JP7071842B2 - Organic fiber reinforced resin composition and its manufacturing method - Google Patents

Description

The present invention relates to an organic fiber reinforced resin composition and a method for producing the same, and more particularly to an organic fiber reinforced resin composition containing an olefin resin and a method for producing the same.

Olefin-based resins are widely used in various fields such as automobile interior parts and exterior parts because they are highly versatile, inexpensive, and have excellent mechanical properties. In such an olefin resin, organic fibers such as wood flour, cellulose fibers and polyester fibers and inorganic fibers such as glass fibers and carbon fibers are blended in order to improve mechanical properties. For example, Japanese Patent Application Laid-Open No. 7-62167 (Patent Document 1) describes 100 parts by mass of a crystalline propylene polymer (A) having a melt flow rate of 0.2 g / 10 minutes or more and 100 g / 10 minutes or less and an inorganic filler. Described is an organic fiber-based propylene resin composition having excellent heat resistance, rigidity, and moldability, which contains 10 to 100 parts by mass of a polyester fiber (B) such as a polyethylene terephthalate fiber. However, the conventional fiber-reinforced resin composition in which organic fibers and inorganic fibers are blended with an olefin resin exhibits brittle behavior, and has a problem that the molded body breaks under a tensile load.

Japanese Unexamined Patent Publication No. 7-62167

The present invention has been made in view of the above-mentioned problems of the prior art, and provides an olefin resin composition which exhibits ductile behavior under a tensile load and prevents breakage of a molded product, and a method for producing the same. The purpose is.

As a result of diligent research to achieve the above object, the present inventors have made a large melt mass flow rate (MFR) specific as the olefin resin in the organic fiber reinforced resin composition containing the olefin resin and the organic fiber. ) In combination with an olefin resin having a specific small melt mass flow rate (MFR), a ductile behavior is exhibited under a tensile load, and breakage of the molded product is suppressed. And completed the present invention.

That is, the organic fiber reinforced resin composition of the present invention has a first olefin resin having a melt mass flow rate of 10 to 200 g / 10 min and a melt mass flow rate of 0.2 to 5 g / 10 min , and is a homopolymer of ethylene. And at least one second olefin resin selected from the group consisting of homopolymers of propylene and organic fibers.
The mass ratio of the first olefin resin to the second olefin resin is 20:80 to 80:20.
The content of the organic fiber is 5 to 100 parts by mass with respect to 100 parts by mass of the total amount of the first olefin resin and the second olefin resin.
It is characterized by that.

In such an organic fiber reinforced resin composition of the present invention, the first olefin resin is selected from at least a group consisting of a homopolymer of ethylene, a homopolymer of propylene, and a copolymer of ethylene and propylene. It is preferably one kind, and the second olefin resin is preferably a copolymer of propylene . Further, the organic fiber is preferably a plant fiber.

In the method for producing an organic fiber reinforced resin composition of the present invention, after mixing an organic fiber with a first olefin resin having a melt mass flow rate of 10 to 200 g / 10 min, the melt mass flow rate is 0.2 to 5 g / 10 min. It is characterized in that at least one second olefin-based resin selected from the group consisting of a homopolymer of ethylene and a homopolymer of propylene is further mixed.

In the present invention, the melt mass flow rate (MFR) of the olefin resin is a value measured under standard conditions set for each resin in accordance with JIS K7210. As the standard conditions, the temperature: 190 ° C. and load: 21.2N for polyethylene, the temperature: 230 ° C. and load: 21.2N for polypropylene, and the temperature for ethylene-propylene copolymers. : 230 ° C, load: 21.2N, temperature: 190 ° C for other ethylene-based copolymers, load: 21.2N, temperature: 230 ° C, load: for other propylene-based copolymers. It is set to 21.2N.

Further, the reason why the organic fiber reinforced resin composition of the present invention exhibits ductile behavior under a tensile load and the fracture of the molded body is suppressed is not always clear, but the present inventors infer as follows. .. That is, in the case of producing the organic fiber reinforced resin composition of the present invention, first, the first olefin resin having a specific large MFR and the organic fiber are mixed. By using the first olefin resin having a specific large MFR, breakage of organic fibers and abnormal heat generation during mixing can be suppressed, and deterioration of organic fibers can be prevented. Next, a second olefin resin having a specific small MFR is mixed with the mixture thus obtained. Since the second olefin resin having a specific small MFR has a large molecular weight, the molecular chains are entangled with each other, and this entanglement suppresses the growth of cracks in the first olefin resin under a tensile load and is ductile. Is given, and it is presumed that the breakage of the molded body is suppressed.

According to the present invention, it is possible to obtain an olefin-based resin composition that exhibits ductile behavior under a tensile load and prevents fracture of the molded body.

It is a graph which shows the stress-strain curve (representative value) of the organic fiber reinforced resin composition obtained in Example 1 and Comparative Examples 1 and 2. It is a graph which shows the stress-strain curve (representative value) of the organic fiber reinforced resin composition obtained in Example 2 and Comparative Examples 3-4. It is a graph which shows the stress-strain curve (representative value) of the carbon fiber reinforced resin composition obtained in the comparative example 5.

Hereinafter, the present invention will be described in detail according to the preferred embodiment thereof.

First, the organic fiber reinforced resin composition of the present invention will be described. The organic fiber reinforced resin composition of the present invention has a first olefin resin having a melt mass flow rate (MFR) of 10 to 200 g / 10 min and a second melt mass flow rate (MFR) of 0.2 to 5 g / 10 min. It contains an olefin resin and an organic fiber.

(First olefin resin)
The first olefin-based resin used in the present invention is an olefin-based resin having an MFR in the range of 10 to 200 g / 10 min. By using such an olefin resin having a large MFR, while ensuring good molding processability of the resin composition, breakage and abnormal heat generation of the organic fiber at the time of mixing with the organic fiber are suppressed, and deterioration of the organic fiber is prevented. Can be prevented. On the other hand, when the MFR of the first olefin resin is less than the above lower limit, the fluidity is low, so that the molding processability of the resin composition is lowered, and the organic fibers are broken or abnormally heat is generated when mixed with the organic fibers. On the other hand, if the upper limit is exceeded, the mechanical strength of the molded body is lowered. The MFR of the first olefin-based resin is from the viewpoint of improving the molding processability of the resin composition and sufficiently suppressing the breakage and abnormal heat generation of the organic fiber when mixed with the organic fiber. 15 g / 10 min or more is preferable, 20 g / 10 min or more is more preferable, and 100 g / 10 min or less is preferable, and 75 g / 10 min or less is more preferable from the viewpoint of improving the mechanical strength of the molded product.

The first olefin-based resin is not particularly limited as long as the MFR is within the above range, and for example, ethylene homopolymer (polyethylene), propylene homopolymer (polyethylene), and ethylene. Examples thereof include a copolymer of propylene, a copolymer of ethylene and an α-olefin having 4 or more carbon atoms, and a copolymer of propylene and an α-olefin having 4 or more carbon atoms. Examples of the α-olefin having 4 or more carbon atoms include 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene and the like. These first olefin resins may be used alone or in combination of two or more. Among such first olefin resins, ethylene homopolymers, propylene homopolymers, ethylene and propylene copolymers, and theirs, from the viewpoint of moldability and stability of the molded product, are used. Mixtures are preferred.

(Second olefin resin)
The second olefin-based resin used in the present invention is an olefin-based resin having an MFR in the range of 0.5 to 5 g / 10 min. By using such an olefin resin having a small MFR, the growth of cracks in the first olefin resin under a tensile load is suppressed, and ductility is imparted, so that the fracture of the molded product is suppressed. Can be done. On the other hand, when the MFR of the second olefin resin is less than the lower limit, the fluidity is low, so that the molding processability of the resin composition is lowered. On the other hand, when the MFR exceeds the upper limit, the first under a tensile load. Since the growth of cracks in the olefin-based resin is not suppressed and the ductility is not imparted, the molded product breaks. As the MFR of such a second olefin resin, the growth of cracks in the first olefin resin under a tensile load is sufficiently suppressed, and ductility is sufficiently imparted, so that the molded product breaks. From the viewpoint of sufficient prevention, 3 g / 10 min or less is preferable, and 1.5 g / 10 min or less is more preferable.

The second olefin resin is not particularly limited as long as the MFR is within the above range, and for example, ethylene homopolymer (polyethylene), propylene homopolymer (polyethylene), and ethylene. Examples thereof include a copolymer of propylene, a copolymer of ethylene and an α-olefin having 4 or more carbon atoms, and a copolymer of propylene and an α-olefin having 4 or more carbon atoms. Examples of the α-olefin having 4 or more carbon atoms include 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene and the like. These second olefin resins may be used alone or in combination of two or more. Among such second olefin resins, ethylene homopolymers, propylene homopolymers, ethylene and propylene copolymers, and their products, from the viewpoint of moldability and stability of the molded product, are used. Mixtures are preferred.

(Organic fiber)
In the present invention, organic fiber is used as the reinforcing fiber. As a result, the mechanical strength is improved, and the combination with the first and second olefin resins makes it possible to prevent the molded product from breaking. On the other hand, when inorganic fibers such as glass fiber and carbon fiber are used as the reinforcing fibers, it is difficult to prevent the molded product from breaking even by combining with the first and second olefin resins.

Examples of such organic fibers include plant fibers such as wood flour, pulp and cellulose nanofibers (finely divided pulp); synthetic fibers such as polyester fibers and polyamide fibers. These organic fibers may be used alone or in combination of two or more. Among such organic fibers, plant fibers are preferable from the viewpoint of fiber flexibility, and in particular, when cellulose nanofibers are used, a molded product is formed by blending the second olefin resin. Not only is it prevented from breaking, but also the tensile strength and tensile elastic modulus tend to be improved.

The average diameter of such organic fibers is preferably 10 nm to 100 μm. When the average diameter of the organic fibers is less than the lower limit, it tends to be difficult to obtain the reinforcing effect, while when the average diameter exceeds the upper limit, the molded product tends to be embrittled. The average fiber length is preferably 1 μm to 50 mm. When the average fiber length of the organic fiber is less than the lower limit, it tends to be difficult to obtain the reinforcing effect, while when the average fiber length exceeds the upper limit, the viscosity tends to increase due to the entanglement of the fibers and the appearance tends to be poor.

(Other ingredients)
The organic fiber reinforced resin composition of the present invention may contain various additives such as flame retardants, antistatic agents, nucleating agents, plasticizers, and colorants as long as the effects of the present invention are not impaired. ..

<Organic fiber reinforced resin composition>
The organic fiber reinforced resin composition of the present invention contains the first olefin resin and the second olefin resin in a mass ratio of first: second = 20: 80 to 80:20. be. When the mass ratio of the first olefin resin to the second olefin resin is less than the lower limit, the fluidity of the resin composition is lowered, so that good molding processability of the resin composition cannot be ensured. On the other hand, if the upper limit is exceeded, the growth of cracks in the first olefin resin under a tensile load is not suppressed and the ductility is not imparted, so that the molded product breaks. Further, as the mass ratio of such an olefin-based resin, good molding processability of the resin composition is ensured, and the growth of cracks in the first olefin-based resin under a tensile load is sufficiently suppressed. From the viewpoint that ductility is sufficiently imparted and breakage of the molded product can be sufficiently prevented, the first: second = 30:70 to 70:30 is preferable, and 35:65 to 65:35 is more preferable.

Further, the organic fiber reinforced resin composition of the present invention contains the organic fiber in an amount of 5 to 100 parts by mass with respect to 100 parts by mass of the total amount of the first olefin resin and the second olefin resin. It is a thing. When the content of the organic fiber is less than the lower limit, the mechanical strength is lowered, while when the content exceeds the upper limit, the moldability is deteriorated due to the increase in viscosity and the molded product is broken. The content of such organic fibers is preferably 5 to 50 parts by mass, more preferably 10 to 25 parts by mass, from the viewpoint of achieving both moldability and mechanical properties of the molded product.

<Manufacturing method of organic fiber reinforced resin composition>
Next, a method for producing the organic fiber reinforced resin composition of the present invention will be described. In the method for producing an organic fiber reinforced resin composition of the present invention, first, the first olefin resin and the organic fiber are mixed, and then the obtained mixture and the second olefin resin are mixed. do. By first mixing the first olefin resin and the organic fiber, breakage of the organic fiber and abnormal heat generation at the time of mixing can be suppressed, and deterioration of the organic fiber can be prevented. On the other hand, when the second olefin resin and the organic fiber are mixed first, or when the first olefin resin, the second olefin resin and the organic fiber are mixed at the same time, they are mixed. Breaking of organic fibers and abnormal heat generation at times are not sufficiently suppressed, the organic fibers are deteriorated, and the strengthening effect of the organic fibers cannot be sufficiently obtained.

The mixing method of the first olefin resin and the organic fiber is not particularly limited, and for example, known mixing methods such as wet mixing (solution mixing), dry mixing, and melt mixing can be adopted. Further, there is no particular limitation on the mixing method of the mixture of the first olefin resin and the organic fiber and the second olefin resin, for example, wet mixing (solution mixing), dry mixing, melt mixing and the like. A known mixing method can be adopted.

The organic fiber reinforced resin composition of the present invention produced in this manner is molded into a desired shape according to the intended use. The molding method is not particularly limited, and known molding methods such as extrusion molding and injection molding can be adopted. The organic fiber reinforced resin molded body thus molded is not only excellent in mechanical strength, but also does not break even under a tensile load.

Hereinafter, the present invention will be described in more detail based on Examples and Comparative Examples, but the present invention is not limited to the following Examples.

(Example 1)
First, block polypropylene (bPP) (“Nobren AZ864” manufactured by Sumitomo Chemical Co., Ltd.) with an MFR of 33 g / 10 min measured at a temperature of 230 ° C. and a load of 21.2 N in accordance with JIS K7210 and Sugi fine fibers (Sugi wood). Physically crushed with a hammer mill. Average diameter: several μm to several tens of μm) and mass ratio (bPP: Sugi fine fiber) using a twin-screw extruder (“TEX30” manufactured by Nippon Steel Co., Ltd.) Sugi fiber reinforced block polypropylene (bPP-Sugi fiber) was prepared by melt-kneading at 70:30.

Next, the obtained bPP-sugi fiber and polypropylene (PP) having an MFR of 0.5 g / 10 min measured at a temperature of 230 ° C. and a load of 21.2 N according to JIS K7210 (Prime Polymer Co., Ltd. "Prime" Polypro E111G ”) is dry-blended at a mass ratio (bPP-sugi fiber: PP) = 50: 50, and then a cylinder temperature 220 ° C. and a mold temperature are used using an injection molding machine (“Mobile 0813” manufactured by Shinko Selvik Co., Ltd.). Injection molding was performed under the condition of 50 ° C. to prepare a JIS 1BA type dumbbell-shaped test piece (described in JIS K7162 "Annex A small test piece").

(Example 2)
Instead of the bPP having an MFR of 33 g / 10 min, polypropylene (PP) having an MFR of 45 g / 10 min measured at a temperature of 230 ° C. and a load of 21.2 N according to JIS K7210 (Prime Polypro J108M manufactured by Prime Polymer Co., Ltd.) ”) Was used, and coniferous pulp (a beaten-treated coniferous kraft pulp) was used instead of the cedar fine fibers, and the mass ratio was changed to PP: coniferous pulp = 80:20, in the same manner as in Example 1. To prepare coniferous pulp-reinforced polypropylene (PP-pulp).

Instead of the bPP-sugi fiber, the PP-pulp is dry-blended with polypropylene (PP) having an MFR (230 ° C., 21.2 N load) of 0.5 g / 10 min ("Prime Polypro E111G" manufactured by Prime Polymer Co., Ltd.). A JIS1AB type dumbbell-shaped test piece was prepared in the same manner as in Example 1.

(Comparative Example 1)
Instead of the PP having an MFR of 0.5 g / 10 min, block polypropylene (bPP) having an MFR (230 ° C., 21.2 N load) of 33 g / 10 min (“Nobren AZ864” manufactured by Sumitomo Chemical Co., Ltd.) was used as the bPP-sugi. A JIS 1BA type dumbbell-shaped test piece was prepared in the same manner as in Example 1 except that it was dry-blended with the fiber.

(Comparative Example 2)
Instead of the PP having an MFR of 0.5 g / 10 min, polypropylene (PP) having an MFR of 11 g / 10 min measured at a temperature of 230 ° C. and a load of 21.2 N according to JIS K7210 (Novatec, manufactured by Japan Polypropylene Corporation) A JIS 1BA type dumbbell-shaped test piece was prepared in the same manner as in Example 1 except that MA3 ”) was dry-blended with the bPP-sugi fiber.

(Comparative Example 3)
Instead of the PP having an MFR of 0.5 g / 10 min, polypropylene (PP) having an MFR (230 ° C., 21.2 N load) of 45 g / 10 min (“Prime Polypro J108M” manufactured by Prime Polymer Co., Ltd.) is used as the PP-pulp. A JIS 1BA type dumbbell-shaped test piece was prepared in the same manner as in Example 2 except that it was dry-blended.

(Comparative Example 4)
Instead of the PP having an MFR of 0.5 g / 10 min, polypropylene (PP) having an MFR (230 ° C., 21.2 N load) of 11 g / 10 min (“Novatec MA3” manufactured by Japan Polypropylene Corporation) was used as the PP-pulp. A JIS 1BA type dumbbell-shaped test piece was prepared in the same manner as in Example 2 except that it was dry-blended.

(Comparative Example 5)
Instead of the bPP-sugi fiber, carbon fiber reinforced polypropylene (PP-CF) (“Plastron PP-CF20” manufactured by Daicel Polymer Co., Ltd., fiber concentration: 20% by mass) is used in MFR (230 ° C., 21.2 N load). A JIS 1BA type dumbbell-shaped test piece was prepared in the same manner as in Example 1 except that it was dry-blended with 0.5 g / 10 min polypropylene (PP) (“Prime Polypro E111G” manufactured by Prime Polymer Co., Ltd.).

<Tensile test>
Each dumbbell-shaped test piece obtained in Examples and Comparative Examples was allowed to stand in a constant temperature and humidity room set at a temperature of 23 ° C. and a relative humidity of 50% for 48 hours, and then a universal testing machine (Instron's "4302"). A tensile test was performed at a displacement speed of 2 mm / min using the above), and the tensile strength (maximum tensile stress) and the elongation at break were measured. The results (mean value of the number of test pieces n = 3) are shown in Table 1. Further, FIGS. 1 to 3 show stress-strain curves (representative values) of the dumbbell-shaped test pieces obtained in Examples 1 and 2 and Comparative Examples 1 to 5.

As is clear from the results shown in FIGS. 1 and 1, the present invention contains a first olefin resin having a predetermined large MFR, a second olefin resin having a predetermined small MFR, and cedar fine fibers. It was confirmed that the organic fiber reinforced resin composition (Example 1) of No. 1 continued to stretch without breaking and exhibited excellent ductility. On the other hand, an organic fiber reinforced resin composition containing one or two first olefin resins having a predetermined large MFR as olefin resins and not containing a second olefin resin having a predetermined small MFR (comparative). It was found that Examples 1 and 2) started yielding with a lower stress than the organic fiber reinforced resin composition of Example 1 and broke without showing ductility. Further, the organic fiber reinforced resin composition of Example 1 is superior in tensile strength to the organic fiber reinforced resin compositions of Comparative Examples 1 and 2, and in particular, one kind of predetermined large MFR as an olefin resin is used. It was found that the tensile strength was extremely excellent and the tensile elasticity was also excellent as compared with the organic fiber reinforced resin composition (Comparative Example 1) containing only the first olefin resin having. From the above results, in the organic fiber reinforced resin composition containing the olefin resin and the fine fiber of cedar, the first olefin resin having a predetermined large MFR and the second having a predetermined small MFR as the olefin resin. By using the above olefin-based resin in combination, ductility is imparted, and as compared with the case where only the first olefin-based resin having one or more predetermined large MFRs is used as the olefin-based resin. It was found that the tensile strength was improved, and further, the tensile elasticity was improved as compared with the case where only the first olefin-based resin having one kind of predetermined large MFR was used as the olefin-based resin.

Further, as is clear from the results shown in FIGS. 2 and 1, a book containing a first olefin resin having a predetermined large MFR, a second olefin resin having a predetermined small MFR, and coniferous pulp. It was confirmed that the organic fiber reinforced resin composition of the present invention (Example 2) continued to stretch without breaking and exhibited excellent ductility. On the other hand, an organic fiber reinforced resin composition containing one or two kinds of a first olefin resin having a predetermined large MFR as an olefin resin and not containing a second olefin resin having a predetermined small MFR (comparative). In Examples 3 to 4), an organic fiber reinforced resin composition (Comparative Example) containing only a first olefin-based resin having two types of predetermined large MFRs as olefin-based resins, which breaks without showing ductility. It was found that 4) started yielding with a lower stress than that of the organic fiber reinforced resin composition of Example 2. Further, it was found that the organic fiber reinforced resin composition of Example 2 was superior in tensile strength to the organic fiber reinforced resin composition of Comparative Example 4. From the above results, in the organic fiber reinforced resin composition containing the olefin resin and the coniferous tree pulp, the first olefin resin having a predetermined large MFR and the second olefin resin having a predetermined small MFR as the olefin resin. By using it in combination with an olefin resin, ductility is imparted, and the tensile strength is higher than when only the first olefin resin having two or more predetermined large MFRs is used as the olefin resin. It turned out to improve.

Further, as is clear from the results shown in FIGS. 3 and 1, when carbon fiber is used as the reinforcing fiber (Comparative Example 5), a second olefin resin having a predetermined small MFR is blended. However, the carbon fiber reinforced resin composition broke and it was difficult to impart ductility.

As described above, according to the present invention, it is possible to impart ductility to an organic fiber reinforced resin composition containing an olefin resin and an organic fiber.

Therefore, the organic fiber reinforced resin composition of the present invention not only has excellent mechanical strength, but also does not break even under a tensile load. Therefore, for example, in various applications such as automobile interior parts and exterior parts. It is useful as a material for resin molded products.

Claims (5)

It is selected from the group consisting of a first olefin resin having a melt mass flow rate of 10 to 200 g / 10 min and a homopolymer of ethylene and a homopolymer of propylene having a melt mass flow rate of 0.2 to 5 g / 10 min. Containing at least one second olefin resin and organic fiber,
The mass ratio of the first olefin resin to the second olefin resin is 20:80 to 80:20.
The content of the organic fiber is 5 to 100 parts by mass with respect to 100 parts by mass of the total amount of the first olefin resin and the second olefin resin.
An organic fiber reinforced resin composition characterized by this. The first aspect of claim 1, wherein the first olefin-based resin is at least one selected from the group consisting of a homopolymer of ethylene, a homopolymer of propylene, and a copolymer of ethylene and propylene. Organic fiber reinforced resin composition. The organic fiber reinforced resin composition according to claim 1 or 2, wherein the second olefin resin is a homopolymer of propylene . The organic fiber reinforced resin composition according to any one of claims 1 to 3, wherein the organic fiber is a plant fiber. After mixing the first olefin resin having a melt mass flow rate of 10 to 200 g / 10 min and the organic fiber, the melt mass flow rate is 0.2 to 5 g / 10 min , and the ethylene homopolymer and the propylene homopolymer. A method for producing an organic fiber reinforced resin composition, which comprises further mixing at least one second olefin resin selected from the group consisting of.

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