A high-resistance colloidal PBT release film and its processing method

Abstract

The present invention discloses a high-resistance adhesive PBT release film and its processing method, belonging to the technical field of release film materials. The raw materials contained in the PBT release film in the present invention are as follows, by weight: 80-100 parts of PBT particles, 5-20 parts of low-temperature material EMMA, 5-20 parts of hyperbranched polyethylene elastomer, and 1-2 parts of compound antioxidant. Among them, the degree of branching of the hyperbranched polyethylene is 50-130 branches / 1000 carbons, the weight-average molecular weight is 66,000-534,000, the melt index is 3-15 g / 10 min, and the melting point is 40-80 °C. The present invention also provides a preparation method of a PBT release film containing a hyperbranched polyethylene elastomer, which greatly improves the adhesive resistance and toughness of the PBT release film.

Description

Technical Field

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

[0002] Due to the extremely low surface tension of TPX (poly-4-methyl-1-pentene), TPX particles are often selected as the release film material for FPC (flexible printed circuit board) in the market. However, since the price of TPX particles is relatively high, and the release film is an indispensable product in the circuit board market, it has become increasingly important to find a product that can replace the TPX release film.

[0003] Currently, release films produced with PBT as the base material have emerged in the market. However, they usually have poor release properties, a relatively hard film surface, and unsatisfactory anti-adhesive effects. Some multi-layer structured PBT release films are also prone to delamination due to poor compatibility between the layer structures. Moreover, the circuit compositions on various current FPC boards are becoming increasingly complex, with deeper grooves and thicker reinforcing sheets, and the requirements for the release properties and anti-adhesive properties of the release film are also getting higher and higher.

[0004] Therefore, there is an urgent need for a PBT release film with better anti-adhesive performance, overall softness and toughness of the film surface, and capable of meeting the 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 anti-adhesive PBT release film and a processing method thereof.

[0006] In the first aspect of the present invention: A high anti-adhesive PBT release film is provided, which, by weight, comprises 80 - 100 parts of PBT particles, 5 - 20 parts of low-temperature material EMMA, 5 - 20 parts of hyperbranched polyethylene elastomer, and 1 - 2 parts of compound antioxidant; wherein, the degree of branching of the hyperbranched polyethylene is 50 - 130 branches / 1000 carbons, the weight-average molecular weight is 66,000 - 534,000, the melt index is 3 - 15 g / 10 min, and the melting point is 40 - 80 °C.

[0007] In the second aspect of the present invention: A processing method of a high anti-adhesive PBT release film is provided, specifically:

[0008] Mix the PBT particles, low-temperature material EMMA, hyperbranched polyethylene elastomer, and compound antioxidant evenly;

[0009] Add through the main feeding hopper of a twin-screw extruder and melt co-extrude at 210 - 250 °C to obtain a strip;

[0010] Pull the obtained strip to a granulator, granulate, and then dry the pellets;

[0011] The first film layer, the second film layer and the third film layer which are interconnected are prepared by three - layer co - extrusion casting to obtain the PBT release film, 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.

[0012] The present invention has the following beneficial effects:

[0013] In the present invention, PBT particles are modified by low - temperature material EMMA, hyperbranched polyethylene elastomer and antioxidant to improve the mechanical properties of PBT particles. And through the interaction of low - temperature material EMMA and hyperbranched polyethylene elastomer, the formed modified PBT film layer becomes soft and has strong toughness, so as to solve the problems of rough, uneven and poor glue - blocking effect on the surface of the FPC board after lamination.

[0014] In addition, the first film layer and the third film layer adopt pure PBT materials, and use their advantages of hard particles and high stiffness as the release layers, while the modified PBT film layer is located in the middle layer. Such a multi - layer 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, making the prepared release film have good release property and no delamination. Therefore, the PBT release film has good release property and good glue - blocking effect, and can be used as a substitute for the TPX release film. In addition, the production cost of the method of the present invention is low, suitable for industrial production, and has good application prospects in the field of FPC board release films. Specific embodiments

[0015] The following examples are given to further illustrate the present invention, but not to limit the scope of the present invention. Some non - essential improvements and adjustments made by those skilled in the art according to the content of the invention still fall within the protection scope of the present invention.

[0016] The high - glue - blocking PBT release film in the present application, by weight, comprises 80 - 100 parts of PBT particles, 5 - 20 parts of low - temperature material EMMA, 5 - 20 parts of hyperbranched polyethylene elastomer, and 1 - 2 parts of compound antioxidant (Irganox1010 and Irgafos168).

[0017] A further technical solution is that the degree of branching of the hyperbranched polyethylene is 50 - 130 branches / 1000 carbons, the weight - average molecular weight is 66,000 - 534,000, the melt index is 3 - 15 g / 10min, and the melting point is 40 - 80 °C.

[0018] A further technical solution is that the hyperbranched polyethylene is obtained by catalytic polymerization with a post-transition metal catalyst and a cocatalyst. The post-transition metal catalyst is at least one of a diimine nickel or a diimine palladium catalyst; the cocatalyst includes any one or more of a boron salt, an alkylaluminoxane, diethylaluminum chloride, trimethylaluminum, triisobutylaluminum, and diethylaluminum chloride.

[0019] A further technical solution is that the molar ratio of the cocatalyst to the post-transition catalyst is (1~500):1; the temperature of the catalytic polymerization reaction is 50~100 °C, the pressure is 0.6~1.7 Mpa, and the reaction time is 0.5~3 h.

[0020] A preparation method of a high-resistance colloidal PBT release film in this application is specifically as follows:

[0021] The uniformly mixed PBT particles, low-temperature material EMMA, hyperbranched polyethylene elastomer, and the antioxidant are added through the main hopper of a twin-screw extruder, and melt coextruded at 210~250 °C to obtain a strip. The obtained strip is drawn to a pelletizer for pelletizing, and then the pellets are dried.

[0022] The first film layer, the second film layer, and the third film layer that are connected to each other are prepared by a three-layer coextrusion casting method to obtain the PBT release film.

[0023] The first film layer and the third film layer are respectively located on the surfaces on both sides of the second film layer, forming an ABA three-layer structure; the total thickness of the first film layer, the second film layer, and the third film layer is 90~160 μm, and the ratio of the film thicknesses of the first film layer and the third film layer to the second film layer is both (1~6):(2~9); the raw materials for preparing the first film layer and the third film layer are both pure PBT, and the film thicknesses are the same. The raw material for preparing the second film layer is modified PBT.

[0024] A further technical solution is that the surface roughness of the first film layer and the third film layer is Rz ≥ 16 μm.

[0025] 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 an antioxidant.

[0026] A further technical solution is that the antioxidant is a compound antioxidant of a hindered phenol antioxidant and a phosphite antioxidant.

[0027] A further technical solution is that the gel resistance of the PBT release film is 40~80 μm, and the longitudinal elongation at break is 200~400%.

[0028] A further technical solution is that the first film layer and the third film layer are extruded by a first main machine, 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 head temperature is 270 - 280 °C. Example 1

[0029] Preparation of hyperbranched polyethylene elastomer:

[0030] The hyperbranched polyethylene elastomer is obtained by catalytic polymerization of ethylene monomers under the action of a nickel-based catalyst and a cocatalyst. Specifically: 250 mL of n-heptane is added to a 500 mL reaction kettle under an ethylene atmosphere, and then the cocatalyst methylaluminoxane (MAO) is added according to a molar ratio of nickel-based catalyst to cocatalyst of 1:150 and used for the polymerization reaction of ethylene monomers. The reaction temperature is adjusted to 70 °C, and then 5 mL of a dichloromethane solution dissolved with the nickel-based catalyst is injected into the reaction kettle. The ethylene pressure is adjusted to 10 bar. After the reaction continues for 0.5 hour, the solution is poured out into a beaker, and absolute ethanol is added according to a volume ratio of 2 times, and stirred for 24 h to obtain the hyperbranched polyethylene elastomer.

[0031] A PBT release film, and its preparation method is as follows:

[0032] PBT modification and granulation: 100 parts by mass of 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 a compound antioxidant (each of Irganox1010 and Irgafos168 accounts for 50%) are mixed and poured into a mixer for stirring. After being evenly mixed to obtain a mixture, it is then put into a twin-screw extruder for extrusion granulation. Among them, the processing conditions are: temperature 210 - 250 °C, the rotation speed of the main machine is 100 rpm, and the rotation speed of the feeder is 3 rpm. It is extruded from the extrusion port of the twin-screw extruder to obtain a strip, and the obtained strip is pulled to a pelletizer and cut into particles about 2 mm, and then the pellets are dried for use in preparing the second film layer.

[0033] Extrusion casting: The PBT release film is a three-layer co-extrusion structure composed of a first film layer, a second film layer, and a third film layer, and the set thickness value is 120 μm. The thicknesses of the first film layer and the third film layer are equal, and the ratio of the sum of the thicknesses 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 rotation speed of the first main machine is 17 rpm, and the processing temperature is 235 - 280 °C; the rotation speed of the second main machine is 36 rpm, the processing temperature is 235 - 255 °C, and the die head temperature is 275 °C. The PBT release film is prepared by a three-layer co-extrusion method. Example 2

[0034] The difference between this embodiment and Embodiment 1 is that the hyperbranched polyethylene elastomer is replaced with high-density polyethylene. Embodiment 3

[0035] The difference between this embodiment and Embodiment 1 is that the hyperbranched polyethylene elastomer is replaced with low-density polyethylene. Embodiment 4

[0036] The difference between this embodiment and Embodiment 1 is that the hyperbranched polyethylene elastomer is replaced with polypropylene.

[0037] A lamination comparison experiment was carried out on the PBT release films produced in Embodiment 1 and the PBT release films produced in Embodiments 2, 3, and 4. First, the release property was compared. The lamination conditions were: temperature 180 °C, pre-pressing for 10 seconds, molding for 120 seconds, molding pressure 120 kg, and supplementary pressing 5 kg. Then, the anti-resin effect was tested under a laser microscope.

[0038] The melt index of the granulated material of the intermediate layer, i.e., the second film layer, was tested (the test conditions were temperature 250 °C and pressure 2.16 Kg), and various indexes of the finally prepared PBT release film were tested, such as thickness, range, release property, anti-resin effect (measured under a microscope), elongation at break (GB13022 1991), and price.

[0039] The test results show that the PBT release film prepared with the hyperbranched polyethylene elastomer has significantly better physical properties than other materials, and the performance meets the requirements.

[0040] The detection results are shown in Table 1 and Table 2.

[0041] Table 1

[0042]

[0043] Table 2

[0044]

[0045] The specific embodiments described herein are merely illustrative of the spirit of the present invention. Those skilled in the art to which the present invention pertains can make various modifications or supplements to the described specific embodiments or use similar ways to substitute, but 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, and triisobutylaluminum.

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 drawn to a pelletizer, pelletized, and then the pellets are dried to obtain modified PBT; 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 the 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 particles, hyperbranched polyethylene elastomer, low-temperature material EMMA and a compound 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.

Images