JPH11115005A - Manufacture of glass fiber-reinforced polypropylene molding - Google Patents

Abstract

PROBLEM TO BE SOLVED: To upgrade mechanical strength or the like and make a presentable look with the cut of a manufacturing cost by modifying polypropylene with acid and at the same time, kneading the polypropylene with glass fiber and further, injection-molding this molten kneaded product directly into a mold. SOLUTION: A molten kneaded product which is manufactured through an acid-modification step for polypropylene and a polypropylene and glass fiber kneading step which gets underway simultaneously with the acid- modification step, is directly injection-molded into a mold in an injection-molding step without passing through a step to pelletize the kneaded product. Consequently, the polypropylene is acid-modified so that it has an appropriate interfacial adhesive property with the glass fiber, and thus acquires an outstanding mechanical strength. When the tensile strength or rigidity of the polypropylene need to be increased, the homopolymer is used and when the anti-impact properties are required, the block polymer is used. In addition, the glass fiber and the polypropylene are in the blending ratio of 25-150:100 parts.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a glass fiber reinforced polypropylene (FRPP) which is inexpensive and has excellent mechanical strength.
The present invention relates to a molded article and a method for producing the same.

[0002]

2. Description of the Related Art Glass fiber reinforced polypropylene resin is
It is a material that is excellent in mechanical strength, chemical properties, heat resistance and moldability, and is lightweight and inexpensive. For this reason, it is widely used for injection molded articles such as machine parts, and it is expected that its use will be further expanded in the future.

[0003] By the way, polypropylene (P) which is a main constituent material of a glass fiber reinforced polypropylene molding is
Since P) has no polarity, it has poor interfacial adhesion to glass fibers. Therefore, even if the polypropylene and the glass fiber are simply melt-kneaded, almost no reinforcing effect can be obtained. For this reason, conventionally, in the production of glass fiber reinforced polypropylene, glass fiber whose surface is treated with a silane coupling agent or the like to improve the interfacial adhesion with polypropylene has been used.

[0004] However, even if modified glass fibers treated with a silane coupling agent or the like are used, the interfacial adhesion with polypropylene can hardly be improved. When short glass fiber is used, the matrix resin cannot transmit the force to the glass fiber because the glass fiber peels off even a small force from the polypropylene, and a composite material with sufficient mechanical strength is obtained. Absent.

In order to improve this, a separately prepared 0.4-5% by weight acid-modified polypropylene, ie, a so-called fully acid-modified polypropylene, is added to polypropylene as a main raw material so that the total amount of acid modification is 0%. 0.05% to 1%, so that the so-called fully acid-modified polypropylene is mixed with, for example, about 1/5 to 1/3 of the non-acid-modified polypropylene. I have. This is because the glass fiber 2 is conceptually shown in FIG.
The acid-modified polypropylene around 1 is glass fiber,
Alternatively, a glass fiber and a polypropylene are used as a structure in which an interfacial phase (layer) of the modified polypropylene 22 is formed by chemically bonding with the silane coupling agent on the surface and a phase (layer) of the polypropylene 23 which is not acid-modified surrounds the periphery. It is said that the interfacial adhesiveness with the polymer can be increased, and thereby the strength of the composite can be exhibited.

However, for this purpose, polypropylene pellets modified with 0.4 to 5% by weight of acid are separately produced, and this is melt-kneaded with non-acid-modified polypropylene pellets and glass fibers and extrusion-molded. Therefore, it is necessary to produce a glass fiber reinforced polypropylene molded article. Another step is required to modify the polypropylene with an acid. Moreover, the price of acid-modified polypropylene is high because its production volume is small,
As a result, the price of glass fiber reinforced polypropylene and a molded article using the same is increased.

Therefore, as a countermeasure, measures such as increasing the degree of acid modification have been taken in order to reduce the compounding amount (mixing ratio) of expensive acid-modified polypropylene. It will also raise.

Next, the pelletized acid-modified polypropylene is used as a raw material.
For this reason, what was partially oxidized at the time of the high-temperature strand for pellet manufacture will be used, and the appearance of an injection molded article will also be inferior. For these reasons, in order for the glass fiber-reinforced polypropylene molded article, especially the injection molded article to be further used in the future, it is necessary to make the molded article more inexpensive, stronger and more attractive than the current one. .

[0009]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and provides a glass fiber-reinforced polypropylene molded article which is excellent in mechanical strength and the like, is inexpensive and has a good appearance, and a method for producing the same. With the goal.

[0010]

Means for Solving the Problems In order to achieve the above-mentioned object, the present inventors have eagerly studied the mechanism itself of reinforcing polypropylene with glass fibers in a glass fiber-reinforced polypropylene molded article, and further, a production method based on the mechanism. Studied. As a result, in order to obtain sufficient interfacial adhesion to glass fibers, if the degree of acid modification of the entire polypropylene is the same or almost the same, polypropylene, which is acid-modified at a high concentration, is converted into unmodified polypropylene. It has been found that it is not necessary to mix a predetermined amount, that is, it is only necessary that the entire polypropylene has a uniform acid modification degree.

This is because high-density modified polypropylene adheres strongly to glass fibers, so that its molecular movement is hindered and the interfacial phase becomes brittle, causing stress concentration with the unmodified polypropylene phase. This determines the strength of the composite. Therefore, in order to effectively increase the strength of the glass fiber polypropylene formed article, it is preferable to optimally adjust the degree of acid modification of the polypropylene phase so that such stress concentration does not occur. That is, it is preferable that the modification amount is the same as that of the conventional one, and that the polypropylene is uniformly modified.

Further, based on this fact, the raw material composition is suitably adjusted, and the acid modification of the polypropylene and the kneading of the polypropylene and the glass fiber are performed using a screw type injection molding machine equipped with a specific kneading mechanism. Simultaneously, it is found that if this kneaded material is directly injection molded into a molded product, a glass fiber reinforced polypropylene molded product excellent in mechanical strength and excellent in productivity can be obtained,
The present invention has been completed. The present invention specifically has the following configuration.

[0013] The invention according to claim 1 is a method for producing a glass fiber-reinforced polypropylene molded article using an injection molding machine, comprising: an acid modification step for polypropylene; It is characterized by having a kneading step with glass fiber and an injection molding step of directly injecting the melt-kneaded product produced in both steps into a mold without processing it into pellets.

According to the above configuration, in an injection molding machine having a kneading mechanism, all the polypropylenes are acid-modified so as to be uniform and have an appropriate interfacial adhesiveness with the glass fiber, and consequently, the interfacial phase which adheres to the glass fiber. There is also no stress concentration between the embrittled and unmodified polypropylene phase, so that a glass fiber reinforced polypropylene molded body having excellent mechanical strength is produced.

According to a second aspect of the present invention, there is provided the method according to the first aspect, wherein the acid-denaturing step, the polypropylene and glass-refining step,
And the injection molding step comprises (1) 100 parts of granular polypropylene having an average particle diameter of 1 mm or less, and (2) 0.05-1.0 parts of carboxylic acid, dicarboxylic acid or anhydride thereof having an average particle diameter of 1 mm or less. And (3) a liquid or particulate organic peroxide having a half-life of 1 minute and a decomposition temperature of 150 ° C. to 250 ° C., or a half-life of 1 minute and a decomposition temperature of 1 minute.
An organic peroxide masterbatch having an average particle diameter of 1 mm or less containing an organic peroxide at 50 ° C to 250 ° C is 0.01-
0.2 parts and (4) 2 pieces of glass fiber chopped strand
5 to 150 parts of a raw material.

According to the above configuration, the mixing ratio and the particle size of each raw material are suitably set. Then, this raw material mixture is supplied to an injection molding machine having a kneading mechanism. in this case,
Since the mixing ratio and the particle size of the raw materials are appropriate, the acid modification and kneading of all the polypropylene in the injection molding machine are appropriately performed. Therefore, a good molded body having excellent mechanical strength can be manufactured with extremely high productivity.

According to a third aspect of the present invention, the acid, carboxylic acid, dicarboxylic acid or anhydride thereof used in the acid modification step of the first or second aspect is maleic acid or maleic anhydride. It is characterized by the following. With the above configuration, the addition reaction of carboxylic acid to polypropylene is smoothly performed using inexpensive maleic acid or maleic anhydride.

According to a fourth aspect of the present invention, there is provided a method for producing a glass fiber reinforced polypropylene molded article according to the second or third aspect, wherein the carboxylic acid, dicarboxylic acid, The average particle size of the anhydride and the organic peroxide masterbatch is not more than the average particle size of the granular polypropylene as a raw material.

According to the above constitution, the carboxylic acid and the like are mixed well with the polypropylene, and the polypropylene is sufficiently brought into contact with the carboxylic acid and the like due to the small size of each particle, so that the acid modification proceeds more smoothly.

According to a fifth aspect of the present invention, the injection molding machine according to the first to fourth aspects is a screw type injection molding machine having a kneading mechanism, which preheats a raw material supplied from a raw material supply port. A preheating feed zone to be sent downstream,
At least a kneading zone for kneading the raw material sent from the preheating feed zone, the screw in the kneading zone has at least one continuous spiral flight, and the flight is a raw material in a vertical cross-sectional shape. The wall on the front side in the feed direction is orthogonal or substantially orthogonal to the rotation axis of the screw, while the wall on the rear side in the rotation direction is formed so as to gradually reduce the screw diameter, and the cylinder in the kneading zone is in the axial direction of the screw. It has at least one continuous or intermittent trapezoidal or semicircular recess, and a gap is formed between the top surface of the flight and the inner surface of the cylinder to the extent that shearing acts on the raw material. It is characterized by being.

With the above structure, the raw material mixture supplied to the screw type injection molding machine having the kneading mechanism is heated in the preheating feed zone, the polypropylene is heated to near the melting point, and the organic peroxide is heated to the decomposition temperature. Is done. In the next kneading zone, shear shearing of the raw material is performed by the gap between the top surface of the flight and the inner surface of the cylinder, and since the gap is appropriately set, excessive shear shearing force acts to reduce glass fiber. There is no excessive cutting. For this reason, while the acid modification of the polypropylene proceeds sufficiently, kneading of the modified polypropylene and the glass fiber is properly performed. This molten mixture goes around the semicircular or trapezoidal concave portion of the cylinder wall surface, and is cut and remixed by screw flight to form a uniform molten material. This is shown in FIG. Then, the kneaded product of appropriately modified polypropylene and glass fiber is stored at the screw tip of the injection molding machine. Thereafter, it is injected into a mold attached to an injection molding machine to form a molded body. For this reason, a glass fiber reinforced polypropylene molding having excellent mechanical strength can be obtained.

According to a sixth aspect of the present invention, the gap between the top surface of the flight and the inner surface of the cylinder in the kneading mechanism of the screw type injection molding machine according to the fifth aspect of the invention is 0.1 to 1 mm.
mm. With the above configuration, the shearing between the top surface of the flight and the inner surface of the cylinder is further improved in relation to the viscosity of the molten mixture.

According to a seventh aspect of the present invention, the kneading zone of the screw-type injection molding machine according to the fifth or sixth aspect is such that the internal diameter of a cylinder portion of the screw-type injection molding machine is 1D. ~ 5D, more preferably
It is characterized by being in the range of 1.5D to 3D.
According to the above configuration, uniform and sufficient acid modification of the polypropylene and mixing of the acid-modified polypropylene with the glass fiber are performed in a state where the glass fiber is not cut or the like.

[0024]

Embodiments of the present invention will be described below. First, the raw materials will be described. Although it is polypropylene, either a homopolymer or a block copolymer is used depending on the purpose of use of the final product. That is, when it is desired to increase tensile strength or rigidity, a homopolymer is used, and when impact resistance is required, a block copolymer is preferably used.

In the present invention, the preferred form of the polypropylene is not a pellet but a granular polypropylene having a particle size of 1 mm or less in diameter. As such polypropylene, a granular material having an average particle size of 0.6 to 0.7 mm is commercially available, and this is most preferred. However, the present invention is not limited to this.

Although unpelletized products after polymerization can be used, they contain a large amount of fine particles having a particle size of 100 μm or less, so that dust is likely to be generated, which is not only unfavorable in working environment but also may cause dust explosion. It is preferable to add an appropriate wetting agent to such a raw material. Such wetting agents include, but are not limited to, sodium alkyl naphthalene sulfonate, polyoxyethylene sorbitan monolaurate, polyethylene glycol, glycerin, liquid paraffin, and the like.

Further, from the viewpoint of the material of polypropylene,
Preferably, it does not contain an antioxidant.

The carboxylic acid, dicarboxylic acid or anhydride thereof used for modification is usually maleic anhydride because of its bifunctionality and low cost. Here, the reason why the anhydride is used instead of maleic acid is that monomer reactivity is high and grafting is easy in terms of steric hindrance and polar factors. In addition, acrylic acid, methacrylic acid, maleic acid, fumaric acid, itaconic acid, citraconic acid, citraconic anhydride, itaconic anhydride and the like can be used.

As the organic peroxide, the decomposition temperature at a half-life of 1 minute is 150 ° C. to 250 ° C., preferably 160 ° C. to 1 ° C.
80 ° C. can be used. These include lauroyl peroxide, benzoyl peroxide, ditertiary butyl peroxide, tertiary butyl perbenzoate, dicumyl peroxide and the like.

Organic peroxides having a decomposition temperature lower than 150 ° C. decompose and lose their effect before the polypropylene melts, and organic peroxides having a decomposition temperature higher than 250 ° C.
It cannot work within the residence time in the cylinder of the injection molding machine, and there is no opportunity for a hydrogen abstraction reaction from the polypropylene. That is, in each case, the degree of acid modification of the polypropylene is low, and the effect is low.

The organic peroxide may be used in the form of a powder or a liquid. However, the organic peroxide is preferably a liquid in that it can be uniformly blended, but may be volatilized before being decomposed. Therefore, a powder having a high boiling point is more preferable. A powdery substance may explode if it is used. Therefore, from the viewpoint of work hazard prevention, 50
It is preferably used in the form of a masterbatch containing up to 80% by weight. However, in this case, it is a necessary condition that the particle size of the masterbatch is similar to that of polypropylene.

The amount of the organic peroxide is 0.01 to 0.2 part based on 100 parts of polypropylene. If the amount is less than this, the acid modification becomes insufficient, and if it is more than this, the molecular weight of the polypropylene decreases and the strength of the product is impaired. The glass fiber usually has a diameter of about 10 μm (about 5 to 1
It is preferable to use E-glass having a length of about 3 to 6 mm and a surface previously treated with a silane coupling agent in order to improve the interfacial adhesion to the modified polypropylene. In addition, as a silane coupling agent, amino silane, epoxy silane, and acrylic silane are usually used.

In order to converge the glass fibers, polyurethane, epoxy resin or the like is used as a film former. Then, several hundred to one thousand glass fibers converge and are supplied in the form of so-called chopped strands, which are cut to about 3 mm. In addition, glass fiber
If it is too long, the dispersibility decreases, which is not preferable,
Also, it is not preferable that the length is too short in terms of handling, product strength and the like.

Regarding the compounding ratio of the respective raw materials, the compounding ratio of polypropylene, carboxylic acid and organic peroxide is such that if the amount of modification of the polypropylene with an acid is too small, it is not possible to obtain proper adhesion to glass. Even if too much, there is a limit to the improvement of the adhesiveness as well as the molecular weight of polypropylene decreases,
The strength of the composition decreases. Generally, the carboxylic anhydride is 0.05 to 1.0% by weight, more preferably 0.1 to 0.2% by weight, based on the polypropylene.

Next, the kneading mechanism in the screw-type plasticizing mechanism is a well-known technique, and a general description thereof will be omitted.

In the present invention, it is preferable to use a screw injection molding machine having a kneading mechanism disclosed in Japanese Patent Publication No. 56-47847. FIG. 1 is a diagram conceptually illustrating an axial cross section of a screw-type injection molding machine having a kneading mechanism according to the present embodiment.

In FIG. 1, reference numeral 1 denotes a supply section of raw material polypropylene (PP), glass fiber, carboxylic acid, and organic peroxide. 2 is a cylinder, also called a barrel. Reference numeral 3 denotes a screw, which also functions as a piston during injection. Reference numeral 4 denotes a concave portion provided in the cylinder inner cylinder surface in the axial direction. 5 is a flight. 6 is an injection nozzle. Reference numeral 7 denotes a screw rotation drive motor. Reference numeral 8 denotes an injection hydraulic mechanism. 9 is a heater for the cylinder. However, among these, from the injection nozzle 6 to the heater 9 and the other check valves (not shown) are not directly related to the present invention, and the description thereof will be omitted.

I, II, III and IV shown in FIG.
Feed preheating zone, plasticizing kneading zone, degassing zone,
The weighing zone. In each of these zones, a raw material such as polypropylene is supplied by its own weight or through a feeder through a main supply hole 11 provided in the cylinder 2 from a supply unit 1 described later. Further, an exhaust hole 12 can be provided downstream of the cylinder 2.

FIG. 3 shows an AA cross section in FIG.
As shown in FIG. 3, the inner cylinder surface of the cylinder 2 in the feed preheating zone and the plasticizing kneading zone is not only shear shearing but also kneading of raw materials by compression and alternating current together with the flight 5 described later. A plurality of axial or substantially axial grooves 4 are provided. Then, a clearance between the inner surface of the cylinder 2 and the top of the flight 5 (tipclearance)
e) is set to 0.1 to 1 mm so as to be optimal for plasticizing the resin and mixing with maleic anhydride, and dispersing and mixing the glass fiber.

As shown in FIG. 1, the screw 3 is usually provided with a plurality of spiral flights 5 on the outer periphery of the plasticizing portion. For example, as shown in FIG. 1, the screw 3 in the plasticizing kneading zone and the deaeration zone has six flights 5. The width of the top of the flight 5 is, for example, 10 mm when the screw outer diameter is 60 mm.
As a result, the raw material supplied from the main supply hole 21 is transferred downstream by rotation of the screw 3, and the raw material is modified, mixed, and the like.

FIG. 3 conceptually shows the shear shearing step S and the mixing step P of the kneaded material as the screw 3 in the cylinder 2 rotates. In this figure, in the narrow gap between the top surface of the flight 5 and the inner surface of the cylinder 2, shearing shear S of the molten raw material is performed, and the existence of the groove between the flights 5 and the concave portion on the inner surface of the cylinder 2 and the presence of the Since the front wall in the rotation direction of the screw 2 is perpendicular to the rotation direction, it can be seen that the raw material is exchanged in the space formed by the grooves on both the flight 5 and the inner surface of the cylinder 2.

In the screw injection molding machine, generally, the supplied raw material is heated in the feed preheating zone, the raw material is kneaded in the plasticizing kneading zone, and the reaction gas generated by the kneading is degassed in the degassing zone. In the metering zone, the kneaded product in a molten state is stored and measured. However, in the present invention, since the raw material having a small average particle diameter is preliminarily mixed and supplied, heat is efficiently supplied to the material blended in the feed / preheating zone.
In the kneading section, the conversion / melting of the polypropylene and the decomposition of the peroxide are rapidly performed, and the addition reaction of the carboxylic acid is effectively performed.

If the kneading and kneading zone is too long, the size may be shortened due to the cutting of the glass fiber, and the energy efficiency may be reduced. Conversely, if it is too short, the acid modification of the polypropylene may be insufficient. Therefore, assuming that the cylinder inner diameter is D, within the range of 1D to 5D,
Further, although it depends on the particle size of the raw material, more preferably 1.5D
To 3D.

This reaction is carried out by adjusting the distance between the inner surface of the cylinder and the top of the flight to the extent that shearing occurs, specifically 0.1-1 mm, preferably 0.2-0.5 mm. Is efficiently performed, and the glass fiber chopped strands supplied simultaneously at this interval are opened to uniformly disperse the single fibers in the resin simultaneously. The concave portion on the inner surface of the cylinder has the effect of making the molten crude mixture more homogeneous.

Next, the acid modification will be described. As described above, conventionally, the idea of using, as a binder, a glass fiber and a polypropylene, which is so-called acid-modified polypropylene at a high concentration of 0.4 to 5% by weight, has been considered. For this reason, although the amount of acid modification of the entire polypropylene was the same in the cylinder of the screw injection molding machine, there was no idea that the acid modification would be uniform.

In the present invention, if the acid modification to the pre-polypropylene is the same, it is found that the strength of the glass fiber reinforced polypropylene is the same or rather excellent. Polypropylene, carboxylic acid and organic peroxide have an average particle diameter of 1 mm
The following, further, under a limited condition that the organic peroxide is in the form of fine particles or liquid, further provided with a kneading mechanism,
Preferably, by using a screw-type injection molding machine having an appropriate shape and dimensions of the kneading mechanism, appropriate acid modification of all the polypropylene in the screw-type injection molding machine is enabled.

Next, the required amount of the acid-modified polypropylene in the glass fiber reinforced polypropylene will be described.
This was confirmed by the following experiment. A simple polypropylene is blended with a polypropylene having an acid modification degree of 0.4% by weight, and the acid modification degree of the resin is 0, 0.04, 0.08 and 0.13% by weight (the symbols are M1 to M4, respectively). 4), tumble blended with a glass fiber chopped strand having a fiber diameter of 10 μm and a fiber length of 3 mm at a ratio of 50/50, and using a 100T direct injection molding machine.
ASTM D 638 Tensile Specimen and ASTM D790
Bending test pieces (both having a thickness of 3.2 mm) were formed using a set mold.

The effect of the interface modification by the acid modification was observed by SEM (scanning electron microscope) observation of the fracture surface of the tensile test piece. At an acid modification degree of 0.04 wt%, there is not much change, but at 0.08 wt%, a destruction occurs at a thin interface phase on the glass fiber surface, and at an acid modification degree of 0.13 wt%, the interface layer becomes several μ in thickness, Destruction is occurring outside. On the other hand, as shown in FIG. 4, the physical properties (mechanical strength) gradually begin to exhibit an effect from the acid modification degree of 0.04%, but various properties such as tensile strength, bending strength, and Izod impact are as follows.
It was found that sufficient performance was not exhibited unless the acid modification degree exceeded 0.1%.

Next, the mixing ratio of polypropylene to glass fiber will be described. This generally means that both are uniformly mixed and a certain range is determined in order to obtain the strength and the like required for the final product. When the ratio is too large, the flowability of the composition is deteriorated, and injection molding becomes difficult, which is not suitable for practical use. Thus, for 100 parts of polypropylene,
25 to 150 parts, more preferably 50 to 100 parts
Department.

Next, the mixing of the raw materials will be described. First, in order to prevent breakage due to collision with glass fiber particles as much as possible, and to make appropriate acid modification of polypropylene at the same time,
Raw materials excluding glass fibers are separately preliminarily mixed in a room by a drum blender for 10 minutes in advance, and then glass fiber chopped strands are added and premixed for another 2 minutes. In addition, as a method of better performing premixing of carboxylic acid, polypropylene powder and carboxylic acid powder are mixed at a high speed in a high-speed mixer (such as a super mixer), and the temperature is raised to slightly higher than the melting point of the carboxylic acid. There is a method in which a carboxylic acid is attached to the surface of polypropylene in the form of a thin film or penetrates inside.

The mixture thus produced was heated at 230 ° C.
It is charged from a hopper into a screw type injection molding machine equipped with a kneading mechanism heated to about 270 ° C. Further, in the injection molding machine, the mixture is melted, plasticized, and modified by an acid with rotation and heating of the screw.

[0052]

Embodiments of the present invention will be described below. Examples and Comparative Examples of the present invention were manufactured using the following raw materials. Polypropylene a. MS640 manufactured by Tokuyama Corporation Pellets having a diameter of about 3 mm b. Tokuyama PN640 Average particle size 0.5m
m, powder having particles of not less than 1.2 mm and not more than 0.5% by weight c. b was formed into pellets with a diameter of about 3 mm using an extruder. d. Mitsui Toatsu Chemical BJHH 1352 Approx. 3m in diameter
m pellets. e. Mitsui Toatsu Chemical BJHH average particle size 0.2mm,
Powder having particles of 1.0 mm or more and 0.2% by weight or less f. e is extruded into pellets with a diameter of about 3 mm. Maleic anhydride (first grade reagent) a. Powder mixture with a maximum particle size of 5 mm b. Maximum particle size Pulverized to 100 μm Peroxide a. 3 mm diameter pelletized masterbatch based on wax of ditertiary butyl peroxide b. a is crushed to a maximum particle size of 1.5 mm c. Ditertiary butyl peroxide with an average particle size of 1
Powder absorbed in 0 μm calcium carbonate powder. d. Ditertiary butyl perbenzoate (liquid) Glass fiber 245 s (chopped strand with a fiber length of 3 mm) manufactured by Nippon Boseki

Processing machine (1) Production by extrusion Each raw material was charged into a drum blender at the ratios shown in the table below and mixed, and then kneaded to obtain a mixture of 60 kg / h. Extruded with
The strand was cut with a water-cooled pelletizer to form a pellet. Kneading extruder: NRII-46mm SG twin screw extruder manufactured by Freesia Macross Co., Ltd. Cylinder temperature 200 ° C. or 230 ° C. Screw rotation speed 300 RPM L / D = 40 First stage L / D = 24 Inner kneading block 6.5 Second stage L / D = 16 Inner kneading disc 4.0 (2) Production of modified PP by direct injection molding Each raw material was charged into a drum blender at the ratios shown in the table shown below, and preliminarily mixed for 10 minutes. This mixture was kneaded with an injection molding machine equipped with a kneading mechanism and having a mold clamping force of 100 t, and an ASTM D638 tensile test piece and AS
An MT D790 bending test piece was injection molded using a set mold. The following two molding machines were used. Injection molding machine A Injection molding machine equipped with the kneading mechanism shown in FIG. 1 Injection molding machine B General injection molding machine with full flight screw, J75EII manufactured by Nippon Steel Corporation

(Measurement of Effect of Acid Modification) First, the above raw materials,
The result of the confirmation test on the acid modification of the glass fiber reinforced polypropylene molded article manufactured by the equipment will be described.

An extruded product is a pellet, and an injection molded product is a part of the molded product, and a hot press is used to prepare a film having a thickness of about 150 μm. The film is immersed in acetone for one day to remove unreacted maleic anhydride. After the removal, it was dried in vacuum at 80 ° C. for 24 hours, and the infrared absorption spectrum was measured. In this infrared absorption spectrum, C of 840 cm ^-1 polypropylene
C of 1785 cm ^-1 maleic anhydride on -H absorption
The grafting of maleic anhydride onto polypropylene can be measured by the absorbance ratio of ＝ O absorption. Further, the graft ratio of maleic anhydride was calculated from a calibration curve of a known sample. In addition,
This method is described in Fumio Ide et al., Polymer Journal Vol. 32, No. 11,
645-652 (1975). The measurement results are shown in Tables 1 and 2 below.

[0056]

[Table 1]

[0057]

[Table 2]

First, how to read both tables will be described. In the leftmost column of both tables, the symbol under "[Blending]" is PP.
Means polypropylene. For this reason, PPa is the polypropylene a. That is,
MS640 manufactured by Tokuyama Corporation Refers to a pellet having a diameter of about 3 mm. PPb is PN manufactured by Tokuyama Corporation
640 Particles having an average particle size of 0.5 mm and 1.2 mm or more represent a powder of 0.5% or less. Hereinafter, the same applies to PPc to PCf.

MAH refers to maleic anhydride.
For this reason, MAHa and MAHb respectively refer to the maleic anhydride reagents primary a and b described for the raw materials. The meanings of peroxides a, b, c, and d are the same, and refer to peroxides a, b, c, and d described for the raw materials.

Next, the meaning of the numerical values in the columns of Examples and Comparative Examples for measuring the effect of the acid modification will be described.
For example, the numerical value of the row (column) of PPb in Comparative Example 1 of Table 1 is 100, and the numerical value of the row of MAH-modified PPa is 0.
6. The value of peroxide a is 0.1 because Comparative Example 1 is PP
b, 100 parts of MAHa, and 0.1 part of peroxide a.
This indicates that the mixture was kneaded with one part of the raw material and injection-molded. In addition, all the compounding amounts of the peroxide are values of a pure content of the organic peroxide. In other comparative examples and examples, the meanings of the numerical values in the rows corresponding to the respective raw materials are the same.

Next, the manufacturing method of each example and comparative example will be described. Comparative Example 1 shown in Table 1 is a typical raw material mixing ratio when producing a modified polypropylene with maleic anhydride by an extrusion grafting method, and the graft ratio (degree of acid modification) of the obtained modified polypropylene with maleic anhydride. Is about 0.5%. In the prior art, as described above, usually, a polypropylene modified to this degree or more is diluted to 1/2 to 1/5 with unmodified polypropylene to obtain a composition suitable for glass fiber reinforced polypropylene. In addition, when 100% of the so-called high-density modified polypropylene is used, there is a risk that its physical properties may be deteriorated even if reinforced with glass fiber because of its small molecular weight.
Therefore, it is not used as it is.

Similarly, Comparative Example 2 is an example of a modified polypropylene which is used as it is without diluting, and has a graft ratio of 0.14%, which is a value at which the adhesion to glass fibers is sufficiently strong. For this reason, the modified polypropylene is suitable for producing high-strength vitrified fiber-reinforced polypropylene.

Similarly, Comparative Example 3 was an example in which pellet-shaped polypropylene was used as a raw material, and the melting temperature was 230 ° C. The results of maleic acid grafting were the same as Comparative Example 2. In the case of these extrusions, since the cylinder length of the extruder is sufficiently long and the residence time required for the graft reaction is obtained, there is no problem in the graft reaction even if the particle size of maleic anhydride is large.

Comparative Example 4 is an example in which an extruder having the same composition as Comparative Example 2 was replaced with an injection molding machine having a kneading mechanism used in the present invention. Due to the large particle size of the maleic anhydride, the graft ratio is significantly reduced to 0.06% and cannot be used for the purpose of reinforcing glass fibers. Comparative Examples 5 and 6 have the same raw material composition as Comparative Examples 2 and 4, except that polypropylene is changed to PPc and f, that is, pellets having a diameter of about 3 mm. Also in this case, the graft ratios were 0.07 and 0.08, respectively.
%, And cannot be used for glass fiber reinforcement.

Next, Table 2 shows Examples 1, 2 and 3.
Is an example in which maleic anhydride or peroxide was changed to a material having a small particle size at the same blending ratio. In these examples, the graft ratio is 0.14% or more, which is a value suitable for glass fiber reinforcement.
On the other hand, Comparative Example 7 manufactured using the injection molding machine B,
In Examples 8 and 9, although the same polypropylene raw materials as in Examples 1 and 2 were used, the graft ratio was significantly reduced, and the glass raw materials were not suitable for glass fiber reinforcement. Thus, in order to produce a modified polypropylene having an effect of glass fiber reinforcement using an injection molding machine, it is effective only when the production is performed under limited conditions of having a kneading mechanism and a raw material having a small particle size. You can see that.

(Examples of Glass Fiber Reinforced Polypropylene) Next, differences in various mechanical strengths (properties and physical properties) due to differences in the mixing ratio of the raw materials of the glass fiber reinforced polypropylene and its molded product and the equipment used in the production. Will be described. First, the test results are shown in Tables 3, 4, and 5.

[0067]

[Table 3]

[0068]

[Table 4]

[0069]

[Table 5]

In each of the examples and comparative examples in these tables, the [Formulation] column is the same as in Tables 1 and 2. In addition, the modified PP in the [formulation] column refers to the polypropylene produced in Comparative Example 1. Comparative Examples 12, 13 and 14 contain 33 parts of this modified polypropylene.

The unit of tensile strength, bending strength and flexural modulus is kg / mm ² , and the unit of Izod impact is kg
Cm / cm. Therefore, for example, Comparative Example 10 in Table 3
, The numerical value in the row of tensile strength of 9.7 indicates that the strength is 9.7 kg / mm ² .

The GF dispersion is obtained by observing the surface of the injection-molded article with the naked eye and determining the degree of dispersion of the glass fiber based on the criteria shown in Table 6.

[0073]

[Table 6]

Similarly, the surface smoothness is determined by observing the surface of the injection molding machine with the naked eye and judging based on the criteria shown in Table 7.

[0075]

[Table 7]

For this reason, for example, the GF dispersion in Comparative Example 10 in Table 3 is A. In this Comparative Example, 10 g of glass fiber was used.
This indicates that the dispersion failure per hit is zero. The surface smoothness of A indicates that the surface state is all smooth.

Next, the manufacturing method of each of the examples and comparative examples will be schematically described. Comparative Example 10 is based on the conventional method. PP and the like are blended according to the blending in the table, and 60 kg / h. From the second feed port downstream of the same extruder by a screw feeder at 60 kg / h. It was forcibly supplied. Then, the strand extruded from the die of the extruder was cooled in water and cut into 3 mm with a pelletizer to produce a glass fiber reinforced polypropylene pellet. Then, using an injection molding machine J75II of Japan Steel Works, the pellets were cast at a cylinder temperature of 260 ° C. and a mold temperature of 60 ° C. according to ASTM D638.
A tensile test piece and an ASTM D790 bending test piece were molded in a set mold.

Comparative Example 11 is based on a direct modified extrusion method. This method is disclosed in Japanese Patent Application No. 9-19 by the same inventor.
No. 755. According to the formulation in the table, PPb, MAH
a, peroxide a after mixing with a drum blender for 5 minutes, 2
60 kg / h is supplied to the main feed port of the screw extruder. From the second supply port of the same extruder. The glass fiber was forcibly supplied in the above. Then, the strand extruded from the die was water-cooled and cut with a pelletizer to produce a glass fiber reinforced polypropylene pellet. Next, the pellets were subjected to A injection at a cylinder temperature of 260 ° C. and a mold temperature of 60 ° C. using an injection molding machine J75II of Japan Steel Works.
It is formed by molding an STM D638 tensile test specimen and an ASTM D790 bending test specimen in a set mold.

Comparative Examples 12, 13 and 14 are based on the direct injection molding method. According to the formulation in the table, PP
a, PP, so-called sufficiently modified graft fiber having a graft ratio of 0.46% and glass fiber produced in Comparative Example 1 were mixed for 3 minutes by a drum blender, supplied to an injection molding machine equipped with a kneading mechanism, and kneaded. A at 260 ° C, mold temperature 60 ° C
The STM D638 tensile test piece and the ASTM D790 bending test piece were injection molded using a set mold. Therefore, it is close to the prior art glass fiber reinforced polypropylene.

Comparative Examples 15, 16 and 17 (Table 4)
This is based on a direct injection molding method using unmodified PP.
According to the formulation in the table, PP and glass fiber were mixed in a drum blender for 3 minutes, supplied to an injection molding machine equipped with a general type full flight screw and kneaded, and subjected to ASTM at a cylinder temperature of 260 ° C and a mold temperature of 60 ° C. D638 tensile test pieces and ASTM D790 bending test pieces were injection molded using a set-up mold.

Comparative Example 18 is based on the direct modified injection molding method, but the particle size of the raw material is out of the range of the present invention. According to the formulation in the table, PPb, MAHa, and peroxide a are blended, and mixed by a drum blender for 5 minutes. Then, glass fibers are added and mixed by a drum blender for 3 minutes. Next, this mixture was kneaded using an injection molding machine equipped with a kneading mechanism, and A was heated at a cylinder temperature of 260 ° C. and a mold temperature of 60 ° C.
An STM D638 tensile test piece and an ASTM D790 bending test piece were molded by setting.

Examples 4 to 10 (Table 5) are based on the direct modified injection molding method. According to the formulation in the table, PP
The pellets, MAH and peroxide are blended and mixed in a drum blender for 5 minutes. Thereafter, glass fiber is added and mixed again for 3 minutes in a drum blender. This mixture was kneaded using an injection molding machine equipped with a kneading mechanism, and further subjected to ASTM D6 at a cylinder temperature of 260 ° C. and a mold temperature of 60 ° C.
The test piece was injection-molded using a mold for setting a 38 tensile test piece and an ASTM D790 bending test piece.

Comparative Examples 19 to 22 are based on a direct modified injection molding method using a general machine. According to the formulation in the table, the PP pellet, MAH, and peroxide are blended and mixed for 5 minutes by a drum blender. Thereafter, glass fiber is added and mixed again for 3 minutes in a drum blender. This mixture was kneaded using an injection molding machine J75II manufactured by Nippon Steel Works equipped with a full flight type screw, and further subjected to ASTM D638 at a cylinder temperature of 260 ° C. and a mold temperature of 60 ° C.
It was injection-molded using a mold for setting a tensile test piece and an ASTM D790 bending test piece.

Next, the test results will be described. First, in terms of mechanical strength, looking at these three tables, it can be seen that PPb having a small particle size, MAHb having a maximum particle size of 100 μm and peroxide c of a peroxide b powder having a maximum particle size of 1.5 mm were used. , And Examples 1 to 7 and Examples 9 and 10 produced with a liquid peroxide d were used under the other conditions, that is, Comparative Examples 18 and 20 in which the particles of polypropylene and maleic anhydride were large. It can be seen that the tensile strength, flexural strength, flexural modulus and Izod impact value were greatly improved.

Also, it can be seen that Comparative Example 10 having a large graft ratio of polypropylene and Comparative Example 12 which is also close to the conventional example are not inferior but rather excellent. In addition, when compared with Comparative Example 12, it is manufactured in a separate step, and because the amount of production is small, expensive modified polypropylene is not used as a raw material.
Injection moldings are, of course, much better economically.

Further, the fifth embodiment is replaced with the fourth embodiment, the sixth embodiment, the seventh embodiment,
Compared to 8, the effect of the concentration of maleic anhydride,
It can be seen that there is a certain limit around 0.2 to 0.4 parts by weight with respect to 100 parts of polypropylene, that is, around 0.2% to 0.4% by weight with respect to polypropylene.

Further, with respect to polypropylene, Example 8 using pellets of about 3 mm in diameter, PPc, also has mechanical strength second to Examples 4 to 7. Furthermore, in Examples 9 and 10, since the content of the glass fiber was small, the mechanical strength was inferior to that of Examples 4 to 8 by that much,
Still, it is superior to Comparative Examples 21 and 22 manufactured using a general injection molding machine having no kneading mechanism. In addition, it can be seen that, in comparison with Comparative Examples 13 and 14 which are close to the prior art, they are not inferior but rather excellent.

By comparing Example 8 with Comparative Example 20, it can be seen how the difference in the injection molding machine and the difference in the size of the peroxide greatly affect the mechanical strength.

Next, evaluation of GF dispersion and surface smoothness will be described. Comparative Examples 19 to 19 Using a General Injection Molding Machine
In the case of No. 22, these evaluations are almost C or D, specifically, when the glass fiber is fuzzy, and there are only two cases where the surface smoothness is B at best. On the other hand, each of the embodiments uses an injection molding machine equipped with a kneading mechanism, and differs from the embodiment in that only maleic acid pellets (MAHa) are used. Similarly, an injection molding machine equipped with a kneading mechanism is used. In Comparative Example 18 used, all of these evaluations were A.

Although the present invention has been described based on the embodiments, it goes without saying that the present invention is not limited to the above embodiments. For example, a substance that does not act on the organic peroxide and does not react with the carboxylic acid may be mixed in the raw material in advance as a modifier, a colorant, or the like.

[0091]

As described above, according to the present invention, the glass fiber can be prepared without adding a polypropylene having a modification degree of 0.4 to 5% by weight to a pure polypropylene by a separate process. Reinforced polypropylene moldings can be produced by injection molding. Therefore, a significant cost reduction is possible. In addition, since polypropylene is a crystalline polymer, the effect of improving the mechanical strength and heat resistance by glass fiber is sufficiently exhibited, and thus the obtained product has better physical properties than conventional products.

Further, unlike the conventional method for producing glass fiber reinforced polypropylene, there is little opportunity for the polypropylene to come into contact with air in the state of a high-temperature strand for producing pellets.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram of a screw-type injection molding machine having a kneading mechanism.

FIG. 2 is a diagram conceptually showing a state in which a highly acid-modified polypropylene surrounds a glass fiber around the glass fiber, and a polypropylene that has not been acid-modified around the glass fiber.

FIG. 3 is a view conceptually showing a mixing mechanism of raw materials by shearing and compression of the screw type injection molding machine shown in FIG. 2;

FIG. 4 is a diagram showing a state of a change in physical properties of a composite material depending on the degree of acid modification of polypropylene.

[Description of sign]

 DESCRIPTION OF SYMBOLS 1 Supply part 2 Cylinder 3 Screw and extrusion piston 4 Axial recess on the cylinder inner cylinder surface 5 Spiral flight on the cylinder outer surface 6 Injection nozzle 7 Motor 8 Extrusion hydraulic mechanism 9 Heater

Claims (7)

[Claims] 1. A method for producing a glass fiber reinforced polypropylene molded article using an injection molding machine, comprising: an acid modification step for polypropylene; and a kneading step of polypropylene and glass fiber, which is performed simultaneously with the acid modification step. And an injection molding step of directly injection-molding the melt-kneaded product produced in the both steps into a mold. 2. The acid-modifying step, the kneading step of polypropylene and glass fiber, and the injection molding step are as follows: (1) 10 parts of polypropylene having an average particle diameter of 1 mm or less.
0 parts; (2) 0.05-1.0 parts of a carboxylic acid, dicarboxylic acid or anhydride thereof having an average particle diameter of 1 mm or less; and (3) a half-life of 1 minute and a decomposition temperature of 150 ° C. 250
0 ° C. liquid or particulate organic peroxide, or an organic peroxide masterbatch having an average particle size of 1 mm or less including an organic peroxide having a half-life of 1 minute and a decomposition temperature of 150 ° C. to 250 ° C. 2. The glass fiber reinforced polypropylene molded article according to claim 1, wherein the raw material comprises: 0.11 to 0.2 part; and (4) 25 to 150 parts of a glass fiber chopped strand. Manufacturing method. 3. The glass according to claim 1, wherein the acid used in the acid modification step or the carboxylic acid, dicarboxylic acid or anhydride thereof is maleic acid or maleic anhydride. A method for producing a fiber-reinforced polypropylene molded article. 4. The average particle diameter of the raw material carboxylic acid, dicarboxylic acid or anhydride thereof and the organic peroxide master batch to be treated in each of the above steps is equal to the average particle diameter of the raw material granular polypropylene. The method for producing a glass fiber reinforced polypropylene molded product according to claim 2 or 3, wherein: 5. The injection molding machine is a screw injection molding machine having a kneading mechanism, wherein a preheating feed zone for feeding a raw material supplied from a raw material supply port to a downstream side while preheating the raw material, and a feeding from a preheating feed zone. And at least a kneading zone for kneading the raw material that has been provided, wherein the screw in the kneading zone has at least one continuous spiral flight, and the flight is located on the front side in the longitudinal direction of the raw material in the feed direction. The wall is orthogonal or nearly orthogonal to the rotation axis of the screw, while the wall on the rear side in the rotation direction is formed so as to gradually reduce the screw diameter, and the cylinder in the kneading zone is continuous or intermittent in the axial direction of the screw. And at least one concave portion, and further, between the top surface of the flight and the inner surface of the cylinder, shearing of the raw material occurs. 3. A gap formed to the extent that the cutting works.
Or the manufacturing method of the glass fiber reinforced polypropylene molded body of Claim 4. 6. The glass fiber reinforced polypropylene molded article according to claim 5, wherein the gap between the flight top surface and the cylinder inner surface in the kneading mechanism of the screw type injection molding machine is 0.1 to 1 mm. Production method. 7. The screw-type injection molding machine according to claim 5, wherein the kneading zone is within a range of 1D to 5D, where D is an inner diameter of a cylinder portion of the screw-type injection molding machine. Item 7. The method for producing a glass fiber-reinforced polypropylene molded article according to Item 6.