Description:FIELD OF THE INVENTION:
The present invention relates to an environment-friendly and low volatile organic compound (VOC) water-base lamination adhesive composition. Specifically the water-base adhesive composition comprises at least one acrylic monomer, at least one free radical initiator to initiate the polymerisation of the acrylic monomers, at least one anionic surfactant, at least one non-ionic surfactant, an antimicrobial compound, a filler, and water.

BACKGROUND OF THE INVENTION:
The adhesive compositions present today for lamination are usually solvent type adhesives based on polyurethane. While such solvent type adhesives show good adhesion ability, the volatile organic solvents present in the adhesive composition gets released to the environment during the adhesive application, hence creating environmental hazards by polluting the air.

In order to mitigate these environmental effects several solvent-free polyurethane or water-base polyurethane adhesives have been developed in the recent times. However, they lack heat-resistance properties especially during laminating paper to BOPP and Polyesters. Also, conventional water-base adhesives have got low bond-strength while laminating with metallic substrates.

US20110143157A1 discloses an aqueous adhesive composition for dry lamination and a laminate fabricated using the same, which comprises an aqueous resin dispersion and a water-dispersible isocyanate; the aqueous resin dispersion is prepared using an unsaturated monomer having a hydroxyl group, an alkyl acrylic and/or methacrylic ester, an additional unsaturated monomer in the presence of an emulsifier having a phosphate group.

KR20170045484A discloses a water-borne acrylic emulsion-type adhesive, where the water-borne acrylic emulsion-type adhesive comprises an acrylic resin containing latex, a crosslinking monomer, oxidizing and reducing catalysts, nano clay and a latex mixture.

OBJECTS OF THE INVENTION:
The principal objective of the present invention is to provide a multi-use water-base lamination adhesive with better HR (heat-resistance) properties.

Another objective of the present invention is to provide a multi-use water-base lamination adhesive with better lamination/bond strength properties

Another objective of the present invention is to provide a multi-use water-base lamination adhesive with better storage stability

A further objective of the present invention is to provide a multi-use water-base lamination adhesive which can be made one or two component

Other objectives, features and advantages will become apparent to those skilled in the art from the detailed description and the appended claims.

SUMMARY OF THE INVENTION:
The present invention relates to an environment-friendly water-base lamination adhesive composition which is formulated both as a “one-component” adhesive and a “two-component” adhesive based on its application to primary and secondary substrates.

The present invention provides a “one component” water-base adhesive composition. The composition comprises at least one acrylic monomer, at least one free radical initiator to initiate the polymerisation of the acrylic monomers, at least one anionic surfactant, at least one non-ionic surfactant, an antimicrobial compound, and additives.

Specifically the present invention is directed towards water-base adhesive compositions containing ethyl acrylate, acrylic acid and acetoacetoxyethyl methacrylate (AAEM) as principal components.

The present invention also discloses a “two-component” adhesive composition, where an isocyanate based curative is added as a second component to the water base adhesive composition as described here as “one component”.
The two component lamination adhesive formula is specifically useful for flexible packaging applications, particularly for laminating paper to aluminum foil, metallized cast polypropylene (CPP) films, heat-sealable biaxially oriented polypropylene (BOPP) films, polyester films.

The single component lamination adhesive formula is useful to bond various plastic films to 30 to 70 gsm coated and uncoated paper.

DETAILED DESCRIPTION OF THE INVENTION:
The preferred embodiments of the present invention will be described in detail with the following disclosure and examples. The foregoing general description and the following detailed description are provided to illustrate only some embodiments of the present invention and not to limit the scope of the present invention. The invention is capable of other embodiments and can be carried out or practiced in various other ways.

Unless otherwise specified, all the technical and scientific terms used herein have the same meaning as is generally understood by a person skilled in the art pertaining to the present invention. All the patents, published patent applications referred to throughout the entire disclosure herein, unless specified otherwise, are incorporated by reference in their entirety.

In one embodiment, the present invention provides a “one component” water-base adhesive composition. The composition comprises at least one acrylic monomer, at least one free radical initiator to initiate the polymerisation of the acrylic monomers, at least one anionic surfactant, at least one non-ionic surfactant.

Additives that may be included in the water-base adhesive composition of the present invention may include an antimicrobial compound, a filler, a pH adjusting agent and water.

Specifically the present invention is directed towards water-base adhesive compositions containing acetoacetoxyethyl methacrylate (AAEM), ethyl acrylate, and acrylic acid as the principal components.

The Acetoacetoxyethyl Methacrylate (AAEM) present in the water-base adhesive composition of the present invention is about 2.00% by weight to 2.25% by weight of the total weight of the adhesive composition.

The acrylic based monomer present in the water-base adhesive composition of the present invention is about 38% by weight to 40% by weight of the total weight of the adhesive composition.

The anionic surfactant present in the water-base adhesive composition of the present invention is about 0.20% by weight to 0.25% by weight of the total weight of the adhesive composition.

The non-ionic surfactant present in the water-base adhesive composition of the present invention is about 0.16% by weight to 0.20% by weight of the total weight of the adhesive composition.

The antimicrobial compound present in the water-base adhesive composition of the present invention is about 0.08% by weight to 0.10% by weight of the total weight of the adhesive composition.

The free radical initiators may be present in the water-base adhesive composition of the present invention is as known in the art, preferably two initiators are used i.e. about 0.05% by weight of tert-Butyl hydrogen peroxide (TBHP) of the total weight of the adhesive composition, and about 0.30% by weight of Potassium Peroxide Sulphate (K2S2O8) of the total weight of the composition.
The one component water based acrylic based emulsion composition is used to bond flexible plastic films in a thickness of typically 6 micron to 18 micron to 30 to 70 gsm coated and uncoated paper. The plastic films are typically made of materials such as PVC, plasticized PVC, ethylene/vinyl acetate copolymers (EVA), or thermoplastic polyolefins, acrylonitrile/styrene/acrylic ester, polyurethanes, polyamides, polymethacrylates, polycarbonates, polyethylene terephthalate (PET), metallised CPP, metallised BOPP, metallised PET film and polymer blends thereof.

In another embodiment the present invention also provides a “two-component” adhesive composition, where an isocyanate based curative is added as a second component to the water base adhesive composition as described here as “one component”.

The preferred isocynate based curative for the present invention includes hydrophylically modified polyisocyanates, more preferably hydrophylically modified aliphatic polyisocyanates and most preferably hydrophylically modified aliphatic polyisocyanate based on hexamethylene diisocyanate (HDI).

Hydrophylically modified aliphatic polyisocyanate based on hexamethylene diisocyanate (HDI) shows satisfactory reproducibility, is easily transferred to the adhesive mixture, and helps to attain a good pot life.

In the “two component” water-base adhesive composition, the “one component” composition is mixed with the isocyanate based curative at a ratio of 100 parts by weight to 2 parts by weight.

The two component lamination adhesive formula is specifically useful for flexible packaging applications, particularly for laminating paper to aluminum foil, metallized cast polypropylene (CPP) films, heat-sealable biaxially oriented polypropylene (BOPP) films, and polyester films.

Best mode of the invention
In a preferred embodiment, the present invention provides a one-component water-base adhesive formula with the following composition given in Table 1.

Table 1
One-component water-base adhesive composition
Ingredient Amount (wt%) Functionality
Acetoacetoxyethyl Methacrylate (AAEM) 2.2 Acrylic Monomer
Ethyl Acrylate Monomer 38.03 Acrylic Monomer
Acrylic Acid 1.1 Acrylic Monomer
Sodium alkyl benzene sulfonate 0.22 Anionic surfactant
tert-Butyl hydrogen peroxide (TBHP) 0.05 Initiator
Polyoxyethylene Alkyl aryl ether 0.18 Non-ionic surfactant
Ammonium Solution 0.45 pH adjusting agent
Sodium Bicarbonate 0.1 Filler
Potassium Peroxide Sulphate (K2S2O8) 0.32 Initiator
Bioban 551 S (combination of combination of 2-methyl-4-isothiazolin-3-one and 2-methyl 1,2 benzisothiazolin-3-one) 0.1 Antimicrobial compound
Demineralised Water 57.25 Demineralised Water
Total 100

Examples:
The present disclosure will now be explained in further detail by the following examples. These examples are illustrative of certain embodiments of the invention without being limited to the specific formulations, and methods given here.

Example 1 :
The one-component water-base adhesive composition was prepared with the ingredients in the weight ratio as given in Table 1.

A laminate was formed by using the one-component water-base adhesive composition as prepared in this Example 1.

The method of formation of the laminate comprises applying the one-component adhesive composition as prepared here in this Example to a 12 micron thin Polyethylene terephthalate (PET) film substrate. A 50 gsm Chromo Art paper was brought together to the adhesive applied PET film substrate, and then cured for 24 hours at 40°C to form the laminate.

1. Bond Strength
The laminate so formed as said in Example 1, test was conducted to analyse the bond strength of the laminate.

The bond strength of the laminate as formed above is found as fibre tear.

2. Heat resistance
A test was conducted to measure the heat resistance of the laminate of Example 1 at 150°C, dwell time of 2 seconds, and a pressure of 3 Kg/cm2.

No blister formation occurred in the laminate as formed above in between the polymeric layer and the chromo art paper.

Example 2 :
The two-component water-base adhesive composition was prepared by mixing 100 parts of the composition as given in Table 1 with 2 parts of hydrophylically modified aliphatic polyisocyanate based on hexamethylene diisocyanate (HDI) as the isocyanate based curative.

A laminate was formed by using the two-component water-base adhesive composition as prepared in this Example 2.

The method of formation of the laminate comprises applying the two-component adhesive composition as prepared here in this Example to a 12 micron thin Polyethylene terephthalate (PET) film substrate. A 70 gsm Chromo Art paper was brought together to the adhesive applied PET film substrate, and then cured for 24 hours at 40°C to form the laminate.

1. Bond Strength
Once the laminate is formed as said in Example 2, test was conducted to analyse the bond strength of the laminate.

The bond strength of the laminate as formed above is found as fibre tear.

2. Heat resistance
A test was conducted to measure the heat resistance of the laminate of Example 2 at 150°C, dwell time of 2 seconds, and a pressure of 3 Kg/cm2.

No blister formation occurred in the laminate as formed above in between the polymeric layer and the chromo art paper.

Other embodiments and uses of the invention will be apparent to those skilled in the art from consideration of the specification and practice of the invention disclosed herein. It is intended that the specification and examples be considered as exemplary only, with a true scope and spirit of the invention being indicated by the following claims.

Claims:We claim:
1. A water-base adhesive composition comprising:
a. Acetoacetoxyethyl Methacrylate (AAEM);
b. at least an acrylic based monomer other than Acetoacetoxyethyl Methacrylate (AAEM);
c. at least a surfactant; and
d. at least an initiator;
wherein the above ingredients and additives are mixed together with demineralised water,
wherein the water-base adhesive composition is a one-component water-base adhesive.

2. The water-base adhesive composition according to claim 1, wherein the acrylic based monomer is selected from acrylic acid, Ethyl Acrylate Monomer, or combinations thereof, wherein the proportion of acrylic based monomer present is 10 to 30% by weight of the total water-base adhesive composition.

3. The water-base adhesive composition according to claim 1, wherein the surfactant is selected from an anionic surfactant, a non-ionic surfactant, or combinations thereof.

4. The water-base adhesive composition according to claim 1, wherein the initiator is a combination of tert-Butyl hydrogen peroxide (TBHP), and Potassium Peroxide Sulphate (K2S2O8).

5. The water-base adhesive composition according to claim 1, wherein the additives include a filler such as Sodium Bicarbonate, a pH adjusting agent such as Ammonium Solution, and an antimicrobial agent such as a combination of 2-methyl-4-isothiazolin-3-one and 2-methyl 1,2 benzisothiazolin-3-one (Bioban 551 S).

6. A method of laminating a flexible film substrate to a coated or uncoated paper substrate comprising the steps of:
applying the adhesive composition of claim 1 to the flexible film substrate;
bringing together the adhesive applied flexible film substrate in alignment with the coated and uncoated paper substrate;
eliminating water from the adhesive composition; and
curing the lamination by heating.
7. A two component water-base adhesive composition comprising: a first component, and a second component,
wherein the first component includes:
a. Acetoacetoxyethyl Methacrylate (AAEM);
b. at least an acrylic based monomer other than Acetoacetoxyethyl Methacrylate (AAEM);
c. at least a surfactant; and
d. at least an initiator;
wherein the first component includes other additives and demineralised water,
wherein the second component is a hydrophylically modified isocyanate based curative.

8. The two-component water-base adhesive composition according to claim 7, wherein the hydrophylically modified isocyanate based curative is hydrophylically modified aliphatic polyisocyanate based on hexamethylene diisocyanate (HDI).

9. The two-component water-base adhesive composition according to claim 7, wherein the two-component water-base adhesive composition is formed by adding 2 parts by weight of the second component to 100 parts by weight of the first component.

10. A method of laminating a flexible substrate to a coated or uncoated paper substrate comprising the steps of:
applying the two-component adhesive composition of claim 7 to the flexible substrate;
bringing together the coated and uncoated paper substrate in alignment with the adhesive applied side of the flexible substrate;
eliminating water from the adhesive composition; and
curing the lamination by heating. ,