阅读说明：本技术 相位差补偿光学薄膜的制备方法 (Method for preparing phase difference compensation optical film ) 是由 沈勇 于 2021-07-14 设计创作，主要内容包括：本发明公开了一种相位差补偿光学薄膜的制备方法,包括以下步骤：取光学片材,依次进行预拉伸、预热、斜向拉伸和热定型处理。本方法制备的相位差薄膜,其薄膜的拉伸强度较高,光学性能优异,适合使用于液晶或者OELD面板中光学相位差的补偿,且光学补偿薄膜的光轴角度可控,可满足面板贴合Roll to Roll工艺的需要,同时本发明制备方法的生产成本较低,适合大规模产业化生产制造。(The invention discloses a method for preparing a phase difference compensation optical film, which comprises the following steps: and taking the optical sheet, and sequentially performing pre-stretching, preheating, oblique stretching and heat setting treatment. The phase difference film prepared by the method has high tensile strength and excellent optical performance, is suitable for compensating optical phase difference in a liquid crystal or OELD panel, has a controllable optical axis angle, can meet the requirement of a Roll to Roll process for panel bonding, has low production cost, and is suitable for large-scale industrial production and manufacture.)

1. A method for preparing a phase difference compensation optical film is characterized by comprising the following steps:

and taking the optical sheet, and sequentially performing pre-stretching, preheating, oblique stretching and heat setting treatment.

2. The method of manufacturing according to claim 1, wherein the pre-stretching comprises: and soaking the optical sheet in a deionized water diffusion solution for stretching, wherein the stretching direction is longitudinal.

3. The method of claim 1, wherein: the oblique stretching is to simultaneously perform transverse stretching and longitudinal stretching on the preheated sheet; the longitudinal stretching is asymmetric stretching of two sides of the sheet;

the asymmetric stretching is that the two sides of the sheet are not stretched at the same time, or the two sides of the sheet are stretched at the same time at different stretching ratios;

the oblique stretching is segmented stretching, the optical axis angular velocity of an initial stretching section is 0.50-1.00 DEG/s, the optical axis angular velocity of the rest stretching sections is 0.10-0.50 DEG/s, the optical axis angular velocity of the adjacent stretching sections is gradually reduced, and the difference value is 0.05-0.30 DEG/s;

the stretching ratio of the transverse stretching is 1.5-3.0; the stretching ratio of the longitudinal stretching is 1.2-3.0;

the segmental stretching can be 2-5 segments.

4. The method of claim 2, wherein: the pre-stretching time is 30-200S, and the stretching speed ratio is 90-120%.

5. The method of claim 2, wherein: the difference between the solubility parameters of the deionized water diffusion solution and the sheet is 1.0-5.0 (cal/cm)³)^0.5。

6. The method of claim 2, wherein: the deionized water diffusion solution comprises deionized water, a benign solvent and a poor solvent; the volume ratio of the deionized water to the benign solvent to the poor solvent is 1-3: 3-7.5: 1-3; the temperature of the deionized water diffusion solution is 30-60 ℃.

7. The method of claim 2, wherein: the conductivity of the deionized water is 0.1-1.0 us/cm; the benign solvent comprises at least one of acetone, methyl ethyl ketone, cycloethanone, dichloromethane, trichloromethane, chloroform, glycol ether, ethyl acetate, tetrahydrofuran and diacetone alcohol; the poor solvent comprises at least one of isopropanol, n-butanol, isobutanol, n-octanol, n-hexanol, cyclohexanol and hexanediol; the benign solvent has a solubility parameter of 8.0 to 9.8 (cal/cm)³)^0.5(ii) a The poor solvent has a solubility parameter of 10.3 to 17.0 (cal/cm)³)^0.5。

8. The method of claim 1, wherein: the optical sheet has a light transmittance of 90-95%, a haze of 0.10-0.80%, a molecular weight of 22000-32000 g/mol, a molecular weight distribution of 2.3-3.2, and a solubility parameter of 8.5-9.9 (cal/cm)³)^0.5。

9. The method of claim 1, wherein: the optical sheet is made of one of aromatic hexyl carbonate, styrene acrylonitrile copolymer, polystyrene methyl methacrylate, styrene-butadiene-acrylate copolymer, polyacrylate, polyethylene terephthalate, polybutylene terephthalate, polymethyl methacrylate, aromatic polyimide and polyvinyl butyral.

10. A phase difference compensation optical film obtained by the production method according to any one of claims 1 to 9, characterized in that: the standard deviation of the phase difference value (Ro/Rth) of the optical film is 0.1-0.6 nm, the thickness of the optical film is 15-50 um, and the width of the optical film is 1200-2500 mm.

Technical Field

The invention relates to the technical field of photoelectric display, in particular to a preparation method of a phase difference compensation optical film.

Background

In the display field, Liquid Crystal (LCD) and Organic Electroluminescent (OELD) panels have been widely used in various industrial fields, such as: mobile phone, computer, television, vehicle display, medical treatment, etc. Due to birefringence effects of LCD and OELD, when linearly polarized light passes through, optical path difference or phase difference of light is generated on a plane (Ro) or a vertical plane (Rth) of a panel, thereby causing problems such as low definition of a displayed image, viewing angle difference, dark state light leakage, and the like, and in order to compensate for these defects, one or more layers of retardation compensation optical films are usually bonded in the panel, and 1/2 λ, 1/4 λ or 1/2 λ +1/4 λ are commonly used. Meanwhile, with the technical development in the field of display panels in recent years, in order to reduce the manufacturing cost of panel lamination and improve the utilization efficiency of consumables, a roll to roll process is developed and applied to the field of display panel production, and in the manufacturing process of the process, the optical axis angle of the optical compensation film needs to be preset in the film so that the optical compensation film can be directly laminated with a polarizer or other modules.

At present, phase difference compensation optical film materials and production and manufacturing technologies are monopolized by head enterprises such as europe, the united states and japan, the film materials are mainly cyclic polyolefin, block copolymer, polycarbonate and the like, and the adopted resin materials have small molecular weight and low strength and modulus, so that the physical and mechanical properties of the optical film are low; in addition, in the production process, the processes usually adopted are resin blending, two-stage extrusion, three-roll calendering and synchronous stretching, the production process is complicated, the precision requirement of equipment is extremely high, the production efficiency of the film is low, and the cost is high. In addition, in the manufacturing process of the optical film, the extrusion melting resin is easy to generate the phenomenon of melt stretching or elastic necking at the die head, the internal stress between molecular chains is partially retained in the resin and can not be completely released; meanwhile, in the three-roller calendering process, thermal shock and mechanical stress on the upper surface and the lower surface of sheet resin are inconsistent, so that partial molecular chains in the sheet are in a non-relaxed state, and optical problems such as dark fringes and mura appear in a defect area when linearly polarized light passes through the defect area.

In addition, when the sheet is obliquely stretched in an asynchronous track, the stretching rate of the preceding side is always higher than that of the succeeding side, which may cause the tensile stress on the left and right sides of the sheet to be inconsistent, and the molecular chain "orientation" of the preceding side is always higher than that of the succeeding side, so that problems of phase difference between the two sides (operation side and driving side) of the optical film, unstable optical axis angle, and the like occur, and defects such as dark stripes, twill, mura, and the like, may also occur randomly on the film surface of the optical film.

Disclosure of Invention

An object of the present invention is to overcome the disadvantages of the prior art, and to provide a method for manufacturing a retardation compensation optical film, so as to at least achieve the effects of reducing the manufacturing cost, adapting to large-scale continuous production, reducing the display panel bonding cost, and improving the panel bonding efficiency.

The purpose of the invention is realized by the following technical scheme:

a method for preparing a phase difference compensation optical film is characterized by comprising the following steps:

and taking the optical sheet, and sequentially performing pre-stretching, preheating, oblique stretching and heat setting treatment.

Further, the pre-stretching comprises: and soaking the optical sheet in a deionized water diffusion solution for stretching, wherein the stretching direction is longitudinal.

Furthermore, the pre-stretching time is 30-200S, and the stretching speed ratio is 90-120%.

Further, the difference of solubility parameters of the deionized water diffusion solution and the sheet is 1.0-5.0 (cal/cm)³)^0.5。

Further, the deionized water diffusion solution comprises deionized water, a benign solvent and a poor solvent;

further, the volume ratio of the deionized water to the good organic solvent to the poor organic solvent is 1-3: 3-7.5: 1-3; the temperature of the deionized water diffusion solution is 30-60 ℃.

Further, the conductivity of the deionized water is 0.1-1.0 us/cm.

Further, the benign solvent comprises at least one of acetone, methyl ethyl ketone, cycloethanone, dichloromethane, trichloromethane, chloroform, glycol ether, ethyl acetate, tetrahydrofuran and diacetone alcohol; the poor solvent comprises at least one of isopropanol, n-butanol, isobutanol, n-octanol, n-hexanol, cyclohexanol and hexanediol.

Further, the good organic solvent has a solubility parameter of 8.0 to 9.8 (cal/cm)³)^0.5(ii) a The good organic solvent has a solubility parameter of 10.3 to 17.0 (cal/cm)³)^0.5。

The deionized water diffusion solution is prepared by mixing deionized water and an organic solvent, wherein the solubility parameter value of the mixed solvent can be adjusted to be closer to that of sheet resin by the ratio of an organic good solvent to a poor solvent, and molecules of the organic solvent can be swelled and diffused into molecular chains of the resin by controlling the parameters such as the residence time of the sheet in a solution tank, the solution temperature and the like, so that the chains among the molecular chains are wound and opened, the friction among the molecular chains in the resin is reduced, and the residual internal stress in the sheet can be removed when the sheet is pre-stretched; meanwhile, by controlling the solubility parameter difference between the deionized water diffusion solution and the sheet resin, the proportion of deionized water in the solution entering resin molecular chains along with an organic solvent can be regulated, wherein water molecules are combined with carbonyl, ester bonds and the like on resin molecular chains in an intermolecular hydrogen bond mode, and when the sheet is obliquely stretched, the water molecules combined with the intramolecular hydrogen bonds in the resin can play a role in lubrication, so that the mobility of the molecular chains in the resin and the intermolecular chains is improved, the stress concentration effect in the film stretching process is avoided, the internal unevenness of optical film stretching is improved, and the optical defects such as dark marks, mura and the like are effectively avoided.

Further, the oblique stretching is to simultaneously perform transverse stretching and longitudinal stretching on the preheated sheet; the longitudinal stretching is asymmetric stretching of both sides of the sheet.

Further, the asymmetric stretching is stretching at different times on both sides of the sheet, or stretching at different stretch ratios on both sides of the sheet simultaneously.

Furthermore, the oblique stretching is segmented stretching, the optical axis angular velocity of the initial stretching section is 0.50-1.00 DEG/s, the optical axis angular velocity of the rest stretching sections is 0.10-0.50 DEG/s, the optical axis angular velocity of the adjacent stretching sections is gradually reduced, and the difference value is 0.05-0.30 DEG/s.

Further, the stretching ratio of the transverse stretching is 1.5-3.0; the stretching ratio of the longitudinal stretching is 1.2-3.0.

Further, the segmental stretching can be 2-5 segments

Further, the stretching temperature of the oblique stretching is 10-30 ℃ above the vitrification temperature of the sheet material.

The mode that the optical axis angle multi-section is stretched is adopted in the oblique stretching, and the angular velocity of each section is decreased progressively, so that the phenomenon of uneven stretching of the left side and the right side of the sheet due to the fact that the stretching speeds are different in the oblique stretching process is avoided, the phase difference value of the left side and the right side of the film and the deviation of the optical axis angle are reduced, and the stretching uniformity and the optical stability of the optical film are improved.

Further, the optical sheet has a light transmittance of 90 to 95%, a haze of 0.10 to 0.80%, a molecular weight of 22000 to 32000g/mol, a molecular weight distribution of 2.3 to 3.2, and a solubility parameter of 8.5 to 9.9 (cal/cm)³)^0.5。

Further, the optical sheet includes at least one of aromatic hexyl carbonate, styrene acrylonitrile copolymer, polystyrene methyl methacrylate, styrene-butadiene-acrylate copolymer, polyacrylate, polyethylene terephthalate, polybutylene terephthalate, polymethyl methacrylate, aromatic polyimide, and polyvinyl butyral.

The high molecular weight resin adopted by the learning sheet can improve the tensile modulus, the bending resistance and other physical and mechanical properties of the film, and meanwhile, the molecular weight distribution of the resin is wide, so that the mobility of molecular chains in the resin can be improved, the problem of concentration of internal stress generated inside the film when the asynchronous track is obliquely stretched is avoided, and the ductility and the stretchability of the sheet in the stretching process are improved.

Another object of the present invention is to provide a retardation compensation optical film manufactured by the method, so as to at least achieve the effects of avoiding optical defects such as dark fringes and Mura and improving the physical and mechanical properties of the film.

Further, the standard deviation of the phase difference value (Ro/Rth) of the optical film is 0.1-0.6 nm, the thickness of the optical film is 15-50 um, and the width of the optical film is 800-2500 mm.

The invention has the beneficial effects that:

1. the invention provides a phase difference compensation optical film suitable for roll to roll lamination, which has stable phase difference (Ro/Rth) and controllable optical axis angle and can obviously improve the defects of mura, dark fringes and the like in the film.

2. The invention provides a preparation method of a phase difference compensation optical film, which has lower production and manufacturing cost and is suitable for large-scale continuous production.

Detailed Description

The technical solutions of the present invention are described in further detail below, but the scope of the present invention is not limited to the following.

Example 1

The method for preparing the phase difference compensation optical film comprises the following specific steps:

1) and (3) putting the optical sheet into a solution ion diffusion solution for pre-stretching.

The optical sheet has the light transmittance of 91.0%, the haze of 0.50%, the thickness of 100um and the width of 800 mm; the sheet material is aromatic hexyl carbonate, the molecular weight is 24000g/mol, the molecular weight distribution is 2.5, and the solubility parameter is 9.5 (cal/cm)³)^0.5。

The difference in solubility parameter between the ionic water-diffusing solution and the aromatic polycarbonate was 2.70 (cal/cm)³)^0.5The deionized water diffusion solution consists of deionized water, methyl ethyl ketone (benign solvent) and isopropanol (poor solvent), the conductivity of the deionized water is 0.3us/cm, and the solubility parameters of the methyl ethyl ketone and the isopropanol are respectively 9.2 and 11.5 (cal/cm)³)^0.5The composition and volume ratio of the solution are as follows: 20.0% of deionized water, 70.0% of methyl ethyl ketone and 10.0% of isopropanol.

The stretching direction of the pre-stretching is longitudinal, the residence time in the solution is 30s, the pre-stretching speed ratio is 101.2%, and the solution temperature is 45 ℃.

2) Preheating the material obtained in step 1) at a temperature of 150 ℃.

3) Obliquely stretching the material obtained in the step 2) at the temperature of 140 ℃.

Wherein the oblique stretching is performed in an asynchronous stretching track; the oblique stretching comprises transverse stretching and longitudinal stretching; the transverse stretching magnification is 1.7, and the longitudinal stretching magnification is 2.0; the longitudinal stretching is stretching the OS side first and then the DS side (the OS side is a side close to the track operation side, and the DS side is the other side, that is, a side close to the track driving side).

Further, the oblique stretching was two-stage stretching, and the optical axis angular velocity of the initial stretching stage was 0.70 °/s, and the optical axis angular velocity of the second stretching stage was 0.40 °/s.

4) Carrying out heat setting treatment on the material obtained in the step 3) at 135 ℃ to obtain the material.

The optical axis angle of the obtained optical film is 45.2 degrees, the standard deviation is 0.5 degree, the Ro is 135.6nm, the standard deviation is 0.5nm, the Rth is 10.7nm, and the standard deviation is 0.4 nm; the thickness of optical film is 30um, and the width is 1600 mm.

Example 2

The method for preparing the phase difference compensation optical film comprises the following specific steps:

1) and (4) taking the optical sheet. Pre-stretching in a deionizing and diffusing solution.

The optical sheet has the light transmittance of 92.0%, the haze of 0.40%, the thickness of 150um and the width of 600 mm; the sheet material is styrene acrylonitrile copolymer, the molecular weight is 27000g/mol, the molecular weight distribution is 2.6, and the solubility parameter is 9.2 (cal/cm)³)^0.5。

The difference in solubility parameters between the deionized water diffusion solution and the styrene acrylonitrile copolymer was 2.20 (cal/cm)³)^0.5The deionized water diffusion solution consists of deionized water, ethyl acetate (benign solvent) and n-butyl alcohol (poor solvent), the conductivity of the deionized water is 0.4us/cm, and the solubility parameters of the ethyl acetate and the n-butyl alcohol are respectively 9.1 and 11.4 (cal/cm)³)^0.5The composition and volume ratio of the solution are as follows: 15.0% of deionized water, 72.0% of ethyl acetate and 13.0% of n-butanol.

The stretching direction of the pre-stretching is longitudinal, the residence time in the solution is 45s, the pre-stretching speed ratio is 99.5%, and the solution temperature is 35 ℃.

2) Preheating the material obtained in step 1) at a temperature of 140 ℃.

3) Obliquely stretching the material obtained in the step 2) at the temperature of 135 ℃.

Wherein the oblique stretching is performed in an asynchronous stretching track; the oblique stretching comprises transverse stretching and longitudinal stretching; the transverse stretching magnification is 2.1, and the longitudinal stretching magnification is 2.3; the longitudinal stretching is performed by stretching the OS side first and then stretching the DS side.

Further, the oblique stretching is three-stage stretching, and the optical axis angular velocity of the initial stretching stage is 0.90 °/s, the optical axis angular velocity of the second stretching stage is 0.70 °/s, and the optical axis angular velocity of the third stretching stage is 0.50 °/s.

4) Carrying out heat setting treatment on the material obtained in the step 3) at 131 ℃ to obtain the material.

The optical axis angle of the obtained optical film is 75.0 degrees, the standard deviation is 0.3 degrees, the Ro is 130.2nm, the standard deviation is 0.4nm, the Rth is 12.1nm, and the standard deviation is 0.2 nm; the thickness of optical film is 30um, and the width is 1260 mm.

Example 3

The method for preparing the phase difference compensation optical film comprises the following specific steps:

1) the optical sheet is pre-stretched in a deionizing diffusion solution.

The optical sheet has the light transmittance of 91.0%, the haze of 0.50%, the thickness of 100um and the width of 800 mm; the sheet material is aromatic hexyl carbonate, the molecular weight is 23000g/mol, the molecular weight distribution is 2.4, and the solubility parameter is 9.5 (cal/cm)³)^0.5。

The difference of solubility parameters of the deionized water diffusion solution and the aliphatic polycarbonate is 2.30 (cal/cm)³)^0.5The deionized water diffusion solution consists of deionized water, chloroform (benign solvent) and isobutanol (poor solvent), the conductivity of the deionized water is 0.4us/cm, and the solubility parameters of the chloroform and the isobutanol are respectively 9.3 and 10.8 (cal/cm)³)^0.5The composition and volume ratio of the solution are as follows: deionized water 14.0%, chloroform 71.0%Isobutanol 15.0%.

The stretching direction of the pre-stretching is longitudinal, the residence time in the solution is 40s, the pre-stretching speed ratio is 99.3%, and the solution temperature is 43 ℃.

2) Preheating the material obtained in the step 1) at the temperature of 141 ℃.

3) Obliquely stretching the material obtained in the step 2) at the temperature of 133 ℃.

Wherein the oblique stretching is performed in an asynchronous stretching track; the oblique stretching comprises transverse stretching and longitudinal stretching; the transverse stretching magnification is 2.1, and the longitudinal stretching magnification is 2.4; the longitudinal stretching is performed by stretching the DS side first and then stretching the OS side.

Further, the oblique stretching is a three-stage stretching, and the optical axis angular velocity of the initial stretching stage is 0.60 °/s, the optical axis angular velocity of the second stretching stage is 0.50 °/s, and the optical axis angular velocity of the third stretching stage is 0.40 °/s.

4) Carrying out heat setting treatment on the material obtained in the step 3) at 130 ℃ to obtain the material.

The optical axis angle of the obtained optical film is-45.0 degrees, the standard deviation is 0.3 degrees, Ro is 249.8nm, the standard deviation is 0.4nm, Rth is 11.0nm, and the standard deviation is 0.3 nm; the thickness of the optical film is 20um, and the width is 1920 mm.

Example 4

The method for preparing the phase difference compensation optical film comprises the following specific steps:

1) the optical sheet is pre-stretched in a deionizing diffusion solution.

The optical sheet has the light transmittance of 91.0%, the haze of 0.60%, the thickness of 250um and the width of 700 mm; the sheet resin material is styrene acrylonitrile copolymer, the molecular weight is 29000g/mol, the molecular weight distribution is 2.9, and the solubility parameter is 9.2 (cal/cm)³)^0.5。

The difference of solubility parameters of the deionized water diffusion solution and the aliphatic polycarbonate is 2.20 (cal/cm)³)^0.5The deionized water diffusion solution consists of deionized water, ethyl acetate (benign solvent) and isopropanol (poor solvent), and the conductivity of the deionized water0.6us/cm, and solubility parameters of ethyl acetate and isopropanol of 9.1 and 11.5 (cal/cm), respectively³)^0.5The composition and volume ratio of the solution are as follows: 12.0% deionized water, 73.0% ethyl acetate, 15.0% isopropyl alcohol.

The stretching direction of the pre-stretching is longitudinal, the residence time in the solution is 60s, the pre-stretching speed ratio is 99.1%, and the solution temperature is 37 ℃.

2) Preheating the material obtained in the step 1) at a temperature of 130 ℃.

3) Obliquely stretching the material obtained in the step 2) at the temperature of 125 ℃.

Wherein the oblique stretching is performed in an asynchronous stretching track; the oblique stretching comprises transverse stretching and longitudinal stretching; the transverse stretching magnification is 2.3, and the longitudinal stretching magnification is 2.6; the longitudinal stretching is performed by stretching the OS side first and then stretching the DS side.

In addition, the oblique stretching is three-stage stretching, the optical axis angular velocity of the initial stage is 0.60 °/s, the optical axis angular velocity of the second stretching stage is 0.45 °/s, and the optical axis angular velocity of the third stretching stage is 0.30 °/s.

4) Carrying out heat setting treatment on the material obtained in the step 3) at 125 ℃ to obtain the material.

The optical axis angle of the obtained optical film is 45.1 degrees, the standard deviation is 0.2 degrees, the Ro is 260.1nm, the standard deviation is 0.4nm, the Rth is 12.1nm, and the standard deviation is 0.3 nm; the thickness of optical film is 40um, and the width is 1610 mm.

Examples of the experiments

The following tests were carried out on the optical films obtained in examples 1 to 4, and the test results are shown in tables 1 to 4, and table 5 shows the Mura grade judgment rule.

1) Ro, Rth test: the measurement was carried out by using a phase difference meter, the equipment model was KOBRA-HB (King Korea), the measurement wavelength was 550nm, and the measurement method was "rotational polariton method".

2) mura test: the visual inspection method is adopted, namely in a dark room, a test sample is placed in two layers of polaroids with orthogonal optical axis angles, a white LED lamp is placed on the back of the lower layer of polaroid, and the observation angle between human eyes and the sample is 60 degrees. The film sample lengths were: the actual width value of the stretching track outlet is generally 1600-2500 mm; the width of the film sample was: 250-300 mm.

TABLE 1Ro test data

TABLE 2Rth test data

TABLE 3 optical axis Angle test data

TABLE 4Mura test data

TABLE 5Mura grade decision rule

The foregoing is illustrative of the preferred embodiments of this invention, and it is to be understood that the invention is not limited to the precise form disclosed herein and that various other combinations, modifications, and environments may be resorted to, falling within the scope of the concept as disclosed herein, either as described above or as apparent to those skilled in the relevant art. And that modifications and variations may be effected by those skilled in the art without departing from the spirit and scope of the invention as defined by the appended claims.