A kind of anti-ultraviolet matte polyester film and preparation method

Abstract

The present invention discloses an anti-UV matte polyester film, comprising: a polyester film serving as an intermediate layer; a matte surface layer disposed on at least one surface of the polyester film; the matte surface layer comprising first matte particles and second matte particles, wherein the first matte particles are silica modified with a silane coupling agent and grafted with an organic anti-UV agent, and the second matte particles are silica modified with an isocyanate-terminated polyurethane and grafted with an organic anti-UV agent, wherein the organic anti-UV agent has a hydroxyl group. The anti-UV matte polyester film has a reasonable structure, and the first matte particles and the second matte particles are compounded to enhance the matte effect of the polyester film while ensuring mechanical properties in a small amount. The modification by combining the isocyanate-terminated polyurethane and the silane coupling agent not only improves the dispersibility of the particles, but also enhances the anti-UV performance and anti-UV stability by grafting the organic anti-UV agent, thereby optimizing the mechanical properties of the matte polyester film.

Description

Technical Field

[0001] The present invention relates to the technical field of film production, in particular to an anti-ultraviolet matte polyester film and a preparation method thereof. Background Art

[0002] With the change of consumption concepts, people have begun to be interested in low-gloss matte films. The special hazy appearance brought by matte films is more attractive to consumers.

[0003] Polyester film has anti-ultraviolet properties. Common methods include surface coating technology and blending modification. However, the addition of organic UV absorbers has disadvantages such as migration and irritation to human skin. The addition of inorganic UV absorbers has the problem of poor dispersion. Inorganic UV absorbers such as TiO2 and ZnO are expensive. Reducing the amount added will not achieve the anti-ultraviolet effect and shorten the duration of anti-ultraviolet effect.

[0004] Therefore, it is necessary to improve the UV-resistant matte polyester film in the prior art. Summary of the Invention

[0005] One of the purposes of the present invention is to overcome the defects existing in the prior art and provide an anti-UV matte polyester film. The first matte particles and the second matte particles are compounded to improve the matte effect of the polyester film in a small amount and ensure the mechanical properties. The modification is carried out by combining isocyanate-terminated polyurethane and silane coupling agent, which not only improves the dispersibility of the particles, but also improves the anti-UV performance and anti-UV stability by grafting an organic anti-UV agent, and optimizes the mechanical properties of the matte polyester film.

[0006] To achieve the above technical effects, the technical solution of the present invention is: an anti-ultraviolet matte polyester film, which is a co-extruded film, comprising:

[0007] Polyester film, as the middle layer;

[0008] A matte surface layer is provided on at least one surface of the polyester film;

[0009] The matte surface layer includes first matte particles and second matte particles, the first matte particles are silica modified by a silane coupling agent and grafted with an organic anti-UV agent, the second matte particles are silica modified by an isocyanate-terminated polyurethane and grafted with an organic anti-UV agent, and the organic anti-UV agent has a hydroxyl group.

[0010] A preferred technical solution is that the organic anti-ultraviolet agent is a benzophenone and a benzotriazole, the benzophenone is one or more of 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-n-octyloxybenzophenone, 2,2',4-trihydroxybenzophenone, and 4-hydroxybenzophenone; the benzotriazole is one or more of 2-(2'-hydroxy-5'-methylphenyl)benzotriazole, 2-(2'-hydroxy-3',5'-di-tert-butylphenyl)-5-chlorobenzotriazole, 2-(2'-hydroxy-3'-tert-butyl-5'-methylphenyl)-5-chlorobenzotriazole, and 2-(2'-hydroxy-3',5'-di-tert-amylphenyl)benzotriazole.

[0011] A preferred technical solution is that the silane coupling agent is 3-chloropropyltrimethoxysilane.

[0012] A preferred technical solution is that the isocyanate-terminated polyurethane is prepared by catalytic polymerization of isophorone diisocyanate and polyether diol, and the molecular weight of the polyether diol is 1000~1600; further, the molar ratio of isophorone diisocyanate to polyether diol is (2~2.3)~1.

[0013] A preferred technical solution is that the particle size of one of the first matte particles and the second matte particles is 300-500 nm, and the particle size of the other is 1-2 μm.

[0014] A preferred technical solution is that the mass ratio of the first matte particles to the second matte particles is 1:(1-3).

[0015] A preferred technical solution is that the total mass of the first matte particles and the second matte particles is 2% to 8% of the total mass of the matte surface layer.

[0016] A preferred technical solution is that the thickness of one of the matte surface layers accounts for 5.5% to 8.5% of the total thickness of the co-extruded film, and the total thickness of the co-extruded film is 35 to 135 μm.

[0017] A preferred technical solution is a method for preparing the first matte particles: a hydroxy organic anti-UV agent and a strong base powder are dissolved in an N,N-dimethylformamide solvent, reacted at 50-60°C to obtain a phenolate, a silane coupling agent is added dropwise to the phenolate after removing water from the system, and reacted at 50-60°C, followed by impurity removal and washing to obtain a silane coupling agent modified with an organic anti-UV agent, dissolved in a first solvent of acetone and deionized water, hydrolyzed at 40-50°C, and then silicon dioxide is added, and finally dried;

[0018] The second matte particle preparation method comprises the following steps: dissolving silica in acetone, adding isocyanate-terminated polyurethane and an organic metal tin catalyst, reacting at 40-50° C. to obtain polyurethane-modified silica, washing and filtering the silica, and redispersing the silica in acetone. Then, adding a hydroxy organic anti-ultraviolet agent and an organic metal tin catalyst, reacting the silica, washing the silica, and finally drying the silica.

[0019] A second object of the present invention is to overcome the defects in the prior art and provide a method for preparing an anti-ultraviolet matte polyester film, comprising the following steps:

[0020] S1: configuring first matte particles and second matte particles;

[0021] S2: The matte surface layer, polyester film and matte surface layer are sequentially stacked and co-extruded into a cast sheet, which is then biaxially stretched, heat-set, cooled, drawn, corona-treated and rolled to obtain a matte polyester film;

[0022] The matte surface layer is made by mixing and co-extruding the first matte particles and the second matte particles with polyester;

[0023] The temperature for longitudinal stretching is 70~100℃, the stretching ratio is 3~3.6 times, and the stretching rate is 80~120m / min; the temperature for transverse stretching is 110~125℃, the stretching ratio is 3~3.8 times, and the stretching rate is 80~120m / min; the heat setting temperature is 220~240℃.

[0024] The advantages and beneficial effects of the present invention are:

[0025] The anti-ultraviolet matte polyester film has a reasonable structure. The first matte particles and the second matte particles are compounded to improve the matte effect of the polyester film and ensure the mechanical properties. The modification through the combination of isocyanate-terminated polyurethane and silane coupling agent not only improves the dispersibility of the particles, but also improves the anti-ultraviolet performance and anti-ultraviolet stability by grafting the organic anti-ultraviolet agent, and optimizes the mechanical properties of the matte polyester film. DETAILED DESCRIPTION

[0026] The following examples are only used to illustrate the technical solution of the present invention more clearly, and are not intended to limit the scope of protection of the present invention.

[0027] Isocyanate-terminated polyurethane

[0028] It is prepared by catalytic polymerization of isophorone diisocyanate and polyether diol, and the molecular weight of the polyether diol is 1000~1600; further, the molar ratio of isophorone diisocyanate to polyether diol is (2~2.3)~1.

[0029] Isophorone diisocyanate (IPDI) possesses two different types of -NCO groups with varying reactivity, allowing for controlled reaction conditions. Polyether diols selectively react with -NCO groups at primary aliphatic positions to form -NCO-terminated polyurethanes, also known as polyether-based polyurethanes. The choice of polyether diols results in linear polyurethanes, reducing steric hindrance and allowing for greater grafting onto the silica surface. The resulting polyether-based polyurethanes exhibit better hydrolytic stability than polyester-based polyurethanes, making them more stable and less susceptible to degradation in humid environments or when exposed to water. Polyether-based polyurethanes typically have a lower glass transition temperature (Tg), allowing them to maintain good flexibility and elasticity even at low temperatures. They also offer excellent tensile strength, tear strength, and abrasion resistance.

[0030] Preparation of first matte particles and second matte particles

[0031] Preparation method 1: 10g of hydroxy organic anti-UV agent and 3g of NaOH powder are dissolved in 100ml of N,N-dimethylformamide solvent, and reacted at 55°C to obtain phenol salt. After removing the system water, 10g of 3-chloropropyltrimethoxysilane is added dropwise to the phenol salt to react at 60°C, and then the impurities are removed and washed to obtain an organic anti-UV agent-modified silane coupling agent. 5g of the organic anti-UV agent-modified silane coupling agent is taken and dissolved in 50ml of a first solvent mixed with acetone and deionized water in a mass ratio of 10:1. After hydrolysis at 48°C, 5g of silica is added, and finally dried in a vacuum oven at 100°C.

[0032] Preparation method 2: Take 5g of silica and dissolve it in 60ml of acetone, add 20g of isocyanate-terminated polyurethane and 150mg of organic metal tin catalyst, react at 45°C to obtain polyurethane-modified silica, wash and filter, and redisperse it in 40ml of acetone, then add 5g of hydroxy organic anti-ultraviolet agent and 150mg of organic metal tin catalyst, react at 45°C, then wash and finally dry.

[0033] Organic UV inhibitors

[0034] Benzophenones have strong ultraviolet absorption capabilities, especially in the UVB region (290~320 nm).

[0035] Benzotriazoles protect against UVA radiation (320-400 nm) and parts of the UVB region (290-320 nm), offer excellent color stability, and are less likely to cause yellowing. They are also compatible with a variety of polymers and exhibit high thermal stability. They can be combined with benzophenone-based organic UV inhibitors to optimize UV ​​resistance and reduce costs.

[0036] The examples use 4-hydroxybenzophenone, a highly effective UV absorber that provides excellent light stability and is relatively inexpensive compared to other UV absorbers. The 2-(2'-hydroxy-5'-methylphenyl)benzotriazole used is a widely used, highly effective UV absorber with excellent absorption across the UVA and partial UVB regions.

[0037] Example 1

[0038] The anti-UV matte polyester film is a co-extruded film comprising a polyester film and a matte surface layer, wherein the polyester film is an intermediate layer and the matte surface layer is disposed on both surfaces of the polyester film; the matte surface layer comprises first matte particles and second matte particles, wherein the first matte particles are obtained by preparation method one, and the hydroxy organic anti-UV agent is 4-hydroxybenzophenone; the second matte particles are obtained by preparation method two, and the hydroxy organic anti-UV agent is 2-(2'-hydroxy-5'-methylphenyl)benzotriazole. The particle size of the first matte particles is 350nm, the particle size of the second matte particles is 1.5μm, and the mass ratio of the first matte particles to the second matte particles is 1:2. The matte surface layer also includes FG600 polyester, and the mass ratio of the total mass of the first matte particles and the second matte particles to the polyester is 6:94.

[0039] The preparation method of the UV-resistant matte polyester film comprises the following steps:

[0040] S1: preparing first matte particles and second matte particles;

[0041] S2: A matte surface layer, a polyester film and a matte surface layer are co-extruded and cast in a stacked manner. The polyester film is 100% FG600 polyester. After biaxial stretching, the matte polyester film is heat-set, cooled, pulled, corona-treated and rolled up. The longitudinal stretching temperature is 80°C, the stretching ratio is 3.5 times, and the stretching rate is 100 m / min; the transverse stretching temperature is 120°C, the stretching ratio is 3.6 times, and the stretching rate is 105 m / min; and the heat-setting temperature is 225°C.

[0042] The total film thickness of the matte polyester film was 100 μm, and the thickness of the matte surface layer was 7 μm.

[0043] Example 2

[0044] Example 2 is based on Example 1, except that the first matte particles are obtained by Preparation Method 1, and the hydroxyl organic anti-UV agent is 4-hydroxybenzophenone; the second matte particles are obtained by Preparation Method 2, and the hydroxyl organic anti-UV agent is 2-(2'-hydroxy-5'-methylphenyl)benzotriazole. The particle size of the first matte particles is 1.5 μm, and the particle size of the second matte particles is 350 nm. The mass ratio of the first matte particles to the second matte particles is 1:2.

[0045] Example 3

[0046] Example 3 is based on Example 2, except that the mass ratio of the first matte particles to the second matte particles is 1:1, and the other parameters remain unchanged.

[0047] Example 4

[0048] Example 4 is based on Example 2, except that the mass ratio of the first matte particles to the second matte particles is 1:3, and the other parameters remain unchanged.

[0049] Example 5

[0050] Example 5 is based on Example 2, except that the mass ratio of the total mass of the first matte particles and the second matte particles to the mass of the polyester is 2:98, and the other parts remain unchanged.

[0051] Example 6

[0052] Example 6 is based on Example 2, except that the mass ratio of the total mass of the first matte particles and the second matte particles to the mass of the polyester is 12:90, and the other parts remain unchanged.

[0053] Example 7

[0054] Example 7 is based on Example 2, except that the particle sizes of the first matte particles and the second matte particles are both 1.5 μm, and the other parameters remain unchanged.

[0055] Example 8

[0056] Example 8 is based on Example 2, except that the particle sizes of the first matte particles and the second matte particles are both 350 nm, and the other parameters remain unchanged.

[0057] Comparative Example 1

[0058] Comparative Example 1 is based on Example 2, except that the first matte particles are only modified with a silane coupling agent, and the other properties remain unchanged.

[0059] Comparative Example 2

[0060] Comparative Example 2 is based on Example 2, except that the second matte particles are only modified with a silane coupling agent, and the other properties remain unchanged.

[0061] Comparative Example 3

[0062] Comparative Example 3 is based on Example 2, except that the first matte particles and the second matte particles are not modified, and the other properties remain unchanged.

[0063] Comparative Example 4

[0064] Comparative Example 4 is based on Example 2, except that the matte surface layer only contains the first matte particles, and the other parts remain unchanged.

[0065] Comparative Example 5

[0066] Comparative Example 5 is based on Example 2, except that the matte surface layer only contains the second matte particles, and the other parts remain unchanged.

[0067] Comparative Example 6

[0068] Comparative Example 6 is based on Example 1, except that the second matte particles are directly modified and grafted with an organic anti-UV agent by using isophorone diisocyanate, and are not polymerized with polyether diol.

[0069] Performance testing:

[0070] 1. Haze and transmittance test: AT-4725 transmission haze meter from BYK, Germany;

[0071] 2. Tensile strength and elongation at break test: according to ASTM D882;

[0072] 3. UV stability test: According to the standard IEC61215-2005, the UV radiation with a wavelength of 280nm~385nm is 50kWh·m -2 The elongation at break retention rate of matte polyester film after UV irradiation is the ratio of the elongation at break after UV irradiation to the elongation at break of the unirradiated sample multiplied by 100%.

[0073] The test results of the embodiments and comparative examples are shown in the following table:

[0074]

[0075] To achieve a matte effect, the haze should be ≥55%.

[0076] Compared with Example 2, when other conditions remain unchanged, the content of 1.5 μm particles in Example 1 is greater than that of 350 nm particles, and the matte effect is better, but the mechanical properties are reduced.

[0077] Compared with Example 2, in Example 3, while the total mass of the first matte particles and the second matte particles remains unchanged, the content ratio of the 1.5 μm particles increases, which improves the matte effect. At the same time, the content of the polyurethane modified by the second matte particles (350 nm) decreases, resulting in a decrease in mechanical properties.

[0078] Compared with Example 2, in Example 4, the content ratio of 350nm particles increases while the total mass of the first matte particles and the second matte particles remains unchanged, and the matte effect decreases. As the content of polyurethane modified by the second matte particles (350nm) increases, the mechanical properties are improved, and the benzotriazole anti-UV agent is increased, which also improves the anti-UV performance.

[0079] Compared with Example 2, in Example 5, the total mass of the first matte particles and the second matte particles is reduced, and both the matte effect and the anti-ultraviolet effect are reduced.

[0080] Compared with Example 2, in Comparative Example 1, the first matte particles were not modified with an organic anti-ultraviolet agent, and the anti-ultraviolet performance was reduced.

[0081] Compared with Example 2, in Comparative Example 2, the second matte particles were not modified by the isocyanate-terminated polyurethane-modified grafted organic anti-UV agent, and both the mechanical properties and the anti-UV properties were reduced.

[0082] Compared with Example 2, in Comparative Example 3, the first matte particles and the second matte particles are unevenly dispersed, which increases the processing difficulty.

[0083] Compared with Example 2, in Comparative Example 6, the second matte particles are directly modified and grafted with an organic anti-UV agent via isophorone diisocyanate, which has a negative effect on the mechanical properties of the film.

[0084] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A UV-resistant matte polyester film, which is a co-extruded film, comprising: Polyester base film, which is the middle layer; A matte surface layer is provided on at least one surface of the polyester base film and is made by extruding a mixture of first matte particles and second matte particles with polyester; Characterized in that the first matte particles are silica modified by a silane coupling agent and grafted with an organic anti-UV agent, and the second matte particles are silica modified by an isocyanate-terminated polyurethane and grafted with an organic anti-UV agent; The organic anti-ultraviolet agent is benzophenone and benzotriazole, the benzophenone is one or more of 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-n-octyloxybenzophenone, 2,2',4-trihydroxybenzophenone, and 4-hydroxybenzophenone; the benzotriazole is one or more of 2-(2'-hydroxy-5'-methylphenyl)benzotriazole, 2-(2'-hydroxy-3',5'-di-tert-butylphenyl)-5-chlorobenzotriazole, 2-(2'-hydroxy-3'-tert-butyl-5'-methylphenyl)-5-chlorobenzotriazole, and 2-(2'-hydroxy-3',5'-di-tert-amylphenyl)benzotriazole; The silane coupling agent is 3-chloropropyltrimethoxysilane; The isocyanate-terminated polyurethane is prepared by catalytic polymerization of isophorone diisocyanate and polyether diol, and the molecular weight of the polyether diol is 1000-1600; One of the first matte particles and the second matte particles has a particle size of 300-500 nm, and the other has a particle size of 1-2 μm; The mass ratio of the first matte particles to the second matte particles is 1:(1-3); The total mass of the first matte particles and the second matte particles is 2% to 8% of the total mass of the matte surface layer; The first matte particle preparation method comprises the following steps: dissolving an organic anti-ultraviolet agent and sodium hydroxide powder in an N,N-dimethylformamide solvent, reacting at 50-60° C. to obtain a phenolate, removing water from the system, and then dropwise adding a silane coupling agent to the phenolate, reacting at 50-60° C., then removing impurities and washing to obtain a silane coupling agent modified with an organic anti-ultraviolet agent, dissolving the silane coupling agent in a first solvent of acetone and deionized water, hydrolyzing the silane coupling agent at 40-50° C., adding silicon dioxide, and finally drying the silane coupling agent. The second matte particle preparation method comprises the following steps: dissolving silica in acetone, adding isocyanate-terminated polyurethane and an organic metal tin catalyst, reacting at 40-50° C. to obtain polyurethane-modified silica, washing and filtering the silica, and redispersing the silica in acetone. Then, adding an organic anti-ultraviolet agent and an organic metal tin catalyst, reacting the silica, washing the silica, and finally drying the silica.

2. The UV-resistant matte polyester film according to claim 1, characterized in that: The thickness of one of the matte surface layers accounts for 5.5% to 8.5% of the total thickness of the co-extruded film, and the total thickness of the co-extruded film is 35 to 135 μm.

3. A method for preparing the UV-resistant matte polyester film according to any one of claims 1 to 2, characterized in that: The following steps are involved: S1: configuring first matte particles and second matte particles; S2: The matte surface layer, polyester base film and matte surface layer are sequentially stacked and co-extruded into a cast sheet, which is then subjected to biaxial stretching, heat setting, cooling, pulling, corona treatment and winding to obtain a matte polyester film; The temperature for longitudinal stretching is 70~100℃, the stretching ratio is 3~3.6 times, and the stretching rate is 80~120m / min; the temperature for transverse stretching is 110~125℃, the stretching ratio is 3~3.8 times, and the stretching rate is 80~120m / min; the heat setting temperature is 220~240℃.

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