JPH01285331A - Glass fiber reinforced composite body for molding airtight product - Google Patents

Abstract

PURPOSE:To obtain a molded product having airtightness and high strength with a simple composition, by impregnating a mat-shaped glass fiber with a resin based on a crystalline ethylene/propylene random copolymer. CONSTITUTION:A mat shaped glass fiber is prepared by accumulating strands each obtained by bundling glass fibers having a filament diameter of 3-30mum in an almost non-oriented state and forming the same into a mat shape by needle punching and a glass fiber mat obtained by parallelly arranging glass fiber rovings in order to provide directionality if necessary and arranging the same on the strands to perform needle punching may be also used. As a crystalline ethylene/proplylene random copolymer to be infiltrated in the glass fiber mat, one containing 2-6wt.% of ethylene is used and, when the content of ethylene is below 2wt.%, the airtightness of a molded product is not secured and, when exceeds 5wt.%, physical properties or thermal deformation temp. are lowered. The content of the mat-shaped glass fiber is pref. 35-60wt.% and, when said content is below 35wt.%, physical properties such as bending strength or the like become insufficient and, when 60% of more, glass fibers are exposed to the surface of the molded product or the airtightness of the molded product becomes inferior.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a glass fiber reinforced composite for molding airtight products, and is particularly suitable for compression molding of products that require airtightness, such as sleeves for communication cable connections. Relating to glass fiber reinforced composites.

(Prior Art) A composite material in which matte long glass fibers are impregnated with a thermoplastic resin is used as a base plate for mechanical stamping presses, a so-called stampable sheet.

Stampable sheets of this type that use polypropylene resin as thermoplastic resin are being considered for use in various press-formed products due to their light weight, chemical resistance, impact resistance, and low cost. ing.

However, although such conventionally known polypropylene composite materials are sufficient in terms of mechanical strength and impact resistance,
When a press-molded product is used in a sealed state from the outside, such as in a sleeve for a communication cable connection, there is a problem with airtightness.

For this reason, when obtaining molded products that require performance such as gas sealing or moisture proofing, the base plate is matte glass fiber with 10 to 20% by weight of talc or mica.
(Japanese Unexamined Patent Publication No. 61-185019), impregnated with polypropylene resin containing modified polypropylene (Japanese Unexamined Patent Publication No. 62-68823), or a metal plate or metal foil on the surface of the molded product during molding. A method of pasting a non-breathable material (Japanese Patent Laid-Open No. 61-86245) has been proposed, but all of these original plates and methods have the following technical problems.

(Problems to be Solved by the Invention) In other words, the first original plate has satisfactory airtightness, but since talc or mica is added to the plate in an amount of approximately 15% by weight, the glass fiber content is approximately 25% by weight. hand,
It has the disadvantage of lower bending strength and tensile strength than ordinary stampable sheets with a glass fiber weight content of 40%, and is unsatisfactory in terms of strength as a connection sleeve for cables buried directly in the soil. be. On the other hand, with the second master plate using modified polypropylene, if the molten modified polypropylene resin adheres to a metal impregnation pressure device during the manufacturing process of the master plate, the master plate will adhere to the impregnation pressure device, resulting in operational problems. The third method, in which a metal plate or metal foil is attached during molding, has the problem of causing trouble, and requires lamination of an adhesive layer to the metal plate or metal foil, preliminary compression molding, etc. prior to compression molding. However, since the number of steps is increased or the surface metal material needs to be placed in a fixed position during molding, a peripheral edge clamping device is required, which complicates the manufacturing process.

The present invention has been made in view of the above-mentioned problems, and includes:
The purpose is to provide a glass fiber-reinforced composite that can produce a molded article having airtightness and high strength with a simpler composition compared to known glass fiber-reinforced composites.

(Structure of the Invention) The structure of the present invention for achieving the above object is that in a glass fiber reinforced composite made of glass fiber and synthetic resin,
It is characterized in that it is made by impregnating matte glass fibers of 35 to 60% by weight of the total weight with a resin whose main component is a crystalline ethylene-propylene random copolymer having an ethylene content of 2 to 6% by weight.

To explain in more detail, the matted glass fiber that can be used in the present invention is formed by needle punching strands of glass fibers each having a diameter of 3 to 30 strands, which are assembled in a substantially non-oriented manner. It may also be a glass fiber mat in which glass fiber rovings are arranged in parallel and arranged on the strands and punched in order to give directionality to the glass fibers if necessary.

The crystalline ethylene-propylene random copolymer to be impregnated into the glass fiber mat is a copolymer of propylene and ethylene, and in the present invention, the ethylene content in the ethylene-propylene random copolymer is in the range of 2 to 6% by weight. are preferably used.

If the ethylene content is less than 2% by weight, the airtightness of the molded product cannot be ensured, and if it exceeds 6% by weight, the physical properties and heat distortion temperature will decrease.

In addition, the content of the above-mentioned matte glass fiber is 35 to 60
If the amount is less than 35% by weight, physical properties such as bending strength will be insufficient, and if it is more than 60% by weight, glass fibers will stand out on the surface of the molded product, resulting in surface defects or poor airtightness.

(Example) The present invention will be explained below with reference to Examples.

・Example 1 A mat in which glass fiber strands with a single diameter of about 23 μs were layered in a spiral shape was needle-punched at a rate of about 25 times per 1 c. A crystalline ethylene-propylene random copolymer is supplied in a molten state from a melt extruder, and pre-formed sheets of the same crystalline ethylene-propylene random copolymer with a thickness of approximately 0.5 m+s are overlaid on the top and bottom of the glass fiber mat. The glass fiber mat is supplied as a material and heated under pressure on a pair of upper and lower steel conveyors to impregnate the resin into the glass fiber mat, which is subsequently cooled and solidified to have a glass fiber content of 40% by weight.
A glass fiber reinforced composite original plate having a basis weight of 4,400 g/rd and a thickness of 3° and 7 fins was obtained.

The original plate of this glass fiber reinforced composite is 333 x 168 mm.
The blank was cut to the size of , heated until the internal resin temperature reached 200℃, stacked 3 sheets, and fed into a compression molding machine with a mold clamping force of 120 tons and a mold cooling time of 60 seconds. Pressure molded at a mold temperature of 80℃, length 380mm
, outer diameter 130mm.

A semi-cylindrical shape with a wall thickness of 6 mm and a width of 20 mm and a thickness of 10 mm on both sides.
A semi-cylindrical container with i+m flanges was molded.

The airtightness of the obtained semi-cylindrical container was confirmed by the following method.

Two of the above-mentioned semi-cylindrical containers were prepared, their flanges were butted against each other with rubber gaskets interposed therebetween, and the containers were pressed at multiple locations with clamps to assemble into a sealed container.

1゜5k from the gas supply port previously set up inside.
This was immersed in a water tank while applying an air pressure of g/c-, and the presence or absence of leakage of the internal pressurized air was determined by visually inspecting the presence or absence of air bubbles adhering to the surface of the semi-cylindrical container. No air bubbles were observed during the 24 hour test. Also, it can be heated from -30℃ to 80℃ while assembled.
After performing the heat cycle 10 times, a test was conducted under the same conditions as above, but as above, no air bubbles were observed.

On the other hand, the physical properties of the molded products were measured by the following methods. Tensile strength ASTM D638, bending strength ASTM D
790, Izod impact strength ASTM D256, heat distortion temperature ASTM D648 (load: 18.6 kg) The results of measurements by these methods are summarized in Table 1.

Comparative Example 1 Using the same glass fiber mat as the glass mat in Example 1, using a homopolymer of polypropylene resin as the overlay and melt thermoplastic resin,
A glass fiber reinforced composite (assigned by Asdel P11378K) was obtained in the same manner as in Example 1, and this was compression molded to obtain a semi-cylindrical container.

When this semi-cylindrical container was tested for airtightness in the same manner as in Example 1, it was found that air bubbles were significantly attached to the surface of the container, making it unsuitable for molded products requiring airtightness.

Comparative Example 2 Two glass fiber mats with a basis weight of 540 g/d were used, and 20% by weight of talc was added to the same crystalline ethylene-propylene random copolymer (A) as in Example 1 as the resin for the overlay sheet. As a melt resin, the crystalline ethylene-propylene random polymerized post ethylene-propylene block copolymer (B) with a total ethylene content of 5.5% by weight was used as the melt resin.
) with γ-methacryloxypropyltrimethoxysilane and t-butylperoxybenzoate in the above (B).
Modified polypropylene (C) obtained by adding 0.5 parts and 10.25 parts of each to 100 parts by weight and heat-treating at 220°C,
and talc (D) were kneaded in A:C:D-2:2:1, and the weight ratio of overlay sheet and melt was 1=2, the glass content was 25% by weight, and the talc content was 25% by weight. An original plate of a 15% by weight fiber-reinforced composite was prepared, and compression molding was performed in the same manner as in Example 1 using this original plate. As shown in Table 1, the molded product of this comparative example had excellent airtightness, but was poor in bending strength, tensile strength, and Izod impact strength.

In addition, in this comparative example, there was a problem in which the modified polypropylene of the melt protruded from the edge of the original plate during the manufacturing process of the original plate and adhered to the conveyor.

Usually, in a molded product having a rib shape, only about half the height (depth) of the rib is filled with glass fibers, and the tip portion becomes resin-rich, causing a problem of cracking.

Therefore, using each original plate of Example 1 and Comparative Example 1,
A flat plate with a thickness of 3m111, a width of 150+am, and a length of 200mm, with a width of 4am and a height of 20mm in the center of the - side.
A ribbed test piece with ribs of −
A falling ball impact test was conducted in an atmosphere of 30°C using a falling ball with a tip radius of 2.5 mm, and the result was 500 kg-(7)
In the case of molding using the original plate of Comparative Example 1 with an energy of On the other hand, in the original plate of Example 1, no cracks were generated due to the impact of the falling ball.

In addition, the above ribbed test piece was subjected to a heat cycle test of -30°C to 80°C 10 times, but no cracks were observed in the rib portion of the original plate of Example 1, indicating that it was sufficiently cold resistant. It was confirmed that it has.

Table 1 (effects) It is not clear why airtightness improves when a crystalline ethylene-propylene random copolymer with an ethylene content of 2 to 6% by weight is used, but hot blanks heated during compression molding After compression molding, the crystallization rate of the crystalline ethylene-propylene random copolymer when it is cooled and solidified in the mold is relatively slow, resulting in better adhesion between the glass fibers and the resin, making it less difficult to use than conventional products. This seems to be because gas is prevented from leaking around the glass fibers.

In addition, the composite of the present invention has a high content of long fiber glass fiber mat without adding inorganic fillers such as talc, so it can improve mechanical properties and the resin has good cold resistance and resistance. Since it has impact resistance, it is suitable for molded products having a rib shape.

The glass fiber reinforced composite for molding airtight products of the present invention is extremely useful for molding sleeves for communication cable connections, which require airtightness and high strength.

Patent applicant Ube Nitto Kasei Co., Ltd. Representative
People Patent Attorney - Color Ken Axis Patent Attorney Masatoshi Matsumoto

Claims (1)

[Claims] (1) In a glass fiber reinforced composite made of glass fiber and synthetic resin, a crystalline ethylene-propylene random copolymer with an ethylene content of 2 to 6% by weight is added to 35 to 60% by weight of the total weight of matted glass fibers. A glass fiber reinforced composite for molding airtight products, characterized by being impregnated with resin as the main component.