KR100552426B1 - Laminate of polyolefin film and metallic thin layer - Google Patents

Abstract

The present invention relates to a method for producing a polyolefin-based film having excellent adhesion to metal. Specifically, the polyolefin-based film is surface treated with a fluorine / oxygen mixed gas to maintain polyolefin-based polymers while maintaining the properties such as good mechanical properties and excellent processability. The present invention relates to a method for producing a polyolefin film having improved adhesion to copper foil by effectively modifying only the surface of a polymer in a short time to increase surface free energy and introducing an oxygen functional group to the surface.

Description

Joint of polyolefin-based film and metal thin film {LAMINATE OF POLYOLEFIN FILM AND METALLIC THIN LAYER}

1 is a view showing a fluorine mixed gas surface treatment apparatus used in an embodiment of the present invention,

Figure 2 is a graph showing the FTIR-ATR results of the fluorine mixed gas surface treated LDPE film and the untreated film according to an embodiment of the present invention,

3 is an entire XPS spectrum of a fluorine mixed gas surface treated LDPE film and an untreated film according to an embodiment of the present invention,

4 is an XPS C _1S spectrum of the fluorine mixed gas surface-treated LDPE film and the untreated film according to the embodiment of the present invention (before and after the waveform separation (a) and separation (b)),

5 is an XPS O _1S spectrum of the fluorine mixed gas surface-treated LDPE film and the untreated film according to an embodiment of the present invention (before and after the waveform separation (a) and separation (b)),

6 is an XPS F _1S spectrum of a fluorine mixed gas surface treated LDPE film and an untreated film according to an embodiment of the present invention,

FIG. 7 is a graph illustrating surface free energy, γ _S ^SP , and γ _S ^L of the fluorine mixed gas surface treated LDPE film and the untreated film according to the embodiment of the present invention.

Figure 8 is a graph showing the adhesion between the fluorine mixed gas surface treated LDPE film according to an embodiment of the present invention and the untreated film.

<Description of Signs of Major Parts of Drawings>

a: fluorine gas cylinder b: pressure gauge

c: buffer tank d: nitrogen gas cylinder

e: oxygen gas cylinder f: reactor

g: liquid nitrogen h: rotary vacuum pump

i: valve

The present invention relates to a method for producing a polyolefin-based film having excellent adhesion to metal. Specifically, the polyolefin-based film is surface treated with a fluorine / oxygen mixed gas to maintain polyolefin-based polymers while maintaining the properties such as good mechanical properties and excellent processability. The present invention relates to a method for producing a polyolefin film having improved adhesion to copper foil by effectively modifying only the surface of a polymer in a short time to increase surface free energy and introducing an oxygen functional group to the surface.

Surface modification methods of polymer include mechanical methods such as polishing and sand blast, chemical surface treatment using strong acid, low temperature plasma, corona discharge, physicochemical methods such as gamma irradiation, ultraviolet irradiation, and chemical methods such as ozone treatment. There are many ways. Among them, ozone treatment, plasma treatment, corona discharge, gamma irradiation, ultraviolet irradiation, and the like generate peroxides in addition to oxides such as ketones, so that it is known that graft copolymers can be introduced as an initiator. Surface modification using graft polymerization is a relatively well known technique, and some researchers are trying to graft polymerize hydrophilic monomers such as acrylamide on a series of polymer surfaces to increase wettability and apply them to medical applications. Attempts have also been made to graft polymerize glycidyl methacrylate (GMA) on surfaces to improve interfacial adhesion with epoxy resins.

On the other hand, polyolefin-based polymers have been used in a variety of industrial and everyday products by being directly bonded to aluminum foil or paper due to the low cost, good mechanical properties, excellent chemical resistance and excellent processability among various polymer materials. Since the 1970s, researches to improve the surface properties of polymers or to impart new functions to the surface of polymer materials by making the hydrophobic polyolefins hydrophilic have continued.

The study on the surface property modification of such polymers is to improve the paintability, printability, adhesion, wettability, etc. of the polymers. Chemical surface treatment using strong acid, UV or light irradiation, and low temperature plasma treatment are typical. However, the treatment equipment is expensive, or the generation of secondary contaminants and treatment conditions are not easy because they go through relatively many constraints and complex processes.

Therefore, in the present invention, as a result of studying to effectively modify only the surface of the polyolefin-based polymer in a short time while maintaining the properties such as good mechanical properties and excellent processability of the polyolefin-based polymer, surface treatment with a fluorine / oxygen mixed gas on the polyolefin-based film The present invention was completed by increasing the free energy of the film surface and introducing an oxygen functional group to the surface to prepare a polyolefin film having improved adhesion to a metal such as copper foil.

Accordingly, the present invention provides a method for producing a polyolefin-based film having improved adhesion, including surface treatment of a polyolefin-based film with a fluorine / oxygen mixed gas.

Hereinafter, the present invention will be described in detail.

Polyolefin-based film that can be applied to the method of the present invention is polyethylene, polypropylene and the like.

In the fluorine / oxygen surface treatment according to the present invention, the mixing ratio of fluorine and oxygen is preferably in the range of 1: 1 to 7 by volume (pressure ratio), and the treatment time is preferably 1 to 30 minutes. Even if the treatment time is short, greatly improved adhesiveness can be expected, but when more than enough adhesiveness can be exhibited, the adhesiveness also gradually increases as the treatment time increases, so about 30 minutes is preferable. However, the reason why the treatment is not preferable for a long time is that the generation of oxygen functional groups on the surface of the film is insufficient and the effect of improving the adhesion can no longer be expected.

The pressure of the process gas (a mixture of fluorine and oxygen) is suitably 10 to 100 kPa because fluorine gas is expensive and the desired adhesion can be obtained even in a small amount.

When surface treatment is performed with a fluorine / oxygen mixed gas according to the present invention, the surface free energy is increased by effectively modifying only the surface in a short time while maintaining the properties such as good mechanical properties and excellent processability of the polyolefin-based polymer, and oxygen functional groups on the surface. It is possible to introduce, the surface-modified polyolefin-based film according to the present invention can be significantly improved adhesion to not only metals such as copper foil but also substrates such as other resins.

The invention is described in more detail in the following examples, but the scope of the invention is not limited to the examples.

Each characteristic value in the Example was measured by the following method.

1. Surface Characteristics Analysis

The chemical composition of the film surface was analyzed using FTIR-ATR (HATR; MIDAC Co.) and XPS (ESCA LAB MKII; VG Scientific Co.). The X-ray light source used for the XPS measurement was using MgK _α at a 45 ° angle, the pressure in the chamber was adjusted to 1 × 10 ^-9 torr. The contact angle was measured using a Rame-Hart goniometer, and distilled water and diiodomethane were used as the wet liquid. Immediately after each specimen was produced in the standard state, the contact angle of the specimen was measured 10 times or more, and the average value was taken. Using this, the surface free energy of the film treated with the fluorine / oxygen mixed gas was obtained.

2. Adhesion Measurement (J / m ² )

In order to measure the adhesion of the copper foil, which is a metal, the copper foil was a 50 µm thick copper foil manufactured by Fukuda, Japan, and the epoxy resin used as the adhesive was diglycidyl of bisphenol A, a bifunctional epoxy oligomer. Ether (DGEBA, Kukdo Chemical Co., Ltd., YD-128, EEW = 185-190 g / mol, density 1.16 g / cm 3) was used, and the curing agent 4,4-diaminodiphenylmethane (DDM) was used. . The adhesive force of the polyolefin-based film / copper foil was measured for peel adhesion strength in accordance with ASTM 1876-72 using a universal testing machine (Universal Testing Machine, Lloyd LR5K). The adhesive specimens were measured after introducing epoxy as an adhesive between the polyethylene film and the copper foil and curing at 120 ° C. for 2 hours. The size and crosshead speed of the adhesive specimens were set to 30 × 100 mm ² and 200 mm / min, respectively.

Examples 1-4

In this embodiment, a low density polyethylene (LDPE; trade name XJ-700) on pellets containing no additives of Hyundai Petrochemical Co., Ltd. was formed to a thickness of about 200 μm using a thermocompressor.

Cut the prepared LDPE film into 8 × 8 cm ² , wash twice with ultrasonic waves in ethanol for 30 minutes, rinse several times with ethanol, and store in vacuum dry at room temperature until surface treatment of fluorine / oxygen mixed gas. It was.

The LDPE film was placed in a reactor of a fluorine / oxygen mixed gas treatment apparatus as schematically shown in FIG. 1 to treat its surface. Since fluorine gas is generally highly reactive with metallic materials, the reactor is made of stainless steel (sus) and nickel is used for the reactor. The pressure of fluorine and oxygen was adjusted equally to 30 kPa (fluorine and oxygen mixing ratio 1: 1), and the treatment time was treated for 1 minute, 2 minutes, 5 minutes, and 30 minutes, respectively.

The surface characteristics of the LDPE film prepared as described above are shown in FIGS. 2, 3, 4, 5, 6, 7 and Tables 1 and 2, compared with those of the conventional LDPE film without surface treatment. The measurement results are shown in FIG. 8. 2 to 7 are FTIR-ATR results, total XPS spectra and XPS C _1S spectra for the fluorine mixed gas surface treated LDPE film and the conventional LDPE film according to the embodiment of the present invention, respectively (before waveform separation (a) And (b)) after separation, XPS O _1S spectrum (before separation (a) and after separation (b)), XPS F _1S spectrum and surface free energy and γ _S ^SP , γ _S ^L is a graph showing the comparison.

(Unit: °) Milk Untreated Example 1 Example 2 Example 3 Example 4 water 78.1 59.8 56.1 53.7 52.0 Diiodomethane 51.6 36.1 40.0 40.9 42.1

As can be seen from the above, it can be seen that the increase and decrease of the surface free energy of the fluorine / oxygen mixed gas surface treatment specimens are greatly influenced by the polarity factor, as shown in the FTIR-ATR and XPS analysis. Oxygen-containing functional groups, such as CO, C = O, OCO, on the surface of LDPE film as the reaction time increases with O ₂ reactions of carbon radicals activated by fluorine radicals and O ₂ as well as CF bonds on the surface of oxygen-treated LDPE film It is observed that the result depends on the degree of introduction.

As a result, the peel adhesion strength of the film increased according to the treatment time of the fluorine / oxygen mixed gas, and in particular, the increase rate decreased rapidly within one minute after the start of the treatment. These results are as shown in the results of the contact angle measurement. According to the surface treatment of fluorine / oxygen mixed gas, the polar functional groups on the film surface developed rapidly after the reaction started, and then gradually increased and gradually increased the surface free energy of the polymer. It is observed that the wettability is improved and eventually the adhesion is increased, which suggests that the fluorine / oxygen mixed gas surface treatment according to the present invention is a technique capable of efficiently hydrophilizing hydrophobic materials in a short time.

The fluorine / oxygen mixed gas surface treatment according to the present invention can efficiently surface hydrophilize a polyolefin-based film in a short time, and the surface-modified polyolefin-based film according to the present invention has excellent adhesion with a metal.

Claims (5)

A conjugate of a polyolefin-based film and a metal thin film, wherein a polyolefin-based film treated with a mixed gas of fluorine and oxygen is bonded to a metal thin film. The method of claim 1, And wherein the polyolefin is selected from polyethylene and polypropylene. The method of claim 1, A conjugate according to claim 1, wherein the mixing ratio of fluorine and oxygen in the mixed gas is from 1: 1 to 7 by volume. The method of claim 1, And a processing pressure of the mixed gas of fluorine and oxygen in the range of 10 to 100 kPa. The method of claim 1, The conjugate, characterized in that the treatment time of the mixed gas of fluorine and oxygen ranges from 1 to 30 minutes.

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