JP2000289023A - Inorganic fiber-containing thermoplastic resin pellet, molding method using the pellet and molded product - Google Patents

Abstract

PROBLEM TO BE SOLVED: To facilitate manufacture of a pellet and to manufacture a lightweight molded product having excellent physical property balance by incorporating a thermoplastic resin having a specific flexual modulus and a specific wt.% of inorganic fibers arrayed in parallel with each other and having substantially the same length as that of the pellet, and specifying a length of the pellet. SOLUTION: A soft thermoplastic resin having a flexual modulus of a range of 50 to 1,000 MPa and glass fiber as an inorganic fiber are used. A glass fiber bundle is guided to a die, brought into contact with a soft molten thermoplastic resin supplied from an extruder, and then drawn from the die. The drawn strands are cooled, then taken off by a take-off unit, then cut in a length of 3 to 100 mm by a cutter, and then pelletized. Further, as the inorganic fibers, fibers arrayed in parallel with each other and having substantially the same length as that of the pellet are use, and its content amount is set to 10 to 90 wt.%. Thus, the molded product having a light weight and excellent physical properties can be easily manufactured.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inorganic (glass) fiber-containing thermoplastic resin pellet which can be used for injection molding, extrusion molding and the like. In detail, excellent in manufacturing and handling, less fiber breakage during melt kneading, especially
The present invention relates to an inorganic fiber-containing thermoplastic resin pellet having excellent strength and rigidity and capable of molding a molded article having an arbitrary apparent density, a molding method, and a molded article.

[0002]

2. Description of the Related Art Conventionally, in order to improve the strength, rigidity and heat resistance of a thermoplastic resin, a reinforcing method using an inorganic fiber such as a glass fiber has been generally performed. As a reinforcing method, for example, pellets obtained by simple blending and melt-kneading using chopped strand glass fibers are often used. However, when injection molding is performed using these pellets, the glass fiber length in the final molded product is substantially 0.5 m.
m or less, and the reinforcing effect of the glass fiber cannot be fully utilized. For this reason, a fiber-reinforced pellet has been proposed in which strands are arranged in parallel by drawing a glass fiber bundle while impregnating with a resin, and the fibers are cut to keep the fibers long.

[0003] In these fiber-reinforced pellets, the wettability of glass fiber and thermoplastic resin is important. For example, Japanese Patent Publication No. 63-37694 discloses a thermoplastic resin having a shear rate of zero when the shear rate is zero. It is disclosed that a material having a melt viscosity of less than 100 Ns / cm ² is used. As the thermoplastic resin, thermoplastic polyester, polyamide, polysulfone, polyoxymethylene, polypropylene, polyarylene sulfide, polyphenylene oxide / polystyrene blend,
High-strength, high-performance thermoplastic resins such as polyetheretherketone and polyetherketone are exemplified.

In other words, inorganic fibers such as glass fibers, carbon fibers, and metal fibers are intended to enhance the strength and rigidity of a matrix resin by blending these fibers. This is the same as
Needless to say, the thermoplastic resin used is mainly a thermoplastic resin classified as an engineering plastic having high strength and rigidity. Therefore, there is only disclosure of a polypropylene resin as another resin.

[0005] Polypropylene resins have been widely used in the automobile field due to demands for recyclability and the like, and reinforced resins using glass fibers have also been used. For example, Japanese Patent Application Laid-Open No. 8-259,753 discloses that as a resin, a polypropylene resin having an atactic polypropylene content of less than 5% by weight and an unsaturated carboxylic acid and / or
Alternatively, a pellet made of a long glass fiber of 2 to 50 mm using a modified polypropylene resin modified with an anhydride thereof is disclosed, and it is shown that both strength and rigidity are excellent.

Further, a molded article using long fiber pellets in a state where these glass fibers are arranged in parallel to each other is cut in the fiber during melt-kneading in molding by injection molding or the like, and the final molded article has Fiber length may not be enough. Further, although the strength and rigidity are excellent, the impact resistance may not be sufficient. For this reason, Japanese Patent Laid-Open No. 6-3
No. 40784, JP-A-8-3396,
It is disclosed that an elastomer such as an ethylene elastomer or a styrene elastomer is blended.

However, since a pellet containing long glass fibers is originally used as a molding material, the melt viscosity at the time of melt-kneading is high, and the blending of these elastomers further deteriorates the melt fluidity. I have. For this reason, it is extremely difficult to form large molded products and thin molded products. For this reason, it is difficult to maintain the length of the glass fiber in the molded product long by making use of the characteristics of the long fiber of the raw material pellet, and in fact, the field of application is limited. In addition, if the thermoplastic resin serving as the matrix has high strength and high rigidity, it is difficult to cut the pellets of the strand after the pultruding, and there is a problem such as generation of cutting powder.

On the other hand, in the case of an inorganic fiber reinforced resin molded article formed by injection molding, if the amount of fiber such as glass fiber is increased in order to improve the strength and rigidity, the weight of the molded article increases and the glass fiber Warpage deformation tends to increase due to anisotropy due to orientation. For this reason, in order to reduce the weight, a foam injection molding method has been proposed in which a foaming agent is mixed into a raw material and molding is performed while foaming a resin as a molded product (JP-A-7-247679). In this foam injection molding method, it is not easy to obtain a sufficient expansion ratio even if a considerable amount of a foaming agent is used to achieve weight reduction. Moreover, even if the expansion ratio is sufficiently obtained, the appearance is impaired, such as the occurrence of silver on the molded product,
Poor uniformity may not ensure sufficient performance. Further, it is difficult to apply the method to thin molded products, and the field of application is greatly restricted.

The above-mentioned Japanese Patent Application Laid-Open No. 6-340784 discloses that an ethylene-based elastomer, a styrene-based elastomer and a specific inorganic filler are used together with a density of 1.0.
A compact of 10 g / cm ³ or less is described, and a lightweight compact is an object of the invention. However, as is clear from the examples, the density of the molded product is 1.03 to 1.10 g.
/ Cm ³ , which is much higher than the density of the polypropylene resin, and is far from the weight reduction desired from the market.

[0010] In order to solve these problems, international publication WO97 is proposed to reduce the weight while maintaining mechanical properties such as strength, rigidity and impact resistance and appearance quality.
/ 29896 discloses that a fiber-reinforced resin pellet containing relatively long fibers is used, a springback phenomenon is generated by the contained fibers, and the resin being molded is expanded by the springback phenomenon to obtain a lightweight molded product. An expansion molding method is disclosed. According to this method, the weight of the molded article can be sufficiently reduced without impairing the mechanical properties.
It can be said that this is effective in reducing the weight of the fiber-reinforced resin molded product.

The molding method described above enables molding with a wide expansion ratio and has excellent bending strength, bending rigidity and impact resistance despite weight reduction. Due to these characteristics, it has potential application in a wide range of fields. However, there are fields where higher levels of impact resistance are required for some applications. In particular, in the case of parts such as automobiles, the conversion of materials from metal to resin is rapidly progressing from the viewpoint of energy saving and resource saving. In construction and civil engineering materials, there is a demand for resin-made lightweight materials in view of depletion of wood, improvement in durability and workability. Furthermore, recyclable thermoplastic resins are receiving attention due to social demands for resource saving and waste reduction.

For these thermoplastic resin materials, various physical properties have been improved by blending a polypropylene resin or an inorganic filler such as talc or rubber with the polypropylene resin mainly in consideration of recyclability. However, these materials are naturally limited in weight reduction in order to achieve both moldability and physical properties.

[0013]

SUMMARY OF THE INVENTION The present invention overcomes such disadvantages of the prior art, facilitates the production of inorganic fiber-containing pellets having an inorganic fiber length substantially equal to the pellet length, improves the injection moldability, and improves the molding efficiency. Increase the impact resistance of the product, especially in injection or injection compression molding, in the molding of expansion molded products that expand the mold cavity and expand the molten resin,
An object of the present invention is to obtain a light-weight molded product excellent in physical properties such as moldability and impact resistance.

[0014]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to solve the above-mentioned problems, and as a result, a long fiber pellet composed of an inorganic fiber such as a glass fiber and a thermoplastic resin has been used. As a result of intensive research on the selection, the strength and rigidity of conventional matrix resins are completely different, and when using a soft resin, not only is it easy to produce pellets, but also the fiber length can be increased using this. It was found that the molded product that was molded while keeping it was able to obtain a molded product with excellent physical properties such as bending characteristics, impact characteristics, and weld strength, and that the effect was particularly remarkable with a lightweight molded product obtained by expansion molding. Was. The present invention has been completed based on such findings.

That is, the present invention provides: (1) a thermoplastic resin having a flexural modulus of 50 to 1,000 MPa, and 10 to 90% by weight of inorganic fibers arranged in parallel with each other and having substantially the same length as a pellet; Length 3
Inorganic fiber-containing thermoplastic resin pellets of up to 100 mm. (2) The inorganic fiber-containing thermoplastic resin pellet according to the above (1), wherein the thermoplastic resin contains 0.01 to 10% by weight of a modified thermoplastic resin modified with an unsaturated carboxylic acid or a derivative thereof. (3) the thermoplastic resin is a polypropylene resin,
Flexural modulus 100-800MPa, melting point 140-1
The inorganic fiber-containing thermoplastic resin pellet according to the above (1) or (2), which is at 70 ° C. (4) A molding material comprising 30 to 90% by weight of the inorganic fiber-containing thermoplastic resin pellet (A) and 70 to 10% by weight of the thermoplastic resin (B) according to any one of the above (1) to (3). (5) A molding method in which the resin pellet or the molding material according to any of (1) to (4) is melted and kneaded, and the mixture is molded by injection or injection compression into a molding die cavity. (6) The resin pellet or the molding material according to any of the above (1) to (4) is melt-kneaded and injected or injected and compressed into the molding die cavity, and then the molding die cavity volume is increased. Expansion molding method. (7) The expansion molding method according to the above (6), wherein a gas is injected into the molten resin after the expansion of the cavity volume of the molding die is started. (8) A molded article molded by the molding method according to the above (6) or (7), having an inorganic fiber content of 10 to 60% by weight and an average fiber length of 2 to 20 mm. (9) The molded article according to (8), which has an apparent density of 0.2 to 1.0 g / cm ³ .

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail. The inorganic fiber-containing thermoplastic resin pellets of the present invention have a flexural modulus of 50 to 1,000 MPa and are arranged in parallel with each other and have almost the same length as the pellets.
Contains 90% by weight of inorganic fiber and has a length of 3 to 100 mm
And inorganic fiber-containing thermoplastic resin pellets. The thermoplastic resin used in the present invention has a flexural modulus of 50 to 1,000 MPa, preferably 100 to 800 MPa.
It is a soft thermoplastic resin in the range of MPa. Here, if the flexural modulus is less than 50 MPa, strength,
Heat resistance is not sufficient, and if it exceeds 1,000 MPa, moldability and impact resistance may not be sufficient. The soft thermoplastic resin is not particularly limited and includes, for example, ethylene;
Polypropylene resins such as propylene; homopolymers of olefins such as butene-1, and copolymers thereof, and copolymers of these with other copolymerizable unsaturated monomers. These may be used alone or in combination of two or more.

Among these, examples of polyolefin resins include high-density, medium-density, and low-density polyethylenes, linear low-density polyethylenes, ethylene-vinyl acetate copolymers, and ethylene-ethyl acrylate copolymers. And polypropylene-based resins such as propylene homopolymer, propylene-ethylene random copolymer, propylene-ethylene-butene-1 random copolymer, and propylene-ethylene block copolymer. In the present invention, among these, a polypropylene resin is particularly preferable. Examples of the polypropylene resin include a polypropylene resin having low isotactic regularity, a propylene / ethylene random copolymer, a propylene / ethylene / butene-1 random copolymer, and a propylene / ethylene block copolymer.

The soft thermoplastic resin used in the present invention may be classified into the category of elastomers such as ethylene-propylene elastomer, but is preferably not excellent in elastomer properties. Those used as general thermoplastic elastomers are not preferred in view of the melt fluidity of the resin. Therefore, if it is a polypropylene-based resin, a resin containing a crystal part is preferable.

Above all, a polypropylene resin containing 0 to 4% by weight of ethylene or butene-1 is preferred. However, a general polypropylene resin has a bending elastic modulus of 1,200 MPa or more, and the glass fiber reinforced polypropylene resin conventionally used is 1,500 MPa.
It is 300 MPa or more. Therefore, the polypropylene resin used in the present invention is preferably a special polypropylene resin.

For example, JP-A-63-243106, JP-A-63-243107, JP-A-2-25
For example, a polypropylene resin obtained by a production method described in JP-A-5707, JP-A-3-168234, JP-A-7-173223, or a known syndiotactic polypropylene resin can be used.

Particularly, the flexural modulus is 100 to 800MP.
a, a soft polypropylene resin having a melting point in the range of 140 to 170 ° C. is preferably used from the viewpoint of heat resistance. Hereinafter, examples of preferred soft polypropylene-based resins will be described. As the soft polypropylene resin, (a) the flexural modulus is 100 to 800 MPa, and (b) the melting point is 140 to
Examples thereof include a propylene homopolymer at 170 ° C., a copolymer of propylene and another olefin, or a mixture thereof. Specifically, (I) a propylene homopolymer and / or a copolymer containing 4% by weight or less of other olefin units may be used. ) Olefin units other than propylene 10 to 80
You may use the composition which consists of a propylene-type copolymer containing the weight%.

However, the particularly preferred soft polypropylene resin (I) is characterized in that, in addition to (a) the flexural modulus and (b) the melting point, (c) the isotope carbon nuclear magnetic resonance spectrum ( ¹³ C-NMR) ), Rrrr / (1-mmmm) × 100 is 10-6.
0%, (d) containing a propylene homopolymer having a melting enthalpy (ΔH) of 10 to 100 J / g measured by a differential scanning calorimeter (DSC) and / or other olefin units of 4% by weight or less. 100 to 20% by weight of the copolymer and (II) 10 to 8 olefin units other than propylene.
It is a polypropylene resin comprising 0 to 80% by weight, preferably 0 to 50% by weight of a propylene copolymer containing 0% by weight.

Hereinafter, in the present invention, the flexural modulus is 50
Desirable properties (a) to (d) related to a soft polypropylene-based resin of up to 1,000 MPa will be described. First, the soft polypropylene resin preferably has (a) a flexural modulus of 100 to 800 MPa, more preferably 200 to 700 MPa. If it is less than 100 MPa, strength and rigidity are insufficient, and if it exceeds 800 MPa, impact resistance and low-temperature impact resistance become insufficient. The flexural modulus is a value obtained in accordance with JIS-K7202. (B) a melting point of 140 to 170 ° C., preferably 150
１６165 ° C. Here, the melting point is a melting peak temperature (Tm) measured by a differential scanning calorimeter (DSC). If the melting point is lower than 140 ° C., sufficient heat resistance cannot be obtained. This melting point was measured using a Perkin-Elmer DSC
This is a value determined as a melting peak temperature in accordance with JIS K7121 by performing measurement using −7.

For the propylene homopolymer of the component (I) and the copolymer containing 4% by weight or less of other olefin units, (c) isotope carbon nuclear magnetic resonance spectrum ( ¹³ C-NMR) Rrrr / (1-mmmm) × 100 is 10 to 60
% Is desirable. If this value is less than 10%, the heat resistance is insufficient, and if it exceeds 60%, the flexibility is insufficient. From these aspects, preferred rrrr /
(1-mmmm) × 100 is in the range of 15 to 55%. Here, rrrr refers to a three-dimensional structure in which five methyl groups as side chains are alternately located in opposite directions to a main chain formed by carbon-carbon bonds composed of any five consecutive propylene units, or a ratio thereof. The mmmm means a three-dimensional structure in which all five methyl groups as side chains are located in the same direction with respect to a main chain formed by carbon-carbon bonds composed of any five consecutive propylene units, or a ratio thereof. Means

Incidentally, this rrrr / (1-mmmm) ×
100 is a value measured as follows. That is, using JNM-FX-200 (manufactured by JEOL Ltd., ¹³ C-nuclear resonance frequency 50.1 MHz), measurement mode: proton complete decoupling method, pulse width: 6.9 μs (45
°), pulse repetition time: 3 s, integration frequency: 1000
0 times, solvent: 1,2,4-trichlorobenzene / deuterated benzene (90/10% by volume), sample concentration 250 mg / 2.5
Under the conditions of milliliter solvent and measurement temperature: 130 ° C, ¹³
A C-NMR measurement was performed, and the difference in chemical shift due to the stereoregularity of the methyl group, that is, 22.5-1.
The pentad fraction was measured from the area intensity ratio of each peak of mmmm to mrrm appearing in the 9.5 ppm region, and rrr was measured.
The value of r / (1-mmmm) × 100 was determined.

Further, regarding the above component (I), (d)
The enthalpy of fusion (ΔH) measured by DSC is 10
Desirably, it is 100 J / g. ΔH is 100 J /
If it exceeds g, flexibility may be impaired, and the object of the present invention may not be achieved. This ΔH is usually 20 to 100 J /
g. Note that the ΔH is the value of Perkin-El.
The measurement was performed using DSC-7 manufactured by Mer Co., Ltd.
It is a value determined as the total heat energy absorbed during crystal melting according to −7122. The rate of temperature rise and fall in the measurement of the melting point and ΔH by DSC is 10 ° C./min.

The propylene homopolymer of component (I) and the copolymer containing 4% by weight or less of other olefin units have a boiling n-heptane insoluble content of 40 to 95%.
Those in the range of weight% are preferred. If the boiling n-heptane insoluble content exceeds 95% by weight, flexibility may be impaired, and if it is less than 40% by weight, sufficient mechanical strength tends not to be obtained. From the viewpoint of the balance between the flexibility and the mechanical strength, the more preferable boiling n-heptane insoluble content is in the range of 45 to 93 wt%. In addition, the boiling n-heptane insoluble content is a value obtained by using a Soxhlet extraction tester and calculating from the extraction residue after extracting with boiling n-heptane for 6 hours.

In the soft polypropylene-based resin, the polypropylene-based resin used as the component (A) is
Melt index (MI) is 0.5 to 1,000 g /
It is desirably in the range of 10 minutes, preferably 2 to 600 g / 10 minutes. If the MI is less than 0.5 g / 10 minutes, molding is difficult, and if it exceeds 1,000 g / 10 minutes, the mechanical properties of the obtained molded product may be insufficient. From the viewpoint of the balance between the moldability and the mechanical properties of the molded product, the more preferable MI is in the range of 5 to 500 g / 10 minutes. MI is a value measured under the conditions of a load of 2.16 kg and a temperature of 230 ° C. in accordance with JIS K7210.

The soft polypropylene resin comprising the component (I) or the components (I) and (II) is, for example, a single-stage gas phase polymerization method, a single-stage slurry polymerization method, a multi-stage gas phase polymerization method, a multi-stage slurry polymerization method, or a blending method. And the like. For example, when produced by a polymerization method, a solid catalyst component composed of magnesium, titanium, a halogen atom and an electron donor, and a solid component composed of a crystalline polyolefin used as needed, an organic aluminum compound, Propylene may be homopolymerized or propylene and other olefins may be copolymerized in the presence of a catalyst system comprising an alkoxy group-containing aromatic compound and an electron donating compound used as needed.

Further, when a soft polypropylene resin is prepared by adding a peroxide to a relatively high molecular weight powder obtained by polymerization and decomposing it in an extruder to reduce the molecular weight, handling during molding processing becomes easy. This peroxide decomposes the resin,
Even if the molecular weight is reduced, the resin only has good fluidity (increase in MI) and hardly affects the above-mentioned pendad fraction, melting peak temperature and melting enthalpy. As the peroxide, for example, 2,5-dimethyl-2,
5-di- (t-butylperoxy) -hexane, 1,3
-Bis- (t-butylperoxyisopropyl) benzene or 2,5-di-methyl-2,5-di- (t-butylperoxy) hexyne-3 or the like, and if desired,
Antioxidants, stabilizers and chlorine scavengers can be added.

The soft polypropylene resin may optionally contain other resins and various additive components such as various stabilizers,
Inorganic or organic fillers, as well as antistatic agents, chlorine scavengers, antiblocking agents, antifogging agents, organic flame retardants, flame retardant aids, dyes, pigments, natural oils, synthetic oils, waxes, etc. Can be. When the flexural modulus used in the present invention has a good affinity with inorganic fibers such as glass fibers, the thermoplastic resin having a pressure of 50 to 1,000 MPa does not have an adhesive property. It is preferable to contain a modified modified thermoplastic resin, for example, a modified polyolefin resin, particularly a modified polypropylene resin. This modified polyolefin resin is preferable because it improves the interface strength between the inorganic fiber such as glass fiber and the resin and the resin, greatly improves the tensile strength and the like, and promotes the impregnation of the fiber bundle with the resin.

The unsaturated carboxylic acid used for the modification includes, for example, acrylic acid, methacrylic acid, maleic acid, fumaric acid, itaconic acid, crotonic acid, citraconic acid, sorbic acid, mesaconic acid, angelic acid and the like. And derivatives thereof include acid anhydrides, esters,
Examples include amides, imides, metal salts, and the like. For example, maleic anhydride, itaconic anhydride, citraconic anhydride, methyl acrylate, methyl methacrylate, ethyl acrylate, butyl acrylate, monoethyl maleate, acrylamide, monoamide maleate , Maleimide, N-butylmaleimide, sodium acrylate, sodium methacrylate and the like. Among these, unsaturated dicarboxylic acids and derivatives thereof are preferred, and maleic anhydride and fumaric acid are particularly preferred.

These unsaturated carboxylic acids and derivatives thereof may be used alone or in combination of two or more when modifying the polyolefin resin. The modification method is not particularly limited, and various conventionally known methods can be used. For example, a method of dissolving the polyolefin resin in an appropriate organic solvent, adding an unsaturated carboxylic acid or a derivative thereof and a radical generator, stirring and heating, or supplying the respective components to an extruder to carry out graft copolymerization. A method for performing the method can be used. The modified polyolefin-based resin preferably has an addition amount of the unsaturated carboxylic acid or a derivative thereof in the range of 0.01 to 20% by weight, preferably 0.02 to 10% by weight,
Particularly, a maleic anhydride-modified polypropylene resin is preferable.

The inorganic fiber used in the present invention is not particularly limited as long as it is a continuous fiber having high strength and rigidity. For example, metal fiber such as glass fiber, carbon fiber, silicon carbide fiber, stainless steel fiber, and copper fiber can be used. Can be exemplified. In particular, glass fibers are preferably used. As glass fiber,
E-glass, S-glass, etc., whose diameter is 3 to 30
μm, preferably in the range of 6 to 25 μm. In this case, if the fiber diameter is less than 3 μm, it becomes difficult to impregnate or handle the resin, and if it exceeds 30 μm, the appearance and physical properties of the molded product may be reduced. When compounding with a thermoplastic resin, it is usually used in the form of a fiber bundle obtained by collecting a plurality of glass filaments, so-called glass fiber roving.

In the present invention, in order to improve the wettability and adhesiveness with the resin, the glass fiber is used.
It may be previously treated with a surface treatment agent. Examples of the surface treating agent include silane-based, titanate-based, aluminum-based, chromium-based, zirconium-based, and borane-based coupling agents. Among these, silane-based coupling agents and titanate-based coupling agents are exemplified. Preferred are silane coupling agents.

Examples of the silane coupling agent include triethoxysilane, vinyltris (β-methoxyethoxy) silane, γ-methacryloxypropyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, β- (3, 4-epoxycyclohexyl) ethyltrimethoxysilane, N-β- (aminoethyl) -γ
-Aminopropyltrimethoxysilane, N-β- (aminoethyl) -γ-aminopropylmethyldimethoxysilane, γ-aminopropyltriethoxysilane, N-phenyl-γ-aminopropyltrimethoxysilane, γ-mercaptopropyltrimethoxy Silane, γ-chloropropyltrimethoxysilane and the like. Among them, γ-aminopropyltriethoxysilane, N-β-
Aminosilanes such as (aminoethyl) -γ-aminopropyltrimethoxysilane are preferred. The method for treating the glass fiber with the surface treatment agent is not particularly limited, and a conventionally used method, for example, an aqueous solution method,
Any method such as an organic solvent method and a spray method can be used.

The production of the inorganic fiber-containing thermoplastic resin pellet of the present invention will be described by taking glass fiber as an example. As the glass fiber bundle, from the viewpoint of resin impregnation, wettability with resin and adhesion, mechanical properties of the obtained composite material, cost, handleability, etc.
Those having 3,000 fibers and surface-treated with an aminosilane-based coupling agent are preferably used. Next, the glass fiber bundle is guided into a die, brought into contact with a soft molten thermoplastic resin supplied from an extruder, and then pulled out of the die. At this time, the glass fiber bundle can be treated with a liquid substance having a boiling point higher than the temperature of the molten resin in the die, such as liquid paraffin. The strands drawn from the dies are cooled, taken up by a take-up machine, cut into a length of 3 to 100 mm, preferably 5 to 50 mm by a cutter, and pelletized. If the length of the pellet is less than 3 mm, the reinforcing effect of the molded product may not be sufficiently exhibited, and if it exceeds 100 mm, the bite becomes poor in the supply to the melt-kneading molding machine, and a stable uniform molded product is obtained. Production may be difficult.

The content ratio of the fiber and the resin component in the inorganic fiber-containing thermoplastic resin pellet of the present invention is such that the content of the inorganic fiber is 10 to 90% by weight, and the content of the soft thermoplastic resin component is 90 to 90%.
It is in the range of 10% by weight. When the content of the inorganic fiber is less than 10% by weight, the amount of the fiber is insufficient, and it may be difficult to quantitatively extract the fiber. Since the amount of the resin is large, it is difficult to control the shape of the pellet. On the other hand, if the content exceeds 90% by weight, impregnation with the resin may be difficult, and the pellet may be easily cracked at the time of cutting the strand, and it may be difficult to control the shape of the pellet as the inorganic fiber falls off. From the viewpoint of resin impregnating and drawing properties, especially in the case of glass fiber, the glass fiber is 20 to 85% by weight.
80 to 15% by weight of the soft thermoplastic resin component
Is preferably within the range.

In the present invention, the above-mentioned inorganic fiber-containing thermoplastic resin pellets (A) can be used alone as a molding material, but usually, the resin pellets (A) and the thermoplastic resin (B) are mixed together. The mixture can be a molding material. Here, as the thermoplastic resin (B), a resin which is the same as or similar to the thermoplastic resin of the resin pellet (A), or a resin having compatibility or affinity with the thermoplastic resin of the resin pellet (A) is used. Is preferred.

Here, as the thermoplastic resin (B), a soft resin similar to the resin of the resin pellet (A) can be used, but the high strength and high rigidity conventionally used as the inorganic fiber reinforced resin material can be used. Resins can also be used. The resin of the resin pellet (A) and the thermoplastic resin (B) may include, if necessary, other resins, rubbers, etc. for improving various physical properties.
Fillers and additives can also be included. In this case, the content is obtained by replacing a part of the thermoplastic resin.
Examples of additives include, for example, as an impact modifier,
Ethylene-propylene copolymer rubber, polybutadiene rubber, styrene-butadiene-styrene block copolymer rubber (SBS), styrene-ethylene-butylene-styrene block copolymer rubber hydrogenated with SBS (SEB)
Rubbers such as S) can also be added. However, in the present invention, a thermoplastic resin pellet (A) containing an inorganic fiber, which is generally made of a soft resin, is used. In order to further improve impact resistance, a thermoplastic resin elastomer is used instead of a thermoplastic resin elastomer. It is particularly preferable to use a soft resin having a low flexural modulus from the viewpoint of moldability.

In consideration of the required characteristics of the molded article, moldability, etc., metal powder, carbon black, graphite, talc, mica, clay, calcium carbonate, silica, aluminum hydroxide, magnesium hydroxide, calcium sulfate,
Inorganic fillers such as short glass fiber, calcium titanate whisker, fibrous magnesium oxysulfate,
Organic fillers such as crosslinked resin powder, crystallization accelerators, antioxidants (phosphorous, phenolic, sulfuric, etc.), neutralizers,
Foaming agents, lubricants, dispersants, peroxides, heat stabilizers, ultraviolet absorbers, light stabilizers, antistatic agents, flame retardants, flame retardant aids, plasticizers, process oils, epoxy compounds, metal deactivators And additives such as pigments and dyes such as zinc sulfide and titanium oxide.

As these additives, various stabilizers, antistatic agents, coloring agents, nucleating agents, peroxides and the like can be contained. In particular, in consideration of long-term stable performance and recycling, it is desirable to contain an antioxidant such as a phenol-based, phosphorus-based, or sulfur-based agent, a light stabilizer, and an ultraviolet absorber. These various additives are usually 500 to 500 parts by weight based on the weight of the resin in the inorganic fiber-containing molding material.
8,000 ppm, preferably 1,000 to 3,000
ppm, light stabilizer 500 to 10,000 ppm, preferably 1,000 to 6,000 ppm, ultraviolet absorber 50
0 to 10,000, preferably 1,000 to 6,000
ppm. These additives are added, for example, as a master batch using a polyolefin resin.

The thermoplastic resin (B) is not particularly limited, such as pellets, particles, and flakes, but is preferably formed by melt-kneading (including additives) into pellets. Further, as a thermoplastic resin (B),
Conventionally used flexural modulus of 1,000MP
High-strength, high-rigidity thermoplastic resin pellets or inorganic long fiber-reinforced thermoplastic resin pellets exceeding a can be used. For these thermoplastic resins, the molecular weight, melt viscosity, ie, melt index (MI) of the component (A) and the component (B) can be arbitrarily selected and used. The content of the thermoplastic resin as the component (B) is optional for adjusting the amount of inorganic (glass) fibers in the molding material, or adjusting the physical properties and melt viscosity by mixing the resin, and is usually 10 to 70 weight%. %, Preferably about 20 to 60% by weight. These have an inorganic fiber content of 5% in component (A).
0% by weight or more, the content of the inorganic fiber in the molding material is 10 to 60% by weight, preferably 15 to 50% by weight.
It is efficient to use it in the range of weight%.

The molding material of the present invention basically comprises
It consists of (A) or (A) + (B) components. However, if necessary, for example, in the case of molding a lightweight molded article by expansion molding, 0.01-3% by weight, preferably 0.1%
A small amount of a blowing agent such as １1% by weight can be contained.
Here, the type of the foaming agent is not limited as long as it generates gas by heat. For example, oxalic acid derivatives, azo compounds, hydrazine derivatives, semicarbazides, azide compounds, nitroso compounds, triazoles, ureas and related compounds, nitrites, hydrides, carbonates, bicarbonates and the like can be employed. More specifically, azodicarbonamide (ADCA), benzenesulfohydrazide, N, N-dinitropentamethylenetetramine,
Terephthalazide can be used. As the foaming agent, use not only these chemically decomposed foaming agents, but also physical foaming agents such as water, alcohol, propane, butane, a fluorine compound, and an organic solvent, as long as they generate gas when the resin is melted and heated. Can also. These blowing agents are usually used as a master batch (MB) which is melt-mixed at a high concentration in a thermoplastic resin such as a polyolefin resin.

The molding material of the present invention is used as a material for producing a final molded article by various molding machines. The molding method is not particularly limited, such as injection molding, injection compression molding, compression molding, and extrusion molding. However, it is preferably used for injection molding, injection compression molding, and particularly the following injection expansion molding. Less than,
The expansion molding method of the present invention will be described with reference to the drawings. FIG.
Fig. 1 shows a conceptual cross-sectional view of a molding die part which is a main part of the expansion molding method. In FIG. 1, 1 is a fixed mold, 2 is a movable mold, 3 is a molding mold cavity, 4 is a sprue, 5 is an injection resin, 6 is a gas injection pipe, and 7 is a gas exhaust pipe.

As apparent from FIG. 1, the expansion molding method of the present invention requires that the volume of the molding die cavity 3 can be changed. Usually, the thickness of the cavity in the mold opening / closing direction can be changed. That is, an injection molding device having a function of moving the movable mold 2 forward and backward is used. As the injection molding machine, a molding machine capable of generally performing injection compression molding, or an injection molding machine provided with a movable mold moving device in a general injection molding machine is used.

In the molding of the expansion molded article of the present invention, the movable mold 2 moves forward with respect to the fixed mold 1 in FIG. Is advanced to a position where the clearance becomes D1. Then, the inorganic (glass) fiber-containing expansion molding material is melt-kneaded and plasticized and measured by a screw device (not shown).
The molten resin 5 corresponding to the mold cavity clearance D2 is injected from the sprue 4 into the mold cavity 3. This D2 is the amount that fills and fills the entire molding die cavity by compression in the next step. here,
The melt-kneading of the inorganic (glass) fiber-containing expansion molding material
Apparatus and conditions for minimizing breakage of the inorganic (glass) fiber are preferred, and the compression ratio is usually 2.5 or less, preferably 2 or less.

When the molten resin containing inorganic (glass) fibers is injected, the injection amount of the molten resin is usually not more than 2/3 of the cavity volume of the molding die at the time of injection of the molten resin, the injection resin pressure is low, and In addition, the orientation of the inorganic (glass) fibers is low or substantially does not occur. A few seconds after the start of the injection of the molten resin, the movable resin 2 is again advanced to the position indicated by the one-dot chain line, that is, the position where the molding die cavity clearance D2 is reached, so that the molten resin 5 is compressed into the molding die cavity. Fill completely. Thereby, the surface of the molded product is cooled by the mold, and the surface of the mold is
Even small irregularities are completely transferred. After the surface is cooled to some extent and the skin layer is formed, the movable mold 2 expands by retreating to the position of the molding die clearance D3, which is the thickness of the expansion molded product, and is cooled to form the expanded molded product. Then, by opening the movable mold 2, the expansion molded product is taken out.

FIG. 1 illustrates a case where the movable mold 2 leaves a movable clearance C with respect to the fixed mold 1 when the filling by compression is completed, but this clearance C is eliminated. You can also. However, in order to spread the molten resin evenly in the entire mold cavity in the compression step, it may be preferable that a certain level of specified pressure acts on the appearance of a molded product. In the compression step, in addition to controlling the mold cavity thickness, a molding method for controlling the compression force of the resin may be employed. For example, in the case of integral molding of the skin material described later, the compression force can be controlled depending on the type of the skin material to prevent damage to the skin material.

The expansion molding method of the present invention is basically the above-mentioned method. However, nitrogen gas or the like can be injected from the gas injection pipe 6 after the movable mold 2 starts to retract. Injection of this gas assists the expansion by the inorganic (glass) fiber, and after expansion, presses the molded product against the surface of the mold, thereby contributing to improvement in mold transferability and appearance. Further, by controlling the pressure of the injected gas to a certain level as necessary and circulating the gas through the expansion molded product while exhausting the gas from the exhaust pipe, the cooling of the molded product can be promoted.
This means that the expanded molded product that has been insulated due to the formation of voids can be cooled from the inside of the molded product by changing it to the inconvenience of having to be cooled by an external mold. It greatly contributes to improvement. The injection gas is not particularly limited, but an inert gas such as a nitrogen gas or an argon gas is preferably used. Further, the gas pressure is selected in the range of 0.01 to 20 MPa, preferably in the range of 0.1 to 5 MPa.

The gas is usually a gas at room temperature, but a cooling gas having a temperature of 15 ° C. or lower, preferably 0 ° C. or lower can also be used. At this time, if a liquid such as volatile water is accompanied, the cooling effect is further improved. Further, the gas is opened to one of a gas nozzle provided inside a nozzle of an injection device for plasticizing and injecting the molten resin, or a sprue, a runner and a cavity provided inside the mold. It can be injected into the inside of the inorganic fiber-containing molten resin from a gas nozzle or a gas pin. Among these, it is preferable to inject from a gas pin provided in a mold, particularly from a gas pin opened in a cavity.

The above molding method is an example of a preferable molding method. However, depending on the shape and size of the molded product, the compression step can be omitted as a method of injection filling the molten resin. However, as described above, it is preferable to use the injection compression molding method from the viewpoints of resin orientation, prevention of orientation of inorganic (glass) fibers, easy filling of molten resin, mold transferability, and the like. Further, in the expansion molding method of the present invention, a skin material for covering and integrating the surface of the molded product can be attached to the mold in advance before molding. As described above, by using a mold in which a skin material is mounted before molding, an expansion molded product whose surface is integrally covered with the skin material is obtained. Here, as the skin material, cloth such as woven cloth or non-woven cloth, thermoplastic resin sheet, film, synthetic leather, thermoplastic resin foam sheet, and
Single layer material such as a film with a printed pattern, etc., and multi-layer material with a backing material made of thermoplastic resin or foamed sheet of thermoplastic resin used as a skin material such as thermoplastic elastomer or vinyl chloride resin it can. The skin material can be entirely coated on the molded product or can be partially coated.

The expansion molded article of the present invention is obtained by the above expansion molding method. This expansion molded product has a skin layer without voids on the surface, and is cooled under pressure, so that fine irregularities and patterns are faithfully transferred. The ribs, bosses, and the end of the molded product are faithfully formed. In addition, in the central portion, the inorganic (glass) fiber and the resin expand to form a generally continuous void. This void can be arbitrarily controlled by the content of the inorganic (glass) fiber, the length of the fiber, the expansion ratio, and the like. Therefore, as the expansion ratio, the apparent density of the lightweight molded product is 0.2 to 1.0.
g / cm ^3, preferably to be in the range of 0.3 to 0.8 g / cm ^3, typically 1.2 to 6, preferably 1.5 to
5

Therefore, the composition and expansion ratio can be selected in consideration of the apparent density, strength, rigidity and impact resistance required for the application, based on the resin composition and expansion ratio. As the expansion molded product, a molded product having a plate or a plate-shaped portion as a main part is preferable. In the expansion molded product of the present invention, even if glass fibers having a high specific gravity are used, the molded product is reduced in weight by expansion and the apparent density is significantly reduced. In addition, despite having a low apparent density and containing a soft thermoplastic resin having a flexural modulus of 50 to 1,000 MPa, it has a good balance of flexural strength, flexural rigidity and impact strength. This is due to the composite structure of the entanglement of the glass fibers and the continuous void structure between the surface and the intermediate portion, and is completely different from the conventional glass fiber-containing lightweight molded product made of a foaming agent.

It is completely unexpected that the expanded molded article of the present invention has excellent mechanical properties despite using a soft resin having a low flexural modulus. Therefore, in addition to the mechanical properties, a heat insulating property, a sound insulating property, and a sound absorbing property can be obtained by performing a process of transmitting sound through the surface skin layer. Therefore, the expansion molded product of the present invention is expected to be used as an energy-saving and resource-saving material in various fields such as automobile interior materials, building materials, and civil engineering in combination with its recyclability.

[0056]

EXAMPLES Next, the effects of the present invention will be described based on specific examples, but the present invention is not limited to these examples. Preparation of Flexible Polypropylene Resin (FPP) Preparation of Magnesium Compound A glass reactor equipped with a stirrer having an internal volume of about 5 liters was sufficiently replaced with nitrogen gas, and then ethanol was added to about 2,43.
0 g, 16 g of iodine and 160 g of metallic magnesium were charged and heated with stirring, and reacted under reflux conditions until hydrogen gas was not generated from the inside of the system to obtain a solid reaction product. The reaction solution containing the solid reaction product was dried under reduced pressure to obtain a magnesium compound.

Preparation of Solid Catalyst Component (W) 160 g of the magnesium compound (not pulverized) obtained above, 800 ml of purified heptane, were placed in a glass reactor having an internal volume of 5 liter which was sufficiently substituted with nitrogen gas. After charging 24 ml of silicon tetrachloride and 23 ml of diethyl phthalate, maintaining the inside of the system at 80 ° C., adding 770 ml of titanium tetrachloride with stirring, and reacting at 110 ° C. for 2 hours, the solid component was separated to 90 parts. Washed with purified heptane at ℃. Further, after adding 1,220 ml of titanium tetrachloride and reacting at 110 ° C. for 2 hours, it was sufficiently washed with purified heptane to obtain a solid catalyst component (W).

Then, 2.3 liters of purified heptane was charged into a 5 liter reaction vessel equipped with a stirrer, and 250 g of the solid catalyst component and 12 g of triethylaluminum were added.
g, cyclohexylmethyldimethoxysilane at a rate of 5 g. Thereafter, propylene was introduced until the partial pressure of propylene reached 0.3 kg / cm ² G, and the reaction was carried out at 25 ° C. for 4 hours. After the completion of the reaction, the solid catalyst component was washed several times with purified heptane, further supplied with carbon dioxide, and stirred for 24 hours.

Gas phase polymerization In a polymerization tank having an internal volume of 200 liters, 6.0 g / h of the solid catalyst component prepared above, 0.15 mol / h of triisobutylaluminum (TIBA), 1-allyl-
3,4-dimethoxybenzene (ADMB) 0.0042
Mol / h, cyclohexylmethyldimethoxysilane (CHMDMS) 0.012 mol / h, propylene 4
The solution was fed at a rate of 3 kg / hour, and polymerization was performed at 70 ° C. and 28 kg / cm ² G. The production amount of the polymer was 30 kg / hour.

The intrinsic viscosity [η] (at 135 ° C. in decalin) of the polymer obtained by this polymerization was 4.6 deciliter / g. Further, the amount of the boiling n-heptane insoluble component of the polymer was 91.5% by weight, [η] of the boiling n-heptane insoluble component was 4.87 dL / g, and the boiling n-heptane soluble component was [η]. ] Was 1.70 deciliter / g.

On the other hand, the ¹³ C-NMR spectrum of the homopolymer (mmmm: 0.749, rrrr: 0.05
Pentad fraction rrrr / (1-mm) calculated from 3)
mm) × 100 was 21.1%, the melting point (melting peak temperature) measured by DSC was 160.0 ° C., and the enthalpy of fusion (ΔH) was 74.5 J / g. In addition, no reversal bond regarding the head-to-tail bond of propylene was observed.

[0062] 2,5-dimethyl-
2,5-di- (t-butylperoxy) -hexane was mixed, and further added with an antioxidant, a stabilizer, and a chlorine scavenger, mixed and extruded with a 40 mmφ extruder.
Melt index (MI) [230 ° C, 2.16 kg
Load] yielded a pellet of 10 g / 10 min. The polymer was decomposed with peroxide to reduce the molecular weight. However, the pentad fraction, the melting peak temperature, and the melting enthalpy did not change even with the reduced molecular weight polymer. Press molding from the pellets, 3m thick
m, a 10 mm wide strip-shaped test piece is cut out from this sheet, and in accordance with JIS K7203,
A bending test was performed. The flexural modulus was 600 MPa.

Example 1 A glass fiber (fiber diameter: 13 μm, an aminosilane-treated glass fiber bundle consisting of 600 fibers) was contact-treated with liquid paraffin having a boiling point of 358 ° C., and then passed between compression rolls. Led inside. The resin supply amount and the drawing speed are controlled so that the content of the glass fiber in the pellets becomes 70% by weight, and the soft polypropylene-based resin (FPP): 27% by weight and the maleic anhydride-modified polypropylene: After contact impregnation with a resin melt (230 ° C.) consisting of 3% by weight, this is drawn out as a strand, taken off, cooled and cut to a length of 12%.
mm glass fiber-containing soft polypropylene resin pellets were obtained. 50% by weight of soft polypropylene pellets containing glass fiber (A) and soft polypropylene resin (FPP)
50% by weight was dry-blended to obtain a molding material.

The injection molding machine used a screw having a mold clamping force of 450 t and a compression ratio of 1.9 in order to minimize breakage of glass fibers. The molding die is 400mm x 200m
A mold for molding a plate-shaped molded product having a variable mx thickness (two gates at each central part divided into two equal parts) was used. This is an injection molding apparatus having a mold structure equipped with an IPM unit (made by Idemitsu Petrochemical Co., Ltd.) for moving the movable mold forward and backward so that the volume of the molding mold cavity can be changed. The mold was provided with a facility for injecting and exhausting nitrogen gas into the cavity.

After the molding material is melt-kneaded and plasticized and weighed, the molding die cavity thickness is set to D1 (2 mm), and a molten resin equivalent to the molding die cavity thickness, D2 (0.8 mm) is injected. did. After the start of the injection, the movable mold is advanced, compressed to a mold cavity thickness D2 (0.8 mm) and melted (resin temperature: 270 ° C.).
Was filled into a mold cavity (mold temperature: 90 ° C.). Two seconds after the completion of the compression filling, the movable mold was retracted and expanded so that the mold cavity thickness became D3 (2.5 mm).
Two seconds after the start of the retreat of the movable mold, a nitrogen gas of 1 MPa was injected into the resin from a gas pin. Thereafter, the mixture was cooled and solidified for 25 seconds, and after evacuation of gas, the mold was opened to obtain a plate-like expansion molded product. The plate-like expansion molded product has no large hollow inside, and is about 3.
It swelled by a factor of one and had a good appearance having a skin layer without generation of sink marks and silver. First evaluation result of molded product
It is shown in the table.

The evaluation method is described below. Glass fiber content (% by weight): The weight of the test piece was measured after incineration. Average glass fiber length: After the test piece was incinerated, it was directly photographed at a magnification of 10 times with a universal projector, and the average glass fiber length was determined with a digitizer using the image. Apparent density (g / cm ³ ): weight of molded article (g) / volume of molded article (cm ³ ) Area density (g / cm ² ): weight of molded article (g) / projected area of molded article (cm ²⁾ ) Bending test: A test piece for bending test consisting of 160 mm x 50 mm x thickness was cut out from the molded product, and the distance between fulcrums was 80.
mm three-point bending test at a test speed of 10 mm / min.
(3 ° C.). DuPont impact strength: load = 1 kg, hammer = 1/2 inch R, pan = 50 mm diameter. Weld strength: The maximum load in a bending test centered on the weld.

Example 2 In Example 1, 40% by weight of glass fiber-containing soft polypropylene resin pellets (A) and 60% by weight of soft polypropylene resin (FPP) were dry-blended to obtain a molding material. After the molding material was melt-kneaded and plasticized and measured, the molding die cavity thickness was set to D1 (3 mm), and a molten resin corresponding to the molding die cavity thickness and D2 (2 mm) was injected. After the start of the injection, the movable mold is advanced, compressed until it corresponds to the mold cavity thickness D2 (2 mm), and the molten resin (resin temperature: 250 ° C.) is filled in the mold cavity (mold temperature: 50 ° C.). . Then 30
After cooling for 2 seconds, the mold was opened to obtain a plate-like molded product.
The plate-like molded product was solid and had a good appearance having a skin layer without generation of sink marks and silver. Table 1 shows the evaluation results of the molded articles.

Example 3 In Example 1, 50% by weight of glass fiber-containing soft polypropylene pellets (A) and homopolypropylene resin pellets [tensile modulus = 1,500 MPa, melting point (Tm) = 166 ° C., MI (230 ° C.) , 2.16 kg load) = 300 g / 10 min] by dry blending to obtain a molding material.

After melt-kneading and plasticizing and weighing the molding material, the thickness of the molding die cavity is set to D1 (2 mm), and the molten resin corresponding to the molding die cavity thickness and D2 (0.8 mm) is injected. did. After the start of the injection, the movable mold is advanced and compressed until it corresponds to the mold cavity thickness D2 (0.8 mm) and molten resin (resin temperature: 250 ° C.)
Was filled in a mold cavity (mold temperature: 80 ° C.). Two seconds after the completion of the compression filling, the movable mold was retracted and expanded so that the mold cavity thickness became D3 (2.5 mm).
Two seconds after the start of the retreat of the mold, a nitrogen gas of 1 MPa was injected into the resin from a gas pin. Then cool for 30 seconds to solidify,
After the gas was exhausted, the mold was opened to obtain a plate-shaped expansion molded product. The plate-shaped expansion molded product had no large hollow inside, expanded about 3.1 times, and had a good appearance having a skin layer without generation of sink marks and silver. Table 1 shows the evaluation results of the molded articles.

Comparative Example 1 Glass fibers (fiber diameter: 13 μm, aminosilane-treated glass fiber bundle having 600 fibers) were contact-treated with liquid paraffin having a boiling point of 358 ° C., and then passed between compression rolls. Led inside. The resin supply amount and the drawing speed were controlled so that the glass fiber content in the pellets was 70% by weight, and the homopolypropylene resin [tensile elastic modulus = 1,500 MPa, melting point = 1
66 ° C, MI (230 ° C, 2.16 kg load) = 30 g
/ 10 min]: 27% by weight and maleic anhydride-modified polypropylene: 3% by weight resin melt (230 ° C.)
Was drawn out as a strand, pulled out, cooled and cut to obtain a glass fiber-containing polypropylene resin pellet having a length of 12 mm. 50% by weight of glass fiber-containing polypropylene resin pellets and homopolypropylene resin pellets [tensile elastic modulus = 1,
500 MPa, melting point (Tm) = 166 ° C., MI (230
(° C., 2.16 kg load) = 300 g / 10 min] An expansion molded product was obtained in the same manner as in Example 3 except that 50% by weight was dry-blended and used as a molding material. The plate-like expanded molded product had no large hollow inside, expanded about three times, and had a good appearance having a skin layer without generation of sink marks and silver. Table 1 shows the evaluation results.

Comparative Example 2 In Example 1, 65% by weight of soft poly (propylene) resin (FPP) and 35% by weight of glass fiber chopped strand (fiber diameter: 13 μm, fiber length: 3 mm) were molded by an extrusion molding machine. Using pellets obtained by melt kneading,
The molding was performed in the same manner as in Example 1 except that nitrogen gas was not injected. In addition, the average glass fiber length in a pellet is 0.
It was 43 μm. The molded product did not expand, and the surface sink was remarkable. Table 1 shows the evaluation results.

[0072]

[Table 1]

[0073]

According to the present invention, the thermoplastic resin pellets and molding materials containing inorganic fibers of the present invention can minimize the decrease in product rigidity, and can provide molded articles having excellent impact strength, especially DuPont impact strength which is important for practical use. Can be Further, the molding method is such that the resin in the molding die cavity has an expansion ratio of about 3 times, and has excellent physical properties in a lightweight molded product to be subjected to expansion molding. In addition, compared with the improvement of impact resistance by the addition of a general thermoplastic elastomer, it is excellent in melt fluidity and molding of a thin molded product becomes easy. In the case of a thermoplastic elastomer, the weld strength tends to decrease, but when the soft resin of the present invention is used, a high weld strength is exhibited, which is suitable for molding a large molded product or complicated molding. Furthermore, by using a specific high melting point polypropylene-based resin as the soft resin, the heat resistance of the molded article substantially conforms to that of the homopolypropylene resin. In addition, since the melt viscosity can be reduced, for example, in the case of an expansion molded product obtained by expansion molding, a lightweight molded product having good mold transferability and good appearance can be obtained. Expansion molded products have excellent strength, despite their low apparent density.
Rigidity is obtained, and these properties are substantially maintained, so that impact resistance and weld strength are greatly improved. Therefore, it is possible to contribute to weight reduction of automobile parts and building materials, and also to resource and energy saving.

[Brief description of the drawings]

FIG. 1 shows a conceptual cross-sectional view of a molding die part which is a main part of the expansion molding method of the present invention.

[Explanation of symbols]

 1: fixed mold 2: movable mold 3: molding mold cavity 4: sprue 5: injection molten resin 6: gas injection pipe 7: gas discharge pipe

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification code FI Theme coat ゛ (Reference) C08L 23/02 C08L 23/02 // B29C 47/00 B29C 47/00 (C08L 23/02 23:26) B29K 23:00 35:00 105: 12 F term (reference) 4F072 AA02 AA08 AB08 AB09 AB10 AB11 AD04 AG05 AH31 AJ02 AJ03 AK15 AK16 4F201 AA11 AA21 AB16 AB25 AG01 AG20 AM34 BA02 BC19 BC37 BD05 BK12 BL13 BL44 4F206 AA11 A21 AG01 AG20 AM34 JA03 JF01 JL02 JN25 JN26 JN27 JQ03 4F207 AA11 AA21 AB16 AB25 AC01 AG01 AG20 AM34 KA01 KF01 KL41 KL86 4J002 BB031 BB051 BB121 BB141 BB151 BB202 BB212 BP021 DA016 DA076 DC006 DJ006 DJ006

Claims (9)

[Claims] 1. A thermoplastic resin having a flexural modulus of 50 to 1,000 MPa and 10 to 90% by weight of inorganic fibers arranged in parallel with each other and having substantially the same length as a pellet, and having a length of 3 to 100 mm. Certain inorganic fiber-containing thermoplastic resin pellets. 2. A modified thermoplastic resin in which the thermoplastic resin is modified with an unsaturated carboxylic acid or a derivative thereof, in an amount of from 0.01 to 0.01%.
The inorganic fiber-containing thermoplastic resin pellet according to claim 1, which contains 10% by weight. 3. The thermoplastic resin is a polypropylene resin having a flexural modulus of 100 to 800 MPa and a melting point of 14.
The inorganic fiber-containing thermoplastic resin pellet according to claim 1, wherein the temperature is 0 to 170 ° C. 4. 4. A molding material comprising 30 to 90% by weight of a thermoplastic resin pellet (A) and 70 to 10% by weight of a thermoplastic resin (B) according to claim 1. 5. A molding method comprising: melting and kneading the resin pellet or the molding material according to claim 1; and molding the mixture by injection or injection compression into a molding die cavity. 6. The resin pellet or the molding material according to claim 1 is melt-kneaded, and injected or injected and compressed into a molding die cavity, and then the volume of the molding die cavity is enlarged. An expansion molding method for expanding. 7. The expansion molding method according to claim 6, wherein a gas is injected into the molten resin after the expansion of the cavity volume of the molding die is started. 8. A molded article formed by the molding method according to claim 6 or 7 having an inorganic fiber content of 10 to 60% by weight and an average fiber length of 2 to 20 mm. 9. An apparent density of 0.2 to 1.0 g / cm ^3.
The molded article according to claim 8, which is: