WO2009098966A1 - Low-resilience flexible polyurethane foam - Google Patents

Abstract

Disclosed is a low-resilience flexible polyurethane foam which is composed of a flexible polyurethane foam obtained by reacting and foaming a mixed liquid containing (A) an organic polyisocyanate, (B) a polyol, (C) a chain extender, (D) a catalyst and (E) a foaming agent. The flexible polyurethane foam has a density within the range of 65-95 kg/m3, and the organic polyisocyanate (A) contains, per 100% by mass of the organic polyisocyanate (A), 52.5-62.5% by mass of diphenylmethane diisocyanate, 16.5-38.5% by mass of polymethylene polyphenylene polyisocyanate, and 9.0-21.0% by mass of carbodiimide-modified diphenylmethane diisocyanate.

Description

Low resilience flexible polyurethane foam

The present invention relates to a low-resilience flexible polyurethane foam, and more particularly to a low-resilience flexible polyurethane foam that can be suitably used for chair cushion materials, pillows, mattresses for bedding, and the like.

Polyurethane foam is used in a wide range of applications such as furniture and cushioning materials for automobile seats, industrial sealing materials, etc., but in recent years, polyurethane foam having a high level of low resilience that has not been required in the past ( (Hereinafter referred to as “low-resilience polyurethane foam”), and the technology of using low-resilience polyurethane foam for chair cushioning materials, pillows, bedding mattresses, and the like has attracted attention. As such a low resilience polyurethane foam, for example, JP-A-11-286666 (Document 1) can be obtained by reacting a urethane foam composition containing a polyol, an organic polyisocyanate, a catalyst and a foaming agent. A low resilience polyurethane foam having specific viscoelastic properties is disclosed.

However, in the low resilience polyurethane foam as described in Document 1, since the reactivity of the polyurethane foam is insufficient, a handprint or the like (so-called finger mark) is generated when the polyurethane foam is removed. There was a problem. In addition, in such a low resilience polyurethane foam, there is also a problem that tolylene diisocyanate designated as a specific chemical substance is mainly used because it is highly volatile as a raw material and harmful to the human body.

On the other hand, the applicant, Japan Polyurethane Industry Co., Ltd., disclosed in JP-A-6-271644 (Document 2), a polyurethane foam from an organic active hydrogen compound, an organic polyisocyanate, a foaming agent, a catalyst, and optionally a foam stabilizer. Disclosed is a method for producing, and as an organic polyisocyanate used in the method, polyisocyanate (A) obtained by urethane modification of a part of diphenylmethane diisocyanate and / or carbodiimide-modified diphenylmethane diisocyanate, and a part of polymethylene polyphenylene polyisocyanate. A mixture with urethane-modified polyisocyanate (B) is disclosed. However, the polyurethane foam disclosed in Document 2 is generally used for interior parts of automobiles, as is clear from the density of those produced in the examples being 0.68 to 0.71 g / cm ^3. It has a typical resilience. Polyurethane foams having a wide variety of compositions exist as polyurethane foams having general resilience, and among these many polyurethane foams, the polyurethane foam described in Document 2 is a development of a low resilience polyurethane foam. It could never be recalled by those skilled in the art that it can be diverted or used.

The present invention has been made in view of the above-described problems of the prior art, and provides a low-resilience flexible polyurethane foam in which the occurrence of finger marks (handprints generated when the polyurethane foam is removed) is sufficiently suppressed. For the purpose.

As a result of intensive studies to achieve the above object, the present inventors contain an organic polyisocyanate (A), a polyol (B), a chain extender (C), a catalyst (D) and a foaming agent (E). In the case of obtaining a low-repulsive flexible polyurethane foam by reaction foaming of the mixed liquid, the organic polyisocyanate (A) having a specific composition is used, and the density of the obtained flexible polyurethane foam is set within a specific range. The inventors have found that a low-resilience flexible polyurethane foam capable of achieving the above object is obtained, and have completed the present invention.

The low resilience flexible polyurethane foam of the present invention is obtained by reactive foaming of a mixed solution containing an organic polyisocyanate (A), a polyol (B), a chain extender (C), a catalyst (D) and a foaming agent (E). Flexible polyurethane foam,
The density of the flexible polyurethane foam is in the range of 65 to 95 kg / m ³ , and
The organic polyisocyanate (A) is 52.5 to 62.5% by mass of diphenylmethane diisocyanate and 16.5 to 38.5% by mass of polymethylene polyphenylene with respect to 100% by mass of the organic polyisocyanate (A). It contains polyisocyanate and 9.0 to 21.0% by mass of a modified diphenylmethane diisocyanate carbodiimide.

In the low resilience flexible polyurethane foam of the present invention, the polyol (B) has a nominal average functional group number in the range of 1 to 2.3 and a number average molecular weight in the range of 1000 to 2500. It is preferable that it has.

Furthermore, the low resilience flexible polyurethane foam of the present invention preferably has a resilience modulus in the range of 10 to 25%.

According to the present invention, it is possible to provide a low-resilience flexible polyurethane foam in which the generation of finger marks is sufficiently suppressed. Further, when the low resilience flexible polyurethane foam of the present invention is produced, tolylene diisocyanate designated as a specific chemical substance is not used because it is highly volatile and harmful to the human body.

Hereinafter, the present invention will be described in detail on the basis of preferred embodiments thereof.

The low resilience flexible polyurethane foam of the present invention is obtained by reactive foaming of a mixed solution containing an organic polyisocyanate (A), a polyol (B), a chain extender (C), a catalyst (D) and a foaming agent (E). Flexible polyurethane foam,
The density of the flexible polyurethane foam is in the range of 65 to 95 kg / m ³ , and
The organic polyisocyanate (A) is 52.5 to 62.5% by mass of diphenylmethane diisocyanate and 16.5 to 38.5% by mass of polymethylene polyphenylene with respect to 100% by mass of the organic polyisocyanate (A). It contains polyisocyanate and 9.0 to 21.0% by mass of a modified diphenylmethane diisocyanate carbodiimide.

The organic polyisocyanate (A) according to the present invention is 52.5 to 62.5% by mass (preferably 55 to 60% by mass) of diphenylmethane diisocyanate with respect to 100% by mass of such organic polyisocyanate (A). (Hereinafter sometimes referred to as “pure MDI”), 16.5 to 38.5% by mass (preferably 22 to 33% by mass) of polymethylene polyphenylene polyisocyanate (hereinafter sometimes referred to as “polymeric MDI”), 9.0 to 21.0% by mass (preferably 12 to 18% by mass) of a modified diphenylmethane diisocyanate carbodiimide (hereinafter sometimes referred to as “MDI carbodiimide modified product”). When the content ratio of pure MDI in such organic polyisocyanate (A) is less than 52.5% by mass, the ratio of closed cells (single bubbles) tends to increase when the mixture is subjected to reaction foaming, and shrinkage tends to occur. On the other hand, if it exceeds 62.5% by mass, the foam tends to be depressed when polyurethane foam is obtained by reactive foaming of the mixed solution. In addition, when the content ratio of polymeric MDI in such organic polyisocyanate (A) is less than 16.5% by mass, foam depression tends to occur when polyurethane foam is obtained by reaction foaming of the mixture, If it exceeds 38.5% by mass, the proportion of soot bubbles tends to increase when the mixed solution is subjected to reaction foaming, and shrinkage tends to occur. Furthermore, when the content ratio of the MDI carbodiimide modified product in the organic polyisocyanate (A) is less than 9.0% by mass, the ratio of the closed cells tends to increase when the mixed solution is subjected to reaction foaming, and shrinkage is likely to occur. On the other hand, if it exceeds 38.5% by mass, the foam tends to be depressed when a polyurethane foam is obtained by reactive foaming of the mixed solution.

In the present specification, pure MDI refers to pure diphenylmethane diisocyanate (not including polynuclear substances), and is available, for example, as Millionate (registered trademark) MT manufactured by Nippon Polyurethane Industry Co., Ltd. . Polymeric MDI refers to polymethylene polyphenylene polyisocyanate composed of a polynuclear body having three or more benzene rings, and is included in, for example, Millionate (registered trademark) MR-100 manufactured by Nippon Polyurethane Industry Co., Ltd. It is what. Further, the MDI carbodiimide modified product refers to a product obtained by modifying diphenylmethane diisocyanate with a carbodiimidization catalyst. In addition to a carbodiimide group, an isocyanate group is added to a carbodiimide group to reach a urethane imine structure. include. For example, it is included in Millionate (registered trademark) MTL-S manufactured by Nippon Polyurethane Industry Co., Ltd.

Further, the isocyanate group content (NCO content) in such organic polyisocyanate (A) is preferably in the range of 27 to 32% by mass. When the NCO content is less than the lower limit, the expansion ratio is lowered, and the polyurethane foam cannot be satisfactorily filled in the mold, and it tends to be difficult to reduce the density.

As the polyol (B) according to the present invention, known polyols used for producing flexible polyurethane foams can be used, and examples thereof include polyether polyol, polyester polyol, polyether polyamine, and polybutadiene polyol. These polyols can be used individually by 1 type or in combination of 2 or more types. Examples of polyether polyols include active hydrogen atoms such as ethylene glycol, diethylene glycol, triethylene glycol, trimethylolpropane, glycerin, sorbitol, sucrose, bisphenol A, water, ethylenediamine, tolylenediamine, and diphenylmethanediamine. Examples include those produced by addition polymerization by a known method using at least one compound having at least two compounds as an initiator and at least one monomer such as ethylene oxide, propylene oxide, butylene oxide, epichlorohydrin and the like.

Examples of the polyester polyol include ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propylene glycol, trimethylene glycol, 1,3- or 1,4-butanediol, 1,6-hexanediol, and decamethylene. At least one compound having two or more hydroxyl groups such as glycol, glycerin, trimethylolpropane, pentaerythrol, sorbitol, and the like, adipic acid, succinic acid, malonic acid, maleic acid, tartaric acid, sebacic acid, phthalic acid, Examples include those prepared by a known method using at least one compound having two or more carboxyl groups such as terephthalic acid, isophthalic acid, trimellitic acid and the like. Further, it may be a polyester polyol obtained by ring-opening polymerization of caprolactone.

Furthermore, examples of the polyether polyamine include those produced by amination of a hydroxyl group-terminated polyol obtained by addition polymerization of a lower alkylene oxide such as ethylene oxide, propylene oxide, butylene oxide or a mixture thereof. More specifically, examples of such polyether polyamines include Texaco Chemical's Jeffamine and polyoxyalkyleneamine.

Such a polyol (B) has a nominal average functional group number in the range of 1 to 2.3 (more preferably in the range of 1.9 to 2.3), and 1000 to Those having a number average molecular weight in the range of 2500 (more preferably in the range of 1500 to 2000) are preferably used. If the nominal average functional group number is less than the lower limit, unreacted products with isocyanate tend to be generated. On the other hand, if the upper limit is exceeded, the ratio of closed cells (single bubbles) is increased when the mixed solution is reacted and foamed. It tends to increase and shrink tends to occur. Further, if the number average molecular weight is less than the lower limit, the resulting polyurethane foam tends to be hard, and thus it tends to be difficult to obtain a low-resilience polyurethane foam. On the other hand, if the upper limit is exceeded, the mixture is reacted. When foaming to obtain a low resilience flexible polyurethane foam, the foam tends to be depressed. The amount of such polyol (B) is preferably such that the isocyanate index (NCO index) falls within the range described below.

As the chain extender (C) according to the present invention, known chain extenders used for the production of flexible polyurethane foams can be used. For example, diols, polyols, polyethers having a molecular weight in the range of 50 to 500 can be used. More specifically, ethylene glycol, propanediol, butanediol, pentanediol diethylene glycol, dipropylene glycol, 2,2-bis (4-hydroxyphenyl) propane, 1,4-cyclohexanedimethanol, etc. Low molecular diols; low molecular trifunctional or higher functional polyols such as glycerin, trimethylolpropane and pentaerythritol; hydroxyl group-terminated polyethers obtained by addition polymerization of alkylene oxide using an active hydrogen compound as an initiator; Triethanolamine Polyols small molecules containing nitrogen atoms (the amino group), such as diethanolamine. These chain extenders (C) can be used alone or in combination of two or more. The amount of the chain extender (C) added is preferably in the range of 1 to 5 parts by mass with respect to 100 parts by mass of the polyol (B).

Examples of the catalyst (D) according to the present invention include various known urethanization catalysts and trimerization catalysts used for the production of flexible polyurethane foams. More specifically, triethylamine, tripropylamine, tributylamine, N— Methylmorpholine, N-ethylmorpholine, dimethylbenzylamine, N, N, N ′, N′-tetramethylhexamethylenediamine, N, N, N ′, N ′, N ″ -pentamethyldiethylenetriamine, triethylenediamine, bis Tertiary amines such as-(2-dimethylaminoethyl) ether, 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 compounds thereof Salts; imidazole compounds such as 1-methiimidazole, 2-methylimidazole, 1,2-dimethylimidazole, 2,4-dimethylimidazole, 1-butyl-2-methylimidazole; stanas octoate, dibutyltin dilaurate, naphthenic acid Organometallic compounds such as zinc; 2,4,6-tris (dimethylaminomethyl) phenol, 2,4,6-tris (dialkylaminoalkyl) hexahydro-S-triazine, potassium acetate, potassium 2-ethylhexanoate, etc. A trimerization catalyst is mentioned. These catalysts (D) can be used individually by 1 type or in combination of 2 or more types. The amount of such catalyst (D) added is preferably in the range of 1 to 3 parts by mass with respect to 100 parts by mass of the polyol (B).

As the foaming agent (E) according to the present invention, a known foaming agent used for producing a flexible polyurethane foam can be used. For example, a reactive foaming agent such as water; acetone, methylene chloride, hydrofluorocarbon (for example, And inert low-boiling solvents such as HFC-141B). Among these foaming agents (E), water is preferable from the viewpoint of little influence on the global environment. These foaming agents (E) can be used individually by 1 type or in combination of 2 or more types. The amount of the foaming agent (E) added is preferably in the range of 1 to 5 parts by mass with respect to 100 parts by mass of the polyol (B). When water is used as the foaming agent (E), the amount of water added is preferably in the range of 1 to 4 parts by mass with respect to 100 parts by mass of the polyol (B), and 1.5 to 3 More preferably, it is in the range of parts by mass. If the amount of water added is less than the lower limit, it is difficult to reduce the density of the resulting polyurethane foam, and it tends to be difficult to obtain a low-resilience polyurethane foam. Foam tends to be hard and low resilience polyurethane foam tends to be difficult to obtain.

The mixed liquid for producing the low resilience flexible polyurethane foam of the present invention contains the above-mentioned organic polyisocyanate (A), polyol (B), chain extender (C), catalyst (D) and foaming agent (E). To do. In addition, such a mixed liquid may contain other substances as required, such as foaming agents, antioxidants, ultraviolet absorbers, heat resistance improvers, antifoaming agents, leveling agents, colorants, inorganic and organic fillers. Further, a lubricant, an antistatic agent, and a reinforcing material may be further contained.

In the present invention, the isocyanate index [{(isocyanate group) / (isocyanate reactive group)} × 100 (equivalent ratio)] in such a mixed solution is preferably in the range of 50 to 110, A range of 70 to 90 is more preferable. If the NCO index is less than the lower limit, the surface of the resulting polyurethane foam tends to be sticky, whereas if the upper limit is exceeded, the resulting polyurethane foam tends to be hard, and the low resilience polyurethane. It tends to be difficult to obtain a foam.

The low resilience flexible polyurethane foam of the present invention is obtained by reacting and foaming the mixed solution. The specific method for reacting and foaming the mixed solution is not particularly limited. For example, a method of casting the mixed solution into a mold, reacting and foaming in the mold, and demolding is adopted. Can do. In addition, the temperature of the mold and the reaction time are not particularly limited for the reaction foaming of the mixed solution as described above, but generally the mold temperature is about 40 to 50 and the reaction time is about 1 to 5 minutes. Conditions are preferably employed. In the low resilience flexible polyurethane foam of the present invention obtained by reactive foaming as described above, the density is in the range of 65 to 95 kg / m ³ (preferably in the range of 70 to 80 kg / m ³ ). is required. If the density is less than 65 kg / m ³ , the generation of finger marks cannot be sufficiently prevented when producing polyurethane foam. On the other hand, when the density exceeds 95 kg / m ³ , a polyurethane foam having sufficient low resilience cannot be obtained. Further, the low resilience flexible polyurethane foam of the present invention preferably has a rebound resilience of 10 to 25% (more preferably 15 to 20%). The density and rebound resilience of the polyurethane foam can be measured according to the method described in JIS K6400 (1997).

Hereinafter, the present invention will be described more specifically based on examples and comparative examples, but the present invention is not limited to the following examples. Unless otherwise specified, “part” and “%” in the text are based on mass. Moreover, the raw material used in the Example and the comparative example is as follows.

(Raw materials used)
<Isocyanate>
C-1104: Polymeric MDI content 55%, pure MDI content 45%, 4,4'-MDI content in pure MDI 88%, manufactured by Nippon Polyurethane Industry Co., Ltd.
MR-400: 72% polymeric MDI content, 28% pure MDI content, 100% content of 4,4′-MDI in pure MDI, manufactured by Nippon Polyurethane Industry Co., Ltd.
MT: 100% pure MDI content, 100% content of 4,4′-MDI in pure MDI, manufactured by Nippon Polyurethane Industry Co., Ltd.
MTL-S: MDI carbodiimide modified substance content is 30%, pure MDI content is 70%, 4,4'-MDI content in pure MDI is 100%, manufactured by Nippon Polyurethane Industry Co., Ltd.

<Polyol>
FA-703: Polyoxyethylene polyoxypropylene polyol, nominal average functional group number 3, number average molecular weight 5000, manufactured by Sanyo Chemical Industries.
PP-1000: Polyoxypropylene polyol, nominal average functional group number 2, number average molecular weight 1000, manufactured by Sanyo Chemical Industries.

<Chain extender>
1,4-BD: 1,4-butanediol, manufactured by Mitsubishi Chemical Corporation.

<Catalyst>
TEDA-L33: Triethylenediamine 33% DPG solution, manufactured by Tosoh Corporation
DMEA: N, N-dimethylethanolamine, manufactured by Nippon Emulsifier Co., Ltd., trade name “Amino Alcohol 2 Mabs”.

<Foaming agent>
L3151: Foaming agent, manufactured by Momentive.

(Examples 1 to 6 and Comparative Examples 1 to 4)
<Production of flexible polyurethane foam>
In Example 1, a flexible polyurethane foam was obtained as follows. That is, a reactor equipped with a stirrer, a cooling tube, a nitrogen introducing tube and a thermometer was purged with nitrogen, and then 500 parts of MTL-S and 500 parts of C-1104 were charged and mixed to prepare an organic polyisocyanate. The NCO content in the obtained organic polyisocyanate was 29.8%. Meanwhile, 200 parts of FA-703, 800 parts of P-1000, 30 parts of 1,4-BD, 10 parts of L3151, 12 parts of DMEA, 5 parts of TEDA-L33, and 22 parts of water are charged into a container. After that, a polyol premix was obtained by mixing. Next, the temperature of the organic polyisocyanate and the polyol premix was controlled at 22 to 24 ° C., and they were mixed at a ratio such that the NCO index was 70, and mixed while stirring at 3000 rpm for 7 seconds. Thereafter, the obtained mixed liquid is poured into a mold (length: 300 mm × width: 300 mm × thickness: 100 mm) at 40 to 50 ° C., subjected to reaction foaming (curing) for 5 minutes, and then demolded to form flexible polyurethane. Got a form.

In Examples 2 to 5, flexible polyurethane foams were obtained in the same manner as in Example 1 except that the compositions of the organic polyisocyanate and the polyol premix were changed as shown in Table 1. In Example 6, the composition of the organic polyisocyanate and the polyol premix was changed as shown in Table 1, and the flexible polyurethane foam was the same as Example 1 except that the volume of the mold used was changed. Got. Further, in Comparative Examples 1 to 4, an attempt was made to produce a flexible polyurethane foam in the same manner as in Example 1 except that the compositions of the organic polyisocyanate and the polyol premix were changed as shown in Table 2, respectively. In Comparative Example 4, a flexible polyurethane foam could be produced. However, in Comparative Examples 1 to 3, the foam was depressed when the mixed solution was subjected to reaction foaming to obtain a flexible polyurethane foam. I couldn't.

<Evaluation of moldability of flexible polyurethane foam>
For Examples 1 to 6 and Comparative Examples 1 to 4, the moldability of the flexible polyurethane foam was evaluated based on the following criteria. The obtained results are shown in Table 3. Further, the composition of the organic polyisocyanate in Examples 1 to 6 and Comparative Examples 1 to 4 (content ratios of pure MDI, polymeric MDI and MDI carbodiimide modified products (unit: mass%)), NCO content, and nominal polyol Table 3 shows the average number of functional groups and the number average molecular weight.
A: The moldability was good.
B: There was a tendency for the foam to be slightly stronger during molding (the ratio of solitary foam was large).
C: The foam was strong at the time of molding, and crushing was necessary for the purpose of preventing shrinkage.
D: The foam collapsed during molding.

<Measurement of physical properties of flexible polyurethane foam and evaluation of finger marks>
For the flexible polyurethane foams obtained in Examples 1 to 6 and Comparative Example 4, the physical properties of the flexible polyurethane foam were measured by the following method, and the presence or absence of finger marks was evaluated. Table 4 shows the obtained results.

(I) Method for measuring foam physical properties Various physical properties (foam physical properties) of the obtained flexible polyurethane foam were measured as follows. That is, in accordance with the method described in JIS K6400 (1997), the following physical properties [density (core density), impact resilience, mechanical properties (tensile strength, elongation at break, tear strength), compression set] Was measured.

(Ii) Finger Mark Evaluation Method Finger marks were evaluated by visually observing the surface of the obtained flexible polyurethane foam. That is, when a soft polyurethane foam 5 minutes after manufacture is used as a sample and the presence of finger marks (such as a handprint generated when the polyurethane foam is removed) is confirmed on the surface of the sample by observation with the naked eye, "D" The case where the presence of the finger mark was not confirmed was determined as “A”.

As is clear from the results shown in Table 4, the flexible polyurethane foams (Examples 1 to 6) of the present invention are foams having low resilience with a rebound resilience in the range of 17 to 20, while It was confirmed that the occurrence was sufficiently suppressed.

As described above, according to the present invention, it is possible to provide a low resilience flexible polyurethane foam in which generation of finger marks is sufficiently suppressed.
Therefore, the low resilience flexible polyurethane foam of the present invention can be suitably used for chair cushion materials, pillows, bedding mattresses, and the like.

Claims (3)

A flexible polyurethane foam obtained by reactive foaming of a mixed liquid containing an organic polyisocyanate (A), a polyol (B), a chain extender (C), a catalyst (D) and a foaming agent (E),
The density of the flexible polyurethane foam is in the range of 65 to 95 kg / m ³ , and
The organic polyisocyanate (A) is 52.5 to 62.5% by mass of diphenylmethane diisocyanate and 16.5 to 38.5% by mass of polymethylene polyphenylene with respect to 100% by mass of the organic polyisocyanate (A). A low-resilience flexible polyurethane foam comprising polyisocyanate and 9.0-21.0% by mass of a modified diphenylmethane diisocyanate carbodiimide. The polyol (B) has a nominal average functional group number in the range of 1 to 2.3 and a number average molecular weight in the range of 1000 to 2500. The low-resilience flexible polyurethane foam described. The low resilience flexible polyurethane foam according to claim 1 or 2, wherein the resilience modulus is in the range of 10 to 25%.