Liquid crystal display device and method for producing same

1. A liquid crystal display device, comprising:

a pair of substrates;

a liquid crystal layer containing liquid crystal molecules and interposed between the pair of substrates; and

an alignment control layer for perpendicularly aligning the liquid crystal molecules, wherein:

the liquid crystal display device includes substantially no alignment film;

the alignment control layer includes a monofunctional monomer, a polyfunctional monomer, and a polymerization initiator that are polymerized while a liquid crystal composition containing the liquid crystal molecules, the monofunctional monomer, the polyfunctional monomer, and the polymerization initiator, is interposed between the pair of substrates;

the polymerization initiator generates radicals by a self-cleavage reaction caused by photoirradiation and includes at least two radical polymerizable groups;

the polyfunctional monomer generates a radical by annealing and irradiation with light at not less than 340 nm;

the monofunctional monomer is represented by Formula (1):

X represents acrylate, methacrylate, ethacrylate, vinyl, or allyl, m represents an integer of 0 to 12, a and b each independently represent 0 or 1, R represents C1-C20 alkyl, and hydrogen atoms in a ring structure may each independently be substituted with halogen atom, methyl, ethyl, or propyl;

the ratio of the molar concentration of the polyfunctional monomer in the liquid crystal composition to the molar concentration of the monofunctional monomer in the liquid crystal composition is not less than 1.5% and not more than 15%;

the ratio of the molar concentration of the polyfunctional monomer to the molar concentration of the monofunctional monomer is calculated as (mol % of the polyfunctional monomer in the liquid crystal composition)×100/(mol % of the monofunctional monomer in the liquid crystal composition);

the total concentration of the polyfunctional monomer and the polymerization initiator relative to the monofunctional monomer is not more than 18 mol %;

the polyfunctional monomer is represented by Formula (2):

P 1 -A 1 -P 1   (2);

P 1 s each independently represent acrylate, methacrylate, ethacrylate, vinyl, or allyl, A 1 represents phenanthrylene, and hydrogen atoms in A 1 may each independently be substituted with halogen atom, methyl, ethyl, or propyl; and

the polymerization initiator is represented by Formula (5):

wherein

R 1 represents C1-C4 linear or branched alkyl or alkenyl, or Sp 3 -P 3 ;

R 2 represents C1-C4 linear or branched alkyl or alkenyl, or Sp 4 -P 4 ;

P 1 , P 2 , P 3 , and P 4 represent radical polymerizable groups, a total number of P 1 , P 2 , P 3 , and P 4 is at least two;

Sp 1 and Sp 2 each represent C1-C6 linear, branched, or cyclic alkylene, alkyleneoxy, or carbonyloxy, or a direct bond;

Sp 3 and Sp 4 each represent C1-C6 linear, branched, or cyclic alkylene, alkyleneoxy, or carbonyloxy;

L 1 and L 2 each represent —F, —OH, or C1-C12 linear or branched alkyl, alkenyl, or aralkyl;

m 1 represents an integer of 1 to 3;

m 2 represents an integer of 0 to 3;

n 1 and n 2 each represent an integer of 0 to 4; and

a total of m 1 and n 1 is an integer of 1 to 5, a total of m 2 and n 2 is an integer of 0 to 5, and a total of m 1 and m 2 is an integer of 1 to 6.

2. The liquid crystal display device according to claim 1 , wherein the liquid crystal molecules have negative dielectric anisotropy.

3. The liquid crystal display device according to claim 1 , wherein the polyfunctional monomer in the liquid crystal composition has a higher mol concentration than the compound.

4. The liquid crystal display device according to claim 1 , wherein the concentration of the polyfunctional monomer is 0.05 to 0.25% by weight of the liquid crystal composition.

5. The liquid crystal display device according to claim 1 , wherein the concentration of the polymerization initiator is 0.005 to 0.3% by weight of the liquid crystal composition.

6. The liquid crystal display device according to claim 1 , wherein the polymerization initiator is represented by Formula (6):

wherein

R 3 and R 4 each represent C1-C4 linear or branched alkyl or alkenyl;

P 1 and P 2 each represent radical polymerizable groups;

Sp 1 and Sp 2 each represent C1-C6 linear, branched or cyclic alkylene, alkyleneoxy, or carbonyloxy, or a direct bond.

7. The liquid crystal display device according to claim 1 , wherein the polymerization initiator is represented by Formula (7):

wherein

R 5 and R 6 each represent a hydrogen atom or methyl.

8. The liquid crystal display device according to claim 1 , wherein, in Formula (1), m represents an integer of 1 to 8.

9. The liquid crystal display device according to claim 1 , wherein, in Formula (1), m is zero.