Matt polyester film containing porous material and preparation method

Abstract

The present invention discloses a matte polyester film containing a porous material, comprising: a polyester base film, which is a co-extruded film having at least one matte surface layer; a matte coating layer, which is disposed on the surface corresponding to the matte surface layer; modified porous particles uniformly distributed on the matte surface layer, the modified porous particles comprising first particles and second particles, the first particles having a particle size of 200-300 nm, and the second particles having a particle size of 1-2 μm; a matte coating liquid for the matte coating layer comprising a main resin, a thermoplastic resin, a photoinitiator, and a solvent; the thermoplastic resin is a polydimethylsiloxane and styrene copolymer, the molar content of the polydimethylsiloxane in the copolymer being 30%-40%, and the molar mass of the polydimethylsiloxane in the copolymer being 2000-3000 g / mol. The matte polyester film has a good matte effect and excellent mechanical properties, and the thermoplastic resin composed of the polydimethylsiloxane and styrene copolymer further improves the anti-fouling properties of the matte polyester film.

Description

Technical Field

[0001] The present invention relates to the technical field of film production, and in particular to a matte polyester film containing porous materials 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] To achieve a matte film, inorganic additives such as calcium carbonate, magnesium carbonate, silica, talc, kaolin, aluminum oxide, and titanium dioxide are commonly added. The greater the amount of inorganic additives added, the matteness of the resulting film increases, but the gloss loss trend slows. On the other hand, excessive additives can lead to poor dispersion and reduced mechanical strength. Matte films, due to their uneven surface structure, are susceptible to accumulation of dust, grease, water stains, and fingerprints.

[0004] Therefore, it is necessary to improve the 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 a matte polyester film containing a porous material, which has a good matte effect and good mechanical properties, and the anti-fouling performance of the matte polyester film is improved by using a thermoplastic resin composed of polydimethylsiloxane and styrene copolymer.

[0006] In order to achieve the above-mentioned process effects, the technical solution of the present invention is: a matte polyester film containing a porous material, comprising:

[0007] The polyester base film is a co-extruded film having at least one matte surface layer;

[0008] A matte coating layer is provided on a surface corresponding to the matte surface layer;

[0009] The matte surface layer is uniformly distributed with modified porous particles, the modified porous particles include first particles and second particles, the particle size of the first particles is 200 to 300 nm, and the particle size of the second particles is 1 to 2 μm;

[0010] The matte coating liquid of the matte coating includes a main resin, a thermoplastic resin, a photoinitiator and a solvent; the thermoplastic resin is a copolymer of polydimethylsiloxane and styrene, the molar content of polydimethylsiloxane in the copolymer is 30% to 40%, and the molar mass of polydimethylsiloxane in the copolymer is 2000 to 3000 g / mol.

[0011] Furthermore, the molar content of polydimethylsiloxane in the copolymer is 33% to 38%.

[0012] The preferred technical solution is: the mass ratio of the first particles to the second particles is (1-4):1, and the total mass of the first particles and the second particles accounts for 3% to 7% of the total mass of the raw materials in the matte surface layer.

[0013] The preferred technical solution is: the ratio of the thickness of one of the matte surface layers to the total thickness of the polyester base film is 1:(12-18), the total film thickness of the co-extruded film is 35-135 μm; and the layer thickness of the matte coating is 1-4 μm.

[0014] The preferred technical solution is: the main resin is UV-curable polyurethane acrylate.

[0015] The preferred technical solution is: the matte coating liquid of the matte coating comprises, by mass, 10 parts of a main resin, 5 to 12 parts of a thermoplastic resin, 0.4 to 1 part of a photoinitiator and 120 to 300 parts of a solvent.

[0016] The preferred technical solution is: the solvent is toluene and ethyl acetate, and the mass ratio of toluene to ethyl acetate is 1: (0.6-1.2).

[0017] The preferred technical solution is: the preparation method of the thermoplastic resin is as follows: hydroxypropyl di-terminated polydimethylsiloxane is condensed with an azo initiator under the action of a catalyst and an activator to obtain a first chain segment having an initiator, the first chain segment is mixed with a styrene monomer and reacted at 70-80°C, the reactant is precipitated and dried in a vacuum dryer at 35-40°C.

[0018] A second object of the present invention is to overcome the defects in the prior art and provide a method for preparing a matte polyester film containing a porous material, comprising the following steps:

[0019] S1: Preparation of modified porous particles and matte coating solution;

[0020] S2: The first surface layer, the base film, and the second surface layer are sequentially stacked and co-extruded into a sheet, and then biaxially stretched to obtain a polyester base film;

[0021] S3: applying the matte coating liquid on the surface corresponding to the matte surface layer, drying and curing to form a matte polyester film having a matte coating layer;

[0022] The first surface layer and / or the second surface layer is a matte surface layer, and the matte surface layer is a mixture of modified porous particles and a polyester substrate.

[0023] The preferred technical solution is: the modified porous particles in S1 are all silica surface-modified by a coupling agent modification liquid, the coupling agent is KH-550, and the coupling agent modification liquid is configured with a pH value of 4.8 to 6; the temperature is raised to the first stage and the first particles are added to dissolve first, and then the temperature is lowered to the second stage and the second particles are added to dissolve, the temperature of the first stage is 40 to 50°C, and the temperature of the second stage is 25 to 35°C.

[0024] The preferred technical solution is: the continuous drying temperature in S3 is set to 65±5℃, 75±5℃, 80±5℃, 95±5℃, 80±5℃ in sequence; the curing energy is 110~120mJ / cm 2 .

[0025] The advantages and beneficial effects of the present invention are:

[0026] The matte polyester film containing porous material has a matte surface layer with evenly distributed first and second particles compounded with each other, combined with a matte coating to form a concave-convex microstructure through multiphase separation, thereby improving the matte effect of the polyester film while ensuring its mechanical properties. In addition, a thermoplastic resin composed of polydimethylsiloxane and styrene copolymer is used to further improve the anti-fouling performance of the matte polyester film. DETAILED DESCRIPTION

[0027] 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.

[0028] Preparation of thermoplastic resins

[0029] Hydroxypropyl di-terminated polydimethylsiloxane reacts with an azo initiator in the presence of a catalyst and an activator to produce a first segment containing the initiator. The first segment is mixed with styrene monomer in a toluene solvent, with a 20% to 25% reaction mixture maintained at 75-80°C for 7-10 hours. The reactants are then precipitated and dried in a vacuum desiccator at 35-40°C. The azo initiator is 4,4'-azo-(4-cyanovaleric acid), the catalysts are 4-dimethylaminopyridine and p-toluenesulfonic acid, and the activator is dicyclohexylcarbodiimide. This reaction system is highly efficient and produces few byproducts. The formation of the first segment reduces the mobility of the azo initiator, promoting the polymerization of the styrene monomer to produce a copolymer of polydimethylsiloxane (PDMS) and styrene (St).

[0030] Preparation of modified porous particles

[0031] Modified porous particles are all silica that has been surface-modified using a coupling agent modification liquid. The coupling agent is KH-550, which contains amino functional groups that can form hydrogen bonds or chemical bonds with carboxyl or hydroxyl groups in PET, thereby enhancing the bonding between the inorganic filler and the polymer matrix, improving the dispersibility of silica in PET, and helping to improve the mechanical properties of the composite material. Silica is composed of a three-dimensional network structure formed by the accumulation of silicon-oxygen tetrahedrons. This porous structure gives it a large specific surface area, resulting in a larger surface energy and more active sites. The surface is rich in silanol groups (Si-OH), making it easy to modify. It is highly chemically inert and does not easily react with other substances. By varying its preparation method, size, and distribution on the surface of the polyester film, it can effectively scatter light, reduce surface gloss, and produce a matte effect. The coupling agent-modified solution is prepared to a pH of 4.8-6 using ethanol and water as solvents. Furthermore, the mass ratio of ethanol, water, and coupling agent is 1:5:(0.5-0.7). The temperature is raised to the first stage, where the first particles are added and dissolved, and then the temperature is lowered to the second stage where the second particles are added and dissolved. The first stage hydrolysis lasts for 2 hours at a stirring speed of 3000 rpm, while the second stage lasts for 1.5 hours at a stirring speed of 3500 rpm. The coupling agent-surface-modified silica is then dried at a temperature of 100-110°C.

[0032] Since the first particles have a small particle size and a large specific surface area and are prone to agglomeration, the temperature in the first stage is controlled at 40-50°C to reduce the viscosity of the modification liquid and fully hydrolyze the coupling agent, which is beneficial to the dispersion of the first particles and prevents the temperature from being too high, causing the coupling agent to condense after hydrolysis and poor modification. The temperature in the second stage is controlled at 25-35°C to obtain a stable coupling agent hydrolysis solution system and prevent the hydrolyzed coupling agent from self-aggregating, which is not conducive to grafting on the surface of the second particles.

[0033] Matte coating liquid

[0034] It includes a main agent resin, a thermoplastic resin, a photoinitiator and a solvent.

[0035] In matte coatings formulated with a thermoplastic resin and a base resin, the solvent evaporates upon heating, forming a concave-convex microstructure on the polyester film surface after curing, reducing gloss and creating a matte effect. Excessive base resin addition, accompanied by solvent evaporation, leads to phase separation between the base resin and thermoplastic resin, and between the polydimethylsiloxane and styrene copolymer, hindering the formation of the concave-convex microstructure and resulting in a poor matte effect. Excessive base resin addition reduces the mechanical properties and wear resistance of the matte polyester film.

[0036] The photoinitiator was PI 184.

[0037] A matte coating liquid formulated with a solvent combination of toluene and ethyl acetate exhibits excellent leveling properties, allowing it to be applied evenly over matte surfaces with a concave-convex microstructure. Furthermore, the solvent combination exhibits excellent compatibility with polydimethylsiloxane and styrene copolymers. Adjusting the boiling point of the solvent mixture reveals that, during evaporation, the solubility parameters of the polydimethylsiloxane and styrene phases differ. The closer the solubility parameters of the two phases in the solvent, the less readily they evaporate. A larger disparity in solubility leads to less solubility and the formation of surface bumps. Therefore, the combined solvents regulate the bump height and distribution of the concave-convex microstructure of the thermoplastic resin phases, reducing gloss and creating a matte effect. The molar ratio of polydimethylsiloxane to styrene further modulates the bump height and distribution of the concave-convex microstructure.

[0038] The composition and layer thickness of the polyester base film are shown in Table 1 below:

[0039]

[0040]

[0041] In Table 1, the first and second surface layers (A) of the Examples and Comparative Examples are matte finishes. M1 / M2 represents the mass ratio of the first and second particles, respectively; (M1+M2) / M*100 represents the mass fraction of the total mass of the first and second particles relative to the total mass of the raw materials in the matte finish; and the layer thickness ratio A / B / A represents the thickness ratio of the first surface layer (A), base film (B), and second surface layer (A). The total thickness of the polyester base film is 100 μm. A value of 0 for either M1 or M2 indicates that no particles are added; a value of 0 for both indicates that no particles are added.

[0042] The composition of the matte coating liquid is shown in Table 2 below by mass:

[0043]

[0044]

[0045] The preparation method of the matte polyester film containing porous material comprises the following steps:

[0046] S1: Preparation of modified porous particles and matte coating solution;

[0047] The first particles and the second particles were prepared according to Table 1 and surface modified by the above method. The modified porous particles were all silica surface-modified by a coupling agent modification liquid. The coupling agent was KH-550 and the pH value of the coupling agent modification liquid was 4.8-6. The temperature was raised to 48° C. in the first stage and the first particles were added to dissolve first. The temperature was then lowered to 28° C. in the second stage and the second particles were added to dissolve.

[0048] The composition of the matte coating liquid was prepared according to Table 2.

[0049] S2: The modified porous particles are mixed with the polyester substrate and co-extruded, and the first surface layer, the base film, and the second surface layer are sequentially stacked to form a co-extruded sheet, and then biaxially stretched to obtain a polyester base film;

[0050] The total mass of the first and second particles after drying is adjusted according to Table 1 to the total mass of the raw materials in the matte surface layer, that is, the modified porous particles are mixed and co-extruded with the polyester substrate, and the polyester substrate model of the first surface layer, base film and second surface layer is FG600.

[0051] S3: Matt coating liquid is applied to the surface of the matte surface layer, dried and cured to form a matte polyester film with a matte coating. The continuous drying temperature is set to 65°C, 75°C, 80°C, 95°C, and 80°C in sequence; the curing energy is 115mJ / cm 2 .

[0052] Example 12

[0053] Example 12 is based on Example 1, except that the first particles and the second particles in S1 are not dissolved sequentially but mixed together, and the hydrolysis temperature of the coupling agent modified solution is controlled at 50°C.

[0054] Performance testing:

[0055] Performance testing:

[0056] 1. Haze and transmittance test: AT-4725 transmission haze meter from BYK, Germany;

[0057] 2. Tensile strength and elongation at break test: according to ASTM D882;

[0058] 3. Adhesion test: The adhesion of matte coating on polyester base film is graded from 0 to 4 according to GB / T9286 standard. Grade 0 means no or minimal coating peeling in the scribed area. The higher the grade, the larger the peeling area.

[0059] 4. Antifouling performance test: Use a marker to mark the surface of the matte polyester film, then wipe it with a non-woven cloth and observe the residual mark. A trace amount of residue means the area is less than 1%, a small amount of residue means the area is between 1% and 10%, and a large amount of residue means the area is greater than 10%.

[0060] The test results of the embodiments and comparative examples are shown in Table 3 below:

[0061]

[0062] To achieve a matte effect, the haze should be ≥ 70%.

[0063] Compared with Example 1, in Example 5, as the thickness of the first surface layer (A) and the second surface layer (A) decreases, the roughness of their surfaces increases, which can easily lead to uneven coating of the coating liquid of the matte coating, resulting in a decrease in the average adhesion between the matte surface layer and the matte coating.

[0064] Compared with Example 1, in Example 6, as the thickness of the first surface layer (A) and the second surface layer (A) increases, the first particles and the second particles distributed on the surface layers tend to sink, resulting in reduced adhesion between the matte surface layer and the matte coating.

[0065] Compared with Example 1, Example 7 has an increased content of the first particles and the second particles in the first surface layer (A) and the second surface layer (A), which makes processing difficult and the surface roughness increases, which can easily lead to uneven coating of the coating liquid of the matte coating, resulting in a decrease in the average adhesion between the matte surface layer and the matte coating.

[0066] Compared with Example 1, Example 8 has a negative impact on the matte effect and anti-fouling performance as the content of the polydimethylsiloxane phase in the polydimethylsiloxane and styrene copolymer decreases.

[0067] Compared with Example 1, the thin layer thickness of the matte coating in Example 10 has a negative impact on the anti-fouling performance and reduces the adhesion to the matte surface layer.

[0068] Compared with Example 1, the matte coating layer in Example 11 is too thick, which is not conducive to the separation of the two phases of the agent resin and the thermoplastic resin, as well as the separation of the two phases of polydimethylsiloxane and styrene, and is not easy to form a concave-convex microstructure, which has a negative impact on the matte effect.

[0069] In Example 12, the porous particle modification process is difficult to control, resulting in particle agglomeration.

[0070] Compared with Example 1, the matte surface layer of Comparative Example 3 does not contain modified porous particles, which has a negative impact on the adhesion between the matte surface layer and the matte coating, and the matte effect is reduced.

[0071] Compared with Example 1, in Comparative Example 5, as the content of the polydimethylsiloxane phase in the polydimethylsiloxane and styrene copolymer increases, it is difficult to form a concave-convex microstructure, which has a negative impact on the matte effect.

[0072] 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 matte polyester film containing porous material, characterized in that: include: The polyester base film is a co-extruded film having at least one matte surface layer, wherein the matte surface layer is a mixture of modified porous particles and a polyester base material; A matte coating layer is provided on a surface corresponding to the matte surface layer; The matte surface layer is uniformly distributed with modified porous particles, wherein the modified porous particles are silicon dioxide surface-modified by a coupling agent modification liquid, and the modified porous particles include first particles and second particles, wherein the particle size of the first particles is 200-300 nm, and the particle size of the second particles is 1-2 μm; The matte coating liquid of the matte coating comprises, by weight, 10 parts of a main resin, 5 to 12 parts of a thermoplastic resin, 0.4 to 1 part of a photoinitiator, and 120 to 300 parts of a solvent; the thermoplastic resin is a copolymer of polydimethylsiloxane and styrene, the molar content of polydimethylsiloxane in the copolymer is 30% to 40%, and the molar mass of polydimethylsiloxane in the copolymer is 2000 to 3000 g / mol; The mass ratio of the first particles to the second particles is (1-4):1, and the total mass of the first particles and the second particles accounts for 3%-7% of the total mass of the raw materials in the matte surface layer; The ratio of the thickness of one of the matte surface layers to the total thickness of the polyester base film is 1:(12-18), the total film thickness of the co-extruded film is 35-135 μm; the layer thickness of the matte coating is 1-4 μm; The main resin is UV curing polyurethane acrylate.

2. The matte polyester film containing porous material according to claim 1, characterized in that: The solvent is toluene and ethyl acetate, and the mass ratio of toluene to ethyl acetate is 1:(0.6~1.2).

3. The matte polyester film containing porous material according to claim 1, characterized in that: The preparation method of the thermoplastic resin comprises the following steps: hydroxypropyl di-terminated polydimethylsiloxane is subjected to a condensation reaction with an azo initiator under the action of a catalyst and an activator to obtain a first chain segment containing the initiator; the first chain segment is mixed with a styrene monomer and reacted at 70-80°C; the reactants are precipitated and dried in a vacuum dryer at 35-40°C; the catalyst is 4-dimethylaminopyridine and p-toluenesulfonic acid, and the activator is dicyclohexylcarbodiimide.

4. A method for preparing a matte polyester film containing a porous material according to any one of claims 1 to 3, characterized in that: The following steps are involved: S1: Preparation of modified porous particles and matte coating solution; S2: The first surface layer, the base film, and the second surface layer are sequentially stacked and co-extruded into a sheet, and then biaxially stretched to obtain a polyester base film, wherein the first surface layer and / or the second surface layer is a matte surface layer; S3: The matte coating liquid is coated on the surface corresponding to the matte surface layer, and dried and solidified to form a matte polyester film having a matte coating layer.

5. The method for preparing a matte polyester film containing porous material according to claim 4, characterized in that: The modified porous particles in S1 are silica surface-modified by a coupling agent modification liquid, wherein the coupling agent is KH-550, and the coupling agent modification liquid has a pH value of 4.8-6; the temperature is raised to the first stage and the first particles are added and dissolved first, and then the temperature is lowered to the second stage and the second particles are added and dissolved. The temperature of the first stage is 40-50°C, and the temperature of the second stage is 25-35°C.

6. The method for preparing a matte polyester film containing porous material according to claim 4, characterized in that: The drying temperatures in S3 were set to 65±5℃, 75±5℃, 80±5℃, 95±5℃, and 80±5℃, respectively; the curing energy was 110~120mJ / cm 2 .

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