JPS6357448B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to a method for producing polyurethane foam, and in particular to an improvement in the method for producing polyurethane foam that is applied to heat insulating materials for chemical reaction equipment, piping, and the like. [Prior Art] Rigid polyurethane foam is lightweight, has excellent heat insulation properties, and can be molded and processed into any shape, so it is often used as heat/cold insulation for chemical plant equipment, piping, etc. Halogen ions of halogen compounds added as flame retardants are liberated in water in the presence of moisture, causing corrosion of metals that come into contact with polyurethane foam. In particular, in the case of austenitic stainless steel, which is widely used as a corrosion-resistant material for nuclear reactors, chemical reaction equipment, and piping, when tensile stress is applied in the presence of halogen ions such as chlorine ions, the corrosion-resistant passive film is damaged. Corrosion accompanied by cracking (called stress corrosion cracking) may occur, leading to unexpected accidents that are difficult to predict. In order to eliminate the disadvantages of the polyurethane foam heat insulating material in use, it is known to add sodium silicate to a polyurethane foam composition and to foam and harden the composition. This polyurethane foam insulation material containing sodium silicate constitutes a battery of alkali metal and iron, and the alkali metal serves as an anode and preferentially combines with halogen ions, causing a reaction between iron and halogen ions. In addition, the silicate ions form a passive film on the metal surface as iron silicate, which prevents the diffusion of halogen ions into the metal, which has the effect of controlling the corrosion effect on the metal. Based on the above facts, ASTM C 795:
Chemical analysis values according to ASTM C 871 for insulation materials used in austenitic stainless steel.
7.0 to 11.7, soluble chlorine and soluble (Na+
The content of SiO ₃ ) is set within the permissible range as shown in Figure 1, and it is also stipulated that the product must pass the Wick test of ASTM C 692. However, when producing polyurethane foam containing sodium silicate, since sodium silicate is soluble, it easily dissolves in an aqueous solution or water contained in polyurethane raw materials (mainly polyhydroxy compounds), and the pH of the polyurethane foaming stock solution increases.
(basicity), it promotes the polyurethanization reaction between polyhydroxy compounds and polyisocyanates, and disrupts the balance between foaming and resin formation, resulting in fine air bubbles, low thermal conductivity, and heat insulation properties. The disadvantage is that a superior polyurethane foam cannot be obtained. [Problems to be Solved by the Invention] The present invention provides a method for using a polyurethane foam insulation material without causing corrosion or stress corrosion cracking in the metal to be insulated, and without impairing the insulation performance of the polyurethane foam. The main purpose of this invention is to provide a method for producing polyurethane foam that does not require a polyurethane foam. [Means for Solving the Problems] In order to achieve the above object, the present invention selects a sodium silicate cullet that is sparingly soluble in water in place of the sodium silicate, and prepares a polyurethane foam composition in the presence of the sodium silicate cullet. The above-mentioned problems are solved by foaming and curing. That is, the present invention provides a polyhydroxy compound,
A method for producing polyurethane foam from a polyisocyanate, a catalyst, a blowing agent, a foam stabilizer and other additives, which is characterized by foam curing in the presence of sodium silicate cullet. The sodium silicate cullet used in the method of the present invention is an intermediate in the manufacturing process of sodium silicate, and is a mixture of silica sand and soda ash, melted by heating until it becomes transparent, cooled, and then crushed. is anhydrous sodium silicate (Na ₂ O・SiO ₂ ,
_{What is} the above _- mentioned soluble sodium silicate (water glass ₎ ? They are different both scientifically and physically. [Function] In the method of the present invention, since sodium silicate cullet, which is sparingly soluble in water, is used, it hardly dissolves in the process of producing polyurethane foam, and therefore does not have an adverse effect on the foaming and curing reaction of polyurethane foam. In addition, most of the sodium silicate cullet, which is poorly soluble in water, is dispersed in the foamed and hardened polyurethane foam, and when it comes into contact with water, it gradually dissolves into sodium silicate, causing corrosion of the metal to be insulated. It exhibits the same effect as sodium silicate in suppressing stress corrosion cracking and stress corrosion cracking. [Embodiments of the invention] The polyhydroxy compounds used in the production of the polyurethane foams of the invention are polyether polyols having at least two primary and/or secondary hydroxy groups as terminal groups, which are already known in polyurethane chemistry. or polyester polyols, specifically glycols, polyhydric alcohols such as glycerin, pentaerythritol, sorbitol, and sucrose, amino alcohols such as triethanolamine,
Polyether polyols made by ring-opening addition of ethylene oxide and/or alkylene oxides such as propylene oxide to one or a mixture of amines such as ethylenediamine, tolylene diamine, and diaminodiphenylamine, and the above polyhydric alcohols and adipic acid and phthalic acid. It is a polyester polyol produced by a condensation reaction with a low molecular weight carboxylic acid such as. These polyhydroxy compounds may be used alone or in combination of two or more. Polyisocyanate is an aliphatic or aromatic organic compound having at least two isocyanate groups as terminal groups, specifically tolylene diisocyanate, crude MDI, polymethylene polyphenylene polyisocyanate, and the above polyhydroxy Isocyanate prepolymers having isocyanate groups as end groups in which compounds are added to these polyisocyanates are suitable. Active hydrogen in the composition used in the present invention 1
It is preferable to use an amount that gives 0.8 to 8 equivalents of isocyanate groups based on the equivalent weight, and in some cases, it may be used in an amount that gives 10 equivalents. Catalysts are amines and organometallic compounds used in conjunction with amines. Specifically, triethylamine,
N,N,N',N'-tetramethylethylenediamine, N,N,N',N'-tetramethylpropylenediamine, N,N,N',N'-tetramethyl-1,
Alkylamines such as 3-butanediamine, N,
Alicyclic amines such as N-dimethylcyclohexylamine, N,N-diethylcyclohexylamine, N,N-dimethylethanolamine, N,N
- Alkanolamines such as diethylethanolamine, triethanolamine, tetrakis-2-hydromexyethylethylenediamine, 2,4,
Alkylaminoalkylphenols such as 6-tris(dimethylaminomethyl)phenol, N-
Methylmorpholine, N-ethylmorpholine,
Amines such as heterocyclic amines such as N,N-dimethylpiperazine, triethylenediamine, N,N',N-tris(3-dimethylaminopropyl)-S-hexahydrotriazine, dibutyltin dilaurate, dibutyltin acetate, starch Organometallic compounds such as eggplant octoate and potassium octoate, which are known as polyurethanization or isocyanate trimerization reaction catalysts, can be used as they are, and these catalysts may be used alone or in combination.
and a mixture of two or more. There are two types of blowing agents used in the present invention: reactive blowing agents and inert blowing agents. A typical example of the former is water, which reacts with isocyanate to generate carbon dioxide gas. The latter is gasified by the heat of the polymerization reaction of a polyhydroxy compound and a polyisocyanate or a polyisocyanate, and includes halogenated hydrocarbons such as trichloromonofluoromethane and methylene chloride. The foam stabilizer is preferably a conventionally known siloxane and polyoxyalkylene copolymer. Additives such as flame retardants may optionally be present in the compositions used according to the invention. Preferred flame retardants are tris-(2-chloroethyl) phosphate, tris(2,3-dichloropropyl)
phosphate, tris(2,3-dipromopropyl) phosphate, diethyl N,N-bis(2-hydroxyethyl)aminomethyl phosphonate, diethyl N,N-bis(2-hydroxypropyl)aminomethyl phosphonate, These include halogenated condensed phosphate esters. The amount of sodium silicate cullet used in the production of the polyurethane foam of the present invention is appropriately determined depending on the soluble chlorine contained in the polyurethane foam composition. The content is preferably 0.1% by weight or more. If the amount is less than this, the soluble (Na+SiO _{3 )} shown in FIG. The soda cullet may be premixed with the polyhydroxy compound premix or the polyisocyanate component or with each component, or alternatively may be mixed simultaneously with the mixing of each component. Foaming methods such as injection foaming, spray foaming, conventional foaming, flow foaming, etc. can be used as is to produce polyurethane foam, and polyurethane foam can also be produced in the form of slabs, molded products, laminates, etc. The silicate soda cullet powder may be surface-treated using fatty acids, resin acids, etc. Next, the present invention will be explained in more detail with reference to Examples and Comparative Examples. Unless otherwise specified, parts are by weight. Example (1), Comparative Examples (1) to (2) 70 parts of pentaerythritol polyol (hydroxyl value: 410) and amine polyol (hydroxyl value: 770) ) 30 parts, silicone B8404 (manufactured by Goldschmidt Company) 1.2 parts, triethylenediamine
0.15 parts, dibutyltin dilaurate 0.15, water 1.5 parts,
20 parts TCE, 37 parts trichloromonofluoromethane,
Sodium silicate cullet fine powder (manufactured by Nippon Kagaku Kogyo Co., Ltd.: Silbon 330) 16 parts (Example 1), powdered sodium silicate (manufactured by Nippon Kagaku Kogyo Co., Ltd.: powdered sodium silicate) 16
(Comparative Example 2) or without (Comparative Example 1), a premix was prepared, and 1167 parts of Crude MD was added thereto and mixed with stirring to obtain a foam. After leaving this foam at room temperature for 24 hours, we cut it and inspected the inside. As a result, the foam to which the silicate soda cullet fine powder was added (Example 1) showed no problems such as cracks, similar to the foam without additives (Comparative Example 1). It had an extremely good foam with a fine bubble structure without any bubbles, but the foam with powdered sodium silicate added
Many cracks occurred and it had no practical value. (See Table 1 and Figures 2, 3, and 4)

[Table] Example (2) Polyether polyol with a hydroxyl value of 450 containing seurose and propylene oxide as main components
To 100 parts, 1.5 parts of silicone L5420 (manufactured by Nippon Unicar Co., Ltd.), 2.0 parts of N,N-dimethylcyclohexylamine, 0.1 part of dibutyltin dilaurate, 40 parts of trichloromonofluoromethane, fine powder of sodium silicate (manufactured by Nihon Kagaku Kogyo Co., Ltd.: Silvon) 330)
A premix was prepared by adding 0.3 part of the premix, and this was reacted with 120 parts of an isocyanate prepolymer (isocyanate group content: 30.5%) prepared from the polyether polyol and tolylene diisocyanate to obtain a foam. After leaving this foam at room temperature for 48 hours, the density and compressive strength were determined according to JIS
A9514, ASTM C 871 for chemical analysis, ASTM C 692 for stress corrosion cracking test (Witsku test)
The results are shown in Table 2. Since polyurethane foam does not absorb or evaporate water, use quartz wool that has been thoroughly washed with pure water to ensure sufficient evaporation of water and concentration of soluble components at the contact surface between stainless steel and polyurethane foam. I made it. As a result of the test, no stress corrosion cracking occurred in any of the polyurethane foams tested. Example (3) Silicone L5420 is added to 60 parts of a sorbitol-based polyether polyol with a hydroxyl value of 500 and 40 parts of a sorbitol-based polyether polyol with a hydroxyl value of 450.
1.5 parts, triethylamine 1.2 parts N, N, N', N'-
A blemish was prepared by adding 1.0 parts of tetramethylpropylene diamine, 12 parts of tris-(2-chloroethyl) phosphate, 40 parts of trichloromonofluoromethane, and 28 parts of fine powder of sodium silicate.
130 parts of crude MDI was added to this and mixed with stirring to obtain a foam. This foam was tested in the same manner as in Example (2). The results are shown in Table 2. Example (4) 70 parts of a polyether polyol whose main components are sorbitol with a hydroxyl value of 450 and ethylene oxide and propylene oxide, and 30 parts of a polyether polyol with a hydroxyl value of 510 whose main components are glycerin and propylene oxide. 1.5 parts of silicone B8404 (Gold Schmitt Company),
2.0 parts of N,N-dimethylcyclohexylamine,
0.02 parts of dibutyltin dilaurate, 8 parts of chlorinated condensed phosphate ester (manufactured by Daihachi Chemical Industry Co., Ltd.: CR509),
A premix was prepared by adding 40 parts of trichloromonofluoromethane and 2.8 parts of fine powder of sodium silicate, and this was reacted with 120 parts of crude MDI to obtain a foam. This foam was tested in the same manner as in Example (2). The results are shown in Table 2. Example (5) The amount of the fine powder of sodium silicate cullet in Example 3 was increased to 5.6 parts and foamed to obtain a foam. This foam was tested in the same manner as in Example (2). The results are shown in Table 2. Example (6) Polyether polyol used in Example (4)
A premix was prepared by adding 1.5 parts of silicone B8404, 2.0 parts of N,N-dimethylcyclohexylamine, 0.01 part of dibutyltin dilaurate, 98 parts of CR50, and 40 parts of trichloromonofluoromethane to 100 parts. This was reacted with 141 parts of crude MDI mixed with 13.9 parts of fine powder of soda silicate to obtain a foam. This foam was tested in the same manner as in Example (2). The results are shown in Table 2.

[Table] [Effects of the Invention] As described above, according to the present invention, since the silicate soda cullet, which is sparingly soluble in water, is used, it hardly dissolves in the process of manufacturing polyurethane foam, and therefore, the polyurethane foam There is no adverse effect on the foam curing reaction. Moreover, in the foamed and hardened polyurethane foam, most of the sodium silicate cullet, which is sparingly soluble in water, is dispersed as is, and when it comes into contact with water, it gradually turns into sodium silicate and is eluted. The effect of suppressing corrosion and stress corrosion cracking is maximized.

[Brief explanation of the drawing]

Figure 1 is a relational diagram showing the permissible range of soluble chlorine and soluble (Na+SiO ₃ ) in insulation materials specified by ASTM C 795, Figure 2 is a tomographic diagram of the urethane foam product manufactured according to the present invention, 3 and 4 are cross-sectional views of urethane foam products manufactured as comparative examples.

Claims (1)

[Claims] 1. A method for producing polyurethane foam from a polyhydroxy compound, a polyisocyanate, a catalyst, a blowing agent, a foam stabilizer and other additives, comprising:
A method for producing polyurethane foam, which comprises foaming and curing in the presence of sodium silicate cullet. 2. The method for producing a polyurethane foam according to claim 1, wherein the polyhydroxy compound is a polyether polyol and/or a polyester polyol. 3. A patent claim in which the polyisocyanate is tolylene diisocyanate, crude MDI, polymethylene polyphenylene polyisocyanate, or an isocyanate prepolymer having an isocyanate group as a terminal group obtained by adding an equivalent amount of the polyhydroxy compound to the polyisocyanate. A method for producing a polyurethane foam according to item 1. 4. The method for producing a polyurethane foam according to claim 1, wherein the polyisocyanate is used in an amount that provides 0.8 to 8 equivalents of isocyanate groups per equivalent of active hydrogen in the composition. 5. The method for producing polyurethane foam according to claim 1, wherein the content of the sodium silicate cullet is 0.1% by weight or more based on the polyurethane foam composition.