JPH0819240B2 - Method for producing improved polybutylene terephthalate resin composition - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an improved thermoplastic polyester resin which provides a molded article having excellent impact properties and having little deterioration in physical properties such as flexural modulus, and a method for producing the same. It is a thing.

[Conventional technology and its problems]

Thermoplastic polyester resin has excellent moldability, mechanical strength,
Due to its excellent electrical and other physical and chemical properties, it is used as a engineering plastic in a wide range of applications such as automobiles, electric and electronic parts.

However, although the thermoplastic polyester resin has the above-mentioned characteristics, it has a problem in impact resistance depending on its application, and it is often not enough as it is for applications requiring high impact. Therefore, various methods for improving the impact resistance of the thermoplastic polyester resin have been proposed. As a typical method, polycarbonate,
A method of adding an impact modifier such as an olefin-based polymer or a rubber-like polymer to polyester has been proposed.

According to such a method, it is possible to obtain a molded article having an improved impact resistance to some extent, but the effect is still insufficient, and it is extremely difficult to obtain a molded article having a remarkably high impact resistance. It was Further, when a large amount of the above-mentioned polymer is used for the purpose of obtaining a high degree of impact resistance, there are various problems such as the excellent mechanical properties of polyester, particularly the decrease in elastic modulus and rigidity, and the decrease in chemical resistance. Often occurs undesirably and is not preferable.

[Means for solving the problem]

The present inventors have conducted extensive studies for the purpose of improving impact resistance without sacrificing the excellent mechanical properties of the thermoplastic polyester resin as much as possible, particularly without lowering rigidity and elastic modulus. As a result, the thermoplastic polyester is melt-kneaded with a specific modified olefin-based copolymer,
The inventors have found that an improved thermoplastic polyester satisfying the above object can be obtained by further maintaining the mixture at a specific temperature and reacting it in a solid state, and have completed the present invention.

That is, the present invention relates to (A) 99 to 40 parts by weight of a thermoplastic polyester and (B) 0.01 to 10 parts by weight with respect to 100 parts by weight of an olefin polymer.
1 to 60 parts by weight of a modified olefin copolymer obtained by graft-polymerizing parts by weight of an unsaturated carboxylic acid and / or a derivative thereof is melt-kneaded, and the melt mixture is further heated in a temperature range of 100 ° C or higher and not higher than the melting point of the mixture. The present invention relates to an improved thermoplastic polyester resin obtained by heating in a solid state for 30 minutes or more and grafting, and a method for producing the same.

 Hereinafter, the configuration of the present invention will be described in detail.

First, the thermoplastic polyester (A) used in the present invention
The term "polyester" refers to a polyester obtained by polycondensation of a dicarboxylic acid compound and a dihydroxy compound, polycondensation of an oxycarboxylic acid compound, polycondensation of a mixture of these three components, or the like. effective.

If the example of the dicarboxylic acid compound used here is shown,
Known dicarboxylic acid compounds such as terephthalic acid, isophthalic acid, naphthalenedicarboxylic acid, diphenyldicarboxylic acid, diphenyletherdicarboxylic acid, diphenylethanedicarboxylic acid, cyclohexanedicarboxylic acid, adipic acid and sebacic acid, and alkyl, alkoxy or halogen substitution products thereof. Is. Also, these dicarboxylic acid compounds can be used in the form of a derivative capable of forming an ester, for example, a lower alcohol ester such as dimethyl ester. In the present invention, one or more of the above compounds are used.

Examples of dihydroxy compounds are ethylene glycol, propylene glycol, butanediol, neopentyl glycol, hydroquinone, resorcin, dihydroxyphenyl, naphthalenediol, dihydroxydiphenyl ether, cyclohexanediol, 2,2
-Bis (4-hydroxyphenyl) propane, dihydroxy compounds such as diethoxylated bisphenol A, polyoxyalkylene glycols and alkyl, alkoxy or halogen substitution products thereof, etc., and one kind or a mixture of two or more kinds can be used. .

Examples of the oxycarboxylic acid include oxycarboxylic acids such as oxybenzoic acid, oxynaphthoic acid and diphenyleneoxycarboxylic acid, and alkyl, alkoxy or halogen substitution products thereof. Further, ester-formable derivatives of these compounds can also be used. In the present invention, one kind or two or more kinds of these compounds are used.

In the present invention, any of the thermoplastic polyesters produced by polycondensation can be used as the component (A) of the present invention, using the above compounds as monomer components, and can be used alone or in combination of two or more. However, it is preferable to use polyalkylene terephthalate, more preferably polybutylene terephthalate and a copolymer mainly composed of this.

Next, the modified olefin-based copolymer (B) having the constitution of the present invention and graft-polymerized with the unsaturated carboxylic acid and / or its derivative will be described.

Examples of the olefin polymer serving as the skeleton of (B) include homopolymers of ethylene, propylene, butene, methylpentene, and the like, and copolymers containing these as the main components.

As the copolymer component, other α-olefin component units such as propylene, 1-butene, 1-pentene, 4
-Methyl-1-pentene, 1-hexene, 1-octene, 1-decene, 1-dodecene, etc., diene component units such as 1,4-hexadiene, dicyclopentadiene, 5-
Examples thereof include non-conjugated diene components such as ethylidene-2-norbornene and 2,5-norbonadiene, and conjugated diene components such as butadiene, isoprene and piperylene. Also, polar vinyl monomer component units such as vinyl acetate,
Acrylic acid, methacrylic acid, acrylic acid ester, methacrylic acid ester, various metal salts of acrylic acid, various metal salts of methacrylic acid, etc. are also listed as the copolymerization component.

Among these, a copolymer of ethylene and α-olefin and a copolymer of ethylene and a polar vinyl monomer are preferable. As the ethylene-α-olefin copolymer, ethylene / propylene copolymer, ethylene / 1-butene copolymer, ethylene / 4-methyl-1-pentene copolymer, ethylene / 1-hexene copolymer, ethylene・ 1-
Two-component system such as octene copolymer, ethylene / 1-decene copolymer, ethylene / propylene / 1,4-hexadiene copolymer, ethylene / propylene / dicyclopentadiene copolymer, ethylene / propylene / 5-ethylidene −
2-norbornene copolymer, ethylene / 1-butene / dicyclopentadiene copolymer, ethylene / 1-butene /
A three-component system such as a 5-ethylidene-2-norbornene copolymer may be used. Further, as the ethylene-polar vinyl monomer copolymer, ethylene vinyl acetate, ethylene
Examples thereof include copolymers of acrylic acid, ethylene / methacrylic acid, ethylene / acrylic acid ester, ethylene / methacrylic acid ester, ethylene / acrylic acid metal salt, ethylene / methacrylic acid metal salt and the like.

On the other hand, the monomer to be grafted to the above-mentioned skeleton polymer is an unsaturated carboxylic acid and / or a derivative thereof, and α, β-ethylenically unsaturated dicarboxylic acid such as maleic acid, fumaric acid and itaconic acid and / or Alternatively, an acid anhydride, an ester, an amide, or an imide compound thereof can be used, and an unsaturated monocarboxylic acid can be acrylic acid, methacrylic acid, and / or an ester compound thereof.

Of these grafting monomers, maleic acid and / or maleic anhydride are particularly preferred.

The grafting monomer is required to be graft-polymerized in the range of 0.01 to 10 parts by weight with respect to 100 parts by weight of the olefin polymer as the skeleton, and further 0.05
It is preferably graft-polymerized in the range of 5 parts by weight. If it is less than 0.01 parts by weight, no improvement in impact resistance is observed, and if it exceeds 10 parts by weight, a gelled product is likely to be generated in the melt extrusion process.

From the viewpoint of improving impact resistance, the modified olefin copolymer (B) preferably has a low crystallinity of 40% or less, more preferably 20% or less. Such a modified olefin-based copolymer is produced by a known graft polymerization method.
For example, it can be obtained by adding an unsaturated carboxylic acid or the like to the olefin polymer as described above and preferably melt-kneading at 150 to 300 ° C. in the presence of a catalyst. Moreover, you may use a commercial item.

The mixing ratio of the thermoplastic polyester (A) and the modified olefin-based copolymer (B) used in the present invention is 99 to 40 parts by weight of the thermoplastic polyester (A), and the modified olefin-based copolymer (B) 1 -60 parts by weight, preferably (A) 95-50
Modified olefin copolymer (B) 5 to 50 parts by weight
The ratio is parts by weight. The components (A) and (B) are mixed by melt kneading using conventionally known and commonly used equipment and methods to obtain a melt mixture having various shapes depending on the purpose. For example, generally, the components (A) and (B) are pelletized,
Alternatively, it may be in the form of powder or granules and well mixed in advance with a blender or the like, and then melt-kneaded and extruded by using a single-screw or twin-screw extruder to form pellets, or in the form of a strand, a sheet, or any other desired shape in the subsequent process, Can be used for processing.

The above melt mixture used in the present invention is preferably in a state in which the thermoplastic polyester (A) and the grafted modified olefin copolymer (B) are dispersed as fine particles intimately adhered to each other. The size of dispersed fine particles constituting the molten mixture is usually 10 μm or less, preferably 3 μm or less.

The present invention is characterized in that the molten mixture obtained by the above method is further heat-treated at a specific temperature in a solid state, and the heat treatment is 100 ° C. or higher, at least in the temperature range of the melting point of the mixture or lower. It should be 30 minutes or longer, preferably 1 hour or longer. Heating temperature
If the temperature is less than 100 ° C, the effect of the present invention is not sufficiently exhibited or an extremely long time is required for the effect to be exhibited. Further, the heating time varies depending on the heating temperature, and generally, the higher the temperature, the shorter the time required.

The heat treatment method may be carried out according to the method usually employed in the solid phase polymerization method of polyester, and any of a batch type, a continuous type and a combination thereof may be used. The atmosphere during the heat treatment is not particularly limited, but it is preferably performed under reduced pressure or in the presence of an inert gas such as a nitrogen stream.

When performing heat treatment under reduced pressure, the residual air pressure is 10 Torr
It is preferably the following or less, and when the heat treatment is performed in the presence of residual air of 10 Torr or more, the thermoplastic polyester sometimes decomposes due to an oxidation reaction, which may cause a remarkable decrease in physical properties.

When the treatment is carried out in an inert gas atmosphere, examples of the inert gas include helium, nitrogen, neon, argon, krypton, xenon and the like, but helium, nitrogen and argon are preferably used.

As described above, the characteristic feature of the present invention resides in that a molten mixture comprising the thermoplastic polyester (A) and the modified olefin copolymer (B) is further heat-treated at a temperature of 100 ° C. or higher and a melting point of the mixture or lower, By carrying out such a treatment, a characteristic which cannot be obtained by simply melt-kneading both is generated.

It is generally well known that the mechanical properties of a polyester resin molded product are modified by heat treatment due to changes in its molecular orientation. It is also known that properties such as tensile elongation and impact strength increase due to an increase in the degree of polymerization due to solid phase polymerization and the like. However, surprisingly, the thermoplastic polyester resin produced by the method of the present invention is not merely a modification by orientation of molecules by so-called annealing of polyester, and is not a modification by only increasing the degree of polymerization by solid-state polymerization. This is proved not to be a mere annealing effect because a remarkable impact resistance can be obtained only by molding the improved thermoplastic polyester resin pellets according to the present invention, and the degree of polymerization can be increased in advance by an operation such as solid phase polymerization. The resulting polyester and the modified olefin copolymer (B) used in the present invention have much higher impact resistance (toughness), which cannot be obtained by simply melt-blending, and have other different properties. More obvious than that.

Therefore, the high impact resistance (high toughness) of the molten mixture of the thermoplastic polyester (A) and the modified olefin copolymer (B) by heat treatment is merely an annealing effect,
Alternatively, not only by increasing the degree of polymerization of the polyester alone, but by heat treatment, a reaction occurs between the polyester (A) and the modified olefin-based copolymer (B) to form a chemical bond between them, that is, a branched structure. It is understood to be due to. The formation of the branched structure is obvious from the fact that the impact value and the tensile elongation are greatly improved, but the formation of the branched structure can be supported by the behavior such as dynamic viscoelasticity in the molten state. For example, regarding the die swell phenomenon at the time of extrusion, an increase in die swell which is not seen in the high degree of polymerization due to simple solid-state polymerization of polyester is also observed, suggesting that the product of the present invention has a branched structure. It is believed that

The improved thermoplastic polyester resin obtained by the present invention can be injection-molded, extrusion-molded, compression-molded, foam-molded, blow-molded, vacuum-molded, etc. depending on its application, and in any of the molded products, the elastic modulus and the rigidity can be improved. The point is that it has high impact resistance without decreasing

Alternatively, the components (A) and (B) may be melt-mixed and molded into a desired shape, and the molded product may be heat-treated under specific conditions to impart desired properties.

Next, in the present invention, the compounding of the inorganic filler (C) is not always essential, but a molded product excellent in performance such as mechanical strength, heat resistance, dimensional stability (deformation resistance, warpage), and electrical properties is obtained. For this purpose, it is preferable to mix them at any stage of their preparation, and fibrous, powdery, or plate-like fillers are used for this purpose.

As the fibrous filler, glass fiber, asbestos fiber, carbon fiber, silica fiber, silica-alumina fiber, zirconia fiber, boron nitride fiber, silicon nitride fiber, boron fiber, potassium titanate fiber, stainless steel, aluminum, titanium, Inorganic fibrous substances such as metallic fibrous substances such as copper and brass can be used. A particularly representative fibrous filler is glass fiber or carbon fiber.

On the other hand, as the particulate filler, carbon black, silica, quartz powder, glass beads, glass powder, calcium silicate, aluminum silicate, kaolin, talc, clay,
Diatomaceous earth, silicates such as wollastonite, oxides of metals such as iron oxide, titanium oxide, zinc oxide and alumina, carbonates of metals such as calcium carbonate and magnesium carbonate, sulfuric acid of metals such as calcium sulfate and barium sulfate. Examples thereof include salts, other silicon carbide, silicon nitride, boron nitride, and various metal powders.

Examples of the plate-shaped filler include mica, glass flakes, various metal foils and the like.

These inorganic fillers can be used alone or in combination of two or more. The combined use of a fibrous filler, especially glass fiber or carbon fiber, with a granular and / or plate-like filler is a preferable combination particularly in terms of having both mechanical strength, dimensional accuracy, and electrical properties.

When using these fillers, it is desirable to use a sizing agent or a surface treatment agent if necessary. Examples of this are functional compounds such as epoxy compounds, isocyanate compounds, silane compounds and titanate compounds. These compounds may be subjected to a surface treatment or a converging treatment in advance, or may be added at the same time when the material is prepared.

These inorganic fillers are added in an amount of 5 to 120 parts by weight per 100 parts by weight of the polymer mixture of (A) and (B). If the addition amount of the filler exceeds 120 parts by weight, the moldability of the mixture is significantly deteriorated, which is not preferable.

Further, the improved thermoplastic polyester resin of the present invention can be used as a composition by supplementarily using a small amount of another thermoplastic resin in addition to the above components within a range not impairing the purpose. Examples of the other thermoplastic resin used here include polyamide, ABS, polyphenylene oxide, polyalkyl acrylate, polyacetal, polysulfone, polyether sulfone, polyetherimide, polyether ketone, phenoxy resin, and fluororesin. You can Further, these thermoplastic resins may be used as a mixture of two or more kinds.

Incidentally, such a thermoplastic resin that is supplementarily added is the component (A) and the component (B) in the process of producing the improved thermoplastic resin of the present invention.
Melt kneading may be performed in addition to the components, and the effect of the present invention can be obtained as such.

Furthermore, in the thermoplastic polyester resin of the present invention, known substances generally added to thermoplastic resins and thermosetting resins, that is, stabilizers such as antioxidants and ultraviolet absorbers, antistatic agents, flame retardants, It is of course possible to add a colorant such as a dye or a pigment, a lubricant, a crystallization accelerator, a crystal nucleating agent and the like.

The above-mentioned inorganic fillers, additives and the like may be added at any stage of obtaining the improved polyester resin of the present invention, and it is of course possible to add and mix them immediately before obtaining the final molded product.

〔Example〕

Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited to these examples.

Examples 1 and 2 Modified olefin having a crystallinity of 5% obtained by graft-copolymerizing polybutylene terephthalate having an intrinsic viscosity of 1.0 as the component (A) and ethylene / α-olefin copolymer as the component (B). After mixing with the system copolymer (B-1) in the ratio shown in Table 1, it melt-kneaded and granulated using the extruder set to 250 degreeC. The granulated pellets were heat-treated under a nitrogen stream under the conditions shown in Table 1.

Subsequently, using the pellets, various test pieces were prepared by injection molding, and physical properties were evaluated by the following methods.

Tensile test: Tensile strength (kg / cm ² ) according to ASTM D638,
Tensile elongation (%) was measured.

Bending test: Using a test piece having a thickness of 6.4 mm, the bending strength (kg / cm ² ) and the bending elastic modulus (kg / cm ² ) were measured according to ASTM D790.

Izod impact strength: ASTM D
According to 256, Izod impact strength with notch (kg ・ cm / c
m) was measured.

 The results are shown in Table 1.

Examples 3 to 5 Pellets were prepared in the same manner as in Example 1 and evaluated in the same manner as in Example 1 except that the heating conditions shown in Table 1 were used.

Comparative Examples 1 and 2 When polybutylene terephthalate alone was granulated by the same method as in Example 1 and then injection-molded without heat treatment (Comparative Example 1), and granulated pellets were heated in the same manner as in Example 1. Table 1 shows the physical properties of the molded product after the treatment and the injection molding (Comparative Example 2).

Comparative Example 3 The heat-treated polybutylene terephthalate and the modified olefin-based copolymer (B-1) prepared in Comparative Example 2 were mixed in the proportions shown in Table 1, and then melt-mixed into pellets and heated as they were. Molded without treatment and evaluated for physical properties. The results are shown in Table 1.

Comparative Examples 4 and 5, without heating the pellets granulated in Examples 1 and 2,
The physical properties were evaluated. The results are shown in Table 1.

Example 6 As the component (B), a modified olefin copolymer (B-2) obtained by graft-copolymerizing maleic acid and having a crystallinity of 3%.
After granulating in the same manner as in Example 1 except that the above was used in the proportions shown in Table 1, physical properties were evaluated by heat treatment. The results are shown in Table 1.

Comparative Example 6 The physical properties of the pellets granulated in Example 6 were evaluated without heat treatment. The results are shown in Table 1.

Example 7 As the component (B), an ethylene / ethyl acrylate copolymer (B-
After granulating in the same manner as in Example 1 except that 3) was used in the proportions shown in Table 1, physical properties were evaluated by heat treatment under a nitrogen stream. The results are shown in Table 1.

Comparative Example 7 The physical properties of the pellets granulated in Example 7 were evaluated without heat treatment. The results are shown in Table 1.

Example 8 Pellets were prepared in the same manner as in Example 1 and evaluated in the same manner as in Example 1 except that the heat treatment atmosphere was performed under a reduced pressure of 1 Torr.

Example 9 A modified olefin copolymer (B-) obtained by graft-copolymerizing polyethylene terephthalate having an intrinsic viscosity (IV) of 0.8 as the component (A) and maleic anhydride as the component (B).
1) and 1) were mixed in the proportions shown in Table 2, and then melt-kneaded using a 30 mmφ extruder set at 280 ° C. to granulate. The granulated pellets were heat-treated under a nitrogen stream under the conditions shown in Table 2 to measure the physical properties. The results are shown in Table 2.

Comparative Example 8 The physical properties of the pellets granulated in Example 9 were evaluated without heat treatment. The results are shown in Table 2.

Examples 10 and 11 The ethylene / α-olefin copolymer (B-1) obtained by graft-copolymerizing the polybutylene terephthalate and maleic anhydride used in Example 1 was further added with glass fibers (Examples).
10) Alternatively, glass beads (Example 11) were blended in the proportions shown in Table 2, granulated in the same manner as in Example 1, and then heat-treated under the conditions shown in Table 2 to measure physical properties. The results are shown in Table 2.

Comparative Examples 9 and 10 The physical properties of the pellets granulated in Examples 10 and 11 were evaluated without heat treatment. The results are shown in Table 2.

Example 12 As the component (B), an ethylene / ethyl acrylate copolymer (B-
After granulating in the same manner as in Example 10 except that 3) was used, heat treatment was performed under the conditions shown in Table 2 and the physical properties were measured. The results are shown in Table 2.

Comparative Example 11 The physical properties of the pellets granulated in Example 12 were evaluated without heat treatment. The results are shown in Table 2.

Comparative Examples 12 and 13 Polybutylene terephthalate and glass fiber (Comparative Example 1
2) Or glass beads (Comparative Example 13) were mixed in the proportions shown in Table 2, pelletized in the same manner as in Examples 10 and 11, and the physical properties were evaluated without heat treatment. The results are shown in Table 2.

[Effects of the Invention] As apparent from the above description and Examples, the improved polyester of the present invention is extremely remarkable (about 10%) as compared with the original thermoplastic polyester without impairing other physical properties.
Double) The impact strength is improved. Further, the improved polyester resin which has been treated according to the present invention is improved in elongation without substantially lowering the tensile strength, bending strength, etc. and elastic modulus, even compared to an intermediate product obtained by simply melt-kneading the constituent components. Moreover, the impact strength is remarkably improved, and the strength is extremely strong.

The improved thermoplastic polyester resin of the present invention having such characteristics is suitable for automobile parts (for example, bumpers, exterior plates, wheel covers, etc.), electric parts, OA equipment (housing), etc. that are required to have high rigidity and high impact resistance. Can be used.

Claims (6)

[Claims] 1. (A) Polybutylene terephthalate 99-40
0.01 to 10 parts by weight based on 100 parts by weight of (B) olefin polymer
1 to 60 parts by weight of a modified olefin copolymer obtained by graft-polymerizing parts by weight of an unsaturated carboxylic acid and / or a derivative thereof is melt-kneaded, and the melt mixture is further heated in a temperature range of 100 ° C or higher and not higher than the melting point of the mixture. A method for producing an improved polybutylene terephthalate resin composition obtained by heat-treating in a solid state for 30 minutes or more and grafting. 2. The heat treatment is carried out in an inert gas atmosphere or at 10 Torr.
The method for producing an improved polybutylene terephthalate resin composition according to claim 1, which is carried out under the following reduced pressure. 3. The improved polybutylene terephthalate resin composition according to claim 1, wherein the olefin polymer constituting the modified olefin copolymer (B) is a copolymer of ethylene and α-olefin. Manufacturing method. 4. The improved polybutylene according to any one of claims 1 to 3, wherein the olefin polymer constituting the modified olefin copolymer (B) is a copolymer of ethylene and a polar vinyl monomer. Method for producing terephthalate resin composition. 5. The polar vinyl monomer is one or more selected from vinyl acetate, acrylic acid, methacrylic acid, acrylic acid ester, methacrylic acid ester, acrylic acid metal salt, and methacrylic acid metal salt. A method for producing the improved polybutylene terephthalate resin composition according to claim 4. 6. The method for producing the improved polybutylene terephthalate resin composition according to claim 1, at any stage of the production of the improved polybutylene terephthalate resin composition, or after the preparation of the improved polybutylene terephthalate resin composition, the inorganic filler (C) is added to the resin component (A + B). ) A method for producing an improved polybutylene terephthalate resin composition, which comprises adding 5 to 120 parts to 100 parts by weight and uniformly mixing the resin components under melting.