JP2000084926A - Fiber-reinforced thermoplastic resin molding material and molded body using it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fiber-reinforced thermoplastic resin molding material which has especially good biting property of the molding material to a molding machine and provides a fiber-reinforced resin molded body with excellent strength, elasticity, impact resistance, etc., and a molded body. SOLUTION: This fiber-reinforced thermoplastic resin molding material comprises at least two kinds of thermoplastic resin pellets wherein reinforcing fibers with an approximately same length as that of the pellet is incorporated under an aligned or twisted condition in the length direction of the pellet and content of the pellets in continuous length with a length of 5-15 mm is 5-55 vol.% and content of fibers with a length of 5-15 mm incorporated in the whole pellets is 1-12 vol.%.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fiber-reinforced thermoplastic resin molding material used for various moldings such as injection molding, injection compression molding, extrusion molding, and blow molding, and more particularly, to the incorporation of the molding material into a molding machine. The present invention relates to a fiber-reinforced thermoplastic resin molding material which provides a fiber-reinforced resin molded article having good properties and excellent strength, elastic modulus, impact resistance and the like.

Accordingly, the fiber-reinforced thermoplastic resin molding material of the present invention can be used for a battery tray, a bumper beam, a fan shroud, an engine cover, an intake manifold,
Interior and exterior parts for automobiles such as instrument panels, console boxes, oil reservoirs, shift lever bases, seat shells, door handles, truck steps, pulleys and balancers for washing machines, pump casings for dishwashers, air conditioner fans, etc. It can be effectively used for forming parts for home appliances, concrete panels, soundproof walls, civil engineering construction materials such as manhole covers and gratings, transport members such as pallets and containers, and furniture parts such as chairs and desks.

[0003]

2. Description of the Related Art Fiber-reinforced thermoplastic resin pellets used as molding materials for injection molding and the like include: 1) chopped reinforcing fibers of about 3 to 12 mm in length, and various additives depending on the purpose. Melt-kneaded with an extruder, etc., into which an inorganic filler has been added and pelletized, and 2) passing a continuous reinforcing fiber bundle into a molten thermoplastic resin bath Long-fiber pellets obtained by impregnating the fiber, taking it out, and cutting it into an appropriate length are known.

[0004] Since the short fiber pellets are kneaded with a resin in a molten state during pellet production, breakage of the reinforcing fibers is unavoidable, and the length of the reinforcing fibers in the pellets is shortened. In the molded article obtained by injection molding using the pellets in which the reinforcing fibers are shortened, the reinforcing fiber length is 0.3 to 0.6 m.
m, and the entanglement between the reinforcing fibers is reduced,
It is difficult for the reinforcing effect of the reinforcing fiber to be sufficiently exerted, and a molded article having satisfactory mechanical properties cannot be obtained.

For this reason, in recent years, molded articles using long fiber pellets as a molding material have been provided. However,
Injection moldings using long fiber pellets have better mechanical properties than injection moldings using short fiber pellets, but have relatively poor penetration into molding machines due to the use of relatively long pellets. In addition to the time required for weighing, air entrainment increases and voids and gas defects are likely to occur in the molded product, which not only reduces the quality stability of the molded product but also increases the rate of defective products. Come up.

On the other hand, JP-B-49-41105, JP-A-56-5718, JP-A-7-112434, and 6-
Publications such as 287317 also propose a method of containing long fibers and short fibers in one pellet in order to exhibit both the characteristics of long fibers and the characteristics of short fibers. However, in order to obtain a molded product with high impact strength, it is necessary to make a considerable amount of long fibers present, so there is no difference in using long pellets. The accompanying problems are not eliminated.

[0007] Japanese Patent Publication No. Hei 3-25340 and Japanese Patent Application Laid-Open
No. 256647 describes a method of molding using a mixture of a long fiber pellet and a resin pellet containing no short woven fiber pellets or reinforcing fibers. The effect of the pellet length on the biteability of a molding machine is described. And the problems caused by it are not recognized at all.

Further, even if resin pellets containing no short fiber pellets or reinforcing fibers are blended with long fiber pellets, the biteability of the molding machine may be improved. Considering that the long fiber in the long fiber pellet is damaged (broken) in the molding process, the contribution of the short fiber pellet to the impact strength of the mixture of Since it is extremely small, a large amount of long fibers must be blended in order to secure the mechanical properties, and therefore, the variation in the mechanical properties of the molded article increases.

Even when a pellet containing reinforcing fibers is diluted with neat resin pellets containing no reinforcing fibers and used (a resin pellet containing reinforcing fibers is used as a masterbatch), a molded article having excellent impact characteristics can be obtained. Pellets with a long pellet length, in other words, pellets containing long fibers, must be used and the blending amount of the long fibers must be increased, and the dispersion of the reinforcing fibers in the molded body becomes insufficient, resulting in large variations in mechanical properties. Become.

Further, Japanese Patent Application Laid-Open No. Hei 6-23745 discloses that a mixed material composed of a long fiber reinforced resin pellet and a low fiber content pellet having a lower fiber content than the long fiber reinforced resin pellet, A length relationship is disclosed, and a method is disclosed for improving the variation in mechanical properties of a molded article when using fiber-reinforced resin pellets as a masterbatch by properly adjusting these relationships. However, in order to obtain a molded article having a high impact strength by this method, when a pellet having a long fiber length, that is, a pellet having a long pellet length is used, other pellets used in combination with the pellet have a long length. Pellets must be used, and this does not provide a particular improvement in the biteability of the molding machine.

[0011] As a technique for improving poor biting property into a molding machine when long fiber pellets are used, long fiber pellets containing AS (acrylonitrile-styrene copolymer) resin as a thermoplastic resin component are modified with modified AS or Long fiber pellets containing a rubber-modified styrene copolymer (Japanese Unexamined Patent Publication No.
No. 13138 and No. 8-12158).
In this technology, the resin impregnating property of the reinforcing fibers is increased to improve the pellet shape, and the poor penetration into the molding machine caused by the reinforcing fibers falling off the pellets is improved. No mention is made of the biteability in the case of long-fiber pellets composed of a resin having a good quality.

Japanese Patent Application Laid-Open No. 9-324080 discloses that
A technique has been disclosed in which powdery calcium stearate is externally added to long fiber pellets containing a polyolefin resin as a resin component, thereby improving the biteability of a molding machine. However, in the method of externally adding calcium stearate, a certain effect of improving the biteability can be obtained, but deterioration of the mechanical properties of the molded article due to the mixing of calcium stearate into the molding material is inevitable. In addition, in this method, there is a problem of separation and scattering of the powdered calcium stearate generated in the step after blending with the pellets, and the process control including the concentration control of the calcium stearate is complicated.

[0013]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems of the prior art, and has as its object to improve the efficiency of weighing in a short time with good penetration into a molding machine. A fiber-reinforced thermoplastic resin molding material that can be performed well, does not cause a hod or gas defects due to air entrainment, and gives a fiber-reinforced resin molded body with excellent strength, elastic modulus, impact resistance, etc. Is to provide.

[0014]

The fiber-reinforced thermoplastic resin molding material according to the present invention, which can solve the above-mentioned problems, is characterized in that reinforcing fibers having substantially the same length as pellets are aligned or twisted in the longitudinal direction of the pellets. Contains at least two types of thermoplastic resin pellets contained in a state, 5 to 15 m in length
m, the content ratio of the fiber-containing long pellet (A) is 5 to 55.
% By volume and a length of 5 to 1 contained in all the pellets
The gist is that the content of 5 mm fiber is 1 to 12% by volume.

In the present invention, the content of the fiber-containing short pellet (B) having a length of 1 to 3 mm is 18 to 80% by volume together with the above-mentioned fiber-containing long pellet (A). The content of fiber of 1-3 mm in length is 2-2
By setting the content to 5% by volume, a molding material that gives a more stable and high-quality molded product can be obtained. Further, in order to more effectively exhibit the effect of improving the biting property with respect to the molding machine and the mechanical properties (particularly, impact properties) of the molded article, the content of a fiber having a length of 5 to 15 mm in all the reinforcing fibers in the molding material is required. The ratio is suppressed to less than 50% by weight, and the average length of the fiber-containing long pellet (A) is set to be 2.5 to 5 times the average length of the fiber-containing short pellet (B). Desirably, the total content of the reinforcing fibers contained in all the pellets is desirably adjusted to the range of 4 to 35% by volume.

The reinforcing fibers include inorganic fibers including glass fibers, carbon fibers, various metal fibers, etc., and various organic fibers of natural or synthetic nature. The reinforcing performance, corrosion stability, cost and the like are comprehensive. The most preferable from the standpoint of glass is glass fiber.

As described above, the present invention provides a great advantage in improving workability such as shortening the measuring time by improving the bite into the molding machine at the time of the molding process. Since the defect prevention function greatly contributes to the improvement of the mechanical properties and quality stability of the molded article, the molded article using the above molding material also has excellent mechanical properties and quality stability without defects. It is included in the protection scope of the present invention.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The fiber-containing resin pellet used in the present invention is manufactured by, for example, a method described below, and reinforcing fibers having substantially the same length as the pellet are aligned or twisted in the longitudinal direction of the pellet. The molding material of the present invention contains at least two kinds of such thermoplastic resin pellets. In the molding material, a fiber-containing elongate having a length of 5 to 15 mm is contained. The pellet (A) is contained in an amount of 5 to 55% by volume, and the content of the fiber having a length of 5 to 15 mm contained in all the pellets is 1 to 12%.
It has the first feature in that it is volume%.

That is, in the present invention, it is extremely important to ensure the mechanical properties, particularly the impact resistance, of the molded article without impairing the biting property into the molding machine. The content ratio of the fiber-containing long pellets (A) having a length of 5 to 15 mm is within the range of 5 to 55% by volume, and the content of the fibers having a length of 5 to 15 mm contained in all the pellets is 1 to 12%. It is important to adjust the volume%.

Incidentally, when injection molding or the like is performed using the molding material of the present invention, breakage of the reinforcing fiber due to kneading with a screw or injection pressure or the like is inevitable, and the pellet length of the fiber-containing long pellet (A) is inevitable. If it is less than 5 mm, the effect of improving the mechanical properties of the reinforcing fibers will not be fully utilized due to breakage during molding. On the other hand, when the pellet length of the pellet (A) is more than 15 mm, the pellets are liable to cause a bridging phenomenon particularly at the raw material charging hopper portion during the molding process, so that the pellets are less likely to bite into the molding machine. The handling properties such as gas transport also have an adverse effect, and the dispersion of the reinforcing fibers in the molded body becomes non-uniform, so that the dispersion of the mechanical characteristics increases.

Therefore, in order to ensure a sufficient effect of improving the mechanical properties without impairing the biting property at the time of molding,
The pellet length of the fiber-containing long pellet (A) is 5 to 15 m.
m, but more preferably 6
It is desirable that the thickness be 13 mm or more and 13 mm or less, more preferably 8 mm or more and 12.5 mm or less.

Next, it is essential to adjust the content ratio of the fiber-containing long pellet (A) in the range of 5 to 55% by volume. Thus, the content ratio of the pellet (A) is 5% by volume.
If the amount is less than 50%, the effect of improving the mechanical properties, especially the impact resistance, due to the inclusion of the reinforcing fibers will not be fully utilized. This also has an adverse effect on the handling properties, and furthermore, the dispersion of the reinforcing fibers in the molded body becomes non-uniform, and the dispersion of the mechanical characteristics increases.

The lower limit of the content of the fiber-containing long pellet (A), which is particularly preferred for improving both the mechanical properties of the molded article and the biting property during molding, is 6% by volume, more preferably 1% by volume.
0 volume%, a more preferable upper limit is 50 volume%, and still more preferably 47.5 volume%.

Further, in order to achieve the object of the present invention, the content of fibers having a length of 5 to 15 mm (hereinafter, sometimes referred to as long fibers (x)) contained in all the pellets is reduced to 1 to 12% by volume.
It is necessary to adjust to the range. Here, the content of the long fiber (x) contained in all the pellets is substantially determined by the content ratio of the fiber-containing long pellet (A) and the content of the fiber contained in the pellet (A). However, when the content of the long fiber (x) is insufficient, the effect of improving mechanical properties such as impact resistance becomes insufficient. The dispersion of the long fibers in the body becomes non-uniform, making it difficult to obtain a molded body having uniform and stable mechanical properties.

Therefore, the content of the long fibers (x) in the whole pellets is at least 1% by volume, more preferably 1.
5% by volume or more, more preferably 2% by volume or more, and 1%
It should be at most 2% by volume, more preferably at most 11% by volume, even more preferably at most 10% by volume.

In the present invention, by specifying the length and content ratio of the fiber-containing long pellet (A) and the long fiber (x) as described above, it is possible to prevent the lowering of the biting property into the molding machine while preventing the impact. Since the effect of modifying mechanical properties such as properties can be sufficiently enhanced, the size and content ratio of relatively short pellets used in combination with the fiber-containing long pellets (A) can be appropriately changed. In combination with the fiber-containing long pellets (A), in order to take advantage of the features of the long pellets (A) and to suppress the drawback, particularly the adverse effect on the biteability, it is necessary to use short-sized pellets used in combination. The fiber-containing short pellet (B) having a length of 1 to 3 mm is selected and its content ratio is set in the range of 18 to 80% by volume, and the content of the fiber having a length of 1 to 3 mm contained in all the pellets. From 2 to 25 It is desirable to be within the range of volume%.

That is, the fiber-containing short pellets (B) having a length of 1 to 3 mm have an effect of compensating for the drawbacks pointed out in the fiber-containing long pellets (A), thereby improving the biting property during molding and , The long pellet (A) and the long fiber
(x) is uniformly dispersed, and the production of a molded product having uniform and stable strength characteristics without voids, gas defects, etc. is further ensured.

As for the short pellets (B), the effect of improving the biting property and the long pellets (A) become shorter as the length becomes shorter.
The effect of accelerating dispersion is improved, but the pellet length is 1 m
If less than m, the effect of improving the mechanical properties becomes insufficient,
If it exceeds 3 mm, the effect of improving the biting property and the dispersibility with respect to the long fiber cannot be sufficiently exhibited.

A more preferable size of the fiber-containing short pellet (B) for more effectively exhibiting the above-mentioned effects when used in combination with the fiber-containing long pellet (A) is 1.8 to 3 mm.
Range.

In order to effectively exhibit the above-mentioned effects of the combined use of the short pellets (B) as a whole molding material,
The content ratio of the short pellet (B) in all the pellets is 18% by volume or more, more preferably 20% by volume or more,
It is good to be 80 volume% or less, more preferably 70 volume% or less. The content ratio of the short fibers (y) contained in the short pellets (B) as the short fibers (y) having a length of 1 to 3 mm in all the pellets is preferably the content ratio of the short pellets (B). For the same reason as specified above, at least 2% by volume, more preferably at least 3% by volume,
The content is desirably 25% by volume or less, more preferably 20% by volume or less.

Further, if the content ratio of the long fibers having a length of 5 to 15 mm in the total reinforcing fibers contained in the molding material (that is, all the pellets) becomes too large, the molding machine is used for the same reason as described above. Not only does the tendency for bite into the fiber to deteriorate, but also the uniform dispersibility of the long fibers during molding deteriorates, and the uniformity of mechanical properties and the quality stability tend to deteriorate. 5-1 in reinforced fiber
The content ratio of the long fiber of 5 mm is preferably less than 50% by weight, more preferably 48% by weight or less. As a result, the content ratio of the short fiber, particularly the short fiber having a length of 1 to 3 mm, is It is desirable that the content of the reinforcing fibers is 50% by weight or more.

Regarding the diameters of the fiber-containing long pellets (A) and the fiber-containing short pellets (B), as the pellet diameter increases, the state of dispersion of the reinforcing fibers at the time of molding deteriorates, and the mechanical properties of the molded article are reduced. However, this tends to cause variations, and the biteability of the molding machine tends to deteriorate. Therefore, the diameter of the pellets (A) and (B) is, for example, 0.9 to 3.5 mm in the case of glass fiber reinforced polypropylene pellets in consideration of handling properties during molding and mechanical properties as a molded body. Preferably, the range is 1.5 to 3 mm.

This can be expressed by the relationship between the pellet length (L) and the pellet diameter (D) of each of the pellets (A) and (B).
For the long pellet (A), L / D is 1.2 to 6,
More preferably, it is preferably in the range of 1.5 to 5. When the L / D of the pellet (A) is smaller than this range, the pellet becomes a thick pellet, the biteability to a molding machine is deteriorated, and the dispersibility of the reinforcing fiber is also deteriorated, so that the dispersion of the mechanical property value is increased. When the L / D of the pellet (A) exceeds this range, the pellet becomes elongated and the pellet is easily broken at the time of biting into the screw, and the length of the long fiber in the molded product is shortened, resulting in satisfactory mechanical properties. It becomes difficult to obtain characteristic values.

The L / D of the short pellet (B) is as follows.
If the L / D is smaller than this range, cracks are likely to occur at the time of cutting the pellets, and the handling properties are deteriorated due to fluffing of the reinforcing fibers. On the other hand, if the L / D exceeds this range, the pellets become thinner and the productivity becomes worse.
It tends to break during molding, making it difficult to obtain sufficient mechanical properties.

Long pellet (A) and short pellet (B)
The pellet length of the long pellet (A) is 2.5 times the pellet length of the short pellet (B).
It is desirable to adjust so as to be 5 times. However, if the pellet length of the long pellet (A) is less than 2.5 times the pellet length of the short pellet (B), it tends to be difficult to sufficiently exert the effect of improving the mechanical property values, particularly the impact properties. In addition, if it is 5 times or more, the pellet size is too different, so that the pellets (A) and (B) are separated (classified) at the time of molding including transfer, and the dispersion state of the reinforcing fibers becomes uneven. It is difficult to ensure uniformity and quality stability of the molded body. From such a viewpoint, it is more preferable that the pellet length of the long pellet (A) is 2.5 to 4.5 times the pellet length of the short pellet (B).

The total content of the reinforcing fibers contained in the molding material (all pellets) according to the present invention is preferably in the range of 4 to 35% by volume, and if less than 4% by volume, the amount of the reinforcing fibers as a whole is insufficient. In addition to this, not only a sufficient reinforcing effect cannot be obtained, but also with such a blended amount of reinforcing fibers, the biteability itself into a molding machine itself hardly matters, so that the features of the present invention need not be utilized. On the other hand, if the compounding amount of the reinforcing fiber as a whole exceeds 35% by volume, the impregnation of the reinforcing fiber bundle with the matrix resin becomes insufficient, and it becomes difficult to effectively exert the reinforcing effect itself in terms of the mechanical properties of the molded article. In this sense, the more preferable content of the reinforcing fibers in the molding material is 6% by volume or more and 30% by volume or less.

In the present invention, the thermoplastic resin constituting the matrix resin includes, for example, polyolefin resins such as polyethylene, polypropylene and polypropylene-ethylene copolymer; styrene resins such as polystyrene and polyvinylstyrene; nylon 6, nylon 66; Polyamide resin such as nylon 610, nylon 12, nylon 12, aromatic polyamide (nylon MXD), polyester resin such as polyethylene terephthalate and polybutylene terephthalate, polyoxymethylene (PO
M), polyphenylene oxide (PPO or PP
E), polycarbonate, AS, ABS, polyphenylene sulfide, polyetherketone, polyetheretherketone, polyethersulfone, etc., are non-limiting examples, and these can be used alone, and their copolymers and modified products can be used. Alternatively, it can be used as a derivative or a blend.

The method for producing the fiber-containing resin pellet constituting the molding material of the present invention is not particularly limited, but is usually produced by a method as described in, for example, Japanese Patent Publication No. 8-25200. For the concrete ladle, a continuous reinforcing fiber bundle is widened in a belt shape, and impregnated by passing it through a molten bath of a thermoplastic resin while maintaining this state, and then drawn out through a nozzle while converging the widened continuous reinforcing fiber, In this method, a continuous resin-impregnated fiber bundle is produced, cooled and solidified, and then cut into an appropriate length to produce fiber-containing resin pellets.

In this case, for example, Japanese Unexamined Patent Publication No.
As described in JP-A No. 6 (1994), if a method of impregnating the molten resin bath and taking it out while applying twist to the continuous reinforcing fibers is adopted, the impregnation of the reinforcing fiber bundle with the molten resin is promoted, and In a series of steps from the widening, the impregnation, and the drawing, the reinforcing fiber strands can be drawn while the fluffs of the short reinforcing fibers caused by the breakage of a part of the reinforcing fibers are wound together, so that the continuous reinforcing fiber bundle is cut. High-speed production can be performed stably without causing such troubles. In addition, the twist is given to the reinforcing fibers, so that the reinforcing fiber length in the pellets becomes slightly longer, and the fiber-containing pellets containing longer reinforcing fibers can be obtained with good productivity under excellent handling properties. .

By adopting a method in which the continuous reinforcing fiber bundle is impregnated with the resin and then cut to an arbitrary length, not only can a fiber-impregnated resin pellet having a desired length be easily produced, The length of the reinforcing fibers contained in the pellet is also preferable because it can be made almost the same as the length of the pellet.

When the reinforcing fiber is melt-impregnated with the thermoplastic resin, a resin having a low melt viscosity is selected or the melt viscosity is sufficiently low so that the thermoplastic resin can sufficiently impregnate the reinforcing fiber. It is desirable to heat the resin bath to a temperature. For example, when a polypropylene resin is used, the melt flow rate (MFR) (230
° C, 2.16 kgf) from [30 g / 10 min] to [500
g / 10 min], more preferably [40 g / 10 min] to
[300 g / 10 min], more preferably [60 g / 10 min]
Min] to [200 g / 10 min] are preferably used.

If the MFR of the polypropylene resin is less than the above range, it is necessary to lengthen the impregnation time in order to compensate for impregnation failure, and not only the productivity is reduced, but also if the resin is impregnated into the reinforcing fibers even if it can be produced. As a result, the reinforcing fibers fall off or scatter from the obtained pellets, causing a tingling sensation during handling, and reinforced fiber fragments adhered to the molded product, hindering the commercial value, and furthermore, the dispersibility of the reinforcing fibers Insufficiency results in large variations in mechanical characteristic values of the final molded product, and also lowers mechanical characteristics such as strength and elastic modulus, which is not preferable.

The type of the reinforcing fiber is not particularly limited.
As exemplified above, various natural or synthetic fibers can be used regardless of whether they are inorganic or organic, and glass fibers such as E-glass and S-glass, PAN-based and pitch-based carbon fibers,
Metal fibers such as stainless steel can be arbitrarily selected according to the desired mechanical property values or chemical property values including corrosion resistance, and can be used alone or in combination of two or more as necessary. Glass fibers are the most practical in view of overall chemical and chemical properties and costs.

As the form of the reinforcing fiber, roving (long fiber bundle) is most suitable for application to the above-mentioned preferable method for producing pellets, and the fiber diameter depends on the required mechanical characteristic value. You just have to choose the right one. For example, in the case of glass fiber, a glass roving in which a monofilament having a diameter of 6 to 25 μm, more preferably 8 to 20 μm is converged with an appropriate sizing agent is used. If the fiber diameter is less than the above range, not only is the productivity of the glass fiber bundle reduced and the cost is increased, but also when manufacturing the glass fiber reinforced thermoplastic resin pellets, when trying to increase the productivity of the pellets, the glass A large number of woven bundles (rovings) must be bundled, which is disadvantageous in terms of productivity and handling, such as an increase in the number of glass fiber robins when considering continuous production. On the other hand, when the fiber diameter exceeds the above range, the aspect ratio of the glass fiber decreases, and it becomes difficult to sufficiently exhibit the properties as the reinforcing fiber.

The number of converging glass fiber rovings is preferably 300 to 5000, more preferably 500 to 30 in order to ensure good impregnation of the thermoplastic resin.
00 is preferred.

It is also effective to subject the reinforcing fibers to an appropriate surface treatment in order to enhance the wettability with the resin. Examples of the surface treatment agent include silane-based, titanate-based, aluminum-based, chromium-based, zirconium-based, and silane-based coupling agents.A more preferable surface treatment agent when glass fiber is used is silane-based or titanate-based. Among them, particularly preferred are silane coupling agents, for example, aminosilanes such as γ-aminopropyltriethoxysilane, epoxysilanes such as γ-glycidoxypropyltrimethoxysilane, and vinylsilanes such as vinyltrichlorosilane. .

When a polypropylene-based or polyethylene-based resin such as polypropylene or propylene-ethylene copolymer is used as the thermoplastic resin, acid-modified polypropylene is used in order to increase the adhesive strength between the thermoplastic resin and the glass fiber. It is preferable to perform a surface treatment with an acid-modified polyolefin such as polyethylene or an ethylene-propylene-non-conjugated diene compound copolymer (EPDM).

Examples of the acid used for the modification include unsaturated carboxylic acids such as acrylic acid, methacrylic acid, maleic acid, fumaric acid, itaconic acid and sorbic acid, and derivatives thereof such as acid anhydrides, esters and amides. And metal salts such as maleic anhydride, itaconic anhydride, methyl acrylate, maleic monoamide, sodium methacrylate and the like can also be preferably used, and particularly preferred is maleic anhydride.

When the thermoplastic resin to be used is a polypropylene resin, an emulsion of a maleic anhydride-modified polypropylene resin is preferably used as a surface treatment agent for glass fibers.

These surface treatment agents may be previously attached to the reinforcing fiber roving prior to producing the above-mentioned fiber-containing resin pellets, or may be mixed in the impregnated resin.

The molding material of the present invention has the greatest characteristics when the length and the content ratio of the fiber-containing long pellet (A) are specified as described above, and is preferably used in combination therewith. The length and content ratio of the fiber-containing short pellet (B) are specified, and these pellets (A),
(B) alone can be used as a molding material. In addition to these, a thermoplastic resin pellet (C) substantially containing no fibers is used in combination, and the fiber-containing pellets (A) and (B) are so-called master batches. It can also be handled as pellets.

In this case, the fiber-containing pellet (A),
The blending ratio of (B) and the fiber-free pellet (C) is as follows:
It is desirable to set the weight ratio of [(A) + (B)] / (C) to a ratio of 0.25 to 4. By the way, if it is out of this range, the dispersion of the reinforcing fibers in the molded body tends to be non-uniform, and the dispersion of the mechanical characteristics tends to be large.

The material resin of the resin pellet (C) containing substantially no fiber used at this time is not particularly limited. However, the resin pellet (C) is constituted so as to promote dispersion of the reinforcing fiber during molding. The flow characteristics of the thermoplastic resin to be used are preferably selected to be inferior to the flow characteristics of the thermoplastic resin constituting the fiber-containing resin pellets (A) and (B). For example, when the thermoplastic resins constituting the pellets (A), (B) and (C) are all polypropylene-based resins, the melt flow rate (230 ° C., 2.16 kg)
f), that is, [MFR of polypropylene resin constituting (A), (B)] / [MFR of polypropylene resin constituting (C)] is 2 or more, more preferably 6 or more. It is desirable to choose. Further, as a constituent resin of the resin pellet (C), the MFR is 1 to 6 in consideration of the fluidity of the material and the mechanical properties of the molded body.
It is good to use the thing of 0, More preferably, in the range of 5-30.

It is desirable to use the same type of resin having a high affinity for each other for the resins constituting the pellets (A), (B) and (C), but they have sufficient mutual compatibility in the melt-kneading step. As long as they are different resins, different resins can be used in combination.

The molding material of the present invention essentially contains the fiber-containing long pellets (A) as described above, preferably the fiber-containing short pellets (B), and further the fiber-free resin pellets (C). But further includes a dispersant; a lubricant; a flame retardant; an antioxidant; an antistatic agent;
Light stabilizer; ultraviolet absorber; carbon black; crystallization accelerator (nucleating agent); plasticizer; coloring agent such as pigment and dye; talc, calcium carbonate, mica, clay, wollastonite, potassium titanate, and the like It is also effective to incorporate an appropriate amount of an inorganic filler such as whisker. These additives may be added as a master batch or the like separately from (A), (B), and (C) at the time of molding.

[0056]

EXAMPLES Hereinafter, the structure and operation and effect of the present invention will be described in more detail with reference to examples. However, the present invention is not limited to the following examples, and the present invention is applicable to the above and following points. It is also possible to carry out the present invention with appropriate modifications as far as possible, and all of them are included in the technical scope of the present invention.

Examples and Comparative Examples Using thermoplastic resins and reinforcing fibers shown in the following components (a) to (c), these were blended at the ratios shown in Tables 1 and 2, and
A thermoplastic resin-impregnated glass fiber prepreg was produced by impregnating a thermoplastic resin while twisting the reinforcing fiber according to the method disclosed in JP-A-169445, and cut with a strand cutter, and shown in Tables 1 and 2. Glass fiber reinforced polypropylene resin pellet components of dimensions (A), (B)
I got

A molding material obtained by dry blending the obtained pellet components (A) and (B) or the pellet components (A), (B) and (C) at the ratios shown in Tables 3 and 4 below was used for an injection molding machine. A test piece (JIS standard) for measuring physical properties was prepared using (JSW J200SA manufactured by Japan Steel Works, Ltd.), and an evaluation test of mechanical properties was performed. The results are shown in Tables 3 to 7.

(1) Raw materials used Thermoplastic resin component (a): All pellets (a-1); consisting only of a crystalline propylene portion having a density of 0.909 g / cm ³ , and having an MFR (230 ° C., 2 .16 kg
f) is 60 g / 10 min polypropylene. (a-2): consisting of only a crystalline propylene portion having a density of 0.909 g / cm ³ , and having an MFR (230 ° C., 2.16 kg
f) is 100 g / 10 min polypropylene.

Component (b): pellets or crushed product having an acid value of 26 mgKOH / g modified with maleic anhydride;
Density 0.95g / cm ^Three , Molecular weight 40,000 (GPC
Weight average molecular weight by the method), melt viscosity 16,000 cp
s (160 ° C) polypropylene polymer (Sanyo Chemical Industries
"Umex 1001" manufactured by a trade company.

Reinforcing fiber component (c): glass fiber bundle (roving) E-glass fiber bundle of 650 tex having an average diameter of 13 μm, surface-treated with γ-aminopropyltriethoxysilane and then treated with an emulsion of maleic acid-modified polypropylene.

Fiber reinforced resin components (A) and (B): glass fiber reinforced thermoplastic resin, both columnar pellets Fiber reinforced resin pellets manufactured using components (a) to (c) described in Tables 1 and 2 (B-1)-(B-8) and (A-1)-
(A-9).

Resin component not containing reinforcing fiber (C): All pellet components (C-1); 90% by weight of a crystalline polypropylene part (X unit) having a density of 0.909 g / cm ³ and 39% by weight of ethylene content 10% by weight of a propylene-ethylene random copolymer portion (Y unit), each having a MFR (230 ° C., 2.16 kgf) of 15 g / 10 m
in propylene-ethylene block copolymer.

Component (C-2): 90% by weight of a crystalline polypropylene part (X unit) having a density of 0.909 g / cm ³ , and 10% by weight of a propylene-ethylene random copolymer part (Y unit) having an ethylene content of 39% by weight % (C)
-2) The overall MFR (230 ° C, 2.16 kgf) is 6.
5 g / 10 min propylene-ethylene block copolymer.

The measured value of the content of the Y unit was 2 g
Is dissolved in 300 g of boiling xylene for 20 minutes to be dissolved, then cooled to room temperature, and the precipitated solid phase is filtered and dried by a glass filter, and the value is back calculated from the weight.

(2) Physical property evaluation method (2-1) Reduction time of measurement time The biting property of the molding material into the molding machine was evaluated by the measurement time in the injection molding machine. Specifically, the evaluation was made based on the measurement time reduction rate calculated from the following equation. In addition, the thing with a weighing time shortening rate of 20% or more showed favorable mechanical characteristic values. Weighing time reduction rate (%) = 100 x [(A-4 or A-5 weighing time)-(weighing time of each compounded)] / (A-4 or B-5 weighing time)

(2-2) Void fraction Measured in accordance with JIS K 7053. This value is 2
% Or less shows good mechanical property values.

(2-3) Flexural strength The flexural strength was measured according to JIS K7203. The measurement temperature was 23 ° C.

(2-4) Izod impact value (with notch) Measured according to JIS K 7110. The thickness of the test piece was 4 mm and the measurement temperature was 23 ° C.

[0070]

[Table 1]

[0071]

[Table 2]

[0072]

[Table 3]

[0073]

[Table 4]

[0074]

[Table 5]

[0075]

[Table 6]

[0076]

[Table 7]

From Tables 1 to 7, the following can be considered.

(1) Embodiment No. 1 to 10 are all examples satisfying all the requirements of the present invention, have good biteability into a molding machine, short weighing time, small void ratio of molded product, high mechanical property value and small variation. .

(2) Comparative Example No. 2, 6, 7 This is an example in which a pellet having a length of less than 5 mm is used as the long pellet A, and the biteability into a molding machine is good, but the Izod impact value of the molded article is low.

(3) Comparative Example No. 8 The length ratio of the long pellet A exceeds 15 mm and the ratio of the length of the long pellet A to the length of the short pellet B is too large. Not improved enough.

(4) Comparative Example No. 5, 11 This is an example in which a pellet longer than 3 mm is used as the short pellet B, in which the biteability into the molding machine is not sufficiently improved, the void ratio in the molded body is increased, and the mechanical property value is low and uneven. Is also big.

(5) Comparative Example No. 9 Since the length of the short pellet B is too short, the Izod impact value of the molded product is low. Further, since the length ratio of the long pellets A and the short pellets B is large, there is a large variation in the mechanical property values of the molded body.

(6) Comparative Example No. 3 Since the mixing ratio of the short pellets B is too large, the Izod impact value of the molded product is low.

(7) Comparative Example No. 10 The mixing ratio of the long pellet A exceeds 55% by volume,
And 5 to 15 mm of reinforcing fiber (GF) is 50% of the total GF.
Since the content is more than 10% by weight, the effect of improving the biteability in the forming machine is low, and the void ratio of the molded product is high, the mechanical property value is low, and the variation is large.

(8) Comparative Example No. 4 The length ratio of the long pellets A and the short pellets B is slightly too small, so that the Izod impact value of the molded product is slightly low.

(9) Comparative Example No. 12 Content of long pellet A and short pellet B, 5 to 15 m
Although the content range of the m-length and 1-3 mm long reinforcing fibers is appropriate, the mechanical properties of the molded article are large because the reinforcing fibers having a length of 5-15 mm exceed 50% by weight with respect to all the reinforcing fibers. Large variation in values.

[0087]

The present invention is constituted as described above, and the content ratio of the fiber-containing long pellets (A) and the content of the long reinforcing fibers in the molding material are set within specific ranges. By specifying the content ratio of the fiber-containing short pellet and the content of the fiber having a length of 1 to 3 mm in all the pellets, the bite into the molding machine is good, and the measurement can be performed efficiently in a short time. A fiber-reinforced thermoplastic resin molding material that can provide a fiber-reinforced resin molded product that is capable of producing no fiber or gas defects due to entrainment of air and that has excellent strength, elastic modulus, impact resistance, etc. By using the molding material, it is possible to obtain a fiber-reinforced resin molded article having uniform and stable mechanical properties under stable molding processability.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Koichi Hashimoto 1-5-5 Takatsukadai, Nishi-ku, Kobe City Inside Kobe Research Institute, Kobe Steel Ltd. (72) Inventor Toshiaki Okumura 1-chome, Takatsukadai, Nishi-ku, Kobe-shi No.5-5 Kobe Steel, Ltd. Kobe Research Institute F-term (reference) 4F201 AB25 AC01 AD04 AR12 AR15 BA02 BC02 BC12 BC15 BC17 BC19 BC37 BL42 BL44

Claims (7)

[Claims] 1. A pellet containing at least two kinds of thermoplastic resin pellets in which reinforcing fibers having substantially the same length as the pellets are arranged or twisted in the longitudinal direction of the pellet, and have a length of 5%.
The content ratio of the fiber-containing long pellet (A) of 5 to 15 mm is 5 to 55% by volume, and the content of the fiber of 5 to 15 mm in length contained in all the pellets is 1 to 12% by volume. Characteristic fiber-reinforced thermoplastic resin molding material. 2. The content ratio of the fiber-containing short pellet (B) having a length of 1 to 3 mm is 18 to 80% by volume, and the content of the fiber having a length of 1 to 3 mm contained in all the pellets is 2 to 2.
The molding material according to claim 1, wherein the amount is from 25 to 25% by volume. 3. The molding material according to claim 1, wherein the content of the fiber having a length of 5 to 15 mm in the total reinforcing fibers in the molding material is less than 50% by weight. 4. The molding according to claim 2, wherein the average length of the fiber-containing short pellet (A) is 2.5 to 5 times the average length of the fiber-containing short pellet (B). material. 5. The molding material according to claim 1, wherein the total content of the reinforcing fibers in all the pellets is 4 to 35% by volume. 6. The reinforcing fiber is a glass fiber.
5. The molding material according to any one of the above items 5. 7. A fiber-reinforced resin molded article which is molded using the fiber-reinforced thermoplastic resin molding material according to any one of claims 1 to 6.