JP2010053157A - Manufacturing method of flexible polyurethane foam - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a flexible polyurethane foam that exhibits excellent water resistance and alkali resistance and a very good compression set. <P>SOLUTION: The polyurethane foam is obtained by causing a polyol component (A) to react with diphenylmethane diisocyanate-based polyisocyanate (B) in the presence of a catalyst (C), a foam stabilizer (D), a blowing agent (E) and a crosslinking agent (F), where the polyol contains 10-50 mass%, based on the polyol component (A), of a castor oil-based polyol (a1), a vegetable-derived raw material. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a method for producing a flexible polyurethane foam. More specifically, the present invention relates to a method for producing a flexible polyurethane foam which is excellent in water resistance and alkali resistance by using castor oil, which is a plant-derived polyol, and has very good compression residual strain.

Conventionally, flexible polyurethane foams have been widely used as cushioning materials and cushioning materials for sofas and the like because they have flexibility and excellent shock absorption. However, many polyurethane foams are lightweight using toluene diisocyanate-based polyisocyanate, and it is difficult to say that the foam physical properties are sufficient for aging durability. In addition, since toluene diisocyanate-based polyisocyanate has high volatility, there is a concern that the isocyanate at the production site may affect the health of workers. Furthermore, since conventional polyurethane foams have insufficient water resistance or alkali resistance performance against alkaline detergents, there is a problem that the strength is lowered due to swelling or deterioration when washed. As a method for producing a flexible polyurethane foam excellent in water resistance, for example, when the polyol component contains polyoxyalkylene polyol and the polyoxyalkylene polyol is 100% by weight, the content of oxyethylene units is 18% by weight. % Or less has been proposed (see Patent Document 1), but there is no description of durability.
JP 09-071627 A JP 2006-104404 A

  An object of the present invention is to provide a flexible polyurethane foam which is excellent in water resistance and alkali resistance and which has a very good compressive residual strain. Further, in order to improve the working environment, toluene diisocyanate-based polyisocyanate is not used, and from the viewpoint of recent environmental conservation, many plant-derived raw materials having a low environmental load are used.

  In order to solve the above problems, the present inventors provide a foam having excellent physical properties such as water resistance, alkali resistance, and compression residual strain. Think about polyols, foaming agents, foam stabilizers and other auxiliaries, polymerization conditions and polymerization catalysts, and how to obtain flexible polyurethane foam with the proper density and hardness range. Various investigations were conducted, and experimental trials and multifaceted considerations were repeated.

  In these processes, as a result of repeated examination and trials, in order to solve the above-mentioned problems, the use of plant-derived castor oil-based polyol as the polyol component can solve the problem of the present invention. It has been found that the present invention is very effective for providing a flexible polyurethane foam that is capable of being made and has excellent physical properties such as water resistance, alkali resistance, and compressive residual strain.

  In the present invention, the amount of castor oil-based polyol (a1) to be used is particularly effective when it is in the range of 10 to 50% by mass relative to the polyol component (A).

The basic main components in the present invention are polyol component (A), diphenylmethane diisocyanate polyisocyanate (B), catalyst (C), foam stabilizer (D), foaming agent (E), and crosslinking agent (F). In the method for producing a flexible polyurethane foam with a molding composition comprising other auxiliary agents, the castor oil-based polyol (a1) is added in an amount of 10 to 50% by mass based on the polyol component (A). This is a method for producing a flexible polyurethane foam.
Furthermore, in the present invention, when a polyol component, diphenylmethane diisocyanate polyisocyanate, a foaming agent, or the like is specifically specified, a more excellent improvement result can be obtained.

  In the present invention, it becomes possible to obtain physical properties such as water resistance, alkali resistance, and excellent compression residual strain in a flexible polyurethane foam. For this reason, in the flexible polyurethane foam obtained by this invention, it can utilize mainly as a cushioning material which can be wash | cleaned, and a buffer material around a washing machine, and is very useful.

Further, the contents of the present invention will be described in detail.
First, the polyol component (A) used in the production of the polyurethane foam in the present invention is a polyaddition with a diisocyanate to form a polyurethane. The castor oil-based polyol (a1), the polyether polyol (a2), and the polymer polyol (A3).

The castor oil-based polyol (a1) may be any of refined castor oil, semi-refined castor oil, unrefined castor oil, hydrogenated castor oil to which hydrogen is added, castor oil fatty acid and polyol (the above low molecular polyol And / or polyether polyol), for example, diglyceride of castor oil fatty acid, monoglyceride, castor oil fatty acid and trimethylol alkane mono-, di- or triester, castor oil fatty acid and Mono-, di-, or triester with polypropylene glycol. Among these, it is preferable to use unmodified castor oil from the viewpoint of removing petroleum from chemical raw materials and protecting the environment. Here, the main component of “castor oil” is triglyceride of ricinoleic acid, and “castor oil” includes hydrogenated castor oil.
The main component of “castor oil fatty acid” is ricinoleic acid, and “castor oil fatty acid” includes hydrogenated castor oil fatty acid. Examples of the “trimethylol alkane” include trimethylol methane, trimethylol ethane, trimethylol propane, trimethylol butane, trimethylol pentane, trimethylol hexane, trimethylol heptane, trimethylol octane, trimethylol nonane, and trimethylol decane. Can be mentioned. The number average molecular weight of castor oil or castor oil-based modified polyol is preferably 500 to 6,000, more preferably 900 to 2,000. By using a castor oil-based polyol (a1) having a number average molecular weight of 900 to 2,000, it is possible to obtain a flexible polyurethane foam having a density and hardness range suitable for applications such as cushioning materials and cushioning materials. . Specific examples include URIC H-24 and URIC H-30 manufactured by Ito Oil Co., Ltd., but are not limited thereto. The castor oil-based polyol (a1) is preferably used in an amount of 10 to 50% by mass based on the polyol component (A). If it is less than this range, water resistance and alkali resistance performance cannot be fully exhibited. Moreover, if it exceeds this range, the moldability will be deteriorated.

  In the present invention, the polyether polyol (a2) preferably has a number average molecular weight of 1,000 to 10,000 and a nominal functional group number of 2 or more. When the number average molecular weight is less than the lower limit, the flexibility of the resulting foam is insufficient, and when it exceeds the upper limit, the hardness of the foam tends to decrease. Further, when the nominal functional group number is less than 2, there arises a problem that the compression residual strain is deteriorated. In addition, a nominal functional group number means the functional group number of the initiator used when obtaining a polyol.

  As (a2), polypropylene ethylene polyol (PPG), polytetramethylene ether glycol (PTG) or the like is used. As the polyester polyol, polycondensation type polyester polyol adipic acid ethylene glycol polyester polyol, lactone type polyester polyol Polycaprolactone polyol and the like are used.

The polymer polyol (a3) is a method of polymerizing an ethylenically unsaturated monomer in a polyether polyol, a method of mixing separately produced polymer fine particles into a polyether polyol, a macromonomer having an ethylenically unsaturated group, and an ethylenically unsaturated group. It is produced by a method in which a monomer is polymerized in a polyether polyol.
Examples of the ethylenically unsaturated monomer include styrene and acrylonitrile. Of these, those obtained by polymerizing ethylenically unsaturated monomers in polyether polyol are preferred, and those obtained by polymerizing ethylenically unsaturated monomers in polyoxypropylene triol are more preferred. The content of the polymer fine particles is preferably 50% by mass or less, particularly preferably 30% by mass or less, based on the total polyol. When the content of the polymer fine particles exceeds 50% by mass, the viscosity of the polymer polyol becomes high and workability at the time of molding deteriorates.

  As the polyol component (A), in addition to the above (a1) to (a3), a polyester polyol, a polycarbonate polyol, a polybutadiene polyol, a lactone polyol and the like can be used in combination.

The polyisocyanate component used in the production of the polyurethane foam in the present invention is diphenylmethane diisocyanate-based polyisocyanate (B).
Specific examples of the diphenylmethane diisocyanate polyisocyanate (B) include diphenylmethane diisocyanate (pure) comprising 4,4′-diphenylmethane diisocyanate, 2,4′-diphenylmethane diisocyanate, 2,2′-diphenylmethane diisocyanate, and mixtures thereof. Various modified products such as MDI), polymethylene polyphenylene polyisocyanate (p-MDI), urethane-modified products, urea-modified products, allophanate-modified products, and burette-modified products can also be used. In particular, when a pure MDI, a mixture of MDI and p-MDI is used, a higher quality flexible polyurethane foam can be obtained. Moreover, it is preferable that the average functional group number of diphenylmethane diisocyanate type polyisocyanate (B) exists in the range of 2.1-2.5. When the average number of functional groups is less than 2.1, the molding stability of the resulting foam is insufficient, and it is difficult to obtain a foam having good durability. If it exceeds 2.5, the elongation rate of the foam tends to decrease.

As the catalyst (C), various urethanization catalysts known in the art can be used.
For example, 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- Examples of the organic metal compound include dimethylimidazole, dimethylethanolamine, N, N-dimethyl-N-hexanolamine, and organic acid salts thereof, stannous octoate, and zinc naphthenate. Further, amine catalysts having active hydrogen such as N, N-dimethylethanolamine and N, N-diethylethanolamine are also preferable.
The addition amount of the catalyst (C) is preferably 0.01 to 10% by weight with respect to the polyol component (A). If it is less than this range, the curing tends to be insufficient, and if it exceeds this range, the moldability may deteriorate.

As the foam stabilizer (D), an ordinary surfactant is used, and an organosilicon surfactant can be suitably used. Examples thereof include B-4113LF manufactured by Goldschmidt Co., Ltd. and L-5309 manufactured by Nihon Unicar Co., Ltd. These can be used alone or in admixture of two or more.
The amount of the foam stabilizer (D) added is preferably 0.01 to 10% by weight with respect to the polyol component (A) in order to form a uniform cell.

As the foaming agent (E), water is mainly used. Water generates carbon dioxide gas by reaction with the isocyanate group, which causes foaming. Moreover, you may use arbitrary foaming agents in addition to water. For example, a small amount of a low-boiling organic compound such as cyclopentane or isopentane may be used in combination, or air, nitrogen gas, or liquefied carbon dioxide may be mixed and dissolved in the stock solution using a gas loading device and foamed.
The amount of foaming agent added depends on the set density of the resulting product. Usually, it is 0.5 to 15% by weight with respect to the polyol component (A), but it is preferably 0.8 to 1.5% by weight when considered as a cushioning material or cushioning material. If the upper limit is exceeded, foaming may become difficult to stabilize, and if it is less than the lower limit, foaming may not be effective.

Preferred examples of the crosslinking agent (F) include low-molecular active hydrogen compounds having a molecular weight of less than 500, such as low-molecular alcohols, low-molecular amines, and low-molecular amino alcohols used in the synthesis of the polyester polyol described above. Can do.
These can be used alone or in combination of two or more. Of these, low molecular amino alcohols and further diethanolamine are preferred from the viewpoint of slow reaction with isocyanate groups.

  In the production of the flexible polyurethane foam in the present invention, an anti-aging agent such as an antioxidant and an ultraviolet absorber, a filler such as calcium carbonate and barium sulfate, a flame retardant, a plasticizer, a colorant, and an antifungal agent. Various known additives and auxiliaries such as can be used as necessary.

  Next, although this invention is demonstrated concretely based on an Example and a comparative example, this invention is not limited to these Examples, unless the summary is exceeded. Unless otherwise specified, “%” in the text is based on mass.

Examples 1-8, Comparative Examples 1-6
Among the raw materials shown in Tables 1, 2, and 3, the liquid temperature of the mixture of all raw materials other than the polyisocyanate compound (polyol system) is adjusted to 25 ° C. ± 1 ° C., and the polyisocyanate compound is adjusted to the liquid temperature 25 ± 1 ° C. did. Add a predetermined amount of polyisocyanate compound to the polyol system, mix for 7 seconds with a mixer (7000 rpm), inject into the mold, foam the polyurethane foam, take out from the mold, crushing process (foam urethane foam And letting the gas inside the molded product escape by breaking the cell), and the physical properties of the obtained flexible polyurethane foam were measured. In Tables 1, 2, and 3, the isocyanate index (NCO Index) is an equivalent ratio of NCO groups to NCO reactive groups (NCO / NCO reactive groups) present in the formulation.
[Foaming conditions]
Mold temperature: 55-60 ° C
Mold shape: 100 × 300 × 300mm
Mold material: Aluminum cure Condition: 55-60 ° C x 6 minutes Crushing condition: Five-stage crushing roller

[Raw materials]
(Polyol component)
Polyol 1: Polyoxyethylene polyoxypropylene polyol having an EO terminal content of 14%, an average number of functional groups = 3.0, and a hydroxyl value = 24 (mgKOH / g) obtained by adding PO / EO, Asahi Glass Urethane Co., Ltd. EL-851B made
Polyol 2: Polymer polyol having an average number of functional groups of 3.0 and a hydroxyl value of 28 (mgKOH / g) obtained by addition polymerization reaction of PO / EO with glycerin and further polymerization of acrylonitrile monomer, EL manufactured by Asahi Glass Urethane Co., Ltd. -910
Polyol 3: Unrefined castor oil having an average functional group number of 2.7 and a hydroxyl value of 160 (mgKOH / g), URIC · H-24 manufactured by Ito Oil Co., Ltd.
Polyol 4: NE-697 manufactured by Nippon Polyurethane Industry Co., Ltd. prepared by blending two types of commercially available polyoxyethylene polyoxypropylene polyols and adjusting the polyol component (A) to have an EO content of 14.1%.
Polyol 5: NE-698 manufactured by Nippon Polyurethane Industry Co., Ltd., which was prepared by blending two commercially available polyoxyethylene polyoxypropylene polyols and adjusting the EO content in the polyol component (A) to 12.6%.
Polyol 6: NE-699 manufactured by Nippon Polyurethane Industry Co., Ltd. prepared by blending two types of commercially available polyoxyethylene polyoxypropylene polyols and adjusting the EO content in the polyol component (A) to 11.9%.
Polyol 7: NE-700 manufactured by Nippon Polyurethane Industry Co., Ltd. prepared by blending two commercially available polyoxyethylene polyoxypropylene polyols and adjusting the EO content in the polyol component (A) to 11.2%.
Polyol 8: NE-701 manufactured by Nippon Polyurethane Industry Co., Ltd. prepared by blending two commercially available polyoxyethylene polyoxypropylene polyols and adjusting the polyol component (A) to have an EO content of 6.7%.
Polyol 9: NE-702 manufactured by Nippon Polyurethane Industry Co., Ltd. prepared by blending two types of commercially available polyoxyethylene polyoxypropylene polyols and adjusting the polyol component (A) to have an EO content of 5.3%.

(Polyisocyanate component)
Polyisocyanate 1: Nominal average functional group number = 2.27, NCO content = 28.8%, viscosity = 100 mPa · s MDI polyisocyanate (trade name “CEF-300”, manufactured by Nippon Polyurethane Industry Co., Ltd.)
Polyisocyanate 2: Toluene diisocyanate-based polyisocyanate

(catalyst)
Catalyst 1: 33% dipropylene glycol solution of triethylenediamine, TEDA-L33 manufactured by Tosoh Corporation
Catalyst 2: 70% dipropylene glycol solution of bis (2-dimethylaminoethyl) ether, TOYOCAT ET manufactured by Tosoh Corporation

(Foam stabilizer)
Foam stabilizer: Silicone foam stabilizer, B-4113LF manufactured by Goldschmid Co., Ltd.

[Method for measuring physical properties of polyurethane foam]
This was performed based on the method of JIS K6401.
25% ILD is a force obtained when a foam sample is compressed by 25% and is an index representing hardness.
The evaluation of alkali resistance was carried out by immersing the foam in an alkaline aqueous solution of pH = 13 for 5 days at 25 ° C., and maintaining the swelling ratio (%) of the foam, tensile strength, elongation and tear strength after immersion. The measurement was performed by measuring the rate (%).

Swelling rate (%)
= {(Length of specimen after immersion-length of specimen before immersion) / length of specimen before immersion} × 100

The water resistance was evaluated by immersing the foam in tap water for 5 days at 25 ° C., and the swelling ratio (%) of the foam after immersion, and the retention ratio (%) of the tensile strength, elongation ratio, and tear strength. It was done by measuring.

  As shown in Comparative Examples 1 and 2 in Table 1, when 10% of toluene diisocyanate polyisocyanate is contained in the polyisocyanate component, the curing property is lowered and the moldability is deteriorated. Even when the content of the toluene diisocyanate polyisocyanate is less than 10%, the high volatility of the toluene diisocyanate polyisocyanate is likely to affect the health of workers at the production site.

  As shown in Comparative Example 3 in Table 2, when the castor oil-based polyol is not used, the stability of the foam is deteriorated and the filling property is deteriorated. In addition, in the water resistance test and alkali resistance test, the swelling rate increases, and the retention rate of mechanical properties decreases. On the other hand, as shown in Comparative Example 4, when the amount of castor oil-based polyol used exceeds 50% by mass, the foam is so strong that cracking occurs in the crushing process after demolding.

  Table 3 shows the physical property measurement results of the flexible polyurethane foams prepared by fixing the castor oil-based polyol to 20% by mass and adjusting the EO content by changing the mixing ratio of the polyol component (A). As shown in Comparative Example 5, when the EO content is too large, the stability of the foam deteriorates and the filling property deteriorates. In addition, in the water resistance test and alkali resistance test, the swelling rate increases, and the retention rate of mechanical properties decreases. On the other hand, as shown in Comparative Example 6, when the EO content is too small, the foam has a high foaming property, and cracking occurs in the crushing process after demolding.

By comparing each of the above Examples and Comparative Examples, in the present invention, diphenylmethane diisocyanate-based polyisocyanate (B) is used, castor oil-based polyol (a1) is blended in an amount of 10 to 50% by mass, and a polyol component When the EO content of (A) is 6% to 13%, it is clear that a polyurethane foam having excellent work environment properties, water resistance, alkali resistance, and durability (compression residual strain) can be obtained. Therefore, the significance and remarkable excellence of the configuration of the present invention can be understood.

Claims (5)

  A soft product obtained by reacting a polyol component (A) with diphenylmethane diisocyanate polyisocyanate (B) in the presence of a catalyst (C), a foam stabilizer (D), a foaming agent (E) and a crosslinking agent (F). A method for producing a flexible polyurethane foam, characterized in that the castor oil-based polyol (a1), which is a plant-derived raw material, is contained in an amount of 10 to 50% by mass based on the polyol component (A).   A method for producing a flexible polyurethane foam, wherein the polyol component (A) according to claim 1 comprises a castor oil-based polyol (a1), a polyether polyol (a2), and a polymer polyol (a3).   The method for producing a flexible polyurethane foam according to claim 1 or 2, wherein the polyol component (A) has an oxyethylene group content of 6% to 13%.   The method for producing a flexible polyurethane foam according to any one of claims 1 to 3, wherein the average functional group number of the diphenylmethane diisocyanate-based polyisocyanate (B) is in the range of 2.1 to 2.5. 5. The method for producing a flexible polyurethane foam according to claim 1, wherein the foam density is 70 to 120 kg / m ³ and the 25% ILD is 250 to 950 N / 314 cm ² .