JPH0693128A - Production of phenol resin foam - Google Patents

Abstract

PURPOSE:To produce a foam which does not corrode metal, has a high closed- cell content, and is excellent in thermal insulation properties. CONSTITUTION:A powdered basic substance in the form of flock obtd. by dispersing the substance in water and adding a fixing agent to the dispersion is added to a phenol resin in the process for producing the foam by foaming and curing the resin in the presence of an acidic curative, a blowing agent, and a foam stabilizer.

Description

Detailed Description of the Invention

[0001] The present invention relates to a method for producing a phenol resin foam having a high closed cell ratio and having a high corrosion resistance, which is used as a heat insulating material in the fields of construction and various other industries.

[Industrial applications]

[0002]

2. Description of the Related Art Conventionally, a phenol resin foam having excellent heat insulating properties, flame retardance and fireproof properties has been used as a heat insulating material in the construction and other industrial fields. However, although the phenol resin foam has such excellent performance, strong acids such as phenol sulfonic acid and sulfuric acid used as a curing agent at the time of production remain in the phenol resin foam as free acids. However, there is a drawback that it corrodes metals and the like that come into contact with this free acid. To solve this drawback, phenolic resin,
Attempts have been made to blend a metal oxide such as aluminum oxide and zinc oxide or a metal powder such as zinc, magnesium and aluminum as a neutralizing agent into a mixture of an acidic curing agent, a foaming agent and a foam stabilizer. In addition, JP-A-59-15
Japanese Patent No. 2931 describes a method of adding a carbonate having a particle size of 10 to 500 μm as a neutralizing agent to a composition component consisting of a phenol resin, an acidic curing agent, a foaming agent and a foam stabilizer. Further, JP-A-60-92337 describes a method of adding a zinc powder coated with polyvinyl alcohol by using a method for producing microcapsules.

[0003]

However, in the method of blending a metal oxide such as aluminum oxide or zinc oxide or a metal powder such as zinc, magnesium or aluminum, the metal oxide or metal powder is a phenol resin mixture. It is difficult to mix them sufficiently uniformly, and since the basicity is weak, the free acid remaining in the phenol resin foam cannot be sufficiently neutralized, and the solution of corrosion resistance is insufficient. The method of adding a carbonate having a particle size of 10 to 500 μm as a neutralizing agent to a composition component consisting of a phenol resin, an acidic curing agent, a foaming agent and a foam stabilizer described in JP-A-59-152931 is an acidic curing agent. Reacts with the neutralizing agent, curing of the phenolic resin around the neutralizing agent is delayed, and an imbalanced state is created in the bubble film that constitutes the bubbles, causing destruction, increasing the number of closed cells and increasing the number of open cells, and heat conduction. The rate increases and the heat insulation decreases. Further, the acidic curing agent and the neutralizing agent react with each other on the surface of the phenol resin foam, and a spot-like unpleasant pattern is generated in a portion around the neutralizing agent where the curing of the phenol resin is delayed. In addition, JP-A-6
In the method for producing a phenol resin foam, which comprises heating an uncured resol-type phenol-formaldehyde resin liquid in a water-containing state in the presence of an acid curing agent and a foaming agent to foam and cure it, as described in 0-92337, zinc powder is polyvinyl alcohol. The method of adding microcapsules coated with
Since zinc powder is microencapsulated with polyvinyl alcohol, there are problems such as great labor and cost.

[0004]

Means for Solving the Problems The above-mentioned problems are solved in a method for producing a phenol resin foam by foaming and curing in the presence of a phenol resin, an acidic curing agent, a foam stabilizer and a foaming agent optionally added according to the present invention. A method for producing a phenol resin foam, in which a powdery basic substance obtained by dispersing in water and then forming a floc by adding a fixing agent is added to a phenol resin. The present invention will be described below.

The phenolic resin used in the present invention contains phenols such as phenol, cresol, xylenol, paraalkylphenol, paraphenylphenol, resorcin and modified products thereof, and aldehydes such as formaldehyde, paraformaldehyde, furfural and acetaldehyde in water. It is a resol type that is produced by reacting with an alkaline catalyst such as sodium oxide, potassium hydroxide, calcium hydroxide, hexamethylenetetramine, trimethylamine and triethylamine.

Examples of the acid curing agent used in the present invention include inorganic acids such as sulfuric acid and phosphoric acid, and organic acids such as benzenesulfonic acid, paratoluenesulfonic acid, naphtholsulfonic acid and phenolsulfonic acid.

In the present invention, as a foaming agent optionally used, low boiling point aliphatic hydrocarbons such as pentane, hexane and heptane, ethers such as isopropyl ether, chlorinated aliphatic hydrocarbons such as methylene chloride and trichlor. Examples thereof include fluorine compounds such as monofluoromethane and trichlorotrifluoroethane, or a mixture of these compounds.

Examples of the foam stabilizer used in the present invention include foam stabilizers such as silicone type nonionic surfactants.

Examples of the powdery basic substance used in the present invention include carbonates such as calcium carbonate, magnesium carbonate, barium carbonate and zinc carbonate having an average particle size of 10 μm or less. The powdery basic substance need not be limited to one type, and two or more types can be used in combination. The amount used is 100 parts by weight of phenolic resin,
It is 0.3 to 100 parts by weight. When it is 0.3 parts by weight or less, the neutralizing effect is insufficient, which is not preferable.

The fixing agent used in the present invention is a sulfuric acid band and a polyacrylamide-based polymer. As the polyacrylamide-based polymer, any of anion-modified polyacrylamide, cation-modified polyacrylamide and nonion-modified polyacrylamide can be used. .

In the present invention, the powdery basic substance is used by dispersing the powdery basic substance in water in an amount of 0.5 to 20 times in advance and adding a sulfuric acid band to the powdery basic substance 100. 0.1 to 20 parts by weight per part by weight is added and coagulated, and 0.1 to 100 parts by weight of the powdery basic substance.
Add ~ 5 parts by weight of polyacrylamide polymer to form large and strong flocs. The formed flocs may be used after removing excess water by using a coarse cloth or the like, or the flocs may be dehydrated by a centrifugal dehydrator or the like or used after drying. However, since the dried product has a lump shape, it is crushed into coarse particles before use. In the production of a phenol resin foam, the powdery basic substance may be a phenol resin, an acid curing agent, a foam stabilizer and optionally a foaming agent, which may be mixed together at the same time, but before the addition of the acid curing agent. It is preferable that the phenol resin and the floc are uniformly mixed without destroying them. For example, the formed flocs are added to the phenol resin in advance and uniformly mixed with stirring. The degree of agitation is not so strong as to completely destroy the flocs, and the extent to which the flocs are not destroyed and mixed almost uniformly is preferable as one guide. The rotation speed of the mixer is 100 to 500 rpm. However, after adding the acid curing agent, the foaming agent and the foam stabilizer, if desired, in order to make the flocs finer and more uniformly dispersed throughout the system, it is preferable to rotate the mixer at 3000 to 10000 rpm to stir. .

In the present invention, a phenol resin foam is obtained by mixing the phenol resin, the acid curing agent, the foam stabilizer, the foaming agent, the powdery basic substance and the like having the above-described composition components, heating and foaming and curing. These may be performed by a conventionally known method, but an example will be described below. Prepare three tanks, a resin tank, a foaming agent tank, and a curing agent tank. A phenol resin, a foam stabilizer, a floc, and optionally a flame retardant are put in a resin tank and mixed with stirring at 100 to 500 rpm at the rotation speed of the mixer. Prepare the foaming agent in the foaming agent tank. A curing agent is prepared in the curing agent tank. The components of the three tanks are introduced into a mixing head, and a high speed rotating mixer such as a pin type mixer is operated at 3000 to 4000 rpm. p. The mixture is uniformly stirred and mixed at m, and the mixture is discharged from a discharge port onto a face material such as paper on a conveyor belt. Next, place a face material such as paper on the upper surface of the mixture on the conveyor belt and enter the curing furnace. In the curing oven, press from above with another conveyor belt to adjust the phenol resin foam to a specified thickness, then 60 to 100
Foams and hardens under conditions of 2 ° C. and 15 minutes. The phenol resin foam discharged from the curing furnace is cut into a predetermined length.

[0013]

In the present invention, in order to neutralize the acid curing agent remaining in the phenol resin foam, a powdery basic substance having an average particle size of 10 μm or less is dispersed in water, and a sulfuric acid band is added to this. The negative charge of the powdery basic substance is neutralized and coagulated, and a polyacrylamide polymer is added to this to form large and strong flocs, which are uniformly mixed with the phenol resin in advance. By adding an acid curing agent, a foam stabilizer and a foaming agent as desired to a uniform system of powdery basic substance flocs and a phenol resin and stirring with strong shearing force to make the entire system extremely uniform, The resin is uniformly foamed and cured. As a result, neutralization of the acid curing agent remaining in the phenol resin foam is gradually and reliably performed even after the foam curing of the phenol resin without hindering the foam curing of the phenol resin. Next, the present invention will be specifically described with reference to Examples. The invention is not limited to this example.

[0014]

Example Phenolic resin: 84 parts by weight of phenol, 3
558 parts by weight of 7% formalin, calcium hydroxide 11.
1 part by weight was charged into a flask and subjected to an isothermal reaction at 90 ° C. for 60 minutes, subsequently 85 parts by weight of brominated cresol monoglycidyl ether was added, and after reacting for another 20 minutes, the pH of the reaction solution was 7.0. The reaction solution was neutralized by adding oxalic acid to 7.3 and dehydrated at 80 ° C. under reduced pressure to obtain a resol-type phenol resin containing 3.0% by weight of free phenol and 1.9% by weight of free formalin. It was Using this phenol resin, phenol foams of Examples 1 to 4 and Comparative Examples 1 and 2 below were obtained, and the physical properties were measured and shown in Table 1.

Example 1 As a powdery basic substance, 100 g of calcium carbonate having an average particle diameter of 2.6 μm was added to 300 m of water.
1 g, and 3 g of a sulfuric acid band was added thereto, mixed by stirring, and then 0.8 g of cation-modified polyacrylamide was added and mixed by stirring to form flocs. Excessive water content of the flocs was removed with a filter paper, dried and crushed into coarse particles. With respect to 100 parts by weight of phenol resin, 7 parts by weight of the obtained coarse-grained flocs converted to calcium carbonate, and a foam stabilizer (L-5340 manufactured by Union Carbide Co.).
0.2 part by weight was added, and the mixture was stirred and mixed at a mixer rotation speed of 200 rpm for 5 minutes, and allowed to stand still at room temperature for 5 minutes. Then, 7 parts by weight of a blowing agent trichlorotrifluoroethane and 15 parts by weight of an acid curing agent paratoluenesulfonic acid were added to 100 parts by weight of the phenol resin, and 15 parts by weight of a para-toluenesulfonic acid was added to the mixture of the phenol resin, the floc and the foam stabilizer, and the number of rotations of the pin type mixer was 45
Stir and mix at 00 rpm for 8 seconds, then use a wooden frame (220 mm x
220 mm × 25 mm) and heated at 70 ° C. for 40 minutes to foam and cure.

Example 2 A phenol resin foam was obtained in the same manner as in Example 1 except that barium carbonate having an average particle size of 1.2 μm was used.

[Example 3] The same as Example 1 except that the mixture of the phenolic resin, the coarse-grained flocs and the foam stabilizer in Example 1 was stirred and mixed at a mixer rotation speed of 100 rpm for 10 minutes and allowed to stand at room temperature for 24 hours. A phenol resin foam was obtained in the same manner.

[Example 4] A phenol resin foam was prepared in the same manner as in Example 1 except that 15 parts by weight of floc was converted to calcium carbonate based on 100 parts by weight of the phenol resin except for trichlorotrifluoroethane. Obtained.

Comparative Example 1 A phenol resin foam was obtained in the same manner as in Example 1 except that 7 parts by weight of calcium carbonate having an average particle diameter of 2.6 μm was used in place of coarse-grained flocs.

Comparative Example 2 A phenol resin foam was obtained in the same manner as in Example 2, except that 100 parts by weight of the phenol resin was used and 0.2 parts by weight of coarse-grained flocs was converted to calcium carbonate. . Examples 1 to 4 and Comparative Examples 1 and 2
The phenol resin foam obtained in 1. was left at room temperature for 1 week, and its physical properties were measured and shown in Table 1. The methods for measuring each physical property are as follows.

[Measurement Method] Foam density: Measured according to JIS A-9514. Compressed density: Measured according to JIS A-9514. Phenol resin: 0.5 g of a phenol resin foam was cut into a cubic shape. PH of the foam was put in 100 g of distilled water at room temperature for 3 days, and then the pH of the distilled water was measured with a PH meter to measure the P of the phenol resin foam. H. Thermal conductivity: Measured according to JIS A-1413. Closed cell ratio: Measured with a Beckman type air-comparison hydrometer. Appearance: Evaluated visually.

[0022]

[Table 1]

[0023]

As can be understood from the results of Table 1, the phenol resin foam produced according to the present invention maintains the physical properties of the conventional phenol resin foam as it is,
Since the PH of the foam is almost neutral, there is no corrosion of the metal by the phenol resin foam, and the hardening of the phenol resin around the neutralizer is delayed, causing an imbalanced state in the bubble film that constitutes the bubbles and destroying it. Since it does not occur, there are many closed cells and there is an effect of excellent heat insulation.

Claims (1)

[Claims] 1. A method for producing a phenol resin foam by foaming and curing in the presence of a phenol resin, an acid curing agent, a foam stabilizer and an optional foaming agent, which comprises dispersing in water and then adding a fixing agent. A method for producing a phenolic resin foam, which comprises adding a powdery basic substance formed of flocs to a phenolic resin.