JP3169548B2 - Polyacetal resin composition and molded article thereof - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyacetal resin composition having excellent moldability, especially blow moldability, extrudability and physical properties, and a molded article thereof.

[0002]

2. Description of the Related Art Polyacetal resin has excellent balance of mechanical properties, chemical resistance, slidability, etc., and is easy to process, so that it is a typical engineering plastic. Are widely used mainly for various mechanical parts, but most of them are injection molded products. On the other hand, in recent years, by utilizing the chemical resistance of polyacetal resin, especially the excellent resistance to organic solvents, etc., irregular shapes such as hollow parts related to automobile fuel tanks or engine rooms, various containers, nibs, and induction cores. Expectations for application to parts having a cross section are increasing. In general, blow molding is used for the production of such hollow molded parts, and extrusion is used as an efficient means for producing parts having an irregular cross section. In order to improve the drawability at the time of molding, the breakability at the time of blowing, and the prevention of uneven thickness, it is generally necessary to increase the melt tension of the resin. Holia acetal resin is also possible for relatively low molecular weight and low viscosity for general molding such as injection molding,
The melt tension is low for blow molding and extrusion molding, and the molding is extremely difficult. Therefore, there is an example of forming a branched or cross-linked structure in the molecule of the polyacetal resin to improve the melt tension of the resin.However, simply forming a branched or cross-linked structure does not sufficiently improve the melt tension. Further, in order to obtain a sufficient melt tension, it is necessary to further increase the molecular weight and increase the degree of branching / crosslinking. In this case, the flowability is deteriorated, the molding efficiency is hindered, and the impact resistance is poor. Spot-like unevenness was likely to occur on the surface of the molded product, and poor appearance of the molded product was also a serious problem.

[0003]

SUMMARY OF THE INVENTION In view of the above circumstances, the present invention has a high melt tension which is important for blow molding and extrusion molding, has excellent blow moldability and extrudability, has a good appearance, and An object of the present invention is to provide a polyacetal resin composition excellent in impact resistance and a molded product thereof.

[0004]

Means for Solving the Problems As a result of intensive studies, the present inventors have found that a specific polyacetal resin composition can solve the above-mentioned problems, and have completed the present invention. That is, the present invention relates to an ionomer resin of a copolymer containing (A) a specific branched or crosslinked polyacetal resin of 90 to 99.9% by weight (based on A + B) and (B) an olefin and an α, β-unsaturated carboxylic acid. The present invention relates to a blow-molded or extruded polyacetal resin composition comprising 10 to 0.1% by weight (to A + B) (hereinafter sometimes simply referred to as an ionomer), and a molded article thereof.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the polyacetal resin composition of the present invention will be described. Branched or crosslinked polyacetal (A) used in the present invention, conventionally known oxymethylene units (-CH ₂ O-) as a main component are those having a branched or crosslinked structure, also oxymethylene units in the molecule obtained by introducing comonomers other than, Ru encompassed all others was introduced block component. The effects of the present invention cannot be obtained by using only linear polyacetal polymers and copolymers having substantially no branched or crosslinked structure which are generally widely used. The branched or crosslinked polyacetal resin used in the present invention has trioxane as a main monomer, and a cyclic ether or cyclic formal as a comonomer,
Further, it is a polyacetal resin copolymerized with a specific compound capable of forming a branched or crosslinked structure in the presence of a cationically active catalyst, for example, boron trifluoride or a coordination compound thereof or various protonic acid catalysts. In addition, for the purpose of adjusting and stabilizing the molecular weight during polymerization, it is of course possible to use a chain transfer agent such as a low-molecular-weight linear acetal such as methylal having an alkoxy group at both ends without forming an unstable terminal. . Examples of the comonomer include a cyclic ether or cyclic formal such as ethylene oxide, propylene oxide, 1,3-dioxolan, 1,3-dioxane, 1,4
-One or more of butanediol formal, diethylene glycol formal, trioxepane and the like can be mentioned, and the use amount thereof is preferably in the range of 0.2 to 10% by weight based on trioxane. As the component capable of forming a branched or crosslinked structure, the polyfunctional compound is preferably having at least two epoxy rings, dioxolane such cyclic ether group or a cyclic formal group rings per molecule, these are 1 Species, or two or more species may be used in combination. Such polyfunctional compounds include, for example, ethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, 1,4-butanediol diglycidyl ether, hexamethylene glycol diglycidyl ether, resorcinol diglycidyl ether, bisphenol A diglycidyl ether, Diglycidyl ethers such as polyethylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether and polybutylene glycol diglycidyl ether; triglycidyl ethers such as glycerin triglycidyl ether and trimethylolpropane triglycidyl ether; tetraglycidyl such as pentaerythritol tetraglycidyl ether Ethers; or instead of glycidyl ether groups in the above example Compounds having a benzylidene glyceryl ether group and the like, bifunctional compound having two epoxy ring or dioxolane such cyclic ether group or a cyclic formal group rings per molecule among them is preferable. These compounds are used preferably in the range of 0.005 to 0.2% by weight, particularly preferably 0.01 to 0.15% by weight, based on trioxane. The amount of such branching or cross-linking components contributes to the melt tension and, together with the amount of the chain transfer agent, to control the shear viscosity (flowability) of the polymer. If its usage is less than 0.005% by weight,
It is difficult to obtain the properties of the present invention, such as melt tension, as a branched or crosslinked polyacetal.
If the amount is larger than the above range, a non-uniform gel-like substance is produced at the time of melting, so that a molded article is apt to cause spot-like unevenness, resulting in poor appearance, and also reduced impact resistance, which is not preferable. The branched or crosslinked polyacetal used in the present invention preferably has a melt index value (MI) of 0.05 to 10.0 g / 10 min. Where the melt index is ASTM D
It is a value measured at 190 ° C under a load of 2160 g according to -1238. When the melt index exceeds 10.0 g / 10 min, the melt tension of the composition is small, and the blow moldability and extrusion moldability are reduced. When the melt index is smaller than 0.05 g / 10 min, the flowability of the composition is reduced. However, neither is preferred.
Particularly preferred melt index of the branched or crosslinked polyacetal is 0.1 to 5.0 g / 10 min.

Next, the ionomer resin used in the present invention
(B) is a substance composed of a copolymer containing olefins and α, β-unsaturated carboxylic acids as basic components, and whose carboxylic acid groups form ionic crosslinks by metal ions.
The main components of the olefin constituting the ionomer are ethylene, propylene, ethylene-propylene and the like,
Particularly, ethylene is preferred. Examples of the α, β-unsaturated carboxylic acid component include one or more of α, β-unsaturated carboxylic acids having 3 to 8 carbon atoms, such as acrylic acid, methacrylic acid, itaconic acid, and fumaric acid. And acrylic acid and methacrylic acid are particularly preferred. Further, at least one kind of an alkyl ester of an α, β-unsaturated carboxylic acid having 3 to 8 carbon atoms such as methyl acrylate, ethyl acrylate, butyl acrylate, methyl methacrylate, butyl methacrylate, and dimethyl fumarate is used. A multicomponent copolymer or the like copolymerized as the third component may be used. Further, a part thereof may be modified with an amine or an amine complex ion. The content of the α, β-unsaturated carboxylic acid in these copolymers is preferably 0.5 to 15 mol%, particularly preferably 1 to 10 mol%, and the content of α, β-unsaturated carboxylic acid is When the alkyl ester is further copolymerized,
Its content is preferably from 0.2 to 15 mol%, particularly preferably from 0.5 to 10 mol%. The ionomer resin (B) used in the present invention is obtained by ion-cross-linking these olefins and the carboxylic acid group of the α, β-unsaturated carboxylic acid-based copolymer, and as the metal ion used for the ionic cross-linking,
Monovalent metal ions such as lithium, sodium, potassium and cesium; divalent metal ions such as magnesium, calcium, strontium, barium, copper and zinc; and trivalent metal ions such as aluminum and iron, among which lithium and sodium , Potassium, magnesium,
Calcium and zinc are particularly preferred.

The degree of cross-linking (degree of neutralization) by metal ions is determined in consideration of the melt index of the ionomer copolymer, the content of α, β-unsaturated carboxylic acid, the type of metal ion, and the like.
It is preferably from 10 to 100%, particularly preferably from 15 to 85%, based on all carboxylic acid groups. Typical examples of the commercially available ionomer (B) include Himilan manufactured by Mitsui Dupont Polychemicals Co., Ltd., Surlyn manufactured by Dupont Co., Ltd., and ACLYN ACLYN manufactured by Allied Signal Co., Ltd.

The polyacetal resin composition of the present invention is characterized in that the branched or crosslinked polyacetal resin (A) 90 to 9
9.9% by weight (based on A + B) and the above ionomer resin (B) 10
0.10.1% by weight (based on A + B). When the amount of the branched or crosslinked polyacetal resin (A) is less than 90% by weight or the amount of the ionomer resin (B) exceeds 10% by weight, the original properties of the branched or crosslinked polyacetal resin are impaired, and the impact resistance is reduced. Chemical resistance and solvent resistance are reduced, which is not preferred for the purpose of the present invention. Also,
When the content of the ionomer resin (B) is less than 0.1% by weight, sufficient melt tension cannot be obtained, so that it is easy to draw down in blow molding, improvement in moldability cannot be obtained, and improvement in uniformity of a molded product. Is also insufficient, and in either case, it is not preferable. The effect of the ionomer resin (B) can be surprisingly obtained even in a small amount within the above range. However, it is preferable that the branched or cross-linked polyaser (A) is 95 to 99.5% by weight (vs.
A + B), and the ionomer resin (B) is 5 to 0.5% by weight.

The polyacetal resin composition of the present invention may contain other thermoplastic resins, for example, a polyacetal (co) polymer having a substantially linear structure other than the component (A), if necessary, as long as the object of the present invention is not impaired. Coalescence, polyurethane resin, (B)
Other small amounts of polyolefin resin, polyester resin, polyamide resin, polyalkylene glycol resin, and modified products (elastomer) other than the components are also used in small amounts (eg, within 30% by weight of (A + B)). It is possible to In addition, inorganic or organic fibrous reinforcing agents such as glass fiber, carbon fiber, potassium titanate fiber, and aramid fiber; powdered fillers such as glass beads, carbon, calcium carbonate, and talc; and plates such as mica and glass flakes. One or more fillers may be added. Particularly, the combined use of a fibrous reinforcing material such as glass fiber and a powdery or plate-like filler is effective in terms of strength and dimensional stability (warpage, deformation) of a molded product. Further, the composition of the present invention may further contain various known additives to the polyacetal resin, for example, various stabilizers such as antioxidants, heat stabilizers, and light (weather) stabilizers, coloring agents such as dyes and pigments, lubricants, and nucleating agents. One or more of a (crystallization accelerator), a release agent, a surfactant and the like can be blended.

The preparation of the composition of the present invention can be carried out by a general method generally used. For example, the components are well mixed in advance by a blender such as a Henschel mixer, and a single-screw or multi-screw vented extruder is used. In general, the mixture is melt-kneaded and extruded into a composition pellet, but some components may be added separately.

In the present invention, when producing a hollow molded article by blow molding using the above-mentioned polyacetal resin composition, a molding machine used for blow molding of a general thermoplastic resin is used, and a conventional method is used. Just do it. Further, it is also possible to use a special molding machine such as a three-dimensional blow molding machine, the polyacetal resin composition of the present invention in two or more layers, or a layer of another resin such as polyolefin, polyester, polyamide resin and the like. It is also possible to perform multilayer blow molding in combination. On the other hand, in producing extruded products such as round bars, pipes, and irregular cross-section parts by extrusion using the polyacetal resin composition, a molding machine used for extrusion molding of a general thermoplastic resin is used. What is necessary is just to carry out according to a well-known method.

[0012]

According to the present invention, the polyacetal resin composition comprises:
It has high melt tension, which is important for blow molding and extrusion molding, and has excellent blow moldability and extrusion moldability, has a good appearance, and also has excellent impact resistance. Further, the polyacetal resin composition of the present invention has good mechanical properties and chemical resistance, and is used for hollow parts such as those related to a fuel tank or an engine room of an automobile, piping materials such as containers and pipes, nibs, and an induction core. It can be widely used for parts having irregular cross-sections such as sheet-shaped, pipe-shaped or rod-shaped extruded parts, and various other industrial uses.

[0013]

EXAMPLES Hereinafter, the present invention will be described specifically, but the present invention is not limited to these examples. Reference Example 1 (Branched (crosslinked) polyacetal resin POM-1
Preparation of a paddle using a continuous mixing reactor that has a jacket through which a heat medium (warm water of 80 ° C.) is made to pass and a rotary shaft with a paddle and a cross section whose two circles partially overlap each other While rotating the two rotating shafts marked with, at one end, 3.3% by weight of 1,3-dioxolane as a comonomer, 0.05% by weight of 1,4-butanediol diglycidyl ether as a branching (crosslinking) component, and molecular weight control Trioxane containing 0.04% by weight of methylal is continuously supplied as an agent, and at the same time, a 1% cyclohexane solution of a dibutyl ether ligand of boron trifluoride as a catalyst is continuously added to the same place (as BF _3). 50pp for all monomers
m) and copolymerization was performed. Then, the reaction product discharged from the outlet of the polymerization machine is quickly passed through a crusher, and an aqueous solution at 30 ° C. containing 0.1% of triethylamine is added. The resultant is pulverized into fine particles and cooled at the same time, the catalyst is deactivated, and the flake-like crude polyacetal is added. A resin was obtained. Next, pentaerythrityl-tetrakis [3- (3,5-di-tert-butyl-butyl) was used as a stabilizer with respect to 100 parts by weight of the crude polyacetal resin.
4-hydroxyphenyl) propionate] (Irganox10
10, manufactured by Ciba-Gaiky) 0.3 parts by weight and melamine 0.15
Parts by weight, and mixed using a Henschel mixer,
In a twin-screw extruder with a vent, melt-knead at 200 ° C,
Simultaneously with the stabilization, a pellet-like branched (crosslinked) polyacetal resin (POM-1) was obtained. The resin obtained has a melt index (according to ASTM D-1238, 190 ° C) of 1.0
g / 10 min. Reference Example 2 (Branched (crosslinked) polyacetal resin POM-2
Preparation) As a branching (crosslinking) component, instead of 1,4-butanediol diglycidyl ether 0.05% by weight, propylene glycol diglycidyl ether 0.06% by weight was used, and the amount of methylal used was changed to 0.03% by weight. Other than Reference Example 1
In the same manner as described above, branched (crosslinked) polyacetal resin (POM
-2) was obtained. The melt index of the obtained resin is
0.7 g / 10 min. Reference Example 3 (Branched (crosslinked) polyacetal resin POM-3
Preparation) The branching (crosslinking) component was changed to 0.04% by weight of hexamethylene glycol diglycidyl ether instead of 0.05% by weight of 1,4-butanediol diglycidyl ether, and the amount of methylal was changed to 0.06% by weight. In the same manner as in Reference Example 1, a branched (crosslinked) polyacetal resin (POM-
3) was obtained. The resulting resin has a melt index of 2.5
g / 10 min. Reference Example 4 (Branched (crosslinked) polyacetal resin POM-4
Preparation of 1,4-butanediol diglycidyl ether
0.3% by weight, the amount of methylal was changed to 0.09% by weight
Other than the above, a branched (cross-linked) polyacetator was prepared in the same manner as in Reference Example 1.
A resin (POM-4) was obtained. Meltoy of the obtained resin
The index was 1.5 g / 10 min. Reference Example 5 (Preparation of linear polyacetal resin POM-5) Using 1,4-butanediol diglycidyl ether
Except that the amount of methylal used was changed to 0.05% by weight.
Is a linear polyacetal resin (PO
M-5) was obtained. The melt index of the obtained resin is
2.0 g / 10 min.

Examples 1 to 9 and Comparative Examples 1 to 8 The components shown in Table 1 were mixed using a Henschel mixer, melt-kneaded and extruded at a cylinder temperature of 190 ° C. using a 30 mm twin screw extruder, and pelletized. Each composition was prepared. In Comparative Examples 1, 4 to 7, the resins (POM-1 to POM- 5 ) obtained in Reference Examples were used alone. Then, these pellets were collected using a Capillograph 1B manufactured by Toyo Seiki Co., Ltd., with an orifice diameter of 1 mm, an orifice length of 10 mm, a temperature of 190 ° C., an extrusion speed of 10 mm / min (shear speed of 122 sec ⁻¹ ), and a take-up speed of 20 m /
Under the condition of min, the melt tension (load) at the time of take-off was measured with a load cell. Table 1 shows the results. The olefin ionomer (B) used is as follows. ION-1: Ethylene (95 mol) -methacrylic acid (5 mol) copolymer Metal ion; Zn (25% neutralization degree), melt index 15
g / 10 min ION-2: Ethylene (95 mol) -methacrylic acid (5 mol) copolymer Metal ion; Na (neutralization degree 30%), melt index 10
g / 10 min ION-3: Ethylene (95 mol) -methacrylic acid (5 mol) copolymer Metal ion; Zn (neutralization degree 50%), melt index 5.
0 g / 10 min ION-4: Ethylene (97 mol) -methacrylic acid (3 mol) copolymer Metal ion; Mg (degree of neutralization 50%), melt index 1.
0 g / 10min

[0015]

[Table 1]

[0016] Examples 10-13, Comparative Examples 9-14 Examples 1,2,5,9 and Comparative Examples 1 to 3, 6 to the resin composition of the blow molding machine used in the 8 (Placo Co. S-45N
D) In the condition of cylinder temperature 200 ° C, die temperature 200 ° C, mold temperature 80 ° C, blowing pressure 6kg / cm ² , die diameter 30mm, die clearance 2mm, φ70mm × 140mm, water bottle type about 1mm thick The container was molded, and the appearance (spots and surface roughness) of the molded product, the uniformity of the molded product, and the impact resistance were evaluated by the methods described below. Table 2 shows the results. The evaluation method is as follows. (1) Appearance (spots, surface roughness) of molded article The spots and surface roughness of the molded article surface were visually evaluated and ranked as excellent, good, acceptable, and defective. (2) Uniformity of molded products The thickness of the upper, middle and lower sides of the molded products is measured with a micrometer and the variation in thickness (% of the difference between the maximum value and the minimum value with respect to the average thickness) is examined. Was. In addition, according to the following criteria,
Good, acceptable, bad. 0 ≦ Thickness variation (%) <10 Excellent 10 ≦ Thickness variation (%) <15 Good 15 ≦ Thickness variation (%) <20 Possible 20 ≦ Thickness variation (%) Poor (3) Impact resistance For water bottle blow molded products Fill 100% (500cc) with water, 1.4
m from the bottom of the container from the height of the drop on concrete,
It was examined whether or not the container was destroyed by the drop impact. The evaluation was performed 10 times for each resin composition, and based on the following criteria,
Excellent, good, acceptable, bad. Damaged number 0 Excellent Damaged number 1 Good Damaged number 2 Possible Damaged number 3 or more Defective

[0017]

[Table 2]

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification code FI C08L 23:26) B29K 59:00 B29L 22:00

Claims (6)

(57) [Claims] (1) Trioxane (A) as a main monomer,
And cyclic ether or cyclic formal 0.2 to 10% by weight
(To trioxane) as a comonomer and
Two or more cyclic ether groups or cyclic formal
0.005 to 0.2% by weight (based on trioxa
) In the presence of a cation-active catalyst
Obtained by, branched or crosslinked polyacetal resin 90 ~
99.9% by weight (vs. A + B) and (B) an ionomer resin of a copolymer containing an olefin and an α, β-unsaturated carboxylic acid.
A polyacetal resin composition for blow molding or extrusion molding comprising 1% by weight (based on A + B). 2. A branched or crosslinked polyacetal resin
Has a melt index value (190 ° C, load 2160g) of 0.05
The polyacetal resin composition according to claim 1, wherein the composition is from 10 to 10 g / 10 min . 3. The method of claim 1, wherein (B) the ionomer resin comprises ethylene and
Ionomer of copolymer containing α, β-unsaturated carboxylic acid
3. The polyacetal resin composition according to claim 1, which is a resin. 4. The method according to claim 1, wherein (B) the ionomer resin is lithium,
Thorium, potassium, calcium, magnesium and zinc
At least one metal ion selected from lead
4. The ionomer resin according to claim 1, which is a crosslinked ionomer resin.
The polyacetal resin composition according to claim 1. 5. The polymer according to claim 1, wherein
A hollow molded product obtained by blow molding a cetal resin composition. 6. The polymer according to claim 1, wherein
An extruded product obtained by extruding a cetal resin composition.