JP6758089B2 - Gather members, and absorbent articles and medical supplies using them - Google Patents

Description

The present invention relates to a gather member, and an absorbent article and a medical product using the gather member.

Conventionally, elastic gather members are arranged on the waist and legs of disposable diapers in order to improve the fit and prevent leakage of urine and the like. Such a gather member generally has a non-woven fabric and elastic fibers such as rubber and polyurethane, and the elastic fibers are adhered to the non-woven fabric in a stretched state by a hot melt adhesive or the like at the time of manufacturing the gather member, and the gather member. Is given elasticity.

Therefore, the characteristics of the elastic fiber as an elastic material after being adhered to the non-woven fabric by a hot melt adhesive or the like have a great influence on the fit feeling of a disposable diaper or the like and urine leakage. Various proposals have been made for gathering members such as disposable diapers.

For example, Patent Document 1 proposes a polyurethane elastic fiber having a specific treatment agent attached to a polyurethane elastic fiber containing a specific polyalkylene ether diol as a constituent unit, which is easy to put on and take off and has a comfortable fit. .. However, since elastic fibers undergo a drawing step, a hot melt bonding step, and the like in the diaper manufacturing process, their physical properties change during the process, and the degree of effect varies depending on the method of use.

Further, in Patent Document 2, by specifying the physical properties of the gather members in which elastic fibers are arranged at regular intervals between two sheets, it is difficult for the elastic fibers to be displaced at the time of mounting, and the traces of rubber can be suppressed. Diapers have been proposed. However, specific elastic fibers for obtaining these effects are not disclosed.

Japanese Unexamined Patent Publication No. 2005-344214 Japanese Unexamined Patent Publication No. 2004-81365

An object of the present invention is to provide a gather member that is easy to put on and take off, has a good fit for a long time, is hard to slip off, and can provide an absorbent article, a medical article, and the like.

As a result of studies to solve the above problems, the present inventors have found that the elastic fibers contained in the gather member have specific stress during elongation, stress retention rate, residual strain, and stress relaxation time. It was found that the present invention can be solved.

That is, the present invention is as follows.
[1]
A gather member containing elastic fibers, wherein the elastic fibers contained in the gather members are the following (a) to (d):
(A) The stress (cN / dT) at the time of the third repeated 300% elongation in the 300% elongation recovery repeated test is 0.050 or more and 0.150 or less.
(B) The 200% stress retention rate (%) of the third repetition in the 300% extension recovery repetition test is 65 or more and 95 or less.
(C) The residual strain (%) after the third repetition in the 300% stretch recovery repetition test was 42 or less.
(D) A gather member satisfying that the stress relaxation time (seconds) is 70 or more and 95 or less.
[2]
The gather member according to item 1, wherein the elastic fiber is a polyurethane elastic fiber containing a polytetramethylene ether glycol, an organic diisocyanate compound, and an active hydrogen atom-containing compound that reacts with an isocyanate group as a constituent unit.
[3]
The gather member according to item 2, wherein the soft segment of the polymer constituting the elastic fiber has a molecular weight of 4850 or more and 6000 or less.
[4]
The gather member according to item 2 or 3, wherein the hard segment of the polymer constituting the elastic fiber has a molecular weight of 700 or more and 820 or less.
[5]
The gather member according to any one of items 1 to 4, wherein the fineness per filament of the elastic fiber is 5.0 dt or more and 20.0 dt or less.
[6]
An absorbent article having the gather member according to any one of items 1 to 5.
[7]
A medical product having the gather member according to any one of items 1 to 5.

The gather member of the present invention can provide an absorbent article, a medical article, and the like that are easy to put on and take off, have a good fit for a long time, and do not easily slip off.

FIG. 1 is an example of the structural formulas of the soft segment portion and the hard segment portion of the polyurethane elastic fiber included in the gather member of the present embodiment. FIG. 2 is an example of an NMR spectrum diagram of the polyurethane elastic fiber contained in the gather member of the present embodiment. FIG. 3 is an example of a graph at the time of measuring the stress relaxation time of the elastic fiber contained in the gather member of the present embodiment.

Hereinafter, embodiments of the present invention (hereinafter, also referred to as “the present embodiment”) will be described in detail, but the present invention is not limited to the following embodiments.

《Gather member》
The gather member in the present embodiment is a gather member containing elastic fibers, and the elastic fibers contained in the gather members are the following (a) to (d) :( a) 300% stretch recovery repeated test for the third time. The stress (cN / dT) at the time of 300% elongation is 0.050 or more and 0.150 or less, and (b) the 200% stress retention rate (%) of the third repetition in the 300% extension recovery repeated test is 65 or more and 95. The following, (c) the residual strain (%) after the third repetition in the 300% stretch recovery repetition test is 42 or less, and (d) the stress relaxation time (second) is 70 or more and 95 or less. Fulfill. Here, in the present specification, each physical property of the elastic fiber means the physical property of the elastic fiber after being adhered to the non-woven fabric by a hot melt adhesive or the like.

In the present embodiment, the stress (cN / dT) at the time of the third repeated 300% elongation in the 300% elongation recovery repeated test of the elastic fiber contained in the gather member (hereinafter, also simply referred to as “elongation stress”) is determined. It is 0.050 or more and 0.150 or less. When the stress at elongation is 0.050 or more, the function of the elastic fiber as an elastic body can be satisfactorily exhibited, a good fit immediately after wearing can be obtained, and it is 0.150 or less. , When wearing a disposable diaper, it can be worn smoothly even if the stretching force is weak. The stress during elongation is preferably 0.060 or more and 0.145 or less.

In the present embodiment, the 200% stress retention rate (%) (hereinafter, also simply referred to as “stress retention rate”) of the elastic fiber contained in the gather member for the third repetition in the 300% stretch recovery repeated test is 65 or more and 95. It is as follows. When the stress retention rate is 65 or more, the tightening force at the time of wearing can be sufficiently held and slipping is less likely to occur, and when it is 95 or less, the tightening force is not too strong and the wearer is less likely to be uncomfortable, and physical It is easy to produce. The stress retention rate is preferably 67 or more and 95 or less.

In the present embodiment, the residual strain (%) (hereinafter, also simply referred to as “residual strain”) after the third repetition in the 300% stretch recovery repetition test of the elastic fiber contained in the gather member is 42 or less. When the residual strain is 42 or less, the elastic fibers are less likely to be distorted when worn, and problems such as weakening of the tightening force and slipping off can be effectively reduced. The residual strain is preferably 40 or less.

In the present embodiment, the stress relaxation time (seconds) of the elastic fibers contained in the gather member is 70 or more and 95 or less. The shorter the stress relaxation time (seconds) is, the better, but it is physically difficult to produce elastic fibers of less than 70, and if it is 95 or less, it is possible to maintain an appropriate fit for a long period of time when wearing the gather member. .. The stress relaxation time is preferably 70 or more and 93 or less.

The elastic fibers used for the gather member of the present embodiment include polyurethane elastic fibers, polyester elastic fibers, polyamide elastic fibers, polyolefin elastic fibers, natural rubber, rubber threads made of synthetic rubber, and other organic synthetics mainly composed of these. Elastic fibers obtained by compounding or mixing with a resin are used. The polyurethane elastic fiber is composed of a soft segment portion composed of a polyether diol and an organic diisocyanate and a hard segment portion composed of an organic diisocyanate and a diamine or a diol.

The elastic fiber used in the present embodiment is preferably a polyurethane elastic fiber containing a polytetramethylene ether glycol, an organic diisocyanate compound, and an active hydrogen atom-containing compound that reacts with an isocyanate group as a constituent unit.

FIG. 1 shows an example of the structural formulas of the soft segment portion and the hard segment portion of the polyurethane urea of the polyurethane elastic fiber used in the present embodiment. In FIG. 1, R ₁ represents a residue of polyalkylene ether diol, R ₂ represents a residue of organic diisocyanate, and R ₃ represents a residue of diamine. In the present embodiment, it is preferable to use polyurethane elastic fibers from the viewpoint of developing a specific stress during elongation, stress retention rate, residual strain, and stress relaxation time.

Examples of the polyalkylene ether diol contained in the polyurethane elastic fiber used in the present embodiment as a constituent unit include: polyethylene glycol, polypropylene glycol, polytetramethylene ether glycol, polyhexamethylene ether glycol and the like having 2 to 6 carbon atoms. You may use the one in which the alkylene group of the above is linearly ether-bonded; a linear one having 2 to 6 carbon atoms such as ethylene, propylene, tetramethylene and hexamethylene, and 1,2-propylene and 3 A copolymerized polyalkylene having a methyl group on the side chain in which two or more branched alkylene groups having 2 to 10 carbon atoms such as −methyltetramethylene, 3-methylpentamethylene, and 2,2-dimethylpropylene are ether-bonded. Etherdiol may be used. From the viewpoint of the stretch performance of the obtained gathers, water resistance, light resistance, and abrasion resistance, polytetramethylene ether glycol is preferable as the polyalkyrether diol.

Examples of the organic diisocyanate compound contained in the polyurethane elastic fiber used in the present embodiment as a constituent unit include aliphatic, alicyclic and aromatic diisocyanates that are soluble or liquid under reaction conditions. All applicable. For example, 4,4'-diphenylmethane diisocyanate, 2,4'-diphenylmethane diisocyanate, methylene-bis (3-methyl-4-phenylisocyanate), 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, m- And p-xylylene diisocyanate, α, α, α', α'-tetramethyl-p-xylylene diisocyanate, m- and p-phenylenediocyanate, 4,4'-dimethyl-1,3-xylylene diisocyanate, 1 -Alkylphenylene-2,4 and 2,6-diisocyanis, 3- (α-isocyanisethyl) phenylisocyanate, 2,6-diethylphenylene-1,4-diisocyanate, diphenyl-dimethylmethane-4,4-diisocyanis, diphenyl ether -4,4'-diisocyanate, naphthylene-1,5-diisocyanate, 1,6-hexamethylene diisocyanate, methylene-bis (4-cyclohexamethylene diisocyanate), 1,3- and 1,4-cyclohexylene diisocyanate, trimethylene diisocyanate , Tetramethylene diisocyanate, pentamethylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate and the like. These diisocyanates may be used alone or in combination of two or more. From the viewpoint of reactivity and stress during elongation, the organic diisocyanate compound is preferably 4,4'-diphenylmethane diisocyanate.

The active hydrogen atom-containing compound that reacts with the isocyanate group contained in the polyurethane elastic fiber used in the present embodiment as a constituent unit is a polyfunctional active hydrogen atom-containing compound as a chain extender and a monofunctional compound as a terminal terminator. Active hydrogen atom can be mentioned.

Examples of the polyfunctional active hydrogen atom-containing compound, which is a chain extender that reacts with an isocyanate group and contained as a constituent unit in the polyurethane elastic fiber used in the present embodiment, include hydrazine, polyhydrazine, and 2 to 10 carbon atoms. Examples thereof include compounds having an amino group or a hydroxyl group having a linear or branched aliphatic, alicyclic or aromatic active hydrogen, for example, ethylenediamine, 1,3-propylenediamine, 1,5-diaminopentane, and the like. 1,6-diaminohexane, N-methylethylenediamine, N, N'-dimethylethylenediamine, N-ethylethylenediamine, N, N'-diethylethylenediamine, N-isopropylethylenediamine, 1,2-diaminopropane, 2-methyl-1 , 3-Propanediamine, 3-Methyl-1,5-pentanediamine, 1,3-bis (aminomethyl) cyclohexane, phenylenediamine, xylylenediamine, 4,4'-diaminodiphenylmethane, piperazin, JP-A-5-155841 Diamines such as diamines having a urea group described in the publication, hydroxylamine, water, low molecular weight glycols such as ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 2,2-dimethyl -1,3-propanediol, 1,4-butanediol, 1,3-butanediol, hexamethylene glycol, diethylene glycol, 1,10-decanediol, 1,3-dimethylolcyclohexane and 1,4-dimethylolcyclohexane Etc. can be used. Preferably, the polyfunctional active hydrogen atom-containing compound is ethylenediamine or 1,2-propylenediamine.

Examples of the monofunctional active hydrogen atom which is a terminal terminator that reacts with an isocyanate group contained in the polyurethane elastic fiber used in the present embodiment as a constituent unit include a dialkylamine such as diethylamine and an alkyl such as ethanol. Alcohol is used. These chain extenders and terminal terminators may be used alone or in combination of two or more.

Regarding the reaction operation of polyurethane-forming the polyurethane elastic fiber, a solvent-free solvent may be used, or a solvent such as dimethylformamide, dimethyl sulfoxide, or dimethylacetamide may be used.

In the polyurethane polymer of the polyurethane elastic fiber used in the present embodiment, a polyalkylene ether diol is reacted with a molar excess of organic diisocyanate to synthesize a urethane prepolymer to be a soft segment, and then a hard segment is polymerized with a chain extender. It can be produced by using a known technique such as end-sealing with an end-stopping agent.

As a method for controlling the number average molecular weight M _s of the soft segments of the polyurethane elastic fiber used in the present embodiment, the number average molecular weight M _do of the polyalkylene ether diol and the molar ratio N ₁ of the organic diisocyanate to the polyalkylene ether diol are adjusted. There is a way to do it. Here, the soft segment number average molecular weight M _s is calculated by the following formula (1).

M _s = {M _do + M _di (N ₁ −N ₀ )} / (N ₁ −N _0-1 ) -2M _di … Equation (1)

M _s : Number average molecular weight of soft segment portion M _do : Number average molecular weight of polyalkylene ether diol M _di : Molecular weight of organic diisocyanate N ₁ : Molar ratio of organic diisocyanate to polyalkylene ether diol N ₀ : By the following formula (2) The required molar ratio of the unreacted organic diisocyanate present after the urethane prepolymer reaction to the polyalkylene ether diol

N ₀ = aN ₁ ⁴ + bN ₁ ³ + cN ₁ ² + dN ₁ + e ... Equation (2)

In Equation 2, a to e: constants (a = 0.03806, b = -0.3997, c = 1.617, d = -2.144, e = 0.8795).

That is, in order to control the number average molecular weight M _s of the soft segment portion, after determining the molecular weight M _do of the polyalkylene ether diol to be used, M _s of the above formula (1) is set to a predetermined value. it may be designed molar ratio N ₁ of the organic diisocyanate to polyalkylene ether diol.

The number-average molecular weight _{M s} of the soft segment moiety is preferably 6000 or less than 4850. When it is 4850 or more, the proportion of the hard segment portion in the entire polyurethane is reduced, the stress at the time of 300% elongation of the polyurethane elastic fiber in the gather member is reduced, and the detachability is improved. Further, when it is 6000 or less, the proportion of the hard segment portion in the entire polyurethane increases, the stress at the time of 300% elongation of the polyurethane elastic fiber in the gather member increases, and a better fit can be obtained. More preferably, it is 4900 or more and 5900 or less. More preferably, it is 5050 or more and 5900 or less.

The resulting urethane prepolymer is reacted with a diamine, when to chain extension, by the presence of organic unreacted diisocyanate, it is possible to increase the number average molecular weight M _h of the hard segment moiety. Therefore, as a method for controlling the number average molecular weight M _h of the hard segment portion, a method of adjusting the molecular weight M _{da of the} diamine and the molar ratio N ₃ of the organic diisocyanate present during the chain extension reaction to the polyalkylene ether diol can be mentioned. .. The organic diisocyanate present at the time of the chain extension reaction may be an unreacted component existing after the urethane prepolymer synthesis, which was excessively added before the prepolymer reaction, and at the time of the chain extension reaction after the completion of the urethane prepolymer synthesis. It may be additionally added or a combination thereof. That is, the molar ratio N ₃ of the organic diisocyanate present during the chain extension reaction to the polyalkylene ether diol is represented by the following formula (3), and N ₂ may be 0 when it is not necessary to additionally add the organic diisocyanate.

N ₃ = N ₀ + N ₂ ... Equation (3)

N ₃ : Mol ratio of organic diisocyanate present during chain extension reaction to polyalkylene ether diol N ₀ : Mol ratio of unreacted organic diisocyanate present after urethane prepolymer reaction to polyalkylene ether diol determined by the above formula (2) Ratio N ₂ : The molar ratio of the organic diisocyanate added during the chain extension reaction to the polyalkylene ether diol (N ₂ = 0 when no additional addition is made).

The number average molecular weight M _h of the hard segment portion can be calculated by the following formula (4). That is, the molar on determining chain extender to be used, the molecular weight of the diamine, for M _h are formed so that initially determined value, polyalkylene ether diols of the organic diisocyanates present in the chain elongation reaction of the following formula (4) The ratio N ₃ may be determined.

M _h = {M _da (N ₁ + N ₃ −N _0-1 ) + M _di × N ₃ } / (N ₁ −N _0-1 ) + 2M _di … (4)

M _h : Number average molecular weight of the hard segment part M _da : Molecular weight of diamine (when two or more types are mixed and used, the number average molecular weight)
M _di : Molecular weight of organic diisocyanate N ₀ : Molly ratio of organic diisocyanate present after urethane prepolymer synthesis to polyalkylene ether diol N ₁ : Moor ratio of organic diisocyanate to polyalkylene ether diol N ₃ : The molar ratio of the organic diisocyanate present during the chain extension reaction to the polyalkylene ether diol determined by the above formula (3).

The urethane prepolymer to which additional organic diisocyanate is added as needed is diluted with an inert solvent as necessary to adjust the concentration. Then, by reacting the chain extender diamine to generate a hard segment portion, a polyurethane urea solution having the initially determined soft segment number average molecular weight and hard segment number average molecular weight can be produced. At this time, the diamine may be diluted with an inert solvent. Further, a terminal terminator having a monofunctional active hydrogen atom may be contained in the diamine of the chain extender.

The number average molecular weight M _h of the hard segment portion is preferably 700 or more and 820 or less. When it is 700 or more, the proportion of the hard segment portion in the entire polyurethane increases, the stress at the time of 300% elongation of the polyurethane elastic fiber in the gather member increases, and a better fit of the gather member can be obtained. When it is 820 or less, the proportion of the hard segment portion in the entire polyurethane is reduced, the stress at the time of 300% elongation of the polyurethane elastic fiber in the gather member is reduced, and the detachability of the gather member is improved. The number-average molecular weight _{M h} of the hard segment moiety, more preferably is 710 or more 800 or less.

In the present embodiment, various stabilizers, pigments and the like may be added to the polyurethane polymer. For example, lightfasteners, hindered phenolic agents, benzotriazoles, benzophenones, phosphorus and various hindered amine antioxidants, inorganic substances such as iron oxide, titanium oxide, zinc oxide, cerium oxide, magnesium oxide, carbon black and Various pigments, antibacterial agents and deodorants containing silver, zinc and compounds thereof, antistatic agents, nitrogen oxide trapping agents, thermal oxidation stabilizers, light stabilizers and the like may be added in combination.

Polyurethane elastic fibers can be obtained by molding the polyurethane polymer into fibers by a known dry spinning, melt spinning, wet spinning method or the like. Further, polyurethane polymers polymerized using different raw materials may be mixed and spun at the pre-spinning stage. The spinning speed at the time of spinning is preferably 250 to 800 m / min. More preferably, it is 300 to 700 m / min. Furthermore, the speed ratio between the godet roller (hereinafter referred to as the "first godet roller") that the spun yarn first contacts at the time of winding and the winder is shown by the following formula (5), and this speed is expressed. The ratio is preferably 0.9 to 1.7. When the take-up speed ratio is 0.9 or more, the yarn is appropriately drawn, and it becomes easier to set the stress relaxation time (seconds) to 70 or more and 95 or less. When the take-up speed ratio is smaller than 0.9, the yarn is not stretched and the stress relaxation time tends to be short. Further, by setting the winding speed ratio to 1.7 or less, the yarn is not stretched more than necessary, and it becomes easier to adjust the stress at the time of 300% stretching to 0.15 cN / dT or less. The take-up speed ratio is preferably 1.0 to 1.5.

Winding speed ratio = Winding machine speed (m / min) / First Godet roller speed (m / min) ... Equation (5)

The number of single yarns of the polyurethane elastic fiber may be either monofilament or multifilament, but the single yarn fineness shall be 5.0 dt (decitex) or more and 20.0 dt (decitex) or less from the viewpoint of adhesiveness at the time of producing the gather member. Is preferable, and a multifilament having a single yarn fineness of 5.0 dt or more and 20.0 dt or less is more preferable. The single yarn fineness is more preferably 6.0 dt or more and 18.0 dt or less. The total fineness of the elastic fiber is preferably 10 to 3000 dt.

The obtained polyurethane elastic fiber is usually subjected to a treatment agent by a known method such as roll oiling, guide oiling, spray oiling, etc. before or after winding into a paper tube package, but is wound without applying a treatment agent. You may.

The treatment agent used in the present embodiment is not particularly limited, but includes polydimethylsiloxane, polyester-modified silicon, polyether-modified silicon, amino-modified silicon, mineral oil, mineral fine particles, such as silica, colloidal alumina, and talc. Examples of higher fatty acid metal salt powders include higher aliphatic carboxylic acids such as magnesium stearate and calcium stearate, higher aliphatic alcohols, and oils such as paraffin and polyethylene solid wax at room temperature, which are used alone or are required. It may be given in any combination according to the above. Further, for the purpose of adhesiveness to the non-woven fabric via hot melt, unwinding property from the winding body, and improvement of friction during the diaper manufacturing process, homo or copolymer polyalkylene ether diol and an OH group at the terminal are added. A treatment agent obtained by adding mineral oil, dimethyl silicon, or a mixture of mineral oil and dimethyl silicon to a mixture with a higher alcohol having 8 to 25 carbon atoms may be used.

<< Manufacturing method of gather members >>
The gathering member is manufactured by the usual method in the manufacturing process of ordinary disposable diapers, sanitary napkins, masks, bandages, etc., and is adhered to a non-woven fabric or the like via hot melt or the like with the elastic thread stretched. Can be made. Usually, the elastic fiber used for the gather member is unwound from the winding body when it is arranged in the gather portion, and then stretched in a draft ratio of 2.0 to 4.0 via a guide or a roller. In that state, the hot melt is directly applied to the elastic fiber and adhered to the non-woven fabric, or the elastic fiber is adhered to the non-woven fabric to which the hot melt is applied. By going through this step, the elastic fibers are lightly set, and the elastic fibers exhibiting the physical properties of the present embodiment can be obtained.

The elastic fibers in the gather member used in the present embodiment may be bare yarns, or may be coated or covered with other elastic fibers or non-elastic fibers.

<< Absorbent goods and medical supplies >>
The gather member of the present embodiment can be suitably used as a base material for absorbent articles such as sanitary napkins and disposable disposable diapers, and medical products such as masks and bandages. For example, in the waist portion and leg circumference portion of a disposable diaper or the like, there is a portion where elastic fibers are adhered to a non-woven fabric via hot melt, and the gather member of the present embodiment is particularly preferably used for such waist portion and leg circumference portion. be able to.

Hereinafter, the present embodiment will be specifically described with reference to Examples, but the present embodiment is not limited thereto.

<< Manufacturing example of gather member >>
Three elastic fibers are lined up in parallel at intervals of 5 mm, stretched so as to be three times the original length of the elastic fibers, and the stretched elastic fibers are melted at 160 ° C. Hot melt (Henkel Japan). Dispomelt 5434) manufactured by Suntool Co., Ltd. was applied with a comb gun manufactured by Suntool Co., Ltd. so as to have a concentration of 0.03 g / m per fiber. Elastic fibers that have been stretched and coated with hot melt are sandwiched between two pieces of Asahi Kasei Fibers Co., Ltd. non-woven fabric and Eltus Guard (registered trademark) with a width direction of 5 cm and a basis weight of 17 g / m ² while maintaining the stretch. A gather member was produced by crimping with a roller.

<< Evaluation method of gathered parts >>
<Wearing feeling of gathered parts>
The gather member was left in a non-stretched state for one day to sufficiently relieve the stress of the elastic fiber. Then, a length of 42 cm was measured from the relaxed gather member, and the ends were heat-bonded to each other with a heat sealer to prepare a ring having a circumference of 42 cm made of the gather member. Ten subjects with a waist length of 75 cm to 80 cm wore this ring on the waist part, and the sensory evaluation of the wearing feeling at that time was carried out according to the following criteria.
・ Detachability ◎: When 8 to 10 people judge that the detachability is good ○: When 6 to 7 people judge that the detachability is good △: 4 to 4 people who judge that the detachability is good In the case of 5 people ×: When 3 or less people judge that the detachability is good ・ Fit ◎: When 8 to 10 people judge that the tightening is appropriate ○: 6 people judge that the tightening is appropriate ~ 7 people △: 4 to 5 people judged to be moderately tightened ×: 3 or less people judged to be moderately tightened ・ Fit durability ◎: Gathered member wearing 30 minutes tightening When 8 to 10 people judge that it is appropriate ○: When 6 to 7 people judge that tightening for 30 minutes wearing gathered material is appropriate Δ: Those who judge that tightening for 30 minutes wearing gathered material is appropriate In the case of 4 to 5 people ×: When the number of people who judged that tightening for 30 minutes wearing gathered parts was appropriate was 3 or less

<(A) Stress at 300% elongation at the third repetition in the 300% extension recovery repeated test (cN / dT), (b) 200% retention rate (%) at the third repetition, (c) Residual at the third repetition distortion(%)>
The gather member was immersed in cyclohexane, an organic solvent, for 10 minutes and stirred. After stirring, the elastic fibers peeled off from the non-woven fabric were taken out and air-dried for one day. After air-drying, the fineness (dt) was calculated from the following formula (6) from the length (m) and weight (g) of the elastic fibers.

Fineness (dt) = 10000 / Length of elastic fiber (m) x Weight of elastic fiber (g) ... Equation (6)

Next, using a tensile tester (RTG-1210 type Tensilon manufactured by Orientec Co., Ltd.), elastic fibers after air drying with a sample length of 10 mm were subjected to a speed of 100 mm / min under the conditions of 20 ° C. and 65% relative humidity. A repeated stretch recovery test with an elongation of 0% to 300% was carried out three times. At that time, the stress (cN) at the time of 300% elongation for the third time was repeatedly measured. The value obtained by dividing the obtained stress value by the fineness (dt) of the elastic fiber obtained by the above formula (6) was taken as the stress at 300% elongation (cN / dt).

Further, the stress during elongation in the 300% elongation recovery repeated test was defined as SM, the stress during recovery was defined as RM, and SM (cN) and RM (cN) at the time of the third 200% elongation were measured repeatedly. The ratio of RM to SM at the time of 200% elongation is called 200% stress retention rate (%), and is calculated from the following formula (7).

200% stress retention rate (%) = 200% RM / 200% SM × 100 ... Equation (7)

200% RM: RM (cN) at the third 200% elongation in the repeated 300% elongation recovery test
200% SM: SM (cN) at the third 200% elongation in the repeated test of 300% elongation recovery

Further, the strain amount RS (mm) at which the RM becomes 0 after performing the 300% elongation recovery repeated test three times was measured. The residual strain (%) at this time was calculated from the following equation (8).

Residual strain (%) = RS / 10 × 100 ... Equation (8)

RS: Strain amount (mm) at which RM becomes 0 after performing the 300% elongation recovery repeated test three times.

<Number average molecular weight M _s of soft segment portion and number average molecular weight M _{h of} hard segment portion by NMR>
The gather member was immersed in cyclohexane, an organic solvent, for 10 minutes and stirred. After stirring, the elastic fibers peeled off from the non-woven fabric were taken out and air-dried for one day. Then, Soxhlet extraction was performed using chloroform as a solvent to remove organic additives from the elastic fibers. Chloroform was removed by drying, and the measurement was carried out under the following equipment and conditions.
Measuring device: JEOL ECS400
Measurement nucleus: 1H
Resonance frequency: 400MHz
Number of integrations: 256 times Measurement temperature: Room temperature Solvent: Deuterated dimethylformamide Measurement concentration: 1.5% by weight
Chemical shift criteria: Dimethylformamide (8.023 ppm)

FIG. 2 shows an example of the NMR spectrum of the polyurethane elastic fiber composed of the polyalkylene ether diol and 4,4'-diphenylmethane diisocyanate measured under these measurement conditions. The line P in FIG. 2 is the NMR spectrum, and I is the integration curve thereof. In this example, the peak of the methylene group (f1) of a 4,4'-diphenylmethane diisocyanate having urethane bonds at both ends is 3.87 ppm, and one is a urethane bond and the other is a urea bond, 4,4'-diphenylmethane diisocyanate. The peak (f2) of the methylene group of the above can be confirmed at 3.84 ppm, and the peak (f3) of the methylene group of 4,4′-diphenylmethane diisocyanate having a urea bond at both ends can be confirmed at 3.81 ppm. The height of the integral curve of the peak f1 was set to F1, and the height of the integral curve corresponding to f2 and f3 was set to F2 and F3. The average number of repetitions m of the soft segment portion and the average number of repetitions n of the urea portion in the structural formula of FIG. 1 were obtained from the following formulas (9) and (10).

m = 2 × (F1 / F2)… Equation (9)

m: Average number of repetitions of the soft segment part F1: Height of the integral curve of peak f1 F2: Height of integral curve of peak f2

n = 2 × (F3 / F2) ... Equation (10)

n: Average number of repetitions of the hard segment part F3: Height of the integral curve of peak f3 F2: Height of integral curve of peak f2

Further, the number average molecular weight M _{s of} the soft segment portion and the number average molecular weight M _h of the hard segment portion were obtained from the following formulas (11) and (12).

M _s = (M _do + M _di ) × m + M _do … Equation (11)

M _s : Number average molecular weight of soft segment portion M _do : Number average molecular weight of polyalkylene ether diol M _di : Molecular weight of organic diisocyanate m: Average number of repetitions of soft segment portion

M _h = (M _da + M _di ) × n + M _da + 2M _di ... Equation (12)

M _h : Number average molecular weight of the hard segment part M _da : Molecular weight of diamine (when two or more types are mixed and used, the number average molecular weight)
M _di : Molecular weight of organic diisocyanate n: Average number of repetitions of hard segment portion

The structure of the polyalkylene ether diol and the number average molecular weight M _do of the polyalkylene ether diol can also be confirmed by an NMR spectrum.

<(D) Stress relaxation time>
The gather member was immersed in cyclohexane, an organic solvent, for 10 minutes and stirred. After stirring, the elastic fibers peeled off from the non-woven fabric were taken out and air-dried for one day. Next, using a tensile tester (RTG-1210 type Tensilon manufactured by Orientec Co., Ltd.), elastic fibers after air drying with a sample length of 10 mm were placed at a speed of 100 mm / min under the conditions of 20 ° C. and 65% relative humidity. A repeated stretch recovery test with an elongation of 0% to 300% was carried out twice. The elastic fiber having a sample length of 10 mm after the test was further stretched to an elongation of 100% at a rate of 100 mm / min, and the ultimate stress S1 (cN) at that time was measured. The elastic fiber was kept at 100% elongation, and the stress S2 (cN) after 600 seconds was measured. FIG. 3 shows an example of a graph at the time of measuring the stress relaxation time of the elastic fiber contained in the gather member of the present embodiment. Using the S1 and S2 values, the time (seconds) for reaching the relaxation stress S3 (cN) obtained from the following equation (13) was read from the graph as shown in FIG. 3 and used as the stress relaxation time (seconds). However, the stress relaxation time was measured with the start time of elongation to 100% elongation as 0 second.

S3 (cN) = (S1-S2) / 5 + S2 ... Equation (13)

S3: Relaxation stress S1: Stress (cN) reached when elongation is further extended to 100% after repeated elongation recovery tests with elongations of 0% to 300%.
S2: Stress (cN) after repeating the elongation recovery test with an elongation of 0% to 300% twice, further extending to an elongation of 100%, and holding it as it is for 600 seconds.

[Example 1]
1800 g (1.00 mol) of polytetramethylene ether glycol having a number average molecular weight of 1800 and 392 g (1.57 mol) of 4,4′-diphenylmethane diisocyanate are reacted by stirring at 60 ° C. for 3 hours in a dry nitrogen atmosphere. A urethane prepolymer having an isocyanate terminal was obtained. After cooling this to room temperature, 10 g (0.04 mol) of additional 4,4'-diphenylmethane diisocyanate and 2692 g of dimethylacetamide were added and stirred at room temperature to obtain a uniform prepolymer solution.

On the other hand, a solution prepared by dissolving 36.5 g (0.61 mol) of ethylenediamine as a diamine and 4.3 g (0.059 mol) of diethylamine as a terminal terminator in 2663 g of dimethylacetamide was rapidly added to the prepolymer solution. The mixture was added all at once with stirring and further reacted at room temperature for 1 hour to obtain a polyurethane solution.

Further, in the polyurethane solution immediately after polymerization, 1% by weight of a condensate of p-cresol, dicyclopentadiene and isobutylene as an additive was added to the polyurethane polymer solid content, 2- [2-hydroxy-3,5-bis (α). , Α-Dimethylbenzyl) phenyl] -2H-benzotriazole was added in an amount of 0.2% by weight based on the polyurethane polymer solid content, and hydrotalcite was added in an amount of 0.3% by weight based on the polyurethane polymer solid content. A polyurethane solution was obtained. The polyurethane solution to which the additive was added was defoamed at room temperature under reduced pressure to obtain a spinning stock solution.

This undiluted spinning solution is discharged using a spun spout in an atmosphere of a heated nitrogen gas temperature of 270 ° C. directly under the spun spout, and wound under the condition of a speed ratio of 1.3 between the first godette roller and the winder. After applying an oil agent containing dimethyl silicon as a main component at a speed of 500 m / min, the bobbin was wound to obtain 620 dt (72 filaments) of polyurethane elastic fiber.

From this polyurethane elastic fiber, the gather member of Example 1 is produced according to the method described in the above "<< Production example of gather member >>", and according to the method described in the above "<< Evaluation method of gather member >>". The wearing feeling of the gather member and the physical properties of the polyurethane elastic fiber extracted from the gather member were evaluated. As a result, the detachability was ⊚, the fit was ◯, and the fit durability was ◯. Further, (a) the stress at the time of 300% elongation at the third repetition of the 300% elongation recovery repeated test was 0.120 cN / dt, (b) the 200% stress retention rate at the third repetition was 68%, and (c) the repetition 3 The second residual strain was 33%, and (d) the stress relaxation time was 92 seconds.

As a result of NMR measurement of the polyurethane elastic fiber extracted from the gather member of Example 1, the spectrum of FIG. 2 was obtained. The heights F1, F2, and F3 of the integration curves corresponding to f1, f2, and f3 in FIG. 2 were 7.16, 9.03, and 2.18, respectively. The average number of repetitions m of the soft segment portion and the average number of repetitions n of the hard segment portion obtained from these were 2.79 for m and 3.33 for n from the above equations (9) and (10). That is, the number average molecular weight M _s of the soft segment portion and the number average molecular weight M _h of the hard segment portion of this polyurethane urea were 5050 for M _{s and} 710 for M _h from the above formulas (11) and (12). .. Further, since M _s is 5080 and M _h is 740 obtained from the above formula (1) and the above formula (4) from the raw material charge amount, the value obtained by the NMR measurement is calculated from the raw material charge amount. It showed a good match with the value.

[ Reference example 2]
When the polyurethane solution produced with the raw materials and the charging ratio shown in Table 1 below was wound by the same method as in Example 1, the speed ratio between the first Godet roller and the winder was set to 1.6. Spinning was carried out in the same manner as in Example 1 except that 620 dt (72 filaments) of polyurethane elastic fiber was obtained. Further, a gather member was produced in the same manner as in Example 1, and the detachability, fit, fit durability of the gather member, physical property evaluation of the elastic fibers constituting the gather, and analysis by NMR were performed. The results are shown in Tables 1 and 2 below.

[Example 3 , Reference Examples 4 and 5, and Comparative Examples 1 to 6]
A polyurethane solution prepared by the same method as in Example 1 with the raw materials and the charging ratios shown in Table 1 below was spun by the same method as in Example 1 to obtain 620 dt (72 filaments) of polyurethane elastic fibers. Further, in the same manner as in Example 1, a gather member was produced, and the detachability, fit, fit durability of the gather member, physical property evaluation of the elastic fibers constituting the gather, and analysis by NMR were performed. The results are shown in Tables 1 and 2 below.

The gather member of the present embodiment is used as a base material for absorbent articles such as sanitary napkins and disposable disposable diapers, and medical materials such as masks and bandages, so that it is easy to put on and take off and has good long-term fit. It is possible to obtain a product that does not easily slip off.

Claims (5)

A gather member containing elastic fibers, wherein the elastic fibers contained in the gather members are the following (a) to (d):
(A) The stress (cN / dT) at the time of the third repeated 300% elongation in the 300% elongation recovery repeated test is 0.050 or more and 0.150 or less.
(B) The 200% stress retention rate (%) of the third repetition in the 300% extension recovery repetition test is 65 or more and 95 or less.
(C) The residual strain (%) after the third repetition in the 300% stretch recovery repetition test was 42 or less.
(D) stress relaxation time (in seconds) is Ri der 70 or more 93 or less,
(E) Polyurethane elastic fiber
(F) The molecular weight of the soft segment of the polymer constituting the elastic fiber is 4850 or more and 5800 or less.
(G) Molecular weight of the hard segment of the polymer constituting the elastic fiber meets <br/> be 700 or more 780 or less,
The stress relaxation time (seconds) was 100 mm / min and elongation 0% to 300% with respect to the elastic fiber after air drying with a sample length of 10 mm under the condition of 20 ° C. and relative humidity of 65%. The stretch recovery test was carried out twice, and then the ultimate stress when the elastic fiber was stretched to 100% elongation at a rate of 100 mm / min was set to S1 (cN), and then maintained at 100% elongation. When the stress after 600 seconds is S2 (cN), the following formula:
S3 (cN) = (S1-S2) / 5 + S2
A gather member which means the time (seconds) for reaching the relaxation stress S3 (cN) calculated in . The gather member according to claim 1, wherein the elastic fiber is a polyurethane elastic fiber containing a polytetramethylene ether glycol, an organic diisocyanate compound, and an active hydrogen atom-containing compound that reacts with an isocyanate group as a constituent unit. The gather member according to claim 1 or 2 , wherein the fineness of the elastic fiber per filament is 5.0 dt or more and 20.0 dt or less. An absorbent article having the gather member according to any one of claims 1 to 3 . A medical product having the gather member according to any one of claims 1 to 3 .

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