CA2087273A1 - Polymeric films for forming capsule shells - Google Patents
Polymeric films for forming capsule shellsInfo
- Publication number
- CA2087273A1 CA2087273A1 CA002087273A CA2087273A CA2087273A1 CA 2087273 A1 CA2087273 A1 CA 2087273A1 CA 002087273 A CA002087273 A CA 002087273A CA 2087273 A CA2087273 A CA 2087273A CA 2087273 A1 CA2087273 A1 CA 2087273A1
- Authority
- CA
- Canada
- Prior art keywords
- cationic
- composition according
- anionic
- moieties
- polymer
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
Classifications
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
- A61K8/00—Cosmetics or similar toiletry preparations
- A61K8/02—Cosmetics or similar toiletry preparations characterised by special physical form
- A61K8/11—Encapsulated compositions
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
- A61K8/00—Cosmetics or similar toiletry preparations
- A61K8/18—Cosmetics or similar toiletry preparations characterised by the composition
- A61K8/72—Cosmetics or similar toiletry preparations characterised by the composition containing organic macromolecular compounds
- A61K8/81—Cosmetics or similar toiletry preparations characterised by the composition containing organic macromolecular compounds obtained by reactions involving only carbon-to-carbon unsaturated bonds
- A61K8/8141—Compositions of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by only one carboxyl radical, or of salts, anhydrides, esters, amides, imides or nitriles thereof; Compositions of derivatives of such polymers
- A61K8/8158—Homopolymers or copolymers of amides or imides, e.g. (meth) acrylamide; Compositions of derivatives of such polymers
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
- A61K9/00—Medicinal preparations characterised by special physical form
- A61K9/48—Preparations in capsules, e.g. of gelatin, of chocolate
- A61K9/4816—Wall or shell material
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61Q—SPECIFIC USE OF COSMETICS OR SIMILAR TOILETRY PREPARATIONS
- A61Q19/00—Preparations for care of the skin
- A61Q19/10—Washing or bathing preparations
Landscapes
- Health & Medical Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Public Health (AREA)
- Veterinary Medicine (AREA)
- Animal Behavior & Ethology (AREA)
- General Health & Medical Sciences (AREA)
- Epidemiology (AREA)
- Birds (AREA)
- Dermatology (AREA)
- Chemical & Material Sciences (AREA)
- Medicinal Chemistry (AREA)
- Pharmacology & Pharmacy (AREA)
- Manufacturing Of Micro-Capsules (AREA)
- Cosmetics (AREA)
- Medicinal Preparation (AREA)
Abstract
A composition suitable for forming capsule shells is a water soluble synthetic film-forming polymeric composition of cationic and anionic moieties, and is preferably a blend of cationic polymer with anionic polymer. The capsule shells formed of such a composition is suitable for containing a range of non-aqueous fillings ranging from bath additives such as bath oil to hazardous chemicals such as pesticides.
Description
WO 91/19487 PC~/GB91/00930 ,f ::;
~7~273 POLYMERIC FILMS FOR FO MG CAPSULE SHELLS
This invention relates to polymeric films which are suitable for forming shells or capsules for containing various non-aqueous liquids or solids.
Depending on the various uses of the capsule shells, the required properties may vary. At present, capsules are usually made from gelatin. However there are various reasons why it is sometimes undesirable to us~ a naturally occuring material such as gelatinj for instance because of its variable quality or because of a public pre~erence to use a synthetic material rather than an animal-based material. It is known to form capsules from sin~le homopolymeric materials such as polyvinyl alcohol.
However, it is difficult with ~hese polymeric rompositions to produce a product having all the desired properties for each alternative use.
The walls of gel capsules must have high mechanical strength and stability, and resistance to the substance which will be contained in the cap~ule ~hell. It is often necessary that the capsule shells should dissolve rapidly . in .water. .However, the solubility properties can vary ! - considerably from one requirement .to another,~for example the temperature of the aqueous solution:in which the shell . must.dissolve may vary oonsidexably...',:For~example if ~25.~ capsules; ar~ filled with-pesticides -or.herbicides the :. capsule walls must dissolve in cold .water, so that the .. . .. .,. ~
,.~..,pesticidejmay be readily diluted:for application to the land, whereas when the contained ~substance is.,~bath oil, ... ";.;~.;rapid solubility~,must be !achievedmfor ;warm water. In .;..~30....~,,addition,~for..example,~if'~ the.capsule shells~are used for containing.pharmaceutical preparations or cosmetic products .. such .as bath joils,:,:the geljcapsule~mu~t~be'aesthetically acceptable and.~i,therefore~ it.~ is.~,beneficial i~ the lm-forminglpolymericl,material~.-can~be~dyed and/or can be . ...35 ... mixed~with pearlinglagents., ~ i.c; ~ :c.~
T!~ The knownjhomopolymeric systems~for.making capsules : .,. . have very~low controllability:and,:it.is di~ficult to vary i 5UE3STITI)TE SHE~E~
. .
., . . .
. .
: ~ . . . . .
. -wosl/l9487 PCT/GB91/00930 ~S.~r ~~X~7~3 2 the properties to meet the different requirements of capsule shells for various uses. I~ particular, no synthetic film forming system has previously been prc,posed that provides a satisfactory combination of flexlbility and non-stickiness in khe pr~sence o~ ambient humidity, mechanical strength, and total rapid dissolution in water.
This invention relates to a film-forming polymeric system suitable for preparing capsule shells which can be varied easily according to the particular requir~ments of lo the filling material and j especially, to a system that is flexible, non-sticky and completely water ~oluble.
According to the present in~ention there is provided . a polymeric composition suitable for fo~ming a capsule - shell for con~aining a substantially non-aqueous substance characterised in that the composition comprises a wat~r soluble synthetic film-~orming polymeric composition of cationic and anionic moieties.
The invention also provides a capsule shell in which at least part of the shell is ~ormed ~rom such a composition. For instance the total capsule may be formed from~two shells and at least one, and preferably both, of ,;. the shells are ~ormed of~the~composition. !~ shell may be formed of two parts,~ one-part being formed o~ the defined - .~. composition.and tha other part being Pormed from some other - 25 ,~ capsule-~orming~material. :-; The invention also pro~ides .. filled capsules in which at ~least part of ;the capsule i:- m; .-~.shell, and preferably all the capsule shell, is formed from the compositi~n~ ?~ 5~
:: :.,^s~l s The synthetic~film~^~forming polymeric composition can 30.~J comprise'an3amphoteric pol~mér forme~ by co-polymerisàtion P~ranionic ethylenically unsaturated~monomer with cationic ethylenically.unsaturated monomer and, optionally, nonionic ' t '. ethylenically~unsaturated~;monomer~
,cr It!iO '~O~ .Preferably-Jthef~cationic:;and~;;anionic:moieties in the polymeric composition~are~providèdiby a blend o~ cationic i .. ~ . J''(~-;O polymer and;anionic polymer,':~*heiein~each-~`polymer is water :
soluble;and.--ilm;forming.~ ach `polymer is generally T; ~ U~ ;: 9HE~ET ~ :
. . . . .: , ...... ~.. : . . .. . . .. .
.. . . . - . . .: , - . : .
` . : - :
, . . - ., , - . .. ; . . : . . :. . . --, -.,, . .. .. . .- . .. . .. . . ..
WO91/19487 PCT~GB91/00930 ~.? , ` , " 7 2 7 3 formed by polymerisation of a monomer or monomer blend having the desired ionic character ~anionic or cationic).
If a blend is used, it may be a blend of ionic monomers of the chosen character or a blend with a non-ionic monomer.
Each monomer.or monomer blend i5 usually water-soluble in order to ensure that the polymer is soluble in water.
The preferred cationic monomer, is diallyldimethyl ammonium chloride or other diallyl dialkyl ammonium salt.
.Other suitable cationic monomers include dialkylaminoalkyl-~meth)acrylate or -~meth~acrylamide, eith~r as acid salts or, preferably, quaternary ammonium ~alts, the alkyl groups may each contaSin 1 to 4 carbon atoms and the aminoalkyl group may contain 1 to 8 carbon atoms. Particularly preferred are dialkylaminoethyl (meth)acrylates, dialkylaminomethyl (me~h) acrylamides and dialkylamino-1,3~propyl (méth)acrylamides. These monomers may be present as acid salts or, prefeably, quaternary - ammonium salts~ The dialkyl group is generally dimethyl, e.g., (meth)acrylamideopropyl trimethyl ammonium chloride.
: -20 . To make cationic polym,_rs for use in the invention the cationic monomers.~may be homopolymerised or copolymerised with each other;or.with:a non-ionic monomer,!preferably ~ ~ ~ (meth)acrylamide to give a~:polymer ~ormed o~ cationic ; ~ moieties~optionally with non-ionic moieti~s. :: Thus the ,;.,.25 .cationic~polymers,are usually formed fromi30 to 100% by s ~ ~i weight cationic~monomer:with the:balance bèing~non-ionic.
The~amount of cationic monomer-is usually at~least 50% and often~at-:least;'80% by w~ight~and !most?pre~erably 100~.
ther~suitable~cationicipolymers are.polyethylene imines ao ~ I~;and~ polyamines;~^e.g.,~polyamine:epichlorhydrin polymers.
, r,,~ t~ The,.molecular weight~of~the~cationic polymer should s~f:~ io ~preferably~be.such.that the polymer-hasiintrinsi~ vi~co~ity '0 S~ u~,of~a~;;least 0sl,r~and:preferably at~least-`0.~3 ~I~g ~measured - ek) ~jrl~ O~,.by.:~suspendad ilevel~ viscometer~}at 25C:~in~molàr aqueoussodium chloride,).~ IV can be up to~;-Yfor~ins~ance,tlOdljg or - higher.~but is generally below 7 ~'f~most usually beslow 4 and preferably below 2.5dllg.~-Preferred values, especially for .
Si ~35TITVTE S~EIE~T .
. :
:, , , ~ , , ' ' ~
-. . ... . .. , . ....... : - . .
: - ,.. . . ' " . ' '- ' ' ' . ' , ' ' ' ' , ' polymers of diallyl dimethyl ammonium chloride, are in the range 0.8 to 2.4 dl/g. Such values indicate that preferred molecular weights in the region of around 50,000 to 1,000,000 or 2,000,000 and are preferably above 200,000.
If the molecular weight is too high, the forming composition may have an unacceptably high viscosity at reasonable concentrations of polymer.
The anionic monomers that can be used in the invention include acrylic acid, methacrylic acid, maleic acid, 2-acrylamido-2- methyl propane sulphonic acid (AMPS), sodium vinyl sulphonate, or other ethylenically unsaturated carboxylic or sulphonic acids, often as alkali or other water soluble salts.
To make anionic polymers for use in the invention, anionic monomers may be copolymerised with each other or with non-ionic monomer such as (meth) acrylamide.
The proportions of anionic and nonionic monomer and molecular weights for the anionic polymers may all be similar to those discussed above for the cationic monomers, although it can be desirable for the molecular weight to be a little higher, for instance 500,000 to 10 million, preferably 1 million to 5 million.
When the composition is based on an amphoteric polymer, the molecular weight may be as discussed above for cationic polymers. The amount of non-ionic monomer in the blend is generally 0 to 50%, preferably 0 to 20%, by weight of the total monomer blend.
The polymers must be totally soluble in water.
Accordingly, the polymers are preferably linear homopolymers or copolymers of monoethylenically unsaturated water soluble monomers. However, cationic polymers which have a small degree of cross-linking or branching, or that are formed from monomers that include a small proportion of insoluble monomer, can also be suitable provided they do not significantly affect solubility.
We have found that compositions formed from either ionic type alone do not have satisfactory properties for WO91/19487 PCT/GB9l/00930 f ` ~ .
5 ` 2'0'8i7~2i~;3 water soluble capsules but the use of a blend of ionic types, and pr~ferably the u~;e o~ a blend-of counterionic polymers, gives the opportunity of obtaining a variety of properties that can be selected according to selection of the ratio of cationic and anio~ic moieties.
For instance, polymers of polyvinyl pyrrolidone or polyacrylamide or homopolymers of the anionic moieties described abo~e tend to be too brittle when exposed to ambient humid atmospheres. Polymers of polyvinyl alcohol or homopolymers of the cationic moieties described above tend to have adequate flexibility but to be too sticky when exposed to ambient humid atmospheres. This problem of deliquescence applies also to some of the anionic polymers, and is particularly serious in resp~ct of capsules of, for instance, cosmetic preparations such as bath oils.
By selecting appropriate proportions of the a~ionic and cationic monomers (i.e., moieties~ it is possible, for the first time, to provide a synthetic sheli that has the optimum combination of flexibility and other properties when exposed to an ambient atmosphere and yet'which has a , desiredj usually very'fast,;rateiof dissolution in water.
If:tthe amount o~ cationic monomer is`too'`low'`'thenithe shell .will,.tend to be too brittle.'~ If it` is !too high then the : ~ shell will ,tend `:to be ~too'~'sticky in'.'the ;prèsence o~
,~. ,25 -atmospheric hu~idity. ~ :'^; ~:' ' '' ' ~ ': ' -The~-.molar '-i-ratio`-`cationic:anionic- ~moiéties is .~ ;., ..~preferably-.about 5:1 to,1:1,'.mosti'preferably about 4:1 to The weight ratio ~lcationic:anionic `:;mon`omers is ,~..30.i.,,rgenerally at least~l:l and can bë'up`to 8:1, but 4~i is r~ ;iar~.o~ten sufficient.;~ ~'preferred~rang~e:is 1~`.'5~1 to'~3:1, with ~Lrbest results~.:generally at around:''2:1.''`JThèsel;values a~e `3~ .particularly preferrediwhen the catiônic~:p'olymer is based 3;J~ tv ona'diallyl dimetXyl ammo'n'ium' chloridè (p`r`efërably as-.a '35 ~...rhomo'poly~er).typically having molecular:'w'é'igh'~'in the range .,.. 300,000:*o 1.5'~million,'generally`:'50'0;`000'~o'-'i,000,000 and when the.~anionic polymer~ based on-sodium'acrylate or , suests~uT~ S~EET
methacrylate (generally as homopolymer) typically having molecular weight in the range 10,000 to 5,000,000, preferably around 50,000 to 2,000,000.
The shell-forming composition of the invention generally contains the defined synthetic polymer or polymer blend as the only film forming components. The composition is normally free of natural polymers such as gelatin.
An advantage of the invention is that the film can be formulated wholly from reproducible synthetic polymers.
Another advantage is that it can be formulated to dissolve rapidly and completely, without leaving a scum in the water in which it is dissolved.
Another advantage of the invention is that the films can be heated, for instance during drying or formation of the capsules, without adversely affecting the properties of the film. This is in contrast to gelatin since that is liable to become brittle if it is heated significantly.
The capsule shell can be used to contain a variety of substantially anhydrous fillings. The filling must be substantially anhydrous otherwise the water in it may weaken the shell and may even result in rupture of the shell. Generally the water content of the filling is, initially, below 10% and preferably below 5% and, in particular, the total amount of water that is introduced by the filling must be such that the resultant moisture of the film is sufficiently low, generally below 30%, preferably below 20% and most preferably below 10% even when exposed to an ambient atmosphere.
An advantage of the invention is that the film can easily be formulated to maintain structural integrity even when it does contain these small amounts of moisture.
The filling for the capsule can be liquid or powder and can be for instance selected from for instance detergents, fabric softeners, fragrances, flavour oils, hazardous chemicals such as pesticides, herbicides or other agrochemicals, pharmaceuticals or cosmetics. It is WO ~1/19487 P~/GB91iO0930 f ~ t^t,,~3~
7 ~0~7~-73 particularly preferred that the filling is a cosmetic, in particular bath oil or bath grains. If 'che ~illing is a solid, it will be in particulate form which can, typically, be such small particle size that, if it~ was not encapsulatad, might create a dusting hazard.
In a particularly preferred aspect of the invention a shell is prepared that is suitable for forming a capsule for containing a non-aqueous bath additive such as bath oil or bath grains characterised in that the capsule comprises a water-soluble synthetic ~ilm-forming polymeric compositi~n of cationic and anionic moieties in which the cationic moieties are provided by a cationic polymer and the anionic moieties are provided by an anionic polymer and the weight ratio of cationic to anionic polymer is ~rom 1:1 to 8:1, preferably from 1.5:1 to 3:1, and most preferably around 2.1. The preferred po}ymers are polydiallyl dimethyl ammonium chloride and sodium polyacrylat~ or methacrylate, .having the preferred molecular weights indicated above.
- - The shell capsules may be o~ any slze depending on the requirement of the particular use. For exampl~, for pharmaceutical preparations the capsules must be small enough for swallowi~g and may therefore be below lcm diameter, even below 0.5 cm diameter. Preferably the 25 capsules have a diameter above 0.2c~, less preferably they ; could be microcapsules. For use as containers for bath oil, slightly largPr capsules, such as those having diameter of from lcm to 5cm may be preferred.
The compositions can contain; for instance, dyes 30 and/or pearling agents.
c A variety o~.polymeric films suitable for making capsules were formed from various polymer solutions by drying, and the resulting films were evaluated for 35 characteristics of appearance and stability of ~ilms, water-solubilities at temperatures of from 35-45~, mech~nical strength, and resistance to non-aqueous oils.
.
. .
SUBSTITUTIE~ SHIIEE~
': . : : ' , .
, . :' ' .
:
WO 91/194B7 PCI'/GB91/0093û
~7~7~ ~
A ~ 8 The results are given in Tables 1 and 2.
TA~
POLYMER POLYMER '~FIG~T RATE O~
FILM TYPE RATIO DISSOLUTION AT
. 43-45C (y/~ec~
A_ Polv DADMAC - O 005 Poly DAD~AC/
B Poly~odium acrylat~ 3:1 0.009 _ -~ Pearlinq aa~nt 3:1 _ 0.003 Poly DAD~AC/ inco~plete C Poly~odium acrylate 2:1 ~olubil$ty _+ Pearlinq,agent _ 2:1 PolyDADMAC/
D Poly Sodium Methac~ylate 3:1 0.003_ PolyDADMAC/
E Poly Sodium UethacrYlate2:1_ 0.004 PolyDADMAC/
_ F Polv asrylic acid 2:1 _OOQ07 . .... . . , ., ~ . .. .
!''. ,~ ` . ~ `, . ` ' 7f '~ O .~ rJ ~ J~ f~ ~ f 7~ '!7r;-~ ~ .. '.il ii ~ .; :~ s~ i ~ C . i-~
.~"J '~ 'r~ 3'~ ir' ~ f?~ '3~ ~'3~t~ '.'~ f~ fir?
SU13~TIll~UTE SHEE~
f . ~ 3 t2~i) 8 POLYMEiR ~ SICAL_. STRENGTH
60~ REL._ HUMDIITY _ 30~6 REL. HUMliDITY
Elongation Ma~.~oad Elongation , Mi~x ~oad At ~r~ak At BrQak At Break Load at Point Point Point Break ~ -Point A X 2 12N X 1!2 150N
_ . _ - 1 B I
PearlLng Agent 1/7 4N ~ 1/10 69N
1 X 1/7 6N X 1/3 }07N
+
P~arl~ng . ---20 A~ent 1/7 ~3N X 1/10 60N
. . . _ . I
~: 25 ,,.~ X 3 - . ~ 3N ~ X.1/10 . ;:.~.. 98N
The ~echanical strength tests were carried out at 22C
30 on pol~m~ric film sampleæ having thickness,of from 0.4 to O.5m~. ~ .
A subjective assessment was made of various films.
PolyDADMAC having moleaular weight around IV2 gives a tough opaque flexible film that is very sticky in humid . 35 . atmospheres, whilst polyDADNAC having lower molecular 4 weight forms a weaker ~ilm, that is again sticky in humid ,~ ~atmospheres. Polyacrylic acid (as the ~ree acid) ~of :. molecuIar weight of around 2,000,000 gives a hard brittle ilm that is slightly sticky~in a humid atmosphere whilst 40 its sodium salt gives a brittle film that is slightly less ~ticky in humid at~osphexes. Polyacrylamide gives an inflexibls clear film.
I .
SU~3S~?' 'J~ E~
I .
- .
.. . ...
.:
~o87i73 lo Mixtures of two or three parts by weight polyDADMAC
with one pa~t by weigh~. sodium acrylate or methacrylate homopolymer give flexible opaque ~ilms that are only slightly sticky when wet and which dissolve rapidly a~d fully in warm water. ~hen the film is ~ormed from two parts polyDADMAC and one part polyacrylic acid homopolymer (as free acid) the film is rather brittle.
Capsules may ~e formed for instance from the exemplified polymer compositions or other compositions of the invention by conventional capsule forming methods, including sachet folding or casting. For example using casting, the polymer solution may be cast into semi-spherical shapes and this is followed by sealing two semi-spheres together, for example using aqueous based lS adhesive or by moistening the edges of the ~emi-spherical shells and sealing them together by drying.
Capsules can a}so be prepared by ~aving for example a semi-sphere of water-soluble shell adhered to a non water-insoluble hemisphere. Thus, the capsules do not have to be entirely water-soluble, but may comprise a wall which is partly formed of the water-soluble. synthetic . film-forming polymeric composition according to the .invention.
The non-aqueous filling can be ~illed inside the shell capsules by known techniques, for instance injection into a ~ully ~o~med, sealed shell capsule or by incorporation into the capsule during casting or other manu~acturing stèp.~
j, . . . .. ..
$1J1~ TlJTE S~E~
.
. . . . . ................... . . .. . . . . . -- . .. . . . .
.. ., ,, .. . .... . . -. ,- . :. . . . ,. : . . .
.. .. . . .. ,,: . .. . . ., . .. .... . . . . ... ~ . ~ . . .
. .. . . ~ . , .. . . . . .. . . ,: . . .. ...
.. . . . ; .
..... . .. .. . ... .. ...
~7~273 POLYMERIC FILMS FOR FO MG CAPSULE SHELLS
This invention relates to polymeric films which are suitable for forming shells or capsules for containing various non-aqueous liquids or solids.
Depending on the various uses of the capsule shells, the required properties may vary. At present, capsules are usually made from gelatin. However there are various reasons why it is sometimes undesirable to us~ a naturally occuring material such as gelatinj for instance because of its variable quality or because of a public pre~erence to use a synthetic material rather than an animal-based material. It is known to form capsules from sin~le homopolymeric materials such as polyvinyl alcohol.
However, it is difficult with ~hese polymeric rompositions to produce a product having all the desired properties for each alternative use.
The walls of gel capsules must have high mechanical strength and stability, and resistance to the substance which will be contained in the cap~ule ~hell. It is often necessary that the capsule shells should dissolve rapidly . in .water. .However, the solubility properties can vary ! - considerably from one requirement .to another,~for example the temperature of the aqueous solution:in which the shell . must.dissolve may vary oonsidexably...',:For~example if ~25.~ capsules; ar~ filled with-pesticides -or.herbicides the :. capsule walls must dissolve in cold .water, so that the .. . .. .,. ~
,.~..,pesticidejmay be readily diluted:for application to the land, whereas when the contained ~substance is.,~bath oil, ... ";.;~.;rapid solubility~,must be !achievedmfor ;warm water. In .;..~30....~,,addition,~for..example,~if'~ the.capsule shells~are used for containing.pharmaceutical preparations or cosmetic products .. such .as bath joils,:,:the geljcapsule~mu~t~be'aesthetically acceptable and.~i,therefore~ it.~ is.~,beneficial i~ the lm-forminglpolymericl,material~.-can~be~dyed and/or can be . ...35 ... mixed~with pearlinglagents., ~ i.c; ~ :c.~
T!~ The knownjhomopolymeric systems~for.making capsules : .,. . have very~low controllability:and,:it.is di~ficult to vary i 5UE3STITI)TE SHE~E~
. .
., . . .
. .
: ~ . . . . .
. -wosl/l9487 PCT/GB91/00930 ~S.~r ~~X~7~3 2 the properties to meet the different requirements of capsule shells for various uses. I~ particular, no synthetic film forming system has previously been prc,posed that provides a satisfactory combination of flexlbility and non-stickiness in khe pr~sence o~ ambient humidity, mechanical strength, and total rapid dissolution in water.
This invention relates to a film-forming polymeric system suitable for preparing capsule shells which can be varied easily according to the particular requir~ments of lo the filling material and j especially, to a system that is flexible, non-sticky and completely water ~oluble.
According to the present in~ention there is provided . a polymeric composition suitable for fo~ming a capsule - shell for con~aining a substantially non-aqueous substance characterised in that the composition comprises a wat~r soluble synthetic film-~orming polymeric composition of cationic and anionic moieties.
The invention also provides a capsule shell in which at least part of the shell is ~ormed ~rom such a composition. For instance the total capsule may be formed from~two shells and at least one, and preferably both, of ,;. the shells are ~ormed of~the~composition. !~ shell may be formed of two parts,~ one-part being formed o~ the defined - .~. composition.and tha other part being Pormed from some other - 25 ,~ capsule-~orming~material. :-; The invention also pro~ides .. filled capsules in which at ~least part of ;the capsule i:- m; .-~.shell, and preferably all the capsule shell, is formed from the compositi~n~ ?~ 5~
:: :.,^s~l s The synthetic~film~^~forming polymeric composition can 30.~J comprise'an3amphoteric pol~mér forme~ by co-polymerisàtion P~ranionic ethylenically unsaturated~monomer with cationic ethylenically.unsaturated monomer and, optionally, nonionic ' t '. ethylenically~unsaturated~;monomer~
,cr It!iO '~O~ .Preferably-Jthef~cationic:;and~;;anionic:moieties in the polymeric composition~are~providèdiby a blend o~ cationic i .. ~ . J''(~-;O polymer and;anionic polymer,':~*heiein~each-~`polymer is water :
soluble;and.--ilm;forming.~ ach `polymer is generally T; ~ U~ ;: 9HE~ET ~ :
. . . . .: , ...... ~.. : . . .. . . .. .
.. . . . - . . .: , - . : .
` . : - :
, . . - ., , - . .. ; . . : . . :. . . --, -.,, . .. .. . .- . .. . .. . . ..
WO91/19487 PCT~GB91/00930 ~.? , ` , " 7 2 7 3 formed by polymerisation of a monomer or monomer blend having the desired ionic character ~anionic or cationic).
If a blend is used, it may be a blend of ionic monomers of the chosen character or a blend with a non-ionic monomer.
Each monomer.or monomer blend i5 usually water-soluble in order to ensure that the polymer is soluble in water.
The preferred cationic monomer, is diallyldimethyl ammonium chloride or other diallyl dialkyl ammonium salt.
.Other suitable cationic monomers include dialkylaminoalkyl-~meth)acrylate or -~meth~acrylamide, eith~r as acid salts or, preferably, quaternary ammonium ~alts, the alkyl groups may each contaSin 1 to 4 carbon atoms and the aminoalkyl group may contain 1 to 8 carbon atoms. Particularly preferred are dialkylaminoethyl (meth)acrylates, dialkylaminomethyl (me~h) acrylamides and dialkylamino-1,3~propyl (méth)acrylamides. These monomers may be present as acid salts or, prefeably, quaternary - ammonium salts~ The dialkyl group is generally dimethyl, e.g., (meth)acrylamideopropyl trimethyl ammonium chloride.
: -20 . To make cationic polym,_rs for use in the invention the cationic monomers.~may be homopolymerised or copolymerised with each other;or.with:a non-ionic monomer,!preferably ~ ~ ~ (meth)acrylamide to give a~:polymer ~ormed o~ cationic ; ~ moieties~optionally with non-ionic moieti~s. :: Thus the ,;.,.25 .cationic~polymers,are usually formed fromi30 to 100% by s ~ ~i weight cationic~monomer:with the:balance bèing~non-ionic.
The~amount of cationic monomer-is usually at~least 50% and often~at-:least;'80% by w~ight~and !most?pre~erably 100~.
ther~suitable~cationicipolymers are.polyethylene imines ao ~ I~;and~ polyamines;~^e.g.,~polyamine:epichlorhydrin polymers.
, r,,~ t~ The,.molecular weight~of~the~cationic polymer should s~f:~ io ~preferably~be.such.that the polymer-hasiintrinsi~ vi~co~ity '0 S~ u~,of~a~;;least 0sl,r~and:preferably at~least-`0.~3 ~I~g ~measured - ek) ~jrl~ O~,.by.:~suspendad ilevel~ viscometer~}at 25C:~in~molàr aqueoussodium chloride,).~ IV can be up to~;-Yfor~ins~ance,tlOdljg or - higher.~but is generally below 7 ~'f~most usually beslow 4 and preferably below 2.5dllg.~-Preferred values, especially for .
Si ~35TITVTE S~EIE~T .
. :
:, , , ~ , , ' ' ~
-. . ... . .. , . ....... : - . .
: - ,.. . . ' " . ' '- ' ' ' . ' , ' ' ' ' , ' polymers of diallyl dimethyl ammonium chloride, are in the range 0.8 to 2.4 dl/g. Such values indicate that preferred molecular weights in the region of around 50,000 to 1,000,000 or 2,000,000 and are preferably above 200,000.
If the molecular weight is too high, the forming composition may have an unacceptably high viscosity at reasonable concentrations of polymer.
The anionic monomers that can be used in the invention include acrylic acid, methacrylic acid, maleic acid, 2-acrylamido-2- methyl propane sulphonic acid (AMPS), sodium vinyl sulphonate, or other ethylenically unsaturated carboxylic or sulphonic acids, often as alkali or other water soluble salts.
To make anionic polymers for use in the invention, anionic monomers may be copolymerised with each other or with non-ionic monomer such as (meth) acrylamide.
The proportions of anionic and nonionic monomer and molecular weights for the anionic polymers may all be similar to those discussed above for the cationic monomers, although it can be desirable for the molecular weight to be a little higher, for instance 500,000 to 10 million, preferably 1 million to 5 million.
When the composition is based on an amphoteric polymer, the molecular weight may be as discussed above for cationic polymers. The amount of non-ionic monomer in the blend is generally 0 to 50%, preferably 0 to 20%, by weight of the total monomer blend.
The polymers must be totally soluble in water.
Accordingly, the polymers are preferably linear homopolymers or copolymers of monoethylenically unsaturated water soluble monomers. However, cationic polymers which have a small degree of cross-linking or branching, or that are formed from monomers that include a small proportion of insoluble monomer, can also be suitable provided they do not significantly affect solubility.
We have found that compositions formed from either ionic type alone do not have satisfactory properties for WO91/19487 PCT/GB9l/00930 f ` ~ .
5 ` 2'0'8i7~2i~;3 water soluble capsules but the use of a blend of ionic types, and pr~ferably the u~;e o~ a blend-of counterionic polymers, gives the opportunity of obtaining a variety of properties that can be selected according to selection of the ratio of cationic and anio~ic moieties.
For instance, polymers of polyvinyl pyrrolidone or polyacrylamide or homopolymers of the anionic moieties described abo~e tend to be too brittle when exposed to ambient humid atmospheres. Polymers of polyvinyl alcohol or homopolymers of the cationic moieties described above tend to have adequate flexibility but to be too sticky when exposed to ambient humid atmospheres. This problem of deliquescence applies also to some of the anionic polymers, and is particularly serious in resp~ct of capsules of, for instance, cosmetic preparations such as bath oils.
By selecting appropriate proportions of the a~ionic and cationic monomers (i.e., moieties~ it is possible, for the first time, to provide a synthetic sheli that has the optimum combination of flexibility and other properties when exposed to an ambient atmosphere and yet'which has a , desiredj usually very'fast,;rateiof dissolution in water.
If:tthe amount o~ cationic monomer is`too'`low'`'thenithe shell .will,.tend to be too brittle.'~ If it` is !too high then the : ~ shell will ,tend `:to be ~too'~'sticky in'.'the ;prèsence o~
,~. ,25 -atmospheric hu~idity. ~ :'^; ~:' ' '' ' ~ ': ' -The~-.molar '-i-ratio`-`cationic:anionic- ~moiéties is .~ ;., ..~preferably-.about 5:1 to,1:1,'.mosti'preferably about 4:1 to The weight ratio ~lcationic:anionic `:;mon`omers is ,~..30.i.,,rgenerally at least~l:l and can bë'up`to 8:1, but 4~i is r~ ;iar~.o~ten sufficient.;~ ~'preferred~rang~e:is 1~`.'5~1 to'~3:1, with ~Lrbest results~.:generally at around:''2:1.''`JThèsel;values a~e `3~ .particularly preferrediwhen the catiônic~:p'olymer is based 3;J~ tv ona'diallyl dimetXyl ammo'n'ium' chloridè (p`r`efërably as-.a '35 ~...rhomo'poly~er).typically having molecular:'w'é'igh'~'in the range .,.. 300,000:*o 1.5'~million,'generally`:'50'0;`000'~o'-'i,000,000 and when the.~anionic polymer~ based on-sodium'acrylate or , suests~uT~ S~EET
methacrylate (generally as homopolymer) typically having molecular weight in the range 10,000 to 5,000,000, preferably around 50,000 to 2,000,000.
The shell-forming composition of the invention generally contains the defined synthetic polymer or polymer blend as the only film forming components. The composition is normally free of natural polymers such as gelatin.
An advantage of the invention is that the film can be formulated wholly from reproducible synthetic polymers.
Another advantage is that it can be formulated to dissolve rapidly and completely, without leaving a scum in the water in which it is dissolved.
Another advantage of the invention is that the films can be heated, for instance during drying or formation of the capsules, without adversely affecting the properties of the film. This is in contrast to gelatin since that is liable to become brittle if it is heated significantly.
The capsule shell can be used to contain a variety of substantially anhydrous fillings. The filling must be substantially anhydrous otherwise the water in it may weaken the shell and may even result in rupture of the shell. Generally the water content of the filling is, initially, below 10% and preferably below 5% and, in particular, the total amount of water that is introduced by the filling must be such that the resultant moisture of the film is sufficiently low, generally below 30%, preferably below 20% and most preferably below 10% even when exposed to an ambient atmosphere.
An advantage of the invention is that the film can easily be formulated to maintain structural integrity even when it does contain these small amounts of moisture.
The filling for the capsule can be liquid or powder and can be for instance selected from for instance detergents, fabric softeners, fragrances, flavour oils, hazardous chemicals such as pesticides, herbicides or other agrochemicals, pharmaceuticals or cosmetics. It is WO ~1/19487 P~/GB91iO0930 f ~ t^t,,~3~
7 ~0~7~-73 particularly preferred that the filling is a cosmetic, in particular bath oil or bath grains. If 'che ~illing is a solid, it will be in particulate form which can, typically, be such small particle size that, if it~ was not encapsulatad, might create a dusting hazard.
In a particularly preferred aspect of the invention a shell is prepared that is suitable for forming a capsule for containing a non-aqueous bath additive such as bath oil or bath grains characterised in that the capsule comprises a water-soluble synthetic ~ilm-forming polymeric compositi~n of cationic and anionic moieties in which the cationic moieties are provided by a cationic polymer and the anionic moieties are provided by an anionic polymer and the weight ratio of cationic to anionic polymer is ~rom 1:1 to 8:1, preferably from 1.5:1 to 3:1, and most preferably around 2.1. The preferred po}ymers are polydiallyl dimethyl ammonium chloride and sodium polyacrylat~ or methacrylate, .having the preferred molecular weights indicated above.
- - The shell capsules may be o~ any slze depending on the requirement of the particular use. For exampl~, for pharmaceutical preparations the capsules must be small enough for swallowi~g and may therefore be below lcm diameter, even below 0.5 cm diameter. Preferably the 25 capsules have a diameter above 0.2c~, less preferably they ; could be microcapsules. For use as containers for bath oil, slightly largPr capsules, such as those having diameter of from lcm to 5cm may be preferred.
The compositions can contain; for instance, dyes 30 and/or pearling agents.
c A variety o~.polymeric films suitable for making capsules were formed from various polymer solutions by drying, and the resulting films were evaluated for 35 characteristics of appearance and stability of ~ilms, water-solubilities at temperatures of from 35-45~, mech~nical strength, and resistance to non-aqueous oils.
.
. .
SUBSTITUTIE~ SHIIEE~
': . : : ' , .
, . :' ' .
:
WO 91/194B7 PCI'/GB91/0093û
~7~7~ ~
A ~ 8 The results are given in Tables 1 and 2.
TA~
POLYMER POLYMER '~FIG~T RATE O~
FILM TYPE RATIO DISSOLUTION AT
. 43-45C (y/~ec~
A_ Polv DADMAC - O 005 Poly DAD~AC/
B Poly~odium acrylat~ 3:1 0.009 _ -~ Pearlinq aa~nt 3:1 _ 0.003 Poly DAD~AC/ inco~plete C Poly~odium acrylate 2:1 ~olubil$ty _+ Pearlinq,agent _ 2:1 PolyDADMAC/
D Poly Sodium Methac~ylate 3:1 0.003_ PolyDADMAC/
E Poly Sodium UethacrYlate2:1_ 0.004 PolyDADMAC/
_ F Polv asrylic acid 2:1 _OOQ07 . .... . . , ., ~ . .. .
!''. ,~ ` . ~ `, . ` ' 7f '~ O .~ rJ ~ J~ f~ ~ f 7~ '!7r;-~ ~ .. '.il ii ~ .; :~ s~ i ~ C . i-~
.~"J '~ 'r~ 3'~ ir' ~ f?~ '3~ ~'3~t~ '.'~ f~ fir?
SU13~TIll~UTE SHEE~
f . ~ 3 t2~i) 8 POLYMEiR ~ SICAL_. STRENGTH
60~ REL._ HUMDIITY _ 30~6 REL. HUMliDITY
Elongation Ma~.~oad Elongation , Mi~x ~oad At ~r~ak At BrQak At Break Load at Point Point Point Break ~ -Point A X 2 12N X 1!2 150N
_ . _ - 1 B I
PearlLng Agent 1/7 4N ~ 1/10 69N
1 X 1/7 6N X 1/3 }07N
+
P~arl~ng . ---20 A~ent 1/7 ~3N X 1/10 60N
. . . _ . I
~: 25 ,,.~ X 3 - . ~ 3N ~ X.1/10 . ;:.~.. 98N
The ~echanical strength tests were carried out at 22C
30 on pol~m~ric film sampleæ having thickness,of from 0.4 to O.5m~. ~ .
A subjective assessment was made of various films.
PolyDADMAC having moleaular weight around IV2 gives a tough opaque flexible film that is very sticky in humid . 35 . atmospheres, whilst polyDADNAC having lower molecular 4 weight forms a weaker ~ilm, that is again sticky in humid ,~ ~atmospheres. Polyacrylic acid (as the ~ree acid) ~of :. molecuIar weight of around 2,000,000 gives a hard brittle ilm that is slightly sticky~in a humid atmosphere whilst 40 its sodium salt gives a brittle film that is slightly less ~ticky in humid at~osphexes. Polyacrylamide gives an inflexibls clear film.
I .
SU~3S~?' 'J~ E~
I .
- .
.. . ...
.:
~o87i73 lo Mixtures of two or three parts by weight polyDADMAC
with one pa~t by weigh~. sodium acrylate or methacrylate homopolymer give flexible opaque ~ilms that are only slightly sticky when wet and which dissolve rapidly a~d fully in warm water. ~hen the film is ~ormed from two parts polyDADMAC and one part polyacrylic acid homopolymer (as free acid) the film is rather brittle.
Capsules may ~e formed for instance from the exemplified polymer compositions or other compositions of the invention by conventional capsule forming methods, including sachet folding or casting. For example using casting, the polymer solution may be cast into semi-spherical shapes and this is followed by sealing two semi-spheres together, for example using aqueous based lS adhesive or by moistening the edges of the ~emi-spherical shells and sealing them together by drying.
Capsules can a}so be prepared by ~aving for example a semi-sphere of water-soluble shell adhered to a non water-insoluble hemisphere. Thus, the capsules do not have to be entirely water-soluble, but may comprise a wall which is partly formed of the water-soluble. synthetic . film-forming polymeric composition according to the .invention.
The non-aqueous filling can be ~illed inside the shell capsules by known techniques, for instance injection into a ~ully ~o~med, sealed shell capsule or by incorporation into the capsule during casting or other manu~acturing stèp.~
j, . . . .. ..
$1J1~ TlJTE S~E~
.
. . . . . ................... . . .. . . . . . -- . .. . . . .
.. ., ,, .. . .... . . -. ,- . :. . . . ,. : . . .
.. .. . . .. ,,: . .. . . ., . .. .... . . . . ... ~ . ~ . . .
. .. . . ~ . , .. . . . . .. . . ,: . . .. ...
.. . . . ; .
..... . .. .. . ... .. ...
Claims (11)
1. A polymeric composition suitable for forming capsule shell for containing a substantially non-aqueous substance characterised in that the composition comprises a water soluble synthetic film-forming polymeric composition of cationic and anionic moieties.
2. A composition according to claim 1 in which the cationic moieties are selected from diallyl dialkyl ammonium salts, dialkylaminoalkyl (meth) acrylates and dialkylaminoalkyl (meth) acrylamides and the anionic moieties are selected from ethylenically unsaturated carboxylic or sulphonic acids.
3. A composition according to claim 1 in which the cationic moieties are selected from diallyl dimethyl ammonium chloride and dialkylaminopropyl (meth) acrylamides as acid addition or quaternary ammonium salts, and the anionic moieties are selected from acrylic acid, methacrylic acid and water soluble salts thereof.
4. A composition according to any preceding claim in which the weight ratio of cationic moieties to anionic moieties is from 1:1 to 8:1, preferably 1.5:1 to 4:1.
5. A composition according to any preceding claim which is a blend of a water soluble film-forming cationic polymer with a water soluble film-forming anionic polymer.
6. A composition according to claim 5 in which the cationic polymer is formed from 50 to 100% by weight cationic monomer and 0 to 50% by weight non-ionic monomer, and the anionic polymer is formed from 50 to 100% by weight anionic monomer and 0 to 50% by weight non-ionic monomer.
7. A composition according to claim 5 or claim 6 in which the cationic polymer has molecular weight 200,000 to 2 million and the anionic polymer has molecular weight 500,000 to 10 million.
8. Use of a composition according to any preceding claim for forming all or part of a capsule shell.
9. A capsule shell part or all of which is formed of a composition according to any of claims 1 to 7.
10. A filled capsule having a shell part or all of which is formed of a composition according to any of claims 1 to 7, and wherein the filling in the capsule is substantially non-aqueous.
11. A filled capsule having a shell formed of a composition according to any of claims 5 to 7 and containing as filling a non-aqueous bath additive selected from bath oil and bath grains.
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB909013307A GB9013307D0 (en) | 1990-06-14 | 1990-06-14 | Polymeric films for forming capsule shells |
| GB9013307.5 | 1990-06-14 | ||
| PCT/GB1991/000930 WO1991019487A1 (en) | 1990-06-14 | 1991-06-11 | Polymeric films for forming capsule shells |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2087273A1 true CA2087273A1 (en) | 1991-12-15 |
Family
ID=10677626
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002087273A Abandoned CA2087273A1 (en) | 1990-06-14 | 1991-06-11 | Polymeric films for forming capsule shells |
Country Status (4)
| Country | Link |
|---|---|
| EP (1) | EP0533776A1 (en) |
| CA (1) | CA2087273A1 (en) |
| GB (1) | GB9013307D0 (en) |
| WO (1) | WO1991019487A1 (en) |
Families Citing this family (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5698155A (en) * | 1991-05-31 | 1997-12-16 | Gs Technologies, Inc. | Method for the manufacture of pharmaceutical cellulose capsules |
| AU717113B2 (en) | 1995-11-09 | 2000-03-16 | Health Protection Agency | Microencapsulated DNA for vaccination and gene therapy |
| US6270795B1 (en) | 1995-11-09 | 2001-08-07 | Microbiological Research Authority | Method of making microencapsulated DNA for vaccination and gene therapy |
| JPH10316722A (en) * | 1997-05-15 | 1998-12-02 | Sumitomo Chem Co Ltd | Production of graft copolymer rubber and polypropylene resin composition |
| GB9810236D0 (en) | 1998-05-13 | 1998-07-08 | Microbiological Res Authority | Improvements relating to encapsulation of bioactive agents |
| US6406719B1 (en) | 1998-05-13 | 2002-06-18 | Microbiological Research Authority | Encapsulation of bioactive agents |
| DE10012063A1 (en) | 2000-03-14 | 2001-09-20 | Basf Ag | Soft plasticizer-free capsules for use in pharmaceuticals, cosmetics, detergents or plant protectants are made from a polymers obtained by polymerizing a vinyl ester in presence of a polyether substrate |
| EP1462013A1 (en) * | 2003-03-27 | 2004-09-29 | Cognis Iberia, S.L. | Microcapsules made of an hydroxytyrosol-containing matrix and an coating |
| US9725684B2 (en) * | 2011-02-25 | 2017-08-08 | Milliken & Company | Capsules and compositions comprising the same |
Family Cites Families (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR1605150A (en) * | 1968-12-31 | 1973-03-16 | ||
| AU494547B2 (en) * | 1972-07-10 | 1977-10-20 | Johnson & Johnson | Hydrophilic random interpolymer compositions and method for making same |
| FR2436213A1 (en) * | 1978-09-13 | 1980-04-11 | Oreal | COMPOSITION FOR TREATING FIBROUS MATERIALS BASED ON CATIONIC AND ANIONIC POLYMERS |
| FR2525107B1 (en) * | 1982-04-15 | 1986-04-18 | Firmenich Cie | NEW BATHROOMS IN WATER-SOLUBLE BAGS |
| DE3827561C1 (en) * | 1988-08-13 | 1989-12-28 | Lts Lohmann Therapie-Systeme Gmbh & Co Kg, 5450 Neuwied, De |
-
1990
- 1990-06-14 GB GB909013307A patent/GB9013307D0/en active Pending
-
1991
- 1991-06-11 WO PCT/GB1991/000930 patent/WO1991019487A1/en not_active Application Discontinuation
- 1991-06-11 EP EP19910911159 patent/EP0533776A1/en not_active Withdrawn
- 1991-06-11 CA CA002087273A patent/CA2087273A1/en not_active Abandoned
Also Published As
| Publication number | Publication date |
|---|---|
| EP0533776A1 (en) | 1993-03-31 |
| GB9013307D0 (en) | 1990-08-08 |
| WO1991019487A1 (en) | 1991-12-26 |
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