WO2007070269A1

WO2007070269A1 - Release agent composition for skin adhesives

Info

Publication number: WO2007070269A1
Application number: PCT/US2006/046091
Authority: WO
Inventors: Shunsuke Takaki
Original assignee: 3M Innovative Properties Company
Priority date: 2005-12-09
Filing date: 2006-12-08
Publication date: 2007-06-21
Also published as: JP5005916B2; JP2007159604A

Abstract

A release agent composition for skin adhesives in provided, comprising 85-99.8 wt% of a methylsiloxane solvent with a boiling point of at least 95°C and below 170°C, 0.1-5 wt% of an oil-compatible and pressure-sensitive adhesive-dissolving oil with a boiling point of at least 1700C, and 0.1-10 wt% of a nonionic surfactant.

Description

RELEASE AGENT COMPOSITION FOR SKIN ADHESIVES

TECHNICAL FIELD OF THE INVENTION

The present invention relates to a release agent composition for skin adhesives. More specifically, the invention relates to a release agent for surgical tapes, dressing films and medical devices such as bioelectrodes, counter electrode plates and other medical sensors which utilize them, as well as to products comprising the release agent.

BACKGROUND ART Pressure-sensitive adhesive-coated articles used on skin, such as surgical tapes and dressing films, must exhibit sufficient adhesive strength during the time in which they are attached to the skin. However, surgical tapes and the like with powerful adhesive strength are problematic in that they may damage or irritate the skin when peeled. It has therefore been desired to achieve easier release from skin without causing damage or irritation to the skin during peeling after use, while still maintaining adequate adhesive strength during use. Release agents are known which can reduce adhesive strength during peeling of the adhesive-coated articles, and several such release agents are currently proposed for medical purposes.

Japanese Unexamined Patent Publication SHO No. 63-38370 discloses a method of coating a volatile methylsiloxane solvent onto a pressure-sensitive adhesive on skin to remove the adhesive from the skin. Hexamethyldisiloxane (HMDS) is mentioned as a volatile methylsiloxane. However, because low-molecular-weight methylsiloxanes such as hexamethyldisiloxane (HMDS) are extremely volatile, they evaporate rapidly and lead to dryness before adhesive-coated articles such as surgical tapes are completely released, such that the peel strength (the force necessary for release) increases during peeling, often resulting in residual paste or skin injury. The releasing effect of volatile methylsiloxanes depends on the type of adhesive used in the surgical tape or dressing film, and the release effect can be insufficient for acrylic- based adhesives. Japanese Patent Publication No. 3510910 describes a pressure-sensitive adhesive tape release agent composition comprising an alcohol with a boiling point of no higher than 90⁰C such as ethanol or isopropyl alcohol, an organic solvent such as acetone, and a fatty acid ester of the formula RCOOR' (where either or both R and R' are Cl 1-16 and the total number of carbon atoms in both alkyl groups is no greater than 24). The fatty acid ester prevents drying of the skin in order to maintain a moist state.

However, the alcohol, such as ethanol or isopropyl alcohol, and the acetone tend to irritate injured skin. A surgical tape or dressing film is usually applied around skin or membranes which have been damaged by injury, wounding or inflammation.

In addition, several companies provide release agent napkins employing the main component of orange oil, i.e., D-limonene (l-methyl-4-isopropenyl-l- cyclohexene), or mineral oils and other additives. D-limonene (l-methyl-4- isopropenyl-1-cyclohexene) is a powerful dissolver of pressure-sensitive adhesives. Such products are therefore suited for transfer adhesives used in artificial anus appliances. However, for articles comprising adhesives coated on base films, such as surgical tapes, the adhesive layer dissolves and is released from the base film, being completely transferred to the skin, and the transferred adhesive adheres firmly to the finger of the user. Moreover, large amounts of D-limonene produce a very strong odor.

It is desirable to provide a release agent composition which allows pressure- sensitive adhesive-coated articles for skin, such as surgical tapes and dressing films attached to the skin, to be released with low peeling force without injuring or irritating the skin. It is also desirable to provide a release agent composition which facilitates release of surgical tapes and dressing films without excessive dissolution of the pressure-sensitive adhesive layer of the adhesive-coated article and without leaving a residue of the adhesive on the skin.

SUMMARY OF THE INVENTION

According to one mode of the invention, there is provided a release agent composition for skin adhesives, comprising 85-99.8 wt% of a methylsiloxane solvent with a boiling point of at least 95°C and below 170⁰C, 0.1-5 wt% of an oil-compatible and pressure-sensitive adhesive-dissolving oil with a boiling point of at least 170⁰C, and 0.1-10 wt% of a nonionic surfactant.

Throughout the present specification, the methylsiloxane solvent with a boiling point of below 170⁰C will be referred to as "volatile methylsiloxane solvent", and the oil with a boiling point of at least 170⁰C will be referred to as "low-volatile oil" or "non-volatile oil". The release agent composition of the invention has the advantages of low irritation to injured skin, limited force required for release, poor readhesion and low odor. The release agent composition of the invention also has suitable dissolving power for pressure-sensitive adhesives, and therefore leaves no paste residue on the skin and allows release of the surgical tape or dressing film itself. Moreover, the release agent composition of the invention exhibits a nonselective, adequate release effect for most types of pressure-sensitive adhesives such as acrylic-based adhesives, synthetic rubber-based adhesives and other adhesives. Consequently, products comprising the release agent composition of the invention can be widely used not only for surgical tapes and dressing films, but also transfer adhesives used in artificial anus devices (ostomy devices), medical devices such as bioelectrodes and counter electrode plates, as well as other medical devices which employ adhesives.

The release agent composition of the invention comprises a volatile methylsiloxane solvent with a boiling point of at least 95°C and below 170° C, a low- volatile oil-compatible and pressure-sensitive adhesive-dissolving oil with a boiling point of at least 170°C, and a nonionic surfactant. The main component of the release agent composition of the invention is the methylsiloxane solvent with a boiling point of at least 95°C and below 170⁰C. This type of solvent produces no irritation on injured skin and is therefore suitable as the main solvent for the release agent composition.

The methylsiloxane solvent is preferably selected from among hexamethyidisiloxane (HMDS), octamethyltrisiloxane (OMTS), hexamethylcyclotrisiloxane (HMCTS) and mixtures thereof, with hexamethyidisiloxane (HMDS) being most suitable. These methylsiloxane solvents are commercially available from, for example, Shinetsu Chemical Industries Co., Ltd. (Japan), Dow Corning, and other silicone producers. The volatile methylsiloxane solvent is used at 85-99.8 wt% based on the weight of the release agent composition of the invention.

When a low molecular methylsiloxane such as hexamethyidisiloxane (HMDS) is used alone as the release agent the pressure-sensitive adhesive will dissolve, but because of its extremely high volatility the HMDS dries rapidly before the adhesive- coated article, such as surgical tape, is completely peeled off, leading to readhesion of the adhesive-coated article. Consequently, problems of increased peel strength, i.e. increased force necessary for release during peeling, as well as paste residue and skin injury have occurred. According to the invention, a low-volatile oil-compatible and pressure-sensitive adhesive-dissolving oil with a boiling point of at least 170⁰C is added in a small amount in order to prevent drying of the release agent composition and eliminate the problems of increasing peel strength, paste residue and skin injury.

The low-volatile oil-compatible and pressure-sensitive adhesive-dissolving oil functions to aid the volatile methylsiloxane solvent, itself also softening and dissolving the adhesive. Such a low-volatile oil is included at 0.1-5 wt% based on the weight of the release agent composition of the invention. It is added in such a small amount because if the low-volatile oil exceeds this range the skin will tend to become sticky and manageability will be more difficult. Addition of the low- volatile oil provides a thin layer of the low- volatile oil to remain at the interface between the adhesive and the skin even after the methylsiloxane solvent as the major component of the release agent composition has evaporated off, thus keeping the adhesive in a soft condition and preventing readhesion of the adhesive.

Low-volatile oils which are oil-compatible and pressure-sensitive adhesive- dissolving include terpenes, aliphatic compounds, fatty acid esters and certain fatty acids. Among these, terpenes and aliphatic compounds exhibit effective softening and dissolving effects on adhesives. Terpenes include orange oils and turpentine oils, but the most suitable low- volatile terpene from the standpoint of safety, including skin irritation, is D-limonene, which is the major component of orange oil. A small amount of D-limonene (l-methyl-4-isopropenyl-l-cyclohexene) is preferably added to a methylsiloxane solvent, especially hexamethyldisiloxane (HMDS). D-limonene is a natural detergent extracted from citrus fruits such as oranges. D-limonene is commercially available, for example, from Yasuhara Chemical Co. (Japan) or Florida Chemical Co. (USA). D-limonene exhibits strong dissolving power for pressure- sensitive adhesives and a strong odor. Thus, when D-limonene is added in a large amount to a methylsiloxane solvent, the release agent composition thoroughly dissolves the adhesive itself, causing the adhesive layer of the surgical tape to peel from the base film and be completely transferred to the skin, such that a paste residue is left on the skin. While it is sufficient to reduce the peel strength, a suitable amount to prevent excessive dissolution of the adhesive itself is at least 0.1 wt%, more preferably 1 wt%, based on the weight of the release agent composition. Preferably the low-volatile oil is added at no more than 5 wt%, and more preferably no more than 4.5 wt%. Addition at greater than 5 wt% may lead to several difficulties such as paste residue and strong odor, which is inconvenient for handling of such products by patients, doctors, nurses and caregivers. When D-limonene is used as the low-volatile oil, the D-limonene will stably dissolve at room temperature in the release agent composition of the invention, but will tend to separate from the methylsiloxane solvent at temperatures of 50⁰C and above.

Aliphatic compounds are additional suitable examples for the oil-compatible and pressure-sensitive adhesive-dissolving oil. Vegetable fats are preferred as aliphatic compounds, and those selected from among fatty acid triglycerides are effective softening and dissolving adhesives, and they remain stable even at 50⁰C when added to methylsiloxane solvents. Examples of fatty acid triglycerides are effective softening and dissolving adhesives, and are biologically safe, include tricaprylin (tiϊcaprylic acid glycerin ester), marketed under the trade name KOKONADO by Kao Corp. (Japan), tri(caprylic acid/capric acid) glycerin ester and tri(caprylic acid/capric acid/lauric acid) glycerin ester. For example, the most suitable fatty acid triglyceride for low-volatile oils is the tricaprylin marketed under the trade name KOKONADO RK by Kao Corp.

(Japan). The appropriate range of addition is 0.1-5 wt%, with the most appropriate range being 1-4.5 wt%. Addition in an amount exceeding 5 wt% may lead to several difficulties such as paste residue and strong stickiness on the skin. Because such substances are odorless, the products containing them are convenient for handling by users including patients, doctors, nurses and caregivers.

Low- volatile methylsiloxanes with boiling points of at least 170⁰C, such as octamethylcyclotetrasiloxane (OMCTS) and decamethylcyclopentasiloxane (DMCS), are not suitable as low-volatile oil-compatible and pressure-sensitive adhesive- dissolving oils to be used in the compositions described herein. While their compatibility with volatile methylsiloxanes is acceptable, they have low adhesive dissolving properties and therefore do not improve the peel strength, and in particular, they do not exhibit adequate performance for certain types of acrylic-based adhesives.

In addition to the methylsiloxane solvent and the low- volatile oil-compatible and pressure-sensitive adhesive-dissolving oil, the release agent composition of the invention also comprises at least 0.1 wt% of a nonionic surfactant, based on the weight of the release agent composition. Addition of the low- volatile oil reduces the peel strength for many adhesives during peeling. Addition of the nonionic surfactants increases the number of adhesives and/or optimizes the release agent composition to allow adequate control of the dryness of the methylsiloxane solvent, and especially hexamethyldisiloxane (HMDS), and prevent readhesion. By adding a nonionic surfactant to the release agent composition, it is possible to delay the drying speed of the release agent composition to prevent readhesion. Without becoming restricted to any particular theory, it is believed that when the release agent composition of the invention is coated on an adhesive on the skin, a releasable barrier layer containing the low- volatile oil rapidly forms between the adhesive and the skin. Presumably, addition of a nonionic surfactant improves the wettability of the release agent composition for the skin and adhesive surfaces, while also allowing a releasable barrier layer comprising the low- volatile oil and the surfactant to rapidly form between the adhesive and skin. This releasable barrier layer delays drying of the methylsiloxane solvent, particularly hexamethyldisiloxane (HMDS), and inhibits readhesion of the adhesive and skin. Suitable nonionic surfactants include sorbitan ester surfactants (Span series by ICI Co.), polyoxyethylene sorbitan ester surfactants (Tween series by ICI Co.), polyethoxylated alkylphenols (TritonX35, X102, etc.), and polyethyleneglycol fatty acid monoesters (polyethyleneglycol 400 monolaurate, polyethyleneglycol 400 monooleate, etc.). In preferred embodiments, the nonionic surfactant is present in an amount of at least 0.1 wt%, and more preferably, at least 0.5 wt%. In a preferred embodiment, the nonionic surfactant is present in an amount of no more than 5 wt%, and more preferably, no more than 10 wt%. At amounts exceeding 10 wt%, the nonionic surfactant may affect the biocompatibility of the release agent composition. Among these nonionic surfactants, addition of highly hydrophilic polyoxyethylene sorbitan ester yields an opaque liquid mixture and the surfactant tends to separate after long periods of time. It is therefore necessary to shake the mixture before use. The releasable barrier layer comprising the low-volatile oil and the polyoxyethylene sorbitan ester has high affinity for hydrophilic surfaces, and therefore forms primarily on the skin surface and easily remains on the skin.

When the nonionic surfactant added is one of certain types of sorbitan esters with high hydrophobicity, the mixture forms a transparent solution and the surfactant does not separate after long periods. Since the barrier layer comprising the low- volatile oil and sorbitan ester will have strong affinity for hydrophobic surfaces, it forms mainly on the adhesive surface and easily remains on the adhesive surface. Non-restrictive examples of sorbitan esters include Span 20, Span 40, Span 60, Span 65, Span 80 and Span 85, which are commercially available from ICI Co. (USA). Preferred surfactants which form transparent solutions are sorbitan monooleate (Span 80) and sorbitan trioleate (Span 85). These are registered as approved cosmetic materials and food additives in Japan, and are biocompatible and safe. The most preferred surfactant is sorbitan monooleate (Span 80). A release agent composition using Span 80 has sufficiently low peel strength for most types of surgical tapes.

Since the release agent composition of the invention is liquid, it may be housed in a special container, or as a spray or drip. As a spray, for example, an aerosol spray can employing a propellant such as liquid petroleum gas (LPG) or a hand spray bottle using no gas may be applied. For drips there may be used squeeze bottles, hand pumps and dropper containers. A roll-on coating appliance with a roller attached to a liquid supply mouth, or a foam rubber coating appliance having foam rubber attached to a liquid supply mouth, may be used for direct coating onto the affected area on which the surgical tape or dressing film is attached. It may also be applied for a napkin or wipe impregnated with the release agent composition. Thus, while the form of the product may be one having the release agent composition housed in a container or having the release agent composition impregnated in a napkin or wipe, a coating appliance using no gas is preferred from a standpoint of cost and environmental impact. The release agent composition of the invention may be applied for most types of surgical tapes and dressing films, as well as certain types of adhesive-employing medical articles. Pressure-sensitive adhesives which can be released with the release agent composition of the invention include numerous types of pressure-sensitive adhesives such as, for example, acrylic-based adhesives, synthetic rubber-based adhesives, silicone adhesives and other types of adhesives.

In another embodiment, the present invention provides a releasing method of a skin adhesive. The present invention provides, for example, a releasing method of a skin adhesive from a skin comprising steps of: applying a release agent composition to a skin adhesive, and then removing the adhesive from the skin. The application of the release agent composition can be carried out by spray or drop of the release agent composition or by application from a napkin or wipe impregnated with the release agent composition.

Since penetration of the release agent is easy and rapid in a surgical tape using a nonwoven fabric base or porous base, the release agent composition may be dropped, coated or sprayed for easy release. For a surgical tape not employing a nonwoven fabric base or porous base, or for dressing films or other medical articles, it is preferred to first cany out a measure for peeling of the edge of the surgical tape or other product on the skin. After peeling off the edge, the surgical tape or other product may be peeled by continuous dropping or spraying on the newly peeled edge. This procedure will allow most types of surgical tapes, dressing films and adhesive-employing medical tools to be very easily released with a low peeling force and without irritation to the skin.

EXAMPLES Objects and advantages of this invention are further illustrated by the following examples, but the particular materials and amounts thereof recited in these examples, as well as other conditions and details, should not be construed to unduly limit the claims. Several aspects of the release agent composition were evaluated for the following examples and comparative examples. TEST METHODS

Odor and appearance

The presence of separation or color of the release agent composition (liquid) when placed in a transparent bottle was evaluated, and the odor detected when opening the bottle was recorded.

Skin evaluation

MEDIPORE™ (3M Company, St. Paul, MN.), a surgical tape with a 1-inch (25.4 mm) width comprising a polyester spun lace nonwoven fabric and a solution- coated acrylic-based pressure-sensitive adhesive was attached to the forearm of a test participant, and the test release agent composition was sprayed or wiped around the surgical tape. The surgical tape was peeled with a peel tester within 30 seconds at a peel angle of 180° and a peel speed of 6 inch/min (2.54 mm/sec), after which skin cell detachment was evaluated. The skin cell detachment was evaluated by using a solution containing 1 wt% Gentian Violet and 0.5 wt% Brilliant Green to stain the detached skin cells adhering to the adhesive surface of the peeled surgical tape, and performing visual examination with a microscope. Also, the release agent composition was contacted with skin injured by rubbing with a paper file, and irritation of the injured skin by the release agent composition was evaluated.

Release performance on phenol resin test board

Surgical tape was attached to an adherend to evaluate the performance of the release agent composition during peeling of the tape. First, the surgical tape was attached to a phenol resin test board and peeled off within 30 seconds. The peeling was accomplished with a peel tester at a peel angle of 180° and a peel speed of 6 inch/min

(2.54 mm/sec). The obtained peel strength was designated as the "initial peel strength with phenol board (without release agent)". Next, the surgical tape was again attached to a phenol resin test board and peeled within 30 seconds, but before peeling, the test release agent composition was sprayed or wiped onto the area surrounding the surgical tape. The obtained peel strength was designated as the "initial peel strength with phenol board (with release agent)". The presence or absence of paste residue during peeling was also observed.

The surgical tapes used were MEDIPORE™ (3 M Company, St. Paul, MN)₅ a surgical tape with a 1-inch (25.4 mm) width comprising a polyester spun lace nonwoven fabric and a solution-coated acrylic-based adhesive, and TRANSPORE

WHITE™ (3M Company, St. Paul, MN), a surgical tape with a 1-inch (25.4 mm) width comprising a nonwoven fabric base made of rayon and polyester fiber and a hot-melt- coated acrylic-based adhesive.

Because of variability in determining adhesive strength on the skin, such as personal differences, differences of attachment site and differences of attachment time, evaluation was conducted based on the initial peel strength using a phenol resin test board as the standard, in order to objectively determine the effect.

Release performance on skin

The same test was carried out as described for release performance on phenol resin test board, but a human forearm skin was used instead of the phenol resin test board. The obtained peel strength was designated as the "initial peel strength with skin (without release agent)" when no release agent composition was used, and as the "initial peel strength with skin (with release agent)" when the release agent composition was used. The presence or absence of paste residue during peeling was also observed. The surgical tape was also attached to skin, and then after standing for 2 hours, the peel strength was measured in the same manner. The obtained peel strength was designated as the "peel strength after 2 hours on skin (without release agent)" when no release agent was used, and as the "peel strength after 2 hours on skin (with release agent)" when the release agent was used. The presence or absence of paste residue during peeling was also observed.

The desired performance for the peel strength test is the ability to adhere firmly at 100 g/inch (39 g/cm) or greater onto skin, and after the release treatment, to be released at a lower peel strength, preferably no greater than 50 g/inch (20 g/cm) without skin irritation, skin reaction, skin injury or paste residue.

Comparative Examples A-C

Several release agent products were also evaluated as comparative examples. A remover spray composed mainly of ethyl alcohol and isopropyl alcohol as an alcohol- employing release agent product (Comparative Example A: Product A), a release wipe comprising a humectant, mineral oil, etc. added to isopropyl alcohol (Comparative

Example B: Product B) and a release wipe comprising D-limonene₅ mineral oil and other additives (Comparative Example C: Product C) were evaluated. The evaluation results are shown in Table 1. Table 1

\— ' O

The remover spray composed mainly of ethyl alcohol and isopropyl alcohol (Product A) is typically used with sports tape. The release agent spray was effective except for Transpore White. A large amount of paste residue was produced after 2 hours. The release agent also contained alcohol and therefore could irritated injured skin.

The release wipe comprising a humectant, mineral oil, etc. added to isopropyl alcohol (Product B) is typically used for surgical tape and dressing film. The release agent was a mixture of isoparaffϊn, propyl alcohol, dipropyleneglycol methyl ether, aloe extract and perfume. The release solution exhibited a powerful adhesive-dissolving effect for Medipore. Thus, the nonwoven fabric base peeled from the adhesive and left a large amount of sticky adhesive on the skin as paste residue. The paste residue on the skin could be removed by wiping, but because of the tacky and oily condition on the skin and its strong odor, the treatment was undesirable. Also, since the release agent contained isopropyl alcohol, injured skin was slightly irritated. The release effect was also insufficient for Transpore White. The adhesive strength after peeling was somewhat high, and a large paste residue was initially produced.

The release wipe comprising D-limonene, mineral oil and other additives (Product C) exhibited a powerful adhesive-dissolving effect for Medipore. Thus, the nonwoven fabric base peeled from the adhesive and left a large amount of sticky adhesive on the skin as paste residue. The paste residue on the skin could be removed by wiping, but because of the tacky and oily condition on the skin and its strong odor, the treatment was undesirable. Injured skin was not irritated, but the release effect was insufficient for Transpore White. The adhesive strength after peeling was somewhat high.

Some skin cells, detached from skin which had contacted the adhesive surface that was released without transferring to the skin, were observed on all of the surgical tape pieces.

Comparative Examples D-G

Release agent compositions comprising methylsiloxanes and their mixtures were evaluated. Different release agent compositions were coated around surgical tapes by hand spraying. The evaluation was carried out by the evaluation procedure described above. The results are shown in Table 2. Table 2

I

In the tables, HMDS represents hexamethyldisiloxane, OMTS represents octamethyltrisiloxane and DMCS represents decamethylcyclopentasiloxane. The contents are based on weight. Comparative Example D composed of 100 wt% HMDS had an effective release for Medipore but an ineffective release for Transpore White. This was apparently because the drying speed of HMDS was too fast for the HMDS to be released before drying. Readhesion between the skin and adhesive layer caused increase in the peel strength and created paste residue.

In order to inhibit the rapid drying of HMDS₃ decamethylcyclopentasiloxane (DMCS) with a boiling point of 210⁰C was added at 5 wt% to the HMDS in Comparative Example E, but the addition of DMCS instead impaired the performance. Addition of DMCS did not inhibit the drying speed.

In Comparative Example F, comprising 100 wt% octamethyltrisiloxane (OMTS) with a boiling point of 153°C, the peel strength for skin was minimized but the peel strength for Transpore White from a phenol resin board was very high, and this presented a problem in terms of stability and reliability of the peel strength. Since the adhesive-dissolving effect was insufficient in Comparative Example F, the release agent poorly penetrated with bonding to a flat board, resulting in build-up. In order to improve the adhesive-dissolving effect, 7.75 wt% hexamethyldisiloxane (HMDS) was added to octamethyltrisiloxane (OMTS) in Comparative Example G, but the improvement was minimal.

Comparative Examples H-K

Since the peel strength performance from skin and a standard phenol resin board was unsatisfactory with methylsiloxanes alone, D-limonene by Yasuhara Chemical Co. (Japan) was added as a low-volatile oil in a specific amount to hexamethyldisiloxane (HMDS) for Comparative Examples H-J. Also, a mixture of D-limonene and a surfactant was used for Comparative Example K. Each release agent was coated around surgical tape by hand spraying. The evaluation was conducted by the same evaluation procedure described above. The results are shown in Table 3. Table 3

45.

Since addition of D-limonene in a large amount results in dissolution of the adhesive itself, problems such as paste residue and sticking of the adhesive to the finger occurred. The appropriate range for D-limonene was 1-5 wt%. However, the drying speed of hexamethyldisiloxane (HMDS) was too fast for D-limonene to prevent drying of the hexamethyldisiloxane (HMDS). D-limonene containing 10 wt% TweenδO (polyoxyethylene sorbitan monooleate) completely dissolved the Medipore adhesive layer, but did not dissolve the Transpore White adhesive layer.

Examples 1 and 2

In order to obtain an adequate release agent effect, a mixture was prepared comprising a methylsiloxane solvent, a low-volatile oil and a nonionic surfactant, as a release agent composition of the invention. D-limonene was used as the low- volatile oil and the polyoxyethylene sorbitan ester Tween80 was used as the nonionic surfactant. Table 4 shows the compositions and evaluation results for several test release solutions. Each release agent was coated around surgical tape by hand spraying. The evaluation method was the same as in the comparative examples described above.

Table 4

With addition of Tween80 (polyoxyethylene sorbitan monooleate), the mixture was converted to a white opaque liquid. However, each of the mixtures was unstable, and separation of the surfactant occurred with prolonged storage. Remixing by shaking was therefore necessary to obtain a white opaque solution. Addition of 4.5 wt% D-limonene and 0.5 wt% Tween80 (polyoxyethylene sorbitan monooleate) to hexamethyldisiloxane (HMDS) (Example 1) was sufficiently effective as a release agent for Transpore White. In Example 2 where the siloxane solvent was changed from hexamethyldisiloxane (HMDS) to octamethyltrisϊloxane (OMTS)₃ the adhesive-dissolving effect was inadequate and the release reliability was poor.

Examples 3-5

Release agent compositions were developed to achieve stability, transparency and even better release effects for Transpore White. Sorbitan ester-type surfactants (Span) with low HLB (hydrophilic-lipophilic balance) were added to mixtures of hexamethyldisiloxane (HMDS) and D-limonene. Release solutions comprising Sρan20 (sorbitan monolaurate), Span60 (sorbitan monostearate) and Span65 (sorbitan tristearate) as sorbitan ester-type surfactants were opaque solutions. Release solutions containing Span20 (sorbitan monolaurate) and Span60 (sorbitan monostearate) readily separated, but the release solution containing Span65 (sorbitan tristearate) exhibited long-term stability. Also, release solutions containing SpanSO (sorbitan monooleate) and Span85 (sorbitan trioleate) were transparent solutions and exhibited long-term stability. Table 5 shows the compositions and evaluation results for several test release agent compositions. Each release agent was coated around surgical tape by hand spraying. The evaluation method was the same as in the comparative examples described above. Table 5

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Example 3, a mixture of 95 wt% HMDS₅ 4.5 wt% D-limonene and 0.5 wt% SpanδO (sorbitan monooleate), had an excellent release effect for Medipore and Transpore White, not only on skin but also on the standard phenol resin board. The peel strength on skin after the release treatment was 50 g/inch (20 g/cm) or less under all the conditions. There was no paste residue, no irritation to injured skin and minimal skin cell detachment. The mixture also had a low odor, on the level of an agreeable aromatic. In comparison to Example 4 where the surfactant was changed to Span85 (sorbitan trioleate), Example 3 exhibited more satisfactory penetration of the release agent composition. Also, in comparison to Example 5 where the siloxane solvent was changed from hexamethyldisiloxane (HMDS) to octarnethyltrisiloxane (OMTS), Example 3 exhibited an adequate adhesive-dissolving effect and excellent peel strength for the standard phenol resin board.

Example 6

Example 3 was tested with various types of surgical tapes composed of different base materials and adhesives. Table 6 shows the surgical tapes and the evaluation results, all of the surgical tapes being products manufactured by 3 M Company, with their product names shown. Most of the adhesives used were acrylic-based, but each adhesive had a different composition, production method and coating method. In order to confirm whether each surgical tape attached to skin could be released immediately by hand spray coating of the release agent composition of Example 3, one edge of the surgical tape was partially peeled and a 50 g weight was hung with a clip so that the adhesive side was peeled back and facing upward.

The release agent composition readily and rapidly penetrated with the surgical tapes which comprised a nonwoven fabric base or porous base, and therefore release was easy to achieve by hand spraying the release agent composition. For surgical tapes not utilizing a nonwoven fabric base or porous base, the release spray was sprayed on the edge of the surgical tape on the skin. The surgical tape was successfully released by hanging the 5O g weight while continuing to spray on the newly peeled edge. Before the release treatment, none of the surgical tapes could be released from skin simply by hanging the 50 g weight.

By spraying the release agent composition of Example 3 housed in a hand spray container, it was possible to achieve very easy and immediate release of all of the tested surgical tapes, with a very low peel force and without irritation or injury to the skin. Although the level of detached skin cells adhering to the surface of the peeled adhesive layer depended to some degree on the type of surgical tape, the detached skin cell level was less than without treatment. Table 6

Examples 7-9

The fatty acid triglyceride tricaprylin, commercially available as KOKONADO RK from Kao Corp. (Japan), was added as an additional low-volatile oil to a mixture of hexamethyldisiloxane (HMDS) or octamethyltrisiloxane (OMTS) with Sρan80. Table 7 shows the compositions and evaluation results for Examples 7-9. The release agent compositions were transparent stable liquids. The release agent compositions were coated around surgical tape by hand spraying. The evaluation method was the same as in the comparative examples described above. Table 7

O

The mixtures were transparent solutions, with no separation over prolonged periods. The release agent compositions produced low peel strength after release treatment, exhibiting properties roughly identical to the release agents employing D-limonene. The release agent compositions were virtually odorless and convenient to use. After release treatment, the hand spray residue was lightly wiped with a tissue and even the small amount of adhesive residue was removed, leaving a non-sticky and comfortable feel, while in comparison to Example 9 where the siloxane solvent was changed from hexamethyldisiloxane (HMDS) to octamethyltrisiloxane (OMTS), Example 7 exhibited an adequate adhesive-dissolving effect which was superior on the standard phenol resin board.

Example 10

Example 8 was further tested on several different types of surgical tapes composed of different bases and adhesives. Table 8 shows the surgical tapes and the evaluation results, all of the surgical tapes being products manufactured by 3M Company, with their product names shown. Most of the adhesives used were acrylic-based, but each adhesive had a different composition, production method and coating method. In order to confirm whether each surgical tape attached to skin could be released immediately by hand spray coating of the release agent composition of Example 8, one edge of the surgical tape was partially peeled and a 50 g weight was hung with a clip so that the adhesive side was peeled back and facing upward.

The release agent composition readily and rapidly penetrated with the surgical tapes which comprised a nonwoven fabric base or porous base, and therefore release was easy to achieve by hand spraying the release agent composition. For surgical tapes not utilizing a nonwoven fabric base or porous base, the release spray was sprayed on the edge of the surgical tape on the skin. The surgical tape was successfully released by hanging the 50 g weight while continuing to spray on the newly peeled edge. Before the release treatment, none of the surgical tapes could be released from skin simply by hanging the 50 g weight.

By spraying the release agent composition of Example 8 housed in a hand spray container, it was possible to achieve very easy and immediate release of all of the tested surgical tapes, with a very low peel force and without irritation or injury to the skin. Although the level of detached skin cells adhering to the surface of the peeled adhesive layer depended to some degree on the type of surgical tape, the detached skin cell level was less than without treatment. Table 8

Claims

1. A release agent composition for skin adhesives, comprising at least 85 wt% of a methylsiloxane solvent with a boiling point of at least 95°C and below 170⁰C₅ at least 0.1 wt% of an oil-compatible and pressure-sensitive adhesive-dissolving oil with a boiling point of at least 170°C, and at least 0.1 wt% of a nonionic surfactant.

2. A release agent composition according to claim 1, wherein said methylsiloxane solvent is one or more solvents selected from the group consisting of hexamethyldisiloxane (HMDS), octamethyltrisiloxane (OMTS) and hexamethylcyclotrisiloxane (HMCTS).

3. A release agent composition according to claim 1 or 2, wherein said oil-compatible and pressure-sensitive adhesive-dissolving oil is selected from the group consisting of terpenes, aliphatic compounds and mixtures thereof.

4. A release agent composition according to claim 3, wherein said oil-compatible and pressure-sensitive adhesive-dissolving oil comprises D-limonene.

5. A release agent composition according to claim 3, wherein said oil-compatible and pressure-sensitive adhesive-dissolving oil contains a fatty acid triglyceride.

6. A release agent composition according to claim 5, wherein said fatty acid triglyceride is tricaprylic acid glycerin ester (tricaprylin).

7. A release agent composition according to any one of claims 1 to 6, wherein said nonionic surfactant is selected from the group consisting of sorbitan esters and polyoxyethylene sorbitan esters.

8. A release agent composition according to claim 7, wherein said sorbitan esters are selected from the group consisting of sorbitan monooleate and sorbitan trioleate.

9. A release agent composition according to any one of claims 1 to 8, wherein the skin adhesive is an acrylic-based pressure-sensitive adhesive.

10. A release product for skin adhesives comprising a release agent composition according to any one of claims 1 to 9, and a container holding said release agent composition.

11. A release product for skin adhesives comprising a release agent composition according to any one of claims 1 to 9, and a napkin or wipe impregnated with said release agent composition.

12. A releasing method of a skin adhesive from a skin comprising steps of: applying a release agent composition according any one of claims 1 to 9 to a skin adhesive, and then removing the adhesive from the skin.

13. A releasing method according to claim 12, wherein the application of the release agent composition is carried out by spray or drop of the release agent composition or by application from a napkin or wipe impregnated with the release agent composition.

14. The release agent composition of claim 1 , wherein the methylsiloxane solvent with a boiling point of at least 95°C and below 170⁰C comprises no more than 99.8 wt%.

15. The release agent composition of claim 1, wherein the oil-compatible and pressure- sensitive adhesive dissolving oil with a boiling point of at least 170⁰C comprises no more than 5 wt%.

16. The release agent composition of claim 1, wherein the nonionic surfactant comprises no more than 10 wt%.

17. A release agent composition for skin adhesives, comprising

85-99.8 wt% of a methylsiloxane solvent with a boiling point of at least 95°C and below 170⁰C,

0.1-5 wt% of an oil-compatible and pressure-sensitive adhesive-dissolving oil with a boiling point of at least 170⁰C, and

0.1-10 wt% of anonionic surfactant.