UV-curable resin-linear polysiloxane hot melt composition

Abstract

A hot melt composition comprising: (a) T Ar -D-based resin - a linear block copolymer, Ar the siloxane unit blocks are in at least some cases linked to the D-type siloxane unit blocks by linkages containing alkenyl groups, provided that the concentration of such alkenyl groups is in the range of 0.5 to 3.0 mole percent based on the total number of moles of silicon atoms in the resin-linear block copolymer; Ar A hot melt composition comprising: (a) a D-based resin-linear block copolymer; (b) a crosslinking agent containing an average of at least two (meth)acryloxy groups per molecule; (c) a radical photopolymerization initiator; and, optionally, (d) an ultraviolet stabilizer and, optionally, (e) an adhesion promoter.

Description

[Technical Field]

[0001] The present invention relates to ultraviolet light curable polysiloxane hot melt compositions, processes for curing such compositions, and articles containing such compositions. [Background technology]

[0002] Introduction The mini and micro light-emitting diode (LED) markets are growing rapidly, driven in part by their use in displays and automotive applications. Mini LED arrays are useful as backlight panels for standard liquid crystal displays, improving brightness, contrast, and black levels. Micro LEDs refer to tiny LEDs used directly as pixels in displays, specifically a combination of red, green, and blue LED dots. Both technologies require an encapsulant to protect the fragile LEDs and improve light extraction by replacing air with a silicone interlayer.

[0003] Encapsulant compositions have historically been applied to LED components by liquid injection processes. More recently, hot melt systems have proven more desirable due to advantages over liquid injection systems. Such advantages include easy coverage of large areas, process simplicity, and reworkability.

[0004] One form of encapsulant technology uses silicone encapsulants that are cured by hydrosilylation after application to the LED components. Hydrosilylation typically requires high temperatures, exceeding 60 degrees Celsius (°C), and / or cure times of one hour or more. Unfortunately, some display designs incorporate temperature-sensitive materials that cannot be exposed to high temperatures without impairing their functionality. Therefore, it is desirable to identify hot-melt encapsulation techniques that do not require the temperature or time of hydrosilylation cure systems to protect temperature-sensitive materials and improve manufacturing efficiency to meet the growing demand for mini- and micro-LED devices.

[0005] WO 2017068762 discloses a hot melt ultraviolet (UV) curable system that cures using thiol-ene chemistry. This system can cure at lower temperatures than hydrosilylation cure systems, but uses thiol-based reactants that can produce undesirable odors and can result in yellowing.

[0006] Identifying a hot melt encapsulation composition that cures at temperatures below 60°C and / or has a cure time of one hour or less, or even 30 minutes or less, and that does not utilize thiol-based reactants would advance the technology of LED encapsulants. Summary of the Invention

[0007] The present invention provides hot melt encapsulation compositions that cure at temperatures below 60° C. and / or have cure times of 1 hour or less, or alternatively 30 minutes or less, and that do not utilize thiol-based reactants.

[0008] The present invention is the result of the discovery of a resin-linear technology that can undergo acrylate-ene UV curing and can be a suitable hot melt encapsulant composition that does not require unbound nanophase particulates of MQ resin. Ar T having alkenyl functional groups in combination with a crosslinker having multiple (meth)acryloxy groups per molecule ArThe present invention utilizes a -D-based resin-linear block copolymer to provide a hot melt composition that can undergo UV acrylate-ene curing in just a few minutes, or even less than one minute, at temperatures below 60°C, or even below 40°C, or below 30°C, or even below 25°C, without the need for a thiol component.

[0009] In a first aspect, the present invention provides a method for producing a medicament for the treatment of a medicament comprising: (a Ar 80 to 99 parts by mass of at least one T type siloxane unit block containing a siloxane unit block and a D type siloxane unit block Ar -D-based resin-linear block copolymer, (i) T Ar The siloxane block has the structure (I):

[0010] [ka] and is connected to the D-type siloxane unit block by a bond selected from the group consisting of Ar is C6 to C 20 aryl, and R1 is C1-C 20 Alkyl groups and C2-C 20 alkenyl groups, with the proviso that T Ar -D-based resin - Linear block copolymer alkenyl R 1 The average concentration of R groups is in the range of 0.5 to 3.0 mole percent based on the total number of moles of silicon atoms. 2 , and R 3 are independently C1 to C 20 hydrocarbyl, where each dashed line corresponds to a valence bond to a silicon group, a hydrogen group, or a hydrocarbyl group; (ii) T for D-type siloxane unit blocks; Ar (iii) the resin-linear block copolymer contains 8 to 35 mole percent Si—OR′ bonds relative to the number of moles of silicone atoms, where R′ is H or C1 to C8 hydrocarbyl; (iv) each D-type siloxane unit block contains an average of 20 to 200 D-type siloxane units; and (v) each T ArThe siloxane unit block comprises 80 parts by weight to 99 parts by weight of at least one T Ar The hot melt composition comprises a D-type resin-linear block copolymer, (b) 0.5 to 20 parts by mass of a crosslinking agent containing an average of at least two (meth)acryloxy groups per molecule, (c) 0.1 to 10 parts by mass of a radical photopolymerization initiator, (d) 0 to 2.0 parts by mass of an ultraviolet stabilizer, and (e) 0 to 2.0 parts by mass of an adhesion promoter.

[0011] In a second aspect, the invention is a process comprising heating the hot melt composition of the first aspect to soften the hot melt composition, and then coating the softened hot melt composition onto at least a portion of a substrate to form a coating of the hot melt composition on at least a portion of a surface of the substrate.

[0012] In a third aspect, the invention is an article comprising the hot melt composition of the first aspect coating at least a portion of a surface of a substrate.

[0013] The compositions of the present invention are useful as LED encapsulants. DETAILED DESCRIPTION OF THE INVENTION

[0014] Test methods, unless a date is given with the test method number, refer to the test method most recent as of the priority date of this document. Reference to a test method includes both a reference to the testing society and the test method number. The following test method abbreviations and designations apply herein: ASTM refers to the American Society for Testing and Materials, EN refers to European Norm, DIN refers to Deutsches Institut fur Normung, JIS refers to Japanese Industrial Standards, and ISO refers to the International Organization for Standards.

[0015] Products identified by trade names refer to compositions available under those trade names as of the priority date of this document.

[0016] "Multiple" means two or more. "And / or" means "and, or as an alternative." All ranges are inclusive unless otherwise indicated. Identification of materials by trademark or trade name refers to materials having compositions sold under that trademark or trade name as of the priority date of this specification.

[0017] "Parts by weight" refers to the mass of a component in a composition measured in the same units of measure as the parts by weight of the other components to provide an indication of the mass of each component relative to the mass of the other components in the composition. For example, a composition containing 5 grams of component A and 10 grams of component B has 1 part by weight of component A and 2 parts by weight of component B, or alternatively, 5 parts by weight of component A and 10 parts by weight of component B. As used herein, parts by weight refers to the concentration of a component in a hot melt composition relative to the parts by weight of the other components in the hot melt composition, meaning that all parts by weight are based on the same units of mass for the components of the hot melt composition.

[0018] General term “C x~y "," "C x ~C y "," "Cx to Cy," and "Cx-Cy" are interchangeable in the context of chemical structures and refer to having x to y carbon atoms in the chemical structure.

[0019] The number average molecular weight (Mn), weight average molecular weight (Mw), polydispersity index (PDI), and % free resin for the materials were determined by gel permeation chromatography (GPC) using the following method: Sample preparation: Samples were prepared in toluene eluent at a concentration of 20 mg / mL polymer. The solution was shaken for approximately 2 hours at ambient temperature on a flat-bed shaker. The solution was filtered through a 0.45 μm PTFE syringe filter before injection. GPC was performed with a Viscotek GPC Max pump and autosampler. The flow rate was set at 1 mL / min, and the injection volume was set at 100 microliters for the standards and 200 μL for the study samples. Each sample was injected in duplicate. Separation was performed on two Agilent Plgel Mixed-B columns maintained at 35°C. The detector was a Viscotek TDA305 triple detector array maintained at 35°C. The triple detector included RI, UV, LALS, RALS, and DP. Software and data processing: Malvern OMNISEC 5.02 was used for data collection, and Malvern OMNISEC 5.12 was used for data compression. A total of 17 PS linear narrow molecular weight standards from Agilent with Mp values ​​ranging from 4,000 to 0.58 kg / mol were used for conventional molecular weight calibration. A third-order polynomial was used for calibration curve fitting. Therefore, all references to molecular weight averages, distributions, and molecular weights provided in this report are polystyrene (PS) equivalent values, and only RI was used for molecular weight calculations.

[0020] In one aspect, the present invention is a hot-melt composition. A "hot-melt" composition is characterized by a softening point of 50 degrees Celsius (°C) or higher, while typically not exceeding 150°C. The hot-melt composition of the present invention desirably has a softening point of 50°C or higher, preferably 60°C or higher, 70°C or higher, 80°C or higher, or 90°C or higher, and may be 100°C or higher, while simultaneously desirably not exceeding 150°C, preferably not exceeding 125°C, or even not exceeding 100°C. The softening point of the composition was measured using the ring and ball method of JIS K6863-1994. The softening of the hot-melt composition is reversible, meaning that the hot-melt composition can be repeatedly heated above its softening point and cooled below its softening point while maintaining hot-melt behavior.

[0021] Desirably, the hot melt compositions of the present invention have a storage modulus at 25°C greater than 0.01 megapascals (MPa) and a tan δ at 25°C less than 2.0, or preferably 1.5 or less, meaning that the hot melt compositions are non-flowable at 25°C. It is further desirable that the hot melt composition of the present invention have any one or any combination of one or more of the following additional characteristics that make it particularly suitable as an LED encapsulant: (i) a ratio of the viscosity at 25°C divided by the viscosity at 100°C, measured in kilopascals, that is 20 or more, and preferably 100 or more, while simultaneously being typically 10,000 or less, and can be 5000 or less, 4000 or less, or even 3800 or less; ii) a storage modulus at 25°C that is preferably greater than 0.1 MPa, while simultaneously being typically 100 MPa or less, alternatively 50 MPa or less, 25 MPa or less, 10 MPa or less, alternatively 8.5 MPa or less, or alternatively 8 MPa or less; and (iii) a Tan δ value at 25°C that is preferably 2.0 or less, while simultaneously being typically 0.01 or more, and can be 0.05 or more, 0.10 or more, or even 0.12 or more. The viscosity, storage modulus, and Tan δ values ​​of the compositions were measured by rotational rheometry using a TA Instruments ARES-G2 instrument with 25 mm parallel plates and a 1 mm sample thickness. The sample in the test apparatus was equilibrated at 20 °C for 5 minutes, and then the temperature was increased to 120 °C at a rate of 3 °C / min, with data collected every 9 seconds.

[0022] The hot melt composition comprises: (a) T Ar The hot melt composition may be, and preferably is, free of mercapto-functional siloxanes. It is even more desirable that the hot melt composition be free of mercapto-functional components. Additionally or alternatively, the hot melt may be free of unbound Q-based resin particles. "Unbound" refers to the T Ar-D-based resin - refers to a resin that does not contain covalent bonds to either the linear block copolymer or the crosslinker. "Q-based resin particle" refers to a polysiloxane molecule containing SiO2 of 40 mol% or more, and in many cases 50 mol% or more. 42 It refers to polysiloxane particles consisting of siloxane units, but 4 / 2 refers to four oxygen atoms each bonded to a silicon atom and covalently forming a siloxane bond with another silicon atom.

[0023] "Resin-linear block copolymer" refers to a block copolymer comprising one or more blocks of linear polymer bound to one or more blocks of resinous polymer. "Block" refers to a repeating section of multiple units of the same basic type. T Ar -D-based resin - Linear block copolymer is a resinous polymer block, T Ar and D-type siloxane unit blocks which are block or linear polymers.

[0024] T Ar Siloxane units of the type have the chemical formula: ArSi(OR') t O (3-t) / 2 and During the ceremony, Ar refers to an aryl group having 6 or more carbon atoms, and may have 7 or more, 8 or more, 9 or more, 10 or more, 12 or more, 14 or more, 16 or more, or even 18 or more carbon atoms, while at the same time typically having 20 or fewer carbon atoms, and may have 18 or fewer, 16 or fewer, 14 or fewer, 12 or fewer, 10 or fewer, or 8 or fewer carbon atoms, while preferably the aryl group is a phenyl group; R' in each occurrence is independently selected from hydrogen and hydrocarbyl groups, which preferably have 1 or more carbon atoms, and may have 2 or more, 3 or more, 4 or more, 5 or more, 6 or more, or even 7 or more carbon atoms, while at the same time typically have 8 or fewer carbon atoms, and may have 7 or fewer, 6 or fewer, 5 or fewer, 4 or fewer, 3 or fewer, or even 2 or fewer carbon atoms; The subscript t is the number of (OR') groups attached to the silicon atom and typically has a value in the range of 0-2. O (3-t) / 2 refers to (3-t) oxygen atoms bonded to a silicon atom, which are shared with other silicon atoms to form siloxane bonds.

[0025] T Ar The block of type siloxane units is composed of multiple T Ar It contains siloxane units.

[0026] D-type siloxane units have the general chemical formula: R2SiO 2 / 2 wherein O 2 / 2 refers to two oxygen atoms bonded to a silicon atom and shared with another silicon atom to form a siloxane bond, where each R is independently selected from hydrocarbyl groups having one or more carbon atoms, and may have 2 or more, 3 or more, 4 or more, 5 or more, 6 or more, even 7 or more, 8 or more, 10 or more, 12 or more, 14 or more, 16 or more, or even 18 or more carbon atoms, while typically having 20 or less, 18 or less, 16 or less, 14 or less, 12 or less, 10 or less, or 8 or less carbon atoms, and may have 7 or less, 6 or less, 5 or less, 4 or less, 3 or less, or even 2 or less carbon atoms. Typically, each R group is methyl. A block of D-type siloxane units contains multiple D-type siloxane units bonded together via covalent siloxane bonds.

[0027] T Ar The D-type resin-linear block copolymer is further characterized by the following properties: (i)T ArThe siloxane block has the structure (I):

[0028] [ka] and is connected to the D-type siloxane unit block by a bond selected from the group consisting of In the formula, Ar is as defined above. 1 is C1~C 20 Alkyl groups and C2-C 20 alkenyl groups (preferably vinyl groups), with the proviso that T Ar -D-based resin - Linear block copolymer R 1 The average concentration of alkenyl groups is in the range of 0.5 to 3.0 mol% (mol%), and can be 0.5 mol% or more, 0.75 mol% or more, 1.0 mol% or more, 1.5 mol% or more, 2.0 mol% or more, or even 2.5 mol% or more, while simultaneously being 3.0 mol% or less and 2.5 mol% or less, 2.0 mol% or less, 1.5 mol% or less, or even 1.0 mol% or less, based on the total number of moles of silicon atoms; R 2 , and R 3 are independently selected from R groups as described herein, preferably selected from methyl and ethyl groups, and each dashed line corresponds to a valence bond to a silicon group, a hydrogen group, or a hydrocarbyl group; (ii) T for D-type siloxane unit block Ar The molar ratio of the D-type siloxane unit blocks is 2 or more, and preferably each D-type siloxane unit is Ar and is capped at both ends with a siloxane unit block. (iii)T Ar The D-based resin-linear block copolymer has sufficient OR' groups present to provide 8 or more, in some cases 9 or more, 10 or more, 11 or more, 12 or more, 14 or more, 16 or more, 18 or more, 20 or more, 22 or more, 24 or more, 26 or more, or even 28 or more, while simultaneously providing 35 or less, in some cases 30 or less, 25 or less, 20 or less, 15 or less, or even 10 or less, T Ar- D-based resin - having the presence of OR' groups sufficient to provide a mole percent (mol %) of Si-OR' bonds relative to the total number of moles of silicone atoms in the linear block copolymer; (iv) each D-type siloxane unit block contains, on average, 10 to 200 D-type siloxane units, and may contain 10 or more, 20 or more, 30 or more, 40 or more, 50 or more, 60 or more, 70 or more, 80 or more, 90 or more, 100 or more, 120 or more, 140 or more, 160 or more, or even 180 or more D-type siloxane units, while simultaneously typically containing, on average, 200 or less, 180 or less, 160 or less, 140 or less, 120 or less, 100 or less, 90 or less, 80 or less, 70 or less, 60 or less, 50 or less, 40 or less, 30 or less, or even 20 or less D-type siloxane units; (v)Each T Ar The siloxane unit block has a weight average molecular weight (Mw) in the range of 500 to 10,000 grams / mole, and can have a Mw of 500 or more, 750 or more, 1000 or more, 2500 or more, 5000 or more, or even 7500 or more, while at the same time, typically has a Mw of 10,000 or less, 7500 or less, 5000 or less, or 2500 or less, and can have a Mw of 1000 or less, or even 750 or less.

[0029] 29 T by Si NMR spectroscopy Ar -D-based resin - Determination of the average number of D-type siloxane units in a linear block copolymer]. Ar -D-based resin - T in linear block copolymer Ar The average Mw of the moiety siloxane unit blocks is determined by gel permeation chromatography (GPC) using the procedure described herein above.

[0030] T Ar The D-based resin-linear block copolymer may be free of (meth)acryloxy groups, and indeed the entire composition may be free of (meth)acyloxy-functional polysiloxanes.

[0031] The hot melt composition comprises at least one T Ar-D-based resin - containing 80 parts by mass or more of a linear block copolymer, and at least one T Ar -D-based resins - may contain 85 parts by weight or more, 90 parts by weight or more, 95 parts by weight or more, or even 97 parts by weight or more of a linear block copolymer, while at the same time typically containing at least one T Ar -D-based resin - containing 99 parts by mass or less of a linear block copolymer, and at least one T Ar -D-based resin - containing 98 parts by mass or less, 95 parts by mass or less, 90 parts by mass or less, or even 85 parts by mass or less of a linear block copolymer.

[0032] T Ar -D-based resins - linear block copolymers are alkenyl-functional R"3SiO 1 / 2 It may be free of siloxane units, R″ is hydrocarbyl, and O 1 / 2 refers to an oxygen bonded to a silicon atom and shared with another silicon atom in a siloxane bond.

[0033] The crosslinker is a molecule that contains an average of two or more (meth)acryloxy groups per molecule, and can contain three or more, or even four or more, while at the same time typically containing no more than eight, seven or less, six or less, five or less, four or less, or even three or less (meth)acryloxy groups per molecule.

[0034] To avoid loss of composition components during heating (i.e., to achieve stable curability), it is desirable for the crosslinker and / or radical photoinitiator to have a boiling point at 101 kilopascals of more than 100°C, preferably 150°C or more, more preferably 200°C or more, while at the same time generally having a boiling point of 400°C or less, and can have a boiling point of 350°C or less, 300°C or less, 250°C or less, or even 200°C or less.

[0035] The crosslinker may be one or more compounds selected from compounds having average chemical structures (III) and (IV): R' m CX (4-m) (III), XR”-X (IV) and During the ceremony, each R', in each occurrence, is independently selected from alkyl groups having 1 to 20 carbon atoms, and may have 1 or more, 2 or more, 3 or more, 4 or more, 5 or more, 6 or more, 7 or more, 8 or more, 10 or more, 12 or more, 14 or more, 16 or more, or even 18 or more carbon atoms, while simultaneously typically having 20 or fewer, 18 or fewer, 16 or fewer, 14 or fewer, 12 or fewer, 10 or fewer, 8 or fewer, 6 or fewer, 4 or fewer, or even 2 or fewer carbon atoms; each X is independently selected from a —CH2OC(O)CH═CH2 group and a —CH2OC(O)C(CH3)═CH2 group; R" is an alkylene group having from 1 to 20 carbon atoms, and can have 1 or more, 2 or more, 3 or more, 4 or more, 5 or more, 6 or more, 7 or more, 8 or more, 9 or more, 10 or more, 11 or more, 12 or more, 14 or more, 16 or more, or even 18 or more carbon atoms, while simultaneously having 20 or fewer, 18 or fewer, 16 or fewer, 14 or fewer, 12 or fewer, 10 or fewer, 8 or fewer, 6 or fewer, 4 or fewer, or even 2 or fewer carbon atoms.

[0036] Examples of suitable crosslinkers include trimethylpropane triacrylate, pentaerythritol tetraacrylate, and 1,12-dodecanediol dimethacrylate.

[0037] The concentration of the crosslinker in the hot melt composition typically ranges from 0.5 to 20 parts by weight, and may be present in a concentration of 0.5 or more, 1.0 or more, 2.0 or more, 4.0 or more, 6.0 or more, 8.0 or more, 10.0 or more, 12.0 or more, 14.0 or more, 16.0 or more, or even 18.0 or more, while simultaneously typically not more than 20.0, 18.0 or less, 16.0 or less, 14.0 or less, 12.0 or less, 10.0 or less, 8.0 or less, 5.0 or less, 4.0 or less, 3.0 or less, 2.0 or less, or even 1.0 part by weight or less.

[0038] The hot melt composition contains a radical photopolymerization initiator at a concentration of 0.1 parts by mass or more, 0.5 parts by mass or more, 1.0 parts by mass or more, 2.0 parts by mass or more, 3.0 parts by mass or more, 4.0 parts by mass or more, 5.0 parts by mass or more, 6.0 parts by mass or more, 7.0 parts by mass or more, 8.0 parts by mass or more, or even 9.0 parts by mass or more, while simultaneously containing a radical photopolymerization initiator at a concentration of 10 parts by mass or less, 9.0 parts by mass or less, 8.0 parts by mass or less, 7.0 parts by mass or less, 6.0 parts by mass or less, 5.0 parts by mass or less, 4.0 parts by mass or less, 3.0 parts by mass or less, 2.0 parts by mass or less, or even 1.0 parts by mass or less.

[0039] Examples of the radical photopolymerization initiator include any one or a combination of two or more components selected from the group consisting of benzophenone and benzophenone derivatives, acetophenone and acetophenone derivatives, benzoin and its alkyl esters, phosphine oxide derivatives, xanthone derivatives, oxime ester derivatives, and camphorquinone.Suitable commercially available photoinitiators include 2,6-bis(4-azidobenzylidene)cyclohexanone, 2,6-bis(4-azidobenzylidene)-4-methylcyclohexanone, 1-hydroxyl-cyclohexyl-phenyl-ketone (available under the name OMNIRAD™ 184), 2-methyl-1[4-(methylthio)phenyl]-2-morpholinopropan-1-one (available under the name OMNIRAD™ 907), 2-hydroxy-2methyl-1-phenyl-propan-1-one (available under the name OMNIRAD™ 1173), 2-hydroxy-1-[4-(2-hydroxyethoxy)phenyl]-2-methyl-1-propanone (available under the name OMNIRAD™ 2959), and methyl benzoyl formate (OMNIRAD™ 184). MBF), α,α-dimethoxy-α-phenylacetophenone (available under the name OMNIRAD651), 2-benzyl-2-(dimethylamino)-1-[4-(4-morpholinyl)phenyl]-1-butanone (available under the name OMNIRAD369), diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide (available under the name OMNIRAD TPO), ethyl(2,4,6-trimethylbenzoyl)phenylphosphinate (available under the name OMNIRAD TPO-L), and oxime ester compounds (Adeka Examples of suitable photoinitiators include 12-thioxanthene-9-one, 10-methylphenothiazine, isopropyl-9H-thioxanthene-9-one, 2,4-diethyl-9H-thioxanthene-9-one, 2-chlorothioxanthene-9-one, and 1-chloro-4-propoxy-9H-thioxanthene-9-one (available from IGM Corporation as products N-1919, NCI-831, NCI-930, NCI-730, and NCI-100), 12-thioxanthene-9-one, 10-methylphenothiazine, isopropyl-9H-thioxanthene-9-one, 2,4-diethyl-9H-thioxanthene-9-one, 2-chlorothioxanthene-9-one, and 1-chloro-4-propoxy-9H-thioxanthene-9-one. OMNIRAD is a trademark of IGM Group BV. One particularly desirable radical photoinitiator is 2,4,6-trimethylbenzoylphenylphosphinate.

[0040] Optionally, the hot melt composition may include an ultraviolet stabilizer. UV stabilizers are radical scavengers that can extend the shelf life of the hot melt composition by inhibiting cure until the hot melt composition is intentionally exposed to UV light. Radical scavengers include phenolic compounds such as any one or any combination of two or more of the following: 4-methoxyphenol (MEHQ, the methyl ether of hydroquinone), hydroquinone, 2-methylhydroquinone, 2-t-butylhydroquinone, t-butylcatechol, butylated hydroxytoluene, and butylated hydroxyanisole. Other types of ultraviolet stabilizers include phenothiazines and anaerobic inhibitors, such as NPAL-type inhibitors (tris-(N-nitroso-N-phenylhydroxylamine) aluminum salts) available from Albemarle Corporation.

[0041] The concentration of the UV stabilizer is typically 0 parts by weight or more, and can be 0.1 parts by weight or more, 0.5 parts by weight or more, 1.0 parts by weight or more, or even 1.5 parts by weight or more, while at the same time typically is 2.0 parts by weight or less, 1.5 parts by weight or less, 1.0 parts by weight or less, or even 0.5 parts by weight or less.

[0042] Optionally, the hot melt composition may contain an adhesion promoter. Suitable adhesion promoters include organosilicon compounds having at least one silicon-bonded alkoxy group in the molecule. Examples of this alkoxy group include methoxy, ethoxy, propoxy, butoxy, and methoxyethoxy groups, with methoxy being particularly preferred. In addition, groups bonded to silicon atoms other than alkoxy groups in organosilicon compounds include halogen-substituted or unsubstituted monovalent hydrocarbon groups such as alkyl groups, alkenyl groups, aryl groups, aralkyl groups, halogenated alkyl groups, halogenated aryl groups, and halogenated aralkyl groups; glycidoxyalkyl groups such as 3-glycidoxypropyl and 4-glycidoxybutyl; epoxycyclohexylalkyl groups such as 2-(3,4-epoxycyclohexyl)ethyl and 3-(3,4-epoxycyclohexyl)propyl; epoxyalkyl groups such as 3,4-epoxybutyl and 7,8-epoxyoctyl; acrylic groups containing monovalent organic groups such as 3-methacryloxypropyl; and hydrogen atoms. The adhesion promoter preferably contains a group reactive with an alkenyl group or a silicon-bonded hydrogen atom. Specifically, the adhesion promoter preferably contains a silicon-bonded hydrogen atom or an alkenyl group. Furthermore, since the adhesion promoter can impart good adhesion to various types of substrates, it preferably has at least one epoxy-containing monovalent organic group per molecule. Examples of this type of adhesion promoter include organosilane compounds, organosiloxane oligomers, and alkyl silicates. Examples of the molecular structure of the organosiloxane oligomer or alkyl silicate include a linear structure, a partially branched linear structure, a branched structure, a cyclic structure, and a network structure. The linear structure, branched structure, and network structure are particularly preferred.Examples of adhesion promoters include 3-glycidoxypropyltrimethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-methacryloxypropyltrimethoxysilane, a mixture of a siloxane compound having at least one silicon-bonded alkenyl group or at least one silicon-bonded hydrogen atom and at least one silicon-bonded alkoxy group per molecule, a silane compound or siloxane compound having at least one silicon-bonded alkoxy group per molecule, and a siloxane compound having at least one silicon-bonded hydroxyl group and at least one silicon-bonded alkenyl group per molecule, and silane compounds such as methyl polysilicate, ethyl polysilicate, and epoxy-containing ethyl polysilicate. The adhesion promoter is preferably a low-viscosity liquid, and although its viscosity is not particularly limited, it is preferably 1 to 500 millipascals (mPa) at 25°C.

[0043] The concentration of the adhesion promoter is typically 0 parts by weight or more, and can be 0.1 parts by weight or more, 0.5 parts by weight or more, 1.0 parts by weight or more, or even 1.5 parts by weight or more, while at the same time typically is 2.0 parts by weight or less, 1.5 parts by weight or less, 1.0 parts by weight or less, or even 0.5 parts by weight or less.

[0044] In particular, the hot melt compositions of the present invention may be free of hydrosilylation catalysts such as platinum catalysts. Thus, the hot melt compositions may be free of platinum, which may be desirable to avoid yellowing of the composition and to keep costs lower than systems requiring platinum catalysts.

[0045] In another aspect, the present invention is a method of using the hot melt composition of the present invention as a curable coating on a substrate. The method includes heating the hot melt composition of the present invention to soften the hot melt composition, and then coating the softened hot melt composition onto at least a portion of a substrate to form a coating of the hot melt composition on at least a portion of the surface of the substrate. The method can further include exposing the hot melt composition coating to ultraviolet light to cause crosslinking of the composition coating. Crosslinking occurs when the (meth)acryloxy groups of the crosslinker are bonded to T Ar -D-type resin - It is produced by reacting with the alkenyl group of the linear block copolymer.

[0046] In a particularly desirable application, the hot melt composition of the present invention is an encapsulant for light emitting diodes. In such applications, the process is as described, and the substrate onto which the hot melt composition is coated contains light emitting diodes. The coating covers the light emitting diodes, thereby encapsulating them, and the coating is then cured by exposure to UV light.

[0047] In yet another aspect, the present invention is an article comprising the hot melt composition of the present invention coating at least a portion of a surface of a substrate. Desirably, the substrate, most desirably the portion of the substrate coated with the hot melt composition, comprises a light emitting diode. Example

[0048] Synthesis of silanol-terminated polydimethylsiloxane (PDMS) The silanol-terminated PDMS materials for the following examples are prepared by starting with shorter-chain silanol-terminated PDMS and reacting to build longer-chain silanol-terminated PDMS using a potassium hydroxide (KOH) catalyst solution while purging the reaction with nitrogen to remove water during the reaction. Chain length is monitored by monitoring the change in concentration of the OH band in Fourier transform infrared spectroscopy (FT-IR). Different chain lengths can be created by starting with silanol-terminated PDMS of different chain lengths, using different concentrations of catalyst, and reacting for different times. Once the reaction is complete, 29 The degree of polymerization (DP) is confirmed by Si NMR. The silanol-terminated PDMS materials of the following examples are characterized in Table 1.

[0049] [Table 1]

[0050] The following are the procedures for the longest and shortest silanol-terminated PDMS used in the examples. Those skilled in the art should be able to prepare mid-range silanol-terminated PDMS materials based on these procedures. This procedure uses starting silanol-terminated PDMS with a viscosity in the range of 50 to 120 centistokes (commercially available from The Dow Chemical Company under the name XIAMETER™ PMX-0156). XIAMETER is a trademark of Dow Silicones Corporation. DOWSIL is a trademark of The Dow Chemical Company.

[0051] Silanol-terminated PDMS1: Degree of polymerization (DP) = 54 Add 500.0 g of starting silanol-terminated PDMS to a 1-liter, three-necked round-bottom flask equipped with a polytetrafluoroethylene stirring paddle and thermocouple, leaving one neck open while purging with nitrogen gas at a flow rate of 1.5 standard cubic feet per hour. Add 0.17 g of a 3 wt. % potassium hydroxide solution to the flask at 90°C. After 3 hours at 90°C, add 0.53 g of a 2.5 wt. % aqueous phosphoric acid solution. Cool the solution to 25°C. Purge with nitrogen gas overnight to remove water. Filter through a nylon filter to obtain PDMS1. 29 Si NMR confirms that PDMS1 has a DP of 54.

[0052] Silanol-terminated PDMS2: DP=98 Add 1255.6 g of starting silanol-terminated PDMS to a 1-liter, three-necked, round-bottom flask equipped with a polytetrafluoroethylene stirring paddle and thermocouple, leaving one neck open while purging with nitrogen gas at a flow rate of 1.5 standard cubic feet per hour. Add 0.42 g of a 3 wt. % potassium hydroxide solution to the flask at 90°C. After 3.5 hours at 90°C, add 1.32 g of a 2.5 wt. % aqueous phosphoric acid solution. Cool the solution to 25°C. Purge with nitrogen gas overnight to remove water. Filter through a nylon filter to obtain PDMS2. 29 Si NMR confirms that PDMS2 has a DP of 98.

[0053] T Ar -D-based resins - linear block copolymers RL1 to RL6 In addition to PDMS1-4, Table 2 lists the components used with silanol-terminated PDMS to make RL1-RL6.

[0054] [Table 2] DOWSIL is a trademark of The Dow Chemical Company.

[0055] RL1: 45 wt% resin / 55 wt% silanol-terminated PDMS1 and vinyl functionalized Charge 90.0 g of resin and 185.5 g of toluene into a one liter (1 L) four-neck round-bottom flask equipped with a thermocouple, a polytetrafluoroethylene stirring paddle, and a Dean-Stark apparatus attached to a water-cooled condenser. Add enough additional toluene to equal the capacity of the Dean-Stark apparatus. Apply an inert gas blanket and reflux for 30 minutes to remove water.

[0056] Diacetoxysilane-terminated PDMS was prepared by adding 8.50 g of VTA and 5.49 g of acetoxysilane to a mixture of 59.2 g of toluene and 110.0 g of silanol-terminated PDMS1 in a 500 milliliter round-bottom flask. The mixture was stirred for 1 hour. The resulting diacetoxysilane-terminated PDMS was quickly added to the flask containing the resin at 106 °C to form a reaction mixture. The mixture was refluxed for 2 hours. The reaction mixture was cooled to 90 °C and 21.9 g of deionized water was added. Water and the acetic acid by-product were removed by azeotropic distillation. Another water addition was performed. 81.0 g of volatiles were removed by distillation to obtain a concentrated solution. The addition and removal of water was repeated three times. The resulting solution was filtered through a 5-micrometer nylon filter. The volatiles were reduced using a rotovap to increase the solids content. A translucent solution of RL1 in toluene remained with an active concentration of RL1 of 79.6 wt % based on the solution weight.

[0057] RL2: 35 wt% resin / 65 wt% silanol-terminated PDMS2 and vinyl functionalized Charge 70.0 g of resin and 230.0 g of toluene into a one liter (1 L) four-neck round-bottom flask equipped with a thermocouple, a polytetrafluoroethylene stirring paddle, and a Dean-Stark apparatus attached to a water-cooled condenser. Add enough additional toluene to equal the capacity of the Dean-Stark apparatus. Apply an inert gas blanket and reflux for 30 minutes to remove water.

[0058] Diacetoxysilane-terminated PDMS was prepared by adding 8.50 g of VTA and 0.56 g of acetoxysilane to a mixture of 70.0 g of toluene and 130.0 g of silanol-terminated PDMS2 in a 500 ml round-bottom flask. The mixture was stirred for 1 hour. The resulting diacetoxysilane-terminated PDMS was quickly added to the flask containing the resin at 106 °C to form a reaction mixture. Reflux for 2 hours. The reaction mixture was cooled to 106 °C and 1.75 g of acetoxysilane was added. Reflux for 1 hour. The mixture was cooled to 25 °C and 16.9 g of deionized water was added. Water and the acetic acid by-product were removed by azeotropic distillation. Another water addition and removal was performed. Volatiles were removed by distillation to obtain a concentrated solution. The addition and removal of water was repeated three times. The resulting solution was filtered through a 5-micrometer nylon filter. The volatiles were reduced using a rotovap to increase the solids content. A translucent solution of RL2 in toluene remains with an active concentration of RL2 in toluene of 72.9 wt % based on the solution weight.

[0059] RL3: 45 wt% resin / 55 wt% silanol-terminated PDMS4 and vinyl functionalized Charge 270.0 g of resin and 722.3 g of toluene into a three liter (3 L) four-neck round-bottom flask equipped with a thermocouple, a polytetrafluoroethylene stirring paddle, and a Dean-Stark apparatus attached to a water-cooled condenser. Add enough additional toluene to equal the capacity of the Dean-Stark apparatus. Apply an inert gas blanket and reflux for 30 minutes to remove water.

[0060] Diacetoxysilane-terminated PDMS was prepared by adding 25.50 g of VTA and 10.36 g of acetoxysilane to a mixture of 177.7 g of toluene and 330.0 g of silanol-terminated PDMS4 in a 500 mL round-bottom flask. The mixture was stirred for 1 hour. The resulting diacetoxysilane-terminated PDMS was quickly added to the flask containing the resin at 106 °C to form a reaction mixture. The mixture was refluxed for 2 hours. The mixture was cooled to 90 °C and 56.0 g of deionized water was added. Water and the acetic acid by-product were removed by azeotropic distillation. Another water addition was performed. 300.0 g of volatiles were removed by distillation to obtain a concentrated solution. This water addition and removal process was repeated three times. The resulting solution was filtered through a 5-micrometer nylon filter. The volatiles were reduced using a rotovap to increase the solids content. A translucent solution of RL3 in toluene remained with an active RL3 concentration of 78.7 wt.% based on the solution weight.

[0061] RL4: 45 wt% resin / 55 wt% silanol-terminated PDMS2 and vinyl functionalized Charge 90.0 g of resin and 230.0 g of toluene into a one liter (1 L) four-neck round-bottom flask equipped with a thermocouple, a polytetrafluoroethylene stirring paddle, and a Dean-Stark apparatus attached to a water-cooled condenser. Add enough additional toluene to equal the capacity of the Dean-Stark apparatus. Apply an inert gas blanket and reflux for 30 minutes to remove water.

[0062] Diacetoxysilane-terminated PDMS was prepared by adding 7.71 g of VTA to a mixture of 70.0 g of toluene and 110.0 g of silanol-terminated PDMS2 in a 500 ml round-bottom flask. The mixture was stirred for 1 hour. The resulting diacetoxysilane-terminated PDMS was quickly added to the flask containing the resin at 106 °C to form a reaction mixture. Reflux for 2 hours. The reaction mixture was cooled to 106 °C, and 0.79 g of VTA and 6.72 g of acetoxysilane were added. Reflux for 1 hour. The mixture was cooled to 90 °C, and 23.8 g of deionized water was added. Water and the acetic acid by-product were removed by azeotropic distillation. Another water addition was removed. Volatiles were removed by distillation to obtain a concentrated solution. The addition and removal of water was repeated three times. The resulting solution was filtered through a 5-micrometer nylon filter. The volatiles were reduced using a rotovap to increase the solids content. A translucent solution of RL4 in toluene remains with an active RL4 concentration of 71.1 wt % based on the solution weight.

[0063] RL5: 45 wt% resin / 55 wt% silanol-terminated PDMS3 and vinyl functionalized Charge 90.0 g of resin and 240.8 g of toluene into a one liter (1 L) four-neck round-bottom flask equipped with a thermocouple, a polytetrafluoroethylene stirring paddle, and a Dean-Stark apparatus attached to a water-cooled condenser. Add enough additional toluene to equal the capacity of the Dean-Stark apparatus. Apply an inert gas blanket and reflux for 30 minutes to remove water.

[0064] Diacetoxysilane-terminated PDMS was prepared by adding 8.50 g of VTA to a mixture of 59.2 g of toluene and 110.0 g of silanol-terminated PDMS3 in a 500 ml round-bottom flask. The mixture was stirred at 25 °C for 1 hour. The resulting diacetoxysilane-terminated PDMS was quickly added to the flask containing the resin at 106 °C to form a reaction mixture. Reflux for 2 hours. The reaction mixture was cooled to 106 °C and 7.49 g of acetoxysilane was added. Reflux for 1 hour. The mixture was cooled to 90 °C and 25.1 g of deionized water was added. Water and the acetic acid by-product were removed by azeotropic distillation. Another water addition was performed. 100 g of volatiles were removed by distillation to obtain a concentrated solution. This water addition and removal process was repeated three times. The resulting solution was filtered through a 5-micrometer nylon filter. The volatiles were reduced using a rotovap to increase the solids content. A translucent solution of RL5 in toluene remains with an active RL5 concentration of 78.7 wt % based on the solution weight.

[0065] RL6: 45 wt% resin / 55 wt% silanol-terminated PDMS4 and no alkenyl functionalization Charge 90.0 g of resin and 240.8 g of toluene into a one liter (1 L) four-neck round-bottom flask equipped with a thermocouple, a polytetrafluoroethylene stirring paddle, and a Dean-Stark apparatus attached to a water-cooled condenser. Add enough additional toluene to equal the capacity of the Dean-Stark apparatus. Apply an inert gas blanket and reflux for 30 minutes to remove water.

[0066] Diacetoxysilane-terminated PDMS was prepared by adding 11.78 g of acetoxysilane to a mixture of 59.3 g of toluene and 110.0 g of silanol-terminated PDMS4 in a 500 mL round-bottom flask. The mixture was stirred for 1 hour. The resulting diacetoxysilane-terminated PDMS was quickly added to the flask containing the resin at 106 °C to form a reaction mixture. The mixture was refluxed for 2 hours. The solution was cooled to 25 °C and 18.7 g of deionized water was added. Water and the acetic acid by-product were removed by azeotropic distillation. Another water addition was then added and removed. Volatiles were removed by distillation to obtain a concentrated solution. This water addition and removal process was repeated three times. The resulting solution was filtered through a 5-micrometer nylon filter. The volatiles were reduced using a rotovap to increase the solids content. A translucent solution of RL6 in toluene remained, with an active RL6 concentration of 73.1 wt.% based on the solution mass.

[0067] Table 3 shows the T Ar The properties of the D-type resin linear block copolymers RL1 to RL6 are summarized below.

[0068] [Table 3]

[0069] Sample Composition Using RL1 to RL6 and the ingredients in Table 4, prepare the following sample compositions.

[0070] [Table 4]

[0071] Prepare samples by uniformly mixing the parts by weight of each component specified in Table 5 in toluene to form a sample. For the resin-linear component, use the solution of the resin-linear component in toluene as prepared in an amount corresponding to the parts by weight of the active material (i.e., parts by weight of the resin-linear block copolymer) as listed in Table 5. Combine the components in a dental cup and mix the components uniformly using a dental mixer. Coat the formulation onto an ethylene tetrafluoroethylene (ETFE) film and dry at 70°C for 1 hour before characterization.

[0072] Dried samples are characterized to determine whether they meet the requirements for being a "hot melt" composition, as described above, according to JIS K6863-1994: a softening point in the range of 50 to 150°C, a storage modulus at 25°C greater than 0.01 MPa, a Tan δ value at 25°C less than 5.0, and a ratio of viscosity at 25°C to viscosity at 100°C greater than 20. The samples are also characterized for their "curability." To be suitably UV-curable, samples must pass the following UV-curability test. To be suitable for optical encapsulation, such as LED encapsulation, the composition should cure into a material with a percent transmittance (%T) of optical light greater than 90%. The following procedure is used to determine %T: [Ac] / [Vi] is the molar ratio of (meth)acryloxy groups to vinyl groups in the composition. The characterization results for various samples are summarized in Table 5.

[0073] UV curing test The sample is coated onto ethylene tetrafluoroethylene (ETFE) film and dried at 70°C to form a 200 micrometer thick sample film. The sample film is covered with another ETFE film and sandwiched between the ETFE films. The sandwiched sample is placed in a Raven-exchanged UVitron SkyRAY and exposed to 365 nanometer UV radiation (250 milliwatts) for 16 seconds. The sample is turned over and the exposure is repeated. The total UV radiation dose is 8 joules per square centimeter of UV radiation (4 joules per square centimeter on each side).

[0074] Gel Percentage The gel percentage (Gel%) is determined by weighing a sample (approximately 1.0 g) of the cured hot melt composition to obtain the starting sample mass, placing the sample in a 40 milliliter dental cup, adding 15.0 g of toluene to the dental cup, shaking for 1 hour, and decanting the toluene solution to leave the undissolved cured hot melt material. The undissolved cured hot melt material is transferred to a tared aluminum pan, dried at 120°C for 2 hours, and weighed to determine the mass of the undissolved cured hot melt material. Gel% = 100% x (mass of undissolved cured hot melt material) / (starting sample mass).

[0075] If the UV cured sample is greater than 50% gel, it is considered to be suitably curable.

[0076] light transmittance ASTM D1003 is used to determine the %T of the cured composition using a 200 micrometer thick film of the cured composition and Haze-Guard Plus (BYK Gardner).

[0077] [Table 5] * The sample did not cure into a solid film so the %T could not be determined. (Aspect) (Aspect 1) 1. A hot melt composition comprising: (a)T Ar 80 to 99 parts by mass of at least one T type siloxane unit block containing a siloxane unit block and a D type siloxane unit block Ar -D-based resin-linear block copolymer, (i)T Ar The siloxane block has the structure (I):

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Claims

1. 1. A hot melt composition comprising: (a) T Ａｒ 80 to 99 parts by weight of at least one T type siloxane unit block and a D type siloxane unit block Ａｒ -D-based resin - a linear block copolymer, (i) T Ａｒ The type siloxane block has the structure (I): 【Chemistry 1】 (Wherein, Ar is C ６ ~C ２０ aryl, and R １ is C １ ~C ２０ Alkyl group and C ２ ~C ２０ alkenyl groups, with the proviso that T Ａｒ The average concentration of alkenyl groups R 1 in the D-type resin-linear block copolymer is in the range of 0.5 to 3.0 mol % relative to the total number of moles of silicon atoms, and R ２ , and R ３ are independently １ ~C ２０ hydrocarbyl, where each dashed line corresponds to a silicon group, a hydrogen group, or a valence bond to a hydrocarbyl group. and connected to the D-type siloxane unit block by a bond selected from those having the following structure: (ii) T for D-type siloxane unit block Ａｒ the molar ratio of the siloxane unit blocks is at least 2; (iii) The T Ar -D-based resin-linear block copolymer contains 8 to 35 mole percent Si—OR′ bonds relative to the number of moles of silicone atoms, where R′ is H or C １ ~C ８ is a hydrocarbyl, (iv) each D-type siloxane unit block contains an average of 20 to 200 D-type siloxane units; (v) Each T Ａｒ The siloxane unit block comprises at least one T type siloxane having a weight average molecular weight in the range of 500 to 10,000 grams / mole. Ａｒ -D-based resin - linear block copolymer, (b) 0.5 parts by weight to 20 parts by weight of a crosslinking agent containing an average of at least two (meth)acryloxy groups per molecule; (c) 0.1 parts by weight to 10 parts by weight of a radical photopolymerization initiator; (d) 0 to 2.0 parts by weight of an ultraviolet stabilizer; (e) 0 to 2.0 parts by weight of an adhesion promoter.

2. 2. The hot melt composition according to claim 1, wherein the T Ar -D-based resin-linear block copolymer does not contain a (meth)acryloxy group.

3. Ar is phenyl and R １ is vinyl, and R ２ and R ３ 10. The hot melt composition of claim 1, wherein is independently selected from a methyl group and an ethyl group.

4. 10. The hot melt composition of claim 1, wherein the hot melt composition is free of unbound Q-based resin particles.

5. The crosslinking agent comprises a compound having an average chemical structure (III) and a compound having an average chemical structure (IV): R’ ｍ CX （４－ｍ） (III) X-R"-X (IV) wherein each R' is independently selected at each occurrence from an alkyl group having 1 to 20 carbon atoms; and each X is independently -OC(O)CH=CH ２ Groups and —OC(O)C(CH ３ ) = CH ２ and R″ is an alkylene group having 1 to 20 carbon atoms. The hot melt composition according to claim 1, wherein the compound is one or more compounds selected from the group consisting of:

6. 10. A process comprising the steps of: heating the hot melt composition of claim 1 to soften the hot melt composition; and then coating the softened hot melt composition onto at least a portion of a substrate to form a coating of the hot melt composition on at least a portion of a surface of the substrate.

7. 7. The process of claim 6, wherein the process further comprises exposing the coating of the hot melt composition to ultraviolet light to cause crosslinking of the coating of the hot melt composition.

8. An article comprising the hot melt composition of any one of claims 1 to 6 coating at least a portion of a surface of a substrate.

9. The article of claim 8 , wherein the substrate comprises a light emitting diode.

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