MXPA00011315A - Adhesive and coating formulations for flexible packaging - Google Patents

Abstract

Formulations containing reaction products of epoxy compounds with active hydrogen-containing compounds such as amines and carboxylic acids having unique adhesive and other properties are disclosed. Laminates of various films and/or foils made with such formulations have desirable properties for packaging of food and other products.

Description

ADHESIVE AND COATING FORMULATIONS FOR FLEXIBLE PACKAGING BACKGROUND OF THE INVENTION Laminated products of film on film and film on sheet are used in the packaging of various food products and other industrial products. Adhesives and coatings are used to make these composite structures, since it is often difficult to achieve satisfactory bonding of films of different compositions using co-extrusion or thermal welding techniques. Sheet products of this type must have several key performance characteristics such that packaged items can be safely placed, transported and stored until they are used by the consumer. During the various stages of packaging, the products in the form of sheets are subjected to various processes such as printing, bagging, filling, boxing, transport, etc. For more than 20 years, formulations based on polyurethanes produced mainly by the reaction of polyols and polyisocyanates have been employed. These products were mainly solutions of polyester and / or polyether polyol solvents which reacted adequately with aromatic isocyanates such as MDI (diphenylmethane diisocyanate), TDI (toluene diisocyanate) and the many products of the reaction of diisocyanates. Due to increased awareness regarding environmental protection, such solvent solutions were replaced by polyurethanes without solvents in most applications. While some water-based laminated structure adhesives are known, most are provided as 100% solid systems. These systems are essentially similar to products that carry solvents but contain significant amounts of free monomeric isocyanates. Its volatility, the health effects of such isocyanates and their reaction products with atmospheric humidity that depend on the formation of aromatic diamines have been a concern, especially in the case of food packaging. Almost all of the adhesives and most of the coatings used in the industry are based on polyurethanes. When films that are considered to have high barrier capacity, that is, that do not allow the passage of gases freely through them, must be laminated, such adhesives containing free isocyanate cause a problem of appearance. Trace amounts of moisture present on the film surfaces react with the isocyanates in a well-known reaction producing carbamic acid. This unstable acid releases carbon dioxide gas. Due to the impermeable nature of the films, the carbon dioxide is trapped in the form of bubbles causing a problem of appearance. Lamination of adhesive compositions comprising conjugated diene block copolymers with epoxy end groups and adhesion resins that are cured with curing agents BF3 is known. However, the adhesion values obtained for various substrates using such adhesive compositions are limited, ranging from 25 grams / 2.54 cm (25 grams / inch) to 270 grams / 2.54 cm (270 grams / inch). The unsatisfactory adhesion may be due to the presence of a large olefinic medium block. Formulations with slightly higher bond strengths employ base polymers having viscosities of 64,000 pascal seconds or more and are impossible to handle at temperatures of 25 ° C to 75 ° C. Polyurethane compositions with epoxy resins are also known for applications of lamination. However, the need for radiation curing of such compositions results in a huge cost due to the expensive nature of UV curing lamps. In addition, the reaction products of the photoinitiators employed in such formulations provide an unpleasant odor to the finished sheet product. A composition comprising a polyester mixed with an epoxy resin but cured with polyisocyanates is also known. The potential for unreacted monomeric isocyanates and their reaction products remains a concern in applications of this type. SUMMARY OF THE INVENTION The present invention offers a useful formulation for laminating adhesive or coating applications that is essentially solvent free., water, and compounds functionalized with isocyanate. The formulation consists of a product obtained by mixing and reacting an epoxy resin and a curing agent having at least one active hydrogen contained in a functional group selected from primary amino groups, secondary amino groups, carboxyl groups, and combinations thereof. The epoxy resin and the curing agent (the epoxy resins and the curing agents) are selected in such a way as to provide a product having a viscosity within a range of about 1,000 to about 10,000 cps at a temperature of 40 ° C. for at least 20 minutes after mixing the epoxy resin and the curing agent (the epoxy resins and the curing agents). The product provides a flexible adhesive or coating when it reacts completely; the sheet-like products obtained in this way have high values of peel strength, as measured by ASTM D1876, both after 16 hours and after 7 days (typically, at least 200 grams / 2.54 cm (200 grams) / inch) and in some modalities, at least 400 grams / 2.54 cm (400 grams / inch)). DETAILED DESCRIPTION OF THE INVENTION The provision of an adhesive system not based on isocyanate that can be easily used with existing machinery for a wide range of substrates is a key objective of the present invention. Epoxy resins are used as structural adhesives and provide a thermoset bond between rigid substrates. The U.S. 4,751,129, U.S. 3,894,113, U.S. 4,320,047, U.S. 4,444,818, all of which are incorporated in their entirety as if they were reproduced here in fullness are only some of the numerous patent documents in the literature. Several patents have suggested or proposed that epoxy resins can be used as components of an adhesive to bond certain types of films. See, for example, U.S. Patent Nos. 4,211,811, 4,311,742, 4,329,395, 4,360,551, and 4,389,438 and British Patent no. 1,406,447. These patents, however, do not provide any useful guidance for selecting particular combinations of epoxy resins and curing systems in order to obtain a laminating adhesive or coating having a satisfactory viscosity and satisfactory adhesive characteristics. Reaction products of compounds containing di / polyglycidyl ether and di / polyamines and / or di / polyacids are well known in many structural adhesive applications. The present invention relates to compositions that are suitable for combining various printed and non-printed films with other films and sheet substrates. Such formulations also possess unexpectedly desirable properties in the rolling and packaging process. Polyurethane adhesives without solvent are applied through machines specially designed to control the variable tensions of the two laminated substrates. In order to produce a useful lamination, the viscosity of the adhesive formulation must be within a range of about 1,000 cps to about 10,000 cps at an application temperature such that the adhesive can flow regularly and humidify the adhesive. substrate on which it is applied. However, once the second film has come into contact with the adhesive layer, sufficient adhesion must be developed. These specially designed machines keep the newly rolled rolls under mechanical stress in such a way that the differential tension experienced by the two dissimilar films does not destroy the development of the adhesive bond between the two films. Potential users of these products in sheets must wait until the necessary time for the adhesive strength to be sufficient to resist this dissimilar force. The greater the delay in the additional processing of the rolls, the higher the manufacturing cost. The formulations of the present invention develop sufficient strength in a relatively short period of time compared to known polyurethane-based products. With the introduction of fresh products such as salads, vegetables and fruits in easy-to-use packaging, the role of adhesives in their performance as barriers to oxygen, moisture and carbon dioxide becomes significant. While certain products require "breathing capacity," which means oxygen free flow, other products can easily spoil in an oxygen atmosphere. The ability to handle the required oxygen transmission rate (OTR) becomes increasingly critical. While some adhesives based on polyurethane offer some resistance to oxygen transmission, are not good for what is known as high oxygen barrier applications. Of surprising origin, the present invention offers products that, in addition to meeting most of the other requirements of flexible packaging, can easily provide adhesive layers ranging from the absence of barrier to a very high barrier, selecting different starting materials available in the Commerce. Any of the thermosetting resins having an average of more than one epoxide group (preferably two or more) per molecule is known in the art can be used • as the epoxy resin component of the present invention. The epoxy resin (the epoxy resins) however must be selected in such a way as to provide the desired characteristics of the resulting adhesive or resulting coating formulation (eg initial viscosity when mixed with the curing agent containing active hydrogen and flexibility and clarity). when • 10 found in cured state). Epoxy resins are described, for example, in the chapter entitled "Epoxy Resins" (epoxy resins) in the second edition of the Encycopledia of Polymer Science and Engineering, volume 6, pages 322-382 (1986). Resins Particularly suitable epoxies include polyglycidyl ethers obtained by the reaction of polyhydric phenols such as co or bisphenol A, bisphenol F, bisphenol AD, phenol-formaldehyde condensates (novolacs), catechol, resorcinol, or aliphatic polyhydric alcohols such as glycerin, trimethylolpropane, sorbitol, neopentyl glycol, pentaerythritol and polyalkylene glycols with haloepoxides such as epichlorohydrin. Epoxy resin mixtures can be used if desired; for example, mixtures of liquid epoxy resins (at room temperature) can be used, semi-solid, and / or solid. If a solid epoxy resin is selected, the use of a liquid curing agent or mixture of curing agents will generally be preferred in such a way that the resulting mixture has a suitable viscosity • low (1,000 - 10,000 cps) at a temperature of 40 ° C on the 5th mixing. Any of the epoxy resins available from commercial sources is suitable for use in the present invention. Preferably, the epoxy resin has an epoxide equivalent molecular weight of about 50 to 1,000 (most preferred of • 10 approximately 100 to 500). The use of liquid epoxy resins based on glycidyl ethers of bisphenol A is especially advantageous. The curing agent employed in the present invention can be any compound having at least one hydrogen Active (preferably, at least two active hydrogens), wherein the active hydrogen is in a primary amino group (-NH2), secondary amino group (-NHR), or carboxyl group (-COOH). Different types of functional groups may be present in the curing agent molecule (for example, a carboxyl group and a secondary amino group, a primary amino group, and a secondary amino group). Other types of functional groups may also be present in the curing compound (for example, hydroxy groups). Mixtures of different curing agents can also be used. The Functional hydrogen-containing functional groups of the cure are capable of reacting with the epoxy groups of the epoxy resin component, thus curing the epoxy resin in a polymeric matrix. The curing agent or curing agent mixture is selected in such a way as to provide the desired viscosity after mixing with the epoxy resin and the desired physical, adhesive and mechanical properties in the adhesive or coating formulation layer in a cured state. of the product of sheets. Solid curing agents are preferably used in combination with liquid epoxy resins in order to obtain a mixture having a working viscosity at 40 ° C. Particularly preferred classes of curing agents include alkanolamines (eg 2- (2-aminoethylamino) ethanol, monohydroxyethyl diethylenetriamine, dihydroxyethyldiethylenetriamine), polyoxyalkylene-terminated amine such as the ethylene-terminated polymers of ethylene oxide and / or propylene oxide sold by Huntsman Chemical under the trade name JEFFAMINE, polyamidoamines (also sometimes known as polyaminoamides, for example, condensation products based on polyamines such as diethylenetriamine and carboxylic acids or carboxylic acid derivatives), polyamides (particularly those obtained by the reaction of unsaturated fatty acids) digested and trimerized with polyamines such as diethylenetriamine), reaction products obtained from alkanolamines and glycidyl esters of carboxylic acids such as neodecanoic acids, carboxyl-terminated polyester resins (obtained, for example, by condensation polymerization of polyols such as glycols and polycarboxylic acids or derivatives thereof, with aliphatic polycarboxylic acids being preferred in comparison with aromatic polycarboxylic acids), the reaction products obtained from alkanolamines and carboxyl-terminated polyester resins, the products of the reaction obtained from aliphatic polyamines and monofunctional epoxy compounds, and mixtures thereof. Other suitable curing agents include, but are not limited to, aliphatic diamines (e.g., hexanediamine, ethylenediamine, heptanediamine), aromatic diamines (e.g., 4,4'-diaminodiphenylsulfone, 4,4'-diaminodiphenylmethane, m-phenylenediamine), guanidmas (for example, cyanoguanidines), aliphatic polyamines (for example, diethylenetriamine, triethylenetetramine, tetraethylenepentamine), cycloaliphatic diamines and polyamines (for example, isophoronediamine, 1,2-diamino-cyclohexane, N-aminoethylpiperazine), butadiene-acrylonitrile copolymers containing carboxyl terminal groups, and the like. The precise relationship between the epoxy resin (the epoxy resins) and the curing agent (the curing agents) in the lamination adhesive coating formulation is not considered to be particularly critical. Typically, however, it is desirable to maintain the ratio between epoxide equivalents and active hydrogen equivalents within a range from about 1: 0.2 to about 1: 4 (preferably, from about 1: 0.5 to about 1: 2) . For particular end-use applications, it may be desirable to incorporate one or more flow modifiers, wetting agents and other conventional auxiliaries processing. Typically, such additional compositions are added at levels of from about 0.1 to about 1%, based on the total weight of the adhesive formulations or lamination coating. Particularly profitable combinations of epoxy resins And curing agents are the following: a) a liquid diglycidyl ether of bisphenol A having an ß-equivalent weight in epoxide of about 170 to about 300 in combination with a curing agent of polyaminoamine or polyamide; B) a liquid diglycidyl ether of bisphenol A having an epoxide equivalent weight of about 170 to about 300 in combination with the product of the reaction of an alkanolamine and a glycidyl ester of a carboxylic acid; C) a liquid diglycidyl ether of bisphenol A having an epoxide equivalent weight of about 170 to about 300 in combination with an amine-terminated polyoxyalkylene; d) a liquid diglycidyl ether of bisphenol A having an epoxide equivalent weight of about 170 to about 300 in combination with the reaction product of a carboxyl-terminated aliphatic polyester resin having a molecular weight of about 200 to about 3,000 and an alkanolamine; e) a glycidyl ether of an aliphatic polyol (said polyol preferably having 2 to 8 hydroxyl groups) having an epoxide equivalent weight of about 100 to about 300 in combination with the product of the reaction of an alkanolamine and a glycidyl ester of a carboxylic acid; f) a liquid diglycidyl ether of bisphenol A having an epoxide equivalent weight of about 170 to about 300 in combination with a carboxyl-terminated aliphatic polyester resin having a molecular weight of about 300 to about 3,000; g) a liquid diglycidyl ether of resorcinol or bisphenol F having an epoxide equivalent weight of about 100 to about 300 in combination with the product of the reaction of an aliphatic polyamine and a monofunctional epoxy resin.

The film or films to be coated or bonded together using the formulations of the present invention may consist of any of the materials known in the art as suitable for use in flexible packaging, including both polymeric and metallic materials. Thermoplastic agents are especially preferred for use as at least one of the layers. The materials chosen for the individual layers in a product containing several sheets are selected to achieve specific combinations of properties, for example, mechanical strength, tear strength, elongation, puncture resistance, flexibility / stiffness, gas permeability and steam of water, permeability to oil and grease, thermal sealability, adhesion capacity, optical properties (for example, clear, translucent, opaque), training capacity, machine handling capacity, and relative cost. The individual layers may be pure polymers and mixtures of various polymers. The polymeric layers are frequently formulated with dyes, anti-slip processing aids, antiblocking and antistatics, plasticizers, lubricants, fillers, stabilizers, and the like to increase certain layer characteristics. Particularly preferred polymers for use in the present invention include, but are not limited to, polyethylene (including low density polyethylene (LDPE), medium density polyethylene (MDPE), high density polyethylene (HDPE), high density polyethylene. high molecular weight (HM -HDPE), linear low density polyethylene (LLDPE), linear medium density polyethylene (LMDPE)), polypropylene (PP), oriented polypropylene, polyesters such as poly (ethylene terephthalate) (PET) and poly (butylene terephthalate (PBT), ethylene-vinyl acetate (EVA) copolymers, ethylene-acrylic acid copolymers (EAA), ethylene-methyl methacrylate copolymers (EMA), ethylene-methacrylic acid salts (ionomers), hydrolyzed ethylene-vinyl acetate copolymers (EVOH), polyamides (nylon), polyvinyl chloride (PVC), polyvinylidene chloride copolymers (PVDC), polybutylene, ethylene-propylene copolymers, polycarbonates (PC), polystyrene (PS), styrene copolymers, high impact polystyrene (HIPS), acrylonitrile-butadiene-styrene (ABS) polymers, and acrylonitrile (AN) copolymers. The polymer surface can be treated or coated, if desired. For example, a polymer film can be metallized by depositing a thin metal vapor such as aluminum on the surface of the film. The metallization can increase the barrier properties of the finished sheet product. The polymer film surface can also be coated with an antifouling additive or the like, or else subjected to a pretreatment with electric or corona discharges, either ozone or other chemical agents to increase its reception capacity to the adhesion. One or more layers of the product in the form of sheets may also comprise a sheet of metal, for example an aluminum foil or the like. The metal sheet will preferably have a thickness of about 5 to 100 μm. The individual films that make up the sheet products of the present invention can be prepared with very variable thicknesses, for example, from about 0.00254 mm (0.1 mil) to about 0.254 mm (10 mil) and, preferably from approximately 0.0127 mm (0.5 mil) to approximately 0.127 mm (5 mil). The films, sheets, and adhesive or coating formulation for lamination can be assembled into the multilayer product by the use of one or more of the conventional methods known in the art for that purpose. For example, the adhesive or coating formulation can be applied on the surface of one or both of two films / sheets by esion, brushes, rollers, blades, spray or the like and the surface (s) of film / sheet bearing the adhesive or coating formulation can (come) in contact and pass through a set of rollers that press a against one another the superimposed films / sheets having the adhesive or coating formulation between the films / sheets. Typically, the amount of adhesive or coating formulation that is applied on the surface of a film or sheet is within a range of about 0.2 to about 5 g / m2. It is often desirable to heat the product in the form of sheets at an elevated temperature in order to accelerate the complete curing of the adhesive or coating formulations. Typically, temperatures of about 50 ° C to about 100 ° C will be sufficient, although care must be taken not to exceed the melting point of any of the polymeric components of the product in the form of layers. The products in the form of layers prepared in accordance with the present invention can be used for packaging purposes in the same way as known conventional or flexible laminated packaging films. The products in the form of layers are especially suitable for forming containers in the form of a flexible bag capable of being filled with a food and redoubled. For example, two rectangular or square sheets of the product in the form of layers can be stacked in the desired configuration or arrangement; preferably, the two layers of the two facing sheets can be heat sealed between them. Three peripheral portions of the stacked assembly are then heat sealed to form the bag. The seal can be easily achieved through a heating rod, heating blade, heating wire, impulse sealant, ultrasonic sealant, or by induction thermal sealant. The food is then packed in the bag formed in this way. If necessary, gases that are harmful to the food, such as air, are removed through known means such as vacuum gassing, hot pack, boil outgassing, vapor jets or vessel deformation. The opening of the bag is then sealed using heat application. The packaged bag can then be loaded in an oven treatment apparatus and sterilized by heating to a temperature greater than about 100 ° C. Example 1: Four parts by weight of EPON 828 resin (a diglycidyl ether of bisphenol A having an equivalent weight in epoxy of 175-210) obtained in Shell Chemical and 1 part by weight of polyamidoamine HY 955 obtained in Ciba Geigy were mixed in a planetary mixer to obtain a clear yellowish homogeneous liquid. The initial viscosity of the mixture was determined at a temperature of 40 ° C in a Brookfield viscometer at 1,850 cps. The viscosity gradually rose after 20 minutes at 5,000 cps. The fc viscosity range of 1,000 cps at 10,000 cps during the 20 to 30 minute interval after mixing at 40 ° C is considered the most suitable for a lamination without problem in solvent-free laminating machines currently in commercial use . Example 2: Thirty weight percent of 2- (2-aminoethylamino) ethanol and 70% by weight of Exxon's GLYDEXX N-10 (a glycidylester of neodecanoic acid) were mixed together for 30 minutes at a temperature of 50 ° C. The resulting mixture was employed as the active hydrogen-containing component. One and a half parts by weight of EPON 828 resin were mixed with 1 part in weight of the reaction product EPON 828 / GLYDEXX N-10. The viscosity of this mixture also remained within the desirable range of 2,200 to 8,000 cps for at least 30 minutes after the preparation. Example 3: Six parts by weight of EPON resin 828 were mixed with 1 part by weight of JEFFAMINE D 2000, a propylene glycol diamine sold by Huntsman Chemical, to obtain a homogeneous mixture. The viscosity obtained for this mixture was also within the desirable range of 20 to 30 minutes after of the mixture.

Example 4: A carboxyl-terminated polyester resin obtained from the reaction of neopentyl glycol and adipic acid with a molecular weight of 540 reacted with 2- (2-aminoethylamino) ethanol. The resulting product was mixed with an EPON 828 epoxy resin in a weight ratio of 1 to 5 to provide a product having a viscosity that remains within the desired range for at least 30 minutes after mixing. Example 5: Example 2 was repeated using a polyepoxy resin based on sorbitol with a weight in epoxy equivalent of 180 instead of EPON 828. Example 6: Adhesive compositions of examples 1 to 5 were used to produce the following products in the form of layers in a laminator without NORDMECHANICAL solvent. A) polyethylene terephthalate film (Dupont Mylar, 48 gauge) on polyethylene film (Dupont SL1); B) aluminum foil on polyethylene film (Dupont SL3); C) metallized polypropylene film over polyvinylidene chloride (PVdC) coated with oriented polypropylene film (OPP) (70 PSX, Mobile). Example 7: The products in the form of layers obtained from Example 6 were tested to determine their peel strength and their thermal seal strength using • an Instron. The test method employed (ASTM DI876) measured the peel strengths and the thermal seal strengths of the products in the form of layers. The table below shows the adhesion values obtained with example 1 and example 2. Resistance to peel and resistance • 10 thermal seal (grams / 2.54 cm) (grams / inch) AcChesivo employee: Example 2: 16 hrs. 7 days 7 days 15 resistance to resistance to resistance detachment of thermal seal release A). Mylar / SL 1 450 (ST) 450 (ST) 8730 (ST) B). Al Foil / SL 3 650 600 3420 20 C). PET / PVdC / MOPP 350 (ST) 400 (ST) N.A. Adhesives used: Example 1: A). Mylar / SL 1 450 (ST) 450 (ST) 5300 (ST) B). Al Foil / SL 3 500 580 5420 (ST) C). PET / PVdC / MOPP 250 (ST) 300 (ST) N.A.

Coating weight: 1.6 grams / square meter ST: destruction of one or both substrates. Thermal seal conditions: 177 ° C (350 ° F), 2 seconds, residence at 28,124 kg / m2 (40 psi). Example 8: The products in the form of Mylar / SLl layers from Example 7 were used to make bags of 10.16 cm x 10.16 cm (4 inches x 4 inches). The bags were filled with various food products and stored in an oven at a temperature of 60 ° C for 100 h. The bags were examined at the end to determine their integrity. Food ingredients, example 1 example 2 Catsup approved approved approved mustard approved Salad dressing approved approved thousand island Isopropanol approved approved Approved approved hazelnut oil Example 9: Special products in the form of layers were made with oriented 40-gauge propylene and 0.0381 mm (1.5 mil) polypropylene films that contained an anti-clouded coating. The products In the form of layers of these types of films are typically used in the packaging of fresh vegetables and fruits. Adhesion values as well as oxygen transmission rates were determined in the products in the form of obtained layers. Resistance to detachment Adhesive 24 hours 7 days 7 days seal OTRs Thermal Example 2 855 (ST) 800 (ST) 2450 150 * Example 1 750 (ST) 800 (ST) '4000 (ST) 55 * * -cc / 645 cm2 ( 100 square inches) / day: measured in a Mocon Oxytran system Example 10: A polyester resin of molecular weight 1, 000 with carboxyl end groups was made by the reaction of adipic acid and diethylene glycol. The resulting polyester had a viscosity of 2,500 cps at room temperature. An epoxy resin EPON 828 was mixed with the polyester in a weight ratio of 1 to 1 in a laboratory mixer. Choline chloride (0.1% by weight) was added and mixed thoroughly. The resulting mixture had a viscosity within the desirable range of 3,500 to 8,000 cps for at least 30 minutes at a temperature of 40 ° C after mixing. Example 11: A comparative example of polyurethane lamination adhesive was made in the following manner: in a reaction vessel a polyether prepolymer with an NCO content of 15% was prepared from polyether polyol PPG 1025 and methylene diisocyanate. The prepolymer was mixed with a polyester polyol resin based on diethylene glycol and adipic acid in such a way that the resulting adhesive had an NCO: OH ratio of 1.5 to 1. Example 12: Products were made in the form of layers in accordance with that described in Example 7 using the adhesives described in examples 10 and 11. All the test conditions were similar to example 7. Adhesive used: example 10 24 hrs 7 days 7 days appearance resistance strength resistance to detachment sheds thermal seal Mylar / SLl. 400 450 4025 without bubbles OPP / PVdC 350 475 (ST) without bubbles PVdC / OPP * Adhesive used: example 11 Mylar / SLl 450 (ST) 450 (ST) 4500 without bubbles OPP / PVdC 300 425 (ST) air bubbles PVdC / OPP * * coated polypropylene film 70 PSX PVdC (mobile) Example 13: Tetraethylenepentamine (40 pbw) reacted with 60 pbw ERISYS GE8 • (a monofunctional epoxy resin available from CVC Specialty 5 Chemical Inc.). The resulting adduct was mixed with ERISYS RDGE (an epoxy resin based on resorcinol having an epoxy equivalent weight of 127 and a viscosity of 425 cps available from CVC Specialty Chemicals Inc.) using a weight ratio of 2.7 pbw epoxy resin and 1 pbw of adduct. Two polyethylene films (Dupont SL1, 0.0508 mm (2 mils) thick, Huntsman PE 208.24) were laminated using the aforementioned mixture. Within a period of 24 hours, the resulting layered product presented a resistance to detachment of 1.14 kg (2.5 pounds), which is enough to destroy the polyethylene films in the event of attempting the separation. • Example 14 Example 13 was repeated, but using EPOALLOY 8230 (a Epoxy resin based on bisphenol F having an epoxide equivalent weight of 170 and a viscosity of 4,100 cps, available from CVC 'Specialty Chemicals Inc.) instead of ERISYS RDGE. The ratio of epoxy resin / adduct mixture was adjusted to 3.5: 1. The resulting layered product provided a material with a peel strength value of 0.41 kg (0.9 pounds)

Claims (24)

1. CLAIMS A formulation of adhesive or coating for a product that can be formed into sheets that is • ntially free of solvent, water and compounds with isocyanate functionality, and consisting of a product obtained by mixing and reacting an epoxy resin and a curing agent having at least one active hydrogen contained in a functional group selected within the group • consisting of primary amino groups, secondary amino groups, carboxyl groups and combinations thereof, said epoxy resin and said curing agent have been selected in such a way as to maintain the viscosity of said product for at least 20 minutes. 15 minutes after said mixing within a range of 1,000 to 10,000 cps at a temperature of 40 ° C and in such a way as to provide a flexible adhesion or coating when fully reacted.
2. The adhesive or coating formulation for laminated product of claim 1 wherein the curing agent contains two or more active hydrogens.
3. The formulation of adhesive or coating The lamination according to claim 1 wherein the curing agent is an alkanolamine.
4. 4. The adhesive formulation or laminate coating according to claim 1 wherein the curing agent is obtained by the reaction of an alkanolamine with a glycidyl ester of a carboxylic acid.
5. 5. The adhesive formulation or laminate coating according to claim 1 wherein the curing agent is an amine-terminated polyoxyalkylene.
6. 6. The adhesive formulation or laminate coating according to claim 1 wherein the curing agent is diamine or aromatic polyamine.
7. 7. The adhesive formulation or laminate coating according to claim 1 wherein the curing agent is an aliphatic diamine or polyamine.
8. 8. The adhesive formulation or laminate coating according to claim 1 wherein the curing agent is a polyester resin terminated in carboxyl.
9. 9. The adhesive formulation or laminate coating according to claim 1 wherein the curing agent is a polyamidoamine.
10. 10. The adhesive formulation or laminate coating according to claim 1 wherein the curing agent is a polyamide.
11. 11. The adhesive or beading coating formulation according to claim 1 wherein the curing agent is obtained by the reaction of an aliphatic polyamine with a monofunctional epoxy compound.
12. 12. The adhesive or coating formulation according to claim 1 wherein the epoxy resin is a glycidyl ether of a polyhydric phenol.
13. The adhesive or coating composition according to claim 1 wherein the epoxy resin and the curing agent are present in effective amounts to provide a ratio of epoxy equivalent to active hydrogen equivalent within a range of about 1: 0.2 to about 1: 4.
14. 14. The adhesive or coating formulation according to claim 1 wherein the epoxy resin is a diglycidyl ether of bisfer.ol A, bisphenol F, or resorcinol having an epoxide equivalent weight of about 100 to about 500.
15. 15 The adhesive formulation or laminate coating according to claim 1 wherein the epoxy resin is a glycidyl ether of an aliphatic polyol containing from 2 to 8 hydroxyl groups.
16. 16. A sheet product comprising at least one polymeric film and the adhesive or • lamination coating in accordance with the 5 claim 1 in cured form.
17. 17. The sheet product according to claim 16 comprising at least two polymeric films, wherein the adhesive or lamination coating formulation is between two • 10 of said polymer films and adheres said polymer films to each other.
18. 18. The sheet product according to claim 16 wherein at least one polymeric film consists of a selected thermoplastic 15 within the group consisting of polyethylene terephthalate, polyethylene, polypropylene, and polyvinylidene chloride. •
19. 19. The sheet product according to claim 16 further comprising a sheet of 20 metal, where the adhesive formulation or lamination coating is between the metal sheet and at least one polymeric film.
20. 20. The sheet product according to claim 16 wherein at least one film 25 polymer is metallized.
21. 21. A flexible film sheet product comprising (a) a first layer consisting of a first # polyolefin or first polyester; 5 (b) a second layer comprising a second polyolefin, which may be the same or different from the first polyolefin, a second polyester, which may be the same or different from the first polyester, or a sheet of metal; 10 (c) an adhesive layer joining the first layer on the second layer, said adhesive layer is derived from the adhesive formulation or lamination coating of claim 1.
22. 22. A flexible film sheet product in accordance with claim 21 wherein the first layer and the second layer each have a thickness of about 10 microns to about 100 microns.
23. 23. A fold-up food bag made from the product in flexible film sheets according to claim 21.
24. 24. An adhesive or coating formulation for sheet products that is essentially free of solvent, water and functionalized compounds. with Isocyanate, and consisting of a product obtained by mixing and reacting: (a) at least one liquid epoxy resin selected from the group consisting of diglycidyl ethers of bisphenol A, bisphenol F or liquid resorcinol, glycidyl ethers of aliphatic polyols containing from 2 to 8 hydroxyl groups, and mixtures thereof; Y (b) at least one curing agent having at least two active hydrogens contained in a functional group selected from the group consisting of primary amino groups, secondary amino groups, carboxyl groups, and combinations thereof, said agent Cured is selected within the group that _ consists of: (i) alkanolamines; (ii) reaction products of alkanolamines and glycidyl esters of carboxylic acids; (iii) amine terminated polyoxyalkylenes; (iv) aromatic diamines; (v) aromatic polyamines; (vi) aliphatic diamines; . { vii) aliphatic polyamines; (viii) aliphatic polyester resins (ix) terminated in carboxyl; (ix) polyamidoamines; (x) polyamides; (xi) reaction products of aliphatic polyamines and monofunctional epoxy compounds; (xii) reaction products of alkanolamines, and aliphatic polyester resins terminated in carboxyl; and • 10 (xiii) mixtures thereof; said epoxy resin and said curing agent have been selected in such a way that the viscosity of said product is maintained for at least 20 minutes after said mixing within the range of 15 1,000 to 10,000 cps at a temperature of 40 ° C and to provide a flexible adhesive or coating when fully reacted. • 25. A flexible film sheet product comprising (a) a first layer comprising a first polyolefin or a first polyester; (b) a second layer comprising a second polyolefin, which may be the same or different from the first polyolefin, a second polyester, which may be the same or different from the first polyester, or a sheet of metal; (c) an adhesive layer joining the first layer on the second layer, said adhesive layer being derived from the adhesive formulation or lamination coating of claim 24. A foldable food bag made from the sheet product of flexible film of claim 25.