Stock material or miscellaneous articles – Hollow or container type article – Polymer or resin containing
Reexamination Certificate
1998-03-03
2001-05-08
Robinson, Ellis (Department: 1772)
Stock material or miscellaneous articles
Hollow or container type article
Polymer or resin containing
C428S542800, C428S903300, C528S275000, C528S280000, C528S285000, C528S286000, C528S298000
Reexamination Certificate
active
06228447
ABSTRACT:
DETAILED DESCRIPTION OF THE INVENTION
The present invention relates to a polyethylene-2,6-naphthalene dicarboxylate resin and to a preform for a bottle and a bottle, which are molded thereof. More specifically, it relates to a polyethylene-2,6-naphthalene dicarboxylate resin which is excellent in hue, transparency, thermal stability and moldability, to a preform for a bottle and to a bottle molded thereof that is excellent in hue, transparency and thermal stability.
Plastic bottles are mainly used as bottles for beverages such as juice, water, beer or the like. Materials for these plastic bottles need to be excellent in hue, transparency, gas barrier properties and flavor retention properties in view of increasing commercial product value when a bottle and its contents are seen as a unitary commodity.
For the purpose of saving resources and the like, recycling of plastic bottles, that is, the re-use of bottles has been recently studied. A recycle system for the bottles comprises the step of cleaning a bottle with an alkali at a high temperature. Therefore, the bottle must have a resistance to hydrolysis to stand this step.
Polyethylene-2,6-naphthalene dicarboxylate (may be abbreviated as PEN hereinafter) can be basically produced using the same catalyst as that for polyethylene terephthalate (may be abbreviated as PET hereinafter), but from a viewpoint of hue, germanium dioxide is used as a polymerization catalyst for PEN, in particular.
According to studies conducted by the inventors of the present invention, whitening occurs more readily at the time of blow molding PEN than PET, and a bottle having satisfactory transparency cannot be obtained from PEN with the prior art.
The present inventors have further studied the cause of whitening a bottle and have found that whitening of a bottle is caused by deposited particles derived from a catalyst contained in a polymer. That is, the deposited particles derived from a catalyst induce crystallization and increase internal haze. Particularly, in the case of PEN, stress at the time of molding (stretching) a bottle is larger compared with PET and hence, the influence of crystallization largely results.
Therefore, to suppress the whitening of a bottle, the amount of a deposit derived from a catalyst or the like must be reduced.
There is proposed a method for reducing the deposit in which a specific catalyst is used in a specific amount and a specific ratio. It is for sure that the transparency of PEN is improved by this method.
However, even with this method, PEN having satisfactory hue and thermal stability could not be obtained. It has been found that the reason for this is that the decomposition rate of a polymer becomes high when the polymer is melt molded because the catalyst is not deactivated completely due to a small amount of a phosphorus compound added used to deactivate the ester exchange catalyst so as to suppress the production of a deposit in the prior art.
It has been also revealed that when the melt viscosity of the polymer is not appropriate at the time of melt molding PEN, such problems arise that the resulting bottle cannot have a smooth surface and uniform thickness or has an extremely deteriorated haze value, thereby causing the generation of a haze or a large amount of acetaldehyde is regenerated.
When the amount of acetaldehyde contained in the raw material polymer is large in addition to the amount of regenerated acetaldehyde at the time of molding, the amount of acetaldehyde contained in a preform and a bottle is large, whereby an offensive odor derived from acetaldehyde is generated from the contents of the bottle.
Since PEN has low impact strength, a PEN bottle is easily cracked or delaminated when dropped.
JP-A 6-340734 (the term “JP-A” as used herein means an “unexamined published Japanese patent application”) discloses a method for producing polyester naphthalate that can provide a film having excellent surface flatness and that shows a good electrostatic adhesion. In this method, magnesium, calcium, phosphorous and antimony compounds are added to a reaction system in such amounts that satisfy the following expressions (11) to (14) when a lower alkylester of naphthalene dicarboxylic acid is reacted with ethylene glycol to produce polyethylene naphthalate:
2.6≦Ca+Mg≦3.7 (11)
1.3≦Mg/Ca≦6.0 (12)
2.3≦(Ca+Mg)/P≦7.0 (13)
0.4≦Sb≦2.0 (14)
wherein Mg, Ca, Sb and P indicate the number of mols of element magnesium, element calcium, element antimony and element phosphorus, based on 10
6
g of an aromatic dicarboxylic acid component constituting the aromatic polyester, respectively.
JP-A 7-82464 discloses a polyethylene naphthalate composition for sensitized material for photograph, which contains element magnesium, element calcium, element phosphorus and element antimony, each of which is derived from a magnesium compound, a calcium compound, a phosphorus compound and an antimony compound respectively, in polyethylene naphthalate in such amounts that satisfy the following expressions (21) to (24):
2.6≦Mg+Ca≦4.0 (21)
10≦Mg/Ca≦6.0 (22)
0.5≦(Mg+Ca)/P≦1.5 (23)
0.5≦Sb≦2.0 (24)
wherein Mg, Ca, P and Sb are the same as defined in the above expressions (11) to (14).
JP-A 7-258395 discloses a polyethylene naphthalene dicarboxylate composition that contains magnesium, calcium, phosphorus and antimony compounds (in this case, only antimony acetate is acceptable as an antimony compound) in such amounts that satisfy the following expressions (31) to (34):
2.6≦(Mg+Ca)≦4.1 (31)
1.3≦Mg/Ca≦6.0 (32)
1.0≦P/(Mg+Ca)≦1.5 (33)
1.0≦Sb≦3.0 (34)
wherein Mg, Ca, P and Sb are the same as defined in the above expressions (11) to (14), and that further contains an ammonium compound represented by the following formula (35) in an amount of 0.04 to 0.4 mol based on 10
6
g of an acid component constituting the polyester:
(R
1
R
2
R
3
R
4
N
+
)A
−
(35)
wherein R
1
, R
2
, R
3
and R
4
are each a hydrogen atom, an alkyl group, a cycloalkyl group, an aryl group or a derivative group thereof or R
3
and R
4
may form a ring, and A
−
is a residual anion group.
JP-A 8-104744 discloses a method in which magnesium, calcium, phosphorus and antimony compounds are added in such amounts that satisfy the following expressions (41) to (44) when a lower alkylester of naphthalene dicarboxylic acid is reacted with ethylene glycol to produce polyethylene naphthalate:
1.0≦Ca+Mg<2.6 (41)
3.0≦Mg/Ca≦6.0 (42)
2.3≦(Ca+Mg)/P≦7.0 (43)
0.4≦Sb≦2.0 (44)
wherein Ca, Mg, P and Sb are the same as defined in the above expressions (11) to (14).
JP-A 7-258394 discloses a polyester, which comprises naphthalene dicarboxylic acid as a main acid component and ethylene glycol as a main glycol component and contains manganese, phosphorus and antimony compounds in such amounts that satisfy the following expressions (51), (52) and (53):
0.7≦Mn≦1.7 (51)
0.5≦Mn/P≦1.2 (52)
1.0≦Sb≦3.0 (53)
wherein P and Sb are the same as defined in the above expressions (11) to (14) and Mn indicates the number of mols of element manganese in a manganese compound, based on 1 ton of an acid component constituting the polymer.
The polyester has the transmittance (T
400
) at a wavelength of 400 nm of 95%/cm when it is dissolved in a mixed solvent of hexafluoroisopropanol and chloroform (proportion: 2:3) at the concentration of 10 mg/ml, and the difference between transmittance (T
400
) and the transmittance (T
420
) at a wavelength of 420 nm is 3%/cm or less. The polyester is used for molding a bottle.
However, the polyesters disclosed by each of the above prior arts are not yet necessarily satisfactory as a raw material for a bottle.
It is therefore an object of the present invention to provide polyethylene-2,6-naphthale
Sato Kimihiko
Suzuki Minoru
Nolan Sandra M.
Robinson Ellis
Sughrue Mion Zinn Macpeak & Seas, PLLC
Teijin Limited
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