JP2009155446A - Method for producing polyester resin composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain adequate functionalities such as mechanical properties while uniformly dispersing a swellable layered silicate in a polyester at a nano-level. <P>SOLUTION: A method for producing a polyester resin composition includes: melting and kneading a polyester copolymer containing 0.5-15 mol% of an aromatic dicarboxylic acid having a sulfonic acid group as an acid component or a mixture of the copolymer and a thermoplastic aromatic polyester, and the swellable layered silicate treated with an organic onium ion, in order to obtain a pelletized composition; and heat-treating it at a temperature not over the melting points of the polyester copolymer and the thermoplastic aromatic polyester. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method for producing a polyester resin composition in which a swellable layered silicate is uniformly dispersed in a polyester.

  Crystalline thermoplastic polyester resins (for example, polybutylene terephthalate resin) are excellent in mechanical properties, electrical properties, and other physical and chemical properties. Is used as a molding material in a wide range of applications. Further, when mechanical properties and heat resistance are insufficient with a polymer alone, it can be improved by using an inorganic filler as a reinforcing agent. However, in order to sufficiently satisfy the mechanical properties and heat resistance, it is necessary to add a large amount of reinforcing agent. In this case, the strength and heat resistance are improved, but the toughness and surface properties are greatly reduced and the specific gravity is increased. There is a problem. Possible causes of this are poor dispersion of the inorganic filler and the size of the dispersed particles. Therefore, studies have been conducted to improve the high toughness, strength, gas barrier property, thermal stability and flame retardance with a very small content by dispersing the inorganic filler at the nano level.

  In order to develop such a function, JP 2002-88236 A (Patent Document 1) discloses a swellable layered silicate treated with a polyester modified with an aromatic dicarboxylic acid having a sulfonic acid group and an organic onium ion. It has been proposed to use However, although the composition and manufacturing method proposed here can achieve nano-level dispersion, there is a problem that actual mechanical properties are not as great as expected.

  Japanese Patent Laid-Open No. 2000-86232 (Patent Document 2) discloses a melt-polymerized polyester having a high concentration modified with a swellable layered silicate first dispersed in water and an aromatic dicarboxylic acid having a sulfonic acid group. A method for solid phase polymerization is disclosed. However, this method has a problem that the viscosity increase in the polymerization in the presence of the modified layered silicate is remarkably inferior in productivity, and sufficient dispersion at the nano level cannot be obtained, and the expected mechanical properties cannot be obtained. .

Japanese Patent Laid-Open No. 2001-323143 (Patent Document 3) previously mixes a layered compound and a polyether compound, and then melts and kneads this with a thermoplastic polyester resin, and further increases the molecular weight of the polyester resin. A method is disclosed. However, this method has a problem that the layered silicate is not sufficiently dispersed at the nano level and sufficient physical properties cannot be obtained.
JP 2002-88236 A JP 2000-86232 A JP 2001-323143 A

  As described above, it has been difficult to uniformly disperse the swellable layered silicate in the polyester at a nano level by an industrially feasible method, and to obtain sufficient functionality such as mechanical properties. The object of the present invention is to propose a production method which solves these problems.

  As a result of intensive studies to solve the above problems, the inventors of the present invention provide a specific heat treatment step after melt-kneading an aromatic dicarboxylic acid having a sulfonic acid group and a specific swellable layered silicate. The inventors have found that the above object can be achieved by an industrially simple method and have completed the present invention.

  That is, the present invention is a polyester copolymer containing 0.5 to 15 mol% of an aromatic dicarboxylic acid having a sulfonic acid group as an acid component, or a mixture of the copolymer and a thermoplastic aromatic polyester, and an organic onium ion. A polyester resin composition characterized by being melt-kneaded with a swellable layered silicate to obtain a pellet-like composition and then heat-treating at a temperature below the melting point of the polyester copolymer and the thermoplastic aromatic polyester. It is a manufacturing method of a thing.

(Polyester copolymer)
The polyester copolymer used in the present invention is a polyester copolymer containing 0.5 to 15 mol% of an aromatic dicarboxylic acid having a sulfonic acid group as an acid component. Examples of the aromatic dicarboxylic acid having a sulfonic acid group as the acid component include 5-sodium sulfoisophthalic acid and 5-tetrabutylphosphonium sulfoisophthalic acid. When the aromatic dicarboxylic acid having such a sulfonic acid group is used in an amount of 0.5 to 15 mol%, preferably 1 to 6 mol% of the total acid component, the dispersibility of the swellable layered silicate in the polyester becomes good. .

  Other dicarboxylic acids include, for example, terephthalic acid, 2,6-naphthalenedicarboxylic acid, oxalic acid, succinic acid, adipic acid, glutaric acid, and lower alcohol esters thereof, particularly preferably terephthalic acid or terephthalic acid. Dimethyl. Examples of the diol include 1,4-butanediol, ethylene glycol, 1,3-propanediol, 1,6-hexanediol, cyclohexanedimethanol and the like, and 1,4-butanediol is particularly preferable.

  The above polyester copolymer has an intrinsic viscosity of 0.3 to 0.3 when dissolved in a phenol / 1,1 ′, 2,2′-tetrachloroethane = 60/40 (weight ratio) solvent and measured at 35 ° C. It is preferable to use 1.0.

  In the present invention, the above polyester copolymer and thermoplastic aromatic polyester can be used in combination. Examples of the thermoplastic aromatic polyester include polyethylene terephthalate, polybutylene terephthalate, polycyclohexylene dimethylene terephthalate, polyethylene naphthalate, and polybutylene. Naphthalate, polyethylene isophthalate-terephthalate copolymer, polybutylene isophthalate-terephthalate copolymer, polycyclohexylenedimethylene isophthalate-terephthalate copolymer, and the like can be mentioned, and polybutylene terephthalate is particularly preferable.

  The thermoplastic aromatic polyester has an intrinsic viscosity of 0.5 when dissolved in a phenol / 1,1 ′, 2,2′-tetrachloroethane = 60/40 (weight ratio) solvent and measured at 35 ° C. It is preferable to use one having a particle size of ~ 1.4.

In the present invention, the content of the polyester copolymer in the mixture of the polyester copolymer and the thermoplastic aromatic polyester is 10 to 100% by weight, more preferably 30 to 100% by weight.
(Swellable layered silicate)
The swellable lamellar silicate used in the present invention is a lamellar silicate having a cation exchange ability and a property of taking water between layers to swell. For example, the smectite clay mineral may include hectorite, saponite, stevensite, beidellite, montmorillonite, or natural or chemically synthesized products thereof, or substituted, derivatives, or mixtures thereof. Examples of the swellable mica include a synthetic swellable mica having a Li, Na ion between chemically synthesized layers, or a substituted, derivative or mixture thereof.

  The above-mentioned “swellability” refers to the property of swelling when a solvent such as water, alcohol or ether enters between the crystal layers of the layered silicate.

  In the present invention, it is necessary to contain the swellable layered silicate in an organic state with an organic agent. By replacing the interlayer inorganic ions of the layered silicate, which is an inorganic component, with organic ions, the compatibility with the polyester copolymer obtained by copolymerizing the monomer having a sulfonic acid group of the resin component constituting the matrix is improved. A nano-order dispersion state can be obtained by melt-kneading.

  In the present invention, the swellable layered silicate treated with organic onium ions is used. The organic onium ion used is represented by the following formula (1)

A quaternary ammonium ion having a structure in which R ₁ , R ₂ , R ₃ and R ₄ are each independently an alkyl group having 1 to 30 carbon atoms or a polyethylene oxide group is preferable. Here, as a C1-C30 alkyl group, a C1-C18 alkyl group is preferable.

  The organic onium ion represented by the above formula (1) is preferably a quaternary ammonium ion. Specific examples include trimethylstearyl ammonium, dimethyloctadecyl ammonium, oleylbis (2-hydroxyethyl) methyl ammonium.

  The treatment method of the swellable layered silicate with an organic onium ion is usually performed by mixing 1 part by weight of the swellable layered silicate and 0.3 to 10 parts by weight of the organic onium ion in water and then drying. The amount of water is 3 to 100 times that of the swellable layered silicate. The mixing temperature is 10 to 80 ° C., and the mixing time is preferably 0.5 to 2 hours. As drying conditions, drying at normal pressure at 70 to 120 ° C. for 1 to 3 days, or vacuum drying for about 3 hours to 1 day is preferable.

The content of the swellable layered silicate in the polyester resin composition of the present invention is preferably 0.5 to 10% by weight, and particularly 1 to 5% by weight provides high dispersibility and physical properties.
(Melt kneading)
Melt kneading of the polyester copolymer or a mixture of the copolymer and a thermoplastic aromatic polyester and a swellable layered silicate treated with an organic onium ion is a normal uniaxial or biaxial melt kneading extrusion. In a melt kneader such as a machine. A twin screw extruder is preferably used. The melt kneading temperature can be carried out at a temperature higher than the lower melting point (melting point−10 ° C.) of the polyester copolymer and the thermoplastic aromatic polyester and lower than the higher melting point (melting point + 100 ° C.).
(Heat treatment)
As described above, the present invention is characterized in that the resin composition melt-kneaded and pelletized is subjected to heat treatment. That is, the melt-kneaded resin composition is pelletized by a normal method, and is supplied to a reactor in the form of pellets, and is heat-treated at an appropriate temperature under an inert gas atmosphere or under reduced pressure (or under vacuum). Applied.

  The heat treatment temperature may be any temperature as long as the resin composition does not become difficult to handle industrially due to softening, that is, a temperature below the melting point of the polyester copolymer and the thermoplastic aromatic polyester. From the viewpoint of productivity, it is preferable to set the temperature as high as possible within a range where no occurrence occurs. Specifically, the lower melting point (melting point−10 ° C.) or lower (melting point−100 ° C.) of the polyester copolymer and the thermoplastic aromatic polyester is preferable.

  The heat treatment time is 1 to 100 hours, more preferably 5 to 50 hours. In less than 1 hour, the reaction does not proceed sufficiently. In addition, it is sufficient that the reaction is performed for 100 hours. In many cases, the reaction does not substantially proceed even if the treatment is continued for a longer time.

  Note that the crystallinity increases by heat treatment. For this reason, an increase in the latent heat of crystal melting is observed as compared with those not subjected to heat treatment in DSC measurement.

  The nano-dispersion at the molecular level in the present invention means that the diffraction peak derived from the bottom reflection of the (001) plane of the swellable layered silicate measured by X-ray analysis disappears. That is, the state is that the swellable layered silicate is peeled off one by one or very close to that state.

  Various known additives such as stabilizers (antioxidants, ultraviolet absorbers, heat stabilizers, etc.), flame retardants, lubricants, mold release agents, antistatic agents, dyes and pigments are included in the resin composition of the present invention. Of course, a coloring agent such as a coloring agent, a dispersing agent, a plasticizer, and the like can be blended. If necessary, it may be used in combination with other resins (thermoplastic resin, thermosetting resin, etc.).

  Furthermore, you may add an inorganic filler in the range which does not impair the objective of this invention. Examples of the inorganic filler include a plate-like material, a fiber-like material, and a granular material. Specifically, plate-like boehmite, plate-like inorganic fillers such as glass flakes, glass fibers, carbon fibers, ceramic fibers, boron fibers, potassium titanate fibers and other general inorganic fibers, calcium carbonate, alumina, talc, clay, Examples thereof include powdered inorganic fillers such as glass powder, quartz powder, silica sand, wollastonite, barium sulfate, calcined gypsum, silicon carbide, boron nitride, boron nitride and the like, and these inorganic fillers are used alone or in combination of two or more. be able to.

  The polyester resin composition obtained by the present invention can be easily molded by a conventional molding method such as injection molding, extrusion molding, compression molding, blow molding, vacuum molding, rotational molding, gas injection molding, etc. It can be. Examples of the molded article include automotive engine peripheral parts, automotive electrical parts, automotive structural parts, electrical and electronic parts, various industrial materials, food packaging materials, films, pipes, and other materials.

  Hereinafter, the present invention will be described in more detail by way of examples, but the present invention is not limited thereto.

  In this example, as the swellable layered silicate, montmorillonite organized with dimethylbenzylammonium (Esben NZ manufactured by Hojun Co., Ltd., layered silicate-A), and montmorillonite that is not organized for comparison ((stock) ) Hojun Wengel Esbene A, layered silicate-B) was used.

5-sodium sulfodimethylisophthalate is manufactured by Takemoto Yushi Co., Ltd., phenol, 1,1 ', 2,2'-tetrachloroethane, dimethyl terephthalate, 1,4-butanediol, and tetrabutyl titanate are manufactured by Kanto Chemical Co., Inc. As the PBT (polybutylene terephthalate), 500FP (polyester-A) manufactured by Polyplastics Co., Ltd. was used. Polyester-A had an intrinsic viscosity of 0.88 and a melting point of 223.3 ° C.
(Synthesis of polyester copolymer composed of aromatic dicarboxylic acid having sulfonic acid group)
85 parts by weight of dimethyl terephthalate, 3.3 parts by weight of 5-sodiumsulfodimethylisophthalate, 60 parts by weight of 1,4-butanediol and 0.1 parts by weight of tetrabutyl titanate are placed in a stainless steel reaction vessel equipped with a distillation tube, stirrer and heating device. The mixture was transesterified at 150 to 210 ° C. for 2 hours. The system was further depressurized while being heated from 210 ° C. to 250 ° C. over 30 minutes, and then polymerized at 250 ° C. for 1 hour to obtain a polyester copolymer (1). The obtained polymer had an intrinsic viscosity of 0.46 and a melting point of 220.2 ° C. The amount of 5-sodium sulfodimethylisophthalate introduced was 2.4 mol%.

A polyester copolymer was prepared in the same manner as described above using 82.8 parts by weight of dimethyl terephthalate, 6.6 parts by weight of 5-sodiumsulfodimethylisophthalate, 60 parts by weight of 1,4-butanediol and 0.1 parts by weight of tetrabutyl titanate. -(2) was obtained. The obtained polymer had an intrinsic viscosity of 0.41 and a melting point of 217.5 ° C. The amount of 5-sodium sulfodimethylisophthalate introduced was 4.9 mol%.
(Measurement of introduction amount of 5-sodium sulfodimethylisophthalate)
The amount of 5-sodium sulfodimethylisophthalate introduced into the polyester copolymers (1) and (2) was determined by 1H-NMR using trifluoroacetic acid-d as a solvent.
(Intrinsic viscosity measurement)
The intrinsic viscosity of the polyester material was measured at 35 ° C. by dissolving in a phenol / 1,1 ′, 2,2′-tetrachloroethane = 60/40 (weight ratio) solvent.
(Measurement of melting point and latent heat of fusion)
The polyester composite material was heated from room temperature to 270 ° C. at 10 ° C./min using DSC Q-1000 manufactured by TA instruments, and the melting point (peak value) and its latent heat of fusion were measured.
(Melt kneading)
Using a twin-screw extruder TEX-30α manufactured by Nippon Steel Works, it was extruded as a strand at a cylinder temperature of 260 ° C., a rotational speed of 130 rm, and a total composition feed rate of 10 kg / hr, solidified in a water tank, and pelletized. The pellet shape was approximately 2 mm × 3 mm × 4 mm.
(Heat treatment)
The pellets were charged into a stainless steel sealed reaction vessel equipped with a heating device equipped with a nitrogen supply port and an exhaust port and capable of generating a nitrogen stream, and the supply nitrogen temperature and reaction vessel temperature were set to 190 ° C., and the treatment was performed for 20 hours.
(Evaluation of the physical properties)
The obtained resin composition pellets were dried at 140 ° C. for 3 hours and then measured for tensile strength in a dumbbell molded product that was injection-molded at a cylinder temperature of 260 ° C. and a mold temperature of 80 ° C. according to ISO527.
(Evaluation of peeled and dispersed state of swellable layered silicate)
The exfoliation dispersion state of the swellable layered silicate is caused by the disappearance of the diffraction peak derived from the bottom reflection of the (001) plane of the layered silicate of the polyester composite using an X-ray analyzer (Rigaku Electric Co., Ltd. RINT2500HL). The peel dispersion of the swellable layered silicate was evaluated.
Example 1
Pellets were obtained as described above from polyester copolymer- (1); 97 parts by weight and layered silicate-A; 3 parts by weight, and heat-treated under the above conditions for evaluation.
Example 2
Pellets were obtained and evaluated in the same manner as in Example 1 except that the polyester copolymer- (1) was 95 parts by weight and the layered silicate-A was 5 parts by weight.
Example 3
Pellets were obtained and evaluated in the same manner as in Example 1 except that 47 parts by weight of polyester copolymer- (1) and 50 parts by weight of polyester-A were added.
Example 4
A pellet was obtained and evaluated in the same manner as in Example 3 except that 27 parts by weight of polyester copolymer (2) was used instead of polyester copolymer (1) and 70 parts by weight of polyester A was used. It was.
Comparative Example 1
A pellet was obtained and evaluated in the same manner as in Example 1 except that the heat treatment of the pellet was not performed.
Comparative Example 2
Pellets were obtained and evaluated in the same manner as in Example 1 except that layered silicate-B was used instead of layered silicate-A.
Comparative Example 3
Pellets were obtained and evaluated in the same manner as in Example 1 except that polyester-A was used instead of polyester copolymer- (1).
Comparative Example 4
Pellets were obtained and evaluated in the same manner as in Example 1 except that the polyester copolymer- (1) was 100 parts by weight and the layered silicate-A was not added.

  These results are shown in Table 1.

Claims (7)

Swellable layered silicic acid treated with a polyester copolymer containing 0.5 to 15 mol% of an aromatic dicarboxylic acid having a sulfonic acid group as an acid component or a mixture of the copolymer and a thermoplastic aromatic polyester, and an organic onium ion A method for producing a polyester resin composition, comprising melt-kneading a salt to obtain a pellet-like composition, and then heat-treating at a temperature not higher than the melting point of the polyester copolymer and the thermoplastic aromatic polyester. The method for producing a polyester resin composition according to claim 1, wherein the swellable layered silicate is dispersed in the polyester in a peeled state. The method for producing a polyester resin composition according to claim 1, wherein the heat treatment is performed under an inert gas atmosphere or under reduced pressure. The method for producing a polyester resin composition according to claim 1, wherein the organic onium ion is a quaternary ammonium ion. The method for producing a polyester resin composition according to claim 1, wherein the swellable layered silicate is montmorillonite or swellable mica. The method for producing a polyester resin composition according to claim 1, wherein the content of the swellable layered silicate in the polyester resin composition is 0.5 to 10% by weight. The polyester resin composition obtained by the manufacturing method of any one of Claims 1-6.