JPH02140261A - Granular composition for molding - Google Patents

Abstract

PURPOSE:To obtain the subject composition capable of controlling the draw- down and die-swell in blow-molding with a small amount of lubricant and having characteristics maintained in desirable state by attaching a lubricant to granule of a polyester elastomer. CONSTITUTION:The objective composition is produced by attaching (A) 0.001-0.5 pts.wt. of a lubricant selected from higher fatty acid, higher fatty acid alkali metal salt, higher fatty acid alkaline-earth metal salt, higher fatty acid zinc salt, higher fatty acid aluminum salt, higher fatty acid ester, polyethylene-base waxes, polyfluorocarbons, ethylene bisalkylamide, silicone and natural wax to (B) 100 pts.wt. of a granular polyester elastomer containing a polyalkylene terephthalate as a hard segment component and a polyalkylene glycol or a polylactone as a soft segment component.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a granular composition for molding based on a granular polyester elastomer containing polyalkylene terephthalate as a hard segment component and polyalkylene glycol or polylactone as a soft segment component. The present invention relates to a granular composition for blow molding.

[Prior art/issues to be solved by the invention] When polyester elastomers are used for blow molding, drawdown tends to occur unlike when injection molding or extrusion molding is used, and to avoid this, it is necessary to increase the molecular weight. It is generally practiced to increase the melt viscosity by partially performing a crosslinking reaction. However, if the melt viscosity is increased by such a method, the die swell becomes large, making it difficult to produce a molded product with a desired wall thickness.

There are also proposals to solve this problem by blending polymers such as ionomers, but in general, methods using polymer blends have problems with the compatibility of the two and have a considerable impact on physical properties, which limits their use. be.

Furthermore, drawdown and die swell can be avoided to some extent by optimally adjusting molding conditions, particularly temperature conditions, screw rotation speed, and die lip, but there are limits.

[Means to solve the problem]

The present invention was made in order to solve the problems of drawdown and die swell that occur when the polyester elastomer is molded by blow molding. Based on 100 parts by weight of granular polyester elastomer containing alkylene glycol or polylactone as a soft segment component, (B) higher fatty acid, higher fatty acid alkali metal salt, higher fatty acid alkaline earth metal salt, higher fatty acid zinc salt, higher fatty acid aluminum salt, higher fatty acid Molding made by adhering 0.001 to 0.5 parts by weight of one or more lubricants selected from fatty acid esters, polyethylene waxes, polyfluorocarbons, ethylene bisalkylamides, silicones, and natural waxes to the granular polyester elastomer. The present invention relates to a granular composition for use.

〔Example〕

The polyester elastomer used in the present invention is a block copolymer consisting of polyalkylene terephthalate as a hard segment component and polyalkylene glycol or polylactone as a soft segment component.

The hard segment component is a component that has a high melting temperature of 100°C or higher, and part or most of it crystallizes in the block copolymer, and below its melting point, the crystals become nodal points of the polymer, making it look like an elastomer. The term refers to the part that acts as a crosslinking point, and the soft segment component is a component with a glass transition temperature below room temperature, which surrounds the nodal points in the block copolymer and acts as an elastomer when it expands and contracts. This word refers to parts that are easy to move.

The polyalkylene terephthalate contains an acid component mainly composed of terephthalic acid or its ester derivative and a carbon number of 2.
It is a polymer obtained from ~10 alkylene glycols. Particularly preferred examples of such polymers include polyethylene terephthalate, polybutylene terephthalate, and the like.

The polyalkylene glycol has a glass transition temperature of room temperature or lower, preferably 0°C or lower, and more preferably -20°C or lower.
℃ or less, particularly preferably 50℃ or less, and an average molecular weight of 200 to 10,000, preferably 500 to 600
0.

Preferred specific examples of such polyalkylene glycols include polyethylene glycol, polypropylene glycol, random or block copolymers of ethylene oxide and propylene oxide, polytetramethylene glycol, and ethylene oxide and/or propylene oxide of bisphenol A. Examples include additives.

Preferably, the polylactone has a glass transition point and molecular weight comparable to those of the polyalkylene glycol. Preferred specific examples of such polylactones include poly-ε-caprolactone, polyenanthlactone, and random or block copolymers of monomers forming the above polymers.

The polyester elastomer has rubber-like elasticity at room temperature, and has good properties such as moldability, low-temperature properties, mechanical properties, heat retention of tensile elongation at break, and heat-and-moisture resistance. The proportion of the soft segment is determined to be 1 from the viewpoints of having sufficient rubber elasticity at the usage temperature, a tensile strength of preferably 100 kg/c♂ or more, and an elongation of preferably 200% or more.
0 to 50% (weight%, the same applies hereinafter) is preferable, and 20 to 4
0% is more preferable. Preferred specific examples of such polyester elastomers include, for example, a block copolymer consisting of polybutylene terephthalate and polytetramethylene glycol, a block copolymer consisting of polybutylene terephthalate and polycaprolactone, polyethylene terephthalate and polyethylene glycol,
Examples include block copolymers made of polypropylene glycol, polytetramethylene glycol, or block or random copolymers thereof.

In the present invention, the polyester elastomer is
It is extruded and used as pelletized granules or sheet-cut granules for blow molding.

The above-mentioned granules are usually cylindrical, spherical, tablet-shaped, rectangular, etc., which are usually called pellets. For example, in the case of cylindrical ones, the diameter is about 0.5 to 3 mm and the length is about 1 mm. A size of about 5 mm is preferable.

The polyester elastomer can be produced by a conventional polycondensation method, and from the obtained polyester elastomer, for example, a strand is extruded using a conventional melt extruder and then cut with a pelletizer. A granular material is produced by the method.

Normally, polyester elastomers used for blow molding are those whose molecular weight is increased using a chain extender such as hexamethylene diisocyanate, or where a partial crosslinking reaction is performed using a compound having an epoxy group. many.

By doing so, it becomes possible to prevent drawdown during blow molding to some extent. However, these methods alone often result in a large die swell, making it difficult to produce a molded product with a desired wall thickness.

In the present invention, higher fatty acids, higher fatty acid alkali metal salts, higher fatty acid alkaline earth metal salts, higher fatty acid zinc salts, higher fatty acid aluminum salts, 0.001 to 0.5 parts, preferably 0.01 to 0.5 parts of one or more lubricants selected from higher fatty acid esters, polyethylene waxes, polyfluorocarbons, ethylene bisalkylamides, silicones, and natural waxes.
A moldable granular composition is prepared which is deposited in a very small quantity of 2 parts. The composition of the present invention thus prepared can very effectively solve the above problems in blow molding, suppress drawdown, and reduce die swell.

Specific examples of the higher fatty acids include higher fatty acids having about 12 to 25 carbon atoms, such as lauric acid, palmitic acid, stearic acid, and oleic acid. Specific examples include Na salt, K salt, etc. of the higher fatty acids,
Further examples include Ca salt and Mg salt. Specific examples of the higher fatty acid esters include esters of the higher fatty acids and higher alcohols having about 12 to 25 carbon atoms. Furthermore, specific examples of the polyethylene waxes include paraffin wax, polyethylene wax, etc., and specific examples of the polyfluorocarbons include, for example,
~150°C polytetrafluoroethylene wax, polytetrafluoroethylene, perfluoroalkyl carboxylic acid salts, etc., and specific examples of the ethylene bisalkylamides include ethylene bisstearylamide, etc. Specific examples include dimethyl silicone oil, methylphenyl silicone oil, and polyorganosiloxane grafted onto thermoplastics such as polystyrene. Specific examples of natural waxes include carnauba wax, cotton wax, beeswax, and wool wax. etc.

If the amount of the lubricant used is less than 0.001 part, the effect will be poor; on the other hand, if it exceeds 0.5 part, it will not penetrate from the hopper of the blow molding machine, the discharge amount will decrease, and the blowing will be difficult. This is undesirable because it takes a long time, which actually causes drawdown and other problems such as a decrease in productivity.

There are no particular limitations on the method of attaching these lubricants to the granular polyester elastomer, and it is usually sufficient to simply mix and attach the two using a stirrer or the like.
If the adhesion is poor, the objective can be achieved by heating and stirring or by using in combination other lubricants or stabilizers that become liquid at the stirring temperature. In such cases, the additive may be partially impregnated inside the granules, but
Any modification is allowed as long as it does not impair the effects of the present invention.

There is also a method in which the lubricant is heat-melted and kneaded together with the polyester elastomer in an extruder so that it is uniformly present in the granules, but if this method is used to improve drawdown and die swell, it A relatively large amount of lubricant is required and is not efficient. Of course, incorporating a lubricant has the effect of reducing the stickiness of the resin in the molding machine and improving the substitution property, so using both methods together is an effective practical measure.

The composition of the present invention does not require commonly used crystal nucleating agents, antioxidants, thermal decomposition inhibitors, hydrolysis inhibitors, various stabilizers such as ultraviolet absorbers, dyes, pigments, fillers, etc. It is natural to add scales accordingly.

Next, the composition of the present invention will be explained based on Examples.

Examples 1-5 and Comparative Examples 1-2 Polyethylene terephthalate component is 70%, molecule IJI
100 parts of a polyester elastomer consisting of 30% polyethylene glycol component was chain-extended with 1 part of hexamethylene diisocyanate to synthesize one polymer. This polyester elastomer granule (cylindrical pellets with a diameter of about 3+++ m and a length of about 4 mm) was coated with Mg stearate as shown in Table 1, and the content was molded by blow molding under the following conditions. A cylindrical bottle weighing approximately 60 g was molded using ff1400cc. The results are shown in Table 1.

For adhesion of Mg stearate, measure the above granular polyester elastomer into a polyethylene bag, then add a predetermined amount of Mg stearate (commercial product, powder).
This was done by applying vigorous vibrations.

Extruder screw diameter 40m+e Cylinder temperature 280℃ adapter temperature
235℃ crosshead temperature 235
°C Screw rotation speed 3 Orpm Die lip Die/core 24 mm / 23 mm From the results in Table 1, Comparative Example 1 in which Mg stearate is not attached
In this case, the discharge amount is small, drawdown occurs quickly, and the die swell is extremely large.

On the other hand, Example 1 in which Mg stearate was attached
It can be seen that in the case of ~5, the discharge amount increases, the length of the parison until drawdown becomes longer, and the die swell becomes approximately 1/2 of that in the case where Mg stearate is not attached. However, in the case of Comparative Example 2 in which Mg stearate was deposited in a larger amount than the range of the present invention, it was found that the biting from the hopper became worse, and therefore the discharge amount decreased.

Examples 6 to 13 and Comparative Example 3 Polyethylene terephthalate component is 72%, molecule m 1
Polyester elastomer granules (cylindrical pellets cut from extruded strands, average size (having a diameter of approximately 3 mm+ and a length of approximately 4 mm+n+a) was treated in the same manner as in Example 1, and the cases where various lubricants were attached were used and evaluated. The results are shown in Table 2.

[Margin below]

From the results in Table 2, it can be seen that in Examples 6 to 13, both drawdown properties and die swell were significantly better than the blank (Comparative Example 3).

〔Effect of the invention〕

In the present invention, since a lubricant is attached to the polyester elastomer particles, the drawdown and die swell during blow molding can be arbitrarily adjusted by using only a small amount of the lubricant. Further, deterioration of the properties originally possessed by the polyester elastomer can be suppressed to a minimum.

[Brief explanation of the drawing]

Figure 1 shows the die diameter (Dl) and parison diameter (Dl) of the blow molding machine used to determine the die swell ratio.
2) is an explanatory diagram showing 2).

Claims (1)

[Scope of Claims] 1 (A) Based on 100 parts by weight of a granular polyester elastomer containing polyalkylene terephthalate as a hard segment component and polyalkylene glycol or polylactone as a soft segment component, (B) higher fatty acid, higher fatty acid alkali metal salt , higher fatty acid alkaline earth metal salts, higher fatty acid zinc salts, higher fatty acid aluminum salts, higher fatty acid esters, polyethylene waxes, polyfluorocarbons, ethylene bisalkylamides, silicones, and natural waxes. A granular composition for molding, which is obtained by adhering 0.001 to 0.5 parts by weight to the granular polyester elastomer.