CN114311915A - Multilayer high-temperature-resistant fluorine-containing release film and preparation method thereof - Google Patents

Abstract

The invention belongs to the technical field of release films, and particularly relates to a multilayer high-temperature-resistant fluorine-containing release film and a preparation method thereof. The fluorine-containing release film comprises a first release layer, a structural layer and a second release layer, the release film is prepared by a multilayer coextrusion casting mode, the material of the structural layer comprises polyester polymer, fluororesin and functional auxiliary agent, the two release layers comprise fluorine-containing resin, the release layer has good high temperature resistance and tensile strength, no binder is contained between the structural layer and the release layer, the preparation process is simple, the problem of pollution of the binder to the release layer in the prior art is avoided, and the technical effects of high temperature resistance, tensile strength and simple forming process of the release film are realized.

Description

A kind of multi-layer high temperature resistant fluorine-containing release film and preparation method thereof

technical field

The invention belongs to the technical field of thin films, and in particular relates to a multi-layer high temperature resistant fluorine-containing release film and a preparation method.

Background technique

With the development of the information age, electronic devices are becoming more and more functional and diversified, and the requirements for release films are getting higher and higher. In the production process of electronic accessories, release films with excellent performance are indispensable. of.

Chinese patent CN211106113 (application number 201921296084.2) provides an environmentally friendly PET release film, including a PET base layer, two anti-stretch layers, two wear-resistant layers, and a PET release layer, but the temperature resistance and anti-stretch performance are insufficient . Ordinary release film substrates are generally PP, PE, PET, etc. The release film is prepared by plasma treatment, fluorine coating, or coating the surface of the substrate with a silicon release agent, which usually has insufficient elongation and resistance. Insufficient temperature, easy to contaminate electronic devices and other shortcomings. Chinese patent CN106042553A (application number is 201610408694.1) provides a high temperature resistant release film, the release layer is polymethylpentene, and the support layer is polyolefin, but the elastic modulus of the film is too high, and it is easy to be used in electronic products. Wrinkles are created during thermoforming of the device. Fluorine-containing resins usually have good temperature resistance and excellent tensile properties, and more and more researches have been conducted to apply them to release films. Chinese patent CN111002667A (application number 201911317773.1) provides a fluorine-containing resin and polyester material. The release film includes a first raw material, a second raw material and a third raw material, the first raw material is at least one of polytetrafluoroethylene, ethylene-tetrafluoroethylene copolymer, polyvinylidene fluoride and polyvinyl fluoride, and the second raw material It is a bonding material, the third raw material is polyester material, and the ABC three-layer release film with the structure of release layer-adhesion layer-support layer is obtained by co-extrusion of three extruders. High temperature resistance and low thermal shrinkage rate, but a bonding material is used between the first layer and the third layer, and a lamination step is required, and the prepared release film has insufficient tensile properties, which limits its application in the field of film materials.

To sum up, the common release film substrate has shortcomings such as insufficient elongation, insufficient temperature resistance, and poor practicability, and the compatibility between the fluorine-containing resin layer and the polyester layer in the release film is generally poor. , It is often necessary to have an adhesive layer as a transition layer. The adhesive layer is easy to remain on the release layer. When used in the production and processing of electronic devices, it may cause pollution to electronic devices. Therefore, in order to meet practical applications, it is necessary to develop an Adhesive layer, a release film with good tensile properties, high temperature resistance and environmental protection properties.

SUMMARY OF THE INVENTION

In view of the above problems, the present invention provides a high temperature resistant fluorine-containing release film and a preparation method. The release film includes a first release layer, a structural layer and a second release layer from bottom to top, and the release film passes through multiple layers. The material of the structural layer includes polyester polymers, fluororesin and functional additives. The materials of the two layers of release layers are the same or different, and both are fluorine-containing resins. The release layer of the present invention has Good high temperature resistance and tensile strength, there is no binder between the structural layer and the release layer, the preparation process is simple, and the problem of contamination of the release layer by the binder in the prior art is avoided. The technical effect of high temperature resistance, tensile strength and simple forming process of the film.

In order to achieve the above object, the present invention adopts the following technical solutions:

The invention provides a multi-layer high temperature resistant fluorine-containing release film, which is characterized in that it comprises a first release layer, a structural layer and a second release layer, and the structural layer is sandwiched between the first release layer and the second release layer. In the middle of the release layer, the first release layer, the structural layer and the second release layer are made of a three-layer release film by a multi-layer co-extrusion casting method; the total thickness of the release film is 60-100 μm, and the structural layer The thickness ratio is 60-75%, the thickness ratio of the first release layer is 10-25%, and the thickness ratio of the second release layer is 10-25%; the structural layer includes the following components by mass fraction: polyester 76-87 wt % of a polymer-like polymer, 12-19 wt % of a fluororesin, and 1-5 wt % of a compatibilizer, the first release layer and the second release layer contain the same or different fluororesins.

The content of fluororesin in the structural layer can be selected according to the viscosity of the mixed resin in the molten state after it is mixed with polyester polymer for granulation. The content of fluororesin in the structural layer should be in the range of 12%-19% If the proportion is too large, the tensile strength and ductility of the structural layer after melt extrusion of the mixed resin will decrease; if the fluororesin content is too low, the structural layer and the first release layer, the structural layer and the second release The anchoring force between the layers becomes poor.

Preferably, the polyester polymers include polycarbonate (PC), polybutylene terephthalate (PBT), polyethylene naphthalate (PEN), polyethylene terephthalate One or more mixtures of alcohol esters (PET), preferably, the polyester polymer is PC or PET.

Preferably, the melt index of the polyester polymer is 5-20 g/10min, the tensile strength is 40-70 MPa, and the tensile modulus is 400-800 MPa.

Preferably, the fluororesin is perfluoroethylene propylene copolymer (FEP) or ethylene-tetrafluoroethylene copolymer (ETFE)

Preferably, the melt index of the fluororesin is 5-20 g/10min, the tensile strength is 20-50 MPa, and the tensile modulus is 400-800 MPa. Studies have shown that the molecular weight of the polymer is an important factor affecting its melt index. The larger the molecular weight of the polymer, the higher the melt index. For ethylene-tetrafluoroethylene polymers, the greater the proportion of tetrafluoroethylene units in ETFE, the greater the melt index of the ETFE polymer. In the present invention, the melt index of the fluororesin is controlled within the range of 5-20 g/10min. Excessive melt index makes processing more difficult, the smoothness and flatness of the formed film decrease, and the processing cost increases.

The measurement method of the melt index of polyester polymers refers to GB/T 3682-2000. The test conditions are: the test temperature is 300°C, and the nominal load is 1.2kg; the measurement method of the melt index of the fluororesin is the same as that of GB/T 3682-2000. The conditions are: the test temperature is 297°C, and the nominal load is 5kg.

There is a lack of adhesion between fluororesin and most thermoplastic polymers. The first release layer and the second release layer composed of fluororesin are more stable than the structural layer mainly composed of polyester polymers. Adding a compatibilizer to the structural layer can effectively improve the fixing force between the structural layer and the release layer, and avoid the structural layer and the first release layer, the structural layer and the second release layer after molding. The problem of peeling occurs during the pulling process.

The compatibilizer includes one or a mixture of cyclic acid anhydride type, acid anhydride type, epoxy type, and imide-modified acrylic resin. Preferably, the compatibilizer is imide-modified acrylic resin resin.

In the presence of the imide-modified acrylic resin, the thermoplastic polyester-based polymer and the fluororesin are mechanically kneaded and granulated at high temperature to obtain structured layer pellets. The tensile strength of the structure layer of the multilayer high temperature resistant fluorine-containing release film prepared by using the structure layer pellets is obviously improved. The compatibilizer is intended to improve the performance of the structural layer by reducing the interfacial tension and by improving the phase interface between the polyester-based polymer and the fluororesin and the adhesion of both.

The present invention also provides a method for preparing a multi-layer high temperature resistant fluorine-containing release film, which is characterized by comprising the following steps:

(1) The components of the structural layer are weighed according to the mass ratio, mixed in a high-speed mixer, and then melt-blended, extruded, pulled granulated, and dried through a twin-screw extruder to obtain the structural layer pellets.

(2) Prepare three extruders A, B and C, and add fluororesin to the extruders A and C, respectively, to extrude the first release layer and the second release layer of the release film, and extrude The pellets in step (1) are added to the machine B to extrude the structural layer of the release film, the melt extruded by the three-layer extruder enters and is compounded in the casting die, and the compounded multilayer melt The body is shaped, cooled, drawn and annealed to prepare a multi-layer high temperature resistant release film. The thickness is detected and adjusted by an online thickness gauge. The film is trimmed and rolled to obtain a multi-layer high temperature resistant release film product.

Preferably, in the step (1), the blending time is 2-10min, the extrusion temperature is 270-340°C, the screw speed is 15-80r/min, and the granulation is pulled and dried at 100°C for 8h.

Preferably, in the step (2), the screw length-diameter ratio of the extruder A is 20-30, including four heating zone barrels, and the barrel temperatures are respectively set as: 350℃, 3 zone 230-360℃, 4 zone 230-370℃.

Preferably, in the step (2), the screw length-diameter ratio of the extruder B is 25-30, including four heating zone barrels, and the barrel temperatures are respectively set as: 340°C, 220-350°C in zone 3, 220-350°C in zone 4.

Preferably, the process parameters of the extruder C in the step (2) are set with the extruder A.

Preferably, in the step (2), the casting die is a multi-channel in-mold composite casting die, and the temperature is set at 250-370°C.

One or more technical solutions provided by the present invention have at least the following technical effects:

1. The release film prepared by the present invention has good temperature resistance, excellent tensile properties and no pollution.

2. The release film prepared by the present invention has a three-layer structure as a whole, no additional bonding layer and lamination steps are required, the molding process is simple, there is no solvent residue, and the electronic device will not be polluted during use.

Detailed ways

The following specific examples further illustrate the present invention. The raw materials used in the examples are all commercially available products. The tensile property test method of the multilayer high temperature resistant fluorine-containing release film refers to ISO 527-3 2018; the thermal shrinkage rate test method refers to GB/T12027-2004, and the thermal shrinkage rate of the ETFE release layer is treated at a constant temperature in a 160°C oven Measured after 1h, the thermal shrinkage of the FEP release layer was measured after 1h of constant temperature treatment in a 210°C oven.

Example 1

A multi-layer high temperature resistant fluorine-containing release film, the release film is a first release layer, a structural layer, and a second release layer in order from top to bottom. The structural layer includes the following components by mass fraction: ETFE: 12%; PC: 87%; fluoropolyimide-modified acrylic resin: 1%. The structural layer thickness is 36 μm. The first and second release layers are both ETFE layers with a thickness of 12 μm. The melt index of ETFE was 5 g/10 min, the tensile strength was 20.0 MPa, and the tensile modulus was 400 MPa. The melt index of PC was 5 g/10 min, the tensile strength was 40.0 MPa, and the tensile modulus was 400 MPa.

The preparation steps of the release film are as follows:

(1) After weighing the components of the structural layer by mass ratio, they were mixed in a high-speed mixer. The mixing time was 4 minutes, and then the twin-screw extruder was used for melt blending. The extrusion temperature was controlled at 280 ° C, and the screw speed was 30 r/ min, after pulling and granulating, drying at 100°C for 8h, and sealing for later use.

(2) The used extrusion casting film unit contains three extruders, wherein A and C extruders are used to extrude two layers of outer release films, and extruder B is used to extrude structural layer films. The melt extruded by the layer extruder passes through the multi-channel in-die composite casting die, and the composite multi-layer melt undergoes shaping, cooling, pulling, annealing and other steps to prepare a multi-layer high temperature resistant release film. Thickness tester detects and adjusts the thickness, and the film is trimmed and wound to obtain a multi-layer high temperature resistant release film product.

The preparation process parameters of the release film are as follows:

A extruder: The extruder for processing ETFE resin selects a screw with an aspect ratio of 30 and a barrel with four heating zones. The temperature is set to 260°C for zone 1, 270°C for zone 2, and 280°C for zone 3 , 4 zone is 290 ℃. Adjust the thickness of the first release layer to 12 μm.

B extruder: The extruder for processing the structural layer mixture material selects a screw with an aspect ratio of 25 and a barrel with four heating zones. The temperature is set to 240°C for zone 1, 250°C for zone 2, and 260°C for zone 3. °C, 270 °C in zone 4. Adjust the extrusion thickness to 36 μm.

C extruder: The process parameter settings are the same as the A extruder.

Multi-runner die: The temperature was set to 295°C. After each section of the equipment reaches the set temperature value and keeps the temperature for 0.5h, the feeding production starts. The mechanical properties of each layer of the obtained release film are shown in Table 1.

Example 2

A multi-layer high temperature resistant fluorine-containing release film is as in Example 1, the difference is that the structural layer includes the following components by mass fraction: ETFE: 19%; PC: 76%; fluoropolyimide modified acrylic acid Resin: 5%. The melt index of ETFE is 20g/10min, the tensile strength is 50.0MPa, and the tensile modulus is 800MPa. The melt index of PC was 20 g/10 min, the tensile strength was 70.0 MPa, and the tensile modulus was 800 MPa. The preparation steps of the release film of this example are the same as those of Example 1, and the test results of the mechanical properties of each layer of the obtained release film are shown in Table 1.

Example 3

A multi-layer high temperature resistant fluorine-containing release film, the release film is a first release layer, a structural layer, and a second release layer in order from top to bottom. The structural layer includes the following components by mass fraction: fluororesin ETFE: 5%; polyethylene terephthalate (PET): 80%; fluoropolyimide-modified acrylic resin 5%. The thickness of the structural layer is 70 μm. The first and second release layers are both ETFE layers with a thickness of 15 μm. The melt index of ETFE was 10 g/10 min, the tensile strength was 35.0 MPa, and the tensile modulus was 430 MPa. The melt index of PET was 10 g/10 min, the tensile strength was 40.0 MPa, and the tensile modulus was 450 MPa.

The preparation steps of the above-mentioned release film are as follows:

(1) After weighing each component of the structural layer according to the above-mentioned mass ratio, mix in a high-speed mixer, the mixing time is 4 minutes, and then melt and blend through a twin-screw extruder, the extrusion temperature is controlled at 270 ° C, and the screw speed is controlled at 270 ° C. It is 30r/min, and after traction granulation, it is dried at 100℃ for 8h, and sealed for use.

(2) The used extrusion casting film unit contains three extruders, wherein A and C extruders are used for extruding the first and second release films, and extruder B is used for extruding structural layer films, The melt extruded by the three-layer extruder passes through the multi-channel in-die composite casting die, and the composite multi-layer melt undergoes shaping, cooling, pulling, annealing and other steps to prepare a multi-layer high temperature resistant release film. The thickness is detected and adjusted by the thickness gauge, and the film is trimmed and wound to obtain a multi-layer high temperature resistant release film product.

The process parameters of the preparation of the release film are as follows:

A extruder: The extruder for processing ETFE resin selects a screw with an aspect ratio of 30 and a barrel with four heating zones. The temperature is set to 260°C for zone 1, 270°C for zone 2, and 280°C for zone 3 , 4 zone is 290 ℃. The film thickness was adjusted to 15 μm.

B extruder: The extruder for processing the structural layer mixture material selects a screw with an aspect ratio of 25 and a barrel with four heating zones. The temperature is set to 230°C in zone 1, 240°C in zone 2, and 250 in zone 3. °C, 260 °C in zone 4. Adjust the film thickness to 70 μm.

C extruder: The process parameter settings are the same as the A extruder.

Multi-runner die: temperature setting 295°C range. After each section of the equipment reaches the set temperature value and keeps the temperature for 0.5h, the feeding production starts. The mechanical properties test results of each layer of the obtained release film are shown in Table 1.

Example 4

A multi-layer high temperature resistant fluorine-containing release film and a preparation method. The release film is composed of a first release layer, a structural layer and a second release layer from top to bottom. The structural layer is a mixed layer of 12% fluororesin FEP, 85% polycarbonate (PC) and 3% fluoropolyimide modified acrylic resin, with a thickness of 70 μm. The first release layer and the second release layer are both FEP resin layers, with thicknesses of 10 μm and 15 μm, respectively. The melt index of the fluororesin FEP was 10 g/10 min, the tensile strength was 35.0 MPa, and the tensile modulus was 430 MPa. The melt index of PC was 10 g/10 min, the tensile strength was 40.0 MPa, and the tensile modulus was 450 MPa.

The preparation method steps are as follows:

(1) Fluorine resin FEP 12%, polycarbonate (PC) 85%, and fluoropolyimide modified acrylic resin 3% of each component of the structural layer are weighed by mass ratio and mixed in a high-speed mixer for 4 minutes. , and then melt and blend through a twin-screw extruder. The extrusion temperature is controlled at 340 ° C, the screw speed is 30 r/min, and after pulling and granulation, it is dried at 100 ° C for 8 hours, and sealed for use.

(2) The used extrusion casting film unit contains three extruders, wherein A and C extruders are used for extruding the first and second release films, and extruder B is used for extruding structural layer films, The melt extruded by the three-layer extruder passes through the multi-channel in-die composite casting die, and the composite multi-layer melt undergoes shaping, cooling, pulling, annealing and other steps to prepare a multi-layer high temperature resistant release film. The thickness is detected and adjusted by the thickness gauge, and the film is trimmed and wound to obtain a multi-layer high temperature resistant release film product.

The process parameters of the preparation of the release film are as follows:

A extruder: The extruder for processing FEP resin selects a screw with an aspect ratio of 30 and a barrel with four heating zones. The temperature is set to 330°C for zone 1, 340°C for zone 2, and 350°C for zone 3 , 4 zone is 360 ℃. Adjust the film thickness to 10 μm.

B extruder: The extruder for processing the structural layer mixture material selects a screw with an aspect ratio of 25 and a barrel with four heating zones. The temperature is set to 240°C for zone 1, 250°C for zone 2, and 260°C for zone 3. °C, 270 °C in zone 4. Adjust the film thickness to 70 μm.

Extruder C: The process parameters were set the same as the extruder A, and the thickness was 15 μm.

Multi-runner die: The temperature was set to 360°C. After each section of the equipment reaches the set temperature value and keeps the temperature for 0.5h, the feeding production starts.

The mechanical properties test results of each layer of the obtained release film are shown in Table 1.

Table 1. Mechanical properties of the structural layer, the first release layer and the second release layer of the release film of the embodiment

project Example 1 Example 2 Example 3 Example 4 Structural layer tensile strength/MPa 30.8 48.9 28.7 31.2 Tensile strength of the first release layer/MPa 18.5 46.7 36.2 34.7 Tensile strength of the second release layer/MPa 19.3 47.9 35.4 33.5 Elongation at break of the first release layer/% 267 236 247 146 Elongation at break of the second release layer/% 282 228 254 137 Thermal shrinkage rate of the first release layer/% 2.2 2.4 2.3 2.1 Thermal shrinkage rate of the second release layer/% 2.3 2.3 2.1 2.0

It can be seen from the above table that the raw material of the release layer of the high temperature resistant fluorine-containing release film prepared by the present invention is ETFE or FEP material, which has excellent thermal shrinkage properties and tensile properties. The whole release film is a three-layer structure of co-extrusion molding, which does not require additional bonding layers and lamination steps. The molding process is simple, and there is no solvent residue on the surface of the release layer, which will not pollute electronic devices during use. At the same time, the structure layer adopts polyester polymer instead of fluororesin polymer, which reduces the cost of the release film material.

Claims (10)

1. The multilayer high-temperature-resistant fluorine-containing release film is characterized by comprising a first release layer, a structural layer and a second release layer, wherein the structural layer is clamped between the first release layer and the second release layer, and the first release layer, the structural layer and the second release layer are manufactured into a three-layer release film in a multilayer coextrusion casting mode; the total thickness of the release film is 60-100 mu m, the thickness ratio of the structural layer is 60-75%, the thickness ratio of the first release layer is 10-25%, and the thickness ratio of the second release layer is 10-25%; the structural layer comprises the following components in mass fraction: 76-87 wt% of polyester polymer, 12-19 wt% of fluororesin and 1-5 wt% of compatilizer, wherein the first release layer and the second release layer comprise the same or different fluororesin.

2. The release film according to claim 1, wherein the polyester-based polymer comprises at least one of polycarbonate, polybutylene terephthalate, polyethylene naphthalate, and polyethylene terephthalate.

3. The release film as claimed in claim 1, wherein the polyester-based polymer has a melt index of 5-20g/10min, a tensile strength of 40-70MPa, and a tensile modulus of 400-800 MPa.

4. The release film according to claim 1, wherein the fluororesin is a perfluoroethylene propylene copolymer or an ethylene-tetrafluoroethylene copolymer.

5. The release film as claimed in claim 1, wherein the fluororesin has a melt index of 5-20g/10min, a tensile strength of 20-50MPa, and a tensile modulus of 400-800 MPa.

6. The release film according to claim 1, wherein the compatibilizer is one or a mixture of several of a cyclic anhydride compatibilizer, an epoxy compatibilizer, and an imide-modified acrylic resin; preferably, the compatilizer is imide modified acrylic resin.

7. The preparation method of the multilayer high-temperature-resistant fluorine-containing release film according to any one of claims 1 to 6, which comprises the following steps:

(1) weighing the components of the structural layer according to the mass ratio, mixing in a high-speed mixer, and carrying out melt blending, extrusion, traction granulation and drying by using a double-screw extruder to obtain structural layer granules;

(2) preparing three extruders A, B, C, adding fluororesin into the extruder A, C respectively for extruding a first release layer and a second release layer of the release film, adding the granules obtained in the step (1) into the extruder B for extruding a structural layer of the release film, feeding the melt extruded by the three extruders into a casting die head for compounding, shaping, cooling, drawing and annealing the compounded multilayer melt to prepare the multilayer high-temperature resistant release film, detecting and adjusting the thickness by an online thickness gauge, cutting edges of the film and rolling to obtain the multilayer high-temperature resistant fluorine-containing release film product.

8. The preparation method as claimed in claim 7, wherein the blending time in step (1) is 2-10min, the extrusion temperature is 270-340 ℃, the screw rotation speed is 15-80r/min, and the mixture is dried at 100 ℃ for 8h after traction granulation.

9. The preparation method according to claim 7, wherein the screw length-diameter ratio of the extruder A in the step (2) is 20-30, and the extruder A comprises four heating zone barrels, and the temperatures of the four heating zone barrels are respectively set as follows: the 1 region is 220-340 ℃, the 2 region is 230-350 ℃, the 3 region is 230-360 ℃, and the 4 region is 230-370 ℃; the length-diameter ratio of the screw of the extruder B is 25-30, the extruder B comprises four heating zone charging barrels, and the temperatures of the charging barrels are respectively set as follows: the 1 region 210-340 ℃, the 2 region 220-340 ℃, the 3 region 220-350 ℃ and the 4 region 220-350 ℃; the process parameters of extruder C were set as for extruder A.

10. The production method according to claim 7, wherein the casting die in the step (2) is a multi-runner in-mold composite casting die, and the temperature is set to 250 ℃ and 370 ℃.