Selection of post-curing catalyst for rigid polyurethane HFO foaming system

Selection of post-curing catalyst for rigid polyurethane HFO foaming system

SolsticeTM LBA (HFO-1233zd, 1-chloro, 3, 3, 3 trifluoropropylene) is the fourth generation low global change product first launched by Honeywell. Warming Potential (GWP) foaming agent is suitable for foaming polyurethane insulation materials in the fields of household appliances, building insulation, cold chain transportation and industrial insulation. It is the best choice for CFC, HCFC, HFC and other non-fluorocarbon foaming agents. Best alternative foaming agent. It is a new generation foaming agent suitable for the polyurethane foaming industry that can meet various process and environmental protection requirements at the same time. It has the characteristics of high efficiency, energy saving, non-flammability, no volatile organic compounds, low global warming potential, safety and environmental protection. After continuous optimization of formula and process parameters, polyurethane foam made with SolsticeTM LBA, a new generation of high-efficiency, energy-saving and environmentally friendly foaming agent, has a better thermal conductivity than the existing foaming agent system (245fa and cyclopentane). And the energy consumption level of the whole machine is 7% (compared with the 245fa system) and 12% lower in thermal conductivity than the same model of 245fa and cyclopentane system refrigerators.

(Compared with the cyclopentane system), and the overall energy consumption is reduced by 3% (245fa) and 7% (cyclopentane).

Although LBA foaming agent has many of the above advantages, it also faces some problems in practical application. From the perspective of our catalyst, the main problem is: halogen-containing foaming The deactivation of the catalyst caused by the decomposition of the agent, so traditional catalysts are not suitable in the LBA system, but the fact of global warming makes us have to choose LBA, that is, a foaming agent with an ODP value of 0; a global warming potential GWP of less than 5 , can meet the environmental protection requirements of both the Montreal Protocol and the Kyoto Protocol, so the catalyst can only re-select a new catalyst system suitable for this type of blowing agent.

The specific case analysis will be carried out below. Before the specific case analysis, the comparison method will be explained as follows: "Stability" refers to foamable combinations other than isocyanates. A premix of all components will have sufficient activity after 2 weeks of heat aging (in a sealed container) in an oven set to 50°C. During the aging process, hydrofluoroolefin (HFO) blowing agents may decompose, causing the premix to lose activity. This deactivation can be measured using standard FOMAT equipment and measuring the foam rate of rise curve, which involves recording height versus time and foam rise rate versus time during the polymerization process. Deactivation was measured by monitoring changes in the time (in seconds) for the foam to reach 80% of the maximum height achieved at different times during the aging process. Improvements in catalyst performance can then be measured by recording the change ΔT = T aging - T initial. For example, a formulation that takes 20 seconds to reach 80% of the maximum height achieved when initially prepared may experience reactivity decay after two weeks of storage at 50°C and then take 30 seconds to reach 80% of the maximum height achieved ( Measured by FOMAT device). Then ΔT will be 10 seconds. Therefore, when comparing catalyst compositions, smaller changes in ΔT are required because such smaller changes are associated with lower activity losses during aging. Smaller changes in ΔT mean, for example, that a suitable spray foam formulation can still produce foam after aging without the need to add additional fresh catalyst to the premix to prevent the reaction mixture from sagging, dripping or collapsing during application . To obtain a stable foam formulation, it is preferred that the ΔT change in reactivity be less than about 7 seconds. More preferably the reactivity ΔT change is less than about 5 seconds, less than about 4 seconds and within a

Less than about 3 seconds in some cases.

The specific implementation is as follows: add about 100g of the above premix to a plastic container and seal it, and adjust it in an oven in the sealed container at 50°C for 7 or 14 days. The sample is allowed to equilibrate at room temperature and then mixed with corresponding amounts of isocyanate (usually about 25g polyol premix and 25g isocyanate) under vigorous mechanical stirring provided by a mechanical mixing blade at approximately 3000 rpm. Measure the foam rise under sonar detection equipment (FOMAT model V3.5 and standard software included with the FOMAT equipment) and record the selection time for each case. The selection time is measured in seconds and represents the time required for each foam to reach 80% of its full height. Time record 1 is the selection time for the assembled and immediately foamed premix, T2 is the selection time after conditioning at 50°C for 7 days, and T3 is the selection time after conditioning at 50°C for 14 days. ΔT is the reactivity decay or the difference between T3 and T1. Under these conditions, a ΔT of less than 5 seconds is required to have adequate system stability.

Table 1 shows the basic formula in the implementation process.Direct correlation data is obtained from OMAT reactivity assessments (ΔT, or the increase in time required for the foam to reach 80% of its maximum height) and actual foam formulation performance. Mix all components of the polyol premix of the formulation shown in Table 2 together in a metal bucket and mix with a pneumatic mixer for a few minutes before spraying on site with a sprayer. The square cardboard is bolted to a wooden pallet structure that is horizontal to the floor. Reactivity measurements were made by spraying a small amount into a bucket and using a wooden spatula to measure emulsification time, linear gel time, and tack dry time (according to the method described below). Reactivity measurements in these spray tests were performed in triplicate and the average value for each sample was recorded. Initial reactivity measurements were taken on the same day as the polyol premix was formulated. Reactivity measurements on aged samples were prepared by crimping a 5-gallon bucket with a fully formulated polyol premix and placing the bucket in a 50°C oven for 2 weeks.

The specific case analysis will be carried out below. Before the specific case analysis, the comparison method will be explained as follows: "Emulsification time" is when the spray liquid starts to react and foam on the substrate. The required time, in seconds. The preferred emulsification time for spray foam is 0.2

to 3 seconds. If the emulsification time is too long, the formula will not have enough viscosity to stay in the desired location and may drip or run off or off the substrate. "Linear Gel Time" is measured as the time (in seconds) required for a sprayed liquid to react sufficiently for the liquid to begin gelling, and can be pulled out of the foam by touching it with a spatula and pulling. Stay away from bubbles. Preferably, the linear gel time is between 4 seconds and 15 seconds. If the linear gel time is less than 4 seconds,

The foaming material may gel before rising, creating pressure in the foam. If the linear gel time is greater than 15 seconds, the foam may sag or fall back on itself if the polymerization reaction does not proceed to the point where the foam can bear its own weight. “Non-stick time” refers to the time (in seconds) required for the spray liquid to react until the foam material no longer sticks to the tongue depressor when the foam surface is gently tapped. The non-stick time is preferably 5 to 20 seconds.

Table 4 shows the test data obtained from the formula in Table 2. The results illustrate the significant attenuation of the reactivity of the catalyst system after being stored at 50°C for two weeks.

Milk white time （S）	Two weeks of aging milky time (S)	Linear gel time (S)	Two weeks of aging linear gel time （S）	Non-stick time （S）	Two weeks of aging non-stick time (S)
1.2	3.6	4.9	20.4	7.5	30.6

Table 5 shows the test data obtained from the formula in Table 3. The results show that the stability of this catalyst system is better than that of the catalyst system in Table 2.

Milk white time （S）	Two weeks of aging milky time (S)	Linear gel time (S)	Two weeks of aging linear gel time （S）	Non-stick time （S）	Two weeks of aging non-stick time (S)
1.4	1.6	7.5	10.5	11.7	17.1

This catalyst combination can be used to produce any rigid insulating foam, and is particularly useful in spray foam, appliance insulation, insulating building panels and closed-cell rigid polyurethane foams of various other insulation products. Particularly suitable for improving the stability of systems containing hydrohaloolefin blowing agents, such as HFCO-1234ze (trans 1,3,3,3-tetrafluoroprop-1-ene) and HFCO-1233zd

At least one of (trans-1,3,3,3-tetrafluoroprop-1-ene). 1-propene, 1-chloro-3,3,3-trifluoro) and other HFOs.

TechnicalSupport:183-0190-3156

1.4 1.6 7.5 10.5 11.7 17.1

This catalyst combination can be used to produce any rigid insulating foam, and is particularly useful in spray foam, appliance insulation, insulating building panels and closed-cell rigid polyurethane foams of various other insulation products. Particularly suitable for improving the stability of systems containing hydrohaloolefin blowing agents, such as HFCO-1234ze (trans 1,3,3,3-tetrafluoroprop-1-ene) and HFCO-1233zd

At least one of (trans-1,3,3,3-tetrafluoroprop-1-ene). 1-propene, 1-chloro-3,3,3-trifluoro) and other HFOs.

TechnicalSupport:183-0190-3156

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