JP5255278B2 - Polymerizable liquid crystal mixture - Google Patents

Description

Detailed Description of the Invention

(Technical field)
The present invention relates to a polymerizable mixture, its use in the production of a polymer film having improved adhesion to a substrate, a process for the production of such a polymer film, a multilayer film comprising such a polymer film, as well as said mixture or film Relates to the use of optical, electro-optical, decorative or security devices and applications.

(Background technology)
Polymerizable liquid crystal (LC) materials are usually used in the production of optical films in liquid crystal displays. These substances usually contain a certain amount of a compound (bifunctional or polyfunctional) having two or more polymerizable groups, and these are crosslinked to obtain a hard film. However, these hard films often do not readily adhere to plastic substrate surfaces commonly used in the manufacturing process because of the shrinkage of the film during the polymerization and crosslinking process. Thus, films made from such LC materials are usually peeled off and rebonded to other substrates such as polarizer glass or plastic used in liquid crystal displays. However, both stripping and application to alternative substrates are time and materially expensive. It also gives rise to two possible points in time where film loss can be caused by degradation during peeling or relamination, resulting in a reduction in the overall yield of the product.
In the prior art, it has also been reported that an LC polymer film is bonded to a plastic substrate using an adhesive layer and an alignment layer. For example, US Pat. No. 5,631,051 discloses a method for producing an optical compensation sheet on a transparent substrate of TAC by first applying a gelatin adhesion layer onto a triacetylcellulose (TAC) film. Thereafter, the alignment layer is coated with a solution of modified polyvinyl alcohol (PVA) chemically modified by addition of a polymerizable group on the gelatin layer, the solvent is evaporated, and the surface of the polymerized PVA layer is integrated. It is formed by rubbing in the direction. Finally, an optically anisotropic layer containing a discotic LC material is coated on the rubbed surface of the PVA layer and polymerized.

U.S. Pat.No. 5,747,121 describes coating a solution of modified polyvinyl alcohol (PVA) chemically modified by addition of polymerizable groups onto a transparent substrate, evaporating the solvent, and rubbing the surface of the PVA layer in one direction. Discloses an optical compensation sheet manufacturing method. Next, an optically anisotropic layer containing a discotic LC material is coated on the rubbed surface of the PVA layer and polymerized. The film is then subjected to a heat treatment whereby the PVA layer and the discotic LC layer are reported to be chemically bonded to each other through free crosslinkable groups.
However, the above method requires many separate coating steps. Furthermore, the use of several interlayers such as adhesive layers or alignment layers containing isotropic materials such as gelatin or PVA can negatively affect the optical performance of the optical film.
GB 2 398 077 describes a method for preparing a crosslinked LC film having good adhesion by using a polymerizable LC material comprising a crosslinkable compound having two or more polymerizable groups not greater than 7% by weight. Disclosure. Such films adhere well to plastic substrates as commonly used in the optical film industry. However, since this low cross-linked LC film is soft and may be sensitive to mechanical stress, it is preferably coated with a hard coat or with further polymerized LC film containing a high degree of cross-linking.

(Disclosure of the Invention)
(Problems to be solved by the invention)
Thus, it provides a film of crosslinked LC material that adheres well to plastic substrates, saves processing time and reduces losses due to degradation during processing of the LC film, making the film a harder surface and mechanical There is a need for an advantageous method with greater stability to stress or degradation.
The object of the present invention is to provide a crosslinked LC film which does not have the above-mentioned drawbacks, as well as methods and materials for its production. Other objects of the invention will be immediately apparent to the skilled person from the following description.
The above objectives have been solved by providing films, methods and materials according to the present invention as described above and below.

Definition of the Term The term “film” includes a rigid or flexible, self-supporting or free-standing film having mechanical stability, as well as a coating or layer on or between two supporting substrates.
The term “liquid crystal or mesogenic material” or “liquid crystal or mesogenic compound” refers to a material containing one or more columnar, plate or disc mesogenic groups, ie, groups having the ability to induce liquid crystal (LC) phase behavior. Or means a compound. LC compounds having columnar or plate-like groups are also known in the art as “calamitic” liquid crystals. LC compounds with discotic groups are also known in the art as “discotic” liquid crystals. A compound or substance containing a mesogenic group does not necessarily have to exhibit the LC phase itself. These substances or compounds can also exhibit LC phase behavior only in a mixture with other compounds or when polymerized mesogenic compounds or substances or mixtures thereof.
In the following, for simplicity, the term “liquid crystal material” is used for both mesogenic and LC materials.
A polymerizable compound having one polymerizable group is also referred to as a “monoreactive” compound, a polymerizable compound having two polymerizable groups is also referred to as a “bireactive” compound, and has three or more polymerizable groups. Polymeric compounds having are also referred to as “multi-reactive” compounds. A compound having no polymerizable group is also referred to as a “non-reactive” compound. Multi-reactive compounds are also referred to as “crosslinkable” compounds.
The term “reactive mesogen” (RM) means a polymerizable mesogenic or liquid crystal compound.

Unless otherwise specified, in the following, the mass percentage (mass%) of each solid or liquid crystal compound in the polymerizable liquid crystal material is based on the total amount of the solid or liquid crystal compound in the material.
The term “director” means the preferred orientation direction of the long molecular axis (in the case of calamitic compounds) or short molecular axis (in the case of discotic compounds) of the mesogenic group in the LC material.
In films containing uniaxially positive doubly refractive LC materials, the optical axis is provided by the director.
The term “cholesteric structure” or “spiral twist structure” refers to a film containing LC molecules in which the director is twisted spirally about an axis that is parallel to the film plane and perpendicular to the film plane.
The term “homeotropic structure” or “homeotropic orientation” refers to a film whose optical axis is substantially perpendicular to the film plane.
The term “planar structure” or “planar orientation” refers to a film whose optical axis is substantially parallel to the film plane.
The term “tilted structure” or “tilted orientation” refers to a film whose optical axis is tilted at an angle θ from 0 to 90 ° with respect to the film plane.
The term “bevel structure” or “bevel orientation” means a tilt orientation as defined above in which the tilt angle varies in a direction perpendicular to the film plane, preferably from a minimum value to a maximum value.

(式中、Pは、重合性の基であり；
Spは、スペーサー基または一重結合であり；
Aは、芳香族または脂肪族の5員または6員環、或いは２または３個の縮合芳香族または脂肪族5員または6員環を含む基であり；これらの環は、必要に応じて、N、OおよびSから選ばれた１個以上のヘテロ原子を含有し、さらに、必要に応じて、１個以上の同一または異なる基L¹によって置換されており；
Zは、複数存在する場合は互いに独立して、-O-、-S-、-CO-、-COO-、-OCO-、-S-CO-、-CO-S-、-O-CO-O-、-CO-NR⁰-、-NR⁰-CO-、-OCH₂-、-CH₂O-、-SCH₂-、-CH₂S-、-CF₂O-、-OCF₂-、-CF₂S-、-SCF₂-、-CH₂CH₂-、-CF₂CH₂-、-CH₂CF₂-、-CF₂CF₂-、-CH=CR⁰-、-CH=CH-、-CH=CF-、-CY¹=CY¹-、-C≡C-、-CH=CH-COO-、-OCO-CH=CH-または一重結合であり；
Z¹は、Zの意味の１つを有し；
R⁰およびR⁰⁰は、互いに独立して、Hまたは1〜12個のC原子を有するアルキルであり；
Y¹およびY²は、互いに独立して、H、F、ClまたはCNであり；
mは、0または1であり；
L¹、L²は、互いに独立して、F、Cl、Br、I、CN、NO₂、P-Sp-、或いは1〜12個のC原子を有し、１個以上のH原子が必要に応じてFまたはClによって置換されているアルキル、アルコキシ、アルキルカルボニル、アルコキシカルボニル、アルキルカルボニルオキシまたはアルコキシカルボニルオキシであり；
r1およびr2は、互いに独立して、0、1、2、3または4である)。 (Means for solving the problem)
The invention comprises a)> 0-12% of one or more crosslinkable compounds, preferably crosslinkable mesogenic compounds, and b) ≧ 50% of one or more compounds of formula I On the mixture to:

(Wherein P is a polymerizable group;
Sp is a spacer group or a single bond;
A is an aromatic or aliphatic 5- or 6-membered ring, or a group containing 2 or 3 fused aromatic or aliphatic 5- or 6-membered rings; these rings are optionally Contains one or more heteroatoms selected from N, O and S, optionally further substituted by ^one or more identical or different groups L ¹ ;
Z is independently from each other when there are a plurality of Z, -O-, -S-, -CO-, -COO-, -OCO-, -S-CO-, -CO-S-, -O-CO- O-, -CO-NR ^0- , -NR ⁰ -CO-, -OCH _2- , -CH ₂ O-, -SCH _2- , -CH ₂ S-, -CF ₂ O-, -OCF _2- , -CF ₂ S-, -SCF _2- , -CH ₂ CH _2- , -CF ₂ CH _2- , -CH ₂ CF _2- , -CF ₂ CF _2- , -CH = CR ^0- , -CH = CH -, -CH = CF-, -CY ¹ = CY ^1- , -C≡C-, -CH = CH-COO-, -OCO-CH = CH- or a single bond;
Z ¹ has ^one of the meanings of Z;
R ⁰ and R ⁰⁰ are independently of each other H or alkyl having 1 to 12 C atoms;
Y ¹ and Y ² are independently of each other H, F, Cl or CN;
m is 0 or 1;
L ¹ and L ² are independently of each other, F, Cl, Br, I, CN, NO ₂ , P-Sp-, or 1 to 12 C atoms, and one or more H atoms are required Alkyl, alkoxy, alkylcarbonyl, alkoxycarbonyl, alkylcarbonyloxy or alkoxycarbonyloxy, optionally substituted by F or Cl;
r1 and r2 are independently of each other 0, 1, 2, 3 or 4.

The invention further relates to a polymer film obtained by crosslinking a compound according to the invention.
The invention further relates to the use of the mixtures or films according to the invention in optical, electro-optical, information storage, decoration and security applications.
Furthermore, the invention also relates to an optical component or device comprising a mixture or film according to the invention.
The invention further relates to a liquid crystal display comprising a mixture or film according to the invention.
The invention further relates to an appraisal, verification or security mark or color image comprising a mixture or film according to the invention.
Furthermore, the present invention also relates to valuable objects or documents including appraisal, verification or security marks or images as described above and below.

から選ばれ、Lは、式IのL¹の意味の１つを有する。
ハロゲンは、好ましくは、FまたはClである。
Y¹およびY²は、好ましくはHまたはFである。 (Best Mode for Carrying Out the Invention)
In each of the formulas above and below, A is preferably selected from 1,4-phenylene or trans-1,4-cyclohexylene optionally substituted with ¹ to 4 groups L ¹ as described above. It is.
Z ¹ is preferably selected from —COO—, —OCO—, —CH ₂ CH ₂ —, —CH═CH— or a single bond, particularly preferably —COO— or —OCO—.
Z is preferably selected from —COO—, —OCO—, —CH ₂ CH ₂ —, —CH═CH—, or a single bond.
L ¹ and L ² are preferably F, Cl, CN, NO ₂ , CH ₃ , C ₂ H ₅ , OCH ₃ , OC ₂ H ₅ , COCH ₃ , COC ₂ H ₅ , COOCH ₃ , COOC ₂ H ₅ , CF ₃ , OCF ₃ , OCHF ₂ or OC ₂ F ₅ , especially F, Cl, CN, CH ₃ , C ₂ H ₅ , OCH ₃ , COCH ₃ or OCF ₃ , most preferably F, Cl, CH ₃ , OCH Selected from ₃ or COCH ₃ .
r1 and r2 are preferably 0, 1 or 2.
The substituted phenylene is preferably:

And L has ^one of the meanings of L ¹ in formula I.
Halogen is preferably F or Cl.
Y ¹ and Y ² are preferably H or F.

、CH₂=CW²-(O)_k1-、CH₃-CH=CH-O-、(CH₂=CH)₂CH-OCO-、(CH₂=CH-CH₂)₂CH-OCO-、(CH₂=CH)₂CH-O-、(CH₂=CH-CH₂)₂N-、(CH₂=CH-CH₂)₂N-CO-、HO-CW²W³-、HS-CW²W³-、HW²N-、HO-CW²W³-NH-、CH₂=CW¹-CO-NH-、CH₂=CH-(COO)_k1-Phe-(O)_k2-、Phe-CH=CH-、HOOC-、-OCN-、およびW⁴W⁵W⁶Si-から選ばれ； W¹は、H、Cl、CN、フェニルまたは１〜5個のC原子を有するアルキル、とりわけ、H、ClまたはCH₃であり；W²およびW³は、互いに独立して、Hまたは１〜5個のC原子を有するアルキル、とりわけ、メチル、エチルまたはn-プロピルであり；W⁴、W⁵およびW⁶は、互いに独立して、Cl、１〜5個のC原子を有するオキサアルキルまたはオキサカルボニルアルキルであり；Pheは、１個以上の上述したような基Lによって必要に応じて置換した1,4-フェニレンであり；k1およびk2は、互いに独立して、0または1である。
とりわけ好ましくは、Pは、ビニル基、アクリレート基、メタクリレート基、オキセタン基またはエポキシ基、とりわけ好ましくは、アクリレート基またはメタクリレート基である。 The reactive or polymerizable group P can participate in a polymerization reaction such as radical or ionic chain polymerization, polyaddition or polycondensation, or in the polymer main chain in a polymeranaloguous reaction, for example by condensation or addition. It is a group that can be grafted. Especially preferred are polymerizable groups for chain polymerization reactions such as radical, cationic or anionic polymerization. Highly preferred are polymerizable groups containing CC double or triple bonds and polymerizable groups that can be polymerized by ring opening reactions, such as oxetanes or epoxides.
Most preferably, the polymerizable or reactive group P is CH ₂ ═CW ¹ —COO—,

^{_{, CH 2 = CW 2 - (}} O) k1 -, CH 3 -CH = CH-O -, (CH 2 = CH) 2 CH-OCO -, (CH 2 = CH-CH 2) 2 CH-OCO-, (CH ₂ = CH) ₂ CH-O-, (CH ₂ = CH-CH ₂ ) ₂ N-, (CH ₂ = CH-CH ₂ ) ₂ N-CO-, HO-CW ² W ^3- , HS- CW ² W ^3- , HW ² N-, HO-CW ² W ³ -NH-, CH ₂ = CW ¹ -CO-NH-, CH ₂ = CH- (COO) _k1 -Phe- (O) _k2- , Phe-CH = CH-, HOOC-, -OCN-, and W ⁴ W ⁵ W ⁶ Si-; W ¹ is H, Cl, CN, phenyl or alkyl having 1 to 5 C atoms, In particular H, Cl or CH ₃ ; W ² and W ³ , independently of one another, are H or alkyl having 1 to 5 C atoms, in particular methyl, ethyl or n-propyl; W ⁴ , W ⁵ and W ⁶ , independently of one another, are Cl, oxaalkyl or oxacarbonylalkyl having 1 to 5 C atoms; Phe is optionally substituted by one or more groups L as described above Substituted 1,4-phenylene; k1 and k2 are independently of each other 0 The other is 1.
Particularly preferably P is a vinyl, acrylate, methacrylate, oxetane or epoxy group, particularly preferably an acrylate or methacrylate group.

As for the spacer group Sp, all groups known for this purpose to those skilled in the art can be used. The spacer group Sp preferably has the formula Sp′-X such that P-Sp is P-Sp′-X—, where Sp ′ is 1-20 C atoms, preferably 1 Having ˜12 C atoms, optionally mono- or polysubstituted by F, Cl, Br, I or CN, and more than one non-adjacent CH ₂ group optionally In each case, independently of each other, O and / or S atoms are not directly bonded to each other, -O-, -S-, -NH-, -NR ^0- , -SiR ⁰ R ^00- , -CO-, -COO-, -OCO-, -OCO-O-, -S-CO-, -CO-S-, -NR ⁰ -CO-O-, O-CO-NR ^0- , -NR ⁰ Alkylene substituted by -CO-NR ^0- , -CH = CH- or -C≡C-; X is -O-, -S-, -CO-, -COO-, -OCO-, -O-COO -, - CO- NR 0 -, - NR 0 -CO -, - NR 0 -CO-NR 0 -, - OCH 2 -, - CH 2 O -, - SCH 2 -, - CH 2 S -, -CF ₂ O-, -OCF _2- , -CF ₂ S-, -SCF _2- , -CF ₂ CH _2- , -CH ₂ CF _2- , -CF ₂ CF _2- , -CH = N- , -N = CH-, -N = N-, -CH = CR ^0- , -CY ¹ = CY ^2- , -C≡C-, -C H═CH—COO—, —OCO—CH═CH— or a single bond; R ⁰ and R ⁰⁰ are independently of each other H or alkyl having 1 to 12 C atoms; and Y ¹ and Y ² are independently of each other H, F, Cl or CN.
X is preferably, -O -, - S -, - OCH 2 -, - CH 2 O -, - SCH 2 -, - CH 2 S -, - CF 2 O -, - OCF 2 -, - CF 2 S-, -SCF _2- , -CH ₂ CH _2- , -CF ₂ CH _2- , -CH ₂ CF _2- , -CF ₂ CF _2- , -CH = N-, -N = CH-, -N = N-, -CH = CR ^0- , -CY ¹ = CY ^2- , -C≡C- or a single bond, especially -O-, -S-, -C≡C-, -CY ¹ = CY ² -Or a ^single bond, very preferably a group or a single bond capable of forming a conjugated system such as -C≡C- or -CY ¹ = CY ^2- .
Typical Sp ′ is, for example, — (CH ₂ ) _p —, — (CH ₂ CH ₂ O) _q —CH ₂ CH ₂ —, —CH ₂ CH ₂ —S—CH ₂ CH ₂ — or —CH ₂ CH ₂ —NH—CH ₂ CH ₂ — or — (SiR ⁰ R ⁰⁰ —O) _p —, p is an integer from 2 to 12, q is an integer from 1 to 3, R ⁰ and R ⁰⁰ Has the meaning indicated above.
Preferred groups Sp ′ are, for example, ethylene, propylene, butylene, pentylene, hexylene, heptylene, octylene, nonylene, decylene, undecylene, dodecylene, octadecylene, ethyleneoxyethylene, methyleneoxybutylene, ethylene-thioethylene, ethylene-N-methyl. -Iminoethylene, 1-methylalkylene, ethenylene, propenylene and butenylene.
Further preferred are compounds in which Sp is a single bond.

(式中、P、Sp、L¹、L²、r1およびr2は、式Iにおいて示した意味を有する)
を有する１種以上の化合物；
‐r1およびr2が0である式IまたはIaを有する１種以上の化合物；
‐r1およびr2が1である式IまたはIaを有する１種以上の化合物；
‐r1およびr2の片方が0であり他方が1である式IまたはIaを有する１種以上の化合物；
‐下記の式II：

(式中、PおよびSp、L¹、L²、r1およびr2は、式Iにおいて定義したとおりであり；L³は、式IにおけるL¹の意味の１つを有し；r3は、0、1、2、3または4であり；Z¹およびZ²は、式IにおけるZの意味の１つを有する)
を有する１種以上の架橋性メソゲニック化合物；
‐r2およびr3が0であり、r1が0、1または2である式IIを有する１種以上の化合物；
‐Z¹およびZ²が、-COO-、-OCO-、-CH₂CH₂-および一重結合から選ばれる式IIを有する１種以上の化合物；
‐下記の式IIa：

(式中、PおよびSp、L¹およびr1は、式IIにおいて定義したとおりであり、r1は、好ましくは、0または1であり；L¹は、好ましくは、Cl、CH₃またはOCH₃である)
を有する１種以上の架橋性メソゲニック化合物；
‐下記の式III：

(式中、PおよびSpは、式Iにおいて定義したとおりであり；Rは、1〜12個のC原子を有するアルキル、アルコキシ、アルキルカルボニル、アルコキシカルボニル、アルキルカルボニルオキシまたはアルコキシカルボニルオキシであり、１個以上のH原子は、必要に応じて、FまたはClによって置換されている)
を有する１種以上の化合物を含むさらなる成分c)；
‐5〜12％の１種以上の架橋性化合物；
‐>7〜12％の１種以上の架橋性化合物；
‐50〜80%、好ましくは55〜75％の式IまたはIaを有する１種以上の化合物；
‐5〜50%、好ましくは10〜40%の式IIIを有する１種以上の化合物；
‐a) > 0〜12%の１種以上の架橋性化合物、
‐b) >50%の式IまたはIaを有する１種以上の化合物、
‐c) 任意成分としての式IIIを有する１種以上の化合物、
‐d) 好ましくは0.5〜8％の濃度の１種以上の光開始剤、
‐e) 好ましくは0.1〜2%の濃度の、任意成分としての１種以上の界面活性剤、
‐f) 任意成分としての１種以上の安定剤。
重合性LC混合物の透明点は、好ましくは少なくとも50℃、極めて好ましくは少なくとも60℃である。 Preferred mixtures include:
The following formula Ia:

(Wherein P, Sp, L ¹ , L ² , r1 and r2 have the meanings indicated in formula I)
One or more compounds having:
One or more compounds having the formula I or Ia, wherein r1 and r2 are 0;
One or more compounds having the formula I or Ia, wherein r1 and r2 are 1;
One or more compounds having the formula I or Ia, wherein one of r1 and r2 is 0 and the other is 1;
-Formula II below:

(Wherein P and Sp, L ¹ , L ² , r ¹ and r ² are as defined in formula I; L ³ has ^one of the meanings of L ¹ in formula I; r 3 is 0 , 1, 2, 3 or 4; Z ¹ and Z ² have one of the meanings of Z in formula I)
One or more crosslinkable mesogenic compounds having:
One or more compounds having the formula II, wherein r2 and r3 are 0 and r1 is 0, 1 or 2;
One or more compounds having the formula II, wherein Z ¹ and Z ² are selected from —COO—, —OCO—, —CH ₂ CH ₂ — and a single bond;
-Formula IIa below:

Wherein P and Sp, L ¹ and r ¹ are as defined in formula II, r ¹ is preferably 0 or 1; L ¹ is preferably Cl, CH ₃ or OCH ₃ is there)
One or more crosslinkable mesogenic compounds having:
-Formula III below:

Wherein P and Sp are as defined in Formula I; R is alkyl, alkoxy, alkylcarbonyl, alkoxycarbonyl, alkylcarbonyloxy or alkoxycarbonyloxy having 1 to 12 C atoms; One or more H atoms are optionally replaced by F or Cl)
A further component c) comprising one or more compounds having
-5-12% of one or more crosslinkable compounds;
-> 7-12% of one or more crosslinkable compounds;
One or more compounds having the formula I or Ia of -50 to 80%, preferably 55 to 75%;
One or more compounds having the formula III of -5 to 50%, preferably 10 to 40%;
-A)> 0-12% of one or more crosslinkable compounds,
-B) one or more compounds having formula I or Ia> 50%,
-C) one or more compounds having formula III as an optional component,
-D) one or more photoinitiators, preferably in a concentration of 0.5-8%,
-E) one or more surfactants as optional ingredients, preferably in a concentration of 0.1-2%,
-F) one or more stabilizers as optional ingredients.
The clearing point of the polymerizable LC mixture is preferably at least 50 ° C, very preferably at least 60 ° C.

The present invention also relates to a method for producing a polymer film according to the following steps:
Applying a layer of the mixture according to the invention on the substrate;
-Aligning the mixture, if necessary, so that the mesogenic or LC compound acquires a uniform orientation;
-Crosslinking the mixture to form a polymer film; and
-Peeling the polymer film from the substrate, if necessary.
The thickness of the polymer film according to the invention is preferably from 0.5 to 5 μm, very preferably from 1 to 2 μm.
The LC molecules in the polymer film preferably have a planar orientation.
The polymer film according to the invention has a limited crosslink density due to the low amount of crosslinkable compound, and in particular exhibits good adhesion to plastic substrates. Thus, the polymer film according to the present invention can be used as an adhesive or base coating to subsequent LC layers that would otherwise not adhere well to the substrate. At the same time, the polymer film has a hard surface with low tack and improved durability compared to prior art low cross-linked films.
Also, the polymer film according to the present invention can promote alignment in the LC layer coating on the film. Thus, the polymer film according to the present invention can be used as an alignment layer for LC materials. By changing the thickness of the polymer film, it is possible to influence the orientation of the subsequent LC layer, in particular the tilt angle. For example, a polymer film according to the invention having a planar orientation can be used to induce planar orientation in subsequent LC layers. Polymer films according to the present invention having a tilted or beveled orientation can be used to induce tilted or beveled orientation in subsequent LC layers.

Accordingly, another preferred embodiment of the present invention relates to a multi-layer comprising a low cross-linked polymer film according to the present invention as a base layer and further comprising one or more further polymerized or cross-linked LC films. Either or both of the base polymer film and the additional LC polymer film can act as an optical layer, for example.
Furthermore, the present invention also relates to a method for producing a multilayer by the following steps:
-Applying a layer of a polymerizable LC mixture according to the invention on a substrate;
-Aligning the polymerizable LC mixture, if necessary, so that the mesogenic or LC compound acquires a uniform orientation;
-Cross-linking the LC mixture to form a polymer film;
-Applying a layer of a second polymerizable LC material on the free surface of the polymer film;
-Aligning the second LC material, if necessary, so that the mesogenic or LC compound acquires a uniform orientation; and
-Polymerizing the second LC material to form a second polymer film.
The second polymer film has, for example, a planar, inclined or oblique orientation.

The polymerizable LC mixture according to the present invention has at least one polymerizable compound having one polymerizable group (monoreactive) and at least one having two or more polymerizable groups (bireactive or multireactive). A species of polymerizable compound.
The polymerizable LC mixture may also contain one or more chiral compounds, which in addition may be polymerizable and / or mesogenic or liquid crystalline.
The polymerizable LC mixture preferably has a nematic or smectic phase or a cholesteric phase, very preferably a nematic phase.
The polymerizable mesogenic or LC compound is preferably a monomer, very preferably a calamitic monomer. These materials typically have good optical properties, such as reduced chromaticity, and can be easily and quickly aligned to the desired orientation, which means that the polymer film industry on a large scale Particularly important in industrial production.
Polymerizable mesogenic mono-, di- and polyreactive compounds suitable in the present invention are known per se and are also standard organic chemistry works such as, for example, Houben-Weyl, Methoden der organischen Chemie, Thieme-Verlag, Stuttgart. Can be prepared by methods described in the article.
The polymerizable LC mixture according to the present invention may further comprise a chiral or achiral polymerizable mesogenic or LC compound. Suitable compounds of this type are, for example, WO 93/22397, EP 0 261 712, DE 195 04 224, WO 95/22586, WO 97/00600, U.S. Patent 5,518,652, U.S. Patent 5,750,051. US Pat. No. 5,770,107 and US Pat. No. 6,514,578.
Examples of particularly useful and preferred polymerizable mesogenic or LC compounds are shown below:

In each of the above formulas, P is a polymerizable group, such as an acryl, methacryl, vinyl, vinyloxy, propenyl ether, epoxy or styrene group;
x and y are 1 to 12 identical or different integers;
A and D are 1,4-phenylene, or 1,4-cyclohexylene, mono-, di- or tri-substituted optionally by L ¹ ;
u and v are independently 0 or 1;
Z ⁰ is —COO—, —OCO—, —CH ₂ CH ₂ — or a single bond;
Y is, F, Cl, CN, NO 2, OCH 3, OCN, SCN, alkylcarbonyl having 1 to 4 C atoms which is fluorinated as needed, alkoxycarbonyl, alkylcarbonyloxy or alkoxycarbonyloxy, Or mono-, oligo- or polyfluorinated alkyls or alkoxys having 1 to 4 C atoms;
R ⁰ is 1 or more, preferably 1 to 12 C atoms, optionally fluorinated alkyl, alkoxy, alkylcarbonyl, alkoxycarbonyl, alkylcarbonyloxy or alkoxycarbonyloxy;
Ter is, for example, a terpenoid group such as menthyl;
Chol is cholesteryl;
L ¹ and L ² are, independently of each other, H, F, Cl, CN, or an optionally halogenated alkyl having 1 to 5 C atoms, alkoxy, alkylcarbonyl, alkoxycarbonyl, alkylcarbonyl Oxy or alkoxycarbonyloxy.
Suitable chiral compounds are those indicated above, and also R- or S-811, R- or S-1011, R- or S-2011, R- or S-3011, R- or S- Commercially available chiral dopants such as 4011, R- or S-5011 or CB 15 (all from Merck KGaA, Dortmund, Germany). Highly preferred are chiral compounds with a high helical twisting force (HTP), in particular compounds containing sorbitol groups as described in WO 98/00428, hydrobenzoins as described in GB 2,328,207 A compound containing a group, a chiral binaphthyl derivative as described in WO 02/94805, a chiral binaphthol acetal derivative as described in WO 02/34739, as described in WO 02/06265 Chiral TADDOL derivatives and chiral compounds having at least one fluorinated linking group and a terminal or central chiral group as described in WO 02/06196 and WO 02/06195.

Unless otherwise stated, the general production of polymer LC films according to the invention can be carried out by standard methods known from the literature. Typically, by coating or coating a polymerizable LC material onto a substrate arranged in a uniform orientation and exposing it in situ within the LC phase, for example, heat or actinic radiation, preferably Polymerization by photopolymerization, very preferably by UV-photopolymerization, fixes the alignment of LC molecules. If desired, uniform alignment can be facilitated by further means such as shearing of the LC material, surface treatment of the substrate, or addition of a surfactant to the LC material.
As the substrate, for example, glass, quartz sheet or plastic film can be used. It is also possible to place the second substrate on the coating material before and / or during and / or after polymerization. The substrate may or may not be peeled off after polymerization. When using two substrates when cured by actinic radiation, at least one substrate must be transparent to the actinic radiation used in the polymerization. Isotropic or birefringent substrates can also be used. When the substrate is not peeled from the polymerized film after polymerization, an isotropic substrate is preferably used.
Suitable and preferred plastic substrates are, for example, polyesters such as polyethylene terephthalate (PET) or polyethylene naphthalate (PEN), films of polyvinyl alcohol (PVA), polycarbonate (PC) or triacetyl cellulose (TAC), very preferably PET. Or TAC film. As the clothes refractive substrate, for example, a unidirectionally stretchable plastic film can be used. PET film is commercially available, for example, from DuPont Teijin Films under the trade name Melinex ^R.

The polymerizable material can be applied onto the substrate by conventional coating methods such as spin coating or blade coating. Examples of the polymerizable material include screen printing, offset printing, open-reel printing, relief printing, gravure printing, rotary gravure printing, flexographic printing, intaglio printing, pad printing, heat seal printing, It can also be applied by conventional printing methods known to the skilled person such as ink jet printing or printing with stamps or printing plates.
The polymerizable substance can also be dissolved in a suitable solvent. This solution is then coated or printed on the substrate, for example by spin coating or printing or other known methods, and the solvent is evaporated off prior to polymerization. In most cases, it is appropriate to heat the mixture to facilitate evaporation of the solvent. As the solvent, for example, a standard organic solvent can be used. Solvents include, for example, ketones such as acetone, methyl ethyl ketone, methyl propyl ketone or cyclohexanone; acetates such as methyl acetate, ethyl or butyl, or methyl acetoacetate; alcohols such as methanol, ethanol or isopropyl alcohol; Aromatic solvents such as toluene or xylene; halogenated hydrocarbons such as di- or trichloromethane; glycols such as PGMEA (propyl glycol monomethyl ether acetate) and □ -butyrolactone or esters thereof.

The initial alignment (e.g., planar alignment) of the polymerizable LC material may be achieved by applying a magnetic field or applied to the coated material by applying an alignment layer, for example, by rubbing the substrate, by shearing during or after coating of the material. It can be achieved by applying an electric field or by adding a surface active compound to the material. A discussion of alignment methods is given, for example, by I. Sage in "Thermotropic Liquid Crystals", edited by GW Gray, John Wiley & Sons, 1987, pages 75-77, and by T. Uchida and H. Seki "Liquid Crystals- Applications and Uses Vol. 3 ", edited by B. Bahadur, World Scientific Publishing, Singapore 1992, pages 1-63. A discussion of alignment materials and methods is given by J. Cognard in Mol. Cryst. Liq. Cryst. 78, Supplement 1 (1981), pages 1-77.
Particularly preferred are polymerizable materials that contain one or more surfactants that promote specific surface alignment of LC molecules. Suitable surfactants are described, for example, in J. Cognard, Mol. Cryst. Liq. Cryst. 78, Supplement 1, 1-77 (1981). Preferred alignment agents for planar alignment are, for example, non-ionic surfactants, preferably commercially available Fluorad FC-171 ^R (from 3M) or Zonyl FSN ^R (from DuPont). A fluorocarbon surfactant, a surfactant described in GB 2 383 040, or a polymerizable surfactant as described in EP 1 256 617.
It is also possible to apply an alignment layer on the substrate and apply a polymerizable substance on the alignment layer. Suitable alignment layers are, for example, rubbed polyimides or alignment layers made by photoalignment methods such as those described in U.S. Patent No. 5,602,661, U.S. Patent No. 5,389,698 or U.S. Patent No. 6,717,644. Known in the art.

Polymerization is performed, for example, by exposing the polymerizable material to heat or actinic radiation. Actinic radiation means irradiation with light such as UV light, IR light or visible light; irradiation with X-rays or gamma rays; or irradiation with high energy particles such as ions or electrons. Preferably the polymerization is carried out by UV irradiation. As a source for actinic radiation, for example, a single UV lamp or a group of UV lamps can be used. When using high lamp power, the curing time can be shortened. Another possible source of actinic radiation is a laser, for example a UV, IR or visible light laser.
The polymerization is preferably carried out in the presence of an initiator that is absorptive at the wavelength of the actinic radiation. For example, when polymerizing by UV light, a photoinitiator can be used that generates free radicals or ions that decompose under UV irradiation to initiate the polymerization reaction. In polymerizing acrylate or methacrylate groups, preferably a radical photoinitiator is used. In polymerizing vinyl, epoxide or oxetane groups, a cationic photoinitiator is preferably used. It is also possible to use a thermal polymerization initiator that generates free radicals or ions that decompose when heated to initiate polymerization. Typical radical photoinitiators are eg Irgacure 907, Irgacure 651, Irgacure 184, Darocure 1173 or Darocure 4205 (Ciba Geigy); typical cationic photoinitiators are eg UVI 6974 (Union Carbide) It is.
Curing time depends inter alia on the reactivity of the polymerizable material, the thickness of the coating layer, the type of polymerization initiator and the output of the UV lamp. The curing time is preferably ≦ 5 minutes, very preferably ≦ 3 minutes, most preferably ≦ 1 minute. In mass production, a short cure time of ≦ 30 seconds is preferred.
The polymerizable material may also be one or more dyes having an absorption maximum adjusted for the wavelength of radiation used in the polymerization, such as, for example, 4,4 "-azoxyanisole or Tinuvin ^R dye (Ciba UV dyes such as Bezel, Switzerland).

In another preferred embodiment, the polymerizable material comprises one or more monoreactive polymerizable non-mesogenic compounds in an amount of preferably 0-50%, very preferably 0-20%. Typical examples are alkyl acrylates or alkyl methacrylates.
It is also possible to modify the physical properties of the polymer film by adding one or more chain transfer agents to the polymerizable material. Particularly preferred are thiol compounds, for example monofunctional thiols such as dodecanethiol or multifunctional thiols such as trimethylpropanetri (3-mercaptopropionate). Highly preferred are, for example, mesogenic or LC thiols as disclosed in WO 96/12209, WO 96/25470 or US Pat. No. 6,420,001. By using a chain transfer agent, the length of the free polymer chain in the polymer film and / or the length of the polymer chain between two crosslinks can be controlled. Increasing the amount of chain transfer agent decreases the polymer chain length in the polymer film.
Furthermore, the polymerizable substance is, for example, a catalyst, a sensitizer, a stabilizer, an inhibitor, a chain transfer agent, a co-reactive monomer, a surfactant compound, a lubricant, a wetting agent, a dispersant, a hydrophobizing agent, an adhesive, One or more additional ingredients such as flow improvers, antifoams, deaerators, diluents, reactive diluents, adjuvants, colorants, dyes or pigments may also be included.

The polymer film of the present invention can be used in conventional LC displays, such as DAP (deformation of alignment phase), ECB (electrically controlled birefringence), CSH (color super homeotropic), VA (vertical alignment), VAN or VAC. Displays with vertical alignment such as (vertical alignment nematic or cholesteric), MVA (multi-region vertical alignment) or PVA (patterned vertical alignment) mode; OCB (optical compensation curve cell or optical compensation birefringence), Display with curvature or hybrid alignment such as R-OCB (reflective OCB), HAN (hybrid alignment nematic) or pi-cell (π-cell) mode; TN (twisted nematic), HTN (high twist nematic), Display with twist alignment such as STN (super twisted nematic), AMD-TN (active matrix propulsion TN) mode; IPS (in-plane switching) ) Mode of the display; or alignment layer in a display having a switch in the intra-phase isotropic such optically of displays described in EP WO 02/93244, it may be used as retardation or compensation film.
Above and below, all temperatures are given in degrees Celsius, and all percentages are by weight unless otherwise noted. The following abbreviations are used to describe the LC phase behavior: C, K = crystalline; N = nematic; S = smectic; N *, Ch = chiral nematic or cholesteric; I = isotropic. The numbers in these symbols indicate the phase transition temperature in degrees Celsius. Furthermore, mp indicates the melting point and cp indicates the clearing point (in ° C).

(Example)
Hereinafter, the present invention will be specifically described by way of examples, but the present invention is not limited thereto.
Example 1
The polymerizable LC mixture is prepared from various concentrations of compounds (1) to (8) as shown in Table 1 below.
(1) = Crosslinkable (bireactive) mesogenic compound
(2), (4) = monoreactive mesogenic compounds
(3), (5) = monoreactive mesogenic compound of formula (I)
(6) = Irgacure 907 ^R (Photoinitiator from Ciba)
(7) = Irganox 1076 ^R (stabilizer from Ciba)
(8) = Fluorad FC171 ^R (surfactant from 3M)

LC polymer films with planar alignment are produced from these mixtures by dissolving each mixture in 30% or 50% concentration of xylene or toluene. Each solution is bar coated onto the substrate using a wire wound rod to deposit a wet film thickness of about 4 μm (bar # 0 from RK Coating, UK). Immediately after coating, each sample is annealed at 60 ° C. for 30 seconds and polymerized in an air environment at an output of 20 mW / cm ² for 60 seconds using a medium pressure mercury lamp. The substrate is triacetyl cellulose (TAC) from LoFo Germany. Prior to coating, the TAC film is rubbed with a velvet cloth to provide a planar alignment for the polymerizable LC mixture.
The pencil hardness of the polymer film surface is measured according to ASTM D3363-00. The degree of cure (EoC) is defined as the percent of reacted acrylate groups and is measured by FTIR taking the ratio of the lower region of the acrylate peak (at 810 cm ⁻¹ ) before and after polymerization. The adhesion of the polymer film to the TAC substrate is determined by the cross-hatch method (25 squares) using Scotch 610 tape (3M company) ("Tape 1") and Sekisui no. 252 tape ("Tape 2"). Measured using and averaged over at least 3 trials. The cross-hatch method involves forming 25 square grids and then scoring the film (ie, cutting into a substrate) with a device that applies adhesive tape to these grids and presses them before peeling them off. The number of squares remaining for each grid is then counted and the overall percentage for a given film is typically calculated. This method is described in more detail in British Standard IS 2409: 1992 (E).
Table 1 below shows the composition and clearing point of each polymerizable LC mixture, and the EoC, pencil hardness, and adhesion of polymer films P1 to P12 produced from these mixtures.

Table 1 (in 50% solution)

Table 1 (continued)

Mixtures 1-5 contain a low amount of crosslinkable compound and a monoreactive compound of formula I. The resulting polymer films P1 to P5 have good adhesion to TAC, but still have a sticky surface after polymerization. Such a film has a propensity to stick to itself when wound onto a roll, for example in the production process when manufacturing optical films or multilayer parts, thus causing deterioration of the film.
Mixture 6 contains a higher amount of monoreactive compound of formula I and greater than 12% crosslinkable compound. The obtained polymer film P6 has a hard surface, but has low adhesion to TAC.
Mixtures 7-12 according to the invention contain up to 12% of crosslinkable compounds and high amounts of monoreactive compounds of formula I. The resulting polymer films P7 to P12 have good or sufficient adhesion to TAC, and at the same time have a hard surface with low tack, and are further processed against mechanical stress, for example Alternatively, it is more stable when used to produce optical multilayers.

Claims (8)

a)> 0-12% of one or more crosslinkable compounds,
b) 50-80% of one or more of the following compounds of formula I:

(Wherein P is a polymerizable group;
Sp is a spacer group or a single bond;
A is an aromatic or aliphatic 5- or 6-membered ring, or a group containing 2 or 3 fused aromatic or aliphatic 5- or 6-membered rings; these rings are optionally Contains one or more heteroatoms selected from N, O and S, optionally further substituted by ^one or more identical or different groups L ¹ ;
Z is independently from each other when there are a plurality of Z, -O-, -S-, -CO-, -COO-, -OCO-, -S-CO-, -CO-S-, -O-CO- O-, -CO-NR ^0- , -NR ⁰ -CO-, -OCH _2- , -CH ₂ O-, -SCH _2- , -CH ₂ S-, -CF ₂ O-, -OCF _2- , -CF ₂ S-, -SCF _2- , -CH ₂ CH _2- , -CF ₂ CH _2- , -CH ₂ CF _2- , -CF ₂ CF _2- , -CH = CR ^0- , -CH = CH -, -CH = CF-, -CY ¹ = CY ^1- , -C≡C-, -CH = CH-COO-, -OCO-CH = CH- or a single bond;
Z ¹ is one of the meanings of Z;
R ⁰ is H or alkyl having 1 to 12 C atoms;
Y ¹ is H, F, Cl or CN;
m is 0 or 1;
L ¹ and L ² are independently of each other, F, Cl, Br, I, CN, NO ₂ , P-Sp-, or 1 to 12 C atoms, and one or more H atoms are required Alkyl, alkoxy, alkylcarbonyl, alkoxycarbonyl, alkylcarbonyloxy or alkoxycarbonyloxy, optionally substituted by F or Cl;
r1 and r2 are independently of each other 0, 1, 2, 3 or 4), or 50-80% of one or more compounds of formula Ia:

(Wherein P, Sp, L ¹ , L ² , r ¹ and r ² have the meanings given in formula I), and
5-50% of one or more compounds of formula III:

Wherein P and Sp are as defined in Formula I; R has 1 to 12 C atoms, and one or more H atoms are optionally replaced by F or Cl. Alkyl, alkoxy, alkylcarbonyl, alkoxycarbonyl, alkylcarbonyloxy or alkoxycarbonyloxy)
Containing mixture. The mixture of claim 1, wherein the mixture further comprises:
d) one or more photoinitiators;
e) one or more surfactants as optional ingredients;
f) One or more stabilizers as optional ingredients.   A polymer film obtainable by crosslinking the mixture according to claim 1.   Use of a mixture or film according to at least one of claims 1 to 3 in optical, electro-optical, information storage, decoration and security applications.   An optical component or device comprising a mixture or film according to at least one of claims 1-3.   A liquid crystal display comprising the mixture or film according to claim 1.   An appraisal, verification or security mark or color image comprising a mixture or film according to at least one of claims 1-3.   A valuable object or document comprising the appraisal, verification or security mark or image of claim 7.