JP2583155B2 - Method for producing flexible polyurethane foam - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for producing a flexible polyurethane foam. More specifically, in the production of flexible polyurethane foams used in extremely large amounts for cushioning materials, sealing materials, etc. for automobile-related and furniture-related products, the use of a specific organic polyisocyanate compound reduces the density and reduces elasticity. The present invention relates to a method for water-foaming a flexible polyurethane foam which is rich in elongation, has good elongation properties and is excellent in moldability.

[Conventional technology]

Conventionally, as a polyisocyanate component when producing a flexible polyurethane foam, tolylene diisocyanate alone is generally a mixture of tolylene diisocyanate and / or its isocyanate group-terminated prepolymer and polyphenylmethane polyisocyanate.

However, tolylene diisocyanates have a problem from the viewpoint of health and hygiene due to the high vapor pressure, and also have difficulty in curing properties during foam production. It is also said that the foam has a large permanent compression set particularly when wet and hot, and is not suitable for a portion such as a seat cushion.

For this reason, diphenylmethane diisocyanates have recently been applied alone to the production of flexible polyurethane foams.

In a flexible polyurethane foam, water and a chlorofluorocarbon as a carbon dioxide generator are usually used together as an auxiliary foaming agent for reinforcing the foaming action of water. However, with increasing worldwide criticism of the use of chlorofluorocarbons, studies have been made to obtain flexible polyurethane foams using water as the substantially sole blowing agent.
Using diphenylmethane diisocyanate alone,
A disadvantage of obtaining a flexible polyurethane foam is that it is difficult to produce a low-density foam unless an auxiliary foaming agent is used other than water. It is hard to get.

[Problems to be solved by the invention]

The present inventors, when obtaining a flexible polyurethane foam using water as substantially the only foaming agent, without deteriorating the properties of the foam, as a result of intensive studies on a method for obtaining a low-density foam, as an organic polyisocyanate compound It has been found that an excellent effect can be obtained by employing a mixture of an isocyanate group-terminated prepolymer obtained from the reaction of a specific polyester polyol and tolylene diisocyanate with diphenylmethane diisocyanate. The inventors have found that a sufficient effect can be obtained with a mixed amount of tolylene diisocyanate prepolymer that can minimize the disadvantages of the isocyanate, and have completed the present invention.

[Means for solving the problem]

That is, in the present invention, when a flexible polyurethane foam is obtained from the reaction of a mixture of an active hydrogen compound, a foaming agent and an additive with an organic polyisocyanate compound, water is used as a foaming agent; Isocyanate-terminated prepolymers having an NCO content in the range of 10 to 45% by weight obtained from the reaction of a polyester polyol having an average molecular weight in the range of 500 to 10,000 and tolylene diisocyanate. (2) 2,2'- and 2,2 Diphenylmethane diisocyanate containing the 4'-isomer mixture in the range of 5 to 60% by weight or isocyanate group terminals obtained by reacting the diphenylmethane diisocyanate with a polyoxyalkylene polyol having an average molecular weight in the range of 500 to 30,000. Prepolymer (3) A mixture of 2,2'- and 2,4'-isomer A polyphenylmethane polyisocyanate containing 25 to 65% by weight of diphenylmethane diisocyanate contained in a range of 25% by weight is used, and the mixing ratio of (1), (2) and (3) is 1/10. 89-20 / 70
/ 10 (weight ratio) within the range of a flexible polyurethane foam.

The flexible polyurethane foam obtained by the present invention has features such as being rich in elasticity, excellent in elongation properties and moldability, and capable of being adjusted to a low density even when no auxiliary foaming agent is used.

The polyester polyol constituting the isocyanate group-terminated prepolymer of tolylene diisocyanate (1) used in the present invention is, for example, ethylene glycol,
Diethylene glycol, triethylene glycol, 1,2
-Propylene glycol, trimethylene glycol, 1,
3-butylene glycol, tetramethylene glycol,
Hexamethylene glycol, decamethylene glycol,
One or more compounds having at least two or more hydroxyl groups such as glycerin, trimethylolpropane, pentaerythritol, sorbitol and the like, and malonic acid, maleic acid, succinic acid, adipic acid, tartaric acid, pimelic acid, sebacin It can be produced by a known method using one or more compounds having at least two carboxyl groups such as acid, oxalic acid, phthalic acid, terephthalic acid, azelaic acid, trimellitic acid and the like. . Further, lactone-based polyesters obtained by ring-opening polymerization of a monomer having a lactone ring represented by ε-caprolactone and ε-valerolactone are also included.

The average molecular weight of the polyester polyol used in the present invention is in the range of 500 to 10,000, preferably 1,000 to 5,000. The NCO content of the isocyanate group-terminated prepolymer obtained from the reaction between such a polyester polyol and tolylene diisocyanate is 10 to 45% by weight, preferably 15 to 40% by weight.

Examples of the polyether polyol constituting the isocyanate group-terminated prepolymer from the active hydrogen compound used in the present invention and the diphenylmethane diisocyanate according to the above item (2) include ethylene glycol, diethylene glycol, triethylene glycol, and 1,2-propylene glycol. Compounds having at least two active hydrogen atoms, such as trimethylethylene glycol, 1,3-butylene glycol, tetramethylene glycol, hexamethylene glycol, glycerol, sorbitol, sucrose, trimellitic acid, bisphenol A, ethylenediamine, etc. One or more monomers such as ethylene oxide, propylene oxide, butylene oxide, styrene oxide, epichlorohydrin and the like as initiators The is prepared by addition polymerization by a known method. In addition to polyether polyols, it is also possible to use a combination of polyols having at least two or more hydroxyl groups in one molecule, such as polyester polyols and epoxy polyols.

Their average molecular weight is between 500 and 30,000, preferably 1,000.
Within the range of ~ 25,000.

2,2 'as diphenylmethane diisocyanate
-And 2,4'-isomer mixtures in the range of 5 to 60% by weight, preferably 10 to 50% by weight.

The prepolymer obtained from such a polyether polyol and diphenylmethane diisocyanate is NCO
The content is 15 to 32% by weight, preferably 20 to 30% by weight.

Further, as the component (2), those which are not modified with the polyol of the diphenylmethane diisocyanate can also be used.

The polyphenylmethane polyisocyanate (3) used in the present invention comprises a mixture of 2,2'- and 2,4'-isomers.
The diphenylmethane diisocyanate, which is contained in the range of 0.5 to 20% by weight, preferably 1 to 15% by weight, is contained in the range of 25 to 65% by weight, preferably 30 to 60% by weight. By blending a mixture in which the mixing ratio of (1) to (3) is in the range of 1/10/89 to 20/70/10 (weight ratio), reaction foaming is performed.

As a foaming agent in the production of a flexible polyurethane foam, generally, water as a carbon dioxide gas generator, chlorofluorocarbons, and low-boiling solvents are commonly used in combination as an auxiliary foaming agent for reinforcing the foaming action of water. However, since criticism regarding the use of chlorofluorocarbons is increasing worldwide due to the problem of depletion of the ozone layer, water is used in the present invention as substantially the only blowing agent. The amount of water used is 2 to 10 parts by weight, preferably 3.0 to 8.0 parts by weight, based on 100 parts by weight of the active hydrogen compound.

Examples of the additives include a catalyst, a foam stabilizer, and, if necessary, a flame retardant, a viscosity modifier, and a pigment.

Examples of the catalyst include tertiary amines such as dimethylethanolamine, triethylenediamine, tetramethylpropanediamine, tetramethylhexamethylenediamine, and dimethylcyclohexylamine, and organic tin compounds such as stannasoctoate and dibutyltin dilaurate.

Examples of the foam stabilizer include various siloxane / polyalkylene oxide block copolymers, and the selection of the type is determined by the formulation.

As flame retardants, trischloroethyl phosphate,
Trischloropropyl phosphate, trickledyl phosphate, dimethylmethylphosphonate, chlorinated paraffin and the like can be mentioned.

Examples of the viscosity modifier include dibutyl phthalate, dioctyl phthalate, and alkylene carbonates.

A disadvantage that tends to occur in a system using water alone as a foaming agent in obtaining a flexible polyurethane foam is that an isocyanate group terminal obtained from a reaction between a polyester polyol selected as one component of an organic polyisocyanate compound and tolylene diisocyanate. What has been solved by employing the prepolymer is extremely significant.

〔The invention's effect〕

In the production of the flexible polyurethane foam of the present invention, a problem that tends to occur in a system using diphenylmethane diisocyanate alone as an organic polyisocyanate compound and water alone as a foaming agent, that is, difficulty in lowering the density The reduction in rebound resilience, tear properties, elongation properties, etc. can be solved by employing, as a component of the organic polyisocyanate compound, an isocyanate group-terminated prepolymer obtained from a reaction between a selected polyester polyol and tolylene diisocyanate. It became possible.

In a water foaming system, an increase in the amount of water added to reduce the density results in an increase in the amount of catalyst added, which not only increases the reactivity, but also disrupts the foaming balance, and consequently reduces the physical properties of the foam. This makes it difficult to lower the density.

In the present invention, the organic polyisocyanate compound 1
It is thought that the tolylene diisocyanate-based isocyanate group-terminated prepolymer employed as a component will effectively work to maintain the balance between foaming and resinification and mild reactivity even in systems with increased water addition. As a result, it has become possible to improve the physical properties and lower the density of the foam.

〔Example〕

Hereinafter, examples of the present invention will be described in detail, but the present invention is not limited to these examples. Unless otherwise specified, parts and% in the examples indicate "parts by weight" and "% by weight", respectively.

Preparation 1. Preparation of Organic Polyisocyanate Compound (A) 1,000 parts of tolylene diisocyanate (Coronate T-80, manufactured by Nippon Polyurethane Industry) and polyester polyol (Nipporan 168, manufactured by Nippon Polyurethane Industry, average molecular weight 2,500) and 545 parts were reacted at 80 ° C. for 3 hours to obtain an isocyanate group-terminated prepolymer (a) of tolylene diisocyanate. The NCO content was 29.8%. To 50 parts of this prepolymer was added a mixture of 2,2'- and 2,4'-isomers 30.3.
% Of diphenylmethane diisocyanate, containing 10.8% of the 2,2'- and 2,4'-isomer mixture.
47.0% diphenylmethane diisocyanate
% Polyphenylmethane polyisocyanate (Coronate 1104, manufactured by Nippon Polyurethane Industry, NCO content 30.7
%) And stirred for 1 hour to obtain an organic polyisocyanate compound (A) to be subjected to a foaming test. The NCO content of the obtained compound was 32.2%.

Preparation 2. Preparation of organic polyisocyanate compound (B) 498 parts of diphenylmethane diisocyanate containing 29.8% of a 2,2'- and 2,4'-isomer mixture and polyether polyol (average number of functional groups (hereinafter referred to as Abbreviated) 2, 139 parts, polyether polyol The mixture was reacted with 31 parts of the mixture at 80 ° C. for 3 hours to obtain an isocyanate group-terminated prepolymer (b) of diphenylmethane diisocyanate. The NCO content was 24.1%. The prepolymer (a) 82 obtained in Preparation 1 was added to this prepolymer (b).
And then 250 parts of Coronate 1104 were added and stirred for 1 hour to obtain an organic polyisocyanate compound (B) to be subjected to a foaming test. The NCO content of the obtained compound is 26.
2%.

Preparation 3. Preparation of Organic Polyisocyanate Compound (C) 1,000 parts of Coronate T80 and polyester polyol (Nipporan 155, manufactured by Nippon Polyurethane Industry, This was reacted with 511 parts at 80 ° C for 3 hours to obtain an isocyanate group-terminated prepolymer (c) of tolylene diisocyanate. The NCO content was 30.1%. 18.5% of a mixture of 2,2'- and 2,4'-isomers was added to 105 parts of the prepolymer (c).
And 580 parts of diphenylmethane diisocyanate containing 9.4% of the 2,2'- and 2,4'-isomer mixture
Polyphenylmethane polyisocyanate containing 40% of diphenylmethane diisocyanate (MF-24)
315 parts (MR, NCO content 31.0%, manufactured by Nippon Polyurethane Industry Co., Ltd.) was added and stirred for 1 hour to obtain an organic polyisocyanate compound (C) to be subjected to a foaming test. NCO of the obtained compound
The content was 32.2%.

Preparation 4. Preparation of organic polyisocyanate compound (D) 1,000 parts of Coronate T80 and polyester polyol (Nipporan 164, manufactured by Nippon Polyurethane Industry, 532 parts were reacted at 80 ° C. for 3 hours to obtain an isocyanate group-terminated prepolymer (d) of tolylene diisocyanate. The NCO content was 30.0%. To 100 parts of this prepolymer (d), 600 parts of the diphenylmethane diisocyanate used in Preparation 1 was added, and then 300 parts of C-1104 were added, and the mixture was stirred for 1 hour to give an organic polyisocyanate compound (D) to be subjected to a foaming test. Obtained. NCO of the obtained compound
The content was 32.2%.

Preparation 5. Preparation of organic polyisocyanate compound (E) C-110 was added to 668 parts of the prepolymer (b) used in Preparation 2.
4 332 parts were added and stirred for 1 hour to obtain an organic polyisocyanate compound (E) to be subjected to a foaming test of a comparative example.
The NCO content of the obtained compound was 26.6%.

Preparation 6. Preparation of organic polyisocyanate compound (F) Triol 369 having a molecular weight of 700 obtained by addition polymerization of propylene oxide to 1000 parts of coronate T80 and glycerin
Were reacted at 80 ° C. for 3 hours to obtain an isocyanate group-terminated prepolymer (f) of tolylene diisocyanate.
The NCO content was 30.0%. This prepolymer (f) 100
To this part, 600 parts of the diphenylmethane diisocyanate used in Preparation 1 was added, and then 300 parts of C-1104 were added and stirred for 1 hour to obtain an organic polyisocyanate compound (F) to be subjected to a foaming test. NCO content of the obtained compound is 32.2%
Met.

Preparation 7. Preparation of polyol premix The formulation of the polyol premix subjected to the foaming test is shown below. Table 1 shows the organic polyisocyanate compounds and isocyanate indexes used in Examples 1 to 4 and Comparative Examples 1 and 2.

A molded foam was prepared under the following conditions, and the physical properties of the foam were measured.

Mold: 300 × 300 × 100 ^mm made of aluminum Mold temperature: 50 ± 3 ° C. Demolding time: 4 minutes The physical properties of foams of Examples 1 to 4 and Comparative Examples 1 and 2 are shown in Table 1.

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Claims (1)

(57) [Claims] 1. A method for producing a flexible polyurethane foam from a reaction of a mixture of an active hydrogen compound, a foaming agent and an additive with an organic polyisocyanate compound, wherein water is used as a foaming agent; Isocyanate-terminated prepolymers having an NCO content in the range of 10 to 45% by weight obtained from the reaction of a polyester polyol having an average molecular weight in the range of 500 to 10,000 and tolylene diisocyanate. (2) 2,2'- and 2,2 Diphenylmethane diisocyanate containing a 4'-isomer mixture in the range of 5 to 60% by weight or an isocyanate group terminal obtained by reacting the diphenylmethane diisocyanate with a polyether or polyol having an average molecular weight in the range of 500 to 30,000. Prepolymer (3) 0.5 to 20% by weight of a mixture of 2,2'- and 2,4'-isomers Polyphenylmethane polyisocyanate containing 25 to 65% by weight of diphenylmethane diisocyanate contained in the range is used, and the mixing ratio of (1), (2) and (3) is 1/10/89 to 20 / 70
10. A method for producing a flexible polyurethane foam, which is within the range of / 10 (weight ratio).