JPH0820712A - Polybutylene terephthalate resin composition - Google Patents

Abstract

(57) [Abstract] [Purpose] To improve the molding stability of polybutylene terephthalate (PBT) resin. [Composition] A composition comprising 95 to 99.9% by weight of PBT resin and 5 to 0.1% by weight of a mixed ester, and is excellent in heat resistance, rigidity and toughness in addition to molding stability. Here, the mixed ester is composed of an aliphatic monocarboxylic acid having 24 to 40 carbon atoms, a short-chain aliphatic dicarboxylic acid having 2 to 12 carbon atoms, and a polyol having 3 to 12 carbon atoms and 3 to 6 OH groups. .

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to molding stability, heat resistance,
The present invention relates to a polybutylene terephthalate resin composition having excellent rigidity and toughness, and more specifically, to a polybutylene terephthalate resin composition having excellent plasticity time and excellent molding stability during continuous molding.

[0002]

2. Description of the Related Art Polybutylene terephthalate resin (hereinafter abbreviated as PBT) is excellent in mechanical strength represented by rigidity and toughness, chemical resistance and molding processability, so that it is used for electric / electronic parts, automobile parts or other machines. Widely used in parts and the like.

Generally, these products are manufactured by an injection molding method in which a resin melt is injected into a mold, cooled, and then a molded product is taken out.

In recent years, in addition to the complicated shape of parts, there is a tendency to shorten the molding cycle and improve the productivity per hour in order to reduce the manufacturing cost.

Generally, polybutylene terephthalate is a resin excellent in moldability, but when a product having a complicated shape is manufactured in a short cycle, it becomes difficult to remove the product from the mold, and the product becomes It may be damaged or the mold may be broken and production may stop.

Various improvements have been made to solve this problem. For example, as disclosed in JP-A-52-30860, a method of molding on a film coated with a release agent, and as disclosed in JP-B-60-12396, a specific release agent is used. A method of coating a drug in a mold, a method of blending a resin with a higher aliphatic carboxylic acid as a releasing agent as illustrated in JP-B-58-18388, or an example of JP-B-53-11293. As described above, there is a method of blending polycaprolactone.

Among these improved methods, a method of incorporating a release agent into a resin is generally used at present because of its excellent productivity during resin production and molding.

The mold release agent is used to bleed out at the interface between the resin and the mold during molding so that the resin can be easily taken out from the mold before the resin is solidified in the mold. is there. In addition to this characteristic, the release agent is required to be well kneaded with the resin to be blended and not to deteriorate the original characteristic of the resin.

As the release agent to be incorporated into PBT, higher aliphatic carboxylic acids exemplified in JP-B-58-18388, polycaprolactone exemplified in JP-B-53-11293, or JP-A-1-103654. Esters of montanic acid and dihydric alcohols, which are exemplified in the publication, are known. Of these, montanic acid and 2
The ester form with a polyhydric alcohol has the performance as a release agent,
It is widely used as a release agent for PBT because it is excellent in kneading properties with PBT and does not impair the characteristics of the resin.

However, when the resin composition containing these mold release agents is heat dried for pretreatment of molding and then cooled, the mold release agent bleeding out solidifies on the surface of the resin pellets and the resin pellets stick to each other. There is a problem that the material becomes lumpy and does not flow smoothly through the hopper of the molding machine or the material supply device, resulting in defective molding.

As a method for improving such molding defects, a lubricant such as a higher fatty acid metal salt typified by a metal stearate salt is previously attached to the surface of the resin pellet,
A method of preventing the resin pellets from agglomerating is effective.

However, in this method, the lubricant once adhered during the handling of the resin pellets is separated, and the powder flies around the molding machine, impairing the health of the operator, and contaminating the hopper of the molding machine and the material supply device. Another problem arises.

As a result of intensive investigations aimed at further improving the above problems, the present inventors have found that the use of a specific mold release agent allows mold release and molding without deteriorating the original characteristics of PBT. The present invention has led to the development of the resin composition of the present invention having both stability.

[0014]

OBJECT OF THE INVENTION It is an object of the present invention to provide a polybutylene terephthalate resin composition which is excellent in molding stability, heat resistance, rigidity and toughness. Another object of the present invention is to provide a polybutylene terephthalate resin composition which is excellent in molding stability without variation in plasticizing time when continuously molded.

[0015]

DETAILED DESCRIPTION OF THE INVENTION The present invention comprises (A) 95-99.9% by weight of polybutylene terephthalate, (B) a long-chain aliphatic monocarboxylic acid having 24-40 carbon atoms, 2-12 carbon atoms. An aliphatic dicarboxylic acid having 3 and 1 to 3
Mixed ester of polyol having 2 carbon atoms and 3 to 6 OH groups, KOH 8 to 30 m / g
g acid value, KOH 130-220 mg hydrolysis value per gram, and 200-2000 mPa at 90 ° C.
A thermoplastic resin composition comprising 0.1 to 5% by weight of the mixed ester having a melt viscosity of S.

The polybutylene terephthalate (A) used in the present invention is a polymer obtained by condensation reaction containing tetramethylene glycol or its ester-forming derivative and terephthalic acid or its ester-forming derivative as main components. Say.

The polybutylene terephthalate may be copolymerized with a dicarboxylic acid component and / or a diol component other than the above-mentioned compounds as long as the original characteristics are not impaired.

The copolymerizable dicarboxylic acid component is
Isophthalic acid, naphthalene-2,6-dicarboxylic acid, naphthalene-1,5-dicarboxylic acid, naphthalene-2,7
-Dicarboxylic acid, adipic acid, sebacic acid, or their ester-forming derivatives. As the diol component, aliphatic glycols such as ethylene glycol, hexamethylene glycol, diethylene glycol and cyclohexanedimethanol, diols having an aromatic ring such as 1,4-bisoxyethoxybenzene and bisphenol A, or ester-forming derivatives thereof are applied. it can.

Polybutylene terephthalate is produced by a known method. That is, after the esterification or transesterification reaction, the polycondensation reaction is carried out under high vacuum. If necessary, polybutylene terephthalate may be further solid-phase polymerized.

The mixed ester (B) used in the present invention is a long-chain aliphatic monocarboxylic acid having 24 to 40 carbon atoms, an aliphatic dicarboxylic acid having 2 to 12 carbon atoms, and 3 to 12 Carbon atoms and 3-6 OH
It is composed of a polyol having a group.

The long-chain aliphatic monocarboxylic acid has 2 units in the molecule.
It has 4 to 40 carbon atoms and montanic acid is preferred. Montanoic acid is a mixture of monocarboxylic acids, containing a high proportion (80%) of aliphatic carboxylic acids having 26 to 34 carbon atoms in the molecule and having 2 carbon atoms.
It contains a low proportion of 5 or less aliphatic carboxylic acids.

As the aliphatic dicarboxylic acid, 2 in the molecule
It has from ~ 12 carbon atoms and can be aliphatic, alicyclic or aromatic. Examples of dicarboxylic acids are oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, nonanedicarboxylic acid, decanedicarboxylic acid, maleic acid, fumaric acid, citraconic acid. , Mesaconic acid, itaconic acid, cyclopropanedicarboxylic acid, cyclobutanedicarboxylic acid, cyclopentanedicarboxylic acid, camphoric acid, hexahydrophthalic acid, phthalic acid, terephthalic acid and isophthalic acid. Of these, adipic acid is preferred.

The polyol has 3 to 12 carbon atoms and 3 to 6 OH groups in the molecule. Glycerol, diglycerol, trimethylolpropane, ditrimethylolpropane, erythritol, pentaerythritol,
Examples are dipentaerythritol, xylitol, mannitol and sorbitol. Of these, glycerol, diglycerol, trimethylolpropane,
Ditrimethylolpropane, pentaerythritol or dipentaerythritol are preferred, and trimethylolpropane is more preferred.

The (B) mixed ester used in the present invention can be prepared by an esterification method known per se. For example, polyhydric polyols are used to esterify long chain aliphatic monocarboxylic acids. In this case, the partial ester obtained still contains a plurality of free hydroxyl groups and the mixed ester is then prepared by reacting these hydroxyl groups with an aliphatic dicarboxylic acid.

However, with dicarboxylic acids some of the hydroxyl groups of the polyol are first esterified and then the remaining free hydroxyl groups of the resulting partial ester are reacted with long-chain aliphatic monocarboxylic acids. You can also

In the reaction, an acid value of 8 to 30 mg of KOH per 1 g of the finally obtained mixed ester, preferably an acid value of 8 to 20 mg of KOH per 1 g, and a hydrolysis value of 130 to 220 mg of KOH per 1 g, preferably Is carried out by a method such that the hydrolysis value of KOH is 130 to 200 mg per 1 g.

The mixed ester (B) comprises an aliphatic dicarboxylic acid, a long-chain aliphatic monocarboxylic acid and an aliphatic polyol (0.4 to 1.0) :( 1.5 to 2.5):
An equivalent ratio of (2.5 to 3.5), preferably (0.7 to
0.9) :( 1.8 to 2.2) :( 2.8 to 3.2) in equivalent ratio. A mixed ester containing adipic acid, montanic acid and trimethylolpropane in an equivalent ratio of 0.8: 2: 3 is particularly preferable.

The mixed ester obtained by the above-mentioned method is solid at room temperature and has a viscosity of 200 to 2000 mPas at 90 ° C.
-S melt viscosity, preferably 200-800 mPa-S
It has a melt viscosity of.

The blended amount of the mixed ester in the PBT composition is 0.1 to 5% by weight. 0.1% by weight
If it is less than this, the releasability is lowered. On the other hand, when it exceeds 5% by weight, various properties such as rigidity of the resin composition deteriorate.

The PBT resin composition used in the present invention may optionally contain other additives such as fillers, heat stabilizers, flame retardants, flame retardant aids, light shielding agents, antistatic agents, pigments, dyes, lubricants. , A foaming agent or a fluorescent whitening agent may be added. In particular, it is preferable to add a heat stabilizer when it is required to have melt heat stability during molding and heat resistance in a long-term region.

The PBT resin composition is manufactured by a known method. That is, (A) polybutylene terephthalate and (B) mixed ester, and if necessary, the above additives are melt-mixed by a mixing means such as a Banbury mixer, a heating roll, a single-screw or multi-screw extruder.

[0032]

The present invention will be described below in detail with reference to examples.

The intrinsic viscosity means that the concentration of solute is 0 from the viscosity measured at 35 ° C. in orthochlorophenol resin.
The value extrapolated to.

Examples 1 to 3 and Comparative Examples 1 and 2 Preparation of PBT Dimethyl terephthalate and 1,4-butanediol were subjected to transesterification reaction in a polymerization kettle, and polycondensation reaction was carried out under high vacuum. , PBT having an intrinsic viscosity of 0.84 was obtained.

Preparation of mixed ester Montanic acid (acid value = KOH 139.2 m / g)
g) 402.7 g was melted in a whit jar. Then, with stirring, trimethylolpropane 67.
1 g and 1.32 ml of butyltin tris-2-ethylhexanoate as a catalyst were added. The mixture was heated to 125 ° C. under a nitrogen atmosphere while stirring and removing water produced by the esterification reaction by distillation.
When the acid number of the mixture dropped below 10 mg KOH / g, 29.2 g adipic acid was added. After continuing the reaction again under the same conditions until the acid value drops below 10 mg of KOH per gram, 2.5 ml of 35% hydrogen peroxide
To improve the color, stir for an additional 15 minutes and then dry to give an acid value of 8.3 mg KOH / g, a hydrolysis value of 180 mg KOH / g, and 573 mP.
A pale yellow waxy mixed ester having a melt viscosity of a · S (90 ° C.) was obtained.

The PBT and mixed ester prepared by the above-mentioned method and the heat-resistant stabilizer (Irganox 1010: manufactured by Ciba-Geigy Co., Ltd.) were mixed at the ratio shown in Table 1, melt-mixed with a twin-screw extruder, and then the diameter of 2 0.5 mm, length 3 mm
Of pellets were obtained.

The pellets were evaluated for mechanical properties, releasability, molding stability and blocking property by the following evaluation methods.

Mechanical Properties The pellets were dried at 130 ° C. for 5 hours with a tray hot air dryer, and then each test piece was molded under the following molding conditions. The tensile properties and impact strength of the obtained test piece were measured by the following measuring methods.

Molding machine: Toshiba IS-75E mold: Test piece mold Molding temperature: (nozzle) 265/260/260/250 ° C Mold temperature: 30 ° C Molding cycle: Injection 8 seconds / cooling 12 seconds / entire cycle 27 seconds Tensile test method: A No. 1 tensile dumbbell was used in accordance with ASTM D-638. Impact strength test method: ASTM D-256 compliant, with machined notch.

Releasability The pellets were dried at 130 ° C. for 5 hours in a tray hot-air dryer, and then continuously used under the following molding conditions with a mold for measuring the mold releasing force in which a pressure gauge was incorporated into an ejector pin in the mold. The ejection stress of the ejector pin during molding was measured for 20 shots. The average value of the protrusion stress was defined as the releasing force. Also,
The release condition of the molded product was visually observed for all shots.

Molding machine: Nissei PS-40E Mold: Mold for measuring mold release force (molded product: cup-shaped, outer diameter 33 mm, height 31 mm, thickness 1 mm) Molding temperature: (nozzle) 265/260/260 / 250 ℃ Mold temperature: 30 ℃

Molding stability Pellets were dried at 130 ° C. for 5 hours in a tray hot-air dryer, continuously molded for 100 shots under the following conditions to stabilize molding conditions, and then continuously molded for 500 shots. The weighing time was recorded. The value obtained by subtracting the average value from the maximum value of the weighing time for 500 shots was defined as the molding stability.
It can be said that the smaller this value, the better the molding stability.

Molding Machine: Nissei PS-40E Mold: Connector Mold Molding Temperature: (Nozzle) 265/260/260/250 ° C Mold Temperature: 30 ° C

Blocking property 2 kg of pellets was heated at 130 ° C. for 1 hour in a tray-type hot air dryer.
After standing for 2 hours, it was cooled at 15 ° C. for 12 hours.
The state of the cooled pellet was visually observed.

Comparative Examples 3 and 4 Instead of the mixed ester, montanic acid diester of ethylene glycol (WA
XE: manufactured by Hoechst Co.) was used, and the mechanical properties, mold release property, molding stability and blocking property were evaluated by the same method as in Example 1.

The results are shown in Table 1.

[Comparative Examples 5 and 6] Mechanical properties and releasability were the same as in Example 1 except that a lithium salt of montanic acid (LiV103: manufactured by Hoechst) was used in place of the mixed ester. The molding stability and blocking property were evaluated.

The results are shown in Table 1 together.

[0049]

[Table 1]

Claims (5)

[Claims] 1. (A) Polybutylene terephthalate 95
˜99.9% by weight, (B) a long-chain aliphatic monocarboxylic acid having 24 to 40 carbon atoms, an aliphatic dicarboxylic acid having 2 to 12 carbon atoms, and 3 to 12 carbon atoms. A mixed ester of a polyol having 3 to 6 OH groups, having an acid value of 8 to 30 mg KOH per 1 g,
A polybutylene terephthalate resin composition comprising 0.1 to 5% by weight of the above mixed ester having a hydrolysis value of 130 to 220 mg of KOH per 1 g and a melt viscosity of 200 to 2000 mPa · S at 90 ° C. 2. The polybutylene terephthalate resin composition according to claim 1, wherein the long-chain aliphatic monocarboxylic acid constituting the mixed ester (B) is montanic acid. 3. The polyol constituting the mixed ester (B) is one or more selected from the group consisting of glycerol, diglycerol, trimethylolpropane, ditrimethylolpropane, pentaerythritol and dipentaerythritol. The polybutylene terephthalate resin composition according to claim 1. 4. The polybutylene terephthalate resin composition according to claim 1, wherein the long-chain aliphatic monocarboxylic acid constituting the mixed ester (B) is montanic acid, the polyol is trimethylolpropane, and the aliphatic dicarboxylic acid is adipic acid. Stuff. 5. A filler, a heat stabilizer, a flame retardant, a flame retardant auxiliary,
The polybutylene terephthalate resin composition according to claim 1, further comprising a light-shielding agent, an antistatic agent, a pigment, a dye, a lubricant, a foaming agent or an optical brightening agent.