JP2009185155A - Low rebound flexible polyurethane foam - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a low rebound flexible polyurethane foam wherein generation of finger marks (a handprint generated in demolding of a polyurethane foam or the like) is fully suppressed. <P>SOLUTION: The low rebound flexible polyurethane foam is produced by reacting and foaming 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 65-95 kg/m<SP>3</SP>, and the organic polyisocyanate (A) contains 52.5-62.5 mass% diphenylmethane diisocyanate, 16.5-38.5 mass% polymethylene polyphenylene polyisocyanate, and 9.0-21.0 mass% diphenylmethane diisocyanate carbodiimide modification based on 100 mass% of the organic polyisocyanate (A). <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  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, bedding mattresses, 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 (Patent Document 1) is obtained by reacting a urethane foam composition containing a polyol, an organic polyisocyanate, a catalyst and a foaming agent. , Low resilience polyurethane foams having specific viscoelastic properties are disclosed.

  However, in the low resilience polyurethane foam as described in Patent Document 1, since the reactivity of the polyurethane foam is insufficient, a handprint (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, Nippon Polyurethane Industry Co., Ltd., disclosed in JP-A-6-271644 (Patent Document 2) an organic active hydrogen compound, an organic polyisocyanate, a foaming agent, a catalyst, and optionally a foam stabilizer from a polyurethane foam. A polyisocyanate (A) obtained by urethane-modifying a part of diphenylmethane diisocyanate and / or carbodiimide-modified diphenylmethane diisocyanate and a part of polymethylene polyphenylene polyisocyanate as organic polyisocyanate used in the method are disclosed. Is disclosed as a mixture with urethane-modified polyisocyanate (B). However, the polyurethane foam disclosed in Patent Document 2 is used for automobile interior parts and the like, as is clear from the density of those produced in the examples being 0.68 to 0.71 g / cm ^3. It has general resilience. As polyurethane foam having general resilience, there are those having a wide variety of compositions, and among these many polyurethane foams, the polyurethane foam described in Patent Document 2 is a low resilience polyurethane foam. The fact that it can be diverted or used for development could never be recalled even by those skilled in the art.
JP-A-11-286666 JP-A-6-271644

  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.

That is, 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). A 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, in the low resilience flexible polyurethane foam of the present invention, the resilience elastic modulus is preferably 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 with reference to 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 mass% (preferably 22 to 33 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 bodies), 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 contained in Millionate (registered trademark) MTL-S manufactured by Nippon Polyurethane Industry Co., Ltd.

  Moreover, it is preferable that the isocyanate group content (NCO content) in such organic polyisocyanate (A) is 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 polyol (B) concerning this invention, the well-known polyol used for preparation of a flexible polyurethane foam can be used, For example, polyether polyol, polyester polyol, polyether polyamine, polybutadiene polyol is mentioned. 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.

  Further, 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 It is preferable to use those having a number average molecular weight in the range of 2500 (more preferably in the range of 1500 to 2000). 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 and polyethers having a molecular weight in the range of 50 to 500 are usable. 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, such as ethanolamine (amino group). These chain extenders (C) can be used alone or in combination of two or more. Moreover, it is preferable that it is the range of 1-5 mass parts with respect to 100 mass parts of said polyols (B) as addition amount of such a chain extension agent (C).

  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 acids thereof Imidazole compounds such as 1-methylimidazole, 2-methylimidazole, 1,2-dimethylimidazole, 2,4-dimethylimidazole, 1-butyl-2-methylimidazole, stannous octoate, dibutyltin dilaurate, zinc naphthenate Organometallic compounds such as 2,4,6-tris (dimethylaminomethyl) phenol, 2,4,6-tris (dialkylaminoalkyl) hexahydro-S-triazine, potassium acetate, potassium 2-ethylhexanoate, etc. A quantification catalyst is mentioned. These catalysts (D) can be used individually by 1 type or in combination of 2 or more types. Moreover, as an addition amount of such a catalyst (D), it is preferable that it is the range of 1-3 mass parts with respect to 100 mass parts of said polyols (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. Moreover, as an addition amount of such a foaming agent (E), it is preferable that it is the range of 1-5 mass parts with respect to 100 mass parts of said polyols (B). In addition, when using water as a foaming agent (E), it is preferable that it is the range of 1-4 mass parts with respect to 100 mass parts of said polyols (B) as addition amount of water, 1.5-3 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 when the mixed solution is subjected to reaction foaming in this way. Conditions are preferably employed. In the low resilience flexible polyurethane foam of the present invention obtained by reactive foaming in this way, 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. Moreover, it is preferable that the resilience elastic modulus of such a low resilience flexible polyurethane foam of the present invention is in the range of 10 to 25% (more preferably in the range of 15 to 20%). The density and rebound resilience of the polyurethane foam can be measured according to the method described in JIS K6400 (1997).

  EXAMPLES Hereinafter, although this invention is demonstrated more concretely based on an Example and a comparative example, this invention is not limited to a following example. 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 is 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 and 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 1-6 and Comparative Examples 1-4)
<Production of flexible polyurethane foam>
In Example 1, a flexible polyurethane foam was obtained as follows. That is, after a reactor equipped with a stirrer, a cooling tube, a nitrogen introducing tube, and a thermometer was purged with nitrogen, 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 said organic polyisocyanate and the said polyol premix were temperature-controlled at 22-24 degreeC, they were mixed in the ratio used as NCO index 70, and it mixed, stirring for 7 seconds at 3000 rpm. 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 reactive foaming (curing) for 5 minutes, and then demolded to form flexible polyurethane. Got a form.

  Moreover, in Examples 2-5, the flexible polyurethane foam was obtained like Example 1 except having changed the composition of organic polyisocyanate and a polyol premix as shown in Table 1, respectively. 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. Furthermore, 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 liquid was subjected to reaction foaming to obtain a flexible polyurethane foam. I couldn't.

<Evaluation of moldability of flexible polyurethane foam>
About Examples 1-6 and Comparative Examples 1-4, 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 (each content ratio of pure MDI, polymeric MDI and MDI carbodiimide modified product (unit: mass%)), NCO content, and nominal polyol Table 3 shows the average number of functional groups and the number average molecular weight.
A: Formability was good.
○: There was a tendency that the foam was somewhat strong during molding (the ratio of the closed foam was large).
(Triangle | delta): The foam was strong at the time of shaping | molding, and crushing was required in order to prevent shrinkage.
X: The foam collapsed during molding.

<Measurement of physical properties of flexible polyurethane foam and evaluation of finger marks>
About the flexible polyurethane foam obtained in Examples 1-6 and the comparative example 4, the physical property of the flexible polyurethane foam was measured with the following method, and also the presence or absence of the finger mark 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. In other words, the sample is a flexible polyurethane foam that has passed 5 minutes after production, and “x” indicates that 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 visual observation. The case where the presence of the finger mark was not confirmed was determined as “◯”.

  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 a low resilience within a range of 17 to 20 while having a rebound resilience. 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 to 21.0 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 according to claim 1.   The low resilience flexible polyurethane foam according to claim 1 or 2, wherein the resilience elastic modulus is in the range of 10 to 25%.