JPH10251431A - Production of polyurethane foam - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce a flexible polyurethane foam freed from the necessity for after cure and thereby shortened in an aging time by specifying the relationship concerning a catalyst, a catalyst constant and an isocyanate index, the mixing ratio of the high-molecular and low-molecular polyhydroxy compounds, the amount of TDI used, etc. SOLUTION: The high-molecular polyhydroxy compound used has an average functionality of 2 or above, a rate of primary hydroxyl groups of 50% or above and a hydroxyl value of 20-60mgKOH/g. The low-molecular polyhydroxy compound has an average functionality of 2 or above and a hydroxyl value of 300mgKOH/g or above. The organic polyisocyanate is a mixture of TDI with cr-MDI. Formula I (wherein X is the amount of the catalyst used; k1 and k2 are catalytic constants; I is the isocyanate index; and i is the number of the types of the catalysts used) which represents the relationship between the catalyst and the isocyanate index and formula II concerning the properties (e.g. mixing ratio) of the starting compounds are satisfied.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing a polyurethane foam, and more particularly, to a method for producing a highly elastic polyurethane foam as a cushion material used for furniture and automobile seats.

[0002]

2. Description of the Related Art When a flexible polyurethane foam is used to produce a cushioning material for automobile seats and furniture, it takes at least one day or more to reach the final foam physical properties after demolding. If the sheet is assembled or stacked in a short time after demolding, a permanent compression set is generated, so that the sheet is deformed and cannot be recovered.

[0003] As a method of shortening the aging time until the final foam property value is obtained after the demolding, there is a method called after-curing in which the foam is demolded and then subjected to a heating step again. For example, Japanese Patent Publication No. 58-458 and Japanese Patent Publication No. 2-3
Tolylene diisocyanate (TDI) is not used as an organic polyisocyanate compound such as 1091 etc., and instead diphenylmethane diisocyanate (hereinafter referred to as “p
-MDI "), 4,4'-isomer, 2,4'-isomer, polymethylene polyphenylisocyanate (hereinafter" cr-M
A so-called all-MDI formulation has also been proposed in which the use of "DI") and / or a derivative thereof enhances reactivity and shortens molding time and aging time.

[0004]

The conventional aging without using after-curing or all-MDI prescription requires a long time of one day or more, so that it becomes a critical rate-determining step in the whole production process, resulting in a decrease in production efficiency. In addition, an increase in production requires a large space for aging, which is a major problem.

[0005] Further, in order to perform after-curing, equipment such as an oven used for the after-curing is required, and furthermore, there is a problem with economic efficiency and the like because it involves work.

[0006] Further, in the case of the all-MDI formulation, the flowability of the foam is poor, and the filling property to the tip portion of a complicated shape is poor.
There are problems that the NCO equivalent is large, it is difficult to reduce the density, the rebound resilience is low, and the compression set is large. For this reason, the all-MDI prescription has been applied to small items such as headrests and armrests, but still has technical problems as a lightweight and excellent cushioning material.

Accordingly, an object of the present invention is to produce a lightweight and excellent cushioning material without requiring long-term aging, without after-curing, and without using an all-MDI formula.

[0008]

Means for Solving the Problems The present inventors have found that the deformation of a foam is caused by unreacted isocyanate groups remaining in the foam, and that the hardness of the foam is correlated with the crosslink density, and the present invention has been made. Completed. That is, the present invention
(A) The average number of functional groups is 2 or more, the primary conversion rate of terminal hydroxyl groups is 50% or more, and the hydroxyl value is 20 to 60.
a polymeric polyhydroxy compound that is mgKOH / g;
(B) The average number of functional groups is 2 or more, and the hydroxyl value is 3
A low molecular weight polyhydroxy compound of at least 00 mg KOH / g and (C) an organic polyisocyanate compound containing at least two or more isocyanate groups as a catalyst,
In a method of producing a flexible polyurethane foam by reacting in the presence of a foaming agent, a foam stabilizer, and other auxiliaries,
(C) The organic polyisocyanate compound is TDI and cr-
A mixture with MDI, the mixing ratio of which is 10% by weight.
0: 0 to 50:50, the isocyanate index of which is 60 to 100; (A) the polymer polyhydroxy compound is a polyol containing a polymer polyol as an essential component; Equation 1

(Equation 3) (Where X is the number of catalysts used per 100 parts of the polymer polyhydroxy compound (A), K1 is the catalyst constant per weight of the catalyst in the resination reaction, and K2
Is the catalyst constant per weight of catalyst in the foaming reaction, I is the isocyanate index, and i
Is the number of types of catalyst and is an integer from 1 to n. )
And (A) a high molecular weight polyhydroxy compound, (B) a low molecular weight polyhydroxy compound, (C) an organic polyisocyanate compound, and the isocyanate index are represented by Formula 2

(Equation 4) (Wherein, Y represents the number of parts of (B) the low molecular weight polyhydroxy compound used per 100 parts of the high molecular weight polyhydroxy compound (A), and H represents the hydroxyl value (mg KOH / g) of (B) the low molecular weight polyhydroxy compound. And T is (C)
The weight percentage of TDI in the organic polyisocyanate compound is 50-100, P is the polymer concentration in the (A) polymeric polyhydroxy compound and is not zero, I is the isocyanate index, and m is (B)
This is the number of types of low molecular weight polyhydroxy compounds. ), Which is a method for producing a flexible polyurethane foam.

The reason that the organic polyisocyanate compound is a mixture of TDI and cr-MDI and that the mixing ratio is 100: 0 to 50:50 by weight is a problem of the above-mentioned conventional all-MDI formulation. This is to avoid it. That is, if the amount of TDI in the organic polyisocyanate compound is too small, cr-MDI becomes the main component, and the flowability of the foam deteriorates and the rebound resilience decreases. For this reason, in the present invention, 50% by weight of TDI in the organic polyisocyanate compound is used.
These problems can be solved by setting the content to 100% by weight.

Next, in order to shorten the aging time, the time required to reach the final value should be shortened in addition to the fact that the absolute value of the physical properties of the foam, especially the compression set, is good.
Here, the deformation of the foam when the aging time is insufficient,
It is considered that most of the reaction is caused by the reaction of unreacted isocyanate groups remaining in the foam, and from that point, it is important to eliminate unreacted isocyanate groups in a shorter time.

Since the isocyanate group is consumed by the reaction between the polyhydroxy compound and water, the catalyst constant k1 per weight of the catalyst for the resination reaction between the isocyanate and the polyhydroxy compound and the foaming reaction between the isocyanate and water are reduced. It is considered that the larger the sum (k1 + k2) of the catalyst constant k2 per weight of the catalyst is, the more effective the aging time is. Also, the larger the amount x of the catalyst used is,
It is considered that the aging time is shortened because these reactions are promoted. Further, it is considered that the smaller the index I indicating the number of moles of isocyanate groups with respect to 100 moles of active hydrogen, the smaller the remaining unreacted isocyanate groups, so that the aging time is shortened.

Here, the catalyst constant k1 is determined by equimolar amounts of TDI-100 (2, 4) in a benzene solution in the presence of the catalyst.
Refers to the reaction constant in the case where diethylene glycol is reacted with isomer (100% isomer), and indicates the resination reaction activity of the catalyst. On the other hand, the catalyst constant k2 refers to a reaction constant when an equimolar amount of TDI-100 is reacted with water in a benzene solution in the presence of the catalyst, and indicates the foaming reaction activity of the catalyst. . Therefore, x (k1 + k2), which is the product of the sum of these catalyst constants and the amount of catalyst used, represents the total reaction activity of the catalyst in the formulation. When a plurality of catalysts are used, the total reaction activity of each catalyst may be used.

Regarding the index I indicating the number of moles of the isocyanate group with respect to 100 moles of the active hydrogen, the active hydrogen reacts with the isocyanate group to reduce the isocyanate group. It is considered that the remaining unreacted isocyanate groups decrease. Therefore, it is considered that the smaller the index I, the shorter the aging time. However, if it is too small, curing will be insufficient, and a good foam as a cushioning material will not be obtained, and the final compression set itself will also deteriorate. The range of the index I at which both the shortening of the aging time and the curing properties are compatible is 60 to 100.

From these facts, the total reaction activity of the catalyst x
The sum of (k1 + k2) divided by the index I indicating the number of moles of isocyanate groups with respect to 100 moles of active hydrogen, and summing the values for each catalyst,
It indicates the magnitude of the action for shortening the aging time. When the relationship between the numerical value calculated by the left side and the aging time was examined, it was found that if the numerical value was 0.40 or more, the aging time was within 2 hours, and the formula (1) was derived. .

On the other hand, if the index I is reduced in order to reduce the aging time according to the formula (1), the hardness of the obtained foam decreases. As a cushion material generally used for furniture and automobile seats, IL
While a hardness of D10 to 30 kgf / (314 cm ² ) is required, an ILD10
Cushion materials that are too soft, less than or equal to kgf / (314 cm ² ), even include inappropriate foams.

To solve this problem, the hardness required for furniture and automobile seats, that is, ILD 10 to 30 kgf / (31
It has been found that in order to obtain excellent cushioning properties while maintaining 4 cm ² ), it is necessary to use at least one or more polymer polyols as the polymer polyhydroxy compound (A) and simultaneously satisfy the formula (2). Was.

The main factors governing foam hardness are:
(B) the structure and amount of the low molecular weight polyhydroxy compound,
(A) The type and blending amount of the polymer polyol in the polymer polyhydroxy compound, (A) the number of functional groups and the hydroxyl value of the polymer polyhydroxy compound, the weight% of TDI in the organic polyisocyanate compound, and the index.

(B) The product Y × H of the compounding amount Y of the low-molecular-weight polyhydroxy compound and the hydroxyl value H indicates the crosslink density, and the larger the numerical value, the higher the hardness. (B) When a plurality of low molecular weight polyhydroxy compounds are used, the sum of the respective crosslink densities is used.

The weight percentage T of TDI in the organic polyisocyanate compound is in the range of 50 to 100 as the polymer concentration P in the polymer polyhydroxy compound (A) is higher, which is determined by the type and blending amount of the polymer polyol. , And the larger the index I,
The resulting foam becomes hard. From this, the left side of equation (2) was devised as an equation indicating the hardness of the obtained foam. It is considered that the larger the numerical value calculated by the left side, the higher the hardness of the obtained foam. Therefore, when the numerical value for obtaining the required ILD of 10 kgf / (314 cm ² ) or more was investigated, it was found to be 10,000. , Equation (2) was derived.

By satisfying both the expressions (1) and (2) described above, it is possible to shorten the aging time while maintaining the practical hardness and cushioning properties of furniture and automobile seats. became.

As the polymer polyhydroxy compound (A) used in the present invention, one or both of a polymer polyol, a polyether polyol and a polyester polyol widely used for flexible cold-cure foams are blended with the polymer polyol. Things.

The polyether polyol is obtained by random or block addition polymerization of an alkylene oxide to a starting material having two or more active hydrogens in the presence of a basic catalyst. Examples of the starting material include polyhydric alcohols such as ethylene glycol, propylene glycol, butanediol, hexanediol, glycerin, trimethylolpropane, pentaerythritol, diglycerin, sorbitol, and sugar, monoethanolamine, diethanolamine, and triethanolamine. And amines such as ethylenediamine and diethylenetriamine. These starting materials may be used alone or in combination of two or more.

As the alkylene oxide, any of ethylene oxide, propylene oxide, butylene oxide, styrene oxide and the like can be used. Of these, ethylene oxide (hereinafter referred to as "EO") and propylene oxide are particularly preferable. (Less than,
"PO").

The polyester polyol is obtained by dehydration condensation of the starting material used for the above-mentioned polyether polyol with a dibasic acid, or by ring-opening polymerization of ε-caprolactone.

The polymer polyol is obtained by graft-polymerizing the polyether polyol with an ethylenically unsaturated monomer such as acrylonitrile, styrene and butadiene in the presence of a radical polymerization catalyst. The polymer concentration in the polymer polyol refers to the proportion of the ethylenically unsaturated monomer graft-polymerized, and is 20 to 40% by weight.
Is preferred.

The high molecular weight polyhydroxy compound (A) used in the present invention has a terminal hydroxyl group primary rate of 50%.
Those having a hydroxyl value of 20 to 60 mgKOH / g are preferred. If the terminal hydroxyl group primary conversion rate is too low, the reaction is slow and the foam tends to collapse, and even if the foam can be formed, the hardness and cure properties become insufficient. If the hydroxyl value is too high, the closed cell rate of the foam will increase,
Crushing becomes difficult, and the rebound resilience and permanent set characteristics deteriorate. Conversely, if the hydroxyl value is too low, the hardness becomes insufficient.

The (B) low molecular weight polyhydroxy compound used in the present invention is generally known as a crosslinking agent or a chain extender, and (A) a polymer polyhydroxy compound alone having insufficient hardness. Used to increase hardness. Of the above-mentioned (A) starting materials of the high molecular weight polyhydroxy compound and alkylene oxide adducts thereof, those having a hydroxyl value of 300 mgKOH / g or more are suitably used alone or in a mixture. If the hydroxyl value is too low, a sufficient effect of improving hardness cannot be obtained.

The organic polyisocyanate compound used in the present invention includes TDI alone or cr-MD
A mixture in which I is mixed in an equal amount or less by weight can be used. That is, TDI: cr-MDI = 100: 0 to 5
Mixtures in the range of 0:50 (weight) can be used.

As the catalyst used in the present invention, a catalyst widely used for a flexible polyurethane foam can be used. For example, triethylenediamine, N, N'-tetramethylhexamethylenediamine, N, N'-dimethyl Ethanolamine, bis (2-dimethylaminoethyl)
Ethers, amine compounds such as N, N, N ′, N ″, N ″ -pentamethyldiethylenetriamine, and metal compounds such as stannas octate and dibutyltin dilaurate may be used alone or in combination. it can.

The blowing agents used in the present invention include water and other blowing agents. Representative examples of the latter include low-boiling organic compounds such as trichloromonofluoromethane and methylene chloride. They may be used alone or a plurality of them may be arbitrarily mixed and used.

In practicing the present invention, various additives such as a foam stabilizer, a colorant, and a flame retardant can be used as necessary.

The foaming according to the method of the present invention can be performed according to a known method. As an example, each raw material other than the organic polyisocyanate compound is pre-mixed in a container, then the organic polyisocyanate compound is added, and after stirring and mixing, the mixture is poured into a mold having a desired shape, and cured by heating to form a foam. Obtainable. Industrially, it is preferable to mix and inject using a high-pressure or low-pressure foaming machine.

As described above, the present invention comprises a polymer polyol as a polyhydroxy compound and TDI as an organic polyisocyanate compound as essential components. The relationship between the index, the catalyst constant and the amount used is further examined. By simultaneously satisfying a certain relational expression for the relationship between the valency and the TDI content in the organic polyisocyanate compound, the polymer concentration in the high molecular weight polyhydroxy compound, and the index, there is no need for a ripening step or after-curing all day long, All MDI
The aging time can be reduced to within 2 hours without using a formula.

Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.

[0035]

EXAMPLES The properties and the like of (A) the high molecular weight polyhydroxy compound, (B) the low molecular weight polyhydroxy compound, the catalyst, and (C) the organic polyisocyanate compound used in the examples are shown in Tables 1 to 4, respectively.

[0036]

[Table 1]

[0037]

[Table 2]

[0038]

[Table 3]

[0039]

[Table 4] * Mixed 2,4 and 2,6 isomers at 80:20

Examples 1, 2, 3, and 9 and Comparative Examples 1, 2,
3, 4, 5, 6, and 8 (A) 70 parts of polyether polyol as polymer polyhydroxy compound, 30 parts of polymer polyol, (B)
The low-molecular-weight polyhydroxy compound and the catalyst were placed in a container at a ratio of a variable portion, 1 part of a foam stabilizer and 2.9 parts of water, and the mixture was uniformly mixed and adjusted to 22 ° C. Also adjusted to 22 ° C (C)
The organic polyisocyanate compound was added to each index, stirred for 5 seconds, and quickly poured into a 350 mm × 350 mm × 50 mm aluminum mold adjusted to 55 ° C. in advance. 80 °
C was placed in an oven adjusted to C and heated and cured for about 7 minutes.

The physical properties of the foam were left to stand all day and night after molding.
It was measured according to SK6401.

The compression set was measured after elapse of 2 hours (a ₂ ) and after elapse of 24 hours (a ₂₄ ) after demolding, and the ripening degree was calculated by the following equation. Aging degree = [(50-a ₂ ) / (50-a ₂₄ )] × 100 [%]

In the same manner, foaming was carried out using an actual automobile seat, and two hours after the foaming was released, a seat assembly was carried out, and the presence or absence of deformation was examined.

Examples 4, 5, 6, 7, 8 and 10 (A) 40 parts of a polyether polyol as a high molecular weight polyhydroxy compound, 60 parts of a polymer polyol, (B)
The low molecular weight polyhydroxy compound and the catalyst were placed in a container at a ratio of a variable part, 1 part of a foam stabilizer and 3.2 parts of water, and the mixture was uniformly mixed and adjusted to 22 ° C. Thereafter, a form was prepared in the same manner as in Example 1, and the physical properties were evaluated.

Comparative Example 7 A container containing (A) 100 parts of polyether polyol as a high molecular weight polyhydroxy compound, (B) a variable part of a low molecular weight polyhydroxy compound and a catalyst, 1 part of a foam stabilizer, and 2.9 parts of water. After mixing uniformly, the mixture was adjusted to 22 ° C. Thereafter, a form was prepared in the same manner as in Example 1, and the physical properties were evaluated.

Comparative Example 9 (A) 70 parts of a polyether polyol as a high molecular weight polyhydroxy compound, 30 parts of a polymer polyol, (B)
The low-molecular-weight polyhydroxy compound and the catalyst were placed in a container at a ratio of a variable portion, 1 part of a foam stabilizer and 2.9 parts of water, and the mixture was uniformly mixed and adjusted to 22 ° C. Next, a mixture obtained by adding 8 parts of CFC 141b to (C) the organic polyisocyanate compound D-4 in an amount corresponding to the index 90 and uniformly mixing the resulting mixture was added. Thereafter, a foam was prepared in the same manner as in Example 1, and the physical properties were evaluated. Was done.

Comparative Example 10 4,4'-MDI / 2,4'-MDI / cr-MDI =
50 parts / 10 parts / 40 parts of the mixture are combined with 13 parts of PEG10
By reacting with M.00, a urethane-modified MDI prepolymer D-5 having an NCO content of 28% was obtained. Using this as an organic polyisocyanate compound (C), a foam was prepared in the same manner as in Comparative Example 9 except for the above, and physical properties were evaluated.

The evaluation results are shown in Tables 5 and 6 in Examples 1 to 10.
And Comparative Examples 1 to 10 are shown in Tables 7 and 8.

[0049]

[Table 5]

[0050]

[Table 6]

[0051]

[Table 7]

[0052]

[Table 8]

[0053]

According to the method of the present invention, there is no need for after-curing, and the aging time can be greatly reduced.
Also, since the method of the present invention does not require equipment modification,
It is also economically superior to other methods. Furthermore, since the space required for ripening, which is required by the conventional method, is not required, the space can be effectively used, and furthermore, the ripening time can be significantly shortened and the productivity can be improved.

Continued on the front page (72) Inventor Takeshi Takiguchi 771 Kozono, Ayase-shi, Kanagawa Ikeda Bussan Co., Ltd. (72) Inventor Eiichi Yamano 771 Koizono, Ayase-shi, Kanagawa Co.

Claims (2)

[Claims] (A) a polymer polyhydroxy compound having an average number of functional groups of 2 or more, a terminal hydroxyl group primary rate of 50% or more, and a hydroxyl value of 20 to 60 mgKOH / g; ) The average number of functional groups is 2 or more, and the hydroxyl value is 3
A low molecular weight polyhydroxy compound of at least 00 mg KOH / g and (C) an organic polyisocyanate compound containing at least two or more isocyanate groups, a catalyst, a foaming agent,
A method for producing a flexible polyurethane foam by reacting in the presence of a foam stabilizer and other auxiliaries, wherein (C) the organic polyisocyanate compound is a mixture of tolylene diisocyanate and polymethylene polyphenyl isocyanate, and the mixing ratio thereof is 100: 0 by weight ratio
(A) the high molecular weight polyhydroxy compound is a polyol containing a polymer polyol as an essential component, and the catalyst and the isocyanate index are represented by the following formula 1. 1) (Wherein, X is the number of parts of the catalyst used per 100 parts of the polymer polyhydroxy compound (A), K1 is the catalyst constant per weight of the catalyst in the resination reaction,
Is the catalyst constant per weight of catalyst in the foaming reaction, I is the isocyanate index, and i
Is the number of types of catalyst and is an integer from 1 to n. )
And (A) a high molecular weight polyhydroxy compound, (B) a low molecular weight polyhydroxy compound, (C) an organic polyisocyanate compound, and the isocyanate index are represented by the following formula 2. (Wherein, Y represents the number of parts of (B) the low molecular weight polyhydroxy compound used per 100 parts of the high molecular weight polyhydroxy compound (A), and H represents the hydroxyl value (mg KOH / g) of (B) the low molecular weight polyhydroxy compound. And T is (C)
The weight percent of tolylene diisocyanate in the organic polyisocyanate compound being 50-100, P is the polymer concentration in the (A) high molecular weight polyhydroxy compound and is not zero, I is the isocyanate index, and m is the number of types of the low molecular weight polyhydroxy compound (B). A method for producing a flexible polyurethane foam, characterized by satisfying (1). 2. The method for producing a flexible polyurethane foam according to claim 1, wherein the isocyanate index is 80 to 90.