JP2007146091A - Method for producing polyurethane foam containing expandable bead - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a favorable polyurethane foam containing expandable beads, wherein the expandable beads are sufficiently expanded, even when they are added in a relatively large amount. <P>SOLUTION: In a method for producing the polyurethane foam containing the expandable beads, a polyurethane foam raw material containing at least a polyol, a polyisocyanate, a foaming agent and unexpanded expandable beads is reacted to expand and cure the polyurethane foam, and the expandable beads are expanded by the heat generated at the reaction. Here, the expansion and curing of the polyurethane foam is carried out under pressure, preferably of 0.15-0.2 MPa. The amount of the unexpanded expandable beads contained is preferably 50-200 pts.wt. based on 100 pts.wt. polyol. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method for producing a foamed bead-containing polyurethane foam in which foamable beads in a polyurethane foam raw material are foamed (expanded) by heat generated during the reaction between a polyol and a polyisocyanate.

  Conventionally, as a method for producing lightweight and high-hardness foams, foamed beads containing foamed beads that are foamed by the heat generated during the reaction between polyol and polyisocyanate by adding unfoamed foamed beads to the polyurethane foam raw material A method for producing a polyurethane foam has been proposed.

  However, in the conventional method for producing foamed bead-containing polyurethane foam, when the foamable bead content exceeds a certain amount and the volume of foamable beads in the polyurethane foam increases, the proportion of urethane resin decreases. As a result, there is a problem that heat generation at the time of foam curing of the polyurethane foam is not sufficiently performed, and as a result, the foamable beads are not sufficiently foamed and a good foamable bead-containing polyurethane foam cannot be obtained. For this reason, the content of expandable beads cannot be increased so much, and there is a limitation in increasing the hardness of the foamable bead-containing polyurethane foam.

JP-A-48-77957 Japanese Patent Publication No. 47-25855

  The present invention has been made in view of the above points, and even if a relatively large amount of expandable beads are added, the expandable beads can be sufficiently expanded to obtain a foamable bead-containing polyurethane foam. An object of the present invention is to provide a method for producing a bead-containing polyurethane foam.

  The invention of claim 1 is to react a polyurethane foam raw material containing at least a polyol, a polyisocyanate, a foaming agent, and an unexpanded expandable bead to foam and cure the polyurethane foam, and to generate the expandable bead by heat generated during the reaction. In the method for producing a foamed bead-containing polyurethane foam to be foamed, the polyurethane foam is foamed and cured under pressure.

  The invention according to claim 2 is the method for producing a foamable bead-containing polyurethane foam according to claim 1, wherein the pressure is 0.15 to 0.2 MPa.

  The invention of claim 3 is characterized in that, in claim 1 or 2, the content of the unexpanded expandable beads is 50 to 200 parts by weight with respect to 100 parts by weight of the polyol.

  A fourth aspect of the present invention is characterized in that, in any one of the first to third aspects, the heat-resistant temperature of the expandable beads is 80 to 150 ° C.

  According to the present invention, the polyurethane foam is foam-cured by reacting a polyurethane foam raw material containing at least a polyol, a polyisocyanate, a foaming agent and unexpanded foam beads, and the foam beads are foamed by heat generated during the reaction. In the method for producing a foamed bead-containing polyurethane foam, the polyurethane foam has a volume expansion during foaming compared to foaming at normal pressure, because the polyurethane foam is foamed and cured under pressure. As the degree decreases, it becomes difficult for heat to escape to the outside. Therefore, even if the content of expandable beads in the polyurethane foam raw material is increased, the decrease in the proportion of the urethane resin during the foaming of the polyurethane foam can be reduced, and the heat does not easily escape from the polyurethane foam. Due to the heat generated during the foam curing, both foaming of the polyurethane foam and foaming of the expandable beads can be sufficiently performed, and a good foamable bead-containing polyurethane foam can be obtained. In this invention, it is possible to use a continuous production apparatus for producing a polyurethane soft slab foam, to provide a pressurizing device in the line, and to place the continuously produced slab stock in a pressurized environment. The pressurizing device itself becomes an excessive facility. Therefore, a batch processing production system manufactured for each capacity stored in the pressurizing apparatus is preferable.

  Hereinafter, embodiments of the present invention will be described in detail. In the method for producing a polyurethane foam in the present invention, the polyurethane foam is foam-cured by reacting a polyurethane foam raw material containing at least a polyol, a polyisocyanate, a foaming agent and unexpanded expandable beads. In the method for producing a foamable bead-containing polyurethane foam in which foamable beads are foamed, the polyurethane foam is foamed and cured under pressure.

  As the polyol used in the present invention, any one or both of known ether polyols and ester polyols used for flexible polyurethane foams are used.

  Examples of ether polyols include polyhydric alcohols such as ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, butylene glycol, neopentyl glycol, glycerin, pentaerythritol, trimethylolpropane, sorbitol, and sucrose, or polyhydric alcohols thereof. The polyether polyol which added alkylene oxides, such as ethylene oxide and a propylene oxide, can be mentioned. As ester polyols, polycondensation of aliphatic carboxylic acids such as malonic acid, succinic acid and adipic acid and aromatic carboxylic acids such as phthalic acid and aliphatic glycols such as ethylene glycol, diethylene glycol and propylene glycol. The polyester polyol obtained in this way can be mentioned.

  The polyisocyanate may be aromatic, alicyclic or aliphatic, and may be a bifunctional isocyanate having two isocyanate groups in one molecule, or three in one molecule. Trifunctional or higher isocyanates having the above isocyanate groups may be used, and these may be used alone or in combination.

  For example, as the bifunctional isocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, m-phenylene diisocyanate, p-phenylene diisocyanate, 4,4'-diphenylmethane diisocyanate, 2,4'- Fragrances such as diphenylmethane diate, 2,2'-diphenylmethane diisocyanate, xylylene diisocyanate, 3,3'-dimethyl-4,4'-biphenylene diisonate, 3,3'-dimethoxy-4,4'-biphenylene diisocyanate Aliphatic ones such as cyclohexane-1,4-diisocyanate, isophorone diisocyanate, dicyclohexylmethane-4,4′-diisocyanate, methylcyclohexane diisocyanate, butane-1,4-diisocyanate Over DOO, hexamethylene diisocyanate, isopropylene diisocyanate, methylene diisocyanate, there may be mentioned aliphatic, such as lysine isocyanate.

  Examples of the tri- or higher functional isocyanate include 1-methylbenzole-2,4,6-triisocyanate, 1,3,5-trimethylbenzole-2,4,6-triisocyanate, biphenyl-2,4,4 ′. -Triisocyanate, diphenylmethane-2,4,4'-triisocyanate, methyldiphenylmethane-4,6,4'-triisocyanate, 4,4'-dimethyldiphenylmethane-2,2 ', 5,5' tetraisocyanate, triisocyanate Examples thereof include phenylmethane-4,4 ′, 4 ″ -triisocyanate, polymeric MDI, etc. In addition, urethane prepolymers can also be used. Further, the polyisocyanate used in combination is limited to one kind each. However, it may be one or more, for example, aliphatic isocyanates It may be used in combination of two of one type and an aromatic isocyanate.

  Water is used as the foaming agent. The amount of water is preferably about 3 to 5 parts by weight with respect to 100 parts by weight of polyol. When the amount is less than 3 parts by weight, the exothermic temperature at the time of the foaming reaction between the polyol and the polyisocyanate is not sufficiently increased. As a result, the foamable beads are not sufficiently foamed and a good polyurethane foam cannot be obtained. On the other hand, if it is more than 5 parts by weight, the exothermic temperature during the foaming reaction between the polyol and polyisocyanate will increase too much, and the polyurethane foam will not foam well, but will also collapse after the foaming beads once foamed. As a result, the polyurethane foam shrinks, and a good polyurethane foam cannot be obtained.

  As the expandable beads, unexpanded beads are used together with the polyol and polyisocyanate. The unfoamed expandable beads are preferable because they have a particle size smaller than that of the foamed beads after foaming, and a desired amount can be dispersed and mixed in the polyurethane raw material. In general, in the method of manufacturing a molded article of beads, unexpanded expandable beads are primarily expanded, and the expanded particles are expanded in a spherical state up to a particle size of 1 to 5 mm. It is made into a molded body by being put in and heated and fused. However, in the present invention, the primary foamed beads are mixed and dispersed in the polyurethane raw material to obtain the polyurethane foam of the present invention because the particle size of the foamable beads is too large and the desired amount cannot be mixed and dispersed. It is not preferable.

Examples of the foamable bead material include polycarbonate, methyl methacrylate, polyethylene / polypropylene copolymer, polyethylene / polystyrene copolymer, acrylic / styrene copolymer, and polyuric acid. Among these, a preferred example of the expandable bead is an expandable polystyrene bead. The expandable polystyrene beads are made by impregnating polystyrene or styrene-based copolymer plastic with a foaming agent. As the foaming agent used for the expandable polystyrene beads, pentane, butane, propane or the like, and a polymer having a number average molecular weight of 1000 to 3000 is preferable. The unfoamed expandable beads are more preferably those having a heat resistant temperature of 80 to 150 ° C. When the temperature is lower than 80 ° C., the expandable beads are once foamed and then collapse and easily contract. On the other hand, when the temperature is higher than 150 ° C., the expandable beads do not foam. The expandable beads have an unfoamed particle size of 0.8 to 1.2 mm, an expansion ratio in the expanded state of 50 to 60 times, and a density after expansion of 0.09 to 0.25 g / cm ³ . From the viewpoint of the reactivity of the polyurethane foam and the effect of increasing the hardness due to the expandable beads. Furthermore, the addition amount of unexpanded expandable beads is preferably 50 to 200 parts by weight with respect to 100 parts by weight of polyol. When the amount is less than 50 parts by weight, it is difficult to obtain the light weight and hardness increasing effect of the polyurethane foam. On the other hand, when it exceeds 200 parts by weight, the foaming balance is lost when the polyurethane foam raw material is foam-cured, making it difficult to obtain a good polyurethane foam.

  Examples of other additives include foam stabilizers and pigments. Any foam stabilizer may be used as long as it is used for a flexible polyurethane foam. Examples thereof include silicone foam stabilizers, fluorine-containing compound foam stabilizers, and known surfactants. As the pigment, those according to the required color are used.

  A catalyst is used for the reaction between the polyol and the polyisocyanate. As the catalyst, those known for flexible polyurethane foams can be used. For example, amine catalysts such as triethylamine, triethylenediamine, diethanolamine, dimethylaminomorpholine, N-ethylmorpholine, tetramethylguanidine, tin catalysts such as stannous octoate and dibutyltin dilaurate, phenylmercurypropionate or lead octenoate And metal catalysts (also referred to as organometallic catalysts). The general amount of the catalyst is about 0.01 to 2.0 parts by weight with respect to 100 parts by weight of the polyol.

  In the production of the polyurethane foam in the present invention, a polyurethane foam raw material comprising the polyol, polyisocyanate, foaming agent (water), unfoamed foam beads and catalyst, and other additives is mixed by a known method to foam. This is done by curing. At that time, the foam curing is performed under pressure. The pressurizing condition is preferably 0.15 to 0.2 MPa. When the pressure is less than 0.15 MPa, the effect of pressurization is difficult to obtain, while when it exceeds 0.2 MPa, foaming of the polyurethane foam itself is inhibited. Further, the pressurization time of 0.15 to 0.2 MPa is preferably 5 to 10 minutes after the reaction mixture is discharged from the foam molding machine. When the time is less than 5 minutes, the effect of pressurization is small. On the other hand, when the time exceeds 10 minutes, foaming of the polyurethane foam itself tends to be hindered. In addition, in the reaction molding of the polyurethane foam as the base material, the fact that the foam is under pressure at the stage where the reaction heat generation reaches the highest level gives heat for foaming the expandable beads, It is preferable to synchronize molding and foaming of foamable beads.

  When the polyurethane foam is produced, the polyurethane foam raw material (reaction mixed raw material) may be discharged from a known foam molding machine under atmospheric pressure and then placed under the pressure to be foam-cured, or It may be directly discharged under the pressurized environment to be foam-cured. In addition, the polyurethane foam raw material may be reacted by any one of the one-shot method and the prepolymer method. The one-shot method is a method in which a polyol and polyisocyanate are directly reacted in the presence of unfoamed expandable beads, a catalyst, a foaming agent (water), and other appropriate additives. On the other hand, in the prepolymer method, polyol and polyisocyanate are reacted in advance to obtain a prepolymer having an isocyanate group at the terminal, and unexpanded expandable beads, catalyst, foaming agent (water) and additives are added to the prepolymer. In the presence of the above, the polyol is reacted.

Examples of the present invention will be specifically described below together with comparative examples. Each component shown in Table 1 is blended according to the blending ratio in the same table and discharged under atmospheric pressure by the one-shot method. For the examples, immediately pressurizer (Osaka Air Machinery Co., Ltd., product number PT-200) ), And maintained in a pressurized state for 10 minutes as it is, and foamed and cured. On the other hand, in the comparative example, the applied pressure was lowered or the amount of water added as a foaming agent was changed and foamed and cured. Thus, foamable bead-containing polyurethane foams were produced. Polyols in Table 1 are polyether polyols (product number: GP3050F, functional group number f = 3, OH number = 56, Mw = 3000, manufactured by Sanyo Chemical Industries, Ltd.), and amine catalysts are N, N, N ′, N ″, N "-Pentamethyldiethylenetriamine (product number: Kao Riser No3, manufactured by Kao Corporation), metal catalyst is stannous octylate (product number: MRH110, manufactured by Johoku Chemical Industry Co., Ltd.), and foam stabilizer is silicone foam stabilizer (product number: BF2370, manufactured by Goldschmidt), expandable beads are expandable polystyrene beads (product number: SSBTX17, heat resistant temperature 120-130 ° C., particle size 0.8-1.2 mm in unexpanded state, expansion ratio 50 in expanded state) 60 times, density after foaming 0.09~0.25g / cm ^3, manufactured by Hitachi Chemical Co., Ltd.), the polyisocyanate Torirenjii Cyanate (part number: T-80, manufactured by Nippon Polyurethane Industry Co., Ltd.) is.

  Comparative Example 1 is an example in which the pressing force under pressure is reduced to 0.12 MPa. Since the pressing force is low, foaming beads are not foamed even when a polyurethane foam is molded, and good foaming is achieved. The bead-containing polyurethane foam was not obtained. Comparative Examples 2 and 3 are examples in which the amount of water as a foaming agent was changed. In Comparative Example 3 in which a large amount of water was added, the reaction exothermic temperature required for the synthesis of the polyurethane foam became too high, and the expandable beads once contracted (expanded) and contracted. In Comparative Example 2 in which the amount of water added was small, the reaction exothermic temperature required for the synthesis of the polyurethane foam was low even under the predetermined pressure condition, and the temperature for foaming the expandable beads was not reached. On the other hand, in Examples 1-5, the foaming bead containing polyurethane foam of a favorable foaming state was obtained. Furthermore, regarding Example 1, when the molding was performed without applying pressure, the internal exothermic temperature of the foamable bead-containing polyurethane foam was 110 ° C., and the foamable beads could not be sufficiently foamed. In Example 1 pressurized at 2 MPa, it was observed that the temperature was raised to 130 ° C.

Moreover, about the foamable bead containing polyurethane foam of the said Example and a comparative example, the density was measured according to JISK7222-2004, and 25% compression hardness was measured according to JISK6400-2: 2004D method. The 25% compression hardness is indicated by the compressive stress when the sample size is 30 × 50 × 50 mm and the sample is completely compressed to 25%. The measurement results are as shown in the lower part of Table 1. In the example, the 25% compression hardness was extremely high for the density as compared with the comparative example.

Claims (4)

Polyurethane foam raw material containing at least a polyol, a polyisocyanate, a foaming agent and unfoamed foam beads is reacted to foam and cure the polyurethane foam, and the foam beads containing foam are foamed by heat generated during the reaction. In the foam production method,
A method for producing a foamable bead-containing polyurethane foam, wherein the polyurethane foam is foamed and cured under pressure.   The said pressurization is 0.15-0.2 MPa, The manufacturing method of the foamable bead containing polyurethane foam of Claim 1 characterized by the above-mentioned.   The method for producing an expandable bead-containing polyurethane foam according to claim 1 or 2, wherein the content of the unexpanded expandable beads is 50 to 200 parts by weight with respect to 100 parts by weight of the polyol. The heat resistance temperature of the expandable beads is 80 to 150 ° C, The method for producing a foamable bead-containing polyurethane foam according to any one of claims 1 to 3.