GB2463735A

GB2463735A - Fully biodegradable adhesives

Info

Publication number: GB2463735A
Application number: GB0817839A
Authority: GB
Inventors: Paul Howard James Roscoe
Original assignee: Individual
Current assignee: Individual
Priority date: 2008-09-30
Filing date: 2008-09-30
Publication date: 2010-03-31
Also published as: GB0817839D0

Abstract

The invention relates to a range of fully biodegradable and compostable adhesives, which will find major use in attaching labels and tapes to the packaging of supermarket goods. In addition the adhesives can be used in the fabrication of cartons, boxes and envelopes. These adhesives comprise of a proprietary copolymer formed by polymerisation of an alkyl polyglycoside maleic acid ester with a vinyl monomer mixed with an aliphatic hydrocarbon resin dispersion. The desired properties of the adhesive are enhanced by the incorporation of a range of additives which include synthetic proteins, sugars, metallic carboxylates, polyhydric alcohols and most importantly wheat based protein copolymers. Premature microbial degradation of the adhesives is prevented by the inclusion of an isoazolinone. When these components are mixed together in critical stoichiometric proportions ,a synergistic effect occurs resulting in a range of novel adhesives which for the first time pass all criteria for biodegradable materials testing according to European Packaging standard.

Description

Fully biodegradable adhesives There are grave concerns in the UK about large amounts of land being used as waste fill sites and it is predicted that in the next few years such land fill sites will be exhausted and that government legislation will be introduced to combat the problem by the introduction of financial penalties for the disposal of non-biodegradable materials.

By the use of these adhesives (which typically represent between 0.001 and 0.05 percent by weight of a typical item which requires such adhesives during manufacture), huge savings can be made both in financial and environmental terms. In essence, these adhesives are natural products and will be returned to the ecosystem with the minimum effect on waste filled sites and in general, the eco-system.

Adhesives are all around us. They are used to fabricate a large number of everyday products which may be soft or hard, washable, degradable, transparent or colorful. Up to 100,000 chemicals are in use in the EU, but for 99% (by volume) there exists only sketchy data about their effects on the environment Globally, 35 % of the world's adhesives are used in the packaging industry.

A new regulatory system called REACH (Registration, Evaluation and Authorisation of Chemicals) will change this, providing us with the information we need to use chemicals safely. Currently, the European Parliament and the Council are in the process of adopting this ground-breaking piece of legislation. They are pushing hard for this new chemicals policy in order to offer a higher level of protection to consumers, workers and the environment in the decades to come.

Accelerating worldwide economic growth is increasing pressure on the global environment Developing clean technologies -or eco-innovation' -is essential if we are to reduce these pressures and conserve increasingly scarce natural resources.

There has been innovation in industries such as the packaging sector for the development and use of ceo-friendly and sustainable materials for the manufacture of a wide range of items, components and finished articles. Many of these have been made using biodegradable materials,but historically the adhesives used in their fabrication which have been non-biodegradable, non-compostable, non-disintegrable and toxic.

There are many modern adhesives which use natural products as their major component such as starch and casein. These natural products are well known for their ceo-friendliness but adhesives containing them do not have the technical specification to meet the performance criteria necessazy for packaging adhesives. These criteria include: * resistance to deep freezing, * oxygen permeability and * adhesion to adhesion resistant substrates, * adhesion in hostile environments such as freeze thaw conditions * high shear adhesion failure temperatures.

The above physical properties of any adhesive are often intrinsic to the structure of the organic molecule and in particular the side chains and functional groups attached to the main carbon chain. These structures are also of paramount importance in the mechanism of biodegradation in which active bacteria can cause bond cleavage and depolymersation of the carbon chain.

In Europe, about 60% of the adhesive industry is dominated by the applications of pressure sensitive adhesives and about 80% of these applications concern the product labeling industry.

In 2000, adhesives accounted for about 20 billion dollars worth of sales throughout European and American markets.

Environmental concerns are driving the advancement in adhesive technology and standards such as the ISO 14001 series are seeking companies to develop more environmentally responsible attitudes are to produce "eco-friendly products".

Some of the desirable features of such adhesives are as follows: * Ultimate disposability * Very low VOC content * The use of renewal resource materials used in their manufacture * Biodegrability * Compostability * Repulpability * Recycleability This invention relates to a range of fully biodegradable and fully compostable adhesives, which will find major use in a wide range of industries but is primarily aimed at the packaging and labeling industries.

These adhesives are comprised of two specialist main polymeric entities namely a propriety copolymer formed by polmerisation of an alkyl polyglcoside maleic acid ester with a vinyl monomer and a propriety water based resin dispersion.Both of these polymeric entities have intellectual property right protection, however such stand-alone preparations are not fully biodegradable and have not passed the European standards criteria for biodegradable materials testing.

Novel adhesives are formed when the above two components are carefully blended together in very strict stoichiometric proportions together with a range of additives.

This invention concerns the introduction of a range of other ingredients which render the adhesive fully biodegradable.

With the exception of the two msun polymer components, most of the other additives used in this invention have never been used before in the adhesive or associated industries.

The range of additives included in this invention rendering the biodegradability include: * A synthetic protein mimic * A synthetic protein mimic -wheat coplymer * Asugar * A metal carboxylate * A polyhyric alcohol * A buffer * A wetting agent * A preservative Synthetic protein mimic These are more readily available than their natural counterparts and offer some advantages over natural proteins.

The incorporation of a synthetic protein has been found to enhance the wetting properties, increase the ability of the adhesive to readily form films and to increase film elasticity. More importantly however is the distinct advantage over conventional adhesives in that the inclusion of a synthetic protein fucilities a catalytic effect in the biodegradation process. Once again this is due to the inclusion of a nitrogen containing group within the heterocycic ring Examples of such proteins used in this invention include N-vinyl pyrrolidone and glutamine derived from wheat Synthetic protein mimic -wheat copolymer This copolymer controls the degree of tackiness of the adhesive and the two keys features to its inclusion are the concentration in which it is added and its molecular weight When used at concentrations between 5 and 35 parts per polymer, it is found not to interfere with the biodegradation process and may in fact probably enhance the process.

Examples of such copolymers used in this invention are the Coltide HPVP range of A sugar Both monosaccharides and disaccharides can be used in this invention. These constituents contribute to the film forming properties and elasticity of the adhesive. In addition because of the spontaneous intramolecuar interaction between the hydroxyl and aldehydic groups, a pathway for biodegradation is provided.

Examples of monosaccharides which can be used in this invention are glucose, fructose and sorbose.

Examples of suitable disaccharides include sucrose, lactose and maltose.

Metal carboxylates Salts of transition metal elements including both saturated and unsaturated carboxylic acids are also used in this invention.

Specifically, transition metal salts of cobalt, zinc and iron and specifically octadecanoic (stearic) acid, hexadecanoic (palmitic) acid and tetradecanoic (myristic) acid. These have proven to be effective catalysts in the biodegradation process when incorporated in small concentrations. When added in concentrations between of between 0.09 and 0.25% and in the presence of heat or light, these metal carboxylates trigger the degradation process of the adhesive film.

Polyhydric alcohols Polyhydric alcohols or polyols derived from sugars enhance the degree of hydrogen bonding between adjacent hydroxyl groups and greatly increase the ease of biodegradability of such adhesives.

Examples include glycerol, lactilol, mannitol, sorbitol and xylitoL Buffer On mixing the components of the adhesive slight changes in pH may occur and these changes may result in destabilisation of the polymeric mix.Destabilisation is prevented by the addition of a buffer solution consisting of a di or tn hydroxyl carboxylic acid. The presence of the hydroxyl groups ensures that no retardation in the biodegradation process occurs.

Examples of buffers used include citric and tartanic acid both of which can be added Wetting agent A wetting agent when added to the mix lowers its surface tension and thus increases the adhesives spreadability.

The adhesives in this invention use a fully biodegradable wetting agent such as dioctyl suiphosuccinate and are manufactured by Lankem Limited under the trade names of KemsurfOT-60 and Kemsurf OT-70.

The most effective results were obtained when the wetting agent was added at levels between 0.05 and 2.0 %.

Preservative Adhesives composed largely of natural materials are prone to bacterial attack with the resultant loss of desirable adhesive properties. Examples of such biocides used in this invention are alkyl isoazolinones such as methyl, propyl, butyl and methyicloro isoazolinones or a combination thereof.

A blend of methyl and methylchloro isoazolinones gave the best results. These are available from Thor Specialities (UK) Ltd under the trade name of"Acticide MV" The most effective results were obtained when added in concentrations of between 0.05 and 0.25%.

This invention therefore concerns a combination of additives which when mixed with a propriety copolymer fonned by polmerisation of an alkyl polygicoside maleic acid ester with a vinyl monomer and an aliphalic hydrocarbon resin dispersion, in a certain order and when mixed in certain proportions, produce a fully biodegradable adhesive. It is the unique combination of these ingredients which combine together to have a dramatic synergistic effect which results in complete biodegradation.

Examples

Example 1

Propriety water based resin dispersion mixed with a copolymer formed by polymersation of an alkyl polygicoside maleic acid ester with a vinyl monomer such as Ecostix produced by EcoSynthetix 100 parts Propriety hydrocarbon resin such as "Tacolyn" produced by Eastman parts Cobalt stearate 2 parts Methylcioro isoazolinone 0.01 part Dioctyl suiphosuccinate 0.01 part

* Example 2

Propriety water based resin dispersion mixed with a copolymer formed by polmersation of an alkyl polyglcoside maleic acid ester with a vinyl monomer such as Ecostix produced by EcoSynthelix 100 parts Propriety hydrocarbon resin such as "Tacolyn" produced by Eastman 22 parts Propriety hydrolysed wheat protein and polyvinyl pyrrolidone copolymer such as "Coltide HPVP" produced by Croda 17 parts Cobalt stearate 2 parts Methylciom isoazolinone 0.01 parts Dioctyl suiphosuccinate 0.01 parts

Example 3

Propriety water based resin dispersion mixed with a copolymer formed by polmersation of an alkyl polygicoside maleic acid ester with a vinyl monomer such as Ecostix produced by EcoSynthelix 100 parts Propriety hydrocarbon resin such as "Tacolyn" produced by Eastman 22 parts Sucrose syrup 17 parts Poly-N-vinyl pyrrolidone 17 parts Propriety surfactant 1 parts Propriety defoaming agent 1 parts

Example 4

Propriety water based resin dispersion mixed with a copolymer formed by polmersalion of an alkyl polygicoside maleic acid ester with a vinyl monomer such as Ecostix produced by EcoSynthetix 100 parts Propriety hydrocarbon resin such as "Tacolyn" produced by Eastman parts Poly-N-vinyl pyrrolidone 8 parts Glucose liquid 6 parts Tartaric acid powder I part Cobalt stearate I part

Example 5

Propriety water based resin dispersion mixed with a copolymer formed by polmersation of an alkyl polygicoside maleic acid ester with a vinyl monomer such as Ecostix produced by EcoSynthetix 100 parts Propriety hydrocarbon resin such as "Tacolyn" produced by Eastman 22 parts Propriety hydrolysed wheat protein and polyvinyl pyrrolidone copolymer such as "Coltide HPVP" produced by Cmda 8 parts Sorbitol 70 % liquid 5 parts Citric acid 55% aqueos solution 5 parts t

Claims

Claim set l.A biodegradable adhesive comprising of a mixture of a propriety copolymer formed by polmerisation of an alkyl polygicoside maleic acid ester with a vinyl monomer and a propriety aliphatic hydrocarbon resin dispersion,the biodegrability, compostability and eco-toxicity of which is further enhanced by the incorporation of a range of additives.
2. An adhesive as in Claim I, in which a synergistic effect occurs on the inclusion of a range of additives resulting in an adhesive, which for the first time passes all criteria tests (EN 13432) for biodegradability, compostabilty and eco-toxity.
3. An adhesive as in Claim I which consists of some or all of: * A synthetic protein mimic * A synthetic protein mimic -wheat coplymer * A sugar * A metal carboxylate * A polyhyric alcohol * A buffer * A wetting agent * A preservative * .* * * * * ** **. * * * *. * **** * S ** SISS..... ** *. * n *S
4. An adhesive as in Claim 3 consists of * A synthetic protein mimic, namely poly-N-vinyl pyrrolidone * A synthetic protein mimic -wheat copolymer namely,Coltide HPVP * A sugar namely, glucose or sucrose * A metal carboxylate namely, cobalt stearate * A polyhyric alcohol namely sorbitol * A buffer namely citric or tartaric acid * A wetting agent namely Kemsurf OT-60 or Kemsurf OT-70 * A preservative namely methyl isoazolinone or chloro methyl isoazolinone * ** * S S * S. S... * S *. * S I...S a S SI S. * .S