JPH0211614A - Production of flexible polyurethane foam - Google Patents

Abstract

PURPOSE:To produce a flexible polyurethane foam excellent in high-temperature in-mold moldability in pouring a urethane stock solution by reacting a polyhydroxy compound prepared from specified polyols with an organic polyisocyanate, a catalyst, a foam stabilizer, a blowing agent and other additives. CONSTITUTION:A flexible polyurethane foam is prepared from a polyhydroxy compound, an organic polyisocyanate, a catalyst, a foam stabilizer, a blowing agent and other additives, by using as said polyhydroxy compound a polyoxyalkylene polyol of a hydroxyl value of 35-65mg KOH/g and/or a polymer polyol (A) obtained by graft-polymerizing an ethylenically unsaturated monomer with said polyol, or a combination of component A with, at most 1 pt.wt., per pt.wt. component A, polyalkylene polyol of a hydroxyl value of 85-180mg KOH/g and/or polymer polyol (B) obtained by graft-polymerizing an ethylenically unsaturated monomer with this polyol, and adding 0.01-2.0wt.% (in terms of the solid matter) silica sol (C) to this polyhydroxy compound.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for producing flexible polyurethane foam in mold foaming.

More specifically, the present invention relates to a method for producing a flexible polyurethane foam that uses a specific polyol and has excellent moldability at high temperatures during injection of a urethane stock solution during mold foaming.

[Prior Art and Problems] Normally, when producing soft hot mold foam, a urethane stock solution is injected into a mold that has been adjusted to a temperature of 35 to 45 degrees Celsius, foaming is performed, and after a hardening reaction occurs in a furnace, desorption is performed. mold and get the product. Mold temperature 35-45
The reason why it is necessary to adjust the temperature is that, for example, if the temperature is below 35°C, insufficient curing may occur or increase in density, and if it is above 45°C, the foam surface may peel off or cracks may occur inside the foam. This is because it is not possible to obtain a good product. In addition, when manufacturing low-density or low-hardness foam, Freon-11 is normally used, but in the future, due to fluorocarbon regulation issues, we will reduce the amount of Freon used.
Or it is desirable not to use it.

Therefore, if a good foam can be stably obtained even when the mold temperature is 45° C. or higher, the mold cooling step after demolding the foam in the foam manufacturing line can be greatly omitted, and energy loss can also be prevented. Furthermore, the foam obtained by increasing the mold temperature has a lower density due to the higher foaming efficiency. Therefore, the blowing agent must be reduced to obtain the same density as the foam at normal mold temperatures. In other words, this means that the amount of fluorocarbons used can be reduced in response to the issue of fluorocarbon regulations, which will become important in the future.

[Means for Solving the Problems] The present inventors discovered that the mold temperature at the time of injection of the urethane stock solution was 45°C.
As a result of intensive studies to obtain a flexible polyurethane foam that can provide a good foam body even with the above conditions and that can reduce the amount of added fluorocarbon, the present invention has been achieved.

That is, in producing flexible polyurethane foam from a polyhydroxy compound, an organic polyisocyanate, a catalyst foam stabilizer, a blowing agent, and other additives, the present invention provides (A) a hydroxyl value of 35 to 65 mg KO+ (/g) as a polyhydroxy compound. A polyoxyalkylene polyol and/or a polymer polyol obtained by graft polymerizing an ethylenically unsaturated monomer to the polyol; 180 mgKOH/g of a polyoxyalkylene polyol and/or a polymer polyol obtained by graft polymerizing an ethylenically unsaturated monomer to the polyol, and this polyhydroxy compound has a solid content of 0% relative to the polyhydroxy compound. This is a method for producing a flexible polyurethane foam characterized by blending silica sol (C) in an amount of 1 to 2.0% by weight.

In the present invention, the polyoxyalkylene polyol is a polyether polyol obtained by adding an alkylene oxide to a compound (hereinafter referred to as an initiator) having a small number of hydrogen atoms to which two alkylene oxides can be added.Alkylene oxide Although a small amount of other monoepoxides such as halogen-containing alkylene oxides, styrene oxides, glycidyl ethers, etc. may be added thereto, it is preferable to use substantially only alkylene oxides.The alkylene oxides have 2 to 2 carbon atoms. The alkylene oxide of No. 4 is suitable, and propylene oxide alone or a combination of propylene oxide and ethylene oxide is particularly preferred. When propylene oxide and ethylene oxide are used together, a mixture of both may be added (or may be added separately or sequentially). Often these can be combined, with an ethylene oxide cap if the ethylene oxide is added last.

Furthermore, the proportion of primary hydroxyl groups can be adjusted by further adding a small amount of propylene oxide after capping with ethylene oxide. As the initiator, polyhydric alcohols, polyhydric phenols, mono- or polyamines, and others can be used, but polyhydric alcohols and polyhydric phenols are suitable, and polyhydric alcohols are particularly preferred.

Moreover, two or more types of initiators can also be used in combination.

Specific examples of initiation are shown below, but the invention is not limited thereto. A particularly preferred initiator is a trihydric polyhydric alcohol, or a mixture thereof with a dihydric, tetrahydric or higher hydric initiator.

Divalent initiators: ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, 1,4-butanediol, bisphenol A.

Trivalent initiators - diglycerin, trimethylolpropane, hexanetriol.

Initiators with a valence of 4 or higher: pentaerythritol, diglycerin, ditrimethylolpropane, dextrose, sorbitol, shakerose, novolak.

Examples of ethylenically unsaturated heptamers include styrene,
Acrylonitrile or the like can be used, and a polymer polyol obtained by graft polymerizing these in the presence of a free radical polymerization catalyst can also be used as part or all of each of (A) and (B). The amount of this polymer is preferably 50% by weight or less, particularly 30% by weight or less based on the total polyoxyalkylene polyol.

The other main raw material for producing flexible polyurethane foams is polyisocyanate compounds.

As the polyisocyanate compound, various compounds having two or more incyanate groups can be used, but aromatic polyisocyanates are particularly suitable. Suitable aromatic polyisocyanates include mononuclear or polynuclear compounds having isocyanate groups bonded to aromatic nuclei, and modified products thereof. Specific examples include tolylene diisocyanate, diphenylmethane diisocyanate, polymethylene polyphenylisocyanate, and prepolymer types, carbodiimide types, urea types, and other modified products thereof. Two or more of these polyisocyanate compounds can also be used in combination. The amount of the polyisocyanate compound used is about 90 to 120, especially about 95, expressed as 100 times the number of isocyanate groups to the number of active hydrogens in the total active hydrogen-containing compounds (usually referred to as isocyanate index).
~110 is appropriate. The active hydrogen-containing compound is mainly a polyol such as the above-mentioned polyoxyalkylene polyol, but it also contains a small amount of water as a blowing agent, and in some cases, if a chain extender or crosslinking agent is used, they may also be used. included.

Another essential component of the foamable mixture is the catalyst. As a catalyst for producing flexible polyurethane foam, a tertiary amine catalyst and an organometallic compound, particularly an organotin compound, are usually used, and they are usually used in combination. Various tertiary amine catalysts can be used as the tertiary amine catalyst, such as triethylenediamine, N-ethylmorpholine, N,N-dimethylaminoethylmorpholine, triethylamine, N,N,N' , N'-tetramethylhexamethylenediamine, bis(2-dimethylaminoethyl)ether, N,N',N'-trimethylaminoethylethanolamine, etc., and two or more of these can be used in combination. A particularly preferred tertiary amine catalyst is triethylene diamine, especially [Dabco 33LV
A mixture of triethylene diamine and dipropylene glycol in a weight ratio of 1:2, well known under the trade name J, is most suitable. The amount used can vary depending on the desired reaction conditions, etc., but is usually about 0.01 to 1.0 parts by weight, preferably 0.02 to 0.0 parts by weight, based on 100 parts by weight of the polyol.
．． 5 parts by weight is appropriate, especially "Dub: +33LVJ
It is appropriate to use 0.1 to 0.5 parts by weight of and Lte. The organometallic compound catalyst is most preferably an organotin compound catalyst, such as stannath octoate, stannath slaurate, dibutyltin dilaurate, dibutyltin dimaleate, dibutyltin diacetate, dioctyltin diacetate, and the like. In particular, stannath octoate and dibutyltin dilaurate are preferred, and the amount of this organotin compound catalyst used is usually 0 parts by weight per 100 parts by weight of polyol.
．． O1 to 1.0 parts by weight. However, the amount of this catalyst used needs to be slightly changed depending on the type of polyol, reactivity, and other conditions, and the various optimal ranges are relatively narrow. Similar to the description of the tin range in the production of high modulus foams.

In the present invention, this tin range tends to increase as the amount of silica sol increases. For example, if the tin range is about 0.05 to 0.1 parts by weight in a system without silica sol, the tin range is about 0.0 parts by weight in a system containing about 0.2 parts by weight of silica sol in solids based on the polyol. 12~
It becomes 0.18.

Another ingredient added to the foamable mixture is a blowing agent. Water and halogenated hydrocarbon blowing agents are suitable as blowing agents, but low boiling point gases such as air and other blowing agents may be used alone or in combination with water and halogenated hydrocarbon blowing agents. Moreover, water and a halogenated hydrocarbon foaming agent can also be used together. Examples of the halogenated hydrocarbon blowing agent include trichlorofluoromethane, dichlorodifluoromethane, and methylene chloride. A particularly preferred blowing agent is water, the amount of which is used varies depending on the density of the desired foam, but is usually about 1 to 8 parts by weight, particularly about 2 to 6 parts by weight, based on 100 parts by weight of polyol. Furthermore, another normally essential ingredient is a siloxane foam stabilizer,
Examples include polydialkylsiloxane and polydialkylsiloxane-polyoxyalkylene block copolymer. Other optional ingredients include, for example, colorants, antioxidants, ultraviolet absorbers, light stabilizers, flame retardants, and other additives that can be used in the production of cured foam.

The silica sol in the present invention is one in which fine particulate silica is stably dispersed in a dispersion medium. "Stablely" means that the particulate silica does not substantially separate from the dispersion medium even if it is allowed to stand still. The average particle diameter of the finely divided silica in this silica sol is usually 1 μm or less, and preferably about 1 to 100 μm. Most preferably about 5-20I11μ.

It is essential that the amount of silica sol added to the polyoxyalkylene polyol is 0.01 to 2.0% by weight in terms of solid content based on the polyoxyalkylene polyol. A more preferable blending amount is 0.02 to 0.5, especially 0.02 to 0.5.
05-0.3% by weight.

If the amount is less than this range, the high temperature molding properties of the flexible polyurethane foam will not reach the desired level. The lower limit of the more preferred amount is about 0.08% by weight. If the blending amount exceeds this range, the resulting flexible polyurethane foam is likely to suffer from various problems. For example, the foam surface tends to crack or become rough.

Among the polyhydroxy compounds used in the present invention, (A)
The component is a polyether polyol with a hydroxyl value of 35 to 65 mgKOH/g and/or a polymer polyol obtained by graft polymerizing an ethylenically unsaturated monomer to the polyol. However, if the hydroxyl group is less than 35 mgKOH/g, the foam is in the process of foaming. It will collapse. Furthermore, if the hydroxyl value exceeds 65 mg KO)1/g, the foam becomes closed cells with no air permeability, and in severe cases, shrinkage occurs.

Component (B) is a polyoxyalkylene polyol with a hydroxyl value of 85 to 180 mgKOH/g and/or a polymer polyol obtained by graft polymerizing an ethylenically unsaturated monomer to the polyol, but the hydroxyl group is 85 to 180 mgKOH/g.
If it is less than mgKOH/g, cracks occur inside the foam or peeling occurs on the foam surface.

Furthermore, if the hydroxyl value exceeds 180 mgKOH/g, the foam becomes closed cells with no air permeability, and in severe cases, shrinkage occurs. Polyhydroxy compound (A):
The weight ratio of (B) is 100:0 to 50:50, preferably 95:5 to 60:40, especially 90:l
0 to 60:40 is used. If the specific range of the present invention is exceeded, the foam becomes closed cells with no air permeability, but cracks occur inside the foam and peeling occurs on the foam surface.

[Examples] Hereinafter, the present invention will be specifically explained with reference to Examples and Comparative Examples. Hereinafter, parts refer to parts by weight.

Example 1 A polyether polyol (hereinafter referred to as A-1) having a hydroxyl value of 56.0 mgKOH/g was obtained by addition polymerizing alkylene oxide to glycerin. Next, a polyether polyol (hereinafter referred to as B-1) having a hydroxyl value of 100.0 mgKOH/g was obtained by addition polymerizing alkylene oxide to glycerin. These A-1, 8
-1 in a weight ratio of 70:30 to obtain a polyether polyol in which silica sol was blended so that the solid content was 0.1% by weight with respect to the polyether polyol ( 450 parts of this mixture, 18 parts of water, Dabc.

1.35 parts of 33LV (manufactured by Sun-Avro), 1.35 parts of N-methylmorpholine, and 6.75 parts of 5Z-1105 (silicone foam stabilizer manufactured by Nippon Unicar) were placed in a polyethylene container of 24, and heated at 3000 rpm+ for 30 seconds. After stirring, adjust the liquid temperature to about 25℃, and
), stirred for another 5 seconds, and immediately added 0.54 parts of DI.
() lylene diisocyanate)-80 in a stoichiometric amount (N
GO index 1.00) and stirred for 5 seconds to form a 60mm
℃ into an aluminum mold, and the mold was heated to 150℃.
The molded product was placed in an oven set at 100 mL and cured for 12 minutes to obtain a soft mold form. The results are shown in Table 1.

Example 2 A soft mold form was obtained by pouring into a mold at 35° C. in the same manner as in Example 1. The results are shown in Table 1.

Example 3 In the same manner as in Example 1, the mixture was poured into a mold at 50° C. to obtain a soft mold form. The results are shown in Table 1.

Example 4 A polyether polyol (hereinafter referred to as B-2) having a hydroxyl value of 140.0 mgKOH/g was obtained by addition polymerizing alkylene oxide to glycerin. °These A
-1 and B-2 are blended in a weight ratio of 80:20, and silica sol is added to the polyether polyol so that the solid content is 0.2% by weight. A polyol was obtained (this was C
-2). 450 parts of the mixture, 20 parts of water, Dab
08 parts of co 33LVO, 0.4 parts of bis(2-dimethylaminoethyl) ether, and 8 parts of 5F-2904 (silicone foam stabilizer manufactured by Toshi Silicon Co., Ltd.) were placed in a 212 polyethylene container and stirred at 3000 rpm for 30 seconds. ,
Adjust the liquid temperature to about 25℃ and add Stanus Octoate 0℃
Add 8 parts. The mixture was poured into a mold at 60° C. in the same manner as in Example 1 to obtain a soft mold form. The results are shown in Table 1.

Comparative Example I A polyether polyol prepared by blending A-1:B-1 at a weight ratio of 40:60 with silica sol to give a solid content of 0.1% by weight (this C-3) was obtained. The mixture was poured into a mold at 60° C. in the same manner as in Example 1 to obtain a soft mold form. The results are shown in Table 1.

Comparative Example 2 A-1 was adjusted to 100% by weight, and this polyether was injected into a mold at 60° C. in the same manner as in Example 1 to obtain a soft mold form. The results are shown in Table 1.

Table 1 Foam state and foam physical properties [Effects of the invention] The present invention has the effect of smoothly and advantageously producing a good foam body even at high mold temperatures. It also has the advantage that foams can be reduced or eliminated (but with lower density or stiffness).

Claims (1)

[Claims] 1. Polyhydroxy compound, organic polyisocyanate,
When producing flexible polyurethane foam from a catalyst foam stabilizer, a blowing agent, and other additives, (A) a polyoxyalkylene polyol with a hydroxyl value of 35 to 65 mgKOH/g and/or an ethylenic inorganic compound is added to the polyol as a polyhydroxy compound. A polymer polyol obtained by graft polymerization of a saturated monomer, or a polyoxyalkylene polyol (B) having a hydroxyl value of 85 to 180 mgKOH/g and/or a polyoxyalkylene polyol having an equal weight or less to (A) and (A). A polymer polyol obtained by graft polymerization of an ethylenically unsaturated monomer is used, and 0.01 to 2.0% by weight of silica sol (C) is blended into this polyhydroxy compound as a solid content based on the polyhydroxy compound. A method for producing flexible polyurethane foam, characterized by: 2. In the method for producing flexible polyurethane foam, (
The method for producing a flexible polyurethane foam according to claim 1, wherein the weight ratio of A):(B) is 95:5 to 60:40.