Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Cellular products or processes of preparing a cellular...
Patent
1998-09-18
1999-10-05
Cooney, Jr., John M.
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Cellular products or processes of preparing a cellular...
521132, 521170, 521172, 521173, 521174, C08J 908
Patent
active
059625422
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
It is known that polyurethane rigid foams can be blown with low-boiling alkanes. Cyclic alkanes are used to advantage here because they make an outstanding contribution to the thermal conductivity of the expanded material due to their low gaseous thermal conductivity. Cyclopentane is preferably used.
The beneficial properties when used as an insulator in domestic refrigerators have to be compared with a disadvantageous commercial situation. Thus, a specific quality of polystyrene inner container has to be used, as a result of the solvent properties of cyclopentane.
Furthermore, cyclopentane has the disadvantage, due to its relatively high boiling point of 49.degree. C., that it condenses at low temperatures such as are conventional during the use of polyurethane rigid foams as insulators in domestic refrigerators. Due to the undesired condensation of the blowing agent, a reduced pressure is produced in the cells which again has to be offset by an elevated foam strength or increased density.
Compared with the acyclic homologous pentane compounds, n-pentane and i-pentane, cyclopentane incurs higher manufacturing costs. n-pentane or i-pentane blown systems have been known for some time in the field of polyurethane rigid foams. However, the higher gaseous thermal conductivities, as compared with cyclopentane, which result in poorer thermal insulation capacity of the corresponding expanded systems is a disadvantage.
In addition, the solubility of n-pentane and i-pentane in polyols is much lower than that of cyclopentane, which has a negative effect on production reliability and the adhesion of the expanded material to covering layers.
SUMMARY OF THE INVENTION
The object of the present invention was to develop a n-pentane or i-pentane blown rigid foam in which the disadvantages mentioned above are overcome.
Surprisingly, it has now been found that polyol formulations based on aromatic amines, sucrose and propylene glycol provide expanded materials with good adhesive properties and lower thermal conductivities. The solubility of acyclic pentanes satisfies all the requirements.
DETAILED DESCRIPTION OF THE INVENTION
The present invention therefore provides a process for preparing rigid expanded materials containing urethane and optionally isocyanurate groups, characterised in that a polyurethane rigid foam is prepared by reacting react with isocyanates, containing weight of 300 to 700 based on 70 to 100 wt. % of 1,2-propylene oxide and 0 to 30 wt. % of ethylene oxide molecular weight of 400 to 1,000 based on 70 to 100 wt. % of 1,2-propylene oxide and 0 to 30 wt. % of ethylene oxide weight of 500 to 1,500 based on 70 to 100 wt. % of 1,2-propylene oxide and 0 to 30 wt. % of ethylene oxide
Amine started polyethers are preferably understood to be those based on o-toluylene diamine. This starter is preferably reacted with 1,2-propylene oxide. The molecular weight of these polyethers is preferably between 300 and 800, in particular between 500 and 600. In polyol formulations, the proportion of aromatic aminopolyether is preferably 30 to 80 wt. %, in particular 35 to 70 wt. %.
The sucrose started polyethers are preferably prepared by reaction with 1,2-propylene oxide; diethylene glycol, ethylene glycol or propylene glycol in amounts of 10 to 30 wt. % is optionally used as a co-starter.
The molecular weight is preferably between 400 and 1,000, in particular between 500 and 600. In polyol formulations, the proportion of sucrose started polyethers is preferably 10 to 40 wt. %, in particular 15 to 35 wt. %.
Propylene glycol started polyethers are also prepared by reaction with 1,2-propylene oxide.
Propylene glycol started polyethers with a molecular weight between 500 and 1,500 are preferably used, in particular between 900 and 1,100.
In polyol formulations, their proportion is preferably 5 to 30 wt. %, in particular 15 to 25 wt. %.
By using polyol formulations in accordance with the invention, n-pentane and i-pentane blown expanded materials with low thermal conductivities and good adhesion
REFERENCES:
patent: 5025039 (1991-06-01), Neuhaus et al.
patent: 5308885 (1994-05-01), Doerge
patent: 5391317 (1995-02-01), Smits
patent: 5451615 (1995-09-01), Birch
patent: 5602190 (1997-02-01), Lamberts et al.
35th Annual Polyurethane Technical Marketing Conference; "An Insight into the Characteristics of a Nucleation Catalyst in CFC-Free Rigid Foam Systems"; H. Yoshimura, et al, pp. 300-310, (1994).
Database WPI; Derwent Publications Ltd.; AN 95-085467 & JP 07 010 955 A (Polyurethane Kasei KK) (1995).
Database WPI; Derwent Publications Ltd.; AN 94-313741 & JP 06 239 956 A (Sumitomo Bayer Urethane) (1994).
Dietrich Karl Werner
Eisen Norbert
Heilig Gerhard
Bayer Aktiengesellschaft
Cheung Noland J.
Cooney Jr. John M.
Gil Joseph C.
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