JPH10158431A - Reinforced thermoplastic resin composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a compsn. which contains a layered silicate homogeneously dispersed therein at a molecular level without causing flocculation at all by using a suspension comprising a dispersion medium and a layerd silicate homogeneously dispersed therein with a dispersing and a monomer for forming a thermoplastic resin and by conducting the polymn. of the monomer simultaneously with the removal of the dispersant. SOLUTION: 'To homogeneously disperse at a molecular level' means that the layered silicate is dispersed in a thermoplastic resin matrix with distances between layers of, on average, at least 20Å. A swellable fluoromica mineral is the most favorable as the layered silicate in terms of whitness. 0.01-100 pts.wt. layered silicate is compounded based on 100 pts.wt. thermoplastic resin formed from the monomer. An example of the dispersant is a tripolyphosphate. E xamples of the dispersion medium are water and methanol. 0.1-20 pts.wt. dispersion medium is used based on 100 pts.wt. layered silicate, and 0.001-10 pts.wt. dispersant, based on 100 pts.wt. dispersion medium.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reinforced thermoplastic resin composition in which a layered silicate is uniformly dispersed at a molecular level and in which there is no aggregated structure of the layered silicate.

[0002]

2. Description of the Related Art Resin compositions in which a thermoplastic resin such as polyamide or polyester is reinforced with a fibrous material such as glass fiber or carbon fiber or an inorganic filler such as calcium carbonate are widely known. However, these reinforcing materials have poor affinity with thermoplastic resins, and although the mechanical strength and heat resistance of the reinforced thermoplastic resin are improved, the toughness is reduced and the resin composition reinforced with fibrous material is molded. There was a problem that the warp of the product became large. In addition, the resin compositions reinforced with these inorganic fillers have a problem that the mechanical strength and heat resistance do not improve unless a large amount of the filler is added.

As an attempt to improve the disadvantages of such a reinforced thermoplastic resin composition, for example, a resin composition comprising a polyamide and a clay mineral represented by montmorillonite has been proposed (Japanese Patent Application Laid-Open No. Sho 62-74957). JP-A-63-23
0766, JP-A-2-102261, and JP-A-3-7729).

[0004] These resin compositions attempt to form a composite in which the clay mineral is uniformly dispersed at the molecular level by infiltrating polyamide chains between layers of the clay mineral. For this purpose, montmorillonite is used. When used, as described in each of the above publications, before blending montmorillonite with a polyamide or a monomer forming a polyamide, the montmorillonite is brought into contact with a swelling agent such as an aminocarboxylic acid, so that the interlayer distance of montmorillonite is increased. The treatment for expanding was indispensable. further,
In order for the montmorillonite to be evenly dispersed in the polyamide matrix, it is necessary that the polyamide chains penetrate into all layers of the montmorillonite,
This is difficult in the above-described composite, and usually, the aggregated structure of montmorillonite partially exists.

[0005] As an attempt to solve such a problem,
The present inventors have found that a polyamide composite having excellent mechanical strength and heat resistance can be obtained by adding a specific swellable fluoromica-based mineral to a monomer that forms a polyamide and polymerizing the same. (JP-A-6-248176)
However, also in this composite, the aggregate structure of the swellable fluoromica-based mineral was partially present.

[0006]

SUMMARY OF THE INVENTION The present invention aims to provide a reinforced thermoplastic resin composition in which the layered silicate is uniformly dispersed at the molecular level and in which there is no aggregated structure of the layered silicate. Things.

[0007]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems, and its gist is as follows. Using a suspension in which a layered silicate is uniformly dispersed in a dispersion medium with a dispersant and a monomer that forms a thermoplastic resin, the layered silicate that can be produced by removing the dispersion medium and simultaneously polymerizing the monomer is a molecule. A reinforced thermoplastic resin composition uniformly dispersed at a level.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.

The reinforced thermoplastic resin composition of the present invention is obtained by uniformly dispersing a layered silicate at a molecular level in a thermoplastic resin. The term “uniformly dispersed at the molecular level” means a state where each layered silicate maintains an average interlayer distance of 20 ° or more when dispersed in a thermoplastic resin matrix. Here, the interlayer distance refers to the distance between the centers of gravity of the layered silicate plates, and the uniform dispersion means that the layered silicates are formed in parallel with each other or with a multilayer having an average overlap of 5 layers or less. It means a state where 50% or more, preferably 70% or more, of them are dispersed without forming a lump at random or in a state where parallel and random are mixed. Specifically, wide-angle X-ray diffraction measurement is performed on the pellets of the reinforced thermoplastic resin, and it can be confirmed from the disappearance of the peak due to the thickness direction of the layered silicate.

In the present invention, first, it is necessary to prepare a suspension in which the layered silicate is uniformly dispersed in the dispersion medium. For this purpose, the layered silicate is dispersed by using a dispersant. It is necessary to disperse them evenly in it.

The layered silicate in the present invention has a structure comprising a negatively charged layer mainly composed of silicate and a positive charge (ion) interposed between the layers.

Preferred examples of such a layered silicate include:
Smectite group (eg, montmorillonite, beidellite, saponite, hectorite, sauconite), vermiculite group (eg, vermiculite), mica group (eg, fluoromica, muscovite, paragonite phlogopite, biotite, lepidolite), brittle mica group ( For example, there are margarite, clintite, anandite), chlorite (for example, dombasite, sudoite, coucheite, clinochlore, chamosite, nimmite) and the like.

These layered silicates may be naturally occurring, artificially synthesized or modified, or treated with an organic compound such as an onium salt. Good.

Among the above-mentioned layered silicates, swellable fluoromica-based minerals are most preferable in terms of whiteness, which is represented by the following formula and can be easily synthesized. α (MF) · β (aMgF ₂ · bMgO) · γSiO ₂ (where M represents sodium or lithium, α, β,
γ, a and b each represent a coefficient, and 0.1 ≦ α ≦ 2, 2 ≦ β
≦ 3.5, 3 ≦ γ ≦ 4, 0 ≦ a ≦ 1, 0 ≦ b ≦ 1, a + b
= 1. )

As a method for producing such a swellable fluoromica-based mineral, for example, silicon oxide, magnesium oxide, and various fluorides are mixed, and the mixture is heated at a temperature of 1400 to 1500 ° C. in an electric furnace or a gas furnace. There is a so-called melting method in which the mica is completely melted in the range and the fluorine mica-based mineral grows in the reaction vessel during the cooling process.

There is also a method in which talc is used as a starting material, and alkali metal ions are intercalated into the starting material to obtain a swellable fluoromica-based mineral (Japanese Patent Laid-Open No. 2-1494).
No. 15). In this method, talc is mixed with an alkali silicate or an alkali fluoride, and is mixed in a magnetic crucible for about 7 minutes.
By performing a short heat treatment at 00 to 1200 ° C., a swellable fluoromica-based mineral can be obtained.

At this time, the amount of alkali silicate or alkali fluoride mixed with talc is 10 to 35% of the whole mixture.
It is preferable to be within the range of weight%, and if it is out of this range, the production rate of the swellable fluoromica-based mineral decreases, which is not preferable.

In order to obtain the above-mentioned swellable fluoromica-based mineral, the alkali metal of alkali silicate or alkali fluoride must be sodium or lithium. These alkali metals may be used alone or in combination. In addition, among alkali metals, swellable fluorine mica is not obtained in the case of potassium, but it can be used in combination with sodium or lithium, and for the purpose of adjusting the swellability in a limited amount. .

Further, in the step of producing the swellable fluoromica-based mineral, it is possible to adjust the swellability of the resulting swellable fluoromica-based mineral by adding a small amount of alumina.

Examples of the dispersing agent in the present invention include tripolyphosphate, metaphosphate, orthophosphate, humate, ligninsulfonate, tannate, silicate, acrylate, polyacrylate, sulfophosphate and the like. Styrene maleic anhydride copolymer, 1-hydroxyethane-1,1
-Diphosphonic acid, hydroxides and salts of alkali metals such as sodium hydroxide and sodium carbonate, and among these, tripolyphosphate, humate, ligninsulfonate, tannate, acrylate And polyacrylic acid salts are particularly preferred, and one or more of these can be used.

Examples of the dispersion medium include water, methanol, ethanol, propanol, ethylene glycol, butanediol, glycerin, dimethyl sulfoxide, N, N-dimethylformamide, N-methylpyrrolidone, acetic acid,
Formic acid, pyridine, aniline, phenol, acetone, acetonitrile, ethylene carbonate, propylene carbonate, methyl cellosolve, methylene chloride, chloroform, n-hexane, etc.
More than one species can be used.

In order to prepare a suspension in which the layered silicate is uniformly dispersed in the dispersion medium using the dispersant, the amount of the dispersant is as follows:
It is preferably 0.1 to 20 parts by weight based on 100 parts by weight of the layered silicate. If the amount is less than 0.1 part by weight, it is difficult to obtain a dispersion in which the layered silicate is uniformly dispersed, while if the amount exceeds 20 parts by weight, the rigidity of the reinforced thermoplastic resin composition is reduced. It is not preferable because it lowers.
The dispersant is used in an amount of 0.001 to 10 parts by weight based on 100 parts by weight of the dispersion medium.
It is preferred to add in parts by weight.

Next, in the present invention, the above-mentioned suspension and the monomer forming the thermoplastic resin are used, and the monomer is polymerized simultaneously with the removal of the dispersion medium, whereby the layered silicate is uniformly dispersed at the molecular level. Reinforced thermoplastic resin composition.

At this time, the compounding amount of the layered silicate is 0.01 to 1 with respect to the monomer amount forming 100 parts by weight of the thermoplastic resin.
Preferably it is 00 parts by weight, more preferably 0.1 to 20 parts by weight. If the amount is less than 0.01 part by weight, a resin composition having excellent mechanical strength, heat resistance, dimensional stability, etc. cannot be obtained. On the other hand, if the amount is more than 100 parts by weight, the toughness when formed into a molded product is undesirably increased.

Further, at the time of polymerization of the monomer, an acid having a pKa of 0 to 5 or a negative acid in water at 25 ° C. may be added. Although the role of this acid is not clear, it is thought that a part of the thermoplastic resin is cationized, the interaction with the negatively charged layered silicate increases, and the rigidity and heat resistance of the resin composition improve. It is.

Such an acid may be an inorganic acid or an organic acid, such as benzoic acid, sebacic acid, formic acid, acetic acid, monochloroacetic acid, dichloroacetic acid, trichloroacetic acid, trifluoroacetic acid, nitrous acid, and nitric acid. , Phosphoric acid, phosphorous acid, hydrochloric acid, hydrobromic acid, hydroiodic acid, sulfuric acid, perchloric acid, fluorosulfonic acid-pentafluoroantimony (1: 1) [Aldrich “Magic Acid” (trade name) )], Oxonium salts such as fluoroantimonic acid and methyl ether hydrochloride, ammonium salts such as 2,4,6-trinitroaniline hydrochloride, and sulfonium salts such as dimethyl sulfide.

The amount of the acid is preferably 0.001 to 10 parts by weight based on the amount of the monomer forming 100 parts by weight of the thermoplastic resin. If the amount is less than 0.001 part by weight, the effect of the acid is not sufficient. On the other hand, if the amount exceeds 10 parts by weight, a thermoplastic resin having a high degree of polymerization tends to be hardly obtained.

Examples of the thermoplastic resin in the present invention include polyamide, polyester, polycarbonate, polyarylate and the like, and among them, polyamide and polyester are particularly preferred.

These thermoplastic resins are produced using a conventionally known monomer, and the relative viscosity of the resin is as follows:
There is no particular limitation as long as the resin can exhibit its performance and can be molded.

The reinforced thermoplastic resin composition of the present invention contains a pigment, a heat stabilizer, an antioxidant, a weathering agent, a flame retardant, a plasticizer, a release agent, and a reinforcing agent as long as the properties are not significantly impaired. Etc. may be added.

As the heat stabilizer and the antioxidant, for example, hindered phenols, phosphorus compounds, hindered amines, sulfur compounds, copper compounds, alkali metal halides, and mixtures thereof can be used.

As the reinforcing agent, for example, clay, talc,
Calcium carbonate, zinc carbonate, wollastonite, silica,
Alumina, magnesium oxide, calcium silicate, sodium aluminate, sodium aluminosilicate, magnesium silicate, glass balloon, carbon black, zinc oxide, antimony trioxide, zeolite, hydrotalcite, metal fiber, metal whisker, ceramic whisker, potassium titanate Examples include whiskers, boron nitride, graphite, glass fibers, carbon fibers, and the like.

These additives are added at the time of polymerization or melt kneading or melt molding of the obtained resin composition.

Further, the reinforced thermoplastic resin composition of the present invention may be used as a mixture with another polymer. Examples of such a polymer include elastomers such as polybutadiene, butadiene / styrene copolymer, acrylic rubber, ethylene / propylene copolymer, ethylene / propylene / diene copolymer, natural rubber, chlorinated butyl rubber, and chlorinated polyethylene. And their acid-modified products such as maleic anhydride, styrene / maleic anhydride copolymer, styrene / phenylmaleimide copolymer, polyethylene, polypropylene, butadiene / acrylonitrile copolymer, polyvinyl chloride, polyacetal, polyvinylidene fluoride, Polysulfone, polyphenylene sulfide, polyether sulfone, phenoxy resin, polyphenylene ether, polymethyl methacrylate, polyether ketone,
Examples include polytetrafluoroethylene.

The reinforced thermoplastic resin composition of the present invention can be formed into a desired molded product by a usual molding method. For example, a hot melt molding method such as injection molding, extrusion molding, blow molding, or sinter molding, or a method of forming a molded article from an organic solvent solution by a casting method can be employed. The reinforced thermoplastic resin composition of the present invention has remarkably improved mechanical strength, heat resistance and dimensional stability as compared with the thermoplastic resin alone, and has little change in mechanical properties and dimensions due to water absorption. This resin composition, due to its excellent performance, mechanical parts and housings such as switches and connectors in the field of electrical and electronic equipment,
It is used as an underbonnet part, an exterior part, an outer plate part, an optical part such as a reflector in the automobile field, or a gear or a bearing retainer in the mechanical field.

[0036]

The role of the dispersant in making the reinforced thermoplastic resin composition of the present invention is not clear, but can be explained as follows. Generally, the layered silicate layer has a negative charge on the surface and a positive charge on the edge. Therefore, a three-dimensional gel structure is often formed in the dispersion medium. However, when a dispersant that generates anions is added in the dispersion medium, the dispersant neutralizes the positive charge at the end of the layered silicate layer or anionizes it to form a three-dimensional gel structure. Can be prevented. As a result, a suspension in which the layered silicate is uniformly dispersed can be obtained. Next, this suspension is mixed with a monomer that forms a thermoplastic resin, and when the monomer is polymerized simultaneously with the removal of the dispersion medium, the layered silicate is uniformly dispersed at the molecular level, and the layered silicate is aggregated. A reinforced thermoplastic resin composition having no structure at all is obtained.

[0037]

Next, the present invention will be described more specifically with reference to examples. In addition, the raw materials used in the examples and comparative examples and the measuring method of the performance test are as follows. 1. Raw materials (1) Swellable fluoromica mineral Mineral talc ground by a ball mill to have an average particle diameter of 4 μm was mixed with sodium silicate having the same average particle diameter of 4 μm so that the total amount would be 15% by weight. This was put in a magnetic crucible and reacted in an electric furnace at 850 ° C. for 1 hour to synthesize. The powder was subjected to wide-angle X-ray diffraction measurement. As a result, the thickness of the raw material talc in the c-axis direction was 9.2.
The peak corresponding to Å disappeared, and a peak corresponding to 12 to 16 示 す indicating the formation of a swellable fluoromica-based mineral was observed.

2. Measurement method (a) Relative viscosity: Measured under the conditions of a temperature of 25 ° C. and a concentration of 1 g / dl. In addition, as the measurement solvent, 96 was used for the reinforced nylon 6 resin composition.
% Concentrated sulfuric acid, phenol / ethane tetrachloride (1/1, weight ratio) was used for the reinforced polyethylene terephthalate resin composition. (b) Dispersibility of layered silicate Using a pellet of the reinforced thermoplastic resin composition, the dispersion was measured with a wide-angle X-ray diffractometer (Rigaku Corporation, RAD-rB type). (c) Tensile strength, tensile modulus and elongation at break Measured based on ASTM D-638. (d) Flexural strength and flexural modulus Measured based on ASTM D-790. (e) Izod impact strength Based on ASTM D-256, a 3.2 mm thick test piece was measured with a notch of a predetermined depth. (f) Heat deformation temperature Measured under a load of 18.6 kg / cm ² based on ASTM D-648. (g) Cohesiveness Transmission electron microscope (JEM-200CX, manufactured by JEOL Ltd.)
And used as an index of cohesion by observing an electron micrograph (TEM photograph) of the molded test piece. ：: No layered silicate having a particle diameter of 0.1 μm or more was observed at all, and there was no aggregated structure. ×: Layered silicate having a particle diameter of 0.1 μm or more was partially observed and had an aggregated structure.

Example 1 A mixture of 200 g of a swellable fluoromica-based mineral and 3 L of water was stirred with a homomixer at 7000 rpm for 2 hours.
20 g of sodium tripolyphosphate is added to this mixture,
The mixture was further stirred for 2 hours to obtain a suspension in which the swellable fluoromica-based mineral was uniformly dispersed in the aqueous dispersion medium. Next, this suspension and 10 kg of ε-caprolactam were placed in a 30 liter reactor and heated to 260 ° C. while stirring to obtain 15 kg / cm ²
Pressure. Then release the pressure to normal pressure, 260 ℃
For 2 hours. At the time of completion of the polymerization, the reaction product was discharged into a strand, cooled, solidified, and cut to obtain a pellet made of a reinforced nylon 6 resin composition.
The resulting pellets were treated with hot water at 95 ° C. to scour and dry. The pellets were supplied to an injection molding machine and injection-molded at a cylinder temperature of 260 ° C. and a mold temperature of 70 ° C. to form a test piece. Various performance tests were performed on the obtained test pieces.

Example 2 A reinforced nylon 6 resin was prepared in the same manner as in Example 1 except that the suspension used in Example 1, 10 kg of ε-caprolactam and 20 g of phosphoric acid were placed in a reaction vessel having a content of 30 liters. A pellet of the composition was obtained. Using the pellets, test pieces were formed in the same manner as in Example 1, and various performance tests were performed.

Examples 3 to 5 Pellets of a reinforced nylon 6 resin composition were obtained in the same manner as in Example 1 except that the amount was changed as shown in Table 1.
Using these pellets, test pieces were formed in the same manner as in Example 1, and various performance tests were performed.

Comparative Example 1 Example 1 was repeated except that sodium tripolyphosphate was not added.
In the same manner as in the above, pellets of the reinforced nylon 6 resin composition were obtained. Using the pellets, test pieces were formed in the same manner as in Example 1, and various performance tests were performed.

The pellets in Examples 1 to 5 and Comparative Example 1 were subjected to wide-angle X-ray diffraction measurement. As a result, the peak in the thickness direction of the layered silicate was completely disappeared in all cases, and the pellets in the nylon 6 resin matrix It was found that the layered silicate was uniformly dispersed at the molecular level.

The results in Examples 1 to 5 and Comparative Example 1 are summarized in Table 1.

[0045]

[Table 1]

Example 6 A reinforced polyethylene terephthalate (PE) was prepared using a polymerization apparatus comprising a stirrer, a fractionator, a feed port for raw materials, and a polycondensation tank having an outlet for product and an outlet for product.
T) A resin composition was obtained by the following method. That is, 100 g of a swellable fluoromica-based mineral and ethylene glycol (E
G) A mixture of 1.99 kg (32 mol) and 100 g of water was stirred with a homomixer at 7000 rpm for 2 hours. This mixture was mixed with 10 g of sodium tripolyphosphate and further stirred for 2 hours to obtain a suspension in which the swellable fluoromica-based mineral was uniformly dispersed in the EG / water dispersion medium. Next, this suspension and 3.32 kg (20 mol) of terephthalic acid were put into an esterification reaction tank and reacted at 255 ° C. for 2 hours to obtain an oligomer containing bishydroxyethyl terephthalate as a main component.
Next, this oligomer was transferred to a polycondensation tank, and 2 × 10 ⁻⁴ mol of antimony trioxide was added to 1 mol of the terephthalic acid component. Was subjected to polycondensation at a pressure of 0.7 hPa and a temperature of 275 ° C. for 4 hours. At the time of completion of the polycondensation, the reaction product was discharged in the form of a strand, cooled, solidified, and cut to obtain a pellet made of the reinforced PET resin composition. The pellets are supplied to an injection molding machine, where the cylinder temperature is 270 ° C and the mold temperature is 60 ° C.
A test piece was molded by injection molding. Various performance tests were performed on the obtained test pieces.

Examples 7 to 10 Pellets of a reinforced PET resin composition were obtained in the same manner as in Example 6, except that the amounts were changed as shown in Table 2. Using these pellets, test pieces were formed in the same manner as in Example 6, and various performance tests were performed.

Comparative Example 2 Example 1 was repeated except that sodium tripolyphosphate was not added.
In the same manner as in the above, pellets of the reinforced PET resin composition were obtained.
Using the pellets, test pieces were formed in the same manner as in Example 6, and various performance tests were performed.

Table 2 summarizes the results in Examples 6 to 10 and Comparative Example 2.

[0050]

[Table 2]

[0051]

According to the present invention, it is possible to obtain a reinforced thermoplastic resin composition in which the layered silicate is uniformly dispersed at the molecular level and in which there is no aggregated structure of the layered silicate.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Koji Fujimoto, 23 Uji Kozakura, Uji-city, Kyoto Prefecture Unitika Central Research Laboratories (72) Inventor Izumi Yoshida 23, Uji Kozakura, Uji-shi, Kyoto Unitika Central Research, Ltd. Inside

Claims (4)

[Claims] 1. A method in which a suspension in which a layered silicate is uniformly dispersed in a dispersion medium by a dispersant and a monomer forming a thermoplastic resin are used, and the monomer is polymerized simultaneously with the removal of the dispersion medium. A reinforced thermoplastic resin composition in which a layered silicate is uniformly dispersed at a molecular level. 2. The dispersant is at least one selected from the group consisting of tripolyphosphate, humate, ligninsulfonate, tannate, acrylate and polyacrylate. 2. The reinforced thermoplastic resin composition according to 1. 3. The reinforced thermoplastic resin composition according to claim 1, wherein 0.01 to 100 parts by weight of the layered silicate is blended with respect to the amount of the monomer forming 100 parts by weight of the thermoplastic resin. 4. A layered silicate of 0.01 to 100 parts by weight based on the amount of a monomer forming 100 parts by weight of a thermoplastic resin, and 25 ° C.
The reinforced thermoplastic resin composition according to any one of claims 1 to 3, further comprising 0.001 to 10 parts by weight of pKa in water of 0 to 5 or a negative acid.