JP2001114980A - Polyacetal resin composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polyacetal resin composition useful as an injection molding material having a balance of rigidity, impact resistance and fluidity. SOLUTION: A difference in solubility parameter between (A) a polyacetal resin and (B) a polyacetal polymer (b1) and the polyacetal polymer (b1) is 0.5 (cal / cm ³ ) ^1/2 or less. A polyether block copolymer with the polymer (b2) and a filler (C) are blended.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to rigidity, impact resistance,
The present invention relates to a polyacetal resin composition useful as a material for injection molding having a good balance of fluidity.

[0002]

2. Description of the Related Art Polyacetal resins are excellent in mechanical properties, friction and abrasion resistance, chemical resistance and heat resistance. It is used for various molded products such as parts. However, in recent years, there are cases where higher properties are required in applications where a polyacetal resin is used. In the field of injection molding, in particular, there is a demand for high impact resistance, high rigidity, and high fluidity. The development of a polyacetal resin that has been removed is awaited. Regarding the high performance of polyacetal resin, addition of inorganic substances, polymer blend,
Attempts have been made to increase the functionality according to various uses, including modification such as copolymerization. For example, by increasing the crystallization rate during cooling, the time of the molding process (molding cycle) can be shortened, and the productivity (economic) of the molded product can be increased. It is known that inorganic fillers such as boron nitride and talc are added in order to obtain. However, this method can provide a material having high rigidity, but has a disadvantage that toughness is impaired. As a general method to prevent the decrease in toughness, there is a method using high-molecular-weight polyacetal.However, there is a problem in that the flowability decreases, and rigidity, impact resistance, and flowability can be balanced at a high level. Have difficulty. In addition, an elastomer such as polyurethane can be blended with polyacetal to obtain a polyacetal resin composition having improved impact resistance. However, this method also has a problem that rigidity is reduced. Filling with an elastic modulus filler or the like causes a decrease in fluidity and toughness, and it is also difficult to balance rigidity, impact resistance and fluidity at a high level with this method.
In addition, a large number of block copolymers in which a crystalline polymer and an amorphous polymer are linked by a covalent bond have been proposed in the past with the expectation that the above-mentioned object can be achieved. Japanese Patent Publication No. 35-2194 proposes to obtain a block copolymer of polyacetal by polymerizing formaldehyde in the presence of a polymer such as polytetramethylene glycol and vinyl acetate copolymer. However, although the block copolymer has slightly improved toughness, the strength is significantly reduced. In Japanese Patent Publication No. 4-6583, an aba-type triblock copolymer elastomer composed of a crystalline polyacetal portion and an amorphous thermoplastic polymer having a degree of crystallinity of 30% or less is blended with polyacetal. Attempts have been made to achieve both strength and toughness. However, this method only finely disperses a soft polymer having a low crystallinity, so that the surface rigidity of the molded product is greatly reduced,
Applications are limited. In addition, many attempts have been made to lower the crystallization rate and the degree of crystallinity and to increase the toughness by adding a plasticizer or modifying by copolymerization. However, especially in the latter modification that lowers crystallinity, heat resistance typified by the melting point is reduced, and mechanical strength such as rigidity and surface hardness has to be sacrificed.

[0003]

In view of the above-mentioned problems, the present inventors diligently take measures to control not only the degree of crystallization and the crystallization rate of a crystalline polymer but also the form of a crystalline lamella. As a result of repeated studies, the use of the crystalline polymer and a specific polyether-based block copolymer, in particular, a block copolymer obtained by combining a soft segment having a high affinity with the crystalline polymer, enables the rigidity to be improved. ,
The present inventors have found that a polyacetal resin composition useful as an injection molding material having a good balance between impact resistance and fluidity can be obtained, thereby completing the present invention. That is, the present invention provides (A) a polyacetal resin (B) a polyacetal polymer (b1) and a polyether-based polymer.
a polyether block copolymer (b1) comprising the polyether block copolymer (b2) and a filler (C), and constituting the polyether block copolymer (B); and a polyether polymer.
(b2) a polyacetal resin composition having a difference in solubility parameter of 0.5 (cal / cm ³ ) ^1/2 or less (hereinafter referred to as the first invention); and (A) a polyacetal resin (B) Polyacetal polymer (b1) and polyether polymer
The polyether block copolymer with (b2) and the filler (C) are filled, and the spherulite region having a diameter of 3 μm or more by molding is 10%.
A polyacetal resin composition (hereinafter referred to as a second invention) characterized by being capable of forming the following molded article, and (A) a polyacetal resin (B) a polyacetal polymer (b1) and a polyether-based polymer
a polyether-based block copolymer with (b2), and (C) a filler, wherein the resin component has a crystallinity of 65 to 90%, a flexural modulus of 1500 MPa or more, as determined from reflection wide-angle X-ray scattering, A polyacetal resin composition having a notched Izod impact strength of at least 80 J / m, a melt viscosity measured at 190 ° C. and a shear rate of 1216 sec ^-1 of 250 Pa · s or less (hereinafter, referred to as
This is referred to as the third invention of the present application).

[0004]

BEST MODE FOR CARRYING OUT THE INVENTION The components constituting the composition of the present invention and the characteristics of the present invention will be described below. [Polyacetal resin (A)] Polyacetal resin (A)
Is a polymer compound having an oxymethylene group (—CH ₂ O—) as a main constituent unit, and is a polyacetal homopolymer,
Polyacetal copolymers containing other comonomer units besides oxymethylene groups are included. In the copolymer, the comonomer unit contains an oxyalkylene unit having about 2 to 6 carbon atoms (preferably about 2 to 4 carbon atoms). The ratio of the oxymethylene group and the comonomer unit of the polyacetal resin (A) is, for example, the former / the latter = 80/20
100100/0 (mol%), preferably 90 / 10-100 / 0
(Mol%), more preferably in the range of about 95/5 to 100/0 (mol%). The polyacetal copolymer may be a copolymer composed of two or more comonomers. The terminal group of the polyacetal resin (A) may be stabilized by esterification with a carboxylic acid such as acetic acid or propionic acid, and the terminal group may contain a hydroxyl group. Not restricted. Melt index of polyacetal resin (A) (M
Although there is no particular limitation on I), for example, a temperature of 190 ° C. and a load
At 2.16 kg, 10 to 100 g / 10 min, preferably 30 to 100 g
A time of / 10 minutes is suitable for obtaining a highly fluid composition.

[Polyether block copolymer (B)]
The polyether-based block copolymer of the present invention is a block copolymer composed of a polyacetal polymer (b1) and a polyether-based polymer (b2) having a high affinity for the polyacetal polymer (b1). The polymer (b1) acts as a hard component of the block copolymer, and the polyether-based polymer (b2) acts as a soft component.
The block copolymer may be prepared by any method such as a polymerization method and a polymer reaction. For example, it can be easily obtained by reacting the reactive end groups of the polyacetal polymer (b1) and the polyether polymer (b2) with the polyisocyanate compound (b3). Hereinafter, each component constituting the polyether-based block copolymer (B) will be described.

[Polyacetal polymer (b1)] The polyacetal polymer (b1) includes a polyacetal homopolymer and a polyacetal copolymer. The comonomer unit has about 2 to 6 carbon atoms (preferably 2 to 4 carbon atoms).
Oxyalkylene units (for example, an oxyethylene group (—CH ₂ CH ₂ O—), an oxypropylene group, an oxytetramethylene group, etc.). The ratio of the oxymethylene unit and the comonomer unit (particularly, C ₂ -C ₄ oxyalkylene unit) in the polymer (b1) is in a range where the polymer (b1) does not impair the crystallinity, for example, the former / the latter = 90/10 ~ 100
/ 0 (mol%), and the content of oxymethylene unit is usually more than 93 mol% and 100 mol% or less. The polyether block copolymer (B) of the present invention needs to be efficiently reacted with a polyisocyanate compound in order to obtain excellent properties, and the polyacetal polymer (b1) has many hydroxyl groups at the molecular chain terminals. In the polyacetal polymer (b1), the concentration of hydroxyl groups based on the entire terminal groups is preferably 70 mol% or more from the viewpoint of appearance of mechanical properties. The concentration of terminal hydroxyl groups of the polyacetal polymer can be adjusted by adding water or a polyhydric alcohol to the polymerization step.

[Polyether-based polymer (b2)] A feature of the present invention resides in that a polyether-based polymer having a high affinity for a polyacetal polymer is used as a soft component. In selecting the polyether-based polymer (b2), a difference (Δδ) in solubility parameters can be used as a parameter indicating affinity with the polyacetal polymer (b1). Here, various methods for calculating the solubility parameter have been proposed. DWKrevelen, "Properties of Polymers", Elsev
ier, Amsterdam, 1976. That is, the solubility parameter [delta], is the ratio of the molar attraction constant F and the molar volume V of the monomer units constituting the polymer, F can be calculated as the sum of the contribution F _i from each atomic group. δ = F / V = ΣF _i / V (cal / cm ³ ) ^1/2 The difference between the solubility parameters (Δδ) is calculated from the following equation. Δδ = | δ _b1 −δ _b2 | Here, δ _b1 and δ _b2 represent the solubility parameters of the polyacetal polymer (b1) and the polyether polymer (b2), respectively. The first invention of the present application relates to a polyacetal polymer (b
The difference (Δδ) between the solubility parameter and 1) is 0.5 (cal / c)
m ³ ) A polyether-based polymer (b2) exhibiting ^1/2 or less is selected, and a polyether-based block copolymer (B) composed of the polyacetal polymer (b1) and the polyether-based polymer (b2) Is used. Furthermore, in consideration of the reactivity with the polyisocyanate compound (b3), it is necessary to have a functional group that reacts with the isocyanate group at the molecular terminal of the polyether polymer. Polyethylene glycol is exemplified as a polyether-based polymer satisfying these two conditions. The molecular weight of the polyether polymer is 300 to 70,000 in number average molecular weight, preferably 500 to
It can be selected from the range of about 50,000, more preferably about 1,000 to 20,000. When the number average molecular weight exceeds 70,000, it is usually disadvantageous from the viewpoints of economy, production handling, and the like.

[Polyisocyanate (b3)] As the polyisocyanate, aromatic polyisocyanate, araliphatic polyisocyanate, alicyclic polyisocyanate,
Aliphatic polyisocyanates and the like can be used. Diisocyanates are widely used as polyisocyanates.

Examples of the aromatic polyisocyanate include diisocyanates [m- or p-phenylene diisocyanate, 2,4- or 2,6-tolylene diisocyanate, 4,4'-diphenyl diisocyanate, 1,5-naphthalene diisocyanate, 4,4'-diphenylmethane diisocyanate, 4,4'-diphenyl ether diisocyanate, etc.), polyisocyanate (triphenylmethane-
4,4 ', 4 "-triisocyanate]. Examples of the araliphatic polyisocyanate include diisocyanates [1,3- or 1,4-xylylene diisocyanate, 1,3- or 1,4-]. Bis (1-isocyanate-1-
Methylethyl) benzene and the like, and polyisocyanates [1,3,5-triisocyanatemethylbenzene and the like]. Examples of the aliphatic polyisocyanate include diisocyanates [1,4-cyclohexane diisocyanate, isophorone diisocyanate, 4,4′-methylenebis (cyclohexyl isocyanate), 1,4-bis (isocyanatomethyl) cyclohexane, etc.], polyisoisocyanate [1 , 3,5-Triisocyanatocyclohexane, 1,3,5-trimethylisocyanatecyclohexane, 2- (3-isocyanatopropyl) -2,5-
Di (isocyanatomethyl) -bicyclo (2,2,1) heptane]. Among these polyisocyanates, diisocyanates (for example, aromatic diisocyanates such as tolylene diisocyanate and 4,4′-diphenylmethane diisocyanate, alicyclic diisocyanates such as isophorone diisocyanate, and aliphatic diisocyanates such as hexamethylene diisocyanate) can be used. preferable.

The polyacetal polymer (b1) and the polyether-based polymer (b2) are combined with a polyisocyanate compound (b3)
In order to obtain the polyether-based block copolymer (B) by reacting in the above, the proportion of each component (b1), (b2), and (b3) can be selected according to the type and molecular weight of each component, and usually ( The ratio of the hydroxyl group of the component (b1) and the component (b2) to the isocyanate group of the component (b3) is OH / NCO = 0.8 / 1 to 1.2 / 1 (molar ratio).
It is about. The ratio between the polyacetal polymer (b1) and the polyether-based polymer (b2) is calculated as follows: component (b1) / (b2)
Component can be selected from the range of 75/25 to 25/75. The polyether-based block copolymer (B) comprises the component (b1), (b)
It can be obtained by reacting component 2) and component (b3) in the presence or absence of a solvent. As the solvent, various organic solvents inert to the reaction, for example, benzene, toluene,
Examples thereof include aromatic hydrocarbons such as xylene, nitro compounds such as nitrobenzene, halogen compounds such as chlorobenzene and dichlorobenzene, ethers such as anisole, nitriles such as acetonitrile and benzonitrile, dimethylformamide, and dimethylsulfoxide. The reaction system using the solvent may be a homogeneous system or a heterogeneous system. The reaction temperature is, for example, 130 to 200 ° C,
Preferably it is about 150 to 190 ° C. After completion of the reaction, the solvent is removed to obtain the polyether block copolymer (B). The reaction of the above components in the absence of a solvent can be performed in a melt-kneading system.
Melt kneading is performed at a suitable temperature at which a homogeneous melt is formed, for example,
It can be carried out at a temperature in the range of 160 to 230 ° C, preferably about 170 to 220 ° C. As the apparatus, a known apparatus can be used, and any method such as a continuous system and a batch system can be used. The blending ratio of the polyether block copolymer (B) is 10 to 5 in 100 parts by weight in total with the polyacetal resin (A).
0 parts by weight, preferably 20 to 35 parts by weight. If the amount of the polyether block copolymer (B) is too small, the impact strength is low, and if it exceeds 50 parts by weight, the rigidity and the fluidity may be greatly reduced.

[Filler (C)] As the filler (C), powdery, granular, plate-like or fibrous fillers can be used alone or in combination of two or more. As the particulate filler, for example, calcium carbonate, magnesium carbonate, silicon carbide, boron carbide, magnesium oxide, titanium oxide, alumina,
Examples include calcium silicate, aluminum silicate, silica, carbon black, and glass beads. As the plate-like filler, mica, talc, silicate compounds such as clay,
Glass flakes and the like are mentioned as examples. Examples of the fibrous filler include whiskers such as potassium titanate, glass fibers, carbon fibers, borate fibers, boron nitride fibers, and silica / alumina fibers. The shape of the filler is not particularly limited in the polyacetal resin composition of the present invention, but it is preferable to use a plate-like filler and a fibrous filler from the viewpoint of further improving rigidity by controlling the crystal arrangement. The mixing ratio of the filler depends on the resin component (component (A) and component (A)
(B) 0.1 to 20 parts by weight,
Preferably, it can be selected from the range of about 1 to 15 parts by weight. The second invention of the present application comprises a polyacetal resin (A), a polyether-based block copolymer (B), and a filler (C) as described above, and a spherulite region having a diameter of 3 μm or more and 10% or less is formed by molding. A polyacetal resin composition characterized by being capable of forming a product. It is known that a polyacetal resin, which is one of the highly crystalline resins, usually has a spherulite structure when injection molded. However, the spherulite structure is not always suitable for mechanical properties such as impact resistance and stiffness. The further improvement is expected. In fact, in polypropylene composites,
In some cases, polypropylene crystals are arranged in a specific structure to significantly improve mechanical properties. In the case of a polyacetal resin, a great improvement in mechanical properties is expected by controlling the crystal structure, but the relationship between the crystal structure and the mechanical properties, a method of controlling the crystal structure, and the like have not yet been established. On the other hand, when the polyether block copolymer and the filler as described above are blended with the polyacetal resin, and the resin composition is formed into an injection molded product, the diameter is 3 μm or more as observed by a scanning electron microscope (SEM). When a molded article having an area occupied by spherulites of 10% or less can be formed, a remarkable improvement in mechanical properties, that is, a remarkable increase in impact strength without sacrificing much rigidity is exhibited. In general, simply adding a filler to polyacetal does not improve the impact strength, and the spherulite structure has a smaller diameter.
It has a diameter of about 5 μm at most, even if a filler having a nucleating agent action is compounded. The improvement of the mechanical properties of the composition of the present invention is attributable to the crystal structure in which spherulites having a diameter of 3 μm or more are substantially not observed. It is presumed that the property has improved. In the present invention, the spherulite structure is observed by the following method. A dumbbell-type injection molded product having a thickness of 3 mm is prepared, and a plane parallel to the resin flow direction is cut at a substantially parallel center with a microtome to form a smooth surface. The surface is immersed in concentrated sulfuric acid for 30 seconds at room temperature (23 ° C.), and then immersed in 30% sulfuric acid for 30 minutes to perform an etching process. After sufficiently washing with water to remove sulfuric acid, drying is performed. Normal SEM
A platinum palladium film is coated by sputtering performed for observation to obtain a sample for SEM observation. The SEM observation may be performed by a general apparatus, but is performed at an acceleration voltage of 5 kV, and an appropriate magnification is selected from the range of 600 to 2000 times depending on the size of the spherulite structure.

Further, the third invention of the present application relates to a polyacetal resin (A) and a polyether block copolymer as described above.
(B) and (C) a filler having a crystallinity of 65 to 90% and a flexural modulus of 15 determined by reflection wide-angle X-ray scattering.
Not less than 00MPa, notched Izod impact strength is more than 80J / m, melt viscosity measured at 190 ° C and shear rate 1216sec ^-1
It is a polyacetal resin composition characterized by being 250 Pa · s or less. Here, the crystallinity is determined by the following method using reflection wide-angle X-ray diffraction. That is, the measurement sample is melted on a hot plate at a temperature of 190 ° C. and solidified on another hot plate adjusted to a temperature of 70 ° C. Under the output condition of 40kV / 140mA, slit width 0.5
Observe the scattering intensity monochromatized by the monochromator under the condition of degree. Based on the (100) crystal plane peak area (Ac) and the compound area (Aa) of the amorphous halo portion, the degree of crystallization was calculated as [Ac
/ (Ac + Aa)]. Generally, an elastomer is blended as a method of improving the impact strength of a crystalline resin.In this case, the impact resistance can be improved, but the addition of the elastomer causes a decrease in the crystallinity of the entire resin component. , The rigidity decreases. The method of the present invention in which a specific polyether-based block copolymer and a filler are added does not cause a decrease in crystallinity of the entire resin component as in the case of blending an elastomer, that is, without sacrificing much rigidity. Improves impact resistance. The crystallinity of the polyacetal resin alone depends on the degree of polymerization and molding conditions, but is usually 75
However, since the polyacetal resin composition of the present invention contains a specific polyether block copolymer, the degree of crystallinity can be maintained at 65% or more. Accordingly, the notched Izod impact strength is improved to 80 J / m or more, and in most cases to 100 J / m or more, while maintaining a low stiffness and a flexural modulus of 1500 MPa or more. By the way,
Polyacetal Notched Izod Impact Strength 100J
When a urethane elastomer is blended in order to attain a pressure of at least / m, the flexural modulus is significantly reduced to about 800 MPa. As a method of improving the impact resistance, there is a method of using a polymer having a high molecular weight, but in this case, fluidity is sacrificed. The resin composition of the present invention can be used at 190 ° C. and a shear rate of 1216 sec by selecting a polyacetal having an appropriate molecular weight or viscosity.
Despite having an extremely high fluidity with a melt viscosity measured at ^-1 of 250 Pa · s or less, it exhibits the above-mentioned high impact resistance. It is well known that the incorporation of a filler increases the elastic modulus, but in that case, the impact resistance is reduced. As an example, 10% by weight of calcium carbonate in polyacetal resin
Just adding it reduces the notched Izod impact strength by half. Despite the fact that the resin composition of the present invention contains a filler, the notched Izod impact strength is 80 J /, while maintaining a flexural modulus of 1500 MPa or more, due to the effect of the specific polyether-based block copolymer. m or more, and in most cases 100J / m or more. As described above, the polyacetal resin composition of the present invention has rigidity and impact resistance by selecting a polyacetal having an appropriate molecular weight or viscosity and adding a specific polyether-based block copolymer and a filler thereto. In addition, it is possible to provide a material having a good fluidity.

The polyacetal resin composition of the present invention may contain, if necessary, various additives such as antioxidants, heat stabilizers, coloring agents such as dyes and pigments, release agents, antistatic agents,
You may add an ultraviolet absorber etc. by 1 type or in combination of 2 or more types.

[0014]

By blending a specific polyether block copolymer and a filler into a polyacetal resin,
It is possible to provide a polyacetal resin composition useful as an injection molding material having a balance of rigidity, impact resistance, and fluidity.

[0015]

EXAMPLES Hereinafter, the present invention will be described specifically, but the present invention is not limited to these examples. [Production Example 1] Production of polyacetal polymer (b1) 90 parts by weight of trioxane, 10 parts by weight of dioxolane, and 100 ppm of ethylene glycol based on the whole system were charged into a stainless steel reaction vessel, and polymerization temperature was measured using trifluoromethanesulfonic acid as a catalyst. It was bulk polymerized at 70 ° C. The resulting polymerization flakes were pulverized, washed with distilled water and acetone, and dried under reduced pressure. The amount of oxymethylene units with respect to all oxyalkylene units in the obtained polymer was determined to be 96.9 mol% by ¹ H-NMR measurement using hexafluoroisopropanol-d2 as a measuring solvent, and the melting point was determined by DSC measurement at a heating rate of 10 ° C./min. 160 ° C, crystallinity 83
% By weight. Further, the terminal hydroxyl group was acetylated with acetic anhydride, and the amount of hydroxyl terminal was determined by ¹ H-NMR measurement. The result was 278 mol / kg, and the ratio of hydroxyl terminal to all terminal groups was 98%.

Production Example 2 Production of Polyether Block Copolymers (B-1 and B-2) Polyethylene glycol (number average molecular weight 3000) was used as the polyether polymer (b2). In order to bond the polyacetal polymer (b1) obtained in Production Example 1 and the polyethylene glycol (b2), a reaction between a hydroxyl group at a polymer terminal and a bifunctional isocyanate compound (b3) was used. That is, the polymer (b1) and polyethylene glycol (b2) were dissolved in nitrobenzene at a concentration of 30% by weight in the ratio shown in Table 1, and the number of terminal hydroxyl groups of the polymer (b1) and polyethylene glycol (b2) was determined. 0.5 mol of 4,4-
Add diphenylmethane diisocyanate (b3), 1
The reaction was performed at 70 ° C. for 90 minutes. After the completion of the reaction, the reaction mixture was washed with cold methanol, and then dried under reduced pressure to obtain a polyether block copolymer. Table 1 shows the properties of the obtained polyether-based block copolymer.

[0017]

[Table 1]

[Production Example 3] Production of polyether block copolymer (B-3) (comparative product) Polyether polymer used in polyether block copolymer (B-1) of Production Example 2 Polyethylene glycol (b2) with polypropylene glycol (number average molecular weight 3000)
The procedure was the same as that for the polyether block copolymer (B-1).

[Production Example 4] Production of polyether random copolymer (comparative product) 37.7 parts by weight of trioxane and 62.5 parts by weight of dioxolane were charged into a stainless steel reaction vessel, and a polymerization temperature of 70 ° C using trifluoromethanesulfonic acid as a catalyst. Was used for bulk polymerization. The resulting polymer was washed with diethyl ether, dried under reduced pressure, and acetylated at the end groups with acetic anhydride. The ratio of oxymethylene units to all oxyalkylene units in the obtained polymer was 70 mol% from NMR measurement. The number average molecular weight was 28,000.

Examples 1 to 5 and Comparative Examples 1 to 4 Polyacetal resin (MI = 75 g / 10 min), polyether block copolymer (B-1, B-2, B-3), polyether random The copolymer and calcium carbonate were blended in the proportions shown in Table 2 and the cylinder temperature was 190 ° C. using a twin screw extruder.
And melt-kneaded to produce pellets. The melt viscosity of the pellet was measured at 190 ° C. using a
/ Sec. A test piece was prepared by injection molding using this pellet, and Izod impact strength, flexural modulus,
Rockwell hardness ASTM-D256, ASTM-D785, ASTM-D79
The measurement was carried out according to 0 respectively. Table 2 shows the obtained results. The difference (Δδ) between the solubility parameters of the polyacetal polymer (b1 component) and polyethylene glycol (b2 component) and Δδ of the polyacetal polymer (b1 component) and the polyether random copolymer are determined by the above-described methods. The solubility parameter of each polymer was calculated and Δδ was determined therefrom. In addition, a spherulite region having a diameter of 3 μm or more was observed. The spherulite region having a diameter of 3 μm or more was observed by the following method. A dumbbell-type injection-molded product having a thickness of 3 mm is prepared, and a plane parallel to the resin flowing direction is cut at a substantially parallel center with a microtome to form a smooth surface. The surface is immersed in concentrated sulfuric acid for 30 seconds at room temperature (23 ° C.), and then immersed in 30% sulfuric acid for 30 minutes to perform an etching process. After sufficiently washing with water to remove sulfuric acid, the mixture is dried. SE by coating a platinum-palladium film by sputtering performed by ordinary SEM observation
This is a sample for M observation. The SEM observation was performed at an acceleration voltage of 5 kV, and an appropriate magnification was selected from the range of 600 to 2000 times depending on the size of the spherulite structure. The area of the spherulite having a diameter of 3 μm or more was determined by image processing, and the occupied area ratio was determined. Further, the crystallinity of the resin component was examined. The crystallinity was determined by the following method using reflection wide-angle X-ray diffraction. That is, the pellet is placed on a hot plate at 190 ° C
Melt at a temperature of 70 ° C. and solidify on another hot plate adjusted to a temperature of 70 ° C. Under the output condition of 40 kV / 140 mA, the scattering intensity monochromatized by the monochromator under the condition of the slit width of 0.5 degree is observed. (100) Crystal plane peak area (Ac)
The crystallinity was calculated as [Ac / (Ac + Aa)] from the above and the compound area (Aa) of the amorphous halo portion. Table 2 also shows these results.

[0021]

[Table 2]

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C08L 71/02 C08L 71/02 75/04 75/04 (72) Inventor Hidetoshi Okawa 973 Miyajima, Fuji City, Shizuoka Prefecture Address Polyplastics Co., Ltd. (72) Inventor Toshio Nakane 973 Miyajima, Fuji City, Shizuoka Prefecture Polyplastics Co., Ltd. (72) Inventor Shinya Kawamura 1 Toyota Town, Toyota City, Aichi Prefecture Toyota Motor Corporation (72) Invention Person Masatoshi Matsuda 1 Toyota Town, Toyota City, Aichi Prefecture F-term in Toyota Motor Corporation (reference) 4J002 CB00W CB00X CH02X CH05X DA016 DA036 DE076 DE136 DE146 DE186 DE236 DJ006 DJ016 DJ036 DJ046 DJ056 DK006 DL006 FA016 FA046 FA066 FA086 FD016 4A03A AC08 AD01 AF10 4J034 BA03 BA07 DA01 DG03 DN01 HA01 HA02 HA07 HC12 HC13 HC17 HC22 HC46 HC 54 HC64 HC67 HC70 HC71 HC73 QD01 RA11 RA14

Claims (8)

[Claims] (A) a polyacetal resin (B) a polyacetal polymer (b1) and a polyether polymer
a polyether block copolymer (b1) comprising the polyether block copolymer (b2) and a filler (C), and constituting the polyether block copolymer (B); and a polyether polymer.
A polyacetal resin composition, wherein the difference in the solubility parameter of (b2) is 0.5 (cal / cm ³ ) ^1/2 or less. (2) a polyacetal resin (B) a polyacetal polymer (b1) and a polyether polymer
The polyether block copolymer with (b2) and the filler (C) are filled, and the spherulite region having a diameter of 3 μm or more by molding is 10%.
A polyacetal resin composition capable of forming the following molded article. (3) (A) a polyacetal resin (B) a polyacetal polymer (b1) and a polyether polymer
a polyether-based block copolymer with (b2), and (C) a filler, wherein the resin component has a crystallinity of 65 to 90%, a flexural modulus of 1500 MPa or more, as determined from reflection wide-angle X-ray scattering, A polyacetal resin composition having a notched Izod impact strength of at least 80 J / m, a melt viscosity measured at 190 ° C. and a shear rate of 1216 sec ⁻¹ of 250 Pa · s or less. 4. The polyether block copolymer (B) comprises:
Polyacetal polymer (b1) and polyether polymer (b2)
Is a block copolymer obtained by reacting with a polyisocyanate compound (b3). The polyacetal resin composition according to any one of claims 1 to 3, wherein 5. The polyacetal resin composition according to claim 1, wherein the polyether polymer (b2) is polyethylene glycol. 6. The polyacetal resin composition according to claim 4, wherein the polyisocyanate compound (b3) is a diisocyanate compound. 7. A polyether block copolymer (B) comprising:
Polyacetal polymer (b1) and polyether polymer (b2)
The polyacetal resin composition according to any one of claims 1 to 6, wherein the polyacetal resin composition is obtained by reacting at a weight ratio (b1 / b2) of 75/25 to 25/75. 8. The filler (C) is used in an amount of 0.1 to 50 parts by weight of the polyacetal resin (A) and 10 to 50 parts by weight of the polyether-based book copolymer (B). ~
The polyacetal resin composition according to any one of claims 1 to 7, comprising 20 parts by weight.