LAMINATION ADHESIVE FOR STERILISATION

Abstract

A solvent-based two-component polyurethane-type adhesive composition comprises an —OH component and an —NCO component. The —OH component comprises an amorphous prepolymer including two —OH end groups, with a number-average molar mass M.sub.n of 8000 to 12, 000 g and is chosen from: a) a copolyester (A1) obtained by a polycondensation reaction of at least one aliphatic diol (i) with at least one aromatic diacid (ii) and at least one aliphatic diacid (iii); and b) a polyurethane (A2) obtained by a polyaddition reaction between an aliphatic diisocyanate compound and an amorphous copolyester diol with a number-average molecular weight M.sub.n ranging from 4000 to 11 500 g/mol. The —NCO component comprises a compound (B1) including three —NCO end groups, obtained by the reaction of meta-xylylene diisocyanate (m-XDI) with a triol, said compound (B1) being alone or as a mixture with a compound (B2) derived from an aliphatic diisocyanate.

Claims

1-17. (canceled)

18. A solvent-based two-component polyurethane-type adhesive composition, comprising an —OH component and an —NCO component, such that: the —OH component is a composition (A) comprising an amorphous prepolymer which includes two —OH end groups, the number-average molar mass M.sub.n of which ranges from 8000 to 12,000 g and which is chosen from: a copolyester (A1) obtained by a polycondensation reaction: of at least one aliphatic diol (i); with at least one aromatic diacid (ii) chosen from terephthalic acid, isophthalic acid, phthalic acid and one of their diester or anhydride derivatives; and at least one aliphatic diacid (iii) or one of its diester or anhydride derivatives; and a polyurethane (A2) obtained by a polyaddition reaction between an aliphatic diisocyanate compound (A2.P1) and an amorphous copolyester diol (A2.P2), the number-average molecular weight M.sub.n of which ranges from 4000 to 11 500 g/mol, said copolyester being obtained by the polycondensation reaction as defined above for (A1); and the component —NCO is a composition (B) comprising a compound (B1) which includes three —NCO end groups, and which is obtained by the reaction of meta-xylylene diisocyanate (m-XDI) with a triol, said compound (B1) being: either the only compound comprised in (B) including three —NCO end groups; or else a mixture with another compound (B2) including three —NCO end groups, (B2) being derived from an aliphatic diisocyanate and the content of (B1) in said mixture being at least 40% by weight, based on the total weight of said mixture.

19. The adhesive composition as claimed in claim 18, wherein the amorphous prepolymer included in the composition (A) is the amorphous copolyester diol (A1) and the diol (i) is selected from the group consisting of ethylene glycol, diethylene glycol, trimethylene glycol, hexamethylene glycol, propylene glycol, propane-1,3-diol, (1,4-, 1,3- or 1,2-)butanediol, neopentyl glycol, 2-methyl-1,3-propanediol, hexanediol and cyclohexanedimethanol.

20. The adhesive composition as claimed in claim 19, wherein the aliphatic diacid (iii) is selected from the group consisting of adipic acid, azelaic acid, sebacic acid, cyclohexanedicarboxylic acid, dodecanedicarboxylic acid, 1,10-decanedicarboxylic acid and succinic acid.

21. The adhesive composition as claimed in claim 19, wherein the copolyester diol (A1) is obtained by polycondensation: of two aliphatic diols (i) consisting respectively of ethylene glycol and diethylene glycol; with two diacids (ii) consisting respectively of terephthalic acid and isophthalic acid; and adipic acid as aliphatic diacid (iii).

22. The adhesive composition as claimed in claim 18, wherein the compound (B1) is the only compound comprised in the composition (B) including three —NCO end groups.

23. The adhesive composition as claimed in claim 18, wherein the compound (B1) is the adduct of m-XDI and of trimethylolpropane (TMP).

24. The adhesive composition as claimed in claim 18, wherein the compound (B1) is as a mixture with the compound (B2).

25. The adhesive composition as claimed in claim 24, wherein the compound (B2) is chosen from: the isocyanurate (B2-1) of said aliphatic diisocyanate; and the adduct (B2-2) of said aliphatic diisocyanate and of a triol.

26. The adhesive composition as claimed in claim 24, wherein the compound (B2) is an isophorone diisocyanate (IPDI) derivative.

27. The adhesive composition as claimed in claim 24, wherein the composition (B) comprises a mixture of: the adduct (B1) of m-XDI and of trimethylolpropane (TMP); and of IPDI isocyanurate as compound (B2).

28. The adhesive composition as claimed in claim 24, wherein the content of (B1) in the mixture of (B1) and (B2) is within a range extending from 40% to 80% weight/weight.

29. The adhesive composition as claimed in claim 18, wherein the composition further comprises an adhesion promoter included in the —NCO component or in the —OH component.

30. The adhesive composition as claimed in claim 29, wherein the adhesion promoter is an aminosilane.

31. The adhesive composition as claimed in claim 18, wherein the amounts of the —NCO and —OH components are such that the —NCO/—OH molar equivalent ratio is within a range extending from 3 to 5.

32. A multilayer film comprising two thin layers of material bonded together by a continuous layer, wherein said layer is constituted by the two-component adhesive composition as defined in claim 18 in the crosslinked state, in a proportion of an amount of less than 7 g/m.sup.2.

33. A process for the continuous preparation of the multilayer film as defined in claim 32, comprising the sequential stages of: (i) combining the —NCO and —OH components and, if appropriate, diluting with a solvent, in order to form an adhesive mixture; (ii) coating, with said adhesive mixture, a first thin layer of material in the form of a substantially continuous layer; (iii) evaporating the organic solvent; (iv) laminating a second thin layer over the first thin layer coated in accordance with stage (ii), then (v) crosslinking the adhesive mixture.

Description

EXAMPLE 1 (REFERENCE): —OH COMPONENT—PREPARATION OF A COMPOSITION (A) COMPRISING AN AMORPHOUS COPOLYESTER DIOL (A1) AND AMINOPROPYLTRIMETHOXYSILANE

[0184] First of all, an amorphous linear copolyester diol (A1) is prepared according to the procedure indicated below.

[0185] 35.120 g of monoethylene glycol and 154.435 g of diethylene glycol are introduced into a closed 1 liter reactor which is equipped with a stirrer, a distillation column, heating means and a thermometer and which is connected to a vacuum pump.

[0186] When the temperature of the reaction mixture reaches 120° C., the following are introduced into the reactor: 76.190 g of adipic acid, 170.035 g of isophthalic acid, 64.165 g of terephthalic acid and 0.035 g of a catalyst based on a titanium chelate (Tyzor® LA from DuPont).

[0187] Subsequently, a temperature gradient is programmed in order to reach a temperature of 230° C. in 3 h. The acid number (N.sub.a) is subsequently measured. The reaction is halted when the acid number N.sub.a is less than 25 mg KOH/g.

[0188] 0.020 g of a titanium-based catalyst (of formula (nBuO).sub.4Ti, Tyzor® TnBT from DuPont) is then introduced, then the reactor is placed under vacuum (reach of 15 mbar in 2 h) and the reaction mixture is heated to 240° C.

[0189] Measurements are taken of the N.sub.a and of the Brookfield viscosity at 180° C. The reaction is halted when the N.sub.a is less than 3 mg KOH/g and when the viscosity is between 8000 and 9000 mPa.Math.s.

[0190] The copolyester diol obtained is subsequently cooled to 200° C. and is then slowly poured into ethyl acetate at ambient temperature with stirring, to form a 59.47% weight/weight solution.

[0191] The NOH of the copolyester diol thus obtained was measured according to the standard ISO 14900:2017 and is equal to 10 mg KOH/g, corresponding to an M.sub.n of 11 220 g/mol.

[0192] Silquest® A1110 is added to said solution, as adhesion promoter, after cooling to 45° C. and at a content of 0.89% weight/weight.

[0193] The content by weight of —OH functional groups of the —OH component is 0.18% weight/weight.

[0194] The Brookfield viscosity at 23° C. of the —OH component is 5 Pa.Math.s.

EXAMPLE 2 (REFERENCE): —NCO COMPONENT—PREPARATION OF A SOLUTION (B) IN ETHYL ACETATE OF THE ADDUCT (B1) OF M-XDI AND OF TRIMETHYLOLPROPANE (TMP)

[0195] Use is made, for the adduct (B1) of m-XDI and of TMP, of the product Takenate® D-110N sold by Mitsui Chemicals, which is a 75% weight/weight solution of said adduct in ethyl acetate and the content of —NCO functional group of which, expressed as % weight/weight, is 11.5%.

[0196] Said product Takenate® D-110N is simply introduced at ambient temperature into a glass reactor kept stirred and under nitrogen; the content of ingredient (B1) of the solution (B) is shown in table 1, expressed as % weight/weight.

[0197] The Brookfield viscosity at 23° C. is measured and the value obtained is shown in table 1.

[0198] The content by weight as % weight/weight of —NCO functional group is also shown in table 1.

EXAMPLE 3 (REFERENCE): —NCO COMPONENT—PREPARATION OF A SOLUTION (B) IN ETHYL ACETATE OF THE ADDUCT (B1) OF M-XDI AND OF TMP, AND OF IPDI ISOCYANURATE (B2)

[0199] Use is made, for the IPDI isocyanurate, of the product Vestanat® T1890/100 sold by Evonik, which is solvent-free and the content of which, expressed as % weight/weight of —NCO functional group, is 17.3%.

[0200] The adduct (B1) of m-XDI and of TMP is still Takenate® D-110N.

[0201] The IPDI isocyanurate (B2) is dissolved, in ethyl acetate preheated to 50° C., in a glass reactor maintained under constant stirring and under nitrogen. After it has completely dissolved, the adduct (B1) of m-XDI and of TMP is introduced into the mixture at the same temperature.

[0202] The mixture is maintained at 70° C. and homogenized for 30 minutes.

[0203] A solution is obtained, the contents of ingredients of which are shown in table 1.

[0204] The Brookfield viscosity at 23° C. is measured and the value obtained is shown in table 1.

[0205] The content by weight as % weight/weight of —NCO functional group is measured according to the standard NF T52-132 and given in table 1.

[0206] The ratio by weight (B1)/[(B1)+(B2)] is also shown in table 1.

EXAMPLES 4 TO 5 (REFERENCE) AND 6 (COMPARATIVE): —NCO COMPONENT—PREPARATION OF SOLUTIONS (B) IN ETHYL ACETATE OF THE ADDUCT (B1) OF M-XDI AND OF TMP, AND OF IPDI ISOCYANURATE (B2)

[0207] Example 3 is repeated for different contents of (B1) and (B2).

[0208] The Brookfield viscosity at 23° C., the ratio by weight (B1)/[(B1)+(B2)] and the content by weight as % weight/weight of —NCO functional group are also given in table 1.

EXAMPLE 1/2 (ACCORDING TO THE INVENTION): TWO-COMPONENT ADHESIVE COMPOSITION OBTAINED BY MIXING THE —OH COMPONENT OF EXAMPLE 1 AND THE —NCO COMPONENT OF EXAMPLE 2

[0209] The —OH component of example 1 is mixed with the —NCO component of example 2 in a proportion of an —NCO/—OH molar equivalent ratio equal to 4.13, which corresponds to an —NCO component/—OH component ratio by weight equal to 100 g of —OH component per 16 g of —NCO component.

[0210] The mixing is carried out at ambient temperature in the feed tank of the laminating machine, via a mixing unit and a static mixer.

[0211] The constituent data of the two-component adhesive composition are given in table 2.

EXAMPLES 1/3, 1/4 AND 1/5 (ACCORDING TO THE INVENTION) AND 1/6 (COMPARATIVE): TWO-COMPONENT ADHESIVE COMPOSITIONS

[0212] The preceding example 1/2 is repeated, the —NCO component of example 2 being replaced with the —NCO component of examples 3, 4, 5 and 6 respectively.

[0213] The values of the —NCO/—OH molar equivalent ratio and of the —NCO component/—OH component ratio by weight are also given in table 2.

EXAMPLE 7 (ACCORDING TO THE INVENTION): TWO-LAYER FILM BOPA/CPP

[0214] A two-layer film consisting of a film of BOPA and of a film of cPP bonded by a layer of adhesive composition is prepared.

[0215] A film of biaxially oriented polyamide with a thickness of 15 μm and a film of cast polypropylene with a thickness of 60 μm is used.

[0216] This two-layer film is obtained by feeding the tank of a laminating machine of Nordmeccanica type with the two-component adhesive composition, for each of examples 1/2 to 1/6.

[0217] Said laminating machine is provided with a coating device of roller type with an open tank, operating at ambient temperature and at a running speed of 50 m/minute; the adhesive layer binding the films of BOPA and of cPP exhibits a thickness of approximately 3.5 μm, corresponding to approximately 3.5 g/m.sup.2 of adhesive composition.

[0218] This two-layer film is subjected to the following tests.

[0219] A. Determination of the Crosslinking Time:

[0220] A.1. Principle of the Test:

[0221] The aim of this test is to measure the period of time (expressed in days) necessary for the crosslinking of the constituent two-component adhesive of the adhesive layer of the two-layer film, starting from the manufacture of said film by lamination.

[0222] This period of time is evaluated by the number of days necessary for the film to be sufficiently cohesive and more specifically for the cohesion of said film, measured by the 1800 peel test (described below), to be greater than a reference value equal to 3 N/15 mm.

[0223] A.2. Sampling of the Film:

[0224] Immediately after it has been manufactured, the two-layer film is stored at a temperature of 23° C. and under an atmosphere having 50% relative humidity (RH).

[0225] A sample is taken each day from the two-layer film thus stored and is subjected to the 1800 peel test.

[0226] A.3. Description of the 1800 Peel Test:

[0227] The 180° peel test is as described in the French standard NF T 54-122. The principle of this test consists of the determination of the force necessary for the separation (or peeling) of two individual layers of films, which layers are bonded by the two-component adhesive.

[0228] A test specimen of rectangular shape, with a width of 15 mm and a length of approximately 10 cm, is cut out from the two-layer film. The two individual layers of film comprised in this strip are manually detached from the end of this test specimen, and over approximately 2 cm, and the two free ends thus obtained are attached to two fastening devices respectively connected to a stationary part and a movable part of a tensile testing device which are located on a vertical axis.

[0229] While a drive mechanism imparts a uniform rate of 100 mm/minute to the movable part, resulting in the detachment of the two layers, the detached ends of which gradually move along a vertical axis with the formation of an angle of 180°, the stationary part—connected to a dynamometer—measures the force which is withstood by the test specimen thus held and which is expressed in N/15 mm.

[0230] A.4. Result:

[0231] The crosslinking time is shown in days, for each of the two-component adhesive compositions 1/2 to 1/6, in table 2.

[0232] B. Determination of the Initial Tack:

[0233] The initial tack is evaluated by measuring the cohesion of the two-layer film immediately after its manufacture, by means of the 1800 peel test described above in § A.3.

[0234] The result is shown in N/15 mm in table 2, for each of the two-component adhesive compositions 1/2 to 1/6.

[0235] The values obtained are greater than 2 N/15 mm and thus correspond to an entirely satisfactory initial tack.

EXAMPLE 8 (ACCORDING TO THE INVENTION): THREE-LAYER FILM PET/ALU/CPP

[0236] A three-layer film consisting of a first film made of PET, of a second film made of aluminum and of a third film made of cPP, which are bonded at each interface by a layer of adhesive composition, is prepared.

[0237] Use is made of a film of polyethylene terephthalate with a thickness of 12 μm, a film of aluminum with a thickness of 7 μm and a film of cast polypropylene with a thickness of 60 μm.

[0238] This three-layer film is obtained according to a sequential process by feeding the tank of a laminating machine of Nordmeccanica type with the two-component adhesive composition, for each of examples 1/2 to 1/6.

[0239] Said laminating machine is provided with a coating device of roller type with an open tank, operating at ambient temperature and at a running speed of 50 m/minute. The adhesive layer bonding the three films at each PET/ALU and ALU/cPP interface exhibits a thickness of approximately 3.5 μm, corresponding to approximately 3.5 g/m.sup.2 of adhesive composition.

[0240] This three-layer film is subjected to the test of resistance to sterilization described below.

[0241] Resistance to Sterilization:

[0242] The three-layer film, after it has been manufactured, is placed for 7 days in a climate-controlled chamber maintained at a temperature of 40° C.

[0243] A sample of rectangular shape and of A4 format (dimensions 21×29.7 cm) is then taken, which sample is folded in two lengthwise, while exerting a manual pressure on the fold.

[0244] This sample is placed in an autoclave at 135° C. in the vapor phase for one hour in order to simulate a sterilization treatment.

[0245] The sample is subsequently kept at ambient temperature for 1 hour and the cohesion of the PET/ALU interface of the film is subsequently measured, by means of the 1800 peel test described above in § A.3.

[0246] The result is shown in N/15 mm in table 2, for each of the two-component adhesive compositions 1/2 to 1/6.

[0247] These operations are repeated on another sample of the film in order to determine the cohesion of the ALU/cPP interface.

[0248] The values obtained are all greater than 3 N/15 mm, thus corresponding to an entirely satisfactory resistance to sterilization of the three-layer.

EXAMPLE 9 (ACCORDING TO THE INVENTION): THREE-LAYER FILM PET.SUB.SIOX./BOPA/CPP

[0249] Example 8 is repeated using a film of PET with a thickness of 12 μm coated with a coating of silica SiO.sub.x with a thickness of less than 0.1 μm, a film of biaxially oriented polyamide with a thickness of 15 μm and a film of cast polypropylene with a thickness of 60 μm. The PET.sub.SiOx film is, for example, available from Amcor under the Ceramis® brand.

[0250] The results of the test of resistance to sterilization are given in table 2.

[0251] The values obtained at the BOPA/cPP interface are greater than 3 N/15 mm and entirely satisfactory.

[0252] The values obtained at the PET.sub.SiOx/BOPA interface are greater than 2 N/15 mm, which is also regarded as entirely satisfactory, in the case of an interface which comprises a thin layer consisting of a thermoplastic polymer covered with a layer of less than 1 μm of aluminum, of alumina or of silica SiO.sub.x.

EXAMPLE 10 (ACCORDING TO THE INVENTION): FOUR-LAYER FILM PET/ALU/BOPA/CPP

[0253] A four-layer PET/ALU/BOPA/cPP film is prepared according to a process analogous to that described in examples 8 and 9, using individual films of the same thickness as the films employed in the preceding examples.

[0254] The test of resistance to sterilization is also repeated, while adding thereto a check, by visual examination, of the quality of the lamination at the fold formed in the sample of multilayer film.

[0255] The results are given in table 3.

[0256] The peel values obtained at the three interfaces are greater than 3 N/15 mm and entirely satisfactory.

TABLE-US-00002 TABLE 1 Compositions (B) (—NCO component) Content (as % weight/weight) Ex. 2 Ex. 3 Ex. 4 Ex. 5 Ex. 6 Ingredient (reference) (reference) (reference) (reference) (comparative) (B1) m-XDI and TMP adduct 75 4.95 54.9 51.60 26.25 (B2) IPDI isocyanurate — 10 20 23.40 49 Ethyl acetate 25 25.05 25.02 25 24.75 Composition Brookfield viscosity at 550 1290 980 1070 2700 (B) 23° C. (mPa .Math. s) Ratio by weight 100 87 73 69 35 (B1)/[(B1) + (B2)] (as %) Content by weight of 11.50 11.69 11.60 11.00 12.50 —NCO (in %)

TABLE-US-00003 TABLE 2 Two-component adhesive compositions Ex. 1/6 Ex. 1/2 Ex. 1/3 Ex. 1/4 Ex. 1/5 (comp.) —OH component Example 1 Example 1 Example 1 Example 1 Example 1 —NCO component Ex. 2 (ref.) Ex. 3 (ref.) Ex. 4 (ref) Ex. 5 (ref) Ex. 6 (comp.) —NCO/—OH molar equivalent ratio 4.13 4.20 3.91 3.95 4.21 —NCO/—OH component ratio by weight 16/100 16/100 15/100 16/100 15/100 Twin-layer Crosslinking time (in days) 1 1 1 1 >7 BOPA/cPP Initial tack (N/15 mm) 5.00 4.51 2.29 2.30 3.02 Resistance to sterilization Three-layer Peel PET/ALU interface (N/15 mm) 3.72 4.89 3.95 4.36 4.97 PET/ALCU/cPP Peel ALU/cPP interface (N/15 mm) 4.21 4.82 4.55 4.49 4.85 Three-layer Peel PET.sub.SiOx/BOPA interface (N/15 mm) 3.03 2.84 2.29 2.55 3.23 Peel BOPA/cPP interface (N/15 mm) 5.35 6.87 6.88 5.99 5.01

TABLE-US-00004 TABLE 3 Resistance to Ex. 1/6 sterilization Ex. 1/2 Ex. 1/3 Ex. 1/4 Ex. 1/5 (comp.) Four-layer Peel PET/ALU 5.53 4.92 3.75 4.69 6.63 PET/ALU/ interface (N/15 mm) BOPA/cPP Peel ALU/BOPA 3.49 5.67 5.85 5.71 5.35 interface (N/15 mm) Peel BOPA/cPP 5.87 6.15 6.20 6.58 7.73 interface (N/15 mm) Appearance of the Presence of Presence of In In In film at the fold blisters blisters accordance accordance accordance