JPH07195496A - Hollow molded product made of polyacetal resin - Google Patents

Abstract

PURPOSE:To provide a hollow molded product made of polyacetal resin wherein blow molding properties are extremely improved while mechanical properties, molding properties, etc., which are in-herent in polyacetal resin are being held. CONSTITUTION:A resin composition wherein 1-100 pts.wt. of a core shell polymer having a core of rubber-like polymer and a shell of glassy polymer (B) and /or 1-100 pts.wt. of at least one kind of thermosetting polyurethane resin (C-1), and 0.1-10 pts.wt. of at least one kind of isocyanate compound (C-2) (C) are blended in 100 pts.wt. of polyacetal resin (A), is molded by a blow molding method to manufacture a hollow molded product made of polyacetal resin.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a hollow molded article obtained by molding a polyacetal resin composition by a blow molding method.
More specifically, the blow moldability is maintained while maintaining the mechanical properties and moldability of the polyacetal resin, which is obtained by adding a specific core-shell polymer to the polyacetal resin and / or a thermoplastic polyurethane resin and an isocyanate compound. It is intended to provide a hollow molded article made of a polyacetal resin, which is remarkably improved.

[0002]

2. Description of the Related Art As is well known, a polyacetal resin is an engineering material having excellent physical properties such as mechanical properties and electrical properties, or chemical properties such as chemical resistance and heat resistance. Recently, it has been used as a resin in a very wide range of fields. However, the polyacetal resin molded product is mainly molded by injection molding due to the characteristics of the resin, and the molded product by blow molding is extremely small. This is because the melt flow characteristic of the polyacetal resin is close to Newtonian flow, the parison during blow molding is easy to draw down, and uneven thickness occurs.
This is because it is difficult to obtain a good molded product. Therefore, it has been desired to develop a polyacetal resin material that has excellent mechanical properties and is excellent in blow moldability that is unlikely to cause drawdown.

[0003]

[Means for Solving the Problems] The inventors of the present invention have conducted extensive studies to develop a polyacetal resin excellent in blow moldability without sacrificing the excellent characteristics inherent in the polyacetal resin as much as possible. As a result, the present invention has been completed. That is, the present invention comprises (A) 100 parts by weight of a polyacetal resin, (B) 1 to 100 parts by weight of a core-shell polymer having a rubbery polymer core and a glassy polymer shell, and / or (C) (C-1) heat One or more plastic polyurethane resins 1-10
0 part by weight and (C-2) one or more isocyanate compounds 0.1
The present invention relates to a hollow molded article made of a polyacetal resin obtained by molding a resin composition containing 10 to 10 parts by weight by a blow molding method.

The constituent components of the present invention will be described in detail below. First, the (A) polyacetal resin used in the present invention is a polymer compound having an oxymethylene group (--CH ₂ O--) as a main constituent unit, and a polyoxymethylene homopolymer and other constituent units other than the oxymethylene group. It may be a copolymer, terpolymer or block copolymer having a small amount, and the molecule may have not only a linear structure but also a branched or crosslinked structure.

The core-shell polymer (B) used in the present invention is an organic compound having a rubber-like polymer core and a glass-like polymer shell, and can be prepared by a known method, or a commercially available product can be used. It can also be used. Typical examples are Acryloid KM330 and KM653 of Rohm and Haas, Paraloid KCA-102 and KCA-301 of Kureha Chemical Co., Ltd., Staphyroid PO-0270, PO-0143 and Kanebuchi of Takeda Pharmaceutical Co., Ltd. Chemical Industry Co., Ltd.
Kane Ace FM, Metabrene C-10 from Mitsubishi Rayon Co., Ltd.
2, E-901, W-800, S-2001 and the like. Among such core-shell polymers, preferred is a core-shell polymer having a rubber-like polymer core and a glass-like polymer shell mainly composed of methyl methacrylate,
Particularly, it is a core-shell polymer in which substantially no anion is detected. When a core-shell polymer in which anions are detected is used, decomposition of polyacetal may be promoted during melt-kneading or blow molding, and desired blow moldability may not be obtained. In some cases, too much decomposition may make melting and kneading impossible. Here, the core-shell polymer in which an anion is not substantially detected means a core-shell polymer in which an anion is not detected by a usual qualitative test of anion. For example, as a measuring method, 5 g of the sample (core shell polymer) is weighed in a 50 ml Erlenmeyer flask, 20 ml of ion-exchanged water is added, the mixture is stirred with a magnetic stirrer for 3 hours, and then the filtrate obtained by filtering with No. 5 C filter paper is divided into two parts. Then, 1m barium chloride aqueous solution 0.5m on one side
A method to compare the occurrence of turbidity by adding l (a qualitative test for sulfate ion), and perform the same treatment, and add a 0.1 N silver nitrate aqueous solution instead of a 1% barium chloride aqueous solution to compare and observe the occurrence of turbidity. The presence of anions can be confirmed by the method (qualitative test for halogen ions).
A core-shell polymer in which these anions are not present is preferably used.

The core-shell polymer preferably used in the present invention is one obtained by emulsion polymerization using a nonionic surfactant and a polymerization initiator in which the radicals generated are neutral. Such a core-shell polymer can be produced, for example, by using the emulsion polymerization technique described in JP-A-3-14856. The emulsion polymerization can be carried out, for example, using the following surfactants and polymerization initiators. Nonionic surfactants include ether type such as polyoxyethylene nonylphenyl ether, polyoxyethylene stearyl ether, polyoxyethylene lauryl ether, ester type such as polyoxyethylene monostearate, polyoxyethylene sorbitan monolaurate and the like. Most of the widely used nonionic surfactants such as sorbitan ester type and block polymer type such as polyoxyethylene polyoxypropylene block copolymer can be used. The amount of addition is appropriately selected according to the particle stabilizing ability of the surfactant. As the polymerization initiator, azobisisobutyronitrile, 2,2 '
-Azo-based polymerization initiators such as dimethyl azobisisobutyrate and 2,2'-azobis (2-aminopropane) dihydrochloride, and peroxide-based polymerization initiation such as cumene hydroperoxide, diisopropylbenzene hydroperoxide and hydrogen peroxide The agents are used alone or in combination of two or more kinds. When emulsion polymerization is carried out in such a reaction system using a surfactant containing no anion and a polymerization initiator other than persulfate, the obtained core-shell polymer becomes substantially free of anion. The polyacetal resin composition using such a core-shell polymer that does not substantially contain anions becomes excellent in blow moldability.

The core-shell polymer in the present invention is
It is obtained by a continuous multi-stage emulsion polymerization method in which the polymer of the previous stage is sequentially coated with the polymer of the latter stage, that is, a so-called seed emulsion polymerization method. At the time of particle generation polymerization, it is preferable to start the emulsion polymerization reaction by adding a monomer, a surfactant and water to a reactor, and then adding a polymerization initiator. The first stage polymerization is a reaction that forms a rubbery polymer. Examples of the monomer that constitutes the rubber-like polymer include conjugated dienes, alkyl acrylates having an alkyl group with 2 to 8 carbon atoms, and mixtures thereof. These monomers are polymerized to form a rubber-like polymer having a glass transition temperature of -30 ° C or lower. As such a conjugated diene, for example, butadiene,
Although there can be mentioned isoprene, chloroprene and the like,
In particular, butadiene is preferably used. Further, as an alkyl acrylate having an alkyl group having 2 to 8 carbon atoms,
For example, ethyl acrylate, propyl acrylate, butyl acrylate, cyclohexyl acrylate, 2-
Examples thereof include ethylhexyl acrylate, but butyl acrylate is particularly preferably used. In the first-stage polymerization, a copolymerizable monomer such as a conjugated diene and an alkyl acrylate, for example, styrene, vinyltoluene, aromatic vinyl such as α-methylstyrene, aromatic vinylidene, acrylonitrile, methacrylonitrile, and other cyanide vinyl are used. It is also possible to copolymerize vinylidene cyanide, alkyl methacrylate such as methyl methacrylate and butyl methacrylate. If the first stage polymerization does not contain conjugated dienes, or if it contains conjugated dienes and is 20% by weight or less of the total amount of monomers in the first stage, use a small amount of crosslinkable monomer and grafting monomer. It is possible to obtain a polymer having higher impact resistance. Examples of the crosslinkable monomer include aromatic divinyl monomers such as divinylbenzene, ethylene glycol diacrylate, ethylene glycol dimethacrylate, butylene glycol diacrylate, hexanediol diacrylate, hexanediol dimethacrylate, oligoethylene glycol diacrylate, oligoethylene glycol dimethacrylate. Methacrylate, trimethylol propane diacrylate, trimethylol propane dimethacrylate, trimethylol propane triacrylate, trimethylol propane trimethacrylate and the like can be mentioned alkane polyol polyacrylate or alkane polyol polymethacrylate, but especially butylene glycol diacrylate, Hexanediol diacrylate is preferred It is needed. Examples of the grafting monomer include unsaturated carboxylic acid allyl esters such as allyl acrylate, allyl methacrylate, diallyl maleate, diallyl fumarate and diallyl itaconate, and allyl methacrylate is particularly preferably used. Such a crosslinkable monomer and a grafting monomer are used in an amount of 0 to 5% by weight, preferably 0.1 to 2% by weight, based on the total amount of the first stage monomers.

The core of the rubber-like polymer is preferably in the range of 50 to 90% by weight based on the whole core-shell polymer. When the core is less than this weight range, or more than this weight range, the impact resistance of a hollow molded article made of polyacetal resin obtained by blow molding a resin composition obtained by melt mixing the resulting core-shell polymer The effect of may not be sufficient. Also, the glass transition temperature of the core is -30
If it is higher than 0 ° C, the effect of improving low temperature impact resistance may not be sufficient. A glassy polymer is formed in the outermost shell phase (shell phase). Examples of the monomer constituting the glassy polymer include methyl methacrylate and a monomer copolymerizable with methyl methacrylate. These monomers are methyl methacrylate alone or a mixture of monomers copolymerizable with methyl methacrylate, and form a glassy polymer having a glass transition temperature of 60 ° C. or higher. Examples of monomers copolymerizable with methyl methacrylate include alkyl acrylates such as ethyl acrylate and butyl acrylate, ethyl methacrylate,
Alkyl methacrylates such as butyl methacrylate, styrene, vinyltoluene, aromatic vinyl such as α-methylstyrene, vinylidene cyanide such as aromatic vinylidene, acrylonitrile, methacrylonitrile, vinyl polymerizable monomers such as vinylidene cyanide. I can, but
Particularly preferably, ethyl acrylate, styrene, acrylonitrile and the like are used. The outermost shell phase is preferably in the range of 10 to 50% by weight based on the whole core-shell polymer. When the outermost shell phase is less than this weight range or more than this weight range, it is possible to improve the impact resistance of a hollow molded article obtained by blow molding a resin composition obtained by melt mixing the resulting core-shell polymer. The effect may not be sufficient. Also,
An intermediate phase may be present between the first stage and the final polymerized phase. For example, polymerized monomers having functional groups such as glycidyl methacrylate, methacrylic acid, hydroxyethyl methacrylate, etc., polymerized monomers that form glassy polymers such as methyl methacrylate, polymerized monomers that form rubbery polymers such as butyl acrylate, etc. The intermediate phase is formed by seed emulsion polymerizing. Such an intermediate phase can be variously selected depending on the desired properties of the core-shell polymer. Also,
The polymerization rate may be appropriately selected depending on the monomer used. For example, when the glassy polymer is used as the intermediate phase, its polymerization rate may be calculated as a part of the shell, and in the case of a rubbery polymer, it may be calculated as a part of the core.

The structure of the core-shell polymer having such an intermediate phase has, for example, a multi-layered structure in which another layer is present between the core and the shell, or the intermediate phase has a fine granular structure in the core. One that has a salami structure that is dispersed. In a more extreme case of a core-shell polymer having a salami structure, the mesophase to be dispersed may form a new core at the center of the core. The core-shell polymer having such a structure may occur when a monomer represented by styrene is used as a monomer constituting the mesophase. Further, when a core-shell polymer having an intermediate phase is used, not only the impact resistance but also the elastic modulus, the heat distortion temperature, and the appearance are improved. In the present invention, the amount of the (B) core-shell polymer added is 1 to 10 with respect to 100 parts by weight of the (A) polyacetal resin.
0 parts by weight, preferably 1 to 50 parts by weight, more preferably 10
~ 50 parts by weight. If the amount of the core-shell polymer added is less than 1 part by weight, the effect of lowering the drawdown property is insufficient and the required blow moldability cannot be obtained. If it is more than 100 parts by weight, the resin composition obtained is molded by blow molding. In the hollow molded product, the mechanical strength, particularly the rigidity is significantly reduced, and the thermal stability is also adversely affected.

The core-shell polymer (B) is added and blended in the polyacetal resin (A) to retain the excellent mechanical properties of the polyacetal resin,
Exhibits excellent drawdown reduction effect. The effect of reducing the drawdown property is that in the resin in which the core-shell polymer is added and blended in the polyacetal resin, the core-shell polymer is dispersed inside the polyacetal resin in the form of particles of about 0.1 to 2 μm while interacting with the polyacetal resin. It is considered that the melt viscosity of the product is improved and the drawdown property is suppressed.

The component (C) used in the polyacetal resin composition of the present invention comprises (C-1) a thermoplastic polyurethane resin and (C-2) an isocyanate compound.

The thermoplastic polyurethane resin (C-1) is a reaction product containing the following components (i), (ii) and (iii). (i) diisocyanate compound (ii) high molecular weight polyol having a molecular weight of 500 to 5000 (iii) low molecular weight polyol and / or polyamine having a molecular weight of 60 to 500 where the thermoplastic polyurethane resin (C-1) is constituted (i)
The diisocyanate compound of, for example, 1,4-butylene diisocyanate, 1,6-hexamethylene diisocyanate, cyclopentylene-1,3-diisocyanate,
4,4'-dicyclohexylmethane diisocyanate, isophorone diisocyanate, cyclohexylene-1,4-diisocyanate, 2,4-tolylene diisocyanate, 2,
6-tolylene diisocyanate, an isomer mixture of 2,4-tolylene diisocyanate and 2,6-tolylene diisocyanate, 4,4'-methylenebis (phenylisocyanate), 2,2-diphenylpropane-4,4'- Diisocyanate, p-phenylene diisocyanate, m-phenylene diisocyanate, xylene diisocyanate, 1,4
-Naphthylene diisocyanate, 1,5-naphthylene diisocyanate, 4,4'-diphenyl diisocyanate, azobenzene-4,4'-diisocyanate, m- or p-
Includes tetramethyl xylene diisocyanate and 1-chlorobenzene-2,4-diisocyanate. Preferably 4,4'-methylenebis (phenylisocyanate), 1,6-hexamethylenediisocyanate, 2,4-
Examples include tolylene diisocyanate and isophorone diisocyanate. Next, (ii) the high molecular weight polyol, which is a constituent component of the thermoplastic polyurethane resin (C-1), has a molecular weight of 500 to
The component which forms the soft segment of the polyurethane (C-1) is 5000, preferably 1000 to 3000. Such high molecular weight polyols are mainly polyester diols having hydroxyl groups at both ends (including polycarbonate diols), polyether diols and the like, and a small amount of them may be triols and the like. Suitable polyester diols are polyester diols of one or more dihydric alcohols with one or more dicarboxylic acids. Suitable dicarboxylic acids constituting this are adipic acid, succinic acid, sebacic acid, suberic acid, methyladipic acid, glutaric acid, pimelic acid, azelaic acid, thiodipropionic acid and citraconic acid and small amounts of aromatic dicarboxylic acids. The mixture etc. which are contained are mentioned. Suitable dihydric alcohols as other constituents are 1,3- or 1,2-propylene glycol, 1,4-butanediol, 1,3-butanediol, 2-methylpentanediol, 1,5 -Diethylene glycol, 1,5-pentanediol, 1,6-pentanediol, 1,12-dodecanediol and a mixture thereof and the like can be mentioned. In addition, hydroxylcarboxylic acids, lactones and carbonates,
For example, ε-caprolactone and 3-hydroxybutyric acid can also be the constituents of the polyester diol. Preferred polyesters are polyadipate diols, polylactone diols and polycarbonate diols. Next, preferred polyether diols are one or more alkylene glycols such as ethylene glycol, 1,2- or 1,3.
-Propylene glycol, 1,4-butanediol and
Condensation products such as 1,5-pentanediol and mixtures thereof. Suitable polyalkylene ether glycols can also be prepared from tetrahydrofuran. Furthermore, polyether diols, as comonomers, in particular as random or block comonomers,
It may be an ether glycol derived from ethylene oxide, propylene oxide and / or tetrahydrofuran (THF), TH with a small amount of 3-methyl THF
It is also possible to use F polyether copolymers. Particularly preferred polyether diols are poly (tetramethylene ether) glycol (PTMEG), poly (propylene oxide) glycol, copolymers of propylene oxide and ethylene oxide, and copolymers of tetrahydrofuran and ethylene oxide, more preferably poly (tetramethylene). Ether) glycol. Other suitable polymeric diols may be those whose backbone is predominantly hydrocarbon, such as polybutanediol. Next, (iii) the low molecular weight polyol and / or polyamine having a molecular weight of 60 to 500, which is a constituent component of the thermoplastic polyurethane (C-1), is mainly selected from an aliphatic linear diol or diamine, or an aromatic diol or diamine. In addition, at least one kind or a part thereof may contain a small amount of triol. This component becomes a hard segment of polyurethane (B-2) and also plays a role of chain extension and crosslinking. Preferred low molecular weight polyols include 1,2-ethanediol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, and 1-hexanediol. Examples include 1,4-cyclohexanediol, ethylene glycol, propylene glycol, glycerin, hexanetriol, trimethylolpropane, hydroquinone diethylol ether, resorcinol ether and the like. Examples of polyamines include diphenylmethanediamine, m-phenylenediamine, and their derivatives. More preferably ethylene glycol, propylene glycol, 1,2-ethanediol, 1,
4-butanediol, 1,6-hexanediol, glycerin, hydroquinone diethylol ether, resorcin diethylol ether or derivatives thereof. Thermoplastic polyurethane resin (C-
1) is such that the low molecular weight polyol and / or polyamine (iii) is about 0.2 to 1 equivalent of the high molecular weight polyol (ii).
Polyurethane constituted in an amount within the range of 5 equivalents is preferable, and the larger the amount of component (ii), the softer the polyurethane becomes and the hardness of the composition is affected. The blending amount of the (C-1) thermoplastic polyurethane resin is 1 to 100 parts by weight based on 100 parts by weight of the (A) polyacetal resin,
It is preferably 1 to 50 parts by weight, particularly 10 to 50 parts by weight. If the blending amount is too small, the drawdown property-reducing effect is not sufficiently exerted, and even if it is added unnecessarily excessively, the appearance of the hollow molded article is deteriorated and the thermal stability is also adversely affected.

Further, in the present invention, even if the (A) polyacetal resin and (C-1) the thermoplastic polyurethane resin are blended alone, the effects of improving the impact resistance and reducing the drawdown property are slight, It is essential to blend an isocyanate compound as the component C-2). The preferred isocyanate compound (C-2) used here is a compound represented by the general formula O = C = NRN = C = O (R: divalent group) and modified products thereof. For example, 4,4'-methylenebis (phenyl isocyanate), 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, xylylene diisocyanate, 1,6-hexamethylene diisocyanate, isophorone diisocyanate, 1,5-naphthalene diisocyanate. And any of these dimers, trimers, and compounds in which the isocyanate group (-NCO) is protected in any way are effective, but various properties such as discoloration during melt processing,
Or considering safety in handling, 4,4'-methylenebis (phenylisocyanate), isophorone diisocyanate, 1,5-naphthalene diisocyanate, 1,
Modified products (or derivatives) such as 6-hexamethylene diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate and dimers and trimers thereof are particularly preferable. The presence of such an isocyanate compound during melt-kneading eliminates the delamination phenomenon on the surface of the molded article, which is another object of the present invention, and also exerts a remarkable effect on the reduction of mold deposits and the like. To do. The amount of the (C-2) isocyanate compound used here is 0.1 to 100 parts by weight of the (A) polyacetal resin.
It is in the range of 10 parts by weight, preferably 0.3 to 5 parts by weight. When the blending amount exceeds 10 parts by weight, the fluidity of the polyacetal resin composition is lowered and problems occur in blow moldability and the like.

The polyacetal resin composition used in the present invention preferably has a melt viscosity of 20,000 poise or more when measured at 190 ° C. and a shear rate of 100 / sec. If the melt viscosity is low, drawdown occurs during the blow up of the parison, making it difficult to obtain a hollow molded article. Further, (B) core-shell polymer and (C) a thermoplastic polyurethane resin and an isocyanate compound, it is possible to obtain a good hollow molded article by blending either, (C) a thermoplastic polyurethane resin and an isocyanate compound However, since the reaction proceeds during melt-kneading, it is easier to obtain stable physical properties in the case of blending the (B) core-shell polymer.

The polyacetal resin composition used as a raw material for the hollow molded article of the present invention is preferably supplemented with various known stabilizers to reinforce the heat stabilizer. For this purpose, known antioxidants and nitrogen are used. It is desirable to use one type or two or more types of the contained compound, the alkali or alkaline earth metal compound and the like. Further, in order to impart desired properties to the composition according to its purpose, conventionally known additives such as lubricants, nucleating agents, release agents, weathering stabilizers, antistatic agents and other surfactants, or It is possible to add one or more organic polymer materials other than the component (B).

The composition used in the present invention can be prepared by the equipment and method generally known as a method for preparing a synthetic resin composition. Further, the compounds such as the stabilizers and additives may be added at any arbitrary stage, and it is of course possible to add and mix them just before obtaining the final molded product. The hollow molded article of the present invention can be obtained by molding by a usual method using a blow molding machine generally used for blow molding of thermoplastic resins. That is, the above resin composition is plasticized by an extruder or the like, and is extruded or injected by an annular die to form an annular molten or softened intermediate parison, which is sandwiched in a mold to form a gas inside. It is blown, inflated, cooled and solidified, and molded as a hollow body. Molding conditions for the polyacetal resin composition used as a raw material for the hollow molded article of the present invention include a cylinder and a die temperature of 18
It is preferably carried out at 0 to 240 ° C, particularly preferably 190 to 2
20 ° C. The mold temperature is preferably 60 to 140 ° C, particularly preferably 80 to 120 ° C. The gas blown into the inside may be air, nitrogen or the like, but air is usually used in consideration of economy, and the blowing pressure is preferably 4 to 10 kg / cm ² . Further, it can be molded by a special blow molding machine such as a three-dimensional blow molding machine.
It is also possible to make the polyacetal resin composition used as a raw material of the hollow molded article of the present invention into one or more layers, or to combine it with a layer made of another material to obtain a multilayer blow-molded article. The polyacetal resin composition used as a raw material for the hollow molded article of the present invention has a parison during blow molding.
It is desirable that the ratio of the time to fall to 120 mm and the time to fall to 600 mm be 3 or more. If this value is less than 3, the drawdown of the parison is large and the blow moldability is significantly reduced.

[0017]

EXAMPLES The present invention will be described below with reference to examples.
The present invention is not limited to these. Examples 1 to 5 and Comparative Examples 1 to 4 Each material having the composition shown in Table 1 was mixed using a Henschel mixer, and then a cylinder temperature of 190 was obtained using a 30 mm twin-screw extruder.
The mixture was melt-kneaded and extruded at 0 ° C to form pellets. Then, using the pellets, using a blow molding machine, a blow molding machine (S-45ND manufactured by Placo Co., Ltd.), a cylinder temperature of 200 ° C., a die (die diameter of 50 mm, die interval of 3 mm) temperature of 200 ° C., mold temperature of 100 ° C., A cylindrical container having an average thickness of 2.5 mm and an internal capacity of 500 cc was formed at a blowing pressure of 5 kg / cm ² . At this time, the moldability (drawdown property), the uniformity of the meat pressure of the molded product, and the appearance were evaluated.

The results are shown in Table 1. The evaluation method is as follows. (1) Melt viscosity Using a Capillograph manufactured by Toyo Seiki, resin temperature 190 ℃,
Capillary diameter 1 mm, capillary length 10 mm, shear rate 1
The melt viscosity at 00 / sec was measured. (2) Measurement of drawdown property Using a blow molding machine, a parison with a diameter of 2 cm was extruded from a die, and the time extruded up to 120 mm was divided by the time extruded up to 600 mm for evaluation. In this case, the larger this value is, the more difficult it is to draw down. (3) Uniformity of the molded product Cut the molded product and cut the circumference of the cylinder and its upper part, center part,
The thickness of the lower part was measured with a micrometer, and the variation in thickness was examined. (4) Breakage during Blow Judgment was made by visually observing whether or not the material was broken during blow molding. (5) Appearance evaluation Visually observing the surface smoothness (roughness), excellent, good, acceptable,
Ranked as impossible. (6) Drop weight impact test Using General Research Dyna Tap 8250,
The weight of a hemisphere having a tip shape of φ40 mm and 6.08 kg was dropped from a height of 90 cm, and the 65% fracture value of the cylindrical container formed in the example was measured. The abbreviations used in Examples and Comparative Examples are as follows. Polyacetal resin (A); Polyplastics Co., Ltd.
Made, Duracon Core Shell Polymer (B); Takeda Pharmaceutical Co., Ltd., Staphyloid PO-0143 Thermoplastic Polyurethane (C-1); Takeda Badishe Urethane Co., Ltd., Elastollan ET680L-10 Isocyanate Compound (C -2) ； Isophorone diisocyanate trimer

[0019]

[Table 1]

[0020]

EFFECTS OF THE INVENTION As is clear from the above description and examples, a composition obtained by pro-molding a composition in which a specific core shell polymer and / or an isocyanate compound and a thermoplastic polyurethane resin are added to a polyacetal resin is blended. The hollow molded article of the present invention has the remarkable effect of remarkably improving the blow moldability while maintaining the balanced mechanical properties of polyacetal. Therefore, the hollow molded article of the polyacetal resin of the present invention can be suitably used for applications such as gasoline tanks and fuel pipes around fuel for automobiles, which require chemical resistance.

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Claims (9)

[Claims] 1. A core-shell polymer having 1 to 100 parts by weight of (A) 100 parts by weight of a polyacetal resin, (B) a core of a rubbery polymer and a shell of a glassy polymer, and / or (C) (C-1) heat. One or more plastic polyurethane resins 1-10
0 part by weight and (C-2) one or more isocyanate compounds 0.1
Hollow molded product made of polyacetal resin obtained by molding a resin composition containing up to 10 parts by weight by a blow molding method. 2. The core-shell polymer (B) is a core-shell polymer in which substantially no anion is detected.
Hollow molded article made of the described polyacetal resin. 3. The (B) core-shell polymer is obtained by emulsion polymerization using a nonionic surfactant and a polymerization initiator in which radicals generated are neutral.
Hollow molded article made of the described polyacetal resin. 4. The hollow molded article made of polyacetal resin according to claim 1, wherein the shell of the core-shell polymer (B) is a polymer containing methyl methacrylate as a main component. 5. The soft segment in the thermoplastic polyurethane resin (C-1) is polypropylene glycol, polytetramethylene ether glycol, adipate-based polyol, polycaprolactan-based polyol or polycarbonate polyol. A hollow molded article made of the polyacetal resin according to any one of claims. 6. The polyacetal resin hollow molding according to claim 1, wherein the (C-2) isocyanate compound is diphenylmethane diisocyanate, isophorone diisocyanate, tolylene diisocyanate, naphthalene diisocyanate or metaxylylene diisocyanate. Goods. 7. The hollow molded article made of a polyacetal resin according to claim 1, wherein the melt viscosity of the polyacetal resin composition measured at 190 ° C. and a shear rate of 100 / sec is 20,000 poise or more. 8. The hollow polyacetal resin according to claim 1, wherein the ratio of the time for the parison to fall to 120 mm and the time to fall to 600 mm during blow molding of the polyacetal resin composition is 3 or more. Molding. 9. The falling weight impact strength of a hollow molded article made of polyacetal by the method described in the text is 0.80 kg.m / mm at a 65% failure value.
It is above, The hollow molding made from the polyacetal resin of any one of Claims 1-8.