JP3135398B2 - Resin composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a composition obtained by blending a specific styrenic copolymer with a polyacetal resin and melt-kneading the resin, and has excellent compatibility, dispersibility and interfacial adhesion between the resins. An object of the present invention is to provide a composition in which various disadvantages are improved by compensating for the respective drawbacks caused by the styrene resin alone.

[0002]

2. Description of the Related Art Polyacetal resins are excellent in moldability and have well-balanced mechanical properties, electrical properties, heat resistance, chemical resistance, friction and wear properties, and the like. Because of its excellent fatigue resistance as a plastic material, it is used in a very wide field as a typical engineering resin. However, this resin also has problems that require improvement in heat resistance, weather resistance, acid resistance, mechanical properties, molding shrinkage (deformability), adhesiveness, etc., depending on the purpose of use. Thermoplastic styrenic resins are inexpensive, have excellent moldability, have low shrinkage during molding, and have good dimensional accuracy, but have poor mechanical properties and poor solvent resistance. In general, in modifying the physical properties of a thermoplastic resin, it is common practice to compensate for the disadvantage by blending another resin having a property to supplement the physical properties, and the purpose is often achieved. However, polyacetal resins are different from general thermoplastic resins, and when other thermoplastic resins are blended, the mutual compatibility and dispersibility between the resins are particularly poor, the adhesion between the two phases is insufficient, and the phase at the interface is poor. When the molded product is separated, the surface layer may be peeled off, and it is extremely difficult to modify such a resin by a compounding means. The blending with a general thermoplastic styrene resin is not an exception, and the adhesion at the interface between the two phases is insufficient, phase separation occurs at the interface, and surface peeling occurs when a molded product is formed, which has a practical problem. . From this viewpoint, the present invention seeks and examines a modified thermoplastic styrenic resin having good compatibility with polyacetal resin and good interfacial adhesion, and by mixing these, maintains a uniform and good dispersion form, thereby maintaining mechanical properties. It is an object of the present invention to provide a molding resin composition in which various properties such as shape, deformability and surface condition are modified and improved.

[0003]

Means for Solving the Problems To achieve the above object, the present inventors have conducted intensive studies on the improvement of compatibility, dispersibility, and interfacial adhesion between a polyacetal resin and a styrene-based resin. By discovering that the polymer satisfies this property, by blending this copolymer and melt-kneading, it maintains the excellent properties inherent in both resins,
In addition, the inventors have found that the disadvantages of both cases are improved, and arrived at the present invention. That is, the present invention relates to (A) 97 to 5 parts by weight of a polyacetal resin and (B) 99.5 to 50% by weight of a styrene-based monomer.
It is composed of 0.5 to 50% by weight of a vinyl monomer having at least one kind of group represented by (1) or (2) and 0 to 49.5% by weight of another vinyl monomer.
(1) or a styrene-based binary or tertiary or more copolymer having at least one kind of group represented by (2)
95 parts by weight -O-Ar (1) -NH-Ar (2) (However, Ar is an aryl group, and the group represented by the general formula (1) or (2) may be directly bonded to the main chain. And may be bonded to the main chain via a divalent organic group (-R-).)
It is a resin composition comprising:

Hereinafter, the components of the present invention will be described. The polyacetal resin used in the present invention (A), a polymer compound having an oxymethylene group (-CH ₂ O-) as the main constituent unit, a polyoxymethylene homopolymer, the other structural units in addition to oxymethylene groups Copolymer, terpolymer, block polymer may be contained in a small amount,
The molecule may have not only a linear shape but also a branched or crosslinked structure. The degree of polymerization is not particularly limited as long as it has moldability (for example, a melt flow value (MFR) at 190 ° C. under a load of 2160 g of 1.0 to 100).

In the present invention, the styrene-based copolymer (B) blended with the polyacetal resin (A) is mainly composed of at least one styrene unit represented by the above general formula (1) or (2). It is a polymer having a group in the side chain. The group represented by the general formula (1) or (2) constituting the side chain in the styrenic copolymer (B) is directly bonded to the atom constituting the main chain of the styrenic copolymer (B). And it may be bonded to the main chain via a divalent organic group -R-. In this case, -R- is not particularly limited, but preferably -R-
Is absent, or -CO-,-(CH ₂ ) _n- , -COO (CH ₂ ) _n- , -CO (O (C
_{H 2) n] m -,} -CO-NH- (CH 2) n -CO -, - COOCH 2 -CH (OH) -CH 2 -,
It is at least one or more divalent organic groups selected from -CH ₂ -O-CO- (CH ₂ ) _n- (where n = 1 to 4, m = 1 to 5).

The preparation of the styrenic copolymer (B) is not particularly limited, but includes at least one vinyl compound having a group represented by the above general formula (1) or (2) together with a styrenic monomer. It is obtained by copolymerizing as a monomer component. As a vinyl monomer to be copolymerized with such a styrene monomer,

[0007]

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[0008]

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The polymerization method includes anionic polymerization, cationic polymerization,
Although any of radical polymerization may be used, industrially preferred is radical polymerization, which is performed by bulk, solution, suspension, or emulsion polymerization.
The styrenic copolymer (B) used in the present invention further comprises
A multi-component copolymer obtained by copolymerizing a vinyl monomer other than the component as the third component may be used. Although not particularly limited as such a third component, α-methylstyrene,
Acrylic acid or methacrylic acid and its aliphatic esters,
Acrylonitrile, butadiene, chlorinated ethylene and the like are preferably used. The proportion of each component constituting the styrene-based copolymer (B) is from 99.5 to 50% by weight of the styrene-based unit and from 0.5 to 50% by weight of the repeating unit having a group represented by the general formula (1) or (2). And preferably 98 to 60% by weight of the former and 2 to 40% by weight of the latter. When other components are also contained, the amount of the third component is 49.5% by weight or less, preferably 40% by weight or less. If the repeating unit having the group represented by the general formula (1) or (2) is too large, the characteristics (cost, moldability, etc.) of the styrene resin will be lost, and if it is too small, the phase with the polyacetal resin will be lost. It is not preferable because effects such as solubility, dispersibility, and adhesiveness cannot be obtained.

The amount of the styrene copolymer (B) is 3 to 95 parts by weight, preferably 5 to 90 parts by weight, based on 100 parts by weight of the total with the polyacetal resin (A). If each of the components (A) and (B) is too small or too large, a sufficient reforming effect cannot be obtained, which is not preferable.

The resin composition of the present invention has good compatibility and dispersibility between the polyacetal resin (A) and the styrene copolymer (B), and the (A) or (B) component is uniform as extremely fine particles. And the adhesion at the interface is also improved. This can be confirmed by observing the fracture surface of the composition molded article with an electron microscope. That is, in the case of a molded article of a composition of a polyacetal resin and another general thermoplastic styrenic resin, when the fracture surface is observed with an electron microscope, particularly the interface can be clearly identified, and as a large particle or layered The two-phase separation structure was confirmed, and it was recognized that poor adhesion at the interface caused the fracture. It is also recognized that when immersed in a solvent in which the other resin dissolves, the other resin phase is eluted and voids are formed. On the other hand, in a polyacetal resin composition containing the specific styrene copolymer (B) of the present invention, in the same observation or treatment, the interface between the two resins could hardly be identified, and the interface was broken. It is suggested that this is not the cause, and that the specific resin composition of the present invention is excellent in dispersibility and interfacial adhesion.

Further, as described above, the styrene copolymer (B) used in the composition of the present invention not only has good compatibility of the component (B) itself with the polyacetal resin, but also has the following features: An advantage of improving the compatibility and dispersibility of a third resin component (C) (eg, a general thermoplastic styrene resin) which is originally poorly compatible and dispersible with a polyacetal resin. Exists, which expands the possibility of blending other resins with polyacetal resin, and the possibility of modification by it is also greatly expected. From this point of view, the composition of the present invention can further contain many other thermoplastic resins (C) as a third component, and as such a resin as the third component, for example, polystyrene, styrene-acrylonitrile copolymer, Styrene resin such as ABS, polyoxyalkylene glycol such as polyethylene glycol and polypropylene glycol, acrylic resin such as polyacrylic acid or its ester, polymethacrylic acid or its ester, polyester resin such as polyethylene terephthalate and polybutylene terephthalate, etc. Is raised. Further, the resin composition of the present invention may be a conventionally known additive such as a lubricant, a lubricant, a nucleating agent, a dye / pigment, a mold release agent, an antioxidant, in order to impart desired properties within a range that does not impair the purpose of the resin composition. Additives such as heat stabilizers, weather (light) stabilizers, hydrolysis stabilizers, reinforcing agents, fillers and the like can be blended.

The composition of the present invention can be prepared by various known methods, but it is necessary to heat and melt the mixture in the presence of at least two components (A) and (B) and to knead it for 20 seconds or more. Yes, other components may be simultaneously used together, or may be added separately. Specifically, for example, a polyacetal resin (A), a polymer (B), and other additives as necessary are uniformly mixed in advance by a mixer such as a tumbler or a Henschel mixer, and then, a single-screw or twin-screw extrusion is performed. In general, the mixture is melted and kneaded while being supplied to a machine, and an open roll, a Banbury mixer, a kneader, or the like may be used. The resin composition kneaded by these methods may be pelletized and then subjected to molding, or may be directly molded. The treatment temperature is 5 ° C to 100 ° C higher than the temperature at which the resin component melts, and particularly preferably 10 ° C to 60 ° C higher than the melting point. If the temperature is too high, decomposition or abnormal reaction occurs, which is not preferable. The melt-kneading time is at least 20 seconds to 10 minutes, preferably 1 to 5 minutes.

[0014]

The resin composition comprising the polyacetal resin (A) of the present invention and the specific styrenic copolymer (B) is excellent in compatibility and dispersibility between resin components, peeling of the surface of a molded product, etc. There is no problem due to poor dispersion, deformation due to molding shrinkage can be suppressed, and various other properties can be improved.
In addition, this composition also has the effect of improving the compatibility of the third component resin, which is originally poorly compatible with the polyacetal resin,
The range of modification is expanded, and many uses are expected.

[0015]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, but it should not be construed that the invention is limited thereto.
The dispersibility and other characteristics of the resin composition were evaluated according to the following methods. [Confirmation of compatibility and interfacial adhesion] The fractured surface of the molded piece was used as it is or after immersion in a solvent of the polymer (B), for example, a tetrahydrofuran solution. The dispersion form (particle shape and size), interface adhesion and the like depending on the state of the fracture surface were determined. The dispersibility and interfacial adhesiveness were ranked as excellent, good, and poor by combining them. [Mechanical strength of molded piece] The tensile strength was measured according to the method of ASTM D638. [Surface Peeling Test] An adhesive tape was stuck to the surface of the tensile test piece, which was instantaneously peeled off, and the presence or absence of surface peeling of the test piece was visually judged. [Evaluation of molded product deformation (flatness)] 70 × 50 × 3 by injection molding
A flat plate of mm is placed on a flat table, and the height of each part of the molded product is measured using a three-dimensional measuring machine (Microcode A121, manufactured by Mitutoyo Corporation). Was evaluated.

The styrene copolymer used in this embodiment
(B) was prepared by the following method. [Preparation of styrene-based copolymer (B)] Prepared by heat-polymerizing styrene, the vinyl monomers shown below, and optionally other monomers in the presence of a radical catalyst (such as azobisisobutyronitrile). . The obtained styrenic copolymer
The copolymer composition of (B) is as shown below.

[0017]

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Examples 1 to 12 Polyacetal resin (Duracon, Polyplastics Co., Ltd.) and the styrene copolymer (B-1 to 10)
Were mixed at the ratios shown in Tables 1 to 3, and were melt-kneaded at a set temperature of 190 ° C. at a screw rotation speed of 80 rpm using a twin-screw extruder with an inner diameter of 30 mm to form pellets. Next, the pellets were molded by an injection molding machine to prepare test pieces, and the above evaluation was performed. The results are shown in Tables 1 to 3. Comparative Examples 1 to 8 For comparison, a polyacetal resin alone, a styrene-based copolymer (B) alone and a styrene-based thermoplastic resin not belonging to the styrene-based copolymer (B) of the present invention were mixed at the ratios shown in the table. , And molded and evaluated in the same manner as in the examples. The results are shown in Tables 1 and 3.

Examples 13 to 15 The polyacetal resin and a styrene copolymer (B-
3) and another styrene-based resin were mixed at the ratio shown in Table 4, and a test piece was prepared and evaluated in the same manner. The results are shown in Table 4. The styrene copolymer (B-1 to B-1)
B-10) melt index (MI; measured at 190 ° C)
Is as follows. B-1; 8.3 B-2; 9.5 B-3; 7.3 B-4; 8.6 B-5; 7.4 B-6; 6.8 B-7; 5.5 B -8; 5.9 B-9; 8.1 B-10; 9.2 The details of other styrene resins used are as follows.
It is. PS (polystyrene); Styrone (Asahi Kasei Corporation)
AS ) (styrene-acrylonitrile copolymer (75-25 wt.
%)); Sebian N (manufactured by Daicel Chemical Industries, Ltd.) SB (styrene-butadiene copolymer (80-20 wt. %)
%)); Asaflex (produced by Asahi Kasei Corporation) ABS (styrene-acrylonitrile-butadiene copolymer )
Coalescence (60-20-20wt%));
Industrial Co., Ltd.)

[0020]

[Table 1]

[0021]

[Table 2]

[0022]

[Table 3]

[0023]

[Table 4]

Claims (5)

(57) [Claims] (1) 97 to 5 parts by weight of a polyacetal resin (A) and 99.5 to 50% by weight of a (B) styrene monomer;
It comprises 0.5 to 50% by weight of a vinyl monomer having at least one kind of group represented by (1) or (2) and 0 to 49.5% by weight of another vinyl monomer.
(1) or a styrene-based binary or ternary or more copolymer having at least one kind of group represented by (2)
95 parts by weight -O-Ar (1) -NH-Ar (2) (However, Ar is an aryl group, and the group represented by the general formula (1) or (2) may be directly bonded to the main chain. And may be bonded to the main chain via a divalent organic group (-R-).)
A resin composition comprising: 2. The general formula of the styrene copolymer (B)
The resin composition according to claim 1, wherein -Ar in the group of (1) or (2) is a phenyl group. 3. The general formula of the styrene copolymer (B)
The group represented by (1) or (2) is a divalent organic group (-R
The resin composition according to claim 1, which is a copolymer bonded to the main chain via —). -R-; -CO-,-(CH ₂ ) _n- , -COO (CH ₂ ) _n- , -CO [O (CH ₂ ) _n ] _m-
, -CO-NH- (CH ₂ ) _n -CO-, -COOCH ₂ -CH (OH) -CH _2- , -CH ₂ -O-
CO- (CH ₂ ) _n- (however, n = 1 to 4, m = 1 to 5) 4. The styrene-based copolymer (B) is a multi-component copolymer containing at least one of acrylonitrile, butadiene, acrylic acid or methacrylic acid and an aliphatic ester thereof. The resin composition as described in the above. 5. The resin composition according to claim 1, further comprising another thermoplastic resin (C).