PL219938B1 - Method for producing photoreactive pressure-sensitive adhesives based on urethane acrylates - Google Patents

Description

The present invention relates to a process for the production of photo-reactive pressure-sensitive adhesives based on urethane acrylates. The obtained glue is a solvent-free glue.

From the international publication WO 2006/117156, UV-cross-linked photoreactive urethane acrylate adhesives are known, made of unsaturated polyurethanes having terminal unsaturated acrylate or methacrylate groups. Unsaturated polyurethanes are based on diisocyanate prepolymers, partially reacted with hydroxyacrylates and then modified with hydroxylated polybutodienes, the hydroxyl end groups of which are modified again with diisocyanates and then with hydroxyacrylates. The urethane acrylate-based pressure-sensitive adhesives obtained in this way have in their structure unsaturated bonds derived from the structure of polybutadiene, which do not lead to cross-linking of the adhesive with UV radiation, thus causing a decrease in mechanical strength and a decrease in the pressure-sensitive properties of the cross-linked adhesive. From the patent description JP 2002309185 there are known photoreactive functionalized polyurethanes consisting of acrylated polyurethanes, aliphatic acrylates and a photoinitiator. From the patent description JP 2003155455 there are known photoreactive pressure-sensitive adhesives made of acrylated polyurethanes, unsaturated monomers and photoinitiators. JP 2002322454 discloses multiple-use photoreactive pressure-sensitive adhesives based on urethane (meth) acrylates, synthesized with organosilicon polyols, hydroxylated polybutadienes and diisocyanates. The photoreactive pressure-sensitive adhesives obtained on the basis of the abovementioned urethane acrylates are characterized, compared to typical photoreactive polyacrylates, by low adhesion and low cohesion at elevated temperatures, especially above 70 ° C.

The task of the proposed invention is to develop a method for the production of photoreactive pressure-sensitive adhesives based on urethane acrylates with properties that can be used in the production of self-adhesive labels, decorative films and masking tapes.

The method of producing photo-reactive pressure-sensitive adhesives based on urethane acrylates, according to the invention, consists in modifying the isocyanate groups of a polyurethane prepolymer with acrylates containing hydroxyl groups and adding a photoinitiator and then crosslinking with UV radiation. The essence of the invention is that the polyurethane prepolymer containing isocyanate end groups is obtained by mixing 10-45% aliphatic, cycloaliphatic and / or aromatic diisocyanates, 10-50% by weight of 1,6-hexanediol or polypropylene glycols with a molecular weight above 1000 g / mol, 5-30% by weight of hydroxylated polycarbonates having a hydroxyl number (HZ) between 35 and 225 and 5-35% by weight of hydroxylated saturated synthetic rubbers, the total weight fraction of all components being 100%.

Preference is given to using trimethyl-1,6-hexamethylene diisocyanate (TMDI), hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDl), 1,5-naphthyl diisocyanate, and / or 2,6-toluyl diisocyanate as the diisocyanates. The use of hydroxylated polycarbonates with lower hydroxyl numbers reduces the cohesion of the resulting self-adhesive adhesives, and the use of hydroxylated polycarbonates with higher hydroxyl numbers reduces the self-adhesive properties (tack, adhesion) of cross-linked photoreactive adhesives. Due to the presence of unsaturated bonds in the polymer structure, the use of unsaturated hydroxylated rubbers leads to the reduction of its photoreactivity, and thus to the reduction of self-adhesive properties and reduction of the cohesion of UV cross-linked self-adhesive products. Preferably, the isocyanate-terminated polyurethane prepolymer is obtained in the presence of the catalyst in the form of tin organic compounds. Preferably, the catalyst is added in an amount of 0.5 to 1.5% by weight. Preferably, the radical photoinitiator is added in an amount of 0.1 to 5% by weight. The use of diols reduces the cohesion, measured at elevated temperature, of cross-linked urethane acrylate based pressure-sensitive adhesives. Ko ₂ preferably crosslinked radiation in the range of 200-1500 mJ / cm ^2. Preferably, the modification of the isocyanate groups of the polyurethane prepolymer with hydroxyl-containing acrylates is carried out at a temperature lower than the preparation temperature of the prepolymer, preferably at 25 ° C. Lowering the temperature allows the addition reaction to be carried out more safely.

An advantage of the process according to the invention is that the pressure-sensitive adhesives can be coated at a temperature of 80 to 100 ° C, which is a temperature significantly lower than the standard coating temperature. The new method makes it possible to eliminate the need to use specialized equipment

The coating temperature is 100 to 140 ° C, the temperature typical for coating hotmelt adhesives. The proposed method makes it possible to obtain photo-reactive solvent-free pressure-sensitive adhesives based on urethane acrylates, which can be used for the production of labels, decorative films and masking tapes.

The invention is illustrated in more detail by the following examples. The basic properties of the cross-linked pressure-sensitive adhesive layer obtained according to examples 1-6, such as tack (tack), adhesion (tack) and cohesion (internal strength of the adhesive) were measured according to the AFERA standard, used by the European Self-Adhesive Manufacturers Association: viscosity according to the AFERA 4105 standard, adhesion according to the AFERA 4001 standard and cohesion at room temperature and at 70 ° C according to the AFERA 4012 standard were tested on a Zwick / Roell Z1.0 testing machine. The results of the tests according to AFERA standards are presented in the table.

P r z k ł a d 1

To a 250 ml flask equipped with an anchor stirrer and a reflux condenser was added 100 g of a mixture consisting of 21.0 wt. % polypropylene glycol Voranol 1010 (Dow / USA), 5.8 wt. % of hydroxylated polycarbonate UH-CARB 300 (HZ = 38.1) (UBE / Japan), 30.0 wt. % hydroxylated saturated synthetic rubber Kraton Liquid L2203 (Shell / Netherlands) and 43.2 wt. isophorone diisocyanate (Bayer / Germany) in the presence of 1.0 wt. of tin dibutylolaurethanate (DBTL) catalyst. After the components were mixed, the flask with the reaction mixture was placed in a water bath at 50 ° C, while the contents of the flask were stirred for 2 h. The temperature of the reaction mixture in the flask was then reduced to 25 ° C, and 12.5 g of 2-hydroxyethyl acrylate (BASF) was slowly dropped to it. /Germany). After adding 3 g of the radical photoinitiator Irgacure 184 (BASF / Germany), the solvent-free pressure-sensitive adhesive obtained in this way was coated at 60 ° C with a ₂ clone on a polyester film, obtaining an adhesive film with a basis weight of 60 g / m ² , which was then crosslinked with ₂ UW radiation. with an intensity of 1000 mJ / cm ² . A single-sided adhesive tape was thus obtained.

P r z k ł a d 2

To a 250 ml flask equipped with an anchor stirrer and a reflux condenser was added 100 g of a mixture consisting of 42.0 wt. % polypropylene glycol Voranol 2000 (Dow / USA), 24.0 wt. % of hydroxylated polycarbonate UH-50 (HZ = 224.8) (UBE / Japan), 13.3 wt. % hydroxylated saturated synthetic rubber Kraton Liquid L2203 (Shell / Netherlands) and 20.7 wt. % hexamethylene diisocyanate (BASF / Germany) in the presence of 1.0 wt. of tin dibutylolaurethanate (DBTL) catalyst. After mixing the components, the flask with the reaction mixture was placed in a water bath at 50 ° C, while stirring the contents of the flask for 2 h. Then the temperature of the reaction mixture in the flask was reduced to 25 ° C, and 8.8 g of 4-hydroxybutyl acrylate ( BASF / Germany). After addition of 2.5 g of radical photoinitiator Irgacure 184 (BASF / Germany) thus obtained solvent-free pressure-sensitive adhesive coated on tempera ₂ at 60 ° C squeegee on a polyester film to give a film adhesive having a basis weight of 60 g / m ^2, which does not pedal ₂ crosslinked with UV radiation at the intensity of 1000 mJ / cm ² . A single-sided adhesive tape was thus obtained.

P r z k ł a d 3

To a 250 ml flask equipped with an anchor stirrer and a reflux condenser was added 100 g of a mixture consisting of 12.0 wt. % 1,6-hexanediol (BASF / Germany), 8.9 wt. % of hydroxylated polycarbonate UH-CARB 200 (HZ = 57.5) (UBE / Japan), 15.8 wt. % hydroxylated saturated synthetic rubber Kraton Liquid L2203 (Shell / Netherlands) and 28.2 wt. 1,5-naphthyl diisocyanate (Cytec / USA) in the presence of 1.0 wt. of tin di (2-ethylhexyl) laurethane catalyst. After the components were mixed, the flask with the reaction mixture was placed in a water bath at 50 ° C, while the contents of the flask were stirred for 2 h. The temperature of the reaction mixture in the flask was then reduced to 25 ° C, and 14.3 g of 2-hydroxypropyl acrylate (BP /Great Britain). After addition of 2 g of the radical photoinitiator Irgacure 127 (BASF / Germany) thus obtained solvent-free pressure-sensitive adhesive was coated at 60 ° C ra _two of the terminals on a polyester film to give a film adhesive having a basis weight of 60 g / m ^2, which was then cured ₂ UV with an intensity of 1000 mJ / cm ² . One-sided adhesive tape was obtained.

P r z k ł a d 4

To a 250 ml flask equipped with an anchor stirrer and a reflux condenser was added 100 g of a mixture consisting of 20.0 wt. % polypropylene glycol Voranol 1010 and 29.7 wt. % polypropylene glycol Voranol 2000 (Dow / USA), 25.3 wt. hydroxylated polycarbonate UH4

PL 219 938 B1

-CARB 100 (HZ = 110.1) (UBE / Japan), 34.0 wt. % hydroxylated saturated synthetic rubber Kraton Liquid L2203 (Shell / Netherlands) and 11.0 wt. trimethyl-1,6-hexamethylene diisocyanate (Evonik / Germany) in the presence of 1.0 wt. of tin dibutylolaurethanate (DBTL) catalyst. After the components were mixed, the flask with the reaction mixture was placed in a water bath at 50 ° C, while the contents of the flask were stirred for 2 h. The temperature of the reaction mixture in the flask was then reduced to 25 ° C, and 10.6 g of 2-hydroxyethyl acrylate (BASF) was slowly dropped to it. /Germany). After adding 3 g of the free radical photoinitiator Irgacure 127 (BASF / Germany), the solvent-free pressure-sensitive adhesive thus obtained was coated at 60 ° C with a squeegee on a polyester film, _{2 to} obtain an adhesive film with a basis weight of 60 g / m ² , which was then crosslinked with UV radiation ₂ intensity 1000 mJ / cm ² . One-sided adhesive tape was obtained.

P r z k ł a d 5

To a 250 ml flask equipped with an anchor stirrer and a reflux condenser was added 100 g of a mixture consisting of 38.5 wt. % polypropylene glycol Voranol 3000 (Dow / USA), 28.0 wt. % of hydroxylated polycarbonate UM-CARB 90 (HZ = 124.2) (UBE / Japan), 6.0 wt. % hydroxylated saturated synthetic rubber Kraton Liquid L2203 (Shell / Netherlands) and 13.5 wt. % isophorone diisocyanate (Bayer / Germany) and 14 wt. 2,6-toluyl diisocyanate (Cytec / USA) in the presence of 1.0 wt. of tin dibutylolaurethanate (DBTL) catalyst. After the components were mixed, the flask with the reaction mixture was placed in a water bath at 50 ° C, while the contents of the flask were stirred for 2 h. The temperature of the reaction mixture in the flask was then lowered to 25 ° C and 6 g of 2-hydroxyethyl acrylate (BASF / Germany) was slowly dropped into it. ) and 7.1 g of 4-hydroxybutyl acrylate (BASF / Germany). After adding 3 g of radical photoinitiator Irgacure 184 (BASF / Germany) thus obtained solvent-free of My adhesive coated in a temperatu _two carvings 60 ° C squeegee on a polyester film to give a film adhesive having a basis weight of 60 g / m ^2, which further _two cured UV with an intensity of 1000 mJ / cm ² . One-sided adhesive tape was obtained.

P r z k ł a d 6

To a 250 ml flask equipped with an anchor stirrer and a reflux condenser was added 100 g of a mixture consisting of 37.4 wt. % polypropylene glycol Voranol 1010 (Dow / USA), 26.6 wt. % of hydroxylated polycarbonate UHC 50-100 (HZ = 113) (UBE / Japan), 16.0 wt. % hydroxylated saturated synthetic rubber Kraton Liquid L2203 (Shell / Netherlands) and 20.0 wt. isophorone diisocyanate (Bayer / Germany) in the presence of 1.0 wt. of tin dibutylolaurethanate (DBTL) catalyst. After the components were mixed, the flask with the reaction mixture was placed in a water bath at 50 ° C, while the contents of the flask were stirred for 2 h. The temperature of the reaction mixture in the flask was then lowered to 25 ° C and 10 g of 2-hydroxyethyl acrylate (BASF / Germany) was slowly dropped into it. After adding 1.5 g of the radical photoinitiator MAPO (BASF / Germany), the thus obtained solvent-free pressure-sensitive adhesive was coated at a temperature of 60 ° C with a doctor blade ₂ on a polyester film, obtaining an adhesive film with a basis weight of 60 g / m ² , which was then cross-linked to beam ₂ UV radiation at an intensity of 1000 mJ / cm ^{2. A} single-sided adhesive tape was obtained.

T a b e l a

Self-adhesive glue according to the example Viscosity [N] Adhesion [N] Cohesion [N] 20 ° C 70 ° C 20 ° C 70 ° C 1 10.3 14.7 10.9 90 16 2 11.0 12.6 11.3 90 12 3 12.6 14.2 12.1 90 24 4 9.5 11.9 10.5 90 thirty 5 10.6 12.2 11.3 90 twenty 6 13.1 16.8 13.4 90 18

PL 219 938 B1

Claims (7)

1. Method for the production of photoreactive pressure-sensitive adhesives based on urethane acrylates, consisting in the modification of the isocyanate groups of a polyurethane prepolymer with acrylates containing hydroxyl groups and adding a photoinitiator and then crosslinking with UV radiation, characterized in that the polyurethane prepolymer containing isocyanate end groups is obtained by mixing 10-45% by weight aliphatic, cycloaliphatic and / or aromatic diisocyanates, 10-50% by weight of 1,6-hexanediol or polypropylene glycols with a molecular weight above 1000 g / mol, 5-30% by weight of hydroxylated polycarbonates having a hydroxyl number (HZ) between 35 and 225 and 5-35% by weight of hydroxylated saturated synthetic rubbers, the total weight of all components being 100%. 2. The method according to p. The process of claim 1, wherein the diisocyanates are trimethyl-1,6-hexamethylene diisocyanate (TMDI), hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI), 1,5-naphthyl diisocyanate, and / or 2,6-toluyl diisocyanate. 3. The method according to p. The process of claim 1, wherein the isocyanate-terminated polyurethane prepolymer is obtained in the presence of a catalyst in the form of tin organic compounds. 4. The method according to p. The process of claim 3, characterized in that the catalyst is added in an amount of 0.5 to 1.5% by weight. 5. The method according to p. The process of claim 1, wherein the radical photoinitiator is added in an amount of 0.1 to 5% by weight. 6. The method according to p. The method of claim 1, characterized in that it is cross-linked with radiation in the range 200-1500 mJ / cm ² . 7. The method according to p. The process of claim 1, wherein the modification of the isocyanate groups of the polyurethane prepolymer with acrylates containing hydroxyl groups is carried out at a temperature lower than the preparation temperature of the prepolymer, preferably at 25 ° C.