JP4993967B2 - Flexible polyurethane foam - Google Patents

Description

  The present invention relates to a flexible polyurethane foam capable of suppressing discoloration due to NOx gas and ultraviolet rays, and more particularly to a flexible polyurethane foam having little discoloration even when used for a long period of time.

  A flexible polyurethane foam obtained by foaming and curing a foaming raw material containing a polyol, a polyisocyanate, a foaming agent and a catalyst has excellent lightness, cushioning and durability. Widely used for brassiere pads and shoulder pads. Usually, the polyoxyalkylene polyol, which is a raw material for the flexible polyurethane foam, is obtained by adding an antioxidant during the synthesis and causing a polymerization reaction, so that the polyol itself contains an antioxidant.

  BHT (butylated hydroxytoluene) is used as an antioxidant during the synthesis of such polyoxyalkylene polyol, and BHT remains in the flexible polyurethane foam after foaming. As a result, BHT remaining in the foamed flexible polyurethane foam reacts with nitrogen oxides (NOx) in the atmosphere, and the soft polyurethane foam itself turns yellow, and the fabric comes into contact with the flexible polyurethane foam. There is a problem of transfer discoloration that causes discoloration. Furthermore, the conventional flexible polyurethane foam also has a problem of yellowing due to ultraviolet rays. Such discoloration of the flexible polyurethane foam is not preferable due to poor appearance in daily use such as clothing, medical care, and other miscellaneous goods.

  Conventionally, in order to suppress discoloration of the flexible polyurethane foam, a polyol mainly composed of polypropylene glycol is used, an ultraviolet absorber, a NOx-proofing agent is added, and a highly volatile antioxidant such as BHT is used. It has been done to reduce or not use. As another method, an aliphatic polyisocyanate effective for yellowing resistance is also used.

  However, discoloration or migration of flexible polyurethane foam itself due to NOx or ultraviolet rays, even if UV absorbers or NOx-proofing agents are added, or the amount of highly volatile antioxidants such as BHT is limited. Discoloration could not be sufficiently suppressed. Although the effect of suppressing discoloration can be obtained by using an aliphatic polyisocyanate, the aliphatic polyisocyanate itself is expensive, so there is a problem of increasing the cost of the flexible polyurethane foam, and the aliphatic polyisocyanate has a low reactivity. Therefore, there is a problem inferior in productivity of flexible polyurethane foam.

JP-A-11-060721 Japanese Patent Laid-Open No. 11-060722 JP 11-323126 A Japanese Patent Publication No. 52-30437

  The present invention has been made in view of the above points, and can suppress long-term discoloration and transfer discoloration of the flexible polyurethane foam due to NOx, ultraviolet rays, etc., and is inexpensive and has good productivity. The purpose is to provide a form.

The present invention relates to a flexible polyurethane foam obtained by foaming and curing a foaming raw material containing a polyol, a polyisocyanate, a foaming agent, a catalyst and an antioxidant , and 1 to 30 parts by weight of (meth) in 100 parts by weight of the polyol. An acrylic polyol is included.

  According to the present invention, when the (meth) acrylic polyol is contained in the polyol, it is possible to suppress long-term discoloration and discoloration of the flexible polyurethane foam itself due to NOx, ultraviolet rays, and the like. Therefore, it is not always necessary to use an expensive and low-reactive aliphatic polyisocyanate in order to suppress the properties, and a flexible polyurethane foam having good productivity and low cost can be obtained.

  As the polyol in the present invention, ether type polyol or ester type polyol and (meth) acrylic polyol which are known for flexible polyurethane foams can be used. Particularly in the present invention, (meth) acrylic polyol is essential as a polyol component in the foaming raw material.

  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 also be used.

  The (meth) acrylic polyol has a hydroxyl value (OHV) of preferably 13 to 200 mgKOH / g, more preferably 28 to 88 mgKOH / g. When the hydroxyl value is less than 13 mgKOH / g, the resulting flexible polyurethane foam becomes too soft, resulting in difficulty in shape retention. On the other hand, when the hydroxyl value exceeds 200 mgKOH / g, the resulting flexible polyurethane foam becomes hard.

  The (meth) acrylic polyol is obtained by copolymerization of a hydroxyl group-containing (meth) acrylate and another polymerizable monomer. The amount of the hydroxyl group-containing (meth) acrylate is determined so that the hydroxyl value of the (meth) acryl polyol becomes the above value, but usually 1 to 30 parts by weight is preferable with respect to 100 parts by weight of the raw material monomer. In addition, a monomer is used individually by 1 type or in combination of 2 or more types.

  Examples of the hydroxyl group-containing (meth) acrylate include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-chloro-2-hydroxypropyl (meth) acrylate, and diethylene glycol mono (meth) acrylate. Can do.

  Examples of the other polymerizable monomers include alkyl (meth) acrylates, other (meth) acrylates, styrene monomers, and other vinyl monomers.

  Alkyl (meth) acrylates include methyl (meth) acrylate, ethyl (meth) acrylate, isopropyl (meth) acrylate, butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, lauryl (meth) acrylate, and stearyl (meth). An acrylate etc. can be mentioned.

  Examples of other (meth) acrylates include cyclohexyl (meth) acrylate, diethylene glycol mono (meth) acrylate, methoxyethyl (meth) acrylate, ethoxyethyl (meth) acrylate, and glycidyl (meth) acrylate.

  Examples of the styrene monomer include alkyl styrene, halogenated styrene, nitroso styrene, acetyl styrene, and methoxy styrene. Examples of the alkyl styrene include styrene, methyl styrene, dimethyl styrene, trimethyl styrene, ethyl styrene, diethyl styrene, triethyl styrene, propyl styrene, butyl styrene, and hexyl styrene. Examples of the halogenated styrene include fluorostyrene, chlorostyrene, bromostyrene, dibromostyrene, and iodostyrene.

  Examples of the other vinyl monomers include vinyl pyridine, vinyl pyrrolidone, vinyl carbazole, divinyl benzene, vinyl acetate, acrylonitrile and the like, conjugated diene monomers such as butadiene, isoprene and chloroprene, and vinyl halides such as vinyl chloride and vinyl bromide. And vinylidene halides such as vinylidene chloride.

  The (meth) acrylic polyol used in the present invention preferably has a weight average molecular weight of 3000 to 10,000. When the weight average molecular weight is less than 3000, the resulting flexible polyurethane foam becomes hard and brittle, whereas when it exceeds 10,000, the obtained flexible polyurethane foam becomes soft and mechanical strength is lowered. Moreover, the amount of (meth) acrylic polyol contained in the foaming raw material is preferably 1 to 30 parts by weight in 100 parts by weight of polyol. When the amount of the (meth) acrylic polyol is less than 1 part by weight in 100 parts by weight of the polyol, it is difficult to obtain the effect of suppressing discoloration. On the other hand, when it exceeds 30 parts by weight, the mechanical properties are deteriorated.

  As polyisocyanate, aromatic polyisocyanate, aliphatic isocyanate, and alicyclic polyisocyanate having two or more isocyanate groups can be used. The aromatic polyisocyanate refers to a polyisocyanate having an aromatic ring, and examples thereof include toluene diisocyanate (TDI), diphenylmethane diisocyanate, naphthalene diisocyanate, xylylene diisocyanate, and polymeric isocyanate (crude MDI). On the other hand, the aliphatic polyisocyanate refers to a polyisocyanate having an isocyanate group attached to a linear hydrocarbon chain, and examples thereof include tetramethylene diisocyanate, pentamethylene diisocyanate, hexamethylene diisocyanate, and lysine diisocyanate. The alicyclic polyisocyanate refers to a polyisocyanate having an isocyanate group on a cyclic hydrocarbon chain, and examples thereof include isophorone diisocyanate (IPDI) and dicyclohexamethane diisocyanate. Other prepolymers can also be used. In addition, the aromatic polyisocyanate, the aliphatic polyisocyanate, and the alicyclic polyisocyanate are not limited to one type, and may be one or more types. For example, two types of aromatic polyisocyanate and one type of alicyclic polyisocyanate may be used in combination. In particular, the polyisocyanate of the present invention is preferably an aromatic polyisocyanate that is inexpensive and has good reactivity.

  As the foaming agent, known ones for flexible polyurethane foams are used. In particular, water is suitable as the foaming agent. The amount of water as a blowing agent is preferably about 0.5 to 5.0 parts by weight with respect to 100 parts by weight of polyol.

  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, stannous octoate, etc. And tin catalysts such as dibutyltin dilaurate and metal catalysts (also referred to as organometallic catalysts) such as phenylmercury propionate or lead octenoate. In particular, it is preferable to use an amine catalyst alone. By using an amine catalyst alone, yellowing can be more effectively suppressed. 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.

  Antioxidants are added to effectively suppress discoloration and transfer discoloration of the flexible polyurethane foam itself. Examples of the antioxidant include phenolic, amine-based, sulfur-based and phosphorus-based agents. The antioxidant added here is different from the BHT used in the synthesis of the polyoxyalkylene polyol described in the background art, and is particularly preferably phosphorus. The antioxidant is not limited to one type, and a plurality of types may be used. The addition amount of the antioxidant is preferably 0.5 to 15 parts by weight, more preferably 0.5 to 10 parts by weight with respect to 100 parts by weight of the polyol. If the addition amount of the antioxidant is less than the above range, discoloration and transfer discoloration of the flexible polyurethane foam itself cannot be effectively suppressed. On the other hand, if it is more than the above range, poor foaming tends to occur. .

  In addition, the foaming raw material includes additives as appropriate. Examples of the additive include a foam stabilizer, a pigment, a crosslinking agent, and an ultraviolet absorber.

  Any foam stabilizer may be used as long as it is used for flexible polyurethane foams, and 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. In particular, a white pigment is preferable as the pigment in the foam of the clothing pad material.

  The cross-linking agent is used to make the flexible polyurethane foam have a hardness according to the application. As the crosslinking agent, known ones can be used, for example, ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, 1,3-butanediol, 1,4-butanediol, glycerin, trimethylolpropane, pentane. Polyhydric alcohols such as erythritol and sorbitol, amines such as ethylenediamine, diethylenetriamine, hexamethylenediamine, hydrazine, diethyltoluenediamine, and diethylenetriamine, amino alcohols such as diethanolamine and triethanolamine, and these active hydrogen compounds as ethylene oxide And a compound to which polypropylene oxide or the like is added.

  The ultraviolet absorber is used for more effectively suppressing discoloration of the foam due to ultraviolet rays. As the ultraviolet absorber, 2- (2H-benzotriazol-2-yl) -p-cresol, 2- (2′-hydroxy-3 ′, 5′-di-t-amylphenyl), which is a benzotriazole type, is used. Benzotriazole, 2- (2-hydroxy-5- (1,1,3,3-tetraethylbutyl) phenyl) benzotriazole, 2,2′-methylenebis (6- (2Hbenzotriazol-2-yl) -4- 1,1,3,3- (tetramethylbutyl) phenol), 2- (2′-hydroxy-5′-methylphenyl) benzotriazole, 2- [5-chloro (2H) -benzotriazol-2-yl] 2-hydroxy-4-methoxybenzophenone, 5-benzoyl-4-hydride, such as -4-methyl-6- (t-butyl) phenol, which is benzophenone-based 2,4-t-butylphenyl-3,5-di-t which is a benzoate type such as xyl-2-methoxybenzene sulfonic acid 2-hydroxy-4-n-octyloxybenzophenone, 2,4-dihydroxybenzophenone, etc. Examples include cyanoacrylate-based ethyl-2-cyano-3,3-diphenyl acrylate, 2-ethylhexyl-2-cyano-3,3-diphenyl acrylate, and the like such as -butyl-4-hydroxybenzoate. A preferable amount of the ultraviolet absorber is 0.5 to 10 parts by weight with respect to 100 parts by weight of the polyol.

  The flexible polyurethane foam in the present invention can be produced by a one-shot method in which a polyol and a polyisocyanate are directly reacted in the presence of a foaming agent, a catalyst, or the like, or a prepolymer having an isocyanate group at the terminal by reacting in advance with a polyol and a polyisocyanate. The prepolymer can be obtained by any of the prepolymer methods in which a polyol is reacted with this prepolymer in the presence of a foaming agent, a catalyst or the like. Moreover, as a flexible polyurethane foam of this invention, a slab polyurethane foam is preferable. The slab polyurethane foam is a continuous foaming material (reaction mixture material) that is mixed and stirred onto a belt conveyor. While the belt conveyor moves, the material naturally foams and cures at room temperature and atmospheric pressure. Manufactured. Then, after hardening (curing) in a drying furnace, it is cut into a predetermined shape.

  Examples of the present invention will be specifically described below together with comparative examples. Each component shown in Table 1 was blended according to the blending ratio in the same table, and flexible polyurethane foams of Examples and Comparative Examples were produced by the one-shot method and the method for producing slab polyurethane foam.

  The polyols in Tables 1 and 2 are product name: GP3050 (polyether polyol, OHV = 56.1), manufactured by Sanyo Chemical Industries, Ltd., and acrylic polyol 1, product name: UT-1001 (poly 2-ethylhexyl acrylate polyol, Mw = 3500, OHV = 58), manufactured by Soken Chemical Co., Ltd., acrylic polyol 2, product name: UT-3001 (poly 2-ethylhexyl acrylate polyol, Mw = 3800, OHV = 76), manufactured by Soken Chemical Co., Ltd., acrylic polyol 3 Product name: UMB-2005 (poly 2-ethyl acrylate polyol, Mw = 3000, OHV = 88), manufactured by Soken Chemical Co., Ltd., acrylic polyol 4, product name: 1-A (poly 2-ethylhexyl acrylate polyol, Mw 10000, OHV) = 28) Soken Chemical Co., Ltd., catalyst is product name: DABCO33LV (triethylenediamine 33% propylene glycol solution, OHV = 974), Air Products Co., Ltd., antioxidant is tris (2-ethylhexyl) phosphite, foam stabilizer is product name: SZ-1136 (polyalkylene-modified silicone), manufactured by Toray Dow Corning Co., Ltd., UV absorber is 2- (2H-benzotriazol-2-yl) -6-dodecyl-4-methylphenol, polyisocyanate is product name: coronate T-80 (toluene diisocyanate, NCO% = 48.2), manufactured by Nippon Polyurethane Industry Co., Ltd. In Comparative Example 4, the cream time and rise time during foaming were long, and foaming was not good. In other Comparative Examples and Examples, the foamed state was good.

  For the flexible polyurethane foams of Examples and Comparative Examples thus obtained, the density (according to JIS K 7222: 1999), hardness (according to JIS K 6400-2: 2004 D method), and elongation (JIS K 6400-). 5: 2004 conformity), tensile strength (conforms to JIS K 6400-5: 2004), and tear strength (conforms to JIS K 6400-5: 2004). Also, 30 mm square test pieces were collected from the flexible polyurethane foams of the comparative example and the example, and two kinds of discoloration tests were performed. In the first discoloration test, after leaving the test piece for 168 hours in a humid-heat furnace at a temperature of 50 ° C. and a humidity of 95 RH%, the initial YI value of the test piece was measured with a YI value measuring device (COLOUR COMPUTER SM-4, manufactured by Suga Test Instruments). It was measured. Put this test piece into a glass bottle, fill the glass bottle with NOx gas, leave it for 3 hours, take out the test piece, and measure the YI value after processing with a YI value measuring instrument (COLOUR COMPUTER SM-4, manufactured by Suga Test Instruments). did. The ΔYI value was calculated by subtracting the initial YI value from the post-processing YI value obtained in this way. The measurement results are as shown in the lower part of Tables 1 and 2. In the second discoloration test, instead of the treatment of leaving the test piece in a wet heat furnace at a temperature of 50 ° C. and a humidity of 95 RH% in the first discoloration test for 168 hours, the test was left in a humid heat furnace at a temperature of 80 ° C. and a humidity of 95 RH% for 10 hours. For other treatments, the YI value was measured and the ΔYI value was calculated in the same manner as in the first discoloration test.

From the ΔYI value, it can be seen that the flexible polyurethane foams of the examples are hardly discolored even when used for a long time. On the other hand, Comparative Example 1 containing no acrylic polyol and Comparative Examples 2 to 3 in which the blending amount of the acrylic polyol was less than the range of the present invention both had a large ΔYI value and were easily discolored. On the other hand, in Comparative Example 4 in which the amount of the acrylic polyol is larger than the range of the present invention, a large amount of the acrylic polyol makes it difficult to balance the foam and curing and good foaming is not performed, but a foam is obtained, but the physical properties are inferior. It was not suitable for practical use. Further, Comparative Example 5 containing neither an ultraviolet absorber nor an antioxidant had a large ΔYI value and was likely to cause discoloration. In addition, the flexible polyurethane foams of the examples are those in which density, hardness, elongation, tensile strength, tear strength are almost the same as those known for conventional flexible polyurethane foams, and the strength etc. of conventional products Was not inferior.

Claims (2)

In a flexible polyurethane foam obtained by foaming and curing a foam raw material containing a polyol, polyisocyanate, foaming agent, catalyst and antioxidant,
1 to 30 parts by weight of (meth) acrylic polyol is contained in 100 parts by weight of the polyol. The flexible polyurethane foam according to claim 1, wherein the foaming raw material contains an ultraviolet absorber .