WO2018041008A1

WO2018041008A1 - Polymer-based composite and preparation process thereof

Info

Publication number: WO2018041008A1
Application number: PCT/CN2017/098920
Authority: WO
Inventors: 韩辉升; 张红梅; 丁阳; 陈璐; 孙强; 施捷; 倪静娴; 陆婷
Original assignee: 南通万德科技有限公司
Priority date: 2016-08-30
Filing date: 2017-08-24
Publication date: 2018-03-08
Also published as: CN106409539A

Abstract

A polymer-based composite and a preparation process thereof, wherein a composite sheet is obtained by compositing and molding a metal sheet with a polymer, then holes perpendicular to a metal layer of the composite sheet are etched into the metal layer, while a polymer layer is not affected by etching. The etched metal layer is continuous. As the metal layer provided with holes is evenly coated on the polymer substrate, the thermal expansion of the polymer substrate would not cause the polymer substrate to protrude to a surface of the metal layer having a certain thickness; and, the thickness of the metal layer may cancel out the thermal expansion of the polymer substrate. Therefore, such a composite is applicable as an electrical contact material in various weather conditions.

Description

Polymer matrix composite material and preparation process thereof

Technical field

This invention relates to the field of composite materials and, more particularly, to conductive composite materials prepared from polymeric materials and metals which can be used to make electrical contacts, particularly electrical contacts in rubber keys.

Background technique

The layered composite conductive material of metal and polymer combines the electrical conductivity of the metal material with the ease of processing of the polymer. Patent Document "Rubber Conductive Particles and Preparation Method Therefor" of Application No. 201110027418.8 discloses a rubber conductive particle comprising a rubber substrate and a metal plating film on the surface thereof, the metal plating film covering the entire surface of the rubber substrate. Patent Document No. 201110193369.5, "Majiao Metal and Rubber Composite Conductive Particles" discloses a composite conductive particle obtained by bonding a ply surface metal surface layer having pits and bumps to a rubber substrate. A large pressure is generated under the same pressing force, and the conductive member as the button has relatively stable conductivity and relatively reliable electrical conductivity, but the conductive particles are generally hard and the overall mechanical strength is not easily regulated in a wide range.

The patent document "Composite Conductive Sheet" of Application No. 201010592410.1 discloses a composite conductive sheet composed of a polymer matrix and a metal foil compounded therein. The metal foil here refers to a nickel foil, a copper foil, an aluminum foil, a stainless steel foil, a gold foil, a silver foil or a woven mesh containing pores, and the polymer matrix refers to a silicone rubber, a nitrile rubber, an ethylene propylene rubber, a natural rubber, a rubber plastic material. , thermoplastics, thermosets or fiber reinforced plastics. It is worth noting that the holes or slits in the metal foil or woven mesh in the composite conductive sheet described in the invention are filled with a polymer matrix. When a composite material made of a continuous metal material and a polymer is used as an electrical contact, since the coefficient of thermal expansion of the polymer is usually much larger than that of a common metal material, sometimes even as high as ten times or more (for example, the coefficient of thermal expansion of the silicone rubber is about pure Nickel 15 times), when the temperature rises, the polymer material in these composite materials will protrude from the surface of the composite material due to a large coefficient of thermal expansion, so that the surface contact resistance of the electrical contact becomes large, and even the electrical contact may be made. Becomes non-conductive and completely ineffective. In fact, a button containing such an electrical contact, if used in a car, may create a safety problem.

Therefore, how to obtain a more reliable material for the electrical contacts used in the preparation of the keys, and how to effectively solve the problem of failure of the electrical contacts prepared from the composite of the polymer and the continuous metal material at high temperatures is production. What the industry needs urgently.

Summary of the invention

OBJECTS OF THE INVENTION The present invention provides a composite of metal and polymer whose overall hardness is easily adjusted for preparing a button electrical contact having reliable conduction performance, which is not raised under elevated temperature conditions. Failure, while also providing a method of preparing such an electrical contact.

Electrical contacts are a key component of the button and are typically used in conjunction with contact switches on printed circuit boards (PCBs). It must have a low contact resistance. If the contact resistance is too large, the key switch function will be invalid and misjudged.

The following is an example of a failure of the electrical contact conduction function: a composite made of rubber and sheet metal, as an electrical contact on a rubber button, when the temperature rises, such as from 25 ° C to 80 ° C, will The rubber swells and protrudes from the metal surface, which affects the conduction, as shown in Figure 1.

Technical Solution: The present invention discloses a composite material and electrical contacts prepared from the composite material, and a preparation process thereof: a polymer matrix of 0.01-10 mm thick and a metal layer of 0.005-2.0 mm thickness are laminated into a layer The composite sheet is then etched into the metal layer in the layered composite sheet such that the metal layer has one or more holes having a circumscribed circle diameter of 0.05 to 5 mm, and the shape of the hole is a circle, an ellipse, a triangle, a square , rectangular, polygonal or other geometric shapes, resulting in a composite material that can be used to make electrical contacts. The composite material is die cut or divided into circumscribed circle diameters. 1.0-10.0mm round, elliptical, square or other geometrical small pieces, each having one or more complete holes; the holes are perpendicular to the metal sheet, or between the hole axis and the metal sheet The angle is greater than 60°. This small piece can be used as a polymer based electrical contact on a button made of a polymer. Due to the presence of voids in the metal layer of the composite, the resulting polymer-based electrical contacts have good dust, particle and oil resistance properties.

Between the polymer substrate and the metal layer, there may be an adhesive layer having a thickness of less than 1 μm to increase the adhesion between the polymer substrate and the metal layer. If the polymer substrate itself has a good bond strength with the metal layer, it is not necessary to bond the polymer substrate and the metal layer with an adhesive layer.

The metal layer may be smooth or rough, or embossed. Specifically, the metal layer is made of a metal sheet having a surface roughness Ra of 0.025-100 on both sides or a single side, or a metal sheet having a bump, a convex surface, a concave point, a concave surface, a convex line or a concave line. The diameter of the circumscribed circle of the bump, the convex surface, the concave point and the concave surface is not more than 2.0 mm, and the width of the convex line and the concave line is not more than 2.0 mm.

For example, the metal layer is a hole type with a surface roughness Ra of 0.2 to 12.5, a thickness of 025-0.25 mm, a hole uniformly distributed in the metal layer, a hole diameter of 50 μm to 1.0 mm, and a hole pitch of 25 μm to 1.0 mm. A sheet of metal that is round, regular polygon or other geometric shape.

Metal mesh or sintered metal mesh having a mesh size of 80 mesh or more can also be used as the metal layer in the above composite material and polymer-based electrical contacts. The metal mesh or sintered metal mesh may be single layered, two layered or multilayered. Metal mesh or sintered metal mesh having a mesh size of less than 80 mesh is not suitable for use in preparing the polymer-based composite material described in the present invention. This is because they have too large a pore size to allow the polymer matrix to fill and penetrate the metal mesh or the sintered metal mesh.

The material of the metal layer can be various and can be composed of aluminum, iron, cobalt, nickel, copper, zinc, tin, titanium, manganese, tungsten, silver, gold or alloys thereof; the metal layer is made of homogeneous or a non-homogeneous metal material; further, the surface of the metal layer and the inner surface of the hole therein may have The metal-plated, metal-plated layer may cover, in whole or in part, the surface of the porous metal and the inner surface of the porous metal hole. Gold plating or silver plating is preferred. Gold and silver have relatively good electrical conductivity. As the outer layer of the metal material, the surface conductivity of the electrical contact can be improved, the contact resistance of the electrical contact can be reduced, and the electrical conductivity or service life of the electrical contact can be improved.

In the present invention, not only the material selection of the metal layer can be varied, but also the selection range of the polymer matrix is also broad. The polymer matrix can be prepared from thermoset rubber, thermoplastic rubber, thermoset plastics, thermoplastics, radiation curable materials, adhesives, inks or coatings.

Since many buttons are made of rubber, the polymer substrate in the polymer matrix composite can be prepared by rubber, and can be made of diene liquid rubber, olefin liquid rubber, polyurethane liquid rubber, acrylate. Prepared from liquid rubber, liquid polysulfide rubber, silicone-based liquid rubber, fluorine-based liquid rubber, or from the corresponding solid raw rubber of these categories.

The subsequent use of these composites should be considered when selecting the type of rubber. If these composite materials are used to make electrical contacts on the rubber keys, it should be understood which rubber is used to make the rubber keys have a good relationship between the electrical contacts and the key substrate during hot vulcanization or radiation curing. Bonding. The same kind of rubber is easy to heat vulcanize and bond. Polymer-based electrical contacts made from olefinic EPDM rubber can be used to prepare EPDM buttons containing polymer-based electrical contacts. Polymer-based electrical contacts made of silicone rubber can be used to make silicone rubber buttons containing polymer-based electrical contacts.

The formulation of the polymer matrix may contain various auxiliaries such as pigments, fillers or conductive fillers, etc., that is, the polymeric substrate may be electrically conductive. The polymeric substrate can be a conductive plastic, a conductive rubber, a conductive adhesive, a conductive ink, or a conductive coating. Conductive polymer substrates provide further assurance of the electrical conductivity of polymer-based electrical contacts.

The preparation process of the polymer matrix composite material in the invention is: the polymer is prepared by injection, lamination, pad printing, silk screen printing, brush coating, roller brush coating, blade coating, spray coating, dip coating, shower coating, and draw coating. And metal sheets Together, or by a thermoplastic molding process, a thermosetting molding process or a radiation curing process, a two-layer composite material composed of a polymer and a metal sheet is formed, and then the metal layer in the composite material is passed through an etching process. A hole having a diameter of 0.05-5 mm with one or more circumscribed circles is formed; the composite material obtained can be further die-cut or divided into circular, elliptical, square or other geometric shapes with a circumscribed circle diameter of 1.0-10.0 mm. Small pieces of shape, each containing more than one complete hole. This small piece can be used as an electrical contact for the button. Mechanical die cutting to prepare small pieces is a fast and efficient method. For special occasions, such as in the case of sample preparation or small batch production, laser segmentation can also be used.

The etching process is an important step in the preparation of polymer matrix composites. A wet etching process or a dry etching process can be employed. The wet etching process uses a chemical solution to remove a portion of the metal through a chemical reaction to form a hole, and the dry etching uses a plasma, an electron beam, or a laser to remove a portion of the metal to form a hole.

Advantageous Effects: The beneficial effects of the present invention are as follows:

(1) The electrical contact made of the polymer-based composite material prepared in the present invention has good electrical conductivity when the temperature is raised. As shown in Figure 1, the polymer-filled porous material, when steadily increasing, may protrude from the surface of the electrical contact due to the polymer having a higher coefficient of thermal expansion. Figure 2 shows that the electrical contacts of the present invention, in the case of elevated temperatures, such as from 25 ° C to 80 ° C, the thickness of the metal layer offsets the thermal expansion of the polymer, does not produce polymer protruding from the electrical touch The problem with the surface of the point.

(2) Compared with the surface-flat electrical contacts, the electrical contacts made of the polymer-based composite material prepared in the present invention can generate a large pressure under the same pressing force due to the presence of holes in the surface, thereby The conduction stability of the electrical contacts can be enhanced.

(3) The electrical contact made of the polymer-based composite material prepared in the present invention has certain dust resistance, particle resistance and oil stain resistance due to the hole on the surface of the electrical contact.

(4) The electrical contact made of the polymer-based composite material prepared in the present invention can be adjusted in a wider range, and the electrical contact can be made soft enough and has a certain service life. Electrical contact overall hardness Soft, can further increase the dust resistance of the electrical contacts.

In summary, the polymer-based composite material of the present invention and the electrical contacts thus produced have good conduction stability, good dust resistance and oil stain resistance, and at the same time, they can offset the polymer substrate. The large thermal expansion is therefore suitable for use under a variety of meteorological conditions and operating conditions.

DRAWINGS

1 is a schematic view showing the surface of a composite material prepared from a rubber and a metal mesh when the temperature is raised in the present invention; wherein, 1-silicon rubber, 2-metal mesh;

Figure 2 is a schematic view of the surface of the present invention in which thermal expansion does not cause the rubber to protrude from the porous metal; among them, 3-rubber, 4-porous metal.

detailed description

The invention will now be further described in conjunction with specific embodiments.

Example 1

A 0.2 mm thick stainless steel sheet having a surface roughness Ra of not more than 0.8 is treated with a primer or a binder (in this embodiment, a Chemlok 250 adhesive manufactured by Lord Chemical Co., Ltd.), and then ethylene propylene diene monomer. The rubber compound was heat-vulcanized to form a metal-rubber composite sheet having a total thickness of 1.0 mm. Etching with an etching solution containing ferric chloride, in the stainless steel of the composite sheet, the pore diameter of the stainless steel layer etched throughout the composite sheet is 0.4-0.6 mm, and the spacing of holes of any adjacent two holes is 0.2. A hole of -0.3 mm, the hole penetrates perpendicularly to the stainless steel sheet to obtain a polymer matrix composite. The composite sheet having the etched holes is then die cut into small wafers having a diameter of 1.5 to 5 mm to obtain polymer based electrical contacts that can be applied to the rubber keys. This polymer-based electrical contact provides low contact resistance under temperature altering conditions, especially at elevated temperatures. Even if the coefficient of thermal expansion of rubber is larger than that of metal, when the temperature rises, such as from 25 ° C to 80 ° C, the rubber will not protrude from the hole of the metal (as shown in Figure 2), and will not produce Figure 1. The phenomenon shown is that the electrical contact contact resistance rises. In addition, The polymer-based electrical contacts prepared in this embodiment also have good dust resistance, particle resistance and oil resistance, and the overall hardness of the electrical contacts is easily adjusted.

Example 2

A nickel-plated stainless steel sheet having a thickness of 0.1 mm coated with a nickel plating layer of 5 μm was applied. The roll was pressed into a sinusoidal corrugated sheet, and the total thickness of the sheet after rolling was 0.15 mm, and the distance between adjacent two peaks was 0.75 mm. The surface of the stainless steel sheet without nickel plating and the silicone rubber are thermally vulcanized and thermally vulcanized to form a metal-rubber composite sheet having a total thickness of 1.0 mm, and then laser etching is performed using only etching the metal without etching the silicone rubber. A polymer-based composite material was obtained by etching a hole having a hole diameter of 0.5 mm and a hole pitch of any adjacent two holes of 0.25 mm. The composite material having the etched holes is then die cut into small wafers having a diameter of 1.5 to 5 mm to obtain polymer-based electrical contacts that can be applied to the rubber keys. In such polymer-based electrical contacts, the holes in the metal layer, as well as the sinusoidal corrugations of the surface, contribute to the dust and oil repellency of the electrical contacts.

Example 3

In this embodiment, a photocurable material is selected to improve production efficiency. On a 200-mesh nickel wire mesh, a 50 μm thick UV-curable liquid silicone rubber containing 0.5-1% of adhesion promoter was screen-printed separately (Silopren UV LSR 2060 manufactured by Momentive Co., Ltd. in this example). And a UV-curable urethane acrylate adhesive (self-made), which is cured by appropriate UV light to cure the photocurable material to produce a composite sheet of nickel mesh. Then, using a plasma etching machine, the nickel mesh in the composite sheet is etched into a uniformly arranged square hole having a side length of 0.5 mm, and the distance between the square holes is 0.25 mm, thereby obtaining a polymer-based composite material. . The resulting composite was die cut into small discs of 2-5 mm diameter for use as electrical contacts for polymer buttons. The use of wire mesh as the metal layer in the electrical contacts facilitates the dust resistance and oil stain resistance of the electrical contacts.

Example 4

A one-component room temperature-curing silicone rubber ink was applied to the surface of a 0.1 mm thick fine-grained silver AgNi 0.15 sheet by knife coating. The dry film thickness of the ink layer was 0.25 mm. After completion of curing by exposure to air for 30 minutes, the pore pattern shown in Example 2 was etched with a silver etching solution containing hydrogen peroxide, and then the sheet was die-cut into small discs having a diameter of 3 mm or 5 mm. This small wafer is an electrical contact with good electrical continuity.

Example 5

The electrical contacts prepared in each of the above Examples 1, 2 and 3 were plated with an average thickness of about 0.2 μm in thickness by electroless plating on the metal surface and the inner surface of the hole in the electrical contact. More than 99.0% gold plating. Gold plating gives the electrical contacts a higher conductivity and a longer lifetime.

The present invention is not limited to the above-described preferred embodiments, and any other form of product can be derived by anyone of the present invention, but without any change in shape or structure, it is the same as or equivalent to the present application. Approximate technical solutions are all within the scope of the present invention.

Claims

A polymer-based composite material suitable for use in the preparation of electrical contacts, characterized in that the polymer-based composite material is a composite of a polymer matrix of 0.01-10 mm thick and a metal layer of 0.005-2.0 mm thickness. By etching the metal layer in the composite sheet of the metal sheet and the polymer, the metal layer has one or more holes having a circumscribed circle diameter of 0.05-5 mm, and is punched or divided into circumscribed circle diameters. Prepared from 1.0-10.0mm round, elliptical, square or other geometrical pieces; each small piece has one or more complete holes; the holes are perpendicular to the metal sheet, or the hole axis and the metal sheet The angle between the holes is greater than 60°; the shape of the holes is circular, elliptical, triangular, square, rectangular, polygonal or other geometric shape; between the polymer substrate and the metal layer, or having a thickness of less than 1 μm Mixture layer.
The polymer matrix composite according to claim 1, wherein the metal layer is made of a metal sheet having a surface roughness Ra of 0.025-100 on both sides or a single side, or has a bump. a convex sheet, a concave surface, a concave surface, a convex line or a concave line made of a metal sheet; the circumscribed circle of the convex point, the convex surface, the concave point and the concave surface has a diameter of not more than 2.0 mm, and the width of the convex line and the concave line is not more than 2.0mm.
The polymer matrix composite according to claim 1, wherein the metal layer has a surface roughness Ra of 0.2 to 12.5 and a thickness of 0.025 to 0.25 mm, and the pores are uniformly distributed in the metal layer, and the pore diameter is A metal sheet having a hole shape of 25 μm to 1.0 mm and a hole pitch of 25 μm to 1.0 mm and having a circular shape, a regular polygon or other geometric shape.
The polymer-based composite material according to claim 1, wherein the metal layer in the polymer-based composite material is prepared from a metal mesh of 80 mesh or more or a sintered metal mesh.
The polymer matrix composite according to claim 1, wherein the metal layer is made of aluminum, iron, cobalt, nickel, copper, zinc, tin, titanium, manganese, tungsten, silver, gold or the like. The metal layer is composed of a homogeneous or non-homogeneous metal material; the metal layer or metal plating layer; the metal plating layer is completely or partially covered with the metal layer. Surface and metal layer holes Inner surface.
The polymer matrix composite according to claim 1, wherein the polymer matrix in the polymer matrix composite is composed of a thermosetting rubber, a thermoplastic rubber, a thermosetting plastic, a thermoplastic, a radiation curing material, and a binder. , ink or paint preparation.
The polymer matrix composite according to claim 1 or 6, wherein the polymer matrix is composed of a diene liquid rubber, an olefin liquid rubber, a polyurethane liquid rubber, an acrylate liquid rubber, or a liquid. Made of polysulfide rubber, silicone-based liquid rubber, fluorine-based liquid rubber, or prepared from the corresponding solid raw rubber of these categories.
The polymer matrix composite according to claim 7, wherein the polymer matrix is a conductive plastic, a conductive rubber, a conductive adhesive, a conductive ink or a conductive paint.
The invention relates to a process for preparing a polymer matrix composite according to claim 1, which is characterized by: injection, lamination, pad printing, silk screen printing, brush coating, roller brushing, blade coating, spray coating, dip coating, and shower coating. The method of drawing, the polymer and the metal sheet are together, or cured by a thermoplastic molding process, a thermosetting molding process or a radiation curing process to form a two-layer composite sheet composed of a polymer and a metal sheet. Then, the metal layer in the composite sheet is formed into one or more holes having a diameter of 0.05-5 mm by an etching process; the prepared composite sheet is further punched or divided into a circumscribed circle having a diameter of 1.0. - 10.0 mm round, oval, square or other geometrical small pieces; each piece contains more than one complete hole.
The process for preparing a polymer-based composite material according to claim 9, wherein the etching process is a wet etching process or a dry etching process; and the wet etching is performed by using a chemical solution through a chemical reaction. A part of the metal is removed to form a hole, and the dry etching is to form a hole by removing a part of the metal by using a plasma, an electron beam or a laser.