Silicone composition

Abstract

The silicone composition of the present invention comprises: (a1) C2 to C 20 A first organopolysiloxane composed of the following units, in which an alkenyl group is bonded to both ends or at least one Si in the chain; (RSiO 1 / 2 ) a (R2SiO 2 / 2 ) b (RSiO 3 / 2 ) c (SiO 4 / 2 ) d (In the formula, a is in the range of 1 to 50, b is in the range of 100 to 500, c is in the range of 0 to 50, and d is in the range of 0 to 50.) (a2) C2 to C 20 The alkenyl group is bonded to at least one Si at both ends or in the chain, and SiO 4 / 2 and (b) a second organopolysiloxane containing at least one structural unit represented by the formula: 20 and organohydrogensiloxanes containing at least one aryl group of the formula:

Description

[Technical Field]

[0001] The present invention relates to silicone compositions, and more particularly to fast-curing silicone adhesive compositions that can be applied to plastic substrates. [Background technology]

[0002] Silicone adhesives have high stability as interlayer adhesives due to their flexible structure, which provides low shrinkage and stress relief, as well as the excellent heat and chemical resistance of silicone itself. These properties mean that silicone adhesives are used as adhesives in a variety of fields, including industrial, electrical and electronic, and automotive applications.

[0003] In recent years, the industrial, electrical and electronics, and automotive sectors have all seen progress in weight reduction and diversification of designs. As a result, lightweight, injection-moldable, high-performance engineering plastics such as polycarbonate (PC), polyethylene terephthalate (PET), and polymethyl methacrylate (PMMA) are being applied to a variety of designs, and their use is on the rise.

[0004] Conventional silicone adhesives lack functional groups capable of chemically bonding to the surfaces of such high-performance engineering plastics, and their adhesive strength is therefore limited, meaning their applications are limited. Furthermore, conventional thermosetting silicone adhesives run the risk of causing dimensional deformation of the plastic substrate due to the long curing time at high temperatures, limiting their applications. Summary of the Invention [Problem to be solved by the invention]

[0005] The present invention relates to a silicone composition that exhibits stable adhesive strength to high-performance engineering plastics such as polycarbonate (PC), polyethylene terephthalate (PET), and polymethyl methacrylate (PMMA).

[0006] The present invention further relates to a silicone composition that cures rapidly at low temperatures and that can minimize dimensional distortion of plastic substrates. [Means for solving the problem]

[0007] According to an embodiment of the present invention, the silicone composition comprises: (a1) A first organopolysiloxane composed of the following units, in which a C2-C20 alkenyl group is bonded to both ends or at least one Si atom in the chain: (R3SiO 1 / 2 ) a (R2SiO 2 / 2 ) b (RSiO 3 / 2 ) c (SiO 4 / 2 ) d (In the formula, a is in the range of 1 to 50, b is in the range of 100 to 500, c is in the range of 0 to 50, and d is in the range of 0 to 50.) (a2) C2~C 20 The alkenyl group is bonded to at least one Si at both ends or in the chain, and SiO 4 / 2 a second organopolysiloxane containing at least one structural unit represented by the formula: (b) Contains at least two SiH functional groups per molecule and has a C6-C 20 an organohydrogensiloxane containing at least one aryl group represented by the formula: Includes: [Effects of the Invention]

[0008] According to one or more embodiments of the present invention, the silicone composition according to the present invention exhibits similar adhesion to most substrates, including plastics, and is therefore applicable to bonding, sealing, and assembly, including bonding between dissimilar materials, such as between automobiles and electronic components.

[0009] Furthermore, because the silicone composition of the present invention has excellent heat resistance and stress relaxation properties, it can be used in outdoor display devices and in-vehicle display devices that are exposed to harsh conditions. Because it cures and bonds rapidly at low temperatures, it can also be used in areas where dimensional stability of the module is important, such as curved displays.

[0010] Furthermore, the silicone composition of the present invention can be used in a nozzle dispenser, and therefore can be applied regardless of the shape of the substrate or the application area. DETAILED DESCRIPTION OF THE INVENTION

[0011] The silicone composition according to an embodiment of the present invention comprises: (a1) C2~C 20 A first organopolysiloxane composed of the following units, in which an alkenyl group is bonded to both ends or at least one Si atom of the chain: (R3SiO 1 / 2 ) a (R2SiO 2 / 2 ) b (RSiO 3 / 2 ) c (SiO 4 / 2 ) d (In the formula, a is in the range of 1 to 50, b is in the range of 100 to 500, c is in the range of 0 to 50, and d is in the range of 0 to 50.) (a2) C2~C 20 The alkenyl group is bonded to at least one Si at both ends or in the chain, and SiO 4 / 2 a second organopolysiloxane containing at least one structural unit represented by the formula: (b) Contains at least two SiH functional groups per molecule and has a C6-C 20 an organohydrogensiloxane containing at least one aryl group represented by the formula: Includes:

[0012] Each component will be described in detail below.

[0013] 1. Component (a) Component (a) is an organopolysiloxane. The silicone composition according to an embodiment of the present invention contains, as component (a): (a1) C2~C 20 A first organopolysiloxane comprising the following units, each having an alkenyl group bonded to both ends or at least one Si in the chain: (R3SiO 1 / 2 ) a (R2SiO 2 / 2 ) b (RSiO 3 / 2 ) c (SiO 4 / 2 ) d (wherein a is in the range of 1 to 50, b is in the range of 100 to 500, c is in the range of 0 to 50, and d is in the range of 0 to 50), and (a2) C2~C 20 The alkenyl group is bonded to at least one Si at both ends or in the chain, and SiO 4 / 2 A second organopolysiloxane containing at least one structural unit represented by the formula: Contains two or more of the above.

[0014] The first organopolysiloxane (a1) and the second organopolysiloxane (a2) can each independently have a linear structure, a branched structure, a cyclic structure, or a linear structure with a partially branched or partially cyclic structure.

[0015] The first organopolysiloxane (a1) and the second organopolysiloxane (a2) each independently contain C2 to C 20 Alkenyl group, preferably C2-C 12 It may include alkenyl groups such as vinyl, propenyl, isopropenyl, butenyl, hexenyl, and octenyl groups.

[0016] The first organopolysiloxane (a1) and the second organopolysiloxane (a2) contain organo groups bonded to silicon (Si) atoms in addition to alkenyl groups bonded to silicon atoms. As used herein, an organo group can be a monovalent hydrocarbon group having 1 to 20, specifically 1 to 10, more specifically 1 to 8 carbon atoms, which can be substituted or unsubstituted. For example, the organo group can be a C1-C6 group such as methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, pentyl, neopentyl, hexyl, octyl, nonyl, and decyl. 20 or C6 to C6 alkyl groups such as phenyl, tolyl, xylyl, and naphthyl groups. 20 or C7-C, such as phenylethyl and phenylpropyl groups. 20 It may also be an aralkyl group.

[0017] The first organopolysiloxane (a1) and the second organopolysiloxane (a2) each have a weight-average molecular weight in the range of 1,000 to 150,000 g / mol, more preferably 10,000 to 50,000 g / mol, and preferably a viscosity at 25°C in the range of approximately 100 to 500,000 mPa s.

[0018] In the silicone composition of the present invention, the total content of the first organopolysiloxane (a1) and the second organopolysiloxane (a2) is preferably in the range of 10 to 80% (wt%), more preferably in the range of 30 to 55 wt%, based on the total amount of the silicone composition.

[0019] The first organopolysiloxane (a1) preferably has vinyl groups at both ends, and more preferably contains an MQ resin.

[0020] The second organopolysiloxane (a2) preferably has a vinyl group on at least one side of its chain, and more preferably contains an MQ resin.

[0021] 2. Ingredient (b) Component (b) contains at least two Si-H functional groups per molecule and at least one C-C 20 It is a type of crosslinking agent that is an organohydrogensiloxane containing aryl groups, and reacts with the alkenyl groups of component (a) to form a polymer matrix with a crosslinked structure.

[0022] Component (b) preferably contains hydrogen attached to a silicon atom in a side chain of the polymer chain, e.g., a Si-H group. Component (b) is preferably RSiO 1 / 2 , R2SiO 2 / 2 , RSiO 3 / 2 , and SiO 4 / 2 The organosiloxane structure may be a linear structure, a branched structure, a cyclic structure, or a linear structure having a partially branched or partially cyclic structure.

[0023] The component (b) has an organyl group of C1 to C 20 More specifically, the monovalent hydrocarbon group may be C1 to C 20 Alkyl groups and C7-C 20 It may also contain a hydrocarbon group selected from an aralkyl group.

[0024] The component (b) is basically at least one C6-C 20 Component (b) preferably contains at least one aryl group per molecule, and preferably contains two or more different MD resins.

[0025] In order to achieve rapid curing at low temperatures in the silicone composition of the present invention, the content of the organohydrosiloxane in component (b) is preferably such that the number of silicon-bonded hydrogen atoms in component (b) is 0.5 moles or more, more preferably in the range of 1.5 to 2 moles per mole of alkenyl groups in components (a1) and (a2).

[0026] 3. Ingredient (c) Component (c) is an adhesion promoter. The adhesion promoter applicable to the present invention is not particularly limited as long as it is generally known in the art, and may include, for example, silanes or siloxanes, specifically silanes or siloxanes containing acrylic or epoxy groups, preferably alkoxysilanes. Specific examples of adhesion promoters include, but are not limited to, methacryloyloxypropyltrimethoxysilane, methacryloyloxypropyltriethoxysilane, glycidyloxypropyltrimethoxysilane, glycidyloxypropyltriethoxysilane, tris(3-propyltrimethoxysilyl)isocyanurate, trimethoxysilylpropylsuccinic anhydride, allyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, (epoxycyclohexyl)ethyldimethoxysilane, (epoxycyclohexyl)ethyldiethoxysilane, and combinations thereof. Furthermore, the content of the adhesion promoter in the silicone composition of the present invention is not particularly limited. For example, it may be in the range of about 0.01 to 5% by weight, preferably about 0.05 to 3% by weight, and more preferably about 0.1 to 1% by weight, relative to the total amount of the silicone composition.

[0027] In addition to components (a), (b), and (c), the silicone composition according to the present invention may further comprise one or more components selected from, for example, (d) a coupling agent, (e) a platinum-based catalyst, and (f) a reaction inhibitor.

[0028] 4. Component (d) Component (d) is a coupling agent that assists in forming cohesive forces with the adherend.

[0029] The coupling agent of component (d) is, for example, C1 to C 30 Alkyl groups of C2 to C 30 Alkenyl groups, C2-C 30 Alkynyl groups, C1-C 30 Alkoxy group or C6-C 30The coupling agent may comprise an organic titanate or a derivative thereof containing at least one organyl group selected from aralkyl groups. The amount of the coupling agent may be in the range of 0.1 to 0.7 times, preferably 0.2 to 0.5 times, the weight of the adhesion promoter.

[0030] 5. Component (e) Component (e) is a hydrosilylation catalyst. This catalyst promotes the reaction between the aforementioned organopolysiloxane (a) and organohydrogensiloxane (b). The catalyst applicable to the present invention is not particularly limited as long as it is one used in hydrosilylation reactions in the art, and includes platinum-based catalysts, palladium-based catalysts, and rhodium-based catalysts. Among these, platinum or platinum compounds are preferred due to their excellent reactivity. Examples include platinum clusters, platinum black, platinum chloride, chloroplatinic acid and its salts, alcohol-modified chloroplatinic acid, chloroplatinic acid-olefin complexes, and platinum coordination compounds, each of which uses silica, carbon, or the like as a support.

[0031] In the silicone composition of the present invention, the content of the catalyst of component (e) is not particularly limited, but if the catalyst content is too low, the catalytic effect may not be obtained, and conversely, if the catalyst content is too high, the effect of accelerating the addition reaction may not be improved, which is therefore uneconomical. Furthermore, because the catalyst content affects the curing behavior, in order to achieve rapid curing at low temperatures, it is preferable to adjust the content of the catalyst of component (e) to about 0.1 to 1.0 wt.% of the total amount of the composition, specifically about 0.2 to 0.5 wt.%.

[0032] 6. Component (f) Component (f) is a reaction inhibitor for controlling the degree of activation. By applying the reaction inhibitor component (f), reaction stability at room temperature is ensured and the reaction is promoted at a specific temperature for a desired time.

[0033] The reaction inhibitor applicable to the present invention is not particularly limited as long as it is one used in hydrosilylation reactions in the relevant technical field, and may include, for example, materials such as divinyldisiloxane, divinylpolysiloxane, diethyl maleate, diethyl fumarate, methylbutynol (e.g., 2-methyl-3-butyn-2-ol), vinyl groups, maleic acid groups, fumaric acid groups, and alkynol groups. In particular, low-molecular-weight siloxanes containing alkenyl groups are most preferred for achieving rapid curing at low temperatures.

[0034] In the silicone composition of the present invention, the content of the reaction inhibitor is preferably in the range of about 0.1 to 1.0 wt %, and more preferably in the range of about 0.2 to 0.6 wt %, based on the total weight of the platinum catalyst.

[0035] 7. Other additives In addition to the above components (a) to (e), the silicone composition of the present invention may further contain additives generally known in the art, depending on the intended use and environment of the composition. Examples of such additives include, but are not limited to, dyes, pigments, flame retardants, anti-settling agents, dispersants, thickeners, leveling agents, thixotropic agents, etc.

[0036] Thixotropic adhesive compositions may optionally further contain one or more fillers selected from silica, alumina, quartz, boron, or zinc oxide.

[0037] The content of the additive is not particularly limited and may be within a conventional range known in the art, for example, in the range of about 0.001 to 10% by weight, specifically about 0.01 to 5% by weight, and more specifically about 0.1 to 3% by weight, relative to the total weight of the silicone composition.

[0038] The kinematic viscosity of the silicone composition according to the present invention is preferably in the range of 1,000 to 300,000 mPa·s, and more preferably 5,000 to 50,000 mPa·s, measured at 25°C and 10 to 25 rpm, so that it can be used with a variety of dispensers.

[0039] In order to maintain the shape after application, the viscosity is preferably in the range of 5,000 to 3,000,000 mPa·s, and more preferably 100,000 to 1,000,000 mPa·s, at a similar kinematic viscosity of 25° C. and 0.1 to 0.5 rpm.

[0040] The heat curing conditions for the silicone composition of the present invention are not particularly limited, but in order to minimize dimensional deformation of the plastic substrate, the heat curing temperature may be set to a range of 50 to 90°C, preferably about 60 to 80°C, and the heat curing time may be set to about 5 to 30 minutes, preferably about 10 to 15 minutes. As described above, the silicone composition of the present invention can be cured at a low temperature in a short time depending on the intended use. Therefore, it is preferable that the silicone composition of the present invention be cured rapidly at a low temperature.

[0041] The silicone composition of the present invention exhibits excellent adhesion to most substrates, including plastics, and is therefore applicable to adhesion, sealing, and assembly of automobiles and electronic components, including adhesion between different types of materials. Specifically, the composition is applicable to adhesion, sealing, and assembly of at least one of display devices, electronic components, solar cell modules, semiconductors, and automobile components.

[0042] The silicone composition of the present invention can be used to bond high performance engineering plastics such as polycarbonate (PC), polyethylene terephthalate (PET), and polymethyl methacrylate (PMMA).

[0043] In the case of a display device, it can be used, for example, as a housing or backlight unit for a liquid crystal display (LCD), a light emitting diode (LED) display, or an organic electroluminescent (EL) display.

[0044] Furthermore, the silicone composition of the present invention has excellent heat resistance and stress relaxation properties, making it particularly advantageous for outdoor display devices and vehicle-mounted display devices that are exposed to harsh conditions.

[0045] The silicone composition according to the present invention has the advantage of exhibiting rapid curing behavior and rapid bond formation speed, especially at low temperatures, and is therefore applicable to processes where module dimensional stability is important, such as curved displays.

[0046] Furthermore, the silicone composition of the present invention may have a viscosity that allows it to be applied with a nozzle dispenser, and therefore it can be applied without being significantly affected by the shape of the substrate or the area to which it is applied. [Example]

[0047] Hereinafter, the present invention will be described in detail through embodiments. However, the following embodiments are merely illustrative of the present invention, and the present invention is not limited to the following embodiments.

[0048] [Examples 1 to 6, Comparative Examples 1 to 3] Rapid-curing silicone compositions for bonding plastic substrates were prepared according to the examples and comparative examples by uniformly heating and mixing the components listed below in the composition ratios (parts by mass) shown in Table 1. In each structural formula, Me represents a methyl group and Vi represents a vinyl group.

[0049] [Table 1]

[0050] The following components were used as component (a):

[0051] a-1: (CH2=CHMe2SiO(SiMe2O)xSiMe2CH=CH2), Molecular weight 16500g / mol, average chain length 210

[0052] a-2: (CH2=CHMe2SiO(SiMe2O)xSiMe2CH=CH2), Molecular weight 36800g / mol, average chain length 441

[0053] a-3:M5M Vi 1Q4

[0054] a-4:M7M Vi 1Q 12

[0055] The following components were used as component (b):

[0056] b-1: Me3SiO(Me2SiO)x(MeHSiO)ySiMe3 (Average chain length, x+y=100)

[0057] b-2: Me3SiO(Me2SiO)x(MeHSiO)ySiMe3 (Average chain length, x+y=45)

[0058] b-3:MD Ph 40 -DH 20 -M

[0059] b-4:H-M2-D Ph 2-M2-H

[0060] The following components were used as component (c):

[0061] c-1: Glycidoxypropyltrimethoxysilane

[0062] c-2: Methacryloxypropyltrimethoxysilane

[0063] Divinyltetramethyldisiloxane platinum(0) was used as component (d).

[0064] Methylbutynol was used as component (e).

[0065] For the component (f), alumina with an average particle size (D50) of 1 μm was used.

[0066] The compositions of Examples 1 to 6 and Comparative Examples 1 to 3 were measured for viscosity, hardness, tensile adhesion, shear adhesion, etc., and the results are shown in Table 2 below.

[0067] [Table 2]

[0068] The viscosity was measured with a rheometer (Anton Paar, CP50-2, 25 / shear rate), and the hardness was measured using a Shore A rubber durometer.

[0069] The tensile adhesive strength was measured as follows. First, the silicone composition was bonded (e.g., laminated) to a thickness of 0.3 mm between polycarbonate substrates (50 mm wide x 100 mm long x 5 mm thick) and cured at 75°C for 15 minutes. This test piece was displaced in the tensile direction at a rate of 300 mm / min in accordance with ASTM D2651, and the maximum stress obtained was used to determine the "tensile adhesive strength (kgf / cm) of the rapid-curing silicone composition for bonding plastic substrates." 2 In this case, if a fracture mode (e.g., failure mode) remained on both substrates, it was judged as "cohesion," and if it remained on only one substrate, it was judged as "adhesion."

[0070] The shear adhesive strength was measured as follows. First, a 0.3 mm thick silicone composition was adhered (e.g., laminated) between polycarbonate substrates (25 mm wide x 100 mm long x 2 mm thick) and cured at 75°C for 15 minutes. This test piece was displaced in the shear direction at a rate of 300 mm / min in accordance with ASTM D-3163, and the "shear adhesive strength (kgf / cm) of the quick-drying silicone composition for bonding plastic substrates" was calculated from the maximum stress obtained. 2In this case, if a fracture mode (e.g., failure mode) remained on both substrates, it was judged as "cohesion," and if it remained on only one substrate, it was judged as "adhesion."

[0071] In Examples 1 to 6, when cured at 75°C for 15 minutes, all compositions cured (there were no uncured areas), and although some showed adhesive failure, the overall composition showed cohesive failure, indicating stable adhesion to polycarbonate, which is one of the substrates that is difficult to bond to.

[0072] In Comparative Examples 1 to 3, all of the compositions lacking some of the components (a) and (b) of the present invention exhibited an adhesive failure mode with polycarbonate, and were therefore evaluated as not being applicable to bonding plastic substrates.

Claims

1. (a1) C ２ ~C ２０ A first organopolysiloxane composed of the following units in which an alkenyl group is bonded to both ends or at least one Si atom of the chain: (R) ３ SiO １／２ ) ａ (R) ２ SiO ２／２ ) ｂ (RSiO ３／２ ) ｃ (SiO ４／２ ) ｄ (In the formula, a is in the range of 1 to 50, b is in the range of 100 to 500, c is in the range of 0 to 50, and d is in the range of 0 to 50.) (a2) C ２ ~C ２０ The alkenyl group is bonded to at least one Si at both ends or in the chain, and SiO ４／２ a second organopolysiloxane containing at least one structural unit represented by the formula: (b) contains at least two SiH functional groups per molecule and ６ ~C ２０ an organohydrogensiloxane containing at least one aryl group represented by the formula:

1. A silicone composition comprising:

2. 2. The silicone composition according to claim 1, wherein the weight average molecular weight of (a1) and / or (a2) is in the range of 1,000 to 150,000 g / mol.

3. 2. The silicone composition according to claim 1, wherein the total content of (a1) and / or (a2) is in the range of 10 to 80% by weight (wt %) based on the total amount of the silicone composition.

4. 2. The silicone composition of claim 1, wherein (a1) comprises an MQ resin containing vinyl groups at both ends, and (a2) comprises an MQ resin containing a vinyl group in at least one of the chains.

5. 2. The silicone composition of claim 1, wherein (b) contains one or more phenyl groups per molecule.

6. 10. The silicone composition of claim 1, wherein (b) comprises two or more different MD resins.

7. 2. The silicone composition according to claim 1, wherein the number of hydrogen atoms bonded to silicon in (b) is 0.5 moles or more per mole of alkenyl groups in both (a1) and (a2).

8. 10. The silicone composition of claim 1, further comprising (c) an adhesion promoter.

9. The silicone composition of claim 1 , wherein (c) is an alkoxysilane.

10. 10. The silicone composition according to claim 9, wherein the content of (c) is in the range of 0.01 to 5 wt % based on the total amount of the silicone composition.

11. 10. The silicone composition of claim 1, further comprising (d) a coupling agent.

12. The (d) is C １ ~C ３０ alkyl group of C ２ ~C ３０ an alkenyl group of C ２ ~C ３０ an alkynyl group of C １ ~C ３０ an alkoxy group of C ６ ~C ３０ 12. The silicone composition of claim 11, comprising an organic thionate or derivative thereof containing at least one organyl group selected from the group consisting of aralkyl groups of the formula:

13. 13. The silicone composition according to claim 12, wherein the content of (d) is in the range of 0.1 to 1.5 times the weight of the adhesion promoter.

14. 10. The silicone composition of claim 1, further comprising (e) a catalyst for hydrosilylation reactions.

15. 15. The silicone composition according to claim 14, wherein the component (e) is contained in an amount ranging from 0.01 to 5 wt % relative to the total amount of the silicone composition.

16. 10. The silicone composition of claim 1, further comprising (f) a reaction inhibitor.

17. 2. The silicone composition according to claim 1, wherein (f) is contained in an amount ranging from 0.1 to 10 wt % based on the total amount of (e).

18. 2. The silicone composition according to claim 1, which cures rapidly at low temperatures of 90°C or less within 30 minutes.

19. 2. The silicone composition of claim 1, having a viscosity in the range of 1,000 to 300,000 mPa·s at a kinematic viscosity of 10 to 25 rpm at 25°C, and a viscosity in the range of 5,000 to 3,000,000 mPa·s at a similar kinematic viscosity of 0.1 to 0.5 rpm at 25°C.

20. 10. The silicone composition of claim 1, which is applied to adhesion, sealing, or assembly in display devices, electronic components, solar cell modules, semiconductors, or automotive parts.

21. The silicone composition according to claim 1, which is used for bonding plastics.

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