PRESSURE SENSITIVE ADHESIVE CONTAINING LIQUID RESIN COMPRISING AN OLIGOESTER COMPOSITION

Abstract

The present invention relates to a pressure-sensitive adhesive composition containing at least one polymer, at least one liquid resin comprising an oligoester composition as described herein and at least one further plasticizer, wherein the at least one further plasticizer comprises an isobutene/butene copolymer. The invention also relates to the use of the pressure-sensitive adhesive composition according to the invention, to a method for preparing the pressure-sensitive adhesive composition, and to a method for bonding at least two substrates. Finally, the invention relates to an article comprising the pressure-sensitive adhesive composition according to the invention.

Claims

1. A pressure-sensitive adhesive composition comprising a) at least one polymer; b) at least one liquid resin comprising an oligoester composition, which is a reaction product of a reaction mixture, comprising: ii) one or more monocarboxylic acids; iii) one or more polyhydric alcohols; and iv) optionally one or more polycarboxylic acids, wherein the reaction mixture comprises one or more colophonies; c) at least one further plasticizer, wherein the at least one further plasticizer comprises an isobutene/butene copolymer; d) optionally at least one further resin; and e) optionally at least one additive.

2. The pressure-sensitive adhesive composition according to claim 1, wherein the at least one polymer a) is selected from the group of polymers based on acrylate, polyester, urethane, ethylene acrylate, butyl rubber and (synthetic) natural rubber; ethylene-vinyl acetate copolymers (EVA), polyolefin (co)polymers (PO), polyamide (co)polymers (PA), ethylene-propylene copolymers or styrene copolymers, individually or as a mixture, said polymer is present in 20 to 70 wt. %, based on the total weight of the composition.

3. The pressure-sensitive adhesive composition according to claim 1, wherein the reaction mixture for preparing the oligoester composition comprises 25 wt. % to 85 wt. % of one or more monocarboxylic acids, 7 wt. % to 35 wt. % of one or more polyhydric alcohols, and more than 0 wt. % to less than 4 wt. % of one or more polycarboxylic acids, wherein the reaction mixture contains 5 wt. % to 75 wt. % colophony.

4. The pressure-sensitive adhesive composition according to claim 3, wherein the colophony comprises a mixture of colophony acids, selected from the group consisting of abietic acid, neoabietic acid, dehydroabietic acid, dihydroabietic acid, pimaric acid, levopimaric acid, sandaracopimaric acid, isopimaric acid and palustric acid and their isomers.

5. The pressure-sensitive adhesive composition according to claim 1, wherein the at least one liquid resin b) is contained in the pressure-sensitive adhesive composition in an amount of 5 to 30 wt. %, based on the total weight of the pressure-sensitive adhesive composition.

6. The pressure-sensitive adhesive composition according to claim 1, wherein the at least one further plasticizer c) i) is contained in an amount of 1 to 15 wt. %, based on the total weight of the pressure-sensitive adhesive composition; and/or ii) has a number-average molecular weight M.sub.n of 900-1300 g/mol, measured by size-exclusion chromatography (GPC, gel permeation chromatography); and/or iii) has a glass transition temperature (Tg) of 60 to 73 C. measured by dynamic differential thermal analysis (DSC: differential scanning calorimetry); and/or iv) has a kinematic viscosity of 0.00018-0.0007 m.sup.2/s (180 to 700 cSt), determined according to ASTM D445 at 100 C.

7. The pressure-sensitive adhesive composition according to claim 1, wherein the pressure-sensitive adhesive composition comprises no further plasticizers besides the isobutene/butene copolymer plasticizer c).

8. The pressure-sensitive adhesive composition according to claim 1, wherein the at least one further resin d) is a solid and is selected from the group consisting of a a tall oil ester, a gum rosin (colophony ester), a partially polymerized tall resin, a terpene, a crude-oil-based aliphatic, aromatic or cycloaliphatic hydrocarbon resin, a C5 aliphatic or C9 aromatic hydrocarbon resin, and a C5/C9 monomer mixture, which is present in an amount of 15 to 60 wt. %, based on the total weight of the pressure-sensitive adhesive composition.

9. The pressure-sensitive adhesive composition according to claim 1, wherein the at least one further resin d) comprises at least two further resins, wherein the resins are selected from solid (cyclo)aliphatic hydrocarbons and/or solid colophony esters.

10. The pressure-sensitive adhesive composition according to claim 1, wherein the at least one additive e) comprises at least one substance from the group consisting of antioxidants, such as stabilizers, waxes, UV protectors, solvents, adhesion promoters, fillers, pigments, flame retardants, UV absorbers, optical brighteners and fragrances, which is present in an amount of 0.01 to 20 wt. %, based on the total weight of the pressure-sensitive adhesive composition.

11. A method for preparing the pressure-sensitive adhesive composition according to claim 1, comprising mixing at least one liquid resin b) with at least one polymer a) and the at least one further plasticizer c) and resin d) and/or at least one additive e), in a suitable order; at a temperature of 100 to 200 C.

12. The pressure-sensitive adhesive composition according to claim 1, which is a prepared as a tape, label or package.

13. An article comprising the tape, label or package of the claim 12.

14. A method for bonding at least two substrates, wherein the pressure-sensitive composition according to claim 1 is applied to at least one substrate and the at least two substrates are subsequently joined together.

15. The article of claim 13, which a diaper, beverage bottle, flexible package, food package, cardboard box, envelope, automobile books, magazines or brochures.

Description

EXAMPLES

Example 1

[0230] The preparation of a pressure-sensitive adhesive with liquid resin, comprising an oligoester composition as described herein:

[0231] The raw materials listed were formulated according to the mixing sequence listed in the table below at the specified temperature. The adhesive was mixed with a propeller mixer at speeds of 50-500 rpm.

TABLE-US-00001 TABLE 1 Formulation 1 Mixing Raw material type Trade name Wt. % Weight in g temperature SBC polymer Vector 4186 .sup.1 30 60 160 C. Resin 1 Sylvalite RE 100s.sup.2 28 56 Resin 2 Escorez 5400.sup.3 15 30 Liquid resin with For example, 17.5 35 oligoester composition sample 28 according to US 2017/0190935 A1 Polybutene Polybutene PB 8 16 1300 Stabilizer Irganox B225.sup.4 1 2 .sup.1 radial styrenic block copolymer with narrow molecular weight distribution, available from TSRC Corporation, USA .sup.2stabilized pentaerythritol ester of tall oil colophony, available from Kraton Corporation, USA .sup.3cycloaliphatic hydrocarbon resin, available from ExxonMobil, USA .sup.4mixture of phenolic antioxidant (Irganox 1010) and a secondary phosphite antioxidant (Irgafos@ 168), available from BASF, Germany.

[0232] The adhesive according to the invention has increased adhesion to various substrates while reducing the application weight. This means that significantly less adhesive can be used to meet the requirements of the application in comparison with reference adhesive 1. This leads to energy and cost savings for the customer.

TABLE-US-00002 TABLE 2 Physical properties Mineral-oil-free Mineral-oil-free pressure-sensitive pressure-sensitive adhesive with adhesive with liquid polyester polyol based resin with oligoester on betulin composition Reference 1 Method (EP3878883A1) (formulation 1) Technomelt 8746 Brookfield viscosity 140 C.: 12,300 140 C.: 27,350 140 C.: 26,500 (20 RPM with 160 C.: 9,200 160 C.: 12,930 160 C.: 11,425 spindle 27) in mPas Softening point 110.2 91.3 98.0 in C. (ring-and-ball, ASTM D36, glycerol) Tg (DMA) in C. 6.9 6.3 7.9 Crossover (DMA) 89.5 81.2 86.1 in C.

[0233] The coatings required to carry out the adhesion tests are produced on a laboratory scale on a heatable coating table. This table has a heated and movable doctor blade that can be used to draw the adhesive across the table. The layer thickness is set using two adjusting screws for rough adjustment and two adjusting screws for fine adjustment. The gap width between the doctor blade and the heating plate is displayed by means of two manometers, which rest on the doctor blade above the adjusting screws. Here, the gap width in micrometers can be read off a scale. The adhesive is applied to silicone paper, which is fixed to the plate by a vacuum. After the adhesive layer has been applied, it is rolled onto a PET film. After checking the application weight with a maximum deviation of 10% and a rest period of 24 hours, the finished coating can be used for the test. The coatings were made with a 50 m thick PET film and an application weight of 40 g/m.sup.2.

[0234] The following table provides 180 peel and loop tack adhesion values on various substrates. The mineral-oil-free adhesive according to the invention with liquid resin comprising an oligoester composition, as described herein, exhibits improved values in comparison with the mineral-oil-free pressure-sensitive adhesive with polyester polyol based on betulin (EP3878883A1) and is comparable to a good label and all-rounder pressure-sensitive adhesive (Reference 1).

TABLE-US-00003 TABLE 3 Adhesive properties Mineral-oil-free Mineral-oil-free pressure- pressure- sensitive sensitive adhesive with adhesive with polyester polyol liquid resin with based on betulin oligoester Reference 1 Method Substrate (EP3878883A1) composition Technomelt 8746 Peel test 180 Steel (after 20 34N 40N 39N (FINAT-FTM1) min) based on 25 mm Steel (after 24 33N 40N 36N wide PET hr) coating LD 20N 22N 19N polyethylene (after 20 min) LD 19N 22N 17N polyethylene (after 24 hr) Non-woven 13N 12N 12N fabric (after 20 min) Cardboard 18N 18N 17N Loop tack based Steel 44N 46N 47N on 25 mm Glass 43N 43N 34N 25 mm PET LD 15N 23N 24N coating polyethylene