JP3086274B2 - Polyacetal resin composition structure and method for producing the same - 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 structure in which a polyacetal resin is used as a matrix, and a vinyl chloride resin is dispersed in a network, and a method for producing the same. The present invention provides a resin molded product having a good appearance and retaining the characteristics of a polyacetal resin, and particularly having improved acid resistance and flame resistance.

[0002]

BACKGROUND OF THE INVENTION Polyacetal resins are excellent in moldability and have well-balanced mechanical properties, electrical properties, heat resistance, solvent 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, with the expansion of application fields, cost reduction is desired,
In addition, the performance requirements for resins tend to be increasingly sophisticated or specialized, and examples of such requirements include acid resistance and flame resistance. That is, molded products of polyacetal resin are flammable due to their molecular structure, and are often susceptible to acids and are required to have improved acid resistance. Therefore, severe parts such as automobile parts and electric / electronic parts are required. May be problematic for environmental applications. In general, as a method for responding to such a requirement of the polyacetal resin, the incorporation of a vinyl chloride resin is considered to be an effective means for improving the acid resistance, the flame resistance and the like of the polyacetal resin. However, according to the study of the present inventors, when polyvinyl chloride resin is simply blended into the polyacetal resin, the dispersibility is poor, and the phase structure is such that the vinyl chloride resin phase is dispersed in the form of islands or layers, Therefore, the improvement of acid resistance, flame resistance, etc. is not enough, and a large amount of vinyl chloride resin has to be blended. Therefore, the mechanical properties, electrical properties, heat resistance, friction and wear properties of polyacetal resin inherently exist. There is a problem that it decreases. The present invention improves the above-mentioned drawbacks based on the dispersibility of both components when a polyvinyl chloride resin is blended with a polyacetal resin, and when formed into a molded product, has a good appearance and excellent acid resistance and excellent flame resistance. The purpose is to provide.

[0003]

Means for Solving the Problems In view of the above problems, the present inventors have conducted intensive studies on the improvement of the dispersion form in a polymer blend of a polyacetal resin and a vinyl chloride resin, and as a result, have found that a specific filler is used in combination. By adjusting the relative surface tension and the like between the components during melt-kneading, a structure in which a vinyl chloride resin is dispersed in a polyacetal resin in a network form is formed, and the network structure thus obtained is It has been found that the acid resistance, the flame resistance are good, and the mechanical properties, the electrical properties, the heat resistance, the friction and wear properties, etc. inherent to the polyacetal resin are maintained, and the present invention has been reached. . That is, in the present invention, when the polyacetal resin A is used as a matrix and the vinyl chloride resin B is melt-kneaded, the surface tension at the melt-kneading temperature is at least the component B.
A and B components are characterized by melt-kneading a filler C having a larger size and an average particle size of 0.05 to 50 μm in a blending amount satisfying the following formulas (1) and (2). TECHNICAL FIELD The present invention relates to a method for producing a composition structure which has penetrated and dispersed in a network, and a molded article comprising a polyacetal resin composition structure obtained by the production method. B / (A + B) = 0.05-0.4 (weight ratio) (1) C / (B + C) = 0.1-0.7 (weight ratio) (2) Here, the vinyl chloride resin B generally means 30% by weight or less. This includes the case where the mixture contains the plasticizer for vinyl chloride used.

First, a description will be given of the dispersion form of the interpenetrating network structure referred to in the present invention. FIG. 1 is a schematic view showing the dispersion form in a conventional polymer blend system, which is compared with a polyacetal resin A which is a matrix resin. The vinyl chloride resin B having a small content is in a dispersed form separated into particles or layers. On the other hand, FIG. 2 is a schematic view showing an interpenetrating network structure according to the present invention. In this structure, a specific filler C is selectively included in a vinyl chloride resin B, and Although the content of B is small, the polyacetal resin A and the vinyl chloride resin B form a network with each other and have an entangled structure, thereby forming a substantially continuous phase.

That is, in the present invention, at least a part of the effective amount of the vinyl chloride resin B relative to the polyacetal resin A generally exhibits a dispersed structure in which most are substantially continuous with each other,
The present invention is characterized by exhibiting such a dispersion form, and solves a problem based on poor dispersibility, which is a fatal drawback of the conventional vinyl chloride resin compound. Such a dispersed structure can be confirmed by appropriately pulverizing or cutting a formed structure, for example, a molded piece, and decomposing and removing the component A as a matrix with an acid solution. In the case where the component B is dispersed in the form of a mesh, after the matrix A is decomposed and removed, the form is maintained as it is,
When the particles are separated and dispersed in the form of particles or layers, it can be understood that the form is broken and the original form is not retained. In addition, after the matrix is decomposed, the portion existing in a network can be known almost quantitatively by separating the matrix with an appropriate sieve.

Next, the components of the present invention will be described. The polyacetal resin of the component A used in the present invention is a polymer compound having an oxymethylene group (—CH ₂ O—) as a main structural unit, and other structural units other than the polyoxymethylene homopolymer and the oxymethylene group. It may be any of a copolymer, terpolymer or block copolymer containing a small amount, and may be a molecule having not only a linear but also a branched or crosslinked structure. The degree of polymerization, branching and cross-linking are not particularly limited, and those having melt processability (for example, a melt flow value (MR under a load of 2160 g at 190 ° C.)
F) should be 1.5 to 70). Further, two or more kinds of polyacetal resins may be used as the component A.

Next, the vinyl chloride resin of the component B used in the present invention may be any resin containing at least 50% by weight of vinyl chloride units, and may be a resin containing vinyl chloride or a monomer copolymerizable with vinyl chloride. It is a copolymer resin. Examples of monomers copolymerizable with vinyl chloride include carboxylic acid vinyl esters such as vinyl acetate and vinyl propionate; and unsaturated alcohol ethers such as methyl vinyl ether, isobutyl vinyl ether, cetyl vinyl ether, and (meth) allyl glycidyl ether. Vinylidene halides such as vinylidene chloride and vinylidene fluoride; diethyl maleate, butyl benzyl maleate, di-2-maleate
Unsaturated carboxylic acids such as hydroxyethyl, dimethyl itaconate, methyl (meth) acrylate, ethyl (meth) acrylate, lauryl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, and glycidyl (meth) acrylate Acid esters; vinyl-substituted aromatic carboxylic esters such as glycidyl p-vinylbenzoate; unsaturated sulfonic esters such as glycidyl vinyl sulfonate and glycidyl (meth) allyl sulfonate; α, β-unsaturated esters such as (meth) acrylonitrile Saturated nitriles; epoxide monoolefins such as butadiene monoxide and vinylcyclohexene monoxide; olefins such as ethylene and propylene; and aromatic vinyl compounds such as styrene, α-methylstyrene, p-methylstyrene, etc. Not limited to Also, such component B may be a mixture of two or more.

The vinyl chloride resin B of the present invention may contain a conventionally known plasticizer for vinyl chloride resin. Examples of such a plasticizer include phthalic acid di-2.
Phthalic esters such as ethylhexyl, dibutyl phthalate, diisodecyl phthalate, diisononyl phthalate;
Fatty acid esters such as diisodecyl adipate and di-2-ethylhexyl adipate; glycol esters such as diethylene glycol dibenzoate; phosphate esters such as tricresyl phosphate and trixylyl phosphate; trimellitic acid such as tri-2-ethylhexyl trimellitate Ester and the like, and those having good compatibility with the vinyl chloride resin can be used. As the amount of the plasticizer increases, processability and flexibility improve, but on the other hand, heat resistance and mechanical strength tend to decrease. Therefore, although the amount of the plasticizer is determined depending on the use, it is generally 0 to 30% by weight of the vinyl chloride resin B, more preferably 0 to 15% by weight.
It is. Such a plasticizer may be used in a state of being melt-kneaded with a vinyl chloride-based polymer in advance, or may be used by simply impregnating the vinyl chloride-based polymer or blending with the vinyl chloride-based polymer and the component A. .

The viscosity of the vinyl chloride resin B is not particularly limited. However, when the viscosity is significantly higher than that of the component A at the time of melt-kneading, it tends to be difficult to form a network-like dispersion form which is the object of the present invention. In general, the viscosity (poise) of the component A is preferably three times or less at the melt-kneading temperature, and particularly preferably lower when the blending amount of the component B is relatively small.

In the present invention, the compounding ratio of the components A and B is such that the component B is 5 to 40% by weight, preferably 10 to 35% by weight of the total weight of the components A and B. If the amount of component B is too small, it becomes difficult to develop a network-like dispersion form which is the object of the present invention, which does not contribute to the improvement of acid resistance and flame resistance, and if it is too large, the original properties of the polyacetal resin are lost. We do not like it.

The component C must have a surface tension at the melt-kneading temperature which is at least higher than the surface tension of the component B at the same temperature. Preferably, the surface tension difference from the component B is 2 dyn / cm or more. Things. The surface tension of each component is the surface tension at the melt-kneading temperature, and in the case of polyacetal resin A, can be evaluated by the hanging drop method at that temperature as generally used widely in thermoplastic resins. Here, the hanging drop method is a method in which a tube is set upright, and the surface tension of a liquid is determined from the shape behavior of a droplet in a state where a sample placed on the inner surface of the tube hangs as a droplet. Alternatively, the critical surface tension may be determined by the contact angle method calculated by the Zisman plot method. In the case of component B, especially component C, the latter is more suitable (for details, see Examples below). Incidentally, the surface tension of polyacetal resin A at 190 ° C. is about 21 dyn / c.
m, the value of the vinyl chloride resin B is generally 27 to 35 dyn / cm (for example, 10-2-dihexyl phthalate is used as a plasticizer.
The weight percentage of vinyl chloride resin is about 30 dyn / cm). Therefore, when the surface tension of the component C is kneaded at 190 ° C., it is preferable that the surface tension is higher than the value of the component B and is as high as possible.

The filler of the component C is preferably in the form of powder (or fiber) having an average particle size (or average fiber length) of 0.05 to 50 μm, more preferably 0.1 to 10 μm. The smaller the particle size, the more advantageous in forming a fine network structure. The amount of component C is suitably from 10 to 70% by weight, and preferably from 20 to 60% by weight, based on the total amount of components B and C. If it is too small, it is difficult to exert the effect of the present invention,
If it is too large, it affects the physical properties, which is not preferable.

The development of the network-like dispersion form of the present invention is based on the fact that the component C satisfying the above conditions is present at the time of melt-kneading. It is understood that the component B containing a large number of the components C extends in a branch shape in conjunction with the movement and dispersion by the kneading of the component C, and joins to form a network structure.

The filler of component C satisfies the above conditions, and may be an inorganic filler or an organic filler as long as the surface tension value is greater than the value of component B at the melt-kneading temperature as described above. Any shape such as a fiber shape, a powder shape, a plate shape or the like may be used depending on the purpose. For example, as the inorganic filler C, an average fiber length of 50 μm or less such as glass fiber, asbestos fiber, silica fiber, silica / alumina fiber, alumina fiber, zirconia fiber, boron nitride fiber, silicon nitride fiber, boron fiber, potassium titanate fiber, etc. Inorganic fibrous substances, or carbon black, graphite, silica, quartz powder, glass beads, milled glass fiber, glass balloon, glass powder, calcium silicate, aluminum silicate, kaolin, talc, clay, diatomaceous earth, wollastonite Metal oxides such as silicates, iron oxides, titanium oxides, zinc oxides, antimony trioxides, aluminas, metal carbonates such as calcium carbonate and magnesium carbonate, metal sulfates such as calcium sulfate and barium sulfate, etc. Ferrite, silicon carbide, silicon nitride, boron nitride, etc. , Average diameter 50μm following particulate or plate-like fillers such as glass flakes and the like, subject to selection as component C in consideration of the relative surface tension of the component B to be used. Further, as the organic filler C, a filler composed of a heat-resistant, high-melting thermoplastic resin, a thermosetting resin, or the like can be used as long as the above-mentioned conditions are satisfied. , Aromatic polyester resin, aromatic polyamide resin, aromatic polyimide resin, polystyrene resin, acrylic resin, MBS resin, melamine resin, phenol resin, epoxy resin, etc., satisfy the above conditions. As long as it is selected as the component C. These fillers can be used alone or in combination of two or more. If necessary, these fillers can be used as Component C by adjusting the surface tension by performing a surface treatment with an appropriate surface treatment agent or the like.

In order to further impart desired properties to the polyacetal resin composition structure of the present invention without impairing its purpose, conventionally known additives such as lubricants, lubricants, nucleating agents, dyes and pigments, Additives such as release agents, antioxidants, heat stabilizers, weather (light) stabilizers, hydrolysis stabilizers, thermoplastic resins other than components A and B, reinforcing agents other than component C, fillers, etc. You may.

The composition structure of the present invention can be prepared by various known methods, and at least three of A, B and C can be prepared.
It is necessary to heat and melt in the coexistence of the components, and to perform a kneading treatment for 30 seconds or more. Other components may be simultaneously used together, or may be added separately. Specifically, for example, A,
B and C may be uniformly mixed in advance by a mixer such as a tumbler or a Henschel mixer, and then supplied to a single- or twin-screw extruder to be melt-kneaded to form pellets, which may then be subjected to molding, or directly molded. May be. The melt kneading here is desirably performed at a melting temperature under a shear rate of 40 sec ^-1 or more. Particularly preferably, the shear rate is 100 to 500 sec- ¹ . The processing temperature is 5 ° C to 100 ° C higher than the temperature at which the resin component melts, and particularly preferably 10 ° C from the melting point.
Up to 60 ° C higher. If the temperature is too high, decomposition or abnormal reaction occurs, which is not preferable. The melt-kneading time is 30 seconds or more and 15 minutes or less, preferably 1 to 10 minutes.

[0017]

The structure of the polyacetal resin composition of the present invention has a structure in which a polyvinyl chloride resin is dispersed in a network in a polyacetal resin, and can be formed by a simple method. The surface condition is better than that of the molded article (particulate separation and dispersion), and the properties close to those of a polyacetal resin are maintained, and the acid resistance, the flame resistance and the like are improved, so that many applications are expected.

[0018]

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.

Examples 1 and 2 (A) Polyacetal resin (manufactured by Polyplastics Co., Ltd., Duracon) having a surface tension value (190 ° C.) shown in Table 1
(B) a vinyl chloride (PVC) -based resin impregnated with 10% by weight of di-2-ethylhexyl phthalate (DOP), (C) talc particles (manufactured by Fuji Talc Kogyo KK, average particle size 2 μm or 20 μm)
m) were mixed in the proportions shown in Table 1, and kneaded at a set temperature of 190 ° C. at a screw rotation speed of 80 rpm (shear speed: about 100 sec ⁻¹ ) using a 30 mm twin-screw extruder to form pellets. Then
Test pieces were prepared from the pellets using an injection molding machine, and the following characteristics were evaluated. The results are shown in Table 1.

Measurement method of surface tension (the following examples are also based on this method ) For polyacetal resin, Kyowa Interface Science Co., Ltd.
Using the automatic interfacial tensiometer PD-Z type, the hanging drop method (Maruzen Co., Ltd.
78-79) in an atmosphere of 190 ° C. The surface tension of the polyacetal resin was 21 dyn / cm. or,
The vinyl chloride resin B was processed into a film by a press at about 150 ° C, and the contact angle method (Maruzen Co., Ltd. new experiment) was carried out using an automatic contact angle meter CA-Z manufactured by Kyowa Interface Science Co., Ltd. The critical surface tension at each temperature was measured in accordance with the method described in Science Course, Vol. 18, “Interface and Colloid” (1977), pp. 93-106, and the temperature coefficient was determined. The measurement results are as follows, 19
Approximately 30 when converted to the surface tension of vinyl chloride resin at 0 ° C.
dyn / cm. 25 ° C Surface tension 42dyn / cm 60 ° C Surface tension 40dyn / cm 80 ° C Surface tension 39dyn / cm Temperature gradient (−dr / dT) = 0.05 dyn / cm It was about 63 dyn / cm in terms of surface tension at 190 ° C.

Confirmation method of network structure (the following example is also based on this) A molded piece cut into a size of 10 × 10 × 3 mm was subjected to a hydrochloric acid ethanol solution (32
N hydrochloric acid: ethanol = 1: 3 (vol)) at room temperature for 24 hours.
After a time treatment to decompose and remove the polyacetal resin A as a matrix resin, the dispersion form of the vinyl chloride resin B that does not decompose under these conditions was examined. Here, if the vinyl chloride resin B is a particle dispersion as in the prior art, the form of the molded piece does not remain, and the deposit of the particulate vinyl chloride resin B is only observed with the naked eye or an optical microscope. . On the other hand, when the vinyl chloride resin B has a network structure as in the present invention, the polyacetal resin A as the matrix resin remains in the form of a molded piece even after being decomposed and removed. And suggests that it is excellent in acid resistance. Furthermore, formation of an interpenetrating network structure can be confirmed by observation under a scanning electron microscope. Incidentally, an electron micrograph showing the particle structure (network structure) of the composition structure of Example 1 after the decomposition treatment is shown in FIG. or,
As a quantitative evaluation method of the network structure portion, after the acid treatment by the above method, the mesh structure portion was separated by a 12-mesh sieve, and the remaining weight was examined.
Although the particulate dispersion portion does not pass through the sieve but remains in the network structure portion, the remaining weight% means the weight of (B + C) in the network structure portion.

Tensile elongation : Measured according to the method of ASTM D-638. Flame resistance : The test piece was ignited for 10 seconds by the method specified in JIS K 6911, and thereafter, the flame was removed and the time (second) until the flame or the resin dropped was evaluated.

Comparative Examples 1-4 For comparison, polyacetal resin A alone, DOP impregnated PVC
When the particle size of the component C is out of the range of the present invention when the particle diameter of the component C is out of the range of the present invention, the composition is prepared in the same manner as in Example 1, and the resin is molded. evaluated. The results are shown in Table 1.

Examples 3 to 6 and Comparative Examples 5 to 8 Compositions were prepared in the same manner as in the previous example except that the amounts of components A, B and C were changed as shown in Table 2, molded and evaluated. . The results are shown in Table 2.

Examples 7 to 8, Comparative Example 9 Polyamide particles (manufactured by Toray Industries, Inc., average particle size: 5 μm), calcium carbonate (manufactured by Shiraishi Industry Co., Ltd., average particle size: 1 μm) were used as the filler C. For this reason, a composition was prepared in the same manner as in the previous example except that silicone rubber particles (manufactured by Toray Silicone Co., Ltd., average particle size 1 μm) were used, molded and evaluated. The results are shown in Table 3.

[0026]

[Table 1]

[0027]

[Table 2]

[0028]

[Table 3]

[Brief description of the drawings]

FIG. 1 is a schematic view showing a state of dispersion of a structure by a conventional polymer blend system.

FIG. 2 is a schematic diagram showing a dispersion state of a structure according to the present invention.

FIG. 3 is an electron micrograph showing a particle structure (network structure) of a structure according to the present invention (Example 1) after treatment with a hydrochloric acid solution.

Claims (4)

(57) [Claims] 1. A filler comprising a polyacetal resin A as a matrix and a vinyl chloride resin B melt-kneaded, wherein the filler has a surface tension at a melt-kneading temperature at least higher than that of the component B and an average particle size of 0.05 to 50 μm. A method for producing a composition structure in which components A and B penetrate into each other and are dispersed in a network, wherein C is melt-kneaded in a compounding amount satisfying the following formulas (1) and (2). B / (A + B) = 0.05-0.4 (weight ratio) (1) C / (B + C) = 0.1-0.7 (weight ratio) (2) 2. The method for producing a composition structure according to claim 1, wherein the surface tension of the filler C at the melt-kneading temperature is at least 2 dyn / cm higher than the surface tension of the vinyl chloride resin B. 3. The method for producing a resin composition structure according to claim 1, wherein the vinyl chloride resin B is a mixture containing 0 to 30% by weight of a plasticizer for vinyl chloride. 4. A molded article comprising a resin composition structure produced by the method according to claim 1.