Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – From carboxylic acid or derivative thereof
Reexamination Certificate
1998-10-05
2001-06-05
Boykin, Terressa M. (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
From carboxylic acid or derivative thereof
C528S176000, C528S271000
Reexamination Certificate
active
06242560
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a thermoplastic polyester elastomer and a composition comprising the same. More particularly, the present invention relates to a thermoplastic polyester elastomer which has a high melting point and good water resistance, weather resistance and heat resistance, and a composition comprising the same.
The thermoplastic polyester elastomer of the present invention can be used for the production of various shaped products such as fiber, films, sheets and the like. In particular, it is suitable as a molding material for boots, gears, tubes and the like, and it is useful in applications which require heat resistance, for example, automobiles, electric home appliances, etc. such as joint boots, coatings of electric wires, and the like.
2. Prior Art
Conventional thermoplastic polyester elastomers include a polyetherester elastomer comprising hard segments of polybutylene terephthalate (PBT) and soft segments of polytetramethylene glycol (PTMG) (see JP-B-49-48195 and JP-B-49-31558), a polyesterester elastomer comprising hard segments of PBT and soft segments of polycaprolactone (PCL) (see JP-B-48-4116, JP-A-59-12926 and JP-A-59-1517), a polyesterester elastomer comprising hard segments of PBT and soft segments of dimer fatty acids (see JP-A-54-127955), and the like, and these thermoplastic elastomers are practically used.
When the hard segments comprise PBT, the melting point of elastomers does not exceed 230° C., since the melting point of PBT is less than 230° C. To improve this drawback of the conventional elastomers comprising hard segments of PBT, elastomers are proposed, which comprise hard segments of polyethylene naphthalate or polycyclohexanedimethylene terephthalate having a high melting point (see JP-A-5-202176). However, the content of the hard segments should be 60 wt. % or less from the viewpoint of elastic properties of the elastomers, since soft segments comprise polytetramethylene glycol, and elastomers having a high melting point of 230° C. or higher have not been produced.
SUMMARY OF THE INVENTION
One object of the present invention is to provide a thermoplastic polyester elastomer having a high melting point and also good water resistance, weather resistance and heat resistance.
The term “high melting point” used herein will be explained.
In general, the melting or softening point of an elastomer increases, as the content of hard segments increases, and an elastic modulus increases. Thus, the increase of an elastic modulus can lead to the increase of a melting or softening point. However, an elastomer having a high elastic modulus has a high glass transition temperature and cannot exhibit good elastic properties, since it contains an increased amount of hard segments. The present invention intends to suppress the excessive increase of the elastic modulus and the glass transition temperature of an elastomer while achieving the high melting point of the elastomer. That is, in the present invention, an elastomer having a high melting point means an elastomer having a sufficiently high melting point although it has an elastic modulus in the same level as that of elastomers having a relatively low melting point. That is, one object of the present invention is to provide an elastomer having a high melting point in such a sense.
Accordingly, the present invention provides a thermoplastic polyester elastomer having a crystalline melting point which satisfies the relationship of the following formula (1), a Vicat softening point which satisfies the relationship of the following formula (2), and a tensile elongation of at least 100% which is measured according to JIS K 6251:
Crystalline melting point:
y≧
200+0.5
x
(1)
Vicat softening point:
z≧
50+1.5
x
(2)
in which
x is a weight percentage of polymeric units which substantially constitute hard segments of the elastomer;
y is a crystalline melting point (°C.) measured with a differential scanning calorimeter (DSC) by raising a temperature from a room temperature at a heating rate of 20° C./min.; and
z is a Vicat softening point (°C.) measured according to ASTM D1525.
In one preferable embodiment, the crystalline melting point y satisfies the relationship of the formula:
y≧
200+0.55
x
(1′)
more preferably
y≧
200+0.6
x
(1″)
In another preferable embodiment, the Vicat softening point z satisfies the relationship of the formula:
z≧
50+1.7
x
(2′)
more preferably
z≧
70+1.7
x
(2″)
When the relationships of the formulas (1) and (2) are not met, the elastomer has insufficient heat resistance, and thus cannot be used in applications which require heat resistance, for example, automobiles, electric home appliances, etc.
In principle, a Vicat softening point is measured according to ASTM D1525. Depending on the shape of a sample, a Vicat softening point may be defined by a softening point which is measured in an analogous method to ASTM D1525. For example, a temperature at which a storage modulus (E′), that is measured with a dynamic viscoelastometer, starts to decrease, or an extrapolated melt-starting temperature according to JIS K 7121 may be used as a softening point. In this application, a temperature at which a storage modulus (E′) starts to decrease in the measurement of dynamic viscoelasticity is used as a substitute for a Vicat softening point.
Here, a softening point is determined by measuring a storage modulus in the measurement of dynamic viscoelasticity using a RHEOVIBRON DDV-II (manufactured by TOYO BOLDWIN) with a sample having a thickness of from 100 to 500 &mgr;m at a heating rate of 2° C./min. and a frequency of 110 Hz.
Furthermore, the present invention provides a thermoplastic polyester elastomer comprising repeating units of the general formulas (I), (II), (III) and (IV):
wherein
R is an aromatic group having 6 to 18 carbon atoms, provided that the R groups in the general formulas (I), (II), (III) and (IV) may be the same or different;
G is a polyoxyalkylene group having a molecular weight of from 400 to 6000;
D is a residue of a hydrogenated dimer diol or its derivative;
R′ is an alkylene group having 1 to 25 carbon atoms;
a, b and c represent weight percentages of the respective repeating units in the whole polymer, provided that a is from 30 to 95 wt. %, and the ratio of b to the sum of b and c is from 0.01:1 to 0.99:1; and
d is a molar percentage in the whole polymer and from 0 to 20 mole %.
Furthermore, the present invention provides a composition comprising the above thermoplastic polyester elastomer of the present invention, and at least one additive selected from the group consisting of antioxidants, light stabilizers, lubricants, fillers, compounds having at least one epoxy group, compounds having a phenyl group which is substituted with at least one halogen atom, flame retarding aids, and compounds having a triazine group and derivatives thereof.
DETAILED DESCRIPTION OF THE INVENTION
The thermoplastic polyester elastomer of the present invention should satisfy the relationships of the above two formulas (1) and (2).
To this end, the acid component constituting the repeating units of the above general formulas (I), (II), (III) and (IV) comprises at least one aromatic dicarboxylic acid. Preferable examples of the aromatic dicarboxylic acid include terephthalic acid, naphthalenedicarboxylic acid, diphenyldicarboxylic acid, isophthalic acid, 5-sodiumsulfoisophthalic acid, and the like. They may be used singly or in combination of two or more. The proportion of the aromatic dicarboxylic acid to the whole acid component is usually at least 70 mole %, preferably at least 80 mole %.
Examples of acid components other than the aromatic dicarboxylic acid are alicyclic dicarboxylic acids, aliphatic dicarboxylic acids. Specific examples of the alicyclic dicarboxylic acid are cyclohexanedicarboxylic acid, tetrahydrophthalic anhydride, etc., and specific examples of the aliph
Araki Yoshio
Gyobu Shoichi
Kobayashi Koji
Miyaji Hidetaka
Nakayama Seiji
Boykin Terressa M.
Kenyon & Kenyon
Toyo Boseki Kabushiki Kaisha
LandOfFree
Thermoplastic polyester elastomer and composition comprising... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Thermoplastic polyester elastomer and composition comprising..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Thermoplastic polyester elastomer and composition comprising... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2522114