JPH03220245A - Fibrous reinforcing filler for thermoplastic resin - Google Patents

Abstract

PURPOSE:To prepare an inorg. fibrous filler which is used for reinforcing a thermoplastic resin, has a flowability, and is excellent in the dispersibility by forming an inorg. short-fiber material having a specified mean fiber diameter into a square sheet having a specified side length. CONSTITUTION:An inorg. short-fiber material (e.g. glass fiber) having a mean fiber diameter of 2mum or lower is formed into a square sheet having a side length of 1-30mm by the Fourdrinier or cylinder papermaking method. The resulting sheet is used as an inorg. fibrous filler for reinforcing a thermoplastic resin (e.g. polyethylene). Unlike the traditional inorg. short-fiber filler having a mean fiber length of 2mum or lower and no flowability, the sheet has a flowability, and can be homogeneously dispersed in a thermoplastic resin when mixed into the resin being extruded on an extruder without agglomerating or scattering.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a filler for fiber-reinforced thermoplastic resins that is blended into thermoplastic resins.

(Prior Art) Fiber-reinforced thermoplastic resins in which inorganic short fibers such as glass fibers are blended as fillers with thermoplastic resins such as polycarbonate and polyethylene have been known. To produce the fiber-reinforced thermoplastic resin, the thermoplastic resin and inorganic short fibers are mixed in a V-blender or the like, and then extruded in a -screw or twin-screw extruder to produce a pellet-shaped fiber-reinforced thermoplastic resin. Alternatively, inorganic short fibers are fed into the extruder during extrusion of thermoplastic resin with a single-screw or twin-screw extruder, and the thermoplastic resin and inorganic short fibers are mixed to produce a pellet-shaped fiber-reinforced thermoplastic resin. Ta. Thereafter, the pellet-shaped fiber-reinforced thermoplastic resin is injection molded using, for example, an injection molding machine, as necessary, to produce a molded article.

(Problem to be solved by the invention) However, the average fiber diameter obtained by cutting long glass fibers as an inorganic fiber filler to be blended into a thermoplastic resin is
When using a chipped strand consisting of filaments with a diameter of 3 μm and an average fiber length of 2 to 201 snow, it can be mixed uniformly into thermoplastic resin, but due to the fiber shape of the relatively large diameter filaments, molding is difficult. Fiber-reinforced thermoplastic resin molded products have a large anisotropy in mold shrinkage rate and may warp, making them unsuitable for applications that require dimensional accuracy. Roughness (
There was a problem that the appearance of the product was impaired due to the floating of fibers.

In addition, in order to improve the anisotropy of the molding shrinkage rate of fiber-reinforced thermoplastic resin molded products, attempts were made to use the above-mentioned inorganic fiber filler together with spherical glass fillers such as glass beads and glass balloons. However, there were problems in that not only the desired mechanical strength could not be obtained, but also the appearance could not be sufficiently improved.

Therefore, the present applicant previously proposed in Japanese Patent Application No. 167,700/1983 a composition with excellent appearance, low anisotropy in molding shrinkage rate, and high mechanical strength. We proposed a thermoplastic resin composition containing inorganic short fibers with a fiber diameter of 2 μm or less.

In order to produce such a thermoplastic resin composition, inorganic short fibers are added from a hopper equipped with a metering device during the extrusion of the thermoplastic resin using a single-screw or twin-screw extruder, blended, and then extruded. The pellet composition is produced by mixing in a machine, or the pellet composition is produced by feeding a raw material mixture in which a predetermined amount of inorganic staple fibers is blended into a thermoplastic resin in advance into a single-screw or twin-screw extruder and mixing. was trying to manufacture.

However, inorganic short fibers with an average fiber diameter of 2 μm or less exhibit a wool-like form, and when the inorganic short fibers are blended during extrusion of the thermoplastic resin in the former method,
Since the inorganic short fibers have no fluidity, a bridging phenomenon occurs in the hopper (filling materials solidify together due to their own weight, clogging the input port), and a predetermined amount of glass fiber is uniformly blended into the thermoplastic resin. The problem is that it is not possible. In the latter case, the thermoplastic resin and inorganic short fibers themselves are blended in a predetermined amount, but when the raw material mixture is supplied to the extruder, sufficient fluidity cannot be obtained in the hopper, resulting in the bridging phenomenon. However, there are problems in that the compound cannot be stably supplied to the extruder, and productivity is poor, making continuous mass production impossible.

An object of the present invention is to provide a filler for fiber thermoplastic resin that solves these problems.

(Means for Solving the Problems) The inventors of the present invention made extensive studies to solve these problems, and found that when inorganic short fibers blended with a thermoplastic resin are formed into a sheet of a predetermined shape, fluidity is obtained, and extrusion is possible. When blending thermoplastic resin while extruding it in a machine, the specified amount can be blended uniformly without causing a bridging phenomenon in the hopper.
It has also been found that when a raw material mixture prepared by blending inorganic short fibers with a thermoplastic resin is supplied to an extruder in advance, it can be continuously and stably supplied to the extruder.

The fiber-reinforced thermoplastic filler of the present invention was made based on this knowledge, and in the inorganic fiber filler blended into the thermoplastic resin, the inorganic fiber filler is inorganic short fibers with an average fiber diameter of 2 μm or less. It is characterized in that it is formed into a paper-made sheet with a side of 1 to 30 angles.

The thermoplastic resin used in the present invention is not particularly limited as long as it is a resin normally used as a fiber-reinforced resin composition. Specific examples of the thermoplastic resin include polycarbonate, polyethylene, polypropylene, polyamide,
Polystyrene, acrylonitrile-styrene copolymer,
Examples include acrylonitrile-butadiene-styrene copolymer, saturated polyester, polyimide, polyphenyl sulfide, polyacetal, fluororesin, ethylene-vinyl acetate copolymer, thermoplastic polyurethane, polyphenylene oxide, polysulfone, vinyl chloride resin, methacrylic resin, etc. It will be done.

Glass fiber is preferable as the inorganic short fiber that is a raw material for the paper sheet to be blended with the thermoplastic resin. The glass fiber is produced by pulling out glass melted in a glass melting furnace as a filament of a desired uniform diameter from a porous plate, guiding it into a high-temperature, high-speed burner flame, and converting it into fiber, thereby producing flocculent, ultra-fine glass fiber. Glass fibers with an average fiber diameter of 2 μm or less and a large specific surface area manufactured by the so-called short fiber flame method are suitable, and alkali-free glass such as E-glass is preferable as a raw material for the glass fibers. This is to prevent degradation and decomposition of the thermoplastic resin from being accelerated due to acceleration of alkaline hydrolysis by the glass fibers and deterioration of physical properties when C glass or the like is used.

Specific examples of such E-glass fibers having an average fiber diameter of 2 μm or less include E-FMW-800 (average fiber diameter 0.8 μm) and E-FMW-1700 (average fiber diameter 0.6 μm) manufactured by Nippon Inuki. ).

Further, in order to improve the adhesion between the thermoplastic resin and the glass fibers, the glass fibers may be subjected to a surface treatment before forming the glass fibers into a paper sheet. Specific examples of surface treatment methods include aminosilane, epoxysilane,
An example of the method is to immerse glass fibers in a 0.01 to 1% by weight aqueous solution of a silane coupling agent such as acrylic silane or vinyl silane, and then heat treat the fiber at a temperature of 140 to 160° C. for 1 to 2 hours.

As for the papermaking method for the papersheet, glass fibers may be made by the usual Fourdrinier method or the synchronized method, and neutral papermaking is preferable rather than acidic papermaking, as there is no need to be particular about the appearance of the papersheet. , papermaking is extremely simple. However, during papermaking, care must be taken to ensure that the glass fibers do not break and the fiber length becomes extremely short.

The weight per unit area of the paper sheet is 50 to 500 g/r+f, since it is defibrated before being fed into the extruder and a predetermined amount is uniformly mixed without inhibiting fluidity.
The thickness is preferably about 0.5 to 3.0 degrees.

In the present invention, the paper sheet is formed to have a side of 1 to 30 mm plus a corner. The reason why the size of the paper sheet is set in the range of 1 to 30 squares is that if the size of the sheet is less than 1 square, the inorganic short fibers constituting the paper sheet will be dispersed before the paper sheet is evenly dispersed. Uniform dispersion cannot be achieved. Further, if the size is 30II11 or more, it is too large to be uniformly dispersed when blended into a thermoplastic resin.

In order to form the paper sheet into a square with a side of 1 to 30 mm, the paper sheet may be cut using, for example, a square cutting pelletizer.

In addition, the vertical to horizontal dimensional ratio of the paper sheet is about 1:3, preferably 1:1, from the viewpoint of fluidity, anisotropy of molding shrinkage rate, etc.
And it is sufficient.

The blending amount of the paper sheet into the thermoplastic resin depends on the dimensional accuracy (low shrinkage rate) of the resulting molded product, the effect of improving mechanical strength, etc., the fluidity and economic efficiency when blending to produce fiber-reinforced thermoplastic resin. From these points, the proportion in the composition is 2 to 50% by weight.
The amount may be preferably about 8 to 40% by weight.

Normally, a binder is not required during papermaking, but fiber reinforcement is used to prevent the papersheet from being defibrated and impeding fluidity when fed to the thermoplastic resin, and to increase paper density. A bander, such as a mixture of polyamide resin and butadiene-acrylonitrile copolymer, which does not inhibit the properties of the thermoplastic resin, can be added internally (added with water during defibration) or externally (sprayed or rolled after forming the sheet). (impregnated and adhered using a coating device, etc.)
You may also do so.

The conventional method for producing fiber-reinforced thermoplastic resin by blending a paper sheet of inorganic short fibers with a thermoplastic resin is to mix the thermoplastic resin and the paper sheet in a V-type blender, then mix the thermoplastic resin and the paper sheet in a V-shaft or A method of pelletizing with a twin-screw extruder, or a method of supplying a paper sheet to a thermoplastic resin that is being extruded with a single-screw or twin-screw extruder, mixing in the extruder, and pelletizing is used.

(Example) Next, specific examples of the present invention will be described together with comparative examples.

Example First, E glass fiber (E-FMW-8,00, manufactured by Nippon Inuki) with an average fiber diameter of 0.8 μm and an average fiber length of 5 to 50 mm was used.
A 3x3 square paper sheet (hereinafter referred to as glass fiber A
) was prepared. Next, while extruding glass fiber A with polycarbonate resin powder (Nipiron E-2000, viscosity average molecular weight FFI 28,000, manufactured by Mitsubishi Gas Chemical Co., Ltd.) using a twin screw extruder, the mixing ratio of the composition was changed to glass fiber A2.
0% by weight: 80% by weight of resin was fed and blended from a hopper equipped with a metering machine, and mixed in a twin-screw extruder to produce a pellet-shaped fiber-reinforced thermoplastic resin.

The produced pellet-shaped fiber-reinforced thermoplastic resin was heated to a temperature of 1
It was dried in a hot air dryer at 20° C. for 5 hours, and then molded into a molded article (test piece for measuring physical properties) using an injection molding machine.

Then, the pelletization of the resin, the outer tube, bending strength, bending elastic modulus, tensile strength, and molding shrinkage rate of the molded product were investigated, and the results are shown in the table.

Measurement condition ■ Beretization: By visual inspection.

Evaluation: O: Stable supply possible, ×: Stable supply not possible■ Based on second visual inspection of appearance.

Evaluation: O: Surface smooth, x2 Surface roughness ■ Bending strength,
Flexural modulus: Based on ASTM D790.

■ Tensile strength: Based on ASTM 083g.

■ Molding shrinkage rate: Create a molded product using a mold for making a test piece,
It was calculated using the following formula using the mold dimensions (dimensions at a temperature of 25°C: A) and the dimensions of the molded product (dimensions at a temperature of 25°C: 2B).

-B Mold Shrinkage Rate- Comparative Example 1 Instead of the glass fiber A, a short fiber wool-like E glass fiber (E-FMW-800, manufactured by Nippon Inuki) with an average fiber diameter of 0.8 μm and an average fiber length of 5 to 50 mm was used. A molded article was molded in the same manner as in the previous example except that glass fiber (hereinafter referred to as glass fiber B) was used.

Then, the pelletization of the resin, the appearance, bending strength, bending elastic modulus, tensile strength, and molding shrinkage rate of the molded products were examined under the same conditions as in the previous example, and the results are shown in the table.

Comparative Example 2 Instead of the glass fiber A, a chopped strand (CS03, '409, manufactured by Asahi Fiberglass ■, hereinafter referred to as glass fiber C) composed of filaments of ugly E glass with an average fiber diameter of 13 μm and an average fiber length of 611 was used. A molded article was molded in the same manner as in the previous example except that the following was used.

Then, the pelletization of the resin, the appearance, bending strength, bending elastic modulus, tensile strength, and molding shrinkage rate of the molded products were examined under the same conditions as in the previous example, and the results are shown in the table.

Comparative Example 3 A molded article was molded in the same manner as in the example above, except that glass beads (EGB731, manufactured by Toshiba Parodi II, hereinafter referred to as glass beads) having an average diameter of 28 μm were used in place of the glass fiber A.

Then, the pelletization of the resin, the appearance, bending strength, bending elastic modulus, tensile strength, and molding shrinkage rate of the molded products were examined under the same conditions as in the previous example, and the results are shown in the table.

As is clear from the table, in the embodiment of the present invention, the inorganic fiber filler blended into the thermoplastic resin is a paper-made sheet of glass fiber with an average fiber diameter of 2 μm or less.
It is easier to pelletize compared to Comparative Example 1, which uses wool-like glass fibers of micrometers or less, and the anisotropy of molding shrinkage rate, appearance, and mechanical strength of the obtained molded product are equivalent to those of Comparative Example 1. was confirmed.

(Effects of the Invention) As described above, according to the present invention, since the filler is a paper-made sheet formed of inorganic short fibers having an average fiber diameter of 2 μm or less and 1 to 30 squares on each side, the conventional average fiber diameter is 2μm
Unlike short inorganic fibers that do not have fluidity, they have fluidity, so when mixed with thermoplastic resin during extrusion using an extruder, the specified amount can be uniformly blended without clumping or dispersing. In addition, when feeding the compound blended into the thermoplastic resin in advance to the extruder, it can be stably fed without solidifying, allowing continuous mass production and increasing productivity. effective.

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Claims (1)

[Claims] In inorganic fiber fillers blended into thermoplastic resins,
The inorganic fiber filler is a filler for a fiber-reinforced thermoplastic resin, characterized in that the inorganic short fibers having an average fiber diameter of 2 μm or less are formed into a paper sheet having a side of 1 to 30 mm square.