JP2002309108A - Resin molding material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a resin molding material which, when molded by an extrusion process, gives a molded object substantially free from the occurrence of a void on the surface and having high bending elasticity and a high modulus in flexure, and which, when molded by a simple metal die injection molding process, gives a greater number of simple metal die life shots. SOLUTION: The resin molding material for extrusion or a simple metal die injection molding consists of 45-80 wt.% of a thermoplastic resin having a number-average molecular weight of 9,000 to 13,000 or 13,000 to 15,000, and 55-20 wt.% of a first reinforcing fiber having a length of 20-180 μm and an aspect ratio of 2 to 20, or beads having a diameter of 30-150 μm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a resin molding material. More specifically, the present invention relates to a resin molding material for extrusion molding and simple mold injection molding.

[0002]

2. Description of the Related Art It is known to form a fiber-reinforced thermoplastic resin material by an extrusion molding method or a simple mold injection molding method. However, in injection molding, unlike injection molding, a high injection pressure is not applied. Therefore, in the case of a fiber-reinforced resin material having a high viscosity, (a) the desired shape cannot be controlled, and (b) There is a problem that voids are generated due to poor adhesion of the resin, and there is a problem that fiber reinforced resin materials cannot be applied except for blow molding which does not require mold transferability with high dimensional accuracy.

Further, in a simple mold for resin injection molding using an aluminum epoxy resin or the like, since the strength is reduced as compared with a conventional steel mold, the injection molding pressure is 100% due to high viscosity.
In the case of a fiber reinforced resin material that is as high as about MPa,
(A) Under the same molding conditions as the steel mold, the gate portion and the runner portion of the mold are overloaded, and the number of life shots is significantly shortened. (B) Injection pressure and holding pressure to avoid the burden on the mold Drops may cause problems such as warping, and in the worst case, shortage may occur where the resin is not filled in the cavity or sinkage may occur without flatness.

As shown in FIG. 3, for example, an injection molding machine for a thermoplastic resin includes a heating cylinder 1 having a molding material supply hopper 11 and a screw 12 coaxially therein.
3 and an injection cylinder 16 which is connected to a screw drive hydraulic motor 14 and has an injection cylinder 16 provided with a piston 15 therein. 17 opening and closing operation and mold 1
7, a mold clamping device B including a fixed plate 18 and a movable plate 19 for preventing the mold 17 from opening due to the pressure of the injected material, the driving device C of the injection device A and the mold clamping device B, and the operation of each part. Of the control device (D) (not shown) for controlling the power supply.

On the other hand, as shown in FIG. 4, for example, an extruder comprises a molding material supply hopper 21 on the upper part, a heater 22 on the periphery, a screw 23 coaxially inside, and a cylinder 25 having a die 24 at the tip. A plasticizing mechanism that plasticizes and melts the material by the rotation of the screw 23 and extrudes the material to the outside by the feed pressure of the screw 23. Further, there is also an apparatus that shapes and processes the material using this extrusion unit. (JP-A-9-57857).

In the case of this extrusion molding, since there is no device for applying high pressure to the molten resin and no device for receiving this high pressure, the shape of a fiber-reinforced resin material having a high viscosity can be controlled except for a simple sectional shape such as a pellet. Can not. Further, in a device for forming a resin, in the case of a fiber-reinforced resin material having a high viscosity, voids are generated due to poor resin adhesion between lamination layers.

[0007] The injection molding die includes a flow mechanism including a cabidi 31 and a core 32 filled with a molten resin, a sprue runner gate 33, and the like, a molded product take-out mechanism, and the like.
It consists of a temperature control mechanism and a mold base serving as a mold body (see FIG. 5).

In the case of a mass production mold, a steel material such as SKD is used, but an aluminum material, an epoxy resin, or the like which requires a short processing time may be used as a simple mold material. In the case of such a simple mold, the strength of the mold material is low (aluminum 7000-200 to 300 MPa in tensile strength, epoxy resin -100 to 200 MPa in tensile strength), and the gate and the cavity, which are subjected to pressure during molding, start and break. May be. When using a fiber-reinforced resin material with high viscosity,
100 to eliminate molding defects such as sink marks and shorts
It is necessary to apply injection pressure and holding pressure of about MPa,
In a simple mold using an aluminum material or an epoxy material, the mold may be damaged in about several hundred shots. In addition, if the injection pressure and the holding pressure are reduced in order to prevent the mold from being damaged, the above-described molding failure occurs.

[0009]

Accordingly, an object of the present invention is to provide a novel resin molding material.

Another object of the present invention is to provide a resin molding material for extrusion molding or simple mold injection molding.

Still another object of the present invention is to provide a resin molding material for extrusion molding for obtaining a molded article having no voids in the molded article and having a smooth surface.

Another object of the present invention is to provide a resin molding material for simple mold injection molding having a high number of life shots of the mold used.

[0013]

These objects are achieved by the following (1) to (7).

(1) Number average molecular weight 9,000-13,
Extrusion consisting of 45-80% by weight of a 000 thermoplastic resin and 55-20% by weight of a first reinforcing fiber having a fiber length of 20-180 μm and an aspect ratio of 2.5-15 or beads having a diameter of 30-150 μm. A resin molding material for molding or simple mold injection molding.

(2) The length of the fiber is 200 to 300 μm
The resin molding material according to the above (1), wherein the second reinforcing fiber is blended in an amount of 40% by weight or less based on the total of the first and second reinforcing fibers.

(3) The resin molding material according to (1) or (2), wherein the reinforcing fibers are glass fibers or wollastonite.

(4) The resin molding material according to any one of (1) to (3), wherein the material is for extrusion molding.

(5) Number average molecular weight 13,000-1
45 to 80% by weight of a 5,000 thermoplastic resin and a fiber length of 20 to 180 μm and an aspect ratio of 2.5 to 1
5. A resin molding material for extrusion molding or simple mold injection molding, comprising 55 to 20% by weight of first reinforcing fibers or beads having a diameter of 30 to 150 μm.

(6) The resin molding material according to (5), wherein the reinforcing fibers are glass fibers or wollastonite.

(7) The resin molding material according to (5) or (6), wherein the material is used for simple mold injection molding.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS As described above, the first invention of the present application provides a thermoplastic resin having a number average molecular weight of 9,000 to 13,000 at 45 to 80% by weight and a fiber length of 30 to 150 μm.
A resin molding material for extrusion molding or simple mold injection molding, comprising 55 to 20% by weight of first reinforcing fibers having an aspect ratio of 2.5 to 15 or beads having a diameter of 30 to 150 μm.

Further, the second invention of the present application relates to a 45-80% by weight polyamide having a number average molecular weight of 13,000-15,000, a fiber length of 30-150 μm and an aspect ratio of 2.5-15. 1 reinforcing fiber or diameter of 30 to
It is a resin molding material for extrusion molding or simple mold injection molding, comprising 55 to 20% by weight of 150 μm beads.

As the thermoplastic resin used in the present invention, any thermoplastic resin commonly used as so-called engineering plastics can be used. For example, polyamide, polybutylene terephthalate,
Examples include polyphenylene sulfide and modified polyphenylene oxide. Of these, polyamides are most preferred.

As the polyamide, any polyamide can be used. For example, nylon 6, nylon 66, nylon 610, nylon 9, nylon 11,
Nylon 12 and the like are available. Of these, nylon 6 and nylon 66 are widely used as structural materials, and are most preferable in terms of cost and the like.

In the first invention, the thermoplastic resin used has a number average molecular weight of 9,000.
~ 13,000 are suitably used. Also, the second
In the invention, the number average molecular weight is from 13,000 to 1
Those of 5,000 are preferably used.

The reinforcing fibers include inorganic fibers such as glass fibers, carbon fibers, boron fibers, and magnesium oxysulfide whiskers, and synthetic resin fibers such as aramid fibers, polyester fibers, polyamide fibers, and polyacrylonitrile fibers. Inorganic fibers are preferred,
Particularly, glass fiber is more preferable. In addition to glass fiber, talc, kaolin clay, and wollastonite as inorganic fillers may be used. Particularly, wollastonite (needle-like fiber) can be expected to have an effect of improving strength. Preferred reinforcing fibers.

The reinforcing fiber has a fiber length of 20-18.
0 μm, and preferably 30 to 150 μm. That is, when the thickness is less than 20 μm, the bending strength and the bending elastic modulus of a molded product obtained by extrusion of the obtained material are reduced,
On the other hand, if it exceeds 180 μm, the effects on high strength, high impact, creep resistance, and vibration fatigue resistance, which are features of long fiber reinforcement, become insignificant, and voids ( This is because voids are generated and the appearance is deteriorated. Further, the aspect ratio of the fiber is 2-2.
0, preferably 2.5 to 15. If the length is outside this range, the same problem as in the case where the length is out of the fiber occurs.

It is preferable to treat these reinforcing fibers and beads in advance with maleic anhydride, a silane coupling agent, or the like because the reinforcing effect is good.

As the reinforcing beads, there are glass beads, calcium carbonate beads, silica beads, aluminum hydroxide beads, alumina beads and the like, but glass beads are preferred. Its average diameter is between 30 and 150 μm, preferably about 50 μm. That is, if it is out of this range, a sufficient reinforcing effect cannot be obtained, and, for example, the bending strength and the bending elastic modulus of the molded product obtained by the extrusion molding method of the molding material become insufficient.

In the molding composition according to the present invention, the content of polyamide in the molding composition is 45 to 80% by weight, preferably 50 to 70% by weight, and the content of reinforcing fibers or beads is 55 to 20% by weight, preferably 50-30% by weight
It is. That is, the content of reinforcing fibers or beads is 20
If the amount is less than 5% by weight, the bending strength, the flexural modulus and the like of the molded product are insufficient, while if it exceeds 55% by weight, voids are formed on the surface of the molded product, resulting in poor appearance.

The number average molecular weight is from 8,000 to 13.0.
When the polyamide of No. 00 is used, the second reinforcing fiber is added to the total of the first and second reinforcing fibers by 40%.
% By weight, preferably 20 to 40% by weight, whereby a molded article having no voids on the surface, having an extremely good surface condition, and having excellent bending strength and flexural modulus can be obtained.

Such a resin molding material is obtained by blending and kneading the polyamide and the reinforcing fibers or beads.

In order to obtain a molded product, the kneaded product is melt-extruded in advance by a twin-screw extruder or the like, pelletized, and the obtained pellet is processed by an extrusion molding method or a simple mold injection molding method. Goods. In the case of a low-strength fiber, the reinforcing fiber is crushed when passing through an extruder, the aspect ratio becomes small, and it may be difficult to obtain a polyamide molded article having the desired mechanical strength. In this case, the polyamide and the reinforcing fiber itself or the reinforcing fiber hardened with a sizing agent or the like or the reinforcing fiber hardened with a thermoplastic resin such as polyamide are blended into the resin molding material of the present invention, and this blended product is directly extruded. Alternatively, a molded product is obtained by simple mold injection molding. In this case, since the kneading only needs to be performed once at the time of extrusion molding or at the time of simple mold injection molding, the aspect ratio in the molded article is smaller than that of the injection molding after blending with a twin-screw extruder. It becomes closer to the aspect ratio and becomes a polyamide molded article having high mechanical strength, which is more preferable.

The extrusion molding method employed in the present invention includes:
Any conventionally used extrusion molding method can be used.

Further, both the simple mold injection molding method and the conventional simple mold injection molding method can be used. The simple mold referred to here is, for example, an aluminum mold (JIS standard aluminum alloy material 7000A
1-Zn-Mg alloy), resin type (hardened by mixing 30 to 70% by weight of aluminum powder with epoxy resin) and the like.

[0036]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited thereto. In these examples and comparative examples, the test methods used for evaluating various physical properties, and the production methods of the thermoplastic elastomer used for the raw materials and the blending are as follows.

(1) Flexural strength The flexural strength was measured at 23 ° C. in accordance with JIS K6758.

(2) Flexural modulus JIS K6758
It measured at 23 degreeC by the method based on.

Examples 1 to 13 As shown in Table 1, a resin molding material was prepared by changing the type and amount of polyamide 6) nylon and glass fiber or glass beads, and then using this material. , A molding pressure of 30 MPa, a resin temperature of 280 ° C., and an extrusion speed of 50 cm ³ / sec by using an extruder, and a part (one cylinder) 1 of the intake manifold shown in FIGS. 1 (A) and 1 (B). Was molded. In addition, since the resin number average molecular weight of 9,000 shown in Table 1 is not set as a product, a test is performed by changing the number average molecular weight by applying a heat load to the resin having a number average molecular weight of 13,000. Was. Also, for the extrusion molding machine, if the molding material is extruded only by the screw operation without operating the piston of the injection molding machine, the molding material is not injected at a high pressure,
Because it is possible to obtain the same function as an extruder,
Injection molding machine manufactured by Mitsubishi Heavy Industries, Ltd.
50MMG), the piston was stopped, and the molding material was extruded only by screw operation.

The appearance (the state of voids), flexural strength and flexural modulus of some parts of the intake manifold thus obtained were measured. The results are as shown in Table 1. By plotting this result, a graph shown in FIG. 2 was obtained (marked with ○).
Each of them had a bending strength of 60 MPa or more and a flexural modulus of 3.5 GPa, which are necessary for practical use.

The simple mold and the extrusion mold for resin molding can be manufactured relatively easily and are inexpensive, so that they are suitable for small-scale production of various kinds. As shown by the circles in FIG. 2, the appearance quality and high strength without voids can be ensured. For example, when mass-producing a resin intake manifold as an automobile engine component, a bending strength of about 150 MPa and a bending elastic modulus of about 7.5 GPa are required, so that a product having a higher strength than that of this embodiment can be obtained. It is molded by a cast iron injection molding die using a resin molding material. However, if the strength of the circle shown in FIG. 2 can be secured, there is no practical problem.
In this embodiment, as a trial operation, a part 1 of the intake manifold is molded by the above-described simple mold for resin molding or an extrusion mold, and is used for measuring durability, sound vibration characteristics, and the like. And, based on the result, a product design using a resin molding material that can obtain higher strength in consideration of a further safety factor is performed,
Mass production will be performed using a cast iron injection mold or the like. This makes it possible to develop resin products at low cost and in a short period of time.

Comparative Examples 1 to 7 As shown in Table 1, resin molding materials were prepared by changing the types and amounts of polyamide and glass fibers or wollastonite (needle-shaped fibers) as an inorganic filler. The material was extruded under the same conditions as in Example 1 to form a part of an intake manifold similar to that of Example 1.

The appearance (the state of voids), bending strength and flexural modulus of some parts of the intake manifold thus obtained were measured. The results are as shown in Table 1. By plotting this result,
The graph shown in FIG. 2 was obtained (indicated by a solid circle), and the comparative example not only had insufficient bending strength and flexural modulus, but also
There were many voids on the surface, the appearance was poor, and it was not practical.

Examples 14 to 16 As shown in Table 2, the types and amounts of polyamide (nylon 6 manufactured by Ube Industries, Ltd.) and glass fiber or wollastonite (needle-like fiber) or glass beads as an inorganic filler were determined. After preparing a resin molding material by changing it, a simple mold (epoxy resin containing aluminum powder (Terradite M-55, manufactured by Terada Co., Ltd.)) (Quinnate MEZ350, manufactured by Vantico Co., Ltd.)
1 (A) and 1 (A) with an injection molding machine (trade name: 550 MMG) manufactured by Mitsubishi Heavy Industries, Ltd. under molding conditions shown in Table 2.
Part 1 of the intake manifold shown in (B) was molded.

The number of life shots of the mold was examined for some parts of the intake manifold thus obtained, and the results are as shown in Table 2.

Comparative Examples 8 to 9 As shown in Table 2, a resin molding material was prepared by changing the types and amounts of polyamide and glass fiber, and a simple mold injection was performed using the material under the conditions shown in Table 2. Molding,
Some parts of the same intake manifold as in Example 14 were molded.

The number of die life shots of some of the parts of the intake manifold obtained as described above was examined. As shown in Table 2, Examples 14 to 16 showed that
In each case, compared to Comparative Examples 8 and 9, the number of life shots of the mold is 10 times or more, and 1000 shots or more can be formed.

The number average molecular weight of the polyamide used was measured according to JIS K 6920-1 as a solution in sulfuric acid (98%) in relation to the relative viscosity ηr. Table 3 shows the results.

[0049]

[Table 1]

[0050]

[Table 2]

[0051]

[Table 3]

[0052]

As described above, the resin molding material according to the present invention has a high degree of freedom in the cross-sectional shape of an extruded (by molding method) molded article, and when the resin is formed, the adhesion of the resin between the laminations is high. As the properties are improved, voids (voids) are eliminated,
The surface appearance is excellent, and the mechanical strength such as flexural strength and flexural modulus is increased.

Also, when molded by a simple mold injection molding method, unlike conventional materials, molding can be performed with a low injection pressure and holding pressure of about 30 to 60 MPa. The number of life shots is remarkably improved, and molding defects such as warpage, sink marks and shorts are extremely suppressed.

Therefore, it is extremely effective for manufacturing an intake manifold, a rocker cover, a near-flexion shielding cover, and the like.

[Brief description of the drawings]

FIG. 1A is a plan view showing an example of a part of an intake manifold as an example manufactured using a resin molding material of the present application. FIG. 1B is a side view of some parts of the intake manifold shown in FIG.

FIG. 2 is a graph showing the performance of a molded article of a resin molding material according to the present invention.

FIG. 3 is a sectional view showing a basic structure of a thermoplastic resin injection molding machine.

FIG. 4 is a sectional view showing a basic structure of an extruder.

FIG. 5 is a sectional view showing a basic structure of an injection molding die.

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Claims (7)

[Claims] 1. A number average molecular weight of 9,000 to 13,000.
45 to 80% by weight of a thermoplastic resin having a fiber length of 2
First reinforcing fibers having an aspect ratio of 2 to 20 or beads 55 to 20 having a diameter of 30 to 150 μm;
A resin molding material for extrusion molding or simple mold injection molding consisting of wt%. 2. A second fiber having a fiber length of 200 to 300 μm.
2. The resin molding material according to claim 1, wherein the reinforcing fiber is blended with the second reinforcing fiber in an amount of 40% by weight or less based on the total of the first and second reinforcing fibers. 3. 3. The resin molding material according to claim 1, wherein the reinforcing fibers are glass fibers or wollastonite. 4. The resin molding material according to claim 1, wherein said material is for extrusion molding. 5. A number average molecular weight of 13,000 to 15,000.
0 to 45% by weight of a thermoplastic resin and first reinforcing fibers having a fiber length of 20 to 180 μm and an aspect ratio of 2 to 20 or beads 55 to 2 having a diameter of 30 to 150 μm.
A resin molding material for extrusion molding or simple mold injection molding comprising 0% by weight. 6. The resin molding material according to claim 5, wherein the reinforcing fibers are glass fibers or wollastonite. 7. The resin molding material according to claim 5, wherein the material is for simple mold injection molding.