Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – From reactant having at least one -n=c=x group as well as...
Reexamination Certificate
2001-06-20
2004-09-14
Sergent, Rabon (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
From reactant having at least one -n=c=x group as well as...
C005S499000, C036S098000, C052S408000, C135S087000, C297S463200, C528S904000, C602S041000, C602S052000, C602S058000
Reexamination Certificate
active
06790926
ABSTRACT:
The invention pertains to a non-porous, waterproof film having a water vapour permeability of at least 1000 g/m
2
day in accordance with ASTM E96-66 (Procedure B), with the proviso that the water temperature is kept at 30° C., while the ambient temperature is 21° C. at 60% RH, based on a thermoplastic polyurethane composed of a polyether glycol, a polyisocyanate, and a chain extender, at a ratio of NCO to active hydrogen atom of 0,9 to 1,2, and to the use of such films in rainwear and tents, as mattress covers, as underslating for roofing, in the manufacture of waterproof shoes, in the manufacture of seats, especially car seats, in garments for medical purposes, and for the manufacture thereof of wound dressings.
Non-porous, waterproof and water vapour permeable films based on a thermoplastic polyether urethane of the aforesaid composition having a water vapour permeability of at least 1000 g/m
2
day are known from JP-A-09 157 409. The preparation of the polyurethane resin does not involve the use of solvents. Because of the presence of a very high percentage of polyethylene oxide glycol, a polymer is obtained which in its film form has a very high water vapour permeability, but which also has high tackiness. Furthermore, it was found that the waterproofness of films of the composition as described in said document is found wanting for a wide range of applications. Likewise, polyurethanes of the composition as described therein generally have a too low melting point for use in many of the applications listed above.
The invention now provides non-porous thermoplastic polyurethane films having a high water vapour permeability, a satisfactory waterproofness, and a sufficiently high softening point to allow cleaning at higher temperatures in the case of use in, e.g, garments.
The invention consists in that in a thermoplastic polyurethane film of the known type mentioned in the opening paragraph the polyurethane is composed of:
a) 40 to 52 wt. % of polyether glycol, calculated as polyethylene oxide glycol, having an average molecular weight of greater than 800 to 4000 and an atomic ratio of carbon to oxygen in the range of 2,0 to 4,3, with at least 30 wt % of the polyurethane being composed of a polyether glycol having an atomic ratio of carbon to oxygen in the range of 2,0 to 2,4,
b) 30 to 45 wt. % of polyisocyanate, calculated as 4,4′-diphenyl methane diisocyanate,
c) 0,5 to 10 wt. % of araliphatic diol of the formula
k=0 or 1, where if k=1, Y stands for a methylene or isopropylidene group,
Q has the meaning of an H-atom or a CH
3
group, C
6
X
4
has the meaning of a phenylene group wherein X is hydrogen or a chlorine or bromine atom, and m and n may be the same or different and stand for an integer≧1, with m+n≦10, and
d) 5 to 20 wt. % of a chain extender having a maximum molecular weight of 500, calculated as 1,4-butane diol, less the amount of araliphatic diol.
Surprisingly, it was found that polyurethane films of the aforesaid composition are well-balanced in terms of softening point, water vapour permeability, waterproofness, and sticking. Moreover, using a halogenated araliphatic diol makes it possible to obtain films which have fire retardant properties. It should be noted that thermoplastic polyurethanes which have a higher softening point because of the incorporation of a compound based on an ethoxylated and/or propoxylated bisphenol A are known as such from Japanese patent publications JP-A-55-54320 and JP-A445117.
The former publication discloses a polyurethane incorporating a compound of the formula
For the meaning of n and m an integer of 2 to 30 is listed there, while Q stands for a CH
3
group or a hydrogen atom and C
6
H
4
stands for a phenylene group. The examples only mention diols with an average molecular weight of 1800 to 2000. The compounds do not have the effect of increasing the softening point, however, but only have a favourable effect on such general physical properties as resistance to degradation under the influence of UV light, yellowing, and sticking. Nor is there any mention of the possible use of polyethylene oxide glycol for the manufacture of water vapour permeable films.
In the latter publication there also is a polyurethane incorporating a diol according to the formula above. The object in this case is to obtain a less brittle polymer which gives fewer injection moulding problems. In order to obtain a sufficiently hard polymer, the molecular weight of any polyalkylene oxide glycol incorporated therein should not exceed 800. Consequently, there is no question of the manufacture of films, let alone waterproof yet at the same time water vapour permeable films.
Preferably, the long-chain glycols are composed wholly of polyethylene oxide glycol. In some cases it may be desirable to employ random or block copolymers of epoxyethane with minor amounts of a second epoxyalkane. In general, the second monomer makes up less than 40 mole % of the polyalkylene oxide glycols, preferably less than 20 mole %. Suitable examples of second monomers are 1,2- and 1,3-epoxypropane, 1,2-epoxybutane, and tetrahydrofuran. Alternatively, use may be made of mixtures of polyethylene oxide glycol, e.g., poly-1,2-propylene oxide glycol or polytetramethylene oxide glycol.
Using a polyalkylene oxide glycol with a molecular weight of 800 or less will generally be at the expense of the water vapour permeability, and also less flexible films are obtained. Using a polyalkylene oxide glycol with a molecular weight of more than 4000 may give rise to problems due to phase separation.
So far, very favourable results have been obtained using a polyalkylene oxide glycol with an average molecular weight of 1000 to 3000.
Optimum results have been obtained so far using a polyalkylene oxide glycol with a molecular weight of about 2000.
The amount of polyether glycol may vary within wide limits. In general, optimum results are obtained using a weight percentage between 41 and 50.
Depending on the meaning of Q, X, m, and n, the amount of araliphatic diol varies between 0,5 and 10 wt. %, but preferably between 1 and 8 wt. %.
Very good results were obtained using an araliphatic diol according to the formula above wherein k=1, Y represents an isopropylidene group, Q and X have the meaning of an H-atom, and m and n=1.
Very good results were also obtained using an araliphatic diol according to the formula above wherein k=1, Y represents an isopropylidene group, Q has the meaning of a CH
3
group and X has the meaning of a hydrogen atom, and m and n=1.
The amount of polyisocyanate, calculated as 4,4′-diphenyl methane diisocyanate, is at least 30 and at most 45 wt. %.
Examples of suitable polyisocyanates are 4,4′-diisocyanatodiphenyl, 3,3′-dichloro-4, 4′-diisocyanatodiphenyl, 3,3′-diphenyl-4,4′-diisocyanatodiphenyl, 3,3′-dimethoxy-4, 4′-diisocyanatodiphenyl, 4,4′-diisocyanatodiphenyl methane, 3,3′-dimethyl-4, 4′-diisocyanatodiphenyl methane, and a diisocyanatonaphthalene. Optimum results were obtained using an amount in the range of 35 to 42 wt. %, calculated as 4,4′-diphenyl methane diisocyanate.
The amount of low-molecular weight chain extender in the polyurethane resin is 5 to 20 wt. %, calculated as 1,4-butane diol, less the amount of araliphatic diol according to the formula above. The low-molecular weight chain extending agent preferably has two reactive hydrogen atoms and a molecular weight of at most 500, preferably of at most 300.
Suitable hydroxy-functional compounds include aliphatic or cycloaliphatic polyols having 2 hydroxyl groups. Examples of polyols include ethylene glycol, propylene glycol, diethylene glycol, tetramethylene diol, neopentyl glycol, hexamethylene diol, cyclohexane diol, and bis-(4-hydroxycyclohexyl)methane. Also suitable for use are low-molecular weight amino acid hydrazides such as aminoacetic acid hydrazide, &agr;-aminopropionic acid hydrazide, &bgr;-aminopropionic acid hydrazide, &bgr;-amino-&agr;,&agr;-dimethyl amino-propi
Bontinck Dirk
De Koninck Luc
Mezger Thomas
Spijkers Jozef C. W.
Van De Ven Hendricus J. M.
Sergent Rabon
Sympatex Technologies GmbH
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