JP2007039545A - Polyacetal resin composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polyacetal resin composition excellent in a balance of mechanical properties such as stiffness, strengths, toughness and heat resistance, and superior in heat stability. <P>SOLUTION: This polyacetal resin composition comprises 100 parts by mass of a polyacetal resin (I), 0.1-100 parts by mass of calcium carbonate (II) that has an average particle diameter of ≥0.01 μm and <1.5 μm, and exhibits an aspect ratio (L/D), namely a ratio of an average major axis (L) to an average minor axis (D) of the particle, of ≤3, 0.001-10 parts by mass of a coupling agent (III) and 0.001-10 parts by mass of an organic acid (IV). <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a resin composition excellent in the balance of mechanical properties such as rigidity, strength, toughness, heat resistance, and the like, which is obtained by blending a specific calcium carbonate, a coupling agent and an organic acid with a polyacetal resin.

Polyacetal resins are used as engineering plastics because they have easy mechanical properties and processability, and are widely used mainly in electrical equipment, mechanical parts of electrical equipment, automobile parts, and other mechanical parts.
In recent years, improvement in mechanical properties such as rigidity, strength, toughness, and heat resistance of polyacetal resin has been demanded due to demands for weight reduction and miniaturization of each part. Furthermore, due to environmental considerations, there is a demand for further reduction of formaldehyde generated during molding and processing, and there is a need for properties that are excellent in thermal stability.

  Conventionally, as a method for improving mechanical properties such as rigidity and strength, an inorganic filler such as glass fiber, talc, uwalastonite, and carbon fiber has been blended. However, although effective in improving rigidity, strength, and heat resistance, toughness tends to be significantly impaired. Furthermore, in the case of a polyacetal resin, the thermal stability is remarkably lowered by adding an inorganic filler, formaldehyde as a monomer is generated, and in addition to environmental problems, mold contamination during molding becomes a problem. There was a case.

  Therefore, a specific adhesion promoter is added to an alkaline earth metal such as calcium carbonate in a resin composition (Patent Document 1) made of polyacetal resin and calcium carbonate or talc that has been subjected to a specific surface treatment, or polyacetal resin. A resin composition (Patent Documents 2 and 3), and a composition comprising a polyacetal resin and calcium carbonate having a specific particle size and shape and a saturated fatty acid or a metal salt thereof (Patent Document 4) are disclosed. The rigidity is improved while maintaining. However, the strength of the resin composition tends to decrease, which may be a problem. Furthermore, it was found that the thermal stability is not fully satisfactory.

In addition, a polyacetal resin composition for a sliding member (patent document 5) comprising a polyacetal resin, an inorganic powder such as calcium carbonate having a specific particle size, and a specific fatty acid ester, or a specific additive, magnesium or calcium for the polyacetal resin Although a composition (for example, Patent Document 6) excellent in thermal stability obtained by blending an oxide or carbonate of the above is disclosed, it is not sufficient to improve mechanical properties such as rigidity and toughness. all right.
Thus, in the prior art, it is difficult to obtain a composition excellent in thermal stability while having a good balance of mechanical properties of polyacetal resin, in particular, rigidity, strength, toughness, heat resistance, etc. A composition having an excellent balance is desired.

Japanese Patent Publication No. 8-30137 Japanese Examined Patent Publication No. 3-26222 U.S. Pat. No. 4,456,710 Japanese translation of PCT publication No. 2004-506772 Japanese Patent Publication No. 8-26207 Japanese Patent Laid-Open No. 7-62199

  The present invention provides a resin composition excellent in the balance of mechanical properties such as rigidity, strength, toughness, heat resistance, etc. and heat stability, which is obtained by blending a specific calcium carbonate, a coupling agent and an organic acid with a polyacetal resin. The purpose is to do.

As a result of diligent studies to solve the above problems, the present inventor has blended specific calcium carbonate, a coupling agent, and an organic acid, thereby balancing mechanical properties such as rigidity, strength, toughness, heat resistance, and the like. The inventors have found that the thermal stability is excellent, and have completed the present invention.
That is, the present invention is as described below.

(1) The average particle diameter is 0.01 μm or more and less than 1.5 μm with respect to 100 parts by mass of the polyacetal resin (I), and the ratio of the average major axis (L) of the particles to the average minor axis (D) of the particles 0.1 to 100 parts by mass of calcium carbonate (II) having an average aspect ratio (L / D) of 3 or less, 0.001 to 10 parts by mass of coupling agent (III), 0.001 of organic acid (IV) 10 to 10 parts by mass of a polyacetal resin composition,
(2) The amount of BET adsorption of calcium carbonate (II) is X ₁ (m ² / g), the mass is X ₂ , the minimum coating area of the coupling agent (III) is Y ₁ (m ² / g), and the mass , Y ₂ , the minimum covering area of organic acid (IV) is Z ₁ (m ² / g), and the mass thereof is Z _2. Resin composition,
50 ≦ (Y ₁ Y ₂ + Z ₁ Z ₂ ) / X ₁ X ₂ × 100 ≦ 200
10 ≦ Y ₁ Y ₂ / (Y ₁ Y ₂ + Z ₁ Z ₂ ) × 100 ≦ 90
(3) The polyacetal resin composition according to the above (1) or (2), wherein the calcium carbonate (II) is light calcium carbonate,
(4) The polyacetal resin composition according to any one of (1) to (3) above, wherein the average particle diameter of calcium carbonate (II) is 0.01 μm to 1.0 μm,
(5) The polyacetal resin composition according to any one of (1) to (4) above, wherein calcium carbonate (II) is 6 to ²⁰⁰ m ² / g in a BET specific surface area,
(6) The polyacetal resin composition according to any one of the above (1) to (5), wherein the content of particles having a particle size of 1 μm or less of calcium carbonate (II) is 90% or more,
(7) In the calcium carbonate (II), the amount of Na relative to Ca is 250 ppm or less, and the polyacetal resin composition according to any one of (1) to (6) above,
(8) In the calcium carbonate (II), the amount of Sr with respect to Ca is 500 to 2500 ppm, The polyacetal resin composition according to any one of (1) to (7) above,
(9) The polyacetal resin composition according to any one of (1) to (8) above, wherein the coupling agent (III) is a silane coupling agent,
(10)
Any of (1) to (9) above, wherein the coupling agent (III) is at least one selected from the group consisting of compounds represented by the following general formula and / or a polycondensate thereof: A polyacetal resin composition according to claim 1,
(R ₁ O) _l SiR _2m C ₃ H ₆ NHC ₂ H ₄ NH ₂
(R ₁ O) _l SiR _2m C ₃ H ₆ NH ₂
(R ₁ O) _l SiR _2m C ₃ H ₆ NCO
Here, l + m = 3, l, m is a number selected from 0 to 3, R ₁ and R ₂ are hydrogen or a saturated or unsaturated hydrocarbon group, and the hydrocarbon group has a functional group. May be introduced,
It is.

  The polyacetal resin composition of the present invention has an effect of excellent balance of mechanical properties such as rigidity, strength, toughness, heat resistance, and thermal stability.

Hereinafter, the present invention will be specifically described.
The polyacetal resin (I) used in the present invention is a known polyacetal resin and is not particularly limited. For example, a polyacetal homopolymer consisting essentially of oxymethylene units obtained by homopolymerizing formaldehyde monomers or cyclic oligomers of formaldehyde such as trimers (trioxane) and tetramers (tetraoxane), Formaldehyde, its trimer (trioxane) and tetramer (tetraoxane) formaldehyde cyclic oligomers and ethylene oxide, propylene oxide, epichlorohydrin, 1,3-dioxolane, 1,4-butanediol formal and other glycols and diglycols And polyacetal copolymers obtained by copolymerizing cyclic ethers such as cyclic formal and cyclic formal.

  Here, among the polyacetal copolymers, the addition amount of a preferable comonomer such as 1,3-dioxolane is 0.1 to 60 mol% with respect to 1 mol of trioxane from the viewpoint of more excellent balance of rigidity, toughness, and heat resistance. More preferably, it is 0.1-20 mol%, Most preferably, it is 0.15-10 mol%. At this time, although the melting point of the polyacetal resin depends on the comonomer amount, the preferable melting point is 164 ° C. to 172 ° C., more preferably 165 ° C. to 171 ° C., and most preferably 167 ° C. to 170 ° C.

  Further, as the polyacetal copolymer, a branched polyacetal copolymer having a branch obtained by copolymerizing a monofunctional glycidyl ether, or a crosslinked polyacetal copolymer having a crosslinked structure obtained by copolymerizing a polyfunctional glycidyl ether can also be used. . Furthermore, a block type polyacetal homopolymer having a block component obtained by polymerizing a formaldehyde monomer or a cyclic oligomer of formaldehyde in the presence of a compound having a functional group such as a hydroxyl group at both ends or one end, for example, polyalkylene glycol, In the presence of a compound having a functional group such as a hydroxyl group at both ends or one end, for example, hydrogenated polybutadiene glycol, formaldehyde monomer or cyclic formaldehyde such as trimer (trioxane) or tetramer (tetraoxane). A block-type polyacetal copolymer having a block component obtained by copolymerizing an oligomer with cyclic ether or cyclic formal can also be used. In the present invention, the polyacetal resin may be used alone or in a mixture of two or more.

  Among the polyacetal resins, from the viewpoint of excellent balance of rigidity, toughness, and thermal stability, the polyacetal resin (I) may be a random, block, branched, or crosslinked polyacetal copolymer in which comonomer components are randomly bonded. And a mixture thereof, and a random or block type polyacetal copolymer is more preferable from the viewpoint of cost.

  Furthermore, from the viewpoint of thermal stability, the polyacetal resin (I) preferably has a formaldehyde generation rate of 15 ppm or less when heated at 220 ° C. for 10 to 30 minutes in a nitrogen stream at 10 ppm / min. The following is more preferable, and 5 ppm / min. Most preferably: Here, the measurement of the formaldehyde generation rate is specifically described. Under a nitrogen stream (50 NL / hr), the polyacetal resin is heated and melted at 220 ° C., and the generated formaldehyde is absorbed in water, and then by a sodium sulfite method. Titrate.

At that time, the amount of formaldehyde generated (ppm) from the start of heating to 2 minutes after is S ₂ , S _{10 is} until 10 minutes later, S _{30 is 30} minutes, S _{50 is} 50 minutes, S _{50 is} 90 minutes, and S _{90 is} 90 minutes. And when
Generation rate from 2 minutes to 10 minutes: (S ₁₀ -S ₂ ) / 8 (ppm / min.)
Generation rate from 10 minutes to 30 minutes: (S ₃₀ -S ₁₀ ) / 20 (ppm / min.)
Generating a rate of 50 minutes to 90 _{minutes: (S 90 -S 50) /} 40 (ppm / min.)
Calculate as

  These values are said to be caused by formaldehyde adhering to the polyacetal resin, caused by formaldehyde generated by terminal decomposition of the polyacetal resin, and caused by formaldehyde generated by main chain decomposition of the polyacetal resin. In the present invention, the terminal decomposition of the polyacetal resin, that is, the formaldehyde generation rate in 10 to 30 minutes is preferably in the above range.

  The melt flow index MFI (measured by ASTM-D1238) of the polyacetal resin (I) is not particularly limited, but is preferably 0.1 g / 10 min to 150 g / 10 min, more preferably from the viewpoint of workability. Is 0.5 g / 10 min to 130 g / 10 min, most preferably 1 g / 10 min to 100 g / 10 min.

  In the present invention, a known method for producing a polyacetal resin can be employed as a method for producing the polyacetal resin (I), and is not particularly limited. For example, in the case of the polyacetal homopolymer, polymerization is performed by introducing high-purity formaldehyde into an organic solvent containing a basic polymerization catalyst such as an organic amine, an organic or inorganic tin compound, or a metal hydroxide. And a method in which the polymer terminal is acetylated by heating in acetic anhydride in the presence of sodium acetate. In the case of the polyacetal copolymer, boron trifluoride is introduced by introducing a high purity trioxane, a copolymer component such as ethylene oxide or 1,3-dioxolane, and a chain transfer agent for adjusting the molecular weight into an organic solvent such as cyclohexane. Cationic polymerization using a polymerization catalyst such as a Lewis acid such as a diethyl ether complex, followed by deactivation of the catalyst and stabilization of the end groups, or without using any solvent, a kneader, biaxial Introducing trioxane, copolymerization component, chain transfer agent for molecular weight adjustment and catalyst into a self-cleaning type extrusion kneader such as a screw type continuous extrusion kneader, twin screw paddle type continuous mixer, etc. A method of manufacturing by adding a quaternary ammonium compound such as choline oxide formate and decomposing and removing unstable terminals, etc. Can.

Here, as a method for obtaining a preferred polyacetal resin (I) having excellent thermal stability, the polyacetal resin is thermally unstable using at least one quaternary ammonium compound represented by the following general formula (1). A method of stabilizing the ends by treating them can be mentioned.
[R ¹ R ² R ³ R ⁴ N ⁺ ] _n X ⁿ⁻ (1)
(Wherein R ¹ , R ² , R ³ and R ⁴ are each independently an unsubstituted alkyl group or substituted alkyl group having 1 to 30 carbon atoms, an aryl group having 6 to 20 carbon atoms, or 1 to carbon atoms) An aralkyl group in which 30 unsubstituted alkyl groups or substituted alkyl groups are substituted with at least one aryl group having 6 to 20 carbon atoms, or an aryl group having 6 to 20 carbon atoms has at least one carbon atom having 1 to 30 carbon atoms Represents an unsubstituted alkyl group or an alkylaryl group substituted with a substituted alkyl group, and the unsubstituted alkyl group or substituted alkyl group is linear, branched, or cyclic, the above-mentioned unsubstituted alkyl group, aryl group, aralkyl group; In the alkylaryl group, a hydrogen atom may be substituted with a halogen, n represents an integer of 1 to 3. X represents a hydroxyl group, a carboxylic acid having 1 to 20 carbon atoms, a hydrogen acid, or an It represents an acid residue of oxo acid inorganic thio acid or organic thio acid having 1 to 20 carbon atoms.)

In the above general formula, preferable R ¹ , R ² , R ³ and R ⁴ are each independently an alkyl group having 1 to 5 carbon atoms or a hydroxyalkyl group having 2 to 4 carbon atoms, and more preferably R 1 ^{1, R 2,} R 3, at least one of ^{R 4,} a hydroxyethyl group. More specifically, tetramethylammonium, tetoethylammonium, tetrapropylammonium, tetra-n-butylammonium, cetyltrimethylammonium, tetradecyltrimethylammonium, 1,6-hexamethylenebis (trimethylammonium), decamethylene-bis- (Trimethylammonium), trimethyl-3-chloro-2-hydroxypropylammonium, trimethyl (2-hydroxyethyl) ammonium, triethyl (2-hydroxyethyl) ammonium, tripropyl (2-hydroxyethyl) ammonium, tri-n-butyl (2-hydroxyethyl) ammonium, trimethylbenzylammonium, triethylbenzylammonium, tripropylbenzylammonium, tri-n-butyl Benzylammonium, trimethylphenylammonium, triethylphenylammonium, trimethyl-2-oxyethylammonium, monomethyltrihydroxyethylammonium, monoethyltrihydroxyethylammonium, okdadecyltri (2-hydroxyethyl) ammonium, tetrakis (hydroxyethyl) ammonium, etc. Hydroxides of hydrochloric acid, odorous acid, hydrofluoric acid, etc .; sulfuric acid, nitric acid, phosphoric acid, carbonic acid, boric acid, chloric acid, iodic acid, silicic acid, perchloric acid, chlorous acid, hypochlorous acid Oxo acid salts such as chlorosulfuric acid, amidosulfuric acid, disulfuric acid, tripolyphosphoric acid; thioic acid salts such as thiosulfuric acid; formic acid, acetic acid, propionic acid, butanoic acid, isobutyric acid, pentanoic acid, caproic acid, caprylic acid, capric acid , Carboxylates such as benzoic acid and oxalic acid And the like.
Of these, hydroxides, sulfuric acid, carbonic acid, boric acid, and carboxylic acid salts are preferred. Furthermore, formic acid, acetic acid, and propionic acid are particularly preferable among carboxylic acids. These quaternary ammonium compounds may be used alone or in combination of two or more.

At this time, the amount of the quaternary ammonium compound added is 0.05 to 5 in terms of the amount of nitrogen derived from the quaternary ammonium compound represented by the following formula relative to the total mass of the polyacetal resin and the quaternary ammonium compound. 50 ppm by mass, preferably 1 to 30 ppm by mass.
P × 14 / Q
(In the formula, P represents the concentration (mass ppm) of the quaternary ammonium compound relative to the polyacetal resin, 14 represents the atomic weight of nitrogen, and Q represents the molecular weight of the quaternary ammonium compound.)
At this time, when the addition amount of the quaternary ammonium compound is less than 0.05 mass ppm, the decomposition and removal rate of the unstable terminal portion tends to decrease. The color tone of the polyacetal resin tends to decrease.

  A preferable method for stabilizing is to heat-treat the quaternary ammonium compound and the polyacetal resin using an extruder, a kneader, or the like at a resin temperature not lower than the melting point of the polyacetal resin and not higher than 260 ° C. Here, if it exceeds 260 ° C., there is a possibility that coloring problems and decomposition (lower molecular weight) of the polymer main chain may occur.

  Moreover, there is no restriction | limiting in particular in the addition method of a quaternary ammonium compound, There exist the method of adding as aqueous solution in the process of deactivating a polymerization catalyst, the method of spraying on resin powder, etc. Whichever addition method is used, it is sufficient that the polyacetal resin is added in the heat treatment step, and the compound is poured into an extruder, or the compound is attached to the resin pellet. Decomposition may be performed. The unstable terminal can be decomposed after deactivating the polymerization catalyst in the polyacetal resin obtained by polymerization, or can be performed without deactivating the polymerization catalyst.

Calcium carbonate (II) used in the present invention is a known calcium carbonate and is not particularly limited. For example, as a generally known crystal form of calcium carbonate, any of calcite, aragonite, and vaterite is used. Also in the manufacturing process, it may be called natural calcium carbonate or light calcium carbonate obtained by artificial synthesis (or colloidal calcium carbonate, precipitated calcium carbonate, activated calcium carbonate, etc.) ). In general, light calcium carbonate, unlike heavy calcium carbonate, may be confirmed by Fourier infrared spectroscopy to have some active sites such as hydroxyl groups in a part of the surface layer. It is not limited.
In the above-mentioned calcium carbonate, light calcium carbonate can be mentioned as a preferable calcium carbonate from the viewpoint of excellent balance of mechanical properties of the resulting polycetal resin. Similarly, calcite is preferable as a crystal form.

In the present invention, among the calcium carbonate particles, the length of the longest axis is defined as the major axis, and the length of the shortest axis corresponding thereto is defined as the minor axis. The average particle diameter and the average major axis, average minor diameter, and the average aspect ratio, long diameter L _i in unit _volume, when the calcium carbonate minor D _i is N _i number exists,
Average particle diameter = Average major axis = ΣL _i ² N _i / ΣL _i N _i
Average minor axis = ΣD _i ² N _i / ΣD _i N _i
Average aspect ratio L / D = (ΣL _i ² N _i / ΣL _i N _i ) / (ΣD _i ² N _i / ΣD _i N _i )
It is defined and used.

  More specifically, sampling of calcium carbonate to be inspected using a scanning electron microscope (SEM), and using this, a particle image was taken at a magnification of 1,000 to 50,000 times, and randomly selected at the lowest Each length is determined from 100 particles of calcium carbonate.

  In the calcium carbonate (II) used in the present invention, the preferable average particle size of calcium carbonate is 0.01 to 1.0 μm, more preferably 0.05 to 0.6 μm, and most preferably 0.10 to 1.0 μm. 0.40 μm. The average aspect ratio (L / D), which is the ratio of the average major axis (L) of the particles to the average minor axis (D) of the particles, is 3 or less, more preferably 2 or less, and more preferably 1. 5 or less. If it is in the said range, it exists in the tendency which is excellent in the balance of the mechanical characteristic of the polyacetal resin composition obtained by this invention.

For the same reason, in calcium carbonate (II), the preferred specific surface area is 6 to ²⁰⁰ m ² / g, more preferably 8 to 100 m ² / g, more preferably 10 to 20 m ^{2 in the} BET adsorption method. / G.
For the same reason, the preferable average particle size of calcium carbonate (II) is 90% or more, more preferably 95% or more, and most preferably 98% or more. The measurement method of average particle size here is obtained by a light transmission particle size analysis method.

  In the calcium carbonate (II) used in the present invention, the preferable amount of Na relative to Ca is 250 ppm or less, more preferably 150 ppm or less, and most preferably 100 ppm or less. Similarly, the amount of Sr with respect to Ca is preferably 500 to 2500 ppm, more preferably 700 to 1300 ppm, and most preferably 800 to 1000 ppm. Here, the amount of Na and Sr with respect to Ca can be determined by high frequency inductively coupled plasma (ICP) emission analysis.

  More specifically, 0.5 g of calcium carbonate is weighed in a platinum dish and carbonized in a 500 ° C. electric furnace. After cooling, add 5 mL of hydrochloric acid and 5 mL of pure water, and boil and dissolve on a heater. After cooling again, pure water is added to obtain a measurable concentration, and quantification is performed according to the characteristic wavelength of each metal by high frequency inductively coupled plasma (ICP) emission analysis using IRIS / IP manufactured by Thermo Jarrel Ash. Thereafter, the amounts of Na and Sr with respect to Ca are calculated. Here, the Na and Sr are derived from impurities contained in the calcium carbonate.

  In general, calcium carbonate is obtained by crushing and refining naturally occurring heavy calcium carbonate, artificial synthesis and purification by blowing carbon dioxide into a calcium hydroxide aqueous solution, and in some cases adding an anti-agglomeration agent or surface treatment agent. In any of the steps, Na contained in water or Sr that can be substituted for Ca may be incorporated into calcium carbonate as an impurity. Moreover, it may be contained as an impurity in the limestone etc. used as the raw material of calcium carbonate.

  When the content of Na and Sr with respect to Ca is in the above range, the resulting polyacetal resin composition has an excellent balance of mechanical properties such as thermal stability, rigidity, and toughness, and tends to have excellent creep life and fatigue resistance. It is in. It is not clear about these reasons, but it is presumed that it has the effect of reducing the particle size of calcium carbonate and sharpening the particle size distribution, and further improving the wettability and interface with the polyacetal resin. Is done.

  The coupling agent (III) used in the present invention is a known coupling agent, and a silane coupling agent, a titanate coupling agent, or an aluminate coupling agent can be used. The coupling agent can be used in any combination of silane, titanate, and aluminate.

As said silane coupling agent, at least 1 type chosen from the group which consists of a compound represented by following General formula (2), and / or those polycondensates can be used.
(R ₁ O) _k SiR _2l R _3m R _4n (2)
(Where k + l + m + n = 4, k, l, m, n are numbers selected from 0 to 4, and R ₁ , R ₂ , R ₃ , R ₄ are hydrogen or a saturated or unsaturated hydrocarbon group. Yes, a functional group may be introduced into the hydrocarbon group, and in (R ₁ O) _k , (R ₁ O) may be replaced with a halogen such as Cl.)

For example, R ₁ can be a methyl, ethyl, or phenyl group, and R ₁ , R ₂ , or R ₃ can be an alkyl group having a vinyl group, an epoxy group, a methacryl group, an amino group, or a mercapto group. Can do.
More specifically, examples of the alkyl type include tetramethoxysilane, tetraethoxysilane, dimethyldimethoxysilane, and diphenyldimethoxysilane. Examples of the vinyl type include vinyltrichlorosilane, vinyltrimethoxysilane, vinyltriethoxysilane, and vinyltris (2 -Methoxyethoxy) silane, etc. As epoxy type, 2- (3,4 epoxycyclohexyl) ethyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltrimethyldiethoxysilane, 3-glycol Sidoxypropyltriethoxysilane and the like, styryl type is p-styryltrimethoxysilane and the like, and methacryloxy type is 3-methacryloxypropylmethyldimethoxysilane and 3-methacryloxypropyltrimethoxy. Silane, 3-methacryloxypropylmethyldiethoxysilane, 3-methacryloxypropyltriethoxysilane, acryloxy-based 3-acryloxypropyltriethoxysilane, etc., amino-based N-2 (aminoethyl) 3- Aminopropylmethyldimethoxysilane, N-2 (aminoethyl) 3-aminopropyltrimethoxysilane, N-2 (aminoethyl) 3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxy Silane, 3-triethoxysilyl-N- (1,3-dimethyl-butylidene) propylamine, N-phenyl-3-aminopropyltrimethoxysilane and the like, and ureidos include 3-ureidopropyltriethoxysilane and the like, chloro Propyl type Is 3-chloropropyltrimethoxysilane, etc., as mercapto type, 3-mercaptopropyltrimethoxysilane, 3-mercaptopropylmethyldimethoxysilane, etc., as sulfide type, bis- (3- [triethoxysilyl] -propyl ) -Tetrasulfane and the like, such as 3-isocyanatopropyltriethoxysilane and the like can be exemplified.
These silane coupling agents may be two or more polycondensates generated by hydrolysis and dehydration condensation of a part of the bond. Two or more types may be used in combination or polycondensed.

As said titanate coupling agent, at least 1 sort (s) chosen from the group which consists of a compound represented by following General formula (3), and / or those polycondensates can be used.
(R ₅ O) _k TiR _6l R _7m R _8n (3)
(Where k + l + m + n = 4, k, l, m, n are numbers selected from 0 to 4, and R ₅ , R ₆ , R ₇ , R ₈ are hydrogen or a saturated or unsaturated hydrocarbon group. Yes, a functional group may be introduced into the hydrocarbon group.)
For example, examples of R ₅ include isopropoxyl and n-butoxy groups. Examples of R ₆ , R ₇ and R ₈ include acetonato having a vinyl group, an epoxy group, a methacryl group, an amino group, and a mercapto group, Aminato group can be raised.

More specifically, tetraethoxy titanium, tetraisopropoxy titanium, tetra n-butoxy titanium, isopropoxy titanium triisostearate, isopropoxy titanium dimethacrylate isostearate, isopropoxy titanium tridodecyl benzene sulfonate, isopropoxy titanium tris. Dioctyl phosphate, isopropoxy titanium tri-N-ethylaminoethylaminato, titanium bisdioctyl pyrophosphate oxyacetate, bisdioctyl phosphate ethylene glycolato titanium, tetraisopropoxy titanium bisdioctyl phosphite, di-n-butoxybistriethanolaminato Examples include titanium.
These silane coupling agents may be two or more polycondensates produced by hydrolysis and dehydration condensation of part of the bonds. Two or more types may be used in combination or polycondensed.

As said aluminate coupling agent, at least 1 sort (s) chosen from the group which consists of a compound represented by following General formula (4), and / or those polycondensates can be used.
(R ₈ O) _l AlR _9m R _10n (4)
(Where l + m + n = 3, l, m, n is a number selected from 0 to 3; R ₈ , R ₉ , R ₁₀ are hydrogen or a saturated or unsaturated hydrocarbon group; May contain a functional group.)

For example, R ₈ can be an isopropoxyl or n-butoxy group, and R ₉ and R ₁₀ can be an acetonato or aminato group having a vinyl group, an epoxy group, a methacryl group, an amino group, or a mercapto group. be able to. These aluminate coupling agents may be two or more polycondensates produced by hydrolysis and dehydration condensation of some of the bonds. Two or more types may be used in combination or polycondensed.

  Among these, as a preferable coupling agent from the viewpoint of cost, a silane coupling agent is preferable. Further, the chemical stability of the coupling agent itself, good handling when performing surface treatment, and actually surface-treated carbonic acid. From the viewpoint of excellent balance of mechanical properties in a resin composition obtained by kneading calcium with a polyacetal resin, a silane coupling agent having an amino group, a ureido group, and an isocyanate group is preferable. It is most preferable to use at least one selected from the group consisting of silane coupling agents represented by the general formulas (5) to (7) and / or their polycondensates.

(R ₁ O) _l SiR _2m C ₃ H ₆ NHC ₂ H ₄ NH ₂ (5)
(R ₁ O) _l SiR _2m C ₃ H ₆ NH ₂ (6)
(R ₁ O) _l SiR _2m C ₃ H ₆ NCO (7)
(Where l + m = 3, l and m are numbers from 0 to 3, R1 and R2 are hydrogen or a saturated or unsaturated hydrocarbon group, and a functional group is introduced into the hydrocarbon group. Is also good.)
Specific examples include N-2 (aminoethyl) 3-aminopropylmethyldimethoxysilane, N-2 (aminoethyl) 3-aminopropyltrimethoxysilane, N-2 (aminoethyl) 3-aminopropyltriethoxy. Silane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, and 3-isocyanatopropyltriethoxysilane.

  The organic acid (IV) used in the present invention is a monovalent or polyvalent carboxylic acid having an aliphatic group and an aromatic group, and a part of these having a substituent such as a hydroxyl group introduced therein, or these acids Acid anhydrides, monovalent or polyvalent sulfonic acids having an aliphatic group and an aromatic group, and those into which a substituent such as a hydroxyl group is introduced, a further aliphatic group and an aromatic group The monovalent or polyvalent phosphoric acid having a hydrogen atom and a part of these having a substituent such as a hydroxyl group introduced therein are not particularly limited as long as they are known.

  For example, as saturated fatty acids, acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, caprylic acid, lauric acid, tridecylic acid, myristic acid, palmitic acid, heptadecylic acid, stearic acid, pivalic acid, isobutyric acid, and ethylenediamine tetra Acetic acid or the like as an unsaturated fatty acid, oleic acid, elaidic acid, erucic acid, linoleic acid, ricinoleic acid, etc., alicyclic carboxylic acid as naphthenic acid, etc. as resin acid, abietic acid, pimaric acid, parastolic acid, Examples include neoabietic acid and the like, and these acid anhydrides as mono- or polyvalent sulfonic acids, such as lauryl sulfonic acid, polyoxyethylene lauryl ether sulfonic acid, dodecylbenzene sulfonic acid, and dialkyl sulfosuccinic acid. it can.

These may be used alone or in a mixture of two or more.
Of these, saturated fatty acids, unsaturated fatty acids, alicyclic carboxylic acids, and resin acids, which are preferably monovalent and polyvalent carboxylic acids, can be mentioned from the viewpoints of thermal stability and color tone, and further dispersed in polyacetal resins. Saturated fatty acids are preferred from the standpoints of properties and color tone, and the polyacetal resin composition obtained further has 8 to 36 carbon atoms, more preferably 10 to 30 carbons from the viewpoint of bleeding of carboxylic acid on the surface of the molded article or MD. Saturated fatty acids, most preferably 12 to 24, are preferred. For example, lauric acid, tridecylic acid, myristic acid, pentadecylic acid, palmitic acid, heptadecylic acid, stearic acid, nonadecanoic acid, alginate, behenic acid, lignoceric acid, serotic acid, heptacoic acid, montanic acid, linoleic acid, alginate, etc. Can give.

  In the polyacetal resin composition of the present invention, the average particle diameter is 0.01 μm or more and less than 1.5 μm with respect to 100 parts by mass of the polyacetal resin (I), and the average major axis (L) of the particles and the average of the particles 0.1 to 100 parts by mass of calcium carbonate (II) having an average aspect ratio (L / D) of 3 or less, which is the ratio of the minor axis (D), 0.001 to 10 parts by mass of coupling agent (III), organic It is formed by blending 0.001 to 10 parts by mass of acid (IV). Here, from the viewpoint of excellent mechanical balance of the polyacetal resin, the amount of calcium carbonate (II) is preferably 1 to 80 parts by mass, more preferably 5 to 60 parts by mass, and most preferably 10 -40 mass parts. Similarly, the amount of coupling agent (III) is preferably 0.01 to 8 parts by mass, more preferably 0.1 to 5 parts by mass, and most preferably 0.5 to 3 parts by mass. is there. Similarly, the compounding amount of the organic acid (IV) is preferably 0.01 to 5 parts by mass, more preferably 0.1 to 3 parts by mass, and most preferably 0.3 to 1 part by mass. .

Here, from the viewpoints of excellent dispersibility and adhesion to the polyacetal resin, excellent balance of strength, rigidity and toughness of the resulting resin composition, and excellent thermal stability, coupling with calcium carbonate (II) is preferable. The following relationship can be given as the blending amount of the agent (III) and the organic acid (IV).
50 ≦ (Y ₁ Y ₂ + Z ₁ Z ₂ ) / X ₁ X ₂ × 100 ≦ 200
10 ≦ Y ₁ Y ₂ / (Y ₁ Y ₂ + Z ₁ Z ₂ ) × 100 ≦ 90
(Wherein the amount of BET adsorption of calcium carbonate (II) is X ₁ (m ² / g), the mass is X ₂ , the minimum coating area of the coupling agent (III) is Y ₁ (m ² / g), (The mass is defined as Y ₂ , the minimum covering area of the organic acid (IV) is defined as Z ₁ (m ² / g), and the mass is defined as Z _2. )

Here, the minimum covered area is a value indicating the size of each molecule calculated from the Stuart-Briegleb molecular model. For example, in a silane coupling agent, (78.3 × 1000) / (silane The molecular weight of the coupling agent (m ² / g). Similarly, the linear fatty acid is defined by (120.4 × 1000) / (molecular weight of fatty acid) (m ² / g).

In the above relational expression, (Y ₁ Y ₂ + Z ₁ Z ₂ ) / X ₁ X ₂ × 100 is a surface area occupied by molecules of the coupling agent (III) and the organic acid (IV) with respect to the surface area of calcium carbonate (II). %, That is, the surface coverage ratio is preferably 70 to 180%, more preferably 80 to 150%, and most preferably 90 to 120%.

Further, Y ₁ Y ₂ / (Y ₁ Y ₂ + Z ₁ Z ₂ ) × 100 is the ratio of the area occupied by the coupling agent (III) to the area occupied by both the coupling agent (III) and the organic acid (IV) And preferably 20 to 85%, more preferably 40 to 80%, and most preferably 60 to 75%.

The method for producing the polyacetal resin composition of the present invention is a method in which the polyacetal resin (I) is dissolved in a solvent and then the components (II) to (IV) are added and mixed to remove the solvent. The polyacetal resin (I) A method of adding and mixing the above components (II) to (IV) to the heated melt of, a method of adding calcium carbonate (II) and a coupling agent (III) prepared in advance, and an organic acid (IV) as a master batch, Or the method of combining these is not particularly limited.
Among these, as a preferable production method from the viewpoint of excellent productivity, a method of adding and mixing calcium carbonate (II), a coupling agent (III), and an organic acid (IV) to a heated melt of the polyacetal resin (I), That is, a melt kneading method can be mentioned.

Here, in the melt kneading method, the method for adding the polyacetal resin (I), calcium carbonate (II), coupling agent (III), and organic acid (IV) is not particularly limited. For example, a slurry in which calcium carbonate (II) is dispersed in a solvent such as water is brought into contact with stirring with a stock solution of the coupling agent (III) or a solution such as water or alcohol and an organic acid (IV). A method of melt-kneading with polyacetal resin (I) after surface treatment in advance by a wet treatment method, a coupling agent (III) stock solution, or a solution such as water or alcohol for calcium carbonate (II) powder, and A method in which an organic acid (IV) is added, mixed with a Henschel mixer, etc., and subjected to surface treatment by a dry treatment method in which the mixture is stirred, and then melt-kneaded with the polyacetal resin (I). After adding and adhering coupling agent (III) and organic acid (IV), add calcium carbonate (II) and add. Examples include a method of performing melt kneading, a method of mixing and adhering calcium carbonate (II), a coupling agent (III), and an organic acid (IV) to the polyacetal resin (I), followed by heat melting and kneading. Can do.
The above methods may be used alone or in combination.

  Here, from the viewpoint of excellent mechanical properties of the obtained polyacetal resin composition, preferably calcium carbonate (II) is subjected to surface treatment with a coupling agent (III) and an organic acid (IV) in advance. From the viewpoint of efficiency, dry surface treatment is preferred.

  When manufacturing by the said melt-kneading, the kneader generally put into practice can be applied as the apparatus. For example, a single-screw or multi-screw kneading extruder, a roll, a Banbury mixer, etc. may be used. Among these, a twin-screw extruder equipped with a decompression device and side feeder equipment is most preferable. Here, the melt-kneading conditions are not particularly limited, but the degree of reduced pressure is preferably 0 to 0.07 Mpa. The kneading temperature is preferably 1 to 100 ° C. higher than the melting point or softening point obtained by differential scanning calorimetry (DSC) measurement according to JISK7121. More specifically, it is 180 ° C to 240 ° C.

The shear rate in the kneader is preferably 100 (SEC ⁻¹ ) or more, and the average residence time during kneading is preferably 1 to 15 minutes. The solvent in the resin composition is preferably 1% by mass or less. If it is in the said range, it exists in the tendency which is excellent in productivity and suppresses discoloration of the obtained polyacetal resin composition, and can obtain the resin composition excellent in rigidity, toughness, heat resistance, and acid resistance.

  In the present invention, a suitable known additive can be further blended as necessary within the range not impairing the object of the present invention. Specifically, antioxidants, heat stabilizers, anti-glare (light) stabilizers, mold release (lubricants), crystal nucleating agents, inorganic fillers, conductive materials, thermoplastic resins, thermoplastic elastomers, pigments, etc. I can give you.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not restrict | limited to a following example. The evaluations described in the following examples and comparative examples were carried out by the following methods.

(1) Melt flow index (MFI: g / 10 min)
Measurement was performed under conditions of 190 ° C. and 2160 g using a MELT INDEXER manufactured by Toyo Seiki Co., Ltd. according to ASTM-D1238.

(2) Scanning electron microscope (SEM) observation The following apparatus was used for observation of the average particle diameter, average aspect ratio (measurement of average major axis and average minor axis) and shape of calcium carbonate particles.
Fine coater: JFC-1600 manufactured by JEOL Ltd.
The coating conditions were 30 mA and 60 seconds.
Scanning electron microscope: JSM-6700F manufactured by JEOL Ltd.
The measurement conditions were an acceleration voltage of 9.00 kV and an applied current of 10.0 μA.
The average particle diameter was determined according to the formula: average particle diameter = average major axis = ΣLi ² Ni / ΣLiNi by measuring the major axis of at least 100 particles randomly selected from the obtained particle image. The average aspect ratio was determined according to the following formula by measuring the major axis and minor axis of at least 100 particles randomly selected from the obtained particle images.
Average major axis = ΣLi ² Ni / ΣLiNi
Average minor axis = ΣDi ² Ni / ΣDiNi
Average aspect ratio L / D = (ΣLi ² Ni / ΣLiNi) / (ΣDi ² Ni / ΣDiNi)

(3) Determination of Ca, Na, Sr in calcium carbonate and calculation of the amount of Na, Sr with respect to Ca 0.5 g of calcium carbonate is weighed in a platinum dish and carbonized in a 500 ° C. electric furnace. After cooling, add 5 mL of hydrochloric acid and 5 mL of pure water, and boil and dissolve on a heater. After cooling again, pure water was added to obtain a measurable concentration, and quantification was performed according to the characteristic wavelength of each metal by high frequency inductively coupled plasma (ICP) emission analysis using IRIS / IP manufactured by Thermo Jarrel Ash. Thereafter, calculation of the amount of Na and Sr with respect to Ca was calculated.

(4) Physical properties of the resin composition Using an injection molding machine (SH-75 manufactured by Sumitomo Heavy Industries, Ltd.), the cylinder temperature was set to 200 ° C., the mold temperature was set to 70 ° C., and the injection was performed for 15 seconds and cooled for 25 seconds. Dumbbell pieces and strips for evaluation were obtained under injection molding conditions, and various physical properties were measured as follows.

(4-1) Flexural modulus (GPa) and flexural strength (MPa)
This was performed according to ASTM D790.
(4-2) Tensile elongation (%) and tensile strength (MPa)
This was performed according to ASTM D638.
(4-3) Izod impact strength with notch It was performed according to ASTM D256.
(4-4) High load deflection temperature (1.82 MPa)
The dumbbell pieces were aged at 150 ° C. for 3 hours and then left at 23 ° C. and 50% RH for 48 hours. Then, it carried out according to ASTM D648.

(4-5) Measurement of formaldehyde generation rate (ppm / min.) 3 g of a pellet of a polyacetal resin composition that had been previously dried at 140 ° C. for 1 hour was heated and melted at 220 ° C. under a nitrogen stream (50 NL / hr). The generated formaldehyde was absorbed in water and titrated by the sodium sulfite method. At that time, the formaldehyde generation amount (ppm) from the start of heating to 2 minutes later was S ₂ , 10 minutes was S ₁₀ , 30 minutes was S ₃₀ , 50 minutes was S ₅₀ , and 90 minutes was S ₉₀ . sometimes,
Generation rate for 2 to 10 minutes: (S ₁₀ -S ₂ ) / 8 (ppm / min.)
Generation rate from 10 minutes to 30 minutes: (S ₃₀ -S ₁₀ ) / 20 (ppm / min.)
Generating a rate of 50 minutes to 90 _{minutes: (S 90 -S 50) /} 40 (ppm / min.)
Calculated as These values are attributed to formaldehyde adhering to the polyacetal resin composition, attributed to formaldehyde generated by terminal decomposition of the polyacetal resin, and attributed to formaldehyde generated from main chain decomposition of the polyacetal resin. Among these, the generation rate due to formaldehyde generated by terminal decomposition and main chain decomposition is effective as an index of the thermal stability inherent in the resin composition.

Moreover, the following component was used for the Example and the comparative example.
<Resin>
Asahi Kasei Chemicals Co., Ltd. polyacetal resin Tenac (registered trademark) HC450 65 parts by mass and Asahi Kasei Chemicals Co., Ltd. polyacetal resin Tenac (registered trademark) HC750 were mixed in pellets. The MFI was 15 (g / 10 min).

<Calcium carbonate>
(A-1) Brilliant-15 manufactured by Shiroishi Kogyo Co., Ltd.
Light calcium carbonate Content of Na to Ca 50ppm
Content of Sr with respect to Ca 820ppm
(A-2) Caltex 5 manufactured by Maruo Calcium Co., Ltd.
Heavy calcium carbonate Content of Na to Ca 30ppm
Content of Sr to Ca 330ppm
(A-3) PC made by Shiroishi Kogyo Co., Ltd.
Light calcium carbonate Content of Na to Ca 30ppm
Content of Sr with respect to Ca 790ppm
(A-4) Silver W made by Shiroishi Kogyo Co., Ltd.
Light calcium carbonate Content of Na to Ca 30ppm
Content of Sr with respect to Ca 1030ppm
(A-5) Maruo Calcium Co., Ltd. Super S
Heavy calcium carbonate Content of Na to Ca 15ppm
Content of Sr with respect to Ca 410ppm
(A-6) R heavy coal manufactured by Shiroishi Kogyo Co., Ltd.
Heavy calcium carbonate Content of Na to Ca 15ppm
Content of Sr with respect to Ca 410ppm

<Silane coupling agent>
(B-1) Shin-Etsu Silicone KBE-9007 3-isocyanatopropyltriethoxysilane (b-2) Shin-Etsu Silicone KBM-603 N-2 (aminomethyl) 3-aminopropyltrimethoxysilane ( b-3) Shin-Etsu Silicone Co., Ltd. KBM-403 3-Glydoxypropyltriethoxysilane (b-4) Shin-Etsu Silicone Co., Ltd. KBM-503 3-Methacryloxypropyltrimethoxysilane <Organic Acid>
Stearic acid (F-3 manufactured by Kawaken Fine Chemical Co., Ltd.)

[Production Examples 1 to 8 of surface-treated calcium carbonate]
Calcium carbonate powder, silane coupling agent, and organic acid were blended in the blending amounts shown in Table 1, and the mixture was stirred and mixed in a Henschel mixer at 120 ° C. and 2000 rpm for 15 minutes in a Henschel mixer. Obtained calcium.

[Examples 1 to 16 and Comparative Examples 1 to 6]
Each component was weighed and mixed in the ratios shown in Tables 2 to 4, and added and melt-kneaded from the top of the extruder using a twin screw extruder (PCM-30 manufactured by Ikegai Co., Ltd.). A resin composition was obtained. At that time, the melt-kneading conditions were a temperature of 200 ° C. and a rotation speed of 200 rpm. The evaluation results are shown in Tables 2-4.
As is apparent from Tables 2 to 4, it can be seen that the polyacetal resin composition of the present invention is excellent in the balance of mechanical properties such as rigidity, strength, toughness, heat resistance and the like, and further in thermal stability.

  Since the polyacetal resin composition obtained in the present invention is excellent in the balance of mechanical properties such as rigidity, strength, toughness, heat resistance and thermal stability, it can be suitably used in fields such as automobiles, electrical and electronic industries, and other industries. .

Claims (10)

  The average particle diameter is 0.01 μm or more and less than 1.5 μm with respect to 100 parts by mass of the polyacetal resin (I), and the average is the ratio of the average major axis (L) of the particles to the average minor axis (D) of the particles 0.1 to 100 parts by mass of calcium carbonate (II) having an aspect ratio (L / D) of 3 or less, 0.001 to 10 parts by mass of coupling agent (III), 0.001 to 10 parts by mass of organic acid (IV) The polyacetal resin composition formed by blending parts. The BET adsorption amount of calcium carbonate (II) is X ₁ (m ² / g), its mass is X ₂ , the minimum covering area of the coupling agent (III) is Y ₁ (m ² / g), and its mass is Y _2. The polyacetal resin composition according to claim 1, wherein the following relationship is satisfied, where Z ₁ (m ² / g) is the minimum covering area of the organic acid (IV) and the mass is Z ₂ .
50 ≦ (Y ₁ Y ₂ + Z ₁ Z ₂ ) / X ₁ X ₂ × 100 ≦ 200
10 ≦ Y ₁ Y ₂ / (Y ₁ Y ₂ + Z ₁ Z ₂ ) × 100 ≦ 90   The polyacetal resin composition according to claim 1 or 2, wherein the calcium carbonate (II) is light calcium carbonate.   The polyacetal resin composition according to any one of claims 1 to 3, wherein an average particle size of calcium carbonate (II) is 0.01 µm to 1.0 µm. The polyacetal resin composition according to any one of claims 1 to 4, wherein calcium carbonate (II) is 6 to ²⁰⁰ m ² / g in a BET specific surface area. The polyacetal resin composition according to any one of claims 1 to 5, wherein calcium carbonate (II) has a content of particles having a particle diameter of 1 µm or less of 90% or more.   7. The polyacetal resin composition according to claim 1, wherein in calcium carbonate (II), the amount of Na relative to Ca is 250 ppm or less.   The polyacetal resin composition according to any one of claims 1 to 7, wherein an amount of Sr with respect to Ca is 500 to 2500 ppm in calcium carbonate (II).   The polyacetal resin composition according to any one of claims 1 to 8, wherein the coupling agent (III) is a silane coupling agent. 10. The coupling agent (III) is at least one selected from the group consisting of compounds represented by the following general formula and / or a polycondensate thereof: Polyacetal resin composition.
(R ₁ O) _l SiR _2m C ₃ H ₆ NHC ₂ H ₄ NH ₂
(R ₁ O) _l SiR _2m C ₃ H ₆ NH ₂
(R ₁ O) _l SiR _2m C ₃ H ₆ NCO
Here, l + m = 3, l, m is a number selected from 0 to 3, R ₁ and R ₂ are hydrogen or a saturated or unsaturated hydrocarbon group, and the hydrocarbon group has a functional group. It may be introduced.