JP4514205B2 - Method for producing film-free flexible polyurethane foam - Google Patents

Description

  The present invention relates to a method for producing a film-free flexible polyurethane foam capable of removing water-soluble impurities or reducing the content thereof.

  Conventionally, in order to obtain a soft polyurethane foam with high air permeability used for filters, cleaning sponges, etc., the cell membrane is removed by performing film removal treatment on the foamed soft polyurethane foam, To be done. The film removal treatment is generally a blast treatment in which oxygen is injected into a soft polyurethane foam and ignited to blast the cell membrane.

However, when the film removal treatment is performed, the chemical substances contained in the flexible polyurethane foam partially dissociate to generate water-soluble impurities such as aldehydes or acids, which may cause odors or cause sick house syndrome. It may become. Furthermore, the aldehydes and acids generated by the film removal process also correspond to volatile organic compounds (VOC) that affect air pollution, which is a problem in the field of automobiles and the like. Further, aldehydes and acids generated by the film removal treatment remain as they are in the film-free soft polyurethane foam, and the problem of sick house and VOC may occur for a long time. The indoor concentration guideline value of acetaldehyde set by the Ministry of Health, Labor and Welfare on January 22, 2002 to prevent damage to sick houses and the like is 48 μg / m ³ (0.03 ppm).
JP 2003-521 A

  The present invention has been made in view of the above points, and is a filmless film capable of removing or reducing the content of water-soluble impurities such as aldehydes and acids generated by film removal and remaining in the foam. A method for producing a flexible polyurethane foam is provided.

  The invention of claim 1 is characterized in that the removal of water-soluble impurities in the soft polyurethane foam or the content thereof is reduced by subjecting the soft polyurethane foam subjected to film removal to steam treatment and then drying. The present invention relates to a method for producing a film flexible polyurethane foam.

  The invention according to claim 2 is characterized in that a film-free soft polyurethane foam is subjected to superheated steam treatment to remove or reduce the content of water-soluble impurities in the soft polyurethane foam. The present invention relates to a method for producing a polyurethane foam.

  According to the first aspect of the present invention, water-soluble impurities such as aldehydes and acids generated by the film removal treatment and remaining in the foam can be obtained by subjecting the foam after the film removal treatment to steam treatment. It dissolves in the moisture of the water vapor that permeates into the water and is eluted from the foam together with the water vapor. Moreover, since the cell membrane is removed from the foam, water vapor easily passes through the inside of the foam, and water-soluble impurities in the foam can be efficiently eluted. Moreover, the water | moisture content of the water vapor | steam which will be contained in a foam by carrying out the steam process of a foam is removed from a foam by subsequent drying. As a result, a film-free flexible polyurethane foam from which water-soluble impurities have been removed or whose content has been reduced is obtained.

  According to the invention of claim 2, water-soluble impurities such as aldehydes and acids generated by the film removal treatment and remaining in the foam are foamed by the superheated steam treatment of the foam after the film removal treatment. It dissolves in the water of superheated steam that permeates into the body and elutes from the foam together with water vapor. Moreover, since the cell membrane is removed from the foam, the superheated steam easily penetrates into the foam, and water-soluble impurities in the foam can be efficiently eluted. Furthermore, the solubility of water-soluble impurities in the foam is increased by the high-temperature superheated steam, and the water-soluble impurities are efficiently dissolved in the superheated steam and discharged from the foam together with the superheated steam. As a result, a film-free flexible polyurethane foam from which water-soluble impurities have been removed or whose content has been reduced is obtained. Moreover, the superheated steam is a steam obtained by further heating a saturated steam at 100 ° C. as is well known, and is in a gaseous state even when the temperature is lowered. It does not wet the foam and does not require a drying step after the superheated steam treatment.

  The method for producing a film-free soft polyurethane foam according to the present invention comprises removing a film-treated soft polyurethane foam by steaming and then drying, or replacing the steaming and subsequent drying with a film-removed soft polyurethane. The foam is subjected to superheated steam treatment to remove or reduce the content of water-soluble impurities in the flexible polyurethane foam.

  The flexible polyurethane foam in the present invention can be obtained by a known foaming method in which a polyurethane foam raw material comprising a polyol, a catalyst, a foaming agent, a foam stabilizer, an auxiliary agent appropriately added, and a polyisocyanate is mixed and stirred.

  As the polyol, ether-based polyol or ester-based polyol known for use in flexible polyurethane foam can be used. Ether-based polyols include ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, butylene glycol, neopentyl glycol, glycerin, pentaerythritol, trimethylolpropane, sorbitol, sucrose, and other polyhydric alcohols such as ethylene oxide and propylene oxide. The polyether polyol which added the alkylene oxide of this can be mentioned. As ester polyols, polycondensation of aliphatic carboxylic acids such as malonic acid, succinic acid and adipic acid and aromatic carboxylic acids such as phthalic acid and aliphatic glycols such as ethylene glycol, diethylene glycol and propylene glycol. The polyester polyol obtained in this way can also be used. In addition, a polymer polyol obtained by polymerizing an ethylenically unsaturated compound in a polyether polyol can also be used.

  As the catalyst, an amine catalyst such as triethylamine or tetramethylguanidine, a tin catalyst such as stannous octoate, or a metal catalyst such as phenylmercurypropionate or lead octenoate (also referred to as an organometallic catalyst) is used. Can do. A common amount of catalyst is 0.01 to 2.0 parts by weight per 100 parts by weight of polyol.

  As the blowing agent, water or hydrocarbons such as pentane can be used alone or in combination. In the case of water, carbon dioxide gas is generated during the reaction of the raw material composition, and foaming is performed by the carbon dioxide gas. The amount of the blowing agent is appropriately determined. In the case of water, about 0.5 to 7.0 parts by weight is preferable with respect to 100 parts by weight of the polyol.

  Any foam stabilizer may be used as long as it is used in the production of flexible polyurethane foams. Examples thereof include silicone foam stabilizers, fluorine-containing compound foam stabilizers, and known surfactants. A common amount of foam stabilizer is 0.1 to 3.0 parts by weight per 100 parts by weight of polyol.

  Other auxiliary agents that can be added as appropriate include ultraviolet absorbers, flame retardants, antioxidants, fillers, colorants, and the like. A well-known thing is used as a ultraviolet absorber. Examples thereof include benzophenone-based, benzotriazole-based, and benzoxazinone-based compounds. Examples of benzophenone compounds include 2-hydroxy-4-octoxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2,2′-dihydroxy-4,4′-dimethoxybenzophenone, 2,2 ′, 4,4′-. Examples thereof include tetrahydroxybenzophenone, 2,4-dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone-5-sulfonic acid, and the like. Examples of the flame retardant include those made of an organic phosphate compound.

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

  Film removal treatment is performed on the foamed soft polyurethane foam. The film removal process is performed by a known blasting process in which oxygen is injected into a soft polyurethane foam and ignited. By this film removal treatment, the cell membrane of the flexible polyurethane foam is removed, and air permeability is increased. Also, the chemical substance used in the polyurethane foam raw material and contained in the soft polyurethane foam after foaming is partially dissociated by the film removal treatment to become water-soluble impurities such as aldehydes and acids, and after the film removal treatment. Remains in the foam.

  The foam after the cell membrane removal treatment is subjected to steam treatment or superheated steam treatment, thereby removing water-soluble impurities or reducing the content of the foam after the cell membrane removal. A film-free flexible polyurethane foam is obtained.

  The steam treatment refers to placing the foam after removal of the cell membrane in a steam environment, for example, by spraying water on the surface of the foam after removal of the cell membrane, or in a container filled with steam. This refers to placing the foam after removal of the cell membrane. Thereafter, the foam is accommodated in a drying furnace and dried. As the water vapor, a humidity of 40 to 95% and a temperature of 70 to 100 ° C. are suitable. The time for performing the water vapor treatment on the foam after the film removal treatment is appropriately determined according to the size of the foam and the like, and an example is 1 to 10 minutes. In addition, when spraying and applying water vapor | steam to the foam after a film removal process, you may apply to one surface of a foam, and may apply to the whole surface. Since the foamed film has a three-dimensional network skeleton structure, water vapor applied to one surface can easily pass through the foam, and water-soluble impurities contained in the foam are foamed together with water vapor. It can be discharged from the body. Moreover, since the deterioration of a foam and a physical-property fall will arise if the drying temperature and drying time after the said steam treatment are too long, drying temperature is preferably 50 to 70 ° C. and drying time is preferably 30 to 40 minutes.

  The superheated steam treatment refers to placing the foam after removal of the cell membrane in a superheated steam environment. For example, the superheated steam is sprayed on the surface of the foam after removal of the cell membrane, or the superheated steam is filled. The foam after the cell membrane is removed is placed in a container. The superheated steam is steam obtained by further heating a saturated steam at 100 ° C. The superheated steam is generated as follows. First, generate saturated steam with a steam generator (boiler for gas, petroleum, etc.), then depressurize the saturated steam with a pressure reducing valve, and introduce the resulting reduced-pressure saturated steam into the superheated steam generator to generate superheated steam. To do. The decompression valve is a device for controlling the discharge amount of superheated steam, and by reducing the pressure, excessive volume expansion in the superheated steam discharged under atmospheric pressure is prevented, and disasters such as explosions are avoided. As the superheated steam generator, a known device that can superheat saturated steam to form superheated steam can be used.

  The time for performing the superheated steam treatment on the foam after the film removal treatment is appropriately determined according to the size of the foam and the like, and is about several seconds to 3 minutes as an example. If the superheated steam treatment time is too long, the foam is deteriorated and the physical properties are lowered. Therefore, it is preferable that the superheated steam treatment time is short. In addition, when spraying and applying superheated steam to the foam after film removal treatment, it may be applied to one surface of the foam or the entire surface. Since the foam after the film removal treatment has a three-dimensional network skeleton structure, superheated steam applied to one surface can easily pass through the foam and can exert a water-soluble impurity removing action. . Further, since the superheated steam maintains a gaseous state even when the temperature falls upon the foam, the foam does not get wet by the superheated steam treatment, and the subsequent drying treatment becomes unnecessary.

Examples of the present invention will be described below. A polyol, a catalyst, a foaming agent, and a foam stabilizer having the following composition were used as a polyol component, and the polyol component and polyisocyanate were mixed and foamed as follows. Mixing was performed by putting the polyol component and polyisocyanate in a 500 cc beaker and stirring at 20 ° C. using a propeller mixer. Also, the mixed reaction mixture was poured into a 300 × 300 × 300 mm box and foamed and cured to form a flexible polyurethane foam having a density of 0.03 g / cm ³ .
Polyurethane foaming raw material-Polyol (Nippon Polyurethane Industry Co., Ltd., N101) 100 parts by weight-Catalyst (Kao Co., Ltd., Caorizer (registered trademark) No. 22 0.5 part by weight-Foaming agent (water) 3 parts by weight- Foam stabilizer (Nippon Unicar Co., Ltd., SE-232) 1 part by weight Polyisocyanate (Nippon Polyurethane Industry Co., Ltd., T-65) 45 parts by weight

  The resulting soft polyurethane foam was subjected to film removal treatment by a known blast treatment. A required number of 200 × 200 × 10 mm test pieces were cut from the foam after the film removal treatment. Comparative Example 1 with the test piece thus obtained as it was, Comparative Examples 2 and 3 in which tap water treatment was performed on the test piece, Examples 1 and 2 in which steam treatment was performed on the test piece, Examples 3 and 4 in which superheated steam treatment was performed on the test pieces were prepared.

  In the tap water treatment, the test piece was placed on a wire mesh, and water at 25 ° C. was applied to the test piece from the outlet of the pipe facing downward from above the test piece, in Comparative Example 2 for 5 minutes, and in Comparative Example 3 for 10 minutes. After that, the test piece was placed in a drying furnace at 70 ° C. for 40 minutes. In the steam treatment, the test piece was placed on a wire mesh, and water vapor with a humidity of 70% × 80 ° C. was sprayed from the outlet of the pipe facing downward from above the test piece for 5 minutes in Example 1 and for 10 minutes in Example 2. Thereafter, the test piece was placed in a drying furnace at 70 ° C. for 40 minutes. In the superheated steam treatment, the test piece was placed on the wire mesh, and superheated steam was sprayed from the outlet of the pipe facing downward from above the test piece for 5 minutes in Example 3 and for 10 minutes in Example 4. The superheated steam has a saturated steam pressure (primary pressure) of 0.6 MPa before decompression by the decompression valve, a pressure (secondary pressure) after decompression by the decompression valve of 0.04 MPa, and the temperature of the superheated gas at the outlet of the pipe. Is 190 ± 5 ° C., the pipe diameter is ½, and the distance between the test piece and the superheated steam pipe outlet is 50 mm. The used wire mesh is rough enough to allow water, water vapor, and superheated steam to pass through, and has a strength sufficient to hold the test piece.

  The contents of formaldehyde, acetaldehyde, and propionic acid were measured for the test pieces of Comparative Examples 1 to 3 and Examples 1 to 4. In the measurement method, a measurement piece of 5 × 30 × 30 mm cut from each test piece was accommodated in a 1 L glass desiccator, and then the air in the glass desiccator was replaced with nitrogen and left in a constant temperature bath at 65 ° C. for 2 hours. Then, the gas in a glass desiccator was sucked and analyzed according to JIS Z8808 using a gas chromatograph. The analysis results are as shown in Table 1.

As is clear from Table 1, the tap water treatment (Comparative Example 2 and Comparative Example 3) is almost the same as the case where the treatment is not carried out (Comparative Example 1) with respect to the amounts of formaldehyde and acetaldehyde, and the removal effect of aldehydes is improved. It turns out that it is very low. It can be seen that the amount of formaldehyde, acetaldehyde and propionic acid in the steam treatment (Example 1, Example 2) is greatly reduced compared to the case where the treatment is not performed (Comparative Example 1). Moreover, it turns out that the removal effect of formaldehyde, acetaldehyde, and propionic acid is so high that the spraying time of water vapor | steam is long. The superheated steam treatment (Examples 3 and 4) has a smaller amount of formaldehyde, acetaldehyde and propionic acid and higher removal effect of formaldehyde, acetaldehyde and propionic acid than the steam treatment (Examples 1 and 2). I understand that. Moreover, since the superheated steam treatment does not wet the foam with moisture, there is no need to dry the foam, and the superheated steam treatment for several minutes can remove or reduce the content of water-soluble impurities such as aldehydes and acids. It is possible to obtain a film-free flexible polyurethane foam with little peculiar irritating odor due to acid or the like.

Claims (2)

  Production of a non-film flexible polyurethane foam characterized by removing water-soluble impurities or reducing the content of water-soluble impurities in the flexible polyurethane foam by subjecting the film-treated soft polyurethane foam to steam treatment and then drying. Method. A process for producing a film-free soft polyurethane foam, characterized in that the removal of water-soluble impurities in the soft polyurethane foam or the content thereof is reduced by subjecting the soft polyurethane foam subjected to film removal treatment to superheated steam treatment.