JP7547015B2 - Dispersant for inorganic fibers - Google Patents

Description

The present invention relates to a dispersant for inorganic fibers.

In order to improve the mechanical and thermal properties of polyolefin resins, inorganic fibers have been mixed into the resins. However, since the affinity between polyolefin resins and inorganic fibers is low, there are problems with moldability, mechanical strength, etc., and various improvement measures have been proposed. For example,
A method has been proposed in which inorganic fibers are coated with a polyolefin resin in advance and then mixed with the polyolefin resin (see, for example, Patent Document 1).

Japanese Patent Application Publication No. 6-16883

However, while the method of coating inorganic fibers with a polyolefin resin beforehand and then mixing with the polyolefin resin improves the dispersibility of inorganic fibers, it is still not sufficient and there is a problem of poor mechanical strength, and improvement is urgently needed. The object of the present invention is to provide a dispersant for inorganic fibers that has excellent dispersibility of inorganic fibers.

The present inventors have conducted studies to achieve the above object, and have arrived at the present invention. That is, the present invention relates to an inorganic fiber dispersant containing an acid-modified polyolefin (X) containing a polyolefin (A) and an unsaturated (poly)carboxylic acid (anhydride) (B) as constituent raw materials, the (A) containing ethylene and an α-olefin (having 3 to 8 carbon atoms) as constituent monomers, the weight ratio of the ethylene to the α-olefin [ethylene/α-olefin] being 3/97 to 50/50 , and the acid-modified polyolefin (X) has an isotacticity of 1 to 50% in the α-olefin portion (Y) .

The dispersant for inorganic fibers (Y) of the present invention has the following effects.
(1) Excellent dispersibility of inorganic fibers.
(2) It imparts excellent mechanical strength (impact resistance, etc.) to a molded article of the inorganic fiber-containing polyolefin resin composition (Z).
(3) It imparts excellent moldability to the inorganic fiber-containing polyolefin resin composition (Z).

<Polyolefin (A)>
The polyolefin (A) in the present invention contains ethylene and an α-olefin (having 3 to 8 carbon atoms) as constituent monomers.
Examples of the α-olefin include propylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, and 1-octene.
Although two or more kinds of α-olefins may be used in combination, it is preferable to use one kind.
Among the above α-olefins, propylene is preferred from the viewpoints of mechanical strength and industrial applicability.
Among the (A) resins, from an industrial viewpoint, ethylene/propylene copolymers are preferred.

The weight ratio of ethylene to an α-olefin (having 3 to 8 carbon atoms) which is a constituent monomer of the polyolefin (A) [ethylene/α-olefin] is 3/97 to 50/50, preferably 5/95 to 40/60, and more preferably 10/90 to 30/70.
If the weight ratio [ethylene/α-olefin] is less than 3/97, the dispersibility is poor, and if it exceeds 50/50, the mechanical strength is poor.
The weight ratio [ethylene/α-olefin] can be calculated, for example, by ¹ H-MNR.

The (A) may contain other monomers as constituent monomers in addition to ethylene and α-olefins. In that case, the weight of the other monomers is preferably 10% by weight or less, more preferably 5% by weight or less, and particularly preferably 1% by weight or less, based on the weight of all the monomers constituting the (A).
Examples of the other monomers include 2-butene, isobutene, α-olefins having a carbon number (sometimes abbreviated as C) of 9 to 30 (1-decene, 1-dodecene, etc.), and unsaturated monomers having a carbon number of 4 to 30 (for example, vinyl acetate).

From the viewpoints of mechanical strength, dispersibility, and moldability, the number average molecular weight (Mn) and weight average molecular weight (Mw) of the polyolefin (A) are preferably 800 to 50,000, more preferably 1,500 to 40,000, and particularly preferably 2,000 to 30,000.

In the present invention, the conditions for measuring Mn and weight average molecular weight (Mw) by GPC (gel permeation chromatography) are as follows.
Apparatus: High temperature gel permeation chromatograph
["Alliance GPC V2000", manufactured by Waters Corporation]
Detector: Refractive index detector Solvent: Orthodichlorobenzene Reference material: Polystyrene Sample concentration: 3 mg/ml
Column stationary phase: PLgel 10 μm, MIXED-B 2 columns in series
[Manufactured by Polymer Laboratories, Inc.]
Column temperature: 135°C

The number of double bonds per 1,000 carbon atoms in the polyolefin (A) [the number of carbon-carbon double bonds at the molecular terminals and/or in the molecular chain of (A)] is preferably 1 to 20, more preferably 1.5 to 18, and particularly preferably 2 to 15, from the viewpoints of reactivity with the (poly)carboxylic acid (anhydride) (B) described below and productivity.
Here, the number of double bonds can be determined from the ^1H -NMR (nuclear magnetic resonance) spectroscopy spectrum of (A). That is, the peaks in the spectrum are assigned, and the relative value between the number of double bonds in (A) and the number of carbon atoms in (A) is determined from the integral value derived from the double bonds in (A) at 4.5 to 6 ppm and the integral value derived from (A), and the number of double bonds in the molecular terminal and/or molecular chain per 1,000 carbons in (A) is calculated. The number of double bonds in the examples described later follows this method.

The isotacticity of the α-olefin portion of the polyolefin (A) is preferably 1 to 50%, more preferably 5 to 45%, and particularly preferably 10 to 40%, from the viewpoints of dispersibility, mechanical strength and moldability.
The isotacticity of the α-olefin portion of the polyolefin (A) tends to be directly reflected in the isotacticity of the α-olefin portion of the acid-modified polyolefin (X) described below.

The isotacticity can be calculated, for example, by using ¹³ C-NMR (nuclear magnetic resonance spectroscopy). It is generally known that a side chain methyl group is affected by the configuration (meso or racemo) of the methyl groups on both sides (triad), on both sides of the triad (pentad), and on both sides of the pentad (heptad), and peaks are observed at different chemical shifts. The stereoregularity is generally evaluated for the pentad, and the isotacticity in the present invention can also be calculated based on the evaluation of the pentad.
That is, when the α-olefin is propylene, the carbon peaks derived from the side chain methyl groups in propylene obtained by ^13C -NMR are taken as the peaks of each pentad (H), and the peaks derived from the methyl groups in isotactic propylene in which the pentad is formed only of a meso structure (Ha), the isotacticity is calculated by the following formula:
Isotacticity (%) = [(Ha) / Σ(H)] × 100 (1)
In the formula, H a is the peak height of an isotactic signal (pentads are formed only from mesostructures), and H is the height of each peak of the pentad.
The isotacticity of the α-olefin moiety of (X) described below can also be measured in the same manner as above.

The method for producing the polyolefin (A) in the present invention includes, for example, a method of thermally degrading a polyolefin (A0) having a high molecular weight (preferably Mn of 60,000 to 400,000, more preferably Mn of 80,000 to 250,000).

The thermal degradation method includes (1) a method of thermally degrading the polyolefin (A0) in the absence of an organic peroxide, for example, at 300 to 450° C. for 0.5 to 10 hours, and (2) a method of thermally degrading the polyolefin (A0) in the presence of an organic peroxide [for example, 2,5-dimethyl-2,5-di(t-butylperoxy)hexane], for example, at 180 to 300° C. for 0.5 to 10 hours.
Of these, from the industrial and dispersibility viewpoints, the method (1) is preferred, which can easily give a polymer having a larger number of double bonds at the molecular terminals and/or in the molecular chain.

The weight ratio [ethylene/α-olefin] of ethylene and α-olefin, which are monomers constituting the above (A), tends to be maintained the same as the weight ratio [ethylene/α-olefin] of the high molecular weight polyolefin (A0).
Furthermore, the higher the thermal degradation temperature and the longer the thermal degradation time, the larger the number of double bonds per 1,000 carbon atoms tends to be.
Furthermore, the larger the Mn of (A0), the higher the thermal degradation temperature, and the longer the thermal degradation time, the smaller the Mn of (A) tends to be.
In addition, the higher the isotacticity of (A0), the higher the isotacticity of (A) tends to be.

<Unsaturated (poly)carboxylic acid (anhydride) (B)>
The unsaturated (poly)carboxylic acid (anhydride) (B) in the present invention includes (poly)carboxylic acid (anhydrides) having one polymerizable unsaturated group and having 3 to 30 carbon atoms [hereinafter sometimes abbreviated as C].
In the present invention, the unsaturated (poly)carboxylic acid (anhydride) means an unsaturated monocarboxylic acid, an unsaturated polycarboxylic acid and/or an unsaturated polycarboxylic acid anhydride.
Among the (B), examples of the unsaturated monocarboxylic acid include aliphatic monocarboxylic acids (C3-24, e.g., acrylic acid, methacrylic acid, α-ethylacrylic acid, crotonic acid, isocrotonic acid), alicyclic monocarboxylic acids (C6-24, e.g., cyclohexene carboxylic acid); examples of the unsaturated poly(2-3 or more) carboxylic acids (anhydrides) include unsaturated dicarboxylic acids (anhydrides) [aliphatic dicarboxylic acids (anhydrides) (C4-24, e.g., maleic acid, fumaric acid, itaconic acid, citraconic acid, mesaconic acid, and anhydrides thereof), alicyclic dicarboxylic acids (anhydrides) (C8-24, e.g., cyclohexene dicarboxylic acid, cycloheptene dicarboxylic acid, bicycloheptene dicarboxylic acid, methyltetrahydrophthalic acid, and anhydrides thereof)], etc. (B) may be used alone or in combination of two or more.
Among the above (B), from the viewpoints of reactivity with the polyolefin (A) and dispersibility, unsaturated dicarboxylic acid anhydrides are preferred, and maleic anhydride is more preferred.

<Acid-modified polyolefin (X)>
The acid-modified polyolefin (X) in the present invention contains the polyolefin (A) and the unsaturated (poly)carboxylic acid (anhydride) (B) as constituent raw materials (constituent units). Preferably, the polyolefin (A) and the unsaturated (poly)carboxylic acid (anhydride) (B) are reacted in the absence or presence of a radical initiator.

From the viewpoint of the balance between dispersibility and mechanical strength, the weight ratio of (A) to (B) [(A)/(B)] is preferably 80/20 to 99.5/0.5, and more preferably 90/10 to 99/1.

The acid-modified polyolefin (X) can be preferably produced by reacting the polyolefin (A) and the unsaturated (poly)carboxylic acid (anhydride) (B) with an appropriate organic solvent [C3 to C18, for example, hydrocarbons (hexane, heptane, octane, dodecane, benzene, toluene, xylene, etc.), halogenated hydrocarbons (di-, tri-, or tetrachloroethane, dichlorobutane, etc.), ketones (acetone, methyl ethyl ketone, di-t-butyl ketone, etc.), ethers (ethyl-n-propyl ether, di-n-butyl ether, di-t-butyl ether, dioxane, etc.)], if necessary, in the presence of a radical initiator (f).
The radical initiator (f) may be a known one, for example, an azo initiator (azobisisobutyronitrile, etc.) or a peroxide initiator (dicumyl peroxide, etc.).
Of the above (f), peroxide initiators are preferred.

From the viewpoint of the reactivity of (A) and (B) and productivity, the reaction temperature is preferably 100 to 270°C, more preferably 120 to 250°C, and particularly preferably 130 to 240°C.

The acid-modified polyolefin (X) preferably satisfies one of the following requirements (1) to (3), more preferably two of the requirements, and particularly preferably three of the requirements:
(1) Acid value is 1 to 100 mgKOH/g
(2) Number average molecular weight (Mn) of 1,000 to 60,000
(3) Isotacticity of the α-olefin portion is 1 to 50%

Requirement (1):
From the viewpoint of mechanical strength and productivity of (X), the acid value of (X) is preferably 1 to 100 mgKOH/g (hereinafter, only numerical values are shown), more preferably 3 to 75, and particularly preferably 5 to 50. The acid value here is a value obtained by measuring in accordance with JIS K0070 according to the following procedures (i) to (iii).
(i) 1 g of (X) is dissolved in 100 g of xylene adjusted to 100° C.
(ii) After cooling to 70°C, titration [titration rate: 2 mL/min] is performed with a 0.1 mol/L ethanolic potassium hydroxide solution [product name "0.1 mol/L ethanolic potassium hydroxide solution", manufactured by Wako Pure Chemical Industries, Ltd.] at 70°C using phenolphthalein as an indicator.
(iii) The amount of potassium hydroxide required for the titration is converted into mg to calculate the acid value (unit: mgKOH/g).
In the above measurement, one acid anhydride group is equivalent to one carboxyl group. The acid value in the examples described later was measured according to this method.
The acid value can be appropriately adjusted by the number of double bonds in (A), the weight of (A), and the type and weight of (B).

Requirement (2):
From the viewpoints of mechanical strength, dispersibility and moldability, Mn of (X) is preferably 1,000 to 60,000, more preferably 2,000 to 50,000, and particularly preferably 3,000 to 40,000.
Moreover, Mn of (X) can be appropriately adjusted by controlling Mn of (A), the type and weight of (B), and the reaction between (A) and (B).

Requirement (3):
The isotacticity of the α-olefin portion of (X) is preferably 1 to 50%, more preferably 5 to 45%, and particularly preferably 10 to 40%, from the viewpoints of mechanical strength, dispersibility and moldability.
Furthermore, the isotacticity of the α-olefin portion of (X) can be appropriately adjusted by the isotacticity of (A) and (A0) as described above.
That is, the isotacticity of the α-olefin portion is the isotacticity of the α-olefin portion derived from the polyolefin (A) which is the raw material for the composition of (X).

<Dispersant for inorganic fibers (Y)>
The inorganic fiber dispersant (Y) of the present invention contains the acid-modified polyolefin (X). The (Y) may contain in advance an additive (G) which may be contained in the inorganic fiber-containing polyolefin resin composition (Z) described below.
The dispersant for inorganic fibers (Y) can be used as a dispersion for various inorganic fibers, but can be particularly suitably used as a dispersant for dispersing inorganic fibers (G) in a thermoplastic resin [particularly, a polyolefin resin (E)].

<Polyolefin resin (E)>
The polyolefin resin (E) in the present invention includes those obtained by the polymerization methods exemplified as the production methods of the above-mentioned (Y), or by the degradation (thermal, chemical and mechanical degradation) methods of high molecular weight polyolefins (preferably Mn 80,000 to 400,000). For example, the above-exemplified ethylene unit-containing (propylene unit-free) (co)polymers, propylene unit-containing (ethylene unit-free) (co)polymers, ethylene/propylene copolymers and (co)polymers of C4 or higher olefins are included.

As a combination of (E) and (X), from the viewpoint of compatibility between (E) and (X), it is preferable that the structural units of (E) and the structural units of the polyolefin (A) constituting (X) are the same or similar. For example, when (E) is a propylene unit-containing (ethylene unit-free) (co)polymer, it is preferable that (A) constituting (X) is also a propylene unit-containing (ethylene unit-free) (co)polymer.

The Mn of (E) is preferably 10,000 to 500,000, more preferably 20,000 to 400,000, from the viewpoints of the mechanical strength of the polyolefin resin substrate and compatibility with (X).

<Inorganic fiber (F)>
Examples of the inorganic fiber (F) in the present invention include glass fiber, carbon fiber, alumina fiber, ceramic fiber, rock fiber, slag fiber, stainless steel fiber, wollastonite, and silicon carbide fiber.
Among the above (F), carbon fibers and glass fibers are preferred from the viewpoint of the mechanical strength of the molded article. These fibers may be used alone or in combination of two or more.

Specific examples of glass fibers include glass roving, glass chopped strands, glass milled fibers, glass staples, and glass cloth.

Examples of carbon fibers include various known carbon fibers, such as carbon fibers made from polyacrylonitrile, rayon, pitch, and hydrocarbon gases, graphite fibers, and metal-coated carbon fibers obtained by coating these with metals such as nickel, aluminum, and copper. From the viewpoint of mechanical strength, polyacrylonitrile-based carbon fibers and metal-coated carbon fibers obtained by further coating these with a metal are preferred.

The shape of (F) is not particularly limited, but the fiber diameter of (F) is preferably 1 to 1,000 μm, more preferably 3 to 500 μm, from the viewpoint of the mechanical strength and moldability of the molded product. In addition, the fiber length of (F) is preferably 1 to 100 mm, more preferably 2 to 50 mm, from the viewpoint of the mechanical strength and moldability of the molded product.

<Inorganic fiber-containing polyolefin resin composition (Z)>
The inorganic fiber-containing polyolefin resin composition (Z) of the present invention contains the dispersant (Y), a polyolefin resin (E), and inorganic fibers (F).
In the resin composition, the proportion of each component based on the total weight of (Y), (E), and (F) is as follows: (Y) is preferably 0.1 to 15%, more preferably 0.5 to 12%, and particularly preferably 1 to 10%, from the viewpoints of dispersibility of (F) and mechanical strength of a molded article; (E) is preferably 30 to 98%, more preferably 40 to 85%, and particularly preferably 50 to 80%, from the viewpoints of productivity and mechanical strength of a molded article; and (F) is preferably 1 to 60%, more preferably 5 to 55%, and particularly preferably 10 to 50%, from the viewpoints of mechanical strength and productivity of a molded article.

In addition to the above-mentioned (X), (E), and (F), the inorganic fiber-containing polyolefin resin composition (Z) of the present invention may further contain various additives (G) as necessary within a range that does not impair the effects of the present invention.
Examples of (G) include one or more selected from the group consisting of colorants (G1), flame retardants (G2), fillers (G3), lubricants (G4), antistatic agents (G5), dispersants other than (X) (G6), antioxidants (G7) and ultraviolet absorbers (G8).

Colorants (G1) include pigments and dyes.
Examples of the pigment include inorganic pigments (alumina white, graphite, etc.); and organic pigments (azo lake type, etc.).
The dyes include azo dyes, anthraquinone dyes, and the like.

Examples of flame retardants (G2) include organic flame retardants (nitrogen-containing compounds [such as urea compounds and salts of guanidine compounds], sulfur-containing compounds [sulfuric acid esters, sulfamic acid, and their salts, esters, amides, etc.], silicon-containing compounds [polyorganosiloxanes, etc.], phosphorus-containing compounds [phosphate esters, etc.], etc.); inorganic flame retardants [antimony trioxide, magnesium hydroxide, aluminum hydroxide, ammonium polyphosphate, etc.], etc.

Examples of fillers (G3) include carbonates (magnesium carbonate, calcium carbonate, etc.), sulfates (aluminum sulfate, etc.), sulfites (calcium sulfite, etc.), metal sulfides (molybdenum disulfide, etc.), silicates (aluminum silicate, etc.), diatomaceous earth, silica powder, talc, silica, zeolite, wood materials (wood flour, etc.), and mixtures of these.

Lubricants (G4) include waxes (such as carnauba wax), higher fatty acids (such as stearic acid), higher alcohols (such as stearyl alcohol), higher fatty acid amides (such as stearic acid amide), etc.

Antistatic agents (G5) include nonionic, cationic, anionic and amphoteric surfactants as described below and in US Pat. Nos. 3,929,678 and 4,331,447.
(1) Nonionic surfactants: Alkylene oxide (hereinafter abbreviated as AO)-added nonionics, for example, (poly)oxyalkylene derivatives (AO adducts and higher fatty acid mono- and di-esters of polyalkylene glycols) of active hydrogen atom-containing compounds having hydrophobic groups (C8-24 or more) [saturated and unsaturated higher alcohols (C8-18), higher aliphatic amines (C8-24) and higher fatty acids (C8-24), etc.]; (poly)oxyalkylene derivatives of higher fatty acid (C8-24) esters of polyhydric alcohols (C3-60) (Tween-type nonionics, etc.); (poly)oxyalkylene derivatives of (alkanol)amides of higher fatty acids (above) (poly)oxyalkylene derivatives of polyhydric alcohol (above) alkyl (C3-60) ethers; and polyoxypropylene polyols [polyoxypropylene derivatives of polyhydric alcohols and polyamines (C2-10) (Pluronic®-type and Tetronic-type nonionics)]; polyhydric alcohol (above) type nonionics (e.g., fatty acid esters of polyhydric alcohols, polyhydric alcohol alkyl (C3-60) ethers, and fatty acid alkanolamides); and amine oxide type nonionics [e.g., (hydroxy)alkyl (C10-18) di(hydroxy)alkyl (C1-3) amine oxides].

(2) Cationic surfactants Quaternary ammonium salt type cationics [tetraalkylammonium salts (C11-100), alkyl (C8-18) trimethylammonium salts, dialkyl (C8-18) dimethylammonium salts, etc.]; trialkylbenzylammonium salts (C17-80) (lauryl dimethylbenzylammonium salts, etc.); alkyl (C8-60) pyridinium salts (cetyl pyridinium salts, etc.); (poly)oxyalkylene (C2-4) trialkylammonium salts (C12-100) (polyoxyethylene lauryl dimethylammonium salts, etc.); and acyl (C8-18) aminoalkyl (C2-4) or acyl (C8-18) oxyalkyl (C2-4) tri[(hydroxy)alkyl (C1-4)] ammonium salts. (Sapamine-type quaternary ammonium salts) [These salts include, for example, salts of halides (chloride, bromide, etc.), alkyl sulfates (methosulfate, etc.) and organic acids (described below)]; and amine salt-type cationics: inorganic acid (hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid, etc.) salts and organic acid (C2-22) salts of primary to tertiary amines [for example, higher aliphatic amines (C12-60), polyoxyalkylene derivatives [ethylene oxide (hereinafter abbreviated as EO) adducts, etc.] of aliphatic amines (methylamine, diethylamine, etc.), and acylaminoalkyl or acyloxyalkyl (above) di(hydroxy)alkyl (above) amines (stearoyloxyethyl dihydroxyethylamine, stearamidoethyl diethylamine, etc.)].

(3) Anionic Surfactants Higher fatty acid (above) salts (sodium laurate, etc.), ether carboxylic acids [carboxymethylated products of EO (1 to 10 moles) adducts, etc.] and their salts; sulfates (alkyl and alkyl ether sulfates, etc.), sulfated oils, sulfated fatty acid esters, and sulfated olefins; sulfonates [alkylbenzenesulfonates, alkylnaphthalenesulfonates, dialkyl sulfosuccinates, α-olefin (C12-18) sulfonates, N-acyl-N-methyltaurines (Igepon T type, etc.), etc.]; and phosphates (alkyl, alkyl ether, and alkylphenyl ether phosphates, etc.).

(4) Amphoteric surfactants:
Carboxylic acid (salt) type amphoterix [amino acid type amphoterix (laurylaminopropionic acid (salt) etc.), and betaine type amphoterix (alkyl dimethyl betaine, alkyl dihydroxyethyl betaine etc.)]; sulfate ester (salt) type amphoterix [laurylamine sulfate ester (salt), hydroxyethyl imidazoline sulfate ester (salt), etc.]; sulfonic acid (salt) type amphoterix [pentadecylsulfotaurine, imidazoline sulfonic acid (salt), etc.]; and phosphate ester (salt) type amphoterix, etc. [glycerol laurate phosphate ester (salt), etc.].

The salts of the above anionic and amphoteric surfactants include metal salts, such as salts of alkali metals (lithium, sodium, potassium, etc.), alkaline earth metals (calcium, magnesium, etc.) and Group IIB metals (zinc, etc.); ammonium salts; as well as amine salts and quaternary ammonium salts.

Examples of dispersants (G6) include polymers with Mn of 1,000 to 20,000, such as vinyl resins (polyolefins (polyethylene, polypropylene, etc.), modified polyolefins (oxidized polyethylene (polyethylene oxidized with ozone, etc., to which carboxyl groups, carbonyl groups, and/or hydroxyl groups, etc., have been introduced) and vinyl resins other than the above polyolefins (polyvinyl halides (polyvinyl chloride, polyvinyl bromide, etc.), polyvinyl acetate, polyvinyl alcohol, polymethyl vinyl ether, poly(meth)acrylic acid, poly(meth)acrylic acid esters (polymethyl (meth)acrylate, etc.), and styrene resins (polystyrene, acrylonitrile/styrene (AS) resin, etc.)); polyester resins (polyethylene terephthalate, etc.), polyamide resins (nylon 6,6, nylon 12, etc.), polyether resins (polyethersulfone, etc.), polycarbonate resins (polycondensates of bisphenol A and phosgene, etc.), and block copolymers thereof.

Antioxidants (G7) include hindered phenol compounds [p-t-amylphenol-formaldehyde resin, nordihydroguaiaretic acid (NDGA), 2,6-di-t-butyl-4-methylphenol (BHT), 2-t-butyl-4-methylphenol (BHA), 6-t-butyl-2,4,-methylphenol (24M6B), 2,6-di-t-butylphenol (26B), etc.];

Sulfur-containing compounds [N,N'-diphenylthiourea, dimyristylthiodipropionate, etc.];

Examples of phosphorus-containing compounds include 2-t-butyl-α-(3-t-butyl-4-hydroxyphenyl)-p-cumenylbis(p-nonylphenyl)phosphite, dioctadecyl-4-hydroxy-3,5-di-t-butylbenzylphosphonate, etc.

Examples of ultraviolet absorbers (G8) include salicylate compounds (e.g., phenyl salicylate); benzophenone compounds (e.g., 2,4-dihydroxybenzophenone); and benzotriazole compounds (e.g., 2-(2'-hydroxy-5'-methylphenyl)-benzotriazole).

The total content of (G) in the inorganic fiber-containing polyolefin resin composition (Z) is, for example, 20% or less based on the total weight of the composition, and from the viewpoints of functional expression of each (G) and industrial considerations, is preferably 0.05 to 10%, and more preferably 0.1 to 5%.
The amount of each additive used based on the total weight of the composition is, for example, 5% or less, preferably 0.1 to 3% for (G1); 8% or less, preferably 1 to 3% for (G2); 5% or less, preferably 0.1 to 1% for (G3); 8% or less, preferably 1 to 5% for (G4); 8% or less, preferably 1 to 3% for (G5); 1% or less, preferably 0.1 to 0.5% for (G6); 2% or less, preferably 0.1 to 0.5% for (G7); 2% or less, preferably 0.05 to 0.5% for (G8).

When additives overlap among the above (G1) to (G8), each additive should not be used in the amount that produces the corresponding additive effect, but should be adjusted according to the purpose of use, taking into consideration that the effects of other additives can also be obtained at the same time.

The method for producing the inorganic fiber-containing polyolefin resin composition (Z) of the present invention includes the following steps:
(1) A method in which the (Y), (E), (F) and, if necessary, (G) are mixed together in a lump to obtain an inorganic fiber-containing polyolefin resin composition (Z) (lump method);
(2) A method (masterbatch method) in which a part of (E), the whole of (Y), and, if necessary, a part or the whole of (G) are mixed to prepare a masterbatch polyolefin resin composition containing a high concentration of (Y), and then the remaining (E), (F), and, if necessary, the remaining (G) are added and mixed to obtain an inorganic fiber-containing polyolefin resin composition (Z) is also included.
From the viewpoint of the mixing efficiency of (Y), the method (2) is preferred.

Specific mixing methods in the production method of the inorganic fiber-containing polyolefin resin composition (Z) include the following:
(i) A method in which the components to be mixed are mixed using, for example, a powder mixer ("Henschel Mixer" [product name "Henschel Mixer FM150L/B", manufactured by Mitsui Mining Co., Ltd., which has since changed its name to Nippon Coke and Engineering Co., Ltd.], "Nauter Mixer" [product name "Nauter Mixer DBX3000RX", manufactured by Hosokawa Micron Corporation], "Banbury Mixer" [product name "MIXTRON BB-16MIXER", manufactured by Kobe Steel, Ltd.], etc.) and then kneaded using a melt kneading device [batch kneader, continuous kneader (single-screw kneader, twin-screw kneader, etc.)] at usually 120 to 220° C. for 2 to 30 minutes;
(ii) The components to be mixed are directly kneaded under the same conditions using the same melt kneading apparatus as above, without previously mixing the components in powder form.
Among these methods, method (i) is preferred from the viewpoint of mixing efficiency.

The inorganic fiber-containing polyolefin composition (Z) of the present invention has excellent dispersibility of inorganic fibers, and the molded product described below has excellent mechanical strength. The mechanical strength of the molded product can be evaluated based on the impact resistance described below. On the other hand, the dispersibility of inorganic fibers can be evaluated based on the affinity between the polyolefin resin (E) and the inorganic fibers (F) described below. In addition, the moldability was evaluated by visually inspecting the mold after molding.

<Molded products, molded articles>
The molded article of the present invention is produced by molding the inorganic fiber-containing polyolefin resin composition (Z).
Examples of molding methods include injection molding, compression molding, calendar molding, slush molding, rotational molding, extrusion molding, blow molding, and film molding (casting method, tenter method, inflation method, etc.). The molding can be carried out by any method including molding, multi-layer molding, foam molding, etc. The molded product may be in the form of a plate, sheet, film, fabric, fiber (including nonwoven fabric, etc.), etc.

The molded article of the present invention has excellent mechanical strength and also has good paintability and printability, and a molded article can be obtained by painting and/or printing the molded article.
Methods for coating the molded product include, for example, air spray coating, airless spray coating, electrostatic spray coating, dip coating, roller coating, brush coating, and the like, but are not limited to these.
Examples of paints include paints that are generally used for painting plastics, such as polyester melamine resin paints, epoxy melamine resin paints, acrylic melamine resin paints, and acrylic urethane resin paints. These paints, which are so-called relatively highly polar, as well as paints with low polarity (olefin-based, etc.) can be used.
The coating film thickness (dry film thickness) can be appropriately selected depending on the purpose, but is usually 10 to 50 μm.

As a method for printing on the molded article or on a molded article after coating, any printing method generally used for printing on plastics can be used, such as gravure printing, flexographic printing, screen printing, pad printing, dry offset printing, and offset printing.
As the printing ink, those usually used for printing on plastics, such as gravure ink, flexo ink, screen ink, pad ink, dry offset ink and offset ink, can be used.

The dispersant for inorganic fibers (Y) of the present invention has excellent dispersibility of inorganic fibers, and molded articles of the inorganic fiber-containing polyolefin resin composition (Z) have excellent mechanical strength (impact resistance, etc.) and moldability.
Therefore, it can be suitably used for various polyolefin molded products.

The present invention will be further explained below with reference to examples and comparative examples, but the present invention is not limited to these. Unless otherwise specified, % means % by weight and parts means parts by weight.

<Production Example 1>
A reaction vessel was charged with 1,000 g of a polyolefin (A0-1) having structural units of 85% propylene and 15% ethylene [product name "Vistamaxx 6202", manufactured by Exxon Mobil, the same applies below], which was heated and melted using a mantle heater while aerating nitrogen into the liquid phase, and thermally degraded at 380°C for 50 minutes with stirring, to obtain polyolefin (A-1).
The polyolefin (A-1) had an Mn of 3,900, the number of double bonds at the molecular terminals and/or in the molecular chain per 1,000 carbons was 7.4, and the isotacticity was 17%.

<Production Examples 2 to 9, Comparative Production Example 1>
Each polyolefin (A) was obtained in the same manner as in Production Example 1, except for following Table 1. The results are shown in Table 1.

Example 1
A reaction vessel was charged with 100 parts of (A-1) and 5 parts of maleic anhydride (B-1), and after replacing with nitrogen, the mixture was heated to 180°C under nitrogen aeration to dissolve uniformly. A solution of 2 parts of a radical initiator [dicumyl peroxide, trade name "Percumyl D", manufactured by NOF Corp.] (f-1) dissolved in 5 parts of xylene was added dropwise thereto over 5 minutes, and stirring was continued for 1 hour under reflux of xylene. Thereafter, unreacted maleic anhydride was distilled off under reduced pressure (1.5 kPa, the same applies below) to obtain an inorganic fiber dispersant (Y-1) containing an acid-modified polyolefin (X-1).
Incidentally, (X-1) had an acid value of 26, an Mn of 4,500, and an isotacticity of 14%.

<Examples 2 to 15, Comparative Example 1>
Each inorganic fiber dispersant (Y) containing each acid-modified polyolefin (X) was obtained in the same manner as in Example 1, except that in Table 2, the results were as shown in Table 2.

<Examples 16 to 37 and Comparative Examples 11 to 15>
The obtained dispersant (Y) and the following raw materials used [polyolefin resin (E), inorganic fiber (F)] were each blended for 3 minutes in a Henschel mixer according to the composition (parts) in Table 3, and then melt-kneaded in a vented twin-screw extruder under conditions of 180°C, 100 rpm, and a residence time of 5 minutes to obtain an inorganic fiber-containing polyolefin resin composition (Z).
Each inorganic fiber-containing polyolefin resin composition (Z) was molded using an injection molding machine [product name "PS40E5ASE", Nissei Plastic Industrial Co., Ltd.] at a cylinder temperature of 190°C and a mold temperature of 60°C to prepare a predetermined test piece, which was then evaluated according to the evaluation method described below. The results are shown in Table 3.

The raw materials used in Table 3 are as follows.
<Ingredients used>
Polyolefin resin (E)
(E-1): Commercially available polypropylene [product name "Sunallomer PL500A",
Sanallomer Co., Ltd., Mn 300,000]
(E-2): Commercially available polyethylene [product name "Novatec HJ490",
Nippon Polyethylene Co., Ltd., Mn 300,000]
(E-3): Commercially available ethylene/propylene copolymer [product name "SunAllomer PB222A", manufactured by SunAllomer Co., Ltd.,
Mn 350,000

Inorganic fiber (F)
(F-1): Glass fiber [product name "FT157C", manufactured by Asahi Fiberglass Co., Ltd.,
(F-2): Carbon fiber [product name "TORAYCA T700SC-1200", manufactured by Toray Industries, Inc.,
Polyacrylonitrile type, fineness 800tex, filament count 12,000]
(F-3): Alumina fiber [product name "Denka Arsen Bulk", manufactured by Denka Co., Ltd.,
Fiber diameter 5 μm]
(F-4): Stainless steel fiber [product name "Naslon", manufactured by Yamanaka Sangyo Co., Ltd.,
Fiber diameter 8 μm] cut to fiber length 5 mm (F-5): Wollastonite [product name "Wollastonite", manufactured by Kansai Matec Co., Ltd.]
(F-6): Silicon carbide fiber [product name "Tyranno Fiber ZMI", manufactured by Ube Industries, Ltd.
Fineness 200tex, fiber diameter 11μm] cut to fiber length 5mm

<1> Impact resistance (unit: kJ/ ^m2 )
The Charpy impact value was measured in accordance with JIS K7111.

<2> Affinity between polyolefin resin (E) and inorganic fiber (F) After the test of <1> above, the fracture surface of the test piece was observed, and the affinity between (E) and (F) was evaluated according to the following evaluation criteria.
<Evaluation criteria>
◎: No interfacial peeling between (E) and (F) ○: Interfacial peeling between (E) and (F) but only partially △: Interfacial peeling between (E) and (F) is somewhat severe ×: Interfacial peeling between (E) and (F) is severe

<3> Moldability (resistance to mold contamination)
The obtained inorganic fiber-containing polyolefin resin composition (Z) was molded 100 times. After molding, the mold was visually inspected and evaluated according to the following criteria.
<Evaluation criteria>
◎: No change in the mold ○: Very little dirt on the mold △: Dirt can be seen on the mold ×: Heavy dirt on the mold

The results in Tables 1 to 3 show that the inorganic fiber dispersant of the present invention has superior inorganic fiber dispersibility compared to the comparative agents, and imparts excellent moldability to inorganic fiber-containing polyolefin resin compositions and excellent mechanical strength to molded articles.

The inorganic fiber dispersant of the present invention has excellent dispersibility of inorganic fibers, imparts excellent moldability to inorganic fiber-containing polyolefin resin compositions, and the molded products have excellent mechanical strength, making them highly useful in a wide range of fields, such as electrical and electronic equipment, transport materials, living materials, and building materials.

Claims (7)

An inorganic fiber dispersant comprising an acid-modified polyolefin (X) containing a polyolefin (A) and an unsaturated (poly)carboxylic acid (anhydride) (B) as constituent raw materials, the (A) containing ethylene and an α-olefin (having 3 to 8 carbon atoms) as constituent monomers, the weight ratio of the ethylene to the α-olefin [ethylene/α-olefin] being 3/97 to 50/50 , and the inorganic fiber dispersant (Y) wherein the isotacticity of the α-olefin portion of the acid-modified polyolefin (X) is 1 to 50% . 2. The dispersant (Y) for inorganic fibers according to claim 1, wherein the polyolefin (A) has 0.5 to 20 carbon-carbon double bonds per 1,000 carbon atoms. 3. The dispersant (Y) for inorganic fibers according to claim 1 or 2, wherein the acid-modified polyolefin (X) has an acid value of 1 to 100 mgKOH/g. The dispersant (Y) for inorganic fibers according to any one of claims 1 to 3, wherein the acid-modified polyolefin (X) has a number average molecular weight (Mn) of 1,000 to 60,000. 5. An inorganic fiber-containing polyolefin resin composition (Z) comprising the inorganic fiber dispersant (Y) according to any one of claims 1 to 4 , a polyolefin resin (E), and inorganic fibers (F). The inorganic fiber-containing polyolefin resin composition (Z) according to claim 5, wherein the proportions based on the total weight of ( Y) , (E), and (F) are 0.1 to 15% for (Y), 30 to 98% for (E), and 1 to 60% for (F). A molded article obtained by molding the inorganic fiber-containing polyolefin resin composition (Z) according to claim 5 or 6 .