SKIN-ADHESIVE ITEM

Abstract

A skin-adhesive item is described that can include a substrate F coated continuously or discontinuously on at least one of the two faces thereof by a pressure-sensitive silicone adhesive Z that has been previously sterilized by means of gamma radiation and demonstrates good tack on the skin even after sterilization.

Claims

1. A skin-adhesive article comprising a substrate F coated, continuously or noncontinuously, on at least one of the two faces with a pressure-sensitive silicone adhesive Z obtained by crosslinking a silicone composition X comprising: 1) from 80 to 20 parts by weight of at least one silicone resin A comprising SiOH functional groups, 2) from 20 to 80 parts by weight of at least one polyorganosiloxane G2 comprising at least two Si-vinyl functional groups at the chain end and which is a silicone gum having a consistency at 25 C. of between 200 mm/10 and 2000 mm/10, 3) a silicone base B1 capable of reacting by addition reactions, comprising: at least one organohydrosiloxane having at least two SiH functional groups in an amount sufficient to provide an SiH/Si-vinyl molar ratio of between 0.5:1 and 20:1, a catalyst of the addition reaction C2, and optionally an inhibitor of the addition reaction, and 4) at least one solvent S, with the condition according to which: c) the amount of solvent S is determined so that the silicone composition X contains, by weight as solid content of silicone, from 20% to 80%, and d) said skin-adhesive article is sterilized by means of gamma radiation at doses of between 10 kGy and 50 kGy.

2. The skin-adhesive article as claimed in claim 1, wherein the crosslinking to obtain the pressure-sensitive silicone adhesive Z is initiated by evaporating the solvent S.

3. The skin-adhesive article as claimed in claim 1, wherein the solvent S is selected from the group consisting of: aliphatic C.sub.6 to C.sub.16 hydrocarbons, polydimethylsiloxanes comprising a trimethylsilyl end group having a viscosity of 0.65 to 5 mPa.Math.s at 25 C., cyclic polydimethylsiloxanes, (3-octyl)heptamethyltrisiloxane, toluene, xylene, a C.sub.1 to C.sub.8 alkyl ester, a C.sub.2 to C.sub.4 carboxylic acid and their mixtures.

4. The skin-adhesive article as claimed in claim 1, wherein the silicone resin comprising SiOH functional groups is selected from the group consisting of: a) hydroxlyated silicone resins of MQ.sup.(OH) type which are copolymers comprising M and Q.sup.(OH) siloxy units of following formulae: M=R.sup.1R.sup.2R.sup.3SiO.sub.1/2, and Q.sup.(OH)=(OH)SiO.sub.3/2, with optionally the presence of siloxy unit Q=SiO.sub.4/2 b) hydroxlyated silicone resins of MD.sup.VIQ.sup.(OH) type which are copolymers comprising M, D.sup.Vi and Q.sup.(OH) siloxy units of following formulae: M=R.sup.1R.sup.2R.sup.3SiO.sub.1/2, D.sup.Vi=(Vi)(R.sup.1)SiO.sub.2/2, and Q.sup.(OH)=(OH)SiO.sub.3/2, with optionally the presence of siloxy unit Q=SiO.sub.4/2 c) hydroxlyated silicone resins of MM.sup.ViQ.sup.(OH) type which are copolymers comprising M, M.sup.Vi and Q.sup.(OH) siloxy units of following formulae: M=R.sup.1R.sup.2R.sup.3SiO.sub.1/2, M.sup.Vi=(Vi)(R.sup.1)(R.sup.2)SiO.sub.2/2, and Q.sup.(OH)=(OH)SiO.sub.3/2, with optionally the presence of siloxy unit Q=SiO.sub.4/2 d) hydroxlyated silicone resins of MDT.sup.(OH) type which are copolymers comprising M, D and T.sup.(OH) siloxy units of following formulae: M=R.sup.1R.sup.2R.sup.3SiO.sub.1/2, D=R.sup.1R.sup.2SiO.sub.2/2, T.sup.(OH)=(OH)R.sup.1SiO.sub.2/2, and e) hydroxlyated silicone resins of DT.sup.(OH) type which are copolymers comprising D and T.sup.(OH) siloxy units of following formulae: D=R.sup.1R.sup.2SiO.sub.2/2, T.sup.(OH)=(OH)R.sup.1SiO.sub.2/2, in which formulae the symbol Vi=a vinyl group and the symbols R.sup.1, R.sup.2 and R.sup.3 are selected, independently of one another, from the group consisting of: linear or branched alkyl groups having from 1 to 8 carbon atoms and optionally substituted by one or more halogen atoms, and aryl or alkylaryl groups having from 6 to 14 carbon atoms inclusive.

5. The skin-adhesive article as claimed in claim 4, wherein the silicone resin A is a hydroxylated silicone resin of M.sup.Q(OH) or MM.sup.ViQ.sup.(OH) type and contains from 0.1% to 4% by weight of hydroxyl group with respect to the dry weight of said silicone resin A.

6. The skin-adhesive article as claimed in claim 1, it wherein the article is a component of a dressing for medical or paramedical use.

7. The skin-adhesive article as claimed in claim 1, wherein the article is a component of a wearable medical device.

8. The skin-adhesive article as claimed in claim 1, wherein the amount of solvent S is determined so that the silicone composition X contains from 40% to 70% by weight as solid content of silicone.

9. The skin-adhesive article as claimed in claim 2, wherein the solvent S is evaporated while keeping the skin-adhesive article in a chamber within which the temperature is between 50 C. and 200 C.

10. The skin-adhesive article as claimed in claim 9, wherein the temperature within the chamber is kept at plus or minus 5 C. from the boiling point of said solvent S.

11. The skin-adhesive article as claimed in claim 4, wherein when R.sup.1, R.sup.2 and R.sup.3 are, independently of one another, the linear or branched alkyl groups, they are selected from the group consisting of methyl, ethyl, isopropyl, tert-butyl and n-hexyl groups.

12. The skin-adhesive article as claimed in claim 4, wherein when R.sup.1, R.sup.2 and R.sup.3 are, independently of one another, the aryl or alkylaryl groups, they are selected from the group consisting of the phenyl, xylyl and tolyl groups.

Description

EXAMPLE 1: COMPARATIVE TESTS

[0136] Three commercial silicone gels supplied by Bluestar Silicones were prepared and coated continuously or noncontinuously over a flexible polyurethane film and then subsequently sterilized by gamma radiation (at 16, and 50 kGy). The peel strength of the sterilized silicone gels was measured and compared with the peel strength without sterilization (the variations in % are mentioned in table 1). [0137] Silicone gel 1: Silbione HC2 2011 [0138] Silicone gel 2: Silbione HC2 2022 [0139] Silicone gel 3: Silbione HC2 2031

[0140] Measurement Conditions:

[0141] Peeling measurement on a sheet of Bristol paper (Exacompta, dimensions: 21 cm*5 cm)

[0142] Test specimen size: 2.5 cm14 cm; peeling rate 300 mm/min10 N cellpeeling over 12 cm.

TABLE-US-00001 TABLE 1 Variations in % of the peel strengths measured for the different silicone gels Peel strength Peel strength Peel strength variation after variation after variation after 16 kGy treatment 30 kGy treatment 50 kGy treatment Gel 1 47% 71% 92% Gel 2 48% 78% 88% Gel 3 42% 76% 97%

[0143] The peel strength (on a sheet of Bristol paper (simulating adhesion to the skin)) of the silicone gels decreases very strongly, even at low sterilization doses (16 kGy). The adhesion to the skin of devices using the gels 1, 2 and 3 after sterilization by gamma radiation is not satisfactory.

EXAMPLE 2: TESTS ACCORDING TO THE INVENTION

[0144] Three commercial pressure-sensitive silicone adhesives (PSAs) provided by Bluestar Silicones were prepared and coated continuously over a flexible polyethylene terephthalate (PET) film and then subsequently sterilized with gamma radiation (at 16 or 30 kGy). The peel strength of the sterilized silicone PSAs was measured and compared with the peel strength without sterilization (the variations in % are mentioned in table 2). [0145] Silicone PSA 1: Silcolease PSA 502 (PSA which crosslinks by platinum-catalyzed addition reactions). [0146] Silicone PSA 2: Silcolease PSA 400 (PSA which crosslinks by condensation reactions). [0147] Silicone PSA 3: Silcolease PSA 408 (PSA which crosslinks by condensation reactions).

[0148] Measurement Conditions:

[0149] Peeling measurement on a sheet made of stainless steel (provided by Cheminstrument, reference TP-26 Steel Panels)

[0150] Test specimen size: 2.5 cm14 cm; peeling rate 300 mm/min10 N cellpeeling over 12 cm.

TABLE-US-00002 TABLE 2 Variations in % of the peel strengths measured for the different silicone PSAs Peel strength Peel strength variation after variation after 16 kGy treatment 30 kGy treatment Silicone PSA 1 4% 3% (Invention) Silicone PSA 2 14% 17% (Comparative 1) Silicone PSA 3 19% 11% (Comparative 2)

[0151] The best results are obtained with PSA 1, which is a pressure-sensitive adhesive which crosslinks by addition reactions (platinum catalyst). It is noticed that the peel strength of the silicone PSA 1 after irradiation is decreased by 3% to 4%, with respect to the same nonirradiated PSA, illustrating a change in the chemical structure of the product obtained after irradiation.

[0152] The silicone PSAs 2 and 3 (comparative), which are PSAs which crosslink by polycondensation, show variations in the peel strengths of between 10% and 15%, causing problems of adhesion, in particular when adhesion to the skin is concerned.