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WO2013090988A1 - Produits d'étanchéité photodurcissables sur demande - Google Patents

Produits d'étanchéité photodurcissables sur demande Download PDF

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Publication number
WO2013090988A1
WO2013090988A1 PCT/AU2012/001545 AU2012001545W WO2013090988A1 WO 2013090988 A1 WO2013090988 A1 WO 2013090988A1 AU 2012001545 W AU2012001545 W AU 2012001545W WO 2013090988 A1 WO2013090988 A1 WO 2013090988A1
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WIPO (PCT)
Prior art keywords
sealant
cure
formulation according
formulation
light
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
PCT/AU2012/001545
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English (en)
Inventor
Stuart Bateman
Shirley Shen
Januar GOTAMA
Tri Nguyen
Kelly Clark
Weidong Yang
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Commonwealth Scientific and Industrial Research Organization CSIRO
Boeing Co
Original Assignee
Commonwealth Scientific and Industrial Research Organization CSIRO
Boeing Co
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Application filed by Commonwealth Scientific and Industrial Research Organization CSIRO, Boeing Co filed Critical Commonwealth Scientific and Industrial Research Organization CSIRO
Publication of WO2013090988A1 publication Critical patent/WO2013090988A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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Classifications

    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
    • C09K3/00—Materials not provided for elsewhere
    • C09K3/10—Materials in mouldable or extrudable form for sealing or packing joints or covers
    • C09K3/1006—Materials in mouldable or extrudable form for sealing or packing joints or covers characterised by the chemical nature of one of its constituents
    • C09K3/1012—Sulfur-containing polymers, e.g. polysulfides
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
    • C09K3/00—Materials not provided for elsewhere
    • C09K3/10—Materials in mouldable or extrudable form for sealing or packing joints or covers
    • C09K2003/1034—Materials or components characterised by specific properties
    • C09K2003/1068—Crosslinkable materials

Definitions

  • the present invention relates to formulations and cure methodologies which enable a sealant to be cured on demand.
  • the invention provides a sealant with optionally long shelf and work life and optionally rapid cure kinetics following the cure trigger event.
  • Sealants are used in many industry sectors for example building and construction, mining and in transport for use in aircraft, automotive vehicles and marine craft.
  • the physical and chemical properties of the sealant may be tuned through design of the sealant polymer chemistry and through the use of additives in the formulation to meet the desired performance requirements, for example, to obtain suitable rheological properties for deployment, cure kinetics, bond strength to the substrate, mechanical properties and chemical resistance.
  • Application and performance properties relevant to many industry sectors including aerospace sealants are specified and may be assessed practically according to relevant standards.
  • sealants are of critical importance to the construction of modern aircraft - for example to obtain
  • Sealant formulations are supplied commercially in many formats to cater to a diverse range of deployment and application requirements. This includes:
  • Polysulfide and/or polythioether based sealants may be formulated to cure at room temperature through the use of cure catalysts such as manganese dioxide and lead oxide which convert the thiol end groups to sulfide based linkages. Chlorates, dichromates and organic and inorganic peroxides have also been employed for this purpose. Considering that thiols can participate in both addition and substitution reactions, cure may also proceed through reaction with epoxy resins such as those based on glycidyl ethers of bisphenol A, bisphenol F and the like. The cure chemistries are described in Lowe, Int. J. Adhesion and Adhesives, 17, (1997), p345 and Clark and Cosman, Int. J. Adhesion and Adhesives, 23, (2003), p343.
  • Typical sealant formulations like those based on polysulfide chemistries comprise two part kits - Part A containing the pre-polymer(s) and/or monomer(s) such as Thiokol LP polysulfide prepolymer and optionally other additives and Part B containing the curing agent such as manganese dioxide and optionally other additives.
  • the two components are separated by packaging to achieve sufficient shelf life prior to deployment. When the two components are mixed sealant work life begins, and sealant work life ends when the properties of the sealant [such as its rheological properties] are no longer suitable for the application method. Once deployed, the sealant continues to cure reaching a tack free point at an intermediate cure and then ultimate hardness following full cure.
  • the cure rate can be slowed by freezing to allow a suitable shelf life.
  • Work life begins on thawing of the sealant to provide reduced viscosity for deployment and increased cure kinetics.
  • the amount of active catalyst, accelerators such as tertiary amines and retarders such as stearic acid are often employed to modify work life and cure rate.
  • Increased cure rate decreases work life and the time required to reach a tack free state and ultimate hardness. Decreased cure rate increases work life and the time to reach tack free and ultimate hardness.
  • changes in cure rate may also alter the cross-link network formed.
  • the cure rate and usable work life of such sealants is defined by their cure chemistry, and cure begins once the sealant prepolymer and/or monomer is mixed with the curing agent.
  • sealants formulated for fast tack free times e.g. 2hrs
  • formulations and methods to cure sealants on demand hence overcoming the inherent limitation of conventional methods to cure them.
  • the formulations and methods decouple sealant work time from cure rate to provide a sealant with optionally long work life and following the trigger event, optionally rapid cure kinetics.
  • the formulations and methods are useful in the storage and deployment of sealants without compromising their performance once cured.
  • a light triggered cure on demand sealant formulation which comprises
  • component (a) being capable of generating reactive species such as free radicals when the formulation is subjected to a light trigger.
  • the sealant formulation further comprises
  • the light trigger is affected by exposure of the formulation to actinic radiation containing light.
  • the sealant formulation may also comprise (d) reinforcements and/or fillers and (e) other additives.
  • the sealant formulation is in the form of a kit in which components (a) and (b) and optionally (c), (d) and (e) are held separately or two or more of the components are held together.
  • a method for the preparation of the cure on demand sealant formulation defined above which comprises combining components (a) and (b) and optionally (c), (d) and (e).
  • a method of curing the sealant formulation defined above which comprises subjecting the sealant formulation to a light source as a means to trigger cure of the formulation.
  • a cured sealant formulation prepared by the method defined in the third aspect above.
  • a substrate which is wholly or partly coated or sealed with the cure on demand sealant formulation defined in the first aspect above or the cured sealant formulation defined in the fourth aspect above.
  • the application generally relates to cure on demand sealant formulations which are receptive to, and activated by a light-based triggering event to initiate cure.
  • Sealant formulation
  • Preferred sealant formulations are sealants which incorporate sulfur into their polymer backbone and have free thiol groups such as polysulfides and/or polythioethers, monomers, blends or derivatives thereof.
  • Non-limiting examples of polysulfide prepolymers and/or monomers are described in US 2466963 and US 5610243, while non-limiting examples of polythioether prepolymers and/or monomers are described in WO 02/02710 and US 6509418, the entire contents of which are incorporated herein by reference.
  • the sealant is a polysulfide such as a Thiokol polysulfide having the following general formula: HS-(C2H4-0-CH2-0-C2H4- ⁇ S-S ⁇ 2-6)x-C2H4-0-CH2-0-C 2 H4-SH in which x is 1 to 200.
  • a polysulfide such as a Thiokol polysulfide having the following general formula: HS-(C2H4-0-CH2-0-C2H4- ⁇ S-S ⁇ 2-6)x-C2H4-0-CH2-0-C 2 H4-SH in which x is 1 to 200.
  • the sealant prepolymers and/or monomers may include other functional groups such as but not limited to those disclosed in WO 02/0271 1 and US 5610243, the entire contents of which are incorporated herein by reference. These functional groups may assist in the cure on demand mechanism. Examples include double bonds such as vinyl, acryl and methacryl groups.
  • the sealant prepolymer and/or monomer may be present in an amount of up to about 99% based on the total weight of the formulation. It will be appreciated that this amount will vary depending on the amount of reinforcements and/or fillers and other additives present in the formulation.
  • the sealant formulation containing the prepolymer(s) and/or monomer(s) described above may also contain one or more non-polysulfide or non-polythioether prepolymer(s) and/or monomer(s).
  • non-polysulfide or non- polythioether prepolymers include polyamides and phenolic resins.
  • Non-limiting examples of non-polysulfide or non-polythioether monomer(s) include silane derivatives such as aminosilane epoxysilane and diglycidyl derivatives such as bisphenol A diglycidyl ether.
  • Cure of the sealant is facilitated through a source of unsaturation such as double or triple bonds which may be carbon based with the crosslinked structure manipulated through the use of mono-, di-, tri- and/or tetra- unsaturated functional species.
  • a source of unsaturation such as double or triple bonds which may be carbon based with the crosslinked structure manipulated through the use of mono-, di-, tri- and/or tetra- unsaturated functional species.
  • the general cure is based on thiol - ene chemistries.
  • the source of unsaturation is a double bond "ene" crosslinker having a molecular weight in the range of 100 to 5000.
  • a molecular weight range of 100 to 1000 is preferred.
  • the thiol-ene mole ratio has an impact on curing and the crosslinked network structure following exposure to the light trigger.
  • the ene component ranges from 0.7 to 1.5 mols per per mol of thiol. More preferably, the ene component ranges from 0.95 to 1.1 per mol of thio. Most preferably, the thiol-ene mole ratio is 1 : 1.
  • the sealant formulation may also comprise reinforcements and/or fillers such as calcium carbonate, silica, clays, carbon black and mica in an amount of up to about 50% based on the total weight of the formulation.
  • reinforcements and/or fillers such as calcium carbonate, silica, clays, carbon black and mica in an amount of up to about 50% based on the total weight of the formulation.
  • the sealant formulation may further comprise other additives.
  • Additives used in sealant formulations will be known to the person skilled in the art as described in WO 02/02710.
  • Non-limiting examples of additives include other polymers such as polyamides and phenolic resins; plasticizers such as phthalate esters, chlorinated parrafins and hydrogenated terphenyls; moisture scavengers; adhesion promoters and coupling reagents such as phenolics, organosilanes (e.g. epoxy, mercapto or amino functional silanes such as vinyl silane and
  • the sealant formulation may also comprise a photosensitizer to assist in the cure on demand mechanism. While not wishing to be bound by any theory, it is believed that the presence of a photodecane (trimethoxy silane), titanates, and zirconates; retarders such as stearic acid; accelerators such as amines (e.g. DABCO (4- diazabicyclo[2.2.2]octane), diphenyl guanidine and triethylamine); non-ionic and ionic surfactants; and solvents to achieve the required deployment characteristics and cure performance.
  • the other additives may be present in an amount in the range of up to about 20% based on the total weight of the formulation.
  • the sealant formulation may also comprise a photosensitizer to assist in the cure on demand mechanism. While not wishing to be bound by any theory, it is believed that the presence of a photodecane (trimethoxy silane), titanates, and zirconates; retarders such as stearic acid; accelerator
  • photosensitizer in a polysulfide sealant pre-polymer or monomers thereof during exposure to the light trigger will improve the rate of crosslinking due to a greater efficiency of thiyl radical formation.
  • Non-limiting examples of photosensitizers include acylphosphine oxides such as Irgacure 819 and/or keto based photosensitizers such as Darocure 1 173.
  • Irgacure 819 is an example of a type I photosensitizer which means that it is capable of forming free radicals which then abstract thiol protons from polysulfide sealants when exposed to actinic radiation.
  • Darocure 1 173 is an example of a type II photosensitizer which forms an excited triplet state that subsequently undergoes bimolecular reactions with other species to generate free radicals.
  • the amount of photosensitizer employed can affect both the rate and depth of cure.
  • the photosensitizer may be present in an amount of up to 5% based on the total weight of the formulation.
  • the sealant formulation comprises
  • the sealant formulation comprises
  • the sealant formulation may be prepared by combining at least two of components (a) and (b) and optionally (c), (d) and (e) and packaging at some point prior to application.
  • the components (a) and (b) and optionally (c), (d) and (e) of the sealant formulation may be packaged separately or two or more of the components held together in one or more compartments such as in the form of a kit and then combined prior to or during the sealant being deployed.
  • the sealant formulation or the components thereof may be deployed by any suitable known methods such as but not limited to extrusion, injection, pumping, spatulation, spraying, brushing, rolling, and/or filleting. Preferred methods of deployment include injection, extrusion, filleting and spraying.
  • a light trigger initiates cure of the sealant formulation.
  • Application of the trigger may take place prior to, at some point during and/or throughout cure of the sealant formulation.
  • the light trigger may also be applied intermittently.
  • the light trigger may be applied by any means known to those skilled in the art at ambient or elevated temperatures.
  • the light trigger may be actinic radiation in one or more of the ultraviolet, visible or near infrared spectral ranges.
  • Examples of light sources include those available commercially from suppliers such as Fusion.
  • the intensity (for example the power) can be tuned to the requirements of the application and the sealant formulation.
  • the cure rate of the sealant formulation may be altered to meet the application requirements via modification of the components of the sealant formulation and/or the trigger event.
  • the cure time may range from 0.1 to 600 seconds of light exposure depending on the application method, formulation and thickness of the sealant required.
  • Such processes may include sealant surface treatment, painting, bonding, and the like.
  • Surface treatment may include mechanical or chemical treatment to change the topography and/or chemistry of the sealant surface.
  • the sealant may also be bonded to another entity or via application of an adhesive to the surface or the modified sealant surface.
  • the sealant may also be painted with coating layers such as but not limited to primers and topcoats. Additional layers of sealant may also optionally be applied to the sealant formulation. One or more of the additional layers may be composed of a conventional or a cure on demand sealant formulation defined above.
  • the substrate to which the sealant is applied is not of consequence, although the cure on demand formulation may be tuned to specifically meet the requirement of the substrate.
  • the substrates may be bare or coated and composed of one or more different types of materials such as but not limited to metals such as steel, stainless steel, aluminum and titanium and anodized, primed, organic coated and chromate coated forms thereof; plastics such as thermoplastics including polyolefins, polyamides, polyesters, polycarbonates, polyketones, polysulfones, polyimides and thermosetting plastics such as those based on epoxy, urethane, imide, vinylester, acrylic and polyester; composite materials such as but not limited to plastics incorporating reinforcements such as carbon and/or glass fibre, inorganic fillers, graphite, fiberglass composite and KEVLAR ® ; other sealants; coated materials where the coating in contact with the sealant is a primer and/or a topcoat; and naturally derived materials such as wood and cotton.
  • the substrate for which the sealant is used may find
  • Fig. 1 is a graph showing the change in viscosity following UV irradiation of Thiokol LP2 with a commercial UV light source
  • Fig. 2 is a graph showing the change in viscosity following UV irradiation of Thiokol LP2 with Irgacure 819;
  • Fig. 3 is a graph showing change in viscosity of Thiokol LP2 with DEGDVE before and after UV exposure;
  • Fig. 4 are photographs showing the impact of UV exposure times on photosensitized thiol-ene model sealant formulations
  • Fig. 5 is a graph showing the change in viscosity of Thiokol LP2, Igracure 819 and DEGDVE in the absence of UV light;
  • Fig. 6 is a graph showing DSC result of Tg for the mixture after UV curing for 60 seconds or 300 seconds;
  • Fig. 7 are graphs showing FTIR spectra of photosensitized "thiol-ene” formulations with different exposure to UV light;
  • Fig. 8 is a graph showing FTIR spectra of various specimens prepared with constant "Thiol” content and varying "Ene” content;
  • Fig. 9 are graphs showing FTIR result for different initiator loadings when exposed to UV for 300 seconds using 4 mm thick samples;
  • Fig. 10 is a graph showing TG of Thiokol LP2: DEGDVE formulation incorporating different Irgacure 819 photoinitiator loadings (note Tg taken from the mid point of the transition);
  • Fig. 1 1 are graphs showing FTIR result of samples with different thickness
  • Fig. 12 are reactive schemes showing modification of terminal thio groups of Thiokol LP2 to incorporate points of unsaturation
  • Fig. 13 are graphs showing FTIR showing the impact of micron sized CaC0 3 in the Irgacure 819 sensitized photo-cure of Thiokol LP2:DEGDVE;
  • Fig. 14 is a graph showing Tg of Thiokol LP2:DEGDVE formulations with and without micron sized CaC0 3 filler (note Tg taken from the mid point of the transition);
  • Fig. 15 is a graph showing UV Vis transmission spectrum through a borosilicate glass filter
  • Fig. 16 is a graph showing UVA is absorption spectrum of Irgacure 819 at different concentrations
  • Fig. 17 are graphs showing FTIR spectra of samples photocured in the presence of a glass filter
  • Fig. 18 is a graph showing stability of Thiokol LP2 + DEGDVE + Igracure 819 at 104F (40°C) over a week;
  • Fig. 19 is a graph showing stability of Thiokol LP2 + DEGDVE + Igracure 819 at 122F (50°C) over a week;
  • Fig. 20 is a graph showing peel energy vs peel length for adhesion promoters in photosensitized thiol-ene cured LP2;
  • Fig. 21 is a graph showing 180° peel test result for model sealant formulations
  • Fig. 22 is a graph showing DSC results of the five benchmark samples.
  • Thiokol polysulfides (generalised structure below) were out of Toray supplied by Swift and company Australia.
  • the LP2 grade was employed for the experiments which incorporated 2mol% branching reagent in its synthesis to provide an overall thiol content of 2.0% per the certificate of analysis (COA) from Toray, its mole weight is 4000, its viscosity at 25°C is 45 Pa-s, and its simplified structure is shown below.
  • COA certificate of analysis
  • DDSA DDSA surfactant
  • polysulfide based formulations Prior to polymerisation, polysulfide based formulations were combined manually or employing a speed mixer (model DAC 400 FVZ) taking care to protect the photo-active formulations from strong light sources.
  • the latter mixing technique not only provided efficient mixing via the high centrifugal forces produced but also an efficient means to eliminate entrapped air.
  • powdered initiators were first dissolved in THF to facilitate uniform mixing with the viscous polysulfide with the solvent subsequently removed with a vacuum pump prior to polymerisation.
  • Moulds for conducting photopolymerization of liquid precursors were prepared from a silicone sheet bonded to a glass plate. A maximum of four cavities were used per polymerisation run to ensure uniform light exposure to all cavities. Light exposure of the liquid formulations was completed using a FUSION UV curing unit fitted with a H+ bulb with a maximum emmittance at 365nm. To limit sample heating the curing duration was limited to a maximum of 60s interval blocks or as appropriate.
  • Rheological properties were assessed using a HAAKE RheoStress RS 600 Rheometer, utilising 20mm round parallel plates. Approximately one gram of sample was required to fill the 0.5mm gap distance between the plates. Testing was completed either at a constant shear rate or alternatively across a shear rate range of 0.1-10 s " at temperatures indicated (between 30 and 70°C).
  • the surface hardness was measured by a digital Shore A hardness durometer, supplied by Instron once a sample had cured. An average hardness from five different locations was taken on both top surface and bottom surface as appropriate (eg relevant for light exposed samples). Dwell time was set at 1.7 seconds.
  • FTIR Fourier transform infrared spectroscopy
  • FTIR analysis was carried out on a Bruker model Equinox 55 FTIR using golden gate ATR type attachment. Scan ranges of 400-4000cm "1 were employed.
  • DSC Differential scanning calorimetry
  • Tg Glass transition temperature values of a cured polysulfide sample were measured using a TA instruments MDSC (model 2920), under nitrogen flow. A ramp rate of 10°C/min was employed between -120°C and room temperature on the second thermal cycle. Tg values are taken from the mid-point of the thermal transition. 180° Peel test
  • the peel test specimen was manufactured on an aluminium substrate primed with Akzo-Nobel 10P20-44 primer and the mould template as outlined below and the assembly was cured with actinic radiation.
  • Direct exposure to light at wavelengths around 250nm may result in the formation of disulfide crosslinks from thiol based precursors via a thiyl radical based pathway.
  • Thiokol LP2 the polysulfide prepolymer was exposed to unfiltered light from a Fusion H+ bulb and the rheology measured over time as a test for cure. Viscosity results provided in Fig. 1 demonstrated that there was no significant change in rheology after exposure of the system to the light source and hence no cure within the time period and for the light intensities explored.
  • a photosensitizer to Thiokol LP2 during light exposure was anticipated to improve the rate of crosslinking due to the greater efficiency of thiyl radical formation.
  • Acylphosphine oxides such as Irgacure 819 is a known class of photosensitizer which has been previously employed to photocure filled materials such as pigmented coatings and glass-fibre reinforced resins.
  • the reagent may be formulated as a one component initiator but also has been used successfully in combination with other keto based photosensitizers such as Darocure 1 173 to cure thick slab sections.
  • Irgacure 819 decomposes under light to form free radicals directly (so called type I photosensitizer with the free radical thus generated capable of abstracting thiol protons at effectively diffusion controlled transfer rates).
  • type II initiators eg Darocure BP often in conjunction with amines
  • Fig. 2 illustrates that a slight reduction in viscosity was provided by dispersion of the photosensitizer into Thiokol LP2 whilst an increase in viscosity was provided upon exposure of the system to light.
  • no "solid" polysulfide sealant was formed under the experimental conditions employed just a marginal increase in viscosity to the liquid precursors presumably due to some chain extension.
  • the strategy by itself would not be expected to have practical value to cure sulfur containing sealants like those based polysulfide or polythioether chemistries unless much higher intensity light was employed.
  • Table 2 shows the impact of UV light on specimens incorporating a 1 :1 thiohene ratio as calculated from the certificate of analysis for thiol content and a 2phr loading of Irgacure 819.
  • Ten seconds of UV exposure cured 1 mm thick samples, whereas irradiation for 180 seconds cured a 4 mm thick slab.
  • Fig 4 provides photos of the "fully" cured materials following exposure of the thiol-ene formulations to light.
  • Glass transition values (Tg) quoted as the mid point of the transition (Fig. 6) were obtained for thiol-ene formulations exposed to light for various time periods. Thicker (eg 4mm) and thinner (1 mm) samples could be cured using the
  • Fig. 7 provides FTIR spectral data of selected samples discussed in Table 2. Absorptions from the DEGDVE double bonds (Vinyl -1620 & 1640 cm-1 ) disappeared after sufficient exposure to light. Naturally shorter irradiation times could be achieved by higher intensity light sources or by application of the light during the pumping (extrusion) of the sealant system through a transparent cell or tube of small diameter. Impact of Formulation and Cure Conditions
  • Thiol-ene mole ratio impacts the cure mechanism and hence the network structure formed following light exposure.
  • Preliminary results suggested that a 1 :1 thiol : ene mole ratio [based on the Thiokol certificate of analysis (COA)] was suitable which is consistent with a potential theoretical cure mechanism.
  • COA Thiokol certificate of analysis
  • Fig. 8 shows the FTIR result from exposing different formulations to UV light for 300 seconds. At higher thiol to ene ratios there was some evidence that vinyl moieties remained unreacted following light exposure.
  • Figs. 9 and 10 show preliminary FTIR and thermal analysis (Tg) results of formulations incorporating different Irgacure 819 loadings, respectively.
  • vinyl groups could not be identified after 300 seconds irradiance when Irgacure 819 was present at 2 phr, although residual vinyl was noted primarily with a 0.5phr but also just identifiable at a 1 phr loading.
  • glass transition temperature higher concentrations of Irgacure 819 resulted in a higher glass transition temperature which suggests a higher crosslink density, although it should be noted that there was only a marginal shift in the value obtained between 1 and 2phr photosensitizer. This result is mirrored in the hardness values obtained, which is also known to be dependent on crosslink density (Table 4).
  • Thiokol LP2 is effectively crosslinked by shorter chain dienes using photoactivated thiol-ene chemistry.
  • Calcium Carbonate (CaC0 3 ) is a conventional filler employed widely in sealants to both extend the sealant (reduce cost) and (potentially) to provide the required physical properties eg mechanical performance.
  • unfilled Thiokol LP2: DEGDVE formulations could be cured in slab thicknesses of up to 12mm, it was anticipated that the addition of solid fillers would scatter (block) the light penetrating the specimen to effectively reduce the cure depth achieved.
  • a dual cure mechanism could be used to achieve full thickness cure in these instances.
  • UV light to trigger cure in production must consider worker occupational health and safety. Although UV light may be readily blocked by conventional safety glasses and appropriate clothing, removal of the shorter and arguably more dangerous wavelengths (below 300nm) is highly desirable.
  • One common method to achieve this is to place a filter between the source and the specimen with glass filters effectively blocking out wavelengths less than about 300nm (Fig. 15).
  • Irgacure 819 has a number of additional peak absorptions between 200 and 450nm (Fig. 16). Whilst the intensity of each absorption maxima decreases with increasing wavelength this class of photo-sensitizer provides some activity even into the visible wavelength regions.
  • Fig. 17 provides images and FTIR data of 4mm thick Thiokol LP2 - DEGDVE formulations incorporating 2phr Irgacure 819 cured with glass-filtered and unfiltered light sources.
  • solid materials were formed following 300 second irradiation times, although in the case of specimens prepared under filtered light hardness values were marginally lower and the FTIR spectrum indicated that residual vinyl groups remained compared with the specimen cured under unfiltered lighting conditions. This suggests that the curing efficiency and hence rate is lower which is expected considering that the available light source would naturally lead to a lower free radical flux and require higher intensity light to achieve similar kinetics.
  • UV trigger and photosensitizer assisted thiol-ene model system was shown to be stable up to 21 days at room temperature.
  • Figs. 18 and 19 present rheology test results at 104F and 122F respectively for up to one week.
  • Table 13 compares viscosity data of Thiokol LP2 incorporating the light trigger and photosensitizer assisted thiol-ene cure system compared to pure LP2 (without any additives) at a shear rate of 1 (s-1 ). The viscosity stays reasonably stable at 104F and 122F up to one week, even though viscosity of a mixture is lower than that of neat LP2 due to the presence of the DEGDVE.
  • glycidyl(oxy)propyltrimethoxy silane with epoxy functional group was added. Without wishing to be limited by theory it was considered that such reagents would co-cure into the sealant during the thiol-ene crosslinking reaction.
  • Peel forces were measured using standard Instron methodologies and the peel energy was calculated and plotted as in Fig. 20. The results show that an addition of only 1 .5 phr adhesion promoter increased the peel energy by about 15%.
  • Model sealant formulations were analysed for performance. This included physical properties such as thermal properties (Tg, thermal resistance); and adhesion to common materials (180° peel test);
  • Sample 1 commercial sealant AC770B2 (based on a polysulfide chemistry with Mn0 2 curative));
  • the base process of manufacturing the sealant slabs involves curing under light for the photocurable formulations or under the manufacturer recommended conditions for conventionally cured materials.
  • DSC results for the five samples are shown in Fig. 22.
  • the five formulations were shown to all have T g values around -57°C (-71 F) suitable for numerous low temperature applications such as that required by aerospace or infrastructure application in cold regions.

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Abstract

La présente invention concerne des formulations et des procédés de durcissement permettant de durcir sur demande un produit d'étanchéité. La formulation du produit d'étanchéité photodurcissable sur demande comprend (a) un ou plusieurs prépolymère(s) pour produit d'étanchéité durcissable ou un ou plusieurs monomère(s) correspondant(s) ; et (b) une source d'insaturation pour faciliter la réticulation qui est séparée de et/ou intégrée au composant (a), le composant (a) étant capable de générer des espèces réactives telles que des radicaux libres lorsque la formulation est soumise à un déclencheur lumineux. L'invention concerne en particulier un produit d'étanchéité pouvant avoir une longue durée de conservation et d'utilisation et pouvant avoir une cinétique de durcissement rapide après activation du durcissement.
PCT/AU2012/001545 2011-12-22 2012-12-17 Produits d'étanchéité photodurcissables sur demande Ceased WO2013090988A1 (fr)

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Cited By (11)

* Cited by examiner, † Cited by third party
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EP3106488A1 (fr) 2015-06-19 2016-12-21 Université de Haute Alsace Polymérisation oxydante catalysée par photobase de poly (disulfure)s
WO2018005416A1 (fr) 2016-06-30 2018-01-04 3M Innovative Properties Company Composition de thiol-ène à double durcissement, comprenant un polythiol, un composé insaturé, un photoinitiateur et un hydroperoxyde organique, ainsi qu'un agent d'étanchéité polymère réticulé préparé à partir de cette dernière destiné à être utilisé dans le domaine aérospatial
WO2018075902A1 (fr) * 2016-10-21 2018-04-26 Basf Se Composition de matériau d'étanchéité durcissable
US10072135B2 (en) 2013-12-30 2018-09-11 3M Innovative Properties Company Compositions including a polythiol, an unsaturated compound, and a dye and methods relating to such compositions
US10233307B2 (en) 2013-12-30 2019-03-19 3M Innovative Properties Company Dye, filler made therefrom, compositions including the filler, and method of determining degree of cure of such compositions
US10246557B2 (en) 2015-12-01 2019-04-02 The Boeing Company pH sensitive quantum dots for use as cure indicators
WO2019064103A1 (fr) 2017-09-26 2019-04-04 1/1 Ok3M Innovative Properties Company Compositions d'étanchéité durcissables, capuchon d'étanchéité, et leurs procédés de fabrication et d'utilisation
US10703906B2 (en) 2014-12-23 2020-07-07 3M Innovative Properties Company Dual cure polythioether
US10745558B2 (en) 2015-06-29 2020-08-18 3M Innovative Properties Company Compositions including a polythiol, an unsaturated compound, and a dye and methods relating to such compositions
EP3256541B1 (fr) 2015-02-13 2022-11-16 Chemetall GmbH Procédé pour l'application d'une masse d'étanchéité contenant du soufre, dispositif à cet effet, et son utilisation
US12415942B2 (en) 2021-10-22 2025-09-16 Nano And Advanced Materials Institute Limited Light or heat triggered frontally cured cure-on-demand adhesives kit

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US10072135B2 (en) 2013-12-30 2018-09-11 3M Innovative Properties Company Compositions including a polythiol, an unsaturated compound, and a dye and methods relating to such compositions
US10968332B2 (en) 2013-12-30 2021-04-06 3M Innovative Properties Company Dye, filler made therefrom, compositions including the filler, and method of determining degree of cure of such compositions
US10233307B2 (en) 2013-12-30 2019-03-19 3M Innovative Properties Company Dye, filler made therefrom, compositions including the filler, and method of determining degree of cure of such compositions
US11319440B2 (en) 2014-12-23 2022-05-03 3M Innovative Properties Company Dual cure polythioether
US10703906B2 (en) 2014-12-23 2020-07-07 3M Innovative Properties Company Dual cure polythioether
EP3256541B1 (fr) 2015-02-13 2022-11-16 Chemetall GmbH Procédé pour l'application d'une masse d'étanchéité contenant du soufre, dispositif à cet effet, et son utilisation
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EP3106488A1 (fr) 2015-06-19 2016-12-21 Université de Haute Alsace Polymérisation oxydante catalysée par photobase de poly (disulfure)s
US10745558B2 (en) 2015-06-29 2020-08-18 3M Innovative Properties Company Compositions including a polythiol, an unsaturated compound, and a dye and methods relating to such compositions
US10246557B2 (en) 2015-12-01 2019-04-02 The Boeing Company pH sensitive quantum dots for use as cure indicators
US11072687B2 (en) 2015-12-01 2021-07-27 The Boeing Company pH sensitive quantum dots for use as cure indicators
WO2018005416A1 (fr) 2016-06-30 2018-01-04 3M Innovative Properties Company Composition de thiol-ène à double durcissement, comprenant un polythiol, un composé insaturé, un photoinitiateur et un hydroperoxyde organique, ainsi qu'un agent d'étanchéité polymère réticulé préparé à partir de cette dernière destiné à être utilisé dans le domaine aérospatial
US11041049B2 (en) 2016-06-30 2021-06-22 3M Innovative Properties Company Dual curable thiol-ene composition, comprising a polythiol, an unsaturated compound, a photoinitiator and an organic hydroperoxide, as well as a cross-linked polymer sealant prepared therefrom for use in aerospace
WO2018075902A1 (fr) * 2016-10-21 2018-04-26 Basf Se Composition de matériau d'étanchéité durcissable
WO2019064103A1 (fr) 2017-09-26 2019-04-04 1/1 Ok3M Innovative Properties Company Compositions d'étanchéité durcissables, capuchon d'étanchéité, et leurs procédés de fabrication et d'utilisation
US12415942B2 (en) 2021-10-22 2025-09-16 Nano And Advanced Materials Institute Limited Light or heat triggered frontally cured cure-on-demand adhesives kit

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