CN103135157B - Method for preparing composite phase difference board - Google Patents

Abstract

A method for preparing a composite phase difference plate, comprising: providing a first support plate, forming a photo-alignment film on the surface thereof, and coating a first liquid crystal coating on the first surface of the photo-alignment film material, making it solidify to form the first retardation plate. The first surface of the first phase difference plate is pasted on a second support plate, and then the photo-alignment film is peeled off from the first support plate, so that the second surface of the photo-alignment film is exposed. Finally, a second liquid crystal coating material is coated on the second surface of the photo-alignment film, and cured to form a second retardation plate. In this way, only a single photo-alignment film can be used to produce two phase difference plates, so the amount of alignment film used can be effectively reduced, so the process cost is relatively low, and a thinner composite phase difference film can be produced. plate.

Description

A kind of method for preparing composite phase difference plate

technical field

The invention relates to a method for preparing a phase difference plate by an optical alignment method, in particular to a method for preparing a composite phase difference plate by an optical alignment method.

Background technique

It is known that liquid crystal molecules have different refractive indices in different axial directions. This is the birefringence of liquid crystal molecules, so that when light is irradiated through liquid crystal molecules, the polarization direction of light is changed and optical retardation occurs ( Optical retardation) produces a phase difference, which is the optical anisotropy of liquid crystal molecules. Because the optical anisotropy of the liquid crystal will change the direction of light polarization, it can be used to control the light transmittance to achieve the light and dark effect on the display, and then applied to the display; on the other hand, the optical anisotropy caused by the optical anisotropy The retardation phenomenon makes the liquid crystal molecular film layer applicable as a retardation plate (optical retarder). In application, the phase difference plate can be matched with the liquid crystal display according to the required phase difference value, so as to reduce the light leakage of the liquid crystal display and improve the display contrast, so as to achieve the effect of wide viewing angle.

Whether it is applied to a display or a retardation plate, the liquid crystal molecules must be aligned to be effectively utilized. The alignment of liquid crystals is first through a microgroove structure with a specific direction formed on the surface of the alignment film, so that the liquid crystal molecules arranged on the alignment film follow the specific direction of the microgroove structure (ie is the alignment direction) to carry out alignment alignment, and then obtain the effect of alignment.

The manufacturing method of this kind of alignment film, the known technology mostly adopts the contact brushing method (rubbing) to brush and grind the micro-groove structure on the surface of the alignment film, but the rubbing method is not suitable for large-area alignment , it cannot achieve sufficient yield under the requirement of large-scale display; and problems such as fine particles, fiber pollution or static electricity are easy to be generated on the surface of the alignment film during the brushing process (see US6649231, which in turn affects the alignment of liquid crystal molecules on it Alignment effect. On the other hand, it is not easy to achieve multi-region alignment on an alignment film by brushing. It needs to go through multiple brushing processes, and the product yield is not high, and the surface of the alignment film is easy to appear Due to problems such as defects and particle contamination, this method cannot be used to meet the needs of displays with multi-region alignment to achieve wide viewing angle performance.

In order to overcome the shortcomings of the aforementioned brushing process, a non-contact alignment method emerged as the times require. In U.S. Patent No. 5,389,698, a photo-alignment method is mentioned, which uses linearly polarized ultraviolet light to irradiate photo-crosslinked photo-alignment resins, so that such resin molecules are affected by linearly polarized ultraviolet light. A photo-alignment film can be formed after the homeotropic alignment is carried out along the required predetermined direction, and then fixed by a cross-linking reaction. This kind of photo-alignment film aligns liquid crystals by irradiating linear polarized ultraviolet light, so that the Van der Waals force of the resin molecules on the surface of the photo-alignment film can be distributed along the preset direction, and then drive the liquid crystal molecules to follow the preset direction. (that is, the alignment direction) to carry out the alignment (M.Schadt, JJAP, 1992, and finally obtain the effect of alignment. The aforementioned Van der Waals force distributed along the preset direction is caused by the molecules on the surface of the photoalignment film. The specific direction distribution of functional groups or side chain structures makes the electron cloud or dipole distribution on the surface of the photoalignment film directional.

The advantage of the photo-alignment method is that the liquid crystal molecules can be induced to align in a specific direction without rubbing or touching the surface of the alignment film, which solves the problems of particles and static electricity generated by the traditional brushing method. On the other hand, the photo-alignment method can be applied to flexible or curved substrate surfaces, which can overcome the limitation of using hard and flat substrates in the known contact method, so it can be applied to the continuous process of roll to roll. Production. In addition, the photo-alignment method can also be applied to form an alignment layer on the aligned liquid crystal film layer, and perform alignment in different directions without damaging the film surface of the aligned liquid crystal film layer in the lower layer, so as to form a plurality of Composite retardation plates of alignment films and liquid crystal film layers with different alignment directions, and the alignment direction of the photo-alignment method can be set arbitrarily, which is difficult to achieve with the known brushing method.

In order to meet the requirements of different types of liquid crystal displays for the retardation value, it is known that multiple alignment films with different alignment directions and liquid crystal film layers can be stacked to form different types of composite retardation plates by using the aforementioned optical alignment method to reduce the liquid crystal. Display light leakage defects. For example, vertical alignment (vertical alignment) liquid crystal displays require a composite phase difference plate with a positive type A plate and a negative type C plate to compensate for the required phase difference, so that the liquid crystal display can achieve better performance. The effect of contrast and wide viewing angle; or the cholesteric liquid crystal used in the brightness enhancement film (brightenhancement film) requires a composite phase difference plate with a positive type A plate and a positive type C plate to improve its contrast and improve color shift. question.

Such applications all use two-layer retardation plates, but the known production method must use at least two layers of alignment films, so that the liquid crystal film layers used as retardation plates have the same or different alignment directions. US Pat. No. 6,717,644 mentions a composite retardation plate comprising two layers with different functions (different alignment directions or different retardation values), which uses two alignment films to align two layers of liquid crystal molecules respectively. However, it is known that the material cost of the alignment film is quite expensive, and the use of the two-layer alignment film will greatly increase the cost of the composite phase difference film, and will also increase the thickness of the retardation film, which is not conducive to the demand for thinner displays.

Therefore, it is necessary to develop a method for manufacturing a composite phase difference plate with a lower cost.

Contents of the invention

The main purpose of the present invention is to provide a method for preparing a composite phase difference plate.

According to the method for preparing a composite phase difference plate disclosed in the present invention, it includes the following steps: (a) providing a first support plate; (b) coating a photo-alignment resin on the upper surface of the first support plate, and A first linear polarized ultraviolet light irradiates the photo-alignment resin to make it undergo a photo-alignment reaction (photo-alignment) to form a photo-alignment film; (c) coating a first surface on the first surface of the photo-alignment film liquid crystal coating material, and irradiate the first liquid crystal coating material with a first nonlinear polarized ultraviolet light to cure it to form a first phase difference plate; (d) the first phase difference plate of the first phase difference plate The surface is pasted on a second support plate, and then the photo-alignment film is peeled off from the first support plate, so that the second surface of the photo-alignment film is exposed; and (e) on the second surface of the photo-alignment film A second liquid crystal coating material is coated on the surface, and the second liquid crystal coating material is irradiated with a second non-linear polarized extreme ultraviolet light to make it solidify so as to form a second retardation plate.

According to the preparation method pointed out in the present invention, only a single photo-alignment film can be used to produce two phase difference plates, so the amount of alignment film can be effectively reduced, so it has a relatively low process cost, and can produce thin Composite retardation plate.

In addition, the preparation method of the present invention can simultaneously solve the problem of particles and static electricity on the surface of the alignment film produced by the known brushing method for preparing the composite phase difference plate due to the application of the photo-alignment method.

According to another object of the present invention, it is to provide a composite phase difference plate prepared by the aforementioned method, because it can use one less layer of alignment film than the known composite phase difference plate, so its thickness can be further reduced, To achieve the effect of thinning.

Description of drawings

Fig. 1 is a schematic diagram of photo-alignment resin molecules undergoing a photo-alignment reaction.

FIG. 2 is a schematic diagram of forming a photo-alignment film.

FIG. 3 is a schematic diagram of forming a first phase difference plate.

FIG. 4 is a schematic diagram of sticking the first phase difference plate on the second support plate and peeling off the photo-alignment film from the first support plate.

FIG. 5 is a schematic diagram of forming a second retardation plate.

FIG. 6 is a schematic diagram illustrating a second linearly polarized ultraviolet light irradiating on the second surface of the photo-alignment film with a polarization direction different from that of the first linearly polarized ultraviolet light.

[Description of main component symbols]

13: Photoalignment resin molecules

16: First linearly polarized extreme ultraviolet light

161: preset polar direction

22: The first support plate

221: upper surface

23: Photoalignment resin

24: Photoalignment film

241: First Surface

242: Second Surface

33: The first liquid crystal coating material

34: The first phase difference plate

341: First Surface

36: First nonlinear polarized extreme ultraviolet light

42: Second support plate

50: Composite retardation plate

53: Second liquid crystal coating material

54: The second phase difference plate

56: Second nonlinear polarized extreme ultraviolet light

66: second linearly polarized extreme ultraviolet light

661: Preset Pole Direction

Detailed ways

In order to achieve the above purpose, the present invention proposes a method for preparing a composite phase difference plate, which can effectively solve the problem of high cost of the aforementioned known technology.

In order to facilitate those skilled in the field of the present invention to understand the technology disclosed in the present invention, the method for preparing the composite phase difference plate of the present invention is illustrated with reference to FIG. 1 to FIG. 6 below.

Referring to Fig. 2, the method disclosed according to the present invention comprises the following steps:

Firstly, a first support plate 22 is provided.

Next, a photo-alignment resin 23 is coated on the upper surface 221 of the first support plate 22, and the photo-alignment resin 23 is irradiated with a first linearly polarized ultraviolet light 16 to cause a photo-alignment reaction to form a photo-alignment resin. Alignment film 24.

It is known that photoalignment resins will undergo photochemical reactions after being irradiated with light. According to the photochemical reactions of different mechanisms, they can be roughly divided into three types: photoisomerization type, photocrosslinking type, and photocleavage type. . The photo-alignment resin applicable in the present invention is not particularly limited, and is preferably a photo-crosslinking photo-alignment resin.

Referring to FIG. 1 , taking the photo-crosslinked photo-alignment resin as an example, after it is irradiated with polarized ultraviolet light, the molecules 13 of this type of photo-alignment resin will undergo a cross-linking reaction. During the cross-linking process, the overall photo-alignment resin molecules 13 will be affected by the first linearly polarized extreme ultraviolet light 16, and will be aligned along the required preset polarization direction 161, and will be fixed through the cross-linking reaction , this process is the photoalignment reaction.

The photo-alignment resin 23 refers to a resin having functional groups that can undergo photochemical reactions. The functional groups that can be applied to the photo-alignment resin 23 in the present invention include, but are not limited to, selected from cinnamate, A group consisting of coumarin, phenyl styrene ketone (Chalcone), maleimide, quinolinone and bis (benzylidene) , at least one of the functional groups.

It is known that linearly polarized ultraviolet light refers to planar light with a single linear polarization direction, and the polarized light in other directions is screened out by general nonlinear polarized ultraviolet light (non-polarized ultraviolet), leaving only the required It is obtained from polarized light in a single linear direction, and generally, polarized film or grating can be used to screen out linearly polarized extreme ultraviolet light. The nonlinear polarized extreme ultraviolet light is the light emitted by a general light source, also known as circularly polarized polarized light, which is distributed in all directions with equal intensity and illuminates in all directions.

The aforementioned first linearly polarized ultraviolet light 16 irradiates the dose of the photo-alignment resin. Those skilled in the art can select a suitable irradiation dose according to requirements, such as: the type of equipment used, the type of photo-alignment resin, and the like. It is known that the photo-crosslinked photo-alignment resin can undergo photo-alignment reaction only by irradiation with linearly polarized ultraviolet light with an irradiation dose not less than 5mJ/ ^cm2 . Therefore, in order to make the photo-alignment resin used in the present invention can be The photoalignment reaction is carried out smoothly, and the irradiation dose is preferably not less than 5mJ/cm ² .

The method of coating the photo-alignment resin 23 on the upper surface 221 of the first support plate 22 is not particularly limited, and the implementer can choose it in consideration of the convenience of implementation, including but not limited to, spin coating (spin coating), wire bar Coating methods such as bar coating, dip coating, slot coating, or roll to roll coating.

The coating thickness of the photo-alignment resin 23 that can be applied in the present invention is not particularly limited, and it does not affect the function of aligning the liquid crystal molecules. For convenience in operation and cost considerations, the thickness is 10 nm to 1 μm More preferably, 10nm to 50hm is more preferred.

In addition, after the photo-alignment resin 23 is coated on the upper surface 221 of the first support plate 22, the photo-alignment resin can be further dried to remove the auxiliary coating solvent contained in the photo-alignment resin, and keep the coating The surface of the layer is dried to facilitate subsequent processing or storage. For example, drying on a heating plate, drying in an oven or vacuum drying, etc., any other applicable methods known to those skilled in the art can be selected because of their convenience in implementation, and there is no special limitation in the present invention. .

Referring to FIG. 3, a first liquid crystal coating material 33 is coated on the first surface 241 of the photoalignment film 24, and the first liquid crystal coating material 33 is irradiated with a first nonlinear polarized ultraviolet light 36, so that It solidifies to form a first phase difference plate 34 .

According to the first liquid crystal coating material 33 described in the present invention, when it is coated on the first surface 241 of the photo-alignment film 24, it will be subjected to the van der Waals force of the molecules on the surface of the photo-alignment film, thereby driving the photo-alignment film to The liquid crystal molecules in the first liquid crystal coating material 33 on the surface 24 are aligned in a homeotropic manner according to the predetermined direction (ie, the alignment direction), so that the liquid crystal molecules are aligned.

The aforementioned first liquid crystal coating material 33 has acrylic functional groups that can undergo photochemical reactions, so after being irradiated by the first nonlinear polarized ultraviolet light 36, the unsaturated double bonds in the acrylic functional groups will cross each other. Combined and solidified to form a liquid crystal molecular film layer. In addition, since the liquid crystal molecules have different refractive indices in different axial directions (called birefringence), when light passes through the liquid crystal molecules, the polarization direction of the light is changed and optical retardation occurs, resulting in phase difference. It is known that the aligned liquid crystal molecular film layer has a uniform birefringence because the liquid crystal molecules are aligned in a specific direction, so it can be used as an optical retarder. The phase difference required by the phase difference plate can be calculated by the following equation (a):

Ro＝Δn·d (a)

Among them, Ro is the retardation value; Δn is the refractive index difference in different axial directions, that is, the complex refractive index; d is the thickness of the liquid crystal molecular film. Δn is a physical property of the liquid crystal material itself, and different liquid crystal materials have different Δn values; the thickness of the liquid crystal molecular film layer can be adjusted through coating methods and parameters to achieve different phase difference values.

The coating method of the first liquid crystal coating material 33 that can be applied in the present invention is not particularly limited, and the implementer can choose it in consideration of the convenience of implementation, including but not limited to, spin coating (spin coating), wire bar coating Cloth (bar coating), dip coating (dip coating), slot coating (slot coating), or roll to roll coating (roll to roll coating) and other coating methods. In addition, the coating thickness of the liquid crystal molecular film layer can be further regulated by means of the passing speed, the specification of the wire rod used, or the winding speed.

The first liquid crystal coating material 33 applicable in the present invention includes, but is not limited to, a photo-crosslinkable liquid crystal material with acrylic functional groups.

In addition, after coating the first liquid crystal coating material 33 on the first surface 241 of the photo-alignment film 24, the first liquid crystal coating material 33 may be further dried, and the auxiliary coating contained in the first liquid crystal coating material may be further dried. The solvent used for the cloth is removed, and the surface of the coating layer is kept dry to facilitate subsequent processing or storage. For example, drying by heating plate, oven drying or vacuum drying, etc., any other applicable method known to those skilled in the art can be selected for its convenience in implementation.

For the aforementioned irradiation energy of the first nonlinear polarized extreme ultraviolet light 36 , the implementer can select an appropriate irradiation dose according to the type of liquid crystal coating material used and the type of equipment used. Since the liquid crystal coating material used in the present invention comprises a photocrosslinkable liquid crystal material, in order to make it curable to form a liquid crystal molecular film layer, the energy that can be applied to the first nonlinear polarized ultraviolet light irradiation in the present invention is 20-1000mJ/cm ² is preferred, and 170-500mJ/cm ² is more preferred.

Wherein, the irradiation energy of the first nonlinear polarized extreme ultraviolet light 36 is only used to cure the liquid crystal coating material in a state of homeotropic alignment in a predetermined direction. However, the radiation dose used by the known technology is about 1500-5000mJ/cm ² , which is far greater than the applicable range of the present invention. These energy will penetrate the liquid crystal molecular film layer and affect the electron cloud or dipole distribution on the surface of the photoalignment film. Cause damage, so that the molecules on the surface of the photo-alignment film lose alignment, so the liquid crystal molecules cannot be further driven to align. However, even if the photoalignment film loses the function of driving liquid crystal molecules to align, it does not affect the alignment result of the cured and formed liquid crystal molecular film layer. The performance of the retardation film without affecting its optical properties, and the main reason why the two-sided alignment of the known photo-alignment film cannot be utilized.

Referring to FIG. 4 , the first surface 341 of the first phase difference plate 34 is pasted on a second support plate 42 .

There is no particular limitation on the method of pasting the first surface 341 of the first phase difference plate 34 on the second support plate 42 . For example, by applying an adhesive such as pressure-sensitive glue or UV glue between the first phase difference plate 34 and the second support plate 42, or doing an adhesive surface treatment on the second support plate 42, etc., Those skilled in the art can also choose other methods for bonding the two, and the scope of application of the present invention is not limited thereto.

Next, the photo-alignment film 24 is peeled off from the first support plate 22 to expose the second surface 242 of the photo-alignment film 24 .

In order to make the peeling process easier to implement, the upper surface 221 of the first support plate 22 can be pre-selectively given a surface treatment to enhance the release effect. The surface treatment method for improving the release effect is not particularly limited. Examples that can be cited here include, but are not limited to, sticking a release film or coating a resin layer with a release effect, etc., which are well known to those skilled in the art. Any other applicable methods can be used, and the scope of application of the present invention is not limited thereto.

The materials applicable to the first support plate 22 and the second support plate 42 in the present invention can be respectively, including but not limited to, glass, triacetyl cellulose resin (Triacetyl Cellulose), polyester-based resin (polyester-based resin) ), acetate-based resin, polyethersulfone-based resin, polycarbonate-based resin, polyamide-based resin, polyimide Amine-based resin, polyolefin-based resin, acrylic-based resin, polyvinyl chloride-based resin, polystyrene-based resin (polystyrene-based resin), polyvinyl alcohol-based resin, polyarylate-based resin, polyphenylene sulfide-based resin, polyvinyl dichloride Department of resin (polyvinylidenechloride-based resin) or methacrylate resin ((methyl) acrylic-based resin). The materials of the first support plate and the second support plate can be selected according to the use requirements, and the two can be the same or different.

For the convenience of operation, and the consideration of saving material and process costs, etc., the composite phase difference plate disclosed in the present invention can be directly applied to the optical film layer combination to be applied when it is manufactured. Therefore, the types of the second support plate 42 that can be applied in the present invention include but are not limited to, release film, polarizer, protective film, diffusion film, diffusion plate, light guide plate, brightness enhancement film, flexible panel or touch panel.

Referring to FIG. 5, a second liquid crystal coating material 53 is coated on the second surface 242 of the photoalignment film 24, and then a second nonlinear polarized ultraviolet light 56 is used to irradiate the second liquid crystal coating material 53, because It has acrylic functional groups that can undergo photochemical reactions. After being irradiated by the second nonlinear polarized ultraviolet light 56, the unsaturated double bonds in the acrylic functional groups will be cross-linked and solidified to form a liquid crystal molecular film layer, which can It is applied as a phase difference plate, that is, the second phase difference plate 54 .

According to the second liquid crystal coating material 53 described in the present invention, when it is coated on the second surface 242 of the photo-alignment film 24, it will be aligned by the molecules on the surface of the photo-alignment film to have a homeotropic arrangement in a predetermined direction. .

The second liquid crystal coating material 53 applicable in the present invention includes, but is not limited to, a photo-crosslinkable liquid crystal material with acrylic functional groups.

For the irradiation energy of the aforementioned second nonlinear polarized ultraviolet light 56, the implementer can select an appropriate irradiation dose according to the type of liquid crystal coating material used and the type of equipment used, as long as the liquid crystal coating material can be cured Both can be applied in the present invention without any special limitation. In addition, since the liquid crystal coating material 53 used in the present invention includes a photocrosslinkable liquid crystal material, in order to make it curable to form a liquid crystal molecular film layer, it can be applied to the second nonlinear polarized ultraviolet light irradiation in the present invention. Energy, preferably not less than 20mJ/cm ² .

In addition, since the photo-alignment film 24 no longer needs to be further utilized, even if the photo-alignment film is irradiated with too high energy of the second nonlinear polarized extreme ultraviolet light 56, thus losing the function of inducing the alignment of liquid crystal molecules, it still cannot It affects the alignment result of the cured and formed liquid crystal molecular film layer.

The method of coating the second liquid crystal coating material 53 that can be applied in the present invention is not particularly limited, and the implementer can choose it in consideration of the convenience of implementation, including but not limited to, spin coating (spin coating), wire bar Coating methods such as bar coating, dip coating, slot coating, or roll to roll coating. Moreover, the implementer can further adjust the coating thickness of the liquid crystal molecular film layer through the passing speed, the specification of the used wire bar or the winding speed according to the requirement.

In addition, after the second liquid crystal coating material 53 is coated on the second surface 242 of the photo-alignment film 24, the second liquid crystal coating material 53 can be further dried, and the auxiliary material contained in the second liquid crystal coating material 53 can be further dried. The solvent used for coating is removed, and the surface of the coating layer is kept dry to facilitate subsequent processing or storage. For example, drying by heating plate, oven drying or vacuum drying, etc., any other applicable method known to those skilled in the art can be selected for its convenience in implementation.

Referring to FIG. 6 , according to another specific implementation aspect of the method for preparing a composite phase difference plate of the present invention, before coating the second liquid crystal coating material 53 on the second surface 242 of the photoalignment film 24, another liquid crystal coating material 53 may be further included. The step of irradiating the second surface 242 with the second linearly polarized ultraviolet light 66 , which is different from the aforementioned first linearly polarized extreme ultraviolet light 16 , in the preset polarization direction 661 , so that the molecules of the photo-alignment film on the second surface 242 can move along different predetermined directions. Set the direction to arrange in a forward direction. In this way, when the second liquid crystal coating material 53 is coated on the second surface 242, it can have a direction different from that of the first liquid crystal coating material 33, thereby forming a first phase difference The plate 34 and the second phase difference plate 54 are composite phase difference plates 50 having different alignment directions (ie, alignment directions).

In order to prepare the above-mentioned composite phase difference plate 50 with different alignment directions, the irradiation dose of the second linearly polarized extreme ultraviolet light 66 is not particularly limited in the present invention, as long as it is greater than that of the first linearly polarized extreme ultraviolet light 16. The irradiation dose only needs to be enough, so that the photoalignment film 24 can be affected by the second linear polarized extreme ultraviolet light 66 and change its homeotropic alignment direction. The implementer can consider the convenience of implementation and select an appropriate second linear polarized extreme ultraviolet light 66. The irradiation dose of light 66. However, a higher irradiation dose of the second linearly polarized extreme ultraviolet light 66 requires long-time irradiation and consumes more energy. Therefore, the irradiation dose of the second linearly polarized extreme ultraviolet light 66 is preferably not greater than 1000 mJ/cm ² , and more preferably not greater than 500 mJ/cm ² .

On the other hand, if the irradiation dose of the first linearly polarized ultraviolet light 16 is too high, the resin molecules on the second surface 242 of the photoalignment film 24 will dissociate along a single The preset polarizing direction 161 is in a homeotropic arrangement and fully cross-linked and cured, and its homeotropic arrangement direction can no longer be changed by the irradiation of the second linear polarized ultraviolet light 66 (at this time, it is in a fully cross-linked and cured state, does not destroy its existing orientation). Therefore, when manufacturing a composite retardation film in which the first retardation film 34 and the second retardation film 54 have different alignment directions, the irradiation dose of the first linearly polarized extreme ultraviolet light 16 should not make the photoalignment In principle, the film 24 is completely cured. The irradiation dose of the first linearly polarized extreme ultraviolet light 16 applicable to the present invention is preferably no more than 300 mJ/cm ² .

The present invention also proposes a composite phase difference plate 50 prepared according to the aforementioned method, which includes:

(a) a support plate 42;

(b) a first phase difference plate 34, which is arranged on the support plate 42;

(c) an optical alignment film 24, which is arranged on the first phase difference plate 34; and

(d) a second phase difference plate 54, which is arranged on the optical alignment film 24,

Wherein, the optical alignment film 24 is used to align the first phase difference film 34 and the second phase difference film 54 , and the first phase difference film 34 and the second phase difference film 54 have different alignment directions.

According to the preparation method of the present invention, only a single photo-alignment film can be used to produce two phase difference plates, so the amount of alignment film used can be effectively reduced, so the process cost is relatively low, and thin Composite retardation plate.

In addition, the preparation method of the present invention can simultaneously solve the problem of particles and static electricity on the surface of the alignment film produced by the known brushing method for preparing the composite phase difference plate due to the application of the photo-alignment method.

The present invention also provides a composite phase difference plate, which can further reduce its thickness and achieve the effect of thinning because it can use one less layer of alignment film than the known composite phase difference plate. Several examples are enumerated below to describe the method of the present invention in more detail, but they are only for illustration purposes and are not intended to limit the present invention. The scope of protection of the present invention should be as defined by the scope of the appended patent application.

Example

Preparation of photoalignment film

The photo-alignment resin is coated on the substrate, and then cured after being irradiated with linear polarized ultraviolet light to form a photo-alignment film, which includes the following steps:

1. Methylethylketone (methylethylketone) and cyclopentanone (cyclopentanone) were prepared in a weight ratio of 1:1 to prepare 3.5 g of a mixed solvent.

2. Take 0.5 g of photo-alignment resin (Switzerland Rolic, model ROP103, cinnamate, solid content 10%), add 3.5 g of mixed solvent prepared in step 1, and dilute the solid content of photo-alignment resin to 1.25%.

3. Coat the photo-alignment resin prepared in step 2 on the surface of polyester substrate PET (Toyobo, Japan, model A4100, 10cm×10cm×100μm) by spin coating method (spin coating, 3000rpm, 40s). After it is flattened, it is baked in an oven with a constant temperature of 100°C for two minutes to remove the solvent, and then taken out and left to stand until it returns to room temperature.

4. The photo-alignment resin returned to room temperature in step 3 was irradiated with the first linearly polarized extreme ultraviolet light with a dose of 20 mJ/cm ² to make it cross-linked and have a homeotropic alignment to form a photo-alignment film.

Preparation of liquid crystal coating solution

Liquid crystal coating liquid A: Take 2 g of photo-crosslinkable liquid crystal coating material (Merck, Germany, model 03011, solid content 30%), add 1 g of cyclopentanone, and prepare liquid crystal coating liquid A with a solid content of 20%.

Liquid crystal coating solution B: photo-crosslinkable liquid crystal coating material (Rolic, Switzerland, model Rof5101, solid content 30%), which can be used directly without dilution and adjustment.

Liquid crystal coating solution C: Take 1.35g of photo-crosslinked liquid crystal solid (German BASF, model LC242), 0.11g of optical active agent material (German BASF, model LC756) and 0.07g of photoinitiator (American Ciba, model TPO) , add toluene to fully dissolve, and prepare liquid crystal coating liquid C with a solid content of 29.2%.

A. Preparation of different types of composite phase difference plates

Example 1:

(1.1) Take 3g of liquid crystal coating solution A, apply it on the photo-alignment film by spin coating method (spin coating, 3000rpm, 40 seconds), and bake it in an oven with a constant temperature of 80°C for 5 minutes. Remove the solvent, then take it out and let it return to room temperature. Next, nitrogen gas is passed through and at the same time irradiated with non-linear polarized extreme ultraviolet light (Fusion, Fusion UV chamber, USA) at a dose of 20 mJ/cm ² to cure it to form the first retardation plate. It can be confirmed whether the alignment effect is good by using a polarization analyzer and a phase difference detector (Oji Technical Laboratory, Japan, model Kobra).

(1.2) Paste the first surface of the first phase difference plate to a cellulose triacetate substrate TAC (Japan Konica, 10cm×10cm×80μm) with pressure-sensitive adhesive, and peel off the photoalignment film from the PET, so that The contact surface between the original photo-alignment film and the PET (that is, the second surface of the photo-alignment film) is exposed to the air.

(1.3) Take another 3g of liquid crystal coating solution B, and apply it on the surface of the peeled optical alignment film by spin coating (spin coating, 1000rpm, 40 seconds) to flatten it, and then place it at a constant temperature of 55 °C oven for 5 minutes to remove the solvent, then take it out and let it return to room temperature. Then nitrogen gas is passed through and at the same time, the non-linear polarized ultraviolet light is irradiated with an irradiation dose of 470 mJ/cm ² to cure it to form a second phase difference plate. The prepared composite phase difference plate can be confirmed by using a polarization analyzer and a phase difference detector to determine whether its alignment effect is good.

Example 2:

(2.1) The embodiment is as described in step (1.1), but the irradiation dose is 170mJ/cm ² of nonlinear polarized extreme ultraviolet light, and it is cured to form the first retardation plate.

(2.2) The embodiment is as described in step (1.2).

(2.3) The embodiment is as described in step (1.3).

Example 3:

(3.1) The embodiment is as described in step (1.1), but the liquid crystal coating liquid is replaced by 5g of liquid crystal coating liquid C, and the irradiation dose is 300mJ/ ^cm A first phase difference plate is formed.

(3.2) The embodiment is as described in step (1.2).

(3.3) The embodiment is as described in step (1.3).

Example 4:

(4.1) The embodiment is as described in step (1.1), but the liquid crystal coating solution is replaced with 3g of liquid crystal coating solution B, and the irradiation dose is 470mJ/cm ² Non-linear polarized ultraviolet light is irradiated to make it solidify. A first phase difference plate is formed.

(4.2) The embodiment is as described in step (1.2).

(4.3) The embodiment is as described in step (1.3), but the liquid crystal coating solution is replaced with 5g of liquid crystal coating solution C, and the irradiation dose is 300mJ/cm ² Non-linear polarized ultraviolet light is irradiated to make it solidify. A second phase difference plate is formed.

Example 5:

(5.1) The embodiment is as described in step (4.1), but the irradiation dose is 700mJ/cm ² of nonlinear polarized extreme ultraviolet light, and it is cured to form the first retardation plate.

(5.2) The embodiment is as described in step (4.2).

(5.3) The embodiment is as described in step (4.3).

Embodiment 6:

(6.1) The embodiment is as described in step (4.1), but the irradiation dose is 980mJ/cm ² of nonlinear polarized extreme ultraviolet light, and it is cured to form the first retardation plate.

(6.2) The embodiment is as described in step (4.2).

(6.3) The embodiment is as described in step (4.3).

Comparative example 7:

(7.1) The embodiment is as described in step (4.1), but the irradiation dose is 1100mJ/cm ² of nonlinear polarized extreme ultraviolet light, and it is cured to form the first retardation plate.

(7.2) The embodiment is as described in step (4.2).

(7.3) The embodiment is as described in step (4.3).

The comparison of the irradiation dose of the nonlinear polarized extreme ultraviolet light used for irradiating the first retardation film in the embodiment and the alignment effect of the composite retardation film is summarized in Table 1.

Table 1 Comparison of alignment effects of composite phase difference plates

It can be seen from Table 1 that when the irradiation energy of the nonlinear polarized extreme ultraviolet light used to irradiate the first phase difference plate is 1100mJ/cm ² , its alignment direction cannot be identified by the analyzer, which means that the excessively high irradiation energy leads to light The alignment ability of the alignment film is destroyed, so that the alignment direction of the preset direction is not obvious and the alignment direction is difficult to identify. Therefore, the energy of nonlinear polarized extreme ultraviolet light irradiating the first retardation plate used in the preparation method of the present invention is preferably 20-1000 mJ/cm ² .

B. Preparation of composite phase difference plates with different alignment directions

Comparative example 8:

(8.1) The embodiment is as described in step (1.1), but the liquid crystal coating solution is replaced with 3g of liquid crystal coating solution B, and the irradiation dose is 700mJ/cm ² Non-linear polarized ultraviolet light is irradiated to make it solidify. A first phase difference plate is formed.

(8.2) The embodiment is as described in step (1.2).

(8.3) The embodiment is as described in step (1.3).

Comparative example 9:

(9.1) The embodiment is as described in step (8.1).

(9.2) The implementation method is as described in step (8.2), and the second linearly polarized ultraviolet light with an irradiation dose of 10 mJ/cm ² and a polarization direction orthogonal to the first linearly polarized extreme ultraviolet light is irradiated after peeling The surface of the photo-alignment film (that is, the second surface of the photo-alignment film).

(9.3) The embodiment is as described in step (8.3).

Comparative Example 10:

(10.1) The implementation is as described in step (8.1).

(10.2) The implementation method is as described in step (8.2), and then irradiated with the second linearly polarized extreme ultraviolet light whose irradiation dose is 20mJ/ ^cm2 and whose polarization direction is orthogonal to that of the first linear polarized extreme ultraviolet light after peeling The surface of the photo-alignment film.

(10.3) The implementation is as described in step (8.3).

Comparative Example 11:

(11.1) The implementation is as described in step (8.1), but the selected photo-alignment film is irradiated with the first linear polarized extreme ultraviolet light with a dose of 30 mJ/cm ² to make it cross-linked and has a homeotropic alignment.

(11.2) The implementation method is as described in step (8.2), and then irradiated with the second linearly polarized extreme ultraviolet light whose irradiation dose is 30mJ/ ^cm2 and whose polarization direction is orthogonal to the first linearly polarized extreme ultraviolet light after peeling The surface of the photo-alignment film.

(11.3) The implementation is as described in step (8.3).

Comparative example 12:

(12.1) The implementation method is as described in step (8.1), but the selected photo-alignment film is irradiated with the first linear polarized extreme ultraviolet light at a dose of 100 mJ/cm ² to make it cross-linked and has a homeotropic alignment.

(12.2) The implementation is as described in step (8.2), and the second linearly polarized ultraviolet light with an irradiation dose of 50 mJ/cm ² and a polarization direction orthogonal to the first linearly polarized extreme ultraviolet light is irradiated after peeling The surface of the photo-alignment film.

(12.3) The implementation is as described in step (8.3).

Comparative Example 13:

(13.1) The implementation method is as described in step (8.1), but the selected photo-alignment film is irradiated with the first linear polarized extreme ultraviolet light at a dose of 100 mJ/cm ² to make it cross-linked and has a homeotropic alignment.

(13.2) The implementation method is as described in step (8.2), and then irradiated with the second linearly polarized extreme ultraviolet light with an irradiation dose of 100mJ/cm ² and a polarization direction orthogonal to the first linearly polarized extreme ultraviolet light after peeling The surface of the photo-alignment film.

(13.3) The implementation is as described in step (8.3).

Example 14:

(14.1) The implementation is as described in step (8.1).

(14.2) The implementation method is as described in step (8.2), and the second linearly polarized ultraviolet light with an irradiation dose of 25mJ/cm ² and a polarization direction orthogonal to the first linearly polarized extreme ultraviolet light is irradiated after peeling The surface of the photo-alignment film.

(14.3) The implementation is as described in step (8.3).

Example 15:

(15.1) The implementation is as described in step (8.1).

(15.2) The embodiment is as described in step (8.2), and then irradiated with the second linearly polarized extreme ultraviolet light whose irradiation dose is 30mJ/ ^cm2 and whose polarization direction is orthogonal to the first linear polarized extreme ultraviolet light after peeling The surface of the photo-alignment film.

(15.3) The implementation is as described in step (8.3).

Example 16:

(16.1) The implementation is as described in step (8.1).

(16.2) The embodiment is as described in step (8.2), and then irradiated with the second linearly polarized extreme ultraviolet light whose irradiation dose is 50mJ/ ^cm2 and whose polarization direction is orthogonal to the first linearly polarized extreme ultraviolet light after peeling The surface of the photo-alignment film.

(16.3) The implementation is as described in step (8.3).

Example 17:

(17.1) The implementation method is as described in step (8.1), but the selected photo-alignment film is irradiated with the first linear polarized extreme ultraviolet light at a dose of 30 mJ/cm ² to make it cross-linked and has a homeotropic alignment.

(17.2) The embodiment is as described in step (8.2), and then irradiated with the second linearly polarized extreme ultraviolet light whose irradiation dose is 40mJ/ ^cm2 and whose polarization direction is orthogonal to that of the first linear polarized extreme ultraviolet light after peeling The surface of the photo-alignment film.

(17.3) The implementation is as described in step (8.3).

Example 18:

(18.1) The implementation method is as described in step (8.1), but the selected photo-alignment film is irradiated with the first linear polarized extreme ultraviolet light at a dose of 30 mJ/cm ² to make it cross-linked and has a homeotropic alignment.

(18.2) The embodiment is as described in step (8.2), and then irradiated with the second linearly polarized extreme ultraviolet light whose irradiation dose is 60mJ/ ^cm2 and whose polarization direction is orthogonal to the first linear polarized extreme ultraviolet light after peeling The surface of the photo-alignment film.

(18.3) The implementation is as described in step (8.3).

Example 19:

(19.1) The implementation is as described in step (8.1), but the selected photo-alignment film is irradiated with the first linear polarized extreme ultraviolet light at a dose of 100 mJ/cm ² to make it cross-linked and has a homeotropic alignment.

(19.2) The implementation method is as described in step (8.2), and then irradiated with the second linearly polarized extreme ultraviolet light with an irradiation dose of 150mJ/cm ² and a polarization direction orthogonal to that of the first linearly polarized extreme ultraviolet light after peeling The surface of the photo-alignment film.

(19.3) The implementation is as described in step (8.3).

The comparison of the irradiation dose and alignment effect of the second linearly polarized extreme ultraviolet light whose polarization direction is perpendicular to the first linearly polarized extreme ultraviolet light in the embodiment is summarized in Table 2.

Table 2 Comparison of Alignment Effects of Secondary Irradiation Photo-Alignment Films

It can be seen from Table 2 that when the second linearly polarized extreme ultraviolet light is not greater than the irradiation energy difference of the first linear polarized extreme ultraviolet light, the photo-alignment resin molecules on the second surface will be unstable and cannot be uniformly aligned in a homogeneous manner. Mura is generated, and it is difficult to observe its alignment and deflection effects through a polarizer.

Therefore, the irradiation energy of the second linearly polarized extreme ultraviolet light used in the preparation method of the present invention must be greater than the irradiation energy of the first linearly polarized extreme ultraviolet light, that is, the second surface of the photoalignment film has a color different from that of the first surface. The alignment direction of the phase difference plate can further be prepared with a composite phase difference plate with different alignment directions (that is, the alignment directions of the first phase difference plate and the second phase difference plate are different).

Claims (18)

1. prepare a method for composite phase difference board, it comprises:

A () provides one first back up pad;

B () is coated with a smooth orientation resin in the upper surface of this first back up pad, and with one first this light orientation resin of linear polar biased UV-irradiation, make it carry out light orientation reaction, to form a smooth alignment film;

C () is coated with one first liquid crystal coating material on the first surface of this light alignment film, and with this first liquid crystal coating material of one first non-linear polar biased UV-irradiation, make it solidify to form one first phase difference board;

D the first surface of this first phase difference board sticks on one second back up pad by (), then this light alignment film and this first back up pad are peeled off, and exposes to the open air to make the second surface of this light alignment film;

(e) with one second linear polar biased UV-irradiation on the second surface of this light alignment film, wherein the polar biased direction of this second linear polar biased ultraviolet light is different from the polar biased direction of the first linear polar biased ultraviolet light, and the energy of this second linear polar biased UV-irradiation is greater than the energy of the first linear polar biased UV-irradiation; And

F () is coated with one second liquid crystal coating material on the second surface of this light alignment film, then with this second liquid crystal coating material of the second non-linear polar biased UV-irradiation, make it solidify to form a second phase difference plate.

2. the method for claim 1, wherein the energy of this first non-linear polar biased UV-irradiation is 20 ~ 1000mJ/cm ².

3. the method for claim 1, wherein the energy of this first non-linear polar biased UV-irradiation is 170 ~ 500mJ/cm ².

4. the method for claim 1, wherein the energy of this first linear polar biased UV-irradiation is for being not less than 5mJ/cm ².

5. the method for claim 1, wherein the energy of this second non-linear polar biased UV-irradiation is for being not less than 20mJ/cm ².

6. the method for claim 1, wherein the coating thickness of this light alignment film is 10nm ~ 1 μm.

7. the method for claim 1, wherein this light orientation resin is photocrosslinking type light orientation resin.

8. method as claimed in claim 7, wherein this light orientation resin has the group being selected from cinnamic acid ester group (cinnamate), cumarin ester group (coumarin), styryl phenyl ketone group (Chalcone), dimaleoyl imino (maleimide), quinoline ketone group (quinolinone) and two benzylidene (bisbenzylidene) and forming, at least one of them functional group.

9. the method for claim 1, wherein this first liquid crystal coating material is the photocrosslinking type liquid crystal material with acryl functional group.

10. the method for claim 1, wherein this second liquid crystal coating material is the photocrosslinking type liquid crystal material with acryl functional group.

11. the method for claim 1, wherein the material of this first back up pad is glass, Triafol T resin (Triacetyl Cellulose), polyester based resin (polyester-based resin), acetic acid system resin (acetate-based resin), polyethersulfone system resin (polyethersulfone-based resin), polycarbonate-based resin (polycarbonate-based resin), polyamide series resin (polyamide-based resin), polyimide system resin (polyimide-based resin), polyolefin-based resins (polyolefin-based resin), acrylic ester resin (acrylic-based resin), polyvinyl chloride resin (polyvinyl chloride-based resin), polystyrene resin (polystyrene-based resin), polyvinyl alcohol resin (polyvinyl alcohol-based resin), polyarylate system resin (polyarylate-based resin), polyphenylene sulfide system resin (polyphenylene sulfide-based resin), the sub-vinylite (polyvinylidene chloride-based resin) of poly-dichloro or methacrylate ester resin ((methyl) acrylic-based resin).

12. the method for claim 1, wherein the material of this second back up pad is glass, Triafol T resin (Triacetyl Cellulose), polyester based resin (polyester-based resin), acetic acid system resin (acetate-based resin), polyethersulfone system resin (polyethersulfone-based resin), polycarbonate-based resin (polycarbonate-based resin), polyamide series resin (polyamide-based resin), polyimide system resin (polyimide-based resin), polyolefin-based resins (polyolefin-based resin), acrylic ester resin (acrylic-based resin), polyvinyl chloride resin (polyvinyl chloride-based resin), polystyrene resin (polystyrene-based resin), polyvinyl alcohol resin (polyvinyl alcohol-based resin), polyarylate system resin (polyarylate-based resin), polyphenylene sulfide system resin (polyphenylene sulfide-based resin), the sub-vinylite (polyvinylidene chloride-based resin) of poly-dichloro or methacrylate ester resin ((methyl) acrylic-based resin).

13. the method for claim 1, wherein this second back up pad is release film, Polarizer, diaphragm, diffusion barrier, diffuser plate, light guide plate, brightness enhancement film, flexible panel extends roller or contact panel.

14. the method for claim 1, wherein the upper surface of this first back up pad is the surface once promoting release effect process.

15. the method for claim 1, wherein in this step (b), after the upper surface of this first back up pad is coated with this light orientation resin, comprises a pair this light orientation resin further and carry out dry step.

16. the method for claim 1, wherein in this step (c), be coated with this first liquid crystal coating material on the first surface of this light alignment film after, comprise a pair this first liquid crystal coating material further and carry out dry step.

17. the method for claim 1, wherein in this step (e), be coated with this second liquid crystal coating material on the second surface of this light alignment film after, comprise a pair this second liquid crystal coating material further and carry out dry step.

18. 1 kinds through the composite phase difference board obtained by the method for claim 1, it comprises:

(a) back up pad;

(b) one first phase difference board, it is arranged on this back up pad;

(c) smooth alignment film, it is arranged on this first phase difference board; And

(d) second phase difference plate, it is arranged on this light alignment film,

Wherein, this light alignment film is in order to this first phase difference board of orientation and this second phase difference plate, and this first phase difference board has different alignment direction from this second phase difference plate.