KR19990044126A - Method for producing phenolic foam - Google Patents

Abstract

The present invention relates to the production of low density resolfoam from resol resins. This resolfomal has a density of up to 9.0 pounds (144.166 kg / m ³ ) per cubic foot and is made of halogen-free hydrocarbon blowing agents such as pentane.

Description

Method for producing phenolic foam

Not only is the recent damage of chlorofluorocarbons (CFCs) to the ozone layer and less damaging by their replacement hydrochlorofluorocarbons (HCFCs), but the recognition of the activity of these materials as greenhouse gases is not only a blowing agent for foam materials. Raised the debate about the future viability of the Development of hydrofluorocarbons (HFCs) that do not deplete ozone is underway, but the problem is a suitable candidate with acceptable properties and reasonable cost. The disadvantage of alkanes is that their conductivity is less than that of CFCs. As the trend toward high energy efficiency conditions increases, the importance of the insulating role of the foam material is increasing. Therefore, meeting these requirements as a low efficiency insulating gas is a major challenge in foam manufacturing.

Phenolic foam has been used as an insulating material for many years. Their good thermal and aged thermal properties are well known. Independent foam phenolic foams retain blowing agent gas for longer periods of time and have lower ingress than urethanes, isocyanurates and polystyrene foams. Due to the long permeability of thermal conductivity due to the low permeability of phenolic foams to blowing agents and atmospheric gases, the long term retention of thermal conductivity provides improved thermal insulation properties over the life of the product. In addition, phenolic materials are known to have excellent plasticity characteristics and low smoke emission compared to other types of foam materials.

Disclosure of the Invention

It has been found that preparing phenolic foams as alkan blowing agents produces self extinguishing resolfoals. Alkan blowing agents have significantly higher flammability than CFCs and HCFCs. Many of the foams currently being produced with non-flammable blowing agents are self flammable, and using alkanes as blowing agent for these foams will increase their flammability in the absence of flame retardant additives.

The present invention can significantly improve the techniques available in the manufacture of low density insulating materials with high flammable blowing agents. The low permeability of the phenolic matrix provides an excellent barrier to both blowing agents and air and shows excellent thermal properties even at extremely low densities. The firing properties of these materials are superior to urethane foams made from equivalent blowing agents.

Best Mode for Carrying Out the Invention

The method of the present invention,

(a) phenol formaldehyde resol resins having substantially no or almost no formaldehyde, having a water content of 4 to 8% and a viscosity in the range of 5,000 cps to 40,000 cps at 40 ° C, (b ) A foam composition comprising a blowing agent, (c) a surfactant, and (d) a catalyst;

Mixing the composition to initiate the foam and to prepare the resol foam; And

Curing the resolfoam to a density in the range of 0.5 to 9.0 pounds (8.01 to 144.166 kg / m ³ ) per cubic foot. This method makes it possible to foam phenol formaldehyde resins having high viscosity, thereby curing the foam at very low density.

Commonly used blowing agents are hydrocarbons containing aliphatic and alicyclic alkanes. Preferred blowing agents are aliphatic alkanes containing pentane. Preferably, these aliphatic alkanes contain carbon atoms not less than 4 or greater than 7. Examples include pentane, heptane, isobutane, and isopentane. In addition, unsaturated hydrocarbons such as pentane and heptane are contained.

Alicyclic (or aliphatic) hydrocarbons containing at least 4 or less than 7 carbon atoms may or may not be saturated. Exemplary saturated cycloaliphatic hydrocarbons include cyclopentane, methylcyclopentane, cycloheptane, and methylcycloheptane. Exemplary unsaturated cycloaliphatic include cyclopentene, cyclohexene, and 1,3-cyclohexadiene.

In addition, mixtures such as cyclopentane and acetone, although not preferred, may also be used. While halogen-free hydrocarbons and mixtures of CFCs and HCFCs have been proposed for foams other than resolfoam, the blowing agents for the resolfoam of the present invention are preferably free of CFCs and HCFCs.

The foam of the present invention utilizes a starting molar ratio of phenol to conventional formaldehyde, in the present invention 1: 1 to 1: 4.5. Preferably, it is prepared from resol prepared in the range of 1: 1.5 to 1: 2.5. High molar ratios of material are initially based on resins that can be treated with high formaldehyde side reactants or scavengers.

This resin is aggregated so that the resin does not have a water content. Conventional resins used to prepare resolfoam have a viscosity on the order of 4,000 to 40,000 cps and a water content of 4 to 8%. However, according to the present invention, the resin used during the preparation of the phenolic foam from the high viscosity resin preferably has a viscosity of about 5,000 to 20,000 cps at 40 ° C.

Moldable resol mixtures (resins, surfactants, blowing agents, catalysts) can be partitioned into either a batching process or a continuous process. In the batching process, the molding mixture is poured into a mold preheated to 80 ° C, sealed, and cured in an oven at 80 ° C for 20 minutes. Subsequently, while demoulding, the foam is additionally cured at 80 ° C. for 20 minutes.

In a continuous process, the molding composition is dispensed onto a carrier sheet that moves from uniformly spaced tubes and nozzles. The foam parallels are joined together as the process expands to form a continuous sheet moving through the conveyor oven at 80 ° C. The board is transferred to a separate oven for additional curing and further cured. The cured resorfoam will have a density in the range of 0.5 to 9.0 pounds (8.0 to 144.166 kg / m ³ ) per cubic foot.

Example 1 Preparation of Resol

As the resol resin used in the preparation of these foams, formaldehyde (F / P) with a molar ratio of 2.3: 1 was used, using 52% formaldehyde and 99% phenol. The reaction was carried out under basic conditions with 50% caustic solution at increased temperature. When the Ostwald viscosity of the resin reached 62 cst (measured at 25 ° C.), the reaction was cooled to neutralize with 50% aqueous aromatic sulfonic acid. The resin was passed through a thin film evaporator to reduce the moisture content from about 30% to 4-8%. The final viscosity of the resin thus prepared was 4,000 to 12,000 cps (measured at 40 ° C).

Example 2 Preparation of Resolfomal

47.75 g of a phenol resol prepared according to Example 1, having a formaldehyde / phenol ratio of 2.3, containing 7% water and a viscosity of 5,200 cps at 40 ° C., was 1: 1 ethoxylated alkylphenol It was mixed with 2.5 g of a surfactant blend of Pluronic F127 (BASF), a copolymer of Harfoam PI (Huntsman Chemical) and ethylene oxide-propylene oxide blocks. To this blend, 4.5 g of n-butane was added while stirring in a cup. This mixture was stirred until n-butane was dispersed with resol and surfactant. Next, 5 g of a catalyst consisting of a blend of toluene, xylene sulfonic acid, diethylene glycol, and resorcinol was added while stirring rapidly. The contents of the cup were then transferred to a rectangular steel mold of volume 8 × 8 × 2 in ³ (203 × 203 × 51 mm ³ ) preheated to 75 ° C. After 20 minutes, the foam was demoulded and further cured at 70 ° C. for 3 hours. The properties of the final foams are shown in Table 1. The foam had a density of 1.54 pcf (24.668 kg / m ³ ) and was found to be 0.145 Btu.in/hft ² ° F. (0.021 w / mK). The foam sample was placed on a Bunsen burner in the laboratory. When removed from the burner flame, the foamy flame was extinguished.

Example 3 Preparation of Resolfomal

In addition, 1.7 g of the surfactant in Example 2 and 38.0 g of the resol in Example 1 were mixed. Thus, 5.1 g of n-pentane was added, followed by stirring until the pentane was uniformly distributed. 5 g of the catalyst material of Example 2 was added to this blend while stirring rapidly. The final blend was transferred to a mold preheated to 70 ° C. as in Example 2. The mold was placed in an oven at 70 ° C. for 20 minutes, demoulded and further cured at 70 ° C. for 3 hours. The foam has an initial thermal conductivity of 1.12 pcf (17.941 kg / m3), 0.154 Btu.in/hft ² ° F (0.22 w / mK), and 0.166 Btu.in/hft ² ° F (0.24 w / mK) after 200 days of aging. ) Had thermal conductivity.

Example 4 Preparation of Resolfomal

In addition, 30.0 g of the blend of the resol of Example 1 and the surfactant of Example 2 were mixed with 5.0 g of n-pentane containing 2 mass% of perfluoroalkane (3M working fluid 5050) at a total of 3.5%. It was. To this, 5.0 g of the catalyst of Example 2 was added while stirring rapidly. The final mixture was transferred to a mold preheated to 80 ° C. as described in Example 2 and then the mold was transferred to an oven preheated to 80 ° C. After 20 minutes, the foam demolded, and the foam had a density of 0.87 pcf (13.94 kg / m ³ ) and a thermal conductivity of 0.171 Btu.in/hft ² ° F. (0.025 w / mK).

Example 5 Preparation of Foam (Control)

20 g Alkapol SOR 490 (Rhone Poulenc) and 4 g n-butane were added. To this mixture, 20 g of Mondur MR (Mobay) was added. This mixture was mixed thoroughly. Next, 4 drops of Dabco T9 (Air Products) were added while stirring the mixture. The blend was then moved from the cup to a flat aluminum foil sheet and cured.

The foam sample was placed in a Bunsen burner flame. Upon removal, the foam continued to burn vigorously.

Test result Example Density pcf (kg / m ³ ) Initial Thermal Conductivity Btu.in/hft ² ℉ (w / mK) Thermal conductivity after 200 days at room temperature Btu.in/hft ² ℉ (w / mK) Flammability 2 1.54 (24.668) 0.145 (0.021) 0.166 (0.024) X 3 1.12 (17.941) 0.154 (0.022) 0.166 (0.024) - 4 0.87 (13.940) 0.171 (0.025) - - 5 - - - O

X = material is digested

O = material retains flame

Table 1 shows that low density resolfoam can be prepared with an alkane blowing agent that does not deplete ozone. Both the initial thermal conductivity and the thermal conductivity after 200 days were excellent and showed high thermal efficiency of the low density resol foam. Furthermore, as shown in Table 1, the foam of Example 2 had excellent flame resistance and was extinguished upon removal of the flame source, whereas Comparative Example 5, which is a rigid polyisocyanate foam, continued to burn even upon removal of the flame. It was.

The present invention relates to a process for producing low density phenolic foams having good thermal properties, high heat retention and good plastic properties. This method uses a blowing agent that does not deplete ozone.

Claims (10)

(a) phenol formaldehyde resol resins having substantially no or almost no formaldehyde and having a water content of 4 to 8% and a viscosity in the range of 4,000 cps to 40,000 cps at 40 ° C. (b) halogen-free hydrocarbon blowing agents, (c) surfactants, and (d) providing a foam composition consisting of a catalyst; Mixing the composition, starting the foam to produce a resol foam; And A method of making an independent foam resolfoam comprising curing the resolfoam to a density ranging from 0.5 to 9.0 pounds per cubic foot (8.01 to 144.166 kg / m ³ ). The method of claim 1, The blowing agent is a method for producing an independent foam resol foam, characterized in that the aliphatic or alicyclic alkanes. The method of claim 1, The blowing agent is a method for producing an independent foam resol foam, characterized in that it comprises 4 to 7 carbon atoms. The method of claim 1, The blowing agent is a method for producing an independent foam resol foam, characterized in that the saturated or unsaturated. The method of claim 1, The blowing agent is a method for producing an independent foam resol foam, characterized in that the pentane, isopentane, or cyclopentane. The method of claim 1, The resol resin has a viscosity in the range of 5,000 to 20,000 cps at 40 ℃ a method for producing an independent foam resol foam. The method of claim 1, Phenolfoam density is a method for producing an independent foam resol foam, characterized in that the range of 0.5 to 2.0 pounds (8.01 to 32.037 kg / m ³ ) per cubic foot. The method of claim 1, The phenolic foam density ranges from 0.7 to 1.8 pounds per cubic foot (11.21 to 28.833 kg / m ³ ). Low density resol foam prepared according to the method of claim 1. A low density resol foam prepared according to the method of claim 5.