POLY- OR PREPOLYMER COMPOSITION, OR EMBOSSING LACQUER COMPRISING SUCH A COMPOSITION AND USE THEREOF

Abstract

Wth a prepolymer composition containing at least one mono or oligomer component with at least one polymerizable C—C double bond as well as at least one multifunctional monomer component, the multifunctional monomer component a multifunctional monomer component is contained with at least two thiol groups selected from the group: 3-Mercaptopropionates, 3-Mercaptoacetates, thioglycolates, and alkylthiols, wherein the mono or oligomer component with at least one polymerizable double bond is selected from the group acrylates, methyl acrylates, vinyl ethers, allyl ethers, propenyl ethers, alkenes, dienes, unsaturated esters, allyl triazines, allyl isocyanates, and N-vinyl amides, and wherein at least one surface-active anti-adhesive additive selected from the group alkyl (meth)acrylates, polysiloxane (meth)acrylates, perfluoroalkyl (meth)acrylates, perfluoropolyether (meth)acrylates, alkyl vinyl ethers, polysiloxane vinyl ethers, perfluoroalkyl vinyl ethers, and perfluoropolyether vinyl ethers, as well as a photoinitiator are contained, as well as the use thereof.

Claims

1. A prepolymer composition containing at least one mono or oligomer component having at least one polymerizable C—C double bond as well as at least one multifunctional monomer component, wherein the multifunctional monomer component is contained with at least two thiol groups selected from the group consisting of: 3-Mercaptopropionates, 3-Mercaptoacetates, thioglycolates, and alkyl thiols, wherein the mono or oligomer component having at least one polymerizable double bond is selected from the group consisting of acrylates, methyl acrylates, vinyl ethers, allyl ethers, propenyl ethers, alkenes, dienes, unsaturated ester, allyl triazines, allyl isocyanates, and N-vinyl amides, and wherein at least one surface-active anti-adhesive additive selected from the group consisting of alkyl-(meth)acrylates, poly-siloxane (meth)acrylates, perfluoroalkyl (meth)acrylates, perfluoropolyether (meth)acrylates, alkyl vinyl ethers, polysiloxane vinyl ethers, perfluoroalkyl vinyl ethers, and perfluoropolyether vinyl ethers, as well as one photoinitiator are included.

2. Prepolymer composition according to claim 1, wherein the multifunctional monomer component having at least two thiol groups is contained in a quantity of 1 to 50 wt %, particularly of 5 wt % to 30 wt %, and wherein two mono or oligomer components having at least one polymerizable double bond are contained in a total quantity of 1 wt % to 90 wt %, particularly of 10 wt % to 50 wt %.

3. Prepolymer composition according to claim 1, wherein urethane acrylate oligomers with a molecular weight between approximately 300 g/mol and 2500 g/mol are used as a mono or oligomer component having at least one polymerizable double bond.

4. Prepolymer composition according to claim 3, wherein the mono or oligomer components having at least one polymerizable double bond are selected from the group consisting of bifunctional urethane acrylate oligomers with a molecular weight between 300 g/mol and 1200 g/mol, trifunctional urethane acrylate oligomers with a molecular weight between 450 g/mol and 1750 g/mol, and tetrafunctional urethane acrylate oligomers with a molecular weight between approximately 500 g/mol and 2500 g/mol.

5. Prepolymer composition according to claim 1, wherein the surface-active anti-adhesive additive is contained in a quantity of 0.01 wt % to 10 wt %, particularly 0.1 wt % to 3 wt %.

6. Prepolymer composition according to claim 1, wherein the photoinitiator is selected from the group consisting of thioxanthones, ketosulfones, (alkyl-)benzyl phenyl phosphine oxides, 1-Hydroxy alkyl phenyl ketones or 2,2-Dimethoxy-1,2-diphenylethane-1-on.

7. Prepolymer composition according to claim 6, wherein the photoinitiator is contained in a quantity of 0.1 wt % to 10 wt %, particularly 0.5 wt % to 5 wt %.

8. Prepolymer composition according to claim 1, wherein at least one monomer component having at least one polymerizable double bond is contained as a reactive thinner.

9. Prepolymer composition according to claim 8, wherein the reactive thinner is selected from the group consisting of aliphatic (meth)acrylates or poly-ether(meth)acrylates, particularly HDDA or TMP(EO)xTA.

10. Prepolymer composition according to claim 9, wherein at least one multifunctional aliphatic or polyether(meth)acrylate, particularly TMP(EO).sub.9TA, TMP(EO)6TA, TMP(EO).sub.3TA or TMPTA is contained as a reactive thinner.

11. Prepolymer composition according to claim 1, wherein it has a viscosity of 0.01 Pas to 1 Pas.

12. Prepolymer composition according to claim 1, wherein an additive containing silicone or fluoride selected from the group consisting of mono or polyfunctional polydimethylsiloxane (meth)acrylates, perfluoro-n-alkyl (meth) acrylates or perfluoropolyether (meth) acrylates in a quantity of 0.1 wt % to 3 wt % is contained as a surface-active anti-adhesive additive.

13. Use of the prepolymer composition according to claim 1 as an embossing lacquer, wherein the hardened prepolymer composition has a modulus of elasticity between 50 MPa and 5 GPa.

14. Use of the prepolymer composition according to claim 13, wherein the embossing lacquer has a surface energy of 10 mJ/m.sup.2 to 60 mJ/m.sup.2.

15. Use of the prepolymer composition according to claim 13 for manufacturing self-moldable embossing stamps for UV imprinting largely identical types of polymers.

16. Use according to claim 13, wherein it is used for continual structuring and in situ UV hardening in a roll-to-roll imprint process.

Description

[0024] The invention will be explained in further detail below based on design examples as well as drawings. The following are shown there:

[0025] FIG. 1 a diagram, which shows the impact of the quantity of the multifunctional monomer component with at least two thiol groups on the conversion of the C—C double bonds in relation to the time for hardening of the prepolymer composition through UV irradiation,

[0026] FIG. 2 an analogous diagram as in FIG. 1, which shows the impact of the quantity of the mono or oligomer component on the conversion of the C—C double bonds in relation to the time for hardening of the prepolymer composition through UV irradiation,

[0027] FIG. 3 a diagram, which shows the impact of the components of the prepolymer on the dynamic viscosity of the prepolymer,

[0028] FIG. 4 a diagram, which shows the curve of the module of elasticity in relation to the concentration of individual components of the prepolymer,

[0029] FIG. 5 the change of surface energy of the prepolymer composition in relation to the quantity of the utilized anti-adhesive additive, and

[0030] FIGS. 6, 7 and 8 examples for the self-replication of embossing lacquers, which were produced based on the prepolymer composition according to the invention, wherein FIG. 6 shows urethane acrylate polymer stamp molded from a nickel master (FIG. 6a) and a polymer imprint (FIG. 6b) conducted therewith, FIG. 7 shows an analogous depiction, in which FIG. 7a shows a urethane acrylate master, FIG. 7b shows the urethane acrylate embossing stamp molded from that, and FIG. 7c shows the embossing lacquer produced with the foil in a urethane acrylate embossing lacquer on a foil, and FIG. 8 shows an example of the transfer of three-dimensional structures with a urethane acrylate embossing stamp according to the invention, wherein FIG. 8a shows the silicon imprinting master and FIG. 8b shows the imprint produced by means of a urethane acrylate polymer roller stamp in the roll-to-roll UV imprint process on foil.

[0031] Example 1 shows the impact of the addition of a multifunctional monomer component with at least two thiol groups on polymerization kinetics.

[0032] Specifically, varying quantities of trithiol (trimethylolpropane tris (3mercaptopropionate)), were respectively added to a prepolymer matrix containing 4.5% of a tetrafunctional urethane acrylate oligomer (UAO), 0.5% of an anti-adhesive additive, polydimethylsiloxane, 3% or 5% of a photoinitiator, i.e. 2-Hydroxy-2-methyl-1-phenyl propane-1-one as well as a reactive thinner TMP(EO).sub.3TA. With an increasing proportion of trithiols, the content of reactive thinner TMP(EO).sub.3TA reduces to the same degree. As is clearly evident in FIG. 1, the reaction kinetics is considerably accelerated the higher the share of trithiol. Furthermore, it is evident in FIG. 1 that the greater the content of trithiol is, the higher the content of unconverted double bonds is. Finally, it is evident in FIG. 1 that a complete conversion of all C—C double bonds has already occurred after a few seconds with a trithiol content of 30% and that an increase of the proportion of photoinitiator from 3% to 5% likewise leads to an acceleration of polymerization.

[0033] Thus, the higher the shares of trithiol or shares of multifunctional monomer components having at least two thiol groups are in the prepolymer composition, the faster the complete conversion of C—C double bonds is, wherein these prepolymer compositions can be used, e.g. as embossing lacquers (imprint embossing lacquers). An incomplete conversion of C—C double bonds in the short exposure time available of <1 s, with, e.g. 2 W/m.sup.2 in an R2R imprint process would cause sticky surface, through which a separation of the embossing lacquer from the stamp does not seem possible and, for example, the embossing lacquer may adhere to the stamp. The addition of multifunctional monomer components with at least two thiol groups enables such a rapid conversion of the C—C double bonds that the embossing lacquers can be used in a continuous roll-to-roll UV nanoimprint lithography process. An increase of the portion of urethane oligomer acrylate in a prepolymer matrix consisting of 9.5% trithiol, 0.5% polydimethyl siloxane as an anti-adhesive additive, 3% 2-Hydroxy-2-methyl-1-phenyl propane-1-one as a photoinitiator, and TMP(EO).sub.3TA as a residue-reactive thinner leads to a deceleration of polymerization kinetics, as can be recognized in FIG. 2. The higher the share of the urethane acrylate oligomer, i.e. the mono or oligomer component with at least one polymerizable double bond, the slower the polymerization kinetics become, which can be explained with an increase in viscosity and thus a reduction of the mobility of radicals. The consequence of this is a more rapid achievement of the gel point, a lower conversion rate, and finally a lower yield rate. It is evident in FIGS. 1 and 2 that a prepolymer composition must have a highest possible share of multifunctional monomer components with at least two thiol groups for the use as an imprint embossing lacquer. The following prepolymer composition is mentioned here as an example: 20% trithiol, 35%<x<60% UAO, (74.5-x) % TMP(EO).sub.3TA, 5% photoinitiator, and 0.5% of an anti-adhesive additive, which distinguishes itself through a complete conversion and thus produced embossing lacquers are distinguish by a particularly high scratch embossing lacquerance.

EXAMPLE 2

[0034] A prepolymer mixture consisting of a urethane acrylate oligomer, reactive thinner, photoinitiator, and multifunctional monomer component with at least two thiol groups, particularly trithiol as well as a photoinitiator, was studied with respect to the change of viscosity by analyzing the impact of the chain length of the oligomer component with at least one polymerizable double bond for viscosity, the concentration of the monomer component with at least two thiol groups for viscosity, as well as of the reactive thinner for viscosity. As can be seen in FIG. 3, the dynamic viscosity increases in relation to the chain length of the oligomer component with at least two polymerizable double bonds. From this test, we can see that the higher the share of the oligomer component is, the higher the viscosity of the prepolymer system is. Because it is beneficial for a roll-to-roll process if the prepolymer composition has a dynamic viscosity of less than 1.0 Pas—and it has proved in other tests that smooth, consistently thick layers can be achieved when using these prepolymer compositions. It is natural that the lower the viscosity of the embossing lacquer is, the more easily complicated structures of the imprint relief in the stamp can be sufficiently rapidly filled during a roll-to-roll imprint process and subsequently precisely transferred.

[0035] FIG. 3 reveals that an optimal prepolymer composition for an embossing lacquer or an embossing stamp material has a share of less than 60% of urethane acrylate oligomer with a molecular weight<1000 g/mol and that the concentration of other components, such as anti-adhesive additive, multifunctional monomer components with at least two thiol groups, photoinitiator, as well as the type of reactive thinner only have a minimal impact on the viscosity.

[0036] Example 3 shows how the mechanical strength, i.e. the reduced Young's modulus of elasticity* of the tetrafunctional UAO changes with 600 g/mol after exposure, i.e. cross-linking with through 1 min. of pre-hardening at 5 mW/cm.sup.2 with the Waldmann UV source and final hardening for 1 min. at 2.2 W/cm.sup.2 depending on the composition.

[0037] As can be seen in FIG. 4, the modulus of elasticity increases with an increase of the share of the oligomer component with at least one polymerizable double bond, such as a tetrafunctional urethane acrylate oligomer with different molecular weights between 600 g/mol to 1000 g/mol, in a prepolymer matrix consisting of (96.5-x) % TMP(EO).sub.3TA, wherein x is the quantity of the oligomer component with at least one polymerizable double bond or TMP(EO).sub.9TA or trithiol, as well as 3% of 2-Hydroxy-2-methyl-1-phenyl propane-1-one is used as a photoinitiator and 0.5% of polydimethylsiloxane acrylate is used as an anti-adhesive additive. The maximum elasticity* values are at 5 GPa with a concentration of 80% urethane acrylate oligomer, wherein the increase of the modulus of elasticity arises from the fact that the oligomers have a higher number of cross-linkable acrylate groups.

Table 1:

[0038] Similarly, it is shown that the modulus of elasticity of the hardened polymer decreases if the side arm length—i.e. the number of ethoxy groups—of the monomer components with at least one polymerizable double bond used as reactive thinners selected from TMPTA, TMP(EO).sub.3TA, TMP(EO.sub.6)TA, and TMP(EO.sub.9)TA increases, as can be seen in the following table. Furthermore, we can see from this table that the higher the molecular weight—i.e. the side are length—or the number f ethoxy groups—of the reactive thinner is, the greater the degree of conversion is of the double bonds, wherein the thinner was respectively introduced in a quantity of 65% of the total prepolymer composition. The polymer was hardened for 1 minute at 5 mW/cm.sup.2.

TABLE-US-00001 TABLE 1 100% DBC(%) E*[MPa] TMPTA 61 1701 TMP(EO).sub.3TA 77 1340 TMP(EO).sub.6TA 94 404 TMP(EO).sub.9TA 98 129

[0039] The result of the test in Example 3 is a decrease of the modulus of elasticity when trithiol is added, which largely relates to the lowering of the glass transition temperature during thiol polymerization—addition of trithiol.

[0040] Thus, 5% trithiol, 35≦x≦60% UOA, (89.5-x) % TMP(EO).sub.3xTA, 5% photoinitiator, and 0.5% of an anti-adhesive additive emerges as an ideal composition of a prepolymer for an embossing stamp with a high degree of hardness and 100% conversion through subsequent hardening. A rapid cross-linking is not so necessary for producing the embossing stamp because it is possible to imprint significantly slower in this case and subsequent hardening is also possible.

[0041] A second ideal composition for the embossing lacquer with a nearly complete conversion would be: 5% trithiol, 35≦x≦60% UAO, (89.5-x) % TMP(EO).sub.9TA, 5% photoinitiator, and 0.5% of an anti-adhesive additive, wherein no subsequent hardening is necessary.

[0042] Example 4 shows the impact of the quantity of an anti-adhesive additive on the surface energy of the prepolymer.

[0043] As can be seen in FIG. 5, the surface energy of the prepolymer can be extremely reduced during its hardening against air/argon by adding a perfluoropolyether acrylate (HFPO-A) as an anti-adhesive additive of concentrations that are less than 1%. In contrast, it is evident that if the hardening of the prepolymer occurs with respect to an untreated nickel surface, the high surface energy of the nickel in the embossing lacquer is “copied”, and despite the addition of an anti-adhesive additive no significant degradation of the surface energy of the imprinted polymers is achieved. On the other hand, if the hardening occurs during imprinting with respect to nickel surface treated with a fluorinated self-assembling alkyl monolayer, the lower surface energy of this monolayer will be copied and in turn the surface energy of the imprinted, hardened polymer is lowered, as can likewise be seen in FIG. 5.

[0044] Thus, we recognize that the addition of anti-adhesive additives to a prepolymer composition, any composition in a concentration between 0.1% and 0.5% occurs to a significant lowering of the surface energy when hardening with respect to a low-energetic surface, such that a defect-free demolding of the hardened polymer is enabled.

EXAMPLE 5

[0045] Self-replications of prepolymer compositions based on a mono or oligomer component with at least one polymerizable double bond and at least one multifunctional monomer component having at least two thiol groups.

[0046] The prepolymer compositions demonstrate excellent self-replicability, particularly in a roll-to-roll nanoimprint lithography process. To ensure that this self-replicability is present, the polymer stamp embossing lacquer must be completely hardened, i.e. completely CONVERTED. In FIG. 6, a polymer stamp based on a urethane acrylate oligomer is molded from a nickel master (FIG. 6a) and roll-to-roll molding is then conducted form that (FIG. 6b), from which we recognize that FIG. 6b represents a mirror image of FIG. 6a.

[0047] The replication of irregular and undercut 3D structures is depicted in FIG. 7, wherein the depicted figures are diatom structures. Here, FIG. 7a shows the urethane acrylate master; FIG. 7b shows urethane acrylate oligomer embossing stamp on foil molded from that, and FIG. 7c shows an imprint produced with the stamp from FIG. 7b by means of a roll-to-roll process in a urethane acrylate oligomer embossing lacquer according to the invention.

[0048] FIG. 8 shows that the transfer of 3D structures with undercuts with a high aspect ratio, such as in silicon-etched pillar structures in the urethane acrylate oligomer embossing lacquer is possible in roll-to-roll process. The positive Si master is shown here in FIG. 8a. A negative urethane acrylate oligomer embossing stamp was produced from this Si master and in FIG. 8b, the imprint produced with this embossing stamp in a roll-to-roll UV nanoimprint lithography process (R2R-UV-NIL) is depicted.

[0049] Here, FIGS. 6 to 8 are electron microscopic images from linear structures with a distance of 400 nm and a width of 600 nm, which were transferred into the urethane acrylate oligomer embossing lacquer in an R2R process at a speed of 10 m/min.

EXAMPLE 6

[0050] Manufacturing of Water and Dirt-Repellent Polymer Foils

[0051] The production of water-repellent and dirt-repellent or self-cleaning polymer foils with prepolymer compositions containing 10 wt % of 90 wt % of a mono or oligomer component with at least one polymerizable double bond, particularly low-viscous, multifunctional, aliphatic polyurethane acrylates, 10 wt % to 90 wt % of a multifunctional, reactive thinner selected from the aforementioned group, 1 wt % to 10 wt % of a photoinitiator, particularly 2-Hydroxy2-methyl-1-phenyl propane-1-one and 0.1 wt % to 3 wt % of a surface-active anti-adhesive polymer, particularly 1H,1H, 2H,2H-Tridecafluoroctyl acrylate, embossing lacquers having an extremely low surface energy of 12 mJ/m.sup.2 can be produced from the prepolymer composition. Because the surface additive is absorbed very efficiently on the embossing lacquer surface, it forms a dense monolayer with a high share of CF.sub.3, through which it is possible to produce foils, which—if an imprinting tool with a respectively reduced surface energy is simultaneously used, such as nickel stamp surfaces or silicon or quartz surfaces, as a stamp, which are respectively coated with long-chain active perfluoroalkyl phosphonic acids, such as 1H,1H, 2H,2H-Tridecafluoroctyl phosphonic acid—provide a stamp material, which likewise has a low surface energy of 12 mJ/m.sup.2. To further reduce the water/polymer contact surface, which must be as small as possible for a water-repellent or dirt-repellent effect, the embossing lacquer surface is subsequently micro or nanostructured, through which the contact angle can be raised with water to more than 170° with a simultaneously very low contact angle hysteresis and the slope angle of water droplets can be reduced to <2°. It is noted simply for comparison that smooth surfaces of the embossing lacquer have a contact angle of approx. 115° with water, such that the water-repellent effect can only be achieved with a strong tendency of the foil itself, whereas water cannot adhere to a nearly level surface either in the case of a structured foil.