JPH11216724A - Thermoplastic resin composition and manufacture thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize the easy addition of fine silica particles to a thermoplastic resin and favorable dispersion properties by a method wherein the fine silica particles, the SiOH groups on the outer surface of each of which are treated with a silicon- containing organic matter so as to bring the number of SiOH groups per unit area on the surface of the particle below the specified value, are dispersingly included in the thermoplastic resin. SOLUTION: Fine silica particles treated with a silicon-containing organic compound can obtain a large effect, when amorphous fine silica particles, which are manufactured by a wet method so that a large number of SiOH groups are present on the surface of each particle and the specific surface area of each particle is comparatively large, are employed. As far as the kneading with the thermoplastic resin is concerned, the few the number of the SiOH groups on the surface of the fine silica particle is, the better the dispersion properties of the fine silica particles become. The fine silica particle, the number A of SiOH groups on the surface of which is set to be 2 μmol/m<2> or less by the surface treatment with a silicon-containing organic matter, is preferable. The fine silica particle, A of which is set to be 1.5 μmol/m<2> or less, is especially preferable. In this case, A is the number of SiOH groups on the surface of the particle in μmol/g per the specific surface area of the particle in g/m<2> .

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermoplastic resin composition and a method for producing the same, and more particularly, to a thermoplastic resin which can easily add fine silica particles to a thermoplastic resin, and which has good dispersibility of the added particles. The present invention relates to a resin composition and a method for producing the same.

[0002]

2. Description of the Related Art Thermoplastic resins, particularly polyesters, are used in large quantities as fibers, films, resins and the like because of their excellent physical and chemical properties. On the other hand, it is known that troubles such as poor workability, poor productivity, and low product value occur due to poor slipperiness when handling the molding process for obtaining such a formed product or the product itself.

[0003] In order to solve such a problem, there has been proposed a method in which fine particles are present in a thermoplastic resin to impart appropriate irregularities to the surface of a molded article to improve the slipperiness. , Titanium dioxide, calcium carbonate,
Inorganic fine particles such as talc and kaolinite are employed. Among them, silica is one of the preferable inorganic fine particles in terms of price, particle size, handling and the like.

[0004] When inorganic fine particles such as silica are added, mixing of coarse particles is a problem. The presence of the coarse particles impairs important film quality, for example, in the case of a film for a magnetic tape, deteriorating electromagnetic characteristics or causing dropout.

[0005] As a method for removing the coarse particles, when inorganic fine particles are added during a usual thermoplastic resin synthesis reaction, the particles are added in a slurry state or a suspension state through pulverization and classification operations. . However, in this method, the slurrying, pulverizing, and classifying operations require a great deal of cost and work time, and even if this operation is performed, re-collection occurs after being added during the thermoplastic resin synthesis reaction, and coarse particles are formed. There arises a problem that mixing of undulation cannot be avoided. Also, when producing a variety of value-added polymers from one type of master polymer, if the inorganic fine particles are added during the polymerization reaction, a large amount of loss is caused by switching the brand.

Therefore, a method of kneading powdery particles into polyester using a single-screw extruder or a twin-screw kneader (Japanese Unexamined Patent Publication No.
And a method of adding and kneading particles in a slurry state or a suspension state (JP-A-6-91).
No. 635) has been proposed.

[0007] However, according to the study of the present inventors,
When these methods are applied to highly cohesive silica fine particles having a large specific surface area and a large number of silanol groups on the particle surface, when the shear stress is insufficient, aggregation in the resin or insufficient crushing of the coarse particles causes the resin in the resin to be insufficiently crushed. If the dispersibility of the particles becomes worse, and if the shearing stress is too high, on the contrary, the particles will be too crushed and the particle size will be reduced, impairing the original purpose of slipperiness and the like. It became.

A method for producing a polyester film containing fine silica particles whose surface silanol groups have been surface-treated with a silane coupling agent has also been proposed (JP-A-4-298538). Silanol groups of 30 to 70% of the total amount of silanol groups contained in the particles,
This is to perform surface modification while blocking with a silane coupling agent. At that time, all silanol groups contained in the particles are to be blocked.

However, when silica particles treated under these conditions are used, the particles are made into a slurry state or a suspension state, and the mixture is added and kneaded using a twin-screw kneading extruder to produce a thermoplastic resin composition. The dispersibility of the silica fine particles in the film using the produced resin was not satisfactory.

[0010]

SUMMARY OF THE INVENTION The present inventor has found that the improvement of the dispersibility of the particles does not involve much the silanol groups in the pores within the particles, and the outer surface portion of the particles where the interaction between the particles is easy. In order to solve the conventional problems based on the above, it is considered that only the silanol group treatment is involved, and the above problem may be due to the excessive amount of the silane coupling agent enhancing the interaction between the particles. After careful examination,
The present invention has been reached.

Accordingly, it is an object of the present invention to provide a thermoplastic resin composition in which silica fine particles can be easily added to a thermoplastic resin and the added particles have good dispersibility, and a method for producing the same. .

[0012]

SUMMARY OF THE INVENTION The object of the present invention is to provide: Treating the SiOH groups on the outer surface of the particles with a silicon-containing organic material,
Thermoplastic resin composition containing dispersed silica fine particles having a number A of 2 μmol / m ² or less, where A = (the number of SiOH groups on the particle surface [μmol /
g]) / (specific surface area of particles [g / m ² ]).

And 2. In a method for producing a thermoplastic resin composition by kneading a thermoplastic resin and silica fine particles in a vented twin-screw kneading extruder, the surface-treated silica fine particles are used as the silica fine particles, and the water- and / or boiling point is adjusted to This is achieved by a method for producing a thermoplastic resin composition, characterized in that the resin is dispersed in an organic compound having a melting point lower than that of the thermoplastic resin and supplied to a vented twin-screw kneading extruder.

As the thermoplastic resin in the present invention, polyethylene, polypropylene, polyamide, polyester and the like are preferably used. Among them, polyester is preferred.

The polyester is particularly preferably an aromatic polyester having an aromatic dicarboxylic acid as a main acid component and an aliphatic glycol as a main glycol component.

The aromatic dicarboxylic acids include terephthalic acid, 2,6-naphthalenedicarboxylic acid, 4,4'-
Examples thereof include diphenyldicarboxylic acid and the like, and among them, terephthalic acid and 2,6-naphthalenedicarboxylic acid are preferable. Examples of the aliphatic glycol include ethylene glycol, propylene glycol, 1,4-butanediol, and 1,4-cyclohexanedimethanol. Among them, ethylene glycol is preferable.

The polyester in the present invention is preferably a homopolymer composed of the above-mentioned aromatic dicarboxylic acid component and aliphatic glycol component, but is a copolymer obtained by copolymerizing a small amount of a copolymer component as long as its characteristics are not impaired. You can also.

As the third component, for example, when the main component is ethylene terephthalate, as the aliphatic diol component, diethylene glycol, propylene glycol, neopentyl glycol, polyalkylene glycol, 1,4-cyclohexanedimethanol, etc. Diols and carboxylic acid components include succinic acid, adipic acid, sepasic acid, phthalic acid, isophthalic acid, 2,6
And dicarboxylic acids such as naphthalenedicarboxylic acid, and polyfunctional polycarboxylic acids such as trimellitic acid and pyromellitic acid. In addition, the main component is ethylene
In the case of 2,6-naphthalate, the same components as described above (however, terephthalic acid is used instead of 2,6-naphthalenedicarboxylic acid) can be exemplified.

The thermoplastic resin in the present invention is not particularly limited as long as it can be efficiently produced by a conventionally known method or a method accumulated in the art. At that time, a catalyst and a stabilizer can be used as needed, and other additives can be added. In particular, the polyester contains a metal catalyst used in the production thereof, for example, compounds such as lithium, sodium, calcium, magnesium, manganese, zinc, antimony, germanium, and titanium, and a phosphorus compound as a stabilizer. Is preferred.

In the present invention, the silica fine particles treated with the silicon-containing organic compound are not particularly limited in terms of particle size, production method, shape, etc., but are wet-type, having a large surface area and a relatively large specific surface area. When amorphous silica fine particles manufactured by the method are used, a great effect can be obtained.

In the present invention, the surface of the silica fine particles needs to be treated with a silicon-containing organic substance. In addition, there is no particular limitation on the particle size, production method, shape, and the like as long as the surface of the silica fine particles is treated.

In the present invention, the finer silica particles used for kneading with a thermoplastic resin are better as the number of SiOH groups on the surface is smaller, and the number A of SiOH groups on the particle surface is preferably ² μmol / m ² or less by the surface treatment of the silicon-containing organic substance. Silica fine particles are preferred. Particularly preferably, A is 1.5 μmo
1 / m ² or less silica fine particles. Where A =
(Number of SiOH groups on particle surface [μmol / g]) / (specific surface area of particle [g / m ² ]).

The number of SiOH groups on the particle surface [μmo
l / g] is a value titrated with a bulky amine, for example, triethylamine.

Since a bulky amine is difficult to react with SiOH in pores in particles due to its bulkiness, it is possible to evaluate SiOH capable of interaction between particles.

As the silicon-containing organic substance that can be used in the present invention, any silicon-containing organic substance having a functional group capable of binding to a silanol group on the silica surface in a state of binding to the silicon element in the compound can be used. it can. Compounds known as silica surface treating agents, for example, halogenosilanes, alkyldisilazanes, alkoxylanes, silane coupling agents and the like can be used.
More specifically, examples of the halogenosilanes include monomethylchlorosilane, dimethyldichlorosilane, and trimethylchlorosilane. Examples of the alkyldisilazane include hexamethyldisilazane. Examples of the alkoxysilanes include trimethylmethoxysilane and dimethyldimethoxysilane. Furthermore, as a silane coupling agent,
γ-glycidoxypropyltrimethoxysilane, γ-mercaptopropyltrimethoxysilane, γ-ureidopropyltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane, polyoxyethylenepropyltrimethoxysilane and the like.

Among these, in consideration of the dispersibility of the surface-treated silica fine particles in the dispersion liquid, the dispersibility in the thermoplastic resin, and the interaction at the interface, the alkoxysilanes and the silane coupling agent are used. Particularly preferred. For example,
Trimethylmethoxysilane and γ-glycidoxypropyltrimethoxysilane.

In the present invention, the addition amount of the silica fine particles to the thermoplastic resin is preferably 0.01 to 10% by weight (based on the thermoplastic resin), and more preferably 0.01 to 5% by weight. If this amount exceeds 10% by weight, sufficient dispersibility cannot be obtained. On the other hand, when the content is less than 0.01% by weight, the effect of adding particles is not sufficiently exhibited. On the other hand, if the shear stress is increased too much to promote this dispersion, the particles will be crushed and the particle size will be reduced.

The dispersion medium used in the present invention includes:
Disperse the silica fine particles surface-treated with the organic material,
There is no particular limitation as long as the slurry can be integrated. For example, almost all known media such as water and liquid having a boiling point of 200 ° C. or less can be used. Among them, water, methanono, ethanol, ethylene glycol and the like are preferable in terms of economy and handling. In particular, water is the most preferred medium in terms of safety.

In the present invention, the method of supplying the dispersion containing the surface-treated silica fine particles to the vented twin-screw kneading extruder is efficient, safe, quantitative, and does not affect the dispersibility. There is no particular limitation.

For example, in a vented twin-screw extruder, immediately after the thermoplastic resin is supplied to the extruder, a dispersant containing surface-treated silica particles is extruded under atmospheric pressure using a Milton pump or the like. Supply to the machine.

In the present invention, the vented twin-screw kneading extruder and the kneading conditions are not particularly limited as long as the kneading and extruding can be carried out efficiently and safely. It is preferable to determine the number of kneading elements such as kneading discs in a vented twin-screw kneading extruder, the number of revolutions, the temperature, etc., based on the balance between the film quality and the film quality.

In the present invention, the method of supplying the dispersion containing the surface-treated silica particles to the vented twin-screw kneading extruder is efficient, safe, quantitative, and affects the dispersibility. There is no particular limitation unless. Also, regarding the vent type twin screw kneading extruder and kneading conditions,
Efficiently, there is no particular limitation as long as the kneading extrusion can be performed safely, but in order to efficiently remove water and / or an organic compound having a boiling point lower than the melting point of the thermoplastic resin, at least one of the vent holes is provided. It is preferred to keep under reduced pressure. At this time, the degree of pressure reduction of the vent hole is 100 Torr.
r or less, preferably 50 Torr or less, more preferably 30 Torr or less. Also,
With respect to the vented twin-screw extruder and the kneading conditions, it is necessary to control the shear stress within a desired range, but this is preferably controlled by the melt viscosity of the thermoplastic resin in the shear rate range during kneading. At this time, the thermoplastic resin preferably has a melt viscosity of 100 to 10000 Poise, and more preferably 500 to 5000 Poise. If the melt viscosity is too low, the dispersibility of the added silica particles will be insufficient, while if it is too high, the added silica particles will be crushed and the particle size will be reduced.

According to the present invention, silica particles can be contained uniformly and at a high concentration in a thermoplastic resin. Therefore, a thermoplastic resin composition containing silica particles dispersed at a high concentration can be produced, and the composition can be used after being diluted with a thermoplastic resin containing substantially no particles. Furthermore, the silica particles in the obtained thermoplastic resin composition are uniformly dispersed without agglomeration, and therefore, when the composition is formed into a stretched film, a uniform uneven surface without coarse projections is obtained. As a result, a film having excellent lubricity and abrasion resistance can be obtained.

Further, the thermoplastic resin of the present invention may contain lubricant particles other than silica, and may be added at the time of polymerization, or the silica particles are kneaded into the resin by a vented twin-screw kneading extruder. It may be added at the same time.

[0035]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, which should not be construed as limiting the scope of the invention. In addition, the measuring methods and definitions of various physical properties and characteristics in the examples are as follows.

(1) Number of SiOH Groups on Particle Surface The silica particles are vacuum-dried at 120 ° C. for 6 hours, and then titrated with triethylamine in a toluene solvent.

(2) Average particle size of particles The particle size of the particles is measured by the following method. 1) In the case of obtaining from a dispersion, a low concentration solution is prepared by adding ethylene glycol or water to a dispersion in which silica fine particles are dispersed in a medium, and then the average particle diameter is measured using a laser analyzer SALD-2000 manufactured by Shimadzu Corporation. Is measured.

2) From particles in the film: A small piece of the sample film was fixed on a sample stage for a scanning electron microscope, and the film surface was measured using a battering device (1B-2 type ion coater device) manufactured by Eiko Engineering Co., Ltd. Is subjected to an ion etching process under the following conditions.

The conditions were as follows: the sample was placed in a cylinder jar, and the air vacancy was increased to a vacuum of about 5 × 10 ^-2 To rr.
Perform ion etching at a voltage of 0.90 kV and a current of 5 mA for about 5 minutes. Further, the film surface is subjected to gold sputtering with the same apparatus, and the scanning electron microscope is used to perform 2000 to 300 minutes.
Observe at × 00 and find the average particle size equivalent to the area circle as in 1).

(3) Dispersibility Using a biaxially oriented film, under an optical microscope, 100 cm
Coarse particles (agglomerated particles) having a diameter of 10 μm or more per ² were measured and evaluated according to the following criteria. However, the concentration of the silica particles in the film is set to be 0.06% by weight based on the polyester. [Judgment Criteria] ○: less than 100 △: 100-1000 ×: more than 1000

(4) Coefficient of friction of the film The coefficient of static friction and the coefficient of dynamic friction of the film are measured using a friction coefficient measuring device manufactured by Toyo Tester Industries.

(5) Film haze POIC haze meter SE manufactured by Nihon Seimitsu Kogyo KK
The surface haze of the film is measured using a T-HS-D1 type.

Example 1 Wet synthetic amorphous silica fine particles having a specific surface area of 300 m ² / g were dispersed in water, and stirred.
Γ-glycidoxypropyltrimethoxysilane corresponding to 4% of the particle weight was added dropwise. Thereafter, the mixture was heated to 65 ° C., stirred at that temperature for 1 hour, and allowed to cool. The obtained reaction solution was subjected to distillation under reduced pressure, followed by vacuum drying for 2 hours to obtain a treated silica powder.

When the number of SiOH groups in this powder was measured, it was 400 μmol / g.
The radix A was 1.3 μmol / m ² . Water was added to the obtained powder to prepare a 10% silica particle-containing aqueous dispersion.

A pent-type, co-rotating, meshing twin-screw kneading method using an undried polyethylene terephthalate chip containing 0.4% by weight of water and a kneading disk paddle as a screw component at a rate of 12 kg / h from a vibratory metering feeder. The mixture was fed to an extruder, and at the same time, the above-mentioned aqueous dispersion was added using a Milton metering pump so that the particle concentration in the composition was 0.4% by weight. Further, after the addition of the dispersion, an undried polyethylene terephthalate chip containing 0.4% by weight of water was supplied at a rate of 8 kg / h from a vibration type quantitative feeder. At this time, the degree of vacuum at the vent port was set to 1
It was set to mmHg, melt-kneaded at a cylinder temperature of 285 ° C., and extruded into pellets.

Using the obtained polyester composition pellet containing silica fine particles and the polyester pellet containing no particles, the particle concentration in the film was 0.06% by weight,
An unstretched film having a thickness of about 240 μm is manufactured by a conventional method, and then 3.1 times in a machine direction by a normal sequential biaxial stretching method.
The film was stretched 3.1 times in the transverse direction to produce a biaxially oriented polyester film.

The results are shown in Table 1. The dispersibility of the silica particles in the obtained polyester film was good, and a highly transparent film could be obtained.

Examples 2 to 4 The same procedures as in Example 1 were carried out except that the surface treating agents and their concentrations were changed as shown in Table 1. The results are shown together in Table 1.

[Comparative Example 1] The same procedure as in Example 1 was performed using wet synthetic amorphous silica particles having a specific surface area of 300 m ² without surface treatment. The obtained film did not satisfy the target quality.

Comparative Example 2 The procedure of Example 1 was repeated, except that the number of silanol groups after the surface treatment was changed as shown in Table 1. About the polyester film thus obtained,
Table 1 shows the dispersibility of the particles, the coefficient of friction of the film, and the characteristics of the surface haze of the film. As is clear from the results in Table 1, the effect of the present invention was excellent.

[0051]

[Table 1]

[0052]

According to the present invention, silica fine particles can be easily added to a thermoplastic resin, and a thermoplastic resin composition having good dispersibility of particles in the obtained composition can be produced. it can.

Claims (6)

[Claims] 1. A thermoplastic resin comprising a silica fine particle in which the SiOH groups on the outer surface of the particles are treated with a silicon-containing organic substance and the number A of SiOH groups per unit area on the particle surface is ² μmol / m ² or less. Resin composition. Where A = (the number of SiOH groups on the particle surface [μmol / g])
/ (Specific surface area of particles [g / m ² ]). 2. A method for producing a thermoplastic resin composition by kneading a thermoplastic resin and silica fine particles in a vented twin-screw kneading extruder, wherein the silica fine particles contain silicon-containing SiOH groups on the outer surface of the particles. Treated with an organic substance, the number of SiOH groups A per unit area on the particle surface was set to 2 μmo.
1 / m ² or less silica fine particles, which are dispersed in water and / or an organic compound having a boiling point lower than the melting point of the thermoplastic resin and supplied to a vented twin-screw extruder. A method for producing a thermoplastic resin composition. 3. The method for producing a thermoplastic resin composition according to claim 2, wherein the silicon-containing organic substance when treating the SiOH group on the outer surface of the silica fine particles with the silicon-containing organic substance is an alkoxysilane compound. 4. The method for producing a thermoplastic resin composition according to claim 2, wherein the silicon-containing organic substance when treating the SiOH groups on the outer surface of the silica fine particles with the silicon-containing organic substance is a silane coupling agent. 5. The thermoplastic resin composition according to claim 1, wherein the thermoplastic resin is a polyester. 6. The method for producing a thermoplastic resin composition according to claim 2, wherein the thermoplastic resin is a polyester.