JP3342958B2 - Polybutylene terephthalate resin composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 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 particularly, to a polybutylene terephthalate resin composition which is excellent in molding stability without variation in plasticization time when continuously molded.

[0002]

2. Description of the Related Art Polybutylene terephthalate resin (hereinafter abbreviated as PBT) is excellent in mechanical strength represented by stiffness and toughness, chemical resistance and moldability, so that it can be used for electric / electronic parts, automobile parts or other machinery. Widely used for 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 a molded product is taken out.

[0004] In recent years, in addition to increasing the complexity of parts, there is a tendency to shorten the molding cycle in order to reduce manufacturing costs and improve productivity per hour.

[0005] In general, polybutylene terephthalate is a resin having excellent moldability. However, when a product having a complicated shape is manufactured in a short cycle, it is difficult to take out the product from a mold. Production may be stopped due to damage or mold damage.

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

[0007] Among these improved methods, a method of blending a release agent with a resin is generally used at present because of its excellent productivity in resin production and molding.

[0008] The release agent is used to bleed out to the interface between the resin and the mold before the resin solidifies in the mold during the molding process, so that the molded product can be easily removed from the mold. is there. In addition to these properties, the release agent is required to be well kneaded with the resin to be compounded and not to lower the inherent properties of the resin.

Examples of the release agent to be mixed with PBT include higher aliphatic carboxylic acids exemplified in JP-B-58-18388, polycaprolactone exemplified in JP-B-53-11293, and JP-A-1-103654. And the like, for example, an ester of montanic acid and a dihydric alcohol, which are exemplified in JP-A No. 2000-163, are known. Of these, montanic acid and 2
Ester with a dihydric alcohol, performance as a release agent,
Since it is excellent in that it does not impair the kneadability with PBT and the properties of the resin, it is widely used as a PBT release agent.

However, after the resin composition containing these release agents is thermally dried for pre-molding treatment and then cooled, the release agents bleed out to the surface of the resin pellets are solidified, and the resin pellets adhere to each other. There is a problem that the material becomes a lump and does not flow smoothly through the hopper or the material supply device of the molding machine, and molding defects occur.

As a method for improving such molding defects, a lubricant such as a metal salt of a higher fatty acid represented by a metal salt of stearic acid is attached to the surface of a resin pellet in advance.
A method of preventing agglomeration of resin pellets is effective.

However, in this method, the lubricant once adhered during handling of the resin pellets is separated, and the powder scatters around the molding machine, thereby damaging the worker's health and contaminating the hopper and the material supply device of the molding machine. Another problem arises.

The inventors of the present invention have conducted intensive studies on the improvement of the above problems, and as a result, by using a specific release agent, the releasability and the moldability without deteriorating the inherent characteristics of PBT. The present inventors have developed a resin composition of the present invention having both stability.

[0014]

SUMMARY OF THE INVENTION An object of the present invention is to provide a polybutylene terephthalate resin composition having excellent molding stability, heat resistance, rigidity and toughness. It is another object of the present invention to provide a polybutylene terephthalate resin composition which is excellent in molding stability without variation in plasticization time when continuously molded.

[0015]

The present invention relates to (A) 95 to 99.9% by weight of polybutylene terephthalate, (B) a long-chain aliphatic monocarboxylic acid having 24 to 40 carbon atoms, 2 to 12 carbon atoms. An aliphatic dicarboxylic acid having the formula:
A mixed ester of a polyol having 2 carbon atoms and 3 to 6 OH groups, wherein KOH is 8 to 30 m / g.
g of acid number, hydrolysis number of 130-220 mg KOH 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 a condensation reaction comprising tetramethylene glycol or an ester-forming derivative thereof and terephthalic acid or an ester-forming derivative thereof as main components. Say.

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

The copolymerizable dicarboxylic acid component includes:
Isophthalic acid, naphthalene-2,6-dicarboxylic acid, naphthalene-1,5-dicarboxylic acid, naphthalene-2,7
-Dicarboxylic acids, adipic acids, sebacic acids or their ester-forming derivatives. As the diol component, aliphatic glycols such as ethylene glycol, hexamethylene glycol, diethylene glycol and cyclohexane dimethanol, 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, a polycondensation reaction is performed under a high vacuum. If necessary, polybutylene terephthalate may be further subjected to solid phase polymerization.

The mixed ester (B) used in the present invention includes 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. Carbon atoms and 3-6 OH
It is composed of a polyol having a group.

The long-chain aliphatic monocarboxylic acid has 2 in the molecule.
It has from 4 to 40 carbon atoms, with montanic acid being preferred. Montanic 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.
Contains a low proportion of up to 5 aliphatic carboxylic acids.

As the aliphatic dicarboxylic acid, 2
It has up to 12 carbon atoms and can be aliphatic, cycloaliphatic or aromatic. Examples of dicarboxylic acids include 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 is preferred, and trimethylolpropane is more preferred.

The mixed ester (B) used in the present invention can be prepared by a known esterification method. For example, a long-chain aliphatic monocarboxylic acid is esterified using a polyhydric polyol. In this case, the resulting partial ester still contains a plurality of free hydroxyl groups, and the mixed ester is then prepared by reacting those hydroxyl groups with an aliphatic dicarboxylic acid.

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

The reaction is carried out in such a manner that the finally obtained mixed ester has an acid value of 8 to 30 mg of KOH per gram, preferably an acid value of 8 to 20 mg of KOH per gram, and a hydrolysis value of 130 to 220 mg of KOH per gram. Is carried out in such a way that it has a hydrolysis value of from 130 to 200 mg of KOH per gram.

The (B) mixed ester is obtained by mixing an aliphatic dicarboxylic acid, a long-chain aliphatic monocarboxylic acid and an aliphatic polyol with (0.4 to 1.0): (1.5 to 2.5):
(2.5-3.5), preferably (0.7-3.5).
0.9): (1.8 to 2.2): (2.8 to 3.2). Mixed esters containing adipic acid, montanic acid and trimethylolpropane in an equivalent ratio of 0.8: 2: 3 are particularly preferred.

The mixed ester obtained by the above-mentioned method is solid at ordinary temperature, and is 200 to 2000 mPa.
・ S melt viscosity, preferably 200 to 800 mPa ・ S
Having a melt viscosity of

The compounding amount of the mixed ester in the present PBT composition is 0.1 to 5% by weight. 0.1% by weight
If it is less than the above range, the releasability will be reduced. Conversely, if it exceeds 5% by weight, various properties such as the rigidity of the resin composition are reduced.

The PBT resin composition used in the present invention may optionally contain other additives such as a filler, a heat stabilizer, a flame retardant, a flame retardant auxiliary, a light-blocking agent, an antistatic agent, a pigment, a dye, and a lubricant. , A foaming agent or a fluorescent whitening agent. In particular, when the melt heat stability at the time of molding and the heat resistance in a long time range are required, it is preferable to add a heat stabilizer.

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

[0032]

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

The intrinsic viscosity is defined as the value of the solute concentration determined from the viscosity of a resin measured at 35 ° C. in orthochlorophenol.
Means a value extrapolated to

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

Preparation of mixed ester Montanic acid (acid value = 139.2 m KOH / g)
g) 402.7 g were melted in a whit jar. Next, with stirring, trimethylolpropane.
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 the water formed in the esterification reaction by distillation.
When the acid number of the mixture dropped to less than 10 mg KOH / g, 29.2 g of adipic acid was added. The reaction was continued under the same conditions until the acid value was reduced to less than 10 mg of KOH / g, and then 2.5 ml of 35% hydrogen peroxide.
To improve the color, stirred for a further 15 minutes and then dried to give an acid number of 8.3 mg KOH / g, a hydrolysis number of 180 mg KOH / g and 573 mP
A pale yellow waxy mixed ester having a.S (90 ° C.) melt viscosity was obtained.

The PBT and the mixed ester prepared by the above-mentioned method and a heat-resistant stabilizer (Irganox 1010: manufactured by Ciba Geigy Co., Ltd.) were mixed at the ratio shown in Table 1 and melt-mixed with a twin screw extruder. .5mm, length 3mm
Was obtained.

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

Mechanical Properties The pellets were dried at 130 ° C. for 5 hours with a tray-type 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 pieces were measured by the following measurement methods.

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

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

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

Molding stability The pellets were dried at 130 ° C. for 5 hours with a hot-air dryer, continuously molded for 100 shots under the following conditions to stabilize the 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 molding stability.
It can be said that the smaller the 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 the pellets were placed in a tray hot air dryer at 130 ° C.
After allowing to stand for 2 hours, it was cooled at 15 ° C. for 12 hours.
The cooled pellet was visually observed.

Comparative Examples 3 and 4 In place of the mixed ester, montanic acid diester of ethylene glycol (WA) was used.
X-E: manufactured by Hoechst Co.), except that mechanical properties, release properties, molding stability and blocking properties were evaluated in the same manner as in Example 1.

Table 1 shows the results.

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

Table 1 also shows these results.

[0049]

[Table 1]

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int. Cl. ⁷ , DB name) C08L 67/00-67/02

Claims (5)

(57) [Claims] (A) Polybutylene terephthalate 95
-99.9 wt%, (B) a long chain aliphatic monocarboxylic acid having 24-40 carbon atoms, an aliphatic dicarboxylic acid having 2-12 carbon atoms, and 3-12 carbon atoms. A mixed ester of a polyol having 3 to 6 OH groups, having an acid value of 8 to 30 mg of KOH / g;
A polybutylene terephthalate resin composition comprising 0.1 to 5% by weight of the mixed ester having a hydrolysis value of 130 to 220 mg of KOH / 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 (B) the long-chain aliphatic monocarboxylic acid constituting the mixed ester 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 (B) the long chain aliphatic monocarboxylic acid constituting the mixed ester is montanic acid, the polyol is trimethylolpropane, and the aliphatic dicarboxylic acid is adipic acid. object. 5. A filler, a heat stabilizer, a flame retardant, a flame retardant auxiliary,
5. 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 a fluorescent whitening agent.