JP2005232382A - Method for manufacturing soft polyurethane foam - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a low density soft polyurethane foam obtained by foaming with water, the foam having improved distortion under compression due to the use of a specific polyether polyol. <P>SOLUTION: A soft polyurethane foam is obtained by reacting a polyol and an organic polyisocyanate in the presence of a foaming agent, a foam controlling agent and a catalyst. Water is used as the foaming agent. A polyether polyol, as the polyol component having a number average molecular weight of 2,000-7,000 is 1-50 wt.% of the total polyol. The polyether polyol is obtained by adding propylene oxide to a polyglycerol having an average polymerization degree of 2-4, followed by addition of ethylene oxide. The ethylene oxide content in the total polyether polyol is 5-50 wt.%. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a flexible foamed polyurethane foam and a method for producing the same. Specifically, it relates to a flexible foamed polyurethane foam that is frequently used for interior materials for vehicles, furniture cushioning materials, bedding, miscellaneous goods, etc., which are improved in durability, represented by compression strain. It is related with the manufacturing method.

  Due to its cushioning properties, the flexible foamed polyurethane foam is widely used for vehicle cushioning materials, furniture mats, bedding, sundries and the like. Soft foam polyurethane foam is polyol, polymer polyol in which polymer particles obtained by radical polymerization of acrylonitrile or styrene in polyol are dispersed, water as foaming agent, foam stabilizer such as silicone surfactant, amines, It is produced by mixing a catalyst such as a tin compound, if necessary, a crosslinking agent, a flame retardant, a pigment and the like with an organic polyisocyanate. Water as a foaming agent reacts with the organic polyisocyanate, and the carbon dioxide that has been released becomes a foaming gas, and at the same time functions as a foaming agent by a reaction that produces polyurea.

In recent years, for example, for vehicles, there has been a demand for lower density for weight reduction corresponding to fuel consumption regulations, and at the same time, there has been an increasing demand for lower density in terms of cost reduction. In order to meet such a demand, water as a blowing agent tends to increase further. Increasing the amount of water increases the amount of generated carbon dioxide gas and is effective in reducing the density of the flexible foamed polyurethane foam, but causes deterioration in compression strain characteristics and durability characteristics. The shape stability of such a flexible foamed polyurethane foam causes various problems. For example, there is a problem that the thickness of the bed cushion decreases with use, or the thickness or hardness of the vehicle cushion changes with use. Especially in the case of vehicle cushions, etc., the cushion thickness and hardness at the beginning of the design will decrease due to long-time vehicle driving, the driver's home position will be lowered, the field of view will be narrowed and safety will be impaired, and sitting comfort and riding comfort will deteriorate To do. These problems are problems of durability of the flexible foamed polyurethane foam. Therefore, a flexible foamed polyurethane foam that can achieve weight reduction and has excellent physical properties in compression strain and repeated compression tests has been desired. Patents using a polyol having a hydroxyl value of 34 to 60 and a total degree of unsaturation of 0.03 or less as a polyol for improving compression strain (for example, see Patent Document 1), and a polyol having a hydroxyl value of 5 to 25 and a total degree of unsaturation of 0 Patents using a mixture of a high molecular weight polyoxyalkylene polyol having a molecular weight of 0.07 or less and a polyfunctional compound having a low molecular weight isocyanate reactive group (for example, see Patent Document 2) are disclosed. In these methods, it can be considered that the degree of cross-linking of the flexible foamed polyurethane foam is increased, and the compression strain of the flexible foamed polyurethane foam is improved. In such a method, the machine required for the flexible foamed polyurethane resin is used. This is a problem because the elongation, which is a physical property, decreases.
Japanese Patent Laid-Open No. 02-151521 Japanese Patent Laid-Open No. 03-068620

  An object of the present invention is to provide a low-density flexible foamed polyurethane foam having a property excellent in durability, particularly compressive strain, and using water as a foaming agent, and a method for producing the same.

  As a result of various studies, the present inventors have found a flexible foamed polyurethane foam using water as a foaming agent and having excellent durability even at a low density by using a specific polyether polyol, and completed the present invention. It was. That is, in the production of a flexible foamed polyurethane foam obtained by reacting a polyol with an organic polyisocyanate in the presence of a foaming agent, a foam stabilizer, and a catalyst, water is used as the foaming agent, and the average degree of polymerization is as the polyol component. After adding propylene oxide to 2 to 4 polyglycerin, all the polyether polyols having an ethylene oxide content of 5 to 50% by weight and a number average molecular weight of 2000 to 7000 are further added. A flexible foamed polyurethane foam characterized by containing 1 to 50% by weight based on the polyol and a method for producing the same were found.

  By using the polyether polyol used in the present invention, a flexible foamed polyurethane foam with improved compression strain and excellent durability can be produced.

  Hereinafter, the present invention will be described in detail.

  The flexible foamed polyurethane foam of the present invention reacts a polyol with an organic polyisocyanate in the presence of a foaming agent, a foam stabilizer, and a catalyst, uses water as a foaming agent, and has an average polymerization degree of 2 to 4 as a polyol component. After adding propylene oxide to the polyglycerin, a polyether polyol having an ethylene oxide content of 5 to 50% by weight and a number average molecular weight of 2,000 to 7000 with respect to the total polyol is further added. In an amount of 1 to 50% by weight. When the initiator constituting the polyether polyol used in the present invention has a smaller number of functional groups than diglycerin having an average polymerization degree of 2, the hardness, mechanical strength and durability of the resulting foam will be insufficient, and compression strain will be reduced. growing. In addition, when there are more functional groups than tetraglycerin having an average degree of polymerization of 4, the inherent hardness of the flexible foam cannot be obtained, and the elongation and mechanical strength tend to decrease. When the number average molecular weight of the polyether polyol is less than 2,000, the flexibility of the resulting foam tends to be insufficient, and when the number average molecular weight exceeds 7,000, the curing becomes insufficient and the compression strain increases. . In addition, in the case of a polyether polyol having a number average molecular weight of 2000 to 7000 obtained by adding only propylene oxide to polyglycerin having an average degree of polymerization of 2 to 4, the reaction with isocyanate is slow, and a good foam cannot be obtained. In addition, in the case of a polyether polyol having a number average molecular weight of 2000 to 7000 obtained by adding only ethylene oxide to polyglycerin having an average degree of polymerization of 2 to 4, the reaction with the isocyanate is accelerated, but the distortion of the foam is remarkably increased. . Therefore, after adding propylene oxide to polyglycerol having an average degree of polymerization of 2 to 4, the ethylene oxide content of further adding ethylene oxide is 5 to 50% by weight and the number average molecular weight is 2000 to 7000. However, if the ethylene oxide content is less than 5% by weight, the reaction with isocyanate is slow, and if it exceeds 50% by weight, the distortion of the foam increases, so 5 to 50% by weight is added. It is necessary to make it. Moreover, when the addition amount with respect to all the polyols is less than 1% by weight, the compression distortion of the resulting foam increases, and when it exceeds 50% by weight, the foam stability at the time of foaming deteriorates and a good foam is obtained. Therefore, it is necessary to add 1 to 50% by weight. From these things, after adding propylene oxide to diglycerin or triglycerin among all polyols, the content of ethylene oxide further added with ethylene oxide is 15 to 40% by weight of the whole, and the number average It is preferable to contain 10 to 30% by weight of a polyether polyol having a molecular weight of 3000 to 6000.

  In producing the flexible foamed polyurethane foam of the present invention, after adding propylene oxide to polyglycerin having an average degree of polymerization of 2 to 4, the ethylene oxide content further added with ethylene oxide is 5 to 50% by weight of the whole. In addition, polyols other than polyether polyols having a number average molecular weight of 2000 to 7000 may be those known in the art, and ring-opening polymerization of cyclic ether containing alkylene oxide is performed using an active hydrogen group-containing compound as an initiator. Is obtained. As initiators, ethylene glycol, propylene glycol, butanediol, diethylene glycol, dipropylene glycol, pentanediol, hexanediol, octanediol, nonanediol, neopentylglycol, 3-methyl-1,5-pentanediol, cyclohexane-1 , 4-diol, cyclohexane-1,4-dimethanol, bisphenol A, hydrogenated bisphenol A, glycerin, trimethylolpropane, pentaerythritol, sorbitol, sugar alcohols such as sucrose, glucose, fructose, ethylenediamine, Examples include propylene diamine, toluene diamine, metaphenylene diamine, diphenylmethane diamine, and xylylenediamine. Examples of cyclic ethers include alkylene oxides such as ethylene oxide, propylene oxide, and butylene oxide, alkyl glycidyl ethers such as methyl glycidyl ether, aryl glycidyl ethers such as phenyl glycidyl ether, and tetrahydrofuran. In addition, since the hardness of the foam obtained can be freely adjusted by using together what is called a polymer polyol which polymerized the vinyl monomer in polyol is used for a polyol, it is preferable. Examples of vinyl monomers include vinyl cyanide compounds such as acrylonitrile and methacrylonitrile, halogen-containing vinyl compounds such as vinyl chloride and vinylidene chloride, and aromatic ring-containing vinyl compounds such as styrene, α-methylstyrene and vinyltoluene. And acrylic compounds such as acrylic acid, methacrylic acid, methyl acrylate and methyl methacrylate, and vinyl ester compounds such as vinyl acetate. In addition, it is preferable that the hydroxyl value of all the polyols used when manufacturing the flexible foaming polyurethane foam of this invention is 30-80.

  Water used in the present invention is used as a foaming agent, and the amount of water is preferably 3 to 6 parts by weight per 100 parts by weight of polyol. When the blending amount of water is small, the generated carbon dioxide gas decreases, so it becomes difficult to maintain the expansion ratio. When the blending amount of water is large, the number of urea groups increases, so the mechanical strength of the foam and The impact resilience tends to decrease and the compressive strain tends to increase.

  As the catalyst used in the present invention, various urethanization catalysts known in the art are used in order to adjust the reaction rate and the foamability. Specifically, triethylamine, tripropylamine, tributylamine, N-methylmorpholine, N-ethylmorpholine, dimethylbenzylamine, N, N, N ′, N′-tetramethylhexamethylenediamine, N, N, N ′ , N ′, N ″ -pentamethyldiethylenetriamine, bis- (2-dimethylaminoethyl) ether, triethylenediamine, 1,8-diaza-bicyclo (5,4,0) undecene-7, 1,2-dimethylimidazole , Tertiary amines such as 1-butyl-2-methylimidazole, reactive tertiary amines such as dimethylethanolamine, N-trioxyethylene-N, N-dimethylamine, N, N-dimethyl-N-hexanolamine, These organic acid salts, stannous octoate, dibutyltin dilaurate, zinc naphthenate, etc. Organometallic compounds, and the like. The blending amount of the catalyst is preferably 0.005 to 5 parts by weight with respect to 100 parts by weight of the polyol.

  The foam stabilizer used in the present invention is an organic silicon surfactant known in the art, and the blending amount of the foam stabilizer is preferably 0.2 to 2 parts by weight with respect to 100 parts by weight of the polyol.

  Examples of the organic polyisocyanate used in the present invention include tolylene diisocyanate (TDI) such as 2,4- or 2,6-tolylene diisocyanate, 4,4′-diphenylmethane diisocyanate, and 3,3′-dimethyl-4. Diphenylmethane diisocyanate (MDI) such as 1,4′-diphenylmethane diisocyanate, phenylene diisocyanate (PDI) such as 1,3-phenylene diisocyanate, 1,4-phenylene diisocyanate, 1-chloro-2,4-phenylene disissocyanate, Diphenyl diisocyanates such as 4′-diphenyl diisocyanate, 3,3′-dimethyl-4,4′-diphenyl diisocyanate, 3,3′-dimethoxy-4,4′-diphenyl diisocyanate, 1,5-naphthalene diisocyanate Aromatic polyisocyanates such as naphthalene diisocyanate (NDI), crude TDI, modified TDI, crude MDI, modified MDI; aliphatic polyisocyanates such as hexamethylene diisocyanate, lysine diisocyanate; isophorone diisocyanate, cyclohexane-1,4-diisocyanate And alicyclic polyisocyanates such as hydrogenated MDI; and polymeric polyisocyanates thereof. These organic polyisocyanates can be used alone or in combination of two or more. Preferred organic polyisocyanates include aromatic polyisocyanates, particularly TDI, crude TDI, MDI, crude MDI, and the like, and mixtures of TDI and MDI (or crude MDI), including at least TDI, such as TDI alone. Including. The amount of the organic polyisocyanate used is such that the isocyanate index is 70 to 130, preferably 80 to 120, and more preferably about 90 to 110. If the isocyanate index is less than 70, the elasticity and durability of the foam tends to be lowered, and if it exceeds 130, the foam tends to be brittle.

  Hereinafter, although an example and a comparative example explain the present invention in more detail, the present invention is not limited to these. In Examples and Comparative Examples, “parts” represents “parts by weight” and “%” represents “% by weight”.

<Examples 1-4, Comparative Examples 1-5>
Polyol A: Hydroxyl value 56 mg KOH / g obtained by addition polymerization of propylene oxide to glycerin, Polyether polyol polyol B: Molecular weight 3000 3000 Addition polymerization of propylene oxide to glycerin, followed by addition polymerization of ethylene oxide 53 mg KOH / g Polyether polyol polyol C having an ethylene oxide content of 20% by weight and a molecular weight of 3000: a hydroxyl value of 73 mgKOH / g, an ethylene oxide content of 40% by weight after addition polymerization of propylene oxide to diglycerin and then addition polymerization of ethylene oxide Polyether polyol polyol D having a molecular weight of 3100: a hydroxyl value of 51 mg KOH / g obtained by addition polymerization of propylene oxide to diglycerin and then addition polymerization of ethylene oxide, ethylene Polyether polyol polyol E having an oxide content of 15% by weight and a molecular weight of 4400: a hydroxyl value of 50 mgKOH / g, an ethylene oxide content of 15% by weight after addition polymerization of propylene oxide to triglycerin followed by addition polymerization of ethylene oxide, Polyether polyol polyol F having a molecular weight of 5600: A polyether polyol polyol G having a hydroxyl value of 60 mg KOH / g, an ethylene oxide content of 80% by weight and a molecular weight of 3700, obtained by addition polymerization of propylene oxide to diglycerin and then addition polymerization of ethylene oxide. : After addition polymerization of propylene oxide to triglycerin, followed by addition polymerization of ethylene oxide, a hydroxyl value of 30 mg KOH / g, ethylene oxide content of 50% by weight, molecular weight of 9350 Ether polyol polyol H: Polypropylene polyol foam stabilizer having a hydroxyl value of 80 mg KOH / g, an ethylene oxide content of 50% by weight and a molecular weight of 4200 obtained by addition polymerization of propylene oxide to sorbitol and then addition polymerization of ethylene oxide: Shin-Etsu Silicone ( Silicone foam stabilizer "FT-242T" manufactured by KK
Catalyst A: DABCO (dipropylene glycol solution containing triethylenediamine at a concentration of 33% by weight)
Catalyst B: Tin 2-ethylhexanoate organic polyisocyanate: TDI mixture isocyanate in which the isomer ratio of 2,4-tolylene diisocyanate and 2,6-tolylene diisocyanate is 80/20

  A mixture of polyol, water, catalyst and foam stabilizer and organic polyisocyanate were weighed in proportions shown in Table 1 and mixed with a high speed mixer. Immediately after mixing, the mixture was poured into an aluminum mold (inner dimensions 400 × 400 × 70 mm) previously adjusted to 62 ± 2 ° C., the lid was closed, and held as it was for 5 minutes to perform foam molding. The foam was taken out from the mold, and the properties of the obtained flexible foamed polyurethane foam were measured according to JIS K 6401. The results are shown in Table 1.

By blending a specific polyether polyol, it becomes possible to obtain a low-density flexible foamed polyurethane foam with improved compression strain and durability. Therefore, interior materials for vehicles, furniture cushion materials, bedding, It can be suitably used as a material for miscellaneous goods.

Claims (1)

In the production of a flexible foamed polyurethane foam obtained by reacting a polyol with an organic polyisocyanate in the presence of a foaming agent, a foam stabilizer, and a catalyst, water is used as the foaming agent, and the average degree of polymerization is 2 to 2 as the polyol component. After adding propylene oxide to polyglycerin 4 and further adding ethylene oxide, polyether polyol having an ethylene oxide content of 5 to 50% by weight and a number average molecular weight of 2000 to 7000 is used as the total polyol. 1 to 50% by weight of a flexible foamed polyurethane foam and a method for producing the same.