JP2646027B2 - Molding material - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a molding material, and more particularly, it is used for injection molding, extrusion molding, compression molding, etc., and has good dispersibility at the time of molding and fiber breakage. The present invention relates to a molding material which can provide a molded article having a small amount of mechanical strength and greatly improved mechanical strength.

[Conventional technology]

Conventionally, as a method for producing a thermoplastic resin composition reinforced by fibers, a dry blend is prepared by dry blending a glass fiber having a length of, for example, about 3 mm with a thermoplastic resin, and this is kneaded with an extruder. A method for forming pellets by granulation or the like is known.

[Problems to be solved by the invention]

However, in such a conventional production method, since the dry blend is kneaded with an extruder, the glass fibers tend to be bridging and matting. As a result, the dispersibility of the fiber becomes insufficient, and the fiber breaks.
There is a problem that the reinforcing effect is reduced, for example, irregular arrangement with a normal distribution length having a central portion at a length of 0.3 mm.

Conventionally, the upper limit of the glass fiber filling rate is generally 30% by weight, but in recent years, for the purpose of improving mechanical strength and the like, development of a molding material having a high glass fiber filling rate has been attempted. However, since it is difficult to disperse the fibers at the time of kneading, there is a problem that a molding material having a high filling rate of 30% by weight or more of a glass fiber cannot be obtained.

On the other hand, in order to solve the above-mentioned problems, a method of coating glass fiber or the like with a thermoplastic resin has been proposed. For example, Japanese Patent Publication No. 49-41105 describes the following method. That is, while passing a fiber bundle such as glass fiber into the die perforation,
The thermoplastic resin melted by an extruder is guided into the perforations of the dies to cover the fiber bundle. Then, after cooling, it is cut into a certain length to obtain a cylindrical molding material. However, the molding material obtained in this manner also has the same fiber length in the pellets before molding as the pellet length. There was a problem of causing poor sex. In addition, most of the fibers are broken by shearing between the barrel and the screw in the supply zone in the extruder, and the average fiber length in the resulting molded product is about 0.5 mm, and the fiber reinforcing effect cannot be sufficiently exerted. was there.

Therefore, an object of the present invention is that despite the fact that the fiber reinforcement is filled in a high concentration, the fiber dispersibility at the time of molding is good, the breakage or breakage of the fiber is small, and the mechanical strength, especially the impact strength is low. An object of the present invention is to provide a molding material from which a significantly improved molded product can be obtained.

[Means for solving the problem]

As a result of intensive studies to solve the above problems, the present inventor has found that
The problem of poor fiber dispersion or fiber breakage occurring in the extruder during molding is closely related to the specific surface area of the molding material, and by setting this specific surface area to a certain value or more, the molding material is supplied in the supply zone of the extruder. The present inventors have found that the above-mentioned problems can be solved despite the fact that the thermoplastic resin in the inside becomes molten in a short time and the fibers are filled in the molding material at a high concentration.

That is, the molding material according to the present invention is a plate having a structure in which a fibrous reinforcing material composed of a single fiber (filament) is coated with a thermoplastic resin, and the thermoplastic resin is impregnated in the fibrous reinforcing material. A molding material obtained by cutting the plate-like body filled with the fibrous reinforcing material, wherein (i) the filling rate of the fibrous reinforcing material with respect to the molding material is 50% by weight or more and 90% by weight % Or less, (ii) the length of the fibrous reinforcing material is 1 to 30 mm, (iii) at least one side of the plate-like body is 1 mm or less, and (iv) the specific surface area of the molding material is 20 cm ² / g or more. It is characterized by the following.

First, an example of the molding material of the present invention will be described with reference to FIG. In the figure, 20 is a molding material, 21 is a thermoplastic resin, and 22 is a single fiber.

L is the length of the molding material, that is, the fiber length, 1.0 to 30 mm
It is. If it is less than 1.0 mm, the fiber length is short, and a sufficient reinforcing effect cannot be obtained. Conversely, if it exceeds 30 mm, bridging or the like is caused in the hopper and molding becomes difficult, which is not preferable.

 The following equation is an equation for calculating the specific surface area.

In the formula, L: length of molding material (cm) W: width of molding material (cm) H: thickness of molding material (cm) P: specific gravity of molding material (g / cm ³ ) Of which, at least one is 1.0mm or less,
Preferably, it is less than 0.5 mm in order to set a large specific surface area.

In the present invention, the specific surface area is at least 20 cm ² / g, preferably at least 30 cm ² / g, more preferably at least 40 cm ² / g. When the specific surface area is less than 20 cm ² / g, it takes a long time for the thermoplastic resin in the molding material to be in a molten state in the extruder during molding such as injection molding or extrusion molding. Problems such as defects and fiber breakage occur, which is not preferable.

The thickness H is preferably set to 0.1 mm or more from the viewpoint of classification in the hopper and handling.

Examples of the type of the fibrous reinforcing material used in the present invention include glass fibers such as E-glass and S-glass, carbon fibers such as polyacrylonitrile, pitch and rayon, and “Kevlar” (trademark) manufactured by DuPont. Typical examples include aromatic polyamide fibers, silicon carbide fibers such as "Nicalon" (trademark) of Nippon Carbon Co., Ltd., and metal fibers. These fibrous reinforcing materials can be used alone or in combination.

In the present invention, the fiber diameter varies depending on the type of the fiber. For example, in the case of glass fiber, the diameter is usually 5 to 25 μm. Surface treatment of the fibrous reinforcing material is preferable from the viewpoint of adhesiveness with a thermoplastic resin. For example, in the case of glass fiber, a silane-based
Treating with a titanate-based coupling agent is particularly preferred.

The thermoplastic resin used in the present invention is not particularly limited, and may be selected according to the application. For example, polypropylene, styrene acrylonitrile copolymer, polystyrene, acrylonitrile / butadiene / styrene copolymer (methyl methacrylate / butadiene / styrene, methyl methacrylate / acrylonitrile / butadiene / styrene, acrylonitrile / butadiene / α-methylstyrene / styrene copolymer) Coalesce), polyphenylene ether (including modified polyphenylene oxide), polyethylene, polyoxymethylene, polycarbonate, polyamide, polymethyl methacrylate, polyvinyl chloride, polyethylene terephthalate, polybutylene terephthalate, polyphenylene sulfide, polysulfone, polyether sulfone, Polyether ether ketone, polyether ketone, polyimide, polyether ether De, and the like.

In the present invention, the filling rate of the fibrous reinforcing material in the molding material is from 50% by weight to 90% by weight. If the amount is less than 50% by weight, the effect of the present invention such as high filling of fibers and the characteristics cannot be exhibited, and when it is used as a master batch described later, it is not preferable from the viewpoint of economy. On the other hand, if it exceeds 90% by weight, the surface of the single fiber cannot be sufficiently covered with the thermoplastic resin, which is not preferable.

The molding material according to the present invention is a plate-like body having a configuration in which a fibrous reinforcing material composed of a single fiber (filament) is coated with a thermoplastic resin, and the thermoplastic resin is impregnated in the fibrous reinforcing material. Is obtained by cutting the plate-like body filled with the fibrous reinforcing material into a predetermined length.

In the present invention, it is preferable to obtain a molding material in which the surface of at least 90% of a single fiber (filament) constituting the fibrous reinforcing material is a constituent unit is covered with the thermoplastic resin.

In the present invention, the method of impregnating a fibrous reinforcing material with a thermoplastic resin to coat the surface of a single fiber (filament), which is a structural unit of the fiber, with the thermoplastic resin is not particularly limited. For example, a melt impregnation method in which a fibrous reinforcing material is impregnated with a molten thermoplastic resin, a fluidized bed method in which a powdery thermoplastic resin is suspended in air or impregnated in a state of being suspended in a liquid such as water. Is mentioned.

Representative examples of the melt impregnation method are described in JP-A-61-229534 and JP-A-61-229534.
No. 229535, No. 61-229536 and Japanese Patent Application No. 61-216253.

An example of the melt impregnation method that can be employed in the present invention will be described with reference to FIG.

After the rovings 2 of long fibers drawn from the plurality of bobbins 1 are aligned in one direction by the aligner 3, they are passed through the tension adjusting rolls 4, 5, and 6 to form the fiber sheet 7. In the present invention, multidirectional continuous fibers can be used in addition to the fiber sheets aligned in one direction.

On the other hand, a resin heated and melted by an extruder (not shown) is applied to the surface of a lower belt 10 heated by a heating roll 9 via a die 8. The upper belt 12 is heated by the heating roll 11.

Next, the sheet 7 passes between the impregnating rolls 13 while being tensioned, while being sandwiched between the lower belt 10 and the upper belt 12.

The continuous fiber / thermoplastic resin composite 14 thus obtained is laminated or hot-pressed as it is or, if necessary, so as to have a desired thickness. Then, by cutting the fiber into a desired length in a direction perpendicular to the fiber with a cutting machine 18, a square shaped molding material 20 can be obtained. In FIG. 3,
15 and 16 are take-up rolls.

As the method of laminating and hot pressing, for example, the composite
The surface of No. 14 is heated to a temperature higher than the softening point of the thermoplastic resin and then laminated, or is heated in a heating furnace after the lamination to a temperature higher than the softening point of the resin. Next, the composite 14 is cooled to a temperature below the solidification temperature of the resin under pressure, for example, by passing the composite between cold nip rolls.

The molding material thus obtained is used as it is or as a so-called master batch by dry blending with a fiber-reinforced thermoplastic resin so as to have a desired fiber filling ratio, so that injection molding and extrusion molding can be performed. Offered. The molding material can be applied to, for example, compression molding in addition to the injection molding and extrusion molding. Even when applied to this compression molding, the shape of the molding material is a plate,
That is, since it has a scale shape, it has good adhesion to the mold. In addition, since the specific surface area is large, the melting time of the resin in the material is short, and molding can be performed in a shorter time than in the conventional method. In this case, while the conventional molding material is usually in a cylindrical shape, the material is in the form of a scale and has a secondary effect that the position setting on the mold is easy.

〔Example〕

Hereinafter, examples of the present invention will be described, but the scope of the present invention is not limited to these examples.

Example 1 Using the apparatus shown in FIG. 3, a molding material was obtained from polypropylene and glass fiber as follows.

100 rovings of glass fiber (fiber diameter 13 μm, convergence number 1600) pulled out from 100 bobbins 1
After aligning in one direction by aligner 3, tension adjusting rolls 4, 5,
6 to form a fiber sheet 7 having a width of 200 mm.

On the other hand, the polypropylene heated and melted at 210 ° C. by an extruder (not shown) is passed through a die 8 to a lower belt roll 9.
The coating was applied to the surface of the lower belt 10 heated to 220 ° C. (three in this case) with a thickness of 145 μm. Then the sheet is
22 with lower belt and upper belt roll 11 (3 in this case)
While sandwiching the upper belt 12 heated to 0 ° C., the impregnated rolls 13 (here, three rolls) having a diameter of 240 mm heated to 220 ° C. are applied at a speed of 50 cm / min while applying a tension of 150 kg. Let it pass. The glass fiber-polypropylene composite 14 thus obtained is cooled to 100 ° C.,
After slitting with a slitter 17, slits were made at intervals of 5 mm, and then cut by a cutter 18 into a length of 3 mm to obtain a molding material having a thickness of 0.24 mm and a glass fiber filling rate of 70% by weight.

When the specific surface area of the obtained molding material was calculated, 58 cm ² / g
Met.

Next, 57 parts by weight of the molding material and 43 parts by weight of fiber-reinforced polypropylene resin were dry-blended, and then a test piece having a glass fiber filling rate of 40% by weight was prepared using an injection molding machine.

When the cross section of the test piece was observed with a scanning electron microscope, the dispersibility of the fiber was good and no development such as blocking was observed.

In addition, Izod impact strength and fiber length were measured using the test piece. The results are shown in Table 1. The center of the fiber length distribution was about 1.6 mm, and the fiber breakage during injection molding was smaller than that of the prior art product, and the Izod impact strength was about twice.

Comparative Example 1 A polypropylene melted by an extruder was fed into a crosshead die having a hole having a diameter of 3 mm and a length of 300 mm. On the other hand, nine glass fibers used in Example 1 were passed through the perforations, and were passed through a crosshead heated to 220 ° C. and were brought into contact with molten polypropylene to coat the fibers with a resin.

Next, after cooling to 100 ° C. or lower, the product was cut into a length of 3 mm, and a cylindrical molding material having a diameter of 3 mm and a glass fiber filling rate of 50% by weight was obtained. When the specific surface area of the obtained molding material was determined, it was 16 cm ² / g.

Next, the obtained molding material was dry-blended as shown in Table 1, and a test piece having a glass fiber filling rate of 40% by weight was prepared by the injection molding machine used in Example 1. When the cross section of the test piece was observed with a scanning electron microscope, the dispersibility of the fibers was insufficient and the phenomenon of blocking was observed.

In addition, Izod impact strength and fiber length were measured using the test piece. The results are shown in Table 1. As shown in Table 1, the center of the fiber length distribution was about 0.6 mm, and the fiber breakage during injection molding was more severe than that in Example 1. As a result, the Izod impact strength was greatly reduced.

Comparative Example 2 Five glass fiber composites 14 obtained by treating in the same manner as in Example 1 were stacked, and passed through a pair of 200 ° C. heating rolls for 50 k.
After hot pressing with a linear pressure of g / cm, the same treatment as in Example 1 was performed to obtain a molding material having a length of 3 mm, a thickness of 1.20 mm, a width of 5 mm and a glass filling rate of 70% by weight. The specific surface area of the molding material was 17 cm ² / g.

Then, after dry-blending in the same manner as in Example 1, injection molding was performed to prepare a test piece having a glass fiber filling rate of 40% by weight.

The cross section of this test piece was observed with a scanning electron microscope.
The fibers were considerably blocked and poorly dispersed.

In addition, Izod impact strength and fiber length were measured using the test piece. The results are shown in Table 1. The center of the fiber length distribution was about 0.7 mm, which was severely broken during molding, and the Izod impact strength was also reduced.

Examples 2 to 4 In Example 1, instead of the fibers and resins shown in Table 1,
A composite was obtained in the same manner as in Example 1.

Next, after slitting to a width of 5 mm, the material was cut to a length shown in Table 1 to obtain a molding material. Next, after dry blending with the fiber powder reinforced resin at the ratios shown in Table 1, injection molding was performed to obtain test pieces.

When the cross section of the test piece was observed with a scanning electron microscope, the dispersibility of the fiber was good, and no phenomenon of blocking was observed.

For this test piece, the fiber length and Izod impact strength were measured in the same manner as in Example 1. Table 1 shows the results.

Examples 5 to 10 In Example 1, instead of the fibers and resins shown in Table 2,
A composite was obtained in the same manner as in Example 1.

Next, after slitting to a width of 5 mm, the material was cut to a length shown in Table 2 to obtain a molding material. Next, after dry blending with the fiber powder reinforced resin at the ratio shown in Table 2, injection molding was performed to obtain a test piece.

When the cross section of the test piece was observed with a scanning electron microscope, the dispersibility of the fiber was good and no phenomenon such as blocking was observed.

When the fiber length and Izod impact strength of this test piece were measured in the same manner as in Example 1, the same results as in Example 1 were obtained.

Example 11 The molding material obtained in Example 9 was dry-blended with PEEK to adjust the fiber filling rate to 30%. Using a dry extruder, a test piece of a round bar having a diameter of 30 mmφ was obtained from this dry blend.

The cross section of this test piece was observed with a scanning electron microscope.
The dispersibility of the fiber was good, and no phenomenon such as blocking was observed.

Example 12 The molding material 20 obtained in Example 1 was placed in a female mold 30 shown in FIG. 4 to which a release agent (FREKOTE44; manufactured by FREKOTE Inc., USA) was applied.
After placing 300g uniformly, the male mold 31 coated with the above release agent
Was set. Next, after leaving the mold in a heating furnace heated to 300 ° C. until the mold temperature reached 230 ° C., the mold was quickly transferred to a compression molding machine having a normal-temperature pressing plate, and 50 kg / cm ^2.
For 20 minutes to obtain a molded product of 300 × 300 × 2.0 mm.

The surface of the molded article was observed with the naked eye, but the fibers were not dispersed on the surface, the fibers were well dispersed, and the surface had good surface gloss.

[Effects of the Invention] According to the present invention, despite the fact that the fibrous reinforcing material is filled at a high concentration, the fiber dispersion during molding is good, the fiber breakage or breakage is small, the mechanical strength, In particular, it is possible to provide a molding material from which a molded article having significantly improved impact strength can be obtained.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an example of the structure of the molding material of the present invention,
FIG. 2 is a partially enlarged view of the molding material, FIG. 3 is a schematic diagram showing an example of an apparatus for producing the molding material of the present invention, and FIG. 4 is an example of a compression molding die to which the present invention is applied. FIG. 20: Molding material 21: Thermoplastic resin 22: Single fiber 30: Female mold 31: Male mold

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code Agency reference number FI Technical indication B29K 309: 08 (72) Inventor Chiaki Maruko 3-11-4 Ofuna, Kamakura City, Kanagawa Prefecture (56) Reference Document JP-A-1-214408 (JP, A)

Claims (10)

(57) [Claims] A fibrous reinforcing material composed of a single fiber (filament) is coated with a thermoplastic resin, and a plate-like body having a configuration in which the thermoplastic resin is impregnated in the fibrous reinforcing material is obtained. In a molding material obtained by cutting the plate-like body filled with the fibrous reinforcing material, (i) a filling rate of the fibrous reinforcing material with respect to the molding material is 50% by weight or more and 90% by weight or less; ) The length of the fibrous reinforcing material is 1 to 3 mm, (iii) at least one side of the plate-like body is 1 mm or less, and (iv) the specific surface area of the molding material is 20 cm ² / g or more. Molding material. 2. The molding material according to claim 1, wherein the fibrous reinforcing material is glass fiber. 3. The molding material according to claim 1, wherein the fibrous reinforcing material is carbon fiber. 4. The molding material according to claim 1, wherein the filling rate of the fibrous reinforcing material is 60% by weight or more and 90% by weight or less. 5. The molding material according to claim 4, wherein the filling rate of the fibrous reinforcing material is 70% by weight or more and 90% by weight or less. 6. The molding material according to claim 1, wherein at least one side of the plate is less than 0.5 mm. 7. The molding material according to claim 1, wherein the specific surface area of the molding material is 30 cm ² / g or more. 8. The molding material according to claim 7, wherein the specific surface area of the molding material is 40 cm ² / g or more. 9. The molding material according to claim 1, wherein the molding material is used for injection molding. 10. The molding material according to claim 1, wherein the molding material is used for extrusion molding.