JP4813076B2 - Liquid crystalline polymer injection stretch blow molded article and method for producing the same - Google Patents

Description

  The present invention relates to an injection stretch blow molded article using a liquid crystalline polymer and having high heat resistance, chemical resistance, and gas barrier properties.

  Polyester containers made by stretch blow molding, especially polyethylene terephthalate containers, are widely used as containers for beverages, seasonings, cosmetics, liquid detergents, etc., regardless of whether they are foods or non-foods. However, it was not sufficient and could not be applied to applications requiring a high degree of oxygen interruption.

  On the other hand, liquid crystalline polymers have excellent fluidity, mechanical strength, heat resistance, chemical resistance, electrical properties, etc. in a well-balanced manner, so they are widely used as high-performance engineering plastics. Used for injection molding. Recently, the use of liquid crystalline polymers is also becoming more sophisticated and specialized. Especially in recent years, applications for thin-walled products such as hollow containers are expected by utilizing the excellent gas barrier properties of liquid crystalline polymers. Yes.

  However, the liquid crystalline polymer is excellent in fluidity, physical properties, etc., but has a problem that it is easy to be oriented in the direction of the melt in the melt flow direction, and is easy to tear in a thin hollow container by injection molding, and a liquid crystalline polymer container by melt extrusion blow molding. Therefore, there is a problem that a tube-shaped parison that is extrusion blow molded easily draws down, and a parting line is generated in the biting portion, so that a crack is easily generated from the parting line due to a drop impact or the like. there were.

  Therefore, it is conceivable to form a liquid crystalline polymer container by injection stretch blow molding, which does not cause a problem due to extrusion blow molding. Generally, liquid crystalline polymers have a large temperature dependency of viscosity, and a preform ( If the pre-injection molded body) has a non-uniform temperature distribution, there is a problem that only the high temperature portion is extended and the parison is ruptured.

  Patent Document 1 describes a method in which a preform in which a barrier resin such as a liquid crystalline polymer is multilayered with another resin material, and then stretch blow molding is described. In this case, each layer is recycled at the time of recycling. It is difficult to separate and recover the resin for reuse, and delamination occurs when the container is used, resulting in a significant reduction in container strength.

Patent Document 2 describes a method of performing stretch blow molding using a composition obtained by melt-mixing a liquid crystalline polymer with another resin at a blending ratio of 40% or less. In this case, the liquid crystalline polymer is It is a dispersed phase and does not exhibit any excellent gas barrier performance of the liquid crystalline polymer.
Japanese Patent Laid-Open No. 11-286077 JP 11-179792 A

  An object of the present invention is to obtain a hollow molded article having excellent gas barrier properties by injection stretch blow molding of a liquid crystalline polymer.

  As a result of diligent research, the present inventors have found that the above object can be achieved by a specific liquid crystalline polymer and specific preferable stretch blow molding conditions, and have completed the present invention.

  That is, according to the present invention, a melting point is not observed by DSC measurement at a heating rate of 20 ° C./min, and a substantially amorphous and anisotropic molten phase having a glass transition temperature of 100 to 180 ° C. can be formed. A liquid crystal polymer injection stretch blow-molded product having a mouth part, a body part and a bottom part made of a liquid crystal polymer.

  The present invention also relates to a liquid crystal in which 1 to 50% by weight of a thermoplastic resin having a melting point of 230 ° C. or lower or an amorphous resin is blended with the liquid crystalline polymer, the liquid crystalline polymer being a continuous phase and the thermoplastic resin being a dispersed phase. A liquid crystalline polymer injection stretch blow molded product having a mouth, a body and a bottom made of a conductive polymer composition, and such a melting point of 230 ° C. or lower or an amorphous thermoplastic resin includes a modified polyolefin resin or a nylon resin Can be used.

  According to the present invention, it is possible to easily obtain a blow molded article excellent in design by injection stretch blow molding without impairing the low gas permeability (gas barrier property) which is a characteristic of a liquid crystalline polymer. The body has excellent heat resistance, mechanical strength, dimensional stability and low gas permeability, and is suitable for storage containers of substances that do not like oxygen, and used for gas transfer tanks, automobile fuel tanks and their liners It is done.

  The present invention will be described in detail below. The liquid crystalline polymer used in the present invention is an amorphous wholly aromatic polyester whose melting point is not observed by DSC measurement at a heating rate of 20 ° C./min, but whose glass transition temperature is observed in the range of 100 to 180 ° C. Polyester amide, preferably polyester. That is, the liquid crystalline polymer of the present invention needs to be substantially amorphous so that the melting point is not observed by DSC measurement at a heating rate of 20 ° C./min. A crystalline polymer is not preferable because processability is lowered. Furthermore, the liquid crystalline polymer of the present invention needs to have a glass transition temperature in the range of 100 to 180 ° C. When the glass transition temperature is lower than 100 ° C, the heat resistance is unfavorably deteriorated, and when it is higher than 180 ° C, the moldability is deteriorated.

  The liquid crystalline polymer used in the present invention and the liquid crystalline polymer are blended with 1 to 50% by weight of a thermoplastic resin having a melting point of 230 ° C. or lower or amorphous, and the liquid crystalline polymer is a continuous phase and the thermoplastic resin is a dispersed phase. As specific examples of the liquid crystalline polymer composition, as materials suitable for films and direct blow molding, JP-A No. 2004-217889, JP-A No. 2004-217890, JP-A No. 2004-339462 In the present invention, such a liquid crystalline polymer and composition can be used.

  In order to produce the liquid crystalline polymer injection stretch blow molded article of the present invention, it is necessary to first obtain a preform (pre-injection molded body) by injection molding the liquid crystalline polymer and the composition thereof.

  The preform shape at the time of injection molding will be described below. The shape of the preform may be appropriately selected depending on the desired final product shape, and is generally a closed shape having a mouth portion having the same shape as the final product as shown in FIG. FIG. 1 is a cross-sectional view of a preform 1, which includes a mouth portion 2, a shoulder portion 3, a body portion 4, and a bottom portion 5. A neck ring 6 is formed below the mouth portion 2. A gate portion 7 is formed.

  The conditions for injection molding are not particularly limited, and molding under general molding conditions for liquid crystalline polymers is possible.

  Next, in order to produce the injection stretch blow molded article of the present invention, a step of blow molding a liquid crystalline polymer and a preform of the composition is necessary. The blow molding method includes a hot parison method (one-stage method) in which blow molding is performed immediately after preform injection molding, and a cold parison method in which the preform is allowed to cool to room temperature and then reheated to perform blow molding. Although there are (two-stage methods), any method can be selected in the production method of the present invention. However, the liquid crystalline polymer of the present invention and the composition thereof have a large temperature dependency of viscosity, and the feature is that the thickness of the molded product can be easily controlled by managing the preform temperature distribution during blow molding, and optimum molding. It is preferable to use the cold parison method in terms of easy finding of conditions.

  As the preform temperature condition, it is preferable to first heat the preform while rotating the preform so that the preform is uniformly heated in the circumferential direction, and the preform surface temperature immediately before blow molding is set to 120 ° C. or higher. At this time, it is preferable to divide the heater that heats the preform body to the bottom, and manage the heat input separately. In addition to adjusting the heater, the temperature condition of the preform can be adjusted by adjusting the heating time.

In the stretch blow stage, when the preform is softened, the preform is moved into the mold, and a stretch plug is inserted from the mouth portion and mechanically stretched in the length direction, and a pressurized gas is sequentially introduced into the preform. Shape. At this time, the pressure applied when the drawn plug reaches the bottom of the molded body is 3 kg / cm ² or less as the primary pressure, and the secondary pressure for shaping after the drawn rod is fully extended is 20 kg / cm ² or less. It is a preferable condition to obtain a hollow container having a uniform thickness and an excellent design property. When the primary pressure is too high, when the softened preform expands, the temperature falls locally by touching the inner surface of the mold, leading to rupture. If the primary pressure is zero, the inner surface of the softened preform touches the stretched plug and is ruptured due to a local temperature drop. Therefore, the primary pressure is 0.1 kg / cm ² or more and 2 kg / cm ² or less. The range for the secondary pressure is 2 kg / cm ² or more and 10 kg / cm ² or less.

The blow ratio when the preform is stretch blow molded is appropriately selected according to the composition of the liquid crystalline polymer and the performance and application required for the final product, but the blow ratio is preferably in the range of 1.05 to 5 The range of 1.2 to 3 is more preferable. When the blow ratio exceeds 5, the shape and thickness distribution of the molded product may be non-uniform, and a uniform hollow molded product may not be obtained. Also, if the blow ratio is smaller than 1.05, the purpose of thinning, which is also a feature of blow molding, cannot be achieved, which is also not preferable. The blow ratio indicates the swell ratio of the parison. In the preform shown in FIG. 1, when the diameter of the body portion is D ₀ and the diameter of the body portion of the final product is D ₁ , D ₁ / D ₀ expressed.

Further, in the preform shown in FIG. 1, when the length excluding the mouth 2 from the entire length of the preform is L ₀ and the length excluding the mouth of the final product is L ₁ , L ₁ / L ₀ About the longitudinal stretch ratio represented, it is preferable to set it as the range of 1.0-5, and the range of 1.0-3 is more preferable.

  Further, when the liquid crystalline polymer injection stretch blow molded article of the present invention is defined from its shape, the mouth portion has a thickness of 2.0 to 3.0 mm, and the body portion has a thickness of 1/10 or less of the mouth portion. It can be said that this is a thin hollow molded body. This thin-walled hollow molded product can also be used as a container for storing liquid materials, a container for storing gas, or a tank liner whose outer layer is reinforced with other materials because of its excellent gas barrier properties, heat resistance, dimensional stability, etc. Further, it is within the scope of the present invention.

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited thereto. In addition, the method of the physical property measurement in an Example is as follows.
[Melting point, glass transition temperature]
It measured on 20 degreeC / min temperature rising conditions with the differential scanning calorimeter (DSC7 by Perkin-Elmer Co.). Since the melting point Tm may be difficult to determine by melting peak in DSC if it is liquid crystalline, it is preferable to determine it together with the phase change under a crossed Nicol under a microscope.
[Melt viscosity]
The apparent melt viscosity at a predetermined temperature and a shear rate of 1000 sec ⁻¹ was measured with a capillary rheometer (Toyo Seiki Capillograph 1B: piston diameter 10 mm) in accordance with ISO 11443. For the measurement, an orifice having an inner diameter of 1 mm and a length of 20 mm was used.
[Gas barrier properties of hollow moldings]
A predetermined amount of volatile liquid was put into a 500 ml bottle and sealed with a PTFE cap, and then left in a room at room temperature of 25 ° C. and humidity of 50% for 48 hours to examine the weight reduction rate.
Production Example 1 (Production of liquid crystalline polymer A1)
p-hydroxybenzoic acid 122.8 parts by weight (40 mol%), 2-hydroxy-6-naphthoic acid 125.48 parts by weight (30 mol%), acetoxy-4-aminophenol 50.39 parts by weight (15 mol%), isophthalic acid 55.39 parts by weight Parts (15 mol%), 0.02 parts by weight of potassium acetate catalyst, and 196.7 parts by weight of acetic anhydride were charged into a reactor equipped with a stirrer and a distillation tube, respectively, and thoroughly purged with nitrogen. And stirring was started. The reaction is carried out at 140 ° C for 1 hour, the temperature is raised to 330 ° C over 3.3 hours, and the pressure is further reduced to 10 Torr (ie 1330 Pa) over 20 minutes to distill off acetic acid, excess acetic anhydride, and other low-boiling components. The melt polymerization was carried out. After the stirring torque reached a predetermined value, nitrogen was introduced and the pressure was changed from a reduced pressure state to a normal pressure, and the polymer was discharged from the lower part of the polymerization vessel. The obtained liquid crystalline polymer A1 did not exhibit a melting point, and had a glass transition temperature of 136 ° C. and a melt viscosity of 173.1 Pa · s at 230 ° C.
Production Example 2 (Production of Liquid Crystalline Polymer Composition A2)
After 5% by weight of Daicel Degussa polyamide elastomer (Vestamide E47-S1) was dry blended with the liquid crystalline polymer A1 produced as described above, a cylinder temperature of 230 was used using a twin screw extruder (TEX30α type manufactured by Nippon Steel). The mixture was melt-kneaded at a temperature of 200 ° C., a discharge rate of 30 kg / hr, and a rotation speed of 200 rpm to form pellets.
Production Example 3 (Production of Liquid Crystalline Polymer Composition A3)
After 5% by weight of Mitsui Chemicals polyolefin elastomer (Admer SF731) was dry blended with the liquid crystalline polymer A1 produced as described above, a twin screw extruder (TEX30α type manufactured by Nippon Steel) was used, and the cylinder temperature was 230 ° C. Melt kneading was carried out at a discharge rate of 30 kg / hr and a rotation speed of 200 rpm to form pellets.
Production Example 4 (Production of Liquid Crystalline Polymer Composition A4 (Comparative Product))
After a dry blend of 55% by weight of a polyamide elastomer (Vestamide E47-S1) made by Daicel Degussa with the liquid crystalline polymer A1 produced as described above, a twin screw extruder (TEX30α type manufactured by Nippon Steel) was used, and the cylinder temperature was 200. The mixture was melt-kneaded at a temperature of 200 ° C., a discharge rate of 30 kg / hr, and a rotation speed of 200 rpm to form pellets.
Example 1
By using the following equipment as a molding apparatus, a preform having the shape shown in FIG. 1 was injection-molded using the liquid crystalline polymer A1 under the following conditions, and then stretch-blown to perform injection stretch-blow molding. The thickness of the stretch blow molded product was about 1 mm.
(Preform injection molding)
Injection molding machine: J180EII-SP injection mold manufactured by Nippon Steel Works: Length 10cm (L ₀ = 8cm), trunk diameter (D ₀ ) 2.5cm, trunk thickness 4mm preform shape molding for beverage bottles Temperature: 240 ° C
Mold temperature: 80 ℃
Injection speed: 1.0m / min (stretch blow molding)
Blow molding machine: Material development KIT-RD1 heating temperature: 170 ° C (measured with a non-contact infrared thermometer)
Heating time: 125 seconds Blow mold: length 20cm (L ₁ = 18cm), 500ml capacity beverage bottle shape mold temperature: 25 ° C
Stretch rod speed: 5 m / min Primary blow pressure: 0.5 kg / cm ²
Secondary blow pressure: 4kg / cm ²
Holding time: 5 seconds Table 1 shows the results.
Examples 2-4, Comparative Examples 1-3
The bottle was manufactured by changing the liquid crystalline polymer material, the injection molding conditions, and the blow molding conditions as shown in Table 1. The results are shown in Table 1. The thickness of the stretch blow molded product that could be molded was about 1 mm.
Comparative Example 4
Although injection stretch blow molding was attempted under the conditions shown in Table 1 using Polyplastics Vectra A950 (melting point 280 ° C.) as the liquid crystalline polymer, the preform did not expand at all.
Comparative Example 5
When the gas barrier property of the commercially available polyethylene terephthalate bottle was similarly examined, the weight reduction rate was 1.0% for methanol and 2.3% for hexane.

It is sectional drawing which shows the shape of a preform.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Preform 2 ... Mouth part 3 ... Shoulder part 4 ... Trunk part 5 ... Bottom part 6 ... Neck ring 7 ... Gate part

Claims (7)

A liquid crystalline polymer that is substantially amorphous and capable of forming an anisotropic molten phase, wherein the melting point is not observed by DSC measurement at a heating rate of 20 ° C./min, and the glass transition temperature is 100 to 180 ° C., or In a liquid crystalline polymer that is substantially amorphous and capable of forming an anisotropic molten phase, the melting point is not observed by DSC measurement at a heating rate of 20 ° C./min, and the glass transition temperature is 100 to 180 ° C. A preform obtained by injection-molding a liquid crystalline polymer composition in which the melting point is 230 ° C. or less or an amorphous thermoplastic resin is blended in an amount of 1 to 50% by weight, the liquid crystalline polymer is a continuous phase and the thermoplastic resin is a dispersed phase. When forming a hollow molded body by blow molding, the primary pressure of the pressurized gas introduced into the preform in the blow molding process is 0.1-2 kg / cm. ² Secondary pressure is 2-10kg / cm ² A process for producing a liquid crystalline polymer injection stretch blow-molded product characterized in that The method for producing a liquid crystalline polymer injection stretch blow-molded product according to claim 1, wherein the thermoplastic resin having a melting point of 230 ° C or lower or an amorphous resin is a modified polyolefin resin or a nylon resin. 3. When forming a hollow molded body by blow-molding a preform obtained by injection-molding the liquid crystalline polymer or liquid crystalline polymer composition according to claim 1 or 2, the preform surface temperature immediately before blow molding is set to 120 ° C. or higher. A process for producing a liquid crystalline polymer injection stretch blow-molded product characterized in that The liquid crystalline polymer injection stretch blow molding according to any one of claims 1 to 3, wherein the pressure of the pressurized gas introduced into the preform in the blow molding step is pressurized in two stages of primary and secondary. Product manufacturing method. A container for storing a liquid material comprising a liquid crystalline polymer injection stretch blow molded product obtained by the production method according to any one of claims 1 to 4. The container which stores the gas which consists of a liquid crystalline polymer injection stretch blow molded article obtained by the manufacturing method of any one of Claims 1-4. A liner comprising a liquid crystalline polymer injection stretch blow molded article obtained by the production method according to claim 1.

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