Colorimetric curing indicator in polyurethane acrylate mixed resin system and use method of colorimetric curing indicator

Abstract

The present invention relates to a urethane acrylate hybrid composition comprising the reaction product of: an isocyanate component comprising one or more isocyanate compounds and one or more initiators; and an isocyanate reactive component comprising: one or more polyether polyols and / or polyester polyols; and one or more hydroxy (meth) acrylate monomers; and one or more anthraquinone curing indicators.

Description

Technical Field

[0001] Embodiments are directed to colorimetric cure indicators for polyurethane-acrylate hybrid resin systems. Background Art

[0002] In recent years, polyurethane (PU) hybrid resin systems containing hydroxyl-functional (meth)acrylate monomers have been developed. Due to long open time, low heat release, good surface quality and excellent physical and mechanical properties, such as high toughness and fatigue resistance, they have wide application potential in various fields, especially in some composite manufacturing processes that require long open time, such as vacuum infusion. Only after full cure can the composite parts show the best mechanical properties in application. However, in order to evaluate the degree of cure, many factors are considered, including surrogate indicators of cure, such as glass transition temperature (Tg), heat deformation temperature (HDT), dielectric and mechanical properties, which are determined by differential scanning calorimetry (DSC), thermomechanical analyzer (TMA), dynamic mechanical analysis (DMA) or other methods. These techniques for monitoring the degree of cure are difficult or impossible to implement in the field and during resin application, especially for large products, such as wind blades. Summary of the invention

[0003] A polyurethane acrylate hybrid composition comprising the reaction product of: an isocyanate component comprising one or more isocyanate compounds and one or more initiators; and an isocyanate reactive component comprising: one or more polyether polyols and / or polyester polyols; and one or more acrylate monomers according to the formula:

[0004]

[0005] Wherein R1 is selected from hydrogen, methyl or ethyl, R2 is selected from alkylene having 2 to 6 carbon atoms, 2,2-bis(4-phenylene)propane, 1,4-bis(methylene)benzene, 1,3-bis(methylene)benzene, 1,2-bis(methylene)benzene, and n is an integer selected from 1 to 6; and one or more anthraquinone solidification indicators. DETAILED DESCRIPTION

[0006] Embodiments relate to colorimetric cure indicators for PU acrylate hybrid compositions. Specifically, the PU acrylate hybrid compositions can include one or more anthraquinone cure indicators that provide a colorimetric indicator of cure progress during PU and free radical polymerization.

[0007] The PU acrylate hybrid composition can be generated by reacting an isocyanate component with an isocyanate reactive component containing one or more anthraquinone curing indicators. The isocyanate component may include at least one compound having an isocyanate group. The isocyanate component may include one or more isocyanates and a polyisocyanate having an average of at least 2.0 isocyanate groups per molecule. The isocyanate component may contain aliphatic, alicyclic, alicyclic, aromatic, aromatic and / or derivatives thereof. Preferably, the isocyanate component contains a portion in which the NCO group is directly attached to the aromatic ring. Examples of compounds suitable for isocyanate components include monomeric methylene diphenyl diisocyanate (MDI), modified MDI, oligomeric MDI, polymeric MDI, toluene 2,4- / 2,6-diisocyanate (TDI), etc. The isocyanate may have an average isocyanate functionality of 2 to 5, 2.2 to 5, or 2.2 to 4. The isocyanate may have an isocyanate equivalent weight (EW) in the range of 75 g / eq to 250 g / eq, 80 g / eq to 200 g / eq, or 80 to 175 g / eq.

[0008] The isocyanate component may include one or more prepolymers formed by the reaction of a polyisocyanate compound and a polyol, including, for example, the reaction of 4,4'-MDI and tripropylene glycol, or the reaction of ethylene oxide-terminated propoxylated glycerol and 4,4'-MDI. The prepolymer may have an NCO content of 5 wt % to 30 wt %, 10 wt % to 25 wt %, or 15 wt % to 25 wt %. The isocyanate component may include a prepolymer in the range of 5 wt % to 70 wt %, 10 wt % to 65 wt %, or 15 wt % to 60 wt % by weight.

[0009] The isocyanate reactive component may include a polyol blend comprising, by weight percentage (wt%) of the blend, one or more polyether polyols and / or polyester polyols in the range of 35 wt% to 75 wt% and one or more hydroxyl functional (meth)acrylates in the range of 35 wt% to 75 wt%. As used herein, "(meth)" when used with various acrylate species indicates that the scope of the present specification encompasses both the acrylate or methacrylate variants of the referenced compounds.

[0010] The isocyanate reactive component may include one or more polyether polyols, which are prepared by adding an alkylene oxide such as propylene oxide and / or ethylene oxide to a polyhydroxy functional starting compound in the presence of a catalyst known in the art. The polyether polyol may be prepared from a starting compound and one or more alkylene oxides (e.g., ethylene oxide, butylene oxide and / or propylene oxide). The starting compound may include molecules having 2 to 8 hydroxyl groups per molecule, such as ethylene glycol, propylene glycol, diethylene glycol, dipropylene glycol, triethylene glycol, tripropylene glycol, 1,4-butylene glycol, 1,6-hexanediol, bisphenol A, glycerol, trimethylolpropane, pentaerythritol, sugars and sugar alcohols such as sucrose and sorbitol, etc.

[0011] The polyether polyol may have an average hydroxyl value (OH value) in the range of 100 to 500 mg KOH / g, 150 to 450 mg KOH / g, or 200 to 450 mg KOH / g as determined according to ASTM D4274-21.

[0012] The polyester polyol disclosed herein includes the reaction product of one or more carboxylic acids and a polyol with 2 to 4 OH functionalities. Suitable carboxylic acids may include aromatic diacids or anhydrides and C4 to C12 aliphatic diacids. Suitable polyols for forming polyesters include one or more alkylene glycols or polyalkylene glycols with 2 to 4 hydroxyl functionalities, such as ethylene glycol, 1,2- or 1,3-propylene glycol, 1,4-butanediol, 1,6-hexanediol, diethylene glycol, glycerol, etc. Examples of polyester polyols include polyesters of phthalic anhydride and diethylene glycol, and polyesters of C4 to C12 diacids (such as succinic acid or adipic acid) and diethylene glycol.

[0013] The polyester polyol may have an average hydroxyl value (OH value) in the range of 100 mg KOH / g to 500 mg KOH / g, 150 mg KOH / g to 450 mg KOH / g, or 200 mg KOH / g to 450 mg KOH / g as determined according to ASTM D4274-21. The isocyanate reactive component may include one or more polyester polyols in the range of 10 wt % to 40 wt %, 15 wt % to 35 wt %, or 15 wt % to 30 wt %.

[0014] The isocyanate reactive component may include one or more hydroxyl functional (meth) acrylate monomers that react with the isocyanate component and / or polymerize in the presence of a free radical initiator to produce a PU acrylate hybrid composition. The hydroxyl functional (meth) acrylate monomer may have the following general structure:

[0015]

[0016] wherein R1 is selected from hydrogen, methyl or ethyl; R2 is selected from alkylene having 2 to 6 carbon atoms, 2,2-bis(4-phenylene)propane, 1,4-bis(methylene)benzene, 1,3-bis(methylene)benzene, 1,2-bis(methylene)benzene; and n is an integer selected from 1 to 6. The hydroxyl-functional (meth)acrylate monomer may include a hydroxy C1-10 (meth)acrylate alkyl ester monomer, such as hydroxyethyl acrylate, hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, hydroxybutyl (meth)acrylate monomer, and the like.

[0017] The added amount of the hydroxyl functional (meth)acrylate can range from 15 wt % to 40 wt %, 20 wt % to 38 wt %, 25 wt % to 35 wt % or 27 wt % to 32 wt % based on the weight percentage (wt %) of the polyurethane acrylate hybrid composition.

[0018] The isocyanate reactive component may include one or more anthraquinone curing indicators that provide a visual indication of the progress of the PU acrylate hybrid composition during curing. In some cases, curing may be indicated by a transition from light green to brownish red, which indicates that the composition is substantially cured. Suitable anthraquinone curing indicators include anthraquinone dyes such as 1-(methylamino)-4-p-toluaminoanthraquinone (CAS: 128-85-8), 1,4-bis(ethylamino)-9,10-anthraquinone, 1,4-bis(4'-methylphenylamino)anthraquinone, 1,4-bis(o-sulfo-p-toluidine)anthraquinone, and the like.

[0019] The anthraquinone curing indicator may be added in an amount ranging from 0.001 wt % to 0.15 wt %, 0.001 wt % to 0.10 wt % or 0.01 wt % to 0.05 wt % based on the weight percentage (wt %) of the polyurethane acrylate hybrid composition.

[0020] The polyurethane acrylate hybrid composition may include one or more initiators (e.g., free radical initiators) added to the isocyanate component. Initiators include, but are not limited to, peroxides, persulfides, peroxycarbonates, peroxyboric acid, azo compounds, or other suitable free radical initiators that can initiate the curing of double bond-containing compounds. Suitable initiators include azo compounds or peroxides. Preferably, the azo compound can be 2,2-azobisisobutyronitrile (AIBN); the peroxide is selected from the group consisting of: tert-butyl perbenzoate, butyl 4,4-di(tert-butylperoxy)valerate, di-tert-amyl peroxide, diisopropyl peroxide, di(tert-butylperoxyisopropyl)benzene, 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane, tert-butyl peroxide isopropyl benzene, 2,5-dimethyl-2,5-di(tert-butylperoxy)hexyne-3, di-tert-butyl peroxide, 3,6,9-triethyl-3,6,9-trimethyl-1,4,7-triperoxynonane, isopropyl hydroperoxide isopropyl benzene, 1,1,3,3-tetramethylbutyl hydroperoxide, isopropyl hydroperoxide, tert-butyl hydroperoxide and any combination thereof.

[0021] The polyurethane acrylate hybrid composition may include greater than 0 wt % initiator by weight percentage (wt %), including at least 0.1 wt %, at least 0.2 wt %, or at least 0.3 wt %, and up to 6.0 wt %, up to 5.0 wt %, or up to 4.0 wt %.

[0022] The isocyanate reactive component may include one or more accelerators, including metal salts such as cobalt and zinc salts that catalyze free radical polymerization reactions. The amount of accelerator added may range from 0 wt % to 0.15 wt %, 0.001 wt % to 0.10 wt %, or 0.01 wt % to 0.05 wt % based on the weight percentage (wt %) of the polyurethane acrylate hybrid composition.

[0023] Catalysts for promoting PU reactions may also be added, including amine catalysts, organometallic catalysts, or mixtures thereof. Amine catalysts may include one or more of triethylamine, tributylamine, triethylenediamine, N-ethylmorpholine, N,N,N',N'-tetramethylethylenediamine, pentamethyldiethylenetriamine, N-methylaniline, N,N-dimethylaniline, etc. Organometallic catalysts may include organotin compounds, such as tin acetate (II), tin octoate (II), tin ethylhexanoate, tin laurate, dibutyltin oxide, dibutyltin dichloride, dibutyltin diacetate, dibutyltin maleate, dioctyltin diacetate, etc. The amount of catalyst added may be in the range of 0 wt % to 0.15 wt %, 0.001 wt % to 0.10 wt %, or 0.01 wt % to 0.05 wt % based on the weight percentage (wt %) of the polyurethane acrylate mixed composition.

[0024] The isocyanate-reactive component may also contain one or more additives, including blowing agents, surfactants, crosslinking agents, plasticizers, fillers, smoke suppressants, flavors, enhancers, moisture scavengers, preservatives, odor masking agents, physical blowing agents, chemical blowing agents, flame retardants, internal mold release agents, biocides, antioxidants, UV stabilizers, antistatic agents, thixotropic agents, adhesion promoters, cell openers, and the like.

[0025] The PU acrylate hybrid composition may include one or more silicone or organic defoamers in a range of 0.05 wt % to 5 wt %, 0.1 wt % to 1.5 wt % or 0.1 wt % to 1 wt % based on the weight percentage (wt %) of the PU acrylate hybrid composition.

[0026] The PU acrylate hybrid composition can be used in any suitable method for developing articles and composite materials, including molding, injection, vacuum infusion, pultrusion, etc. In one method, the PU acrylate hybrid composition can be prepared by the following steps: mixing an isocyanate component and an isocyanate-reactive component to form a mixture; processing the mixture in a mold to produce a molded article; and demolding the molded article.

[0027] PU acrylate hybrid compositions can be used to prepare molded composite parts. For the preparation of composite parts, the polyurethane-poly (meth) acrylate reactive composition is mixed with a reinforcing material or injected into the reinforcing material, for example, by vacuum assisted resin transfer molding (VARTM) and / or resin transfer molding (RTM). Suitable reinforcing materials include any one or more of glass fibers, carbon nanotubes, carbon fibers, polyester fibers, natural fibers, aramid fibers, nylon fibers, basalt fibers, boron fibers, silicon carbide fibers, asbestos fibers, whiskers, hard particles, metal fibers, etc.

[0028] The composite article prepared using the PU acrylate hybrid composition of the present invention may include one or more reinforcing materials in a weight percentage (wt %) range of 1 wt % to 90 wt %, 30 wt % to 90 wt %, 50 wt % to 85 wt % or 50 wt % to 80 wt %.

[0029] The composite product prepared using the PU acrylate hybrid composition of the present invention may also include one or more core materials to facilitate molding and weight reduction of the composite material. The core material may include polystyrene foam, polyester PET foam, polyimide PMI foam, polyvinyl chloride foam, metal foam, cellulose, wood such as balsa wood, etc.

[0030] The polyurethane acrylate hybrid composition can produce products and composite materials with excellent mechanical properties, such as high heat distortion temperature, high tensile and flexural strength, high fatigue resistance, high ductility and low shrinkage. The products and composite materials can be used to manufacture wind turbine blades, wind turbine nacelle shells, ship propeller blades, hulls, interior and exterior automotive decorative parts, automobile bodies, radar covers, mechanical structural components, decorative parts and structural components of buildings and bridges, etc.

[0031] Example

[0032] The following examples are provided to illustrate embodiments of the present invention and are not intended to limit the scope of the invention. Table 1 provides the materials used in the following examples.

[0033]

[0034]

[0035] In the following examples, PU acrylate mixtures were tested to determine the extent of cure of the isocyanate reactive component (Part A) or the isocyanate component (Part B) at various stages after combination.

[0036] The degree of curing of the samples was evaluated using a TA DSC-Q2000 (TA Instruments), and the thermal residual of each sample was recorded by a continuous heating cycle. Specifically, the sample was equilibrated to 0°C, and data was recorded when the temperature was increased to 50°C at a rate of 10°C / min. The sample was then equilibrated to 0°C again, and a second data series was collected when the temperature was increased to 250°C at a rate of 20°C / min.

[0037] The heat residual (J / g) of each sample is calculated by the integrated area of ​​the exothermic peak. The heat residual value of the CE1 (0% TBPB) control group is set as the benchmark TR0, that is, the total heat residual that can be released by a sample during curing. Then, the reduction in the heat residual of other samples compared to the benchmark is taken as the degree of cure. For example, the heat residual of sample A is set as TR1, and then the degree of cure (C1) of the sample is calculated as follows:

[0038] C1=(1-TR1 / TR0)*100%

[0039] Using X-Rite TM The chromaticity measurements in the examples were obtained using a spectrophotometer to provide quantitative results of color changes in LAB values. The measurements were based on the L*A*B* color space = determination of L (brightness) and A and B (chromaticity coordinates). ΔE is a formula summarizing the difference between two colors:

[0040] ΔE=(L1-L2) 2+(A1-A2) 2 +(B1-B2) 2

[0041] A ΔE of 1 indicates that the two colors are nearly identical, and a ΔE greater than 3 indicates two different colors due to differences in brightness and / or differences in chromaticity.

[0042] Example 1: Curing characteristics of PU acrylate mixtures as a function of initiator concentration

[0043] In this example, various PU acrylate formulations containing various levels of initiator (TBPB) were quantitatively and qualitatively analyzed. Comparative sample (CS1) PU acrylate system and samples of the present invention containing 0.25g (IS1) and 0.5g (IS2) initiator were analyzed. The sample formulations are shown in Table 2, where all values ​​are in grams.

[0044]

[0045] The sample formulations were blended in the specified proportions using a high-speed stirrer. The obtained liquid resin was degassed and cast into a plastic cup. The sample cups were then heated in an oven at 50°C for 2 hours for pre-curing. One control sample of each sample series was set aside and not heated further. In order to obtain different degrees of cure for each group, the remaining sample series cups were placed in an oven at 70°C / 80°C / 90°C / 100°C and heated for 0.5 hours, 1 hour, 1.5 hours, 2 hours, and 2.5 hours, respectively. The entire series included 21 samples, 5 samples at each temperature, and one was a control sample. The samples were then taken out of the cups and the sample color and sample cure were analyzed.

[0046] The anthraquinone cure indicator is initially green and turns to a brownish red as cure proceeds. The chromaticity results for the CS1 series are shown in Table 3, IS1 in Table 4, and IS2 in Table 5.

[0047] The heat residual and degree of cure obtained by DSC are shown in Table 6 for each series.

[0048]

[0049]

[0050]

[0051] As shown in Table 3, in the absence of a peroxide initiator in CS1, there is no free radical polymerization, which is visible as a negligible change in color after heat treatment (a slight change from pure green to yellow-green). The DSC data shown in Table 6 shows the reduction of thermal residues in the PU component and the progression of the degree of cure, indicating that the anthraquinone cure indicator is largely responsive to the presence of free radical polymerization.

[0052] Tables 4 and 5 show that the IS1 (50% initiator) and IS2 (100% initiator) series exhibit an increasing degree of color change and a corresponding increase in heat residual and degree of cure (Table 6). For each series, the color shift from green to yellow to brownish red (and L) is associated with a corresponding increase in the secondary cure measurement.

[0053] While the foregoing is directed to illustrative embodiments, other and further embodiments may be devised without departing from the basic scope of the present invention, which is defined by the claims that follow.

Claims

1. A polyurethane acrylate hybrid composition comprising the reaction product of the following components: an isocyanate component comprising one or more isocyanate compounds and one or more initiators, and An isocyanate-reactive component, the isocyanate-reactive component comprising: one or more polyether polyols and / or polyester polyols; and One or more acrylate monomers according to the formula: wherein R1 is selected from hydrogen, methyl or ethyl, R2 is selected from an alkylene group having 2 to 6 carbon atoms, 2,2-bis(4-phenylene)propane, 1,4-bis(methylene)benzene, 1,3-bis(methylene)benzene, 1,2-bis(methylene)benzene, and n is an integer selected from 1 to 6; and One or more anthraquinone solidification indicators.

2. The polyurethane acrylate hybrid composition according to claim 1, wherein the anthraquinone curing indicator is Sudan Blue.

3. The polyurethane acrylate hybrid composition according to claim 1, wherein the added amount of the hydroxyl functional acrylate monomer is in the range of 15 wt % to 40 wt % based on the weight percentage (wt %) of the polyurethane acrylate hybrid composition.

4. The polyurethane acrylate hybrid composition according to claim 1, wherein the isocyanate reactive component further comprises a cobalt salt accelerator.

5. The polyurethane acrylate hybrid composition according to claim 1, wherein the addition amount of one or more polyether polyols and / or polyester polyols is in the range of 10 wt% to 40 wt% based on the weight percentage (wt%) of the polyurethane acrylate hybrid composition.

6. The polyurethane acrylate hybrid composition according to claim 1, wherein the anthraquinone curing indicator is added in an amount ranging from 0.01 wt% to 0.15 wt% based on the weight percentage (wt%) of the polyurethane acrylate mixture.

7. An article comprising the polyurethane acrylate hybrid composition according to claim 1.

8. A method for preparing the polyurethane acrylate hybrid composition according to claim 1, the method comprising: combining the isocyanate component and the isocyanate-reactive component to form a mixture, further comprising one or more reinforcement materials and / or core materials; processing the mixture in a mold to produce a molded article; as well as The molded article is demoulded.

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