Permeation-inhibiting release coating

1. A permeation-inhibiting release coating obtained by curing a composition comprising components (I), (II) and optionally (III):

(I) 20 to 90% by weight, based on a sum total of components (I), (II) and (III) of the composition, comprises silicon-free hydrocarbons which consist of carbon, hydrogen and oxygen and which have at least one ethylenically unsaturated free-radically polymerizable group and has no oxyethylene groups,

wherein component (I) has a hydrocarbon to an extent of at least 80 and up to 100% by weight, based on a total mass of component (I), having two or more ethylenically unsaturated free-radically polymerizable groups and at least one aromatic group;

(II) 10 to 90% by weight, based on a sum total of components (I), (II) and (III) of the composition, of one or more organomodified silicones having 50 to 500 silicon atoms, wherein 0.4 to 10% of silicon atoms optionally have ethylenically unsaturated free-radically polymerizable groups; and

(III) 0 to 70% by weight, based on a sum total of components (I), (II) and (III) of the composition, of one or more organomodified silicones having 4 to 40 silicon atoms, wherein 15 to 100% of silicon atoms have ethylenically unsaturated free-radically polymerizable groups; and

optionally an additive;

wherein the permeation-inhibiting release coating has a permeation barrier against butyl acetate, and the permeation-inhibiting release coating has a delta-L* value of from 1 to 20.

2. The permeation-inhibiting release coating according claim 1 , wherein the delta-L* value is from 1 to 18.

3. The permeation-inhibiting release coating according to claim 1 , wherein the permeation-inhibiting release coating has a release force of at most 80 cN/2.5 cm, wherein a lower value of the release force is greater than 1 cN/2.5 cm, and wherein the release force is determined in accordance with FINAT Handbook 8th Edition, The Hague/NI, 2009 under the designation FTM 10.

4. The permeation-inhibiting release coating according to claim 1 , wherein the ethylenically unsaturated free-radically polymerizable groups in components (I) and (III) and/or ethylenically unsaturated free-radically polymerizable groups, if present in component (II) are groups selected from an acrylic ester function, a methacrylic ester function or both.

5. The permeation-inhibiting release coating according to claim 1 , wherein

component (I) is present at 20 to 70% by weight,

component (II) is present at 30 to 80% by weight, and

component (III) is present at 0 to 40% by weight, all based on the sum total of components (I), (II) and (III) of the composition.

6. The permeation-inhibiting release coating according to claim 1 , wherein the component (II) comprises a compound of formula (I):

M 1 a M 2 b D 1 c D 2 d   (I)

wherein M 1 =[R 1 3 SiO 1/2 ],

M 2 =[R 1 2 R 2 SiO 1/2 ],

D 2 =[R 1 2 SiO 2/2 ],

D 2 =[R 1 R 2 SiO 2/2 ],

a=0to 2,

b=0to 2, and a+b=2,

c=50 to 490,

d=0 to 15, and

a ratio of the sum (b+d) to the sum (c+d+2) is from 0.004 up to 0.1,

the sum (c+d+2) is 50 to 500,

R 1 denotes identical or different aliphatic hydrocarbons having 1 to 10 carbon atoms or aromatic hydrocarbons having 6 to 12 carbon atoms, and

R 2 denotes identical or different hydrocarbons which have 1 to 5 identical or different ester functions, and the hydrocarbon is linear, cyclic, branched and/or aromatic.

7. The permeation-inhibiting release coating according to claim 1 , wherein the component (III) comprises a compound of formula (II):

M 1 e M 3 f D 1 g D 3 h   (II)

wherein

M 1 =[R 1 3 SiO 1/2 ],

M 3 =[R 1 2 R 3 SiO 1/2 ],

D 1 =[R 1 2 SiO 2/2 ],

D 3 =[R 1 R 3 SiO 2/2 ],

e=0 to 2 ,

f=0 to 2, and e+f=2,

g=0 to 38,

h=0 to 20 and

a ratio of the sum (f+h) to the sum (g+h+2) is from 0.15 up to 1,

the sum (g+h+2) is from 4 to 40,

R 1 denotes identical or different aliphatic hydrocarbons having 1 to 10 carbon atoms or aromatic hydrocarbons having 6 to 12 carbon atoms, and

R 3 denotes identical or different hydrocarbons which have 1 to 5 identical or different ester functions, and the hydrocarbon is linear, cyclic, branched and/or aromatic.

8. The permeation-inhibiting release coating according to claim 1 , wherein component (III) comprises ester groups that are not free-radically polymerizable.

9. The permeation-inhibiting release coating according to claim 1 , wherein ester groups that are not free-radically polymerizable are not present in component (II) and ester groups that are not free-radically polymerizable are present in component (III) in a numerical proportion of 5 to 15%, based on the number of all ester functions in component (III).

10. A method for preparing the permeation-inhibiting release coating according to claim 1 , the method comprising:

radiation-curing the permeation-inhibiting release coating.

11. A topcoat for thermal papers, comprising:

a permeation-inhibiting release coating obtained by curing a composition comprising components (I), (II) and optionally (III):

(I) 20 to 90% by weight, based on a sum total of components (I), (II) and (III) of the composition, comprises silicon-free hydrocarbons which consist of carbon, hydrogen and oxygen and which have at least one ethylenically unsaturated free-radically polymerizable group and have no oxyethylene groups,

wherein component (I) has a hydrocarbon to an extent of at least 80 and up to 100% by weight, based on a total mass of component (I), having two or more ethylenically unsaturated free-radically polymerizable groups and at least one aromatic group;

(II) 10 to 90% by weight, based on a sum total of components (I), (II) and (III) of the composition, of one or more organomodified silicones having 50 to 500 silicon atoms; and

(III) 0 to 70% by weight, based on a sum total of components (I), (II) and (III) of the composition, of one or more organomodified silicones having 4 to 40 silicon atoms, wherein 15 to 100% of silicon atoms have ethylenically unsaturated free-radically polymerizable groups; and

optionally an additive;

wherein the permeation-inhibiting release coating has a permeation barrier against butyl acetate, and the permeation-inhibiting release coating has a delta-L* value of from 1 to 20.

12. The topcoat according to claim 11 , wherein the thermal paper is self-adhesive and is designed as adhesive tape.

13. A radiation-curing coating composition for preparing a permeation-inhibiting release coating having a permeation barrier against butyl acetate, the permeation-inhibiting release coating comprising components (I), (II) and optionally (III):

(I) 20 to 90% by weight, based on a sum total of components (I), (II) and (III) of the composition, comprises silicon-free hydrocarbons which consist of carbon, hydrogen and oxygen and which have at least one ethylenically unsaturated free-radically polymerizable group and have no oxyethylene groups,

wherein component (I) has a hydrocarbon to an extent of at least 80 and up to 100% by weight, based on a total mass of component (I), having two or more ethylenically unsaturated free-radically polymerizable groups and at least one aromatic group;

(II) 10 to 90% by weight, based on a sum total of components (I), (II) and (III) of the composition, of one or more organomodified silicones having 50 to 500 silicon atoms; and

(III) 0 to 70% by weight, based on a sum total of components (I), (II) and (III) of the composition, of one or more organomodified silicones having 4 to 40 silicon atoms, wherein 15 to 100% of the silicon atoms have ethylenically unsaturated free-radically polymerizable groups; and

an additive,

wherein the permeation-inhibiting release coating has a delta-L* value of from 1 to 20.

14. The radiation-curing coating composition according to claim 13 , wherein the additive is at least one selected from the group consisting of a photoinitiator, a photosensitizer, a filler, a pigment, a solvent, a phosphorus-containing compound which polymerizes under UV light, a stabilizer, an anti-misting additive and an amine synergist.