CN111574951A - Self-skinning modified polyurethane thermosetting sealant composition and preparation method thereof - Google Patents
Self-skinning modified polyurethane thermosetting sealant composition and preparation method thereof Download PDFInfo
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- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
- C09J175/00—Adhesives based on polyureas or polyurethanes; Adhesives based on derivatives of such polymers
- C09J175/04—Polyurethanes
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- C08G18/00—Polymeric products of isocyanates or isothiocyanates
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- C08G18/28—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen characterised by the compounds used containing active hydrogen
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- C08G18/00—Polymeric products of isocyanates or isothiocyanates
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- C08G18/28—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen characterised by the compounds used containing active hydrogen
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- C08G18/00—Polymeric products of isocyanates or isothiocyanates
- C08G18/06—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen
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- C08G18/72—Polyisocyanates or polyisothiocyanates
- C08G18/74—Polyisocyanates or polyisothiocyanates cyclic
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- C08G18/00—Polymeric products of isocyanates or isothiocyanates
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- C08G18/7664—Polyisocyanates or polyisothiocyanates cyclic aromatic containing two or more aromatic rings containing alkylene polyphenyl groups
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- C09J11/00—Features of adhesives not provided for in group C09J9/00, e.g. additives
- C09J11/02—Non-macromolecular additives
- C09J11/04—Non-macromolecular additives inorganic
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Abstract
The invention discloses a self-skinning modified polyurethane thermosetting sealant composition and a preparation method thereof, wherein the self-skinning modified polyurethane thermosetting sealant composition comprises the following components in parts by weight: the coating comprises 15-40 parts of isocyanate-based polyurethane prepolymer, 5-20 parts of epoxy resin, 2-10 parts of modified polyurethane prepolymer, 0.2-5 parts of thermal curing agent or accelerator, 10-25 parts of plasticizer, 0.3-2 parts of water removing agent, 10-40 parts of filler, 3-20 parts of rheological additive, 0.1-10 parts of dye or pigment, 0.2-3 parts of latent curing agent and 0.01-1 part of catalyst. The invention has good adhesion with metal plate, can quickly form strength, has excellent mechanical property, does not foam when heated, is stable to store and is suitable for being used as the sealant of the automobile body framework.
Description
Technical Field
The invention relates to the field of polyurethane thermosetting sealants, in particular to a self-skinning modified polyurethane thermosetting sealant composition and a preparation method thereof.
Background
In the framework construction of vehicles, the individual metal sheets are connected to one another, and in order to prevent corrosion as much as possible, the framework metal sheets are subjected to electrophoretic and paint-spraying treatments, which play an important role in the corrosion resistance of automobiles and can extend the service life of the vehicles.
For the general position of the car body, the electrophoretic fluid and the baking varnish coating can play a good role in protecting, but in the section position of some plates, the coating is very little, and the service life of the car body is often reduced by the positions. At present, for the positions of vehicle body processing cutting, seam and welding seam, joint filling materials are generally used for sealing and waterproofing, high-temperature treatment is needed for electrophoresis and spray painting, and the common polyurethane sealing material can bubble after being baked at high temperature, so that the paint surface is cracked. In order to solve the problem, the common sealant in the market at present is mainly an organosilicon modified polyether sealant, although the sealant can resist higher temperature, the finishing property of the sealant is inferior to that of a polyurethane sealant, the sealant can be peeled from a paint surface, the skinning and curing time is long, and the process operation is complex. In addition, a PVC sealant is used for sealing a welding line, but the sealant cannot be self-cured, needs heating treatment and has higher requirements on a use position and a process, and the common low-end PVC sealant has poor flexibility, can cause water leakage when used at a high-displacement position, influences the durability of a vehicle body, and generates micromolecular gas to be harmful to a human body after being baked. The pot life problem exists for two-component products, and the special equipment required in the use process also increases the production cost.
Disclosure of Invention
Aiming at the defects in the prior art, the invention provides the self-skinning modified polyurethane thermosetting sealant composition and the preparation method thereof, the self-skinning modified polyurethane thermosetting sealant composition has good bonding with a metal plate, can quickly form strength, has excellent mechanical properties, does not foam when heated, is stable in storage, and is suitable for being used as a sealant for the automobile body framework.
The purpose of the invention is realized by the following technical scheme:
the self-skinning modified polyurethane thermosetting sealant composition comprises the following components in parts by weight:
wherein the isocyanate group-containing polyurethane prepolymer is prepared by reacting a polyol-containing compound with an isocyanate compound; the polyol-containing compound is at least one of polyether polyol, polyester polyol, polycarbonate polyol, polyacrylate polyol and polyhydrocarbon polyol; the isocyanate compound is at least one of an aromatic polyisocyanate or an aliphatic polyisocyanate.
Preferably, the isocyanate group-containing polyurethane prepolymer is prepared by reacting polyether polyol and diisocyanate according to the NCO/OH molar ratio of 1.2-5.
Preferably, the epoxy resin is one of diglycidyl ether of bisphenol a, diglycidyl ether of bisphenol F, diglycidyl ether of bisphenol a/F, 1, 2, 3-glycerol diglycidyl ether, and polyethylene glycol diglycidyl ether.
Preferably, the modified polyurethane prepolymer is an epoxy modified polyurethane prepolymer obtained by modifying and synthesizing the isocyanate group-containing polyurethane prepolymer by using an epoxy group-containing small molecular compound, and the NCO content is lower than 0.2 wt%;
wherein the epoxy group-containing small molecule compound has a chemical structure of:
Preferably, the thermal curing agent or accelerator is one of dicyandiamide, guanamine, guanidine, aminoguanidine and derivatives thereof, organic acid hydrazide, Lewis acid salt amine complex, polyamine salt and complex of aromatic amine and inorganic salt.
Preferably, the plasticizer is at least one of phthalic acid esters, phosphoric acid esters, adipic acid esters, sulfonic acid esters, sulfonamides, and chlorinated paraffins.
Preferably, the water removal agent is one of isocyanate-terminated compounds, triethyl orthoformate, oxazolidine water removal agents, molecular sieve drying agents, calcium oxide and silane water removal agents.
Preferably, the filler is one of mica, talc, kaolin, wollastonite, feldspar, syenite, chlorite, bentonite, montmorillonite, calcium carbonate, dolomite, quartz, calcined silica, precipitated silica, cristobalite, calcium oxide, aluminum hydroxide, magnesium oxide, ceramic hollow spheres, glass hollow spheres, organic hollow spheres, glass beads, carbon black.
Preferably, the rheological aid is a thickener or thixotropic agent.
Preferably, the dye or pigment is one or a combination of titanium dioxide, carbon black, iron oxide red, iron oxide yellow and iron blue.
Preferably, the latent curing agent is one of aldimine, ketimine and bisoxazolidine;
preferably, the catalyst is an organotin compound, an amine, a bismuth compound, a morpholino compound or an imidazole derivative.
A preparation method of the self-skinning modified polyurethane thermosetting sealant composition comprises the following steps:
step 1, dehydrating a polyol-containing compound and a plasticizer, adding an isocyanate compound, reacting for 2-3 h at 60-80 ℃, adding a catalyst, continuing to react for 1-2 h, adding an epoxy resin, continuing to react until the NCO content reaches 0.8-2.5%, and stopping reacting to obtain a blend of an isocyanate-containing polyurethane prepolymer and the epoxy resin;
and 2, adding a mixture containing isocyanate-based polyurethane prepolymer and epoxy resin, modified polyurethane prepolymer and plasticizer into a stirring kettle, adding dye or pigment for dispersing for 0.5-1 h, then adding a thermal curing agent or accelerator, a water removing agent, a filler, a rheological aid and a latent curing agent, stirring for 10-15 min, and uniformly stirring to obtain the self-skinning modified polyurethane thermosetting sealant composition.
According to the technical scheme provided by the invention, the self-skinning modified polyurethane thermosetting sealant composition with a wet-heat dual-curing mechanism is formed by adopting the polyurethane prepolymer containing isocyanate groups, epoxy resin, modified polyurethane prepolymer, a heat curing agent or an accelerator, a plasticizer, a water removing agent, a filler, a rheological aid, a dye or a pigment, a latent curing agent and a catalyst in a specific ratio; the self-skinning modified polyurethane thermosetting sealant composition can be cured with moisture at room temperature to quickly form skinning with certain strength, can also be thermally cured to form elastomer sealant under heating conditions, has excellent mechanical properties, does not bubble when heated after electrophoresis/spray painting, has excellent bonding properties and stable storage, and is suitable for being used as an automobile body framework sealant.
Detailed Description
The technical solutions in the present invention are clearly and completely described below, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments of the present invention without making any creative effort, shall fall within the protection scope of the present invention.
The self-skinning modified polyurethane thermosetting sealant composition and the preparation method thereof provided by the present invention are described in detail below. Details not described in the present invention are well known to those skilled in the art.
The self-skinning modified polyurethane thermosetting sealant composition comprises the following components in parts by weight:
specifically, the self-skinning modified polyurethane heat-curable sealant composition includes the following embodiments:
(1) the isocyanate group-containing polyurethane prepolymer is prepared by reacting a polyol-containing compound with an isocyanate compound. The polyol-containing compound is at least one of polyether polyol, polyester polyol, polycarbonate polyol, polyacrylate polyol and polyhydrocarbon polyol; the compound containing the polyol is preferably polyether polyol or polyester polyol, and is preferably polyether polyol with the molecular weight of 1000-8000, and most of the polyether polyol is bifunctional polyether polyol and trifunctional polyether polyol. The isocyanate compound is at least one of aromatic polyisocyanate or aliphatic polyisocyanate; the isocyanate compound is preferably diisocyanate, and more preferably Toluene Diisocyanate (TDI), diphenylmethane diisocyanate (MDI), Hexamethylene Diisocyanate (HDI), isophorone diisocyanate (IPDI). In practical application, the isocyanate group-containing polyurethane prepolymer is preferably prepared by reacting polyether polyol and diisocyanate according to a molar ratio of NCO/OH of 1.2-5 (preferably 1.5-3), and the content of residual free isocyanate groups in the isocyanate group-containing polyurethane prepolymer obtained after the reaction is 0.8-2.5%.
(2) The epoxy resin is one of diglycidyl ether of bisphenol A (DGEBA), diglycidyl ether of bisphenol F, diglycidyl ether of bisphenol A/F, 1, 2, 3-glycerol dehydrated glycerol ether and polyethylene glycol diglycidyl ether; the epoxy resin is preferably a diglycidyl ether of bisphenol A. The blend of the isocyanate-based polyurethane prepolymer and the epoxy resin not only has isocyanate groups, but also contains epoxy groups.
(3) The modified polyurethane prepolymer is obtained by modifying and synthesizing the isocyanate group-containing polyurethane prepolymer by using an epoxy group-containing small molecular compound, and the NCO content is lower than 0.2 wt%;
wherein the epoxy group-containing small molecule compound has a chemical structure of:
(4) The curing agent in the thermal curing agent or the accelerator is dicyandiamide, guanamine, guanidine, aminoguanidine and derivatives thereof, organic acid hydrazide, Lewis acid salt amine complex (BCl 3-diethylamine complex), polyamine salt and one of aromatic amine and inorganic salt complex, in particular dicyandiamide with the particle size of 5-9 mu m; in addition, accelerators having a curing action may be substituted, such as substituted ureas, imidazoles and imidazolium salts, imidazolines, amidoamines (phthalic anhydride and diethylenetriamine 1:1 addition), preferably N, N-dimethylurea. The thermal curing agent or accelerator can be stable with the epoxy resin at room temperature, and can be activated to react with the epoxy resin at the rising temperature, and the activation temperature is generally higher than 120 ℃.
(5) The plasticizer is at least one of phthalate, phosphate, adipate, sulfonate, sulfonamide and chlorinated paraffin.
(6) The water removal agent is one of isocyanate-terminated compounds, triethyl orthoformate, oxazolidine water removal agents, molecular sieve drying agents, calcium oxide and silane water removal agents; the water scavenger is preferably methyl benzenesulfonyl isocyanate (PTSI).
(7) The filler is one of mica, talc, kaolin, wollastonite, feldspar, syenite, chlorite, bentonite, montmorillonite, calcium carbonate, dolomite, quartz, calcined or precipitated silica, cristobalite, calcium oxide, aluminum hydroxide, magnesium oxide, ceramic hollow spheres, glass hollow spheres, organic hollow spheres, glass beads and carbon black.
(8) The rheological additive is a thickening agent or a thixotropic agent; the rheological aid is preferably a polyurea compound, a polyamide wax, bentonite or fumed silica, and most preferably a hydrophobic fumed silica.
(9) The dye or pigment is one or a combination of titanium dioxide, carbon black, iron oxide red, iron oxide yellow and iron blue.
(10) The latent curing agent is one of aldimine, ketimine and bisoxazolidine; the latent curing agent is preferably aldimine.
(11) The catalyst is an organotin compound (e.g., dibutyltin diacetate, dibutyltin dilaurate, stannous octoate, dibutyltin dichloride, dibutyltin diacetylacetonate and dioctyltin dilaurate), an amine (e.g., triethylenediamine), a bismuth compound (e.g., bismuth trioctoate), a morpholino compound (e.g., dimorpholinodiethylether) or an imidazole derivative (e.g., 1, 2-dimethylimidazole).
Furthermore, the preparation method of the self-skinning modified polyurethane thermosetting sealant composition can be divided into three steps, wherein in the first step, a blend containing isocyanate-based polyurethane prepolymer and epoxy resin is synthesized; secondly, synthesizing a modified polyurethane prepolymer; and thirdly, preparing the self-skinning modified polyurethane heat-curing sealant composition by using the compositions in the first two steps. The method specifically comprises the following steps:
and A, dehydrating polyether polyol and a plasticizer, adding polyisocyanate, reacting for 2-3 h at 60-80 ℃, adding a catalyst, continuing to react for 1-2 h, adding epoxy resin, continuing to react until the NCO content reaches 0.8-2.5%, and stopping reacting to obtain the isocyanate group-containing polyurethane prepolymer and epoxy resin blend.
And step B, dehydrating polyether glycol and a plasticizer, adding diisocyanate, reacting for 2-3 h at 60-80 ℃, adding a catalyst, continuing to react for 1-2 h, adding a small molecular compound containing an epoxy group, continuing to react for 2-3 h, and stopping reacting until the NCO content is lower than 0.2%, thereby preparing the modified polyurethane prepolymer.
And step C, adding a mixture containing isocyanate-based polyurethane prepolymer and epoxy resin, modified polyurethane prepolymer and plasticizer into a stirring kettle, adding dye or pigment for dispersing for 0.5-1 h, then adding a thermal curing agent or accelerator, a water removing agent, a filler, a rheological aid and a latent curing agent, stirring for 10-15 min, and uniformly stirring to obtain the self-skinning modified polyurethane thermosetting sealant composition.
The self-skinning modified polyurethane thermosetting sealant composition provided by the invention has a wet-heat dual-curing mechanism: the first heavy curing mechanism is that the isocyanate group-containing polyurethane prepolymer is in contact reaction with water in the air, so that the surface of the polyurethane prepolymer forms crusts, the polyurethane prepolymer can be moved without damaging adhesive tapes, and is not easy to be stained with dust, and the appearance of a paint film of a vehicle body is not influenced; the second curing mechanism is that when the baking process is carried out after paint spraying, the epoxy resin in the self-skinning modified polyurethane thermosetting sealant composition can be completely cured by high-temperature heating (120-190 ℃) to form a high-mechanical-strength sealing rubber strip without bubbles. Meanwhile, the modified polyurethane prepolymer in the self-skinning modified polyurethane thermosetting sealant composition can be used as a bridge of epoxy resin and polyurethane, so that a stable IPN network structure is formed after the epoxy resin and the polyurethane polymer are cured, and the heat resistance and the mechanical property of the self-skinning modified polyurethane thermosetting sealant composition are improved. In addition, the modified polyurethane prepolymer can reduce the viscosity and improve the storage stability of the self-skinning modified polyurethane thermosetting sealant composition. The self-skinning modified polyurethane thermosetting sealant composition is particularly suitable for use as a sealant for the construction of the frame of a vehicle body.
The automobile body framework is complex in construction process, and often needs to move in a short time after a metal plate is bonded and sealed, so that the sealant needs to form strength quickly; meanwhile, electrophoresis and paint spraying usually need higher temperature, bubbles cannot be generated in the process, otherwise, the formed bubbles not only reduce the mechanical property of the sealant, but also have great influence on the appearance, and especially, the outer coating paint film can amplify internal defects and influence the attractiveness. The self-skinning modified polyurethane thermosetting sealant composition provided by the invention is well bonded with a metal plate, can quickly form strength, and does not generate bubbles during heating.
In actual use, if bubbles are formed during the curing process of the sealant composition, the mechanical properties of the sealant composition are affected, and the appearance is greatly affected, especially during the later paint film covering process, uneven appearance is more prominent due to the colored paint. The self-skinning modified polyurethane thermosetting sealant composition provided by the invention adopts a damp-heat dual-curing mechanism, and can rapidly form skinning at room temperature, so that the painted surface is more complete and attractive, gas is not generated in the thermosetting process, and colloid bubbling is avoided; in addition, the elastomer strength of the self-skinning modified polyurethane thermosetting sealant composition after thermosetting is obviously improved, and the sealant composition is beneficial to later-stage moving processing.
The self-skinning modified polyurethane thermosetting sealant composition provided by the invention has excellent storage stability, is suitable for framework sealing before automobile assembly line electrophoresis and paint spraying, and is particularly suitable for weld seam sealing before engine compartments, vehicle doors, luggage compartments and paint spraying.
In conclusion, the embodiment of the invention has the advantages of good bonding with the metal plate, rapid forming of strength, excellent mechanical property, no foaming during heating, stable storage and suitability for being used as the automobile body framework sealant.
In order to more clearly show the technical solutions and the technical effects provided by the present invention, the self-skinning modified polyurethane thermosetting sealant composition and the preparation method thereof provided by the embodiments of the present invention are described in detail by the following specific examples.
The following formula (unit is weight portion) in the following table 1 is adopted in the inventive examples 1-3 and the comparative examples 1-2:
TABLE 1
| Example 1 | Examples2 | Example 3 | Comparative example 1 | Comparative example 2 | |
| Polyether polyol 330N | 12.8 | 12.8 | 12.8 | 12.8 | 12.8 |
| Polyether polyol DL-2000 | 6.4 | 6.4 | 6.4 | 6.4 | 6.4 |
| Diphenylmethane diisocyanate (MDI) | 4 | 4 | 4 | 4 | 4 |
| Diglycidyl ether of bisphenol A (DGEBA) | 7.4 | 7.4 | 7.4 | 7.4 | 7.4 |
| Polyether diol N210 | 2.4 | 2.4 | 4 | 2.4 | |
| Toluene Diisocyanate (TDI) | 0.6 | 0.6 | 1 | 0.6 | |
| Epoxypropanol | 0.16 | 0.16 | 0.25 | 0.16 | |
| Water scavenger PTSI | 0.3 | 0.3 | 0.3 | 0.3 | 0.3 |
| Dicyandiamide | 1.0 | 1.0 | 1.0 | ||
| Amidoamines | 2.0 | ||||
| N, N-dimethyl urea | 1.0 | ||||
| Plasticizer DIDP | 16 | 16 | 16 | 16 | 16 |
| Aldimines | 1.2 | 1.2 | 1.2 | 1.2 | |
| Calcium oxide | 3.7 | 3.7 | 3.7 | 3.7 | 3.7 |
| Thixotropic agent SiO2 | 7.0 | 7.0 | 7.0 | 7.0 | 7.0 |
| Calcium carbonate | 30.4 | 28.4 | 28.4 | 34.8 | 31.4 |
| Titanium white powder | 5.6 | 5.6 | 5.6 | 5.6 | 5.6 |
| Dibutyltin dilaurate solution | 1.0 | 1.0 | 1.0 | 1.0 | 1.0 |
In the above table 1, the dibutyltin dilaurate solution is a solution obtained by diluting dibutyltin dilaurate to 10% with DIDP.
Example 1
The preparation method of the self-skinning modified polyurethane thermosetting sealant composition can comprise the following steps:
step a1, preparing a blend of isocyanate group-containing polyurethane prepolymer and epoxy resin:
adding polyether polyol 330N, polyether polyol DL-2000 and a plasticizer DIDP into a reaction kettle, heating to 120 ℃, carrying out vacuum dehydration for 2h, then cooling to 60-80 ℃, adding diphenylmethane diisocyanate (MDI), reacting for 2-3 h, adding a catalyst (dibutyltin dilaurate DBTDL diluted to a solution of 10% by using the plasticizer DIDP), continuing to react for 1-2 h, then adding diglycidyl ether of bisphenol A (DGEBA) while stirring, stirring for 1-2 h at 80 ℃, stopping the reaction until the NCO content reaches 1.8%, thus obtaining the isocyanate-containing polyurethane prepolymer and epoxy resin blend.
Step a2, preparing a modified polyurethane prepolymer:
adding polyether glycol N210 and a plasticizer DIDP into a reaction kettle, heating to 120 ℃, carrying out vacuum dehydration for 2h, then cooling to 60-80 ℃, adding Toluene Diisocyanate (TDI), reacting for 2-3 h, adding a catalyst (dibutyltin dilaurate DBTDL is diluted to a 10% solution by the plasticizer DIDP), continuing to react for 1-2 h, then adding epoxy propanol while stirring, stirring for 2-3 h at 80 ℃, stopping the reaction until the NCO content is lower than 0.2%, and thus obtaining the modified polyurethane prepolymer.
Step a3, preparing the self-skinning modified polyurethane heat-curable sealant composition:
adding the blend containing isocyanate-based polyurethane prepolymer and epoxy resin prepared in the step a1, the modified polyurethane prepolymer prepared in the step a2, a plasticizer DIDP into a stirring kettle, adding titanium dioxide, vacuumizing, dispersing and stirring for 0.5-1 h, and then adding dicyandiamide, a water removing agent PTSI, calcium oxide, calcium carbonate and a thixotropic agent SiO2And mixing with aldimine, stirring for 10-15 min, and uniformly stirring to obtain the self-skinning modified polyurethane thermosetting sealant composition. The self-skinning modified polyurethane heat-curable sealant composition was filled into an aluminum tube.
Example 2
A self-skinning modified polyurethane thermosetting sealant composition, which is substantially the same as that of example 1 of the present invention, except that: the amounts of the starting materials used are different and amidoamine and N, N-dimethylurea are used instead of dicyandiamide in step a 3.
Example 3
A self-skinning modified polyurethane thermosetting sealant composition, which is substantially the same as that of example 1 of the present invention, except that: the dosage of each raw material is different.
Comparative example 1
A polyurethane heat-curable sealant composition, which can be prepared by a method comprising the steps of:
step d1 is the same as step a1 in example 1 of the present invention.
D2, adding the blend of isocyanate group-containing polyurethane prepolymer and epoxy resin prepared in the step d1 and a plasticizer DIDP into a stirring kettle, adding titanium dioxide, vacuumizing, dispersing and stirring for 0.5-1 h, and then adding dicyandiamide, a water removing agent PTSI, calcium oxide, calcium carbonate and a thixotropic agent SiO2And stirring for 10-15 min, and uniformly stirring to obtain the polyurethane thermosetting sealant composition.
Comparative example 2
A polyurethane heat-curable sealant composition, which can be prepared by a method comprising the steps of:
step e1 was the same as step a1 in inventive example 1.
Step e2 was the same as step a2 in inventive example 1.
Step e3, adding the blend containing isocyanate-based polyurethane prepolymer and epoxy resin prepared in the step e1, the modified polyurethane prepolymer prepared in the step e2 and a plasticizer DIDP into a stirring kettle, adding titanium dioxide, vacuumizing, dispersing and stirring for 0.5-1 h, and then adding a water removing agent PTSI, calcium oxide, calcium carbonate and a thixotropic agent SiO2And mixing with aldimine, stirring for 10-15 min, and uniformly stirring to obtain the polyurethane thermosetting sealant composition.
Performance detection
The following performance tests were performed on examples 1 to 3 of the present invention and comparative examples 1 to 2:
(1) carrying out colloid bubbling and bonding test; scrape 100 × 15mm × 2mm strips on the plate. After being placed in a thermostatic chamber (23 ℃, 50% relative air humidity) for 120min, the electrophoresis plate is placed in a 160 ℃ oven to be heated for 40min, then the electrophoresis plate is placed at room temperature, the adhesive tape is cut by a knife and stripped at 180 ℃, the adhesive tape bonding and appearance state is recorded, if the appearance is spongy and has a large amount of bubbles, the recording is unqualified, and if the appearance is less than 80% cohesive failure, the recording is unqualified.
(2) The time for the colloid to crust; in a thermostatic chamber, the skinning time was tested according to GB/T13477.5-2002.
(3) Colloidal storage stability: the strip was placed in a 60 ℃ oven, the viscosity and initial viscosity were recorded for 14 days, the rate of change of viscosity was calculated and above 100% was recorded as unacceptable.
(4) Mechanical properties of the colloid; the strip was placed in an oven at 160 ℃ and, after baking, tested for tensile strength and elongation at break according to GB 528.
The results are shown in table 2 below:
TABLE 2
In Table 2 above, CF represents cohesive failure and greater than 90% CF represents good adhesion; a viscosity change rate after aging within 100% is acceptable; the mechanical property data of comparative example 2 were measured under ambient curing conditions.
As can be seen from table 2 above: compared with comparative examples 1-2, the self-skinning modified polyurethane thermosetting sealant composition provided by the invention has the advantages that the bonding between the self-skinning modified polyurethane thermosetting sealant composition provided by the invention 1, the self-skinning modified polyurethane thermosetting sealant composition provided by the invention 2 and a base material is good, no air bubbles exist, the mechanical properties of the self-skinning modified polyurethane thermosetting sealant composition are excellent, the self-skinning modified polyurethane thermosetting sealant composition is completely cured after being baked at high temperature and has higher hardness, the self-skinning modified polyurethane thermosetting sealant composition provided by the invention is suitable for being used as a sealant before electrophoresis and paint spraying processes in an automobile manufacturing process.
In conclusion, the embodiment of the invention has the advantages of good bonding with the metal plate, rapid forming of strength, excellent mechanical property, no foaming during heating, stable storage and suitability for being used as the automobile body framework sealant.
The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present invention are included in the scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.
Claims (10)
1. The self-skinning modified polyurethane thermosetting sealant composition is characterized by comprising the following components in parts by weight:
wherein the isocyanate group-containing polyurethane prepolymer is prepared by reacting a polyol-containing compound with an isocyanate compound; the polyol-containing compound is at least one of polyether polyol, polyester polyol, polycarbonate polyol, polyacrylate polyol and polyhydrocarbon polyol; the isocyanate compound is at least one of an aromatic polyisocyanate or an aliphatic polyisocyanate.
2. The self-skinning modified polyurethane thermosetting sealant composition according to claim 1, wherein the isocyanate group-containing polyurethane prepolymer is prepared by reacting polyether polyol and diisocyanate at a molar ratio of NCO/OH of 1.2 to 5.
3. The skinned modified polyurethane thermosetting sealant composition of claim 1 or 2, wherein the epoxy resin is one of diglycidyl ether of bisphenol a, diglycidyl ether of bisphenol F, diglycidyl ether of bisphenol a/F, 1, 2, 3-glycerol anhydroglycidyl ether, and polyethylene glycol diglycidyl ether.
4. The self-skinning modified polyurethane thermosetting sealant composition according to claim 1 or 2, wherein the modified polyurethane prepolymer is an epoxy modified polyurethane prepolymer synthesized by modifying the isocyanate group-containing polyurethane prepolymer with an epoxy group-containing small molecular compound, and the NCO content is less than 0.2 wt%;
wherein the epoxy group-containing small molecule compound has a chemical structure of:
5. The skinned modified polyurethane thermosetting sealant composition of claim 1 or 2, wherein the thermal curing agent or accelerator is one of dicyandiamide, guanamine, guanidine, aminoguanidine and derivatives thereof, organic acid hydrazide, Lewis acid salt amine complex, polyamine salt and complex of aromatic amine and inorganic salt.
6. The self-skinning modified polyurethane thermosetting sealant composition of claim 1 or 2, wherein the plasticizer is at least one of phthalic acid esters, phosphoric acid esters, adipic acid esters, sulfonic acid amides, and chlorinated paraffin.
7. The self-skinning modified polyurethane thermosetting sealant composition of claim 1 or 2, wherein the water scavenger is one of isocyanate terminated compounds, triethyl orthoformate, oxazolidine water scavengers, molecular sieve driers, calcium oxide, silane based water scavengers.
8. The self-skinning modified polyurethane thermoset sealant composition of claim 1 or 2, wherein the filler is one of mica, talc, kaolin, wollastonite, feldspar, syenite, chlorite, bentonite, montmorillonite, calcium carbonate, dolomite, quartz, fumed silica, precipitated silica, cristobalite, calcium oxide, aluminum hydroxide, magnesium oxide, ceramic hollow spheres, glass hollow spheres, organic hollow spheres, glass beads, carbon black.
9. The self-skinning modified polyurethane thermosetting sealant composition of claim 1 or 2, wherein the rheological aid is a thickener or thixotropic agent;
the dye or pigment is one or a combination of titanium dioxide, carbon black, iron oxide red, iron oxide yellow and iron blue;
the latent curing agent is one of aldimine, ketimine and bisoxazolidine;
the catalyst is organic tin compound, amine, bismuth compound, morpholinyl compound or imidazole derivative.
10. A preparation method of the self-skinning modified polyurethane thermosetting sealant composition is characterized by comprising the following steps:
step 1, dehydrating a polyol-containing compound and a plasticizer, adding an isocyanate compound, reacting for 2-3 h at 60-80 ℃, adding a catalyst, continuing to react for 1-2 h, adding an epoxy resin, continuing to react until the NCO content reaches 0.8-2.5%, and stopping reacting to obtain a blend of an isocyanate-containing polyurethane prepolymer and the epoxy resin;
step 2, adding a mixture containing isocyanate-based polyurethane prepolymer and epoxy resin, modified polyurethane prepolymer and plasticizer into a stirring kettle, adding dye or pigment for dispersing for 0.5-1 h, then adding a thermal curing agent or accelerator, a water removing agent, a filler, a rheological aid and a latent curing agent, stirring for 10-15 min, and uniformly stirring to obtain the self-skinning modified polyurethane thermosetting sealant composition of any one of claims 1-9.
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