JP2005330314A - Heat-resistant polyamide film and mold release film for electronic component and copper-clad laminate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To inexpensively prepare a highly heat-resistant polyamide crosslinked film having moderate rigidity and excellent shape stability without melting even at a temperature as high as 300°C while holding excellent characteristics (strengths, impact strength and chemical resistance) of a polyamide resin. <P>SOLUTION: The heat-resistant polyamide film is characterized as follows. A film composed of a polyamide resin composition containing (A) an aliphatic polyamide resin and (B) an electron beam crosslinking aid is crosslinked by irradiation of electron beams, and the dynamic modulus at 300°C is ≥0.5 MPa. Furthermore, the heat-resistant polyamide film is characterized as follows. A film composed of a polyamide resin composition containing (A) the aliphatic polyamide resin, (B) the electron beam cross-linking aid and (C) a hindered phenol heat stabilizer is crosslinked by irradiation of the electron beams, and the dynamic modulus at 300°C is ≥0.5 MPa. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a heat resistant film suitable for an electronic component crosslinked by irradiating an electron beam onto a film made of a polyamide resin composition. More specifically, the present invention relates to a release film suitable for a copper clad laminate having excellent rigidity, impact resistance and chemical resistance of polyamide resin, retaining rigidity even at high temperatures, and not melting and having excellent shape retention.

  In recent years, miniaturization and high performance have progressed mainly in information communication equipment, and the demand for heat resistant films as electronic component materials such as printed wiring board materials, semiconductor packaging materials and cable coating materials related to these fields has expanded. Yes. Among these electronic components, the flexible wiring board, the demand of which is expanding most rapidly, is required to have higher performance, higher functionality, and lower cost.

In the production of a copper clad laminate performed as a pre-process for manufacturing this flexible wiring board, the copper foil and the prepreg are bonded together by heating and pressurizing at the same time. In general, heating and pressing are performed with a release film sandwiched between the combinations. This release film does not melt in the heating and pressurizing step, and requires an appropriate rigidity. In addition, since the release film is discarded after the copper clad laminate is manufactured, it is not preferable to use an expensive heat-resistant film such as a polyimide film as the release film because the manufacturing cost is remarkably increased.
Conventionally, a film made of cellophane, polypropylene, poly-4-methyl-1-pentene or the like has been used as the release film. In particular, since poly-4-methyl-1-pentene has a high melting point of 235 ° C., it has been evaluated as a release film with few defects (for example, Patent Documents 1 and 2). However, in recent years, with the market demand for high-quality and inexpensive flexible wiring boards, the heating and pressing conditions in the manufacturing process of copper-clad laminates have become stricter, and a release film having higher rigidity at high temperatures has been demanded.
In addition, an inexpensive heat-resistant film that retains moderate rigidity up to nearly 300 ° C. is also demanded for electronic components other than a release film for manufacturing a flexible wiring board.
JP-A-57-70653 JP 2000-263724 A

  Accordingly, the present invention provides a low-cost polyamide film with high heat resistance that retains the excellent properties (strength, impact resistance, chemical resistance) of the polyamide resin and maintains appropriate rigidity even at a high temperature of 300 ° C. This is a problem.

  As a result of diligent research to solve the above problems, the present inventors have formed a film with a polyamide-based resin composition in which an electron beam crosslinking aid is blended with an aliphatic polyamide resin, and irradiates the film with an electron beam. As a result, it was found that the resin does not melt even at 300 ° C. and maintains an appropriate rigidity, and the present invention has been completed.

  That is, the present invention relates to (1) a film comprising a polyamide resin composition containing (A) an aliphatic polyamide resin and (B) an electron beam crosslinking aid, which is crosslinked by electron beam irradiation, and operates at 300 ° C. Heat-resistant polyamide film characterized by an elastic modulus of 0.5 MPa or more, (2) (A) an aliphatic polyamide resin, (B) an electron beam cross-linking aid, and (C) a hindered phenol heat stability A heat-resistant polyamide-based film characterized in that a film made of a polyamide-based resin composition containing an agent is crosslinked by electron beam irradiation and has a dynamic elastic modulus at 300 ° C. of 0.5 MPa or more, (3 (2) From the heat-resistant polyamide film according to any one of (1) and (2) above, which does not break at an elongation rate of 200%, (4) From the polyamide film according to any one of (1) to (3) That the electronic component release film and (5) a copper-clad laminate for release film of a polyamide-based film according to any one of 1 to 3.

  The crosslinked polyamide resin film in the present invention is a film in which an aliphatic polyamide resin is efficiently electron beam crosslinked together with an electron beam crosslinking aid, and not only maintains the excellent strength and impact resistance of the aliphatic polyamide resin. Since moderate rigidity can be maintained even at a high temperature of 300 ° C., it is particularly suitable as a release film used in a press-forming process of a copper clad laminate that is heated and pressurized at a high temperature. Further, it can be widely used in other electronic parts that require heat resistance.

The present invention will be specifically described below.
The aliphatic polyamide resin as the component (A) of the present invention has an acid amide bond (—CONH—) in the molecule, and specifically includes, for example, ε-caprolactam, 6-aminocaproic acid, ω-enanthate. Polymers or copolymers or blends obtained from lactam, 7-aminoheptanoic acid, 11-aminoundecanoic acid, 9-aminononanoic acid, α-pyrrolidone, α-piperidone, etc., hexamethylenediamine, nanomethylenediamine, undeca Examples include, but are not limited to, polymers or copolymers or blends obtained by polycondensation of diamines such as methylenediamine and dodecanemethylenediamine with dicarboxylic acids such as adipic acid and sebacic acid. It is not a thing.
In the present invention, the number average molecular weight of the (A) aliphatic polyamide resin is preferably 7,000 to 30,000. If the number average molecular weight is less than 7,000, toughness is lowered, which is not preferable. Moreover, when it exceeds 30,000, fluidity | liquidity will fall and it is unpreferable.

The electron beam cross-linking aid which is the component (B) of the present invention promotes the cross-linking of the aliphatic polyamide resin during electron beam irradiation. Specifically, for example, triallyl cyanurate (TAC), triallyl isocyania. Nurate (TAIC), trimethylallyl isocyanurate (TMAIC), trimethylolpropane trimethacrylate (TMPTA), trishydroxyethyl isocyanuric acrylate (THEICA), N, N'-m-phenylenebismaleimide (MPBM) Although a functional compound can be illustrated, it is not limited to these. These electron beam crosslinking aids may be used alone or in combination of two or more.
The compounding amount of the electron beam crosslinking aid is 0.01 to 10 parts by mass, preferably 0.03 to 8 parts by mass with respect to 100 parts by mass of the aliphatic polyamide resin. If it is less than 0.01 part by mass, the crosslinking does not proceed and the degree of crosslinking becomes low. On the other hand, if it exceeds 10 parts by mass, not only the efficiency as an electron beam crosslinking aid is deteriorated, but also the physical properties of the aliphatic polyamide resin are lowered, which is not preferable.

  The heat stabilizer which is the component (C) of the present invention is the heat of a compound having relatively poor thermal stability, such as an electron beam crosslinking aid, when kneading a polyamide-based resin, an electron beam crosslinking aid and other blends. The main purpose is to prevent deterioration, and there is no particular limitation as long as it is a hindered phenol-based heat stabilizer. Specifically, 2,6-di-t-butyl-4-methylphenol (BHT), tetrakis- [methylene-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate] methane (Ciba Geigy) Irganox (R) 1010), triethylene glycol-bis [3- (3-tert-butyl-4-hydroxy-5-methylphenyl) propinate] (Ciba Geigy, Irganox (R) 245), etc. However, it is not limited to these. These heat stabilizers can be used alone or in combination of two or more. The compounding quantity of a heat stabilizer is 0.05-5 mass parts with respect to 100 mass parts of polyamide-type resin compositions, Preferably it is 0.1-3 mass parts. If it is 0.05 parts by mass or less, there is no effect as a heat stabilizer, and if it is 5 parts by mass or more, the efficiency as a heat stabilizer is poor and it is not economical.

  In addition to (A) aliphatic polyamide resin, (B) electron beam crosslinking aid, and (C) heat stabilizer, the polyamide-based resin composition and film thereof according to the present invention are used in ordinary polyamide resin compositions. Carbon black and copper antioxidants and / or alkali metal halides, antioxidants, flame retardants, mold release agents, lubricants, crystal nucleating agents, antistatic agents, pigments, dyes, etc. Also good.

  As a method for producing a film comprising a polyamide resin composition in the present invention, it is preferable to first produce a kneaded pellet of a polyamide resin composition. Although the manufacturing method of this polyamide-type resin composition pellet is not specifically limited, It can manufacture using a common single screw extruder, a twin screw extruder, a pressure kneader, etc. as a kneading apparatus. In the present invention, the use of a twin screw extruder is particularly preferred. The kneading temperature is preferably 230 to 290 ° C. and the kneading time is preferably about 2 to 15 minutes. In addition, you may mix (A) aliphatic polyamide resin, (B) electron beam crosslinking adjuvant, and another additive in the extrusion process which melt-extrudes a film.

A film made of a polyamide-based resin composition can be produced by melt-extruding the above pellets and using a T-die method or an inflation method, but the apparatus for producing the film is not particularly limited. The film extrusion temperature is preferably about 230 to 300 ° C.
Although the thickness of a film changes with purposes, when using it as a release film, it is 5-500 micrometers. If it is less than 5 μm, there may be a problem in terms of handleability and mechanical strength. Since thickening is economically disadvantageous, it is not necessary to make it thicker than 500 μm.

The polyamide film of the present invention is obtained by irradiating an electron beam onto a film made of the polyamide resin composition and crosslinking.
Although the dose of electron beam irradiation varies depending on the type of polyamide resin composition and the thickness of the film, it is generally 20 to 400 kGy, and in particular, it is crosslinked at the minimum dose that can obtain the heat resistance of the intended crosslinked film. It is preferable to do.
In the crosslinked film by electron beam irradiation, the degree of crosslinking of the film surface layer directly hit by the electron beam is the highest, and the degree of crosslinking gradually decreases from the inner layer portion to the back surface. Since the film is thin, the difference in the degree of cross-linking between the surface layer and the back surface is relatively small. However, it is preferable to perform electron beam irradiation from both sides of the film in order to cross-link the entire film as uniformly as possible.

The film comprising the polyamide resin composition of the present invention is cross-linked between polyamide molecules by electron beam irradiation and does not melt even at a high temperature above the melting point, and can maintain the shape of the film, and at a high temperature of 300 ° C., 0.5 MPa. It has the above dynamic elastic modulus. Further, the film is crosslinked to such an extent that it does not dissolve even when immersed in formic acid, which is a solvent for aliphatic polyamide resin, and maintains the form of the film.
For example, even when a film (thickness 150 μm) is immersed in 98% formic acid at a temperature of 23 ° C. and an immersion time of 90 seconds, the film shape is maintained.

  Furthermore, the heat-resistant polyamide-based film of the present invention has a characteristic that it does not break even when stretched by 200% or more, despite being crosslinked. It is preferable that the film does not break even when stretched by 200% or more. The breaking elongation is preferably 300% or more and 600% or less. This cross-linking is a factor that develops rigidity at a high temperature above the melting point. The characteristics of the heat-resistant film of the present invention are obtained by this characteristic crosslinking.

EXAMPLES The present invention will be described in more detail with reference to examples below, but the present invention is not limited to these examples.
Moreover, each characteristic and physical property value shown in the following Examples and Comparative Examples were measured by the following test methods.
(1) Film thickness: It was measured using a micrometer (Mitutoyo Co., Ltd., MDC25S).
(2) Tensile strength at break and tensile elongation: Measured according to JIS K7161.
(3) Tensile impact strength: Measured according to JIS K7160.
(4) Dynamic viscoelasticity: It measured on the following test conditions using the test piece of width 5mm and thickness 0.15mm with the Toyo Sangyo Co., Ltd. "Rheogfl-E4000" test device.
Frequency: 1 Hz, heating rate: 3 ° C / min, measurement temperature range: 20-320 ° C
Initial load: automatic static load 200%, 25 gf.
(5) Formic acid solubility: The film was immersed in 98% formic acid to evaluate the solubility of the film (thickness 150 μm). Immersion temperature 23 ° C, immersion time 90 seconds.

(Examples 1-6, Comparative Examples 1-2)
<Raw materials used>
NY6 (manufactured by Toyobo Nylon T-850) and NY66 (manufactured by Asahi Kasei Co., Ltd., Leona (R) 1700) as an aliphatic polyamide resin and triallyl isocyanurate (Nippon Kasei) as an electron beam crosslinking aid A hindered phenol heat stabilizer (manufactured by Ciba Geigy, Irganox (R) B1171) was further used as a heat stabilizer.

<Manufacture of evaluation samples>
In the production of the evaluation sample, each raw material was weighed at a ratio shown in Table 1, mixed with a tumbler, and then kneaded at a temperature of 230 to 290 ° C. with a twin-screw extruder to obtain a polyamide resin composition pellet. A film of the polyamide-based resin composition was formed by extruding the pellets into a film shape with an extruder with a T die and casting the film on a rotating cooling roll. The cylinder temperature was 230-290 ° C. The film thickness was 150 μm.
A cross-linked film (also referred to as a cross-linked film) was obtained by irradiating an electron beam onto the above-mentioned polyamide resin composition film under the following electron beam irradiation conditions. The test piece for evaluating physical properties was produced by punching out a test piece having a shape according to JIS K7161 and K7160 from the crosslinked film obtained by the above-described method.

<Electron beam irradiation conditions>
Electron beam irradiation device: Dynamitron type 5 MeV electron accelerator manufactured by RDI Irradiation conditions: Voltage = 4.6 MeV, current = 20 mA
Irradiation dose: 50 kGy, 100 kGy
The evaluation results of the obtained crosslinked film are shown in Table 1.

  When the aliphatic polyamide is nylon 6 (also referred to as NY6), as is apparent from Examples 1 to 2, 5 and Comparative Example 1, the crosslinked film irradiated with the electron beam has excellent physical properties such as tensile breaking strength and tensile impact strength. In addition, the dynamic elastic modulus is 0.5 MPa or more, and an appropriate rigidity is maintained even at a high temperature of 300 ° C. On the other hand, in the film of Comparative Example 1 that has not been irradiated with the electron beam, the dynamic elastic modulus suddenly decreases from the vicinity of the melting point, and the flow of the evaluation sample occurs at a temperature lower than 300 ° C. When the aliphatic polyamide is nylon 66 (also referred to as NY66), as shown in Examples 3 to 4 and 6 and Comparative Example 2, the strength properties of the crosslinked film are improved by electron beam irradiation as in NY6, and at 300 ° C. The dynamic modulus of elasticity also maintains a rigidity of 0.5 MPa or more. Moreover, as shown in Examples 1-6, in the case of the crosslinked film irradiated with the electron beam, the film immersed in the formic acid solution does not dissolve and maintains the form of the film.

  The present invention is a heat-resistant polyamide resin film having an appropriate rigidity even at a high temperature of 300 ° C. and excellent in form stability, and is particularly suitable as a release film in a molding process of a copper clad laminate. In addition, it can be used as a heat-resistant film material for electronic parts that requires heat resistance, such as semiconductor package materials and cable coating materials, and greatly contributes to the industry.

Claims (5)

  A film made of a polyamide-based resin composition containing (A) an aliphatic polyamide resin and (B) an electron beam crosslinking aid is crosslinked by electron beam irradiation, and has a dynamic elastic modulus at 300 ° C. of 0.5 MPa or more. A heat-resistant polyamide film characterized by   A film made of a polyamide-based resin composition containing (A) an aliphatic polyamide resin, (B) an electron beam crosslinking aid and (C) a hindered phenol-based heat stabilizer is crosslinked by electron beam irradiation at 300 ° C. A heat-resistant polyamide-based film having a dynamic modulus of elasticity of 0.5 MPa or more.   The heat-resistant polyamide-based film according to any one of claims 1 and 2, wherein the heat-resistant polyamide-based film does not break at an elongation rate of 200%.   The release film for electronic components which consists of a polyamide-type film of any one of Claims 1-3.   The release film for copper clad laminated boards which consists of a polyamide-type film of any one of Claims 1-3.