Cleavable free radically curable compositions

Abstract

1. A composite comprising a filler and a free radical curable composition that is cleavable after curing, the composition comprising a compound of general formula E 1 -OC(R 2 )(R 3 )-XE 2 (1) (where E 1 and E 2 each of which contains a free radically polymerizable ethylenically unsaturated moiety, and X is either oxygen (O) or sulfur (S)), and optionally a moiety -OC(R 2 )(R 3 and wherein the composition comprises at least one free radically polymerizable ethylenically unsaturated molecular component b that does not contain —X—, and when the composition cures, the composition has a T of greater than 50° C. as measured by dynamic mechanical thermal analysis (DMTA). g forming a polymer having the following structure:

Description

[Technical Field]

[0001] The present invention relates to a composite comprising a filler and a post-cure free radically curable composition that is cleavable. The present invention further relates to a method for at least partially cleaving the composite to at least partially recover the filler. [Background technology]

[0002] In the field of composite materials, the recovery and reuse of expensive reinforcing filler materials such as glass and carbon fibers, and / or resin fibers, has become a priority in the context of sustainability and the circular economy.

[0003] Free radical curable resins, in conjunction with photoinitiation or electron beam initiation, are used to produce glass and carbon fiber composites. Composites based on free radical polymerizable groups have excellent mechanical and chemical resistance after curing due to their tightly crosslinked network, but recycling remains a challenge. Decrosslinking thermosetting resins, such as resins cured by electron beam, or recycling filler materials in composites, is significantly more difficult than composites made from thermoplastic materials due to the high crosslink density of thermosetting resins.

[0004] WO2015 / 164087 discloses a method for manufacturing a pressure sensitive adhesive (PSA) comprising incorporating a polymer made from a cleavable crosslinked polymer, which allows the cured composition to have a low glass transition temperature (T g ), the purpose of which is to tailor the physical properties of the PSA, such as gel content, storage modulus, or peel adhesion, upon actinic or thermal activation of the cleavable moiety, to achieve performance for a range of PSA applications. Summary of the Invention [Problem to be solved by the invention]

[0005] There is a need in the art for free radically curable compositions that can be used in composites that maintain good integrity during their useful life while also having good recyclability at the end of their useful life.

[0006] It is therefore an object of the present invention to develop a composite comprising a free radically curable composition that, after curing, allows for good recyclability of fibers that have come into contact with such a composition. [Means for solving the problem]

[0007] The composites of the present invention may have one or more of the following advantages:

[0008] The composites of the present invention may have post-curing compositions that are cleavable or even soluble in certain circumstances, thus allowing for integration into circular economy processes.

[0009] The composites of the present invention may have post-curing compositions that are cleavable or even soluble in certain acidic conditions, even without added organic solvents.

[0010] The composites of the present invention may have a cured composition that has excellent mechanical and chemical resistance over its useful life.

[0011] In a first aspect, the present invention provides a composite comprising a filler and a free radically curable composition after curing that is cleavable, wherein the free radically curable composition before curing comprises the following components: a. General formula E 1 -OC(R 2 )(R 3 )-XE 2 (1) (In the formula, E 1 and E 2each contains a free radically polymerizable ethylenically unsaturated moiety, X is either oxygen (O) or sulfur (S), and R 2 and R 3 are independently selected from the list consisting of hydrogen, alkyl, alkenyl, alkynyl, cycloalkyl, cycloalkenyl, cycloalkynyl, aryl, heterocycloalkyl, heterocycloalkenyl, heteroaryl, alkoxyaryl, and alkoxyalkyl, or C(R 2 )(R 3 ) are linked to form a cycloalkyl, cycloalkenyl, cycloalkynyl, aryl, heterocycloalkyl, heterocycloalkenyl, heteroaryl, or alkoxyaryl ring system; R 2 and R 3 are independently or C(R 2 )(R 3 ) forms a ring structure, at least one bridge molecule component a.) is either substituted or unsubstituted. b. Optionally, the moiety -OC(R 2 )(R 3 ) at least one free radically polymerizable ethylenically unsaturated molecular component that does not contain —X— b. Including, The cured material formed after polymerization of the composition has a glass transition temperature (T) of greater than 50°C as measured by dynamic mechanical thermal analysis (DMTA). g ) and the filler is an organic fiber or an inorganic fiber; Regarding composites.

[0012] In a second aspect, the present invention relates to a method for at least partially recycling a filler, and optionally a cleaved cured free radically curable composition of a composite according to any embodiment of the first aspect, comprising the step of subjecting the cured free radically curable composition to a cleaving environment comprising at least one of an aqueous liquid, an alcohol, an acid, and a temperature above 40°C, preferably above 85°C. DETAILED DESCRIPTION OF THE INVENTION

[0013] As used herein, and unless otherwise stated, the term "cleavable" means that the composition undergoes cleavage of covalent bonds in a cleavage environment. In this context, a specific form of cleavable is "soluble." The term "cleavage environment" refers to an environment comprising at least one of an aqueous liquid, an alcohol, an acid, and a temperature greater than 40°C, preferably greater than 60°C, and more preferably greater than 85°C. The term "soluble" as used herein means that the composition undergoes cleavage of covalent bonds in a "cleavage environment," which is a liquid comprising at least one of an aqueous liquid, an alcohol, and an acid, possibly in combination with a higher temperature, thereby at least partially dissolving the composition in the liquid. Preferably, when the cleavage environment comprises an aqueous liquid, an acid is also present. Preferably, the pH of the aqueous liquid is less than 5, preferably less than 4, and more preferably less than 3. For example, the pH may be 1.5 to 2.5 or 1.8 to 2.2. Preferably, the temperature is not increased above 300°C. This is to avoid thermal decomposition of the free radically curable composition after curing.

[0014] In a first aspect, the present invention provides a composite comprising a filler and a free radically curable composition after curing that is cleavable, wherein the free radically curable composition before curing comprises the following components: a. General formula E 1 -OC(R 2 )(R 3 )-XE 2 (1) (In the formula, E 1 and E 2 each contains a free radically polymerizable ethylenically unsaturated moiety, X is either oxygen (O) or sulfur (S), and R 2 and R 3 are independently selected from the list consisting of hydrogen, alkyl, alkenyl, alkynyl, cycloalkyl, cycloalkenyl, cycloalkynyl, aryl, heterocycloalkyl, heterocycloalkenyl, heteroaryl, alkoxyaryl, and alkoxyalkyl, or C(R 2 )(R 3) are linked to form a cycloalkyl, cycloalkenyl, cycloalkynyl, aryl, heterocycloalkyl, heterocycloalkenyl, heteroaryl, or alkoxyaryl ring system; R 2 and R 3 are independently or C(R 2 )(R 3 ) forms a ring structure, at least one bridge molecule component a.) is either substituted or unsubstituted. b. Optionally, the moiety -OC(R 2 )(R 3 ) at least one free radically polymerizable ethylenically unsaturated molecular component that does not contain —X— b. Including, The cured free radically curable composition material formed after polymerization of the composition has a glass transition temperature (T) of greater than 50° C. as measured by dynamic mechanical thermal analysis. g ) and the filler is an organic fiber or an inorganic fiber; Regarding composites.

[0015] For clarity, unless otherwise stated, the glass transition temperature (T g All values ​​quoted for (a) refer to the state after polymerization (i.e., cure) of solvent-free cured free-radical curable compositions as determined by dynamic mechanical thermal analysis (abbreviated DMTA), and are meant to be free of fillers.

[0016] According to the present invention, the filler is an organic or inorganic fiber. The synthetic fiber may be organic or inorganic. Examples of synthetic inorganic fibers are glass fiber and boron fiber. Examples of synthetic organic fibers are carbon fiber, polyamide (polyaramid) fiber. Examples of organic natural fibers (or biofibers) are fibers derived from plants (derived from wood, sisal, hemp, coconut, cotton, kenaf, flax). Preferably, the fibers are selected from glass fiber and / or carbon fiber. The composite of the first aspect is formed by curing a pre-cure free-radically curable composition in contact with the filler. The fiber is used as a reinforcement in the radically cured curable composition.

[0017] The free radical curable composition of the first embodiment before curing is curable by the action of free radicals due to the compounds a. and b. that are polymerizable by the action of free radicals. For example, free radical curing can be initiated by electron beams, by a combination of photoinitiators and actinic radiation, such as ultraviolet radiation in the wavelength range of 200 to 400 nm or visible light in the wavelength range of 400 to 550 nm, or after thermal decomposition of a radical initiator such as a peroxide or an azo compound.

[0018] Preferably, at least one component a. and optionally b. has a T above 50°C. g Component b., if present, provides a cured material having a T value greater than 50° C. after curing. g is preferably present in the composition in an amount to form a material having the formula:

[0019] Preferably, component b, upon polymerization, has a T g It has a value.

[0020] The composition of the first aspect is preferably liquid at 25°C. For resin infusion composite applications, the composition preferably has a viscosity of less than 5000 mPa.s at 25°C. For example, the composition may have a viscosity of less than 2500 mPa.s at 25°C or less than 1000 mPa.s at 25°C. A viscosity of less than 1000 mPa.s at 25°C is advantageous when using the composition in the manufacture of composite materials by resin infusion. Some embodiments of the present invention also provide a viscosity in the range of 1 to 50 mPa.s at 25°C.

[0021] Viscosity: 20s -1 is measured in accordance with DIN EN ISO 3219 using a rotational rheometer at a shear rate of 100 MPa.

[0022] Glass transition temperature (T g ) marks the boundary between a glassy, ​​rigid state and a softer, relaxed state of a polymer or polymer network, which may be rubbery or even fluid. A suitable method for determining the glass transition temperature of a solid polymer or polymer network is dynamic mechanical thermal analysis, as described, for example, by standard method ASTM D4065-01 (Standard Test Method for Assignment of Glass Transition Temperatures by Dynamic Mechanical Analysis).

[0023] Preferably, the T of the free radically curable composition after curing g may be above 60°C, even more preferably above 75°C. g is less than 160°C, such as less than 140°C.

[0024] After curing, free-radical curable compositions should meet the mechanical property requirements for composite applications. Young's modulus, or tensile modulus, is a mechanical property that provides an index of the degree of stiffness of a solid material. It defines the relationship between the tensile stress (force per unit area) and tensile strain (relative deformation rate) of a substance for small uniaxial deformations. Ultimate tensile elongation (UTE) or elongation at break describes a material's resistance to fracture. Tensile properties are reported at a temperature of 23°C in accordance with one of the above-mentioned standard methods for determining tensile properties: ASTM D638 (Standard Test Method for Tensile Properties of Plastics), ASTM D882 (Standard Test Method for Tensile Properties of Thin Sheets of Plastics), or ISO 527-1 (Plastics - Determination of Tensile Properties). These measurements are performed on the free-radical curable compositions after solvent-free curing, i.e., in the absence of fillers.

[0025] In embodiments, the free radically curable composition after curing may have a Young's modulus of at least 10 MPa, preferably at least 100 MPa, and more preferably at least 1000 or 3000 MPa.

[0026] In embodiments, the free radically curable composition after curing may have a UTE of at least 0.2%, preferably at least 0.5%, and more preferably at least 2.0%. For example, the free radically curable composition after curing may have a UTE of 3-15%, which is particularly advantageous when the composition is used with fillers such as glass fiber or carbon fiber.

[0027] In addition to components a. and b., the composition may contain further components.

[0028] For example, the composition may comprise the moiety -OC(R 2 )(R 3 )—X—, at least one free radically polymerizable ethylenically unsaturated molecule, g Component c. may be included such that, after curing, the entire composition has a Tg Component c., if present, is preferably present in an amount of less than 5% by weight of the sum of components a., b., and c. Preferably, component c. is absent.

[0029] In another embodiment, the composition may include a solvent (component d.), which may be present in any amount, as it is removed before or during curing of the composition.

[0030] The composition may also include a radical photoinitiator or a radical thermal initiator (component e.).

[0031] General formula E 1 -OC(R 2 )(R 3 )-XE 2 In the cross-linking molecule component a., R 2 and R 3 are preferably independently selected from the list consisting of hydrogen, alkyl (e.g., C1-C6), and aryl, or are joined together to form a 5- or 6-carbon ring structure. In a preferred embodiment, R 2 and R 3 are independently selected from the list consisting of hydrogen and methyl, or C(R 2 )(R 3 ) are linked together to form a five-carbon ring structure.

[0032] R 2 and R 3 Preferably, both R are alkyl groups. Most preferably, R is 0 or 1 since upon hydrolysis after cleavage, formaldehyde or other aldehydes such as acetaldehyde are produced, which is undesirable for environmental reasons. 2 and R 3 are not hydrogen. In a preferred embodiment, X is an oxygen atom.

[0033] E 1 and E 2Due to the presence of E, each cross-linking molecule can act as a cross-linking agent. 1 and E 2 E can independently be any moiety that contains one or more free radically polymerizable ethylenically unsaturated functional groups. 1 and E 2 may be the same or different. If they are the same, it is advantageous as it facilitates manufacturing. However, it is not necessary. In an embodiment, E 1 and E 2 may each comprise a functional group independently selected from vinyl (e.g., vinyl ether), acrylamide, methacrylamide, acrylate functionality, or methacrylate functionality. 1 and E 2 may each contain an acryloyl or methacryloyl functional group. For example, E 1 and E 2 may independently comprise or form a methacrylate or acrylate functional group.

[0034] If component a. comprises crosslinking molecules in which E1 and / or E2 contain two or more free-radically polymerizable ethylenically unsaturated functional groups, the amount of this crosslinking agent is preferably at most 20% by weight of the crosslinking agent that constitutes component a.

[0035] In embodiments, E 1 and E 2 is the following formula: -(CO)C(R 1 )=CH2(5) -L 1 -O(CO)C(R 1 )=CH2(6) -L 1 -OC(R 2 )(R 3 )O(CO)C(R 1 )=CH2(7) -L-XC(R 2 )(R 3 )-OL 1 -O(CO)C(R 1)=CH2(8) -L 1 -(OC(R 2 )(R 3 )-O(CO)-L 2 (CO)OC(R 2 )(R 3 )OL 1 ) n OC(R 2 )(R 3 )O(CO)C(R 1 )=CH2(9) (In the formula, X, R 2 and R 3 are as previously described with respect to formula (1), but may be independently selected from therein. Preferably, X, R 2 and R 3 are the X and R in formula (1). 2 and R 3 is the same as L 2 , L 1 and L are divalent bridging groups which may be the same or different and are selected independently of each other, provided that L 2 may be a single bond; R 1 is either H or CH3, but at higher T g CH3 is preferred to obtain a cured composition having

[0036] Divalent Linking Group, L 2 , L 1 and L typically has a molecular weight of less than 2000 g / mol. In some embodiments, the molecular weight is less than 500, 250, 100, 75, or 50 g / mol.

[0037] In some preferred embodiments, the divalent linking group L 2 , L 1 Or, L may be a (e.g., C1-C6) alkylene group. In some embodiments, L 2 , L 1 Or L is a C2, C3 or C4 alkylene group.

[0038] In some embodiments, L 2 may be a single bond.

[0039] In some embodiments, the divalent linking group L 1 may contain oligomers. For example, L 1 is expressed as follows: -CH2CH(XH)CH2-DB-(-D-CH2CH(XH)CH2-DB-) n -or -L1'-(-O-CHCH3-OLO-CHCH3-O-L1'-) n -or -L1'-(-O-CHCH3-SLS-CHCH3-O-L1'-) n - and L and L 1’ L 1 Unlike L 1’ is a divalent linking moiety as defined above for L, but is independently selected therefrom; B is alkylene, alkenylene, alkynylene, arylene, alkylene-arylene, arylene-alkylene, alkylene-arylene-alkylene, alkenylene-arylene, arylene-alkenylene, alkenylene-arylene-alkenylene, alkylene-arylene-alkenylene, alkenylene-arylene-alkylene, alkynylene-arylene, arylene-alkynylene, alkynylene-arylene-alkynylene, alkynylene-arylene-alkylene, alkylene-arylene-alkynylene, alkenylene-arylene-arylene alkynylene-alkynylene, alkynylene-arylene-alkenylene, heteroarylene, alkylene-heteroarylene, heteroarylene-alkylene, alkylene-heteroarylene-alkylene, alkenylene-heteroarylene, heteroarylene-alkenylene, alkenylene-heteroarylene-alkenylene, alkylene-heteroarylene-alkenylene, alkenylene-heteroarylene-alkylene, alkynylene-heteroarylene, heteroarylene-alkynylene, alkynylene-heteroarylene-alkynylene, alkynylene Heteroarylene-alkylene, alkylene-heteroarylene-alkynylene, alkenylene-heteroarylene-alkynylene, alkynylene-heteroarylene-alkenylene, cycloalkylene, alkylene-cycloalkylene, cycloalkylene-alkylene, alkylene-cycloalkylene-alkylene, alkenylene-cycloalkylene, cycloalkylene-alkenylene, alkenylene-cycloalkylene-alkenylene, alkylene-cycloalkylene-alkenylene, alkenylene-cycloalkylene-alkylene, alkynylene cycloalkylene, cycloalkylene-alkynylene, alkynylene-cycloalkylene-alkynylene, alkynylene-cycloalkylene-alkylene, alkylene-cycloalkylene-alkynylene, alkenylene-cycloalkylene-alkynylene, alkynylene-cycloalkylene-alkenylene, heterocycloalkylene, alkylene-heterocycloalkylene, heterocycloalkylene-alkylene, alkylene-heterocycloalkylene-alkylene, alkylene-heterocycloalkylene-alkylene, alkenylene-heterocycloalkylene, heterocycloalkylene-alkenylene,Alkenylene-heterocycloalkylene-alkenylene, alkylene-heterocycloalkylene-alkenylene, alkenylene-heterocycloalkylene-alkylene, alkynylene-heterocycloalkylene, heterocycloalkylene-alkynylene, alkynylene-heterocycloalkylene-alkynylene, alkynylene-heterocycloalkylene-alkylene, alkylene-heterocycloalkylene-alkynylene, alkenylene-heterocycloalkylene-alkynylene, alkynylene-heterocycloalkylene- Alkenylene, cycloalkenylene, alkylene-cycloalkenylene, cycloalkenylene-alkylene, alkylene-cycloalkenylene-alkylene, alkenylene-cycloalkenylene, cycloalkenylene-alkenylene, alkenylene-cycloalkenylene-alkenylene, alkylene-cycloalkenylene-alkenylene, alkenylene-cycloalkenylene-alkylene, alkynylene-cycloalkenylene, cycloalkenylene-alkynylene, alkynylene-cycloalkenylene-alkynylene, alkyl alkylene-cycloalkenylene-alkylene, alkylene-cycloalkenylene-alkynylene, alkenylene-cycloalkenylene-alkynylene, alkynylene-cycloalkenylene-alkenylene, heterocycloalkenylene, alkylene-heterocycloalkenylene, heterocycloalkenylene-alkylene, alkylene-heterocycloalkenylene-alkylene, alkenylene-heterocycloalkenylene, heterocycloalkenylene-alkenylene, alkenylene-heterocycloalkenylene, alkenylene-heterocycloalkenylene-alkenylene, alkenylene-heterocycloalkenylene-alkenylene, alkenylene-heterocycloalkenylene-alkenylene, a It can be selected from alkylene-heterocycloalkenylene-alkenylene, alkenylene-heterocycloalkenylene-alkylene, alkynylene-heterocycloalkenylene, heterocycloalkenylene-alkynylene, alkynylene-heterocycloalkenylene-alkynylene, alkynylene-heterocycloalkenylene-alkylene, alkylene-heterocycloalkenylene-alkynylene, alkenylene-heterocycloalkenylene-alkynylene, alkynylene-heterocycloalkenylene-alkenylene.

[0040] B is preferably arylene-alkylene or cycloalkylene-alkylene. B is most preferably phenylene-methylene or cyclohexylene-methylene.

[0041] D and X are independently selected from O and S.

[0042] n is preferably 1 to 10.

[0043] Particularly preferably, E1 and / or E2, more preferably E1 and E2, are -L 1 -O(CO)C(R 1 )=CH2(6).

[0044] In embodiments, each of the, or one or more of, the at least one cross-linking molecule (component a.) is: [ka] and X 1 is selected from O and C(O)O, C is directly bonded to L; R 1 , R 2 , R 3 , L and L 1 is as defined above.

[0045] Formula (2) corresponds to a preferred embodiment of formula (1) in which both E1 and E2 comply with formula (6).

[0046] Formula (3) corresponds to an embodiment of formula (1) in which E1 conforms to formula (5) and E2 conforms to formula (7). This embodiment is less preferred.

[0047] Equation (4) corresponds to an embodiment of equation (1) in which E1 conforms to equation (6) and E2 conforms to equation (8). This embodiment is less preferred.

[0048] In embodiments, each of the, or one or more of the at least one cross-linking molecule is: [ka] and L, D, B, X, R 1 , R 2 and R 3 is as defined above, and L 1’ is a divalent linking moiety as defined above for L, but is independently selected therefrom; m is 1-10; and n is 1-10.

[0049] Crosslinkers according to formula (2) can be synthesized, for example, as follows: [ka] For example, 2,2-di(2-acryloxyethoxy)propane can be synthesized from 2-hydroxyethyl acrylate and dimethoxypropane as described in WO2015 / 164087A1 from 3M: [ka]

[0050] Alternatively, -OC(R 2 )(R 3 Cleavable crosslinking monomers containing one —O— can be synthesized from ketones or aldehydes: [ka] For example, 2,2-di(2-acryloxyethoxy)propane is a hydroxypropyl acrylate with 2-hydroxyethyl acrylate and acetone (R 2 =R 3 =CH3): [ka] This synthesis can be achieved as follows: 2-hydroxyethyl acrylate and acetone are dissolved in tetrahydrofuran in a molar ratio of 1:1:0.8, and 0.1 equivalents of p-toluenesulfonic acid pyridinium salt (PPTS) and an appropriate amount of 5 Å molecular sieves are added at room temperature. After 48 hours, the reaction mixture is neutralized with 0.1 equivalents of potassium carbonate. After filtration, the filtrate is evaporated to give 2,2-di(2-acryloxyethoxy)propane as the major product.

[0051] Similarly, 1,1-di(2-acryloxyethoxy)ethane can be prepared by the reaction of 2-hydroxyethyl acrylate and acetaldehyde (R 2 =H, R 3 =CH3): [ka]

[0052] Similarly, 1,1-di(2-acryloxyethoxy)cyclopentane can be prepared by the reaction of 2-hydroxyethyl acrylate and cyclopentanone (R 2 and R 3 = cyclopentane): [ka]

[0053] Examples of ketones are acetone, methyl ethyl ketone, acetophenone, 2-pentanone, 3-methylbutanone (methyl isopropyl ketone), 3-hexanone (ethyl propyl ketone).

[0054] Examples of cyclic ketones: cyclopentanone, cyclohexanone and their substituted analogues. Examples of aldehydes: formaldehyde, acetaldehyde, propionaldehyde, benzaldehyde

[0055] Crosslinkers according to formula (3) can be synthesized, for example, as follows: [ka] For example, butane-1,4-diylbis(oxy)bis(ethane-1,1-diyl) diacrylate is available from 3M in accordance with WO2015 / 164087A1 (R 1 =H;R 3 =H, L 1 It can be synthesized by the reaction of 1,4-divinyl ether with acrylic acid, as described in (=(CH2)4).

[0056] Or: [ka] See Examples 11 and 12 for examples of crosslinkers prepared in this manner.

[0057] Or: [ka] In this case, the reaction of the divinyl ether derivative with the diol can be carried out in the presence of trifluoroacetic acid or a sulfonic acid.

[0058] Or: [ka] The reaction conditions are similar to those described in the paper by Lou, Fengwen et al.; Huaxue Xuebao (2010), Vol. 68 (No. 12), pp. 1223-1228, regarding the addition of thiols to vinyl ethers for the synthesis of alkoxythioethers.

[0059] Crosslinkers according to formula (4) can be synthesized, for example, as follows: [ka] For example, 2-(2-vinyloxyethoxy)ethyl acrylate (R 1 =H, L 1 =CH2CH2OCH2CH2) is reacted with adipic acid (L=(CH2)4; X=COO) in a 2 / 1 molar ratio using THF as solvent at 80 °C for 10 hours, after which the solvent is evaporated.

[0060] Expression HOOCL 2 Examples of polycarboxylic acids of COOH are, inter alia, phthalic acid, isophthalic acid, terephthalic acid, oxalic acid, adipic acid, succinic acid, maleic acid, malonic acid, and polyesters with carboxylic acid residues.

[0061] Examples of polyols of the formula HOLOH are, inter alia, ethylene glycol, diethylene glycol, tripropylene glycol, 1,6-hexanediol, neopentyl glycol and cyclohexyldimethanol, polyethylene glycol polypropylene glycol, and polyesters having residual hydroxyl groups.

[0062] Examples of polythiols of the formula HSLSH are M n Poly(ethylene glycol) dithiols, including those having a molecular weight of 500 to 10,000 g / mol.

[0063] In embodiments, the T of at least one bridge molecule component a. g When polymerized together, T may be greater than 60°C, preferably greater than 70°C, and more preferably greater than 80°C. g is greater than 90°C, greater than 100°C, or even 110°C or greater.

[0064] In an embodiment, the amount of component a. is preferably greater than 5 wt. %, more preferably greater than 10 wt. %, even more preferably greater than 15 wt. %, even more preferably greater than 30 wt. %, and most preferably greater than 50 wt. % of the sum of component a. and component b.

[0065] In an embodiment, the amount of component a. is preferably less than 99% by weight, more preferably less than 95% by weight of the sum of component a. and component b.

[0066] The composition comprises component b., i.e., moiety -OC(R 2 )(R 3 Preferably, component b. is a free radical polymerizable ethylenically unsaturated molecule that does not contain —X—. Preferably, component b. is a free radical polymerizable ethylenically unsaturated molecule that, after curing, does not cause the composition to have a T of greater than 50° C. g Similarly, preferably at least one of component a. and component b. is present in the composition in an amount such that, upon polymerization (i.e., when all of the molecules forming compound a. are polymerized, or when all of the molecules forming compound b. are polymerized), a T of greater than 50° C. is formed, as measured by DMTA. g Component b. has the moiety -OC(R 2 )(R 3 )-X- is not present, it is not generally cleavable under cleavage conditions that would cleave component a.

[0067] The component b. is selected from monomers, oligomers, and polymers. As used herein, an oligomer is one having a molecular weight of M n and the polymer comprises at least 11 repeat units.

[0068] In embodiments, at least 95 wt. % of component b. contains at most two free-radically curable moieties, preferably one free-radically curable moiety. Up to 5 wt. % of component b. may contain three or more free-radically curable moieties. This typically still allows for substantial changes in the physical properties of the cured composition upon exposure to a cleavage environment. In embodiments where the cured free-radically curable composition is in contact with a filler, such changes in physical properties can be, for example, complete dissolution, partial dissolution, or any other change that allows for easier separation of the cured composition from the filler.

[0069] In embodiments, each of said components b. contains at most two free radically curable moieties, which favors a substantial change in the physical properties of the cured composition upon exposure to a cleavage environment.

[0070] In a preferred embodiment, each of said components b. contains exactly one free radically curable moiety, which is particularly advantageous in that the cured composition undergoes a substantial change in its physical properties upon exposure to a cleavage environment.

[0071] Preferred free radically curable moieties are selected from acrylate and methacrylate groups.

[0072] In an embodiment, at least one of the components b. includes a hydroxyl moiety. This is advantageous because the OH moiety can promote adhesion to the substrate or filler. This is particularly advantageous when the composition is cured in contact with glass fibers. Examples of such components b. include hydroxyl alkyl (meth)acrylates such as 2-hydroxyethyl (meth)acrylate; 2-hydroxypropyl (meth)acrylate; tone™ M-100 (Dow Chemical), which is 2-hydroxyethyl acrylate reacted with caprolactone; 2-hydroxyethyl methacrylate reacted with caprolactone; and 2-hydroxyethyl (meth)acrylate reacted with ethylene oxide or propylene oxide.

[0073] Preferably, each of said components b. has, after polymerization, a T of greater than 10°C, preferably greater than 20°C, preferably greater than 30°C, even more preferably greater than 40°C, even more preferably greater than 50°C. g It has.

[0074] For example, the polymer of 2-hydroxyethyl methacrylate has a T of 105°C in the case of a syndiotactic structure. g Characterized by value.

[0075] Preferably, component b. (which is a moiety -OC(R 2 )(R 3 ) may consist of one or more free radically polymerizable ethylenically unsaturated molecules not containing -X-) after the composition has cured, the T g is present in the composition in an amount to form a polymer having

[0076] Components a. and b., after polymerization, have a T of more than 50°C. g If any amount of component b. independently provides a composition that, after curing, has a T of greater than 50°C, g The amount of component b. can be at least 1% by weight, preferably at least 5% by weight, but can also be at least 30% by weight, or even at least 50% by weight, of the total of components a. and b.

[0077] In any other case, the type of component b. and the suitable amount of component b. can be easily determined by trial and error or by the polymerization of the constituent monomers (T gi )T g Values ​​and individual weight fractions W i From the Fox formula

number

[0078] In an embodiment, this amount is preferably at least 1% by weight of the sum of component a. and component b., preferably at least 5% by weight, more preferably at least 30% by weight or at least 50% by weight.

[0079] In an embodiment, the amount of component b. is preferably less than 95% by weight, more preferably less than 90% by weight, even more preferably less than 85% by weight, and even more preferably less than 70% by weight of the sum of component a. and component b.

[0080] In one embodiment, the cured free-radically curable composition has a double bond conversion (e.g., (meth)acrylate double bond conversion) of 20 to 100%, preferably 70 to 100%, as measured by infrared spectroscopy. Tightly crosslinked polymer networks may require harsh cleavage conditions to produce a highly soluble cured composition or to obtain a cleaved composition from which the filler can be removed. Those skilled in the art will be able to identify appropriate cleavage environments suitable for this purpose.

[0081] After curing, the free radical curable composition has a T above 50°C. g Preferably, the T of the free radically curable composition after curing g may be greater than 60°C, preferably greater than 70°C, and even more preferably greater than 75°C. g is less than 160°C, such as less than 140°C.

[0082] In embodiments, the free radically curable composition after curing may have a Young's modulus at 20°C of at least 10 MPa.

[0083] To form the composite, compound a. and optional compound b. as described in the first aspect can be contacted with the filler before curing.

[0084] The composites of the present invention can be used in the automotive industry, aerospace industry, the building sector, marine infrastructure, the oil and gas industry, consumer products, protective equipment, sports, and are particularly suitable for wind blades (for wind motors), for example wind blades made from the composite material according to the first aspect.

[0085] In a second aspect, the present invention provides a method for at least partially recycling a filler and optionally a cleaved cured free radically curable composition of a composite comprising a filler that has been in contact with the cured free radically curable composition according to any embodiment of the first aspect, comprising: subjecting the composite to a cleavage environment comprising at least one of an aqueous liquid, an alcohol, an acid, and a temperature above 40°C. The present invention relates to a method, including:

[0086] In one embodiment, the method further comprises recovering at least a portion of the filler and / or cleaved cured free radically curable composition.

[0087] In the most preferred embodiment, the composite is subjected to a cleavage environment that does not use organic solvents, making the recycling process cheaper and safer.

[0088] Preferably, the method for at least partially recycling a composite comprising a filler in contact with a cured free radically curable composition according to any embodiment of the first aspect comprises the steps of: subjecting the composite to a cleavage environment consisting of an aqueous liquid, an acid, and a temperature above 40°C. Includes.

[0089] Preferably, the acid is acetic acid, preferably at a concentration greater than 15% by weight in water.

[0090] The acetic acid thereby decomposes the cured free radically curable composition, thus rendering the composition at least partially soluble, thus separating the cured free radically curable composition from the filler, allowing for reuse of the cured free radically curable composition and the filler. When the composite contains glass or carbon fibers, glass or carbon fibers and resin, derivatives can be recovered by cleavage of the cured free radically curable composition.

[0091] Preferably, when the cleavage environment comprises an aqueous liquid, an acid is also present. Preferably, the pH of the aqueous liquid is less than 5, preferably less than 4, more preferably less than 3. For example, the pH can be 1.5 to 2.5 or 1.8 to 2.2.

[0092] Preferably, the soluble content after the cured composition is exposed to a cleavage environment and a suitable solvent is at least 20 wt%, more preferably at least 50 wt%, even more preferably at least 90 wt% or even 100 wt%, whereby the soluble content is defined as the weight percent that is no longer part of the cured composition and is removed from the cured composition. A soluble content of 100 wt% means that the composition is completely broken up or dissolved, while a soluble content of 20 wt% means that 20 wt% of the original composition is broken up or dissolved. In some cases, this may already be sufficient to separate the substrate or filler. Higher temperatures can accelerate this process.

[0093] In some embodiments, the cleavage environment is an elevated temperature without the use of a solvent. In such an environment, the composition can be cleaved and become soluble once contacted with a suitable solvent. It is possible that the cleavage generates a solvent, eliminating the need for additional solvent. Under such conditions, the soluble content is at least 20 wt%, more preferably at least 50 wt%, even more preferably at least 90 wt%, or even 100 wt%, whereby the soluble content is defined as the weight percent that is no longer part of the cured composition and is removed from the cured composition once contacted with a suitable solvent. A soluble content of 100 wt% means that the composition is completely disintegrated or dissolved, while a soluble content of 20 wt% means that 20 wt% of the original composition is disintegrated or dissolved. In some cases, this may already be sufficient to separate the substrate or filler.

[0094] In this situation, a suitable solvent may be an aqueous liquid or an organic solvent. Preferably, an acid is added to the solvent.

[0095] Any feature of the second aspect may be as correspondingly described in any of the preceding aspects.

[0096] The invention will now be described in detail with reference to the following non-limiting examples, which are given by way of illustration only. [Example]

[0097] Glass transition temperature (T g ) determination A suitable method for determining the glass transition temperature of a solid polymer or a cured polymer network is dynamic mechanical thermal analysis, as described, for example, by standard method ASTM D4065-01 (Standard Test Method for Assignment of Glass Transition Temperature by Dynamic Mechanical Analysis).

[0098] DMTA measurements are performed in tension mode using a DMA Q800 (TA Instruments) instrument. The sample dimensions between the clamps are typically 11 mm x 8.0 mm x 0.04 mm. Cyclic strain deformation is applied at a frequency of 1 Hz with an amplitude of 30 μm. Viscoelastic properties are measured following a temperature profile from -50°C to 200°C at a heating rate of 3°C per minute. g is the loss factor curve (i.e., tangent d max ) is calculated as the temperature at the maximum value.

[0099] Determination of (meth)acrylate double bond conversion A suitable instrumental technique for determining the conversion of ethylenic unsaturation (i.e., double bonds) for cured (meth)acrylate networks is ATR-FTIR (attenuated total reflectance-Fourier transform infrared) spectroscopy. The procedure is conveniently described in ASTM E168 (Standard Practice for General Techniques of Infrared Quantitative Analysis) or the equivalent ASTM E1252.

[0100] More specifically, the consumption of (meth)acrylate double bonds was measured at 1715 cm to compensate for measurement variations. -1 (ν(C=O), area A 1715 1635 cm, which corresponds to the area of ​​the carbonyl stretching absorption band at -1 (Extension ν(C=C), area A 1635 The double bond conversion rate was estimated from the area of ​​the absorption peak at DBC(%)=100[1-(A 1635 / A 1715 ) 硬化後 / (A 1635 / A 1715 ) 液体 ] A of the liquid composition after hardening and the initial liquid composition 1635 / A 1715 It was estimated by comparing the ratios.

[0101] Example 1: Synthesis of crosslinker G1 1 mol of 1,4-bis(vinyloxy)butane is reacted with 2 mol of methacrylic acid to give L 1is the butylene moiety, and R 1 is methyl and R 3 is hydrogen, thereby obtaining a crosslinker G1 of formula (3).

[0102] Example 2: Synthesis of crosslinker G2 1 mol of tripropylene glycol divinyl ether is reacted with 2 mol of methacrylic acid to give L 1 has for the general formula -(-OCH2CH(CH3)-)3-, and R 1 is methyl and R 3 is hydrogen, thereby obtaining a crosslinker G2 of formula (3).

[0103] Example 3: Synthesis of crosslinker G3 1,1-di(2-acryloxyethoxy)cyclopentane (R 2 and R 3 Synthesis of (is linked by a cyclopentane ring). 2-Hydroxyethyl acrylate and cyclopentanone are dissolved in tetrahydrofuran in a molar ratio of 1:1:0.8, and 0.1 equivalents of p-toluenesulfonic acid pyridinium salt (PPTS) and an appropriate amount of 5 Å molecular sieves are added at room temperature. After 48 hours, the reaction mixture is neutralized with 0.1 equivalents of potassium carbonate. After filtration, the filtrate is evaporated to give 1,1-di(2-acryloxyethoxy)cyclopentane as the major product.

[0104] Example 4: Preparation of free radically curable composition F1 100 pbw of crosslinker G2 was mixed with 1 pbw of photoinitiator (ADDITOL® BCPK). The resulting free radical curable composition was coated onto a glass substrate, covered with a polypropylene film, and then exposed to UV light (LED spot Honle) 14 cm from the substrate for 3 minutes, providing 110 mW cm at a wavelength of 365 nm. -2 After polymerization, the (meth)acrylate double bond conversion of the cured composition was 80%. g The temperature was 110°C.

[0105] Example 5: Preparation of free radically curable composition F2 50 pbw of crosslinker G1 was mixed with 50 pbw of 2-hydroxypropyl methacrylate. To this mixture, 1 pbw of photoinitiator (ADDITOL® BCPK) was added. The resulting free radical curable composition was coated onto a glass substrate, covered with a polypropylene film, and then exposed to UV light (LED spot Honle) at a wavelength of 365 nm for 3 minutes, providing 110 mW cm of light. -2 After polymerization, the (meth)acrylate double bond conversion (DBC) of the cured composition was 80%. g The temperature was 125°C.

[0106] Comparative Example 1: Preparation of free radically curable composition C1 50 pbw of 1,6-hexanediol diacrylate was mixed with 50 pbw of 2-hydroxyethyl methacrylate. To this mixture, 1 pbw of photoinitiator (ADDITOL® BCPK) was added. The resulting free radical curable composition was coated onto a glass substrate, covered with a polypropylene film, and then exposed to UV light (LED spot Honle) at a wavelength of 365 nm for 3 minutes, providing 110 mW cm. -2 After polymerization, the (meth)acrylate double bond conversion (DBC) of the cured composition was 82%. g The temperature was 101°C.

[0107] Comparative Example 2: Preparation of free radically curable composition C2 50 pbw of 1,6-hexanediol diacrylate was mixed with 50 pbw of 2-hydroxypropyl methacrylate. To this mixture, 1 pbw of photoinitiator (ADDITOL® BCPK) was added. The resulting free radical curable composition was coated onto a glass substrate, covered with a polypropylene film, and then exposed to UV light (LED spot Honle) at a wavelength of 365 nm for 3 minutes, providing 110 mW cm. -2After polymerization, the (meth)acrylate double bond conversion (DBC) of the cured composition was 80%. g was 98°C.

[0108] Example 6: Preparation of free radically curable composition F3 50 pbw of crosslinker G2 was mixed with 50 pbw of 2-hydroxyethyl methacrylate. To this mixture, 1 pbw of photoinitiator (ADDITOL® BCPK) was added. The resulting free radical curable composition was coated onto a glass substrate, covered with a polypropylene film, and then exposed to UV light (LED spot Honle) at a wavelength of 365 nm for 3 minutes, providing 110 mW cm of light. -2 After polymerization, the (meth)acrylate double bond conversion (DBC) of the cured composition was 72%. g The temperature was 122°C.

[0109] Example 7: Preparation of free radically curable composition F4 50 pbw of crosslinker G2 was mixed with 50 pbw of 2-hydroxypropyl methacrylate. To this mixture, 1 pbw of photoinitiator (ADDITOL® BCPK) was added. The resulting free radical curable composition was coated onto a glass substrate, covered with a polypropylene film, and then exposed to UV light (LED spot Honle) at a wavelength of 365 nm for 3 minutes, providing 110 mW cm of light. -2 After polymerization, the (meth)acrylate double bond conversion (DBC) of the cured composition was 73%. g The temperature was 117°C.

[0110] Example 8: Preparation of free radically curable composition F5 50 pbw of crosslinker G2 was mixed with 25 pbw of 2-hydroxypropyl methacrylate and 25 pbw of isobornyl methacrylate. To this mixture, 1 pbw of photoinitiator (ADDITOL® BCPK) was added. The resulting free radical curable composition was coated onto a glass substrate, covered with a polypropylene film, and then exposed to UV light (LED spot Honle) at a wavelength of 365 nm for 3 minutes, providing 110 mW cm. -2 After polymerization, the (meth)acrylate double bond conversion (DBC) of the cured composition was 72%. g The temperature was 135°C.

[0111] Example 9: Preparation of free radically curable composition F6 100 pbw of crosslinker G1 was mixed with 1 pbw of photoinitiator (ADDITOL® BCPK). The resulting free radical curable composition was coated onto a glass substrate, covered with a polypropylene film, and then exposed to UV light (LED spot Honle) at a wavelength of 365 nm and 110 mW cm for 3 minutes, located 14 cm from the substrate. -2 After polymerization, the (meth)acrylate double bond conversion of the cured composition was 80%. g The temperature was 85°C.

[0112] Example 10: Dissolution of hardened samples in 30% or 100% acetic acid Cured compositions C1-C3 and F1-F6 were immersed in either 30% or 100% acetic acid at 80°C for one week, followed by one week at room temperature. The table below indicates whether the cured compositions were either undissolved (1), partially dissolved (2), or completely dissolved (3) after two weeks. Partial dissolution generally resulted in easier separation of the cured composition from the substrate than complete dissolution. As can be seen in Examples F5 and F1, the cleavage environment can vary depending on the composition. Those skilled in the art will be able to determine the appropriate conditions. [Table A]

[0113] Comparative Example 4: Preparation of free radically curable composition C4 100 pbw of 2-hydroxypropyl methacrylate was mixed with 1 pbw of photoinitiator (ADDITOL® BCPK). The resulting free radical curable composition was coated onto a glass substrate, covered with a polypropylene film, and then exposed to UV light (LED spot Honle) 14 cm from the substrate for 3 minutes, providing 110 mW cm at a wavelength of 365 nm. -2 After polymerization, the (meth)acrylate double bond conversion rate of the cured composition was 100%. g The temperature was 117°C.

[0114] Example 11: Synthesis of crosslinker G4 Reaction of triethylene glycol divinyl ether with adipic acid (HOOC-(CH2)4-COOH) followed by reaction with methacrylic acid; L 1 = triethylene glycol; L 2 =(CH2)4. 7.23 g of adipic acid and 29 g of 1,4-dioxane were added to a 50 ml glass reactor and heated to 80° C. under stirring. Then, 20 g of triethylene glycol divinyl ether dissolved in 10 g of 1,4-dioxane was added. The reaction mixture was further heated at 80° C. for 14 hours, after which the solvent was evaporated. The formation of the acetal -O-CH(CH)-OC(═O)- linking group was 1 The reaction was clearly evidenced by H-NMR signals at 1.40 ppm (CH3) and 5.94 ppm -O-CH(CH3)-O-CO-. 10 g of the resulting product with vinyl ether residues was further reacted with 3 g of methacrylic acid and heated at 50 °C for 14 h. The reaction of the vinyl ether residues with methacrylic acid was confirmed by GPC analysis (peaks shifted to higher molecular weights). The viscosity was 139 mPas at 25 °C.

[0115] Example 12: Synthesis of Crosslinker G5 Reaction of 1,4-butanediol divinyl ether with oxalic acid (HOOC-COOH) and subsequent reaction with methacrylic acid; L 1 =(CH2)4;L 2 :Single bond. 10 g of 1,4-butanediol divinyl ether and 5 g of THF were added to a 50 ml glass reactor and stirred at room temperature. Next, 3.17 g of oxalic acid dissolved in 10 g of THF was slowly added to the reactor, and the reaction mixture was further stirred at room temperature for 7 hours, after which the solvent was evaporated. The formation of the acetal -O-CH(CH3)-OC(=O)- linking group was 1 This was clearly evidenced by H-NMR signals at 1.50 ppm (CH3) and 6.03 ppm O-CH(CH3)-O-CO. The vinyl ether residue was reacted with one equivalent of (meth)acrylic acid.

[0116] Example 13: Preparation of glass fiber composite A series of glass fiber composites were prepared as follows.

[0117] It forms three layers and 2 50 pbw of glass fibers weighing 390 g per fiber were immersed in 50 pbw of resin mixed with 1 pbw of ADDITOL® HDMAP and 0.25 pbw of bis-acylphosphine oxide, two photoinitiators.

[0118] These soaked fiber sheets were then cured as follows: both the top and backside were irradiated with 80 W / cm2 for the top side at a conveyor speed of 10 m / min. 2 Two Ga lamps were used at a power density of 120 W / cm, then at a conveyor speed of 5 m / min. 2 The back side was irradiated with two Ga lamps at 120 W / cm at a conveyor speed of 5 m / min. 2 This was done using two Ga lamps.

[0119] Composites containing the following resins were prepared: 100% G1, 100% G2, 100% HEMA (2-hydroxyethylmethacrylate), 100% HPMA (2-hydroxypropyl methacrylate), and 100% Raylok C1100 (a styrene-free vinyl ester-based resin specifically developed for making glass fiber composites that are cured by ultraviolet (UV) light).

[0120] Example 14: Testing of glass fiber composites The composite of Example 13 was cut into 2 x 5 cm strips and introduced into a test vessel with 30% (w / v) acetic acid at 80°C. The results are shown in the table below. [Table B]

[0121] As can be observed, the fibers of the inventive composite were completely separated from the resin after one week of treatment, which was not the case for the comparative example.

[0122] Example 15: Synthesis of crosslinker G4 Synthesis of 2,2-di(2-methacryloxyethoxy)propane (ketal dimethacrylate) obtained by reacting 2-hydroxyethyl methacrylate with 2,2-dimethoxypropane according to reaction conditions similar to those described in Preparation Example 1 of WO2015164087.

[0123] Example 16: Preparation of free radically curable composition F7 10 pbw of crosslinker G4 was mixed with 1 pbw of photoinitiator (ADDITOL® BCPK) and 90 pbw of 2-hydroxypropyl methacrylate. A 0.5 cm diameter and 1 mm thick cured disk of the resulting free radically curable composition was exposed for 3 minutes to UV light (LED spot Honle) located 14 cm from the composition, protected by a polypropylene film, and irradiated with 110 mW cm at a wavelength of 365 nm. -2After polymerization, the cured composition had a methacrylate double bond conversion of greater than 75%.

[0124] Example 17: Testing of glass fiber composites The composite was prepared using F7 as described in Example 13. The dissolution conditions were 100° C. for 3 hours in 30 wt % acetic acid. The fibers of the composite could be easily peeled off.

Claims

1. 1. A composite comprising a filler and a post-cure free radical curable composition that is cleavable, wherein the pre-cure free radical curable composition comprises the following components: ・General formula E １ -O-C(R ２ ) (R ３ )-X-E ２ (1) (where E １ and E ２ each contains a free radically polymerizable ethylenically unsaturated moiety, X is either oxygen (O) or sulfur (S), and R ２ and R ３ are independently selected from the list consisting of hydrogen, alkyl, alkenyl, alkynyl, cycloalkyl, cycloalkenyl, cycloalkynyl, aryl, heterocycloalkyl, heterocycloalkenyl, heteroaryl, alkoxyaryl, and alkoxyalkyl, or C(R ２ ) (R ３ ) are linked to form a cycloalkyl, cycloalkenyl, cycloalkynyl, aryl, heterocycloalkyl, heterocycloalkenyl, heteroaryl, or alkoxyaryl ring system; R ２ and R ３ are independently or C(R ２ ) (R ３ ) forms a ring structure, at least one bridge molecule component a of ) which is either substituted or unsubstituted, and Optionally, the moiety —O—C(R ２ ) (R ３ ) at least one free radically polymerizable ethylenically unsaturated molecular component b that does not contain —X—; Including, When the composition cures, it exhibits a T of greater than 50° C. as measured by dynamic mechanical thermal analysis (DMTA). ｇ and the filler is an organic fiber or an inorganic fiber. Composite.

2. Component b., upon polymerization, exhibits a T of greater than 10°C as measured by DMTA. ｇ 10. The composite of claim 1, having:

3. 3. The composite of claim 1 or 2, wherein component b. is present in an amount of at least 1 wt.%, preferably at least 5 wt.%, and more preferably at least 30 wt.% of the sum of components a. and b.

4. 4. The composite of any one of claims 1 to 3, wherein the concentration of component b. is less than 95 wt%.

5. 5. The composite of any one of claims 1 to 4, wherein each of components b. comprises one or two free radically curable moieties.

6. 6. The composite of claim 1, wherein at least one of components b. comprises a hydroxyl moiety.

7. 7. The composite of claim 1, wherein E1 and E2 each comprise either an acrylate moiety or a methacrylate moiety.

8. The one or more bridging molecules are 【Chemical 1】 (In the formula, X １ is selected from O, C(O)O, C is directly bonded to L, and R １ are independently selected from hydrogen and methyl; L, L １ and L １’ are independently selected from divalent linking moieties; D is independently selected from O; m is 1-10; and n is 1-10.

8. The composite of claim 1 having a general formula selected from:

9. 9. The composite of any one of claims 1 to 8, wherein the amount of component a. is greater than 5 wt% of the sum of component a. and component b.

10. 10. The composite of any one of claims 1 to 9, wherein the free radically curable composition has a viscosity of less than 1000 mPa.s at 25°C.

11. 11. The composite of claim 1 having a Young's modulus at 20°C of at least 10 MPa.

12. 12. The composite of claim 1, wherein the filler is selected from glass fibers, carbon fibers and / or natural fibers.

13. 13. A method for at least partially recycling a filler and, optionally, a cleaved cured free radically curable composition of a composite according to any one of claims 1 to 12, comprising the steps of: subjecting the cured free radically curable composition to a cleavage environment comprising at least one of an aqueous liquid, an alcohol, an acid, and a temperature above 40°C; The above method, comprising:

14. 14. The method of claim 13, further comprising recovering at least a portion of the cleaved cured free radically curable composition of the filler and / or the composite.

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