JP7212433B2 - Polyurethane foam and its manufacturing method - Google Patents

Description

TECHNICAL FIELD The present invention relates to a lightweight polyurethane foam having sound absorption properties and a method for producing the same.

Polyurethane foams obtained from polyurethane foam raw materials containing polyol, isocyanate, blowing agent and catalyst are widely used for furniture, building materials, vehicle interior materials and the like.

Polyurethane foams containing a large amount of water (7 to 17 parts by weight per 100 parts by weight of polyol) used as a blowing agent are known as lightweight polyurethane foams having sound absorbing properties. (Patent document 1, claim 7).

However, a polyurethane foam containing a large amount of water as a blowing agent generates heat at a high temperature during foaming, and scorches occur in the polyurethane foam, resulting in deterioration of quality.

Japanese Patent No. 5204754

SUMMARY OF THE INVENTION It is an object of the present invention to provide a sound-absorbing, lightweight and high-quality polyurethane foam and a method for producing the same.

The invention of claim 1 is a polyurethane foam obtained from a polyurethane foam raw material containing a polyol, an isocyanate, a blowing agent, and a catalyst, wherein the polyurethane foam raw material contains sodium hydrogen carbonate and an organic solid acid, and water as the blowing agent is It is 10 parts by weight or more with respect to 100 parts by weight of the polyol, the isocyanate index is 100 or more, and the catalyst contains 0.4 to 0.8 parts by weight of a metal catalyst with respect to 100 parts by weight of the polyol. Characterized by

The invention of claim 2 is characterized in that, in claim 1, the sodium hydrogen carbonate is 5 to 50 parts by weight with respect to 100 parts by weight of the polyol.

The invention according to claim 3 is characterized in that in claim 1 or 2, the amount of the organic solid acid is 1/30 to 1/60 of the amount of the sodium hydrogen carbonate.

The invention of claim 4 is characterized in that, in any one of claims 1 to 3, the organic solid acid is citric acid and/or malic acid.

According to a fifth aspect of the invention, there is provided a method for producing a polyurethane foam by mixing and reacting polyurethane foam raw materials containing a polyol, an isocyanate, a blowing agent, and a catalyst, wherein the polyurethane foam raw materials include sodium hydrogen carbonate and an organic solid acid, and the foaming water as an agent is 10 parts by weight or more with respect to 100 parts by weight of the polyol; It is characterized by containing parts by weight.

In the present invention, since 10 parts by weight or more of water is used as a foaming agent with respect to 100 parts by weight of polyol, there is concern that the temperature of the reaction exotherm may increase during the production of polyurethane foam. The solid acid is decomposed by the heat generated during the production of the polyurethane foam to generate water, and the latent heat of vaporization (heat of vaporization) of the water suppresses the temperature rise. It is possible to obtain a high-quality polyurethane foam which is light in weight and hardly discolored.

When the organic solid acid is citric acid, the endothermic reaction in the first stage is as shown in FIG. Absorption of heat suppresses temperature rise due to reaction of raw materials for polyurethane foam.

The sodium hydrogen carbonate not consumed in the endothermic reaction in the first stage undergoes the endothermic reaction in the second stage shown in FIG. The rise can be further suppressed. In the endothermic reaction of the second stage, the sodium hydrogen carbonate not consumed in the endothermic reaction of the first stage is thermally decomposed into sodium carbonate, water and carbon dioxide.

FIG. 2 shows the first-stage endothermic reaction and the second-stage endothermic reaction when the organic solid acid is malic acid.
In addition, water and carbon dioxide are generated as reaction decomposition products of sodium bicarbonate and an organic solid acid (e.g. citric acid or malic acid). form can be lightened.

Further, since 0.4 to 0.8 parts by weight of a metal catalyst is included as a catalyst with respect to 100 parts by weight of polyol, the polyurethane foam has low air permeability and can improve sound absorption.

It is a figure which shows the endothermic reaction by sodium hydrogencarbonate and a citric acid. It is a figure which shows the endothermic reaction by sodium hydrogencarbonate and malic acid. 1 is a table showing formulations and measurement results of physical properties of examples and comparative examples.

The polyurethane foam of the present invention is produced by mixing and reacting polyurethane foam raw materials including polyol, isocyanate, blowing agent, catalyst, sodium hydrogencarbonate and organic solid acid.

Polyols for polyurethane foams can be used as polyols, and for example, any of polyether polyols, polyester polyols, and polyether ester polyols can be used, and one or more of them can be used.

Examples of polyether polyols include polyhydric alcohols such as ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, butylene glycol, neopentyl glycol, glycerin, pentaerythritol, trimethylolpropane, sorbitol, sucrose, and ethylene oxide (EO ) and polyether polyols to which alkylene oxides such as propylene oxide (PO) are added.

Examples of polyester polyols include polycondensation from aliphatic carboxylic acids such as malonic acid, succinic acid and adipic acid, aromatic carboxylic acids such as phthalic acid, and aliphatic glycols such as ethylene glycol, diethylene glycol and propylene glycol. Polyester polyols obtained by
Examples of polyether ester polyols include those obtained by reacting the above polyether polyols with polybasic acids to form polyesters, and those having both polyether and polyester segments in one molecule.

As for the polyol, it is preferable to use one or a plurality of polyols having a hydroxyl value (OHV) of 20 to 300 mgKOH/g, a functional group number of 2 to 6, and a weight average molecular weight of 500 to 15,000.

As the isocyanate, aliphatic or aromatic polyisocyanates having two or more isocyanate groups, mixtures thereof, and modified polyisocyanates obtained by modifying them can be used. Examples of aliphatic polyisocyanates include hexamethylene diisocyanate, isophorone diisocyanate, and dicyclohexamethane diisocyanate. Examples of aromatic polyisocyanates include toluene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), naphthalene diisocyanate, xyloxy Examples include diisocyanate, polymeric MDI (crude MDI), and the like. In addition, other prepolymers can also be used.

The isocyanate index (INDEX) is preferably 100 or more, more preferably 100-125. The isocyanate index is a value obtained by dividing the number of moles of isocyanate groups in isocyanate by the total number of moles of active hydrogen groups such as hydroxyl groups in polyol and multiplying this value by 100. Calculated.

Water is preferred as the blowing agent. Water generates carbon dioxide gas when polyol reacts with isocyanate, and the carbon dioxide gas causes foaming. The amount of water as a blowing agent is 10 parts by weight or more with respect to 100 parts by weight of polyol, and the preferred amount of water is 10 to 15 parts by weight.

Catalysts include metal catalysts and are preferably used in combination with amine catalysts. Examples of metal catalysts include tin catalysts such as stannus octoate and dibutyltin dilaurate, phenylmercuric propionate, and lead octenate. The amount of metal catalyst is 0.4-0.8 parts by weight, preferably 0.4-0.6 parts by weight, based on 100 parts by weight of polyol. By containing the metal catalyst in the above range, the air permeability of the polyurethane foam is reduced, and the average sound absorption coefficient in the entire frequency range from the low frequency range to the high frequency range, specifically, the average sound absorption coefficient in the range of 1000 to 12500 Hz is increased. can be done. Amine catalysts include triethylamine, triethylenediamine, diethanolamine, dimethylaminomorpholine, N-ethylmorpholine, tetramethylguanidine and the like. The amount of amine catalyst is preferably 0 or 0.05 to 0.7 parts by weight per 100 parts by weight of polyol.

The amount of sodium hydrogen carbonate is preferably 5 to 50 parts by weight with respect to 100 parts by weight of polyol. By setting the amount of sodium bicarbonate within the above range, the endothermic reaction can be favorably performed, and an exothermic temperature rise during the production of the polyurethane foam can be suppressed.

When the organic solid acid is used in combination with sodium hydrogencarbonate, the endothermic effect increases during the production of the polyurethane foam, and the increase in the exothermic temperature of the polyurethane foam can be suppressed more effectively. The amount of the organic solid acid is preferably 1/30 to 1/60, more preferably 1/30 to 1/50, of the amount of sodium hydrogencarbonate.

Examples of organic solid acids include citric acid, fumaric acid, malonic acid, stearic acid, pyruvic acid, phthalic acid, malic acid, maleic acid, succinic acid, and polybasic carboxylic acids having hydroxy groups. The organic solid acid is not limited to one type, and two or more types may be used in combination. In particular, citric acid and malic acid (hydroxy acids) are more preferred organic solid acids in the present invention, and either or both of them are used. In particular, malic acid is a preferred organic solid acid in the present invention. Both hydrates and anhydrides of citric acid can be used.

Other auxiliary agents may be added to the polyurethane foam raw material. Examples of auxiliary agents include foam stabilizers and coloring agents. As the foam stabilizer, those known for polyurethane foam can be used. Examples thereof include silicone foam stabilizers, fluorine foam stabilizers and known surfactants. As the colorant, a carbon pigment or the like can be used according to the use of the polyurethane foam.

The polyurethane foam of the present invention preferably has a density (JIS K7220) of 10-15 kg/m ³ . By making the density within the above range, the weight of the polyurethane foam can be reduced, and the average sound absorption coefficient at 2500 to 12500 Hz can be increased.
Further, the polyurethane foam of the present invention preferably has air permeability (JIS K6400-7:2012) of 0.1 to 10 cc/cm ² /s, more preferably 0.2 to 5 cc/cm ² /s. be. By setting the low air permeability within the above range, the average sound absorption coefficient of the polyurethane foam in the entire frequency range from the low frequency region to the high frequency region, specifically the average sound absorption coefficient of 1000 to 12500 Hz can be increased.

As a foaming method for producing polyurethane foam, a molding foaming method of casting into a mold or a slabstock foaming method can be employed, and among these, the slabstock foaming method is preferable for mass production. The slabstock foaming method is a method in which two liquid polyurethane foam raw materials are mixed with a stirrer, discharged onto a belt conveyor, and foamed at room temperature under atmospheric pressure. A one-shot method, a prepolymer method, or the like can be employed for the polyurethane raw material composition.

The following components were mixed according to the formulation shown in FIG. 3, reacted and foamed to prepare polyurethane foams for each of Comparative Examples and Examples. The unit of the addition amount of each component is parts by weight.
Polyol; polyether polyol, molecular weight: 3000, number of functional groups 3, hydroxyl value 56.1 mgKOH / mg, product number: GP-3050, manufactured by Sanyo Chemical Industries, Ltd. ・Blowing agent -1; water ・Blowing agent -2; liquefied carbon dioxide gas ( _CO2 )
Amine catalyst; N-ethylmorpholine, product number: NEM, manufactured by Huntsman Metal catalyst; stannous octylate, product number: MRH110, manufactured by Johoku Chemical Industry Co., Ltd. Foam stabilizer; silicone-based foam stabilizer, product number: B8110, Manufactured by Evonik ・Sodium hydrogen carbonate ・Malic acid ・Isocyanate;

For each comparative example and each example, heat generation temperature (maximum heat generation temperature), density (JIS K7220), hardness (JIS K6400-2), air permeability (JIS K6400-7: 2012), vertical incident sound absorption coefficient (JIS A1405 -2: 2007) was measured.

The method for measuring the exothermic temperature is as follows. A wooden box of 100 cm×100 cm×60 cm without a lid was prepared in advance, and the thermocouple was set in the center of the wooden box. Then, two liquids of the polyol compounding component and the isocyanate component in each comparative example and each example are separately prepared, and after mixing and stirring the two liquids with a propeller mixer, the reaction mixture is poured into the wooden box to form a polyurethane. The foam was naturally foamed at normal temperature and atmospheric pressure, and the heat generation temperature was measured with a thermocouple. The measurement results of exothermic temperature were evaluated, and when the exothermic temperature was less than 150°C, it was evaluated as “⊚”;

The density measurement results were evaluated, and the density was evaluated as "⊚" when the density was less than 12 kg/m ³ , "◯" when the density was 12 kg/m ³ or more and less than 15 kg/m ³ , and "x" when it was 15 kg/m ³ or more.

The normal incident sound absorption coefficient was measured with a measurement sample having a thickness of 10 mm and a center frequency range of 1000 to 12500 Hz in the 1/3 octave band. Also, average values were obtained for each range of 1000 to 12,500 Hz, 2,000 to 12,500 Hz, and 2,500 to 12,500 Hz to evaluate sound absorption. The sound absorption was evaluated as "O" when the average value of each range in the measured values of the normal incident sound absorption coefficient was 0.6 or more, and as "X" when less than 0.6 existed even in one range.

Also, a comprehensive evaluation was made based on the exothermic temperature evaluation, density evaluation, and sound absorption evaluation. When all the evaluations were "O" or more, the overall evaluation was "O", and when even one "X" was present, the overall evaluation was "X".
In addition, each measurement result, each evaluation, and the result of comprehensive evaluation are shown in FIG.

Comparative Example 1 contains 100 parts by weight of polyol, 5 parts by weight of blowing agent-1 (water), 4 parts by weight of blowing agent-2 (CO ₂ ), 0.2 parts by weight of amine catalyst, 0.3 parts by weight of metal catalyst, This is an example in which the foaming agent is 1 part by weight, the isocyanate is 60 parts by weight, the isocyanate index is 105, and neither sodium hydrogen carbonate nor malic acid is added.

Comparative Example 1 has an exothermic temperature of 154°C, an exothermic temperature evaluation of “◯”, a density of 14.2 kg/m ³ , a density evaluation of “◯”, a hardness of 60 N, an air permeability of 23 cc/cm ² /s, and a normal incidence sound absorption coefficient of 1000 to 12500 Hz. 0.49, 2000 to 12500 Hz average 0.63, 2500 to 12500 Hz average 0.69, the sound absorption evaluation was "x", and the overall evaluation was "x". In Comparative Example 1, since the amount of blowing agent-1 (water) is less than 10 parts by weight and less than 0.4 parts by weight of the metal catalyst, air permeability is high, and the normal incidence sound absorption coefficient is improved in the range of 1000 to 12500 Hz. was low and the sound absorption was poor.

Comparative Example 2 is an example in which 5.6 parts by weight of blowing agent-1 (water), 0 parts by weight of blowing agent-2 (CO ₂ ), and 66.1 parts by weight of isocyanate are used, and the rest is the same as in Comparative Example 1. .

Comparative Example 2 has an exothermic temperature of 159°C, an exothermic temperature evaluation of “O”, a density of 21.0 kg/m ³ , a density evaluation of “X”, a hardness of 98 N, an air permeability of 90 cc/cm ² /s, and a normal incidence sound absorption coefficient of 1000 to 12500 Hz. 0.41, 2000-12500 Hz average 0.51, 2500-12500 Hz average 0.56, sound absorption evaluation "x", overall evaluation "x". Compared to Comparative Example 1, Comparative Example 2 does not contain foaming agent-2 (CO ₂ ), has higher density, hardness and air permeability, and has a normal incidence sound absorption coefficient of less than 0.6 in each range. and the sound absorption was poor.

Comparative Example 3 is an example in which 0.45 parts by weight of the metal catalyst was used and the other conditions were the same as in Comparative Example 2.

Comparative Example 3 has a heat generation temperature of 162° C., a heat generation temperature evaluation of “×”, a density of 20.5 kg/m ³ , a density evaluation of “×”, a hardness of 90 N, an air permeability of 18 cc/cm ² /s, and a normal incidence sound absorption coefficient of 1000 to 12500 Hz. 0.64, average 0.80 at 2000 to 12500 Hz, average 0.85 at 2500 to 12500 Hz, sound absorption evaluation "O", overall evaluation "X". In Comparative Example 3, the amount of the metal catalyst was increased compared to Comparative Example 2, so the exothermic temperature was higher, but the air permeability was lower, and the normal incidence sound absorption coefficient was 0.6 or more in each range. , resulting in good sound absorption.

Comparative Example 4 is an example in which 10 parts by weight of sodium hydrogencarbonate is contained and the other conditions are the same as in Comparative Example 2.

Comparative Example 4 has a heat generation temperature of 149° C., a heat generation temperature evaluation of “◎”, a density of 19.9 kg/m ³ , a density evaluation of “×”, a hardness of 85 N, an air permeability of 21 cc/cm ² /s, and a normal incidence sound absorption coefficient of 1000 to 12500 Hz. 0.53, 2000-12500 Hz average 0.66, 2500-12500 Hz average 0.71, sound absorption evaluation "x", overall evaluation "x". Compared to Comparative Example 2, Comparative Example 4 contains less than 10 parts by weight of Blowing Agent-1 (water), so the density is about the same but heavier, and the exothermic temperature is lower due to the inclusion of sodium bicarbonate. However, the air permeability is high, and the normal incident sound absorption coefficient decreases in the range of 1000 to 12500 Hz, resulting in poor sound absorption.

Example 1 contains 100 parts by weight of polyol, 10 parts by weight of blowing agent-1 (water), 0.2 parts by weight of amine catalyst, 0.4 parts by weight of metal catalyst, 1 part by weight of foam stabilizer, and 10 parts by weight of sodium hydrogen carbonate. , 0.7 parts by weight of malic acid, 131.2 parts by weight of isocyanate, and an isocyanate index of 105. Compared to Comparative Examples 2 and 4, Example 1 increased the amount of blowing agent-1 (water) to 10 parts by weight, increased the amount of metal catalyst to 0.4 parts by weight, and added both sodium bicarbonate and malic acid. and the amount of isocyanate is adjusted so that the isocyanate index is 105, which is the same as Comparative Examples 2 and 4.

Example 1 has a heat generation temperature of 158° C., a heat generation temperature evaluation of “◯”, a density of 12.8 kg/m ³ , a density evaluation of “◯”, a hardness of 85 N, ventilation of 1.8 cc/cm ² /s, and a normal incidence sound absorption coefficient of 1000. The average was 0.66 at ~12500 Hz, the average was 0.82 at 2000-12500 Hz, the average was 0.88 at 2500-12500 Hz, the sound absorption evaluation was "◯", and the overall evaluation was "◯".

In Example 1, compared to Comparative Examples 2 and 4, the amount of blowing agent-1 (water) was increased to 10 parts by weight and the amount of metal catalyst was increased to 0.4 parts by weight. Including both sodium bicarbonate and malic acid lowered the exothermic temperature, which should have been the case. In addition, in Example 1, the amount of blowing agent-1 (water) was increased to 10 parts by weight and the amount of metal catalyst was increased to 0.4 parts by weight. The normal incident sound absorption coefficient was 0.6 or more in each range, and the sound absorption was improved.

Example 2 is an example in which the amount of foaming agent-1 (water) is increased to 12 parts by weight, the amount of sodium hydrogen carbonate to 30 parts by weight, and the amount of malic acid to 0.8 parts by weight. . Example 2 has an exothermic temperature of 141° C., an exothermic temperature evaluation of “◎”, a density of 10.9 kg/m ³ , a density evaluation of “◎”, a hardness of 74 N, an air permeability of 1.5 cc/cm ² /s, and a normal incidence sound absorption coefficient of 1000. The average was 0.67 at ~12500 Hz, the average was 0.83 at 2000 to 12500 Hz, the average was 0.89 at 2500 to 12500 Hz, the sound absorption evaluation was "◯", and the overall evaluation was "◯".

In Example 2, the amount of Blowing Agent-1 (water) was increased to 12 parts by weight compared to Example 1, so that the exothermic temperature should be higher. Increasing both amounts resulted in a lower exotherm temperature. In addition, in Example 2, by increasing the amount of foaming agent-1 (water), the density was lower than in Example 1, and the air permeability was lower. was also increased, and the sound absorption was further improved.

Example 3 is an example in which the amount of the metal catalyst is increased to 0.5 parts by weight, and other conditions are the same as in Example 2.

Example 3 has an exothermic temperature of 145° C., an exothermic temperature evaluation of “◎”, a density of 10.5 kg/m ³ , a density evaluation of “◎”, a hardness of 78 N, an air permeability of 0.2 cc/cm ² /s, and a normal incidence sound absorption coefficient of 1000. The average was 0.69 at up to 12500 Hz, the average was 0.86 at 2000 to 12500 Hz, the average was 0.91 at 2500 to 12500 Hz, the sound absorption evaluation was "◯", and the overall evaluation was "◯".

Compared to Example 2, Example 3 has lower air permeability due to the increase of the metal catalyst to 0.5 parts by weight, and the normal incidence sound absorption coefficient is higher than Example 2 in each range. Better sound absorption.

Example 4 is an example in which the amount of sodium bicarbonate is increased to 35 parts by weight, and other conditions are the same as in Example 2.

Example 4 has a heat generation temperature of 137° C., a heat generation temperature evaluation of “◎”, a density of 10.4 kg/m ³ , a density evaluation of “◎”, a hardness of 76 N, an air permeability of 1.0 cc/cm ² /s, and a normal incidence sound absorption coefficient of 1000. The average was 0.66 at ~12500 Hz, 0.83 at 2000 to 12500 Hz, and 0.89 at 2500 to 12500 Hz.

In Example 4, the exothermic temperature was slightly lowered by increasing the amount of sodium hydrogencarbonate by 5 parts by weight from that in Example 2. As for the normal incidence sound absorption coefficient, results equivalent to those of Example 2 were obtained in each range, indicating good sound absorption.

Example 5 is an example in which the amount of sodium bicarbonate is increased to 45 parts by weight, and the rest is the same as in Examples 2 and 4.

Example 5 has an exothermic temperature of 129°C, an exothermic temperature evaluation of "⊚", a density of 10.9 kg/m ³ , a density evaluation of "⊚", a hardness of 71 N, an air permeability of 1.3 cc/cm ² /s, and a normal incidence sound absorption coefficient of 1000. The average was 0.67 at ~12500 Hz, the average was 0.84 at 2000-12500 Hz, the average was 0.90 at 2500-12500 Hz, the sound absorption evaluation was "◯", and the overall evaluation was "◯".

In Example 5, the exothermic temperature was further lowered by increasing the amount of sodium bicarbonate compared to Examples 2 and 4. As for the normal incidence sound absorption coefficient, the results equivalent to those of Examples 2 and 4 were obtained in each range, indicating good sound absorption.

As described above, the polyurethane foam of the present invention has good sound absorption properties, is lightweight, and has good quality, and is suitable for furniture, building materials, vehicle interior materials, sound absorbing materials, and the like.

Claims (4)

In a polyurethane foam obtained from a polyurethane foam raw material containing a polyol, an isocyanate, a blowing agent and a catalyst,
The polyurethane foam raw material contains sodium hydrogen carbonate and an organic solid acid,
The organic solid acid is selected from citric acid, fumaric acid, malonic acid, stearic acid, phthalic acid, malic acid, maleic acid, succinic acid,
The amount of the organic solid acid is 1/30 to 1/60 of the amount of the sodium hydrogen carbonate,
Water as the foaming agent is 10 parts by weight or more with respect to 100 parts by weight of the polyol,
The isocyanate index is 100 or more,
A polyurethane foam, wherein the catalyst contains 0.4 to 0.8 parts by weight of a metal catalyst based on 100 parts by weight of the polyol. The polyurethane foam according to claim 1, wherein the sodium bicarbonate is 5 to 50 parts by weight with respect to 100 parts by weight of the polyol. 3. The polyurethane foam according to claim 1, wherein said organic solid acid is citric acid and/or malic acid . In a method for producing a polyurethane foam by mixing and reacting polyurethane foam raw materials containing a polyol, an isocyanate, a blowing agent and a catalyst,
The polyurethane foam raw material contains sodium hydrogen carbonate and an organic solid acid,
The organic solid acid is selected from citric acid, fumaric acid, malonic acid, stearic acid, phthalic acid, malic acid, maleic acid, succinic acid,
The amount of the organic solid acid is 1/30 to 1/60 of the amount of the sodium hydrogen carbonate,
Water as the foaming agent is 10 parts by weight or more with respect to 100 parts by weight of the polyol,
The isocyanate index is 100 or more,
A method for producing a polyurethane foam, wherein the catalyst contains 0.4 to 0.8 parts by weight of a metal catalyst with respect to 100 parts by weight of the polyol .

Images