JPH10230517A - Manufacture of long fiber reinforced polyolefin resin composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To simplify a manufacturing process, improve the impregnability of a resin in a reinforcing fiber bundle, realize the stable supplying of the resin to an molder and improve its moldability by a method wherein a melted rein, the viscosity of which is lowered by melt-kneading a polyolefin resin and an organic peroxide, is directly fed to a resin impregnating die box. SOLUTION: A reinforced fiber roving 2 is introduced from a robing roll 1 into a resin impregnating die box 3. On the other hand, from a resin feed opening 11 and an organic peroxide feed opening 10, a polyolefin resin and an organic peroxide are supplied so as to melt-knead knead both of them each other in order to successively introduce the resultant resin having the melt flow rate of 100-350g/10min under melted state into the die box 3. Next, the roving 2 is impregnated with the melted resin in the die box 3 and, after that, pulled out with a puller 6 through a cooling device 5. The pulled-out resin strand 4 is cut into pellets with a pelletizer 7 in order to obtain long fiber reinforced resin pellets.

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 a long-fiber-reinforced polyolefin resin composition, and more particularly, to a long-fiber-reinforced polyolefin resin composition having a simple production process and excellent in impregnation of a reinforcing fiber with a resin. The present invention relates to a method for manufacturing a product. The long-fiber-reinforced polyolefin resin composition obtained by the production method of the present invention has excellent moldability when molding the composition, and further, the obtained molded article has excellent strength and appearance.

[0002]

2. Description of the Related Art A long fiber reinforced polyolefin resin composition is prepared by passing a roving (fiber bundle) of continuous glass fiber or the like through a resin impregnation die box such as a crosshead die to impregnate the fiber bundle with a resin. It can be produced by cooling, cutting and pelletizing, and the obtained resin composition is used as a raw material for molding such as injection molding.

However, generally available polyolefin resins have high viscosities, and long glass fiber reinforced polyolefin resin compositions produced using such high-viscosity resins have poor resin impregnation properties. For this reason, when the glass fiber (hereinafter also referred to as GF) drops from the pellet and fuzzes (hereinafter, the dropped GF is referred to as free GF), and the injection molding or the like is performed, the pellet is supplied to the molding machine. However, there was a problem that the composition was not smooth and the moldability was poor.

Furthermore, when injection molding is performed, glass fiber bundles are generated in the molded article, often causing a problem that the appearance of the molded article is significantly impaired. The generation of the glass fiber bundle in the molded body can be suppressed by, for example, increasing the back pressure during injection molding and increasing the kneading properties to disperse the GF. However, in this case, since the reinforcing fibers are broken, the high strength properties originally required of the long fiber reinforced resin composition are impaired.

On the other hand, Japanese Patent Publication No. 63-37694 discloses a method using a low-viscosity polyolefin resin as a raw material to improve the impregnation of the resin into rovings. Such a low-viscosity polyolefin resin can be obtained by decomposing a high-viscosity polyolefin resin with a peroxide or the like, but requires a process for reducing the viscosity,
Significant increases in manufacturing processes and equipment are required.

Further, at the time of molding, it is necessary to re-melt the resin which has once become solid, so that thermal decomposition of the resin occurs, and it is difficult to control the viscosity. Also decreases in strength. It is also conceivable to obtain a low-viscosity polyolefin resin from a resin manufacturer, but it is not practical because it is expensive and has a small supply amount.

A method of improving the impregnation property of a resin by previously adhering a peroxide to a roving is disclosed in Japanese Patent Application Laid-Open No. Hei 8-90660.
However, there is a problem that the moldability in injection molding or compression molding is inferior to the case where the viscosity is reduced as a whole because the decomposition of the resin becomes uneven.

[0008]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems of the prior art, to simplify the manufacturing process, to excel in impregnating the reinforcing fiber bundle with the resin, and to obtain the obtained resin composition. A method for producing a long-fiber-reinforced polyolefin resin composition that can be stably supplied to a molding machine when molding a resin, has excellent moldability, and further has excellent mechanical strength and appearance both in the obtained molded article. To provide.

[0009]

SUMMARY OF THE INVENTION The present invention provides a method for producing a long fiber reinforced polyolefin resin composition in which a roving of reinforced fibers continuously supplied is impregnated with a molten polyolefin resin in a resin impregnation die box. And melt-kneading the polyolefin resin and the organic peroxide using a melt-kneader connected to the die box, and continuously supplying the melt-kneaded material in a molten state into the die box, A method for producing a long-fiber-reinforced polyolefin resin composition, wherein the melt flow rate of the melt-kneaded material supplied into the inside is set to 100 to 350 g / 10 minutes.

In the present invention, the polyolefin resin is preferably polypropylene and maleic anhydride-modified polypropylene. In the present invention, it is preferable that the reinforcing fibers are glass fibers. The melt flow rate of the melt-kneaded product supplied into the resin impregnation die box in the present invention is a solid sample obtained by melt-kneading a polyolefin resin and an organic peroxide at a test temperature of 230 ° C and a test load. It is a value measured according to JIS K7210 under the condition of 2.16 kgf.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in more detail. The present inventors have conducted intensive studies in order to solve the above-described problems of the prior art, and as a result, melt-kneaded a polyolefin resin and an organic peroxide, and then reduced the viscosity of the molten resin, directly into a resin impregnation die box. It has been found that the following excellent effects can be obtained by supplying.

Control of the viscosity of the resin is facilitated, and the effect of improving the impregnation of the roving with the resin is obtained. : The amount of reinforcing fibers falling off from the obtained long-fiber-reinforced polyolefin resin composition (hereinafter also referred to as long-fiber-reinforced resin composition) is small, and the resin composition can be stably supplied to a molding machine, and the moldability is improved. Excellent.

The molded article using the obtained long fiber reinforced resin composition has excellent mechanical strength and appearance. Hereinafter, the raw materials used in the present invention, a method for producing a long fiber reinforced resin composition, and a method for molding the obtained long fiber reinforced resin composition will be described. (Polyolefin resin :) Examples of the polyolefin resin include homopolymers and copolymers of ethylene, propylene, butene, 4-methylpentene and the like, and further, the above monomers and vinyl acetate, acrylic acid, acrylic acid ester, maleic anhydride and the like. Examples include resins modified with polar monomers such as random, alternating, block copolymers or graft copolymers with polar monomers, and two or more of these may be used.

Specifically, preferably, high-pressure polyethylene, ethylene-propylene copolymer, low-pressure polyethylene, ethylene-propylene copolymer, ethylene-1-butene copolymer, ethylene-1-propylene are preferable. Examples thereof include hexene copolymers, medium-pressure polyethylene, high-pressure ethylene-vinyl acetate copolymer, polypropylene, and random or block copolymers of propylene-ethylene. Two or more of these may be used.

Of these, polypropylene is preferred from the viewpoint of the strength of the molded article. Polypropylene, in addition to propylene homopolymer, a copolymer containing ethylene component mainly propylene, such as propylene-ethylene block copolymer, block copolymer of propylene and ethylene-propylene rubber, acrylic acid-modified polypropylene, For example, maleic anhydride-modified polypropylene can be used.

Two or more of these polypropylene resins may be used. When two or more polypropylene resins are used, a mixture of polypropylene and maleic anhydride-modified polypropylene is preferably exemplified. In this case, the amount of the maleic anhydride-modified polypropylene added was 1 to 100 parts by weight of the polypropylene.
Preferably, it is 15 parts by weight.

This is because the addition of 1 part by weight or more of the maleic anhydride-modified polypropylene has the effect of improving the strength of the molded article, and the effect is saturated even if it exceeds 15 parts by weight. Because it is not economical. (Reinforcing Fiber :) Examples of the reinforcing fiber used in the present invention include fibers generally used for reinforcing a synthetic resin such as glass fiber and carbon fiber.

In the present invention, from the viewpoints of performance and economy of a molded article produced from the long fiber reinforced resin composition,
Particularly, glass fibers are preferably used. The type of glass fiber may be any commonly used glass fiber. For example, E-glass which is an alkali-free glass, AR-glass which is a high zirconia-containing alkali-resistant glass,
Examples include T-glass having high strength, high elastic modulus, and high heat resistance, and D-glass, S-glass, C-glass, and R-glass having a low dielectric constant.

The roving of the reinforcing fibers is a long fiber bundle in which thousands of reinforcing fibers are bundled with a sizing agent or the like. The diameter of the reinforcing fiber is suitably 3 to 40 μm. If it is less than 3 μm,
When the reinforcing fiber content in the long fiber reinforced resin composition is the same,
Since the number of reinforcing fibers is relatively increased, it is difficult to impregnate the reinforcing fiber bundle with the resin. Conversely, if it exceeds 40 μm, the surface appearance of the molded product is significantly deteriorated. A more preferred reinforcing fiber diameter is 9 to 25 µm.

(Organic peroxide) Any organic peroxide can be used as long as it can be used for reducing the molecular weight of the polyolefin resin. Specific examples of the organic peroxide include, for example, benzoyl peroxide, acetyl peroxide, di-t-butyl peroxide, t-
Butyl peroxylaurate, dicumyl peroxide, 1,3-bis (t-butylperoxyisopropyl) benzene, 1,4-bis (t-butylperoxyisopropyl) benzene, 2,5-dimethyl-2,5 -Di-t-butylperoxyhexane, 2,5-dimethyl-
2,5-di-t-butylperoxyhexyne-3,2,2
5-di-t-butylperoxyhexane, t-butylperoxybenzoate, n-butyl-4,4-bis-t
-Butylperoxyvalide, octanoyl peroxide, p-menthanehydroperoxide, t-butylmaleic acid, t-butylperoxyacetate and the like.

These organic peroxides can be used alone or in combination of two or more. (Production method): A long fiber reinforced polyolefin resin composition is produced by impregnating a molten polyolefin resin in a resin impregnation die box such as a die or a crosshead die while opening roving of the reinforcing fiber. Can be.

A feature of the present invention is that a polyolefin resin and an organic peroxide are melt-kneaded, and the melt-kneaded product is continuously supplied in a molten state into a resin impregnation die box.
The melt flow rate of the melt-kneaded product supplied into the die box is set to 100 to 350 g / 10 minutes (at 230 ° C., 2.16 kgf). According to the production method of the present invention, the molten resin whose viscosity has been reduced by the organic peroxide can be directly supplied to the impregnation die. Since it is not necessary to melt the resin once solidified, the viscosity of the resin can be easily controlled, and the effect of improving the impregnation of the roving with the resin can be obtained.

Further, the amount of the reinforcing fibers falling off from the obtained long fiber reinforced resin composition is small, the resin composition can be stably supplied to a molding machine, the moldability is excellent, and the obtained molded article is further improved. And the appearance of the molded article is excellent.
In the present invention, a polyolefin resin and an organic peroxide are supplied to a melt kneader connected to a resin impregnation die box such as a die or a crosshead die.

As a result, the polyolefin resin is decomposed by the action of the organic peroxide during melt-kneading, the melt viscosity is reduced, the fluidity of the resin is improved, and the impregnation of the reinforcing fiber into the roving with the resin is improved. . The melt kneader may be any as long as it can melt the resin, and the type thereof is not limited, but an extruder or the like is suitable.

The method for supplying the polyolefin resin and the organic peroxide to the melt kneader is as follows: (1) In order to keep the ratio of the organic peroxide to the polyolefin resin constant,
Examples of a method in which a polyolefin resin and an organic peroxide are premixed and supplied to a melt kneader, and a method in which (2) the polyolefin resin and the organic peroxide are supplied from the inlet of the melt kneader without being premixed. But is not particularly limited.

As the supply method in the above method (2), the supply may be performed from one input port or from separate input ports. Also, the form of the organic peroxide may be a master batch diluted to a few percent,
Preferred for safety. Examples of the resin impregnation die box include a die and a crosshead die, but the type is not limited as long as it is a structure that can impregnate the molten resin while opening the roving of the reinforcing fiber.

The fiber-reinforced polyolefin resin composition (also referred to as resin strand) drawn from the resin impregnation die box is cut into a desired length after cooling. The pellets obtained by cutting have a length of preferably 2 to 50 mm and the reinforcing fibers are arranged in parallel with the pellets at substantially the same length. When the length of the pellet is less than 2 mm, the strength of the molded body is low because the length of the remaining fiber in the molded body (hereinafter referred to as molded body) obtained in the molding step in the subsequent step becomes too short.

Conversely, when the length of the pellet exceeds 50 mm,
Stable supply to the molding machine becomes difficult. The length of the pellet is
6 to 15 from the viewpoint of ensuring the strength of the compact and stable supply to the molding machine
mm is more preferred. The amount of the organic peroxide to be added is not particularly limited, but the melt flow rate of the polyolefin resin at the time when it is supplied into the resin impregnation die box is 100 to 100%.
It is necessary to adjust the addition amount so that 350 g / 10 min (at 230 ° C, 2.16 kgf).

The melt flow rate of the polyolefin resin at the time it is fed into the resin impregnation die box is more preferably 140 to 300 g / 10 min (at 230 ° C., 2.16 kgf
). If the melt flow rate is lower than 100 g / 10 minutes, the impregnating property of the resin into the roving becomes insufficient, and the appearance of the molded article is impaired or the moldability tends to be insufficient.

Conversely, if the melt flow rate is higher than 350 g / 10 minutes, the appearance and moldability of the molded article will be good, but the mechanical strength of the molded article will be reduced. The content of the reinforcing fibers in the long fiber reinforced polyolefin resin composition is preferably in the range of 10 to 80% by weight. If it is less than 10% by weight, the strength of the molded body is not sufficient, and if it is more than 80% by weight, the reinforcing fiber bundle such as a glass fiber bundle is insufficiently impregnated with the polyolefin resin, and the reinforcing fiber may fall off. In addition, the appearance of the molded article becomes poor.

In the present invention, an antioxidant, a heat stabilizer, an ultraviolet absorber, a light stabilizer, a lubricant, a flame retardant, a mold release agent, an inorganic or organic filler, as long as the object of the present invention is not impaired. Various additives such as an antistatic agent and a colorant can be added. (Molding method :) The long fiber-reinforced polyolefin resin composition produced by the production method of the present invention can be molded by a method such as injection molding, blow molding, or extrusion molding.

For large members, injection compression molding and low pressure injection molding are suitable.

[0033]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be specifically described below based on embodiments. The present invention is not limited to the specific contents such as the manufacturing apparatus and the manufacturing conditions of the following examples. Example 1 A long fiber reinforced polyolefin resin composition was produced using the apparatus shown in FIG.

In FIG. 1, a roving 2 of reinforcing fibers is introduced from a roving roll 1 into a resin impregnation die box 3. On the other hand, the resin supply port 11 and the organic peroxide supply port
A polyolefin resin and an organic peroxide are supplied from 10, and both are melt-kneaded in an extruder 9, and a resin having a predetermined melt flow rate is continuously introduced into the resin impregnation die box 3 in a molten state.

The reinforcing fiber rovings 2 are impregnated with the molten resin in the resin impregnation die box 3 and then cooled by the cooling device 5.
And is pulled out by the pulling-out machine 6 via. The drawn resin strand 4 is cut and pelletized by a pelletizer 7 to produce a long fiber reinforced resin pellet 8 which is a long fiber reinforced polyolefin resin composition.

In the present embodiment, a glass fiber roving in which 9200 monofilaments having a fiber diameter of 16 μm are converged was used as the reinforcing fiber roving 2. As the polyolefin resin, a polypropylene homopolymer (hereinafter referred to as PP) having a melt flow rate of 8 g / 10 min and a maleic anhydride-modified polypropylene were used.

The maleic anhydride-modified polypropylene is represented by P
10 parts by weight with respect to 100 parts by weight of P100 were mixed in advance and used. Further, 0.1 part by weight of 1,4-bis (t-butylperoxyisopropyl) benzene as an organic peroxide was added to 100 parts by weight of a mixture of polypropylene (PP) and maleic anhydride-modified polypropylene.

The barrel temperature of the extruder was set at 200 ° C., and a long fiber reinforced resin pellet having a length of 9 mm was obtained. Next, using the obtained pellets, a molded body was manufactured using an injection molding machine having a mold clamping force of 50 t. The cylinder temperature was set at 240 ° C and the mold temperature at 70 ° C.

The melt flow rate of the melt-kneaded product (composition of PP, maleic anhydride-modified polypropylene and organic peroxide) supplied into the resin impregnation die box, and the obtained long-fiber reinforced resin pellets and molded products Was evaluated by the evaluation method described below. (Examples 2 to 7) Except that the melt flow rate of polypropylene, the amount of organic peroxide added, and the type of organic peroxide were changed, a long fiber reinforced resin pellet and a molded article were produced in the same manner as in Example 1. Manufactured and evaluated.

Comparative Example 1 A long fiber reinforced resin pellet and a molded article were produced and evaluated in the same manner as in Example 1 except that no organic peroxide was added. (Comparative Example 2) In Example 1, the organic peroxide was used.
Except for adding 0.15 wt%, a long fiber reinforced resin pellet and a molded article were produced and evaluated in the same manner as in Example 1.

Comparative Example 3 A long fiber reinforced resin pellet and a molded product were produced and evaluated in the same manner as in Example 4 except that the organic peroxide was not added in Example 4 described above. Comparative Example 4 Polypropylene homopolymer (PP) having a melt flow rate of 8 g / 10 min, maleic anhydride-modified polypropylene and 1,4-bis (t
-Butyl peroxyisopropyl) benzene,
The mixture was melt-kneaded in an extruder to obtain a polypropylene resin pellet having a length of 3 mm.

The maleic anhydride-modified polypropylene is represented by P
10 parts by weight based on 100 parts by weight of P and 0.11 part by weight of 1,4-bis (t-butylperoxyisopropyl) benzene is added to 100 parts by weight of a mixture of polypropylene (PP) and maleic anhydride-modified polypropylene. did. The barrel temperature of the extruder was set at 200 ° C.

The melt flow rate of the obtained polypropylene resin pellets was 300 g / 10 minutes. Next, using the obtained polypropylene resin pellets and the same apparatus as shown in FIG. 1 as in Example 1, under the condition where no organic peroxide was added, a long fiber reinforced polyolefin resin composition (: long fiber reinforced resin pellets) Was manufactured, and a molded body was manufactured in the same manner as in Example 1.

Further, the melt flow rate of the melt-kneaded product (polypropylene resin pellets) supplied into the resin impregnation die box and the obtained long fiber reinforced resin pellets,
The molded body was evaluated by the method described below. Example 1 above
7, Table 1 shows the experimental results of Comparative Examples 1 to 4. As is clear from the results shown in Table 1, the long fiber reinforced polyolefin resin composition obtained by the production method of the present invention is:
The amount of the reinforcing fibers falling off from the resin composition was small, stable supply to the molding machine was possible, and not only excellent moldability, but also excellent mechanical strength and appearance of the obtained molded article. (Examples 1 to 7).

On the other hand, in Comparative Example 1 where the melt flow rate of the melt-kneaded product supplied into the resin impregnation die box was out of the lower limit of the range of the present invention, the amount of the reinforcing fibers dropped from the resin composition was low. In many cases, the moldability was inferior and the appearance of the molded body was also poor. In Comparative Example 3, the appearance of the molded body was poor. In Comparative Example 2 in which the melt flow rate of the melt-kneaded product supplied into the resin impregnation die box was out of the upper limit of the range of the present invention, the mechanical strength of the molded product was inferior.

In Comparative Example 4 using resin pellets produced by adding an organic peroxide to the resin in advance, the mechanical strength of the molded product was inferior. The rise in the melt flow rate of the resin shown in Comparative Examples 1, 3, and 4 in Table 1 is presumed to be due to the thermal decomposition of the resin during melt-kneading. [Evaluation method] (1) Measurement of melt flow rate: [PP:] Based on JIS K7210 (230 ° C, 2.16 kgf).

[Melt flow rate of melt-kneaded product supplied into resin impregnation die box:] Any one of the following samples is melt-kneaded under the conditions of an extruder barrel temperature of 200 ° C.
The melt flow rate of the pulverized product of the solid sample obtained by cooling (the sample extracted from the exit side of the extruder 9 in FIG. 1) was measured under the conditions of a test temperature of 230 ° C. and a test load of 2.16 kgf according to JIS K7210.
It measured according to.

Samples (Examples 1 to 7, Comparative Example 2); Polyolefin resin (mixture of PP and maleic anhydride-modified polypropylene) + organic peroxide Sample (Comparative Example 1, Comparative Example 3); Polyolefin resin (PP and Mixture of maleic anhydride-modified polypropylene) Sample (Comparative Example 4); Polypropylene resin pellet (2) Measurement of pellet impregnating property (void ratio): The pellet was embedded in epoxy resin and polished, and the pellet cross section (end face)
Was observed, and the ratio (%) between the area of the embedded resin existing inside the pellet and the cross-sectional area of the pellet was determined.

The lower the void ratio, the higher the resin impregnation. (3) Measurement of the amount of free GF: The pellet was mechanically shaken in a 1 mm mesh test sieve, and GF dropped from the pellet.
Was sieved and the amount was determined from the weight reduction ratio of the pellet. If the resin impregnation is good, the amount of free GF is small.

(4) Evaluation of moldability: Evaluation was made according to the following evaluation criteria. ；: A normal molded product can be obtained without any problem. ×: Short shot (: insufficient injection ^* ) is likely to appear. [*: State in which the resin is not completely filled up to the end of the molded product. (5) Evaluation of appearance of molded article: ；: good occurrence with few glass fiber bundles △; slightly high generation of glass fiber bundles ×: many generations of glass fiber bundles, ugly (6) Strength measurement: The tensile strength was measured according to ASTM D 638, and the Izod impact strength was measured according to ASTM D 256.

[0051]

[Table 1]

[0052]

According to the present invention, the molten resin whose viscosity has been reduced by the organic peroxide can be directly supplied to the impregnation die.
Since it is not necessary to melt the resin once solidified again, the viscosity can be easily controlled, and the effect of improving the impregnation of the roving with the resin can be obtained.

The long-fiber-reinforced polyolefin resin composition produced by the production method of the present invention can be supplied stably to a molding machine because of a small amount of reinforcing fibers falling off during handling. Excellent. Furthermore, by using the long fiber reinforced polyolefin resin composition produced by the production method of the present invention, it is possible to suppress the occurrence of fiber bundles in the molded product, and to provide a molded product excellent in both appearance and mechanical strength. Obtainable.

[Brief description of the drawings]

FIG. 1 is a schematic view showing an apparatus for producing a long fiber reinforced polyolefin resin composition.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Roving winding body 2 Roving of reinforcing fiber 3 Die box for resin impregnation 4 Resin strand 5 Cooling device 6 Pick-up machine 7 Pelletizer 8 Long fiber reinforced resin pellet 9 Extruder 10 Organic peroxide supply port 11 Resin supply port

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI B29K 105: 08 309: 08 C08K 5:14 (72) Inventor Hideto Iwasaki 1 Kawasaki-cho, Chuo-ku, Chiba-shi, Chiba Pref. Inside Chiba Works (72) Inventor Masashi Nakamura 1 Kawasaki-cho, Chuo-ku, Chiba-shi, Chiba Kawasaki Works Chiba Works

Claims (3)

[Claims] 1. A method for producing a long-fiber reinforced polyolefin resin composition in which a roving of continuously supplied reinforcing fibers is impregnated with a molten polyolefin resin in a resin impregnation die box. The melt-kneaded product is melt-kneaded with a polyolefin resin and an organic peroxide using a connected melt-kneader, and the melt-kneaded material is supplied into the die box while the melt-kneaded material is continuously supplied in a molten state. The melt flow rate
A method for producing a long-fiber-reinforced polyolefin resin composition, wherein the composition is 100 to 350 g / 10 min. 2. The method for producing a long fiber reinforced polyolefin resin composition according to claim 1, wherein the polyolefin resin is polypropylene and maleic anhydride-modified polypropylene. 3. The method for producing a long fiber reinforced polyolefin resin composition according to claim 1, wherein the reinforcing fibers are glass fibers.