JPH05179113A - Resin composition structure based on polyalkylene phthalate and manufacture thereof - Google Patents

Abstract

PURPOSE:To provide a resin composition structure which solves the defects due to dispersibility by forming an interpenetrating network structure in a composition comprising a polyalkylene phthalate resin and a thermoplastic polystyrene resin, maintains the characteristics of the polyalkylene phthalate resin including mechanical properties, gives a reduced shrinkage rate when formed into moldings to improve the dimensional accuracy, and has an improved fusibility with other resins. CONSTITUTION:In the melt-kneading of a thermoplastic polystyrene resin B with a matrix of a polyalkylene phthalate resin A, a filler C, which has a lower surface tension at the melt-kneading temperature than the component B and an average particle size of 0.5-50mum, is added in amounts satisfying the relationship: B/(A+B)=0.05-0.40 (by weight) and C/(B+C)=0.1-0.7 (by weight).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure in which a polyalkylene phthalate resin is used as a matrix, and a thermoplastic polystyrene resin is dispersed in a network in the matrix, and a method for producing the structure, which is formed by an inexpensive and simple method. It retains the physical properties of polyalkylene phthalate resin as a molded product, especially chemical resistance, dimensional accuracy, and fusion property with styrene resin,
A resin molded product having improved mechanical properties and the like is provided.

[0002]

BACKGROUND OF THE INVENTION Polyalkylene phthalate resins represented by polyethylene terephthalate or polybutylene terephthalate are excellent in moldability and have well-balanced mechanical properties, low water absorption and chemical resistance. It has gas barrier properties, etc., and is superior in heat deterioration characteristics at high temperatures compared to other thermoplastic resins and has a high heat distortion temperature. It's being used. However, with the expansion of fields of use, the performance requirements for resins tend to become more sophisticated and specialized, and examples of such requirements include improvements in dimensional accuracy due to molding shrinkage, fusion resistance with other resins, and the like. .. That is, for example, a polyalkylene terephthalate resin is liable to cause mold shrinkage due to its high crystallinity and warp / deformation of a molded product due to the shrinkage, resulting in a problem in use in fields such as large-sized parts and precision electronic parts. ..
Further, it has poor adhesiveness and fusion property with other resins, especially styrene resin, which may cause a problem when it is used as a laminated film with styrene resin or the like, or as a composite molded product for blow molding. is there.

As a method for solving such a problem, blending of other resins has been attempted. One of them is the blending of thermoplastic polystyrene-based resins, and it is considered to be an effective means for improving the molding shrinkage of polyalkylene phthalate-based resins and the fusion property with polystyrene-based resins. However, according to the studies by the present inventors, when a thermoplastic polystyrene-based resin is simply added to a polyalkylene phthalate-based resin as a main component, the dispersion structure of the thermoplastic polystyrene-based resin phase is separated into islands. Therefore, the molding shrinkage or the improvement of the fusion property with the styrene resin or the like is not yet sufficient, and a large amount of the thermoplastic polystyrene resin is blended, and therefore the polyalkylene phthalate resin originally has There is a problem that the mechanical properties, chemical resistance, and heat resistance are deteriorated.

In order to ameliorate such drawbacks, the present invention improves the dispersibility of both components when a thermoplastic polystyrene resin is blended with the polyalkylene phthalate resin, and features of the polyalkylene phthalate resin such as mechanical properties. To improve the dimensional accuracy by reducing the shrinkage rate during molding.
Moreover, it aims at improving the fusion-bonding property with a polystyrene resin.

[0005]

SUMMARY OF THE INVENTION In view of the above problems, the present inventors have been keen to improve the dispersion form of both components in a polymer blend containing a polyalkylene phthalate resin as a main component and a thermoplastic polystyrene resin. As a result of examination, a composition in which a thermoplastic polystyrene resin is dispersed in a polyalkylene phthalate resin in a network by adjusting the relative surface tension between each component during melt-kneading in combination with a specific filler The resulting structure has a low shrinkage rate during molding, is excellent in dimensional accuracy, has a good fusion property with a styrene resin, etc., and has a polyalkylene phthalate resin originally. The present invention has been completed by finding out that the mechanical properties that are maintained are maintained. That is, the present invention relates to the polyalkylene phthalate resin A
When the thermoplastic polystyrene resin B is melt-kneaded by using as a matrix, a filler C having a surface tension at the melt-kneading temperature lower than that of the component B and an average particle diameter of 0.05 to 50 μm is prepared by the following formula (1). And a composition obtained by melt-kneading in a blending amount satisfying (2), wherein components A and B intrude into each other and are dispersed in a mesh shape, and a composition obtained by the method. The present invention relates to a molded article composed of a structure. B / (A + B) = 0.05 to 0.40 (weight ratio) (1) C / (B + C) = 0.1 to 0.7 (weight ratio) (2) First, the dispersion form of the interpenetrating network structure referred to in the present invention will be described. FIG. 1 is a schematic diagram showing a particle dispersion morphology in a conventional polymer blend system, in which a thermoplastic polystyrene resin B having a relatively small amount as compared with a polyalkylene phthalate resin A which is a matrix resin is separated into particles. It has a morphology. On the other hand, FIG. 2 is a schematic diagram showing the form of the interpenetrating network structure of the present invention. In this structure, the thermoplastic polystyrene resin B contains a specific filler C, and the thermoplastic polystyrene resin B
Despite the low content of polyalkylene phthalate-based resin A and thermoplastic polystyrene-based resin B, they form a network with each other to form an intertwined structure to form a continuous phase. That is, in the present invention, at least a partial effective amount of the thermoplastic polystyrene-based resin B with respect to the polyalkylene phthalate-based resin A generally exhibits a dispersed structure in which most of them are substantially continuous with each other, and the present invention is to exhibit such a dispersed form. It has the characteristics of the invention, and has further improved mechanical properties, shrinkage ratio at the time of molding, fusion property with other resins, etc., as compared with the case of simply blending a thermoplastic polystyrene resin (particulate dispersion). is there.

Such a dispersed structure can be confirmed by appropriately crushing or cutting the formed structure, for example, a molded piece, and selectively decomposing and removing the component A which is a matrix with an appropriate alkaline solution. .. When the component B is dispersed in the form of a mesh, the form is retained as it is even after the matrix A is decomposed and removed, whereas when the component B is separated and dispersed in the form of particles or layers, the form is You can also understand that the original shape does not stay. In addition, after the matrix is decomposed and separated by an appropriate sieve, it is possible to almost quantitatively determine the meshed portion.

Next, the components used in the present invention will be described. The polyalkylene phthalate resin as the component A used in the present invention is a saturated alkylene phthalate polymer or copolymer obtained by condensation polymerization using various phthalic acids and various alkylene diols as main components. Among them, a polyalkylene terephthalate polymer or copolymer containing terephthalic acid or its ester-forming derivative and an alkylene diol having 2 to 8 carbon atoms as main components is preferable, and isophthalic acid, cyclohexanedimethanol and bisphenol are used as the copolymerization component. Preferred examples include A, 2,2-bis (β-hydroxyethoxyphenyl) propane, halogen-substituted compounds thereof, and ester-forming derivatives thereof. Also, trimethylol propane,
It may be a polyalkylene phthalate resin having a branched structure in which a small amount of a polyfunctional monomer such as pentaerythritol, trimellitic acid, pyromellitic acid, trimesic acid and their ester-forming derivatives are used together. or,
The degree of polymerization is not particularly limited as long as it has molding processability. Specifically, for example, polybutylene terephthalate, polybutylene terephthalate isophthalate copolymer, polyethylene terephthalate, polyethylene terephthalate isophthalate copolymer, polybutylene-cyclohexane dimethylene terephthalate copolymer, polycyclohexane dimethanol terephthalate, polycyclohexane dimethanol Particularly preferred examples include polyalkylene terephthalate homopolymers and copolymers such as terephthalate isophthalate copolymers. The component A may be a mixture of two or more kinds.

The thermoplastic styrene resin as the component B used in the present invention is mainly styrene and is obtained by a radical polymerization reaction or an ionic polymerization reaction. Industrially, it is bulk polymerization, solution polymerization, Any of those obtained by suspension polymerization, emulsion polymerization and the like can be used. In addition to polystyrene, the thermoplastic polystyrene resin B of the present invention contains styrene as a main component and copolymerizes with other reactive monomers such as vinyl compounds and diene compounds, as long as the properties thereof are not significantly impaired. A rubber component may be introduced. In particular, polystyrene, poly-α-methylstyrene, or a copolymer containing them as a main component and acrylic acid, methacrylic acid, or an ester thereof, acrylonitrile, butadiene, chlorinated ethylene, or the like is also preferably used. The degree of polymerization is also not particularly limited, and may be any as long as it is thermoplastic and has moldability, but one having a relatively low viscosity, for example, one having a lower viscosity than the component A at the melt-kneading temperature. Preferred for the purposes of the present invention.

The mixing ratio of the components A and B in the present invention is such that the component B is 5 to 40% by weight, preferably 10 to 35% by weight based on the total weight of the components A and B. When the amount of the component B is too small, it is difficult to obtain the network-like dispersed form which is the object of the present invention, and the effects such as the improvement of the shrinkage ratio and the fusion property with other resins cannot be obtained. On the other hand, if it is too large, the original features of the polyalkylene phthalate resin are lost, which is not preferable.

Next, the component C must have a surface tension at the melt-kneading temperature which is at least smaller than the surface tension of the component B at the same temperature, and preferably the surface tension difference from the component B is 2 dyn / cm or less. It is a thing. For the surface tension of each component, it is necessary to know the surface tension at the melt-kneading temperature,
In the case of a thermoplastic resin, it can be evaluated by the hanging drop method at that temperature, as is generally used. Here, the hanging drop method is a method in which the surface tension of the liquid is determined from the shape behavior of the droplet in a state in which the tube is set up vertically and the sample contained therein forms droplets and hangs at the tube end. For those that do not melt (Component C), the critical surface tension can be obtained and evaluated by the contact angle method calculated by the Zisman plotting method (for details, see Examples below).

Regarding the surface tension relationship between the component A and the component B, it is necessary that the surface tension of the component B is smaller than that of the component A at the melt-kneading temperature, but generally, the melting of the thermoplastic styrene resin B is performed. The surface tension at the kneading temperature is smaller than that of the polyalkylene terephthalate resin A, and this relative relationship is satisfied. By the way, the value of the surface tension of the polyalkylene terephthalate resin A at 245 ° C is 30-
38 dyn / cm (For example, polybutylene terephthalate has 36 dyn / cm
cm, polyethylene terephthalate is 30 dyn / cm), and the value of the thermoplastic polystyrene resin B is 24 to 30 dyn / cm (for example, polystyrene is about 25 dyn / cm, and styrene-acrylonitrile copolymer is about 29 dyn / cm). Therefore, when kneading at 245 ° C., the surface tension of the component C needs to be equal to or lower than the value of the component B, and it is preferable that the surface tension is as low as possible.

The filler of the component C is preferably powdery or granular (or fibrous) having an average particle size (or average fiber length) of 0.05 to 50 μm, more preferably 0.1 to 10 μm.
Is. The smaller the particle size, the more advantageous it is in forming a fine mesh structure. The content of the component C is appropriately 10 to 70% by weight, preferably 20 to 70% by weight based on the total weight of the components B and C.
60% by weight. If it is too small, the effect of the present invention is difficult to be exhibited, and if it is too large, the physical properties are affected, which is not preferable.

In the development of the network-like dispersed form of the present invention, since the component C satisfying the above conditions is present at the time of melt-kneading, the particulate component C selectively selects the component B due to the influence of the relative surface tension. It is understood that the component B, which is included by the above-mentioned, and which contains a large number of the component C, extends in a branch shape in association with the movement and dispersion of the component C due to the kneading, and is joined to form a network structure.

The filler of the component C may be an inorganic filler or an organic filler as long as the above conditions are satisfied and the surface tension value is smaller than the value of the component B at the melt-kneading temperature as described above. As for the shape, an arbitrary shape such as fibrous, powdery, plate-shaped or the like is used. For example, a fluorine-based resin or rubber, a silicone-based resin or rubber, etc. may be mentioned. Further, it can be effectively used as the component C by subjecting a widely used powdery or granular inorganic filler to a surface treatment with the above-mentioned fluorine-based resin, silicone-based resin or other suitable surface-treating agent to adjust the surface tension. it can.

The composition structure of the present invention may further have conventionally known additives such as a lubricant, a lubricant, a nucleating agent, a dye / pigment, and a release agent in order to impart desired properties to the composition structure without impairing its purpose. , Antioxidants, heat stabilizers, weathering (light) stabilizers, hydrolysis stabilizers, thermoplastic resins other than components A and B, fibrous reinforcing agents other than component C, powdery granules, plate-like fillers, etc. You may mix an additive. The composition structure of the present invention can be prepared by various known methods, but it is preferable that the composition is heated and melted in the coexistence of at least three components A, B and C, and kneaded for 30 seconds or longer. Ingredients may be used in combination at the same time or may be added separately. Specifically, for example, the components A, B, and C are uniformly mixed in advance with a kneader such as a tumbler or a Henschel mixer, and then supplied to a single-screw or twin-screw extruder to be melt-kneaded into pellets. It may be subjected to molding or may be molded directly. The melt-kneading referred to here is preferably carried out at a melting temperature under a shear rate of 40 sec ^-1 or more. Particularly preferred shear rate is 100 to 500 sec ^-1
Is. The processing temperature is 5 ° C above the melting temperature of the resin component
To 100 ° C. higher, particularly preferably 10 above the melting point.
The temperature is higher by 60 ° C to 60 ° C. If the temperature is too high, decomposition or abnormal reaction occurs, which is not preferable. The melt-kneading time is
It is 30 seconds or more and 15 minutes or less, preferably 1 to 10 minutes.

[0016]

The polyalkylene phthalate resin composition structure of the present invention has a structure in which a thermoplastic polystyrene resin is dispersed in a polyalkylene phthalate resin in a mesh form, and can be formed by a simple method. Compared to the conventional composition (particulate separation / dispersion) that simply combines both components, it retains physical properties close to those of polyalkylene phthalate resin, has excellent mechanical properties, molding shrinkage or dimensional accuracy, styrene resin, etc. The fusion property with other resins is further improved, and many applications are expected.

[0017]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited thereto.

Examples 1 and 2 Polybutylene terephthalate resin A (PBT) (Duranex, manufactured by Polyplastics Co., Ltd.) having a surface tension value (245 ° C.) shown in Table 1 and thermoplastic polystyrene resin B (Sumitomo Chemical Co., Ltd.) Industrial Co., Ltd.), silicone rubber particles C
(SP) (Tore Silicone Co., Ltd., average particle size 1μ
m or 20 μm) at the ratio shown in Table 1, and set the temperature to 2
Screw rotation speed using a twin screw extruder with an inner diameter of 30 mm at 45 ° C
The mixture was melt-kneaded at 80 rpm (shear rate of about 100 sec ^-1 ) and pelletized. Then, a test piece was prepared from the pellet by an injection molding machine, and the characteristics were evaluated as follows. The results are shown in Table 1.

Measuring method of surface tension For polybutylene terephthalate resin and thermoplastic styrene resin, an automatic interfacial tension meter PD-Z type manufactured by Kyowa Interface Science Co., Ltd. was used and a hanging drop method (Maruzen Co., Ltd. new experiment) was used. It was measured in an atmosphere of 245 ° C. according to the method described in pages 78-79 of Science Course Vol. 18, “Interface and Colloid” (1977)). Polybutylene terephthalate resin is 36 dyn / cm, thermoplastic polystyrene resin is
It was 25 dyn / cm. Silicone rubber particles are processed into a film with a press machine at about 300 ° C, and an automatic contact angle meter CA-Z manufactured by Kyowa Interface Science Co., Ltd. is used. The critical surface tension and temperature coefficient were measured according to the method described in Pages 93-106 of Science Course Vol. 18, "Interface and Colloid" (1977). The surface tension of the silicone rubber particles at 245 ° C. was about 9 dyn / cm. 25 ℃ Surface tension 19dyn / cm 60 ℃ Surface tension 17dyn / cm 80 ℃ Surface tension 16dyn / cm Temperature gradient (-dr / dT) = 0.05 Confirmation method of network structure 1N hydroxylated molded piece cut into 10 × 10 × 3mm Put in an aqueous solution of sodium and reflux at 60 ° C for 12 hours to decompose and elute the matrix resin, polybutylene terephthalate resin, and then observe the morphological changes with the naked eye, optical microscope and electron microscope. The dispersion morphology of the plastic polystyrene resin was investigated. Here, if the thermoplastic polystyrene resin is particle-dispersed as in the conventional case, the form of the molded piece is not retained, and only a deposit of the particulate thermoplastic polystyrene resin is observed. On the other hand, when the thermoplastic polystyrene resin has a network structure as in the present invention, the molded piece retains its shape, and this is observed with the naked eye or an optical microscope. Furthermore, the network structure can be more clearly confirmed by enlarging and observing with a scanning electron microscope. Incidentally, the electron micrograph showing the particle structure (mesh structure) of the composition structure of Example 1 after the decomposition treatment is shown in FIG. Further, as a quantitative evaluation method of this network structure, after the matrix resin A was eluted and removed by the above-mentioned method, it was separated with a 12-mesh sieve and the residual weight was examined. The particulate dispersion portion does not pass through the sieve and remains, but the network structure portion remains, so the residual weight% means the weight of (B + C) of the network structure portion. Tensile strength and elongation : Measured according to the method of ASTM D638. Fusing property : A 1 mm-thick test piece was prepared with a press machine, was overlaid with a polystyrene test piece prepared in the same manner, was fused with a press machine at 245 ° C. for 2 minutes at 50 kg / cm ² , and was then rapidly cooled. 1 mm
The fusion strength of the thick sample was measured according to the method of JIS C6481. Molding shrinkage rate : ASTM tensile test pieces were molded, the dimensions of certain parts of the molded products were measured accurately, and the difference with respect to the dimensions of the corresponding mold was shown in%.

Comparative Examples 1 to 4 Polybutylene terephthalate resin A alone, polystyrene resin B alone, a combination of components A and B containing no filler C, or the silicone rubber particles C have the same particle size. When the combination was out of the scope of the invention, the composition was prepared in the same manner as in Example 1, molded and evaluated. The results are also shown in Table 1.

Examples 3 to 6 and Comparative Examples 5 to 8 Molded pieces were prepared and evaluated in the same manner as in Example 1 except that the compounding amounts of the components A, B and C were changed as shown in Table 2. Table 2 shows the evaluation results
Shown in.

Example 7, Comparative Examples 9 to 10 Fluorine rubber particles as a filler C (Daikin Industry Co., Ltd.)
Manufactured by Shiraishi Industry Co., Ltd. (average particle size 1 μm) and talc particles (average particle size 2 μm) were used to prepare a composition in the same manner as in Example 1. It was prepared, molded and evaluated. The results are shown in Table 3.

Examples 8 to 9 and Comparative Examples 11 to 12 Polybutylene terephthalate resin as component A was polyethylene terephthalate resin (PET) (Kanebo Co., Ltd.,
When it is changed to velpet), polystyrene resin is used as the component B, and the styrene-acrylonitrile copolymer (A
S) (AS230, manufactured by Nippon Synthetic Rubber Co., Ltd.) was used to prepare a composition in the same manner as in Example 1, and the composition was molded and evaluated. The results are shown in Table 4.

[0024]

[Table 1]

[0025]

[Table 2]

[0026]

[Table 3]

[0027]

[Table 4]

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a dispersed state of a structure according to a conventional polymer blend system.

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

FIG. 3 is an electron micrograph showing a particle structure (mesh structure) after the alkaline aqueous solution decomposition treatment of the structure according to the present invention (Example 1).

Claims (4)

[Claims] 1. When melt-kneading a thermoplastic polystyrene resin B using a polyalkylene phthalate resin A as a matrix, the surface tension at the melt-kneading temperature is smaller than that of the component B, and the average particle diameter is 0.05 to 50 μm. Production of a composition structure in which a certain filler C is melt-kneaded in a blending amount satisfying the following formulas (1) and (2) and components A and B intrude into each other and are dispersed in a mesh form. Law. B / (A + B) = 0.05 to 0.40 (weight ratio) (1) C / (B + C) = 0.1 to 0.7 (weight ratio) (2) 2. The method for producing a composition structure according to claim 1, wherein the surface tension of the component C at the melt-kneading temperature is smaller than that of the component B by 2 dyn / cm or more. 3. The thermoplastic polystyrene resin B is polystyrene or a copolymer resin containing styrene as a main component,
The method for producing a composition structure according to claim 1 or 2, wherein the surface tension at the melt-kneading temperature is lower than that of the component A. 4. A molded article comprising a composition structure produced by the method according to claim 1.