Soft skin adhesive composition

Abstract

The invention provides a silica gel forming composition. The silica gel forming composition comprises alpha-dimethyl vinyl siloxy-co-dimethyl hydrogen group end capped polydimethylsiloxane, a silane coupling agent, a silane coupling agent and a curing agent, the invention relates to alpha-dimethyl vinyl siloxy-o-n-butyl terminated polydimethylsiloxane and a preparation method thereof. And a hydrosilylation catalyst. The cured gel has good adhesion to the skin, and no pain is generated when the gel is applied to the skin or removed from the skin.

Description

[0001] Cross - reference to related applications

[0002] This application claims the benefit of priority to co - pending U.S. Provisional Application No. 63 / 429,630, filed on December 2, 2022, the disclosure of which is hereby incorporated by reference in its entirety. Background Art

[0003] Silicone gels that adhere to the skin are well - known. Such gels have many applications, such as for wearable sensors (glucose, heart rate, pulse, ultraviolet radiation patches, electrocardiograms, etc.), wound care, scar and skin treatment, and drug delivery. Conventional compositions typically comprise a combination of vinyl - functionalized MQ resins (generally silicone copolymers formed from reactive or non - reactive trialkylsilyl (“M”) and tetraalkylsilyl (“Q”) structures), vinyl linear siloxanes, SiH chain extenders, and SiH cross - linkers. For example, WO 2005 / 102403; WO2008 / 057155; U.S. Patent No. 5,145,933; U.S. Patent No. 11,051,989; U.S. Patent No. 10,758,640; and U.S. Patent No. 10,662,330 describe various silicone skin - adhesive gel compositions. Although there are differences between these formulations, these gels all contain alkenyl - functionalized polysiloxanes and SiH - functionalized siloxanes, which vary in the number of SiH groups in any given molecule, the viscosity of the SiH - functionalized siloxane, the molar ratio of SiH to alkenyl functional groups, the arrangement of SiH groups on the siloxane molecule, the total SiH content in the gel formulation, the SiH content in the chain extender relative to the SiH content in the SiH - functionalized cross - linker or resin, and the SiH content in the cross - linker.

[0004] Specifically, conventional compositions comprise dimethylvinyl α,ω - terminated siloxane, an SiH siloxane cross - linker (having three or more SiH functional groups), and an α,ω - dimethylhydro - terminated chain - extender siloxane. Some known compositions also include vinyl - functionalized silicone resins. However, although these formulations have good adhesion to the skin, the overall strength of these adhesives still needs to be improved in order to handle larger or heavier skin - adhered objects. The gel adhesive must also be able to be removed from the skin by a peeling mechanism without causing pain. Therefore, a soft skin - adhesive composition with a higher adhesive strength than known compositions and capable of being removed / peeled from the skin painlessly would be desirable. Summary of the Invention

[0005] In one embodiment, aspects of the present disclosure relate to a silicone gel molding composition, the composition comprising:

[0006] (a) α - dimethylvinylsiloxy - ω - dimethylhydrogenterminated polydimethylsiloxane;

[0007] (b) A chain terminator comprising a component of formula (I) and / or formula (II):

[0008] and

[0009] (c) A hydrosilylation catalyst;

[0010] wherein R 1 is a terminal alkenyl group having 2 to about 22 carbon atoms, R 5 is a straight - chain or branched - chain alkyl group having 1 to about 8 carbon atoms, R 6 is hydrogen or a terminal alkenyl group having 2 to about 22 carbon atoms, each R 2 and R 3 is independently a straight - chain or branched - chain alkyl group having 1 to about 8 carbon atoms, and o is an integer such that the viscosity of the component of formula (II) is 2 to about 20,000 mPa - s.

[0011] In a second embodiment, aspects of the present disclosure relate to a silicone gel molding composition comprising:

[0012] (a) α - dimethylvinylsiloxy - ω - dimethylhydrogenterminated polydimethylsiloxane;

[0013] (b) A chain terminator comprising an α - olefin or a siloxane containing one vinyl or one terminal hydride group; and

[0014] (c) A hydrosilylation catalyst.

[0015] Preferred embodiments of the invention are specified in the dependent claims, and these preferred improvements can be implemented individually or in combination.

[0016] In summary, within the scope of the present invention, the following particularly preferred embodiments are proposed:

[0017] Embodiment 1: A silicone gel molding composition comprising:

[0018] (a) α - dimethylvinylsiloxy - ω - dimethylhydrogenterminated polydimethylsiloxane;

[0019] (b) A chain terminator comprising a component of formula (I) and / or formula (II):

[0020] and

[0021] (c) A hydrosilylation catalyst;

[0022] wherein R 1is a terminal alkenyl group having 2 to about 22 carbon atoms, R 5 is a straight-chain or branched-chain alkyl group having 1 to about 8 carbon atoms, R 6 is hydrogen or a terminal alkenyl group having 2 to about 22 carbon atoms, each R 2 and R 3 are independently a straight-chain or branched-chain alkyl group having 1 to about 8 carbon atoms, and o is an integer such that the viscosity of the component having formula (II) is about 2 to about 20,000 mPa-s.

[0023] Embodiment 2: The composition according to Embodiment 1, wherein component (a) has formula (III) and a viscosity of about 50 to about 1000 mPa-s

[0024]

[0025] Embodiment 3: The composition according to Embodiment 1 or 2, wherein component (b) is α-dimethylvinylsiloxy-ω-n-butyl-terminated polydimethylsiloxane.

[0026] Embodiment 4: The composition according to any one of Embodiments 1 to 3, wherein the composition comprises about 350 parts of component (a), about 0.5 to about 10 parts of component (b), and about 0.01 to about 1 part of component (c).

[0027] Embodiment 5: The composition according to any one of Embodiments 1 to 4, further comprising component (d) an α,ω-dimethylhydrogensiloxy-terminated polydimethylsiloxane chain extender.

[0028] Embodiment 6: The composition according to any one of Embodiments 1 to 5, wherein component (d) comprises a polymer having formula (IV) with a viscosity of about 2 to about 10,000 mPa-s,

[0029]

[0030] Embodiment 7: The composition according to any one of Embodiments 1 to 6, further comprising component (e) an α,ω-dimethylvinylsiloxy-terminated polydimethylsiloxane.

[0031] Embodiment 8: The composition according to any one of Embodiments 1 to 7, wherein component (e) comprises a polymer having formula (V) with a viscosity of about 2 to about 10,000 mPa-s,

[0032]

[0033] Embodiment 9: The composition according to any one of Embodiments 1 to 8, further comprising component (f) a linear vinyl siloxane.

[0034] Embodiment 10: The composition according to any one of Embodiments 1 to 9, wherein component (f) comprises a polymer having the formula (VI), with a viscosity of about 10 to about 10,000 Pa-s, wherein the molar percentage of a relative to b is about 45 to 97%, and the polymer having the formula (VI) has at least three silicon-bonded hydrogen atoms:

[0035]

[0036] Embodiment 11: The composition according to any one of Embodiments 1 to 10, further comprising component (g) at least one rate controller or rate inhibitor.

[0037] Embodiment 12: The composition according to any one of Embodiments 1 to 11, wherein component (g) is selected from the group consisting of: 2-methyl-3-butyn-2-ol, 1-ethynyl-cyclohexanol, diallyl maleate, triallyl isocyanurate, 1,3,5,7-tetravinyl-1,3,5,7-tetramethylcyclotetrasiloxane, and triphenyl phosphite.

[0038] Embodiment 13: A silicone gel obtained by heating and curing the composition according to any one of Embodiments 1 to 12.

[0039] Embodiment 14: A silicone gel molding composition, comprising:

[0040] (a) α-dimethylvinylsiloxy-ω-dimethylhydroxy-terminated polydimethylsiloxane;

[0041] (b) A chain terminator comprising an α-olefin or a siloxane containing one vinyl group or one terminal hydrogen group; and

[0042] (c) A hydrosilylation catalyst.

[0043] Embodiment 15: The composition according to Embodiment 14, wherein component (b) is a siloxane having the formula (VII),

[0044]

[0045] wherein n is an integer such that the viscosity of the compound having the formula (VII) is about 2 to about 20,000 mPa-s.

[0046] Embodiment 16: A silicone gel obtained by heating and curing the composition according to Embodiment 14 or 15. Description of the Drawings

[0047] The present invention will be better understood by reading the above summary and the following detailed description of the invention in conjunction with the accompanying drawings. To illustrate the present invention, the currently preferred embodiments are shown in the drawings. However, it should be understood that the present invention is not limited to the exact arrangements and instrumentalities shown in the figures. In the figures:

[0048] Figure 1 is a side elevational view of a test apparatus for testing a composition according to an embodiment of the present invention. Detailed Description

[0049] In a first aspect of the present invention, there is provided a silicone gel forming composition comprising:

[0050] (a) α-dimethylvinylsiloxy-ω-dimethylhydroxy-terminated polydimethylsiloxane;

[0051] (b) a chain terminator comprising a component having formula (I) and / or formula (II):

[0052] and

[0053] (c) a hydrosilylation catalyst;

[0054] wherein, R 1 is a terminal alkenyl group having 2 to about 22 carbon atoms, R 5 is a straight-chain or branched-chain alkyl group having 1 to about 8 carbon atoms, R 6 is hydrogen or a terminal alkenyl group having 2 to about 22 carbon atoms, each R 2 and R 3 is independently a straight-chain or branched-chain alkyl group having 1 to about 8 carbon atoms, and o is an integer such that the viscosity of the component having formula (II) is about 2 to about 20,000 mPa·s.

[0055] Component (a) is a monohydride / monovinyl siloxane (α-dimethylvinylsiloxy-ω-dimethylhydroxy-terminated polydimethylsiloxane), such as one having formula (III).

[0056]

[0057] The variable d, representing the number of repeating units, is an integer such that the viscosity of component (a) is between about 50 and about 1000 mPa·s.

[0058] Component (b) is a chain terminator or end capping agent that functions to terminate the polymer chain and render this end non-reactive, and it comprises a component having formula (I) and / or a component having formula (II). In formula (I), preferably, R 1The groups include -CH=CH2, -CH2CH=CH2, -CH2CH2CH=CH2, -CH2CH2CH2CH2CH=CH2, etc.; more preferably, R 1 is vinyl. More generally, R in formula (I) 1 is -(CH2) x CH=CH2, where x is an integer from 0 to about 20. Preferably, the R 5 group is a small straight-chain alkyl group such as methyl, ethyl, and propyl, and most preferably methyl.

[0059] In formula (II), R 2 and R 3 can be the same or different, and both are preferably small alkyl groups such as methyl, ethyl, propyl, or butyl. R 6 can be hydrogen or a terminal alkenyl group such as -CH=CH2, -CH2CH=CH2, -CH2CH2CH=CH2, -CH2CH2CH2CH2CH=CH2, etc. More generally, R in formula (II) 6 is -(CH2) x CH=CH2, where x is an integer from 0 to about 20. R 6 is preferably hydrogen or vinyl.

[0060] Preferably, component (b) is α-dimethylvinylsiloxy-ω-n-butyl-terminated polydimethylsiloxane, such as one having the following formula:

[0061]

[0062] Other preferred chain terminator components include those having the following structures:

[0063]

[0064] Component (c) is, for example, Karstedt catalyst (which is generally known in the art, as described in U.S. Patent No. 3,775,452), such as diluted to contain 3.0 to 3.5% Pt by weight in α,ω-dimethylvinylsiloxy-terminated PDMS. Other platinum hydrosilylation catalysts known or developed in the art, such as Spier catalyst, can also be used to catalyze the hydrosilylation reaction of SiH to vinyl.

[0065] The exemplary composition contains about 350 parts of component (a), about 0.5 to about 10 parts of component (b), preferably about 1 to about 5 parts of component (b), most preferably about 1.5 to about 3 parts of component (b), and a catalytic amount of component (c), such as about 0.01 to about 1 part, preferably about 0.1 to about 0.5 part.

[0066] The composition may also contain other optional components. For example, as an optional component (d) of the SiH siloxane chain extender, it can be an α,ω-dimethylhydroxysiloxy-terminated polydimethylsiloxane, such as the siloxane having the formula (IV). The variable y, representing the number of repeating units, is an integer such that the viscosity of component (d) is about 2 to about 10,000 mPa·s, preferably about 20 to about 80 mPa·s.

[0067]

[0068] The optional component (e) is an α,ω-dimethylethenylsiloxy-terminated polydimethylsiloxane, such as one having the formula (V):

[0069]

[0070] The variable m, representing the number of repeating units, is an integer such that the viscosity of component (e) is about 2 to about 10,000 mPa·s, preferably about 100 to about 3,000 mPa·s, more preferably about 500 to about 2,000 mPa·s.

[0071] In one embodiment of the present invention, if the composition contains both (d) and (e) simultaneously, the molar ratio of the silicon-bonded hydride in (d) to the vinyl group in (e) is preferably about 1.5 to about 0.7, more preferably about 1.1 to about 1.

[0072] The optional component (f) is a standard linear vinyl siloxane, such as an α,ω-dimethylhydroxysiloxy-terminated polydimethylsiloxane having the formula (VI).

[0073]

[0074] In the formula (VI), relative to "b", "a" is preferably about 45 to about 97 mole percent, there are at least three silicon-bonded hydrogen atoms in the molecule of (f), and "a" and "b" are optional integers such that the viscosity of (f) is about 10 to about 10,000 mPa·s, preferably about 10 to about 1000 mPa·s, more preferably about 10 to about 50 mPa·s.

[0075] The optional component (g) is a rate control agent / inhibitor, such as 2-methyl-3-butyn-2-ol, 1-ethynyl-cyclohexanol, diallyl maleate, triallyl isocyanurate, 1,3,5,7-tetravinyl-1,3,5,7-tetramethylcyclotetrasiloxane or triphenyl phosphite. However, other rate controllers and inhibitors commonly known in the art or developed for such applications also fall within the scope of the present invention. Incorporating one or more of these compounds as component (g) also falls within the scope of the present invention.

[0076] In an aspect of the present invention, an exemplary composition contains 350 parts of component (a), 0 to about 50 parts of component (d), 0 to about 50 parts of component (e), 0 to about 2 parts of component (f), and 0 to about 1.4 parts of component (g), it being understood that the molar ratio of hydride-bonded silicon to vinyl in (d) and (e) described previously is employed. Preferred compositions contain 0 to about 20 parts of (d), more preferably 0 to about 5 parts of (d), 0 to about 20 parts of (e), more preferably 0 to about 5 parts of (e), 0 to about 1.8 parts of (f), more preferably 0 to about 1.4 parts of (f), 0 to about 1 part of (g), more preferably 0 to about 0.5 parts of (g).

[0077] Component (a) is added to the formulation and made to react with itself in the presence of component (c) to provide, upon curing, a soft silicone having a low hardness, the silicone having a high tensile strength and a high tensile elongation. The compositions of the present invention have a very low viscosity, but due to the high chain length, they have the curing characteristics typically associated with high viscosity formulations. The addition of a small amount of component (b) renders the cured silicone highly extensible and strong, and also produces some non-reactive polymer long chains that increase the tack and adhesion when (a), (c), and (b) are heated and cured.

[0078] It has been found that the combination of a monohydride / monovinylsiloxane (a) with a siloxane chain terminator (b) forms a cured gel that has a better adhesion strength compared to adhesives of the prior art and does not cause pain when the adhesive is peeled from the skin. A formulation having a higher adhesion strength can also be made by using the monohydride / monovinylsiloxane in combination with an SiH siloxane chain extender (d) and a standard linear vinylsiloxane (f), wherein the molar amounts of SiH and vinyl are substantially equal.

[0079] Within the scope of the present invention, various alternative chain terminators are also included, such as α-olefins, in the form of component (b) where SiH replaces Si-vinyl, and siloxanes having only one vinyl or SiH group, such as compounds having formula (VII):

[0080]

[0081] In formula (VII), n is an integer such that its viscosity is about 2 to 20,000 mPa-s.

[0082] The soft skin adhesive composition according to the present invention can be formed (cured) into a gel by heating and curing at an elevated temperature. The appropriate heating time and duration can be determined by routine experimentation depending on the specific components, but can be at about 90 °C to 150 °C, preferably at about 100 °C, for about 1 hour to about 16 hours.

[0083] Due to its high adhesion strength and painless application and removal from the skin, the gel of the present invention has many applications, such as for applying wearable sensors (glucose, heart rate, pulse, ultraviolet sunlight exposure patches, electrocardiograms, etc. of different materials), wound care, scar and skin treatment, and drug delivery.

[0084] Unless otherwise indicated, any numerical values listed herein should be understood to be modified by the term "about" in all cases. Thus, the numerical values generally include ±10% of the stated value. For example, a temperature of "10 °C" or "about 10 °C" includes 9 °C and 11 °C and all temperatures in between. In addition, unless explicitly stated otherwise in the context, all numerical ranges expressed in this disclosure clearly include all possible sub-ranges, all individual numerical values within the range, including integers within the range, as well as fractions and decimals of the numerical values.

[0085] The present invention will now be described in conjunction with the following non-limiting examples.

[0086] Four cured gels (two inventive gels and one comparative gel) were obtained by preparing a gel-forming composition containing the following components, curing a 12 mm thick sample in an aluminum dish at 100 °C for 1 hour, and then cooling to room temperature. It has been found that it is difficult to test adhesives on the skin because the skin surface varies due to race, age, gender, and natural genetic variation. However, testing on PET can provide a surface energy similar to that of the skin.

[0087] The cured gels were analyzed by the loop adhesion test, using a PET film that was 203.2 mm long, 80.645 mm wide, and 0.0045 inches thick, and carried out on the cured gels at a pulling force of 508 mm / min, as shown in Figure 1. On a Stable Micro Systems TA-XT plus texture analyzer, the PET was formed into a loop with a length of 152.4 mm and clamped from one end to the other. The clamp on the texture analyzer was lowered until the PET film was mated with a cured silicone gel adhesive sample with a diameter of 161.3 mm x a thickness of 16.5 mm. At the 12.7 mm x 12.7 mm cross-section of the cured silicone gel adhesive, the middle part of the PET loop was pressed onto the cured silicone gel adhesive. With a little force from a finger, ensure that the adhesive completely wets the entire 12.7 x mm x 12.7 mm area (like applying an adhesive bandage). Then the clamp was pulled up at a speed of 508 mm / min, and the maximum force was measured.

[0088] Example 1: Invention Gel 1

[0089] 350 grams of (A) α-dimethylvinylsiloxy-ω-dimethylhydride-terminated polydimethylsiloxane with a viscosity of 150 to 350 cP and 2.92 grams of (B) α-dimethylvinylsiloxy-ω-n-butyl-terminated polydimethylsiloxane with a viscosity of 80 to 120 cP were combined in a 300GRAM MAX TALL Flacktek SpeedMixer cup and mixed manually with a spatula. Next, 0.035 g of Karstedt water silylation catalyst (C) (3.0 to 3.5% platinum content in α,ω-dimethylvinylsiloxy-terminated PDMS) was combined with (A) and (B) in the cup and mixed manually with a spatula. The mixture was then mixed on a Flacktek SpeedMixer DAC 600.2VAC-p centrifugal mixer at 800 rpm for 1 minute and 45 seconds at a vacuum setting of 35 rpm, followed by mixing at 2350 rpm for 15 seconds at the same vacuum setting.

[0090] The order in which the components are added is important. For example, component (A) can be combined with (C), mixed manually, then (B) can be added, mixed manually, and finally mixed on a mixer. However, (C) should not be combined with (B) and then added to (A). Any mixer that can fully mix the raw materials can be used. Typically, the mixture is placed in a vacuum state in the mixer to exclude air, but it can also be done after mixing. All mixing is carried out at room temperature and heating during the mixing process is not recommended. In fact, if mass production is to be carried out, the mixing temperature is preferably kept below 40°C. After curing at 100°C for 1 hour, the cured gel was subjected to the above-mentioned ring adhesion test analysis. It was found that the ring adhesion strength was 8.5kPa, the adhesion to the skin was good, and there was no pain or residue when applying and removing from the skin. Specifically, when the adhesive is applied to hairy skin, the hair will not be pulled off, and there is no pain when removing from hairy or hairless skin.

[0091] Example 2: Invention Gel 2

[0092] In a 300 GRAM MAX TALL Flacktek SpeedMixer cup, combine 350 g (A) of an α-dimethylvinylsiloxy-ω-dimethylhydrogensilyl-terminated polydimethylsiloxane with a viscosity of 150 to 350 cP and 2.92 g (B) of an α-dimethylvinylsiloxy-ω-n-butyl-terminated polydimethylsiloxane with a viscosity of 80 to 120 cP, and manually mix with a spatula. Next, combine 0.035 g of a Karstedt hydrosilylation catalyst (C) (platinum content of 3.0% to 3.5%, in α,ω-dimethylvinylsiloxy-terminated PDMS) with (A) and (B) in the cup, and manually mix with a spatula. Then combine 0.57 g of component (E) (α,ω-dimethylvinylsiloxy-terminated polydimethylsiloxane, viscosity of 1000 cP) and 0.66 g of component (D) (α,ω-dimethylhydrogensiloxy-terminated polydimethylsiloxane, viscosity of 50 cP) in the cup with the other components, and manually mix with a spatula. Then mix on a Flacktek SpeedMixer DAC 600.2VAC-p type centrifugal mixer at 800 rpm for 1 minute 45 seconds at a vacuum setting of 35 rpm, followed by mixing at 2350 rpm for 15 seconds at the same vacuum. The order listed above is the preferred order, and components (D) and (E) can also be added in either order relative to each other optionally.

[0093] After curing at 100 °C for 1 hour, the cured gel was analyzed by the loop adhesion test as described above. The loop adhesion strength was found to be 8.3 kPa, showing good adhesion to the skin, with no pain or residue during application and removal from the skin. Specifically, when applying the adhesive to hairy skin, the hair is not pulled out, and there is no pain during removal from hairy or hairless skin.

[0094] Example 3: Invention Gel 3

[0095] In a 300 GRAM MAX TALL Flacktek SpeedMixer cup, combine 90.13 g (A) of an α-dimethylvinylsiloxy-ω-dimethylhydrogendisiloxane with a viscosity of 150 to 350 cP and 9.57 g (B) of an α-dimethylvinylsiloxy-ω-n-butyl disiloxane with a viscosity of 80 to 120 cP, and manually mix with a spatula. Next, combine 0.06 g of a Karstedt's hydrosilylation catalyst (C) (platinum content 3.0% to 3.5%, in α,ω-dimethylvinylsiloxy-terminated PDMS) with (A) and (B) in the cup, and manually mix with a spatula. Then combine 6.43 g of component (E) (α,ω-dimethylvinylsiloxy-terminated polydimethylsiloxane, viscosity 1000 cP) and 3.44 g of component (D) (α,ω-dimethylhydrogensiloxy-terminated polydimethylsiloxane, viscosity 50 cP) in the cup with the other components, and manually mix with a spatula. Then mix on a Flacktek SpeedMixer DAC 600.2VAC-p type centrifugal mixer at 800 rpm for 1 minute 45 seconds at a vacuum setting of 35 rpm, followed by mixing at 2350 rpm for 15 seconds at the same vacuum. The order listed above is the preferred order, and components (D) and (E) can also be added in either order relative to each other, optionally.

[0096] After curing at 100 °C for 1 hour, the cured gel was analyzed by the loop adhesion test as described above. The loop adhesion strength was found to be 12.21 kPa, with good adhesion to the skin and no pain or residue upon application and removal from the skin. Specifically, when applying the adhesive to hairy skin, the hair is not pulled out, and there is no pain when removing the agent from hairy or hairless skin.

[0097] Example 4: Comparative Gel 1

[0098] In a 300 GRAM MAX TALL Flacktek SpeedMixer cup, combine 366 g of component (E) (α,ω-dimethylvinylsiloxy-terminated polydimethylsiloxane with a viscosity of approximately 1000 cP), 0.27 g of component (G) (2-methyl-3-butyn-2-ol), and 0.035 g of component (C) (Karstedt hydrosilylation catalyst). Then manually mix the ingredients with a spatula. Combine 31.63 g of component (D) (α,ω-dimethylhydrogensiloxy-terminated polydimethylsiloxane with a viscosity of 50 cP) and 2.65 g of component (F) (α,ω-trimethyl-terminated hydrogenated trimethyl / dimethylpolysiloxane copolymer with a viscosity of 25 to 35 cP) in the SpeedMixer cup with the aforementioned ingredients and manually mix with a spatula. Then mix on a Flacktek SpeedMixer DAC600.2VAC-p type centrifugal mixer at a vacuum setting of 35 rpm and a rotational speed of 800 rpm for 1 minute and 45 seconds, followed by mixing at a rotational speed of 2350 rpm for 15 seconds at the same vacuum. The order listed above is the preferred order, and components (D) and (E) can also be added in any order relative to each other optionally.

[0099] After curing at 100 °C for 1 hour, the cured gel was analyzed by the loop adhesion test as described above. The loop adhesion strength was found to be 6.2 kPa, with good adhesion to the skin and no pain or residue when applied and removed from the skin.

[0100] Those skilled in the art will appreciate that the above-described embodiments can be modified without departing from their broad inventive concept. Therefore, it is understood that the present invention is not limited to the specific embodiments disclosed, but is intended to cover modifications within the spirit and scope of the invention as defined by the appended claims.

Claims

1. A silicone gel forming composition, comprising: (a) α-dimethylvinylsiloxy-ω-dimethylhydrogenterminated polydimethylsiloxane; (b) A chain terminator comprising a component having formula (I) and / or formula (II); (c) A hydrosilylation catalyst; Among them, R 1 is a terminal alkenyl group having from 2 to about 22 carbon atoms, R 5 is a straight-chain or branched-chain alkyl group having from 1 to about 8 carbon atoms, R 6 is hydrogen or a terminal alkenyl group having from 2 to about 22 carbon atoms, each R 2 and R 3 is independently a straight-chain or branched-chain alkyl group having from 1 to about 8 carbon atoms, and o is an integer such that the viscosity of the component having formula (II) is from about 2 to about 20,000 mPa-s.

2. The composition according to claim 1, characterized in that, Component (a) has formula (III) and a viscosity of about 50 to about 1000 mPa-s, 3. The composition according to claim 1 or 2, characterized in that, Component (b) is α-dimethylvinylsiloxy-ω-n-butyl terminated polydimethylsiloxane.

4. The composition according to any one of claims 1 to 3, characterized in that, The composition comprises about 350 parts of component (a), about 0.5 to about 10 parts of component (b), and about 0.01 to about 1 part of component (c).

5. The composition according to any one of claims 1 to 4, characterized in that, Further comprising component (d) an α,ω-dimethylhydrogensiloxy terminated polydimethylsiloxane chain extender.

6. The composition according to any one of claims 1 to 5, characterized in that, Component (d) comprises a polymer having formula (IV) with a viscosity of about 2 to about 10,000 mPa-s, 7. The composition according to any one of claims 1 to 6, characterized in that, Further comprising component (e) α,ω-dimethylvinylsiloxy terminated polydimethylsiloxane.

8. The composition according to any one of claims 1 to 7, characterized in that, Component (e) comprises a polymer having formula (V) with a viscosity of about 2 to about 10,000 mPa-s, 9. The composition according to any one of claims 1 to 8, characterized in that, Further comprising component (f) linear vinylsiloxane.

10. The composition according to any one of claims 1 to 9, characterized in that, Component (f) comprises a polymer having formula (VI) and a viscosity of about 10 to about 10,000 Pa-s, wherein the molar percentage of a relative to b is about 45 to 97%, and the polymer having formula (VI) has at least three silicon-bonded hydrogen atoms 11. The composition according to any one of claims 1 to 10, characterized in that, Further comprising component (g) at least one rate controller or rate inhibitor.

12. The composition according to any one of claims 1 to 11, characterized in that, Component (g) is selected from the group consisting of: 2-methyl-3-butyn-2-ol, 1-ethynyl-cyclohexanol, diallyl maleate, triallyl isocyanurate, 1,3,5,7-tetravinyl-1,3,5,7-tetramethylcyclotetrasiloxane, and triphenyl phosphite.

13. A silicone gel obtained by heating and curing the composition according to any one of claims 1 to 12.

14. A silicone gel forming composition, comprising: (a) α-dimethylvinylsiloxy-ω-dimethylhydrogenterminated polydimethylsiloxane; (b) A chain terminator comprising an α-olefin or a siloxane containing one vinyl or one terminal hydrogen group; and (c) A hydrosilylation catalyst.

15. The composition according to claim 14, characterized in that, Component (b) is a siloxane having formula (VII), wherein n is an integer such that the viscosity of the compound having formula (VII) is about 2 to about 20,000 mPa-s.

16. A silicone gel obtained by heating and curing the composition according to claim 14 or 15.

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