JPH11240962A - Molded product of polyester resin composition having improved processabillty - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a new and useful molded product of a polyester resin composition having excellent productivity and heat resistance, and to provide its molding method. SOLUTION: This molded product is composed of a polyester resin composition having improved processability, comprising (A) a high molecular weight aliphatic polyester having 10,000-1,000,000 number-average molecular weight and (B) a crystal nucleus agent and blending the component A with the component B so as to have <15 deg.C half breadth of an exothermic peak according to slow crystallization of the component A and measured at a slow cooling rate of 3 deg.C/min, and is obtained by molding the composition under a composition satisfying formulae (1) and (2). formula (1): (Q-R)/2<25<(P-R), formula (2): P<5<(P+100), P: melting point ( deg.C), Q: exothermic peak temperature ( deg.C), R: mold temperature ( deg.C), S: molding temperature ( deg.C).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a polyester resin composition having improved moldability. More specifically, the present invention relates to a molded article containing a polyester resin composition having improved moldability by adding a crystal nucleating agent to a high molecular weight aliphatic polyester and a molding method thereof.

[0002]

2. Description of the Related Art Generally, aliphatic polyesters are recognized for their biodegradability, and are expected to be used in fibers, molded articles, sheets and films by utilizing their characteristics.

However, the present inventors have been studying the moldability of aliphatic polyesters for a long time, and found that there are two serious problems. First, the aliphatic polyester has a half width of an exothermic peak based on slow cooling crystallization in a measurement with a differential scanning calorimeter (hereinafter abbreviated as DSC) of 15 ° C. or more as measured by a cooling rate of 3 ° C./min. It was found that the crystallization was slow and the moldability was poor. For example, at the time of injection molding, the crystallization speed is slow, so that sufficient crystallization does not occur in the mold,
There is a problem that the surface appearance is poor, and in the worst case, the mold cannot be released from the mold. As for this problem, the inventors of the present invention have conducted research for some time, and as a result, have obtained some findings, and proposed Japanese Patent Application Laid-Open No. 8-120165 as one of them. Japanese Patent Application Laid-Open No. 8-120165 provides a polyester resin composition having a high crystallization rate, excellent moldability, and biodegradability. However, although it was confirmed that the crystallization speed of the polyester resin was increased by this method, it was found that this was not sufficient when actually performing various moldings.

Second, the aliphatic polyester has a molecular weight retention of less than 50% after 190 ° C. and 30 minutes, has poor heat resistance, and is not suitable for use as various molded articles which are plastically processed by heating and melting. Turned out to be.

[0005]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems of the aliphatic polyester, and provides a molded article comprising a new and useful polyester resin composition excellent in productivity and heat resistance, and a molding method thereof. The purpose is to do.

[0006]

Means for Solving the Problems In view of the present situation, the present inventors have conducted intensive studies to solve the above problems, and as a result, have found that a high molecular weight aliphatic polyester (A) having a number average molecular weight of 10,000 to 1,000,000 is used. When the half-width of the exothermic peak based on the slow-cooling crystallization of the component (A) was measured at a slow cooling rate of 3 ° C./min. A polyester resin composition having improved moldability, characterized by blending the components (A) and (B) so as to be 15 ° C. or lower, and satisfies the formulas (1) and (2). The above object has been achieved by developing a molded article molded under the conditions.

[0007]

(Equation 4)

P: melting point (° C.) Q: exothermic peak temperature (° C.) R: mold temperature (° C.) Further, the polyester resin composition can be applied to various molding methods, and is effective in each molding method. It was found that a perfect molded product was obtained. For example, the polyester resin composition can be preferably applied to injection molding, and a method of injection-molding a polyester resin composition satisfying the above (1) under a condition satisfying the above (2) is a method for injection-molding a polyester. I also found it important to gain.

The polyester resin composition of the present invention further contains an antioxidant (C) and further has a viscosity retention index represented by the following formula (3) of 0.7 or more, preferably 0.8 or more: More preferably, by blending the high molecular weight polyester (A), the crystal nucleating agent (B) and the antioxidant (C) so as to be 0.9 or more, the heat stability at the time of molding is excellent, and , After which the molecular weight does not decrease,
In addition, a molded article having excellent molecular weight stability over time can be obtained.

[0010]

(Equation 5)

X: 190 as measured by a flow tester
° C, viscosity after 30 minutes (poise) Y: 190 ° C as measured by a flow tester, viscosity after 5 minutes (poise)

[0012]

To obtain the high molecular weight aliphatic polyester (A) used in the present invention, a) a method of polycondensing a polybasic acid (or an ester thereof) with a glycol; A method of condensation,
C) ring-opening polymerization of a cyclic acid anhydride and a cyclic ether,
D) A method of ring-opening polymerization of a cyclic ester.

Examples of the polybasic acid used in the method (a) include succinic acid, adipic acid, suberic acid, sebacic acid, azelaic acid, decanedicarboxylic acid, octadecanedicarboxylic acid, dimer acid, and esters thereof. Examples of the glycol include ethylene glycol, propylene glycol, 1,3-propanediol, 1,4-butanediol, neopentyl glycol, 1,5-pentanediol, 1,6-hexanediol, decamethylene glycol and the like. It is also possible to use polyoxyalkylene glycol as a part of the glycol component, and examples thereof include polyoxyethylene glycol, polyoxypropylene glycol, polyoxytetramethylene glycol and copolymers thereof. Among these, a combination of succinic acid and ethylene glycol and / or succinic acid and 1,4-butanediol is preferable in consideration of the melting point, biodegradability, and economy of the obtained polyester. In the production of the high molecular weight aliphatic polyester (A), the total amount of the polybasic acid (or its ester) component and the glycol component may be initially mixed and reacted, or may be added separately as the reaction proceeds. I can't tell. The polycondensation reaction can be carried out by a usual transesterification method or esterification method, or a combination of the two methods. If necessary, the degree of polymerization can be increased by increasing or decreasing the pressure in the reaction vessel.

Examples of the hydroxycarboxylic acid used in the method b) include glycolic acid, lactic acid, 3-hydroxypropionic acid, 3-hydroxy-2, 2-dimethylpropionic acid, 3-hydroxy-3-methyl-butyric acid, 4
-Hydroxybutyric acid, 5-hydroxyvaleric acid, 3-hydroxybutyric acid, 3-hydroxyvaleric acid, 4-hydroxyvaleric acid, 6-hydroxycaproic acid, citric acid, malic acid and esters thereof. As the polycondensation reaction, there is no problem by using a usual transesterification method or esterification method or a combination of both methods. If necessary, the degree of polymerization can be increased by increasing or decreasing the pressure in the reaction vessel.

The cyclic acid anhydride used in the method (c) includes, for example, succinic anhydride, maleic anhydride, itaconic anhydride, glutaric anhydride, adipic anhydride, citraconic anhydride and the like. Examples of the cyclic ether include ethylene oxide, propylene oxide, cyclohexene oxide, styrene oxide, epichlorohydrin, allyl glycidyl ether, phenyl glycidyl ether, tetrahydrofuran, oxepane, 1,3-dioxolan and the like. Among these, a combination of succinic anhydride and ethylene oxide is preferable in consideration of the melting point, biodegradability, and economic efficiency of the obtained polyester.
The ring-opening polymerization can be carried out using a known ring-opening polymerization catalyst by a method such as polymerization in a solvent or bulk polymerization.

Examples of the cyclic ester used in the method (d) include β-propiolactone and β-methyl-β-
And propiolactone, δ-valerolactone, ε-caprolactone, glycolide, lactide and the like. The ring-opening polymerization can be carried out using a known ring-opening polymerization catalyst by a method such as polymerization in a solvent or bulk polymerization.

Among the methods for obtaining such a high-molecular-weight aliphatic polyester (A), a method in which ring-opening polymerization of a cyclic acid anhydride and a cyclic ether of (c) is mentioned as a method which can be industrially and efficiently produced in a relatively short time. Is preferred. Hereinafter, the ring-opening polymerization of a cyclic acid anhydride and a cyclic ether will be described in more detail.

It has been known that cyclic acid anhydrides such as succinic anhydride used in the present invention do not homopolymerize. By cyclically adding cyclic ether in the presence of a polymerization catalyst to such a cyclic acid anhydride that is not homopolymerized and polymerizing, a polyester in which an acid component and an alcohol component are substantially copolymerized alternately can be produced in a short time. Can be generated.

The polymerization can be carried out by a method such as polymerization in a solvent or bulk polymerization. In polymerization in a solvent, the cyclic acid anhydride is used by dissolving it in a solvent. In bulk polymerization, the cyclic acid anhydride is melted before use in the present invention.

The polymerization in a solvent can be carried out batchwise or continuously, and the solvent used in this case includes, for example, benzene, toluene, xylene, cyclohexane, n
-Inert solvents such as hexane, dioxane, chloroform and dichloroethane.

The polymerization catalyst is not particularly limited, and those usually used in ring-opening polymerization of polyester are used. For example, tetramethoxy zirconium, tetraethoxy zirconium, tetra-iso-propoxy zirconium, tetra-iso-butoxy zirconium, tetra-n-butoxy zirconium, tetra-t-butoxy zirconium, triethoxy aluminum, triethoxy aluminum, tri-n-propoxy aluminum, tri- iso-propoxyaluminum, tri-n-butoxyaluminum, tri-i
So-butoxyaluminum, tri-sec-butoxyaluminum, mono-sec-butoxy-di-iso-
Propoxy aluminum, ethyl acetoacetate aluminum diisopropylate, aluminum tris (ethyl acetoacetate), tetraethoxy titanium, tetra-iso-propoxy titanium, tetra-n-propoxy titanium, tetra-n-butoxy titanium, tetra-se
c-butoxytitanium, tetra-t-butoxytitanium, tri-iso-propoxygallium, tri-iso-propoxyantimony, tri-iso-butoxyantimony, trimethoxyboron, triethoxyboron, triethoxyboron
iso-propoxyboron, tri-n-propoxyboron, tri-iso-butoxyboron, tri-n-butoxyboron, tri-sec-butoxyboron, tri-t-
Butoxyboron, tri-iso-propoxygallium,
Tetramethoxygermanium, tetraethoxygermanium, tetra-iso-propoxygermanium, tetra-n-propoxygermanium, tetra-iso-butoxygermanium, tetra-n-butoxygermanium, tetra-sec-butoxygermanium, tetra-
metal alkoxides such as t-butoxygermanium, di-iso-propoxymagnesium, di-ethoxymagnesium; antimony pentachloride, zinc chloride, magnesium chloride, ferric chloride, lithium bromide, tin (IV) chloride, cadmium chloride, Halides such as boron fluoride diethyl ether; alkyl aluminums such as trimethylaluminum, triethylaluminum, diethylaluminum chloride, ethylaluminum dichloride, tri-iso-butylaluminum; dimethylzinc;
Alkyl zinc such as diethyl zinc and diisopropyl zinc; triallylamine, triethylamine, tri-n-
Tertiary amines such as octylamine and benzyldimethylamine; heteropolyacids such as phosphotungstic acid, phosphomolybdic acid and silicotungstic acid and alkali metal salts thereof; zirconium oxychloride, zirconyl octylate;
Examples include zirconium compounds such as zirconyl stearate and zirconyl nitrate. Among them, zirconyl octylate, tetraalkoxyzirconium, and trialkoxyaluminum compounds are particularly preferable. The amount of the polymerization catalyst is not particularly limited, but is usually 0.001 to 10% by weight based on the total amount of the cyclic acid anhydride and the cyclic ether. Regarding the method of adding the polymerization catalyst, the polymerization catalyst may be added to the cyclic acid anhydride or may be added sequentially like a cyclic ether.

The polymerization temperature is not particularly limited as long as the cyclic acid anhydride reacts with the cyclic ether.
° C, preferably 50 to 150 ° C, more preferably 10 ° C.
0-150 ° C. During the reaction, the pressure in the reaction vessel varies depending on the reaction temperature, the presence or absence of a solvent, and the type of solvent.However, the increase in unreacted cyclic ether due to the increase in pressure due to the sequential addition of cyclic ether increases the amount of polyether in the reaction product. It is not preferable because the ether component is increased. Thus, pressure in the reaction vessel is preferably normal pressure ~50kgf / cm ^2, the addition of cyclic ethers such more preferably a normal pressure ~15kgf / cm ^2.

The cyclic ether is added in an amount of 3 to 9 per hour per 100 parts by weight of the cyclic anhydride.
The amount is preferably 0 parts by weight, more preferably 5 to 50 parts by weight.

If the addition rate of the cyclic ether is lower than the lower limit of 3 parts by weight, the reaction is prolonged and the productivity is lowered, which is not industrially preferable. On the other hand, if it is higher than the upper limit of 90 parts by weight, the polyether component in the reaction product increases and only a polyester having a low melting point can be obtained.

The term "sequential addition of the cyclic ether" means that the cyclic ether is not added all at once, and it may be either a method of continuously adding the cyclic ether or a method of intermittently adding it in multiple stages. It is preferable to add continuously so that the amount of addition does not largely change over time.

In the present invention, the reaction ratio of the cyclic acid anhydride and the cyclic ether is from 40/60 to 60/40 by their molar ratio.
In view of the fact that the residual cyclic acid anhydride and the terminal carboxyl group of the polyester lower the physical properties of the polyester, the ratio of 40/60 to 49/49 is preferred in order to add the cyclic ether (D) in excess. More preferably, the ratio is / 51. By doing so, 50% of the terminal carboxyl groups of the polyester
Less than a carboxyl group improves heat resistance.

If the ratio is out of this range, unreacted monomers may increase and the yield may decrease. In the present invention, it is preferable that after the sequential addition of a predetermined amount of the cyclic ether determined in consideration of the above molar ratio, polymerization is continued at the reaction temperature to ripen. The polyester formed from the polymerization system after the aging reaction may be separated.

The polyesters obtained by any of the methods a), b), c) and d) also have a number average molecular weight of 1,000.
When it is lower than 0, the molecular weight may be further increased by a transesterification reaction. It is also conceivable to increase the molecular weight with a coupling agent such as an isocyanate compound, but this is not preferable because of the occurrence of a gel-like substance due to the polyfunctional isocyanate and the toxicity of the remaining isocyanate compound.

Crystal nucleating agent (B) used in the present invention
Examples of the known compounds include the following. Inorganic compounds, for example, carbon black, calcium carbonate, synthetic silicic acid and silicate, zinc white, high cytoclay, kaolin, basic magnesium carbonate, mica, talc, quartz powder, diatomaceous earth, dolomite powder, titanium oxide ,
Zinc oxide, antimony oxide, barium sulfate, calcium sulfate, alumina, calcium silicate, boron nitride, etc .; low molecular weight organic compounds having a metal salt of a carboxyl group, for example, octylic acid, toluic acid, heptanoic acid, pelargonic acid, lauric acid Acid, myristic acid, palmitic acid, stearic acid, behenic acid, cerotic acid, montanic acid, melicic acid, benzoic acid, p-tert-butylbenzoic acid,
Metal salts such as terephthalic acid, terephthalic acid monomethyl ester, isophthalic acid and isophthalic acid monomethyl ester; high molecular weight organic compounds having a carboxyl group or metal salts thereof, for example, carboxyl group-containing polyethylene and polypropylene obtained by oxidation of polyethylene; Carboxyl group-containing polypropylene obtained by oxidation, copolymers of olefins such as ethylene, propylene, butene-1 and acrylic acid or methacrylic acid, copolymers of styrene and acrylic acid or methacrylic acid, olefins and maleic anhydride Copolymers with acid, copolymers of styrene with maleic anhydride, etc .; high molecular organic compounds, for example, 3,3-dimethylbutene-1, 3-methylbutene-1, 3-methylpentene-1,3 -Methylhexene-1,3,5 -3-position branched α-olefins having 5 or more carbon atoms such as -trimethylhexene-1, polymers of vinylcycloalkanes such as vinylcyclopentane, vinylcyclohexane and vinylnorbornane; polyalkylene glycols such as polyethylene glycol and polypropylene glycol; Glycolic acid, polyethylene terephthalate, polybutylene terephthalate, polytranscyclohexanedimethanol terephthalate,
Cellulose, cellulose esters, cellulose ethers and the like; phosphoric acid or phosphorous acid and metal salts thereof, for example,
Diphenyl phosphate, diphenyl phosphite, bis (4-tert-butylphenyl) sodium phosphate, methylene (2,4-tert-butylphenyl) sodium phosphate, etc .; bis (p-methylbenzylidene) sorbitol, bis (p Sorbitol derivatives such as -ethylbenzylidene) sorbitol; thioglycolic anhydride, paratoluenesulfonic acid and metal salts thereof. Among these, compounds other than the polymer compound having an aromatic ring in the main chain are preferable from the viewpoint of crystallization speed and biodegradability. Further, since a higher crystallization rate is required for molding, the following nucleating agents are preferable among these nucleating agents. Inorganic compounds, low molecular weight organic compounds having a carboxyl group and metal salts thereof, combinations of inorganic compounds and low molecular weight organic compounds having a carboxyl group and metal salts thereof, high molecular weight organic compounds having a carboxyl group or metal salts thereof, carboxyl Combination of a high molecular weight organic compound having a group or a metal salt thereof with a low molecular weight organic compound having a carboxyl group and a metal salt thereof. Further, among inorganic compounds, talc, mica and boron nitride are preferable, and among low molecular weight organic compounds having a carboxyl group and metal salts thereof, stearic acid is preferable.

The amount of the crystal nucleating agent (B) added is preferably 0.00 to 100 parts by weight of the high molecular weight aliphatic polyester (A).
It is preferably in the range of 01 to 10 parts by weight, more preferably in the range of 0.0001 to 5 parts by weight, and still more preferably in the range of 0.5 to 5 parts by weight. If the amount is less than 0.0001 part by weight, it is difficult to obtain the desired effect, and if the amount exceeds 10 parts by weight, the effect corresponding to the amount cannot be expected, which is not only practical but also uneconomical. However, neither case is preferable.

As the crystal nucleating agent (B), those having an average particle size of 50 μm or less are used, and those having an average particle size of 10 μm or less are preferable from the viewpoint of the appearance of the molded article.

Antioxidant (C) used in the present invention
Examples thereof include phenol-based antioxidants, sulfur-based antioxidants, and phosphorus-based antioxidants, and include the following from known compounds.

Examples of the phenolic antioxidant include the following compounds: 2,4-bis- (n-octylthio) -6- (4-hydroxy-3,
5-t-butylanilino) -1,3,5-triazine,
Pentaerythrityl-tetrakis [3- (3,5-di-
t-butyl-4-hydroxyphenyl) propionate] (trade name: IRGANOX 1010), 2,2-thio-diethylenebis [3- (3,5-di-t-butyl-
4-hydroxyphenyl) propionate], 3,9-
Bis- [2- (3- (3-tert-butyl-4-hydroxy-5-methylphenyl) -propionyloxy) -1,
1-dimethylethyl] 2,4,8,10-tetraoxaspiro [5,5] undecane (trade name Sumiliz
er GA-80), triethylene glycol-bis [3- (3-tbutyl-5-methyl-4-hydroxyphenyl) propionate] (trade name: IRGANOX 2
45), 1,6-hexanediol-bis [3- (3,
5-di-t-butyl-4-hydroxyphenyl) propionate] (trade name: IRGANOX 259), tetrakis [methylene (3,5-di-t-butyl-4-hydroxyhydrocinnamate)] methane, octadecyl-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate (trade name: IRGANOX 107
6), 3,5-di-t-butyl-4-hydroxy-benzylphosphonate-diethyl ester (trade name I
RGANOX 1222), N, N'-hexamethylene-bis (3,5-di-t-butyl-4-hydroxy-hydrocinnamamide), 3,5-di-t-butyl-4-
Hydroxy-benzylphosphonate-diethyl ester, 1,3,5-trimethyl-2,4,6, -tris- (3,5-di-t-butyl-4-hydroxybenzyl) benzene, bis (3,5 -Ethyl t-butyl-4-hydroxybenzylphosphonate) calcium (trade name)
IRGANOX 1425WL), Tris- (3,5-
Di-t-butyl-4-hydroxybenzyl) -isocyanurate (trade name IRGANOX 3114), 1,
1,3-tris (2-methyl-4-hydroxy-5-t
-Butylphenyl) butane, 2,2-bis [4- (2-
(3,5-di-t-butyl-4-hydroxyhydrocinnamoyloxy)) ethoxyphenyl] propane,
2,6-di-t-butyl-4-methylphenol and the like.

The sulfur-based antioxidants include, for example, the following compounds: dilauryl-3,3
-Thiodipropionate (trade name: SUMILIZER)
TPL-R), dimyristyl-3,3-thiodipropionate (trade name SUMILIZER TPM), distearyl-3,3-thiodipropionate (trade name S
UMILIZER TPS), pentaerythrityl tetrakis (3-lauryl thiodipropionate (trade name)
SUMILIZER TP-D), ditridecyl-3,
3-thiodipropionate (trade name: SUMILIZE
RTL), 2-mercaptobenzimidazole (trade name SUMILIZER MB) and the like.

Examples of the phosphorus antioxidant include the following compounds: triphenyl phosphite, trilauryl phosphite, tris (nonylphenyl) phosphite, triisooctyl phosphite, triisodecyl Phosphite, triphenyl phosphite, diphenyl isodecyl phosphite, diphenyl isooctyl phosphite, phenyl isodecyl phosphite, diisooctyl phenyl phosphite, tetrakis (2,4-di-t-butylphenyl) -4,4 −
Biphenylene phosphonite (trade name: IRGAFO
SP-EPQFF), tris (2,4-di-t-butylphenyl) phosphite (trade name: IRGAFOS
168), distearylpentaerythritol-di-phosphite, dioctylpentaerythritol-di-phosphite, diisodecylpentaerythritol-di-phosphite, bis (2,4-di-t-butylphenyl) pentaerythritol-di-phosphite Phyto, bis (2,6-di-t-butyl-4-methylphenyl) pentaerythritol-di-phosphite (trade name ADK STAB PE
Hypophosphorous acid, phosphorous acid and esters thereof such as P-36), tetrakis (2,4-di-t-butylphenyl) -4,4′-biphenylenephosphonite (trade name SANDOSTAB P-EPQ) Diphenyl phosphate, 2-ethylhexyl diphenyl phosphate, dibenzyl phosphate, triethyl phosphate, trimethyl phosphate, trioctyl phosphate, tricresyl phosphate, tris phosphate (4
Phosphoric acid and its esters such as -ter-butylphenyl), tris (butoxyethyl) phosphate and tri-n-butylphosphate; hypophosphorous acid, polyphosphoric acid and the like.

The above antioxidants can be used alone or in combination of two or more.

The antioxidant is used in an amount of 0.01 to 2.00 per 100 parts by weight of the high molecular weight aliphatic polyester (A).
Parts by weight, preferably 0.05 to 1.00 parts by weight. When the content of the antioxidant is less than 0.05 parts by weight, the effect of stabilizing the polyester by heat cannot be obtained. Conversely, when the content of the antioxidant exceeds 1.00 parts by weight, the above stabilizing effect can be obtained, but the effect in proportion to the content cannot be obtained, and the physical properties such as mechanical strength are reduced. I do.

The method for producing the composition of the present invention includes a method of kneading the nucleating agent (B) and the antioxidant (C) when producing the high-molecular-weight aliphatic polyester (A). ) A method of kneading after production is applicable.

The composition of the present invention may contain, if necessary, other components such as pigments, dyes, weathering agents, lubricants, antistatic agents, stabilizers, fillers, reinforcing materials, flame retardants, plasticizers, and other heavy metals. Coalescence can be added within a range that does not impair the effects of the present invention.

The composition of the present invention is prepared by dispersing the component (B) in the component (A) by an arbitrary method and complexing the composition. The composition of the present invention is measured by slow cooling crystallization by DSC. The half width of the exothermic peak in the crystallization temperature range of the high molecular weight aliphatic polyester (A) is 15 ° C. or less, preferably 10 ° C. under the measurement conditions of the cooling rate of 3 ° C./min.
It must be formulated so that:

The DSC can be measured by a conventional method using a commercially available device such as SSC5200 manufactured by Seiko Denshi Kogyo. For example, sample 2 in a nitrogen atmosphere
0 mg is heated above the melting point of the high molecular weight aliphatic polyester (A) and completely melted, and then cooled at a predetermined rate.
This is performed by recording the exothermic peak accompanying crystallization. When the DSC measurement is performed on the high molecular weight aliphatic polyester (A) in this manner, an exothermic peak due to crystallization appears in a range of 10 to 200 ° C. at a cooling rate of 3 ° C./min. However, this exothermic peak is usually extremely wide, and when the nucleating agent (B) is not added, the half width of the peak is usually about 25 ° C., and even when it is small, it is about 15 ° C.

When the cooling rate is further increased, the exothermic peak due to crystallization shifts further to the lower temperature side, while the half-width of this peak further widens.

The high molecular weight aliphatic polyester (A) having a wide half-width of an exothermic peak based on such slow cooling crystallization has a slow crystallization, and a good molded product cannot be obtained.

On the other hand, in the composition of the present invention,
The exothermic peak due to crystallization in the cooling process of the DSC measurement often shifts to a higher temperature side at a cooling rate of 3 ° C./min, and becomes an extremely sharp exothermic peak. And, in order to perform molding efficiently, the half width of this peak is at least 15 ° C. or less, preferably 10 ° C.
Or less, more preferably 8 ° C. or less, and even more preferably 7 ° C. or less. In particular, when the half width is 7 ° C. or less, excellent moldability is exhibited.

According to the present invention, a molded article with improved moldability is obtained only by molding the polyester resin composition under molding conditions satisfying the following formulas (1) and (2). It became possible.

[0046]

(Equation 6)

P: melting point (° C.) Q: exothermic peak temperature (° C.) R: mold temperature (° C.) S: molding temperature (° C.) When the mold temperature is higher than the temperature satisfying the formula (1), high molecular weight fat The molecular motion of the aromatic polyester (A) becomes active, and it takes time for crystallization. On the other hand, when the mold temperature is lower than the temperature that satisfies the formula (1), the molecular motion of the high molecular weight aliphatic polyester (A) becomes slow, and the crystallization also takes time. In any of these cases, it takes a considerable time to remove the molded body from the mold during the molding process, and the molding cycle, which is a characteristic of molding, is impaired, resulting in poor production efficiency.

When the molding temperature is higher than the temperature which satisfies the formula (2), it is necessary to reach the optimum temperature for crystallizing the high molecular weight aliphatic polyester (A) supplied or injected into the mold. It takes time and crystallization takes time. When it is low, the high molecular weight aliphatic polyester (A) is not sufficiently plasticized or undissolved, and a satisfactory molded product cannot be obtained.

The present inventors have found that efficient molding can be achieved only by molding a specific resin composition under molding conditions that satisfy the specific conditions (1) and (2).

The composition of the present invention further comprises an antioxidant (C)
The component is prepared by dispersing the components in the high molecular weight polyester (A) component and the nucleating agent (B) component by an arbitrary method to form a composite, and the composition of the present invention is represented by the formula (3). The high molecular weight polyester (A) component, the crystal nucleating agent (B) component and the antioxidant (C) are mixed so that the viscosity retention index becomes 0.7 or more, preferably 0.8 or more, and more preferably 0.9 or more. Must be blended.

[0051]

(Equation 7)

X: 190 as measured by a flow tester
C., viscosity after 30 minutes (poise) Y: 190 ° C. as measured by a flow tester, viscosity after 5 minutes (poise) If the viscosity retention index is less than 0.7, the thermal stability during molding is poor. The molecular weight after molding is lower than before molding, and physical properties such as strength are deteriorated. Further, when the viscosity retention index is less than 0.7 even after the molding process, the stability with time is low, and the physical properties such as strength deteriorate with time, so that it cannot be used for an injection molded product.

The viscosity retention index was measured by attaching a die (nozzle diameter: 1.00 mm, nozzle length: 10.0 mm) to a commercially available flow tester (CFT-500C, manufactured by Shimadzu Corporation) at 190 ° C. under a test load of 10 kgf. Performed in air.
The sample used for the test was a pellet at 80 ° C.
It dried under reduced pressure (20-50 mmHg) for 10 hours. The measurement procedure was as follows: a flow tester at 190 ° C. was filled with 2-3 g of pellets immediately after drying, and the viscosity (poise) was measured 5 minutes after the start of filling (Y). Further, 2-3 g of pellets immediately after drying were refilled again by the same procedure, and the viscosity (poise) 30 minutes after the start of the charging was measured (X).

In the case of the composition of the present invention, the crystallization rate or the crystallization rate and the heat resistance are improved and the moldability is good, so that a molded article can be obtained. The molded article of the polyester resin composition of the present application had a high flexural strength retention as shown by the following formula (4), and exhibited excellent strength characteristics. Preferably, this retention is at least 80%. More preferably, it is 90% or more.

[0055]

(Equation 8)

V: Bending strength (kgf / cm ² ) after 28 days in the bending test of the formed body W: Initial bending strength (kgf / cm ² ) in the bending test of the formed body As a forming method which can be used in the present invention. Is not particularly limited as long as the polyester resin composition is molded in a mold. For example, compression molding, transfer molding, injection molding, blow molding, vacuum molding, air pressure molding and the like can be mentioned.

[0057]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, but it should not be construed that the invention is limited thereto. The parts in the examples represent parts by weight. The evaluation methods performed in the examples are as follows. Table 1 summarizes the results
It was shown to.

(Molecular Weight) The number average molecular weight in terms of polystyrene was measured using a gel permeation chromatograph.

(Melting point) Measured by DSC.

(Bending Test) A bending test was performed according to JIS K-7203.

(Stability over time) A test piece obtained by molding in accordance with JIS K-7203 was tested at 23 ° C. and a relative humidity of 65.
% In a constant temperature / humidity room for 1 day, separately from this, 50 ° C., 28 days in the air, 23 ° C., relative humidity 6
What was left in a 5% constant temperature / humidity room for 1 day is 28 days later,
Each was subjected to a bending test.

By substituting these values into equation (4), the bending strength retention (%) of the molded body was determined.

[0063]

(Equation 9)

V: Bending strength (kgf / cm ² ) after 28 days in the bending test of the molded body W: Initial bending strength (kgf / cm ² ) in the bending test of the molded body (Biodegradability test) 130 ° C., 150 kg A film having a thickness of 200 μm is prepared by a compression molding machine under the conditions of 2 cm / cm ² and 2 minutes, the obtained film is buried in a planter charged with soil, and water is sprayed once a day at 23 ° C., relative humidity. 65%
Was kept in a constant temperature and humidity room, and the appearance change after 100 days was observed.

The soil used was one collected from Onohara, Minoh-shi and Nishiburi-cho, Suita-shi, and one obtained by mixing humus in a ratio of 3: 1: 3.

The results are described as follows.

(+): Change in appearance was observed.

(-): No change in appearance was observed.

Example 1 An autoclave was charged with 500.0 parts of distilled and purified succinic anhydride and 3.68 parts of zirconyl octylate, followed by purging with nitrogen. Then, the temperature of the autoclave was gradually raised to 130 ° C. with stirring to melt the succinic anhydride. At the same temperature, while maintaining the pressure in the autoclave at 4.0 to 6.5 kgf / cm ² , ethylene oxide 231.1 was added. Parts at an addition rate of 58 parts per hour to 4.0 parts.
Introduced continuously over time. After the ethylene oxide was introduced, an aging reaction was performed at 130 ° C. for 1.0 hour, and then the system was returned to room temperature to obtain a polymerization product. The number average molecular weight by GPC measurement was 36000, and the melting point by DSC was 10
3.4 ° C.

12.0 parts of the obtained polymerization product and 0.48 part of talc were charged with a thermometer, a stirrer, and a nitrogen inlet tube.
After adding to a 0 ml separable flask and performing nitrogen substitution three times, a vacuum pump equipped with a trap immersed in dry ice-methanol in a nitrogen stream was used for 0.9 to 0.9.
Under a reduced pressure of 1.1 mmHg and a temperature of 240 ° C., 1.5
Allowed to react for hours. The obtained product was treated with pentaerythrityl-tetrakis [3- (3,5-di-t-
Butyl-4-hydroxyphenyl) propionate]
0.5% by weight (trade name IRGANOX 1010)
Lithium stearate was kneaded with a twin-screw extruder to a concentration of 0.5% by weight to obtain a polyester resin composition (1). The number average molecular weight measured by GPC was 69000. When the melting point, the exothermic peak temperature based on crystallization, and the half width of the exothermic peak were determined by DSC measurement, they were 92.7 ° C., 51.9 ° C., and 6.1 ° C., respectively. FIG. 1 shows the DSC chart.

The polyester resin composition (1) was molded at a molding temperature of 135 ° C. and a mold temperature of 20 ° C. using an injection molding machine SG25 type manufactured by Sumitomo Heavy Industries, Ltd. The molded body could be taken out with a cooling time of 20 seconds in a mold.

The bending strength of the obtained molded body was 380 (kgf
/ cm ² ) and the flexural modulus was 7,500 (kgf / cm ² ).

Example 2 A three-necked flask equipped with a stirrer, a Wiggrew fractionating tube equipped with a trap immersed in dry ice-methanol at the outlet, and a gas inlet tube was charged with 519.6 parts of succinic acid and ethylene glycol. 286.8 parts and 0.0772 parts of titanium tetraisopropoxide were added and immersed in an oil bath. The temperature of the oil bath was raised, nitrogen was slowly flowed, the temperature was 182 to 200 ° C., and the normal pressure was 3.0.
Water generated in 7 hours at a reduced pressure of mmHg and excess ethylene glycol were distilled off to obtain a polyester having a number average molecular weight of 9700. Subsequently, at a temperature of 200 to 223 ° C;
Ethylene glycol produced at a reduced pressure of 0 mmHg for 3 hours and 15 minutes was distilled off to obtain a polyester having a number average molecular weight of 19,200. Then, the obtained polyester 50.7
Eight parts were added to a 50 ml separable flask equipped with a thermometer, a stirrer, and a nitrogen inlet tube, and after purging with nitrogen three times, a vacuum pump equipped with a trap immersed in dry ice-methanol in a nitrogen stream. 0.9 to 1.5
The reaction was carried out under a reduced pressure of mmHg at a temperature of 220 ° C. for 4.5 hours. The obtained product was treated with pentaerythrityl-tetrakis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate] (trade name)
IRGANOX 1010) 0.5% by weight, mannitol 5% by weight, lithium stearate 0.5% by weight
The resulting mixture was kneaded with a twin-screw extruder to obtain a polyester resin composition (2). Number average molecular weight by GPC measurement is 6
5000. The melting point, the exothermic peak temperature based on crystallization, and the half width of the exothermic peak determined by DSC were 95.3 ° C., 55.4 ° C., and 4.8 ° C., respectively.
Met.

The polyester resin composition (2) was molded at a molding temperature of 135 ° C. and a mold temperature of 20 ° C. using an SG25 type injection molding machine manufactured by Sumitomo Heavy Industries, Ltd. The molded body could be taken out with a cooling time of 18 seconds in a mold.

The bending strength of the obtained molded body was 370 (kgf
/ cm ² ) and the flexural modulus was 7300 (kgf / cm ² ).

Example 3 An autoclave was charged with 500.0 parts of distilled and purified succinic anhydride and 3.68 parts of zirconyl octylate, followed by purging with nitrogen. Then, the temperature of the autoclave was gradually raised to 130 ° C. with stirring to melt the succinic anhydride. At the same temperature, while maintaining the pressure in the autoclave at 4.0 to 6.5 kgf / cm ² , ethylene oxide 231.1 was added. Parts at an addition rate of 58 parts per hour to 4.0 parts.
Introduced continuously over time. After the ethylene oxide was introduced, an aging reaction was performed at 130 ° C. for 1.0 hour, and then the system was returned to room temperature to obtain a polymerization product. The number average molecular weight by GPC measurement was 36000, and the melting point by DSC was 10
3.4 ° C.

[0077] 12.0 parts of the obtained polymerization product was measured with a thermometer.
The mixture was added to a 50-ml separable flask equipped with a stirrer and a nitrogen inlet tube, and after purging with nitrogen three times,
The reaction was carried out in a nitrogen stream at a temperature of 240 ° C. for 1.5 hours under a reduced pressure of 0.9 to 1.1 mmHg by a vacuum pump equipped with a trap immersed in dry ice-methanol. The resulting product was treated with 3,5-di-t-butyl-
4-hydroxy-benzylphosphonate-diethyl ester (trade name: IRGANOX 1222)
5% by weight, 1% by weight of cellulose and 0.1% of stearic acid.
The mixture was kneaded with a twin-screw extruder to a concentration of 5% by weight to obtain a polyester resin composition (3). The number average molecular weight measured by GPC was 62,000. The melting point, the exothermic peak temperature based on crystallization, and the half-width of the exothermic peak were determined by DSC.
7.7 ° C.

The polyester resin composition (3) was molded at a molding temperature of 155 ° C. and a mold temperature of 23 ° C. using an injection molding machine SG25 type manufactured by Sumitomo Heavy Industries, Ltd. The molded body could be taken out with a cooling time of 25 seconds in a mold.

The bending strength of the obtained molded body was 350 (kgf
/ cm ² ) and the flexural modulus was 7600 (kgf / cm ² ).

(Example 4) 3,5-Di-t- of Example 3
Butyl-4-hydroxy-benzylphosphonate-
Diethyl ester (trade name: IRGANOX 122
2) is 3,9-bis- [2- (3- (3-t-butyl-
4-hydroxy-5-methylphenyl) -propionyloxy) -1,1-dimethylethyl] 2,4,8,10
-Tetraoxaspiro [5,5] undecane (trade name
Sumilizer GA-80) 0.2% by weight and tetrakis (2,4-di-t-butylphenyl) -4,4-
Biphenylene phosphonite (trade name: IRGAFO
(SP-EPQFF) A polyester resin composition (4) was obtained in the same manner as in Example 3, except that 0.2% by weight of cellulose and 1% by weight of stearic acid were changed to 1% by weight of polyethylene terephthalate. Was. .

The number average molecular weight measured by GPC was 6,400.
It was 0. According to DSC measurement, the melting point, the exothermic peak temperature based on crystallization, and the half width of the exothermic peak were 94.8 ° C., 45.4 ° C., and 12.5 ° C., respectively.

The polyester resin composition (4) was molded at a molding temperature of 135 ° C. and a mold temperature of 20 ° C. using an SG25 type injection molding machine manufactured by Sumitomo Heavy Industries, Ltd. The molded body could be taken out with a cooling time of 1 minute and 20 seconds in a mold.

The bending strength of the obtained compact was 310 (kgf
/ cm ² ) and the flexural modulus was 7100 (kgf / cm ² ).

Comparative Example 1 A comparative polyester resin composition (1) was obtained in the same manner as in Example 1 except that talc and lithium stearate were not added. The number average molecular weight measured by GPC was 69000. The melting point, the exothermic peak temperature based on crystallization, and the half-width of the exothermic peak determined by DSC were 96.5, respectively.
C, 40.5C, and 26.1C.

The comparative polyester resin composition (1) was molded at a molding temperature of 135 ° C. and a mold temperature of 23 ° C. using an injection molding machine SG25 type manufactured by Sumitomo Heavy Industries, Ltd. The molded product could be taken out only with a cooling time of 3 minutes and 10 seconds in a mold.

Comparative Example 2 The polyester resin composition (1) of Example 1 was used with an injection molding machine SG manufactured by Sumitomo Heavy Industries, Ltd.
Molding was performed using a mold 25 at a molding temperature of 135 ° C and a mold temperature of 0 ° C. The molded product could be taken out only with a cooling time of 1 minute and 30 seconds in a mold.

Comparative Example 3 The pentaerythrityl-tetrakis [3- (3,5-di-tert-butyl-4-) of Example 1
(Hydroxyphenyl) propionate] (trade name IR
A comparative polyester resin composition (2) was obtained in the same manner as in Example 1 except that GANOX 1010) was not added.
The molded body could be removed from the mold in 20 seconds as in Example 1, but the viscosity retention number of the obtained molded body was 0.69, which is considerably lower than 0.81 of Example 1. Was.
The bending strength retention of the molded product was 9% in Example 1.
It was 71.1 (%) lower than 2.1%, and only a molded article having low heat resistance was obtained.

[0088]

[Table 1]

[0089]

[Table 2]

[0090]

The molded article of the present invention has excellent moldability, good heat resistance, and excellent biodegradability. Therefore,
The molded article obtained by the present invention can be effectively used for disposable daily necessities and the like.

[Brief description of the drawings]

FIG. 1 is a DSC chart in Example 1.

Claims (7)

[Claims] 1. A number average molecular weight of 10,000 to 100,000
0 high molecular weight aliphatic polyester (A) and a crystal nucleating agent (B), and the half width of an exothermic peak based on the slow cooling crystallization of the component (A) in the differential scanning calorimeter measurement is gradually cooled at 3 ° C./min. A polyester resin composition having improved moldability, characterized in that the component (A) and the component (B) are blended so that the half-value width is 15 ° C. or less when measured at a speed. A molded article formed under conditions satisfying the formulas (1) and (2). (Equation 1) P: melting point (° C) Q: exothermic peak temperature (° C) R: mold temperature (° C) S: molding temperature (° C) 2. The polyester resin composition according to claim 1, further comprising an antioxidant (C), wherein the viscosity retention index represented by the formula (3) is 0.7 or more. A molded article containing a polyester resin composition having improved moldability, characterized by blending the component (A) and the component (C) such that (Equation 2) X: viscosity at 190 ° C. after 30 minutes (poise) measured by a flow tester Y: viscosity at 190 ° C. after 5 minutes measured by a flow tester (poise) 3. A molded product obtained by molding the polyester resin composition according to claim 1 or 2, wherein the molded product has a bending strength retention of 80% or more represented by the following formula (4). Molded body. (Equation 3) V: Bending strength (kgf / cm) after 28 days in the bending test of the molded body
² ) W: Initial bending strength (kgf / cm ² ) in the bending test of the molded body 4. The high molecular weight aliphatic polyester (A)
The molded product according to any one of claims 1 to 3, wherein the molded product is obtained from an aliphatic dicarboxylic acid component having 2 to 6 carbon atoms and an aliphatic glycol component having 2 to 4 carbon atoms. 5. The high molecular weight aliphatic polyester (A)
The molded article according to any one of claims 1 to 4, wherein the molded article does not contain an isocyanate bond. 6. The high molecular weight aliphatic polyester (A)
Is obtained by ring-opening copolymerization of a cyclic acid anhydride (D) containing succinic anhydride as a main component and a cyclic ether (E) containing ethylene oxide as a main component. Or the molded article according to claim 1. 7. The molded article according to claim 1, wherein the molding is performed by injection molding.