JP6599255B2 - Method for producing urethane foam for elastic elastic member - Google Patents

Description

  The present invention relates to a method for producing urethane foam for elastic elastic members.

Conventionally, the disposable diaper 10 shown in FIG. 1 is provided with elastic elastic members 12 and 16 at the peripheral edge 11 of the leg opening and the peripheral edge 15 of the waist opening to form an elastic gather (please). As the elastic elastic member, there is one in which urethane foam is formed into a tape shape having a thickness of about 2 mm.
Urethane foam is produced by reacting a polyol and an isocyanate in the presence of a foaming agent, a catalyst, and an antioxidant. Moreover, since the urethane foam for elastic elastic members has good elongation and tensile strength at break, an ester urethane foam using a polyester polyol as a polyol is used.

  In addition, white diapers are preferred for giving a hygienic impression, but urethane foam is easily colored with light or nitrogen oxide gas, so it is colored in pink or blue in advance so that the color change is difficult to understand. It has been. However, even if the conventional urethane foam is colored pink or blue, discoloration may be noticeable depending on the storage state.

  In addition, since tertiary urethane is used as a catalyst for the foaming of ester-based urethane foam, the amine has a characteristic odor after foaming or urine provided in a paper diaper during storage of the paper diaper. There is a problem of discoloring the detection sign. The urine detection sign is composed of an indicator that changes color depending on pH or the like.

JP-A-9-75394 Japanese Patent Laid-Open No. 10-36543

  The present invention has been made in view of the above points, and has an elongation at break, tensile strength, good discoloration resistance against nitrogen oxide gas, no smell, and elastic expansion and contraction that does not discolor the urine detection sign of a paper diaper. The purpose is to manufacture urethane foam for parts.

The invention according to claim 1, a polyol and an isocyanate, blowing agent, a catalyst, in the production method of the resilient and elastic members for urethane foam is reacted in the presence of an antioxidant, the only polyester polyol used as the polyol, the isocyanate aromatic The weight ratio of aromatic isocyanate: alicyclic isocyanate is 99-80: 1-20, and only the reactive amine catalyst is used as the catalyst , and the hinder is used as the antioxidant. A dophenol-based and / or reactive phosphite-based antioxidant is used. The “and / or” means “and” or “or”.

The invention of claim 2 is characterized in that, in claim 1 , the urethane foam for elastic elastic member is used for a paper diaper.

In the present invention, since only the polyester polyol is used as the polyol, the elongation and tensile strength at break of the urethane foam can be improved, and a urethane foam suitable for an elastic elastic member can be obtained.
Further, in the present invention, since the isocyanate contains an aromatic isocyanate, the reactivity is excellent, the foamed body becomes good, and the elongation and tensile strength at the time of breaking of the urethane foam are prevented from being damaged by the defective foamed body. be able to.

  Moreover, in this invention, since only a reactive amine catalyst is used as a catalyst and a non-reactive amine catalyst is not used, isocyanate and a reactive amine catalyst react at the time of foaming of urethane foam. For this reason, the amine catalyst does not remain in the foamed urethane foam in a free state, thereby eliminating the odor due to the amine and preventing the detection sign of the paper diaper from being accidentally discolored by the free amine catalyst remaining in the urethane foam. be able to. Furthermore, in the present invention, only the reactive amine catalyst is used as the catalyst, and the metal catalyst that easily causes yellowing of the urethane foam is not used. This can also improve the yellowing resistance of the urethane foam.

Moreover, in this invention, since at least one of a hindered phenol type | system | group and a reactive phosphite ester type | system | group antioxidant is used as antioxidant, discoloration by nitrogen oxide gas can be suppressed.
Furthermore, in the present invention, if the isocyanate is a combination of an aromatic isocyanate and an alicyclic isocyanate, the yellowing resistance of the urethane foam can be further improved.

It is a figure which shows the expansion | deployment state of a paper diaper.

The present invention will be described below. The present invention is a method for producing a urethane foam suitable for the elastic elastic members 12 and 16 of the paper diaper 10 shown in FIG. 1, and reacting a polyol and an isocyanate in the presence of a foaming agent, a catalyst and an antioxidant. Manufactures urethane foam for elastic elastic members.

  As the polyol used in the present invention, only polyester polyol is used. Polyester polyols for urethane foam can be used as the polyester polyol. For example, aliphatic carboxylic acids such as malonic acid, succinic acid, and adipic acid, and aromatic carboxylic acids such as phthalic acid, ethylene glycol, diethylene glycol, propylene Mention may be made of polyester polyols obtained by polycondensation from aliphatic glycols such as glycols. The polyester polyol used in the present invention is more preferably a polyester polyol having a molecular weight (number average molecular weight) of 2000 to 5000 for foaming stability and physical property balance.

The isocyanate used in the present invention is essentially an aromatic isocyanate and may contain at least one of aliphatic and alicyclic isocyanates together with the aromatic isocyanate. Examples of the aromatic isocyanate include tolylene diisocyanate (TDI), 4,4′-diphenylmethane diisocyanate (MDI), polymeric MDI (crude MDI), xylylene diisocyanate, 1,5-naphthalene diisocyanate, and the like. Tolylene diisocyanate (TDI) has isomers of 2,4′-tolylene diisocyanate (2,4′-TDI) and 2,6′-tolylene diisocyanate (2,6′-TDI). , 4'-TDI / 2,6'-TDI ratio is 80/20 and T-4 is 2,4'-TDI / 2,6'-TDI ratio is 65/35. . Examples of the aliphatic isocyanate include hexamethylene diisocyanate, isopropylene diisocyanate, and methylene diisocyanate. Examples of the alicyclic isocyanate include silohexane-1,4-diisocyanate, isophorone diisocyanate (IPDI), hydrogenated MDI, and the like.
In the present invention, the combined use of an aromatic isocyanate and an alicyclic isocyanate is more preferable because the discoloration resistance can be further improved. When the aromatic isocyanate and the alicyclic isocyanate are used in combination, the weight ratio of aromatic isocyanate: alicyclic isocyanate is preferably 99 to 80: 1 to 20.

  The isocyanate index is preferably 80 to 120. When the isocyanate index is less than 80, a good foam cannot be formed. On the other hand, if the isocyanate index exceeds 120, the foam becomes too hard or a good foam cannot be obtained. The isocyanate index is a value obtained by multiplying the value obtained by dividing the number of moles of isocyanate groups in the polyisocyanate by the total number of moles of active hydrogen groups such as hydroxyl groups of polyol and water as a blowing agent, and [the NCO equivalent of polyisocyanate] / Active hydrogen equivalent × 100].

  As the blowing agent used in the present invention, water 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 between the polyol and the isocyanate, and foaming is performed by the carbon dioxide gas. The amount of the blowing agent is appropriately determined, but in the case of water, about 3 to 5.5 parts by weight is preferable with respect to 100 parts by weight of the polyol.

  As the catalyst used in the present invention, only a reactive amine catalyst is used, and a non-reactive amine catalyst and a metal catalyst are not used. The reactive amine catalyst has a functional group that reacts with isocyanate, and is preferably an amine compound having at least one OH group. Examples of amine compounds having at least one OH group include monoethanolamine, diethanolamine, triethanolamine, dimethylethanolamine (DMEA), N, N, N′-trimethylaminoethylethanolamine, N, N-dimethylaminoethoxy. Examples thereof include ethanol, N, N-dimethylaminohexanol, N, N-dimethylaminoethoxyhexanol and the like. Two or more reactive amine catalysts may be used. The amount of the catalyst is preferably about 0.1 to 2 parts by weight with respect to 100 parts by weight of the polyol.

As the antioxidant used in the present invention, at least one of a hindered phenol type and a reactive phosphite type antioxidant is used.
Examples of the hindered phenol antioxidant used in the present invention include 4-methyl-2,6-di-tert-butylphenol (BHT), triethylene glycol-bis [3- (3-t-butyl-5 -Methyl-4-hydroxyphenyl) propionate] (trade name; Irganox 245, manufactured by BASF Japan Ltd.), 1,6-hexanediol-bis [3- (3,5-di-t-butyl-4-hydroxyphenyl) ) Propionate] (trade name; Itsuganox 259, manufactured by BASF Japan), pentaerythritol tetrakis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate] (trade name; Irganox 1010, BASF Japan) ), Octadecyl-3- (3,5-di-t-butyl-4-hydroxypheny) ) Propionate (trade name; Irganox 1076, manufactured by BASF Japan Ltd.), benzenepropanoic acid, 3,5-bis (1,1-dimethylethyl) -4-hydroxy-, C7-C9 side chain alkyl ester (trade name; Irganox 1135, manufactured by BASF Japan), 2,4-bis [(octylthio) methyl] -o-cresol (trade name; Irganox 1520L, manufactured by BASF Japan), 2,4-bis [(dodecylthio) methyl] -6-methylphenol (trade name; Irganox 1726, manufactured by BASF Japan), 3,9-bis [1,1-dimethyl-2-[(3-t-butyl-4-hydroxy-5-methylphenyl) Propionyloxy] ethyl] 2,4,8,10-tetraoxaspiro [5,5] undecane (trade name; Adekas Breakfast AO 80, manufactured by Adeka Corporation), and the like. Among them, in the present invention, octadecyl-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate (trade name; Irganox 1076, manufactured by BASF Japan), benzenepropanoic acid, 3,5- Bis (1,1-dimethylethyl) -4-hydroxy-, C7-C9 side chain alkyl ester (trade name; Irganox 1135, manufactured by BASF Japan Ltd.), pentaerythritol tetrakis [3- (3,5-di-t -Butyl-4-hydroxyphenyl) propionate] (trade name; Irganox 1010, manufactured by BASF Japan Ltd.) is more preferable.

The reactive phosphite-based antioxidant used in the present invention is a phosphite-based antioxidant having an active group that reacts with isocyanate, such as tris (dipropylene glycol) phosphite, poly (dipropylene). Glycol) phenyl phosphite (trade name: Weston DHOP, manufactured by Addivant)
Is mentioned.

  The amount of the antioxidant is preferably about 0.2 to 3 parts by weight with respect to 100 parts by weight of the polyol. If the amount of the antioxidant is too small, the effect of yellowing resistance is reduced, and if it is too much, foaming failure tends to occur.

In addition, additives such as a foam stabilizer, an ultraviolet absorber, and a light stabilizer can be blended.
A foaming state can be made favorable by adding a foam stabilizer. Any foam stabilizer may be used as long as it is used for urethane foam, and examples thereof include silicone foam stabilizers, fluorine-containing compound foam stabilizers, and surfactants.

By adding an ultraviolet absorber, yellowing with respect to light can be more effectively suppressed. As the ultraviolet absorber, for example, a benzotriazole-based, benzophenone-based, benzoate-based, or cyanoacrylate-based ultraviolet absorber can be used.
Examples of the benzotriazole ultraviolet absorber include 2- (2H-benzotriazol-2-yl) -p-cresol, 2- (2′-hydroxy-3 ′, 5′-di-t-amylphenyl) 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] -4 -Methyl-6- (t-butyl) phenol and the like can be mentioned.
Examples of the benzophenone ultraviolet absorber include 2-hydroxy-4-methoxybenzophenone, 5-benzoyl-4-hydroxy-2-methoxybenzene sulfonic acid 2-hydroxy-4-n-octyloxybenzophenone, and 2,4-dihydroxy. Examples include benzophenone.
Examples of the benzoate ultraviolet absorber include 2,4-t-butylphenyl-3,5-di-t-butyl-4-hydroxybenzoate.
Examples of cyanoacrylate-based ultraviolet absorbers include ethyl-2-cyano-3,3-diphenyl acrylate and 2-ethylhexyl-2-cyano-3,3-diphenyl acrylate.

  Examples of the light stabilizer include hindered amines having a hindered piperidine skeleton, such as bis (1,2,2,6,6-pentamethyl-4-piperidinyl) sebacate and bis (2,2,6,6-tetramethyl). -4-piperidinyl) sebacate, poly ((6-((1,1,3,3-tetramethylbutyl) amino) -s-tetrazine-2,4-didyl) (2,2,6,6-tetramethyl -4-piperidyl) imino) hexamethylene (2,2,6,6-tetramethyl-4-piperidyl) imino))), bis (1,2,2,6,6-pentamethyl-4-piperidyl) [[ 3,5-bis (1,1-dimethylethyl) -4-hydroxyphenyl] methyl] butyl malonate and the like.

  The production of the urethane foam may be either a one-shot method or a prepolymer method. The one-shot method is a method in which a polyol and isocyanate are directly reacted in the presence of a foaming agent, a catalyst, an antioxidant and the like. On the other hand, the prepolymer method is a method in which a polyol and isocyanate are reacted in advance to obtain a prepolymer having an isocyanate group at the terminal, and this prepolymer is reacted with a polyol in the presence of a foaming agent, a catalyst, an antioxidant and the like. is there. The urethane foam is preferably a slab urethane foam. Slab urethane foam is a continuous material that is produced by discharging the mixed and stirred raw material (reaction mixture raw material) onto a belt conveyor, and the material naturally foams and cures at room temperature and atmospheric pressure while the belt conveyor moves. To be manufactured. Then, after hardening (curing) in a drying furnace, it is cut into a size suitable for an elastic elastic member.

  The urethane foam for elastic stretchable members produced by the present invention has an elongation at break (JIS K6400-5) of 140% or more and a tensile strength (JIS K6400-5) of 130 kPa or more, and an elastic stretchable member for diapers. It is suitable as.

  The blended raw materials shown in Tables 1 and 2 were stirred with a mixer using the following raw materials, and urethane foams of Examples and Comparative Examples were produced by a one-shot method. The liquid temperature of a compounding raw material is 23 degreeC.

Polyester polyol-1; product name: Edifice E-541, manufactured by Kao Corporation, poly (diethylene glycol adipic acid ester, hydroxyl value: 61 mgKOH / g, number average molecular weight: 2500
Polyester polyol-2; product name: Kurapol F3010, manufactured by Kuraray Co., Ltd., poly [(3-methyl-1,5-pentanediol; trimethylolpropane) -alt- (adipic acid)], hydroxyl value: 56 mgKOH / g, number Average molecular weight: 3000
-Polyether polyol; Product name: Sannix GP-3050, manufactured by Sanyo Chemical Co., Ltd., hydroxyl value: 56 mgKOH / g, average functional group number 3, number average molecular weight 3000

-Foam stabilizer-1; product name: Tegostarb B 8325, manufactured by Evonik Japan, polyether-modified polysiloxane-Foam stabilizer-2; product name: Tegostarb BF 2370, manufactured by Evonik Japan, polyether-modified polysiloxane

-Reactive amine catalyst-1; Product name: DABCO NE300, manufactured by Air Products Japan, N- [2- [2- (dimethylamino) ethoxy] ethyl] -N-methyl-1,3-propanediamine-Reactive amine Catalyst-2: Product name: Kao Riser No. 25, manufactured by Kao Corporation, 6-dimethylamino-1-hexanol, non-reactive amine catalyst-1; product name: DABCO 33-LV, manufactured by Air Products Japan, 1,4 diazabicyclo (2,2,2) octane 33% Dipropylene glycol solution ・ Non-reactive amine catalyst-2; Product name: Kao Riser number 22, manufactured by Kao Corporation, N-ethylmorpholine Tin catalyst; Product name: MRH-110, manufactured by Johoku Chemical Industry Co., Ltd., stannous octylate

Ultraviolet absorber; Tinuvin 571, manufactured by BASF Japan, reaction product of 2- (2-hydroxy-5-methylphenyl) benzotriazole and 1-dodecene Hindered phenolic antioxidant; Product name: Irganox 1135 Manufactured by BASF Japan Ltd., benzenepropanoic acid, 3,5-bis (1,1-dimethylethyl) -4-hydroxy-, C7-C9 side chain alkyl ester, reactive phosphite ester antioxidant; NIAX COLOR STABILIZER CS-22LF, manufactured by Momentive Performance Materials Japan G.K., Tris (dipropylene glycol) phosphite ・ Non-reactive phosphorous acid antioxidant; Product name: JP-308E, manufactured by Johoku Chemical Tris (2-ethylhexyl) phosphite

-Alicyclic isocyanate; Product name: Vestanate IPDI, manufactured by Evonik Japan, isophorone diisocyanate-Aromatic isocyanate-1; Product name: Coronate T-80, manufactured by Tosoh Corporation, 2,4-TDI / 2,6- TDI = 80/20
Aromatic isocyanate-2; product name: Coronate T-65, manufactured by Tosoh Corporation, 2,4-TDI / 2,6-TDI = 65/35

Density (kg / m ³ ), hardness (k / Pa), tensile strength (kPa), elongation at break (%), yellowing, NOx discoloration, ultraviolet rays for urethane foams of Examples , Reference Examples and Comparative Examples Discoloration, odor and discoloration of urine signature were measured and evaluated.
The density was measured based on JIS K7222, the hardness was measured based on JIS K6400-2D, the tensile strength was measured based on JIS K6400-5, and the elongation at break was measured based on JIS K6400-5.
For yellowing, the yellowness YI of the initial sample was measured with a color meter (SM-4, manufactured by Suga Test Instruments Co., Ltd.).
For NOx discoloration, the test piece is set in a 10 L desiccator with an internal stirring device, about 2 ml of 99.9% nitrogen dioxide is collected with a syringe and injected into the desiccator, and continuously stirred at 200 rpm. The nitrogen dioxide concentration in the desiccator is about 200 ppm. After leaving in this state for 2 hours, the test piece was taken out and the yellowness YI was measured. The smaller the ΔYI value obtained from the difference between the YI value (the value after NOx exposure) and the YI initial value, the smaller the discoloration. The NOx discoloration was evaluated by “◎ to xx” depending on which range the ΔYI value falls in the lower column of Tables 1 and 2.
For ultraviolet discoloration, the test piece was set on a fade meter (ultraviolet fade meter U48, manufactured by Suga Test Instruments Co., Ltd., black panel temperature 63 ° C.), taken out after irradiation for 5 hours, and measured for yellowness YI. The smaller the ΔYI value obtained from the difference between the YI value (value after UV exposure) and the initial YI value, the less the color change. The ultraviolet discoloration was evaluated by “◎ to xx” depending on which range the ΔYI value falls in the lower column of Table 1.
The odor was determined by placing the test piece in a plastic bag and allowing it to stand for 1 hour, and then sniffing it directly.
The discoloration of the urine sign was as follows: the urine detection sign part (pee sign part) cut from a paper diaper was covered with urethane foam test pieces and sandwiched with a slide glass and left in a furnace at 40 ° C. for one day. . After removal, it was visually determined how much the urine detection sign portion changed from the initial yellow color to blue color.

Examples 1 to 7 are examples in which an alicyclic isocyanate and an aromatic isocyanate are used in combination as an isocyanate, and evaluation of breaking elongation, tensile strength, discoloration resistance to nitrogen oxide gas (NOx), and discoloration resistance to ultraviolet rays is any. The urine detection sign of the paper diaper was not discolored, and the overall evaluation was ◯ or higher.
Reference Example 8 is an example in which an aromatic isocyanate was used alone as the isocyanate, and although the discoloration resistance against nitrogen oxide gas (NOx) was sufficient, it was slightly inferior to Examples 1-7.

  Comparative Example 1 uses polyether polyol alone as polyol, combined use of reactive amine catalyst and tin catalyst as catalyst, combined use of hindered phenolic antioxidant and reactive phosphite antioxidant as antioxidant, isocyanate As an example of the combined use of alicyclic isocyanate and aromatic isocyanate, the tensile strength and elongation at break were inferior, and the discoloration resistance against nitrogen oxide gas (NOx) was greatly inferior.

  Comparative Examples 2 to 4 are examples in which the polyol in Comparative Example 1 was used in combination with a polyester polyol and a polyether polyol. The tensile strength, elongation at break, and nitric oxide gas (NOx) were slightly different from those in Comparative Example 1. Although improvement was seen, it was still greatly inferior compared with Examples 1-8.

  Comparative Example 5 uses a polyester polyol alone as a polyol, a reactive amine catalyst alone as a catalyst, a combined use of a hindered phenolic antioxidant and a non-reactive phosphorous acid antioxidant as an antioxidant, and an aromatic isocyanate as an isocyanate This was an example of the single use of foam, and the foam collapsed during foaming, and a good urethane foam could not be obtained.

  Comparative Example 6 is an example in which a polyester polyol alone is used as a polyol, a non-reactive amine catalyst is used alone, an antioxidant is not used, and an aromatic isocyanate is used alone as an isocyanate, and resistance to discoloration against nitrogen oxide gas (NOx). In addition, the discoloration resistance to ultraviolet rays and ultraviolet rays were both inferior, smelled, and discolored urine signs.

  Comparative Example 7 is an example in which the reaction type amine catalyst was used alone in Comparative Example 6, and although the discoloration of odor and urine sign was improved, the discoloration resistance against nitric oxide gas (NOx) and the resistance against ultraviolet rays were improved. About discoloration, it was inferior to the comparative example 6.

  Comparative Example 8 is an example of the use of an ultraviolet absorber in Comparative Example 6 and a single use of a hindered phenol-based antioxidant as an antioxidant. Compared with Comparative Example 6, the resistance to discoloration against ultraviolet rays is improved. However, the discoloration resistance against nitrogen oxide gas (NOx) was still inferior, smelled, and the urine sign was discolored.

  Comparative Example 9 is an example in which the catalyst was replaced with a non-reactive amine catalyst in Comparative Example 8 as a reactive amine catalyst, and compared with Comparative Example 8, the odor and urine sign discoloration were improved. The evaluation of discoloration resistance against nitrogen oxide gas (NOx) was slightly improved from “xx” to [×], and the discoloration resistance against nitrogen oxide gas (NOx) was still inferior.

  Comparative Example 10 is a comparative example 9 in which the catalyst is a combination of a non-reactive amine catalyst and a tin catalyst, and the antioxidant is a combined use of a hindered phenol antioxidant and a reactive phosphite ester antioxidant, This is an example in which an isocyanate is a combination of an alicyclic isocyanate and an aromatic isocyanate. Compared to Comparative Example 9, Comparative Example 10 improved discoloration resistance to nitrogen oxide gas (NOx), but was inferior in odor and discoloration of urine signature.

  Comparative Example 11 is an example in which the antioxidant is a combination of a hindered phenol antioxidant and a reactive phosphite ester antioxidant in Comparative Example 9, and nitrogen oxide gas ( NOx) was inferior in discoloration resistance.

  Thus, according to the present invention, the urethane foam for elastic stretchable members has good elongation at break, tensile strength, discoloration resistance against nitrogen oxide gas, no odor, and does not discolor the urine detection sign of a paper diaper. Can be manufactured.

DESCRIPTION OF SYMBOLS 10 Paper diaper 11 Peripheral part of leg opening 12 Elastic elastic member 15 Peripheral part of waist opening 16 Elastic elastic member

Claims (2)

The polyol and isocyanate, blowing agent, a catalyst, in the production method of the resilient and elastic members for urethane foam is reacted in the presence of an antioxidant,
Using only polyester polyol as the polyol,
The isocyanate includes an aromatic isocyanate and an alicyclic isocyanate, and the weight ratio of aromatic isocyanate: alicyclic isocyanate is 99 to 80: 1 to 20,
Using only a reactive amine catalyst as the catalyst,
A method for producing a urethane foam for elastic elastic members, wherein a hindered phenol-based and / or reactive phosphite-based antioxidant is used as the antioxidant. The method for producing a urethane foam for an elastic elastic member according to claim 1, wherein the urethane foam for an elastic elastic member is used for a paper diaper .

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