JP7057113B2 - Resin composition and resin molded product - Google Patents

Description

The present invention relates to a resin composition and a resin molded product.

The polyacetal resin has an excellent balance of mechanical strength, chemical resistance, slidability, and wear resistance, and can be easily processed. Therefore, polyacetal resin is widely used as one of the representative engineering plastics in mechanical parts, automobile parts, and other parts of electric equipment.

Further, in response to the recent trend of improving fuel efficiency in automobiles, parts made of polyacetal resin are also required to be lightened by thinning, and electronic devices are also required to be thinned. In this regard, even if thinning is achieved, it is important that performance (rigidity, slidability, thermal stability, etc.) equal to or higher than that of the conventional one is ensured.

For example, in Patent Document 1, a resin molded product containing a polyacetal resin and glass fibers having a fiber diameter and a fiber length in a predetermined range and having a melt flow rate in a predetermined range has excellent thin-walled formability. It is disclosed that high creepability can be satisfied at the same time.

Further, Patent Document 2 discloses that a molded product containing a polyacetal resin having a predetermined range of comonomer components and at least one coupling agent can satisfy excellent mechanical properties and high heat distortion temperature. ing.

Japanese Unexamined Patent Publication No. 2016-89033 International Publication No. 2014/09727

However, if the fluidity of the resin composition is increased for a thin-walled molded product, the slidability of the molded product tends to be unstable. Further, when ultra-high molecular weight polyethylene or the like is used as the sliding agent, although high slidability can be obtained, there is a problem that it is difficult to obtain a sliding effect at the initial stage of sliding.

Therefore, an object of the present invention is to provide a resin composition and a resin molded product that simultaneously satisfy excellent thin-wall moldability and high slidability.

As a result of diligent studies to solve the above-mentioned problems of the prior art, the present inventors have found that the melt flow rate contains a polyethylene resin in a specific range, and the ratio of the polyacetal resin metroflorate to the polyethylene resin melt flow rate. Has found that a resin composition having a specific range can solve the above-mentioned problems, and has completed the present invention.

That is, the present invention is as follows.
[1] Includes (A) 100 parts by mass of polyacetal resin, (B) 10 parts by mass or more and 55 parts by mass or less of glass fiber, and (C) 0.1 parts by mass or more and 5 parts by mass or less of polyethylene resin.
The melt flow rate (ISO1133 compliant, temperature 190 ° C., load 2.16 kg) of the polyethylene resin (C) is 10 g / 10 minutes or more and 100 g / 10 minutes or less.
The ratio of the metroflorate of the polyacetal resin (ISO1133 compliant, temperature 190 ° C., load 2.16 kg) to the melt flow rate of the polyethylene resin is 0.1 or more and 2.0 or less. A characteristic resin composition.
[2] The resin composition according to [1], wherein the melt flow rate (ISO1133 compliant, temperature 190 ° C., load 2.16 kg) is 8 g / 10 minutes or more.
[3] The resin composition according to any one of [1] and [2], wherein the melt flow rate of the (A) polyacetal resin is 10 g / 10 minutes or more and 100 g / 10 minutes or less.
[4] The resin composition according to any one of [1] to [3], wherein the polyacetal resin (A) has a comonomer concentration of 1.5 mol% or less.
[5] The resin composition according to any one of [1] to [4], wherein the polymonomer concentration of the (A) polyacetal resin is 0 mol% or more and 1.0 mol% or less.

[6] A resin molded product comprising the resin composition according to any one of [1] to [5].
[7] The resin molded product according to [6], which has a thickness of 1 mm or less.
[8] The resin molded product according to [7], which is used as a part for an electric device or a part for an electronic device.

According to the present invention, it is possible to provide a resin composition and a resin molded product that simultaneously satisfy excellent thin-wall moldability and high slidability.

Hereinafter, embodiments for carrying out the present invention (hereinafter referred to as the present embodiment) will be described in detail. The following embodiments are examples for explaining the present invention, and the present invention is not limited to the following contents. The present invention can be variously modified and carried out within the scope of the gist thereof.

[Resin composition]
The resin composition of the present embodiment (hereinafter, also referred to as “polyacetal resin composition”) includes (A) 100 parts by mass of polyacetal resin, (B) 10 parts by mass or more and 55 parts by mass or less of glass fiber, and (C) polyethylene. The melt flow rate (ISO1133 compliant, temperature 190 ° C., load 2.16 kg) of the (C) polyethylene resin is 10 g / 10 minutes or more and 100 g / 10 minutes or less, including 0.1 parts by mass or more and 5 parts by mass or less of the resin. The ratio of the melt flow rate of the polyacetal resin (ISO1133 compliant, temperature 190 ° C., load 2.16 kg) to the melt flow rate of the (C) polyethylene resin is 0.1 or more and 2.0 or less. Further, the resin molded product of the present embodiment may contain a sliding agent, a stabilizer, other components and the like in addition to the above-mentioned components.

The resin composition of the present embodiment preferably has a melt flow rate (ISO1133 compliant, temperature 190 ° C., load 2.16 kg) (hereinafter, also simply referred to as MFR) of 8 g / 10 minutes or more, more preferably. 10 g / 10 minutes or more. By setting the MFR of the resin composition in this range, the thin-walled moldability can be improved. The upper limit of the MFR of the resin composition is not particularly limited, but is preferably 30 g / 10 minutes or less from the viewpoint of thermal stability during molding.
The MFR is one of the indexes of the magnitude of fluidity, and the MFR of the resin composition is, for example, a resin composition or a resin molded product containing the same, which is finely cut into pellet-shaped samples as described above. It can be confirmed by measuring in accordance with the standards and conditions of.

<(A) Polyacetal resin>
The (A) polyacetal resin (which may be referred to as (A) component or (A) in the present specification) that can be used in the resin composition of the present embodiment will be described in detail.
Examples of the (A) polyacetal resin that can be used in the present embodiment include polyacetal homopolymers and polyacetal copolymers.
Specific examples of the polyacetal homopolymer include a polyacetal homopolymer obtained by homopolymerizing a formaldehyde monomer or a cyclic oligomer of formaldehyde such as a trimer (trioxane) or a tetramer (tetraoxane) thereof.
Specifically, as the polyacetal copolymer, a cyclic oligomer of formaldehyde such as a formaldehyde monomer or its trimer (trioxane) or tetramer (tetraoxane) is copolymerized with a cyclic ether or cyclic formal as a comonomer. Examples thereof include polyacetal copolymers obtained in the above. Here, examples of the cyclic ether or cyclic formal include glycols such as ethylene oxide, propylene oxide, epichlorohydrin, 1,3-dioxolane and 1,4-butanediol formal, and cyclic formal of diglycol.

Further, as the polyacetal copolymer, a polyacetal copolymer having a branch obtained by copolymerizing a monomer of formaldehyde and / or a cyclic oligomer of formaldehyde and a monofunctional glycidyl ether as a commonomer, and a monomer of formaldehyde. And / or a polyacetal copolymer having a crosslinked structure obtained by copolymerizing a cyclic oligomer of formaldehyde and a polyfunctional glycidyl ether as a comonomer can also be mentioned.

Further, the (A) polyacetal resin may contain a block copolymer having a different block component as a comonomer component, which is different from the repeating structural unit (that is, the oximethylene unit) of the polyacetal. The block copolymer may be a homopolymer-based block copolymer having a block component, or may be a copolymer-based block copolymer having a block component.

(A) The melt flow rate of the polyacetal resin (ISO1133 compliant, temperature 190 ° C., load 2.16 kg) is preferably 10 g / 10 minutes or more and 100 g / 10 minutes or less. More preferably, it is 15 g / 10 minutes or more and 90 g / 10 minutes or less, and further preferably 20 g / 10 minutes or more and 80 g / 10 minutes or less. (A) When the MFR of the polyacetal resin is in such a range, it is easy to achieve both high thin-wall molding and high slidability.
(A) The MFR of the polyacetal resin can be measured in accordance with the above-mentioned standards and conditions.
When the (A) polyacetal resin is contained in the resin composition or the resin molded product, the (A) polyacetal resin is isolated from the resin composition or the resin molded product and measured in accordance with the above-mentioned standards and conditions. This can be confirmed. For example, a part of the resin composition or the resin molded body is cut out and immersed in HFIP to dissolve the soluble component, and then HFIP as a solvent is evaporated and removed from the solution to isolate (A) the polyacetal resin. be able to.
If the soluble component contains a stabilizer, lubricant, etc., separate and measure as necessary.

The comonomer concentration of the polyacetal resin (A) preferably has an upper limit of 1.5 mol% or less, more preferably 1.2 mol% or less, still more preferably 1.0 mol% or less, and a lower limit of 0.0005 mol% or more. It is preferable, more preferably 0.001 mol% or more, still more preferably 0.002 mol% or more. (A) When the concentration of the comonomer of the polyacetal resin is in such a range, it is easy to maintain the desired mechanical properties even when thin-wall molding is performed.
Here, the comonomer concentration of the (A) polyacetal resin means the content of all comonomer units other than the oximethylene unit in all the units constituting the (A) polyacetal resin. (A) The comonomer unit constituting the polyacetal resin may be one kind or two or more kinds.
When the (A) polyacetal resin is a polyacetal homopolymer, the comonomer concentration is 0 mol%.

The polyacetal resin (A) constituting the resin composition of the present embodiment includes the above-mentioned polyacetal copolymer, polyacetal copolymer having branches, and crosslinked structure in the range where the homopolymer concentration of the (A) polyacetal resin is 1.5 mol% or less. Any of a polyacetal copolymer having a block component, a homopolymer-based block copolymer having a block component, and a copolymer-based block copolymer having a block component can be used, and these can also be used in combination.

Further, as the (A) polyacetal resin, for example, a combination having different molecular weights, a combination of polyacetal copolymers having different comonomer concentrations, and the like can be appropriately used.

<(B) Glass fiber>
The (B) glass fiber (which may be referred to as (B) component and (B) in the present specification) used in the resin composition of the present embodiment is not particularly limited, but is a chopped strand glass fiber. , Milled glass fiber, glass fiber roving and the like. Among these, chopped strand glass fiber is preferable from the viewpoint of handleability and mechanical strength of the molded product.
These (B) glass fibers may be used alone or in combination of two or more.

(B) The fiber diameter, fiber length, and the like of the glass fiber are not particularly limited, and any form of glass fiber may be used, but a smaller fiber diameter is preferable because the rigidity of the molded body is improved.
For example, the average fiber diameter of (B) glass fiber is preferably in the range of 7 μm or more and 15 μm or less. (B) The average fiber diameter of the glass fiber is more preferably 8 μm or more, further preferably 9 μm or more, further preferably 14 μm or less, still more preferably 12 μm or less. By being in such a range, higher rigidity can be obtained.
The fiber diameter referred to here is determined by incinerating the resin molded body at a sufficiently high temperature (for example, 400 ° C. or higher) to remove the resin component, and then observing the obtained ash content with a scanning electron microscope to determine the diameter. By measuring, it can be easily measured. Then, in order to eliminate the error, the diameter of at least 100 or more glass fibers can be measured, the average value thereof can be calculated, and the average fiber diameter can be obtained.
(B) As the glass fiber, two or more kinds of glass fibers having different fiber diameters may be blended and used.

(B) The glass fiber is preferably treated with a film forming agent (sometimes referred to as a converging agent) to have a modified surface. Specific examples of the film-forming agent include urethane resin, epoxy resin, and a copolymer resin having at least one acid component.
By modifying the surface of the glass fiber (B) with the film-forming agent, the adhesive strength at the interface with the polyacetal resin (A) can be increased, and high rigidity and high tensile fracture stress can be obtained.
These film forming agents may be used alone or in combination of two or more.

(B) The glass fiber may be surface-modified with a coupling agent. Specific examples of the coupling agent include, but are not limited to, an organic silane compound, an organic titanate compound, an organic aluminate compound, and the like, and all known ones can be used.
These coupling agents may be used alone or in combination of two or more.

Specific examples of the organic silane compound include vinyl triethoxysilane, vinyl-tris- (2-methoxyethoxy) silane, γ-methacryloxypropylmethoxysilane, γ-aminopropyltrimethoxysilane, and γ-aminopropyltriethoxy. Silane, N-β- (aminoethyl) -γ-aminopropyltrimethoxysilane, β- (3,4-epoxycyclohexyl) ethyltriethoxysilane, γ-glycidoxypropylmethoxysilane, γ-mercaptopropyltrimethoxysilane And so on.
Among these, vinyltriethoxysilane, vinyl-tris- (2-methoxyethoxy) silane, γ-methacryloxypropylmethoxysilane, γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, γ-glycid Xipropylmethoxysilane is preferred. Among these, vinyltriethoxysilane and γ-glycidoxypropylmethoxysilane γ-aminopropyltriethoxysilane are preferable from the viewpoint of economy and thermal stability of the resin composition.

Specific examples of the organic titanate compound include tetra-i-propyl titanate, tetra-n-butyl titanate, butyl titanate dimer, tetrastearyl titanate, triethanolamine titanate, titanium acetylacetonate, titanium lactate, and octylene bricol titanate. , Isopropyl (N-aminoethylaminoethyl) titanate and the like.

Specific examples of the organic aluminate compound include acetalkoxyaluminum diisopropyrate and the like.
By using the glass fiber (B) surface-modified with the coupling agent, the creep resistance of the resin molded product tends to be further improved, and the thermal stability of the resin molded product tends to be further improved.

The resin composition of the present embodiment contains (B) glass fiber in a ratio of 10 parts by mass or more and 55 parts by mass or less with respect to 100 parts by mass of (A) polyacetal resin. (B) When the content of the glass fiber is in this range, it is possible to achieve both high rigidity at the time of thin-wall molding and fluidity capable of thin-wall molding. On the other hand, if the amount of (B) glass fiber is less than 10 parts by mass, the rigidity tends to be insufficient when thin-walled molding is performed, and if the amount of (B) glass fiber exceeds 55 parts by mass, the fluidity is impaired and thin-walled molding tends to be impossible. The content of (B) glass fiber is preferably 11 parts by mass or more, more preferably 12 parts by mass or more, preferably 50 parts by mass or less, and more preferably 45 parts by mass with respect to 100 parts by mass of (A) polyacetal resin. It is not less than parts by mass, more preferably 40 parts by mass or less.

<(C) Polyethylene resin>
Specifically, the polyethylene resin (C) used in the resin composition of the present embodiment (in this specification, component (C), may be referred to as (C)) is ultra-low density polyethylene. , Low density polyethylene, high density polyethylene, linear low density polyethylene and the like. Further, an ethylene-based copolymer containing 5% by mass or less of commonomers such as propylene, butene and octene can also be mentioned. Among these, low-density polyethylene is preferable from the viewpoint of the coefficient of friction in sliding with a metal.
These (C) polyethylene resins may be used alone or in combination of two or more.

The polyethylene resin (C) that can be used in the present embodiment preferably contains at least one having a melting point (hereinafter abbreviated as Tm) of 115 ° C. or lower, and more preferably Tm of 110 ° C. or lower. It is preferable to include at least one of them. (C) When at least one Tm of the polyethylene resin is in this range, the friction coefficient is low from the initial stage and the sliding with the metal becomes very stable.
As Tm, 4 to 6 mg of a sample cut out from the resin composition or the resin molded body containing the resin composition was used (preferably sliced by a press or the like), and 10 ° C./ The peak value of endotherm obtained when the temperature is raised in minutes is used.

The weight average molecular weight of the polyethylene resin (C) is not particularly limited, but is preferably 500,000 or less. (C) When the weight average molecular weight of the polyethylene resin is 500,000 or less, a good low coefficient of friction can be obtained from the initial stage of sliding. Further, (A) it is possible to suppress the generation of rheumatism during melt-kneading with the polyacetal resin and chips during melt-kneading after melt-kneading, and it is possible to improve the quality. The weight average molecular weight of the polyethylene resin (C) is preferably 10,000 or more and 400,000 or less, more preferably 15,000 or more and 300,000 or less, further preferably 20,000 or more and 200,000 or less, and most preferably 30,000 or more and 150,000 or less. It is as follows.
These polyethylene resins having a weight average molecular weight of (C) may be used alone or in combination of two or more. Further, among these (C) polyethylene resins, those having a weight average molecular weight of 10,000 or more and 100,000 or less and those having a weight average molecular weight of 200,000 or more and 500,000 or less are used in combination to maintain a good period of low coefficient of friction for a longer period of time. Therefore, a resin composition suitable as a durable material can be obtained, which is preferable.

The resin composition of the present embodiment contains (C) polyethylene resin in an amount of 0.1 part by mass or more and 5 parts by mass or less with respect to 100 parts by mass of (A) polyacetal resin. (C) When the content of the polyethylene resin is in this range, good slidability can be exhibited while maintaining high mechanical properties. The content of the polyethylene resin (C) is preferably 0.5 parts by mass or more, more preferably 0.7 parts by mass or more, further preferably 1.0 part by mass or more, and preferably 4.5 parts by mass or less. It is more preferably 4.0 parts by mass or less, still more preferably 3.5 parts by mass or less.

In the resin composition of the present embodiment, (C) the melt flow rate of the polyethylene resin (ISO1133 compliant, temperature 190 ° C., load 2.16 kg) (hereinafter, simply abbreviated as MFR) is 10 g / 10 minutes or more and 100 g / 10 minutes. It is as follows. (C) When the MFR of the polyethylene resin is in this range, good slidability can be exhibited from the initial stage of sliding. The MFR of the polyethylene resin (C) is preferably 15 g / 10 minutes or more, more preferably 20 g / 10 minutes or more, further preferably 25 g / 10 minutes or more, preferably 90 g / 10 minutes or less, and more preferably 85 g / min. It is 10 minutes or less, more preferably 80 g / 10 minutes or less.

In the resin composition of the present embodiment, the melt flow rate of the (A) polyacetal resin with respect to the melt flow rate of the (C) polyethylene resin (ISO1133 compliant, temperature 190 ° C., load 2.16 kg) (hereinafter, simply abbreviated as MFR). The ratio of is 0.1 or more and 2.0 or less. When the ratio of the MFR of the (A) polyacetal resin to the MFR of the (C) polyethylene resin (MFR of the component (A) / MFR of the component (C)) is in this range, good slidability is good from the initial stage of sliding. Can be obtained and good slidability can be stably maintained for a long period of time. The ratio is preferably 0.2 or more, more preferably 0.3 or more, still more preferably 0.4 or more, preferably 1.8 or less, more preferably 1.6 or less, still more preferably 1.4. It is as follows.

(C) The MFR of the polyethylene resin can be measured in accordance with the above-mentioned standards and conditions.
When the polyethylene resin (C) is contained in the resin composition or the resin molded product, the polyethylene resin (C) is isolated from the resin composition or the resin molded product and measured in accordance with the above-mentioned standards and conditions. This can be confirmed. For example, a resin composition or a part of a resin molded body containing the resin composition is cut out and immersed in hexafluoroisopropanol (hereinafter abbreviated as HFIP) to dissolve the soluble component, and then the insoluble residue is used as a solvent for HFIP and (hereinafter abbreviated as HFIP). By removing B) the glass fiber, (C) the polyethylene resin can be isolated.
If the insoluble residue contains stabilizers, lubricants, etc., separate and measure as necessary.

<Sliding agent>
The resin composition of the present embodiment may contain a sliding agent usually used in a polyacetal resin composition as long as the object of the present invention is not impaired. Examples of the sliding agent include ultra-high molecular weight polyethylene; ethylene-based copolymers containing more than 5% by mass of comonomer such as propylene, butene, and octene; ester-based compounds such as monoesters and diesters; silicon-based compounds; PTFE and the like. Fluorine compounds; higher alcohols; and the like. These sliding agents may be used alone or in combination of two or more.
The amount of the sliding agent added to the resin composition is preferably in the range of 0.01 parts by mass or more and 5 parts by mass or less with respect to 100 parts by mass of the (A) polyacetal resin.

<Stabilizer component>
The resin composition of the present embodiment may contain a stabilizer usually used in a polyacetal resin composition as long as the object of the present invention is not impaired. Examples of the stabilizer include, but are not limited to, antioxidants, formaldehyde, formic acid scavengers and the like. These stabilizers may be used alone or in combination of two or more.

As the antioxidant, a hindered phenolic antioxidant is preferable from the viewpoint of improving the thermal stability of the resin composition. The hindered phenolic antioxidant is not particularly limited, and known ones can be appropriately used.
The amount of the antioxidant added is preferably 0.01 parts by mass or more and 2 parts by mass or less with respect to 100 parts by mass of the (A) polyacetal resin.

Examples of the trapping agent for formaldehyde and formic acid include compounds containing formaldehyde-reactive nitrogen and polymers thereof; hydroxides of alkali metals or alkaline earth metals, inorganic acid salts, carboxylates and the like. Specific examples of the compound containing formaldehyde-reactive nitrogen and its polymer include melamine and a polyamide resin. Specific examples of the hydroxide, inorganic acid salt, and carboxylate of an alkali metal or alkaline earth metal include calcium hydroxide, calcium carbonate, calcium phosphate, calcium silicate, calcium borate, and the like.
The amount of formaldehyde and formic acid trapping agent added is 0.01 parts by mass or more and 3 parts by mass or less with respect to 100 parts by mass of (A) polyacetal resin for the polymer containing formaldehyde-reactive nitrogen, and alkali metal or alkaline soil. The hydroxides, inorganic acid salts, carboxylates and the like of similar metals are preferably in the range of 0.1 parts by mass or more and 1 part by mass or less with respect to 100 parts by mass of the (A) polyacetal resin.

<Other ingredients>
The resin composition of the present embodiment is other than the known glass-based fillers (glass beads, glass balloons, etc.) and glass-based fillers conventionally used in the polyacetal resin composition, as long as the object of the present invention is not impaired. Fillers (talc, wollastonite, mica, calcium carbonate, etc.), conductivity-imparting agents (carbon black, graphite, carbon nanotubes, etc.), colorants (titanium oxide, zinc oxide, iron oxide, aluminum oxide, organic dyes, etc.) ), Various additives such as an ultraviolet absorber, a light stabilizer, and a lubricant can be contained. The amount of these additives is preferably 30 parts by mass or less with respect to 100 parts by mass of the resin composition for the glass-based filler, the filler other than the glass-based filler, and the conductivity-imparting agent. The amount of the agent, the ultraviolet absorber, the light stabilizer, and the lubricant is preferably 5 parts by mass or less with respect to 100 parts by mass of the resin composition. These may be used alone or in combination of two or more.

[Manufacturing method of resin composition]
The resin composition of the present embodiment can be produced by a known method. Specifically, it can be manufactured by mixing raw material components and melt-kneading with a single-screw or multi-screw kneading extruder, a roll, a Banbury mixer, or the like as described below, and molding the mixture. In particular, a twin-screw extruder equipped with a decompression device and a side feeder facility can be preferably used.

The method of mixing the raw material components and melt-kneading is not particularly limited, and a method well known to those skilled in the art can be used. Specifically, a method in which the component (A) and the component (B) are mixed in advance with a super mixer, a tumbler, a V-shaped blender or the like, and then melt-kneaded collectively by a twin-screw extruder, the component (A) is used. Examples thereof include a method in which the component (B) is added from the side feeder in the middle of the extruder while being supplied to the main throat portion of the twin-screw extruder and melt-kneaded. Any of these can be used, but in order to further enhance the mechanical properties of the resin molded product produced from the resin composition of the present embodiment, the component (A) is supplied to the main throat portion of the twin-screw extruder. A method of adding the component (B) from the middle of the extruder while melt-kneading is preferable.
Since the optimum conditions vary depending on the size of the extruder, those skilled in the art can appropriately adjust the conditions. Those skilled in the art can also make various adjustments regarding the screw design of the extruder.

In addition, a chain transfer agent may be added in the mixing of the raw material components and the melt kneading. Preferred examples of the chain transfer agent include methylal, methoxymethylal, dimethoxymethylal, and trimethoxymethylal. As these chain transfer agents, only one kind may be used alone, or two or more kinds may be used in combination.

The component (C) can be added from the side feeder in the middle of the extruder, but it is preferably supplied from the main throat portion.

The resin composition of the present embodiment obtained as described above can be suitably used as a raw material for a resin molded product that requires high fluidity and high rigidity.

[Resin molded product]
The resin molded product in the present embodiment contains the above-mentioned resin composition. Further, the resin molded product of the present embodiment can be produced from the above-mentioned resin composition.
The resin molded body in the present embodiment includes all molded bodies molded by various methods. Specific examples of the molded product include an injection-molded molded product, an extrusion-molded or inflation-molded molded product (sheet, film, strand, pellet, etc.), a blow-molded molded product, and the like.

The molding method for obtaining the resin molded body in the present embodiment is not particularly limited, and a known molding method can be used. Specifically, extrusion molding, injection molding, vacuum molding, blow molding, injection compression molding, decorative molding, other material molding, gas assisted injection molding, foam injection molding, low pressure molding, ultra-thin injection molding (ultra-high speed injection). It can be molded by any of molding methods such as molding) and composite molding in a mold (insert molding, outsert molding). The resin molded product thus obtained can simultaneously satisfy excellent thin-wall moldability and high slidability.

The resin molded product of the present embodiment can be used in applications that require excellent thin-wall moldability and high slidability. Further, since the resin molded product of the present embodiment can simultaneously satisfy excellent thin-wall moldability and high slidability, the thickness can be 2 mm or less, and the thickness can be 1.5 mm or less, further 1 It can be 0.0 mm or less.

<Use of resin molded product>
The resin molded product of the present embodiment can be suitably used as an automobile part, and in particular, can be suitably used as a part that plays a role as a gear or a pulley that comes into contact with other members.
In addition to the above-mentioned parts, the resin molded product of the present embodiment can be applied to known uses of the polyacetal resin. Specifically, mechanical parts such as cams, sliders, levers, arms, clutches, felt clutches, idler gears, rollers, rollers, key stems, key tops, shutters, reels, shafts, joints, shafts, bearings, guides, etc. ; Outsert molded resin parts, insert molded resin parts, chassis, trays, side plates, automobile parts, represented by door locks, door handles, window regulators, window regulator wire drums, speaker grills, glass holders, carrier plates, etc. Parts around doors; Seat belt peripheral parts such as seat belt slip rings and press buttons; Parts such as combination switch parts, switches, clips, etc. For gasoline tanks, fuel pump modules, valves, gasoline tank flanges, etc. Typical fuel parts, printers, office automation equipment parts such as copying machines; Video equipment parts such as digital video cameras and digital cameras; CDs, DVDs, Blu-ray (registered trademark) Discs, and other optical equipment. Disk drive; Music, video or information equipment such as navigation systems and mobile personal computers, communication equipment parts such as mobile phones and facsimiles; Electrical equipment parts; Electronic equipment parts, etc. ..
In addition, as other applicable items, the pen tip of writing tools, mechanical parts for inserting and removing the core; washstands, drains, drain plug opening and closing mechanical parts; cord stoppers for clothing, adjusters, buttons; nozzles for watering, watering Hose connection joints; building supplies that support stair railings and flooring materials; toys, fasteners, chains, conveyors, buckles, sporting goods, vending machines (opening and closing lock mechanism, product discharge mechanism parts), furniture, musical instruments , Housing equipment parts, key tops and key stems of personal computers, etc.

Hereinafter, the present embodiment will be specifically described with reference to Examples , Reference Examples and Comparative Examples, but the present embodiments are not limited to these Examples and Comparative Examples as long as the gist thereof is not exceeded.

The (A) polyacetal resin, (B) glass fiber, and (C) polyester resin used in each Example , Reference Example, and Comparative Example were prepared or prepared as follows.

(A) Polyacetal resin A twin-screw self-cleaning type polymerizer with a jacket that can pass a heat medium (L / D = 8 (L: distance (m) from the raw material supply port to the discharge port of the polymerizer, D: The inner diameter (m) of the polymerization machine. The same shall apply hereinafter)) was adjusted to 80 ° C. To this polymerization machine, trioxane, 1,3-dioxolane as a comonomer, and methylal as a chain transfer agent were added. At that time, the amounts were adjusted so as to have the comonomer concentration (mol% of ethoxy units with respect to the total units) and MFR shown in Tables 1 and 2.
In Example 13, 1,3-dioxolane as a comonomer was not added.
Further, boron trifluoride di-n-butyl etherate as a polymerization catalyst was continuously added to the polymerization machine in an amount of 1.5 × 10 ^-5 mol with respect to 1 mol of trioxane to carry out polymerization.
The polyacetal copolymer discharged from the polymerization machine was put into a 0.1% aqueous solution of triethylamine to inactivate the polymerization catalyst. Then, the polyacetal copolymer in which the polymerization catalyst was deactivated was filtered through a centrifuge and dried. The dried polyacetal copolymer is supplied to a twin-screw extruder with a vent, and 0.5 parts by mass of water is added to the polyacetal copolymer that is in a molten state in the extruder with respect to 100 parts by mass of the polyacetal copolymer. After the addition, the conditions of the extruder were set to a temperature of 200 ° C. and a residence time of 7 minutes, and the unstable terminal portion (-(OCH ₂ ) n-OH) of the polyacetal copolymer was decomposed and removed.
0.3 parts by mass of triethylene glycol-bis- [3- (3-t-butyl-5-methyl-4-hydroxyphenyl) -propionate] as an antioxidant was added to the polyacetal copolymer in which the unstable end portion was decomposed. It was added and extruded as a strand from the die portion of the extruder while being devolatile under the condition of a vacuum degree of 20 Torr in an extruder with a vent, and pelletized.
In this way, the (A) polyacetal resin was obtained.

(B) Glass fiber (B) As the glass fiber, "T-651H" manufactured by Nippon Electric Glass was used.

(C) Polyethylene resin (C) As the polyethylene resin, low density polyethylene (LDPE) was adjusted and used so as to have each MFR.

Further, in each Example , Reference Example and Comparative Example, a resin composition and a resin molded product were produced with the compounding compositions shown in Tables 1 and 2 according to the following procedure.

(A) The ratio of the screw length L to the extruded screw diameter D (L / D) = 48 (number of barrels 12), side feeders are provided in the 6th and 8th barrels, and a vacuum vent is provided in the 11th barrel. The same-direction rotary twin-screw extruder (TEM-48SS extruder manufactured by Toshiba Machine Co., Ltd.) provided was used. The first barrel was water-cooled, the second to fifth barrels were set to 220 ° C., and the sixth to twelfth barrels were set to 180 ° C.
The screw used for extrusion has the following design. A flight screw (hereinafter abbreviated as FS) is placed at the position of the 1st to 4th barrels, and two kneading discs (hereinafter abbreviated as RKD) having a feeding ability are arranged at the position of the 5th barrel, and kneading without a feeding ability. Two discs (hereinafter abbreviated as NKD) and one kneading disc (hereinafter abbreviated as LKD) having a feeding ability in the opposite direction were arranged in this order. FS was placed at the positions of the 6th to 8th barrels, RKD and NKD were placed one by one at the positions of the 9th barrel, and FS was placed at the positions of the 10th to 11th barrels.
(A) Polyacetal resin and (C) polyethylene resin are charged from the main throat portion of the twin-screw extruder, (B) glass fiber is supplied from the side feeder of the sixth barrel, the screw rotation speed is 150 rpm, and the total extrusion amount is set. Was extruded (melt-kneaded) at 70 kg / h to prepare a resin composition.

(B) Molding Next, using an injection molding machine (EC-75NII, manufactured by Toshiba Machine Co., Ltd.), the prepared resin composition was set to a cylinder temperature setting of 205 ° C., an injection time of 35 seconds, and a cooling time of 15. By molding under the injection conditions of seconds, a resin molded body in the shape of a small tensile test piece compliant with ISO 294-2 was obtained. The mold temperature at this time was 90 ° C.
Similarly, a thin resin molded body having a small tensile test piece shape and a thickness of 1 mm was obtained.

Then, various evaluations were performed on the resin molded bodies of Examples and Comparative Examples according to the following procedure. The results are shown in Tables 1 and 2.

(1) Melt flow rate of resin composition The obtained resin molded product was cut into small pieces and made into pellet-shaped samples. Melt flow rate (g / 10 min) was measured for this pelletized sample according to ISO1133. At this time, the temperature was 190 ° C. and the load was 2.16 kg.

(2) Melt flow rate of (A) polyacetal resin A pellet-shaped sample was measured for melt flow rate (g / 10 minutes) in accordance with ISO1133. At this time, the temperature was 190 ° C. and the load was 2.16 kg.

(3) Melt flow rate of (C) polyethylene resin A pellet-shaped sample was measured for melt flow rate (g / 10 minutes) in accordance with ISO1133. At this time, the temperature was 190 ° C. and the load was 2.16 kg.

(4) Spiral flow length (SFD) (0.5 mm thickness)
Using an injection molding machine (ROBOSHOT α-50iA manufactured by FANUC Corporation), the cylinder temperature is set to 200 ° C., the mold temperature is set to 80 ° C., and the injection pressure is 80 MPa using a 0.5 mm thick SFD mold. SFD was evaluated.
The longer the SFD value, the better the liquidity. It was judged that thin resin molding was possible when the SFD was 3 cm or more, and the evaluation of the thin resin molding accuracy was set to "Δ". It was judged that the SFD was 4 cm or more, which was good for thin resin molding, and the evaluation of the thin resin molding accuracy was evaluated as "◯". When the SFD was 5 cm or more, it was judged to be excellent for thin resin molding, and the evaluation of thin molding accuracy was evaluated as "◎". It was judged that thin resin molding was impossible when the SFD was less than 3 cm, and the evaluation of the thin resin molding accuracy was set to "x".

(5) Bending elastic modulus Using a resin molded body in the shape of a small tensile test piece molded in accordance with the ISO 294-2, a bending test in accordance with ISO 178 was performed and the bending elastic modulus was measured. The pushing speed was 2 mm / min.
The higher the flexural modulus, the better the rigidity, and it is easy to obtain the rigidity even in a thin resin molded body. It was judged that the rigidity was good when the flexural modulus was 4500 MPa or more.

(6) Sliding property [Sliding test]
A ball-on-disk type reciprocating friction and wear tester (AFT-15MS type, manufactured by Toyo Precision Co., Ltd.) was used. Sliding test using the 1 mm thick thin resin molded body under the conditions of a load of 19.6 N, a linear speed of 30 mm / sec, a reciprocating distance of 20 mm, and the number of reciprocations of 5,000 times in an environment of 23 ° C. and 50% humidity. Was done. As the ball, a SUS304 ball (a ball having a diameter of 5 mm) was used.
(6-1) Sliding property (initial)
It was evaluated by the friction coefficient of the 100th sliding start of the sliding test.
The lower the coefficient of friction, the better, and if the coefficient of friction was 0.25 or less, it was judged that the slidability was good.
(6-2) Sliding (low temperature type temperature)
The sliding test was carried out in the same manner except that the mold temperature at the time of molding the 1 mm thick thin resin molded product was set to 60 ° C., and the evaluation was made based on the friction coefficient at 5,000 times.
The lower the coefficient of friction, the better, and if the coefficient of friction was 0.30 or less, it was judged that the slidability was good.
(6-3) Sliding (stability)
The evaluation was made by the fluctuation range obtained by subtracting the minimum value from the maximum value of the friction coefficient from the 100th time to the 5,000th time in the sliding test.
The lower the fluctuation range, the better the stability, and when it was 0.05 or less, it was judged that the slidability was good.
(6-4) Sliding (high load)
The above test was carried out in the same manner except that the load was set to 49.0 N, and the evaluation was made based on the coefficient of friction at 5000 times.
The lower the friction coefficient, the better the slidability, and when the friction coefficient was 0.25 or less, it was judged that the slidability was good.

From Tables 1 and 2, (A) 100 parts by mass of polyacetal resin, (B) 10 parts by mass or more and 55 parts by mass or less of glass fiber, and (C) 0.1 parts by mass or more and 5 parts by mass or less of polyethylene resin are included. , (C) Polyethylene resin melt flow rate (ISO1133 compliant, temperature 190 ° C., load 2.16 kg) is 25 g / 10 minutes or more and 100 g / 10 minutes or less, and (A) for the polyethylene resin melt flow rate. ) The resin molded body containing the resin composition according to the example in which the ratio of the melt flow rate of the polyacetal resin (ISO1133 compliant, temperature 190 ° C., load 2.16 kg) is 0.2 or more and 2.0 or less is excellent thin-walled. It can be seen that the moldability and the excellent slidability are satisfied at the same time.

The resin composition and the resin molded body of the present invention have industrial applicability in various fields in which a polyacetal resin is preferably used, particularly in the field of structural parts where fluidity and rigidity are required.

Claims (8)

It contains (A) 100 parts by mass of polyacetal resin, (B) 10 parts by mass or more and 55 parts by mass or less of glass fiber, and (C) 0.1 parts by mass or more and 5 parts by mass or less of polyethylene resin.
The melt flow rate (ISO1133 compliant, temperature 190 ° C., load 2.16 kg) of the polyethylene resin (C) is 25 g / 10 minutes or more and 100 g / 10 minutes or less.
The ratio of the melt flow rate of the polyacetal resin (ISO1133 compliant, temperature 190 ° C., load 2.16 kg) to the melt flow rate of the polyethylene resin is 0.2 or more and 2.0 or less.
A resin composition characterized by this. The resin composition according to claim 1, wherein the melt flow rate (ISO1133 compliant, temperature 190 ° C., load 2.16 kg) is 8 g / 10 minutes or more. The resin composition according to claim 1 or 2, wherein the melt flow rate of the polyacetal resin (A) is 10 g / 10 minutes or more and 100 g / 10 minutes or less. The resin composition according to any one of claims 1 to 3, wherein the polymonomer concentration of the (A) polyacetal resin is 1.5 mol% or less. The resin composition according to any one of claims 1 to 4, wherein the polymonomer concentration of the (A) polyacetal resin is 0 mol% or more and 1.0 mol% or less. A resin molded product comprising the resin composition according to any one of claims 1 to 5. The resin molded product according to claim 6, which has a thickness of 1 mm or less. The resin molded product according to claim 7, which is used as a part for an electric device or a part for an electronic device.