Release Coating Composition

Abstract

The release coating composition includes an organosilicon compound having at least one terminal aliphatic unsaturated group and an organosilicon composition. The organosilicon compound exhibits a viscosity of 150 cPs or less. The organosilicon composition exhibits a viscosity at least 100 times greater than the viscosity of the organosilicon compound. The release coating composition also includes an organosilicon crosslinker having at least one silicon-bonded hydrogen atom and a catalyst that promotes the addition of the at least one silicon-bonded hydrogen atom to the at least one aliphatic unsaturated group. One or more inhibitors are also included to delay the addition of the at least one silicon-bonded hydrogen atom to the at least one aliphatic unsaturated group when the composition is at room temperature. Before curing, the release coating composition exhibits a viscosity of 150 to 800 cPs at 25°C, and the release coating composition cures at temperatures of 80°C or less.

Description

[Technical Field]

[0001] The present invention relates to release coating compositions and uses thereof. [Background technology]

[0002] Heat-responsive recording materials are known and are often used for labels requiring test, bar code images, graphics, and similar image information. To be usable, such labels require high print contrast and sharp, unbroken images. Heat-responsive recording materials often include a thermal imaging coating that requires a color-forming composition to be used to form the image. Such color-forming compositions are generally activated at temperatures above 80°C. Such labels can be created at the time of use and application by a printer device having a printer head heat source to activate the color-forming composition and form the image.

[0003] As a means of reducing costs and waste, interest in linerless labels, which do not require a liner, is increasing. Such labels are typically formed from a roll of label tape and have a release coating. The release coating prevents adhesion of the adhesive used to attach the label to an object after the label is formed, allowing the label tape to rewind on itself and facilitating rewinding of the roll. However, current linerless label tapes suffer from defects caused by excessive printhead debris, which leads to scuffs, dust, and other image defects on the label surface. A common cause of printhead debris is a defective release coating, including UV-cured systems. Furthermore, current release coating materials have short pot lives, are difficult to apply, cure slowly or incompletely at temperatures below 80°C, and do not exhibit good thermal stability after curing.

[0004] It would therefore be desirable to provide a release coating composition that overcomes the aforementioned drawbacks and is available to meet performance criteria for use in linerless label applications. Summary of the Invention [Means for solving the problem]

[0005] A release coating composition embodiment is provided. In an embodiment, the release coating composition comprises an organosilicon compound having at least one terminal aliphatic unsaturated group and an organosilicon composition. The organosilicon compound exhibits a viscosity of 150 cPs or less. The organosilicon composition exhibits a viscosity at least 100 times greater than the viscosity of the organosilicon compound. The release coating composition also comprises an organosilicon crosslinker having at least one Si-bonded hydrogen atom and a catalyst that promotes the addition of the at least one Si-bonded hydrogen atom to the at least one aliphatic unsaturated group. One or more inhibitors are also included to delay the addition of the at least one Si-bonded hydrogen atom to the at least one aliphatic unsaturated group when the composition is at room temperature. Before curing, the release coating composition exhibits a viscosity of 150 to 800 cPs at 25°C, and the release coating composition cures at temperatures of 80°C or less.

[0006] In embodiments, the release coating composition comprises 50 wt% or more of an organosilicon compound, based on the total weight of the release coating composition, and the organosilicon compound exhibits a viscosity of 25 to 150 CPs at 25°C.

[0007] In another embodiment, the release coating composition comprises up to 30 wt% of the organosilicon composition, based on the total weight of the release coating composition. Preferably, the release coating composition comprises 5-20 wt% of the organosilicon composition, based on the total weight of the release coating composition.

[0008] In certain embodiments, the organosilicon composition has a viscosity of 5,000 to 15,000 cPs at 25° C. Preferably, the organosilicon composition has a viscosity of 8,000 to 11,000 cPs at 25° C.

[0009] In another embodiment, the organosilicon composition comprises a mixture of a first siloxane and a second siloxane. In one such embodiment, the first siloxane is an organopolysiloxane having a viscosity of 1000 cPs or less and containing at least one terminal fatty acid unsaturated group. In another embodiment, the second siloxane is an organopolysiloxane having a viscosity of 400,000 cPs or more and containing an average of less than one functional group per molecule.

[0010] In embodiments, the release coating composition comprises no more than 150 ppm of catalyst based on the total weight of the release coating composition.

[0011] In another embodiment, the release coating composition comprises one or more inhibitors at 1 wt % or less, based on the total weight of the release coating composition.

[0012] Preferably, the release coating composition is cured until the extractables are 5 wt% or less, based on the total weight of the release coating composition.

[0013] Additionally, in some embodiments, the catalyst is a platinum complex containing at least one unsaturated group.

[0014] In some embodiments, a method for producing a coated article is provided. In one embodiment, the method includes providing a substrate and applying a release coating composition onto at least a portion of the substrate. The release coating composition is cured at 80° C. or less.

[0015] In this embodiment, the release coating composition can be cured in 20 seconds or less.

[0016] These and other advantages of the present invention will become readily apparent to those skilled in the art from the following detailed description when considered in light of the accompanying drawings. [Brief explanation of the drawings]

[0017] [Figure 1] FIG. 1 is a graph of the set rate as measured by extract over time for embodiments of the present invention and comparative examples. DETAILED DESCRIPTION OF THE INVENTION

[0018] It is to be understood that the present invention may assume various alternative directions and sequences of steps, unless expressly specified to the contrary. It is also to be understood that the specific materials, compositions, articles, and methods described in the following specification are merely exemplary embodiments of the inventive concepts. Accordingly, specific characteristics, conditions, or other physical characteristics associated with the disclosed embodiments are not to be considered limiting, unless expressly stated otherwise.

[0019] Furthermore, as used herein, the terms "comprises," "comprising," "includes," "has," "having," or other variations thereof, are intended to cover non-exclusive inclusions. For example, a method, article, or composition that includes a list of features is not necessarily limited to only those features and may include other features not expressly listed or inherent to such method, article, or composition. Furthermore, unless expressly stated to the contrary, "or" means an inclusive or, not an exclusive or. For example, condition A or condition B is satisfied by any of the following: A is true (or present) and B is false (or absent), A is false (or absent) and B is true (or present), and both A and B are true (or present).

[0020] Additionally, the use of "a" or "an" is employed to describe elements and components described herein. This is merely for convenience and to provide a general understanding of the scope of the present invention. This specification should be read to include one or at least one, and the singular also includes the plural, and vice versa, unless otherwise clearly indicated. For example, where a single item is described herein, plural items can be used in place of the single item. Similarly, where multiple items are described herein, the single item can be replaced with the plural items.

[0021] In certain embodiments, a release coating composition is provided. The release coating composition is suitable for use in label production. For example, the release coating composition can be used to provide a non-sticky surface that forms part of the label. Such labels can be used in so-called variable information printing applications, where printing is performed using thermal energy. Thermal energy printing activates encapsulated ink within a paper substrate. Currently, labels printed using thermal energy are laminated to a silicone-treated paper or film liner, which functions only as a carrier and is discarded after the label is dispensed. Advantageously, the release coating composition allows heat-activatable label paper to be silicone-treated, eliminating the need for a film liner and reducing costs and waste. This is not possible with current heat-curing silicone systems because the activation temperature of the curing mechanism exceeds the activation temperature of the ink capsules in the paper, causing the label to turn black during application and curing of such silicone systems. However, the release coating composition is not limited to heat-activatable label paper applications and can be used in other applications where providing a non-sticky surface is desired. For example, the release coating composition can be used to produce release paper, backing paper, and interleaved paper, including interleaved paper and release paper.In addition, the release coating composition is also suitable for producing release, backing, and sandwich cards, films, and fabrics, treating the backside of self-adhesive tapes or films, or producing the die-cut surface of self-adhesive labels.The release coating composition is also suitable for treating packaging materials, such as cardboard, plastic, wood, or iron, such as paper, cardboard boxes, metal foil, and drums, intended for storing and / or transporting adhesive-like products, such as sticky foods, such as cakes, honey, candy, and meat, bitumen, asphalt, greased materials, and crude rubber.Another use example of the release coating composition is die-treating a substrate for transfer of a contact adhesive layer in a so-called transfer process.

[0022] The release coating composition comprises an organosilicon compound having at least one terminal aliphatic unsaturated group. Preferably, the aliphatic unsaturated group is a SiC-bonded group having an aliphatic carbon-carbon multiple bond.

[0023] The organosilicon compound can be linear or branched. In some embodiments, the organosilicon compound has the formula [ka] [wherein R is a monovalent hydrocarbon group having no aliphatic carbon-carbon multiple bonds and having 1 to 18 carbon atoms per group; R 1 is a monovalent hydrocarbon group having at least one terminal aliphatic carbon-carbon multiple bond and having 2 to 12 carbon atoms per group; x is 0, 1, 2, or 3; y is 0, 1, or 2, and The sum of x+y is 0, 1, 2, or 3, provided that, on average, there is at least one R 1 groups are present, preferably at least two R per molecule 1 groups are present.] It is preferred to use organosilicon compounds which are linear or branched organopolysiloxanes containing units of the formula:

[0024] In certain embodiments, the compound of formula [ka] [where: R and R 1 has the meaning given above, g is 0, 1, or 2; n is 0 or an integer from 1 to 1500, and m is 0 or an integer from 1 to 200, provided that there is at least one R 1 groups are present, preferably at least two R per molecule 1 groups are present.] It is preferable to use an organosilicon compound which is a linear organopolysiloxane of the formula:

[0025] In formula (II), n units -(SiRO)- and m units -(SiRR 1 O)— can be distributed in the organopolysiloxane molecule in any desired manner.

[0026] In other embodiments, it is preferred to use branched organosilicon compounds, such as branched siloxane copolymers comprising hydrocarbon blocks and siloxane blocks.Examples of such branched siloxane copolymers are described in U.S. Patent No. 7,888,446, column 1, line 40 to column 4, line 24, the disclosure of which is incorporated herein by reference in its entirety.

[0027] In yet another embodiment, a compound of the general formula: [ka] [where: Y is a divalent to dodecavalent organic group, preferably a divalent, trivalent, or tetravalent organic group, more preferably a divalent organic group, the organic group having 1 to 30 C atoms and optionally containing one or more O atoms; a is 0 or 1, and b is an integer from 1 to 11, preferably 1, 2, or 3, more preferably 1, and has at least one, preferably at least two, of the formula R 1 R2SiO 1 / 2 and optionally a siloxane unit of the formula R2SiO 2 / 2 and / or RSiO 1 / 2 siloxane units, where R and R 1 have the meanings given above.] It is preferable to use an organosilicon compound which is a branched siloxane copolymer containing at least one structural unit of the formula:

[0028] Examples of hydrocarbon groups R include alkyl groups such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, n-pentyl, isopentyl, neopentyl, and tert-pentyl; hexyl groups such as n-heptyl; octyl groups such as n-octyl; isooctyl groups such as 2,2,4-trimethylpentyl; nonyl groups such as n-nonyl; decyl groups such as n-decyl; and dodecyl groups such as n-dodecyl. cycloalkyl groups such as cyclopentyl, cyclohexyl, cycloheptyl, and methylcyclohexyl; aryl groups such as phenyl, naphthyl, anthryl, and phenanthryl; alkaryl groups such as o-tolyl, m-tolyl, p-tolyl, xylyl, and ethylphenyl; and aralkyl groups such as benzyl, α-phenylethyl, and β-phenylethyl.

[0029] R 1 Exemplary groups include alkenyl groups such as vinyl, 5-hexenyl, 2,4-divinylcyclohexylethyl, 3,4-divinylcyclohexylethyl, 2-propenyl, allyl, 3-butenyl, and 4-pentenyl, and alkynyl groups such as ethynyl, propargyl, and 2-propynyl. 1 R can be a vinyl group. 1 is a vinyl group, the designation "Vi" may be utilized herein.

[0030] In some embodiments, the release coating composition comprises 50 wt% or more of the organosilicon compound, based on the total weight of the release coating composition. In one such embodiment, the release coating composition comprises 50-90 wt% of the organosilicon compound, based on the total weight of the release coating composition. In other embodiments, the release coating composition comprises 60 wt% or more of the organosilicon compound, based on the total weight of the release coating composition. In one such embodiment, the release coating composition comprises 60-85 wt% of the organosilicon compound, based on the total weight of the release coating composition. In yet another embodiment, the release coating composition comprises 70-85 wt% of the organosilicon compound, based on the total weight of the release coating composition.

[0031] The organosilicon compound has a viscosity of 150 cPs or less at 25° C., preferably 25 to 150 cPs at 25° C., and more preferably 50 to 125 cPs at 25° C. The viscosity of the organosilicon compound can be determined by measurement using a rotational viscometer in accordance with DIN EN ISO 3219.

[0032] In some embodiments, the organosilicon compound can be provided as all or part of component (A). In certain embodiments, component (A) can comprise a mixture of organopolysiloxanes containing one or more embodiments of the organosilicon compound described above. Additional organopolysiloxanes may also be suitable for use in component (A).

[0033] The release coating composition also includes an organosilicon composition. The organosilicon composition is provided to enhance the compatibility of the release coating composition in heat-activatable label systems. More specifically, the organosilicon composition reduces friction between the cured release coating composition and the thermal printhead device, helping to reduce printhead debris during printing.

[0034] The organosilicon composition can be provided as part of component (A). The organosilicon composition exhibits a viscosity that is at least 100 times that of the organosilicon compound. In certain embodiments, the organosilicon composition has a viscosity of 5,000 to 15,000 cPs at 25°C. In other embodiments, the organosilicon composition has a viscosity of 8,000 to 11,000 cPs at 25°C. The viscosity of the organosilicon composition can be determined by measurement using a rotational viscometer in accordance with DIS EN ISO 3219.

[0035] Preferably, the organosilicon composition comprises a mixture of a first siloxane and a second siloxane.

[0036] In an embodiment, the first siloxane is an organopolysiloxane having a viscosity of 1000 cPs or less at 25° C. Preferably, the first siloxane is an organopolysiloxane having a viscosity of 25 to 500 cPs at 25° C. More preferably, the first siloxane is an organopolysiloxane having a viscosity of 50 to 300 cPs at 25° C. The viscosity of the first siloxane can be determined by measurement using a rotational viscometer in accordance with DIN EN ISO 3219.

[0037] The organosilicon composition may generally be non-functional. However, the first siloxane may be an organopolysiloxane having at least one terminal aliphatic unsaturated group. Preferably, the first siloxane has two terminal aliphatic unsaturated groups. In certain embodiments, each terminal aliphatic unsaturated group is a SiC-bonded group having an aliphatic carbon-carbon multiple bond, such as a vinyl bond. In some embodiments, the first siloxane is a vinyl-functional, substantially linear organopolysiloxane. Particularly preferred is a compound of the formula [ka] [where: j is an integer between 60 and 120; R and R 1 has the meaning given above.] It is an organopolysiloxane of the formula:

[0038] The second siloxane is an organopolysiloxane having a viscosity of 400,000 cPs or greater. Preferably, the second siloxane has a viscosity of 800,000 cPs or greater. In some embodiments, the second siloxane may have a viscosity of 1,000,000 cPs or greater. The viscosity of the second siloxane can be determined by measurement using a rotational viscometer in accordance with DIN EN ISO 3219.

[0039] The second siloxane can have a very high molecular weight. For example, the second siloxane can have a molecular weight of 650,000 mm 2 / s or more, preferably 850,000 mm 2 / s or more, and more preferably 1,000,000 mm 2 The second siloxane may have a molecular weight of 1 / s or more. The upper limit of the molecular weight of the second siloxane is limited by its effect on the viscosity of the release coating composition. It is preferable that the second siloxane have low extractables. Thus, in some embodiments, the second siloxane has an average of less than 1 functional group per molecule. In other embodiments, the second siloxane has an average of less than 0.5 functional groups per molecule. In still other embodiments, the second siloxane may have an average of zero functional groups per molecule.

[0040] Preferably, the second siloxane has the formula: [ka] [where: R has the meaning given above, but is preferably a methyl group, and n is selected to provide the desired molecular weight and viscosity. The second siloxane is, for example, RSiO 3 / 2 groups and SiO 4 / 2 It may be lightly crosslinked to contain up to 5 mole % of siloxy groups (where R is preferably a methyl group) based on the total moles of siloxy groups.

[0041] The organosilicon composition can comprise 20 wt% or more of the first siloxane, with the remainder consisting primarily of the second siloxane. In one embodiment, the organosilicon composition comprises 20-98 wt% of the first siloxane, with the remainder consisting primarily of the second siloxane. In another embodiment, the organosilicon composition comprises 50-90 wt% of the first siloxane, with the remainder consisting primarily of the second siloxane. In yet another embodiment, the organosilicon composition comprises 60-80 wt% of the first siloxane, with the remainder consisting primarily of the second siloxane. In these embodiments, the wt% is based on the total weight of the organosilicon composition.

[0042] Preferably, the release coating composition comprises 50 wt% or less of the organosilicon composition. In embodiments, the release coating composition comprises 5-50 wt% of the organosilicon composition. More preferably, the release coating composition comprises 30 wt% or less of the organosilicon composition. In one such embodiment, the release coating composition comprises 5-30 wt% of the organosilicon composition. In another embodiment, the release coating composition comprises 5-20 wt% of the organosilicon composition. In these embodiments, the wt% is based on the total weight of the release coating composition.

[0043] The release coating composition also includes an organosilicon crosslinker having at least one Si-bonded hydrogen atom, sometimes referred to herein by the designation "SiH." The organosilicon crosslinker has the formula [ka] [where: R has the meaning given above, e is 0, 1, 2, or 3; f is 0, 1, or 2, and The sum of e+f is 0, 1, 2, or 3, However, there is on average at least one Si-bonded hydrogen atom per molecule, preferably There are at least two Si-bonded hydrogen atoms per molecule.] The organopolysiloxane may be a linear, cyclic, or branched organopolysiloxane containing units of the formula:

[0044] Preferably, the organosilicon crosslinker is of the formula [ka] [where: R has the meaning given above, h is 0, 1, or 2; o is 0 or an integer from 1 to 1500, and p is 0 or an integer from 1 to 200; However, there is on average at least one Si-bonded hydrogen atom per molecule, preferably There are at least two Si-bonded hydrogen atoms per molecule.] It is an organopolysiloxane of the formula:

[0045] It is understood that in formula (VII), the o units -(SiR2O)- and p units -(SiRHO)- can be distributed in any desired manner in the organopolysiloxane molecule.

[0046] The organosilicon crosslinker contains at least 0.04 weight percent (wt%), preferably 0.8-1.7 wt%, of silicon-bonded hydrogen, based on the total weight of the organosilicon crosslinker. The organosilicon crosslinker has an average viscosity of 10-1000 cPs at 25°C, preferably 10-100 cPs at 25°C. The viscosity of the organosilicon crosslinker is determined by measurement using a rotational viscometer according to DIN EN ISO 3219.

[0047] The organosilicon crosslinking agent is employed so that the molar ratio of SiH groups to aliphatic unsaturated groups in the composition is 0.8-10.0, preferably 1.0-5, and more preferably 1.5-3.

[0048] The release coating composition includes a catalyst. In some embodiments, the release coating composition includes 300 parts per million (ppm) or less of the catalyst, based on the total weight of the release coating composition. For example, the release coating composition can include 50 to 300 ppm of the catalyst, based on the total weight of the release coating composition. Preferably, the release coating composition includes 250 ppm or less of the catalyst, based on the total weight of the release coating composition. In one such embodiment, the release coating composition can include 50 to 250 ppm of the catalyst, based on the total weight of the release coating composition. Advantageously, the release coating composition can be formulated to be curable at low temperatures, for example, 80°C or less, with a catalyst concentration of 200 ppm or less. Thus, in some embodiments, the release coating composition includes 200 ppm or less of the catalyst, based on the total weight of the release coating composition. In other embodiments, the release coating composition includes 150 ppm or less of the catalyst, based on the total weight of the release coating composition. For example, in embodiments, the concentration of catalyst for catalyzing curing can be between 50 and 150 ppm, 75 and 150 ppm, or 100 and 150 ppm of catalyst by total weight of the release coating composition.

[0049] The catalyst promotes the addition of Si-bonded hydrogen atoms from the organosilicon crosslinker to the aliphatic unsaturated groups of the organosilicon compound. Preferably, the catalyst is of the hydrosilylation type, which is understood to mean a catalyst that promotes the addition of Si-bonded hydrogen onto aliphatic multiple bonds.

[0050] Hydrosilylation catalysts known in the art are suitable for use in the release coating composition. When the catalyst is of the hydrosilylation type, it typically contains platinum, although other platinum group metals, such as rhodium, can be utilized. In embodiments, the catalyst can include finely divided platinum and metal, which can be present on a support such as silicon dioxide, aluminum oxide, or activated carbon. In other embodiments, the catalyst can be a platinum compound or complex. For example, suitable compounds and complexes include platinum halides, such as PtCl, HPtCl·6H0, NaPtCl·4H0, platinum-olefin complexes, platinum-alcohol complexes, platinum-alkoxide complexes, platinum-ether complexes, platinum-aldehyde complexes, platinum-ketone complexes, including the reaction product of HPtCl·6H0 with cyclohexanone, platinum-vinylsiloxane complexes, and, in particular, platinum-divinyltetramethylsiloxane complexes, with or without detectable inorganically bound halogen. Platinum compounds include platinum tetrachloride, ...

[0051] Preferably, the catalyst is a platinum complex containing at least one unsaturated group. In such embodiments, the catalyst can be a so-called Karstedt catalyst, i.e., a platinum(0) complex, particularly a platinum(0)-1,3-divinyl-1,1,3,3-tetramethyldisiloxane complex of formula Pt[[(CH=CH)(CHSi]O].

[0052] When the composition is formed by mixing component A and component B, the two components can contain all of the above-mentioned components in any desired combination, although generally one component will not simultaneously contain an organosilicon compound, an organosilicon crosslinker, and a hydrosilylation catalyst. Thus, for two-component compositions, the hydrosilylation catalyst is preferably provided as part of component (A) or component (B).

[0053] The release coating composition further comprises one or more inhibitors. In certain embodiments, it is preferable to include an inhibitor that is acceptable for contact with foodstuffs. In some embodiments, the curable composition may comprise a hydrosilylation inhibitor, which is understood to mean an agent that retards the addition of Si-bonded hydrogen to an aliphatic multiple bond at room temperature but does not retard curing at elevated temperatures. This type of inhibitor is a heat-inactivatable inhibitor or is sufficiently volatile to be expelled from the release coating composition at elevated temperatures. Such inhibitors are utilized to ensure that the release coating composition exhibits a desired processing life and cure initiation temperature.

[0054] Examples of suitable inhibitors include acetylenic alcohols such as 1-ethynyl-1-cyclohexanol, 2-methyl-3-butyn-2-ol, and 3,5-dimethyl-1-hexyn-3-ol, 3-methyl-1-dodecyn-3-ol, polymethylvinylcyclosiloxanes such as 1,3,5,7-tetravinyltetramethyltetracyclosiloxane, methylvinylSiO s such as divinyltetramethyldisiloxane, tetravinyldimethyldisiloxane, 1 / 2 Group and / or R2 vinyl SiO 1 / 2Examples of suitable inhibitors include low molecular weight silicone oils with terminal groups, trialkyl cyanurates, alkyl maleates such as diallyl maleate, dimethyl maleate, and diethyl maleate, alkyl fumarates such as diallyl fumarate and diethyl fumarate, organic hydroperoxides such as cumene hydroperoxide, tert-butyl hydroperoxide, and pinane hydroperoxide, organic peroxides, organic sulfoxides, organic amines, diamines and amides, phosphanes and phosphites, nitriles, triazoles, diaziridines, and oximes. In certain embodiments, the release coating composition contains one or more inhibitors in an amount of 5 wt% or less, based on the total weight of the release coating composition. In one such embodiment, the release coating composition contains one or more inhibitors in a quantitative fraction of 0.00001 to 5 wt% based on the total weight of the release coating composition. Preferably, the release coating composition contains one or more inhibitors in an amount of 0.00005 to 2 wt% based on the total weight of the composition. In another embodiment, one or more inhibitors may be provided in the release coating composition in an amount of 1 wt% or less, based on the total weight of the release coating composition. In this embodiment, one or more inhibitors may be provided in the release coating composition at 0.0001 to 1 wt% in each case based on the total weight of the composition.

[0055] A suitable inhibitor is of formula (VIII) [ka] [where: R 2 represents a hydrogen atom or a monovalent hydrocarbon group having 1 to 12 carbon atoms, optionally substituted with one or more hydroxy groups, provided that R 3 and R 4 When both are hydrogen atoms, R 2 is not a hydrogen atom, R 3 is a hydrogen atom or a monovalent hydrocarbon group having 1 to 12 carbon atoms, or R 3 is R 2together with the group forming a cyclic hydrocarbon group having 1 to 12 carbon atoms, R 4 is a hydrogen atom or a monovalent hydrocarbon group having 1 to 12 carbon atoms. is.

[0056] R 2 Group, R 3 groups, and R 4 Examples of such groups include alkyl groups such as methyl, ethyl, n-propyl, isopropyl, 1-n-butyl, 2-n-butyl, isobutyl, tert-butyl, n-pentyl, isopentyl, neopentyl, and tert-pentyl; hexyl groups such as n-hexyl; heptyl groups such as n-heptyl; octyl groups such as n-octyl, isooctyl groups such as 2,2,4-trimethylpentyl, nonyl groups such as n-nonyl; decyl groups such as n-decyl; dodecyl groups such as n-dodecyl; cycloalkyl groups such as cyclopentyl, cyclohexyl, cycloheptyl, and methylcyclohexyl; aryl groups such as phenyl; alkaryl groups such as o-tolyl, m-tolyl, p-tolyl, xylyl, and ethylphenyl; and aralkyl groups such as benzyl, α-phenylethyl, and β-phenylethyl.

[0057] R 2 can also be a vinyl group or an alkenyl group such as a group of formula -CH2CH2CH=CH(CH3)2(4,4-dimethyl-3-butenyl).

[0058] Suitable inhibitors according to formula (VIII) are of the formula: [ka] Linalool, a compound of 1-dodecen-3-ol, 1-decen-3-ol, 1-penten-3-ol, 1-hexen-3-ol, 1-hepten-3-ol, 1,4-pentadiene-3-ol, 2-methyl-2-propen-1-ol, 3-methyl-5-hexen-3-ol, 1-vinyl-cyclohexanol, 3-methyl-1-penten-3-ol, 2-methyl-1-hepten-3-ol, and 2-methyl-3-buten-2-ol.

[0059] Linalool can be used alone or in combination with other additional inhibitors, such as acetylenic alcohols. Examples of acetylenic alcohols include: 1-ethynylcyclohexan-1-ol (ECH), 2-methyl-3-butyn-2-ol (MB), 3-methyl-1-pentyn-3-ol, 2,5-dimethyl-3-hexyne-2,5-diol, 3,5-dimethyl-1-hexyn-3-ol, and 3,7-dimethyl-oct-1-yn-6-en-3-ol.

[0060] Preferred examples of acetylenic alcohols are: 1-ethynylcyclohexan-1-ol (ECH), and 2-methyl-3-butyn-2-ol (MB).

[0061] In certain embodiments, preferred inhibitors are MB and linalool.MB and linalool are available from BASF.In certain embodiments, it is preferred to use MB and linalool in combination.Surprisingly, in such embodiments, it is found that the pot life of release coating composition can be extended, release coating composition can be hardened, extractables can be reduced, and release coating composition can be hardened at low temperatures such as 80 ℃ or less.In these embodiments, it is preferred that the amount of linalool provided is greater than the amount of MB provided.

[0062] Additionally, the release coating composition may contain additional additives such as, for example, fillers, pigments, and / or dyes.

[0063] In some embodiments, the release coating composition contains a filler in an amount of up to 50% by weight of the total weight of the release coating composition, more preferably in an amount of 40%, 30%, and 10% by weight, in order of preference. In certain embodiments, the filler is absent or contained in an amount of less than 10% by weight, more preferably less than 5% by weight. Fillers can be added to change the viscosity of the uncured release coating composition, to change the rheological profile (e.g., thixotropy, thinning), to improve adhesion, or to change release properties such as release force. The latter is most affected by non-reinforcing fillers, while the former is most affected by reinforcing fillers.

[0064] The reinforcing and non-reinforcing fillers may be composed of the same material, examples of which include silica, alumina, titania, and mixtures thereof, iron oxide, talc, mica, carbon, etc. The reinforcing filler may be 50m 2 / g, more preferably 100m 2 / g, more preferably about 200m 2 / g or more. 2A preferred example of a reinforcing filler is a filler having a BET surface area of ​​less than 50 m 2 / g, more preferably 100m 2 / g or more, most preferably 200-300m 2 Fumed and colloidal silicas have surface areas in the range of 1 / g. Preferred non-reinforcing fillers include, for example, quartz, limestone, marble, dolomite, clay minerals, and ground minerals such as talc. Either type of filler can be used in its natural state, which is generally somewhat hydrophilic, and can be hydrophobized by techniques well known to those skilled in the art, for example, by coating with wax, metal stearates, silicone oils, or reactive coating with reactive silicones, such as those containing silicon-bonded alkoxy groups, or reactive silanes, such as alkylchlorosilanes, alkylalkoxysilanes, and hexamethyldisilizane. Filler modification can be performed ex situ, as is often the case, or in situ. Processes known in the art for performing such modifications are suitably employed.

[0065] Pigments can be used to change the color of the resulting release coating, which is generally colorless and transparent in the absence of fillers. When fillers are present, the composition can range from transparent to translucent to opaque, depending on the amount and particle size of the filler. Those skilled in the art of silicone release coatings generally do not consider traditional fillers such as silica, alumina, or titanium dioxide to be pigments because these fillers do not impart color to the composition and may even produce a transparent composition. Typical pigments include organic pigments and inorganic pigments such as various iron oxide pigments and carbon black. Suitable dyes include both natural and synthetic varieties. Preferably, the release coating composition contains no more than 5 wt. % of dyes and / or pigments, based on the total weight of the release coating, more preferably no more than 3 wt. %, and most preferably no more than 2 wt. However, in certain embodiments, the absence of dyes and / or pigments is preferred.

[0066] The release coating composition can be produced by preparing component (A) before forming the composition. Preferably, component (A) includes an organosilicon compound, an organosilicon composition, and one or more inhibitors. When included in component (A), the organosilicon composition and one or more inhibitors can be mixed with the organosilicon compound to form a mixture. Mixing can be carried out at a predetermined speed for a predetermined time, and can be performed using commercially available mixing equipment such as a Speedmixer® or Dispermat® equipped with a dissolver blade. The organosilicon compound, organosilicon composition, and one or more inhibitors can be as described above. Furthermore, component (A) can be formed by including one or more of the additives described above.

[0067] In certain embodiments, the curable composition can be produced by preparing component (B). Preferably, component (B) can include an organosilicon compound. In addition, component (B) can include one or more inhibitors, organosilicon crosslinkers, and catalysts. When included in component (B), the one or more inhibitors, organosilicon crosslinkers, and catalysts can be mixed with the organosilicon compound to form a mixture. Mixing can be carried out at a predetermined speed for a predetermined time, and commercially available mixing equipment, such as the mixing equipment described above, can be used. The organosilicon compound, one or more inhibitors, organosilicon crosslinkers, and catalysts can be as described above. Furthermore, component (B) can be formed by including one or more additives described above.

[0068] The release coating composition can be formed by mixing. In certain embodiments, component (A) and component (B) can be mixed to form the release coating composition before coating the substrate. Mixing can be performed in a conventional manner, such as at a predetermined speed, for a predetermined time, and by utilizing commercially available mixing equipment, such as the mixing equipment described above.

[0069] After mixing and before curing, the release coating composition exhibits a desired pot life. For example, at catalyst concentrations of 150 ppm or less, the release coating composition can exhibit a pot life of 8 hours or more. At higher catalyst concentrations, such as concentrations of 200 ppm, the release coating composition can exhibit a pot life of 6 hours or more.

[0070] After formation and before curing, the release coating composition preferably exhibits a desired viscosity. The viscosity is selected so that the release coating composition can be applied to a substrate without the need for specialized coating equipment. In embodiments, the release coating composition exhibits a viscosity of 100 to 800 cPs at 25°C. More preferably, the release coating composition exhibits a viscosity of 100 to 300 cPs at 25°C. Even more preferably, the release coating composition exhibits a viscosity of 120 to 300 cPs at 25°C. Viscosity can be determined by measurement using a rotational viscometer in accordance with DIN EN ISO 3219.

[0071] The desired viscosity of the release coating composition allows the composition to be formed without the need for a solvent.Therefore, in certain embodiments, the release coating composition is solventless, i.e., does not contain a solvent.For example, the release coating composition may not contain a solvent, such as an organic solvent, such as toluene, or an inorganic solvent, such as water.In the latter embodiment, the release coating composition is said to be non-aqueous.The elimination of the use of solvents reduces the cost of the composition, helps to avoid damage to the substrate during application and further processing of the release coating composition, and allows the composition to be applied to the substrate using conventional coating equipment, further reducing costs.

[0072] After forming the release coating composition, the surface of the substrate can be coated with the release coating composition. Suitable substrate surfaces can be any desired material that is solid at room temperature and 1013.25 hPa. The substrate can be a single-layer material or can have multiple layers. Suitable materials include paper, wood, cork, and plastic films, such as polyethylene or polypropylene films, woven and nonwoven fabrics of natural or synthetic fibers or glass fibers, ceramic articles, glass, metal, polyethylene-coated paper, and card and board, including asbestos, by which the surface can be defined. The polyethylene can include high-pressure polyethylene, medium-pressure polyethylene, or low-pressure polyethylene. The paper can be, for example, raw kraft paper, i.e., paper that has not been pretreated with chemicals and / or polymeric natural substances and has a basis weight of 60 to 150 g / m. 2 The paper may include low-grade papers such as absorbent papers, including kraft paper, unsized paper, low-freeness paper, machine-made paper, unglazed or uncalendered paper, paper known as "machine-glazed paper" because it is smooth on one side due to the use of dry-glazing cylinders without additional complexities during production, uncoated paper, or paper made from waste paper, i.e., recycled paper. Papers treated according to the present invention may also include high-grade papers such as low-absorbency paper, sized paper, high-freeness paper, chemical paper, calendered or polished paper, glassine paper, parchmented paper, or precoated paper. Cards and boards may also be low-grade or high-grade. Preferably, for linerless label applications, the substrate is part of a system containing one or more color-forming materials that undergo a thermal response upon heating to produce an image.

[0073] The release coating composition can be applied to a substrate to provide any desired thickness, pattern, or configuration. Application of the release coating composition to the surface of the substrate can be accomplished by known methods for applying coatings from liquid materials. Suitable methods include dipping, brushing, pouring, spraying, rolling, printing, e.g., by offset gravure coating equipment, knife coating, and airbrushing. Particularly suitable for applying the composition is a multi-roll system (4-6 rolls) such as rubber-steel-rubber, in which the die film is occasionally split to provide a final coating thickness of 0.1-2 μm.

[0074] The release coating composition can be applied to a substrate by the methods described above, for example, to form a linerless label roll. In some embodiments, the release coating composition can be applied to the surface of the substrate while the substrate is moving. In one such embodiment, the substrate can be moved at a speed of 50 to 500 m / min, preferably 100 to 300 m / min.

[0075] After application of the release coating composition to a substrate, the release coating composition can be cured. The composition can be cured at a predetermined temperature for a predetermined time.

[0076] Preferably, the release coating composition is an addition-cure system. In the context of describing the release coating composition, the release coating composition is "cured" until it has 5 wt% or less extractables based on the total weight of the release coating composition. The wt% of extractables can be measured by coating a substrate with the coating composition and placing the coated substrate in toluene for 24 hours. The concentration of silicone oil in toluene is then measured by atomic absorption spectroscopy. The results are expressed as the percentage of silicone coating extracted by toluene (dry weight / dry weight).

[0077] The release coating composition can be cured at ambient atmospheric pressure, i.e., approximately 1013.25 hPa, but can also be cured at higher or lower pressures. The release coating composition can be cured at a predetermined temperature or within a predetermined temperature range. For example, when using the release coating composition on heat-activatable label paper, the composition can be cured at a temperature of 80°C or less, which is below the activation temperature of the ink capsules in the paper, to prevent the ink capsules from changing. In such embodiments, curing can be performed at temperatures between 40°C and 80°C, more preferably between 60°C and 80°C. To achieve the aforementioned curing temperatures, it is preferable to use an oven, such as a convection oven, a heating tunnel, a heating roll, a heating plate, or infrared heat rays.

[0078] Another advantage of the release coating composition is that it cures at the temperatures described above at a faster rate than known compositions for such release coatings, or cures at a similar rate using less catalyst. For example, as shown in Figure 1, in certain embodiments, the release coating composition cures in 20 seconds or less at a catalyst concentration of 150 ppm or less.

[0079] In linerless label applications, the method for forming the linerless label can also include applying an adhesive to another surface of the substrate opposite the surface to which the release coating composition is applied and cured. In this embodiment, the release coating composition is preferably separated from the outer adhesive layer by the substrate. In this location, the cured release coating composition can define a first outer major surface, and the outer adhesive layer can define a second outer major surface. The resulting composite can then be wrapped onto itself without the use of a liner. [Example]

[0080] The following examples are presented solely for the purpose of further illustrating and disclosing embodiments of release coating compositions. One example of a release coating composition is set forth below as Example 1. Comparative Example 1, which is not part of the present invention, is also set forth below.

[0081] [Example 1] A linear organosilicon compound, available from Wacker Chemical Company and sold under the trade name "Vipo 50," was mixed with an organosilicon composition. The organosilicon compound had a viscosity of approximately 50 cPs at 25°C. The organosilicon composition had a viscosity of approximately 8000 cPs at 25°C and included a first siloxane and a second siloxane. The first siloxane was an organopolysiloxane having a viscosity of less than 1000 cPs and at least one terminal aliphatic unsaturated group, and the second siloxane was an organopolysiloxane having a viscosity of 400,000 cPs and an average of less than one functional group per molecule. The organosilicon compound and organosilicon composition were mixed to form a mixture containing 79.6 wt% organosilicon compound and 19.8 wt% organosilicon composition, based on the total weight of the mixture. The remaining mixture contained an inhibitor system comprising a blend of linalool and 2-methyl-3-butyn-2-ol. To form the mixture, the organosilicon compound and organosilicon composition were added to a vessel and stirred for 1 minute, after which the inhibitor system was added and stirred for 1 minute.

[0082] Next, the release coating composition of Example 1 was formed. The release coating composition contained 74.9 wt.% of the above-described mixture, 12.0 wt.% of an organosilicon crosslinker, and 13.1 wt.% of a catalyst. To form the release coating composition, a portion of the mixture was mixed with an organosilicon crosslinker. The organosilicon crosslinker was added and stirred with the mixture for 1 minute. This crosslinker was available from Wacker Chemical Company under the trade name "V88" and contained at least one SiH group. The organosilicon crosslinker was added to the mixture in an amount to provide a molar ratio of SiH groups to vinyl groups of 2.5 in the release coating composition. The catalyst was of the hydrosilylation type, as described above, and was available from Wacker Chemical Company under the trade name "C05." After the organosilicon crosslinker was added, the catalyst was added and stirred for 1 minute to form the release coating composition. The catalyst was added so that the release coating composition contained 150 ppm of catalyst based on the total weight of the release coating composition.

[0083] The release coating composition of Example 1 exhibited a viscosity of 161 cPs at 25° C., which was measured using a rotational viscometer according to DIN EN ISO 3219.

[0084] [Comparative Example 1] A branched organosilicon compound was mixed with an organosilicon composition. The organosilicon compound of Comparative Example 1 had a viscosity of 280 cPs at 25°C. The organosilicon composition had a viscosity of approximately 8000 cPs at 25°C and included a mixture of a first siloxane and a second siloxane. The first siloxane was an organopolysiloxane with a viscosity of less than 1000 cPs and at least one terminal aliphatic unsaturated group, and the second siloxane was an organopolysiloxane with a viscosity of greater than 400,000 cPs and an average of less than one functional group per molecule. The organosilicon compound and the organosilicon composition were mixed to form a mixture containing 79.6 wt% of the organosilicon compound and 19.8 wt% of the organosilicon composition, based on the total weight of the mixture. The remaining mixture contained an inhibitor system comprising a blend of linalool and 2-methyl-3-butyn-2-ol. To form a mixture, the organosilicon compound and organosilicon composition were added to a vessel and stirred for 1 minute, after which the inhibitor system was added and stirred for 1 minute.

[0085] Next, a coating composition for Comparative Example 1 was formed. This coating composition contained 74.9 wt% of the above-described mixture, 12.0 wt% of an organosilicon crosslinker, and 13.1 wt% of a catalyst. To form the coating composition, a portion of the mixture was mixed with an organosilicon crosslinker. The organosilicon crosslinker was added and stirred with the mixture for 1 minute. This crosslinker was available from Wacker Chemical Co. under the trade name "V88" and contained at least one SiH group. The organosilicon crosslinker was added to the mixture in an amount to provide a molar ratio of SiH groups to vinyl groups of 2.5 in the release coating composition. The catalyst was of the hydrosilylation type, as described above, and was available from Wacker Chemical Co. under the trade name "C05." The catalyst was added after the addition of the organosilicon crosslinker and stirred for 1 minute to form the release coating composition. The catalyst was added so that the release coating composition contained 150 ppm of catalyst based on the total weight of the release coating composition.

[0086] The coating composition of Comparative Example 1 exhibited a viscosity of 161 cPs at 25° C., which was measured using a rotational viscometer according to DIN EN ISO 3219.

[0087] Five milliliter samples of the release coating composition of Example 1 and the coating composition of Comparative Example 1 were applied to supercalendered kraft paper substrates using a single-sheet blade coater at 40 psi pressure. Each coated substrate was placed in an oven, which was at 80°C when the samples were placed inside. After each designated time, each sample was removed from the oven and the extractable silicone content (extractables) of the coated substrate was determined. For each sample, individually represented by a data point on the graph in Figure 1, the wt% extractables were measured by placing the coated substrate in toluene for 24 hours. The silicone oil concentration in toluene was then measured by atomic absorption spectroscopy using a Perkin Elmer PinAAcle 500 spectrometer. The results are expressed as the percentage (dry weight / dry weight) of the silicone coating extracted by toluene. This percentage corresponds to the cure of each sample. A composition is not "cured" until the extractables are 5 wt% or less, based on the total weight of the composition.

[0088] The results for the release coating composition of Example 1 and the coating composition of Comparative Example 1 are shown in Figure 1. As shown, the release coating compositions were able to cure in 20 seconds or less. More specifically, the release coating composition of Example 1 cured in 18 seconds. In stark contrast, the coating composition of Comparative Example 1 did not cure in the oven until 28 seconds. Thus, the release coating composition of Example 1 cured 35% faster than the coating composition of Comparative Example 1.

[0089] It will be apparent from the foregoing detailed description that various modifications, additions, and other alternative embodiments are possible without departing from the true scope and spirit. The embodiments and examples discussed herein have been chosen and described to provide the best explanation of the principles of the invention and its practical application, thereby enabling those skilled in the art to use the invention in various embodiments and with various modifications suited to the particular uses contemplated. It is to be understood that all such modifications and variations are within the scope of the invention.

Claims

1. 1. A release coating composition comprising: (a) an organosilicon compound having at least one terminal aliphatic unsaturated group, the organosilicon compound having a viscosity of 150 cPs or less; (b) an organosilicon composition exhibiting a viscosity at least 100 times that of said organosilicon compound; (c) an organosilicon crosslinker having at least one Si-bonded hydrogen atom; (d) a catalyst that promotes the addition of said at least one Si-bonded hydrogen atom to said at least one aliphatically unsaturated group; and (e) one or more inhibitors that retard the addition of said at least one Si-bonded hydrogen atom to said at least one aliphatically unsaturated group when said composition is at room temperature; A release coating composition wherein, prior to curing, the release coating composition exhibits a viscosity of 100 to 800 cPs at 25°C, and the release coating composition cures at a temperature of 80°C or less.

2. 10. The release coating composition of claim 1, wherein the release coating composition comprises 50 wt % or more of the organosilicon compound, based on the total weight of the release coating composition, and the organosilicon compound exhibits a viscosity of 25 to 150 cPS.

3. 10. The release coating composition of claim 1, wherein said release coating composition comprises up to 30 wt% of said organosilicon composition, based on the total weight of said release coating composition.

4. 10. The release coating composition of claim 1, wherein the organosilicon composition has a viscosity of 5,000 to 15,000 cPs at 25°C.

5. 10. The release coating composition of claim 1, wherein the organosilicon composition comprises a mixture of a first siloxane and a second siloxane.

6. 10. The release coating composition of claim 1, wherein the release coating composition comprises the catalyst at 150 ppm or less, based on the total weight of the release coating composition.

7. 10. The release coating composition of claim 1, wherein the release coating composition comprises up to 1 wt% of one or more inhibitors, based on the total weight of the release coating composition.

8. 10. The release coating composition of claim 1, wherein the release coating composition is cured to have an extractables content of 5 wt% or less, based on the total weight of the release coating composition.

9. 4. The release coating composition of claim 3, wherein said release coating composition comprises 5 to 20 wt % of said organosilicon composition, based on the total weight of said release coating composition.

10. The release coating composition of claim 4, wherein the organosilicon composition has a viscosity of 8,000 to 11,000 cPs at 25°C.

11. 6. The release coating composition of claim 5, wherein the first siloxane is an organopolysiloxane having a viscosity of 1000 cPs or less and having at least one terminal unsaturated fatty acid group.

12. 6. The release coating composition of claim 5, wherein the second siloxane is an organopolysiloxane having a viscosity of 400,000 cPs or less and an average functionality per molecule of less than one.

13. 10. The release coating composition of claim 1, wherein the catalyst is a platinum complex containing at least one unsaturated group.

14. providing a substrate; applying the release coating composition of claim 1 onto at least a portion of the substrate; and and curing said release coating composition at a temperature of 80° C. or less.

15. 13. The method of claim 12, wherein the release coating composition of claim 1 is cured in 20 seconds or less.

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