JPH0678479B2 - Polyester resin composition - Google Patents

Description

TECHNICAL FIELD The present invention relates to a polyester resin composition having excellent molding stability.

[Prior Art] A polyester resin is used in various fields as various molded products by utilizing its excellent properties. However, in these polyester resins, at a molding temperature of 250 ° C. or higher, the molecular weight is partially reduced due to thermal decomposition, and the melt viscosity decreases with time.

In particular, in injection molding or the like in which the resin is kept at a high temperature for a relatively long time, the melt viscosity is greatly reduced, and this causes a problem in molding stability.

Regarding the improvement of such a defect, for example, JP-A-58-83
No. 047 publication, "a composition comprising a saturated polyester resin and a certain range of composition, ethylene-unsaturated carboxylic acid-unsaturated carboxylic acid ester-unsaturated carboxylic acid metal salt copolymer" is proposed, It is disclosed that, when processed into various molded products, the moldability is good because the stability of the melt viscosity is good.

However, the copolymer proposed in this publication is a metal chloride of a copolymer produced using a normal high-pressure polyethylene production apparatus, and its average molecular weight is relatively high, as is clear from the examples. It becomes a thing.

However, when the copolymer having a relatively high average molecular weight is blended with the polyester resin, it is difficult to disperse the polyester resin in a sufficiently uniform manner, and the fluidity of the composition is lowered. Further, the stability of the melt viscosity of the composition is still not sufficient.

On the other hand, JP-A-60-35049 discloses a composition in which a polyester resin is blended with an α-olefin having an average molecular weight of 5,000 or less and an α, β-unsaturated carboxylic acid copolymer, part of which is a metal salt. It has been disclosed that it is easy to be kneaded sufficiently uniformly with polyester in a molten state, and that the meltability after kneading is good and the moldability is good.

However, in the experiments conducted by the present inventors, even if the metal salt of the above copolymer was added to the polyester, the melt viscosity stability of the polyester at high temperature was not improved.

[Problems to be Solved by the Invention] An object of the present invention is to prevent the decrease of the melt viscosity of a polyester resin at high temperature, maintain the molding stability, and at the same time, to improve the fluidity of the composition and the co-weight with the polyester resin. It is intended to provide a polyester resin composition which can improve the homogeneity with a coalesced and / or copolymer salt, and further with a filling substance.

[Means for Solving Problems] The present invention is based on at least the saturated polyester resin (A) 100.
80 parts by weight of ethylene, an α, β-unsaturated carboxylic acid, obtained by thermally degrading a copolymer of relatively high molecular weight ethylene and an α, β-unsaturated carboxylic acid alkyl ester in parts by weight. And the total content of the α, β-unsaturated carboxylic acid alkyl ester is 0.5 to 20 mol%, the composition ratio of the acid and the alkyl ester is 10 to 90% and 90 to 10%, and
A low molecular weight terpolymer (B) having an intrinsic viscosity in the range of 0.07 to 0.6 in decalin at 135 ° C. and / or at least a part or all of the carboxylic acid units of the terpolymer (B) has a valence of A polyester resin composition comprising 0.2 to 30 parts by weight of a copolymer salt (B) 'which is obtained by reacting with a compound of a metal selected from 1 to 3 valences.

Polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polycyclohexane 1,4-dimethylol terephthalate and copolymers thereof are suitable as the saturated polyester (A) of the present invention. As the acid component, it is possible to use terephthalic acid in combination with other aromatic or aliphatic dicarboxylic acid, for example, one or more of isophthalic acid, phthalic acid, adipic acid, azelaic acid and sebacic acid, depending on the purpose. .

Furthermore, as glycol component, ethylene glycol, 1,
In addition to 4-butanediol, other aliphatic diol components,
For example, modified saturated polyesters containing neopentyl glycol, polytetramethylene glycol, etc. may be used.

Among these, the preferred polyester in the present invention is
Polyethylene terephthalate, polybutylene terephthalate and at least 80 mol% of a copolyester having ethylene terephthalate as a repeating unit, particularly preferably polyethylene terephthalate.

The polyester used in the present invention preferably has an intrinsic viscosity of 0.4 or more from the viewpoint of strength properties of the resulting molded product. The intrinsic viscosity referred to here is a value measured at 30 ° C. in a phenol / tetrachloroethane mixed solvent having a weight ratio of 1: 1.

Ethylene-α, β which is the component (B), (B) ′ of the present invention
-Unsaturated carboxylic acid-unsaturated carboxylic acid alkyl ester copolymer or a metal salt thereof means a thermal reduction produced by thermally decomposing a commercially available relatively high-molecular ethylene-α, β-unsaturated carboxylic acid ester. At least a part or all of the product or its thermal degradation product is reacted with a compound having a valence of 1 to 3 and a metal.

For example, an ethylene- (meth) acrylate copolymer as a relatively high molecular weight ethylene-α, β-unsaturated carboxylic acid alkyl ester in an inert atmosphere in the presence of water at a temperature of 200 to 500 ° C. and a pressure of 5 to 5 ° C. An ethylene- (meth) acrylic acid-alkyl (meth) acrylate copolymer can be produced by reacting under the conditions of 500 Kg / cm ² .

As the relatively high molecular weight ethylene-α, β-unsaturated carboxylic acid alkyl ester copolymer before degradation used in the present invention, ethylene and acrylic acid or methacrylic acid alkyl ester copolymer are preferable, It is easily obtained by a high pressure copolymerization method. The melt index of the above copolymer is about 300 g / 10 minutes or less, and the unsaturated alkyl carboxylate content in the molecular chain is about 0.5 to 25 mol%, preferably 1 to 15 mol%.

Specific examples of the ethylene-α, β-unsaturated carboxylic acid alkyl ester copolymer include ethylene-ethyl acrylate, ethylene-methyl methacrylate, ethylene-n-propyl acrylate, ethylene-isopropyl acrylate, ethylene- It is a copolymer of n-butyl acrylate, ethylene-sec-butyl acrylate, tert-butyl acrylate, etc., wherein the alkyl of the unsaturated carboxylic acid alkyl ester is an alkyl group having 1 to 4 carbon atoms, that is, a methyl group. , Ethyl group, isopropyl group, n-butyl group, isobutyl group, tert-butyl group and the like are preferable.

The method for thermally degrading the above-mentioned ethylene-α, β-unsaturated carboxylic acid alkyl ester copolymer is ethylene-α, β-
It depends on factors such as the average molecular weight of the unsaturated carboxylic acid alkyl ester copolymer, the content of the α, β-unsaturated carboxylic acid alkyl ester, the degree of lowering the molecular weight, and the amount of coexisting water. The reaction temperature is 200 to 500 ° C., the reaction pressure is 5 to 500 kg / cm ² , and the reaction time is 1 to 10 hours, preferably 2 to 6 hours using a mold or tank reactor.

Regarding the above thermal degradation method, Japanese Patent Publication No.
It is described in detail in the publications and the like.

The thus obtained ethylene-α, β-unsaturated carboxylic acid-α, β-unsaturated carboxylic acid alkyl ester copolymer (B) of the present invention means 80 to 99.5 mol% of ethylene,
The total content of the α, β-unsaturated carboxylic acid and the α, β-unsaturated carboxylic acid alkyl ester is 0.5 to 20 mol%, preferably 1 to 10 mol%, and the composition ratio of the acid and the ester is 10 to 90. % To 90 to 10%, and the intrinsic viscosity in decalin at 135 ° C. is 0.07 to 0.6, preferably 0.12 to 0.5, and is a low molecular weight terpolymer.

The total content of acid and ester of the above copolymer is 0.5 mol%
If it is less than 20 mol%, the effect of improving the melt viscosity cannot be obtained, and if it exceeds 20 mol%, not only the effect of stabilizing the melt viscosity is not further improved, but also the manufacturing cost of the copolymer becomes high, and the manufacturing itself is also It's difficult.

The composition ratio of acid and ester in the copolymer is 10 to 90%.
Even outside the range of 90 to 10%, stabilization of the melt viscosity cannot be desired.

It is necessary that the α, β-unsaturated carboxylic acid alkyl ester unit is substantially present in the above copolymer.
When the α, β-unsaturated carboxylic acid ester unit is substantially absent, in the composition of the saturated polyester resin and the copolymer or the metal salt of the metal salt of the copolymer, a stable melt viscosity at high temperature is obtained. The improvement of the property is not seen, and the uniformity of the composition is deteriorated.

In the decalin of the copolymer (B), when the intrinsic viscosity at 135 ° C. is 0.07 or less, at least a part of the carboxylic acid unit of the copolymer (B) and / or the copolymer (B) is used as a metal salt. The polymer metal salt (B) 'has a small melt viscosity, and it is difficult to uniformly mix them with the polyester resin. When the intrinsic viscosity exceeds 0.6, the effect of stabilizing the melt viscosity of the composition at high temperature becomes small, and the fluidity of the composition also decreases.

The metal salt of the low molecular weight terpolymer which is the component (B) 'of the present invention comprises at least a part or all of the α, β-unsaturated carboxylic acid units in the low molecular weight terpolymer described above. It is obtained by reacting with a compound of a metal having a valence of 1 to 3.

Examples of the metal having a valence of 1 to 3 include Na, K, Li and M.
It is selected from g, Ca, Ba, Zn, Sb, Cu, Fe, Al, Fe and mixtures thereof, and among these, alkali metals are particularly preferable.

The compounds include sodium hydroxide, magnesium hydroxide, potassium hydroxide, zinc hydroxide, calcium oxide,
Examples thereof include sodium methoxide, sodium ethoxide, magnesium oxide, nickel acetate, sodium carbonate, magnesium acetate, zinc acetate and the like.

The reaction between these metal compounds and the copolymer is described in JP-B-49-6810.
Or the method of reacting a metal compound under heat-melt kneading of a copolymer, or JP-A-60-
-The method disclosed in Japanese Patent Publication No. 79015, that is, ethylene-
For example, a method of converting a α, β-unsaturated carboxylic acid alkyl ester copolymer into a low molecular weight terpolymer metal salt in one step by a method of heating and degrading in the presence of water and a metal ion in an inert atmosphere. Known methods are used.

Among the various processes described above, at least the acrylic acid unit of the ethylene-acrylic acid-ethyl acrylate copolymer obtained by thermally degrading the ethylene-ethyl acrylate copolymer produced by the high-pressure radical polymerization method. Most preferred is a metal salt of a low molecular weight terpolymer having a sodium salt partially.

The mixing ratio of the component (A) to the component (B) and / or (B) 'is 0.2 to 30 parts by weight with respect to 100 parts by weight of the component (A). Preferably 1
~ 20 parts by weight. Above (B) and / or (B) ′
When the content of the component is less than 0.2 parts by weight, the effect of improving the melt viscosity is hardly seen, and when it exceeds 30 parts by weight, the mechanical properties of the composition are adversely affected.

In the present invention, in addition to the above-mentioned component (A), component (B) and / or component (B) ', a filling substance (C) can be further blended.

The compounding amount of the filling substance (C) is 10 to 150 parts by weight. If the amount is less than 10 parts by weight, there is no improvement effect, and if it exceeds 150 parts by weight, the mechanical strength is rather lowered.
In addition, moldability also decreases.

As the filling substance (C) of the present invention, an inorganic or organic filling substance can be used. Specifically, calcium sulfate, calcium silicate, clay, diatomaceous earth, talc, alumina, silica sand, glass powder, iron oxide, metal powder, graphite, silicon carbide, silicon nitride, silica, boron nitride, aluminum nitride, carbon black, etc. Powder-granular filler, mica, glass plate, sericite, pyrophyllite, metal foil such as aluminum flake, flat plate-like or scale-like filler such as graphite, shirasu balloon, metal balloon, glass balloon,
Examples thereof include hollow fillers such as pumice, glass fibers, carbon fibers, graphite fibers, whiskers, metal fibers, silicon carbide fibers, mineral fibers such as asbestos and wollastonite.

In particular, fiber materials such as glass fiber are preferable because they significantly improve mechanical properties. Further, the surface of the inorganic material is coated with a fatty acid such as stearic acid, oleic acid, palmitic acid or a metal salt thereof, paraffin, wax, polyethylene wax or a modified product thereof, organic silane, inorganic borane, organic titanate, etc. It is preferable to perform the surface treatment of.

The composition of the present invention may contain a conventionally used nucleating agent and crystallization accelerator. Examples of these nucleating agents and crystallization accelerators include talc, clay, mica, inorganic compounds such as silica, sodium stearic acid, organic carboxylic acids such as montanic acid, sodium and potassium salts, polynuclear cyclic compounds such as phenanthrene, and ionomers. is there.

Further, a usual additive such as a flame retardant, an ultraviolet absorber, an antioxidant, a colorant, a hydrolysis resistant agent may be added. Furthermore, other thermoplastic resins such as polyethylene, polypropylene, polycarbonate, polyamide, polyphenylene oxide, polyphenylene sulfide, polyarylene, polyether, ether ketone, polystyrene and the like may be blended.

The composition of the present invention comprises a polyester resin (A), a low molecular weight terpolymer (B) and / or (B) ', and optionally inorganic fillers, additives, etc., in a Banbury mixer, a pressure kneader, a kneading extrusion. It is manufactured by melt-kneading with a kneader that is usually used, such as a machine, a twin-screw extruder, or a roll.

[Examples] Examples of the present invention will be described below.

Example 1 An ethylene-ethyl acrylate copolymer having a content of ethyl acrylate units of 6.7 mol% obtained by a high-pressure radical polymerization method and a melt index of 3.4 g / 10 minutes measured according to JIS K6760 was subjected to a tubular reaction. Maximum temperature of 39 in the presence of water
Continuously heat-degraded at 0 ℃, ethylene unit 95.1 mol%, acrylic acid unit 2.3 mol% ethyl acrylate unit 2.6
Mol% and the intrinsic viscosity of decalin at 135 ° C. is 0.1
An ethylene-acrylic acid-ethyl acrylate copolymer of 7 was obtained.

An aqueous solution of sodium hydroxide was added to this copolymer under heat-melting and kneading to obtain a copolymer metal salt (B) 'in which 75% of acrylic acid units in the copolymer were changed to sodium salts.

In a phenol / tetrachloroethane mixed solvent (weight ratio 1:
1), 5.3 parts by weight of the above copolymer salt was added to 100 parts by weight of a polyethylene terephthalate resin (A) (hereinafter referred to as PET) having an intrinsic viscosity of 0.68 at 30 ° C., and melt-mixed at 250 ° C. for 5 minutes using a kneader. A composition was prepared.

The PET and the copolymer metal salt (B) 'were used in the completely dry state including the following Examples and Comparative Examples.

To measure the melt viscosity, the composition was put into a melt indexer controlled at 280 ° C., held at that temperature for 5 minutes and 30 minutes, extruded under a load of 500 g, and the melt index was measured. Shown in the table.

Example 2 The copolymer metal salt obtained in Example 1 was treated with the same PET as in Example 1.
1.5 parts by weight was added to 100 parts by weight to prepare a composition in the same manner as in Example 1, and the melt index was measured. The results are shown in Table 1.

Example 3 The ethylene-ethyl acrylate copolymer used in Example 1 was continuously heat-degraded at a maximum temperature of 390 ° C. in the presence of water and sodium hydroxide in a tubular reactor to give ethylene units of 9 units.
A copolymer metal salt having 5.4 mol%, 3.1 mol% acrylic acid units (75% of which is a sodium salt), and 1.5 mol% ethyl acrylate units was obtained.

When the copolymer metal salt was treated with an aqueous sulfuric acid solution and all the sodium salt was acrylic acid, the intrinsic viscosity of the copolymer in decalin at 135 ° C. was 0.26.

This copolymer metal salt was added to 100 parts by weight of PET used in Example 1.
5.0 parts by weight was added, and a composition was prepared in the same manner as in Example 1 below, and the melt index after 5 minutes and 30 minutes was measured. The results are shown in Table 1.

Example 4 The ethylene-acrylic acid-ethyl acrylate copolymer obtained by heating and degrading the ethylene-ethyl acrylate copolymer in Example 1 was used for 100 parts by weight of PET used in Example 1.
4.0 parts by weight was added, and the composition was prepared by the same operation as in Example 1 below, and the melt index after 5 minutes and 30 minutes was measured. The results are shown in Table 1.

Example 5 To 100 parts by weight of PET used in Example 1, 3.9 parts by weight of the metal salt of the copolymer obtained in Example 1 and 30 parts by weight of glass fiber were added and melt-mixed at 250 ° C. for 5 minutes using a kneader. To prepare a composition.

The composition was charged into a melt indexer controlled at 280 ° C., and the temperature was maintained for 5 minutes and 30 minutes, and then a load of 2160 g was applied to measure the extrusion melt index. As a result, melt index 43 after holding for 5 minutes
The melt index after maintaining at g / 10 minutes and 30 minutes was 42 g / 10 minutes.

Comparative Example 1 The PET used in Example 1 was subjected to the same melt index measurement as in Example 1. The results are shown in Table 1.

Comparative Example 2 An ethylene-methyl methacrylate copolymer having a methyl methacrylate unit content of 4.2 mol% obtained by a high-pressure radical polymerization method and an intrinsic viscosity of 0.75 at 135 ° C. in decalin was mixed with a toluene / isopropyl alcohol mixed solvent. , 12
Saponified with sodium hydroxide at 0 ° C. The saponification reaction product was dispersed in water, and sulfuric acid was added thereto to make a part of the sodium methacrylic acid salt unit in the copolymer a methacrylic acid unit. When this was dried and analyzed, it was found that the ethylene unit was 95.8 mol%, the methacrylic acid unit was 1.3 mol%, the sodium methacrylic acid salt unit was 1.7 mol%, and the methacrylic acid unit was 1.2 mol%.

PET using 5.0 parts by weight of the above copolymer metal salt in Example 1
In addition to 100 parts by weight, a composition was prepared in the same manner as in Example 1 and the melt index was measured. First result
Shown in the table.

Comparative Example 3 The same ethylene-ethyl acrylate copolymer as used in Example 1 was heat-degraded in a tank reactor in the presence of water at a temperature of 360 ° C. to obtain ethylene units of 95.98 mol% and acryl. Acid unit 4.0 mol%, ethyl acrylate unit 0.02 mol%
Thus, a copolymer having an intrinsic viscosity of 0.08 in decalin at 135 ° C. was obtained.

An aqueous sodium hydroxide solution was added to this copolymer while being heated and melt-kneaded to obtain a copolymer metal salt in which all acrylic acid units in the copolymer were sodium salts.

5.0 parts by weight of the above copolymer metal salt was added to 100 parts by weight of the same PET as used in Example 1, a composition was prepared in the same manner as in Example 1, and the melt index was measured.
The results are shown in Table 1.

Comparative Example 4 The same ethylene-ethyl acrylate copolymer as used in Example 1 was used in a tank reactor in the absence of water at 345 ° C.
A copolymer having an ethylene unit of 94.0 mol%, an acrylic acid unit of 0.2 mol%, an ethyl acrylate unit of 5.9 mol% and an intrinsic viscosity of 0.35 at 135 ° C. in decalin was obtained by heating and degrading at the temperature of.

5.0 parts by weight of the above copolymer was added to 100 parts by weight of the same PET as used in Example 1 to prepare a composition in the same manner as in Example 1, and the melt index was measured. First result
Shown in the table.

[Effects of the Invention] The polyester resin composition of the present invention is excellent in stability of melt viscosity under heating, and therefore excellent in molding stability.

Further, the composition has good fluidity and good moldability.

Further, the composition of the copolymer metal salt (B) 'and the polyester resin also has a characteristic that the crystallization rate is high.

Since the polyester resin composition of the present invention has the above-mentioned excellent properties, it is suitable for use in the fields of injection molding of electric / electronic parts, automobile parts, films, bottles and the like.

Claims (9)

[Claims] 1. At least a saturated polyester resin (A)
80 to 99.5 mol% of ethylene, α, β-unsaturated carboxylic acid obtained by thermally degrading 100 parts by weight of a copolymer of relatively high molecular weight ethylene and α, β-unsaturated carboxylic acid alkyl ester And the total content of the α, β-unsaturated carboxylic acid alkyl ester is 0.5 to 20 mol%, and the composition ratio of the acid and the alkyl ester is 10 to 90% to 90 to 10%,
And low molecular weight terpolymer (B) having an intrinsic viscosity in the range of 0.07 to 0.6 in decalin at 135 ° C. and / or at least part or all of the carboxylic acid unit of the terpolymer (B) is an atom. A polyester resin composition comprising 0.2 to 30 parts by weight of a copolymer salt (B) 'which is obtained by reacting with a metal compound selected from valences 1 to 3. 2. A composition comprising 100 parts by weight of the component (A), 0.2 to 30 parts by weight of the component (B) and / or (B) 'and 10 to 150 parts by weight of the filler (C). The polyester resin composition according to item 1 above. 3. The relatively high molecular weight ethylene-α, β-
Α, β- of unsaturated carboxylic acid alkyl ester copolymer
Content of unsaturated carboxylic acid alkyl ester units is 0.5
The polyester resin composition according to claim 1, which is -25 mol%. 4. The relatively high molecular weight ethylene-α, β-
The polyester resin composition according to claim 3, wherein the alkyl group of the alkyl ester of the unsaturated carboxylic acid alkyl ester copolymer has 1 to 4 carbon atoms. 5. The relatively high molecular weight ethylene-α, β-
The polyester resin composition according to any one of claims 1 to 4, wherein the unsaturated carboxylic acid alkyl ester copolymer is an ethylene-acrylic acid alkyl ester copolymer or an ethylene-alkyl methacrylate copolymer. 6. The method according to claim 1, wherein the ethylene-acrylic acid alkyl ester copolymer or the ethylene-methacrylic acid alkyl ester copolymer is an ethylene-ethyl acrylate copolymer or an ethylene-methyl methacrylate copolymer. The polyester resin composition according to item 5. 7. The polyester resin composition according to claim 1, wherein the component (A) is polyethylene terephthalate. 8. The polyester resin composition according to claim 1, wherein the compound of the metal selected from the valences 1 to 3 of the component (B) 'is a sodium compound. 9. The polyester resin composition according to claim 2, wherein the filling substance of the component (C) is glass fiber.