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Method of molding rigid polyurethane foams with enhanced thermal conductivity

A rigid polyurethane and foam technology, applied in the field of foam preparation, can solve the problems of increasing foam, affecting foam expansion density, etc., and achieves the effects of reducing dosage, optimizing ratio, and reducing absolute dosage

Active Publication Date: 2009-01-21
DOW GLOBAL TECH LLC
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, limitations remain in modifying these formulations to optimize the processing and thermal insulation of the foam
Another problem is that due to gas diffusion increasing the λ of the foam over time
There is also the issue of product consistency due to changes in processing conditions, especially changes in atmospheric pressure due to geographic and / or weather conditions, and affect foam expansion and its density

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0110] The formulations of Examples C1 and C2 were modified by reducing the water content of Voratec SD 308 and adding Polycat 5 and Polycat 8 (Table 2). And slightly increase the amount of cyclopentane to compensate for the reduced water. A significant reduction (5%) in thermal insulation (λ) was observed for the foam of Example 1 compared to the foams of Examples C1 and C2. After expansion values ​​are also significantly reduced compared to the reference foams of C1 and C2. This means that the demold time of the freezer made with the foam of Example 1 will be shorter. If the same PU formulation (comparative example C3) is molded at a reference pressure of 1000 mbar, this results in equal lambda but much higher molded densities and post-swells. High densities are not economically viable and they also give unacceptable foaming pressures (approximately 1.8 bar) to the mold walls.

[0111] Table 2

[0112] Example

1

C3

Polyol Formulation A

s...

Embodiment 2 and 3

[0116] In Example 2, the formulation of Example 1 was modified by further adding catalyst. Example 3 has a completely different combination of polyols. The amount of isocyanate was balanced to maintain an index of 115. The formulations and the properties of the resulting foams are shown in Table 3. Both examples show a significant improvement (>6%) in thermal conductivity compared to comparative examples C1 and C2. And the post-expansion when demoulding in 5 minutes is smaller than that of the comparative example when demolding in 7 minutes. Surprisingly, these properties were achieved without negatively affecting molded density and foam compressive strength.

[0117] table 3

[0118] Example

[0119] lambda (24℃)

Embodiment 2

[0120] The faster gel times in Examples 2 and 3 result in improved thermal insulation (λ) over Example 1. Additionally, the post-expansion data for Examples 2 and 3 were improved relative to Comparative Examples C1 and C2. The addition of aromatic polyols (Example 3 vs. Example 2) resulted in a further reduction in lambda. Rapid gelling systems with high aromaticity are therefore preferred in the present invention.

[0121] In the foams of Examples 3 and 4, the amount of gas was 0.281 moles, of which 20.0% was CO 2 .

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PUM

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Abstract

The present invention is to a molded rigid polyurethane foam for application in appliance, having a reduced thermal conductivity at densities between 33 and 38 kg / m<3> and a process for the production of such foams. The molded rigid polyurethane foam have a ratio of applied foam density (kg / m3) to lambda (mW / mK), measured at 10 DEG C, 24 hours after foam production from 1.65 and to 2.15 and are obtained by the process of injecting into a closed mold cavity under reduced pressure a reaction mixture at a packing factor of 1.1 to 1.9 and the reaction mixture comprises: A) an organic polyisocyanate; B) a physical blowing agent, C) a polyol composition containing at least one polyol with a functionality of 3 or greater and a hydroxyl number between 200 and 800 and a water content of 0 to 2.5 weight percent of the total polyol composition; D) catalyst and E) auxiliary substances and / or additives.

Description

technical field [0001] The present invention relates to a molded rigid polyurethane foam for use in appliances having a reduced thermal conductivity and a reduced demoulding time at a density between 33 and 38 kg / m3, the invention also relates to this Preparation method of foam. Background technique [0002] The conventional preparation method of polyurethane foam moldings is: introducing a polyurethane reactive mixture containing blowing agent and water into the mold cavity; during the polyaddition reaction of isocyanate and isocyanate reactive component, the blowing agent is released in the mixture; The reaction mixture was allowed to foam and fill the cavity. [0003] Rigid polyurethane molded foams, including those for consumer use, are well known in their preparation and characteristics. See, eg, G. Oertel et al., Polyurethane Handbook, 2nd Edition, Hanser Verlag, 1993. The polyurethane foam mixture is typically injected into the mold cavity at atmospheric pressure. ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C08G18/08C08J9/12
CPCC08G2101/0025C08J9/14C08J2205/10C08J2375/04C08G2101/005B29C44/38C08J2203/142C08J2203/14C08J2203/12C08G18/4829C08G18/7664C08G18/482C08G2110/0025C08G2110/005C08G18/08C08J9/12
Inventor H·A·G·德福斯V·帕伦蒂
Owner DOW GLOBAL TECH LLC
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