A method for analyzing the structure of a privacy film

Abstract

The application discloses a structure analysis method of a privacy film, and comprises steps S1 to S3, S1. A privacy film is provided, the privacy film comprises a transmission layer and an absorption layer with different thermal expansion coefficients; S2. The privacy film is continuously heated, so that the transmission layer and the absorption layer are deformed to cause interface separation; S3. The physical parameters of the transmission layer and the absorption layer are observed and measured. The structure analysis method of the privacy film utilizes the difference in the thermal expansion coefficients caused by the different formulations of the transmission layer and the absorption layer, and makes the transmission layer and the absorption layer deform to different degrees through heating, so that the boundary of the transmission layer and the absorption layer is separated, and thus the product structure can be more accurately determined by the researchers under the microscope.

Description

Technical Field

[0001] This invention relates to the field of optical technology, and in particular to a method for structural analysis of privacy films. Background Technology

[0002] With the widespread use of monitors, users have increasingly higher requirements for the privacy of displayed pages, which has spurred the continuous development and improvement of privacy screen protector technology. In the manufacturing process, privacy screen protectors generally involve first forming the grating structure of the transmissive layer on a base groove, then filling the gaps in the microstructure with an absorption layer, and finally using UV curing.

[0003] Currently, privacy screen protectors on the market typically fill the transmissive layer with black glue before it is fully cured by UV molding, so that it becomes an incompletely cured absorption layer by UV molding. Finally, it is UV cured to further improve the adhesion between the transmissive and absorption layers.

[0004] While the above preparation methods can improve the weather resistance or bending resistance of privacy film products, they also cause significant challenges for researchers when analyzing the structure of the finished product. Traditional structural analysis methods generally use a blade to select cross-sections of the product for analysis, but due to the enhanced adhesion between the transmission layer and the absorption layer, the cross-sections of the transmission layer and the absorption layer in the cross-section are relatively blurred (see appendix). Figure 6 As shown in the figure, it is impossible to accurately measure and obtain effective data under a microscope, resulting in a large error in the final analysis. Summary of the Invention

[0005] The purpose of this invention is to provide a method for structural analysis of privacy films. By heating the transmissive and absorbent layers with different coefficients of thermal expansion, slight separation of the interface is achieved, thereby enabling accurate testing of the structural parameters between the layers.

[0006] The objective of this invention is achieved through the following technical solution:

[0007] A method for structural analysis of privacy films includes the following steps:

[0008] S1. Provide a privacy film, the privacy film comprising a transmissive layer and an absorbent layer with different coefficients of thermal expansion;

[0009] S2. The privacy film is continuously heated, causing the transmissive layer and the absorbent layer to deform and trigger interface separation;

[0010] S3. Observe and measure the physical parameters of the transmission layer and the absorption layer.

[0011] In some embodiments, the transmissive layer is cured from a light-transmitting adhesive, the light-transmitting adhesive comprising the following components by weight fraction:

[0012]

[0013] In some embodiments, the absorbent layer is cured from a filler adhesive, the filler adhesive comprising the following components by weight fractions:

[0014]

[0015] In some embodiments, the privacy film further includes a substrate layer;

[0016] The transmission layer is disposed on the substrate layer, and the transmission layer has multiple microstructures and grooves are formed between adjacent microstructures.

[0017] The absorbent layer is disposed within the groove.

[0018] In some embodiments, the absorption layer extends upward and forms a planar layer covering the transmission layer;

[0019] The thickness of the planar layer is less than or equal to 1 μm.

[0020] In some embodiments, the height of the privacy film is 10-200 μm.

[0021] In some embodiments, in step S2, the heating temperature of the privacy film is 200-300°C.

[0022] In some embodiments, in step S2, the heating time of the privacy film is 72-168 hours.

[0023] In some embodiments, in step S2, an OCA adhesive layer may be applied to the surface of the privacy film before heating it.

[0024] In some embodiments, the thickness of the OCA adhesive layer is 20-200 μm.

[0025] In some embodiments, the privacy film is heated to a temperature of 200-250°C.

[0026] In some embodiments, the privacy film is heated for 5-48 hours.

[0027] Compared with the prior art, the beneficial effects of the present invention include at least the following: by utilizing the difference in thermal expansion coefficients caused by the different formulations of the transmission layer and the absorption layer, the two are deformed to different degrees by heating, thereby making the boundary between the transmission layer and the absorption layer appear separated, thus making it easier for researchers to determine the product structure more accurately at the microscopic level. Attached Figure Description

[0028] Figure 1 This is a flowchart of the method for analyzing the structure of the privacy film of the present invention.

[0029] Figure 2AThis is a schematic diagram of the structure of the privacy film of the present invention.

[0030] Figure 2B This is another schematic diagram of the privacy film of the present invention.

[0031] Figure 3 This is a schematic diagram showing the rate of change of the dimensions of the privacy film TD with temperature in Embodiment 1 of the present invention, which has a structural height of 95 μm.

[0032] Figure 4 This is a schematic diagram of the abnormal structural texture in the MD direction of the privacy film with a structural height of 95μm in Embodiment 1 of the present invention.

[0033] Figure 5A This is a schematic diagram of a privacy film with an OCA adhesive layer according to the present invention.

[0034] Figure 5B This is a schematic diagram of another structure of the privacy film with an OCA adhesive layer according to the present invention.

[0035] Figure 6 This is a schematic diagram of the cross-sectional structure of the privacy screen protector using traditional structural analysis methods.

[0036] In the diagram: 1. Privacy film; 11. Substrate layer; 12. Transmissive layer; 121. Groove; 13. Absorbing layer; 131. Planar layer; 2. OCA adhesive layer. Detailed Implementation

[0037] Exemplary embodiments will now be described more fully with reference to the accompanying drawings. However, these exemplary embodiments can be implemented in many forms and should not be construed as limited to the embodiments set forth herein; rather, they are provided to make the invention more comprehensive and complete, and to fully convey the concept of the exemplary embodiments to those skilled in the art. The same reference numerals in the drawings denote the same or similar structures, and therefore repeated descriptions of them will be omitted.

[0038] The terms used to express position and direction in this invention are illustrated with reference to the accompanying drawings, but changes can be made as needed, and all such changes are included within the scope of protection of this invention.

[0039] This application discloses a method for analyzing the structure of a privacy screen. This method utilizes the difference in thermal expansion coefficients caused by the different formulations of the transmission layer 12 and the absorption layer 13. By heating, the two layers are deformed to different degrees. This deformation is usually characterized by expansion followed by contraction, which causes the boundary between the transmission layer 12 and the absorption layer 13 to appear separated, thereby facilitating researchers to more accurately determine the product structure at the microscopic level.

[0040] Example 1

[0041] See Figure 1 As shown, this application discloses a method for analyzing the structure of a privacy screen, including steps S1 to S3.

[0042] S1. Provide a privacy film 1, which includes a transmissive layer 12 and an absorbent layer 13 with different coefficients of thermal expansion.

[0043] In this step, the coefficients of thermal expansion of the transmissive layer 12 and the absorbent layer 13 of the privacy film 1 are determined by their respective formulation differences.

[0044] Specifically, the transmissive layer 12 is cured and molded from a light-transmitting adhesive, which comprises the following components in weight fractions: 50-60 parts of photocurable resin A1, 30-40 parts of photocurable monomer B1, 3-8 parts of photoinitiator C1, and 3-8 parts of release agent.

[0045] Among them, the UV-curable resin A1 can be selected from UV oligomers in the field, including but not limited to polyurethane acrylate oligomers, acrylate oligomers, epoxy acrylate oligomers, and polyester acrylate oligomers. For example, it can be Sartoma CN9006NS (6-functional aliphatic polyurethane acrylate), Sartoma CN8010NS (2-functional aliphatic polyurethane acrylate), Changxing 6158B-80 (3- and 8-functional aliphatic polyurethane acrylate), Changxing DR-U029 (4-functional aliphatic polyurethane acrylate), 6210G (2-functional modified epoxy acrylate), etc.

[0046] The photocurable monomer B1 may be selected from monomers in the art, including but not limited to one or more of the following: (meth)acrylate, (meth)acrylate isobornyl acrylate (IBOA), bisphenol A diacrylate (ODA), tetrahydrofurfuryl acrylate (THFA), o-phenylphenoxyethyl acrylate (OPPEA), trimethylolpropane triacrylate (TMPTA), phenoxyethyl acrylate, dipropylene glycol diacrylate, tripropylene glycol diacrylate, isodecyl acrylate, ethoxyethoxyethyl acrylate, and laurate.

[0047] Photoinitiator C1 can be a common initiator in the art, including but not limited to one or more of 1-hydroxycyclohexylphenyl ketone (184), 2-hydroxy-methylphenylpropane-1-one (1173), 2-methyl-1-(4-methylthiophenyl)-2-morpholino-1-propanone (907), benzoin dimethyl ether (651), xylene ketone (BP), 2-isopropylthioxanthone (ITX), 2,4,6-(trimethylbenzoyl)-diphenylphosphine oxide (TPO), and diacylphosphine oxide (819).

[0048] Release agents can be selected that facilitate demolding of metal or soft molds, including but not limited to Tego's ZG-400, RAD2200, 2100, 2500, etc.

[0049] The absorber layer 13 is cured and molded from a filler adhesive, which comprises the following components in weight fractions: 30-40 parts of photocurable resin A2, 35-45 parts of photocurable monomer B2, 3-8 parts of photoinitiator C2, 4-10 parts of light-absorbing material, 0.5-3 parts of additives, and 0-5 parts of thiol.

[0050] Among them, the light-curing resin A2 is a polyether or polyester resin. For example, the polyether resin can be a polyether-type polyurethane acrylate, a polyether-type acrylate, a polyether-type epoxy acrylate, etc., and the polyester resin can be a polyester-type acrylic resin, a polyester-type polyurethane acrylate, etc.

[0051] The photocurable monomer B2 comprises acrylates containing at least six EO blocks, such as bisphenol A dimethacrylate (BPA10EODA), BPA8EODA, BPA15EODA, BPA20EODA, etc. In addition, photocurable monomer B2 may also contain small amounts of conventional monomers, such as o-phenylphenoxyethyl acrylate (OPPEA), bisphenol A diacrylate (ODA), tetrahydrofurfuryl acrylate (THFA), dipropylene glycol diacrylate, tripropylene glycol diacrylate, isodecyl acrylate, ethoxyethoxyethyl acrylate, and trimethylolpropane triacrylate.

[0052] Photoinitiator C2 is at least one of α-hydroxy ketone photoinitiators, acyl oxide photoinitiators, and oxime ester photoinitiators. For example, photoinitiator C2 includes at least one of 1,1'-(methylenedi-4,1-phenylene)bis[2-hydroxy-2-methyl-1-propanone] (127), 2,4,6-(trimethylbenzoyl)-diphenylphosphine oxide (TPO), bis2,6-difluoro-3-pyrrolephenyldipentadienoate (784), and oxime esters (OXE01, OXE02, OXE03, OXE04).

[0053] The light-absorbing material can be a common material in the field, including but not limited to black pigment paste, dye polymer dispersed liquid crystal, etc.

[0054] The additives are common leveling additives in the field, including but not limited to BYK333, 337, 378, 3505, 3500, and TEGO's RAD2200, 2100, 2500, etc.

[0055] S2. The privacy film 1 is continuously heated, causing the transmission layer 12 and the absorption layer 13 to deform and trigger interface separation.

[0056] In this step, the privacy film 1 is placed in a high-temperature furnace and heated at a temperature of 200-300℃ for a time of 72-168 hours to ensure the deformation and separation effect of the transmission layer 12 and the absorption layer 13.

[0057] S3. Observe and measure the physical parameters of the transmission layer 12 and the absorption layer 13.

[0058] In this step, the privacy film 1 is removed and placed under a light source. The presence or absence of structural abnormalities in the MD direction of the privacy film 1 can be visually observed (see...). Figure 4 , Figure 4 (This is a schematic diagram of the abnormal structural texture of the privacy screen protector in the MD direction). Since the interface between the transmission layer 12 and the absorption layer 13 is slightly separated at this time, the structure can be photographed with a microscope, and the physical parameters of the transmission layer 12 and the absorption layer 13, including width and structural period, can be accurately measured to obtain effective data.

[0059] It should be noted that in the above method, the main factor affecting the separation of the transmission layer 12 and the absorption layer 13 is the structural height of the privacy film 1. Therefore, different heating temperatures and heating times can be set according to different structural heights of the privacy film 1.

[0060] In some embodiments, the height of the privacy film 1 is 10-200 μm. For example, a privacy film 1 with a height of 95 μm is selected. In this privacy film 1, the light-transmitting adhesive forming the transmission layer 12 comprises the following components in weight fractions: 50 parts of Sartoma CN8010NS (2-functional aliphatic polyurethane acrylate) as photocurable resin A1; 40 parts of bisphenol A diacrylate (ODA) as photocurable monomer B1; 4 parts of benzoin dimethyl ether (651) as photoinitiator C1; 1 part of 2,4,6-(trimethylbenzoyl)-diphenylphosphine oxide (TPO); and 5 parts of ZG-400 (TEGO) as release agent. The filler adhesive forming the absorption layer 13 comprises the following components in weight fractions: UV-curable resin A2 is selected from 40 parts of polyether-type polyurethane acrylate; UV-curable monomer B2 is selected from 35 parts of bisphenol A dimethacrylate (BPA) and 5 parts of bisphenol A diacrylate (ODA); photoinitiator C2 is selected from 5 parts of 2,4,6-(trimethylbenzoyl)-diphenylphosphine oxide (TPO) and 2 parts of oxime ester (OXE01); light-absorbing material is selected from 8 parts of black pigment; additives are selected from 2 parts of RAD2200 (TEGO); and thiol is selected from 3 parts.

[0061] like Figure 3The diagram shows the dimensional changes of the aforementioned privacy film 1TD along the temperature. As can be seen, the light-transmitting adhesive expands upon heating, peaking between 110-120°C, and then begins to shrink. At temperatures generally above 160°C, the shrunk size of the light-transmitting adhesive is smaller than its original size before heating. Similarly, the filler adhesive expands upon heating, peaking between 180-190°C, and then begins to shrink. At temperatures generally above 240°C, the shrunk size of the filler adhesive is also smaller than its original size before heating. In other words, at a heating temperature of approximately 160°C, the light-transmitting adhesive and the filler adhesive already show a tendency to separate, and especially at heating temperatures of 240°C or higher, the light-transmitting adhesive and the filler adhesive completely separate.

[0062] In one specific embodiment, the privacy film 1 is heated to a temperature of 200°C for 170 hours. At this time, the light-transmitting adhesive separates from the filler adhesive, and correspondingly, the boundary between the transmissive layer 12 and the absorbent layer 13 is clear, allowing for accurate measurement of physical parameters such as the width and structural period of the privacy film 1.

[0063] During the heating process of the privacy film 1, if the heating temperature is below 200℃ and the heating time is less than 168h, the light-transmitting adhesive of the transmission layer 12 and the filling adhesive of the absorption layer 13 will not be completely deformed, and the boundary between the two cannot be accurately confirmed; if the heating temperature is above 300℃ and the heating time is more than 72h, the privacy film 1 may be burned or its internal structure may be severely deformed, affecting the accuracy of the data.

[0064] Given a fixed height for the privacy film 1, adjustments can be made by increasing the heating temperature and shortening the heating time. Taking the privacy film 1 with a structural height of 95μm as an example, in order to separate the boundary between the transmission layer 12 and the absorption layer 13, the heating time and heating temperature can be set as follows: heating temperature of 230℃ and heating time of 120h; or heating temperature of 250℃ and heating time of 108h; or heating temperature of 300℃ and heating time of 72h, etc.

[0065] See Figure 2A As shown, in some embodiments, the privacy film 1 further includes a substrate layer 11, which may be a flexible film, including but not limited to PMMA, TAC, PET, COP, PE or PP.

[0066] The transmission layer 12 is disposed on the substrate layer 11. The transmission layer 12 and the substrate layer 11 can be fabricated separately or integrally formed together, as long as they are made of the same material. In addition, the transmission layer 12 has multiple microstructures, which are roughly isosceles trapezoidal in shape with a smaller top and a larger bottom, and grooves 121 are formed between adjacent microstructures.

[0067] The absorption layer 13 is disposed in the groove 121, and the absorption layer 13 is flush with the groove opening of the groove 121.

[0068] See Figure 2B As shown, in some other embodiments, the absorption layer 13 extends upward to form a planar layer 131 covering the transmission layer 12, the thickness of the planar layer 131 being less than or equal to 1 μm.

[0069] On the one hand, the planar layer 131 helps to improve the viewing angle limitation, enhance visibility and contrast, increase privacy protection, and improve anti-glare effect. On the other hand, the planar layer 131 increases the surface area of ​​the absorption layer 13, which is more conducive to accelerating the deformation of the absorption layer 13 after the OCA adhesive layer 2 is applied, thereby improving the separation efficiency of the transmission layer 12 and the absorption layer 13.

[0070] Example 2

[0071] See Figure 5A and Figure 5B As shown, this application also discloses a method for analyzing the structure of a privacy film, which is based on Example 1, except that: before heating the privacy film 1 in step S2, an OCA adhesive layer 2 can be first set on its surface. The OCA adhesive layer 2 can be directly bonded to the absorption layer 13, or bonded to the absorption layer 13 through the planar layer 131.

[0072] This method involves bonding an OCA adhesive layer 2 to the surface of the privacy film 1. By utilizing the strong creep capability of the OCA adhesive at high temperatures, a stress is applied to the absorber layer 13 bonded to it, accelerating the deformation of the absorber layer 13 and thereby improving the separation efficiency between the absorber layer 13 and the transmissive layer 12.

[0073] In some embodiments, the thickness of the OCA adhesive layer 2 is 20-200 μm. If the thickness of the OCA adhesive layer 2 is less than 20 μm, its creep-induced deformation of the absorption layer 13 is not significant. If the thickness of the OCA adhesive layer 2 is greater than 200 μm, structural distortion of the privacy film 1 may occur during heating, affecting subsequent data acquisition and analysis. Preferably, when the thickness of the OCA adhesive layer 2 is 60-100 μm, the deformation effect of the OCA adhesive layer 2 on the absorption layer 13 is better. The thickness of the OCA adhesive layer 2 can be 60 μm, 70 μm, 80 μm, 90 μm, 100 μm, etc.

[0074] For example, the privacy film 1 with a structural height of 95μm in Example 1 is still selected, and an OCA adhesive layer with a thickness of 100μm is set on its surface and heated. The heating temperature is 150-250℃ and the heating time is 5-48h.

[0075] When the privacy film 1 is heated to 150°C for 20 hours, the separation of the light-transmitting adhesive and the filler adhesive is not obvious. Correspondingly, the boundary between the transmission layer 12 and the absorption layer 13 is not clear, making it impossible to accurately measure the width and structural period and other physical parameters of the privacy film 1.

[0076] When the temperature is raised to 200℃ and the heating time is 12h, the light-transmitting adhesive and the filler adhesive separate, and the boundary between the corresponding transmission layer 12 and absorption layer 13 is clear. At this time, the width and structural period of the privacy film 1 can be accurately measured.

[0077] When the temperature is raised to 250℃ and the heating time is 10h, the light-transmitting adhesive and the filler adhesive separate, and the boundary between the corresponding transmission layer 12 and absorption layer 13 is clear. At this time, the width and structural period of the privacy film 1 can also be accurately measured.

[0078] It should be noted that the above experimental data only applies to the privacy film 1 with a structural height of 95 μm. Within a safe range, the higher the temperature, the shorter the time required for the light-transmitting adhesive and the filler adhesive to separate. Different heating temperatures and times can be set for privacy films 1 with different structural heights. For example, when the structural height of the privacy film 1 is 20 μm, the heating temperature is 200°C and the heating time is 8 hours; or, the heating temperature is 250°C and the heating time is 5 hours. When the structural height of the privacy film 1 is 100 μm, the heating temperature is 200°C and the heating time is 22 hours; or, the heating temperature is 250°C and the heating time is 15 hours.

[0079] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the invention without departing from the principles and spirit of the invention, and all such changes should fall within the protection scope of the claims of the present invention.

Claims

1. A method for structural analysis of a privacy screen protector, characterized in that, Includes the following steps: S1. Provide a privacy film (1), the privacy film (1) comprising a transmissive layer (12) and an absorbent layer (13) with different coefficients of thermal expansion; S2. The privacy film (1) is continuously heated, causing the transmissive layer (12) and the absorbent layer (13) to deform and cause interface separation; S3. Observe and measure the physical parameters of the transmission layer (12) and the absorption layer (13).

2. The method for structural analysis of privacy films according to claim 1, characterized in that, The transmissive layer (12) is formed by curing a light-transmitting adhesive, which comprises the following components by weight fraction:

3. The method for structural analysis of privacy films according to claim 1, characterized in that, The absorbent layer (13) is cured and formed from a filler adhesive, which comprises the following components by weight fraction:

4. The method for structural analysis of privacy films according to claim 1, characterized in that, The privacy film (1) also includes a substrate layer (11); The transmission layer (12) is disposed on the substrate layer (11), and the transmission layer (12) has multiple microstructures and grooves (121) are formed between adjacent microstructures; The absorption layer (13) is disposed in the groove (121).

5. The method for structural analysis of privacy films according to claim 4, characterized in that, The absorption layer (13) extends upward and forms a planar layer (131) covering the transmission layer (12); The thickness of the planar layer (131) is less than or equal to 1 μm.

6. The method for structural analysis of privacy films according to claim 1, characterized in that, The height of the privacy film is 10-200 μm.

7. The method for structural analysis of privacy films according to claim 1, characterized in that, In step S2, the heating temperature of the privacy film (1) is 200-300℃.

8. The method for structural analysis of privacy films according to claim 1, characterized in that, In step S2, the heating time of the privacy film (1) is 72-168h.

9. The method for structural analysis of the privacy film according to claim 1 or 5, characterized in that, In step S2, before heating the privacy film (1), an OCA adhesive layer (2) can be applied to its surface.

10. The method for structural analysis of the privacy film according to claim 9, characterized in that, The thickness of the OCA adhesive layer (2) is 20-200 μm.

11. The method for structural analysis of privacy films according to claim 9, characterized in that, The privacy film (1) is heated to a temperature of 200-250℃.

12. The method for structural analysis of privacy films according to claim 9, characterized in that, The privacy film (1) is heated for 5-48 hours.

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