JPH11300777A - Production of injection-molded molding of glass fiber reinforced polypropylene resin - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the dispersion of glass fibers into a resin and mechanical strength by injection molding the pellets of a specified polypropylene resin and specified glass fibers directly without the melt-kneading process of them. SOLUTION: An injection-molded molding of a glass fiber reinforced polypropylene resin is injection-molded after 100 pts.wt. of polypropylene resin pellets of 30-300 g/10 min MFR and 5-100 pts.wt. of glass fibers being mixed with the pellets unmelted. By the direct injection molding of the pellets of high fluidity and the glass fibers with the pellets unmelted, the poor dispersion of the glass fibers due to the defective defibration of the fibers which has been a defect when conventional resin pellets are used can be eliminated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing an injection-molded glass fiber reinforced polypropylene resin molded article which has good dispersion of glass fibers in a resin and has excellent mechanical strength. is there.

[0002]

2. Description of the Related Art Polypropylene resins are widely used in various fields because they are light, have excellent mechanical strength and appearance, are easy to mold, and are easily available. Particularly in the field of automobiles, building components, and mechanical parts, plastic parts are being promoted for reasons such as weight reduction, cost reduction, and aesthetics. Parts that require particularly high strength are reinforced with glass fibers. The used resin is generally used. As a method of manufacturing an injection molded article in which a polypropylene resin is reinforced with glass fibers, generally, a glass fiber is blended with a resin pellet or powder, and the mixture is kneaded with a glass kneader having a particle size of 2 to 5 mm using a melt kneader. Into pellets,
Next, a method of injection molding the kneaded pellets is employed. However, in such a method, the glass fiber is cut by shear stress to the resin or the glass fiber in the kneading step for pelletizing, and the length of the glass fiber in the kneaded pellet is significantly shorter than the length at the time of compounding. Has become. Furthermore, since the plasticizer is subjected to the second shearing in the plasticizing process during injection molding, the length of the glass fiber present in the injection molded body is further shortened, and the injection molding satisfying mechanical strength, particularly rigidity and impact strength. There is a disadvantage that the body cannot be obtained.

[0003] As a method of remedying such a drawback, glass fiber is mixed with polypropylene resin pellets or powder in an unmelted state of resin and directly injection-molded without a melt-kneading step to obtain glass fiber by shear stress. Although a method of reducing the cutting of the fibers has been studied, a so-called defibration failure occurs in which a bundle of glass fibers is generated in the molded body. Further, as a method of mixing a resin powder and glass fiber, JP-A-58-155925, JP-A-58-183230,
JP-A-58-215425, JP-A-1-218825
According to each of the publications described above, after a polypropylene resin powder (powder) having a specific shape and glass fiber are mixed in an unmelted state of the powder, a production method in which injection molding is directly performed without a melt-kneading step, dispersibility, It is disclosed that an injection molded article having excellent mechanical strength can be obtained.

[0004] However, such powders have poor handling properties due to their properties, and the shipping form is limited to paper bags, so that the workability is poor, and when scattered, the environment deteriorates and the particle size is 200 μm or less. If it is present at a certain concentration, it tends to cause dust explosion and cannot be stored for a long time.
Furthermore, at the time of injection molding, a necessary heat stabilizer is mixed together with the glass fiber, and if the respective components are sufficiently mixed, the stirring time becomes longer, and the physical properties are reduced due to the cutting of the glass fiber. Further, the glass fibers are swollen in a cotton-like manner and cause poor penetration into the hopper, and air is easily entrained during plasticization in powder injection molding, so that a vented molding machine must be used. Furthermore, in direct molding using propylene / ethylene copolymer polypropylene powder, the dispersion of the rubber component present in the polypropylene is not sufficient, resulting in deterioration of physical properties and generation of the rubber component as a bright spot on the product surface. However, problems such as poor appearance occur, and the use of powder has been decreasing in recent years.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in order to solve these drawbacks.
Provided is a method for directly injection-molding polypropylene resin pellets and glass fibers without a melt-kneading step to obtain an injection-molded article having good dispersion of glass fibers in the resin and excellent mechanical strength. The task is to

[0006]

Means for Solving the Problems The present inventor has made various studies in view of the above-mentioned problems, and as a result, using a polypropylene resin pellet having high fluidity, mixing with glass fiber to directly perform injection molding. At this time, they found that an injection-molded article having no fiberization failure, good dispersibility, and excellent mechanical strength was obtained, and completed the present invention. That is, the method for producing a glass fiber-reinforced polypropylene resin injection molded article of the present invention comprises mixing the following components (a) and (b) in a state where the polypropylene resin pellets of the component (a) are not melted, It is characterized by injection molding. Component (a): 100 parts by weight of polypropylene resin in pellet form with MFR of 30 to 300 g / 10 minutes Component (b): 5 to 100 parts by weight of glass fiber

[0007]

DETAILED DESCRIPTION OF THE INVENTION [I] Production of glass fiber reinforced polypropylene resin injection molded article (1) Raw material (a) Polypropylene resin [Component (a)] Pellet polypropylene of component (a) used in the present invention As the resin, a pellet of a highly fluid resin, specifically, a melt flow rate (MFR) measuring device according to JIS-K7210, at a temperature of 230 ° C.
The value measured under the condition of a load of 2.16 kg is 30 to 300.
g / 10 minutes, preferably 50 to 300 g / 10 minutes, particularly preferably 60 to 200 g / 10 minutes, as long as it is a pellet of polypropylene resin. The above MF
If R is less than the above range, the dispersibility of the glass fiber becomes poor, and poor fibrillation occurs in the molded product. On the other hand, if the resin exceeds the above range, the plasticization time during molding becomes longer, and the productivity decreases.

The pellet-shaped polypropylene resin is preferably an additive-containing pellet obtained by melt-kneading with an additive such as a heat stabilizer. The pellets have an average weight per particle of 5 to 50 mg, particularly 10 to 40 mg.
Preferably, The shape of the pellet is not particularly limited, and examples thereof include a round pellet obtained by a hot cut method, a square pellet obtained by a strand cut method, and the like. As for the size of the round pellets, those having a diameter of 1 to 7 mmφ and a length of 1 to 5 mm can be used as an average value of all the sizes.
It is preferable to use one having a diameter of mmφ and a length of 1 to 3 mm. The size of the square pellet is 0.5 to 5 mm in length, 0.5 to 5 mm in width, and 1 to 1 in length as an average of all sizes.
Although the thing of 0 mm can be used, it is preferable to use the thing of 1-3 mm in length, 2-4 mm in width, and 1-5 mm in length.

[0009] The polypropylene resin, depending on the polymerization form,
Although classified into propylene homopolymer, propylene / ethylene block copolymer, propylene / ethylene random copolymer, etc., the effects of the present invention can be sufficiently exerted no matter what is used.

(B) Glass fiber [Component (b)] The glass fiber of the component (b) used in the present invention is:
Generally, commercially available ones can be used as appropriate, but usually those having a length of 3 to 20 mm are used, and among them, it is preferable to use glass fibers having a length of 3 to 13 mm. If the glass fiber length is less than the above range, the dispersibility is good, but one exhibiting excellent mechanical strength cannot be obtained. On the other hand, if the ratio exceeds the above range, the dispersibility becomes poor, and poor fibrillation occurs in the molded product. Further, the diameter of the filament constituting the glass fiber is generally 5 to 20 μm, and this filament is contained in one fiber bundle.
Those containing up to 4,000 can be used.

(C) Unsaturated carboxylic acid and / or derivative thereof [Component (c)] In the present invention, as the unsaturated carboxylic acid and / or derivative thereof of component (c) used as necessary, polypropylene resin may be used. It is blended for the purpose of interfacial adhesion between the glass fiber and the glass fiber, and is mainly blended for the purpose of improving the mechanical strength, and hardly contributes to the dispersibility of the glass fiber in the present invention. In order to further improve the content, it is necessary to add it. Examples of unsaturated carboxylic acids and / or derivatives thereof include maleic acid, maleic anhydride, acrylic acid, methacrylic acid, itaconic acid, itaconic anhydride, crotonic acid, citraconic acid, angelic acid, sorbic acid, and the like. Metal salts of saturated carboxylic acids, amides, imides, esters and the like can be mentioned. These are preferably used alone or a polyolefin resin modified by a derivative thereof is used. In particular, those modified using a polypropylene resin as a base are preferable, and those having a modification ratio of 0.1 to 10% by weight are preferably used. . The form is preferably in the form of pellets from the viewpoint of dispersibility of the component (a) and the component (b).

(D) Other components In the present invention, additives may be blended as other components in order to improve the moldability and environmental adaptability of the injection molded article. Is a heat stabilizer,
Antioxidants, antistatic agents, light stabilizers, ultraviolet absorbers, neutralizing agents, metal corrosion inhibitors, lubricants, flame retardants, nucleating agents, dispersants,
Processing stabilizers and the like can be mentioned. It is preferable that these additives are previously blended with the polypropylene resin pellets as the component (a) by melt kneading or the like.

(2) Mixing ratio The mixing ratio of the raw material is as follows: 100 parts by weight of pelletized polypropylene resin having high fluidity of component (a) and 5 to 100 parts by weight of glass fiber of component (b). And preferably 10 to 70 parts by weight. The polyolefin-based resin modified with the unsaturated carboxylic acid or its derivative of the component (c), which is blended as required, is generally 0.01 to 5 parts by weight, preferably 0.05 to 3 parts by weight. is there.

(3) Mixing The component (a) is a highly flowable pellet-shaped polypropylene resin, the component (b) is glass fiber, and the component (c) is an unsaturated carboxylic acid or After blending the derivative in the above blending ratio, the high flowability pelletized polypropylene resin of the component (a) is mixed in an unmelted state. The mixing is generally performed by using an existing mixing apparatus such as a V blender or a tumbler. The mixing order of each component is as follows: component (a) and component (c) are mixed in advance, and then component (b) is mixed. Are preferably mixed, but the order is not limited to these.

(4) Injection molding After the above mixing is performed, the mixture is put into a hopper of an injection molding machine and directly molded, but is not particularly limited as long as it is an in-line screw type injection molding machine. Preferably, a device equipped with a nasal dripping prevention mechanism such as a shut-off nozzle is used. The injection molding conditions are not particularly limited, but it is preferable to set the molding temperature to a higher temperature in order to improve the intervention of the resin into the glass fibers. Also,
In order to obtain a uniform dispersibility of the glass fiber, it is necessary to increase the screw back pressure and lengthen the plasticization time.However, the glass fiber is cut due to an increase in the shear stress, and the mechanical strength decreases. It is preferable to perform back pressure setting that balances the properties and mechanical strength.

[II] Glass Fiber Reinforced Polypropylene Injection Molded Body The mechanical strength of the glass fiber reinforced polypropylene resin injection molded article by the above injection molding is improved by directly injection molding polypropylene resin pellets and glass fibers. Cutting of glass fibers by melt-kneading can be avoided, and the use of a highly fluid material for the polypropylene resin makes it easier for the polypropylene resin to intervene between each glass fiber. This is because the dispersibility of the fibers is remarkably improved, and an injection molded article in which glass fibers having a long fiber length are uniformly dispersed can be obtained.

[III] Applications The glass fiber reinforced polypropylene resin injection molded article of the present invention is lightweight, has excellent mechanical strength and appearance, and is easy to mold, so that it can be molded into various molded articles. It can be widely used in various fields, but is particularly useful in the field of automobiles, building materials, and mechanical parts.

[0018]

The present invention will be described more specifically with reference to the following examples and comparative examples. [I] Evaluation method (1) Dispersion state of glass fiber The degree of defibration of the glass fiber was visually determined using a test piece for appearance evaluation having a thickness of 80 mm × 120 mm × 2 mm. As a criterion, the following four ranks were evaluated by counting those in which the condensed glass fibers remained clearly white without being loosened. ：: Good dispersion (no defibration failure at all) △: Poor treetop (1 or 2 defibration failures) ×: Defective (several defibration failures) XX: Remarkable failure (defective defibration failures over the entire surface) Yes)

(2) JIS Mechanical Properties Mechanical properties were measured at 23 ° C. and 50% RH. Tensile strength: JIS-K7113 compliant (JIS No. 1 test piece, test speed 5 mm / min) Three-point bending elastic modulus: JIS-K7203 maximum bending stress: JIS-K7203 compliant Izod impact strength: JIS-K7110 compliant (with mold notch) Deflection temperature under load: JIS-K7207 compliant (σ: 1.81 MPa) Flat dart impact strength: Polychem Corporation method (Shock absorption generated when a Dart having a flat-shaped impact surface falls and strikes a flat test piece Test method to measure energy and evaluate impact strength of test material Flat Dart diameter: 20mmφ Support diameter: 40mmφ Dart load: 4kg Drop height: 2m Specimen thickness: 2mm) Evaluation was made based on the following four ranks. ◎: Satisfactory satisfied ○: Satisfied △: Slightly dissatisfied ×: Dissatisfied

[II] Examples and Comparative Examples Examples 1 and 2 As polypropylene resin pellets, BC06C manufactured by Nippon Polychem Co., Ltd. (MFR: 60 g / 10 min, round pellet shape, average weight 30 mg / particle, oxidized as an additive) 0.1 part by weight of an inhibitor mixed and melt-kneaded) (Example 1) and TX1498T (MF
R: 140 g / 10 min, square pellet shape, average weight 1
8 mg / particle, 0.1 part by weight of an antioxidant as an additive, melt-kneaded) (Example 2), 100 parts by weight of each of two kinds of resin, glass fiber (13 m long)
m, diameter 13 μm, number of bundles 1,000, 66.7 parts by weight of Asahi Fiberglass 13MA411J), and maleic anhydride-modified polypropylene resin (maleic anhydride content 1.2% by weight, square pellets) shape)
Was blended by 2 parts by weight and mixed in a V blender for 5 minutes. This mixture was injected into an in-line screw injection molding machine (J15) with a shut-off nozzle mechanism manufactured by Japan Steel Works, Ltd.
0SSIIVA), molding temperature 260 ° C, mold temperature 4
0 ° C., injection pressure 600 kg / cm ² , injection time 15 seconds,
A test piece for measuring mechanical properties according to JIS was molded under the conditions of a cooling time of 30 seconds and a screw rotation speed of 70 rpm, and the screw back pressure was set to a state where disintegration failure did not occur on the test piece (dispersibility ○). . In this molding, when plasticizing before injection, the time required for the screw to retract from the position before plasticization corresponding to the amount of injected resin to this limit switch with plasticization is measured, and this is plasticized. It was evaluated as time. Those having a short plasticizing time and no defibration failure can be judged to have excellent dispersibility. Table 1 shows the plasticization time, dispersibility, and JIS mechanical properties.

Comparative Examples 1 and 2 BC6WHA manufactured by Nippon Polychem Co., Ltd. (MFR: 4 g / 10 min, round pellet shape, average weight 25 mg / particle), and 0.2 parts by weight of an antioxidant as an additive were used as polypropylene resin pellets. After the material was prepared in the same manner as in Example 1 using the compound melt-kneaded mixture), injection molding was performed. However, by changing the screw back pressure, a defective defibration product (dispersibility xx) (Comparative Example 1) and a fine defibrated product (dispersibility）) (Comparative Example 2) were formed, and the respective JIS mechanical properties were evaluated. did. Table 1 shows the results.

Comparative Example 3 As a polypropylene resin powder, BC03CQ (MFR: 30 g / 10 min, powder, average weight 1 mg / one grain) manufactured by Nippon Polychem Co., Ltd. and an antioxidant 0.1 as an additive
The procedure was performed in the same manner as in Example 1 except that the resin in parts by weight was used. Table 1 shows the results.

Example 3 Instead of the glass fiber of the method of Example 1, glass fiber (length 3 mm, diameter 13 μm, number of bundles 1,000, 03MA411J manufactured by Asahi Fiberglass Co., Ltd.) was used.
The method was performed in the same manner as in Example 1. Table 2 shows the results.

Example 4 The procedure of Example 3 was repeated, except that the maleic anhydride-modified polypropylene resin was not used. Table 2 shows the results.

Comparative Example 4 In Example 3, the polypropylene resin pellets were obtained by using BC6WHA (MFR: 4 g / 10 min, manufactured by Nippon Polychem Co., Ltd.
Example 3 was carried out in the same manner as in Example 3 except that a round pellet shape, an average weight of 25 mg / particle, and an additive prepared by mixing and melting and kneading 0.2 part by weight of an antioxidant) were used.
Table 2 shows the results.

Comparative Example 5 In Example 3, as a polypropylene resin powder, BC03CQ manufactured by Nippon Polychem Co., Ltd. (MFR: 30 g /
The procedure was carried out in the same manner as in Example 3, except that 10 minutes, powder, average weight 1 mg / particle) and 0.1 parts by weight of an antioxidant as an additive were used. Table 2 shows the results.

Comparative Example 6 In Example 3, the polypropylene resin pellets, glass fiber and maleic anhydride-modified polypropylene resin were kneaded into pellets using a melt kneader, and injection molding was performed. Table 2 shows the results.

[0028]

[Table 1]

[0029]

[Table 2]

As is clear from Table 1, Examples 1, 2 and 3 of the present invention have the same dispersibility as Comparative Examples 3 and 5 using polypropylene powder. Since the plasticization time is shortened, productivity can be improved. In addition, it has excellent performance in mechanical properties, and when using polypropylene resin powder,
From the high physical property level, it can be confirmed that the dispersion state of the glass fibers in the molded article is uniform and exists with a long fiber length. In Comparative Examples 1 and 4, the fluidity of the resin pellets was insufficient and the dispersibility was inferior. In Comparative Example 2, the dispersibility was improved by increasing the plasticization time. It can be confirmed that the mechanical properties are not sufficient. In Example 4, it can be confirmed that the content of the unsaturated carboxylic acid does not contribute to the dispersibility of the glass fiber.

[0031]

According to the present invention, polypropylene resin pellets having high fluidity and glass fibers are mixed in an unmelted state of the pellets and directly injection-molded to use conventional resin pellets. The poor dispersibility due to poor fiberization of glass fiber, which was a disadvantage when
Good dispersion of glass fiber in resin, and mechanical strength, especially rigidity such as bending strength and flexural modulus, tensile strength, Izod impact strength, impact resistance such as surface impact by punch,
With respect to heat resistance such as load deflection temperature, it is possible to obtain better physical properties than when resin powder is used.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI B29K 23:00 105: 12

Claims (5)

[Claims] 1. A glass fiber reinforced polypropylene, which is obtained by mixing the following components (a) and (b) in a state in which the polypropylene resin pellets of the component (a) are not melted, followed by injection molding. A method for producing a resin injection molded article. Component (a): 100 parts by weight of polypropylene resin in pellet form with MFR of 30 to 300 g / 10 minutes Component (b): 5 to 100 parts by weight of glass fiber 2. The glass fiber-reinforced polypropylene resin injection molded article according to claim 1, wherein the pellet-shaped polypropylene resin of the component (a) is an additive-containing pellet obtained by melt-kneading with an additive. Method. 3. The method for producing a glass fiber reinforced polypropylene resin injection molded article according to claim 1, wherein the pelletized polypropylene resin of the component (a) is a pellet having an average weight per particle of 5 to 50 mg. 4. The glass fiber of component (b) has a length of 3 to 20.
The method for producing a glass fiber reinforced polypropylene resin injection molded article according to claim 1, which is in mm. 5. The glass fiber reinforced polypropylene resin according to claim 1, comprising 0.01 to 5 parts by weight of a polyolefin resin modified by an unsaturated carboxylic acid and / or a derivative thereof as the component (c). A method for producing an injection molded article.