JP3007002B2 - Polyol composition for polyurethane foaming and method for producing polyurethane foam - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyol composition for producing a polyurethane foam used for a heat insulator such as a refrigerator and a freezer, and a method for producing the same.

[0002]

2. Description of the Related Art In a heat insulator composed of a foam having small air bubbles in which the convection of gas in the air bubbles is negligible, the thermal conductivity of the heat insulator depends on the heat conduction by the gas present in the air bubbles and the heat conductivity of the air bubbles. It is expressed by the sum of the heat conduction by heat radiation inside and the solid heat conduction of the resin part. Therefore, once the foaming agent to be used for foaming is determined, it is important to reduce the bubble diameter to reduce the radiation component, and to reduce the density to reduce the contribution of the solid heat conduction of the resin portion. Normally, bubbles are miniaturized by introducing foam nuclei (for example, JP-A-3-54231). As the foam core,
Perfluorocarbons such as perfluoropentane have been used. Then, a polyol composition is emulsified by using perfluorocarbon as an emulsifier, and further combined with a nucleating agent such as silica gel or starch, thereby improving the effect of miniaturizing bubbles. In addition, together with HCFC123 and HCFC141B as blowing agents, 5.
There is also a proposal to make bubbles fine by using an emulsion containing 5% or less of perfluorocarbon as a bubble nucleus (Japanese Patent Laid-Open No. 5-186629).

However, in recent years, environmental destruction due to chlorofluorocarbons such as ozone depletion or global warming has become a social problem.
A major issue is the reduction and elimination of specific freon (trichloromonofluoromethane, etc.), which is a foaming agent for foam insulation such as rigid urethane foam. In addition, perfluorocarbons such as perfluoropentane have a longer lifetime in the atmosphere than specific fluorocarbons, and the lifetime is estimated to be 500 years or more. It is about to be restricted. Against this background, the production of polyurethane foams using a blowing agent such as cyclopentane, which causes less environmental destruction such as ozone layer depletion or global warming, has also been performed. However, since these foaming agents have a higher thermal conductivity of gas than fluorocarbon, it is necessary to reduce the size of air bubbles in order to lower the thermal conductivity of the obtained polyurethane foam. Further, as a production method using a salt, a method for producing a polyurethane foam in which foaming is performed by generating carbon dioxide using water of crystallization of a hydrated salt has been proposed (JP-A-6-1820, JP-A-6-18220). No. 25453)

[0004]

The use of perfluorocarbon as in the prior art to reduce the size of air bubbles to achieve low thermal conductivity increases the amount of perfluorocarbon released into the atmosphere. However, there is a problem that the contribution to global warming increases. Further, when the polyol composition is emulsified during the production, the viscosity of the polyol composition increases. For this reason, the mixing of the polyol composition and the polyisocyanate becomes insufficient or the efficiency of foaming decreases, so that the density of the foam obtained increases and the thermal conductivity is not effectively improved. There were also problems. The present invention provides a polyurethane foam having uniform and fine cells and low thermal conductivity without using perfluorocarbon.
It is a primary object to provide a polyol composition for producing a system. The second object of the present invention is to
An object of the present invention is to provide a method for producing a polyurethane foam having uniform and fine bubbles and low thermal conductivity without using perfluorocarbon.

[0005]

DISCLOSURE OF THE INVENTION The foaming polio of the present invention.
At least one selected from the group consisting of primary alcohols and secondary alcohols having 3 or less carbon atoms.
And a salt that dissolves in the alcohol. The amount of the salt is preferably 0.5 parts by weight or more based on 100 parts by weight of the polyol and an amount that forms a solution having a saturation concentration or less. The alcohol may be ethylene glycol, and the salt may be at least one selected from the group consisting of potassium carbonate, barium chloride, potassium iodide, lithium chloride, sodium bromide and calcium chloride. preferable. Further, the foaming agent contained in the polyol composition for foaming polyurethane of the present invention is preferably a fluorinated iodide hydrocarbon.

[0006] The method for producing a polyurethane foam of the present invention comprises at least one selected from the group consisting of a primary alcohol having 3 or less carbon atoms, a secondary alcohol having 3 or less carbon atoms, and water. A step of obtaining a polyisocyanate emulsion by dispersing a solution obtained by dissolving a salt in a polyisocyanate together with a surfactant, and a step of mixing the emulsion with a polyol composition to form a foam.

[0007]

The polyol composition of the present invention is obtained by dissolving a salt in a primary or secondary alcohol and converting the solution into a polyol.
Mixed with the Salt dissolved in alcohol,
When it is mixed with a polyol, it may be partially precipitated. By this precipitation, the viscosity of the polyol composition can be made lower than in the case of forming an emulsion using perfluorocarbon, and the foaming efficiency can be kept good. Further, during the resinification reaction, the salts remaining in a dissolved state in the polyol composition are also precipitated by mixing with the polyisocyanate as the dissolved alcohol reacts with the polyisocyanate. And acts as a foam nucleus together with the salt that has already been precipitated. At this time, it is necessary that the precipitation of the salt serving as the foam nucleus is progressing in an initial stage before the foaming of the foaming agent starts. Therefore, as the alcohol, a primary or secondary alcohol having a reactivity as high as or higher than polyisocyanate is used. In addition, it is preferable that the dissolved salt is rapidly precipitated at the beginning of the reaction accompanying the reaction of the alcohol. Therefore, a certain concentration or more is required, and the amount of the salt is preferably from 0.5 part or more to 100% by weight of the polyol to the saturation concentration. In particular, the alcohol solution of the salt preferably has a concentration close to a saturated solution.

In general, when a monohydric alcohol reacts with polyisocyanate, the chain length reaction does not proceed and the strength of the obtained polyurethane foam decreases. Alcohols are preferred, and divalent alcohol ethylene glycol is most preferred because of its low viscosity. As the salt to be dissolved, potassium carbonate, barium chloride, potassium iodide, lithium chloride, sodium bromide and calcium chloride, which have particularly high solubility in ethylene glycol, are preferred. Further, the alcohol having 3 or less carbon atoms contained in the polyol composition of the present invention generates heat by the reaction with the isocyanate, and the polyol and the polyisocyanate are generated.
The reaction also has the effect of accelerating the reaction with the gas and suppressing the growth of bubbles due to the connection during the reaction. In particular, in the case of a polyhydric alcohol such as erylen glycol, the viscosity increases due to the chain extension during the reaction, so that the effect of reducing the bubble diameter is obtained.

When fluorinated iodinated hydrocarbons are used as a blowing agent, the reaction between the polyol and the polyisocyanate is slowed down, and the bubble diameter is smaller than when other blowing agents are used. Becomes larger. Therefore, when such a foaming agent is used, the action of accelerating the reaction besides the bubble nucleus is added, particularly by using the alcohol composition of the present invention and the polyol composition containing the salt dissolved therein. The effect of reducing the bubble diameter of the resulting polyurethane foam is increased. Also, as a different method, in the present invention, an alcohol or water in which a salt is dissolved is dispersed in a polyisocyanate together with a surfactant to form an emulsion,
There is a method for producing a polyurethane foam in which this emulsion is mixed with a polyol composition containing a foaming agent and foamed and molded. The advantages of this method are listed below. First,
Since the original viscosity of polyisocyanate is lower than that of polyol, when the above-mentioned method of emulsifying this and using it as cell nuclei is adopted, the viscosity does not change as much as when polyol is emulsified, and the Efficiency is kept good. More importantly, besides the emulsion acting as bubble nuclei, alcohols or salts dissolved in water also act as bubble nuclei. That is, when the emulsion dissolved in alcohol or water starts to disintegrate due to the heat generated by mixing the polyol and the polyisocyanate, precipitation occurs due to the reaction between the alcohol or water and the polyisocyanate, and bubbles are generated. May work as a core.

[0010]

Now, the present invention will be described in further detail with reference to preferred embodiments. As described above, the polyol composition of the present invention is a polyol composition containing an alcohol having 3 or less carbon atoms and a salt, which is mixed with polyisocyanate to form a polyurethane. A foam is obtained. At this time, if the amount of the alcohol in the polyol composition is too large, the strength of the obtained polyurethane foam is lost. Therefore, when a monovalent alcohol is used, the amount is preferably 10 parts by weight or less based on 100 parts by weight of the polyol. Even when ethylene glycol or glycerin is used, if the calorific value is large, it is not preferable to exceed 20 parts by weight to form a good foam.

The alcohol added to the polyol composition of the present invention may be a monovalent alcohol such as methyl alcohol, ethyl alcohol, isopropyl alcohol, allyl alcohol, or divalent alcohol. Is ethylene glycol, 1,3-propanediol, and trivalent alcohol is glycerin. The salt used in the present invention can be suitably used irrespective of an organic salt or an inorganic salt as long as it is soluble in the above-mentioned alcohol in an amount of about 5 to 10% by weight or more. For example, for methyl alcohol, calcium iodide, sodium iodide, lithium chloride, lithium iodide, potassium iodide, strontium bromide, barium bromide, calcium bromide, sodium bromide, calcium nitrate, nitric acid Magnesium, copper chloride, magnesium iodide, nickel bromide, potassium benzoate, lithium benzoate, zinc benzoate, ammonium benzoate, ammonium oleate, lithium acetate, potassium acetate, potassium propionate, potassium butyrate, sodium butyrate, etc. There are salts.For ethyl alcohol, potassium chloride, potassium iodide, sodium iodide, sodium thiocyanate, strontium bromide, sodium bromide, barium iodide, calcium bromide, calcium nitrate, copper chloride, chloride Ferric, lithium bromide Magnesium iodide, there are salts such as ammonium bromide. For propyl alcohol, lithium iodide, sodium iodide, calcium bromide, copper chloride, isopropyl alcohol
For example, copper chloride or the like is used. However, since the effect as the foam nucleus decreases as the amount of the salt decreases, the effect is preferably 0.5 part by weight or more based on 100 parts by weight of the polyol.

As described above, the polyol composition of the present invention is effective in reducing the cell diameter especially when foaming is performed using a fluorinated iodide hydrocarbon as a foaming agent.
As the fluorinated iodide hydrocarbon, heptafluoro-1
-Iodopropane (boiling point 39 ° C), heptafluoro-
2-iodopropane (boiling point 39 ° C), nonafluoro-
1-iodobutane (boiling point 66-68 ° C) and the like.

In the present invention, bubbles can be made finer by adding an alcohol in which a salt is dissolved to polyisocyanate to form an emulsion and using this to form a polyurethane. As the alcohol and salt used at this time, the same ones as in the case of the above-mentioned polyol composition can be used. As salts soluble in water, not only many inorganic salts but also organic salts can be used. For example, sodium benzoate, potassium benzoate, lithium benzoate, sodium formate, potassium formate, barium formate, calcium formate, magnesium formate, zinc formate, potassium salicylate, sodium salicylate, potassium oxalate, sodium nicotinate, sodium phthalate, Sodium benzenesulfonate, copper benzenesulfonate, barium valerate, calcium isovalerate, tetraethylammonium chloride, tetraethylammonium bromide, tetraethylammonium iodide, barium ethyl acetate, calcium acetate, magnesium acetate, zinc acetate, sodium maleate, There are barium acetate, calcium acetate and the like. If the amount of alcohol and water having 3 or less carbon atoms is too small, the formed emulsion does not effectively serve as a bubble nucleus, so that it is 0.5 part by weight or more based on 100 parts by weight of the polyol used. Is preferred. Isocyanate
The surfactant to be added when emulsifying
It is possible to use those usually used as foam stabilizers. By adding such a surfactant, the reaction between the isocyanate and the alcohol having 3 or less carbon atoms or water is delayed, and the emulsion is stably present for about 10 minutes to 1 hour or more. It is stable for 1-2 hours. In order to allow sufficient time for mixing the emulsion and the polyol composition, there is a method in which water or an alcohol in which a salt is dissolved is added to the polyisocyanate immediately before mixing to form an emulsion. Even if the emulsion partially collapses and the polyisocyanate reacts with alcohol or water, most of the polyisocyanate remains if the number of alcohols and water is kept small,
Since the salt acts as a foam nucleus, the effect of making the cells finer appears.
To do so, the amount of alcohol that dissolves the salt is
Preferably, the amount is 20 parts by weight or less for 100 parts by weight of water, and 2 parts by weight or less in the case of water.

Also, the above two methods, namely,
(1) Polio containing salt and alcohol having 3 or less carbon atoms
The foaming agent used in both cases of producing a polyurethane using a water-based composition and (2) producing a polyurethane using an emulsion containing a polyisocyanate includes a carbonizing agent such as water, cyclopentane, or cyclohexane. Hydrogen, tetrahydrofuran, ethers such as 1,3-dioxolane, ketones such as acetone, aromatic compounds such as fluorobenzene and furan, and mixtures thereof can also be used. Further, as the above-mentioned polyol and polyisocyanate, materials used for general hard urethane foaming can be used. Polio
In addition to conventionally used polyester-based polyols and polyester-based polyols, many hydroxyl groups synthesized from polyhydric alcohols are used to obtain hardness or control the reactivity. Polyol having in the molecule is suitable.

The polyisocyanates used in the present invention include diphenylmethane diisocyanate, tolylene diisocyanate, xylylene diisocyanate, metaxylylene diisocyanate, hexamethylene diisocyanate, lysine diisocyanate, isophorone diisocyanate, and trimethylhexamethylene diisocyanate. And dimer acid diisocyanate are suitable, and polyisocyanate having flame retardancy added thereto is most suitable. As the catalyst used in the present invention, it is necessary to select the most effective catalyst depending on the reactivity of the urethane raw material such as a gelling catalyst, a foaming catalyst, and a retarding catalyst. Commonly used catalysts are tertiary amines and organometallic compounds. Examples of the amine catalyst include monoamines, diamines, triamines, cyclic amines, alcohol amines, and ether amines. Organotin compounds are most often used as organometallic compound catalysts. In the present invention, a general formulation catalyst is utilized. But,
Depending on the boiling point, it is necessary to use differently or mix various catalysts.

In the following specific examples, Kaolyzer No. manufactured by Kao Corporation was used as catalyst A. Kaolyzer No. 1 manufactured by Kao Corporation as catalyst B 300, TY-19 manufactured by Takeda Pharmaceutical Co., Ltd. as foam stabilizer A, aromatic amine polyether polyol as polyol A, hydroxyl value 500 mg
A polyisocyanate having an amine equivalent of 170 was used as the polyisocyanate A having a KOH / g. Of course, the present invention relates to these polyols, isocyanates, catalysts,
It is not limited to foam stabilizers.

Example 1 A polyol composition containing ethylene glycol as an alcohol having 3 or less carbon atoms, potassium carbonate as a salt dissolved therein, and cyclopentane as a blowing agent was used. Polyurethane foam
Was made. The weight ratio of the raw materials used is as follows. Polyol A / foam stabilizer A / catalyst B / water / cyclopentane / ethylene glycol / potassium carbonate / polyisocyanate = 100/3/2/1/17/5/5/13
5. First, potassium carbonate was dissolved in ethylene glycol, and this was mixed with cyclopentane, catalyst B, foam stabilizer A, and water together with polyol to obtain a polyol composition. Next, a mixture of the composition and polyisocyanate was poured into a metal container and foamed.

The cell diameter of the obtained polyurethane foam was 260 μm. The bubble diameter when ethylene glycol and potassium carbonate were not added to the polyol composition was 360 μm. Thermal conductivity is ethylene glyco-
It was 94 when expressed as a relative value when 100 when the amount of potassium and potassium carbonate were not added to the polyol composition. Excess potassium carbonate was added to the same amount of ethylene glycol, and the insolubles were filtered to obtain a saturated solution. The polyurethane foam obtained from the polyol composition using this saturated solution had a bubble diameter of 240 μm and a relative thermal conductivity of 92. Similarly, when the amount ratio of potassium carbonate dissolved in the same amount of ethylene glycol is 0.5 (value with respect to polyol A100, the same applies hereinafter), the obtained polyurethane foam has a bubble diameter of 310 μm, The conductivity was 97 in relative value. These results are summarized in Table 1. The ratio of ethylene glycol / potassium carbonate in the table is shown by the value with respect to polyol A100. The thermal conductivity is expressed as a relative value when the value when ethylene glycol and potassium carbonate were not used was taken as 100. Also,
When ethylene glycol / potassium carbonate = 5 / saturation in Table 1, the amount of ethylene glycol was set to 15 and a polyurethane foam was produced, almost the same bubble diameter and thermal conductivity were realized. No shrinkage due to a decrease in resin strength was observed.

[0019]

[Table 1]

Example 2 A polyol composition containing methyl alcohol as an alcohol having 3 or less carbon atoms, lithium benzoate as a salt dissolved therein, and cyclopentane and acetone as blowing agents was used. Thus, a polyurethane foam was prepared. The weight ratio of the raw materials used is as follows. Polyol A / foam stabilizer A / catalyst A / cyclopentane / acetone / methyl alcohol / lithium benzoate / polyisocyanate = 100/3/2/10/8 /
5/1/130. After dissolving the above amount of lithium benzoate in methyl alcohol, this was mixed with cyclopentane, acetone, catalyst A, foam stabilizer A and water with a polyol to obtain a polyol composition. Next, a mixture of this composition and polyisocyanate was poured into a metal container and foamed. The bubble diameter of the obtained polyurethane foam was 300 μm. The thermal conductivity was 96 when expressed as a relative value with 100 when methyl alcohol and lithium benzoate were not added to the polyol composition. In addition, when methyl alcohol and lithium benzoate were not added to the polyol composition, the bubble diameter was 410 μm.
Met. When the ratio of methyl alcohol was set to 15, the strength of the obtained polyurethane foam was not sufficient, and shrinkage was observed.

Example 3 A polyol composition containing ethylene glycol as an alcohol having 3 or less carbon atoms, potassium carbonate as a salt dissolved therein, and heptafluoro-2-iodopropane as a blowing agent. A polyurethane foam was prepared using the product. The weight ratio of the raw materials used is as follows. Polyol A / foam stabilizer A / catalyst A
/ Heptafluoro-2-iodopropane / ethylene glycol / potassium carbonate / polyisocyanate = 100
/3/3/80/5/1.5/130. After dissolving the above indicated amount of potassium carbonate in ethylene glycol, this was added to heptafluoro-2-iodopropane, catalyst A,
And a foam stabilizer A together with a polyol to form a polyol.
To obtain a composition. Next, the composition and the polyisocyanate
The mixture was poured into a metal container and foamed to produce a polyurethane foam. The bubble diameter of the obtained polyurethane foam was 270 μm. The thermal conductivity is expressed by a relative value of 100 when potassium carbonate and ethylene glycol are not added to the polyol composition, and expressed as 9
It was one. In addition, when potassium carbonate and ethylene glycol were not added to the polyol composition, the bubble diameter was 520.
μm.

Example 4 Polyisocyanate was emulsified using ethylene glycol as an alcohol having 3 or less carbon atoms and barium chloride as a salt dissolved therein to prepare a polyurethane foam. Cyclopentane was used as the blowing agent. The weight ratio of the raw materials used is as follows. Polyol A / foam stabilizer A / catalyst A / cyclopentane / ethylene glycol / barium chloride / polyisocyanate = 100/5/2/17/5 / 1.7 / 13
0. First, the above-mentioned amount of barium chloride dissolved in erylen glycol was mixed with polyisocyanate together with foam stabilizer A at a quantitative ratio of 3 to form an emulsion. Subsequently, the emulsion is mixed with a polyol composition comprising a polyol A, a foam stabilizer A having a quantitative ratio of 2, a catalyst A and cyclopentane, and the mixture is poured into a metal container and foamed. A polyurethane foam was obtained. The bubble diameter of the obtained polyurethane foam was 270 μm. The thermal conductivity was 94 when expressed as a relative value when the conventional value in which polyisocyanate was not emulsified using ethylene glycol and barium chloride was taken as 100.
The bubble diameter of a conventional polyurethane foam in which polyisocyanate was not emulsified using ethylene glycol and barium chloride was 390 μm. Further, despite the polyisocyanate emulsion, the foaming efficiency was good, the density of the obtained foam was as low as 0.036 g / cm ^3, and when ethylene glycol and barium chloride were not used. Of 0.035 g / cm ³ . This is probably because the viscosity of the emulsion did not become so high.

Example 5 A polyurethane foam was prepared by emulsifying polyisocyanate using water and zinc acetate as a salt dissolved therein. Furan was used as the blowing agent. The weight ratio of the raw materials used is as follows. Polyol A / foam stabilizer A / catalyst B / furan / water / zinc acetate / polyisocyanate = 100/5/2/1
1/2 / 0.8 / 140. First, the above-mentioned amount of zinc acetate dissolved in water was mixed with polyisocyanate together with foam stabilizer A at a quantitative ratio of 3 to form an emulsion. Subsequently, this emulsion is mixed with a polyol composition comprising a polyol A, a foam stabilizer A having a quantitative ratio of 2, a catalyst B and a furan, and poured into a metal container to form a foam. A polyurethane foam was obtained.

The cell diameter of the obtained polyurethane foam was 230 μm. Thermal conductivity, without adding water and zinc acetate to polyisocyanate and emulsifying,
The thermal conductivity of a conventional foam obtained by mixing a polyisocyanate with a polyol composition comprising a polyol A, a foam stabilizer A, a catalyst B and a furan is represented by a relative value when the thermal conductivity is 100. And 95. Further, a polyol composition comprising a polyol A, a foam stabilizer A, a catalyst B and furan,
The conventional foam obtained by mixing non-emulsified polyisocyanate had a bubble diameter of 400 μm. Also, despite the polyisocyanate emulsion, the foaming efficiency was good and the density of the obtained foam was as low as 0.034 g / cm ³ . This is probably because the viscosity of the emulsion did not become so high. In the above-described embodiments, the alcohol having 3 or less carbon atoms and the salt dissolved therein are each one in each embodiment. However, it is needless to say that a mixture of alcohols and a plurality of salts can be used.

[0025]

As described above, the polyol composition of the present invention has a reduced bubble diameter and a low thermal conductivity of urethane foam.
Give Further, according to the production method of the present invention, the cell diameter of the urethane foam is reduced while maintaining good foaming efficiency, and a urethane foam having a low thermal conductivity can be obtained. The present invention makes it possible to provide an excellent polyurethane foam having small bubbles and low thermal conductivity without using perfluorocarbon which greatly contributes to global warming.

──────────────────────────────────────────────────続 き Continuation of the front page (51) Int.Cl. ⁷ Identification code FI C08G 101: 00) C08L 75:04 (72) Inventor Masaaki Suzuki 1006 Ojidoma, Kadoma, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. ( 72) Inventor Yoshio Kishimoto 1006 Kazuma Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (56) References JP-A-56-84713 (JP, A) JP-A-4-18448 (JP, A) JP-A Hei 4-248823 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C08G 18/08, 18/32 C08J 9/14

Claims (5)

(57) [Claims] 2. The method according to claim 1, further comprising at least one selected from the group consisting of primary alcohols and secondary alcohols having 3 or less carbon atoms, and a salt soluble in said alcohols. Polyol composition for polyurethane foaming. 2. The polyurethane foaming polio according to claim 1, wherein the amount of the salt is 0.5 parts by weight or more based on 100 parts by weight of the polyol to form a solution having a saturation concentration or less. Composition. 3. The alcohol is ethylene glycol, and the salt is at least one selected from the group consisting of potassium carbonate, barium chloride, potassium iodide, lithium chloride, sodium bromide and calcium chloride. The polyol composition for polyurethane foaming according to claim 1. 4. The polyurethane composition for foaming a polyurethane according to claim 1, which comprises a fluorinated iodide hydrocarbon as a foaming agent. 5. A solution prepared by dissolving a salt in at least one selected from the group consisting of a primary alcohol having 3 or less carbon atoms, a secondary alcohol having 3 or less carbon atoms and water. A method for producing a polyurethane foam, comprising the steps of: dispersing in a polyisocyanate together with an activator to obtain a polyisocyanate emulsion; and mixing the emulsion with a polyol composition and foam-forming.