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JP-7857217-B2 - Film, laminate, method for manufacturing laminate

JP7857217B2JP 7857217 B2JP7857217 B2JP 7857217B2JP-7857217-B2

Inventors

  • 和田 倫明

Assignees

  • アウロステクノロジーズ合同会社

Dates

Publication Date
20260512
Application Date
20210513
Priority Date
20200513

Claims (4)

  1. A layer (Layer A1) consisting of an unstretched, low-crystallinity, high-adhesion polyphenylene sulfide film, the crystallinity measured by X-ray diffraction is 20% or less, the water contact angle of both surfaces is 45° or less, and both the longitudinal thermal shrinkage (%) and transverse thermal shrinkage (%) determined by the following thermal shrinkage measurement method are 1% or less. (Method for measuring thermal shrinkage rate) From the above-mentioned unstretched, low-crystallinity, high-adhesion polyphenylene sulfide film, a square (100 mm × 100 mm × 0.025 mm) test specimen is cut out, and the lengths of the four sides (two vertical sides: l1, l2 and two horizontal sides: l3, l4) (l1b, l2b, l3b, l4b) are measured. Next, the test specimen is hot-pressed at 200°C under a load of 2 MPa for 10 minutes. After hot-pressing, the lengths of the four sides of the test specimen (l1a, l2a, l3a, l4a) are measured. The thermal shrinkage rate in the vertical direction (%) and the thermal shrinkage rate in the horizontal direction (%) are calculated according to the following formula. • Thermal shrinkage rate in the vertical direction (%) = ((l1b - l1a) + (l2b - l2a)) ÷ (l1b + l2b) × 100 • Transverse thermal shrinkage rate (%) = ((l3b - l3a) + (l4b - l4a)) ÷ (l3b + l4b) × 100 And, It includes a layer (layer B) made of copper foil having at least one surface roughness (Rz) of 0.7 μm or more and 1.2 μm or less, Both surfaces of the above-mentioned unstretched, low-crystallinity, high-adhesion polyphenylene sulfide film, where the water contact angle is 45° or less, are in contact with at least one surface of the above-mentioned copper foil, where the surface roughness (Rz) is 0.7 μm or more and 1.2 μm or less. Laminate (L1).
  2. A layer (Layer A2) consisting of crystallized material of an unstretched, low-crystallinity, high-adhesion polyphenylene sulfide film, the crystallinity of which is measured by X-ray diffraction is 20% or less, the water contact angle of both surfaces is 45° or less, and both the longitudinal heat shrinkage rate (%) and transverse heat shrinkage rate (%) determined by the following heat shrinkage rate measurement method are 1% or less. (Method for measuring thermal shrinkage rate) From the above-mentioned unstretched, low-crystallinity, high-adhesion polyphenylene sulfide film, a square (100 mm × 100 mm × 0.025 mm) test specimen is cut out, and the lengths of the four sides (two vertical sides: l1, l2 and two horizontal sides: l3, l4) (l1b, l2b, l3b, l4b) are measured. Next, the test specimen is hot-pressed at 200°C under a load of 2 MPa for 10 minutes. After hot-pressing, the lengths of the four sides of the test specimen (l1a, l2a, l3a, l4a) are measured. The thermal shrinkage rate in the vertical direction (%) and the thermal shrinkage rate in the horizontal direction (%) are calculated according to the following formula. • Thermal shrinkage rate in the vertical direction (%) = ((l1b - l1a) + (l2b - l2a)) ÷ (l1b + l2b) × 100 • Transverse thermal shrinkage rate (%) = ((l3b - l3a) + (l4b - l4a)) ÷ (l3b + l4b) × 100 Furthermore, it includes a layer (layer B) made of copper foil having a surface roughness (Rz) of at least one side of 0.7 μm or more and 1.2 μm or less. Both surfaces of layer A2 and at least one surface of the copper foil having a surface roughness (Rz) of 0.7 μm or more and 1.2 μm or less are in close contact. The peel strength measured in the 180-degree peel test between layer A2 and layer B is 4 N/cm or more . Laminate (Laminate L2).
  3. A product comprising the laminate (L2) described in claim 2 .
  4. A method for manufacturing a laminate, comprising the following steps 1, 2, and 3. (Step 1) First, a low-crystallinity polyphenylene sulfide film is prepared, mainly composed of polyphenylene sulfide resin, with a crystallinity of 20% or less as measured by X-ray diffraction. Next, at least one surface of the low-crystallinity polyphenylene sulfide film is subjected to plasma treatment. A process for producing an unstretched, low-crystallinity, high-adhesion polyphenylene sulfide film, in which polyphenylene sulfide resin is the main component, the degree of crystallinity measured by X-ray diffraction is 20% or less, the water contact angle of both surfaces is 45° or less, and both the longitudinal thermal shrinkage rate (%) and transverse thermal shrinkage rate (%) determined by the following thermal shrinkage rate measurement method are 1% or less. (Method for measuring thermal shrinkage rate) From the above-mentioned unstretched, low-crystallinity, high-adhesion polyphenylene sulfide film, a square (100 mm × 100 mm × 0.025 mm) test specimen is cut out, and the lengths of the four sides (two vertical sides: l1, l2 and two horizontal sides: l3, l4) (l1b, l2b, l3b, l4b) are measured. Next, the test specimen is hot-pressed at 200°C under a load of 2 MPa for 10 minutes. After hot-pressing, the lengths of the four sides of the test specimen (l1a, l2a, l3a, l4a) are measured. The thermal shrinkage rate in the vertical direction (%) and the thermal shrinkage rate in the horizontal direction (%) are calculated according to the following formula. • Thermal shrinkage rate in the vertical direction (%) = ((l1b - l1a) + (l2b - l2a)) ÷ (l1b + l2b) × 100 • Transverse thermal shrinkage rate (%) = ((l3b - l3a) + (l4b - l4a)) ÷ (l3b + l4b) × 100 (Step 2) A process for producing a laminate (laminated L1) comprising a layer (layer A1) made of the above-mentioned unstretched, low-crystallinity, high-adhesion polyphenylene sulfide film, and a layer (layer B) made of copper foil having a surface roughness (Rz) of 0.7 μm or more and 1.2 μm or less, A step of stacking the unoriented, low-crystallinity, high-adhesion polyphenylene sulfide film and the copper foil such that both surfaces of the unoriented, low-crystallinity, high-adhesion polyphenylene sulfide film, where the water contact angle is 45° or less, are in contact with at least one surface of the copper foil, where the surface roughness (Rz) is 0.7 μm or more and 1.2 μm or less. (Step 3) A process for manufacturing a laminate (laminated L2) comprising a layer (layer A2) made of a crystallized product of the above-mentioned unstretched, low-crystallinity, high-adhesion polyphenylene sulfide film, and a layer (layer B) made of copper foil having at least one surface roughness (Rz) of 1.2 μm or less, wherein both surfaces of layer A2 and at least one surface of the copper foil having a surface roughness (Rz) of 0.7 μm or more and 1.2 μm or less are in close contact, and the peel strength measured in a 180-degree peel test between layer A2 and layer B is 4 N/cm or more , A step of heating the laminate L1 under pressure to a temperature in the range of 150°C to 190°C, which is above the crystallization temperature of the unstretched, low-crystallinity, high-adhesion polyphenylene sulfide film.

Description

The present invention relates to a film, a laminate, and a method for manufacturing a laminate. Specifically, it relates to a novel low-crystallinity, high-adhesion polyphenylene sulfide film, a laminate having a layer made of the low-crystallinity, high-adhesion polyphenylene sulfide film and a layer made of copper (hereinafter referred to as "laminated L1"), a laminate obtained by heat-pressure treatment of laminate L1 (hereinafter referred to as "laminated L2"), and a method for manufacturing laminate L2. Polyphenylene sulfide (hereinafter referred to as "PPS") is known as an engineering plastic. Polyphenylene sulfide (PPS) has a structure in which 1,4-phenylene groups and sulfur atoms are alternately repeated, and is a thermoplastic crystalline resin with excellent heat resistance. PPS has a high melting point (280°C), and in addition to exhibiting excellent mechanical strength, rigidity, and dimensional stability through filler filling and alloying, it possesses the moldability characteristic of thermoplastic resins. As a high-heat-resistant engineering plastic, its applications are expanding, mainly as a substitute for metals and thermosetting resins. The electrical properties of PPS have attracted particular attention in recent years. The dielectric loss tangent, which is an indicator of electrical insulation when an AC voltage is applied, is significantly smaller than that of other engineering plastics. Furthermore, due to its high heat resistance and low water absorption, PPS exhibits excellent insulation even under high temperature and high humidity conditions (Non-Patent Literature 1). However, because the surface of PPS film lacks reactive groups such as hydroxyl groups (-OH) and carboxyl groups (-COOH), it exhibits poor adhesion to dissimilar materials such as other thermoplastic resins, metals, and glass. Adhesives are known as a means of firmly bonding PPS film to dissimilar materials. Examples include bonding PPS film to copper foil using a polyimide adhesive (Patent Document 1) and bonding PPS film to polyolefin using an adhesive made of polyolefin grafted with specific ethylenically unsaturated monomers (Patent Document 2). However, such adhesive bonding methods have problems, including the need for various adhesives depending on the materials being bonded, resulting in limited versatility; increased costs associated with adhesive use; increased overall product size due to the adhesive layer; and the influence of the adhesive layer on the overall product's properties such as shape retention and strength. Another method for firmly bonding PPS film to dissimilar materials is so-called surface roughening. In this method, the bonding surface of the PPS film is either physically treated beforehand with plasma treatment or corona discharge treatment, or chemically treated beforehand with acid or alkali (Patent Document 3). Since such surface roughening does not require a new material layer such as an adhesive layer, it is suitable for manufacturing laminates that require thin and precise structures. In particular, laminates containing a PPS film layer and a copper foil layer are useful as materials for high-frequency circuits. In the manufacture of such laminates, typically, a pre-plasma-treated PPS film and copper foil are stacked and then pressurized at a high temperature (typically around the melting point of the PPS film: approximately 280°C or higher) to make the PPS film layer and the copper foil layer adhere to each other (Patent Document 4). However, this method tends to have high energy costs for heating and pressurizing, and moreover, the equipment that can be used at such high temperatures is limited. In recent years, while the performance of electronic devices has been steadily increasing, there has also been a strong demand for lower costs for electronic devices and their components. Laminates containing PPS film layers and copper foil layers, which are widely used in electronic devices, require both high performance and low cost. However, since performance and manufacturing cost are inherently in a trade-off relationship, solving these challenges is not easy. Synthetic Chemistry of High-Purity Polyphenylene Sulfide, Kenichi Koyanagi, ENEOS Technical Review Vol. 59, No. 1 (February 2017) Japanese Patent Application Publication No. 9-55334Japanese Patent Publication No. 2003-268051Japanese Patent Publication No. 2003-39595Japanese Patent Publication No. 2011-253958 An example of the low-crystallinity, high-adhesion polyphenylene sulfide film of the present invention and an example of the copper foil used in the present invention are schematically shown.An example of the laminate L1 of the present invention is schematically shown.An example of the laminate L2 of the present invention is schematically shown. [Low Crystallinity, High Adhesion PPS Film] One of the features of this invention is the use of a low crystallinity, high adhesion polyphenylene sulfide film (hereinafter referred