Matt polyester film containing porous material and preparation method thereof

Abstract

The invention discloses a matt polyester film containing a porous material, which comprises a polyester base film, which is a co-extruded film and is provided with at least one matt surface layer; the matte coating is arranged on the surface of the corresponding matte surface layer; modified porous particles are uniformly distributed on the matte surface layer, the modified porous particles comprise first particles and second particles, the particle size of the first particles is 200-300nm, and the particle size of the second particles is 1-2mu m; a matte coating liquid of the matte coating comprises a main agent resin, a thermoplastic resin, a photoinitiator and a solvent; the thermoplastic resin is a copolymer of polydimethylsiloxane and styrene, the molar content of the polydimethylsiloxane in the copolymer is 30%-40%, and the molar mass of the polydimethylsiloxane in the copolymer is 2000-3000 g / mol. The matte polyester film is good in matte effect and mechanical performance, and the anti-fouling performance of the matte polyester film is further improved through thermoplastic resin composed of polydimethylsiloxane and a styrene copolymer.

Description

Technical Field

[0001] The 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 begin to be interested in low-gloss matte films. The special hazy appearance brought by matte films is more attractive to consumers.

[0003] In order to obtain a matte film, the usual method is to add matte inorganic additives, such as calcium carbonate, magnesium carbonate, silicon dioxide, talc, kaolin, aluminum oxide, titanium dioxide, etc. The more inorganic additives are added, the higher the matte degree of the obtained film is, but the glossiness decreases more slowly; on the other hand, excessive additives but poor dispersion will lead to a decrease in the mechanical strength of the film. Matte films are prone to dust, grease, water stains, fingerprints, etc. due to the concave-convex structure on the surface.

[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 good matte effect and good mechanical properties, and through a thermoplastic resin composed of polydimethylsiloxane and styrene copolymer, the anti-fouling performance of the matte polyester film is improved.

[0006] In order to achieve the above 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 disposed 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 200-300 nm, and the particle size of the second particles is 1-2 μm;

[0010] The matte coating liquid of the matte coating comprises 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%-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 includes 10 parts of main resin, 5-12 parts of thermoplastic resin, 0.4-1 part of photoinitiator and 120-300 parts of solvent in parts by mass.

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

[0019] S1: preparing modified porous particles and preparing matte coating liquid;

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

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

[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 temperatures in S3 are set to 65±5℃, 75±5℃, 80±5℃, 95±5℃, and 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 materials has a matte surface layer with evenly distributed first particles and second particles compounded with each other, and a matte coating layer is combined to form a concave-convex microstructure through multiphase separation, thereby improving the matte effect of the polyester film while ensuring its mechanical properties; and 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 specific implementation of the present invention is further described below in conjunction with the examples. The following examples are only used to more clearly illustrate the technical solutions of the present invention, and cannot be used to limit the protection scope of the present invention.

[0028] Preparation of thermoplastic resins

[0029] Hydroxypropyl double-terminated polydimethylsiloxane reacts with azo initiator under the action of catalyst and activator to obtain the first chain segment with initiator. The first chain segment is mixed with styrene monomer in toluene solvent, and 20% to 25% of reaction liquid is prepared. The temperature is controlled at 75 to 80°C and the reaction is carried out for 7 to 10 hours. The reactant is precipitated and dried in a vacuum dryer at 35 to 40°C. Among them, the azo initiator is 4,4'-azo-(4-cyanovaleric acid), the catalyst is 4-dimethylaminopyridine and p-toluenesulfonic acid, and the activator is dicyclohexylcarbodiimide. The reaction system has high efficiency and few by-products. The formation of the first chain segment reduces the mobility of the azo initiator, and promotes the polymerization of styrene monomer to prepare polydimethylsiloxane (PDMS) and styrene (St) copolymer.

[0030] Preparation of modified porous particles

[0031] The modified porous particles are all silica that has been surface-modified by a coupling agent modification liquid. Among them, the coupling agent is KH-550, which contains amino functional groups and can form hydrogen bonds or chemical bonds with carboxyl or hydroxyl groups in PET, thereby enhancing the bonding force 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. The porous structure gives it a large specific surface area, so it has a large surface energy and more active sites. The surface is rich in silicon hydroxyl groups (Si-OH) and is easy to modify; it has high chemical inertness and is not easy to react with other substances; it can effectively scatter light, reduce surface gloss, and produce a matte effect by changing its preparation method, size, and distribution on the surface of the polyester film. The coupling agent modified liquid is configured with a pH value of 4.8 to 6, and the solvent for preparing the coupling agent modified liquid is ethanol and water. Furthermore, the mass ratio of ethanol, water and coupling agent is 1:5:(0.5 to 0.7); the temperature is raised to the first stage, the first particles are added to dissolve first, and then the temperature is lowered to the second stage, the second particles are added to dissolve. The first stage hydrolysis time is 2 hours, the stirring speed is 3000 rpm, the second stage stirring time is 1.5 hours, and the stirring speed is 3500 rpm. Drying to obtain coupling agent surface modified silica, the drying temperature is 100 to 110 ° C.

[0032] Since the first particles have a small particle size and a large specific surface area and are easy to agglomerate, the temperature of the first stage is controlled at 40-50°C to reduce the viscosity of the modified 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 of 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] Matt coating liquid

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

[0035] The matte coating liquid compounded with thermoplastic resin and main resin, the solvent is evaporated by heat, and after curing, a concave-convex microstructure is formed on the surface of the polyester base film, which reduces the gloss and forms a matte effect. Too much main resin is added, accompanied by solvent volatilization, the main resin and thermoplastic resin are separated into two phases, and the polydimethylsiloxane and styrene copolymer are separated into two phases, the formation of the concave-convex microstructure is blocked, and the matte effect is not good; too little main resin is added to reduce the mechanical properties and wear resistance of the matte polyester film.

[0036] The photoinitiator was PI 184.

[0037] The matte coating liquid prepared by the solvent combination of toluene and ethyl acetate has good leveling properties and can be laid on the matte surface with a concave-convex microstructure; it has good compatibility with polydimethylsiloxane and styrene copolymers, and the boiling point of the mixed solvent is adjusted. During the solvent volatilization, according to the different solubility parameters of the two phases of polydimethylsiloxane and styrene in the solvent, the closer the solubility is, the more difficult it is to volatilize, and the larger the solubility difference is, the less soluble it is and protrusions will form on the surface. Therefore, the combined solvent adjusts the protrusion height and distribution morphology of the concave-convex microstructure of the two phases of the thermoplastic resin, reduces the gloss and forms a matte effect. The molar ratio of polydimethylsiloxane and styrene is also used to further adjust the protrusion height and distribution morphology of the concave-convex microstructure.

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

[0039]

[0040]

[0041] In Table 1, the first surface layer (A) and the second surface layer (A) of the examples and comparative examples are both matte surface layers, M1 / M2 respectively represent the mass ratio of the first particles to the second particles; (M1+M2) / M*100 represents the mass fraction of the total mass of the first particles and the second particles in the total mass of the raw materials in the matte surface layer; the layer thickness ratio of A / B / A represents the layer thickness ratio of the first surface layer (A), the base film (B) and the second surface layer (A). The total film thickness of the polyester base film is 100 μm. If one of M1 and M2 is 0, it means that no particles are added, and if both are 0, it means that no particles are added.

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

[0043]

[0044]

[0045] The method for preparing a matte polyester film containing a porous material comprises the following steps:

[0046] S1: preparing modified porous particles and preparing matte coating liquid;

[0047] The first particles and the second particles were prepared according to Table 1, and the surface was 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 coupling agent modification liquid was configured with a pH value of 4.8-6; the temperature was raised to 48°C in the first stage, the first particles were added to dissolve first, and then the temperature was lowered to 28°C in the second stage, 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 and co-extruded with the polyester substrate, and the first surface layer, the base film, and the second surface layer are sequentially stacked and co-extruded to form a 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, the base film and the second surface layer is FG600.

[0051] S3: The matte coating liquid is coated on the surface of the corresponding matte surface layer, dried and cured to form a matte polyester film with a matte coating. The continuous drying temperatures are 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 in S1, the first particles and the second particles are not dissolved sequentially but mixed together and the hydrolysis temperature of the coupling agent modified liquid is controlled at 50°C.

[0054] Performance Test:

[0055] Performance Test:

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

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

[0058] 3. Adhesion test: The adhesion of matte coating on polyester base film is based on the standard GB / T9286; the grades are divided into 0 to 4, and grade 0 means that there is no or little 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 fabric 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 are prone to sink, resulting in reduced adhesion between the matte surface layer and the matte coating.

[0065] Compared with Example 1, as the content of the first particles and the second particles in the first surface layer (A) and the second surface layer (A) increases, Example 7 becomes difficult to process and the roughness of its surface increases, which can easily lead to uneven coating of the coating liquid of the matte coating and reduce the average adhesion between the matte surface layer and the matte coating.

[0066] Compared with Example 1, as the content of the polydimethylsiloxane phase in the polydimethylsiloxane and styrene copolymer decreases, the matte effect and anti-fouling performance are negatively affected.

[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 thickness of Example 11 is too thick, which is not conducive to the separation of the two phases of the agent resin and the thermoplastic resin, and the separation of the two phases of polydimethylsiloxane and styrene, and it 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 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; A matte coating layer is disposed on a surface corresponding to the matte surface layer; 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 200-300 nm, and the particle size of the second particles is 1-2 μm; The matte coating liquid of the matte coating comprises 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.

2. The matte polyester film containing porous material according to claim 1, characterized in that: 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.

3. The matte polyester film containing porous material according to claim 1 or 2, characterized in that: 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.

4. The matte polyester film containing porous material according to claim 1, characterized in that: The main resin is UV curable polyurethane acrylate.

5. The matte polyester film containing porous material according to claim 4, characterized in that: The matte coating liquid of the matte coating layer comprises 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 in parts by mass.

6. The matte polyester film containing porous material according to claim 5, 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).

7. The matte polyester film containing porous material according to claim 1 or 5, 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 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.

8. A method for preparing a matte polyester film containing a porous material, characterized in that: The following steps are involved: S1: preparing modified porous particles and preparing matte coating liquid; S2: The first surface layer, the base film and the second surface layer are sequentially stacked and co-extruded into a cast sheet, and then biaxially stretched to obtain a polyester base film; S3: coating the matte coating liquid on the surface corresponding to the matte surface layer, drying and curing to form a matte polyester film with a matte coating; 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.

9. The method for preparing a matte polyester film containing a porous material according to claim 7, characterized in that: The modified porous particles in S1 are all silica surface-modified by a coupling agent modification liquid, wherein the coupling agent is KH-550, and the coupling agent modification liquid is configured with a pH value of 4.8-6; 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, wherein the temperature of the first stage is 40-50°C, and the temperature of the second stage is 25-35°C.

10. The method for preparing a matte polyester film containing a porous material according to claim 7, characterized in that: The continuous drying temperatures in S3 are set to 65±5℃, 75±5℃, 80±5℃, 95±5℃, and 80±5℃ in sequence; the curing energy is 110~120mJ / cm 2 .

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