JPH058211B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing a flexible polyether urethane foam having low air permeability. Soft polyether urethane foam with low air permeability has excellent compressive strength, impact resistance, and flexibility, so it has been expected to be used in applications such as cushioning materials, sound absorbing materials, and sealing materials. ,
Conventionally, no effective manufacturing method has been established and large demand has not been created, so there have been expectations for the establishment of a new effective manufacturing method. Conventionally, soft polyether urethane foam was
Generally produced by foaming and curing a mixture of a polyether polyol whose main component is propylene oxide with a molecular weight of about 3000, an organic polyisocyanate whose main component is tolylene diisocyanate, a blowing agent, a catalyst, and a foam stabilizer. It has been. The soft polyether urethane foam thus obtained consists mainly of open cells and is therefore a breathable foam. Such open cell breathable foams have flexibility,
It has excellent rebound resilience and is used for cushioning materials, sound absorbing materials, etc., but because of its low compression hardness, it is not suitable for advantageous use in high-load shock absorbing materials, cushioning materials, etc. Semi-rigid polyurethane foams are usually used for such applications, but such foams require highly reactive polyethers and organic isocyanates as polyethers and organic polyisocyanates, and conventional soft polyether urethane foams that are not highly reactive are used. When using polyether, organic polyisocyanate, diethanolamine,
It is necessary to use a crosslinking agent such as triethanolamine, which generally narrows the process range, making reaction control difficult and making it difficult to obtain a form of uniform quality at a low cost. There are disadvantages that make it difficult. Therefore, it has been desired to establish an advantageous manufacturing method for low air permeability soft polyether urethane foam.
Various methods have been proposed. For example, it has been proposed to use highly reactive polyethers or organic polyisocyanates as raw materials, increase curing catalysts, and use crosslinking agents, but these methods do not allow stable formation of foams. Either it cannot be obtained, or even if it can be obtained, it has the disadvantage that the process range is extremely narrow. Another method, as disclosed in JP-A-57-31976, is to produce a closed-cell polyurethane foam in the first step, and then crush it in the second step to obtain a foam with low air permeability. . However, this method has the disadvantage of requiring two steps. SUMMARY OF THE INVENTION It is an object of the present invention to provide a method for producing low air permeability polyether urethane foams that does not have the disadvantages of conventional methods for making low air permeability foams. That is, the present invention provides polyurethane foams from a reaction mixture comprising a polyether, an organic polyisocyanate, a blowing agent, a catalyst, and a foam stabilizer suitable for use in producing polyurethane foams from polyether polyols and organic polyisocyanates. In the method for producing a foam stabilizer, a compound of the formula (CH ₃ ) ₃ SiO[(CH ₃ ) ₂ SiO] _n [(CH _{3
) _ _}
25, and X has the structure [-R(C ₂ H ₄ O) _a (C ₃ H ₆ O) _b Y] (R is an alkylene group containing 1 to 10 carbon atoms and a/b is The molar ratio is 3/1 to 1/3, and Y is -
OR′,

【formula】 [where m has an average value of 1 to 300, n has an average value of 1 to 25, and X has the structure [-R(C ₂ H ₄ O) _a (C ₃ H ₆ O) _b Y]

(R is an alkylene group containing 1 to 10 carbon atoms, a/b is a molar ratio of 3/1 to 1/3, and Y
―OR′,

【formula】

[Formula], R' is a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, and the proportion of hydrogen atoms is 50% or more]. In this polysiloxane-polyoxyalkylene copolymer, the number of dimethylsiloxane units is m
It is determined by the average value of 1 to 300, but
It is preferable to take an average value within the range of 20-200. The number of methyl polyoxyalkylene units is determined by n and can take an average value of 1 to 25, preferably an average value within the range of 3 to 15.
The polyoxyalkylene portion of _the polysiloxane-polyoxyalkylene copolymer is defined by the symbol X and is _a group having the structure -R( _C2H4O ) _a ( _C3H6O ) _bY . In this structure, R is an alkylene group containing 1 to 10 carbon atoms, preferably 2 to 10 carbon atoms.
Preferably, it is an alkylene group containing 5 carbon atoms. The polyoxyalkylene part of the polysiloxane-polyoxyalkylene copolymer consists of oxyethylene groups and oxypropylene groups, and the total amount is a + b
Determined by This takes an average value of 3 to 100, but preferably an average value within the range of 5 to 60. The terminal of the polyoxyalkylene moiety is Y,
This is -OR′,

[Formula] and

[Formula] Group (R' is a hydrogen atom or an alkyl group having 1 to 5 carbon atoms,
The proportion of hydrogen atoms is 50% or more, preferably 70% or more). In the present invention, the polysiloxane-polyoxyalkylene copolymer used as a foam stabilizer and the method for producing them are described in Patent Publication No. 12190/1989 entitled "Method for producing polyurethane foam" by D. Bayley and A. Pater. It is disclosed in detail in Japanese Patent Publication No. 43-16399. Therefore, the polysiloxane-polyoxyalkylene copolymer used in the present invention is a known compound, and the use of this compound as a foam stabilizer for flexible polyether urethane foam is also disclosed in the above-mentioned Japanese Patent Publication No. 1973-
12190 and Japanese Patent Publication No. 43-16399,
The present invention and the technologies disclosed in the above two patent publications are different, and the reason for this is shown below. Japanese Patent Publication No. 40-12190 describes a polysiloxane-polyoxyalkylene copolymer as a polysiloxane-polyoxyalkylene copolymer in which the terminal group of the polyoxyalkylene moiety is a hydroxyl group, which is a feature of the structure of the foam stabilizer used in the present invention. Although the general formula shows that coalescence is possible, the detailed description of the invention and the examples do not show a copolymer with a hydroxyl group at the end, but a copolymer with an alkoxy group at the end. The manufactured foam is also a general air permeable foam, and there is no disclosure at all about the manufacture of the low air permeable foam of the present invention, which is different from the present invention. Next, Claim 2 of Japanese Patent Publication No. 43-16399 discloses a polysiloxane-polyoxyalkylene copolymer similar to the present invention having a hydroxyl group at the terminal, and also shows examples using this copolymer. However, the purpose of using this copolymer is to have an excellent foam stabilizing effect and to make it possible to produce a stable premix of polyurethane foam (see No. 1 of the same publication).
(lines 24 to 28 of the right column of the page, lines 1 to 6 of the formula in the left column of the second page of the same page, and lines 8 of the last column of the left column to the last line of the right column of the 10th page of the same page) are disclosed. There is no disclosure regarding the production of low air permeability foams, which is different from the present invention. Polysiloxane with terminal hydroxyl group similar to that of the present invention
Other patents of similar technology using polyoxyalkylene copolymers as foam stabilizers include Japanese Patent Publication No. 52-13239;
Special Publication No. 53-35119, No. 55-104330, No. 57 Publication No.
-31976, JP-A-57-195722, etc., but the structure and purpose are different from the present invention. In other words, the oxyalkylene part of the copolymer in Japanese Patent Publication No. 52-13239 is only an ethylene oxide part, and the purpose is to manufacture hard urethane foam, and the purpose of Japanese Patent Publication No. 53-35119 is to manufacture hard urethane foam for casting. JP-A-55-104330 is for the production of waterproof (leak-resistant) open-cell polyurethane foam sealing material;
31976 is for the purpose of producing closed-cell polyurethane foam and crushing it to produce polyurethane foam sealing material, and
JP-A-57-195722 is aimed at producing a rigid urethane foam, and is different in that it aims at producing the low air permeability flexible polyurethane foam of the present invention. The amount of polysiloxane-polyoxyalkylene copolymer used in the process of the invention should be in the range of 0.5 to 5.0 parts by weight per 100 parts of polyether polyol, but more or less may be used. Also good. In addition to the above-mentioned polyether polyols, organic polyisocyanates, catalysts, blowing agents, and foam stabilizers, flame retardants, crosslinking agents, and polysiloxane-polysiloxanes that are outside the scope of the polysiloxane-polyoxyalkylene copolymers defined in the present invention. It may also contain an oxyalkylene copolymer. Examples of such bubble stabilizers are those of the general formula RSi [O(R′SiO) _p (C _o H _2o O) _q ]R″ and those of the general formula It is a copolymer of However, in the above formula, R is a hydrocarbon having 1 to 6 carbon atoms, R' is hydrogen or a hydrocarbon having 1 to 10 carbon atoms, p, q, r, s, and u are positive integers, and t is 0 or a positive integer, and n is an integer of at least 2. The final foamed composition of the present invention comprises a large amount of (1) a polyether polyol and (2) an organic polyisocyanate;
(3) a small amount of blowing agent, (4) a catalytic amount of catalyst, and (5) a small amount of polysiloxane-polyoxyalkylene copolymer sufficient to provide an open-cell, low air permeability, flexible urethane foam; (6) Contain appropriate ingredients accordingly. The production of flexible urethane foams with open cells and low air permeability using polysiloxane-polyoxyalkylene copolymers as defined herein has been previously achieved using other polysiloxane-polyoxyalkylene copolymers. This case is unique considering that a foam with communication and high air permeability can be obtained. It has further been found that the process of the present invention provides flexible polyether polyurethane foams with high hardness and low density. The open-cell, low-air permeability flexible polyurethane foam composition of the present invention is useful in a wide range of well-known fields. For example, gas, liquid loca materials, sound absorbing materials,
It can be used for insulation, sealing, shock absorption, etc. Compression hardness as defined herein and shown in the Examples below is measured using the method shown in JIS K6401. Furthermore, if a method based on this method is used in which the compression speed is increased, the properties as a shock absorbing material will be better exhibited. In addition, the closed cell ratio is ASTM D2856
Measure using an air comparison hydrometer shown in -70. Breathability (Journal of Cellular
It is measured by the method shown in Plastics 1965 Vol. 1 No. 1 p. 200-216). Example 1 After thoroughly mixing the following ingredients, the mixture was placed in a 30 x 30 x 30 cm box and after foaming was completed, the mixture was placed in a cure oven for curing. Ingredient parts by weight Polyether polyol made by addition polymerizing propylene oxide to glycerin Molecular weight 3000, hydroxyl value 50 100 Tolylene diisocyanate (80/20) 52.1 Copolymer A 1.0 Water 4.0 Triethylenediamine/dipropylene glycol 33/67 (weight) Mixture 0.2 N-ethylmorpholine 0.2 Stannous octylate 0.3 Example 2 and Comparative Examples 1 to 3 Instead of copolymer A, the same weight parts of copolymers B, C, D, and E are used, respectively. The method of Example 1 was repeated except for the following. Copolymer Average formula A (CH ₃ ) ₃ SiO [(CH ₃ ) ₂ SiO] ₇₀ [CH ₃ XSiO] ₇ Si
_{( CH 3 ) 3 _ _ _ _ _ _ _ _ _ _ 3XSiO} ] _{7Si
( CH 3 ) 3 _ _ _ _ _}
80% C (CH ₃ )SiO [(CH ₃ ) ₂ SiO] ₇₀ [CH ₃ XSiO] ₇ Si
_{( CH 3 ) 3 _ _ _ _ _ _ _ _ _ _ _ _} XSiO] ₇ Si
_{( CH 3 ) 3 _ _ _ _ _ _ _ _ _ _ _ 3XSiO} ] _{7Si
( CH 3 ) 3 _ _}

[Table] As shown in the above table showing the results of the above examples, in Example 1, the foam stabilizer of the present invention in which all the terminals of the polyoxyalkylene moieties of the copolymer are hydroxyl groups
The results obtained by using (A) are shown, showing that it has low air permeability. In Example 2, among the terminal groups of the polyoxyalkylene moiety of the copolymer, the hydroxyl group
The foam stabilizer of the present invention contains 80% and 20% of methoxy groups.
The results obtained by using (B) are shown, and it is shown that it has low air permeability. In Comparative Examples 1 and 2, a foam stabilizer (C is a foam stabilizer for general flexible polyether urethane foam) different from the foam stabilizer of the present invention in which the terminal group of the polyoxyalkylene moiety of the copolymer is only a methoxy group instead of a hydroxyl group. D is a foam stabilizer for general rigid polyether urethane foam). Good results were not obtained. Comparative Example 3 shows the results obtained by using a foam stabilizer (E) different from the foam stabilizer of the present invention in which the polyoxyalkylene portion of the copolymer is composed of a polyethylene oxide portion, but sagging occurred during foam production. However, good results were not obtained as in the present invention.

Claims (1)

[Claims] 1. A polyurethane foam from a reaction mixture comprising a polyether, an organic polyisocyanate, a blowing agent, a catalyst, and a foam stabilizer suitable for use in producing polyurethane foam from a polyether polyol and an organic polyisocyanate. In the process for producing a foam stabilizer, a compound of the formula (CH ₃ ) ₃ SiO[(CH ₃ ) ₂ SiO] _n [(CH _{3
) _ _}
25, and X has the structure -[R(C ₂ H ₄ O) _a (C ₃ H ₆ O) _b Y] (R is an alkylene group having 1 to 10 carbon atoms, and a/
b is 3/1 to 1/3 in molar ratio, and Y is -
OR′, [Formula] [Formula], where R′ is a hydrogen atom or an alkyl group having 1 to 5 carbon atoms,
and the proportion of hydrogen atoms is 50% or more) By using a polysiloxane-polyoxyalkylene copolymer represented by the following, a foam with extremely low air permeability and no shrinkage can be obtained. Method for manufacturing soft polyether urethane foam.