Flexible polyurethane foam and its manufacturing method

Abstract

To provide a flexible polyurethane foam which prevents heat accumulation due to heat of body and hardly makes it stuffy when using in contact with body or close to body such as bedding and a mattress or a pillow, or clothing such as a pad of a brassiere.SOLUTION: In a flexible polyurethane foam obtained from a polyurethane foam composition in which polyol, isocyanate, a foaming agent, a catalyst, and an additive are blended, graphene is contained as the additive, thermal conductivity of the flexible polyurethane foam becomes large due to added graphene, heat accumulation is prevented and it is hardly to be stuffy, when used for bedding or clothing.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a flexible polyurethane foam having good thermal conductivity and a method for producing the same. [Background technology]

[0002] Flexible polyurethane foams obtained from polyurethane foam compositions containing polyols, isocyanates, blowing agents, catalysts, and additives are widely used as cushioning materials and padding materials for bedding, clothing, vehicle interiors, and the like. When used in close proximity to the body, such as in mattresses and brassiere padding, flexible polyurethane foams have the problem that heat from the body is trapped within the flexible polyurethane foam, making it prone to becoming stuffy.

[0003] In addition, there is a heat-storing soft low-resilience polyurethane foam that contains microcapsules containing a latent heat storage agent in order to prevent stuffiness (Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2001-288240 Summary of the Invention [Problem to be solved by the invention]

[0005] However, heat-storing soft low-resilience polyurethane foam containing microcapsules containing latent heat storage agents needs to be cooled down before use. If it is placed in a hot room during the daytime in summer, it takes time and effort to cool it down before use, which makes it difficult to use quickly and easily.

[0006] The present invention has been made in consideration of the above points, and an object of the present invention is to provide a flexible polyurethane foam which has good thermal conductivity and can prevent stuffiness without the need for the time and effort of cooling it before use. [Means for solving the problem]

[0007] First Aspect The flexible polyurethane foam is obtained from a flexible polyurethane foam composition containing a polyol, an isocyanate, a blowing agent, a catalyst, and additives, and is characterized in that the additive contains graphene.

[0008] Second Aspect teeth, First Aspect The graphene is blended in an amount of 5 to 60 parts by weight relative to 100 parts by weight of the polyol.

[0009] Third Aspect teeth, First Aspect or Second Aspect The flexible polyurethane foam is for clothing or bedding.

[0010] Fourth Aspect is a method for producing a flexible polyurethane foam by foaming a flexible polyurethane foam composition containing a polyol, an isocyanate, a blowing agent, a catalyst, and additives, characterized in that the additive contains graphene. [Effects of the Invention]

[0011] According to the present invention, by blending graphene into a flexible polyurethane foam composition, the resulting flexible polyurethane foam has good thermal conductivity, which prevents heat from building up and makes the foam less likely to become stuffy. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a table showing the formulations and physical property measurement results of Examples and Comparative Examples. [Figure 2] 1 is a graph showing the relationship between the thermal conductivity and the amount of graphene or expanded graphite blended in Comparative Examples 1 to 3 and Examples 1 to 6. DETAILED DESCRIPTION OF THE INVENTION

[0013] The flexible polyurethane foam of the present invention is obtained by reacting a polyol with an isocyanate from a flexible polyurethane foam composition containing a polyol, an isocyanate, a blowing agent, a catalyst, and additives.

[0014] As the polyol, polyols for flexible polyurethane foams can be used, and for example, any of polyether polyols, polyester polyols, and polyether ester polyols may be used, and one or more of these may be used.

[0015] Examples of polyether polyols include polyether polyols obtained by adding alkylene oxides such as ethylene oxide (EO) and propylene oxide (PO) to polyhydric alcohols such as ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, butylene glycol, neopentyl glycol, glycerin, pentaerythritol, trimethylolpropane, sorbitol, and sucrose.

[0016] Examples of polyester polyols include polyester polyols obtained by polycondensation of an aliphatic carboxylic acid such as malonic acid, succinic acid, or adipic acid, or an aromatic carboxylic acid such as phthalic acid, and an aliphatic glycol such as ethylene glycol, diethylene glycol, or propylene glycol. Examples of polyetherester polyols include those obtained by reacting the above-mentioned polyether polyols with polybasic acids to form polyesters, and those having both polyether and polyester segments in one molecule.

[0017] It is preferable to use one or more polyols having a hydroxyl value (OHV) of 25 to 70 mg KOH / g, a functionality of 2 to 4, and a weight average molecular weight of 2000 to 7000. Furthermore, it is preferable to use in combination a polyol having a hydroxyl value (OHV) of 50 to 840 mg KOH / g, a functionality of 2 to 4, and a weight average molecular weight of 200 to 2000.

[0018] The isocyanate may be an aliphatic or aromatic polyisocyanate having two or more isocyanate groups, a mixture thereof, or a modified polyisocyanate obtained by modifying the same. Examples of aliphatic polyisocyanates include hexamethylene diisocyanate, isophorone diisocyanate, and dicyclohexamethane diisocyanate. Examples of aromatic polyisocyanates include toluene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), naphthalene diisocyanate, xylylene diisocyanate, and polymeric polyisocyanate (crude MDI). Other prepolymers may also be used.

[0019] The isocyanate index (INDEX) is preferably 70 or more, more preferably 70 to 120. The isocyanate index is a value obtained by dividing the number of moles of isocyanate groups in the isocyanate by the total number of moles of active hydrogen groups such as hydroxyl groups in the polyol, and multiplying the result by 100, and is calculated as [NCO equivalent of isocyanate / active hydrogen equivalent × 100].

[0020] As the blowing agent, water, alternative chlorofluorocarbons, or hydrocarbons such as pentane can be used alone or in combination. In the case of water, carbon dioxide gas is generated during the reaction of polyol with isocyanate, and the carbon dioxide gas causes foaming. The amount of water used as the blowing agent is preferably 1.0 to 5.5 parts by weight per 100 parts by weight of polyol.

[0021] Known urethane catalysts can be used in combination as the catalyst. Examples include amine catalysts such as triethylamine, triethylenediamine, diethanolamine, dimethylaminomorpholine, N-ethylmorpholine, and tetramethylguanidine; tin catalysts such as stannous octoate and dibutyltin dilaurate; and metal catalysts (also called organometallic catalysts) such as phenylmercury propionate and lead octenate. Either an amine catalyst or a metal catalyst may be used alone, or both may be used in combination. The amount of the amine catalyst is preferably 0.01 to 3 parts by weight, more preferably 0.2 to 1 part by weight, per 100 parts by weight of the polyol. The amount of the metal catalyst is preferably 0 or 0.01 to 1 part by weight.

[0022] At least graphene is used as the additive. Graphene is a sheet in which carbon atoms are bonded in a hexagonal network, and its thickness is the thickness of one carbon atom. The graphene used in this example is flat (scale-like) with an average planar size (average value of the maximum diameter (maximum width) in any direction on the plane) of 0.01 to 3 mm, preferably about 0.05 to 1.5 mm. This graphene is easily dispersed in polyol, etc., does not adversely affect the foaming of the flexible polyurethane foam, and provides good thermal conductivity. The average planar size can be determined by taking a magnified photograph using a magnifying glass such as a microscope. The amount of graphene blended is preferably 5 to 60 parts by weight, more preferably 9 to 42 parts by weight, per 100 parts by weight of polyol. If the amount of graphene blended is too small, good thermal conductivity cannot be obtained, while if it is too large, it adversely affects the foaming ability and physical properties of the flexible polyurethane foam.

[0023] Other substances may be added to the additives together with graphene. Examples include a foam stabilizer, a colorant, and a flame retardant. The foam stabilizer may be a known foam stabilizer for urethane foam. Examples include a silicone-based foam stabilizer, a fluorine-containing compound-based foam stabilizer, and a known surfactant. A colorant is used depending on the application of the flexible polyurethane foam, and a flame retardant is used when the application of the flexible polyurethane foam requires flame retardancy.

[0024] A flexible polyurethane foam is produced by reacting the polyol and isocyanate in the flexible polyurethane foam composition to cause foaming. In the method for producing a flexible polyurethane foam, slab foaming is preferred. Slab foaming is a method in which a mixed flexible polyurethane foam composition (polyurethane foam raw material) is mixed and discharged onto a belt conveyor, and foamed at atmospheric pressure and room temperature.

[0025] In the flexible polyurethane foam of the present invention, graphene is blended into the flexible polyurethane foam composition, and therefore, during foaming, at least a portion of the graphene is embedded in the resin skeleton of the flexible polyurethane foam or adhered to the skeleton or the surface of the cell membranes. Therefore, even when the flexible polyurethane foam of the present invention is repeatedly compressed during use, the graphene does not fall off from the flexible polyurethane foam and the blended amount (content) of graphene does not decrease, and the flexible polyurethane foam can maintain good thermal conductivity and a sustained stuffiness prevention effect.

[0026] Unlike the present invention, when graphene is introduced into the surface or interior of a graphene-free flexible polyurethane foam in a post-process such as impregnation, the graphene is simply attached to the resin skeleton of the flexible polyurethane foam or the membrane surfaces of the cells. Therefore, the graphene gradually falls off from the flexible polyurethane foam during use of the flexible polyurethane foam, resulting in a decrease in the amount of graphene.

[0027] The flexible polyurethane foam of the present invention is particularly suitable for use in items worn on the body or placed nearby. Examples of suitable applications include bedding (pillows, mattresses), floor cushions, seat pads, clothing pads (e.g., bra pads), and vehicle seat pads (cushions). Bedding and clothing are particularly suitable.

[0028] In order to obtain a stuffiness prevention effect, the flexible polyurethane foam of the present invention preferably has a thermal conductivity (JIS A1412-2) of 0.0380 W / mK or more, and to obtain an even better stuffiness prevention effect, it is preferably 0.0400 W / mK or more.

[0029] When the flexible polyurethane foam of the present invention is used for bedding such as mattresses and pillows, or cushions, it is compressed by approximately 3 to 80% under the body weight during use. Furthermore, for clothing such as bra pads, the flexible polyurethane foam is used after being compressed by approximately 3 to 90% by heat pressing (thermal compression). Therefore, the flexible polyurethane foam of the present invention preferably has a high thermal conductivity when compressed. Specifically, the thermal conductivity when compressed by 50% is preferably higher than the thermal conductivity when uncompressed. It is effective and more preferable that the thermal conductivity when compressed by 50% is at least 0.0006 W / mK higher than the thermal conductivity when uncompressed. The shaping of flexible polyurethane foam by heat pressing can be performed by compressing a flexible polyurethane foam of a predetermined thickness into a predetermined shape using a hot plate or mold heated to approximately 150 to 250°C, followed by cooling. The flexible polyurethane foam shaped by heat pressing is then covered with a surface material such as woven fabric before use.

[0030] Furthermore, when the flexible polyurethane foam of the present invention is used for clothing or bedding, it has a 25% hardness (JISK6400-2) of 15 to 260 N, more preferably 15 to 100 N, a rebound resilience (JISK6400-3) of 2 to 40%, an air permeability (JISK6400-7) of 40 to 250 L / min, and a density of 18 to 70 kg / m 3 If the 25% hardness is within the above range, the flexible polyurethane foam can be compressed by about 3 to 80%, and the thermal conductivity during compression can be improved.

[0031] The 25% hardness and impact resilience of flexible polyurethane foam can be adjusted by the type and amount of polyol added and by adjusting the index, the breathability can be adjusted by the type and amount of polyol and isocyanate added and by adjusting the index, and the density can be adjusted by the amount of water added and the amount of blowing agent. In particular, to enhance the stuffiness prevention effect, the breathability is preferably 50 L / min or more, more preferably 100 L / min or more.

[0032] In order to achieve a comprehensive effect of preventing stuffiness, it is preferable that the airflow rate is at least 50 L / min or more and that the thermal conductivity when uncompressed is 0.0380 W / mK or more, but more preferably the airflow rate is 100 L / min or more and that the thermal conductivity when uncompressed is 0.0400 W / mK or more, and especially 0.0420 W / mK or more. [Example]

[0033] The following raw materials were mixed in the formulation shown in FIG. 1 and reacted and foamed to produce flexible polyurethane foams of each example and comparative example. Polyol A: Polyether polyol, Mw 1000, functionality 3, hydroxyl value 160 mg KOH / g, obtained by addition polymerization of propylene oxide using glycerin as an initiator. Polyol B: Polyether polyol, Mw 3000, functionality 3, hydroxyl value 56 mg KOH / g, product number GP3050NS, manufactured by Sanyo Chemical Industries, Ltd. Polyol C: Polymer polyol (60% by mass of polyether polyol obtained by addition polymerization of propylene oxide to glycerin, graft-polymerized with 40% by mass of a mixture of styrene and acrylonitrile in a mass ratio of 8:2), Mw 5000, solid content 40% by mass, hydroxyl value 33 (mgKOH / g), number of functional groups for hydroxyl groups 3 Amine catalyst A: Part number: NE300, manufactured by Air Products Co., Ltd. Amine catalyst B: Part number: 33LV, manufactured by Air Products Co., Ltd. Foam stabilizer: Part number: NIAX silicone L595, manufactured by Momentive Graphene: Part number HC-95, manufactured by Paterson Expanded graphite: SYZR 502FP, manufactured by Sanyo Trading Co., Ltd. Metal catalyst: Stannous octoate, product number MRH110, manufactured by Johoku Chemical Industry Co., Ltd. MDI: Crude MDI, product number: Luplanate M5S, manufactured by BASF TDI: A mixture of 80% 2,4-TDI and 20% 2,6-TDI, product number: T-80, manufactured by Nippon Polyurethane Co., Ltd.

[0034] Examples 1 to 7 and Comparative Examples 1 to 3 are examples in which MDI was used as the isocyanate, and Comparative Example 1 is an example in which neither graphene nor expanded graphite was included, Comparative Example 2 is an example in which expanded graphite was included but not graphene, and Comparative Example 3 is an example in which the isocyanate index was higher than that of Comparative Example 1. Furthermore, Example 8 and Comparative Example 4 are examples in which TDI was used as the isocyanate, and Comparative Example 4 is an example in which neither graphene nor expanded graphite was included.

[0035] The density (JISK7222), ILD25% hardness (JISK6400-2), rebound resilience (JISK6400-3), and air permeability (JISK6400-7 Method A) of the obtained Examples 1 to 8 and Comparative Examples 1 to 4 were measured. Thermal conductivity (JISA1412-2) was measured in an uncompressed state and in a 50% compressed state. The measurement results are shown in Figure 1. The "Difference" at the bottom of Figure 1 is the difference between (thermal conductivity in a 50% compressed state) and (thermal conductivity in an uncompressed state).

[0036] In the case of Comparative Example 1 and Examples 1 to 6 in which the isocyanate is MDI, the thermal conductivity in an uncompressed state is 0.0393 W / mK in Comparative Example 1 in which the graphene content is 0 parts by weight, 0.0402 W / mK in Example 1 in which the graphene content is 5 parts by weight, 0.0424 W / mK in Example 2 in which the graphene content is 10 parts by weight, 0.0446 W / mK in Example 3 in which the graphene content is 15 parts by weight, 0.0457 W / mK in Example 4 in which the graphene content is 20 parts by weight, 0.0538 W / mK in Example 5 in which the graphene content is 40 parts by weight, and 0.0568 W / mK in Example 6 in which the graphene content is 60 parts by weight, and the thermal conductivity can be increased by increasing the graphene content.

[0037] In Comparative Example 2, which used expanded graphite instead of graphene, the thermal conductivity increased to 0.0414 W / mK at a blend amount of 15 parts by weight, indicating that adding expanded graphite also increases thermal conductivity. However, the thermal conductivity improvement effect, which is the efficiency relative to the amount added, was inferior to that of Example 3, which added the same amount, and Example 2, which added 10 parts by weight.

[0038] Comparative Example 3, which has a higher isocyanate index than Comparative Example 1, has a lower thermal conductivity of 0.0348 W / mK. On the other hand, Example 7, which has the same isocyanate index as Comparative Example 1 and contains 15 parts by weight of graphene, has a thermal conductivity of 0.0383 W / mK, which is higher (better thermal conductivity) than Comparative Example 3, which does not contain graphene.

[0039] 2 is a graph showing the relationship between the thermal conductivity (uncompressed state) and the amount of graphene blended in Comparative Example 1 and Examples 1 to 6. Note that if the amount of graphene and expanded graphite blended is too large, the flexible polyurethane foam cannot be foamed well.

[0040] 1, the thermal conductivity measurement results for the 50% compressed state showed that in Comparative Example 1, where the graphene content was 0 parts by weight, the thermal conductivity was lower than the thermal conductivity in the uncompressed state, but in Examples 1 to 6, where the graphene content was 5 parts by weight or more, the thermal conductivity was higher than the thermal conductivity in the uncompressed state, indicating that compression can increase the thermal conductivity (improve thermal conductivity).In Comparative Example 2, which used expanded graphite, the thermal conductivity increased from 0.0414 W / mK in the uncompressed state to 0.0417 W / mK in the compressed state, although this increase was slight.

[0041] On the other hand, in the case of Comparative Example 4 and Example 8 in which the isocyanate was TDI, the thermal conductivity in the uncompressed state was 0.0372 W / mK in Comparative Example 4 in which the amount of graphene blended was 0 part by weight, as shown in FIG. 1, whereas it was 0.0403 W / mK in Example 8 in which the amount of graphene blended was 15 parts by weight, and thus the blending of graphene can increase the thermal conductivity (improve the thermal conductivity).

[0042] As described above, the flexible polyurethane foam of the present invention has good thermal conductivity, and when used in bedding such as mattresses and pillows, or in clothing such as bra pads, the good thermoelectric conductivity of the flexible polyurethane foam prevents heat from the body from being trapped inside the flexible polyurethane foam and releases it to the outside, making it less likely to become stuffy.

Claims

[Claim 1] A flexible polyurethane foam comprising graphene, the flexible polyurethane foam having a thermal conductivity at 50% compression that is 0.0006 W / mK or more higher than the thermal conductivity at uncompressed.

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