High-adhesive-resistance PBT release film and processing method thereof

Abstract

The invention discloses a high-adhesive-resistance PBT release film and a processing method thereof, and belongs to the technical field of release film materials. The PBT release film comprises the following raw materials in parts by weight: 80-100 parts of PBT particles, 5-20 parts of a low-temperature material EMMA, 5-20 parts of a hyperbranched polyethylene elastomer and 1-2 parts of a compound antioxidant. Wherein the branching degree of the hyperbranched polyethylene is 50-130 branched chains / 1000 carbons, the weight-average molecular weight is 660-53.40 thousand, the melt index is 3-15 g / 10 min, and the melting point is 40-80 DEG C. The invention further discloses a preparation method of the hyperbranched polyethylene. The invention further provides a preparation method of the PBT release film containing the hyperbranched polyethylene elastomer, and the adhesive resistance and toughness of the PBT release film are greatly improved.

Description

Technical Field

[0001] The present invention relates to the technical field of release film materials, and in particular to a high-resistance adhesive PBT release film and a processing method thereof. Background Art

[0002] Since TPX (poly-4-methyl-1-pentene) has an extremely small surface tension, TPX particles are often used as release film materials for FPC (flexible circuit boards) on the market. However, since TPX particles are relatively expensive and release films are an indispensable product in the circuit board market, it is becoming increasingly important to find products that can replace TPX release films.

[0003] At present, release films produced with PBT as the base material have appeared on the market, but they usually have poor release properties, hard film surface, and poor adhesive resistance. Some multi-layer PBT release films are also prone to delamination due to poor compatibility between layer structures. In addition, the circuit composition of various FPC boards is becoming more and more complex, with deeper grooves and thicker reinforcement sheets, and the requirements for release properties and adhesive resistance of release films are also getting higher and higher.

[0004] Therefore, there is an urgent need for a PBT release film that has excellent adhesive resistance, overall softness and toughness of the film surface and can meet the FPC lamination requirements of current complex circuits to replace the existing expensive TPX release film. Summary of the invention

[0005] In order to overcome the deficiencies of the prior art, the present invention provides a high-resistance adhesive PBT release film and a processing method thereof.

[0006] The first aspect of the present invention provides a high-resistance adhesive PBT release film, which comprises, by weight, 80 to 100 parts of PBT particles, 5 to 20 parts of low-temperature material EMMA, 5 to 20 parts of hyperbranched polyethylene elastomer, and 1 to 2 parts of a compound antioxidant; wherein the hyperbranched polyethylene has a branching degree of 50 to 130 branches / 1000 carbons, a weight-average molecular weight of 66,000 to 534,000, a melt index of 3 to 15 g10 / min, and a melting point of 40 to 80°C.

[0007] The second aspect of the present invention provides a method for processing a high-resistance adhesive PBT release film, specifically: Mix PBT particles, low-temperature material EMMA, hyperbranched polyethylene elastomer and compound antioxidant evenly; Add through the main feeding hopper of the twin-screw extruder, and melt co-extrude at 210 ~ 250℃ to obtain material strips; The obtained material strips are pulled to a pelletizer, pelletized, and then the pellets are dried; The PBT release film is obtained by preparing the first film layer, the second film layer and the third film layer connected to each other by three-layer co-extrusion casting, wherein the raw materials of the first film layer and the third film layer are pure PBT, and the raw material of the second film layer is modified PBT.

[0008] The present invention has the following beneficial effects: The invention modifies PBT particles by using low-temperature material EMMA, hyperbranched polyethylene elastomer and antioxidant to improve the mechanical properties of PBT particles, and the formed modified PBT film layer becomes soft and tough through the interaction of low-temperature material EMMA and hyperbranched polyethylene elastomer, so as to solve the problems of rough and uneven board surface and poor adhesive resistance effect after FPC board is pressed.

[0009] In addition, the first film layer and the third film layer are made of pure PBT material, and the advantages of hard particles and high stiffness are used as release layers, while the modified PBT film layer is located in the middle layer. Such a multilayer structure can not only improve the overall mechanical properties, but also the modified PBT film layer can be well integrated with the first film layer and the third film layer, so that the prepared release film has good release properties and no stratification. Therefore, the PBT release film has release properties and good adhesive resistance, and can be used as a substitute for TPX release film. In addition, the method of the present invention has low production cost, is suitable for industrial production, and has good application prospects in the field of FPC board release films. DETAILED DESCRIPTION

[0010] The following examples are given to further illustrate the present invention, but are not intended to limit the scope of the present invention. Some non-essential improvements and adjustments made to the present invention by those skilled in the art based on the content of the invention still fall within the scope of protection of the present invention.

[0011] The high-resistance adhesive PBT release film in the present application comprises, by weight, 80 to 100 parts of PBT particles, 5 to 20 parts of low-temperature material EMMA, 5 to 20 parts of hyperbranched polyethylene elastomer, and 1 to 2 parts of compound antioxidants (Irganox 1010 and Irgafos 168).

[0012] A further technical solution is that the branching degree of the hyperbranched polyethylene is 50 to 130 branches / 1000 carbons, the weight average molecular weight is 66,000 to 534,000, the melt index is 3 to 15 g / 10 min, and the melting point is 40 to 80°C.

[0013] A further technical solution is that the hyperbranched polyethylene is obtained by catalytic polymerization of a late transition metal catalyst and a co-catalyst, wherein the late transition metal catalyst is at least one of a diimine nickel or a diimine palladium catalyst; and the co-catalyst includes any one or more of boron salts, alkylaluminoxanes, diethylaluminum chloride, trimethylaluminum, triisobutylaluminum, and diethylaluminum chloride.

[0014] A further technical solution is that the molar ratio of the co-catalyst to the late transition catalyst is (1-500):1; the catalytic polymerization reaction temperature is 50-100 degrees, the pressure is 0.6-1.7 MPa, and the reaction time is 0.5-3 hours.

[0015] A method for preparing a high-resistance adhesive PBT release film in the present application is specifically: The uniformly mixed PBT particles, low-temperature material EMMA, hyperbranched polyethylene elastomer and antioxidant are added through the main feeding hopper of a twin-screw extruder, melt co-extruded at 210-250° C. to obtain material strips, which are pulled to a pelletizer for pelletizing, and then the pellets are dried.

[0016] A three-layer co-extrusion casting method is adopted to prepare the first film layer, the second film layer and the third film layer which are connected to each other, so as to obtain the PBT release film.

[0017] The first film layer and the third film layer are respectively located on the surfaces of both sides of the second film layer to form an ABA three-layer structure; the total thickness of the first film layer, the second film layer and the third film layer is 90~160μm, and the ratio of the film thickness of the first film layer and the third film layer to the second film layer is (1~6):(2~9); the raw materials for preparing the first film layer and the third film layer are both pure PBT with consistent film thickness, and the raw material for preparing the second film layer is modified PBT.

[0018] A further technical solution is that the surface roughness of the first film layer and the third film layer is Rz ≥ 16 μm.

[0019] A further technical solution is that the modified PBT is obtained by co-extrusion granulation of PBT raw material particles, hyperbranched polyethylene elastomer, low-temperature material EMMA and antioxidant.

[0020] A further technical solution is that the antioxidant is a compound antioxidant of a hindered phenol antioxidant and a phosphite antioxidant.

[0021] A further technical solution is that the PBT release film has a glue resistance of 40 to 80 μm and a longitudinal elongation at break of 200 to 400%.

[0022] A further technical solution is that the first film layer and the third film layer are extruded by a first main machine, and the second film layer is extruded by a second main machine. The rotation speed of the first main machine is 12 to 20 rpm, and the processing temperature is 235 to 280°C; the rotation speed of the second main machine is 28 to 40 rpm, and the processing temperature is 235 to 255°C; and the die head temperature is 270 to 280°C. Example 1

[0023] Preparation of hyperbranched polyethylene elastomer: The hyperbranched polyethylene elastomer is obtained by catalytic polymerization of ethylene monomer under the action of nickel catalyst and co-catalyst, specifically: 250mL of n-heptane is added to a 500mL reactor under ethylene atmosphere, and then co-catalyst methylaluminoxane (MAO) is added according to the molar ratio of nickel catalyst to co-catalyst of 1:150, and used for the polymerization reaction of ethylene monomer. The reaction temperature is adjusted to 70°C, and then 5 ml of dichloromethane solution dissolved with nickel catalyst is injected into the reactor, and the ethylene pressure is adjusted to 10 bar. After the reaction lasts for 0.5 hours, the solution is poured into a beaker, and anhydrous ethanol is added according to a 2-fold volume ratio, and stirred for 24 hours to obtain a hyperbranched polyethylene elastomer.

[0024] A PBT release film, the preparation method of which is as follows: PBT modified granulation: Pour 100 parts by mass of mixed PBT particles, 14 parts by mass of hyperbranched polyethylene elastomer, 20 parts by mass of low-temperature material EMMA, and 2 parts by mass of compound antioxidant (50% each of Irganox1010 and Irgafos168) into a mixer for stirring, and mix evenly to obtain a mixture, which is then put into a twin-screw extruder for extrusion granulation, wherein the processing conditions are: temperature 210~250℃, main engine speed 100rpm, and feeder speed 3rpm. Extrude from the extrusion port of the twin-screw extruder to obtain material strips, which are pulled to a pelletizer and cut into particles of about 2mm, and then the pellets are dried for use in preparing the second film layer.

[0025] Extrusion casting: The PBT release film is a three-layer co-extrusion structure consisting of the first film layer, the second film layer and the third film layer. The thickness setting value is 120μm. The thickness of the first film layer and the third film layer is equal, and the ratio of the thickness of the first film layer and the third film layer to the thickness of the second film layer is 1:2. The pure PBT particles are placed in the first main machine, and the modified PBT particles are placed in the second main machine. The speed of the first main machine is 17 rpm, and the processing temperature is 235-280℃; the speed of the second main machine is 36rpm, the processing temperature is 235-255℃, and the die temperature is 275℃. The PBT release film is prepared by three-layer co-extrusion. Example 2

[0026] The difference between this embodiment and embodiment 1 is that the hyperbranched polyethylene elastomer is replaced with high-density polyethylene. Example 3

[0027] The difference between this embodiment and embodiment 1 is that the hyperbranched polyethylene elastomer is replaced with low-density polyethylene. Example 4

[0028] The difference between this embodiment and embodiment 1 is that the hyperbranched polyethylene elastomer is replaced with polypropylene.

[0029] The PBT release film produced in Example 1 was subjected to a comparative lamination experiment with the PBT release films produced in Examples 2, 3, and 4. The release properties were first compared. The lamination conditions were: temperature 180 degrees, pre-pressing 10 seconds, molding 120 seconds, molding pressure 120 kg, and supplementary pressure 5 kg. The adhesive resistance effect was then tested under a laser microscope.

[0030] The melt index of the granulated material of the middle layer, i.e. the second film layer, was tested (the test conditions were temperature 250°C, pressure 2.16Kg), as well as the thickness, extreme difference, release, adhesive resistance (measured under a microscope), elongation at break (GB130221991), price and other indicators of the final PBT release film.

[0031] The test results show that the physical properties of PBT release film prepared by using hyperbranched polyethylene elastomer are significantly better than those of other materials and meet the requirements.

[0032] The test results are shown in Tables 1 and 2.

[0033] Table 1

[0034] Table 2

[0035] The specific embodiments described herein are merely examples of the spirit of the present invention. Those skilled in the art may make various modifications or additions to the specific embodiments described or replace them in similar ways, but they will not deviate from the spirit of the present invention or exceed the scope defined by the appended claims.

Claims

1. A high-resistance adhesive PBT release film, characterized in that: The invention comprises 80 to 100 parts by weight of PBT particles, 5 to 20 parts of low-temperature material EMMA, 5 to 20 parts of hyperbranched polyethylene elastomer, and 1 to 2 parts of compound antioxidant; wherein the hyperbranched polyethylene has a branching degree of 50 to 130 branches / 1000 carbon atoms, a weight-average molecular weight of 66,000 to 534,000, a melt index of 3 to 15 g10 / min, and a melting point of 40 to 80°C.

2. The high-resistance adhesive PBT release film according to claim 1, characterized in that: The hyperbranched polyethylene is obtained by catalytic polymerization of a late transition metal catalyst and a co-catalyst.

3. The high-resistance adhesive PBT release film according to claim 2, characterized in that: The co-catalyst includes any one or more of boron salt, alkylaluminoxane, diethylaluminum chloride, trimethylaluminum, triisobutylaluminum, and diethylaluminum chloride.

4. The high-resistance adhesive PBT release film according to claim 2 or 3, characterized in that: The molar ratio of the co-catalyst to the late transition metal catalyst is (1-500):1; the catalytic polymerization reaction temperature is 50-100 degrees, the pressure is 0.6-1.7 MPa, and the reaction time is 0.5-3 hours.

5. A method for processing a high-resistance adhesive PBT release film, characterized in that: The following steps are involved: Mix PBT particles, low-temperature material EMMA, hyperbranched polyethylene elastomer and compound antioxidant evenly; Add through the main feeding hopper of the twin-screw extruder, and melt co-extrude at 210 ~ 250℃ to obtain material strips; The obtained material strips are pulled to a pelletizer, pelletized, and then the pellets are dried; The PBT release film is obtained by preparing the first film layer, the second film layer and the third film layer connected to each other by three-layer co-extrusion casting, wherein the raw materials of the first film layer and the third film layer are pure PBT, and the raw material of the second film layer is modified PBT.

6. The method for processing a PBT release film according to claim 5, characterized in that: The first film layer and the third film layer are extruded by a first main machine, and the second film layer is extruded by a second main machine. The rotation speed of the first main machine is 12-20 rpm, and the processing temperature is 235-280°C; the rotation speed of the second main machine is 28-40 rpm, and the processing temperature is 235-255°C; the die temperature is 270-280°C.

7. The method for processing a PBT release film according to claim 5 or 6, characterized in that: The PBT release film has a resistance of 40 to 80 μm and a longitudinal elongation at break of 200 to 400%.

8. The method for processing a PBT release film according to claim 5, characterized in that: The surface roughness of the first film layer and the third film layer is Rz ≥ 16 μm.

9. The method for processing a PBT release film according to claim 5, characterized in that: The modified PBT is obtained by co-extrusion granulation of PBT raw material particles, hyperbranched polyethylene elastomer, low-temperature material EMMA and antioxidant.

10. The method for processing a PBT release film according to claim 9, characterized in that: The compound antioxidant is a compound antioxidant of a hindered phenol antioxidant and a phosphite antioxidant.

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