JP2006282744A - Polyisocyanate for flexible polyurethane slab foam and method for producing flexible polyurethane slab foam using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polyisocyanate for flexible polyurethane slab foams, which has improved low temperature storage stability, low viscosity, and good workability, and to provide a method for producing the flexible polyurethane slab foam which has good productivity/moldability and whose density can be lowered. <P>SOLUTION: This polyisocyanate for flexible polyurethane slab foams is obtained by charging and reacting the following polymeric MDI (diphenylmethanediisocyanate)(a) with the following polyol (b) in a (a)/(b) mass ratio of 80/20 to 95/5 and having an isocyanate content of 25 to 32 mass%. The polymeric MDI (a): the content of a binuclear compound component is 50 to 80 mass%, and the content of isomers except 4,4'-MDI in the binuclear compound component is 10 to 20 mass%. The polyol (b): a polyether polyol having a nominal average functional group number of 4 and a number-average mol.wt. of 5,000 to 10,000. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a polyisocyanate for a flexible polyurethane slab foam and a method for producing a flexible polyurethane slab foam using the same. More specifically, production of a polyisocyanate for a flexible polyurethane slab foam having improved low-temperature storage stability, low viscosity and good workability, and a flexible polyurethane slab foam having good productivity and moldability and capable of reducing the density. It is about the method.

  Soft polyurethane slab foam is cut to an appropriate size and is used in a wide range of applications such as cushioning materials for furniture and automobile seats, mattresses for bedding, pillows, industrial sealing materials, and soundproofing materials. In recent years, with the aging of the population, there is an increasing need for good support for furniture and mattress applications, as well as a highly flame retardant foam. In production sites, a highly reactive and highly curing raw material system with high production efficiency is desired.

  A technique using toluene diisocyanate (hereinafter abbreviated as TDI) as a polyisocyanate component as a flexible polyurethane slab foam is already widely known. However, the freezing point of TDI is as high as about 17 ° C. under normal pressure, and since it solidifies in winter, it is necessary to keep the temperature and adjust the temperature.

  Recently, we have also proposed flexible polyurethane slab foams that use diphenylmethane diisocyanate (hereinafter abbreviated as MDI), which has a low vapor pressure, as a polyisocyanate component because of its impact on the health of workers at production sites and improved reactivity. Has been. However, the freezing point of 4,4′-MDI is about 38 ° C. under normal pressure, which is higher than TDI and requires pretreatment such as prepolymerization. As a result, the viscosity becomes very high. There were problems such as deterioration and restrictions due to production equipment conditions.

  The present applicant has proposed a method for producing a flexible polyurethane slab foam disclosed in Patent Document 1 as a technique for improving the above points.

JP 2002-322236 A

  According to the present invention, polyisocyanate for flexible polyurethane slab foam having further improved low-temperature storage stability, low viscosity and good workability, and flexible polyurethane slab foam having good productivity and moldability and capable of reducing the density. It became possible to provide a manufacturing method.

  Low-temperature storage stability is further improved compared to conventional polyisocyanates for flexible polyurethane slab foam, low-viscosity polyisocyanates for flexible polyurethane slab foam with good workability, and productivity and moldability are good, resulting in low density. It is an object of the present invention to provide a method for producing a possible flexible polyurethane slab foam.

That is, the present invention is as follows.
(1) Polymeric MDI (I) and polyol (B) shown below are charged and reacted at (A) / (B) = 80/20 to 95/5 (mass ratio), and the isocyanate content is Polyisocyanate for flexible polyurethane slabs, which is 25 to 32% by mass.
Polymeric MDI (I):
Polymeric MDI having a binuclear component content of 50 to 80% by mass and an isomer content other than 4,4′-MDI in the dinuclear component of 10 to 20% by mass
Polyol (b):
Polyether polyol having a nominal average functional group number of 4 and a number average molecular weight of 5,000 to 10,000

(2) A mixed liquid of polyisocyanate (A), polyol (B), catalyst (C), water (D) as a foaming agent, and foam stabilizer (E) for the flexible polyurethane slab of (1) is used as a box or a conveyor. A method for producing a flexible polyurethane slab foam, characterized by continuously injecting and reactive foaming.

(3) The method for producing a flexible polyurethane slab foam according to (2) above, wherein the catalyst (C) contains an acid blocked product of a tertiary amine.

The present invention will be described in further detail.
The polyisocyanate for a flexible polyurethane slab of the present invention is prepared by reacting the following polymeric MDI (I) and polyol (B) at (A) / (B) = 80/20 to 95/5 (mass ratio). And a polyisocyanate having an isocyanate content of 25 to 32% by mass.
Polymeric MDI (I):
Polymeric MDI having a binuclear component content of 50 to 80% by mass and an isomer content other than 4,4′-MDI in the dinuclear component of 10 to 20% by mass
Polyol (b):
Polyether polyol having a nominal average functional group number of 4 and a number average molecular weight of 5,000 to 10,000

  The polyisocyanate for a flexible polyurethane slab of the present invention is prepared by reacting a polymeric MDI (I) and a polyol (B), which will be described later, at (A) / (B) = 80/20 to 95/5 (mass ratio). Polyisocyanate obtained and having an isocyanate content of 25 to 32% by mass.

  In the mass ratio of polymeric MDI (I) and polyol (B), if the amount of polymeric MDI (I) is too small, the viscosity of the resulting flexible polyurethane slab foam increases, and the workability during the production of the flexible polyurethane slab foam decreases. To do. On the other hand, when there is too much polymeric MDI (I), the intensity | strength of the flexible polyurethane slab foam obtained will fall.

The polymeric MDI (A) used in the present invention will be described.
Polymeric MDI (I) is a polyisocyanate obtained by phosgenating a condensate of aniline and formalin. Such polymeric MDI (A) exists as a mixture of a binuclear (MDI) component and two or more polynuclears.

  When condensing aniline and formalin, the ratio of the isomers in the binuclear body (MDI) and the ratio of the binuclear body to the polynuclear body can be changed by controlling the raw material charge ratio and the reaction temperature. Furthermore, by mixing commercially available MDI and polymeric MDI as appropriate, the isomer composition ratio in the binuclear (MDI) component and the ratio between the binuclear component and the polynuclear can be controlled. The isomers of MDI include 2,2'-MDI, 2,4'-MDI, and 4,4'-MDI. Hereinafter, in the present invention, the “nucleus” of polymeric MDI refers to a benzene ring structure.

  The content of the binuclear component of the polymeric MDI (I) used in the present invention is 50 to 80% by mass, and the content of isomers other than 4,4′-MDI in the dinuclear component is 10 to 20% by mass. When the content of the dinuclear component is less than the lower limit, the viscosity of the resulting polyisocyanate for flexible polyurethane slab foam increases, and workability during the production of the flexible polyurethane slab foam decreases. When exceeding an upper limit, the low temperature storage stability of the polyisocyanate for flexible polyurethane slab foams obtained will fall. On the other hand, when the content of isomers other than 4,4′-MDI in the dinuclear component is less than the lower limit, the low-temperature storage stability of the polyisocyanate for flexible polyurethane slab foam to be obtained is lowered. When the upper limit is exceeded, the flexibility of the resulting flexible polyurethane slab foam is lowered.

  In addition, it is also possible to use other isocyanate together for the purpose of flowability, hardness, foaming speed adjustment and the like. Specific examples include 2,2'-MDI, 2,4'-MDI, 4,4'-MDI, 2,4-TDI, 2,6-TDI, p-phenylene diisocyanate, m-phenylene diisocyanate, o- Aromatic diisocyanates such as xylylene diisocyanate, m-xylylene diisocyanate, p-xylylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, 2-methyl-1,5-pentane diisocyanate, 3-methyl-1,5-pentane diisocyanate Aliphatic diisocyanates such as aliphatic diisocyanate, isophorone diisocyanate, hydrogenated diphenylmethane diisocyanate, hydrogenated tolylene diisocyanate, hydrogenated xylylene diisocyanate, cyclohexyl diisocyanate, etc. Diisocyanate, biuret modified products of these diisocyanates, isocyanurate modified body, uretonimine modified product, a carbodiimide modified product, a urethane group-containing polyisocyanates, and the like with polyols modified.

  The polyol (b) used in the present invention is a polyether polyol having a nominal average functional group number of 4 and a number average molecular weight of 5,000 to 10,000. If the nominal average functional group number is too low or the number average molecular weight is too high, the physical properties of the resulting flexible polyurethane slab foam will deteriorate. When the number of nominal average functional groups is too high or the number average molecular weight is too low, the viscosity of the resulting polyisocyanate for flexible polyurethane slab foam becomes too high.

  The polyol (b) used in the present invention is an alkylene such as ethylene oxide (hereinafter abbreviated as EO) or propylene oxide (hereinafter abbreviated as PO) with a low molecular tetraol such as pentaerythritol as an initiator. It can be obtained by ring-opening addition polymerization of oxide. In the present invention, the “nominal average functional group number” refers to the functional group number of an initiator used when obtaining a polyol.

  In the present invention, a mixed liquid of the above-mentioned polyisocyanate (A), polyol (B), catalyst (C), water (D) as a blowing agent, and foam stabilizer (E) for a flexible polyurethane slab is placed on a box or a conveyor. This is a method for producing a flexible polyurethane slab foam, characterized by continuously injecting and reacting foam.

  The preferred polyol (B) used in the present invention is a poly (oxyalkylene) polyol having a nominal average functional group number of 2 to 5 and a number average molecular weight of 3,000 to 8,000, particularly preferably a terminal ethylene oxide cap. Of polyoxypropylene polyol. When the number average molecular equivalent of the polyol (B) is less than 3,000, the flexibility of the foam cannot be obtained. On the other hand, if it exceeds 8,000, the viscosity of the liquid is too high and workability is lowered.

  Such a polyol (B) is a polyol such as water, propylene glycol, dipropylene glycol, glycerin, trimethylolpropane, pentaerythritol, sorbitol, or an amino alcohol such as diethanolamine, triethanolamine, or tripropanolamine, or It can be obtained by ring-opening addition of alkylene oxides such as EO and PO to amines such as ethylenediamine, 1,6-hexanediamine, triethylenetetraamine, aniline, toluylenediamine, and methylenebisaniline.

  In the present invention, a polymer polyol having a solid content of 15 to 50% by mass, a nominal average number of functional groups of 2 to 4, and a number average molecular weight of 1,000 to 10,000 is further used for the purpose of improving flame retardancy and adjusting the hardness. Is preferred. Base polyols include water, propylene glycol, dipropylene glycol, glycerin, trimethylolpropane, pentaerythritol and other polyols, diethanolamine, triethanolamine, tripropanolamine and other amino alcohols, ethylenediamine, Polyether polyols obtained by adding alkylene oxides such as ethylene oxide and propylene oxide to amines such as 6-hexanediamine, triethylenetetraamine, and methylenebisaniline can be used. Examples of the polymer particle component include polymers of ethylenically unsaturated monomers such as acrylonitrile, styrene, and methyl methacrylate and / or aminoplast resins selected from urea, melamine, and phenol.

  As the catalyst (C) used in the present invention, various urethanization catalysts and trimerization catalysts known in the art can be used. Typical examples include triethylamine, tripropylamine, tributylamine, N-methylmorpholine, N-ethylmorpholine, dimethylbenzylamine, N, N, N ′, N′-tetramethylhexamethylenediamine, N, N, N ′, N ′, N ″ -pentamethyldiethylenetriamine, triethylenediamine, bis- (2-dimethylaminoethyl) ether, tertiary amines such as 1,8-diaza-bicyclo (5,4,0) undecene-7, dimethylethanolamine N-trioxyethylene-N, N-dimethylamine, reactive tertiary amines such as N, N-dimethyl-N-hexanolamine or organic acid salts thereof, 1-methimidazole, 2-methylimidazole, 1, 2-dimethylimidazole, 2,4-dimethylimidazole, 1-butyl-2- Imidazole compounds such as tilimidazole, stannous octoate, dibutyltin dilaurate, organometallic compounds such as zinc naphthenate, 2,4,6-tris (dimethylaminomethyl) phenol, 2,4,6-tris (dialkylaminoalkyl) ) A trimerization catalyst such as hexahydro-S-triazine, potassium acetate, potassium 2-ethylhexanoate, etc. In the present invention, the catalyst (C) preferably contains an acid blocked product of a tertiary amine.

  Preferred tertiary amine acid blocked products include triethylamine, tripropylamine, tributylamine, N-methylmorpholine, N-ethylmorpholine, dimethylbenzylamine, N, N, N ′, N′-tetramethylhexamethylenediamine, Tertiary amines such as N, N, N ′, N ′, N ″ -pentamethyldiethylenetriamine, triethylenediamine, bis- (2-dimethylaminoethyl) ether, formic acid, acetic acid, propionic acid, oxalic acid, succinic acid, Examples thereof include those blocked with a carboxylic acid such as adipic acid, sebacic acid and azelaic acid.

  The foaming agent (D) used in the present invention is foamed by carbon dioxide gas generated by the reaction between isocyanate groups and water. For the purpose of reducing the density, carbon dioxide is mixed in a liquid state and vaporized and foamed during foaming. A method can also be used together. The amount of water is preferably 2 to 20 parts by mass with respect to 100 parts by mass of the organic polyisocyanate. When using liquefied carbon dioxide together, the amount is preferably 0.5 to 6 parts by mass with respect to 100 parts by mass of the organic polyisocyanate.

  The foam stabilizer (E) used in the present invention is an organosilicon surfactant known in the art, for example, L-520, L-540, L-5309, L-5366, SZ- from Nippon Unicar. 1306, Toray Dow Corning SH-190, SH-192, SH-193, SH-194, SRX-274C, SF-2962, SF-2964, Goldschmidt B-4113, B-8680, Air Products Examples thereof include DC-2583, DC-5043, DC-5169 and the like. These foam stabilizers are preferably used in an amount of 0.1 to 3 parts by mass with respect to 100 parts by mass of the organic polyisocyanate.

  In addition, the present invention further comprises a communicating agent such as an EO / PO random copolymer, an antioxidant, an ultraviolet absorber, a colorant, various fillers, an internal mold release agent, an antifungal agent, an antibacterial agent and the like as necessary. These processing aids can be added and used. These auxiliaries are usually used by adding them to polyols, but processing auxiliaries having no active hydrogen group capable of reacting with isocyanate can be mixed in advance with the isocyanate component.

  The equivalent ratio (NCO / NCO reactive group) of all isocyanate reactive groups in the isocyanate reactive compound containing water and all isocyanate groups in the organic polyisocyanate of the present invention is 0.5 to 1.5 (isocyanate index = 50 to 150), and particularly preferably 0.7 to 1.2 (isocyanate index = 70 to 120).

  Although it is a manufacturing apparatus in the present invention, a multi-component foaming machine having a rotor rotating type or high pressure collision mixing type mixing head known in the art for mixing raw materials is used, and the mixed liquid from the head is box-shaped or By continuously foaming on a belt conveyor, a slab foam of any size can be obtained.

  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, “part” and “%” in the text are based on mass.

(Raw materials used)
(1) Isocyanate liquid polymeric MDI-1:
Polymeric MDI
Dinuclear content = 70%
Content of isomers other than 4,4′-MDI in the binuclear body = 15%
Viscosity 200mPa · s
NCO = 32.1%
Polymeric MDI-2:
Polymeric MDI
Dinuclear content = 70%
Isomer content other than 4,4'-MDI in the binuclear body = 5%
Viscosity 200mPa · s
NCO = 32.1%
Polymeric MDI-3:
Polymeric MDI
Dinuclear content = 70%
Isomer content other than 4,4'-MDI in dinuclear body = 40%
Viscosity 200mPa · s
NCO = 32.1%
Polyol-1:
Poly (oxypropylene) polyol Nominal average functional group number = 4
Number average molecular weight = 8,000
Polyol-2:
Poly (oxypropylene) polyol Nominal average functional group number = 3
Number average molecular weight = 6,000

(2) Polyol liquid polyol A:
Poly (oxypropylene) polyol with terminal EO cap Nominal functional group = 3
Number average molecular weight = 5,000
EO content = 14.5%
Polyol B:
Polymer dispersed terminal EO-capped poly (oxypropylene) polyol Nominal average functional groups = 3
Number average molecular weight = 5,000
EO content = 14.5%
Polymer type: Polyacrylonitrile Polymer content = 20%
Catalyst A:
Tertiary amine carboxylic acid blocked product Product name “Toyocat NCT” (manufactured by Tosoh Corporation)
Catalyst B:
Tertiary amine Brand name “Toyocat ET” (manufactured by Tosoh Corporation)
Catalyst C:
Tertiary amine dipropylene glycol solution Trade name “Toyocat L-33” (manufactured by Tosoh Corporation)
Catalyst D:
Dipropylene glycol solution of imidazole compound Trade name “Toyocat DP-70” (manufactured by Tosoh Corporation)
Foam stabilizer A:
Silicone foam stabilizer Product name "L-5309" (Nihon Unicar)
Communicating agent A:
EO / PO random copolymer Nominal average functional group number = 4
Number average molecular weight = 8,000
Communicating agent B:
EO / PO random copolymer Nominal average functional group number = 3
Number average molecular weight = 3,400

(Synthesis of polyisocyanate liquid)
Example 1
A reactor equipped with a stirrer, a cooling pipe, a nitrogen introduction pipe, and a thermometer was purged with nitrogen, and then a predetermined amount of isocyanate and polyol were charged with the composition shown in Table 1, and reacted at 80 ° C. for 4 hours with stirring. -1 was obtained. The isocyanate content of NCO-1 was 28.8%.

Examples 2-3 and Comparative Examples 1-6
NCO-2 to 8 were obtained in the same manner as in Example 1 with the formulation shown in Table 1. As NCO-9, polymeric MDI-1 was directly used as NCO-9.

Storage stability: Evaluated by appearance after storage at 0 ° C for 3 days
○ → Clear
× → Turbidity, precipitation, precipitation, etc. occur

  The low temperature storage stability of NCO-1 to 7 was good. On the other hand, since the low-temperature storage stability of NCO-8 and 9 was poor, the subsequent evaluation was not performed.

(Preparation of polyol liquid)
Formulation Examples 1-4
OH-1 to 4 were prepared with the formulation shown in Table 2.

Examples 4-10, Comparative Examples 6-10
According to the formulation of Tables 3 and 4, a flexible polyurethane slab foam was produced in the following manner using a multi-component low-pressure foaming machine manufactured by Cannon Viking. Each component temperature-controlled at a raw material temperature of 25 ± 2 ° C. is stirred and mixed at a predetermined ratio at a rotation speed of 4,500 rpm, continuously injected onto a conveyor having a width of 750 mm, and has a length of 2,000 mm and a height of 700 mm. Slab foam blocks were molded. The obtained polyurethane foam was allowed to stand for a whole day and night after production, and then the foam was cut into 300 mm × 300 mm × 50 mm, and its physical properties were measured. The results are shown in Tables 3 and 4.

In Tables 3 and 4, foam state: evaluation method for the appearance of foam after production, etc. Measurement method for foam physical properties Measurement of foam physical properties was performed based on JIS K6400 (1997). The unit is as follows.

According to the present invention, a polyisocyanate for flexible polyurethane slab foam having good low-temperature storage stability and moldability was obtained. Moreover, the flexible polyurethane slab foam using this polyisocyanate had a stable and uniform cell structure, and had good physical properties such as mechanical strength and compression set. On the other hand, in the case of NCO-4 having an isomer content other than 4, 4'-MDI less than the lower limit, NCO-5 exceeding the upper limit, or NCO-6 in which the nominal average functional group number of the modifier is not 4, foam collapse occurs. No further evaluation was performed. In addition, in NCO-7 having a large amount of modification, poor mixing with the polyol solution occurred.

Claims (3)

Polymeric MDI (I) and polyol (B) shown below are obtained by charging (A) / (B) = 80/20 to 95/5 (mass ratio), and the isocyanate content is 26 to 32. Polyisocyanate for flexible polyurethane slabs, which is in mass%.
Polymeric MDI (I):
Polymeric MDI having a binuclear component content of 50 to 80% by mass and an isomer content other than 4,4'-diphenylmethane diisocyanate in the dinuclear component of 10 to 20% by mass
Polyol (b):
Polyether polyol having a nominal average functional group number of 4 and a number average molecular weight of 5,000 to 10,000 The mixed liquid of polyisocyanate (A) for flexible polyurethane slabs according to claim 1, polyol (B), catalyst (C), water (D) as a foaming agent, and foam stabilizer (E) is continuously provided on a box or a conveyor. A method for producing a flexible polyurethane slab foam, characterized by injecting and reactive foaming. The method for producing a flexible polyurethane slab foam according to claim 2, wherein the catalyst (C) contains an acid blocked product of a tertiary amine.