The invention comes within the field of the preparation of elastomers.
The preparation of elastomeric polymers often makes use of chain-extending compounds, the role of which is to improve certain physical properties of the final polymer, such as its hardness, its resistance to heat or its resistance to hydrolysis.
The most widely used chain extenders in the preparation of polyurethane elastomers are 1,4-butanediol or BDO:
1,4-bis[(2-hydroxyethyl)oxy]benzene or HQEE:
or diethoxylated resorcinol or HER:
In the context of its research into polyalkoxylated compounds, the Applicant Company has developed a novel chain extender which improves the physical properties of polyurethane polymers.
For this reason, a subject-matter of the invention is a composition, characterized in that it comprises
from 0.5% to 100% by weight of a compound of formula (I):
in which R1, R2, R3 and R4, which are identical or different, represent, independently of one another, a hydrogen atom, a methyl radical or an ethyl radical,
n and m, which are identical or different, represent, independently of one another, a number between 0 and 10, it being understood that the sum n+m is greater than zero,
and
from 0% to 99.5% by weight of a compound of formula (II):
in which R5, R6, R7 and R8, which are identical or different, represent, independently of one another, a hydrogen atom, a methyl radical or an ethyl radical, p and q, which are identical or different, represent, independently of one another, a number between 0 and 10, it being understood that the sum p+q is greater than zero.
In the formulae (I) and (II) as defined above, the radicals:
Within each of the groups —[O—CHR1—CHR2]n—, —[CHR3—CHR4—O]m—, —[CHR5—CHR6—O]p— or —[CHR7—CHR8—O]q—, the —O—CH2—CH2—, —CH2—CH(CH3)—O—, —CH(CH3)—CH2—O—, —CH(C2H5)—CH2—O— or —CH2—CH(C2H5)—O— radicals are distributed in block or random fashion.
According to a specific aspect, a subject-matter of the invention is a composition as defined above for which, in the formula (I), R1, R2, R3 and R4 each represent a hydrogen atom.
According to another specific aspect, a subject-matter of the invention is a composition as defined above for which, in the formula (II) , R5, R6, R7 and R8 each represent a hydrogen atom.
According to yet another specific aspect, a subject-matter of the invention is a composition as defined above comprising from 10% by weight to 60% by weight and preferably from 15% by weight to 55% by weight of compound of formula (I) and from 40% by weight to 90% by weight and preferably from 45% by weight to 85% by weight of compound of formula (II).
A very particular subject-matter of the invention is a composition as defined above in which the compound of formula (I) is diethoxylated bisphenol A of formula (Ia):
and in which the compound of formula (II) is diethoxylated resorcinol of formula (IIa):
and a preferred subject-matter of the invention is a composition comprising from 30% by weight to 50% by weight of compound of formula (Ia) and from 50% by weight to 70% by weight of compound of formula (IIa).
According to another aspect, a subject-matter of the invention is also the use of the composition as defined above as chain extender in a polyurethane elastomer formulation and a process for the preparation of a polyurethane elastomer formulation starting from isocyanate prepolymer and from an effective amount of chain extender, characterized in that the said chain extender is the composition as defined above.
According to a final aspect, a subject-matter of the invention is the use of the composition as defined above as monomers in the preparation of saturated or unsaturated polyesters, of polycarbonates or of epoxy resins.
The following account illustrates the invention without, however, limiting it.
A mixture of 52% by weight of diethoxylated resorcinol and 48% by weight of diethoxylated bisphenol A, known as composition E, is prepared.
Two polyurethane elastomer compositions are subsequently prepared according to an experimental method known to a person skilled in the art, the parameters of which are recorded in the following Table 1, starting from Vibrathane™ B625, which is an isocyanate prepolymer having a percentage of isocyanate (—N—C═O) functional group of between 6.2 and 6.9, and from a chain extender, 1,4-butanediol for formulation A according to the state of the art or composition E for formulation I according to the invention.
The mechanical properties of both formulation A and formulation I are evaluated before ageing, after ageing in a dry oven and after ageing in a humid oven.
The results are recorded in the following Tables 2, 3 and 4.
These results clearly reveal the advantage that there is in using composition E according to the invention as chain extender in comparison with 1,4-butanediol, the product most widely used for this purpose.
Number | Date | Country | Kind |
---|---|---|---|
0350323 | Jul 2003 | FR | national |