Dual cure compositions, methods of curing thereof and articles therefrom

Abstract

Disclosed herein are dual cure compositions, methods to cure dual cure compositions, the dual cure compositions comprising at least one filler, at least one curable monomer comprising at least one of an ethylenic unit or cyclic ether unit or mixture thereof; at least one photoinitiator; and at least one thermal initiator. The method comprises the step of photocuring by exposing the compositions to radiation to at least partially photocure the composition, which in turn generates an exotherm which initiates thermal curing. The methods may be used to make cured thick compositions and sandwich structures. Articles made by the methods are also described.

1 . A dual cure composition having structural units derived from a composition comprising: 
 at least one UV opaque filler;    at least one curable monomer comprising at least one ethylenic unit or cyclic ether unit or mixture thereof;    at least one photoinitiator; and    at least one thermal initiator.    
   
   
       2 . The composition of  claim 1 , wherein the UV opaque filler is selected from the group consisting of carbon fibers, carbon black, carbon nanotubes, silicon carbide, boron nitride, titanium dioxide, zirconium oxide, chalk, calcium sulfate, barium sulfate, calcium carbonate, silicates, talc, mica, kaolin, silica, aluminum hydroxide, magnesium hydroxide, polymer powder, polymer fiber, and mixtures thereof.  
   
   
       3 . The composition of  claim 1 , wherein the curable monomer is selected from the group consisting of an unsaturated polyester, a vinyl ester, an acrylate, a methacrylate, a diacrylate, a dimethacrylate, a multifunctional acrylate, a multifunctional methacrylate, an epoxide, an oxetane, a multifunctional epoxide, a multifunctional oxetane, and mixtures thereof.  
   
   
       4 . The composition of  claim 1 , wherein the photoinitiator comprises an organic peroxide, an azo compound, a quinone, a benzophenone, a nitroso compound, an acryl halide, a hydrozone, a mercapto compound, a pyrylium compound, a triacrylimidazole, a bisimidazole, a chloroalkyltriazine, a benzoin ether, a benzil ketal, a thioxanthone an acetophenone, an acylphosphine oxide, an onium salt, a derivative of one of the aforementioned compounds, or mixtures thereof.  
   
   
       5 . The composition of  claim 1 , wherein the photoinitiator is present in a range of from about 0.01 weight percent to about 20 weight percent, based on the weight of the curable monomer.  
   
   
       6 . The composition of  claim 1 , wherein the filler is present in a range of from about 1 weight percent to about 90 weight percent, based on the total weight of the composition.  
   
   
       7 . The composition of  claim 1 , wherein the thermal initiator comprises benzoyl peroxide, dicumyl peroxide, methyl ethyl ketone peroxide, lauryl peroxide, cyclohexanone peroxide, t-butyl hydroperoxide, t-butyl benzene hydroperoxide, t-butyl peroctoate, 2,5-dimethylhexane-2,5-dihydroperoxide, 2,5-dimethyl-2,5-di(t-butylperoxy)-hex-3-yne, di-t-butylperoxide, t-butylcumyl peroxide, α,α′-bis(t-butylperoxy-m-isopropyl)benzene, 2,5-dimethyl-2,5-di(t-butylperoxy)hexane, di(t-butylperoxy) isophthalate, t-butylperoxy benzoate, 2,2-bis(t-butylperoxy)butane, 2,2-bis(t-butylperoxy)octane, 2,5-dimethyl-2,5-di(benzoylperoxy)hexane, di(trimethylsilyl)peroxide, trimethylsilylphenyltriphenylsilyl peroxide, 2,3-dimethyl-2,3-diphenylbutane, 2,3-trimethylsilyloxy-2,3-diphenylbutane, copper(II) acetylacetonate, palladium(II) acetylacetonate, ruthenium(III) acetylacetonate, an onium salt, a sulfonium salt, an iodonium salt, or mixtures thereof.  
   
   
       8 . The composition of  claim 1 , wherein the thermal initiator is present in a range of from about 0.01 weight percent to about 10 weight percent based on the weight of the curable monomer.  
   
   
       9 . The composition of  claim 1 , further comprising at least one additive selected from the group consisting of photosensitizers, pigments, tackifiers, UV transparent fillers, and mixtures thereof.  
   
   
       10 . A method of curing a dual cure composition comprising the steps of: 
 (i) providing a dual cure composition comprising: 
 at least one filler;  
 at least one curable monomer comprising at least one of an ethylenic unit or cyclic ether unit or mixture thereof;  
 at least one photoinitiator; and  
 at least one thermal initiator;  
   (ii) exposing the composition to radiation of a wavelength made available from a radiation source to at least partially photocure the composition and to provide an exotherm sufficient to complete the curing of the composition by thermal curing; and (iii) then turning off the radiation source before complete curing is achieved.    
   
   
       11 . The method of  claim 10 , wherein the radiation comprises a radiation wavelength sufficient to provide the exotherm.  
   
   
       12 . The method of  claim 11 , wherein the radiation wavelength is in the range of from about 200 nanometers to about 1000 nanometers.  
   
   
       13 . The method of  claim 10 , wherein the exposing occurs for a time sufficient to provide the exotherm.  
   
   
       14 . The method of  claim 10 , wherein the exposing occurs for a time period in the range of from about 1 second to about 5 hours.  
   
   
       15 . The method of  claim 10 , wherein the composition is fully cured.  
   
   
       16 . An article made by the method of  claim 10 .  
   
   
       17 . An article with thickness greater than 1 centimeter made by the method of  claim 10 .  
   
   
       18 . A body panel, truck bed, protective plate, fender, spoiler, hood, door, lamp reflector, sanitary article, household implement, house door, house window, furniture, coil, container, radiator, electric motor coil, a wind rotor blade for wind turbine, an aerospace article, a bridge component, a marine article, a sporting goods article, a pipe, or a missile component made by the method of  claim 10 .  
   
   
       19 . A method of making a cured dual cure composition comprising the steps of: 
 (i) providing a dual cure composition comprising: 
 at least one filler comprising glass fibers, fumed silica, or combinations thereof;  
 at least one curable monomer comprising at least one of an ethylenic unit or cyclic ether unit or mixture thereof;  
 at least one photoinitiator; and  
 at least one thermal initiator; and  
   (ii) exposing the dual cure composition to radiation of a wavelength made available from a radiation source to at least partially photocure the composition, and to provide an exotherm sufficient to initiate thermal curing to form a cured composition; wherein the cured composition is at least 6 millimeters thick.    
   
   
       20 . The method of  claim 19 , wherein the radiation source is turned off before complete curing is achieved.  
   
   
       21 . A method of making a cured dual cure composition comprising: 
 (i) providing a dual cure composition comprising: 
 at least one UV opaque filler comprising carbon fibers, carbon black, carbon nanotubes, silicon carbide, boron nitride, titanium dioxide, zirconium oxide, chalk, calcium sulfate, barium sulfate, calcium carbonate, silicates, talc, mica, kaolin, silica, aluminum hydroxide, magnesium hydroxide, polymer powder, polymer fiber, or combinations thereof;  
 at least one curable monomer comprising at least one of an ethylenic unit or cyclic ether unit or mixture thereof;  
 at least one photoinitiator; and  
 at least one thermal initiator; and  
   (ii) exposing the dual cure composition to radiation of a wavelength made available from a radiation source to at least partially photocure the composition, and to provide an exotherm sufficient to initiate thermal curing to form a cured composition; wherein the cured composition is at least 0.1 millimeter thick.    
   
   
       22 . The method of  claim 21 , wherein the radiation source is turned off before complete curing is achieved.  
   
   
       23 . A method of curing a dual cure sandwich structure comprising the steps of: 
 (i) providing a dual cure composition comprising: 
 at least one reinforcing filler core comprising foam, slitted foam, wood, honeycomb, or combinations thereof;  
 at least one curable monomer comprising at least one of an ethylenic unit or cyclic ether unit or mixture thereof;  
 at least one photoinitiator; and  
 at least one thermal initiator; and  
   (ii) exposing the dual cure composition to radiation of a wavelength made available from a radiation source to at least partially photocure the composition, and to provide an exotherm sufficient to initiate thermal curing to form a cured composition.    
   
   
       24 . The method of  claim 23 , wherein the radiation source is turned off before complete curing is achieved.  
   
   
       25 . A method of curing a dual cure composition comprising the steps of: 
 (i) providing a dual cure composition comprising: 
 at least one filler;  
 at least one curable monomer comprising a vinyl ester;  
 at least one photoinitiator comprising a phosphorus compound; and  
 at least one thermal initiator comprising a peroxide compound; and  
   (ii) exposing the dual cure composition to radiation of a wavelength made available from a radiation source to at least partially photocure the composition, and to provide an exotherm sufficient to initiate thermal curing to form an at least partially cured composition.    
   
   
       26 . The method of  claim 25 , wherein the radiation source is turned off before complete curing is achieved.  
   
   
       27 . The method of  claim 25 , wherein the composition is fully cured.  
   
   
       28 . A wind rotor blade for a wind turbine made by the method of  claim 25 .  
   
   
       29 . A wind rotor blade for a wind turbine made by the method of  claim 27.