HICKS JOHN KENNETH (GB)
KING HAZEL ANN (GB)
HICKS JOHN KENNETH (GB)
| WO1993002717A1 | 1993-02-18 |
| EP0565825A1 | 1993-10-20 | |||
| GB2148910A | 1985-06-05 | |||
| FR2214747A1 | 1974-08-19 |
DATABASE WPI Derwent World Patents Index; AN 93-299826(38), XP002007626
| 1. | Compounds of the Formula (1): CH3(CH2)x[CO]n(OCH2CH2)yCO2ACO2H (1) wherein x is an integer of from 4 to 20; n is 0 or 1 ; y is an integer of from 10 to 200 and A is an alkenylene radical such that A(CO2H) is a dibasic acid capable of forming an anhydride A(CO2)O, or a salt of a compound of Formula (1) herein. |
| 2. | A compound of Formula (1) as claimed in claim 1 in the form of an ammonium salt. |
| 3. | Compounds of Formula (1) according to either claim 1 or claim 2 wherein x is from 10 to 17, y is less than 80 and A is a vinyl group. |
| 4. | A polymer composition comprising residues of a compound of Formula (1 ) or a salt thereof, as defined in claim 1. |
| 5. | A polymer according to claim 4 further comprising residues of at least one ethylenically unsaturated monomer. |
| 6. | A polymer according to claim 4 wherein said monomer comprises alkyl esters or amides of acrylic or methacrylic acid or a hydroxylated derivative thereof. |
| 7. | A skin friendly pressure sensitive adhesive comprising a polymer as claimed in any of claims 4 to 6. |
| 8. | An adhesive as claimed in claim 7 wherein the polymer comprises from 0.2 to 5% b weight of a compound of Formula (1), as defined in claim 1 , or a salt thereof. |
| 9. | A medical or surgical dressing comprising a flexible substrate carrying an adhesive as claimed in either claim 7 or claim 8. |
| 10. | A process for producing compounds of Formula (1 ), as defined in claim 1 which comprises reacting a dibasic acid anhydride of the formula. A(CO)2O wherein A is as defined in claim 1 , with ethoxylated acid or alcohol of the formula CH3(CH2)x(CO)n(OCH2CH2)yOH wherein n, x and y are as defined in claim 1. |
| 11. | A process as claimed in claim 10 wherein the reaction product is further reacted with a base to form a salt. |
THEREFROM
This invention concerns polymerisable compounds exhibiting surfactant properties, adhesives containing such compounds and adhesive containing products.
European Patent 0099675 describes polymerisable surfactants of the general formula
CH 2 = C(R)-COO-(CH 2 -CH(CH 3 )-O) x -(CH 2 -CH 2 -O) y OC-A-COOH
wherein R is H or CH 3 . x is an integer from 2 to 20, y is an integer from 0 to 5. A is an alkylene, alkenylene or phenylene radical such that A (COOH) 2 is a dibasic acid capable of forming an anhydride A(CO) 2 O.
These are polymerisable compounds which have surfactant properties and are used in emulsion polymerisation reactions to produce adhesive polymers which are suitable for medical and surgical use. These surfactants are preferentially produced in toluene and purified by washing with diethyl ether or other solvents.
It is well known in the art to form polymers by emulsion polymerisation.
European Patent 0194881 employs copolymerisable surfactants having the formula
O ||
R 1 O-C-CH 2 -C-C-O-(CH 2 ) 3 -S(O 2 )-OM
II II
O CH 2
in which R, is a C 10 to C 14 alkyl radical and M is hydrogen, ammonia or an alkai metal in emulsion polymerisable reactions with one or more copolymerisable acrylic monomers to make emulsion polymers which have adhesive properties and are suitable for application to the skin.
Sodium mono-lauryl itaconoxypropane sulphonate is a surfactant according to the formula claimed in EP 0194881 which is used in the manufacture of an emulsion adhesive polymer as claimed in EP 194881 B1. A pressure sensitive adhesive as disclosed in EP 194881 can be used for adhesive surgical and medical dressings.
The surfactant sodium mono-lauryl itaconoxypropane sulphate for use in the manufacture of an adhesive is the product of a two stage synthesis. Firstly monolauryl itaconate is produced by the reaction of intaconic anhydride with lauryl alcohol. Thereafter the ester is sulphopropylated using propane sultone.
This two stage reaction is an expensive process and adds greatly to the cost of the final material. Also, the final step of converting the mono lauryl itaconate to the surfactant carries a perceived hazard since propane sultone is a suspected carcinogen.
It is an object of the present invention to provide a new surfactant system suitable for use in the manufacture of a water based emulsion adhesive. It is a particular object of the present invention to provide a surfactant system which is a one step system and is less expensive to implement than the systems acknowledged as prior art.
The present invention thus provides a compound having the formula (I):
CH 3 (CH 2 ) x -[CO] n (OCH 2 CH 2 ) y CO 2 -A-CO 2 H (I)
or a salt thereof, wherein,
x is an integer from 4 to 20 n is 0 or 1 y is an integer from 10 to 200 A is an alkenylene radical such that A(CO 2 H) 2 is a dibasic acid capable of forming an anhydride A (CO) 2 O
Apt salts of compounds of formula (I) are water soluble and include the ammonium, water soluble alkyl substituted ammonium and alkali metal salts thereof.
A preferred salt of the compounds of formula (I) is the ammonium salt.
Compounds of general formula (I) having low cloud points can be converted to salts to increase their efficiency.
The water insoluble compounds of the invention can be used as intermediates to form the water soluble compounds of the invention by ion exchange. The compound of formula (I) itself is water soluble.
Favoured residues A are
-CH=CH-, -CH 2 C(=CH 2 )-, -C(=CH 2 )CH 2 ,-CH=C(SO 3 )-C(SO 3 )=CH-
The most preferred residue A is -CH=CH-.
Aptly y has a value of less than 80. Preferred values for y are from 10 to 50 or from 50 to 80. The favoured values for y are 20 to 30.
Favoured values for x are 10 to 17 and more favourably 15 o 17.
All values such as x and y are number average values.
The preferred value for n is 0.
A highly favoured compound of this invention is the ammonium salt of compounds of formula (I) in which x is an integer from 15 to 17, y is 50 to 80, A is -CH=CH-
The compounds of formula (I) of the present invention can be prepared by a process which comprises reacting a dibasic acid anhydride of the formula A(CO) 2 O wherein A is as defined in relation to the compound of formula (I) with a compound of the formula (II):
CH 3 (CH 2 ) x (CO) n (OCH 2 CH 2 ) y OH (II)
wherein x, y and n are as defined in relation to formula (I).
A favoured ethoxylated alcohol is cetostearyl alcohol having an average of 25 moles of oxyethylene groups per molecule and is available under the Trade Mark LUTENSOL AT25 from BASF
Suitable dibasic anhydrides include maleic anhydride, sulphomaleic anhydride and itaconic anhydride.
The reaction between the fatty acid/alcohol and the anhydride may be performed by fusing the reagents at temperatures above their melting points. The reaction may also be performed in a suitable aprotic solvent. More than one molar equivalent of the anhydride may be used.
In a typical favoured process the reagents are heated to 70°C for 30 mins.
The salts may then be formed by reaction of aqueous solutions of formula (I) with appropriate bases. They may either be generated in situ when needed for the relevant emulsion polymerisation processes or stored as solutions.
The surfactant system of the present invention provides an advantage over the prior art in that the one step reaction for
preparation is simpler than that required for the surfactants disclosed and used in EP 0099675 and EP 194881
Water soluble compounds of the invention are surfactants. The ammonium and alkali metal salt compounds in particular have good surfactant properties The ammonium salt is especially favoured for this purpose.
The surfactant compounds of the present invention can be used in emulsion polymerisation, when they will become part of the resulting polymer molecule
Therefore in one aspect, the invention provides a polymer which comprises residues of a compound of formula (I) or a salt thereof
The surfactant compounds of the present invention can be used advantageously in the emulsion polymerisation of acrylic monomers It has been found that these compounds will form stable emulsions with acrylic monomers and will reduce coagulation of any such emulsions during an emulsion polymerisation process
Apt acrylic monomers include alkyl esters or amides of acrylic and methacrylic acids and hydroxylated derivatives thereof
A polymer produced by emulsion polymerisation using a surfactant of the present invention may be an adhesive polymer, advantageously an acrylic adhesive polymer
Apt acrylic monomers for such adhesive polymers include those listed above.
The surfactant compounds of the invention employed during the emulsion polymerisation process will become part of the resulting adhesive polymer molecule.
In accordance with a further aspect of the invention there is provided a skin friendly adhesive suitable for use with medical and surgical dressings comprising a polymer of the invention.
Therefore in an embodiment of this aspect of the invention there is provided an adhesive polymer which comprises residues of one or more acrylic monomers and residues of one or more compounds of formula (I) or a salt thereof.
Adhesive polymers of this type may be pressure sensitive adhesive polymers.
For pressure sensitive adhesives to be used on skin, for example in surgical or medical dressings. It is especially desirable, in order to maintain good adhesion to skin that such adhesives are not water-sensitive (in that water does not significantly affect their adhesive properties). Non copolymerisable surfactants for emulsion- polymerised pressure sensitive adhesives should therefore avoided.
The water soluble compounds of the invention can be readily copolymerised with one or more acrylic monomers by emulsion polymerisation and thus form adhesive materials suitable for use on skin.
The use of an ammonium salt of the invention to form an adhesive polymer of the invention is specially advantageous in that on heating the polymer in a dry form, ammonia is liberated and the adhesive polymer is converted to the acid form. The acid form of the adhesive polymer of the invention is generally less sensitive to water than analogous polymers containing salts of the acid.
The adhesive polymer of the invention may suitably contain 0.2 to 5% by weight of residues of a compound of formula (I) or a salt thereof, for example 1%.
In the apt polymers of the invention the acrylic polymer component consists mainly of acrylic residues for which the
monomer is an alkyl ester of acrylic or methacrylic acid in which the alkyl residue contains 2 to 10 carbon atoms. Favoured pressure sensitive adhesive forming alkyl acrylate monomers are alkyl esters of acrylic acid in which the alkyl group contains 3 to 12 carbon atoms and preferably 4 to 9 carbon atoms. Alkyl acrylate monomers of this type include n-butyl acrylate, 2-ethylhexyl acrylate and other octyl acrylates. Favourably monomers include n-butyl acrylate and 2-ethylhexyl acrylate.
A suitable pressure sensitive adhesive polymer may comprise
90 to 99.5% by weight of such acrylic residues, favourably 94 to 99.5% and preferably 96 to 99.5%.
Often these acrylic residues will consist of a mixture of two monomer species, often in equal proportions.
Preferably a combination of 2-ethyl hexyl acrylate and n-butyl acrylate are used.
Pressure sensitive adhesives of the invention advantageously contain residues of other acrylic monomers. Suitable monomers include acrylic esters, comprising monoesters such as optionally hydroxylated or alkoxylated alkyl esters, for example methyl methacrylate, hydroxyethyl methacrylate and n-butyl methacrylate. Suitable monomer residues also include acrylic amides, comprising monoamides such as optionally N-alkylated amides, for example acrylamide, methacrylamide, N-tert. butylacrylamide and N-lauryl acryiamide. Optional monomers also include ammonium sulphatoethyl methacrylate, monomethacryloyloxyethyl phthalate, acrylic acid and methacrylic acid.
Such residues may form up to 10% by weight of the polymer, for example up to 8%, aptly 4 to 8%. The most apt proportion of such residues will depend to some extent on the particular monomer species, the monomer species of the main components, the emulsion polymerisation conditions and the desired physical properties of the pressure sensitive adhesives.
A suitable pressure sensitive adhesive polymer compnses 39 to 59% by weight of n-butyl acrylate residues, 39 to 59% by weight of 2-ethylhexyl acrylate residues, 0.3 to 10%, aptly 0.3 to 5% by weight of hydroxyethyl methacrylate residues and 2% to 8% by weight of n-butyl methacrylate residues.
A favoured pressure sensitive adhesive polymer comprises
40 to 49.75% by weight of n-butyl acrylate residues, 47 to 54% by weight of 2-ethylhexyl acrylate residues, or 0.8 to 3% by weight of hydroxyethyl methacrylate residues, and 4% to 6% by weight of n- butyl methacrylate residues
Preferred pressure sensitive adhesive polymers of the invention contain: 44, 50, 1 and 5% by weight respectively of the above residues, the last two being respectively hydroxyethyl methacrylate and n-butyl methacrylate.
The pressure sensitive adhesives of the invention can be used for adhesive surgical and medical dressings and therefore adhesive surgical and medical dressings comprising flexible substrates carrying an adhesive of this invention are an important aspect of this invention
The adhesive of the invention may be used to coat fabrics such as non-woven, knitted or woven fabrics; filmic materials, including polymer films such as porous polyvinylchloπde film, continuous and perforated films such as polyurethane-containing film; integral nets; and the like to form surgical and medical adhesive dressings. Suitable backing materials for moisture vapour transmitting adhesive dressings are disclosed in British Patent No. 1 ,280,631
Adhesive polymers of the invention can be prepared by a process which comprises polymerising as an emulsion one or more unsaturated monomers and a water soluble salt of a compound of the formula (I) in the presence of a free radical catalyst.
The free radical catalyst is generally a conventional aqueous free radical catalyst such as ammonium persulpate, or may be a redox catalyst.
The emulsion may conveniently be made by initially forming an aqueous solution of a water-soluble salt of the compound of formula (I) in situ from the acid of formula (I) and a suitable basic salifying agent, for example an alkali metal or optionally trialkyl substituted ammonium hydroxide. The optional termonomer in the polymers of the present invention may then be added to the solution, in particular if it is an acrylic amide, and the remaining monomers to be polymerised then added to the salt solution. Alternatively, all the monomers may be premixed, in particular if the termonomer is an acrylic ester, and the premix then added to the salt solution. In either case the pH of the salt solution is adjusted to approximately pH7 before the addition of remaining or premixed monomers, which are then mixed under high-shear stirring.
The resulting monomer emulsion typically has a solids content in the range of 15 to 60% by weight and preferably 30 to 50%.
The resulting monomer emulsion may then be added to an aqueous solution of free-radical catalyst, for example ammonium persulphate, and polymerisation effected by heating, typically to 75° to 95°C, under an inert atmosphere, such as nitrogen or carbon dioxide. Advantageously, the monomer emulsion may be added to the catalyst solution over a period of time during the polymerisation reaction.
Alternatively the monomer emulsion may be purged with nitrogen before use.
The polyacrylate adhesive emulsions of the invention may contain thickeners, fillers and medicaments such as anti-microbial agents including anti fungal and anti bacterial agents. The adhesive
can be coated onto a suitable substrate by a direct or transfer coating process using conventional coating techniques.
The polyacrylate adhesives of the invention containing residues of an ammonium salt of the compound of the invention when heated lose ammonia and the salt is converted to the acid form. Surgical or medical dressings coated with such polyacrylate adhesives have been found to have good adhesion to skin and are not sensitive to water.
The invention will be further illustrated by the following Examples.
Preparation of Polymerisable Surfactant
Example 1
Cetostearic acid ethoxylate (100 EO) (41.8g 8.9 mmol) was heated to 90°C and itaconic anhydride (1.00g. 8.9 mmol) was added. The temperature was maintained for 60 mins then the product was discharged. After cooling the product was recrystallised from acetone.
Example 2
Cetostearyl alcohol ethoxylate (25 EO) (30.0g, 22mmol) was heated to 65 to 70°C and maleic anhydride (3. Og, 31 mmol) was added. The temperature was maintained at 65 to 70°C for 30 mins. 200cm 3 of deionised water was then added, and the mixture held at 65 to 70°C until solution was complete. After cooling, samples from the solution were adjusted to pH7 using both 0.88 ammonia and 5M sodium hydroxide solutions to give respective ammonium and sodium salts.
Preparation of Emulsion Polvacrvtate Adhesive
Example 3
Aqueous ammonium salt surfactant (equivalent to 3.5g solids) from Example 2 was added to deionised water (143. Og). Premixed n-butyl acrylate (154g), 2-ethylhexyl acrylate (175g), 2-hydroxyethyl methacrylate (3.5g) and n-butyl methacrylate (17.5g) were added whilst the solution was stirred with a high shear mixer to form a monomer emulsion. The monomer emulsion was purged with nitrogen then fed dropwise using a peristaltic pump over a period of 3 hours to a solution of ammonium persulphate (0.91g) in water (186.8g) in a reaction flask fitted with an agitator and a condenser and maintained at a constant temperature in the range of 80 to 90°C by a constant temperature water bath. The polymerisation reaction was allowed to continue for a further hour to give a total reaction time of 4 hours.
Example 4
The procedure of Example 3 was repeated for the sodium salt surfactant from Example 2, except that the monomer feed was carried out over 2 hours at a temperature of 75 to 80°C, with the reaction being allowed to continue for a further 2 hours at a temperature of 80 to 90°C.
Preparation of Adhesive Dressings
Example 5
The polyacrylate adhesive emulsion of Example 4, thickened by the addition of an acrylic thickening solution (Primal ASE 60, available from Rohm and Haas) was coated onto a siiicone coated release paper by means of a blade over flat bed coater, and dried in an air circulating oven at a temperature of 55°C to give a dried pressure sensitive adhesive coating with a weight per unit area of 35g/m 2 . The adhesive coating was transferred to a polyurethane-
containing film, and cut into 1.5cm wide surgical tapes. The resulting tapes showed good adherence to glass and polypropylene surfaces, and should adhere well to human skin under both dry and wet conditions.
Example 6
The procedure of Example 5 was repeated on a cloth substrate wherein the coating weight of the adhesive was 150g/m 2 .
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