JPH033687B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for manufacturing flexible polyurethane foam by mold foaming. More specifically, by using a specific polyol and foam stabilizer, the mold temperature when pouring the urethane stock solution was increased to 55%.
By using a higher temperature range than normal, above ℃, the manufacturing process can be simplified and energy saved.
Furthermore, the present invention relates to a method for producing a flexible polyurethane foam that allows molded products with low density and excellent physical properties to be obtained. Normally, when manufacturing polyurethane foam using the soft hot cure mold method, urethane stock solution is poured into a mold adjusted to 35-45℃, foamed, and cured in a high-temperature furnace at 200-300℃. , demolding and obtaining the product. Mold temperature 35
The reason why it is necessary to adjust the temperature to ~45°C is that, for example, if the temperature is below 35°C, curing failure may occur or increase in density.If the temperature is above 45°C, the foam surface may become rough or cracks may occur inside the foam. This is because it is not possible to obtain a good product due to the occurrence of. Furthermore, in the normal manufacturing process of soft hot cure mold polyurethane foam, the mold temperature during demolding of the product is at a high temperature of 80 to 120°C. Therefore, after demolding the product and applying a mold release agent, the mold must be cooled to 35 to 45°C, which complicates the process and results in a large loss of energy. If a good product could be obtained by injecting the urethane stock solution into the mold at the same temperature during demolding or by a slight cooling, the cooling process would be almost unnecessary and energy loss could be prevented. Of course, if the cooling process is significantly shortened, the temperature of the curing furnace itself can also be significantly lowered. Additionally, traditional methods require a mold temperature of 35 to 45
℃, the resulting foam has a dense part called a skin layer on the surface, but by raising the mold temperature when pouring the urethane stock solution, the formation of the skin layer is almost eliminated, and raw materials can be saved. Furthermore, since there is no skin layer, a foam with excellent compression set can be obtained. Based on this idea, an attempt was made to raise the mold temperature when pouring the urethane stock solution to a higher temperature than usual. A method of raising the temperature to about 80℃ and then injecting it into a mold that is adjusted to a high temperature of 90 to 110℃ (Japanese Patent Publication No. 46-22120). (b) A method of injecting a urethane stock solution into a mold adjusted to a temperature of 45°C or higher by using three types of specific polyethers in a specific ratio (Japanese Patent Laid-Open No.
67330) etc. have been proposed. However, method (a) requires a large area;
In a practical mold with a complex shape, the fluidity of the mixed liquid is poor, resulting in poor filling performance and loss of raw materials during injection, making it impractical. Also b)
In this method, SH-192 and SH-190 are used as bubble stabilizers.
(manufactured by Toray Silicone Co., Ltd.), L-574OM (manufactured by Nippon Unicar Co., Ltd.), or F-242T (manufactured by Shin-Etsu Silicone Co., Ltd.) are used for ordinary soft polyurethane foam, but such ordinary bubble-stabilized polyurethane foams are used. A combination of the agent and the polyether specified in (b) causes roughness on the surface of the foam and cracks inside the foam, making it impossible to obtain a foam that is of practical use. Therefore, the inventors of the present invention have conducted extensive research on a method for producing a soft molded polyurethane foam that allows a good product to be obtained even when the mold temperature during injection of the urethane stock solution is higher than conventional ones.
The inventors have discovered that the object can be achieved by using a specific polyhydroxy compound and a specific foam stabilizer in combination, and have thus come to provide the present invention. That is, in the production of a flexible polyurethane foam whose main components are a polyhydroxy compound, a polyisocyanate, a blowing agent, a foam stabilizer, and a catalyst, the polyhydroxy compound (A) has a hydroxyl value of 35 to 65 mgKOH/g and an ethylene oxide content. 5 to 40% by weight of polyether polyol and/or a polymer polyol obtained by graft polymerizing an ethylenically unsaturated monomer to the polyether polyol (hereinafter referred to as component (A)) (B) Hydroxyl value 28 to 65 mgKOH/g A polyether polyol containing no ethylene oxide and/or a polymer polyol obtained by graft polymerizing an ethylenically unsaturated monomer to the polyether polyol (hereinafter referred to as component (B)) is used, and (C) is used as a foam stabilizer. ) general formula However, R is an alkyl group or acyl group having 1 to 8 carbon atoms, m, n, a and b are each 10
<m+n<100, 0.05<n/(m+n)<0.3,
A method for producing a flexible polyurethane foam characterized by using a siloxane-oxyalkylene copolymer (hereinafter referred to as component (C)) represented by an integer satisfying 20<a+b<60, 0.6<a/(a+b)<1. . In the polyhydroxy compound used in the present invention, component (A) is a compound obtained by adding alkylene oxide to an initiator in a random or block type, and has an ethylene oxide content of 5 to 40% by weight, preferably 10% by weight. ~20% by weight, hydroxyl value 36~
polyether polyol, which is 65mgKOH/g;
and a polymer polyol obtained by graft polymerizing an ethylenically unsaturated monomer to the polyether polyol in the presence of a free radical catalyst,
and a mixture of both. Examples of initiators include polyfunctional polyols having two or more active hydrogen groups such as ethylene glycol, propylene glycol, glycerin, trimerolpropane pentaerythritol, sorbitol, and sucrose, and alkanolamines such as monoethanolamine, diethanolamine, and triethanolamine. and polyamines such as ethylenediamine and diethylenetriamine. Examples of the alkylene oxide include ethylene oxide and propylene oxide.
Examples of ethylenically unsaturated monomers include styrene and acrylonitrile; examples of free radical catalysts include organic peroxides such as benzoyl peroxide; and azo compounds such as azobisisobutyronitrile. . If the ethylene oxide content is less than 5% by weight, cracks will occur inside the foam and the cells will become extremely coarse. If it exceeds 40% by weight,
This results in closed cells with no air permeability, and the skin on the foam surface becomes rough. Component (B) is a product obtained by addition polymerizing only propylene oxide to the above initiator, and has a hydroxyl value.
Examples include polyether polyols having a concentration of 28 to 65 mgKOH/g, polymer polyols obtained by graft polymerizing the ethylenically unsaturated monomers to the polyether polyols in the presence of the free radical catalyst, and mixtures thereof. If the hydroxyl value is less than 28 mgKOH/g, cracks will occur inside the foam, and in severe cases, it will collapse during foaming. In addition, if the hydroxyl value exceeds 65mgKOH/g,
The foam becomes closed cells with no air permeability, and is therefore impractical. The usage amounts of component (A) and component (B) are expressed as a weight ratio of (A) component: (B)
Ingredients = 80:20-20:80, preferably 65:35-35:
The range is 65. If it deviates from this range, the surface skin of the foam becomes rough, the inside of the foam becomes uneven, coarse cells or a foam with no air permeability occur. Next, as component (C), for example, etc. are given. In the general formula of component (C), when R is outside the range of an alkyl group or acyl group having 1 to 8 carbon atoms, m, n, a and b are each 10<m+n<
If it deviates from the ranges such as 100, 0.05<n/m+n<0.3, 20<a+b<60 and 0.6<a/a+b<1, or if both fall outside of these ranges, surface skin roughness will occur on the foam. However, cracks occur inside the foam, resulting in collapse or contraction, making it impossible to obtain a normal foam. The amount of component (C) used is by weight [component (A) + component (B)]: component (C) =
A preferable amount is a ratio of 0.5 to 3:100. Next, as the polyisocyanate, blowing agent, catalyst, etc., those commonly used in the production of flexible polyurethane foam can be mentioned. Examples of the polyisocyanate include 2.4-tolylene diisocyanate, 2.6-tolylene diisocyanate, and mixtures thereof. Examples of the blowing agent include water, monofluorotrichloromethane, difluorodichloromethane, methylene chloride, etc., but water alone is preferred. Examples of catalysts include triethylenediamine,
Examples include amine compounds such as tetramethylhexamethylene diamine, N-ethylmorpholine, and N-methylmorpholine, and organic tin compounds such as stannath octoate and dibutyltin dilaurate. Next, in the production of flexible polyurethane foam, component (A) and
When pouring into the mold a mixture containing component (B), polyisocyanate, blowing agent, and component (C) as a foam stabilizer and a catalyst, that is, a urethane stock solution, the mold temperature should be at a high temperature of 55℃ or higher. It is necessary that there be. When the mold temperature is less than 55°C, the mold temperature is low, so the advantages such as energy saving and low specific gravity of the foam are diminished. In the present invention, other additives such as flame retardants and plasticizers can also be used as necessary. According to the present invention, by using a specific polyhydroxy compound and a specific bubble stabilizer in combination, a flexible polyurethane with good physical properties can be produced even when the mold temperature during injection of the urethane stock solution is higher than conventional ones. form is obtained. The present invention will be specifically explained below with reference to Examples. Hereinafter, "parts" and "%" are based on weight. Example 1 Preparation of various components (A) and (B) Components (A) and (B) were obtained by addition polymerizing an alkylene oxide to an initiator according to a known method. 2 Preparation of Various Components (C) Component (C) was obtained according to a known method. 3 Preparation of flexible polyurethane foam The temperature was adjusted to 20-22℃ in a 1-volume poly beaker.
(A) component (variable part), (B) component (variable part), 10 parts of water,
Add 0.25 parts of triethylenediamine and 2.5 parts of component (C) and mix with a mixer at a rotation speed of 3000 to 4000 RPM.
After uniformly mixing for seconds, add U-28 (manufactured by Nitto Kasei Co., Ltd.)
Add 0.25 part of TDI-80 (2.4-tolylene diisocyanate/2.6-tolylene diisocyanate 80/20) in a stoichiometric amount (NCO index 1.00), and immediately stir for 5 seconds to adjust the temperature. Injected into a x400 (L) x 50 (H) mm aluminum mold and formed into a form.
Next, put this mold in an oven at 150℃ 7
After curing for a minute, the mold was released. The obtained foam was left for 24 hours and its physical properties were measured. The results are shown in Table 1.

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【table】

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Claims (1)

[Scope of Claims] 1. In the production of a flexible polyurethane foam whose main components are a polyhydroxy compound, a polyisocyanate, a blowing agent, a foam stabilizer, and a catalyst, as a polyhydroxy compound, (A) with a hydroxyl value of 35 to 65 mgKOH/g; Polyether polyol with an ethylene oxide content of 5 to 40% by weight and/or a polymer polyol obtained by graft polymerizing an ethylenically unsaturated monomer to the polyether polyol (hereinafter referred to as component (A)) and (B) hydroxyl group using a polyether polyol having a valence of 28 to 65 mgKOH/g and not containing ethylene oxide and/or a polymer polyol obtained by graft polymerizing an ethylenically unsaturated monomer to the polyether polyol (hereinafter referred to as component (B)), and As a bubble stabilizer (C) General formula However, R is an alkyl group or acyl group having 1 to 8 carbon atoms, m, n, a and b are each 10
<m+n<100, 0.05<n/(m+n)<0.3,
A method for producing a flexible polyurethane foam, characterized by using a siloxane-oxyalkylene copolymer (hereinafter referred to as component (C)) represented by an integer satisfying 20<a+b<60, 0.6<a/(a+b)<1. 2. In the production of flexible polyurethane foam, the ratio of component (A) to component (B) is 80:20 to 20:80 by weight,
and the ratio of [(A) component + (B) component] to (C) component is by weight.
The method for producing a flexible polyurethane foam according to claim 1, wherein the ratio is 100:0.5 to 3. 3. In the production of flexible polyurethane foam,
The method for producing a flexible polyurethane foam according to claim 2, wherein the mold temperature during injection of the urethane stock solution is 55° C. or higher.