JPH03121146A - Long fiber-reinforced polyolefin resin composition for molding and preparation thereof - Google Patents

Abstract

PURPOSE:To prepare the title compsn. excellent in the mechanical properties, such as tensile and bending strengths, by compounding a fibrous reinforcement into a resin component comprising a polyolefin and a modified olefin polymer in a specified ratio and thereby specifically orientating the reinforcement in the resin component. CONSTITUTION:The title compsn. is prepd. by compounding 5-80wt.% (based on the compsn.) fibrous reinforcement (e.g. glass fiber) substantially of the length of 2mm or longer into a resin component comprising 98-50 pts.wt. polyolefin (e.g. polypropylene) and 2-50 pts.wt. olefin polymer (e.g. polypropylene) modified with an unsatd. carboxylic acid (deriv.) (e.g. maleic anhydride) in such a manner that the reinforcement is orientated almost in parallel in the resin component.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a polyolefin resin composition for molding which is reinforced with long fibers and has significantly improved mechanical strength, etc., and a method for producing the same.

[Conventional technology and its issues]

As a means to improve the strength of polyolefins,
It is known to blend reinforcing fibers such as glass fibers, and generally, fiber-reinforced polyolefin resin compositions can be produced by mixing polyolefin and short fibers such as chopped strands and extruding the mixture using an extruder. It is being done. This method has the advantage that a fiber-reinforced polyolefin resin composition having a fairly high mechanical strength can be obtained very easily.

However, in recent years, there has been a tendency to require even higher mechanical strength for resins, and the above-mentioned manufacturing method for fiber-reinforced resin compositions, in which fiber breakage is unavoidable during kneading in an extruder, has not met this requirement. cannot respond to

On the other hand, pultrusion molding is attracting attention as a method for improving the above-mentioned drawbacks and producing a thermoplastic resin composition reinforced with long fibers without causing fiber breakage.
There are also examples of its use in reinforcing polyolefins. This method basically involves impregnating a thermoplastic resin while drawing continuous reinforcing fibers. For example, US Pat. No. 287755
No. 01, British Patent Application Publication No. 1167849 discloses that after a continuous #a fiber is passed through a bath of a thermoplastic resin emulsion or solution, the solvent is removed by heating and the resin is melted to form fibers. British Patent Application Publication No. 1,302,048 describes a method in which continuous fibers are impregnated with molten resin while being drawn through a crosshead die, and U.S. Pat. U.S. Pat. No. 3,022,210 discloses a method of impregnating with a melt of a polymer with a small molecular weight, here polystyrene, and JP-A-57-181,852 discloses a method of impregnating with a melt of a polymer having a small molecular weight, and a method of impregnating with a melt of polystyrene while drawing a continuous fiber. A method of impregnating a low viscosity thermoplastic resin is described. However, since the polyolefin targeted in the present invention has no polarity and poor activity, even if an attempt is made to simply use the pultrusion method described above to strengthen the 1ta fiber, the impregnation and adhesion of the resin to the fiber are insufficient. Therefore, it is not possible to improve the strength etc. as much as expected. It also has the disadvantage that the fibers from the resulting composition tend to loosen and fly apart. Fiber reinforcement by pultrusion molding using polyolefin as a base resin has such problems, and an improvement has been desired.

[Means to solve the problem]

The present inventor has solved the above problems with a long fiber-reinforced polyolefin resin composition and a method for producing the same. As a result of intensive studies to obtain a reinforced polyolefin resin composition, it was discovered that these problems could be solved by using a specifically modified olefin polymer together with polyolefin, and the present invention was achieved.

That is, the present invention provides a resin component consisting of 98 to 50 parts by weight of a polyolefin (A) and 2 to 50 parts by weight of a modified olefin polymer (B) modified with an unsaturated carboxylic acid or a derivative thereof; ~80% by weight reinforcing fiber (C)
A long fiber-reinforced polyolefin resin for molding, characterized in that substantially all of the fibers have a length of at least 2 mm or more and are arranged substantially parallel to each other in the resin. Compositions and methods of making such compositions.

First, the polyolefin (A>
is selected from olefin homopolymers and copolymers of two or more olefins; specific examples include polyethylene, polypropylene, polymethylpentene, ethylene-propylene random copolymer, ethylene- Examples include propylene block copolymers, ethylene-α-olefin copolymers, propylene-α-olefin copolymers, and the like. In the present invention, it is also possible to use a mixture of two or more of these polyolefins.

Among these polyolefins, in the present invention, polyolefins mainly composed of polyethylene or polypropylene are preferred, and polyolefins mainly composed of polypropylene are particularly preferred, considering the extrusion processability and moldability of the resin, the properties of the obtained composition, etc. That is.

Next, the modified olefin polymer (B) used in the present invention is an olefin homopolymer or a copolymer of two or more olefins, such as the polyolefin (
A) Graft polymerization of unsaturated carboxylic acids or derivatives thereof to the polymers exemplified as A), one or more selected from olefins, and one or two selected from unsaturated carboxylic acids or derivatives thereof. These include those obtained by copolymerizing more than one species, and those obtained by graft polymerization of an unsaturated carboxylic acid or a derivative thereof.

In the present invention, these modified olefin polymers are
It is also possible to use a mixture of more than one species.

Here, examples of the unsaturated carboxylic acid used for modification include maleic acid, fumaric acid, itaconic acid, acrylic acid, and methacrylic acid. Derivatives of unsaturated carboxylic acids include their acid anhydrides, estenopeamides, imides, metal salts, etc. Specific examples include maleic anhydride, itaconic anhydride, methyl acrylate, ethinobeacrylic acid, etc. Petinobe glycidyl acrylate, methyl methacrylate, ethyl methacrylate,
Glycidyl methacrylate, maleic acid monoethyl ester, maleic acid diethyl ester, fumaric acid monomethyl ester, fumaric acid dimethyl esternoveacrylamide, methacrylamide, maleic acid monoamide, maleic acid diamide, fumaric acid monoamide, maleimide, N-butylmaleimide, methacryl Examples include sodium acid. Among these unsaturated carboxylic acids and derivatives thereof, preferred are glycidyl esters of acrylic acid and methacrylic acid and maleic anhydride, and preferred modified olefin polymers (B) modified with these are glycidyl esters of acrylic acid and methacrylic acid and maleic anhydride.
Examples include those modified by graft polymerizing maleic anhydride to olefin polymers whose main polymer constituent units are ethylene and/or propylene, and olefins whose main constituent units are ethylene and/or propylene and glycidyl (meth)acrylate. Examples include those modified by copolymerizing with ester or maleic anhydride.

In addition, the modified olefin polymer (B) used in the present invention is 0.1 to 40% by weight of the polymer constitutional units.
However, those consisting of the above-mentioned unsaturated carboxylic acids or derivatives thereof are preferred, and in particular when these components are introduced into the polymer chain by random copolymerization or block copolymerization, 3 to 40% by weight, and 3 to 40% by weight by graft polymerization. In some cases, it is preferably 0.1 to 10% by weight.

In the present invention, such a modified polyolefin polymer (
B) is used in an amount of 2 to 50 parts by weight based on 98 to 50 parts by weight of the polyolefin (A). If the amount of the modified polyolefin polymer (B) is less than this, the impregnation and adhesion of the resin to the fibers will be insufficient, so a composition with dramatically improved strength will not be obtained, and on the contrary, the If this happens, the processability will be impaired or the composition will not have the characteristics as a polyolefin resin composition. Preferably, the ratio is 5 to 30 parts by weight of the modified polyolefin polymer (B) to 95 to 70 parts by weight of the polyolefin (A).

Further, in the present invention, it is preferable that the polyolefin (A) and the modified polyolefin polymer (B) have the same main polymer constituent units.

As a specific example, component (A) is polyethylene and component (B
) component is a copolymer of ethylene and glycidyl methacrylate or a combination of ethylene-butene-1 copolymer grafted with maleic anhydride, component (A) is polypropylene and component (B) is a combination of maleic anhydride grafted. Examples include combinations of polypropylene.

Next, there are no particular restrictions on the type of reinforcing fiber (C) used in the present invention (for example, glass fiber, carbon fiber, metal fiber, high melting point (high softening point) resin fiber, etc. can all be used. .

In the present invention, the blending amount of the reinforcing fiber (C) is as follows:
5 to 80% by weight (in the composition). Compounding amount is 5% by weight
If it is less than 80% by weight, the reinforcing effect by the fiber is small;
If the m-fiber content is exceeded, the processability in preparing or molding the composition will be extremely poor, and hardly any improvement in strength can be expected by increasing the amount of m-fiber. Considering the balance between reinforcing effect and processability, the preferred amount of fiber is 20 to 70% by weight (in the composition), particularly preferably 30 to 65% by weight (in the composition).

The molding resin composition of the present invention comprises a polyolefin (A) as described above, a modified olefin polymer (B) and a reinforcing fiber (C), and the fiber has a length of 2 mm or more. and are arranged in substantially parallel to each other. When the fiber length is 2 mm or less,
When such a composition is molded, sufficient strength improvement cannot be expected.

The resin composition of the present invention may be supplemented with one or more other thermoplastic resins in small amounts as long as the purpose and effects thereof are not significantly impaired. In addition, in order to impart desired properties depending on the purpose, known substances that are generally added to thermoplastic resins, such as antioxidants, heat stabilizers, stabilizers such as ultraviolet absorbers, antistatic agents, flame retardants,
It is also possible to further include flame retardant aids, colorants such as dyes and pigments, lubricants, plasticizers, crystallization promoters, crystal nucleating agents, and the like. In addition, plate-like or powder-like inorganic compounds such as glass flakes, mica, glass powder, glass peas, talc, clay, alumina, carbon black, and wollastonite, whiskers, and the like may be used in combination.

In the present invention, a pultrusion method is particularly preferably used in producing such a resin composition.

As mentioned above, pultrusion is basically a method of impregnating a continuous reinforcing fiber with a resin while pulling it, and a method of impregnating the fiber by passing it through an impregnation bath containing a resin emulsion, suspension, or solution. A method in which resin powder is sprayed onto the fibers or the fibers are passed through a vat containing the powder, the resin powder is attached to the fibers, and then the resin is melted and impregnated.An extruder is used in which the fibers are not passed through a crosshead die. Methods of supplying and impregnating a crosshead die with resin are known from the above, and any of these known methods can be used in the present invention. The resin impregnation operation in such pultrusion molding is generally performed in one stage, but it may be performed in two or more stages. When performing the impregnation operation in one stage, a crosshead die is used to mix polyolefin (A) and modified olefin polymer (A) in a predetermined ratio.
Impregnation with the molten resin of B) is preferred. In addition, when the impregnation operation is carried out in two or more stages, each impregnation step involves impregnating with a resin containing an arbitrary ratio of polyolefin (A) and modified olefin polymer (B), and finally forming the desired composition. However, it is particularly preferable to impregnate with a resin rich in modified olefin polymer (B) in the first impregnation step.

Furthermore, a method in which at least the final impregnation operation is performed using a crosshead die is preferred.

In addition, as another impregnation method using pultrusion, polyolefin (A) and unsaturated carboxylic acid or its derivatives are melt-kneaded together with organic peroxide.
It is also possible to synthesize a modified olefin polymer (B) by impregnating the fibers and reacting a portion of the polyolefin (A) with an unsaturated carboxylic acid or a derivative thereof to obtain a desired resin composition.

In the method for producing the resin composition of the present invention using such pultrusion molding, the temperature of the molten resin for impregnating the fibers is preferably 240 to 320°C, and the polyolefin (A) is preferably polypropylene-based. When used, the above temperatures are particularly preferred.

There are no restrictions on the shape of the resin composition of the present invention thus obtained (it can be in any shape such as a strand, a sheet, a flat plate, or a pellet obtained by cutting a strand into an appropriate length). In particular, for application to easy injection molding, it is preferable to form the composition into pellets having a length of 2 to 50 mm.

〔Example〕

EXAMPLES Hereinafter, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited thereto.

Example 1 and Comparative Examples 1-2 1% by weight of maleic anhydride and 2.5% by weight of maleic anhydride in polypropylene
500 ppm of -dimethyl-2,5-di(t-butylperoxy)hexyne-3 was added, and the mixture was melt-kneaded and reacted at 200°C to obtain modified polypropylene.

Next, while drawing the glass roving through a crosshead die in which the continuous fiber passage was processed into a corrugated shape, 90 parts by weight of unmodified polypropylene supplied from an extruder connected to the crosshead die and 10 parts by weight of the modified polypropylene were melted. After being impregnated with the mixture (260° C.), it was pulled out and cut into strands through a shaping die to obtain a pellet-like composition with a glass fiber content of 40% by weight (in the composition) and a length of 12 mm.

In addition, for comparison, the length was compared to a pellet composition impregnated using only unmodified polypropylene without adding modified polypropylene and a mixture of 90 parts by weight of unmodified polypropylene and 10 parts by weight of the modified polypropylene described above. 40% by weight of 3mm short glass fibers (in the composition)
A pellet-like composition was prepared by blending, melt-kneading, and granulating using a twin-screw extruder.

These pellet compositions were injection molded and the results of evaluation are shown in Table 1.

The physical properties were measured as follows.

Tensile strength: Based on 85TyID-638 Bending strength:
Based on ASTM D-790 Flexural modulus: ASTM D
-790 Impact strength: Measure the notched Izo impact strength according to ASTM D-256 (test piece thickness 6.3 mm) Deformation: Form a 3 mm thick flat plate with 1Qcm square,
Surface condition observed with the naked eye for magnitude of deformation (warp): Example 2 and Comparative Examples 3 to 4, in which the surface condition of the above flat plate was observed with the naked eye (using a block copolymer of ethylene and propylene instead of unmodified polypropylene) Pellet-like compositions were prepared in exactly the same manner as in Example 1 and Comparative Examples 1 and 2 except for the above, injection molded, and evaluated.

The results are shown in Table 2.

〔Effect of the invention〕

As is clear from the above explanation and examples, the long fiber reinforced polyolefin resin composition for molding of the present invention is made by using a polyolefin and a modified olefin polymer as a base resin, and reinforcing this with long fibers arranged in parallel. It not only has extremely high mechanical properties such as tensile strength, bending strength, and impact strength, but also has excellent features such as good surface condition of molded products, little warping and deformation, and good dimensional stability. Therefore, it has extremely high industrial value.

Claims (1)

[Scope of Claims] 1 A resin component consisting of 98 to 50 parts by weight of a polyolefin (A) and 2 to 50 parts by weight of a modified olefin polymer (B) modified with an unsaturated carboxylic acid or a derivative thereof; Contains ~80% by weight of reinforcing fiber (C),
A polyolefin resin composition for molding reinforced with long fibers, characterized in that substantially all of the fibers have a length of at least 2 mm or more and are arranged substantially parallel to each other in the resin. 2. The long fiber reinforced polyolefin resin composition for molding according to claim 1, wherein the polyolefin (A) is mainly composed of polyethylene or polypropylene. 3 The modified olefin polymer (B) contains ethylene and/or
The long fiber reinforced polyolefin resin composition for molding according to claim 1 or 2, which is modified by graft polymerizing maleic anhydride to an olefin polymer having propylene as a main polymer constituent unit. 4 The modified olefin polymer (B) contains ethylene and/or
or modified by copolymerizing an olefin mainly composed of propylene and (meth)acrylic acid glycidyl ester or maleic anhydride.
The long fiber reinforced polyolefin resin composition for molding. 5. Any one of claims 1 to 4, wherein the resin composition is in the form of pellets with a length of 2 to 50 mm, and the reinforcing fibers (C) are arranged in the length direction of the pellets with substantially the same length as the pellets. The polyolefin resin composition for long fiber reinforced molding according to item 1. 6. A molded article formed by injection molding using the long fiber reinforced polyolefin resin composition for molding according to any one of claims 1 to 5. 7 While pulling the reinforcing continuous fibers, add polyolefin (A
) and 2 to 50 parts by weight of a modified olefin polymer (B) modified with an unsaturated carboxylic acid or its derivative.
A method for producing a long fiber-reinforced polyolefin resin composition for molding, characterized by containing 80% by weight of reinforcing fibers (C). 8. The long fiber reinforced polyolefin resin for molding according to claim 7, wherein the reinforcing continuous fibers are impregnated with a molten mixture of polyolefin (A) and modified olefin polymer (B) supplied from an extruder while being drawn through a crosshead die. Method of manufacturing the composition. 9. The method for producing a long fiber-reinforced polyolefin resin composition for molding according to claim 7 or 8, wherein the polyolefin (A) is mainly composed of polyethylene or polypropylene. 10. Any one of claims 7 to 9, wherein the modified olefin polymer (B) is modified by graft polymerizing maleic anhydride to an olefin polymer whose main polymer constituent units are ethylene and/or propylene. A method for producing a long fiber-reinforced polyolefin resin composition for molding according to item 1. 11. Claims 7 to 11, wherein the modified olefin polymer (B) is one modified by copolymerizing an olefin mainly composed of ethylene and/or propylene and (meth)acrylic acid glycidyl ester or maleic anhydride. 9
A method for producing a long fiber-reinforced polyolefin resin composition for molding according to any one of the above. 12 Claim 7 Impregnated with molten resin at 240-320°C
12. A method for producing a long fiber reinforced polyolefin resin composition for molding according to any one of items 1 to 11.