USE OF A PARTICULAR ETHYLENE-BUTYL ACRYLATE COPOLYMER IN A HOT-MELT ADHESIVE COMPOSITION THAT IS TRANSPARENT IN THE MOLTEN STATE

Abstract

The present invention relates to the use of at least one ethylene and butyl acrylate copolymer, as defined below, as a cohesion agent, in a hot-melt adhesive composition.

The invention also relates to a hot-melt adhesive composition comprising at least one adhesive hydrocarbon resin, preferably hydrogenated, and at least one ethylene and acrylate copolymer as defined below.

The invention also relates to the use of the corresponding hot-melt adhesive composition for the production of a manufactured article.

Claims

1-21. (canceled)

22. A cohesion agent for use in a thermo-fusible adhesive, the agent comprising at least one copolymer of ethylene and n-butyl acrylate having a melt flow index greater than 400 and less than 750 g/10 minutes, measured at a temperature of 190 C., and having a content greater than or equal to 18% by weight and less than 33% by weight of n-butyl acrylate, calculated with respect to the total weight of the copolymer.

23. The cohesion agent according to claim 22, wherein the copolymer of ethylene and n-butyl acrylate has a melt flow index ranging from 410 to 740 g/10 min, measured at a temperature of 190 C.

24. The cohesion agent according to claim 22, wherein the copolymer of ethylene and n-butyl acrylate comprises from 25 to 31% by weight of n-butyl acrylate, relative to a total weight of the copolymer.

25. The cohesion agent according to claim 22, wherein the copolymer of ethylene and n-butyl acrylate comprises 28% by weight of n-butyl acrylate relative to a total weight of the copolymer and a has a melt flow index of from 450 to 740 g/10 minutes.

26. A thermo-fusible adhesive composition comprising the cohesion agent according to claim 22, wherein the thermo-fusible adhesive composition comprises less than 20% by weight of a copolymer of ethylene and vinyl acetate relative to a total weight of copolymer of ethylene and vinyl acetate and copolymer of ethylene and n-butyl acrylate of said composition

27. The thermo-fusible adhesive composition according to claim 26, wherein the thermo-fusible adhesive composition does not comprise a copolymer of ethylene and vinyl acetate.

28. A thermo-fusible adhesive composition, comprising at least one cohesion agent according to claim 22 and at least one hydrocarbon adhesive resin, different from the cohesion agent of claim 22.

29. The composition according to claim 28, wherein the hydrocarbon adhesive resin is hydrogenated.

30. The composition according to claim 29, wherein the hydrogenated hydrocarbon adhesive resin is selected from the group consisting of hydrogenated aliphatic hydrocarbon resins, cycloaliphatic hydrogenated hydrocarbon resins, aromatic hydrocarbon resins, partially or totally hydrogenated, hydrocarbon resins, aromatic modified aliphatic and/or cycloaliphatic hydrogens, aliphatic or cycloaliphatic modified aromatic hydrogenated hydrocarbon resins and mixtures thereof.

31. The composition according to claim 30, wherein the hydrogenated hydrocarbon adhesive resin is selected from the group consisting of cycloaliphatic hydrogenated hydrocarbon resins, aliphatic and cycloaliphatic hydrogenated hydrocarbon resins, aliphatic modified aromatic hydrogenated hydrocarbon resins and their mixtures.

32. The composition according to claim 28, wherein the hydrocarbon adhesive resin is present in a content ranging from 40 to 60% by weight, relative to the total weight of the composition.

33. The composition according to claim 28, wherein the copolymer of ethylene and n-butyl acrylate is present in the hot-melt adhesive composition in a content ranging from 30 to 40% by weight, relative to the total weight of the composition.

34. The composition according to claim 28, further comprising at least one wax.

35. The composition according to claim 34, wherein the at least one wax is selected from the group consisting of paraffin waxes, microcrystalline paraffin waxes, Fischer-Tropsch waxes, oxidized Fischer-Tropsch waxes, and hydrogenated waxes of stearamide.

36. The composition according to claim 28, wherein the composition has a viscosity ranging from 300 to 1500 mPa.Math.s, measured at a temperature of 170 C.

37. The composition according to claim 28, wherein the composition comprises less than 20% by weight of ethylene and vinyl acetate copolymer, relative to a total weight of copolymer of ethylene and vinyl acetate and copolymer of ethylene and n-butyl acrylate of said composition.

38. The composition according to claim 37, wherein the composition does not comprise a copolymer of ethylene and vinyl acetate.

39. An article of manufacture comprising a hot melt adhesive composition according to claim 28.

40. The article of manufacture of claim 39, wherein the article comprises a package, a binding, a labeling or a banding.

41. A method for bonding a substrate to a similar or different substrate, comprising applying to the substrate a hot melt adhesive composition according to claim 28 in the molten state.

Description

EXAMPLES

[0160] The tested hot-melt adhesive compositions, described below, are heated to a temperature of 170 C. and after about 30 minutes reach a molten state, meaning they are in liquid form.

[0161] When the compositions reach their molten state, they are manually stirred with a glass rod in order to get a homogeneous mixture.

[0162] The adhesive compositions are then left at a temperature of 170 C. for one hour until air bubbles are completely eliminated.

[0163] Transparency

[0164] The transparency of the adhesive compositions is determined by pouring each composition (having the form of a homogeneous mixture) into Petri dishes at a temperature of 170 C. to a depth of about 5 mm.

[0165] A word printed in black is placed under the Petri dish and used to give a visual evaluation of the transparency.

[0166] Cloud Point

[0167] The cloud point or (cloud temperature) appears when the ingredients become incompatible with each other thus giving a cloudy or opaque appearance to the adhesive composition. This appearance is caused by the development of crystals of ingredients from the composition.

[0168] The cloud point is measured according to the following protocol: [0169] heat the adhesive composition being studied to get a molten state at a temperature of about 170 C.; [0170] dip the mercury end of a glass thermometer in the center of the molten adhesive composition (i.e. in the bulk of the mixture); [0171] withdraw the thermometer from the composition and then slowly turn the thermometer downward while letting the additional quantity of composition flow into the adhesive composition; [0172] observe the formation of an opacity at the tip of the thermometer; then [0173] record the temperature on the thermometer when the composition becomes cloudy.

[0174] Viscosity

[0175] The viscosity of the molten hot-melt adhesive compositions is measured with a Brookfield Thermoset viscometer equipped with an SC4-27 spindle according to the NF EN ISO 2555 standard. The measurements are done at a temperature varying from 130 to 170 C.

[0176] Shear Adhesion Failure Temperature (SAFT)

[0177] The shear adhesion failure temperature (SAFT) consists of testing the hot breaking temperature under shear of hot-melt adhesive compositions. It is measured according to the standard ASTM D4498-07.

[0178] The adhesive composition is poured on a flat heating spreader at a temperature range going from 130 to 150 C. so as to form a bubble-free calibrated adhesive film.

[0179] The samples (or assemblies) tested are consi of two 10025 mm.sup.2 Kraft paper substrates adhered to each other with the adhesive film over a 2525 mm.sup.2 surface area. The two substrates are sealed at a temperature of 135 C. under a load of 400 DaN for 5 seconds. The samples therefore form an assembly of two substrates bonded to each other by the adhesive film.

[0180] The samples are then suspended vertically and loaded with a mass of 500 10 g and then the temperature is progressively increased at a controlled rate of 0.4 C./minute until the assembly gives way.

[0181] The equipment tests five samples simultaneously and records each failure temperature.

[0182] The measured temperature therefore corresponds to the maximum temperature supported under shearing.

[0183] Softening Point

[0184] The softening point measured by the ring and ball method (ring and ball (R&B) softening point) corresponds to the temperature at which the adhesive composition reaches some degree of softening under standardized conditions.

[0185] The softening point is measured according to the NF EN 1238 standard.

[0186] Polymer and Copolymers Tested

[0187] The ethylene and n-butyl acrylate copolymers used in the adhesive compositions tested, from the Lotryl series, are produced in an industrial tubular reaction vessel belonging to Arkema.

[0188] The polyethylene prepared by metallocene catalyst used in the adhesive composition tested is sold by Dow under the trade name Affinity GA 1950.

[0189] The main characteristics of the ethylene and n-butyl acrylate copolymers belonging to the Lotryl series and the polyethylene sold under the trade name Affinity GA 1950 are summarized in the following table:

[0190] The melt flow index (MFI) corresponds to the mass of the molten polymer or copolymer flowing through an oblong shaped extruder standardized using a loaded piston (standard mass of 2160 g) over a given time under given temperature conditions.

[0191] The melt flow index of the polymer or copolymer is measured at a temperature of 125 C. in an extruder (capillary) under a load of 325 g and then is extrapolated to a temperature of 190 C. under a load of 2.16 kg.

TABLE-US-00001 TABLE 1 Characteristics of the Polymers and Copolymers Concentration of n- MFI butyl acrylate (Flow index) FTIR Spectroscopy Glass transition Experimental Units temperature ( C.) Conditions g/10 min % by weight Lotryl 35BA320T 320 35% 53 Lotryl A 460 28% 53 Lotryl B 650 28% 54 Affinity GA 1950 500 57

[0192] Transparency and Cloud Point Tests

[0193] The selection of a pair made up of an ethylene and n-butyl acrylate copolymer and an adhesive resin for obtaining the best possible adhesive composition consists of determining the clarity and cloud point when molten of the two compounds in mixture each with a concentration of 50% by weight.

[0194] Table 2 indicates the transparency of compositions in the Petri dish of a mixture made up of 50% copolymer by weight and 50% hydrocarbon adhesive resin by weight.

[0195] The hydrocarbon adhesive resins used are hydrogenated resins sold under the trade names Sukorez SU 100S, Sukorez SU 500, Regalite R1100, Escorez 5380 and Escorez 5400.

TABLE-US-00002 TABLE 2 Appearance of Copolymers/Resin Mixtures Transparency of the mixture of 50% copolymer by weight and 50% adhesive resin by weight at a temperature of 170 C. Sukorez Sukorez Regalite Escorez Escorez Resin SU 100S SU 500 R1100 5380 5400 Lotryl Cloudy Cloudy Cloudy Cloudy Cloudy 35BA320T Lotryl A Transparent Transparent Transparent Transparent Transparent Lotryl B Transparent Transparent Transparent Transparent Transparent

[0196] Table 3 indicates the cloud point of a mixture made up of 50% copolymer by weight and 50% hydrocarbon adhesive resin by weight.

TABLE-US-00003 TABLE 3 Cloud Point of Copolymers/Resin Mixtures Cloud point of the mixture of 50% copolymer by weight and 50% adhesive resin by weight Sukorez Sukorez Regalite Escorez Escorez Resin SU 100S SU 500 R1100 5380 5400 Lotryl 120 C. 110 C. 104 C. 120 C. 115 C. 35BA320T Lotryl A 80 C. 60 C. 50 C. 60 C. 90 C. Lotryl B 75 C. 60 C. 50 C. 60 C. 80 C.

[0197] Hot-Melt Adhesive Composition

[0198] The hot-melt adhesive compositions tested have the following breakdowns: [0199] 35% by weight of an ethylene/n-butyl acrylate copolymer; [0200] 50% by weight of a hydrogenated hydrocarbon adhesive resin; [0201] 14.80% by weight of a wax; and [0202] 0.20% by weight of an antioxidant.

[0203] The percentages are calculated relative to the total weight of the adhesive composition.

[0204] The polyethylene prepared by metallocene (Affinity GA 1950) and the ethylene/n-butyl acrylate copolymers from the Lotryl A and Lotryl B series were formulated with hydrogenated hydrocarbon adhesive resins sold under the names Regalite R1100, Sukorez SU 500 and Escorez 5380 according to the breakdown by weight given above.

[0205] Tables 4, 5 and 6 indicate the viscosities in mPa.Math.s, the softening points ( C.) and the maximum temperature supported under shearing (SAFT or shear adhesion failure temperature in C.) from various formulations with the Regalite R1100, Sukorez SU 500 and Escorez 5380 adhesive resins.

[0206] The results shown in Tables 4, 5 and 6 show that the hot-melt adhesive compositions formulated with ethylene and n-butyl acrylate copolymers conforming to the invention have properties involving viscosity and softening point similar to the adhesive compositions formulated with polyethylene prepared by metallocene.

[0207] Table 4 shows that the adhesive compositions conforming to the present invention have a maximum temperature supported under shearing higher than an identical adhesive composition formulated with a polyolefin prepared by metallocene.

TABLE-US-00004 TABLE 4 Composition Composition Composition Temperature 1 2 3 Lotryl A 35 Lotryl B 35 Affinity GA 35 1950 Regalite R1100 50 50 50 Wax 14.8 14.8 14.8 Irganox 1010 0.2 0.2 0.2 Viscosity 130 C. 3365 2490 3325 in mPa .Math. s 170 C. 2420 1790 2263 150 C. 1700 1350 1715 160 C. 1271 1000 1285 170 C. 1000 750 983 Softening point 93.6 95.4 94 (R&B) SAFT ( C.) 67 68 61

TABLE-US-00005 TABLE 5 Composition Composition Composition Temperature 4 5 6 Lotryl A 35 Lotryl B 35 Affinity GA 35 1950 Sukorez 50 50 50 SU 500 Wax 14.8 14.8 14.8 Irganox 1010 0.2 0.2 0.2 Viscosity 130 C. 3645 2535 3520 in mPa .Math. s 170 C. 2605 1855 2540 150 C. 1933 1396 1875 160 C. 1454 1067 1425 170 C. 1125 817 1117 Softening point 92.5 93.9 93.8 (R&B)

TABLE-US-00006 TABLE 6 Composition Composition Composition Temperature 7 8 9 Lotryl A 35 Lotryl B 35 Affinity GA 35 1950 Escorez 5380 50 50 50 Wax 14.8 14.8 14.8 Irganox 1010 0.2 0.2 0.2 Viscosity 130 C. 3010 2280 3205 in mPa .Math. s 170 C. 2265 1670 3330 150 C. 1696 1250 1725 160 C. 1292 958 1317 170 C. 1008 758 1021 Softening point 91.9 93.5 93.7 (R&B)

[0208] Aging of Adhesive Compositions

[0209] The thermal stability in the molten state of adhesive compositions according to the invention and of the composition containing polyethylene prepared by metallocene was studied over seven days at a temperature of 170 C.

[0210] Over a period of seven days at a temperature of 170 C., none of the compositions tested showed the formation of gels or of traces of char. All compositions are transparent from the start (t=0) and also at the end of seven days (t=7 days).

[0211] The color of the adhesive compositions was also studied during this period by measuring the yellowing index thereof.

[0212] These index measurements are given in color shade in the following tables.

TABLE-US-00007 Composition 1 Composition 2 Composition 3 T = 0 Clear Clear Clear T = 1 day Very Very Very light yellow light yellow light yellow T = 2 days Very Very Amber light yellow light yellow T = 7 days Amber Amber Dark amber

[0213] The results show the compositions 1 and 2 according to the invention remain clear longer than composition 3 whose color degrades more quickly.

[0214] These last results show that the ethylene and n-butyl acrylate copolymers according to the invention confer more advantageous properties to the hot-melt adhesive compositions than those conferred by a polyolefin prepared by metallocene.