Moisture-curing siloxane composition

Abstract

The present invention relates to a moisture-curable siloxane composition containing an organohydroxypolysiloxane, an organopolysiloxane, an alkoxy group-containing silane compound, a curing catalyst, and an adhesion promoter, wherein the organohydroxypolysiloxane contains an alkoxy group-containing repeating unit, the organopolysiloxane contains a first organopolysiloxane capped at both ends with alkoxy groups and a second organopolysiloxane capped at both ends with silanol groups, and the adhesion promoter contains a cyclosiloxane-based compound, and a cured product produced therefrom.

Description

Technical Field

[0001] [Cross - reference to Related Applications] This application claims the benefit of priority based on Korean Patent Application No. 10 - 2022 - 0089773, filed on July 20, 2022, and all the contents disclosed in the Korean patent application are incorporated herein by reference in their entirety.

[0002] The present invention relates to a moisture - curable siloxane composition that has excellent adhesion to a substrate, excellent workability because it has an appropriate finger - touch drying time and appropriate viscosity, excellent transparency and hardness of a formed coating film because of good storage stability, and little surface stickiness.

Background Art

[0003] An organopolysiloxane composition that cures at room temperature (25°C) without separate heating to produce a cured product can be configured as a one - component type because the curing reaction proceeds by contact with moisture in the air. As a result, the composition has the advantage of excellent workability because no separate pre - process is required. For this reason, one - component moisture - curable organopolysiloxane compositions are widely used as elastic adhesives and coating materials in the electrical and electronic industries, or as building sealing materials. Such one - component moisture - curable organopolysiloxane compositions can be classified into acetic acid type, oxime type, alcohol type, acetone type, etc., according to the type of by - products generated during curing. Among them, alcohol - type organopolysiloxane compositions are widely used because they do not corrode metallic substrates and have relatively little bad odor, and are particularly widely used in sensitive fields such as the electrical and electronic fields.

[0004] Specifically, Japanese Registered Patent No. 4045439 (Patent Document 1) discloses a room temperature curable organopolysiloxane composition containing an organopolysiloxane, a branched organopolysiloxane, a hydrolyzable group-containing silane compound bonded to a silicon atom, and a silane coupling agent. However, like in Patent Document 1, the transparency of a cured product produced by a conventional moisture curable organopolysiloxane composition containing a filler such as calcium carbonate is inhibited, resulting in poor visibility of the mounted circuit during coating on an electronic circuit board, causing inconvenience in the process, difficulty in grasping the failure site in case of circuit board failure, and insufficient adhesiveness to the substrate.

[0005] Therefore, there is a need for research and development of a moisture curable siloxane composition that has excellent adhesiveness to the substrate, has an appropriate touch-dry time and viscosity, is excellent in workability, has good storage stability, can be cured at room temperature, and does not contain a filler such as calcium carbonate, so that the produced coating film has excellent transparency.

Summary of the Invention

Problems to be Solved by the Invention

[0006] Therefore, the present invention aims to provide a moisture curable siloxane composition that has excellent adhesiveness to the substrate, has an appropriate touch-dry time and viscosity, is excellent in workability, has good storage stability, can be cured at room temperature, and does not contain a filler such as calcium carbonate, so that the produced coating film has excellent transparency.

Means for Solving the Problems

[0007] The present invention includes an organohydroxypolysiloxane, an organopolysiloxane, an alkoxy group-containing silane compound, a curing catalyst, and an adhesion promoter, the organohydroxypolysiloxane contains an alkoxy group-containing repeating unit, The organopolysiloxane includes a first organopolysiloxane capped at both ends with alkoxy groups and a second organopolysiloxane capped at both ends with silanol groups. The adhesion promoter provides a moisture-curable siloxane composition containing a cyclic siloxane compound.

[0008] The present invention also provides a cured product produced by curing the siloxane composition.

Advantages of the Invention

[0009] The moisture-curable siloxane composition according to the present invention has excellent adhesiveness to a substrate, an appropriate touch-dry time, appropriate viscosity, excellent workability, good storage stability, and can be cured at room temperature. Further, since the siloxane composition does not contain a filler such as calcium carbonate, the produced coating film is excellent in transparency and hardness, and has little surface tackiness, so it is very suitable as a material in sensitive fields such as the electric and electronic fields, particularly as adhesives, coating agents, potting agents, sealing agents, etc.

Modes for Carrying Out the Invention

[0010] Hereinafter, the present invention will be described in detail.

[0011] In this specification, “(meth)acryl” means “acryl” and / or “methacryl”, and “(meth)acrylate” means “acrylate” and / or “methacrylate”.

[0012] Also, the viscosity is measured by a conventional method known in the art, and may be, for example, a value measured at 25 °C using a Brookfield viscometer (Brookfield viscometer, LVDV) or a rheometer (Rheometer, MCR301, Anton Paar).

[0013] Moisture-curable siloxane composition The moisture-curing siloxane composition according to the present invention contains an organohydroxypolysiloxane, an organopolysiloxane, an alkoxy group-containing silane compound, a curing catalyst, and an adhesion promoter.

[0014] Organohydroxypolysiloxane The organohydroxypolysiloxane plays a role in forming the main skeleton of the siloxane composition and improving the hardness of the cured product.

[0015] The organohydroxypolysiloxane contains an alkoxy group-containing repeating unit. For example, the organohydroxypolysiloxane may be represented by the following Chemical Formula 1.

[0016] [Chemical Formula 1] [SiO 1 / 2 (R 1 )3] a [SiO 1 / 2 (OR 2 )3] b [SiO 2 / 2 (OR 3 )2] c [SiO 3 / 2 (OR 4 )] d [SiO 4 / 2 e (OH) f In Chemical Formula 1, R 1 to R 4 are each independently hydrogen, or a substituted or unsubstituted alkyl group, cycloalkyl group, alkenyl group, aryl group or aralkyl group, a is greater than 0.2 and less than 0.6, b + c + d is greater than 0.01 and less than 0.2, e is from 0.09 to 0.7, f is greater than 0 and less than 0.05, a + b + c + d + e + f is 1.

[0017] For example, R 1 to R 4 are each independently hydrogen, or a substituted or unsubstituted C1-15 an alkyl group, C 5-15 a cycloalkyl group, C 2-10 an alkenyl group, C 6-15 an aryl group or C 7-15 an aralkyl group, and at this time, the substitution may be substituted with a halogen atom or a cyanoalkyl group. Specifically, the above-mentioned R 1 to R 4 may each independently be hydrogen; an alkyl group such as a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, an octyl group, a decyl group, a dodecyl group; a cycloalkyl group such as a cyclohexyl group; an alkenyl group such as a vinyl group, an allyl group; an aryl group such as a phenyl group, a tolyl group, a xylyl group; an aralkyl group such as a benzyl group, a 2-phenylethyl group, a 2-phenylpropyl group, etc., and more specifically, may be hydrogen or a methyl group. At this time, the alkyl group and the alkenyl group may be linear or branched.

[0018] Specifically, a is from 0.3 to 0.55 or from 0.38 to 0.50, b + c + d is from 0.02 to 0.18 or from 0.05 to 0.15, e is from 0.2 to 0.6 or from 0.35 to 0.55, f is more than 0 and less than 0.04, or more than 0 and less than 0.02, and a + b + c + d + e + f may be 1.

[0019] If a is less than the above range, the mechanical properties of the cured product deteriorate and it is likely to lose its function as a coating agent. If it exceeds the above range, there may be a problem that it is difficult to realize the high hardness of the cured product. Also, if b + c + d is less than the above range, it may not be cured or it is difficult to obtain a high-hardness cured product. If it exceeds the above range, the curing rate becomes excessively slow or a cured product having high brittleness is formed, so it may be restricted in industrial use. Also, if e is less than the above range, the Q unit ([SiO 4 / 2If the content of the repeating unit) decreases, it is difficult to embody the improvement of the hardness of the cured product. If it exceeds the above range, the brittleness of the cured product increases, and there may be limitations in industrial use. Further, if f exceeds the above range, the stickiness of the coating surface of the cured product increases, and there may be inconveniences in the process such as dust sticking in the working environment.

[0020] The organohydroxypolysiloxane may have a hydroxy group content of more than 0 and 0.24 mmol / g or less, or more than 0 and 0.15 mmol / g or less. When the hydroxy group content of the organohydroxypolysiloxane exceeds the above range, the stickiness of the coating surface of the produced cured product increases, and there may be inconveniences in the process such as dust sticking in the working environment.

[0021] Further, the organohydroxypolysiloxane can be produced by first producing a branched organopolysiloxane having at least one hydroxydimethylsiloxy group (-Si(CH3)2OH), at least one trimethylsiloxy group ((-Si(CH3)3) and at least one Q unit (-SiO 4 / 2 ) and then reacting the branched organopolysiloxane with a tetrafunctional alkoxysilane. The method for producing the branched organopolysiloxane may use a method widely known in the art. For example, the methods disclosed in U.S. Registered Patent No. 2,676,182 and U.S. Registered Patent No. 2,814,601 can be used. Further, as described above, after producing the branched organopolysiloxane and reacting it with a tetrafunctional alkoxysilane to produce an organohydroxypolysiloxane, it is preferable because it is easy to adjust the content of each repeating unit to the target amount, but it is not limited thereto.

[0022] Organopolysiloxane The organopolysiloxane plays a role in adjusting the viscosity of the siloxane composition and imparting flexibility to the produced cured product.

[0023] The organopolysiloxane includes a first organopolysiloxane capped at both ends with alkoxy groups and a second organopolysiloxane capped at both ends with silanol groups. Since the siloxane composition includes two types of organopolysiloxanes with different terminal capping groups as described above, that is, when the first organopolysiloxane and the second organopolysiloxane are used in combination, even in the absence of moisture, the hydroxy groups bonded to silicon and the alkoxy groups bonded to silicon are cured by a condensation catalyst, so the siloxane composition has the advantage of being able to cure rapidly even at room temperature.

[0024] On the other hand, when only the first organopolysiloxane capped at both ends with alkoxy groups is used as the organopolysiloxane, there may occur a problem that cracks occur in the coating film manufactured under high-temperature conditions for reliability evaluation. Further, when only the second organopolysiloxane capped at both ends with silanol groups is used, since the hardness of the manufactured coating film is insufficient, there may occur a problem that the protection for materials in the electric and electronic fields such as PCB substrates is insufficient.

[0025] <The first organopolysiloxane> The first organopolysiloxane may be represented, for example, by the following Chemical Formula 2.

[0026] [Chemical Formula 2] [(R 5 O) (3-i) Si(R 6 ) i -Y 1 -[SiO 2 / 2 (R 7 )2] j -[Si(R 8 )2]-Y 2 -[(R 5 O) (3-i) Si(R 6 ) i In Chemical Formula 2, R 5 from R 8 ​is, independently of each other, a substituted or unsubstituted alkyl group, cycloalkyl group, alkenyl group, aryl group or aralkyl group, Y 1 and Y 2 are, independently of each other, an oxy group, or a substituted or unsubstituted alkylene group, i is 0 or 1, j is an integer from 1 to 300.

[0027] For example, R 5 to R 8 are, independently of each other, a substituted or unsubstituted C 1-15 alkyl group, C 5-15 cycloalkyl group, C 2-10 alkenyl group, C 6-15 aryl group or C 7-15 aralkyl group, where the substitution may be by a halogen atom or a cyanoalkyl group. Specifically, the said R 5 to R 8 may be, independently of each other, an alkyl group such as a methyl group, ethyl group, propyl group, butyl group, pentyl group, hexyl group, octyl group, decyl group, dodecyl group; a cycloalkyl group such as a cyclohexyl group; an alkenyl group such as a vinyl group, allyl group; an aryl group such as a phenyl group, tolyl group, xylyl group; an aralkyl group such as a benzyl group, 2-phenylethyl group, 2-phenylpropyl group, etc., and more specifically, may be a methyl group.

[0028] Y 1 and Y 2 are, independently of each other, for example, an oxy group; or a substituted or unsubstituted C 1-15 alkylene group. Specifically, Y 1 and Y 2 are, independently of each other, a C 1-10 alkylene group, or a C 1-7It may be an alkylene group, and the alkylene group may be linear or branched. At this time, the alkylene refers to a divalent radical that is branched, linear, or cyclic and is derived by removing one hydrogen atom from the carbon atom of an alkyl group. For example, the alkylene may be methylene (-CH2-), 1,1-ethylene (-CH(CH3)-), 1,2-ethylene (-CH2CH2-), 1,1-propylene (-CH(CH2CH3)-), 1,2-propylene (-CH2CH(CH3)-), 1,3-propylene (-CH2CH2CH2-), 1,4-butylene (-CH2CH2CH2CH2-), 2,4-butylene (-CH2(CH3)CH2CH2-), etc., but is not limited thereto.

[0029] At this time, the alkyl group and the alkenyl group may be linear or branched.

[0030] The first organopolysiloxane may have a viscosity at 25°C of 10 to 10,000 cP, or 40 to 6,000 cP. When the viscosity of the first organopolysiloxane at 25°C is less than the above range, the volatility is strong, which may cause danger in operation or problems such as weak mechanical properties of the cured product. When it exceeds the above range, the viscosity of the siloxane composition becomes high, and there may be limitations in use.

[0031] Specifically, the first organopolysiloxane can contain two or more types having different viscosities at 25°C. When using two or more types of the first organopolysiloxane having different viscosities in this way, the viscosity of the composition can be maintained low, and the produced coating film has the advantages of being flexible and not easily cracked.

[0032] For example, the first organopolysiloxane can include a first-1 organopolysiloxane having a viscosity at 25°C of 10 to 500 cP or 40 to 100 cP, and a first-2 organopolysiloxane having a viscosity of 1,000 to 10,000 cP or 4,000 to 6,000 cP. When the viscosity of the first-1 organopolysiloxane is less than the above range, there is a problem that the workability of the composition is insufficient due to strong volatility. When it exceeds the above range, there may be a problem that the viscosity of the siloxane composition containing it is high, resulting in restrictions on the working method. When the viscosity of the first-2 organopolysiloxane is less than the above range, there is a problem that the produced coating film is brittle and prone to cracking. When it exceeds the above range, there may be a problem that the viscosity of the composition is high, resulting in restrictions on the working method.

[0033] The first organopolysiloxane may be included in the siloxane composition at a content of 55 to 140 parts by weight or 60 to 110 parts by weight with respect to 100 parts by weight of the organohydroxypolysiloxane. When the content of the first organopolysiloxane is less than the above content, the viscosity of the siloxane composition is excessively high and operations such as spray coating are impossible. When it exceeds the above content, there may be a problem that the content of the organohydroxypolysiloxane in the composition is relatively low, resulting in insufficient hardness and strength of the produced cured product.

[0034] Specifically, with respect to 100 parts by weight of the organohydroxypolysiloxane, it can include 1 to 100 parts by weight, 4 to 80 parts by weight or 30 to 60 parts by weight of the first-1 organopolysiloxane, and 20 to 100 parts by weight, 20 to 70 parts by weight or 25 to 50 parts by weight of the first-2 organopolysiloxane. When the content of the first-1 organopolysiloxane is less than the above range, there is a problem that the viscosity of the composition is high and work is impossible. When it exceeds the above range, there may be a problem that the strength of the cured product is insufficient. When the content of the first-2 organopolysiloxane is less than the above range, there is a problem that the surface of the cured product is defective. When it exceeds the above range, there may be a problem that the strength of the cured product is insufficient.

[0035] <Second organopolysiloxane> The second organopolysiloxane may be represented by, for example, the following Chemical Formula 3.

[0036] [Chemical Formula 3] HO-[SiO2 / 2(R 10 )2] k -OH In Chemical Formula 3, R 10 is a substituted or unsubstituted alkyl group, cycloalkyl group, alkenyl group, aryl group or aralkyl group, and k is a number such that the viscosity of the second organopolysiloxane at 25°C is from 100 to 100,000 cP.

[0037] For example, R 10 is a substituted or unsubstituted C 1-15 alkyl group, C 5-15 cycloalkyl group, C 2-10 alkenyl group, C 6-15 aryl group or C 7-15 aralkyl group, and at this time, the substitution may be with a halogen atom or a cyanoalkyl group. Specifically, the R 10 may be an alkyl group such as a methyl group, ethyl group, propyl group, butyl group, pentyl group, hexyl group, octyl group, decyl group, dodecyl group; a cycloalkyl group such as a cyclohexyl group; an alkenyl group such as a vinyl group, allyl group; an aryl group such as a phenyl group, tolyl group, xylyl group; an aralkyl group such as a benzyl group, 2-phenylethyl group, 2-phenylpropyl group, etc., and more specifically, it may be a methyl group.

[0038] At this time, the alkyl group and the alkenyl group may be linear or branched.

[0039] The second organopolysiloxane may have a viscosity at 25°C of 100 to 100,000 cP, 500 to 10,000 cP, or 800 to 6,000 cP. When the viscosity of the second organopolysiloxane at 25°C is less than the above range, the curing rate of the siloxane composition is excessively fast and the workability is inhibited. When it exceeds the above range, the curing rate of the siloxane composition becomes excessively slow, and there may be a problem that productivity decreases or foreign substances flow into the cured product during curing.

[0040] Further, the second organopolysiloxane may be contained in the composition in an amount of 30 to 100 parts by weight, 35 to 95 parts by weight, or 50 to 70 parts by weight with respect to 100 parts by weight of the organohydroxypolysiloxane. When the content of the second organopolysiloxane is less than the above content, the adhesive strength becomes weak during curing. When it exceeds the above content, the surface of the cured product becomes sticky, and there is a high possibility that the surface of the cured product is contaminated during room temperature curing, resulting in inconvenience in use.

[0041] The organohydroxypolysiloxane, the first organopolysiloxane, and the second organopolysiloxane may be contained in the composition in a weight ratio of 1:0.55 to 1.4:0.3 to 1.0, or 1:0.6 to 1.1:0.5 to 0.7.

[0042] When the weight ratio of the first organopolysiloxane is less than the above range based on the content of the organohydroxypolysiloxane, the flexibility of the cured product after curing decreases, the brittleness becomes very weak, and the curing rate becomes very slow. When it exceeds the above range, there may be a problem that the content of the organohydroxypolysiloxane, which has a relatively branched structure, becomes low and the hardness of the cured product cannot reach the target hardness.

[0043] Further, when the weight ratio of the second organopolysiloxane is less than the above range based on the content of the organohydroxypolysiloxane, the adhesive strength of the cured product decreases. When it exceeds the above range, tackiness may occur on the surface of the cured product.

[0044] Alkoxy group-containing silane compound The alkoxy group-containing silane compound plays a role in adjusting the viscosity by regulating the touch-dry time of the siloxane composition.

[0045] In addition, the alkoxy group-containing silane compound can contain 1 to 10 silicon atoms in one molecule. For example, it can contain one or more selected from the group consisting of dimethyldimethoxysilane, diphenyldimethoxysilane, methylphenyldimethoxysilane, vinylmethyldimethoxysilane, dimethyldiethoxysilane, methyltrimethoxysilane, vinyltrimethoxysilane, phenyltrimethoxysilane, methyltriethoxysilane, vinyltriethoxysilane, phenyltriethoxysilane, tetramethoxysilane, tetraethoxysilane, tetra-n-propoxysilane and tetraisopropoxysilane. Specifically, the alkoxy group-containing silane compound may be a trialkoxy-containing silane such as methyltrimethoxysilane, vinyltrimethoxysilane, phenyltrimethoxysilane, methyltriethoxysilane, vinyltriethoxysilane, phenyltriethoxysilane, tetramethoxysilane, tetraethoxysilane.

[0046] The alkoxy group-containing silane compound may be contained in the composition in an amount of 10 to 85 parts by weight, 15 to 70 parts by weight, or 20 to 50 parts by weight based on 100 parts by weight of the organohydroxypolysiloxane. When the content of the alkoxy group-containing silane compound is less than the above range, the tack-free time of the composition may become excessively short and the viscosity of the composition may increase, resulting in operational difficulties. When it exceeds the above range, as the tack-free time of the composition becomes longer, the curing time may be long, causing problems in productivity or a decrease in the strength of the cured product.

[0047] Further, the siloxane composition can contain an alkoxy group-containing silane compound and a curing catalyst in a weight ratio of 3:1 to 40:1, 3:1 to 25:1, or 3:1 to 15:1. When the weight ratio of the alkoxy group-containing silane compound and the curing catalyst is less than the above range, that is, when a small amount of the alkoxy group-containing silane compound is contained based on the weight of the curing catalyst, problems such as low hardness of the cured product and discoloration of the cured product may occur. Further, when the weight ratio of the alkoxy group-containing silane compound and the curing catalyst exceeds the above range, that is, when an excessive amount of the alkoxy group-containing silane compound is contained based on the weight of the curing catalyst, the curing rate of the composition may be excessively slow, resulting in problems such as insufficient workability or non-curing.

[0048] Curing catalyst The curing catalyst plays a role in promoting the curing of the composition.

[0049] The curing catalyst is not particularly limited as long as it can be used in a moisture-curing type siloxane composition. For example, organotin compounds such as dibutyltin dimethoxide, dibutyltin diacetate, dibutyltin dioctate, dibutyltin dilaurate, dibutyltin bis(acetylacetonate), dibutyltin bis(benzyl maleate), dimethyltin dimethoxide, dimethyltin diacetate, dioctyltin dioctate, dioctyltin dilaurate, tin dioctate, tin dilaurate; organotitanium compounds such as tetraisopropyl titanate, tetra-n-butyl titanate, tetra-t-butyl titanate, tetra-n-propyl titanate, tetra-2-ethylhexyl titanate, diisopropyl di-t-butyl titanate, dimethoxy titanium bisacetylacetonate, diisopropoxy titanium bisethyl acetoacetate, di-t-butoxy titanium bisethyl acetoacetate, di-t-butoxy titanium bismethyl acetoacetate; amine compounds such as 3-aminopropyltrimethoxysilane, tetramethylguanidylpropyltrimethoxysilane; and the like can be mentioned.

[0050] Also, the curing catalyst may be contained in the composition in an amount of 1 to 10 parts by weight, 1 to 9 parts by weight, or 4 to 9 parts by weight based on 100 parts by weight of the organohydroxypolysiloxane. If the content of the curing catalyst is less than the above content, problems such as a slow curing rate or non-curing of the composition may occur. If the content exceeds the above content, problems such as an increase in viscosity during storage of the siloxane composition or, in severe cases, the composition being cured and unable to be used may occur.

[0051] Adhesion promoter The adhesion promoter plays a role in imparting adhesion to the substrate.

[0052] The adhesion promoter contains a cyclic siloxane-based compound. When the adhesion promoter contains a cyclic siloxane-based compound, it has the effect of reacting with the coated substrate to impart adhesion. For example, when the adhesion promoter contains a cyclosiloxyl group, the substrate reacts with the cyclosiloxyl group to improve the adhesion.

[0053] Also, examples of the adhesion promoter include cyclotrisiloxane (trimer), cyclotetrasiloxane (tetramer), cyclopentasiloxane (pentamer), etc. Specifically, it may be a compound represented by the following Chemical Formula 4.

[0054]

Chemical formula

[0055] For example, R 20from R 22 is, independently of each other, C 1-5 alkyl group or C 1-3 alkyl group, and R 23 and R 24 is, independently of each other, C 1-15 alkylene group, C 1-10 alkylene group or C 1-5 alkylene group, and R 25 and R 26 is, independently of each other, C 1-5 alkyl group or C 1-3 alkyl group may be.

[0056] For example, m + n may be from 2 to 6 or from 3 to 4, m may be from 1 to 4 or from 1 to 3, and n may be from 1 to 4 or from 1 to 2.

[0057] At this time, the alkylene group refers to a divalent radical which is branched, linear or cyclic and is derived by removing one hydrogen atom from the carbon atom of the alkyl group. For example, the alkylene group may include, but is not limited to, methylene (-CH2-), 1,1-ethylene (-CH(CH3)-), 1,2-ethylene (-CH2CH2-), 1,1-propylene (-CH(CH2CH3)-), 1,2-propylene (-CH2CH(CH3)-), 1,3-propylene (-CH2CH2CH2-), 1,4-butylene (-CH2CH2CH2CH2-), 2,4-butylene (-CH2(CH3)CH2CH2-), etc.

[0058] The alkylene group and the alkyl group may be linear or branched.

[0059] For example, the adhesion promoter can contain an ester group and an alkoxy group. Specifically, the adhesion promoter can contain an ester group and an alkoxy group having 1 to 5 carbon atoms or 1 to 3 carbon atoms. When the adhesion promoter contains an ester group and an alkoxy group, the ester group of the adhesion promoter reacts with the polar group of the base material, and the alkoxy group of the adhesion promoter reacts with the alkoxy or hydroxy group of organohydroxypolysiloxane or organopolysiloxane, thereby significantly improving the adhesion of the cured product produced.

[0060] The adhesion promoter can contain, for example, dimethylsiloxy units ((CH3)2SiO 2 / 2 ) and methylhydrogensiloxy units (CH3(H)SiO 2 / 2 ). Specifically, the adhesion promoter can contain dimethylsiloxy units ((CH3)2SiO 2 / 2 ) and methylhydrogensiloxy units (CH3(H)SiO 2 / 2 ), an ester group and a methoxy group. More specifically, the adhesion promoter may be a compound represented by the following Chemical Formula 5.

[0061] [Chemical Formula] Specifically, the adhesion promoter can contain α,2,4,6,6,8-hexamethylcyclotetrasiloxanepropanoic acid 3-(trimethoxysilyl)propyl ester.

[0062] In addition, the adhesion promoter can further contain an acrylic compound.

[0063] Specifically, the adhesion promoter can include a first adhesion promoter containing a cyclosiloxyl group and a second adhesion promoter containing an acrylic group. When the silicone composition includes the first adhesion promoter and the second adhesion promoter as adhesion promoters, there is an effect that the cyclosiloxyl group and the acrylic group, which are different functional groups, act to further strengthen the adhesive force.

[0064] The second adhesion promoter contains an acrylic group, and has an effect that the substrate and the acrylic group react to impart an adhesive force.

[0065] Further, the second adhesion promoter can include a (meth)acrylic group-containing silane compound. Specifically, the second adhesion promoter can include one or more selected from the group consisting of 3-(methacryloxypropyl)trimethoxysilane, 3-(methacryloxypropyl)triethoxysilane, 3-(acryloxypropyl)trimethoxysilane, and 3-(acryloxypropyl)triethoxysilane.

[0066] The first adhesion promoter and the second adhesion promoter can be included in a weight ratio of 1:0.3 to 1:40, or a weight ratio of 1:1 to 1:10. When the weight ratio of the first adhesion promoter and the second adhesion promoter is less than the above range, there is a problem that the adhesive force of the cured product is poor, and when it exceeds the above range, there may be a problem that the surface state of the cured product is poor.

[0067] The adhesion promoter may be included in the composition in an amount of 0.05 to 10 parts by weight, 0.5 to 7 parts by weight, or 1 to 4 parts by weight based on 100 parts by weight of the organohydroxypolysiloxane. When the content of the adhesion promoter is less than the above, the adhesive force of the composition is insufficient, and when it exceeds the above, turbidity may occur in the appearance of the cured product, making it difficult to apply as a transparent coating agent.

[0068] Specifically, the siloxane composition can contain 0.05 to 5 parts by weight or 0.1 to 4 parts by weight of a first adhesion promoter and 0 to 9 parts by weight or 0.2 to 7 parts by weight of a second adhesion promoter with respect to 100 parts by weight of the organohydroxypolysiloxane. When the content of the first adhesion promoter is less than the above, there is a problem that the cured product peels off from the substrate, and when it exceeds the above range, there may be a problem that the appearance after curing discolors.

[0069] Additive The moisture-curable siloxane composition can further contain additives commonly used in the art, such as antistatic agents, pigments, colorants, ultraviolet absorbers, fluorescent agents, heat-resistant agents, flame retardants, antioxidants, radical scavengers, light stabilizers, and the like.

[0070] The moisture-curable siloxane composition may have a viscosity at 25 °C of 1,500 cP or less, 50 to 1,500 cP, or 100 to 1,000 cP. Also, the moisture-curable siloxane composition may have a touch-dry time based on JIS K6249 of 15 minutes or less, 1 to 10 minutes, or 3 to 10 minutes.

[0071] Moreover, since the moisture-curable siloxane composition does not contain a filler, the produced coating film is excellent in transparency and hardness, and thus is suitable as a material for sensitive fields such as the electric and electronic fields. At this time, examples of the filler can include silica and the like.

[0072] The moisture-curable siloxane composition according to the present invention as described above is excellent in adhesion to a substrate, has an appropriate touch-dry time and an appropriate viscosity, so it has excellent workability and can be cured at room temperature.

[0073] Cured product The cured product according to the present invention is produced by curing the siloxane composition.

[0074] The cured product having an average thickness of 6 mm may have a hardness of 80 to 95 Shore A or 85 to 94 Shore A.

[0075] The cured product with an average thickness of 2 mm may have a shear strength of 2.5 MPa or more, 3.5 MPa or more, or 3.5 to 5.0 MPa.

[0076] The cured product as described above is excellent in transparency and hardness, has little surface stickiness, and is excellent in thermal shock resistance, so it is suitable as a material in sensitive fields such as the electric and electronic fields.

Examples

[0077] Hereinafter, the present invention will be described more specifically through examples. However, these examples are only for helping the understanding of the present invention, and in no way limit the scope of the present invention.

[0078] Production Example 1. Production of Organohydroxypolysiloxane 1-1: Production of Organohydroxypolysiloxane-1 (Synthesis Example 1) A branched organopolysiloxane capped with trimethylsiloxy groups (weight average molecular weight (Mw): 3,000 g / mol, silanol content: 2.05 wt%, manufacturer: CCS Silicone) and xylene were mixed at a weight ratio of 1:1 to produce a mixture. Then, 22 parts by weight of tetramethoxysilane was added to 100 parts by weight of the mixture and stirred for 10 minutes. 0.5 part by weight of sulfuric acid was added thereto as a catalyst and stirred at 25°C for 24 hours, and 10 parts by weight of NaHCO3 was added and stirred for 1 hour. Then, it was filtered through a filter to remove NaHCO3, and a transparent liquid (organohydroxypolysiloxane-1) having a viscosity of 8 cP and a solid content of 60 wt% at 25°C was obtained. Then, the pressure was reduced to 5 torr or less at 60°C to remove xylene.

[0079] Of the produced organohydroxypolysiloxane-1 29 As a result of Si-NMR analysis, SiO 1 / 2 (CH3)3 unit 43.89 mol%, SiO 1 / 2 (OCH3)3 unit 2.60 mol%, SiO 2 / 2(OCH3)2 unit: 2.91 mol%, SiO 3 / 2 (OCH3) unit: 3.82 mol%, SiO 3 / 2 (OH) unit: 0.08 mol%, and SiO 4 / 2 The unit was made up of 46.70 mol%. Also, the manufactured organohydroxypolysiloxane-1 had an OH group content of 0.011 mmol / g and an OCH3 group content of 2.35 mmol / g.

[0080] 1 - 2: Production of organohydroxypolysiloxane - 2 (Synthesis Example 2) A branched organopolysiloxane capped with trimethylsiloxy groups (weight - average molecular weight (Mw): 3,000 g / mol, silanol content: 2.05 wt%, manufacturer: CC Silicone) and xylene were mixed at a weight ratio of 1:1 to produce a mixture. Then, 33 parts by weight of tetramethoxysilane was added to 100 parts by weight of the mixture and stirred for 10 minutes. 0.5 part by weight of sulfuric acid was added as a catalyst and stirred at 25°C for 24 hours, and then 10 parts by weight of NaHCO3 was added and stirred for 1 hour. Then, it was filtered through a filter to remove NaHCO3, and a transparent liquid (organohydroxypolysiloxane - 2) with a viscosity of 8 cP at 25°C and a solid content of 60 wt% was obtained. Then, it was depressurized to 5 torr or less at 60°C to remove xylene.

[0081] The manufactured organohydroxypolysiloxane - 2's 29 As a result of Si - NMR analysis, SiO 1 / 2 (CH3)3 unit: 43.52 mol%, SiO 1 / 2 (OCH3)3 unit: 2.78 mol%, SiO 2 / 2 (OCH3)2 unit: 3.77 mol%, SiO 3 / 2 (OCH3) unit: 4.04 mol%, SiO 3 / 2 (OH) unit: 0.1 mol%, and SiO 4 / 2 The unit was made up of 45.79 mol%. Also, the manufactured organohydroxypolysiloxane - 2 had an OH group content of 0.11 mmol / g and an OCH3 group content of 2.66 mmol / g.

[0082] 1-3: Organohydroxypolysiloxane-3 Using organohydroxypolysiloxane-3 29 As a result of Si-NMR analysis, SiO 1 / 2 (CH3)3 units: 45.32 mol%, SiO 3 / 2 (OH) units: 4.38 mol%, and SiO 4 / 2 A polysiloxane composed of 50.3 mol% of units was used. Also, the content of OH groups in organohydroxypolysiloxane-3 was 0.11 mmol / g, and the content of OCH3 groups was 0 mmol / g.

[0083] Experimental Example 1 to 22. Production of moisture-curing siloxane composition The components were mixed in the composition as described in Tables 1 to 3 to produce a moisture-curing siloxane composition.

[0084]

Table 1

[0085]

Table 2

[0086]

Table 3

[0087] The manufacturers and product names, or substance names, etc. of each component used in the experimental examples are shown in Table 4, and the viscosity of the organopolysiloxane at 25°C is the value measured with a Brookfield viscometer (LVDV).

[0088]

Table 4

[0089] Test Example: Evaluation of properties The physical properties of the moisture-curing siloxane composition of the experimental examples and the cured sheets produced therefrom were measured by the following methods, and the results are shown in Table 5.

[0090] Specifically, the moisture-curing siloxane composition of the experimental example was cured at a temperature of 25°C and a relative humidity of 50% for 7 days in a mold capable of forming a 2-mm-thick sheet to produce a cured sheet.

[0091] (1) Viscosity Regarding the moisture-curing siloxane composition of the experimental example, the viscosity at 25°C with a shear force of 10 / s was measured using a rheometer (Rheometer, MCR301, Anton Paar).

[0092] (2) Touch-dry time The touch-dry time of the moisture-curing siloxane composition was measured based on JIS K6249. Specifically, after coating the composition on a PET film to a thickness of 60 μm, the time when the composition no longer sticks to the fingertip when lightly contacting the surface with the finger and then separating was measured.

[0093] (3) Hardness After stacking three cured sheets to a thickness of 6 mm, the hardness was measured with a Shore A hardness tester at 25°C.

[0094] (4) Shear strength The moisture-curing siloxane composition was applied to the end of an aluminum test piece with a width of 2.5 cm and a length of 6 cm to a width of 2.5 cm and a length of 0.5 cm, and another aluminum test piece was placed on it to a thickness of 2 mm. After curing at a temperature of 25°C and a relative humidity of 50% for 7 days, the shear strength was measured using a universal material testing machine (UTM) to confirm the adhesive strength.

[0095] (5) Surface stickiness The degree of stickiness when lightly touching and then separating the finger from the surface of the cured sheet was evaluated. At this time, when the stickiness was very low, it was relatively evaluated as 1, and when it was very high, it was relatively evaluated as 5.

[0096] (6) Thermal shock test The PCB substrate was coated with the moisture-curing siloxane composition and cured at a temperature of 25 °C and a relative humidity of 50% for 7 days. Then, using a thermal shock tester, it was left at -40 °C for 30 minutes and at 125 °C for 30 minutes, with one cycle being defined as such, and a total of 1,000 cycles were carried out. After that, it was stored at 25 °C for 1 day, and then the presence or absence of peeling and cracks in the coating layer (the cured product of the moisture-curing siloxane composition) was confirmed with a microscope. At this time, when peeling or cracks occurred in the coating layer, it was marked with 〇, and when no peeling or cracks occurred, it was marked with ×.

[0097] (7) High-temperature and high-humidity test The PCB substrate was coated with the moisture-curing siloxane composition and cured at a temperature of 25 °C and a relative humidity of 50% for 7 days. Then, using a high-temperature and high-humidity test machine, it was left at a temperature of 85 °C and a relative humidity of 85% for 1,000 hours, and then stored at 25 °C for 1 day. After that, the presence or absence of peeling and cracks in the coating layer (the cured product of the moisture-curing siloxane composition) was confirmed with a microscope, and when peeling and / or cracks occurred in the coating layer, it was marked with 〇, and when no peeling and / or cracks occurred, it was marked with ×.

[0098] (8) Storage stability After the moisture-curing organopolysiloxane composition was put into a glass vial, it was sealed and stored in an oven at 80 °C for 14 days, and the touch-dry time was measured in the same way as in item (2).

[0099]

Table 5(1)

Table 5(2)

[0100] As shown in Table 5, the moisture-curing siloxane compositions of Experimental Examples 1 to 10 had appropriate viscosities and touch-dry times, so they were excellent in workability and also excellent in storage stability. Further, the cured sheets produced from the compositions were excellent in mechanical properties because they were excellent in appearance, hardness, and shear strength, and were excellent in heat resistance, so they were excellent in the thermal shock test and the high-temperature and high-humidity test, and had little surface stickiness.

[0101] On the other hand, the cured sheets produced from Experimental Examples 11, 16, 17, and 20 containing only the third adhesion promoter containing an epoxy group had insufficient shear strength. In particular, the sheet of Experimental Example 11 containing organohydroxypolysiloxane-3 not containing an alkoxy group had very severe surface stickiness. Further, the sheet of Experimental Example 16 containing an excessive amount of the third adhesion promoter was opaque in appearance, insufficient in hardness, sticky on the surface, and insufficient in heat resistance. Furthermore, the sheet of Experimental Example 17 containing a small amount of the third adhesion promoter had insufficient heat resistance, so cracks occurred after the thermal shock test.

[0102] Also, Experimental Example 12 containing 3-glycidoxypropyltrimethoxysilane (third adhesion promoter) and 3-aminopropyltriethoxysilane (fourth adhesion promoter) as adhesion promoters and containing a small amount of a curing catalyst, and Experimental Example 14 containing a small amount of the second organopolysiloxane and an excessive amount of an alkoxy group-containing silane compound could not be cured at room temperature, so uncured occurred.

[0103] In Experimental Example 13 containing an excessive amount of a curing catalyst, yellowing occurred on the sheet.

[0104] Also, the composition of Experimental Example 15 containing a small amount of an alkoxy group-containing silane compound had insufficient workability because of high viscosity and long touch-dry time, poor storage stability, and the sheet produced therefrom had insufficient hardness and stickiness on the surface.

[0105] The composition of Experimental Example 18 containing an excessive amount of the second organopolysiloxane had insufficient storage stability, and the sheet produced therefrom had insufficient hardness.

[0106] In addition, in Experimental Example 19 containing a small amount of the second organopolysiloxane, cracks occurred after the thermal shock test and the high temperature and high humidity test because the heat resistance of the sheet was insufficient.

[0107] In Experimental Example 21 containing a small amount of the first organopolysiloxane and Experimental Example 22 not containing the second organopolysiloxane, the workability was extremely insufficient because the viscosity at 25°C was excessively high, and cracks occurred after the thermal shock test because the heat resistance of the sheet was insufficient. In particular, in Experimental Example 21, the storage stability of the composition was also poor, and surface stickiness also occurred on the sheet. In addition, in Experimental Example 22, the shear strength of the sheet was also insufficient.

Claims

1. A moisture-curing siloxane composition comprising an organohydroxypolysiloxane, an organopolysiloxane, an alkoxy group-containing silane compound, a curing catalyst, and an adhesion promoter, wherein the organohydroxypolysiloxane contains an alkoxy group-containing repeating unit, the organopolysiloxane includes a first organopolysiloxane capped at both ends with alkoxy groups and a second organopolysiloxane capped at both ends with silanol groups, and the adhesion promoter contains a cyclosiloxane-based compound.

2. The moisture-curing siloxane composition according to Claim 1, wherein the organohydroxypolysiloxane is represented by the following Chemical Formula 1: [Chemical Formula 1] [SiO １／２ (R １ ) ３ ａ [SiO １／２ (OR ２ ) ３ ｂ [SiO ２／２ (OR ３ ) ２ ｃ [SiO ３／２ (OR ４ )] ｄ [SiO ４／２ ｅ (OH) ｆ ​​​​ In Chemical Formula 1, R １ from R ４ each independently represents hydrogen, or a substituted or unsubstituted alkyl group, cycloalkyl group, alkenyl group, aryl group or aralkyl group, a is greater than 0.2 and less than 0.6, b + c + d is greater than 0.01 and less than 0.2, e is from 0.09 to 0.7, f is greater than 0 and less than 0.05, and a + b + c + d + e + f = 1.

3. The first organopolysiloxane is represented by the following Chemical Formula 2, and the moisture-curing siloxane composition according to Claim 1, wherein the first organopolysiloxane includes a first-1 organopolysiloxane having a viscosity at 25°C of 10 to 500 cP and a first-2 organopolysiloxane having a viscosity at 25°C of 1,000 to 10,000 cP. [Chemical Formula 2] [(R ５ O) （３－ｉ） Si(R ６ ) ｉ -Y １ -[SiO ２／２ (R ７ ) ２ ｊ -[Si(R ８ ) ２ -Y ２ -[ (R ５ O) （３－ｉ） Si(R ６ ) ｉ ​​ In Chemical Formula 2, R ５ from R ８ is each independently a substituted or unsubstituted alkyl group, cycloalkyl group, alkenyl group, aryl group or aralkyl group, Y １ and Y ２ are each independently an oxy group or a substituted or unsubstituted alkylene group, i is 0 or 1, and j is an integer from 1 to 300.

4. The moisture-curing siloxane composition according to Claim 1, wherein the second organopolysiloxane is represented by the following Chemical Formula 3: [Chemical Formula 3] HO-[SiO ２ / ２ (R １０ ) ２ ｋ -OH​ In Chemical Formula 3, R １０ is a substituted or unsubstituted alkyl group, cycloalkyl group, alkenyl group, aryl group or aralkyl group, k is a number such that the viscosity of the second organopolysiloxane at 25°C is from 100 to 100,000 cP.

5. The moisture-curing siloxane composition according to Claim 1, wherein the adhesion promoter is represented by the following Chemical Formula 4: 【Chemical 1】 In Chemical Formula 4, R ２０ from R ２２ to R ２５ and R ２６ are each independently a substituted or unsubstituted alkyl group, R ２３ and R ２４ are each independently a substituted or unsubstituted alkylene group, m, n, and x are each independently from 1 to 3.

6. The moisture-curing siloxane composition according to Claim 5, wherein the adhesion promoter includes a first adhesion promoter containing a cycloxysilyl group and a second adhesion promoter containing an acrylic group, and the first adhesion promoter and the second adhesion promoter are included in a weight ratio of 1:0.3 to 1:

40.

7. The moisture-curing type siloxane composition according to claim 1, comprising 100 parts by weight of an organohydroxypolysiloxane, 55 to 140 parts by weight of a first organopolysiloxane, 30 to 100 parts by weight of a second organopolysiloxane, 10 to 85 parts by weight of an alkoxy group-containing silane compound, 1 to 10 parts by weight of a curing catalyst, and 0.05 to 10 parts by weight of an adhesion promoter.

8. A cured product produced by curing the siloxane composition according to any one of claims 1 to 7.

Images