 20:13:100.
Example 1
A reversible thermochromic epoxy powder coating is prepared by the following steps:
the raw material components are weighed according to the following weight portions: 50 parts of phenolic aldehyde modified epoxy resin (JECP-02A), 5 parts of dicyandiamide (Guangzhou Brilliant trade Co., ltd.) 0.1 part of 2-methylimidazole (Wuhanana pharmaceutical chemical Co., ltd.) 4.5 parts of organosilicon leveling agent (H421), 4.5 parts of aluminate coupling agent (DL 411), 0.6 part of benzoin, 0.8 part of acrylic ester copolymer (Jining Sanshi biological science Co., ltd.), 20 parts of thermochromic pigment A (thermochromic pigment is purple powder type, hebei's attention and Kyoku new material science Co., ltd.) and 14.5 parts of rutile type titanium dioxide.
All the weighed raw materials are added into a pulverizer to be fully mixed.
The mixed raw materials are added into a double-screw extruder, and melt extrusion is carried out at the temperature of 100 ℃ in the first area and 90 ℃ in the second area.
The fused extrudate is crushed by a crusher and ground to 200 meshes by a mortar, and the reversible thermochromic epoxy powder coating is obtained by sieving by a screen.
The reversible thermochromic epoxy powder coating prepared in the embodiment is sprayed on an iron sheet polished and wiped by absolute ethyl alcohol in an electrostatic spraying mode, is solidified for 40 minutes at 135+/-5 ℃, and is naturally cooled to room temperature, so that the coating performance is measured, the appearance leveling property is good, the gloss is achieved, and no pinholes are formed.
Referring to FIG. 1, the reversible thermochromic epoxy powder coating of the embodiment is purple at normal temperature, has obvious color change (the purple at 20 ℃ is changed into pink at 31 ℃) after spraying, does not fall off or crack after impact test, has the hardness of 3H, has the acid resistance of more than or equal to 24 hours in 10% sulfuric acid solution, has the alkali resistance of more than or equal to 24 hours in 10% sodium hydroxide solution, and has the reversible color change of more than 500 times.
Example 2
A reversible thermochromic epoxy powder coating is prepared by the following steps:
the raw material components are weighed according to the following weight portions: 68 parts of bisphenol A type epoxy resin (CYD-011), 6.5 parts of substituted dicyandiamide (Guangdong Weng Jiang chemical reagent Co., ltd.), 0.6 part of 2-phenyl imidazoline (Hubei long Xin chemical industry Co., ltd.), 2 parts of fatty acid leveling agent (Guangzhou Sichuan polymerization chemical technology Co., ltd.), 2 parts of phthalate ester coupling agent (NDZ-201), 0.7 part of benzoin, 0.2 part of acrylic ester copolymer (Jining Sanshi biological technology Co., ltd.), 15 parts of thermochromic pigment B (the thermochromic pigment is brown-change green, hebei Kogyo new material technology Co., ltd.) and 5 parts of rutile titanium pigment.
All the weighed raw materials are added into a pulverizer to be fully mixed.
The mixed raw materials are added into a double-screw extruder, and melt extrusion is carried out at the temperature of 95 ℃ in the first area and 85 ℃ in the second area.
The fused extrudate is crushed by a crusher and ground to 200 meshes by a mortar, and the reversible thermochromic epoxy powder coating is obtained by sieving by a screen.
The reversible thermochromic epoxy powder coating prepared in the embodiment is sprayed on a treated metal sheet (an iron sheet polished and wiped by absolute ethyl alcohol) by adopting an electrostatic spraying mode, is solidified for 40 minutes at 135+/-5 ℃, is naturally cooled to room temperature, and is good in appearance leveling property, glossy, free of pinholes, obvious in color change (from brown at 20 ℃ to green at 45 ℃) after being measured, free of falling and cracking after impact test, and has the hardness of 3H, the acid resistance of more than or equal to 24 hours in a 10% sulfuric acid solution, the alkali resistance of more than or equal to 24 hours in a 10% sodium hydroxide solution, and the reversible color change of more than 500 times.
The test criteria were the same as in example 1.
Example 3
The raw material components are weighed according to the following weight portions: 50 parts of alicyclic glycidyl ester type epoxy resin (Shanghai Li Ming chemical Co., ltd.), 22 parts of alicyclic epoxy resin (2021P), 6.5 parts of sebacic acid dihydrazide (Henan Xingding chemical Co., ltd.), 0.5 part of 2-ethylimidazole (Wuhan Hanna white pharmaceutical chemical Co., ltd.), 1 part of acrylic ester homopolymer (GLP 505), 1 part of silane coupling agent (KH-171), 0.2 part of benzoin, 0.8 part of acrylic ester copolymer (Jining Sanshi biological technology Co., ltd.), 7.5 parts of thermochromic pigment C (thermochromic pigment is red-yellow, hebei Kogyo New material Co., ltd.) and 8.7 parts of rutile titanium pigment.
All the weighed raw materials are added into a pulverizer to be fully mixed.
The mixed raw materials are added into a double-screw extruder, and melt extrusion is carried out at the temperature of 95 ℃ in the first area and 85 ℃ in the second area.
The fused extrudate is crushed by a crusher and ground to 200 meshes by a mortar, and the reversible thermochromic epoxy powder coating is obtained by sieving by a screen.
The reversible thermochromic epoxy powder coating prepared in the examples 1-3 is sprayed on a treated metal sheet (an iron sheet polished and wiped by absolute ethyl alcohol) respectively by adopting an electrostatic spraying mode, is solidified for 40 minutes at 135+/-5 ℃, is naturally cooled to room temperature, and is good in coating film performance, good in appearance leveling property, glossy, free of pinholes, obvious in color change (from red at 20 ℃ to yellow at 45 ℃) and free of falling and cracking after impact test, has the hardness of 3H, has the acid resistance of more than or equal to 24 hours in a 10% sulfuric acid solution, has the alkali resistance of more than or equal to 24 hours in a 10% sodium hydroxide solution, and has the reversible color change of more than 500 times.
The test criteria were the same as in example 1.
The results of the above three examples show that the preparation of the multi-color reversible thermochromic epoxy powder coating can be realized according to the combination of different thermochromic pigments, the thermochromic pigments adopted in the examples are only specific description of the invention and are not limiting, and the person skilled in the art can select other thermochromic pigments according to the situation, and the encapsulation of the thermochromic pigments can be realized through the microencapsulation treatment of the invention; meanwhile, bisphenol A type epoxy resin and the like are used as shell materials, so that the epoxy powder coating has good compatibility with other raw material components, and the performance of the epoxy powder coating after coating is not affected while reversible color change is realized; the invention has no VOC emission, is green, safe and environment-friendly, and meets the market demand.
Comparative example 1
The difference from example 1 is that the temperature in the first zone of the twin-screw extruder is 90℃and the temperature in the second zone is 80℃and the other steps and conditions are the same as in example 1.
As a result, it was found that the melt extrudate was mixed with powder solids, the melt mixing was insufficient, the discoloration of the coating film was remarkable (change from purple at 20℃to pink at 31 ℃), but the color distribution was uneven, the leveling property was poor, and the peeling and cracking occurred after impact test. Therefore, in the system of the present invention, the temperature of the first zone is preferably 95 to 100 ℃ and the temperature of the second zone is preferably 85 to 90 ℃ during melt extrusion.
Comparative example 2
The difference from example 2 was that the fatty acid leveling agent was adjusted to 0.2 part and the other pigment except for the thermochromic pigment was 6.8 parts. Other steps and conditions were the same as in example 2.
As a result, it was found that the coating film was significantly discolored (from 20 ℃ C. Brown to 45 ℃ C. Green), but the surface was not smooth, sagging appeared, and peeling and cracking appeared after impact test. It is shown that too little leveling agent is detrimental to the coating properties.
Comparative example 3
The difference from example 1 was that the curing agent accelerator was adjusted to 5.2 parts, the rutile titanium dioxide was 9.6 parts, and the other steps and conditions were the same as in example 1.
As a result, it was found that the coating film was significantly discolored (from purple at 20℃to pink at 31 ℃), but pinholes of a large size were formed on the surface, and the coating film was subjected to an impact test to cause peeling and cracking. Indicating that too much curing agent accelerator is detrimental to coating performance.
The invention provides a reversible thermochromic epoxy powder coating and a preparation method thereof. The reversible thermochromic epoxy powder coating comprises the following raw material components in parts by weight: 40-80 parts of epoxy resin, 5-15 parts of curing agent, 0.1-5 parts of curing agent accelerator, 1-5 parts of leveling agent, 1-5 parts of coupling agent, 0.2-0.8 part of defoamer and 0.1-0.8 part of wetting accelerator; 5-20 parts of thermochromic pigment and 5-20 parts of other pigments except the thermochromic pigment. The thermochromic epoxy powder coating provided by the invention has good leveling property, no pinholes, uniform color distribution and a function of reversibly indicating temperature after being formed into a film; the hardness is high, the scratch resistance is good, and the adhesive force is strong; the storage stability is good; no VOC is discharged, and the environment is protected.
The above-described embodiments of the present invention do not limit the scope of the present invention. Any other corresponding changes and modifications made in accordance with the technical idea of the present invention shall be included in the scope of the claims of the present invention.
Claims (10)
1. The reversible thermochromic epoxy powder coating is characterized by comprising the following raw material components in parts by weight: 40 to 80 parts of epoxy resin, 5 to 15 parts of curing agent, 0.1 to 5 parts of curing agent accelerator, 1 to 5 parts of leveling agent, 1 to 5 parts of coupling agent, 0.2 to 0.8 part of defoamer and 0.1 to 0.8 part of wetting accelerator; 5 to 20 parts of thermochromic pigment and 5 to 20 parts of other pigments.
2. The reversible thermochromic epoxy powder coating of claim 1, wherein the epoxy resin is one or more of a phenolic-modified epoxy resin, a cycloaliphatic epoxy resin, a bisphenol a epoxy resin, a hydrogenated bisphenol a epoxy resin, a brominated bisphenol a epoxy resin, a cycloaliphatic glycidyl ether type epoxy resin, and a cycloaliphatic glycidyl ester type epoxy resin.
3. The reversible thermochromic epoxy powder coating of claim 1, wherein the curing agent is one or more of dicyandiamide, substituted dicyandiamide, sebacoyl hydrazide and cyclic amidine SPI.
4. The reversible thermochromic epoxy powder coating of claim 1, wherein the curing agent accelerator is one or more of 2-phenylimidazoline, 2-methylimidazole, 2-ethylimidazole, cyclic amidine and triazine compounds.
5. The reversible thermochromic epoxy powder coating of claim 1, wherein the leveling agent is one or more of an acrylate homopolymer, an acrylate copolymer, a fatty acid leveling agent, and a silicone leveling agent.
6. The reversible thermochromic epoxy powder coating of claim 1, wherein the coupling agent is one or more of an aluminate coupling agent, a silane coupling agent, and a titanate coupling agent.
7. The reversible thermochromic epoxy powder coating of claim 1, wherein the defoamer is benzoin; the wetting accelerator is an acrylate copolymer.
8. The reversible thermochromic epoxy powder coating according to claim 1, wherein the thermochromic pigment is a microcapsule type in which the thermochromic pigment is encapsulated by an gum arabic emulsion and a bisphenol a type epoxy resin solution, and the specific preparation steps include: stirring and emulsifying the thermochromic pigment by using 6-10% of gum arabic emulsion for 0.5-1.5 hours, and then heating and solidifying the thermochromic pigment by using 8-12% of bisphenol A type epoxy resin solution to obtain the thermochromic pigment; wherein the mass ratio of the thermochromic pigment to the gum arabic emulsion to the bisphenol A type epoxy resin solution is (18-22): 10-15): 100.
9. A process for the preparation of a reversible thermochromic epoxy powder coating according to any of claims 1 to 8, comprising the steps of:
mixing all the raw material components to obtain a mixed raw material;
carrying out melt extrusion on the mixed raw materials to obtain a melt extrudate;
and crushing and sieving the melt extrudate to obtain the reversible thermochromic epoxy powder coating.
10. The method for preparing the reversible thermochromic epoxy powder coating according to claim 9, wherein the melt extrusion is performed by adding the mixed raw materials into a twin-screw extruder, and the heating temperature conditions of the twin-screw extruder are as follows: the temperature of the first region is 95-100 ℃, and the temperature of the second region is 85-90 ℃; the molten extrudate was crushed by a crusher and sieved through a 200 mesh sieve.
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