CN110927846A

CN110927846A - Reflective film and method for producing same

Info

Publication number: CN110927846A
Application number: CN201911314278.5A
Authority: CN
Inventors: 金亚东; 杨承翰; 刘海波; 朱正平
Original assignee: Ningbo Solartron Technology Co Ltd
Current assignee: Ningbo Solartron Technology Co Ltd
Priority date: 2019-12-19
Filing date: 2019-12-19
Publication date: 2020-03-27
Anticipated expiration: 2039-12-19
Also published as: CN110927846B

Abstract

The invention relates to a reflecting film which has an ABC three-layer structure, wherein a layer A is a first supporting layer, a layer B is a reflecting layer, a layer C is a second supporting layer, the first supporting layer is made of antistatic agents, first polyester resin and first inorganic particles, the surface resistivity of the reflecting film is less than or equal to 10¹²Omega/□. The invention also provides a preparation method of the reflecting film.

Description

Reflective film and method for producing same

Technical Field

The invention relates to the field of film materials, in particular to a reflecting film and a preparation method thereof.

Background

The backlight module is one of the key components of a liquid crystal display (LCD panel), and since the liquid crystal itself does not emit light, the backlight module functions to provide a sufficient light source with uniform brightness and distribution, so that it can normally display images. The backlight module is mainly assembled by components such as a light source, a lampshade, a reflecting film, a light guide plate, a diffusion plate, a brightness enhancement film, an outer frame and the like.

At present, polyester reflecting films have poor conductivity, are easy to generate static electricity, and have dust or other foreign matters adsorbed on the surfaces. On the other hand, in order to achieve excellent light uniformity, the surface of the reflective film is required to be extremely smooth, and the final display is adversely affected by very small foreign particles adsorbed by static electricity. Therefore, an antistatic layer is formed on the surface of the reflective film by coating an antistatic agent, but the antistatic layer changes the surface structure of the reflective film, resulting in poor light uniformity of the reflective film. In addition, the manufacturing cost is high due to the increase of the coating production process.

Disclosure of Invention

In view of the above, the present invention provides a reflective film having antistatic properties.

The reflecting film has an ABC three-layer structure, wherein the layer A is a first supporting layer, the layer B is a reflecting layer, the layer C is a second supporting layer, the first supporting layer is made of antistatic agents, first polyester resin and first inorganic particles, and the surface resistivity of the reflecting film is less than or equal to 10¹²Ω/□。

Compared with the prior art, the reflecting film comprises a first supporting layer, and the antistatic agent is introduced into the first supporting layer, so that the surface resistivity of the reflecting film is less than or equal to 10¹²Omega/□. Therefore, the reflecting film has excellent antistatic property, does not affect the surface structure, namely the surface of the reflecting film is smooth, and has both antistatic property and light-homogenizing property.

The invention also provides a preparation method of the reflecting film, which comprises the following steps: respectively providing a first mixture and a second mixture;

adding the first mixture and the second mixture into an extruder, and obtaining a prefabricated film with a three-layer structure by a three-layer co-extrusion method, wherein the material of a reflecting layer positioned in the middle of the prefabricated film is the second mixture, and the material of supporting layers positioned at the upper layer and the lower layer is the first mixture, wherein the first mixture comprises a first polyester resin, first inorganic particles and an antistatic agent; and

and stretching and shaping to obtain the reflecting film.

The preparation method is simple to operate and easy to industrialize.

Drawings

FIG. 1 is a schematic structural diagram of a reflective film according to the present invention.

In the figure, 11 denotes a reflective layer; 12 denotes a first support layer; 13 denotes a second support layer; 111 denotes an incompatible resin; 112 denotes cells; 113 denotes second inorganic particles; and 121 denotes first inorganic particles.

Detailed Description

The technical solutions in the embodiments of the present invention will be described clearly and completely below, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, not all of the embodiments. All other embodiments, which can be obtained by a person skilled in the art without inventive step based on the embodiments of the present invention, are within the scope of the present invention.

Referring to fig. 1, the present invention provides a reflective film, which includes an ABC three-layer structure, wherein a layer is a first support layer 12, a layer B is a reflective layer 11, and a layer C is a second support layer. The material of the first supporting layer comprises an antistatic agent, first polyester resin and first inorganic particles, and the surface resistivity of the reflecting film is less than or equal to 10¹²Omega/□. Therefore, compared with the prior art that the antistatic effect is realized by coating antistatic particles on the surface of the reflecting film at the later stage, the reflecting film does not need a coating process, has a simple preparation flow, can ensure high surface gloss, has excellent light uniformity, and is not easy to adsorb dust and the like on the surface during use due to the introduction of the antistatic agent in the first supporting layer. Specifically, the 60-degree glossiness of the reflecting film is more than or equal to 90%.

The line roughness Ra of the surface of the first supporting layer 12 is less than or equal to 0.1 mu m. Preferably, the surface of the first support layer 12 has a line roughness Ra of 0.07 μm or less. Of course, specifically, the difference in gloss between the surface of the first supporting layer 12 and the surface of the second supporting layer 13 is not greater than 30%, so that both the front and back sides of the reflective film can be used, and in actual operation, no distinction is needed. Of course, the material of the second support layer 13 may be the same as that of the first support layer 12, or the ratio of the raw material components of the two support layers or the process may be slightly adjusted during the preparation.

The material of the first support layer 12 includes a first polyester resin, first inorganic particles 121, and an antistatic agent. The first polyester resin includes at least one of polyethylene terephthalate (PET), polybutylene terephthalate, and polyethylene naphthalate. Preferably, the first polyester resin is polyethylene terephthalate. The first inorganic particles 121 include at least one of calcium carbonate, silica, titanium dioxide, and barium sulfate. The particle size of the first inorganic particles 121 is not limited. Preferably, the first inorganic particles 121 are silica, and the particle size of the first inorganic particles 121 is not more than 3 μm. The antistatic agent imparts antistatic properties to the reflective film. The antistatic agent is at least one of an anionic antistatic agent, a nonionic antistatic agent, a zwitterionic antistatic agent and a high-molecular antistatic agent. The anionic antistatic agent specifically comprises one of alkyl sulfonate, alkyl sulfate and alkyl phosphate, the nonionic antistatic agent specifically comprises one of fatty acid polyol ester and alkanolamine, the zwitterionic antistatic agent specifically comprises alkyl imidazoline salt, and the high-molecular antistatic agent specifically comprises polyether ester amide. Preferably, the antistatic agent is an alkyl sulfonate.

The first polyester resin accounts for 96.9-98.9% of the first support layer 12 by mass. The first inorganic particles 121 account for 1 to 3 mass%. The antistatic agent accounts for 0.1-1% of the mass fraction. The reason for the selection is: in order to ensure more excellent antistatic effect, the mass fraction of the antistatic agent is not less than 0.1%. And the mass fraction of the antistatic agent is not more than 1% in consideration of the fact that the addition amount is too high, the antistatic effect of the film surface is rather lowered and the manufacturing cost is increased. Preferably, the first polyester resin accounts for 96.9 to 97.9 mass percent of the first supporting layer 12/13; the first inorganic particles 121 account for 1 to 3 mass percent; the antistatic agent accounts for 0.5-0.7% of the mass fraction.

A plurality of uniform cells 112 are distributed in the reflective layer 11. The material of the reflective layer 11 includes a second polyester resin, second inorganic particles, and an incompatible resin. The second polyester resin comprises at least one of polyethylene terephthalate and polybutylene terephthalate.

The incompatible resin means a resin incompatible with the second polyester resin, including polyolefin-based resins. Since the incompatible resin is incompatible with the second polyester resin, voids can be generated around the incompatible resin during the stretching process, thereby forming the cells 112 in the reflective layer 11. At this time, the incompatible resin 111 may be considered to be located substantially at the center of the cells 112. In order to facilitate the formation of the cells 112, the incompatible resin 111 is preferably at least one of polypropylene, polymethylpentene, and cyclic olefin copolymer having a small critical surface tension. The particle size of the incompatible resin 111 is not limited, and is preferably 0.2 to 0.3 μm. The presence of the cells 112 can increase the reflectivity of the reflective film. The pore size of the cells 112 is not limited, and is preferably 0.3 to 5 microns.

The second inorganic particles include at least one of titanium dioxide, barium sulfate, calcium carbonate, and alumina. Preferably, the second inorganic particles are titanium dioxide, because titanium dioxide has good physical and chemical stability, a high refractive index, good shielding properties, and can provide a higher reflectance.

The second polyester resin accounts for 60-80% of the reflecting layer, the incompatible resin accounts for 5-20% of the reflecting layer, and the second inorganic particles account for 5-20% of the reflecting layer. Preferably, the second inorganic particles account for 15% by mass.

The thickness of the reflective film is not limited, and preferably, the thickness of the reflective film is 100 to 300 micrometers.

The invention also provides a preparation method of the reflecting film, which comprises the following steps:

s1, providing a first mixture and a second mixture, respectively;

s2, adding the first mixture and the second mixture into an extruder, and obtaining a prefabricated film with a three-layer structure by a three-layer co-extrusion method, wherein the material of the reflective layer 11 in the middle of the prefabricated film is the second mixture, and the materials of the first support layer 12 and the second support layer 13 in the upper layer and the lower layer are the first mixture; and

and S3, stretching and shaping to obtain the reflecting film, wherein the obtained reflecting film.

In step S1, the first mixture includes a first polyester resin, first inorganic particles, and an antistatic agent. The second mixture includes a second polyester resin, second inorganic particles, and an incompatible resin. The specific components are as described above and will not be described herein. The granulation can be carried out by twin-screw mixing, i.e. the first mixture particles and the second mixture particles are formed. In order to better mix the components, the intrinsic viscosity of the first polyester resin and the intrinsic viscosity of the second polyester resin are 0.65dL/g-0.75 dL/g. Here, the raw material ratio of the first supporting layer 12 and the second supporting layer 13 may be the same or slightly different, as long as the difference of the glossiness of the two final surfaces is less than 30%.

In step S2, a prefabricated film having a three-layer structure may be formed by three-layer coextrusion, melt plasticizing, and casting of a cast sheet.

In step S3, the prefabricated film is longitudinally stretched, transversely stretched, and heat-set to obtain the reflective film. Wherein, in the stretching process, the longitudinal stretching ratio and the transverse stretching ratio are controlled to be between 3.0 and 3.60. Preferably, the longitudinal stretching ratio and the transverse stretching ratio are controlled to be 3.3. And finally, rolling and packaging the reflecting film.

The reflective film and the method for producing the reflective film according to the present invention will be described below with reference to examples.

Example 1

A reflective film has an ABA three-layer structure, i.e., a first support layer and a second support layer are the same in structure and collectively referred to as a support layer (A layer). The B layer is a reflecting layer. The support layer comprises 97.9% of PET resin, 2% of silica particles and 0.1% of antistatic agent. The reflective layer comprises 70% PET resin (intrinsic viscosity 0.68dL/g), 15% polymethylpentene, 15% titanium dioxide. The thickness of the resulting reflective film was 188 μm, with the thickness of both support layers accounting for 18% of the total thickness and the thickness of the reflective layer accounting for 82% of the total thickness.

Example 2 example 22

The raw materials and the proportions of the respective layers of the reflective film of each example are shown in tables 1 and 2, and the reflective layer is the same as in example 1.

To better illustrate the beneficial effects of the reflective film of the present invention, the present invention also provides comparative examples 1-3.

Comparative examples 1 to 3

The support layer of the comparative PET reflective film was prepared without introducing an antistatic agent, as shown in table 2, and the reflective layer was the same as in example 1.

The following performance tests were performed on the reflective films of examples 1 to 22 and comparative example 1.

And (3) reflectivity testing: according to the GB/T3979-2008 standard, the reflectivity is tested by an integrating sphere D/8 DEG structure under the condition of a D65 light source by adopting a ColorQuest XE spectrocolorimeter (manufactured by Hunterlab corporation), the reflectivity data is 400nm-700nm, and the reflectivity value of 550nm wavelength is taken at intervals of 10nm wavelength.

60 ° gloss test: the surface gloss of the reflecting film is measured by adopting a Switzerland ZGM1020 portable gloss meter, the reflecting film is cut into strips of 5cm multiplied by 15cm after being calibrated, a sample is placed into the strips to be cut, the gloss of the front side and the back side is measured, the gloss data is read, and the average value of the gloss of the two sides is taken as the final gloss value.

And (3) roughness Ra test, namely placing the sample on a smooth marble table or a smooth glass plane by adopting a SURFTEST SJ.210 type surface roughness tester, and measuring the Ra value according to GB-T1031-2009 standard.

And (3) surface resistance testing: adopting a Japanese SIMCO ST-4 surface impedance tester, and meeting the sampling requirement: the sample is required to be flat, and has no wrinkle, no scar and no dust on the surface; testing environment requirements: the temperature is 15-25 ℃, and the humidity is below 60% R.H; during testing, an object to be tested needs to be placed on the desktop made of the insulating material.

The test results are shown in Table 2.

Table 1 raw material table

Code of raw materials	Name of raw materials	Code of raw materials	Name of raw materials
				A	Polyethylene terephthalate	G	Polyol esters of fatty acids
B	Polybutylene terephthalate	H	Alkanolamine
				C	Polyethylene naphthalate	I	Alkyl imidazoline salts
D	Alkyl sulfonates	J	Polyether ester amides
				E	Alkyl sulfates
F	Alkyl phosphates

TABLE 2 tables of addition ratios of raw materials and performances of examples 1 to 20 and comparative examples 1 to 3 of reflection films

As can be seen from table 2, in comparative examples 1 to 3, it was found that example 2 is the most effective and the addition amount of the first inorganic particles is preferably 2% in the actual assembly of the backlight; comparative examples 6 to 12, the antistatic agent is preferably an alkylsulfonate; in comparative examples 3 to 7, the reflecting film obtained was excellent in antistatic property, and the antistatic agent was preferably contained in a proportion of 0.5% to 0.7%. Comparative examples 18 to 22, examples 20 to 22 are preferred in view of obtaining a reflective film having high gloss (gloss of 90% or more), and the gloss range is preferred: the glossiness is more than 135 and more than or equal to 110, namely the roughness is more than 0.01 mu m and less than or equal to 0.05 mu m, the comprehensive performance is better, and the example 21 is the most excellent.

From the above data comparison shown in Table 2, it can be seen that the preferred embodiment 6, the preferred embodiment 16 and the preferred embodiment 21 have the best overall performance among the three thicknesses of 188 μm, 225 μm and 250 μm, respectively. Preferred proportions, preferred types of antistatic agents, and the most preferred embodiment that does not reduce the reflectance per se and satisfies the high gloss ball demand. The appropriate thickness is selected according to actual requirements.

Compared with the common reflecting film, the reflecting film provided by the invention has excellent antistatic performance through the improvement of the proportion, can greatly improve the problem that the reflecting film adsorbs foreign matters in the subsequent cutting and assembling processes, and improves the assembling efficiency and yield.

The technical features of the embodiments described above may be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the embodiments described above are not described, but should be considered as being within the scope of the present specification as long as there is no contradiction between the combinations of the technical features.

The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.

Claims

1. The reflective film is characterized by having an ABC three-layer structure, wherein the layer A is a first supporting layer, the layer B is a reflective layer, the layer C is a second supporting layer, the first supporting layer is made of an antistatic agent, first polyester resin and first inorganic particles, and the surface resistivity of the reflective film is less than or equal to 10¹²Ω/□。

2. The reflective film according to claim 1, wherein the first polyester resin comprises at least one of polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate, wherein the first inorganic particles comprise at least one of calcium carbonate, silica, titanium dioxide, and barium sulfate, and wherein the antistatic agent comprises at least one of an anionic antistatic agent, a nonionic antistatic agent, a zwitterionic antistatic agent, and a polymer antistatic agent.

3. The reflective film according to claim 2, wherein the anionic antistatic agent comprises one of alkyl sulfonate, alkyl sulfate and alkyl phosphate, the nonionic antistatic agent comprises one of fatty acid polyol ester and alkanolamine, the zwitterionic antistatic agent comprises alkyl imidazoline salt, and the polymeric antistatic agent comprises polyether ester amide.

4. The reflective film according to claim 1, wherein the first polyester resin accounts for 97 to 97.9 mass%, the first inorganic particles account for 1 to 3 mass%, and the antistatic agent accounts for 0.1 to 1 mass% of the first support layer.

5. The reflective film of claim 1, wherein the material of the reflective layer comprises a second polyester resin, second inorganic particles, and an incompatible resin.

6. The reflective film of claim 5, wherein said second polyester resin comprises at least one of polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, said incompatible resin comprises polyolefin-based resins, and said second inorganic particles comprise at least one of titanium dioxide, barium sulfate, calcium carbonate, and aluminum oxide.

7. The reflective film according to claim 5, wherein the second polyester resin accounts for 60 to 80 mass%, the incompatible resin accounts for 5 to 20 mass%, and the second inorganic particles accounts for 5 to 20 mass% of the reflective layer.

8. The reflection film according to claim 1, wherein a line roughness Ra of the surface of the first support layer is 0.1 μm or less.

9. The reflective film of claim 1, wherein the material of the second support layer is the same as the material of the first support layer.

10. The reflective film of claim 1, wherein the reflective layer comprises a plurality of cells therein.

11. A method for producing a reflective film according to any one of claims 1 to 10, comprising the steps of:

respectively providing a first mixture and a second mixture;

and stretching and shaping to obtain the reflecting film.

12. The method of manufacturing a reflective film according to claim 11, wherein in the step of stretch-setting, a longitudinal and transverse stretch ratio is in a range of 3.0 to 3.6.

13. The method of making a reflective film of claim 11, wherein the second mixture comprises a second polyester resin, second inorganic particles, and an incompatible resin.