JPH03234784A - Label adhesive composition containing zirconium - Google Patents

Abstract

PURPOSE: To obtain the subject compsn. having resistance against humidity, water and ice by compounding a Zr compd. and a vinyl polymer with an adhesive based on casein.

CONSTITUTION: A zirconium compd. (e.g. zirconium ammonium carbonate) (A), a casein binder (B) and a vinyl polymer (e.g. vinyl alcohol) (C) are added to an aq. base agent to prepare an aq. label adhesive compsn. The contents of the respective components are set so that A is 0.1-6 wt.%, pref., 0.5-3 wt.%, B is 1.0-30 wt.%, pref., 5-15 wt.% C is 0.1-40 wt.% and water is 40-75 wt.%.

COPYRIGHT: (C)1991,JPO

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention This invention relates to adhesives useful for applying labels to various containers. More particularly, the present invention provides an improved, casein-based, water-resistant label that retains a strong bond between the label attached to the object and the object under normal circumstances, including immersion in water. Concerning adhesives for attaching labels that are durable and resistant to ice. Upon contact with an aqueous base, the adhesive softens and debonds, allowing rapid label release.

PRIOR ART AND THE PROBLEM TO BE SOLVED BY THE INVENTION For many years labels have been made of aqueous solutions or dispersions of natural product binders such as starches, dextrins, gums, proteins, casein and casein derivatives. They have been attached to containers or other objects using adhesive systems. These adhesive systems retain considerable bond if kept dry. However, labels bonded with many water-based adhesive systems can be peeled off by significant moisture or exposure to water.

One type of common label adhesive consists of casein-based water-based adhesive systems. Casein and its derivatives form strong bonds and can be formulated to be water and moisture resistant;
It has been used for adhesion because it can be debonded in the presence of an alkaline source. It is used in particular when a high degree of water resistance is required, for example in the pharmaceutical or brewing industry. Casein-based adhesives have traditionally been used for labeling glass containers and offer the advantage of being able to bond to a wide variety of glass coatings to which other forms of adhesives do not bond well. have Casein derivatives also provide maximum drying speeds and improved workability for cold and very wet bottles.

However, in recent years, casein has become less available and more expensive. Therefore, there has been a need to develop casein-based adhesives that use less casein while still maintaining the required adhesive properties.

SUMMARY OF THE INVENTION The present invention is capable of forming substantial bonds that are resistant to moisture, water, and ice, comprising a zirconium compound, a phosphoprotein binder, such as casein, and a vinyl polymer. An improved labeling adhesive composition. If the vinyl polymer is polyvinyl alcohol, the composition has particularly good adhesive properties. By reinforcing the hydrophilic polymeric solids, such as acrylic polymers, the composition can be made into a label adhesive particularly suitable for use on plastic containers. The adhesive of the present invention provides improved moisture resistant bonding of the label to the container (wet adhesion) and has rapid machining properties for improved adjustment speed. By increasing the adhesive wet speed, line speeds can be increased in the bin process for applying labels to various containers. Additionally, the increased wet tack allows lower casein levels to be used due to lower overall fixation relative to traditional formulations, providing a more cost effective adhesive composition. The adhesives of the present invention also exhibit improved machining properties due to their lower solids levels, making them easier to apply and use.

One aspect of the invention consists of novel casein-based label adhesive compositions. Another aspect of the invention comprises a method of making a casein-based adhesive composition. Yet another aspect of the invention comprises a method of labeling a container using the adhesive composition of the invention.

The present invention comprises an effective amount of an active metal compound, such as a zirconium-containing compound, an effective amount of a phosphoprotein binder, such as casein, and an effective amount of a vinyl polymer.
Belongs to improved water resistance and water resistant label adhesive compositions.

The formulation is particularly well suited for use as a label adhesive when the vinyl polymer is polyvinyl alcohol saturated with polyvinyl acetate. Hydrophilic polymer compositions, such as acrylic polymers that are alkali soluble, make the above formulation suitable for plastic containers made from treated polyolefins, polyvinyl chloride, polystyrene and polyesters such as polyethylene terephthalate, polybutylene terephthalate, etc. Can be used as an adhesive. The adhesives of the present invention are substantially stable to chemical reactions in substantially neutral aqueous adhesive systems. Because casein is sensitive to alkali,
Labels bonded with the adhesive of the present invention are alkaline releasable.

Active metal compounds useful in the present invention are zirconium-containing compounds. Zirconium or zirconium oxide forms ions that interact with the polymer to form bonds. Zirconium forms a very stable oxide with the most important valence state of +4, its marginally stable valence in aqueous solutions. The aqueous chemistry of zirconium is characterized by its high degree of hydrolysis, the formation of polymeric species and the large number of complex ions that can be formed. In aqueous systems, zirconium has a high coordination number and exhibits hydrolysis that slowly reaches equilibrium, so that zirconium compounds in aqueous systems polymerize.

Zirconium compounds are useful because of their ability to complex with carbonyl groups to form insoluble organic compounds. These zirconium organometallic compounds are highly reactive towards low molecular weight unsaturated molecules.

Some of these compounds are useful in a variety of syntheses, and others act effectively as polymerization, hydrogenation, or isomerization catalysts. These compounds include zirconium-containing halides, carbonyl complexes, dinitrogen complexes, alkyl and aryl complexes.

Useful zirconium compounds include zirconium acetate, zirconium hydride, zirconium carbide, zirconium nitride, zirconium diboride, zirconium dodecaboride,
Zirconium phosphide, zirconium chalcogenide, zirconium dioxide, zirconium silicate, zirconium tetrafluoride, potassium hexafluorozirconate, zirconium tetrachloride, zirconium tetrabromide, zirconium tetraiodide, zirconium trichloride, zirconium tribromide, triiodide Zirconium chloride, -zirconium chloride, zirconium oxychloride, hydrous zirconium oxide hydrate, zirconium oxide chloride, anhydrous zirconium oxide chloride, anhydrous zirconium tetranitrate, zirconium carbonate, zirconium ammonium carbonate, zirconium sulfate, bis(-hydrogen phosphorous) Acid) Contains zirconium, zirconium alkoxide, hydroxycarbonate, conium, zirconium dichlorobis(dimethylamide) and zirconium arylamine.

In the present invention, a preferred zirconium compound for use is an aqueous solution of ammonium zirconium carbonate (AZC). The compound leaves a zirconium residue after evaporation of ammonia and carbon dioxide without releasing other cations or anions. AZC is useful in adhesive systems as a crosslinker/insolubilizer, tackifier (with wet tack), and adhesion promoter. AZC can crosslink with carbonyl functionality on casein as well as hydroxyl functionality on vinyl polymers, especially polyvinyl alcohol. Moreover, AZ
C can crosslink with the carbonyl function of the acrylic polymer used in the adhesive composition. This crosslinking effect increases the adhesion of the adhesive system.

The adhesives of the present invention are usually aqueous based and are formed by dissolving or dispersing a binder in ice.

After the adhesive is placed between the label and the object, the bonding agent provides an adhesive bond as water is removed. Common binders in aqueous systems are naturally occurring materials such as starches, dextrins, gums, proteins (both animal and vegetable),
Contains phosphoproteins, shellac, natural rubber, and others.

Other synthetic resin dispersions or emulsions are also commonly used as binders. A preferred binder of the invention is a combination of a synthetic resin and a phosphoprotein, such as casein, a casein derivative or a mixture thereof.

Casein is a mixture of related phosphoproteins found in milk and cheese and is used in the adhesive compositions of the present invention. The exact conditions for casein production vary slightly depending on the type of product desired. However, skin milk is usually heated and mixed with acid. The casein is precipitated and separated from the whey or wash water. Casein can be converted to alkali metal casein by mixing casein with a suitable metal base such as calcium, sodium or potassium hydroxide.

Casein hydrolyzate is produced by contacting a neutralized casein solution with proteolytic enzymes and hydrolyzing casein proteins. Casein provides machining properties and wet tack to the adhesive. Casein is also alkali sensitive, resulting in adhesive binding and rapid label release in the presence of strong bases.

Polymeric synthetic resins are mixed with the zirconium compound and casein in the adhesive compositions of the present invention to impart a variety of properties including water resistance, wet tack, viscosity, easy cleaning, and improved adhesion.

Polymeric components useful in adhesive compositions include vinyl polymers, copolymers and mixtures thereof.

Polymers that can be applied to the present invention include polyethylene, polypropylene, polyvinyl chloride, polystyrene, polytetrafluoroethylene, polyacrylonitrile, polymethyl methacrylate, polyvinyl acetate, polycarbonate, polyester, polyether sulfone, polysulfone, polysulfide, polychloro Contains butadiene and polyvinyl alcohol. Copolymers that can be applied are ethylene vinyl acetate, ethylene acrylic acid, ethylene methacrylic acid, polyacrylic acid, polymethacrylic acid, acrylonitrile/butadiene/styrene (ABS
), ABS/polycarbonate, ABS/vinyl blend,
Acrylate modified styrene/acrylonitrile, acrylic/vinyl blend, polyetherimide, polyvinylidene chloride/vinyl chloride, acrylonitrile/ethylene/styrene, styrene/butadiene, hexafluoropropene/vinylidene fluoride, acrylonitrile/butadiene,
Isobutylene/isoprene, polyvinyl acetate/ethylene.

A preferred polymerization component of the present invention is polyvinyl alcohol (
PVOH). The PVOH in the system interacts with other ingredients to provide wet adhesion, improved water resistance, and particularly in combination with AZC, adhesive legging.
) and guiractant flow to reduce stringing,
It also improves short-breaking properties. PVOH is derived from polyvinyl acetate,
It is produced by substituting the acetate group with a hydroxyl group. This alcoholysis proceeds most rapidly in a methanol/methyl acetate mixture in the presence of a catalytic amount of an alkali or mineral acid. PVOH is readily available from a variety of commercial sources. Particularly preferred are protective colloidal dispersions of PVOH in vinyl polymer emulsions.

The adhesive system of the invention consisting of a colloidal dispersion of ammonium zirconium carbonate, casein binder and PVOH in polyvinyl acetate is particularly well suited for labeling glass containers. The amount of casein used in this formulation of the invention is significantly reduced from the amount used in traditional casein-based adhesives. Additionally, the amount of polymerized solids is reduced (up to about 32%) compared to traditional formulations.

The water-based adhesive of the present invention can be a synthetic hydrophilic adhesive reinforcing polymeric solid in combination with the above components,
This imparts additional properties to the adhesive, making it well suited for plastic container applications. Adhesion reinforcing polymeric solids useful in the present invention include urea-formaldehyde (aminoblast), phenol-formaldehyde (phenoplast), polyvinyl acetate, styrene maleic anhydride polymers, polyvinyl alkyl ethers, acrylate and methacrylate polymers, vinyl acetate/ethylene Including copolymers, etc.

Preferred polymeric materials for use in the plastic label adhesives of this invention are alkali soluble acrylic polymers and copolymers made from alkyl acrylates, alkyl methacrylates, acrylic acid, acrylamide, and other related monomers. These polymers increase bonding strength and cure speed, provide viscosity and short break properties, and provide easy cleaning.

Preferably, the acrylic polymer material is provided in the form of an aqueous emulsion, which can be easily mixed into the aqueous adhesive of the present invention.

A particularly preferred adhesive reinforced acrylic polymer is a vinyl acrylic emulsion copolymer with PVOH colloid,
It shows exceptionally good results due to ease of application and good adhesion and stability. By adding an acrylic polymer to the composition of the invention comprising ammonium zirconium carbonate, casein and P V Ot, a tethered adhesive with improved adhesion to plastics is obtained. The amount of casein used in the embodiment is significantly lower than the amount used in glass labeling adhesives (see Examples below). Additionally, plastic adhesives require less overall volume compared to traditional adhesive formulations. The amount of solids is fairly low (up to 40%).

The novel adhesive compositions of the present invention may also contain nitrogenous substances such as urea, urea compounds and dicyandiamide and mixtures thereof. These nitrogen compounds are added to adhesive compositions to improve machinability, control viscosity, and also affect bond strength. Other ingredients that may be used in the adhesive composition are antifoam agents and preservatives commonly used in biologically degradable natural products comprising the composition.

Optionally, if a hydrophilic polymeric composition is used that has substituents that hydrolyze to increase hydrophilicity, the hydrolyzable group can react with a base. Preferably, ammonia or gas in the form of a solution of ammonium hydroxide is added directly to the adhesive composition.

Other desired ingredients that may be used in the adhesive composition are thickening and suspending additives.

In slightly more detail, the adhesive composition of the present invention is made by dispersing or dissolving the components described above in ice.

Adhesives of the present invention have been prepared with less than 50% water. And because of their low viscosity and ease of application, the novel adhesive compositions of the present invention can contain about 50-75% water by weight based on the aqueous adhesive composition.

An effective amount of zirconium compound, such as zirconium ammonium carbonate, is based on the aqueous adhesive composition about 0.2
-6.0% by weight, preferably about 0°5-3% by weight,
Most preferably about 0.0% for reasons of low viscosity or ease of processing.
It was found that the amount was 5-2% by weight.

The adhesive is based on an aqueous adhesive composition with a
0% by weight casein binder or derivative thereof, preferably about 4-20% by weight casein, most preferably about 5-1% by weight casein
It may contain 5% by weight of casein.

The adhesive composition can contain from about 0.5 to 10% by weight POH, preferably the adhesive contains about 0.56% by weight PVOH.
, most preferably about 0.5-3% by weight PVOH.

The acrylic polymeric solid adhesive reinforcement may be present in an adhesive formulated for labeling plastic containers in an amount sufficient to increase bond strength and rate of bond formation. The adhesive may contain about 0 to 40% by weight acrylic polymer, preferably about 01-30% by weight acrylic polymer, and most preferably about 0.5-20% by weight acrylic polymer.

Nitrogen compounds, such as urea, may be present in amounts sufficient to improve machinability, control viscosity, and enhance bond strength. Such compounds may be present in an amount of about 1 to 15% by weight, based on the aqueous adhesive composition.

Ammonia gas (NH3) or ammonium hydroxide (
NH,OH) can be used to hydrolyze the hydrophilic substituents of the adhesive reinforcing polymer. Although ammonia and ammonium hydroxide are strong bases, they do not attack or react with zirconium.

Antifoams and bacterial inhibitors are generally used in economical concentrations of 1% by weight or less, preferably 0.5% by weight or less.

Thickening and suspending additives are generally used at concentrations of 2% by weight or less, preferably 1% by weight or less.

OPERATIONS AND EFFECTS The following examples are illustrative of the invention and include the best mode. Examples 1-5 (Table 1) are adhesive compositions useful for labeling glass containers.

Examples 6-8 (Table 1) are adhesive compositions useful for labeling plastic containers. The adhesive in the examples is
Manufactured by mixing the ingredients in the directions shown.

Warirashi Koi Table 1 Example 1-5 Water 50.0 Clay thickener/suspending agent 0.7 Urea 6.0 Thiourea 1.0 Casein 14.0 Antifoaming agent 0.3 Ammonia 1.0 Polyvinyl acetate* 21.8 Preservatives
0.1 Zirconium Ammonium Hydrocarbonate 2.5 Water 2.1 Urea 0.5 Total too.

Viscosity (cps) 40,000 pH8,3 50,050,0 0,50,5 8,07,0 49,8 0 45,8 4,0 14,014,014,014,0 0,30,3 1 ,01,01,01,0 21,022,023,027,0 0,10,10,10,1 0,10,10,1 2,53,03,03,0 2,11,01,05, 0 0,51,0+,0 100.0 100.0 100.0 100.032
．． 00025,00022,000 30,0008.
4 8.4 8.4 8.4*PVOH protective colloid coexistence Table ■Example 6-8 Hydrourea casein antifoaming agent Acrylic (alkali soluble) Ammoniathiourea nonionic surfactant Vinyl acrylic* Zirconium carbonate Ammonium preservative Water (preparation) 00 7.0 5.0 0.3 34.0 2.0 0.2 28.0 1.5 2.0 18.0 7.0 5.0 0.2 35.0 2.0 19.8 34.0 2 28.0 1.5 Total viscosity (cps) H 100,0 64,000 100,0 42,000 100,0 45,000 8,35 *P V OH Saturated Example 1-8 has high wet tack properties and the amount of solids to be used in the adhesive formulations of the present invention may be lower than that used in traditional label adhesives. According to the invention,
The amount of solids required in traditional formulations can be reduced by as much as 25%.

Also, because the wet adhesion is improved by the present invention, less casein can be used (40% less casein). Examples 6-8 show that the required amount of casein is even less when the acrylic polymer is added to the adhesive formulation, resulting in a less expensive product. The adhesive compositions of the present invention are also relatively odorless and have low viscosity, making them easier to work with.

A 30 mil bar on a speed glass plate from Test 1 of the Examples, Standard Test, was used in this test. The label using the adhesive of Example 1 began to pull at 1 minute and 30 seconds after application and tore at 3 minutes.
ing) starts again. Labels using the traditional formula* began to pull at 3 minutes and tore at 4 minutes and 15 seconds.

The humidity was approximately 30% at the end of the above test. Under humid summer conditions, Example 1 exhibited a faster prescription time than the traditional formulation because the traditional formulation cured more slowly than under humid conditions due to the higher urea content.

*A typical casein label adhesive contains about 44% solids by weight in the form of about 22% casein and significant amounts of urea and inorganic crosslinkers such as ZnO.

2. Wet Adhesion Test Although the traditional adhesive formulation had a little more friction resistance and was slightly tacky than Example 1, the two adhesives were quite similar to each other. Example 1 did not appear to have a shorter failure. Also, Example 1 appeared to be the same or better in terms of stringing and hanging.

3. Water Resistance Test Example 2 and traditional formulations were tested for water resistance properties. Poly-coated Gatorade bottles and labels were used to conduct this study. A label with the adhesive described above was applied to the bottle and left for 8 days.

The labeled bottles were then placed on ice with the following results. After 1.5 hours in water, the label with the adhesive of Example 1O twisted tightly and peeled off. After 2.5 hours, the label with the traditional adhesive formulation twisted tightly and peeled off. The labels with the adhesive of Example 2 twisted tightly and did not peel off until 5.5 hours after soaking the labeled bottles in water.

Containers to which labels can be attached using the adhesive of the present invention include:
Includes bottles made from materials that are substantially resistant to strong bases. Such materials include glass, plastics such as polyethylene, polypropylene, polystyrene, polyvinyl chloride, treated polyolefins, and the like.

Labels can be made from various thin films of materials, such as paper, plastics, metal foils or other thin materials, and carry characters and symbols that identify the product or provide instructions for use. Preferred materials are paper, plastics such as polystyrene, metal foils such as aluminum, etc. Hybrid labels made from paper, plastic, metal foil or other combinations are also preferred materials. Labels can be engraved with characters and symbols using ordinary commercially available ink.

The detailed description or examples are illustrative of the invention. However, many embodiments of the invention may be made without departing from the spirit and scope of the invention.
The invention lies entirely within the scope of the claims.

Claims (1)

[Claims] 1. A moisturizer comprising (a) an effective amount of a zirconium compound, (b) an effective amount of a casein binder, and (c) an effective amount of a vinyl polymer solution or dispersion in an aqueous base. , an aqueous label adhesive composition capable of forming strong bonds that are resistant to water and ice. 2. The zirconium compound accounts for about 0.1-
6% by weight of the adhesive composition, the casein binder is present in an amount of about 1.0-30% by weight of the adhesive composition, and the vinyl polymer is present in an amount of about 0.1-40% by weight of the adhesive composition. The composition of claim 1, wherein the composition is present in an amount of . 3. The composition of claim 1, wherein said zirconium compound comprises zirconium ammonium carbonate. 4. In an aqueous dispersion, (a) about 0.1-6% by weight of a zirconium compound, (b) about 0.1-30% by weight of a casein binder, and (c) about 0.5% by weight stabilized by polyvinyl alcohol.
1-40% by weight of a vinyl polymer dispersion; and (d) at least about 40% by weight of water. thing. 5. The composition of claim 4, wherein said zirconium compound comprises zirconium ammonium carbonate. 6. in an aqueous dispersion (a) about 40-75% water, (b) about 0.5-3% zirconium compound, (c) about 5-15% casein binder, and (d) An aqueous plastic-label adhesive composition capable of forming a strong bond resistant to moisture, water and ice, comprising about 0.1-40% by weight of an acrylic polymer stabilized by a polyvinyl alcohol polymer. 7. The adhesive composition of claim 6, wherein the zirconium compound comprises zirconium ammonium carbonate. 8. A method for producing an aqueous label adhesive composition capable of forming a strong bond that is resistant to moisture, water, and ice, comprising: (a) a predetermined amount of water, an effective amount of a casein binder, and an effective amount of a casein binder; (b) adding to the adhesive premix an effective amount of a zirconium compound, thereby forming the adhesive composition; The material has quick adhesion and wet adhesive bonding properties. 9. The casein binder is about 1.0-30% of the adhesive composition.
% by weight, the vinyl polymer is in an amount of about 0.1-40% by weight of the adhesive composition, and the zirconium compound is in an amount of about 0.1-6% by weight of the adhesive composition. 9. The method of claim 8. 10. The method of claim 8, wherein the zirconium compound is zirconium ammonium carbonate. 11. A method for attaching a label to a glass container, comprising the steps of: (a) forming a layer of the adhesive of claim 4 on the label; (b) bringing the container and the label into contact; The adhesive forms a bond between the label and the container. 12. A method for attaching a label to a plastic container, comprising the steps of: (a) forming a layer of the adhesive of claim 6 on the label; and (b) bringing the container and the label into contact. The adhesive forms a bond between the label and the container.