Type i photoinitiators for crosslinking silicone compositions

Abstract

This invention relates to a type I photoinitiator for free radical crosslinking of radiation-crosslinkable compositions. Specifically, this invention relates to a silicone composition comprising a type I photoinitiator and an organopolysiloxane having at least one (meth)acrylate group.

Description

Technical Field

[0001] The subject of this invention is a type I photoinitiator for free radical curing of radiation-curable compositions. Specifically, this invention relates to a silicone composition comprising a type I photoinitiator and an organopolysiloxane comprising at least one (meth)acrylate group. Background Technology

[0002] Using plastic films as a substrate for applying silicone coatings to form release coatings (non-stick coatings) requires appropriate technology. In fact, most of these plastic films are heat-sensitive. Therefore, under the combined effects of tension and temperature, the film undergoes dimensional deformation during the coating and drying of the silicone layer in a hot oven. The technique of curing functional silicone oils under radiation, particularly ultraviolet (UV) radiation, allows for the curing of release coatings without the need for high temperatures, thus curing them without affecting the substrate. Furthermore, this technology offers the advantage of achieving high productivity without consuming large amounts of energy or using solvents. Plastic substrates are the material of choice for many applications, and their use continues to increase.

[0003] The preparation of silicone release coatings is typically carried out as follows: a silicone composition is applied to a substrate in an industrial coating apparatus, which includes rollers operating at very high speeds (e.g., 600 m / min). Once applied to the substrate, the silicone composition is cured to form a solid silicone (e.g., elastomer) release coating. The resulting coated substrate is also called a silicone liner. This silicone liner is particularly suitable for adhesive lamination because the silicone release coating facilitates the removal of adhesive material reversibly bonded to these substrates. Therefore, these silicone liners can be used in self-adhesive labels, strips (including envelopes), graphic arts, and healthcare and wellness applications.

[0004] Silicone compositions used to form release coatings are typically cured (crosslinked) under radiation, particularly UV or visible light radiation emitted by doped or undoped mercury vapor lamps with emission spectra extending from 200 nm to 450 nm. Light sources such as light-emitting diodes (more commonly known as "LEDs"), which emit speckled ultraviolet or visible light, can also be used.

[0005] Radiation curing of functionalized silicone oils can be carried out using two methods: cationic polymerization of epoxy groups or free radical polymerization of acrylic functional groups. Free radical polymerization is neither inhibited by alkali nor by humidity. Therefore, coating substrates and additives can be more diverse, and interest in such free radical systems is constantly increasing.

[0006] The free radical polymerization of molecules with acrylic functional groups under radiation, particularly ultraviolet radiation, is well documented. Generally speaking, free radical photoinitiator molecules promote curing under radiation. Numerous documents describe free radical photoinitiators and their applications. In the field of free radical polymerization of acrylic-silicone compositions, commonly used photoinitiator molecules are referred to as Type I photoinitiators. Under radiation, these molecules split and generate free radicals. These free radicals initiate polymerization reactions, leading to the hardening of the composition. Much effort has been made to endow Type I photoinitiators with properties that allow them to be used in silicone-acrylic formulations to obtain release coatings. Throughout this application, the term "Type I photoinitiator" is understood to refer to compounds capable of generating polymerization-initiating free radicals through intramolecular homolytic cleavage under radiation.

[0007] There also exist type II photoinitiator systems that include free radical photoinitiators and co-initiators. In type II photoinitiator systems, the photoinitiator used can generate polymerization initiating radicals by reacting with another compound called a co-initiator, the reaction causing hydrogen to transfer from the co-initiator to the photoinitiator. The photoinitiator used in type II photoinitiator systems is called a "type II photoinitiator".

[0008] Type I photoinitiators are commonly used, but they also have drawbacks. Specifically, the solubility of these photoinitiators in silicone compositions is not always optimal. In addition, photoinitiators and their decomposition products (such as benzaldehyde) pose health risks and produce unpleasant odors.

[0009] Therefore, it is necessary to develop type I photoinitiators that can overcome these drawbacks.

[0010] In this context, the present invention aims to satisfy at least one of the following objectives.

[0011] One of the basic objectives of this invention is to provide a radiation-curable silicone composition containing a type I photoinitiator, which can be used to form a release coating.

[0012] Another fundamental objective of this invention is to provide a radiation-curable silicone composition containing a type I photoinitiator and having improved performance.

[0013] Another fundamental objective of this invention is to provide a radiation-curable silicone composition comprising a type I photoinitiator and having improved properties in terms of conversion rate and / or reaction kinetics.

[0014] Another fundamental objective of the present invention is to provide a radiation-curable silicone composition comprising a type I photoinitiator, wherein the decomposition products of the photoinitiator have reduced toxicity and / or a low likelihood of migration through the coating.

[0015] Another fundamental objective of this invention is to provide a compound that can be used as a free radical photoinitiator in radiation-curable compositions.

[0016] Another fundamental objective of this invention is to provide a compound that can be used as a free radical photoinitiator and is soluble in silicone compositions, preferably rapidly soluble in silicone compositions. Summary of the Invention

[0017] These objectives are achieved in particular by the present invention, which first relates to a radiation-curable silicone composition X comprising:

[0018] a. At least one organopolysiloxane A containing at least one (meth)acrylate group;

[0019] b. At least one free radical photoinitiator B, which is a compound of formula (I).

[0020]

[0021] in

[0022] -R1 and R2 are independently selected from C1-C6 alkyl and C3-C7 cycloalkyl;

[0023] Alternatively, R1 and R2 together with the carbon atoms they are attached to form C3-C7 cycloalkyl groups;

[0024] -R3 is H or a C1-C6 alkyl group, preferably R3 is H;

[0025] -R4 is Group;

[0026] - Each R5 group independently represents a C1-C6 alkyl group;

[0027] -n = 0, 1, 2, 3 or 4, preferably n = 0, 1 or 2;

[0028] -R9 is a C1-C6 alkylene or a C1-C6 heteroalkylene; and

[0029] -R 10 It is a straight chain or a branched C1-C 18 Alkyl groups, preferably straight-chain or branched C2-C 17 Alkyl groups, more preferably straight-chain or branched C4-C 13 Alkyl groups, or even more preferably straight-chain or branched C9 alkyl groups.

[0030] The use of free radical photoinitiator B enables the preparation of silicone composition X with excellent properties in terms of conversion and reaction kinetics. Furthermore, the use of free radical photoinitiator B allows for the preparation of silicone release coatings with good properties. Free radical photoinitiator B also allows for good curing of silicone composition X.

[0031] Furthermore, the decomposition products of free radical photoinitiator B have a lower migration potential than existing commercial photoinitiators.

[0032] Free radical photoinitiator B also exhibits good solubility in silicone. Therefore, pure photoinitiator can be used, directly diluted in organopolysiloxane A. Advantageously, free radical photoinitiator B can dissolve in organopolysiloxane A in less than 15 hours, or less than 10 hours, or less than 5 hours, or less than 2 hours. For example, the solubility can be determined by adding 1.5 to 3 parts by weight of free radical photoinitiator B to 100 parts by weight of organopolysiloxane A.

[0033] Another advantage of free radical photoinitiator B is the transparency of the elastomer obtained after curing silicone composition X.

[0034] The present invention also relates to the use of the silicone composition X described in this application for the preparation of silicone elastomers that can be used as release coatings on substrates.

[0035] The present invention also relates to a silicone elastomer obtained by curing the silicone composition X described in this application.

[0036] The present invention also relates to a method for preparing a coating on a substrate, comprising the following steps:

[0037] - Apply the silicone composition X described in this application, and

[0038] - The composition is cured by electron or photon radiation, preferably by exposure to an electron beam, by exposure to gamma rays, or by exposure to radiation with a wavelength of 200 nm to 450 nm, especially UV radiation.

[0039] The present invention also relates to a coating substrate that can be obtained by this method.

[0040] The present invention also relates to the use of the composition X according to the invention for preparing silicone elastomer articles by an additive manufacturing process.

[0041] The present invention also relates to a compound of formula (I).

[0042]

[0043] in

[0044] -R1 and R2 are independently selected from C1-C6 alkyl and C3-C7 cycloalkyl;

[0045] Alternatively, R1 and R2 together with the carbon atoms they are attached to form C3-C7 cycloalkyl groups;

[0046] -R3 is H or a C1-C6 alkyl group, preferably R3 is H;

[0047] -R4 is Group;

[0048] - Each R5 group independently represents a C1-C6 alkyl group;

[0049] -n = 0, 1, 2, 3 or 4, preferably n = 0, 1 or 2;

[0050] -R9 is a C1-C6 alkylene or a C1-C6 heteroalkylene; and

[0051] -R 10 It is a straight chain or a C2-C with branches. 18 Alkyl groups, preferably straight-chain or branched C4-C. 13 Alkyl groups, more preferably straight-chain or branched C9 alkyl groups.

[0052] The present invention also relates to the use of compounds as free radical photoinitiators as defined in this application.

[0053] definition

[0054] In this application, the term "radiation-curable silicone composition" is understood to mean a silicone composition comprising at least one organopolysiloxane capable of being cured by electron or photon radiation. Electron radiation includes exposure to an electron beam. Photon radiation includes exposure to radiation with wavelengths from 200 nm to 450 nm, particularly UV radiation, or exposure to gamma rays.

[0055] "(Meth)acrylate" is understood to refer to methacrylate groups or acrylate groups.

[0056] "Alkyl" is understood to refer to a straight-chain or branched alkyl group. Alkyl groups preferably contain 1 to 6 carbon atoms.

[0057] "alkylene" is understood to refer to a divalent straight-chain or branched alkyl group. Alkylene preferably contains 1 to 6 carbon atoms, more preferably 1 to 4 carbon atoms.

[0058] "Heteroalkylene" is understood to refer to a divalent straight-chain or branched heteroalkyl group. The heteroalkyl group preferably comprises 1 to 6 carbon atoms and 1 to 3 heteroatoms selected from the group consisting of O, N, and S, wherein N and S may optionally be oxidized. The heteroatoms can be located at any position, inside, or at one end of the heteroalkyl group.

[0059] In this application, unless otherwise stated, all percentages are expressed in weight %. Detailed Implementation

[0060] Curable silicone composition X

[0061] This invention first relates to a radiation-curable silicone composition X, comprising:

[0062] a. At least one organopolysiloxane A containing at least one (meth)acrylate group;

[0063] b. At least one free radical photoinitiator B, which is a compound of formula (I).

[0064]

[0065] in

[0066] -R1 and R2 are independently selected from C1-C6 alkyl and C3-C7 cycloalkyl;

[0067] Alternatively, R1 and R2 together with the carbon atoms they are attached to form C3-C7 cycloalkyl groups;

[0068] -R3 is H or a C1-C6 alkyl group, preferably R3 is H;

[0069] -R4 is Group;

[0070] - Each R5 group independently represents a C1-C6 alkyl group;

[0071] -n = 0, 1, 2, 3 or 4, preferably n = 0, 1 or 2;

[0072] -R9 is a C1-C6 alkylene or a C1-C6 heteroalkylene; and

[0073] -R 10 It is a straight chain or a branched C1-C 18 Alkyl groups, preferably straight-chain or branched C2-C 17 Alkyl groups, more preferably straight-chain or branched C4-C 13 Alkyl groups, and even more preferably straight-chain or branched C9 alkyl groups.

[0074] According to one embodiment, the silicone composition X can be cured by photon radiation, preferably by exposure to radiation with a wavelength of 200 nm to 450 nm, especially UV radiation.

[0075] According to one embodiment, the radiation-curable silicone composition X has a viscosity of 50 mPa·s to 2500 mPa·s, preferably 100 mPa·s to 1500 mPa·s. Therefore, it can be used with a coating tool for preparing a silicone release coating.

[0076] All viscosities mentioned in this specification correspond to the dynamic viscosity at 25°C, i.e., the dynamic viscosity measured using a Brinell viscometer in a manner known per se at a sufficiently low shear rate gradient, and the measured viscosity is independent of the rate gradient.

[0077] Organopolysiloxane A

[0078] According to the present invention, the curable silicone composition X according to the present invention comprises at least one organopolysiloxane A, which contains at least one (meth)acrylate group, preferably at least two (meth)acrylate groups.

[0079] As representatives of the (meth)acrylate functional groups carried by silicones and most particularly suitable for the present invention, acrylates, methacrylates, ethers of (meth)acrylates, and ester derivatives of (meth)acrylates linked to polysiloxane chains via Si-C bonds can be specifically mentioned.

[0080] According to one embodiment, organopolysiloxane A comprises:

[0081] a) At least one unit having the following formula (IV):

[0082] R a Z b SiO (4-a-b) / 2 (IV)

[0083] in:

[0084] - The same or different R symbols each represent a straight chain or a chain with branches, C1 to C1. 18 Alkyl, C6 to C 12 aryl or aralkyl, wherein the alkyl and aryl groups may be substituted, preferably substituted with halogen atoms, or -OR 5 Group, wherein R 5 It is a hydrogen atom or a hydrocarbon group containing 1 to 10 carbon atoms.

[0085] The -Z symbol represents a monovalent group in the formula -y-(Y')n, where:

[0086] -y indicates polyvalent C1-C 18 The alkylene or heteroalkylene groups may be straight-chain or branched, and may be interrupted by one or more cycloalkylene groups, and may be extended by C1 to C4 divalent alkylene or polyalkylene radicals. The alkylene, heteroalkylene, alkylene oxide, and polyalkylene oxide groups may be substituted with one or more hydroxyl groups.

[0087] -Y' represents a monovalent alkenyl carbonyl group, and

[0088] -n equals 1, 2, or 3, and

[0089] -a is an integer equal to 0, 1, or 2, b is an integer equal to 1 or 2, and the sum of a and b equals 1, 2, or 3;

[0090] b) Optionally, a unit having the following formula (V):

[0091] R a SiO (4-a) / 2 (V)

[0092] in:

[0093] The -R symbol is defined as in equation (IV) above, and

[0094] -a is an integer equal to 0, 1, 2 or 3.

[0095] In equations (IV) and (V) above, the same or different R symbols each represent a straight chain or a branched chain from C1 to C2. 18 Alkyl or C6 to C 12 Aryl or aralkyl. Preferably, the symbol R represents a monovalent group selected from methyl, ethyl, propyl, 3,3,3-trifluoropropyl, xylyl, tolyl and phenyl, and more preferably, the symbol R represents methyl.

[0096] Organopolysiloxane A can have a linear, branched, cyclic, or network structure. Preferably, organopolysiloxane A has a linear structure. When linear organopolysiloxanes are involved, they can essentially consist of the following:

[0097] - "D" silaneoxy unit, selected from formula R2SiO 2 / 2 , RZSiO 2 / 2 and Z2SiO 2 / 2 Units;

[0098] - "M" silaneoxy unit, selected from formula R3SiO 1 / 2 R2ZSiO 1 / 2 RZ2SiO 1 / 2 and Z3SiO 1 / 2 The unit, and

[0099] The -R and Z symbols are defined as in formula (I) above.

[0100] According to one embodiment, in formula (IV) above, the aforementioned Y'-alkenyl carbonyloxy group includes acryloyloxy [CH2=CH–CO–O–] and methacryloyloxy [CH2=C(CH3)–CO–O–]. Advantageously, the organopolysiloxane A contains at least two Y'-alkenyl carbonyloxy groups, preferably at least three Y'-alkenyl carbonyloxy groups.

[0101] As examples of the y symbol in the unit of formula (IV), the following groups can be mentioned:

[0102] –CH2–;

[0103] –(CH2)2–;

[0104] –(CH2)3–;

[0105] –CH2-CH(CH3)-CH2–;

[0106] –(CH2)3-NR'-CH2-CH2–; where R' is a C1-C6 alkyl group.

[0107] –(CH2)3-OCH2–;

[0108] –(CH2)3-[O-CH2-CH(CH3)-] n -; where n = 1 to 25

[0109] –(CH2)3-O-CH2-CH(OH)(-CH2-);

[0110] –(CH2)3-O-CH2-C(CH2-CH3)[-(CH2-)]2;

[0111] –(CH2)3-O-CH2-C[-(CH2)-]3; and

[0112] –(CH2)2-C6H9(OH)-.

[0113] Preferably, the organopolysiloxane A corresponds to the following formula (VI):

[0114]

[0115] in

[0116] - Same or different R 1 The symbols represent C1 to C1 of a straight chain or a branched chain. 18 Alkyl, C6 to C 12 aryl or aralkyl, wherein the alkyl and aryl groups may be substituted, preferably substituted with halogen atoms, or -OR 5 Group, wherein R 5 It is a hydrogen atom or a hydrocarbon group containing 1 to 10 carbon atoms.

[0117] - Same or different R 2 and R 3 Each symbol represents R 1 A group or a monovalent group of the formula Z = –y-(Y')n, wherein:

[0118] -y indicates polyvalent C1-C18 The alkylene or heteroalkylene groups may be straight-chain or branched, and may be interrupted by one or more cycloalkylene groups, and may be extended by C1 to C4 divalent alkylene or polyalkylene radicals. The alkylene, heteroalkylene, alkylene oxide, and polyalkylene oxide groups may be substituted with one or more hydroxyl groups.

[0119] -Y' represents a monovalent alkenyl carbonyl group.

[0120] -n equals 1, 2, or 3, and

[0121] Where a = 0 to 1000, b = 0 to 500, c = 0 to 500, d = 0 to 500, and a + b + c + d = 0 to 2500, preferably a = 0 to 500 and a + b + c + d = 0 to 500.

[0122] -The condition is that there is at least one R 2 Or R 3 The monovalent group represented by the symbol Z preferably has at least two R groups. 2 Or R 3 The symbol Z represents a monovalent group.

[0123] According to a preferred embodiment, in the above formula (VI):

[0124] -c = 0, d = 0, a = 1 to 1000, b = 1 to 250, symbol R 2 The monovalent group represented by formula Z, and symbol R 1 and R 3 It has the same meaning as the one mentioned above.

[0125] Even more preferably, in the above formula (VI):

[0126] -c = 0, d = 0, a = 1 to 500, b = 2 to 100, symbol R 2 The monovalent group represented by formula Z, and symbol R 1 and R 3 It has the same meaning as the one mentioned above.

[0127] According to one embodiment, the organopolysiloxane A according to the present invention corresponds to one of the following formulas (VII), (VIII), (IX) or (X):

[0128]

[0129] in:

[0130] -x1 is 1 to 1000; preferably, x1 is 1 to 500.

[0131] -n1 is 1 to 100, preferably 2 to 100.

[0132] -x2 is from 1 to 1000, preferably from 1 to 500.

[0133] -n2 is from 1 to 100, preferably from 2 to 100.

[0134] -x3 is from 1 to 1000, preferably, x3 is from 1 to 500, and

[0135] -x4 is 1 to 1000, preferably 1 to 500.

[0136] The radiation-curable silicone composition X may contain 25% to 99.99% organopolysiloxane A relative to the total weight of the radiation-curable silicone composition X. Preferably, the radiation-curable silicone composition X may contain 50% to 99.5% organopolysiloxane A relative to the total weight of the radiation-curable silicone composition X.

[0137] Of course, depending on the variant, organopolysiloxane A can be a mixture of compounds that satisfy the definition of organopolysiloxane A.

[0138] Free radical photoinitiator B

[0139] Free radical photoinitiator B is a type I photoinitiator. After photon irradiation, free radical photoinitiator B undergoes homolytic cleavage at the α-position of the carbonyl functional group, forming two free radical fragments, one of which is a benzoyl free radical substituted with an R4 group.

[0140] Photoinitiator B can improve the properties of silicone composition X, particularly in terms of conversion rate and reaction kinetics. Furthermore, the free radical photoinitiator B enables good curing of silicone composition X.

[0141] Relative to the total weight of the radiation-curable silicone composition X, the silicone composition X may contain 0.01 wt% to 20 wt% of free radical photoinitiator B. Preferably, the radiation-curable silicone composition X contains 0.1 wt% to 10 wt%, more preferably 0.1 wt% to 5 wt% of free radical photoinitiator B.

[0142] Free radical photoinitiator B is a compound of formula (I).

[0143]

[0144] in

[0145] -R1 and R2 are independently selected from C1-C6 alkyl and C3-C7 cycloalkyl;

[0146] Alternatively, R1 and R2 together with the carbon atoms they are attached to form C3-C7 cycloalkyl groups;

[0147] -R3 is H or a C1-C6 alkyl group, preferably R3 is H;

[0148] -R4 is Group;

[0149] - Each R5 group independently represents a C1-C6 alkyl group;

[0150] -n = 0, 1, 2, 3 or 4, preferably n = 0, 1 or 2;

[0151] -R9 is a C1-C6 alkylene or a C1-C6 heteroalkylene; and

[0152] -R 10 It is a straight chain or a branched C1-C 18 Alkyl groups, preferably straight-chain or branched C2-C 17 Alkyl groups, more preferably straight-chain or branched C4-C 13 Alkyl groups, and even more preferably straight-chain or branched C9 alkyl groups.

[0153] According to one embodiment, the compound of formula (I) is the compound of formula (II).

[0154]

[0155] According to one embodiment, the compound of formula (I) is the compound of formula (III).

[0156]

[0157] Advantageously, R1 and R2 are independently selected from C1-C6 alkyl groups. Preferably, R1 and R2 are each methyl.

[0158] Advantageously, R3 is H.

[0159] According to one embodiment, n = 0. According to another embodiment, n = 1 or 2, and each R5 group independently represents a C1-C6 alkyl group, preferably methyl.

[0160] According to one embodiment, R9 is a C1-C6 heteroalkylene group, particularly –O(CH2)2- group, wherein an oxygen atom is attached to a phenyl group.

[0161] R 10 It is a straight chain or a branched C1-C 18 Alkyl groups, preferably straight-chain or branched C2-C 17 Or C2-C 18 Alkyl groups, more preferably straight-chain or branched C4-C 13Or C3-C 10 Alkyl groups, or even more preferably straight-chain or branched C9 alkyl groups.

[0162] According to one implementation, R 10 It is a straight chain or a branched C1-C 18 Alkyl groups, preferably straight-chain or branched C1-C 13 Alkyl groups, more preferably straight-chain or branched C1-C 10 Alkyl groups, or even more preferably straight-chain or branched C1-C9 alkyl groups.

[0163] According to one implementation, R 10 It is a straight chain or a C2-C with branches. 18 Alkyl groups, preferably straight-chain or branched C2-C 13 Alkyl groups, more preferably straight-chain or branched C2-C 10 Alkyl groups, or even more preferably straight-chain or branched C2-C9 alkyl groups.

[0164] According to one implementation, R 10 It is a branched C1-C 18 Alkyl groups, preferably branched C2-C 17 Or C3-C 18 Alkyl groups, more preferably branched C4-C 13 Alkyl groups, or even more preferably branched C9 alkyl groups.

[0165] R 10 Examples of the groups include branched C4 alkyl, branched C6 alkyl, branched C8 alkyl, branched C9 alkyl, and branched C... 11 Alkyl groups and branched C 13 alkyl.

[0166] When R 10 When it is a branched alkyl group, it may include a quaternary carbon. Preferably, the quaternary carbon is located at the α-position of the carbonyl group: the term trialkyl acetate is used. Trialkyl acetate can be derived from cutting oil. According to one embodiment, R 10 The -(CO)-O- group represents a trialkyl acetate, and preferably, R 10 Represents C4, C6, C8, C9, C with branches 11 Or C 13 alkyl.

[0167] In some cases, when R 10 When -(CO)-O- represents a trialkyl acetate derived from cutting oil, several structural isomers may exist. In particular, when R... 10 It is a branched C6, C8, C9, C 11 Or C 13This may be the case with alkyl groups. Therefore, R 10 It can represent a mixture of structural isomers. For example, when R 10 When referring to a branched C9 alkyl group, the alkyl group can contain the following different isomers:

[0168] -C(CH3)2-CH(CH3)-CH2-CH(CH3)2, -C(CH3)(CH(CH3)2)-CH2-CH(CH3)2, -C(CH3)2-(CH2)5-CH3, and -C(CH2-CH3)2-(CH2)3-CH3.

[0169] Other additives

[0170] Radiation-curable silicone composition X may also contain other additives, such as polymerization inhibitors, fillers, antivirals, bactericides, anti-abrasion additives, and pigments (organic or inorganic). For polymerization inhibitors, phenol, hydroquinone, 4-OMe-phenol, 2,4,6-tri-tert-butylphenol (BHT), phenothiazine, and nitro group radicals such as (2,2,6,6-tetramethylpiperidin-1-yl)oxy (TEMPO) may be mentioned.

[0171] The radiation-curable silicone composition X may further comprise an organic compound C, which contains at least one (meth)acrylate functional group. Organic compound C containing at least one (meth)acrylate functional group is understood to refer to any compound containing one or more (meth)acrylate functional groups. According to one embodiment, organic compound C containing at least one (meth)acrylate functional group does not contain a siloxane structure.

[0172] Particularly suitable organic compounds C containing (meth)acrylate functional groups are epoxy (meth)acrylates, polyesters of (meth)acrylate glycerols, urethane (meth)acrylates, polyethers of (meth)acrylates, polyester (meth)acrylates, and acrylic (meth)acrylates. More particularly preferred are trimethylolpropane triacrylate, tripropylene glycol diacrylate, hexanediol diacrylate, and pentaerythritol tetraacrylate.

[0173] Examples of organic compounds C containing (meth)acrylate functional groups include: ethylhexyl acrylate, octadecyl acrylate, tetrahydrofurfuryl acrylate, lauryl acrylate, isodecanyl acrylate, 2(2-ethoxyethoxy)ethyl acrylate, cyclohexyl acrylate, isooctyl acrylate, tridecyl acrylate, isobornyl acrylate, caprolactone acrylate, alkoxylated phenolic acrylate, 1,3-butanediol diacrylate, 1,4-butanediol diacrylate, diethylene glycol diacrylate, neopentyl glycol diacrylate, tetraethylene glycol diacrylate, triethylene glycol diacrylate, dipropylene glycol diacrylate, alkoxylated hexanediol diacrylate, trimethylolpropane triacrylate, ethoxylated trimethylolpropane triacrylate, propoxylated triglyceride triacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, di-trimethylolpropane tetraacrylate, and dipentaerythritol pentaacrylate.

[0174] The radiation-curable silicone composition X may also contain filler. The radiation-curable silicone composition X may contain 0.1% to 40% filler relative to the total weight of the radiation-curable silicone composition X. According to one embodiment, the radiation-curable silicone composition X contains 20% to 30% filler. According to another embodiment, the radiation-curable silicone composition X contains 0.1% to 10% filler. The filler is preferably inorganic. The filler can be a very finely ground product with an average particle size of less than 0.1 μm. The filler can be particularly siliceous. For siliceous materials, they can act as reinforcing or semi-reinforcing fillers. Reinforcing siliceous fillers are selected from colloidal silica, burned and precipitated silica powder, or mixtures thereof. These powders typically have an average particle size of less than 0.1 μm (micrometers) and a BET specific surface area greater than 30 m². 2 / g, preferably 30m 2 / g to 350m 2 / g. Semi-reinforced silica fillers, such as diatomaceous earth or crushed silica, can also be used. These silicas can be incorporated as is or after treatment with organosilicon compounds conventionally used for this purpose. These compounds include: methyl polysiloxanes, such as hexamethyldisiloxane, octamethylcyclotetrasiloxane; methyl polysilazanes, such as hexamethyldisilazane, hexamethylcyclotrisilazane, tetramethyldivinyldisilazane; chlorosilanes, such as dimethyldichlorosilane, trimethylchlorosilane, methylvinyldichlorosilane, dimethylvinylchlorosilane; alkoxysilanes, such as dimethyldimethoxysilane, dimethylvinylmethoxysilane, trimethylmethoxysilane, and mixtures thereof. For non-silica inorganic materials, they can act as semi-reinforced or filled inorganic fillers. Examples of non-silica fillers that can be used alone or in mixtures include calcium carbonate, calcined clay, titanium dioxide in rutile form, iron oxides, zinc oxides, chromium oxides, zirconium oxides or magnesium oxides, various forms of alumina (hydrated or non-hydrated), boron nitride, lithopone, barium metaborate, barium sulfate, and glass microspheres, which may be surface-treated with organic acids or esters of organic acids. These fillers are relatively coarse, with an average particle size typically greater than 0.1 μm and a specific surface area typically less than 30 m² / g. These fillers can be surface-modified by treatment with various organosilicon compounds commonly used for this purpose.

[0175] According to one embodiment, the radiation-curable silicone composition X comprises:

[0176] a. 25% to 99.99% by weight of at least one organopolysiloxane A, which contains at least one (meth)acrylate group;

[0177] b. 0.01% to 20% by weight of at least one free radical photoinitiator B, which is a compound of formula (I).

[0178]

[0179] in

[0180] -R1 and R2 are independently selected from C1-C6 alkyl and C3-C7 cycloalkyl;

[0181] Alternatively, R1 and R2 together with the carbon atoms they are attached to form C3-C7 cycloalkyl groups;

[0182] -R3 is H or a C1-C6 alkyl group, preferably R3 is H;

[0183] -R4 is Group;

[0184] - Each R5 group independently represents a C1-C6 alkyl group;

[0185] -n = 0, 1, 2, 3 or 4, preferably n = 0, 1 or 2;

[0186] -R9 is a C1-C6 alkylene or a C1-C6 heteroalkylene; and

[0187] -R 10 It is a straight chain or a branched C1-C 18 Alkyl groups, preferably straight-chain or branched C2-C 17 Alkyl groups, more preferably straight-chain or branched C4-C 13 Alkyl groups, and even more preferably straight-chain or branched C9 alkyl groups.

[0188] application

[0189] The present invention also relates to the use of radiation-curable silicone composition X for the preparation of silicone elastomers. These silicone elastomers may have release properties relative to the adhesive.

[0190] The present invention also relates to a method for preparing a silicone elastomer, comprising the step of curing a radiation-curable silicone composition X.

[0191] According to one embodiment of the method of the present invention, the curing step is carried out in air or in an inert atmosphere. Preferably, the curing step is carried out in an inert atmosphere.

[0192] According to one embodiment, the curing step of the method according to the invention is carried out by UV radiation with a wavelength of 200 nm to 450 nm, preferably in an inert atmosphere.

[0193] According to another embodiment, the curing step of the method according to the invention is performed by exposure to an electron beam or gamma rays.

[0194] UV radiation can be emitted by doped or undoped mercury vapor lamps with emission spectra extending from 200 nm to 450 nm. Light sources such as light-emitting diodes (more commonly known as "LEDs") can also be used, which emit spot UV or visible light.

[0195] According to a preferred embodiment of the invention, the radiation is ultraviolet light with a wavelength less than 400 nanometers. According to a preferred embodiment of the invention, the radiation is ultraviolet light with a wavelength greater than 200 nanometers.

[0196] According to an advantageous implementation, an LED UV lamp (UV emission at 365nm, 375nm, 385nm and / or 395nm) is used.

[0197] Ultraviolet radiation doses in the range of about 0.1 joules to about 0.5 joules are usually sufficient to induce crosslinking.

[0198] Irradiation time can be very short, typically less than 1 second, and for low coating thicknesses, it is approximately a few hundredths of a second. Even without any heating, the achieved curing is excellent.

[0199] According to one embodiment, the curing step is carried out at a temperature of 10°C to 50°C, preferably 15°C to 35°C.

[0200] Of course, the curing speed can be adjusted specifically by the number of UV lamps used, the duration of UV exposure, and the distance between the composition and the UV lamps.

[0201] The present invention also relates to a method for preparing a coating on a substrate, comprising the following steps:

[0202] - Apply radiation-curable silicone composition X to a substrate, and

[0203] - The composition is cured by electron or photon radiation, preferably by exposure to an electron beam, by exposure to gamma rays, or by exposure to radiation with a wavelength of 200 nm to 450 nm, especially UV radiation.

[0204] According to the invention, the solvent-free composition X, i.e., undiluted, can be applied using an apparatus capable of uniformly depositing small amounts of liquid. For this purpose, an apparatus, for example known as a "Helio glissant," can be used, which specifically comprises two stacked rollers: the lower roller, immersed in a coating tank containing the composition, serves to impregnate the upper roller in a very thin layer, while the upper roller deposits the desired amount of composition impregnated therein onto the paper; this dosage is obtained by adjusting the speeds of the two rollers, which rotate in opposite directions relative to each other.

[0205] Curing of the silicone composition X can be continuously performed by passing the substrate coated with the composition through a radiation device designed to ensure that the coated substrate remains in the radiation environment for a sufficient time to allow the coating to cure. Preferably, curing is performed at the lowest possible oxygen concentration, typically less than 100 ppm, and preferably less than 50 ppm. Curing is typically performed in an inert atmosphere such as nitrogen or argon. The exposure time required to cure the silicone composition X varies depending on the following factors:

[0206] -The specific formulation, type of radiation, and wavelength used

[0207] - Dosage flow rate, energy flux

[0208] - The concentration of free radical photoinitiator, and

[0209] - Atmosphere and coating thickness.

[0210] These parameters are well known to those skilled in the art, who will know how to adjust them.

[0211] The amount of composition X deposited on the substrate is variable, most commonly ranging from 0.1 g / m² of treated surface to 5 g / m² of treated surface. These amounts depend on the properties of the substrate and the desired release characteristics. For non-porous substrates, they are typically 0.5 g / m² to 1.5 g / m².

[0212] This method is particularly suitable for preparing silicone release coatings on substrates that are flexible substrates made of textiles, paper, polyvinyl chloride, polyester, polypropylene, polyamide, polyethylene, polyethylene terephthalate, polyurethane, or nonwoven glass fiber.

[0213] Flexible substrates coated with a silicone release coating can be, for example:

[0214] - Polymer films made of paper or polyolefins (polyvinyl chloride (PVC), polypropylene, or polyethylene) or polyesters (polyethylene terephthalate or PET),

[0215] - Tape with a pressure-sensitive adhesive layer on its inner surface and a silicone release coating on its outer surface;

[0216] - Or a polymer film used to protect the adhesive surfaces of self-adhesive or pressure-sensitive adhesive elements.

[0217] These coatings are particularly suitable for use in the field of mold release coatings.

[0218] The present invention also relates to a coating substrate that can be obtained according to the above method. As described above, the substrate can be a flexible substrate made of textiles, paper, polyvinyl chloride, polyester, polypropylene, polyamide, polyethylene, polyethylene terephthalate, polyurethane, or nonwoven glass fiber.

[0219] The coated substrate has non-stick and waterproof properties, or can improve surface properties such as smoothness, stain resistance, or softness.

[0220] Another object of the present invention relates to the use of substrates at least partially coated with a release coating according to the present invention and as defined above in self-adhesive labels, strips (including envelopes), graphic arts, healthcare and wellness applications.

[0221] This invention also relates to the use of the composition X according to the invention for preparing silicone elastomer articles by an additive manufacturing process. Additive manufacturing is also known as 3D printing. This description typically includes the name ASTM F2792-12a, "Standard Terminology for Additive Manufacturing Technologies." According to this ASTM standard, a "3D printer" is defined as "a machine used for 3D printing," and "3D printing" is defined as "the deposition of material using a printhead, nozzle, or other printer technology to create an object."

[0222] Additive manufacturing (AM) is defined as the process of joining materials together to create objects from 3D model data, typically layer by layer, which differs from subtractive manufacturing. Synonyms related to and encompassed in 3D printing include additive manufacturing, additive processes, additive technology, and layered manufacturing. Additive manufacturing (AM) can also be referred to as rapid prototyping (RP). As used herein, "3D printing" can be used interchangeably with "additive manufacturing," and vice versa.

[0223] As printing proceeds, irradiating the layers of silicone composition X causes at least a portion of the composition to rapidly gel during the production process, and thus each layer retains its shape and the printed structure does not collapse.

[0224] Advantageously, the silicone composition X according to the invention can be used in 3D printing processes that utilize photopolymerization technology (digital light processing, stereolithography), material extrusion, material deposition, or inkjet printing, adapting the viscosity of the silicone composition X to the technology employed.

[0225] Compound of formula (I)

[0226] The present invention also relates to a compound of formula (I).

[0227]

[0228] in

[0229] -R1 and R2 are independently selected from C1-C6 alkyl and C3-C7 cycloalkyl;

[0230] Alternatively, R1 and R2 together with the carbon atoms they are attached to form C3-C7 cycloalkyl groups;

[0231] -R3 is H or a C1-C6 alkyl group, preferably R3 is H;

[0232] -R4 is Group;

[0233] - Each R5 group independently represents a C1-C6 alkyl group;

[0234] -n = 0, 1, 2, 3 or 4, preferably n = 0, 1 or 2;

[0235] -R9 is a C1-C6 alkylene or a C1-C6 heteroalkylene; and

[0236] -R 10 It is a straight chain or a branched C1-C 18 Alkyl groups, preferably straight-chain or branched C2-C 17 Or C2-C 18 Alkyl groups, more preferably straight-chain or branched C4-C 13 Alkyl groups, and even more preferably straight-chain or branched C9 alkyl groups.

[0237] According to one embodiment, the compound of formula (I) is the compound of formula (II).

[0238]

[0239] According to one embodiment, the compound of formula (I) is the compound of formula (III).

[0240]

[0241] Advantageously, R1 and R2 are independently selected from C1-C6 alkyl groups. Preferably, R1 and R2 are each methyl.

[0242] Advantageously, R3 is H.

[0243] According to one embodiment, n = 0. According to another embodiment, n = 1 or 2, and each R5 group independently represents a C1-C6 alkyl group, preferably methyl.

[0244] According to one embodiment, R9 is a C1-C6 heteroalkylene group, particularly an -O-(CH2)2- group, wherein an oxygen atom is attached to a phenyl group.

[0245] R 10 It is a straight chain or a branched C1-C 18 Alkyl groups, preferably straight-chain or branched C2-C 17 Or C2-C 18 Alkyl groups, more preferably straight-chain or branched C4-C 13 Or C3-C 10 Alkyl groups, or even more preferably straight-chain or branched C9 alkyl groups.

[0246] According to one implementation, R 10 It is a straight chain or a branched C1-C 18 Alkyl groups, preferably straight-chain or branched C1-C 13 Alkyl groups, more preferably straight-chain or branched C1-C 10 Alkyl groups, or even more preferably straight-chain or branched C1-C9 alkyl groups.

[0247] According to one implementation, R 10 It is a straight chain or a C2-C with branches. 18 Alkyl groups, preferably straight-chain or branched C2-C 13 Alkyl groups, more preferably straight-chain or branched C2-C 10 Alkyl groups, or even more preferably straight-chain or branched C2-C9 alkyl groups.

[0248] According to one implementation, R 10 It is a branched C1-C 18 Alkyl groups, preferably branched C2-C 17 Or C3-C 18 Alkyl groups, more preferably branched C4-C 13 Alkyl groups, or even more preferably branched C9 alkyl groups.

[0249] R 10 Examples of the groups include branched C4 alkyl, branched C6 alkyl, branched C8 alkyl, branched C9 alkyl, and branched C... 11 Alkyl groups and branched C 13 alkyl.

[0250] When R 10 When it is a branched alkyl group, it may include a quaternary carbon. Preferably, the quaternary carbon is located at the α-position of the carbonyl group: the term trialkyl acetate is used. Trialkyl acetate can be derived from cutting oil. According to one embodiment, R 10 The -(CO)-O- group represents a trialkyl acetate, and preferably, R 10 Represents C4, C6, C8, C9, C with branches 11 Or C 13 alkyl.

[0251] In some cases, when R 10 When the -(CO)-O- group represents a trialkyl acetate derived from cutting oil, several structural isomers may exist. In particular, when R... 10 It is a branched C6, C8, C9, C 11 Or C 13 This may be the case with alkyl groups. Therefore, R 10 It can represent a mixture of structural isomers. For example, when R 10 When referring to a branched C9 alkyl group, the alkyl group may contain different isomers of the following types: –C(CH3)2-CH(CH3)-CH2-CH(CH3)2, -C(CH3)(CH(CH3)2)-CH2-CH(CH3)2, -C(CH3)2-(CH2)5-CH3 and –C(CH2-CH3)2-(CH2)3-CH3.

[0252] The compounds of formula (I) can be synthesized according to standard methods used in organic chemistry known to those skilled in the art.

[0253] In particular, compounds of formula (III) can be synthesized from compounds of formula (XI) or from compounds of formula (XII) using conventional methods known to those skilled in the art in organic chemistry.

[0254]

[0255] Many pathways are possible, for example:

[0256] - The corresponding acid R is directly esterified by the compound of formula (XI) in the presence of a strong acid and a solvent capable of distilling the azeotrope formed with the water. 10 -COOH,

[0257] - Corresponding acid R 10 The methyl or ethyl esters of -COO- are transesterified via compounds of formula (XI) catalyzed, for example, by β-diketones of Group IV metals, particularly zirconium tetraacetylacetone.

[0258] - Compound (XI) and the corresponding acid R 10 The reaction of COCl chloride in the presence of triethylamine

[0259] - Compounds of formula (XII) are prepared from 2-phenoxyethanol, for example by esterification or transesterification, followed by a Friedel-Crafts reaction with isobutyryl chloride, chlorination or bromination of the resulting ketone, and finally alkaline hydrolysis to form compounds of formula (I).

[0260] Uses of compounds of formula (I)

[0261] The present invention also relates to the use of compounds of formula (I) as described above as free radical photoinitiators, particularly as free radical photoinitiators for silicone acrylate compositions.

[0262] In fact, the compounds of formula (I) according to the invention are soluble in silicone; therefore, they can be used as free radical photoinitiators in these compositions without the addition of solvents.

[0263] According to another embodiment, a small amount of solvent can also be used to help dissolve the compound of formula (I) in the silicone composition.

[0264] The present invention also relates to the use of compounds of formula (I) as described above as free radical photoinitiators in a radiation-curable composition Y comprising at least one radiation-curable unsaturated compound D.

[0265] The present invention also relates to a radiation-curable composition Y, comprising:

[0266] -At least one radiation-curable unsaturated compound D,

[0267] - Photoinitiator, which is a compound of formula (I) as described above.

[0268] Radiation-curable unsaturated compound D may contain one or more double bonds that are not part of an aromatic ring.

[0269] According to one embodiment, the radiation-curable unsaturated compound D is a hydrocarbon compound comprising one or more double bonds and optionally one or more heteroatoms selected from N, P, O, S, and F. Unsaturated compound D may, for example, be selected from (meth)acrylic acid, (meth)acrylates, (meth)acrylamides, N-substituted (meth)acrylamides, unsaturated acid anhydrides, styrene compounds, alkylstyrene, divinylbenzene, vinyl ethers, vinyl esters and allyl esters, isocyanurates, N-vinyl heterocycles, and mixtures thereof.

[0270] Unsaturated compound D can be a monomer or an oligomer. When unsaturated compound D is a monomer, it can contain 2 to 40 carbon atoms and optionally 1 to 20 heteroatoms selected from N, P, O, S, and F. Examples of unsaturated oligomers D include polymers containing double bonds in the main chain or side chains. Among these polymers, unsaturated polyesters, unsaturated polyamides, and unsaturated polyurethanes may be mentioned.

[0271] According to another embodiment, the radiation-curable unsaturated compound D is an organopolysiloxane containing one or more double bonds. Preferably, the radiation-curable unsaturated compound D is an organopolysiloxane containing at least one (meth)acrylate group. Unsaturated compound D may be organopolysiloxane A as described above.

[0272] The present invention also relates to the use of a compound of formula (I) as described above as a free radical photoinitiator in a radiation-curable composition Y, the radiation-curable composition Y comprising at least one radiation-curable unsaturated compound D, said unsaturated compound D being an organopolysiloxane containing one or more double bonds, preferably an organopolysiloxane containing at least one (meth)acrylate group.

[0273] The radiation-curable composition Y can be used in a variety of technical fields, such as printing inks, printing technology, varnishes, wood coatings, plastic coatings, metal coatings, adhesives, and 3D printing.

[0274] Example

[0275] In the following examples, various organopolysiloxanes A and type I free radical photoinitiator B were used to prepare radiation-curable silicone compositions X according to the present invention. Their structures are shown in the table below. Unless otherwise stated, all percentages in this document are expressed in weight %.

[0276] Organopolysiloxane A

[0277] [Table 1]

[0278]

[0279]

[0280] Type I free radical photoinitiator B is as follows:

[0281] B1:

[0282]

[0283] Commercially available compound, CAS No.: 106797-53-9, Commercial Reference No.: I2959.

[0284] B2:

[0285]

[0286] According to the compound of the present invention, wherein CO-C9H 19 This indicates a group derived from neodecanoic acid.

[0287] B3:

[0288]

[0289] This compound was prepared by esterifying compound B1 with acetic acid in the presence of a dehydrating agent. Compound B3 was in the form of a recrystallized solid.

[0290] Example 1 Synthesis of photoinitiator B2 and solubility study of compounds B2 and B3 in silicone compositions

[0291] In a single-necked flask, 1 equivalent of B1, 1 equivalent of neodecanoic acid, and 1 mL of concentrated sulfuric acid were added per mmol of product. The mixture was stirred at room temperature under argon for 2 hours. Then, the reaction was carried out at 120°C under argon for 12 hours.

[0292] Once the reaction was complete, 10 times the volume of the reaction medium was added to water, and the mixture was extracted three times with n-hexane. The organic phases were then combined, neutralized with sodium carbonate, dried, and evaporated. The crude product was then purified on silica gel using a 90 / 10 cyclohexane / ethyl acetate eluent to give product B2.

[0293] Compound B2 was characterized by infrared spectroscopy and nuclear magnetic resonance (NMR). The results are shown in Table 2 below.

[0294] [Table 2]

[0295]

[0296] The solubility of compounds B2 and B3 in the silicone composition was also tested. The results are shown in Table 3 below.

[0297] [Table 3]

[0298]

[0299] These results indicate that the photoinitiator according to the invention is soluble in silicone compositions.

[0300] Example 2 Monitoring the polymerization of acrylic functional groups in silicone acrylate under a UV mercury lamp

[0301] The preparation process is as follows: The photoinitiator was weighed and added to organopolysiloxane A1, and the mixture was stirred until a homogeneous product was obtained (approximately 30 minutes). This mixture was prepared based on 2 g of organopolysiloxane A1. Data are expressed as % by weight. The composition is shown in Table 3 below.

[0302] The resulting formulation was then cured under UV radiation at 365 nm using a mercury-xenon lamp with a reflector. The UV lamp power was set to 510 mW·cm⁻¹. -2 .

[0303] Operate under air or lamination conditions to avoid any inhibition of the active substance by oxygen. When operating under lamination conditions, the formulation is placed between two polypropylene sheets, and then between two CaF2 disks.

[0304] Polymerization kinetics were monitored using a real-time Fourier transform infrared spectrometer (RT-FTIR, from a Brucker Optik Vertex 70). This spectroscopic technique simultaneously exposes the sample to light and infrared radiation to track polymerization at 1636 cm⁻¹. -1 The changes in the infrared spectrum are characteristic of the C=C bonds of the acrylic functional groups.

[0305] The conversion rate from C=C to CC during polymerization is related to 1636 cm⁻¹. -1 The reduction in the area under the peak is directly related to the conversion rate, which can be calculated using the following formula: Conversion rate (%) = (A0 - At) / A0 × 100, where A0 is the area under the peak before irradiation and At is the area under the peak at each time t during irradiation.

[0306] The time graph can display not only the final conversion rate, but also other important parameters, such as the maximum conversion rate ((Rp / [M]0)×100). The maximum conversion rate is determined by the slope of the conversion rate (%) = f(t) curve at its inflection point.

[0307] The results are shown in Table 4 below.

[0308] [Table 4]

[0309]

[0310] These results demonstrate that the type I photoinitiator according to the present invention is more efficient than commercially available photoinitiators in terms of conversion rate and reaction kinetics.

[0311] Example 3 The effectiveness of type I photoinitiators was evaluated by monitoring the polymerization of acrylic functional groups in silicone in thin-film applications for non-stick applications.

[0312] In the following examples, the silicone composition according to the invention was applied to a flexible substrate and then cured by exposure to radiation. The release properties of the resulting substrate were evaluated. For this purpose, the formulation was prepared as follows: 100 parts by weight of a mixture comprising 70 parts by weight of organopolysiloxane A2 and 30 parts by weight of organopolysiloxane A3 were prepared. Then, 6.6 mmol of photoinitiator B1, B2, or B3 (corresponding to about 1.5 parts by weight of photoinitiator B1, 2.5 parts by weight of photoinitiator B2, and 1.8 parts by weight of photoinitiator B3, respectively) was added to the mixture. After the photoinitiator was completely dissolved, the composition was applied to various substrates using a Mayer rod under the conditions described in the various examples.

[0313] Tests conducted on substrates coated with a silicone release coating

[0314] Deposits: The silicon deposits coated on the surface were verified by X-ray fluorescence analysis of silicon (from Oxford's Lab-X 3000). The X-ray tube excites the electron shells of silicon atoms, resulting in the emission of X-rays, which is proportional to the amount of silicon excited. This value, or count, is converted into the amount of silicone by calculation (using a standard curve).

[0315] Smearing: Qualitative verification of surface polymerization is performed using the finger smearing method, which consists of the following steps:

[0316] - Place the silicone-coated substrate sample to be inspected on a flat and rigid surface;

[0317] - Draw a line with your fingertip while applying moderate but noticeable pressure; and

[0318] - Examine the formed lines with your eyes, preferably under oblique light. This allows you to see the fingerprints, even very faint ones, by observing differences in surface gloss.

[0319] The assessment is qualitative. "Smearing" is quantified using the following symbols:

[0320] A: Great, no lines were left on your fingers.

[0321] B: Slightly worse, the lines are almost invisible.

[0322] C: Clear lines

[0323] D: The lines are very clear, the surface is smooth, and the product shows almost no aggregation.

[0324] That is, the grades from A to D, from best result to worst result.

[0325] Rub-off: This test verifies the ability of silicone to adhere to a flexible substrate by rubbing it back and forth with your fingers. The verification process consists of the following steps:

[0326] Place the silicone-coated substrate sample to be inspected on a flat and rigid surface, with the silicone on top.

[0327] Rub your fingertips back and forth 10 times (about 10cm in length) while pressing gently but clearly.

[0328] Visually inspect the appearance of the rubbed area. Wipe away any fine white powder or small balls that appear when rolled under your fingers.

[0329] The assessment is qualitative. Erasure is quantified using the following symbols:

[0330] 10: Very good, wipe off after rubbing back and forth 10 times.

[0331] 1: Very poor quality, wiped off after the first rub.

[0332] This score corresponds to the number of back-and-forth rubbing steps (from 1 to 10) that result in erasure.

[0333] That is, from 1 to 10 points, from the worst result to the best result.

[0334] Dehumidification: The degree of polymerization of the silicone layer was assessed by evaluating the transfer of silicone to the adhesive in contact with the coating using a standardized surface tension test ink. The method is as follows:

[0335] Select a silicone-coated paper sample of approximately 20 x 5 cm, cut along its unfolding direction (machine direction), to be characterized.

[0336] Cut a piece of tape about 15cm long, then place it stick-side down on the paper to be inspected, ensuring there are no creases. Apply pressure 10 times by sliding your finger along the length of the tape. (3M "Scotch" tape, reference number 610, width: 25mm);

[0337] Tear off the tape and lay it flat with the adhesive side facing up;

[0338] Using a (disposable) cotton swab, apply an ink line approximately 10cm long (SHERMAN, FERARINI, or BENELI brand ink, with a surface tension of approximately 30 dyn / cm and a viscosity of 2mPa / s to 4mPa / s) to the adhesive portion of the tape. Immediately start the timer;

[0339] When the ink line changes its appearance, it is considered to have entered the dehumidification stage: then the timer is stopped.

[0340] The ink must be applied to the adhesive portion of the tape within 2 minutes of applying the silicone.

[0341] If the result is less than 10 seconds, it is considered that the silicone has migrated to the adhesive and the polymerization is incomplete;

[0342] A score from 0 to 10 will be given, corresponding to the time elapsed (in seconds) before the dehumidification phenomenon was observed;

[0343] If the result is 10 seconds, the aggregation is considered complete. In this case, a score of 10 is given, indicating a very good result.

[0344] Record the score obtained and the ink used (name, brand, surface tension, viscosity).

[0345] Extractable: Measures the amount of silicone that was not grafted onto the formed network during polymerization. These silicones are extracted from the membrane by immersing the sample in MIBK (methyl isobutyl ketone) for at least 24 hours immediately after leaving the machine. This is measured by flame atomic absorption spectrometry.

[0346] Preparation of self-adhesive multilayer articles

[0347] A TESA 7475 standard adhesive substrate (substrate = PET - adhesive = acrylic) was laminated onto a silicone liner prepared above (a substrate coated with a silicone coating obtained by UV curing) to form a multilayer article. Tensile tests were performed to determine the release force before and after aging, as well as the subsequent adhesive and ring tack values. These tests are described below.

[0348] Tests on the resulting multi-layered items

[0349] Subsequent Adhesion (or “SubAd”): The residual tack of the adhesive (TESA 7475) in contact with the silicone coating was measured according to the FINAT 11 (FTM 11) test known to those skilled in the art. The reference specimen here is PET, and the adhesive was kept in contact with the silicone surface to be tested for 1 day at 70°C.

[0350] Results are expressed as a percentage of residual adhesive force of the reference tape:

[0351] CA = (Fm2 / Fm1) x 100 (in percentage terms),

[0352] in:

[0353] Fm2 = the average release force of the tape after 20 hours of contact with a silicone substrate; and

[0354] Fm1 = Average release force of the tape that does not come into contact with the silicone substrate.

[0355] The desired adhesion is higher than 90%.

[0356] Release force: Peel force was measured using TESA 7475 standard adhesive. Specimens of multilayer articles (adhesive in contact with the silicone surface) were held at 23°C for 1 day and at 70°C for 1 day under the pressure conditions required for the FINAT 10 test, and then tested at a low peel rate according to the FINAT 3 test (FTM 3) known to those skilled in the art.

[0357] Release force is expressed in cN / inch and is measured using a force gauge after the sample has been pressurized at room temperature (23°C) or at a higher temperature (typically 70°C) for accelerated aging testing.

[0358] The tested formulations and test results are shown in Table 5 below.

[0359] [Table 5]

[0360]

[0361] The results of application, wiping, and dehumidification of the type I photoinitiator according to the present invention indicate good polymerization of the acrylic silicone formulation. This good polymerization is also reflected in the low levels of extractability. The resulting film exhibits the expected non-stick properties. In particular, subsequent adhesion is better than in the comparative examples.

[0362] Therefore, the type I photoinitiator according to the present invention can be used to produce a release system.

Claims

1. A radiation-curable silicone composition X, said composition X comprising: a. At least one organopolysiloxane A containing at least one (meth)acrylate group; b. At least one free radical photoinitiator B, which is a compound of formula (I). （I） in - R1 and R2 are independently selected from C1-C6 alkyl and C3-C7 cycloalkyl; Alternatively, R1 and R2 together with the carbon atoms they are attached to form C3-C7 cycloalkyl groups; - R3 is H or a C1-C6 alkyl group; - R4 is Group; - Each R5 group independently represents a C1-C6 alkyl group; - n = 0, 1, 2, 3 or 4; - R9 is a C1-C6 alkylene or a C1-C6 heteroalkylene; and - R 10 It is a straight chain or a branched C1-C 18 alkyl.

2. The silicone composition X according to claim 1, wherein the compound of formula (I) is a compound of formula (II). (II) R1, R2, R3 and R4 are as defined in claim 1.

3. The silicone composition X according to claim 1, wherein the compound of formula (I) is a compound of formula (III). (III) Where R 10 As defined in claim 1.

4. The silicone composition X according to claim 3, wherein R 10 It is a straight chain or a C4-C with branches. 13 alkyl.

5. The silicone composition X according to claim 3, wherein R 10 It is a straight-chain or branched C9 alkyl group.

6. The silicone composition X according to any one of claims 1-5, wherein the organopolysiloxane A comprises: a) At least one unit of the following formula (IV): R a Z b SiO (4-a-b) / 2 (IV) in - The same or different R symbols each represent a straight chain or a branched chain from C1 to C2. 18 Alkyl, C6 to C 12 Aryl or aralkyl groups, which can be substituted. - The Z symbol is a monovalent free radical of the formula -y-(Y')n, where: - y represents the polyvalent C1-C 18 The alkylene or heteroalkylene groups can be straight-chain or branched, and can be interrupted by one or more cycloalkylene groups, and can be extended by C1 to C4 divalent oxyalkylene or polyoxyalkylene radicals, wherein the alkylene, heteroalkylene, oxyalkylene, and polyoxyalkylene groups can be substituted with one or more hydroxyl groups. - Y' represents a monovalent alkenyl carbonyl group, and - n equals 1, 2, or 3, and - a is an integer equal to 0, 1 or 2, b is an integer equal to 1 or 2, and the sum of a and b is 1, 2 or 3; and b) Optionally, a unit having the following formula (V): R a SiO (4-a) / 2 (V) in: - The R symbol is defined as in equation (IV) above, and - a is an integer equal to 0, 1, 2 or 3.

7. Use of the silicone composition X according to any one of claims 1-6 for preparing a silicone elastomer capable of being used as a release coating on a substrate.

8. A silicone elastomer, said silicone elastomer being obtained by curing a silicone composition X according to any one of claims 1 to 6.

9. A method for preparing a coating on a substrate, the method comprising the following steps: - Apply the silicone composition X according to any one of claims 1 to 6, and - The composition is cured by electron or photon radiation.

10. A substrate capable of being coated by the method according to claim 9.

11. Use of composition X according to any one of claims 1 to 6 for preparing silicone elastomer articles by an additive manufacturing process.

12. A compound of formula (I) （I） in - R1 and R2 are independently selected from C1-C6 alkyl and C3-C7 cycloalkyl; Alternatively, R1 and R2 together with the carbon atoms they are attached to form C3-C7 cycloalkyl groups; - R3 is H or a C1-C6 alkyl group; - R4 is Group; - Each R5 group independently represents a C1-C6 alkyl group; - n = 0, 1, 2, 3 or 4; - R9 is a C1-C6 alkylene or a C1-C6 heteroalkylene; and - R 10 It is a straight chain or a C2-C with branches. 17 alkyl.

13. The compound according to claim 12, characterized in that, It is a compound of formula (II). (II) R1, R2, R3 and R4 are as defined in claim 12.

14. The compound according to claim 12 or 13, characterized in that, It is a compound of formula (III). (III) Where R 10 As defined in claim 12.

15. The compound according to claim 14, wherein R 10 It is a straight chain or a C4-C with branches. 13 alkyl.

16. The compound according to claim 14, wherein R 10 It is a straight-chain or branched C9 alkyl group.

17. Use of the compound according to any one of claims 12 to 16 as a free radical photoinitiator.

18. The use according to claim 17, wherein the compound serves as a free radical photoinitiator in a radiation-curable composition Y, the radiation-curable composition Y comprising at least one radiation-curable unsaturated compound D.

19. The use according to claim 18, wherein the radiation-curable unsaturated compound D is a hydrocarbon compound comprising one or more double bonds and optionally one or more heteroatoms selected from N, P, O, S and F.

20. The use according to claim 18, wherein the radiation-curable unsaturated compound D is an organopolysiloxane containing one or more double bonds.

21. Compounds of formula (I) (I) Use as a free radical photoinitiator in a radiation-curable composition Y comprising at least one radiation-curable unsaturated compound D, in - R1 and R2 are independently selected from C1-C6 alkyl and C3-C7 cycloalkyl; Alternatively, R1 and R2 together with the carbon atoms they are attached to form C3-C7 cycloalkyl groups; - R3 is H or a C1-C6 alkyl group; - R4 is Group; - Each R5 group independently represents a C1-C6 alkyl group; - n = 0, 1, 2, 3 or 4; - R9 is a C1-C6 alkylene or a C1-C6 heteroalkylene; and - R 10 It is a straight chain or a branched C1-C 18 alkyl, The unsaturated compound D is an organopolysiloxane containing one or more double bonds.

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