JPH07166038A - Polyester resin composition - Google Patents

Abstract

PURPOSE:To obtain a polyester resin compsn. which exhibits an improved crystallization rate during molding, can be molded at a high cycle, and is excellent in stiffness and toughness. CONSTITUTION:This compsn. is obtd. by adding 0.01-5 pts.wt. at least one aliph. ester of a 12C or higher fatty acid to 100 pts.wt. polyester resin which has an increase in enthalpy on melting of 10J/g or higher and an intrinsic viscosity of 0.70-1.05 and is produced from an acid component mainly comprising terephthtalic acid or its lower alcohol ester and a diol component mainly comprising 1,4-butanediol by solidifying a polyester having an intrinsic viscosity of 0.70 or lower and formed by liq.-phase polycondensation and then subjecting the polyester to solid-phase polycondensation in an inert atmosphere or under a reduced pressure.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a polyester resin composition having excellent mechanical properties and molding processability.
More specifically, the present invention relates to a polyester resin composition that has an improved crystallization rate during molding, enables higher cycle molding, and has excellent rigidity and toughness.

[0002]

2. Description of the Related Art Polybutylene terephthalate (hereinafter abbreviated as PBT) has excellent mechanical properties and moldability in the field of industrial plastics such as automobile parts, electric equipment parts and machine parts. Widely used for. Although PBT has a crystallization rate sufficient for injection molding by itself, higher cycle may be desired. When molding is performed in a relatively low temperature mold for high cycle molding, there is a problem that the original rigidity of PBT cannot be obtained because the crystallization speed is insufficient. A conventional solution to this problem is to add an inorganic filler to increase the crystallization speed and the rigidity, but on the other hand, the toughness is significantly reduced. Further, addition of the crystal nucleating agent has a problem that the toughness is lowered and the cost is increased. In order to solve such a problem, the inventors of the present invention proceeded with the examination and found that the Japanese Patent Application No.
No. 204014, a method for producing a polyester having an improved crystallization rate was proposed. According to this method, a polyester having an improved crystallization rate can be obtained. However, further investigations have revealed that the crystallization rate may still be insufficient depending on the application, and the dispersion of physical properties may become large. It has been found. On the other hand, when the molding is made to have a high cycle, a problem of mold release failure often occurs, and it is necessary to add a mold release agent that has an advantageous effect on the crystallization rate and exhibits excellent mold release performance. Paraffin wax, fatty acid amide, etc. are known as a release agent. A polyester resin containing such a release agent improves the release performance, but the release agent at the time of preliminary drying before molding. It cannot be used for high cycle molding because it has a problem that pellets do not bite properly during molding that may be caused by leaching or slip on the screw occurs and stable molding cannot be performed for a long time. . In addition, in recent years, in order to reduce the manufacturing cost of molded products, the opportunity to recycle the molding waste is increasing, and the bite failure at that time is further aggravated, and some problems are desired to be solved. Is slightly inadequate due to the addition of metal soaps to the pellet surface, etc., but it is still insufficient, and the addition work is complicated, environmental problems in the molding factory, corrosion of metal plates, etc. There's a problem.

[0003]

In view of the above problems, the inventors of the present invention have a high crystallization rate, high rigidity, excellent toughness, and good releasability even when performing high cycle molding in a low temperature mold.
As a result of intensive studies to obtain a high-cycle moldable polyester resin with excellent metering stability, a specific liquid phase polycondensed polyester was solid-phase polymerized under specific conditions to identify a polyester resin with an accelerated crystallization rate. It was found that it is effective to add the ester compound of 1) and, if necessary, further add a trace amount of the crystallization nucleating agent, and have completed the present invention. That is, the present invention comprises an acid component mainly composed of terephthalic acid or a lower alcohol ester thereof and 1,4-
Consisting of butanediol-based diol components,
After solidifying liquid-phase polycondensed polyester with an intrinsic viscosity of 0.70 or less, solid-phase polymerize it in an inert gas stream or under reduced pressure to increase the crystal melting enthalpy of the manufactured chip to 10 J / g or more, 100 parts by weight of a polyester resin (a) having a viscosity of 0.70 or more and 1.05 or less, and one or two fatty acid ester compounds containing a fatty acid having 12 or more carbon atoms as a constituent.
It is a polyester resin composition comprising 0.01 to 5 parts by weight of seeds or more (b), and 0.01 to 1.0 parts by weight of a crystallization nucleating agent (c) if necessary.

Hereinafter, the resin composition of the present invention will be described in detail. The polyester used in the present invention comprises a lower alcohol ester such as terephthalic acid or its dimethyl ester as a main constituent acid component and a main constituent alcohol component.
A PBT and its copolymer obtained by using 1,4-butanediol. When preparing a copolymerized PBT,
As acid constituent comonomer, 4,4′-biphenyldicarboxylic acid, which is an acid constituent other than the main constituent acid constituent, 2,6-
One of conventionally known difunctional carboxylic acids such as naphthalenedicarboxylic acid, 2,7-naphthalenedicarboxylic acid, diphenic acid, adipic acid, sebacic acid, 1,4-cyclohexanedicarboxylic acid and their dimethyl esters or lower alcohol esters thereof. Alternatively, two or more kinds can be used. The diol constituent comonomer is a diol component other than the main constituent diol components such as ethylene glycol, diethylene glycol, triethylene glycol, 1,3-propanediol, 1,5-pentanediol, neopentyl glycol, 1,6- Hexanediol, 1,10-decanediol, 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol, p
-Xylidene glycol, alkylene oxide adduct of hydroquinone, alkylene oxide adduct of 2,2-bis (4-hydroxyphenyl) propane, bis (4-
It is possible to use one or more conventionally known bifunctional diols such as an alkylene oxide adduct of hydroxyphenyl) sulfone and an alkylene oxide adduct of 2,6-dihydroxynaphthalene. Further, a halogen-substituted product of the above substances may be used as a comonomer for imparting flame retardancy. The amount of these copolymerization components introduced is
Preferably 20 mol% based on all constituent repeating ester units
It is below, and particularly preferably 15 mol% or below. The amount of the introduced copolymerization component is 20 for all repeating ester units.
When it exceeds the mol%, the crystallization rate and the mechanical strength remarkably decrease, which is not preferable. In addition, trifunctional or more polyfunctional compounds such as trimethyl trimesate, trimethyl trimellitate, trimethylolpropane, and pentaerythritol, stearyl alcohol, monofunctional compounds such as methyl o-benzoylbenzoate and monoepoxy compounds, p-
It is also possible to use a small amount of a hydroxycarboxylic acid derivative such as hydroxyethoxybenzenecarboxylic acid ester, a polyalkylene glycol such as polypropylene glycol or polytetrahydrofuran, or to use in combination with the above copolymerization component.

The esterification reaction using terephthalic acid and 1,4-butanediol as a main raw material is carried out at a ratio of 1 to 5 mol of 1,4-butanediol to 1 mol of terephthalic acid at a normal pressure or a pressure of 190 to. It is carried out at a temperature of 250 ° C while continuously removing water produced.

As a catalyst for obtaining a practical reaction rate, titanium compounds, tin compounds, lead compounds, zinc compounds,
Examples of the manganese compound include organic titanate compounds, titanium tetrachloride compounds, and hydrolyzates or alcoholysis products thereof, tin oxide compounds, tin acetate compounds, and organic tin compounds. More specifically, tetrabutyl titanate, tetrapropyl titanate, tetraethyl titanate, tetramethyl titanate and hydrolysates thereof, hydrolysates such as titanium tetrachloride and titanium sulfate, potassium titanium fluoride, zinc zinc fluoride, cobalt titanium fluoride. Inorganic titanium compounds, such as
Titanium compounds conventionally known as polyester production catalysts such as titanium oxalate and potassium potassium oxalate, and / or
As a polyester production catalyst for dibutyltin oxide, dibutyltin acetate, dioctyltin diacetate, diphenyltin dilauryl mercaptide, polydibutyltin sebacate, dibutyltin ethylene glycolate, dioctyltin thiosalicylate, diphenyltin benzenesulfonate, dimethyltin-p-toluenesulfonate, etc. Conventionally known tin compounds can be mentioned. Particularly preferred are tetrabutyl titanate, tetrapropyl titanate, hydrolyzate of titanium tetrachloride, dibutyltin oxide, dibutyltin acetate, dioctyltin diacetate and the like. If necessary, the addition of these catalysts can be divided into several times during the reaction. The esterification reaction using terephthalic acid and 1,4-butanediol as the main raw materials
It is carried out at a temperature of 190 to 250 ° C. under normal pressure or pressure at a ratio of 1 to 5 mol of 1,4-butanediol and while continuously removing water. At this time, it is often convenient to carry out in the presence of the above-mentioned titanium compound or tin compound.

In the liquid phase polycondensation reaction, the product obtained by the above transesterification reaction or esterification reaction is 180 to 26
The reaction system is depressurized at 0 ° C., and excess 1,4-butanediol and by-products are continuously removed, and melt polymerization is carried out until a specific degree of polymerization (intrinsic viscosity) is obtained. As a catalyst for obtaining a practical reaction rate in such a melt polycondensation reaction, a compound used in the above transesterification reaction or esterification reaction can be used as it is, and in order to improve the rate of the condensation reaction. It is also possible to add one or more of these before the start of the condensation reaction.
Further, it is also possible to add a phosphorus compound and / or an alkaline compound or the like in the monomer preparation step or the melt polycondensation step, and particularly when an appropriate amount of the phosphorus compound is used, the crystallization rate and the mechanical strength in the present invention. Can be efficiently increased. Typical phosphorus compounds here include triphenyl phosphite, tridodecyl phosphite, tridecyl phosphite, trioctyl phosphite, tripropyl phosphite, triethyl phosphite, diphenyl decyl phosphite, tris (2,4- Di-t-butylphenyl) phosphite, tris (4-octylphenyl) phosphite, tris (4- (1-phenylethylphenyl)) phosphite, tetrakis (2,4-di-t-butylphenyl) -4 ,
4'-bisphenylene phosphonite, 3,5-dibutyl-4-hydroxybenzylphosphonate diethyl ester, triphenylphosphine, tridodecylphosphine, tridecylphosphine, trioctylphosphine, tripropylphosphine, Examples thereof include tetraalkylphosphonium halides and tetraalkylphosphonium sulfonate compounds.

The liquid phase polycondensation PBT prepolymer under the above conditions has an intrinsic viscosity at 25 ° C. in orthochlorophenol of 0.70 or less. In particular, in order to improve the effects of the present invention, those having an intrinsic viscosity of 0.50 or less are preferable,
When the intrinsic viscosity of the prepolymer exceeds 0.70, the effect of improving the crystallization rate and the mechanical strength decreases, which is not preferable.
Further, the lower limit of the intrinsic viscosity of the prepolymer is not particularly limited, but in order to efficiently discharge the prepolymer in the form of a strand or sheet from the liquid phase reactor and solidify it, an intrinsic viscosity of 0.30 or more Is preferred.

The prepolymer is then solidified by cooling, crushed or granulated, and then transferred to solid phase polymerization. Cooling and solidification is performed by a usual method. For example, the prepolymer discharged from the melt polycondensation reactor in the form of a strand or a sheet is introduced into an air stream or in water to be cooled and solidified, and then ground or cut. At this time, it is advantageous to use a chip having a size as uniform as possible so that the increase of the molecular weight is uniformly carried out during the solid phase polymerization. Next, the solidified and crushed polymer chip is transferred to a reactor which is maintained at a temperature 5 to 60 ° C. lower than its melting point and has an appropriate gas inlet, exhaust port, vacuum connector, etc., under an inert gas stream or Solid phase polymerization is performed by heat treatment in vacuum. This reactor may be either a batch type or a continuous type. Incidentally, in order to prevent the polymer chips from being fused to each other during the solid phase polymerization, the chips may be dried before the solid phase polymerization as a pretreatment.

In the present invention, the above solid-state polymerized production chip has an intrinsic viscosity of 25 ° C. in orthochlorophenol.
It must be 0.70 or more and 1.05 or less. The desired degree of polymerization (intrinsic viscosity) can be appropriately adjusted by the residence time, the treatment temperature and the like. If the intrinsic viscosity exceeds 1.05, the crystallization speed and mechanical strength will decrease, and the improvement effect will be less, and if it is less than 0.70, the elongation and toughness will decrease, so in either case Is also not preferable. In general, such an intrinsic viscosity value can be obtained only by melt polycondensation, and it is generally known that solid phase polymerization improves the intrinsic viscosity of polyester. It is not necessary that the viscosity is in the above range, and it is not necessary to simply carry out solid phase polymerization, and the increment of crystal melting enthalpy during solid phase polymerization of the chip is 10 J / g or more. It is indispensable and important to process so that Particularly, it is preferably 13 J / g or more. The increment of the crystal melting enthalpy is determined by the difference between the crystal melting enthalpy of the manufactured chip after the solid state polymerization and the crystal melting enthalpy of the prepolymer chip. When the increase in crystal melting enthalpy during solid state polymerization is 10 J / g or less, the effect of improving the crystallization rate and mechanical strength in melt molding is not preferable, and the condition is not preferable. It is necessary to satisfy the conditions together. In the present invention, the above polyester is used as the component (a), but it is preferably a resin mainly containing polyalkylene terephthalate, more preferably polybutylene terephthalate.

Next, the fatty acid ester compound (b) used as a releasing agent in the resin composition of the present invention is an ester compound containing a fatty acid having 12 or more carbon atoms as a constituent component. Examples of the fatty acid having 12 or more carbon atoms constituting the fatty acid ester include lauric acid, oleic acid, palmitic acid, stearic acid, behenic acid, montanic acid and the like, preferably those having 16 to 32 carbon atoms, particularly preferably carbon The number 18 to 22 is used. If the number of carbon atoms is less than 12, the releasability improving effect is small, and if the number of carbon atoms exceeds 32, the heat resistance may decrease, which is not preferable. As the alcohol component constituting the ester, pentaerythritol, dipentaerythritol, sorbitan, aliphatic alcohols, cetyl alcohol, oleyl alcohol, ethylene glycol, diethylene glycol, triethylene glycol, glycerin, diglycerin, polyoxyethylene alcohol, etc. However, sorbitan, pentaerythritol, aliphatic alcohol, and glycerin are preferably used. Examples of preferred fatty acid ester compounds include sorbitan polypalmitate, sorbitan monostearate, sorbitan distearate, sorbitan tristearate, sorbitan monobehenate,
Sorbitan dibehenate, sorbitan tribehenate,
Pentaerythritol monostearate, pentaerythritol distearate, pentaerythritol tristearate, pentaerythritol tetrastearate and the like can be mentioned. The amount of the component (b) added is 0.01 to 5 parts by weight, preferably 0.1 to 2 parts by weight, based on 100 parts by weight of the component (a). If the amount of the component (b) is too small, the effect of improving the releasability is small, resulting in poor releasability during high cycle formation. On the other hand, if the amount of the component (b) is too large, the mechanical properties are deteriorated and the meterability becomes unstable, which is not preferable.

If necessary, a known crystallization nucleating agent (c) may be added to the polyester composition of the present invention in order to obtain a stable crystallization rate. Talc as a crystallization nucleating agent,
Examples include clay, kaolin, mica, asbestos, silicates, silica, boron nitride, silicon nitride, metal oxides and organic nucleating agents. In a normal PBT composition, a large amount of these nucleating agents is required to obtain a desired crystallization rate, so that the toughness is lowered and the cost is increased.
With the composition of the present invention, a sufficiently high crystallization rate can be obtained even with a small amount of addition that does not reduce toughness. That is, in the present invention, the addition amount of the crystallization nucleating agent (c) is 100% polyester resin (a).
It may be 0.01 to 1.0 parts by weight with respect to parts by weight.

Further, other thermoplastic resin may be added to the composition of the present invention within a range not impairing its purpose. As the thermoplastic resin, for example, polyamide, ABS, AA
S, AES, AS, polyphenylene oxide, polyalkyl acrylate, polyacetal, polysulfone,
Examples thereof include polyether sulfone, polyether imide, polyether ketone and fluororesin. Further, these thermoplastic resins may be used as a mixture of two or more kinds. In the composition of the present invention, in order to further impart desired properties depending on its purpose, a known substance generally added to a thermoplastic resin, that is, an antioxidant, a heat stabilizer, a stabilizer such as an ultraviolet absorber, An antistatic agent, a flame retardant, a flame retardant aid, a colorant such as a dye or a pigment, a lubricant, a plasticizer, and an inorganic filler may be added.

The composition of the present invention can be easily prepared by known equipment and methods generally used as conventional resin composition preparation methods. For example, i) after mixing each component, kneading and extruding with an extruder to prepare pellets, and then molding, ii) once preparing pellets having different compositions, and mixing the pellets in a predetermined amount to mold. Any method such as a method of obtaining a molded article having the target composition after the molding and iii) a method of directly charging one or more of each component into a molding machine can be used. In addition, mixing a part of the resin component in the form of fine powder with the other components and adding the powder is a preferable method for uniformly blending these components.

[0015]

INDUSTRIAL APPLICABILITY As described above, the polyester resin composition obtained by the present invention has an improved crystallization rate and is excellent in moldability in injection molding requiring a high cycle, mechanical strength of a molded article, and toughness. It is very useful as a high cycle molding material.

[0016]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited thereto. Examples 1 to 3 194 parts by weight of dimethyl terephthalate, 126 parts by weight of 1,4-butanediol, and 1.21 parts by weight of titanium tetrabutoxide were charged to a reactor which was equipped with a stirrer and a distillation column, and which was sufficiently replaced with nitrogen. The temperature inside the reactor was 140 ° C, and
The temperature was gradually raised and the by-product methanol was distilled off to carry out a transesterification reaction. Distilled methanol is the theoretical amount of 85
At wt% the temperature of the reactants increased to 185 ° C, which was then transferred to another reactor at a temperature of 210 ° C and charged with 1.0 t
After decompressing to orr, simultaneously raising the reaction temperature to 250 ℃, stirring at 1.0 torr pressure for 2.0 hours to carry out melt polycondensation, and then extruding the melt as a strand from the jet outlet, cooling the strand with water. Then, the adhering water was removed by passing under hot air and cut to obtain a white, cylindrical prepolymer chip having a diameter of 2 mm and a length of 3 mm. The resulting prepolymer has an intrinsic viscosity in orthochlorophenol at 25 ° C.
Had 0.45. Next, this tip-like prepolymer was put through a preheater (residence for 30 minutes) and then jacketed (210
℃ heat medium) supplied to the top of the vertical cylindrical solid-phase reactor,
It is deposited at a certain height in the vessel to keep a certain residence time, extracted from the lower part, and dried 210 ° C nitrogen is supplied from the lower part and discharged from the upper part for continuous solid-phase polymerization under a nitrogen stream. went. The internal temperature of this reaction system is 205 at the top.
C., 208.degree. C. at the bottom, and the residence time was 10 hours.
The resulting polymer had an inherent viscosity of 0.95 at 25 ° C in orthochlorophenol. The increase in enthalpy of crystal fusion during solid-state polymerization of manufactured chips was 14.3 J / g.
To the obtained PBT chips (a), sorbitan tribehenate or pentaerythritol tetrastearate as a fatty acid ester compound (b), optionally a crystallization nucleating agent
As (c), talc was added at a ratio shown in Table 1, and then melt-kneaded with a twin-screw extruder to prepare pellets. The evaluation described below was performed. The results are shown in Table 1. Comparative Examples 1 to 2 PBT chips (a) produced by the same method as in Example 1 were added alone or fatty acid ester compound (b) was added in an amount outside the range specified in the present application to prepare pellets in the same manner as in Example 1. And evaluated. The results are shown in Table 1. Comparative Example 3 A PBT chip having an intrinsic viscosity of 0.95 before solid phase polymerization was produced from a prepolymer having an intrinsic viscosity of 0.68 before solid phase polymerization.
The increase in the enthalpy of crystal fusion at this time was 7.1 J / g. Pellets were evaluated in the same manner as in Example 1 except that this PBT chip was used. Comparative Example 4 PBT chips (a) produced by the same method as in Example 1 were added with a general release agent (ethylenebisstearylamide) instead of the fatty acid ester compound (b) to prepare pellets for evaluation. It was

Evaluation items and evaluation methods are as follows. (1) Crystallization rate The crystallization rate and melting point were measured under the following conditions using a DSC measuring instrument, and the temperature difference (ΔT) was shown. The smaller ΔT, the faster the crystallization rate. 260 ℃ (3 minutes hold) → -10 ℃ / minute → 130 ℃ (3 minutes hold) → 10 ℃ / minute → 260 ℃ (2) Tensile strength elongation ASTM No. 1 dumbbell test piece was prepared by injection molding and ASTM D
It measured according to 638 (the number of measurements = 5). The test pieces were molded under the following conditions. Molding machine: Toshiba IS30EPN Cylinder temperature: 250 ° C (nozzle) -240 ° C (third zone) -230 ° C (second zone) -210 ° C (first zone) Mold temperature: Actually measured 40 ° C (3) Pellet feeding Evaluation of performance (variation of measuring time) Box-shaped molded product (D75mm × W40mm × H40mm × t
2 mm) was molded and the measuring time (plasticizing time) was measured. The smaller the average value, the better the pellet biting property (the result is the average value after 200 shots molding).
The box-shaped molded product was molded under the following conditions. Molding machine: Toshiba IS30EPN Cylinder temperature: 260 ° C (nozzle) -250 ° C (third zone) -240 ° C (second zone) -240 ° C (first zone) Mold temperature: 60 ° C Screw rotation speed: 160rpm (4 ) Releasability When the same molded product was molded under the same conditions as in the case of evaluating the pellet biting property, the deformation due to the protruding pin was determined according to the following ranks. ○ None △ Slightly deformed × Largely deformed

[0018]

[Table 1]

Claims (3)

[Claims] 1. A liquid phase polycondensed polyester having an intrinsic viscosity of 0.70 or less, which is composed of an acid component mainly composed of terephthalic acid or a lower alcohol ester thereof and a diol component mainly composed of 1,4-butanediol, and is once solidified. Polyester resin with solid phase polymerization under inert gas flow or reduced pressure to increase crystal melting enthalpy of manufactured chips to 10 J / g or more and intrinsic viscosity of manufactured chips to 0.70 to 1.05
(a) 100 parts by weight of one or two or more fatty acid ester compounds containing a fatty acid having 12 or more carbon atoms as a constituent, and (b) of 0.
A polyester resin composition comprising 01 to 5 parts by weight. 2. The fatty acid ester compound (b) has 12 carbon atoms.
The above fatty acids, sorbitan, pentaerythritol,
The polyester resin composition according to claim 1, which comprises an aliphatic alcohol or glycerin. 3. A crystallization nucleating agent (c) is further used as a polyester resin.
(a) The polyester resin composition according to claim 1 or 2, which is added in an amount of 0.01 to 1.0 part by weight with respect to 100 parts by weight.