JP2652319B2 - Biodegradable disposable diapers - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a disposable diaper using a biodegradable polyester resin nonwoven fabric as a liquid-permeable surface material and a leak-proof backing material, and has a sufficient mechanical strength, flexibility and waterproofness. The present invention relates to a disposable diaper that is not only excellent in breathability and texture, but also has a biodegradable overall diaper.

[0002]

2. Description of the Related Art In recent years, disposable diapers have become very popular, and their quality requirements have become increasingly diverse.

[0003] The constitution of these disposable diapers has been variously improved with the passage of time, but most of them are fluff pulp containing a liquid-permeable surface portion of a surface in contact with the skin, generally called a cover stock, and a highly absorbent polymer. And a leak-proof backing material for preventing leakage of moisture, generally called a back sheet.

Among these, the liquid permeable surface material used to be made of paper in the past, but at present, most of the nonwoven fabrics are made of a thermoplastic resin by a thermal bonding method or a spun bonding method.

The leak-proof backing material is leak-proof (waterproof), flexible, and has moisture permeability to allow moisture inside the diaper to escape to the outside. What is not required is required.

Conventionally, plasticized polyvinyl chloride, low-density polyethylene, polypropylene, polyurethane, ethylene-vinyl acetate copolymer,
A film such as an ethylene- (meth) acrylate copolymer or a filler obtained by mixing and stretching a filler such as calcium carbonate into the film and forming a fine pore is mainly used as a matte-type embossed film. .

Accordingly, although the liquid absorbing material made of fluff pulp is biodegradable, the liquid permeable surface material and the leak-proof backing material do not have biodegradability. However, these materials do not rot and remain as they are. If this complete treatment is desired, it has been necessary to incinerate the whole, or separately treat the topsheet layer by removing the liquid-permeable surface material and the leakproof backing material.

[0008]

SUMMARY OF THE INVENTION The present invention provides a biodegradable liquid-permeable surface material and a leak-proof backing material which are excellent in mechanical strength, flexibility, texture, waterproofness, productivity and productivity. It is intended to develop a biodegradable disposable diaper in combination, further development of a biodegradable disposable diaper imparted breathability without reducing the waterproofness of the diaper,
Another object of the present invention is to develop a diaper having a topsheet layer that is extremely comfortable.

[0009]

The present invention provides: (1) a fat obtained by reacting a coupling agent with a liquid-absorbent material and an aliphatic saturated polyester prepolymer whose terminal group is substantially a hydroxyl group. A biodegradable disposable diaper obtained by combining a liquid permeable surface material comprising an aliphatic polyester resin or an aliphatic saturated polyester resin not treated with a coupling agent and a leak-proof backing material; (1) The biodegradable disposable diaper according to (1), which is a nonwoven fabric made of an aliphatic polyester resin, (3) The leakproof backing material is made of a fiber made of an aliphatic polyester resin by a spun bond method and a melt blown method. A disposable diaper according to (1) to (2), wherein the disposable diaper is a nonwoven fabric obtained by mixing or laminating a web.
And (4) dry method, spun bond method, thermal bond method,
In the case of the stitch bond method or the needle punch method, a nonwoven fabric produced from an aliphatic saturated polyester treated with a coupling agent, and in the melt blown method, from an aliphatic polyester resin treated with an coupling agent or an untreated aliphatic saturated polyester resin. A biodegradable disposable diaper according to (1) to (3), wherein a nonwoven fabric obtained by mixing or laminating the produced fiber with a fiber obtained by a spun bond method is used for a liquid-permeable surface material, a diaper side portion and the like. Thereby, the above object was achieved.

In the present invention, the liquid absorbing material only needs to be biodegradable, and may be a highly absorbent polymer used in conventional disposable diapers in fluff pulp or the like.

In the polyester prepolymer for obtaining the aliphatic polyester resin used in the present invention, the terminal group obtained by reacting glycol with an aliphatic dibasic acid or its anhydride is substantially a hydroxyl group, It is a saturated aliphatic polyester having a relatively high molecular weight having a number average molecular weight of 5,000 or more, preferably 10,000 or more, and a melting point of 60 ° C. or more.

When the number average molecular weight is less than 5,000,
Even with a small amount of the coupling agent of 0.1 to 5 parts by weight, a polyester having good physical properties cannot be obtained. A polyester prepolymer having a number average molecular weight of 5,000 or more can synthesize a high molecular weight polyester by using a small amount of a coupling agent even under severe conditions such as a molten state without generating a gel during the reaction.

The glycols used include, for example, ethylene glycol, 1,4-butanediol, 1,6
-Hexanediol, decamethylene glycol, neopentyl glycol, 1,4-cyclohexanedimethanol and the like. Ethylene oxide can also be used. These glycols may be used in combination.

The aliphatic dibasic acids or their acid derivatives which react with glycols to form aliphatic polyesters include succinic acid, adipic acid, suberic acid, sebacic acid,
There are lower alcohol esters such as dodecanoic acid, succinic anhydride, adipic anhydride and dimethyl ester, which are commercially available and can be used in the present invention. These aliphatic dibasic acids or their acid derivatives may be used in combination.

These glycols and dibasic acids are mainly composed of aliphatic compounds, but may be used in combination with small amounts of other components, for example, trifunctional or tetrafunctional polyhydric alcohols, oxycarboxylic acids and polycarboxylic acids. preferable.

The trifunctional polyhydric alcohol component is typically trimethylolpropane, glycerin or its anhydride, and the tetrafunctional polyhydric alcohol component is pentaerythritol.

As the trifunctional oxycarboxylic acid, malic acid is practically advantageous, and citric acid is practical because a commercially available tetrafunctional oxycarboxylic acid component can be easily obtained at low cost.

As the trifunctional polyvalent carboxylic acid (or acid anhydride) component, for example, trimesic acid, propanetricarboxylic acid and the like can be used, but trimellitic anhydride is advantageous in practical use.

Examples of the tetrafunctional polycarboxylic acid (or an acid anhydride thereof) include pyromellitic anhydride, benzophenonetetracarboxylic anhydride, cyclopentanetetracarboxylic anhydride and the like.

The proportion of the polyfunctional component used is such that the number of moles of any of the glycol component, aliphatic (including cycloaliphatic) component and dicarboxylic acid (or acid anhydride) component is 10%.
5 mol% or less in the case of a trifunctional component with respect to 0 mol%,
It is preferably 0.5 mol% or more and 3 mol% or less, and in the case of a tetrafunctional component, 3 mol% or less, preferably 0.2 mol%.
Not less than 2 mol%.

If the proportion of the trifunctional component is more than 5 mol%, or if the proportion of the tetrafunctional component is more than 3 mol%, the risk of gelling during the esterification reaction is significantly increased.

The polyester prepolymer for aliphatic polyester used in the present invention has a terminal group substantially a hydroxyl group. For this purpose, glycols and dibasic acids (or acid anhydrides thereof) used in the synthesis reaction are used. The proportion used requires the use of some excess of glycols.

In order to synthesize a polyester prepolymer having a relatively high molecular weight, it is necessary to use a deglycol-reaction catalyst during the deglycolization reaction following the esterification.

Examples of the glycol removal catalyst include titanium compounds such as acetoacetoyl-type titanium chelate compounds and organic alkoxytitanium compounds.
These titanium compounds can be used in combination. Examples of these include diacetacetoxyoxytitanium (“Nasem Titanium” manufactured by Nippon Chemical Industry Co., Ltd.), tetraethoxytitanium, tetrapropoxytitanium, tetrabutoxytitanium and the like. The use ratio of the titanium compound is 0.001 to 100 parts by weight of the polyester prepolymer.
1 part by weight, desirably 0.01 to 0.1 part by weight.
The titanium compound may be added from the beginning of the esterification, or may be added immediately before the deglycolization reaction.

As a result, the polyester prepolymer usually has a number average molecular weight of 5,000 or more, preferably 10,000.
A material having a melting point of 0 or more and a melting point of 60 ° C. or more can be easily obtained, and it is more preferable that the material has crystallinity.

In order to obtain the aliphatic polyester resin of the present invention, a polyester prepolymer having a number average molecular weight of 5,000 or more, preferably 10,000 or more, whose terminal group is substantially a hydroxyl group, is further added with Coupling agents are used to increase the average molecular weight.

When an aliphatic polyester which is not subjected to a coupling treatment is used, it is not necessary that the terminal group is a hydroxyl group, but it is necessary that the esterification be sufficiently carried out, and the MFR (190 ° C.) is at least 300. ~
A flow characteristic of about 1000 g / 10 minutes is required.

In the coupling treatment, the above polyester prepolymer is reacted with a coupling agent to further produce a high molecular weight aliphatic saturated polyester resin. As the coupling agent, diisocyanate, oxazoline, diepoxy compound, acid anhydride and the like can be used, but diisocyanate is particularly preferable in terms of reactivity, performance of the obtained polyester and the like.

The type of diisocyanate is not particularly limited, and examples thereof include 2,4-tolylene diisocyanate, 2,4-tolylene diisocyanate and 2,6-tolylene diisocyanate.
A mixture with tolylene diisocyanate, diphenylmethane diisocyanate, 1,5-naphthylene diisocyanate, xylylene diisocyanate, hydrogenated xylylene diisocyanate, hexamethylene diisocyanate,
Isophorone diisocyanate or the like can be used,
In particular, hexamethylene diisocyanate is preferred from the viewpoint of the hue of the formed resin, the reactivity when adding polyester, and the like.

When an oxazoline or a diepoxy compound is used as a coupling agent, the hydroxyl group of the prepolymer is reacted with an acid anhydride or the like to convert the hydroxyl group terminal into a carboxyl group before using the coupling agent. It is necessary.

The amount of the coupling agent to be added differs depending on whether it is formed into a film or a non-woven fabric, and when it is formed into a non-woven fabric, it depends on whether a spun bond method or a melt blown method is used. The amount is 0.1 to 5 parts by weight, preferably 0.5 to 3 parts by weight based on parts by weight.

If the amount is less than 0.1 part by weight, the coupling reaction is insufficient. If the amount exceeds 5 parts by weight, gelation is liable to occur.

The addition is desirably carried out under conditions in which the polyester prepolymer is in a uniform molten state and can be easily stirred. It is not impossible to add to the solid polyester prepolymer and melt and mix through the extruder, but inside the aliphatic polyester production equipment,
Alternatively, it is practical to add the polyester prepolymer in a molten state (for example, in a kneader), but the production method is not limited to this.

In particular, when used in the melt blown method, a resin having good flowability treated with a coupling agent or a resin having a low melt viscosity may not be treated with a coupling agent.

When the above-mentioned polyester resin is used for molding the disposable diaper material according to the present invention, a lubricant, a wax agent, a coloring agent, etc., as necessary, in addition to an antioxidant, a heat stabilizer, an ultraviolet absorber, etc. Of course, a crystallization accelerator and the like can be used in combination.

That is, examples of the antioxidant include hindered phenolic antioxidants such as pt-butylhydroxytoluene and pt-butylhydroxyanisole, and sulfur such as distearylthiodipropionate and dilaurylthiodipropionate. Triphenyl phosphite, trilauryl phosphite, trisnonyl phenyl phosphite and the like as antioxidants and heat stabilizers; pt-butylphenyl salicylate and 2-hydroxy-4-methoxybenzophenone as ultraviolet absorbers , 2-hydroxy-4-methoxy-2'-carboxybenzophenone,
2,4,5-trihydroxybutyrophenone and the like; lubricants such as calcium stearate, zinc stearate, barium stearate and sodium palmitate; antistatic agents such as N, N-bis (hydroxyethyl) alkylamine and alkylamine; Alkyl allyl sulfonate, alkyl sulfonate, etc., hexabromocyclododecane, tris- (2,3-dichloropropyl) phosphate, pentabromophenyl allyl ether, etc. as flame retardants, and calcium carbonate, silica, titanium oxide, etc. as inorganic fillers Examples of crystallization promoters such as talc, mica, barium sulfate, and alumina include polyethylene terephthalate and poly-transcyclohexanedimethanol terephthalate.

The liquid-permeable surface material of the present invention uses the biodegradable polyester resin thus obtained as a nonwoven fabric. The leak-proof backing material is used as a film or a non-woven fabric.

When used as a film, it can be formed by a method such as an inflation method or a T-die method as in the case of a normal thermoplastic resin, but in this case, as in the case of other resins, such as calcium carbonate or the like. It is also possible to extrude a mixture containing a filler, form a film, stretch, and emboss a satin finish to provide a leakproof backing material provided with air permeability. The film thickness in this case is also 20
When the thickness is about 50 μm, a biodegradable leakproof backing material having substantially the same mechanical strength, flexibility, waterproofness, and air permeability can be obtained.

However, the air permeability of the film in which the filler is blended and stretched to give fine pores is still insufficient, and considerable stuffiness cannot be avoided. The present invention has also developed a leak-proof backing material which is not only biodegradable but also waterproof and does not impair the waterproofness.

A nonwoven fabric obtained by laminating webs produced from the above polyester resin by a spunbond method (generally 0.3 to 10 d is obtained) and a melt blown method (generally 0.01 to 1 d is obtained) It was found that when used as a leak-proof backing material, it became a biodegradable disposable diaper having no water permeability and air permeability.

The melting properties of the polyester resin of the present invention can be easily changed depending on the molecular weight of the polyester prepolymer and the blending amount of the coupling agent, and the obtained fiber (non-woven fabric) can be easily subjected to thermal bonding. The production of nonwoven fabrics by spunbonding, meltblowning, stitchbonding, needlepunching, etc. can be produced with extremely high productivity.

At this time, the structure of the nonwoven fabric of the leakproof backing material is such that 95 to 50% by weight of the web of the spun bond method and 5 to 50% by weight of the web of the melt blown method are overlapped, or the fibers are mixed on a line. It is preferable to use a non-woven fabric. Nonwoven fabrics using the spunbond method alone have high air permeability and poor waterproofness, while nonwoven fabrics using the meltblown method alone have good waterproofness but low strength, so the thickness of the nonwoven fabric must be increased to have the same strength. Needs come out.

In the case of a nonwoven fabric obtained by blending or laminating the spun bond method and the melt blown method, it is preferable that the melt blown method, which is a thin fiber, is on the inner side (the side in contact with the skin).

The leak-proof backing material has a waterproof pressure of 1000 m.
mH ₂ O or more, moisture permeability 2500~6000g / m ² · ²
4hrs, air permeability 200-1000sec / 100cc
It is preferable to use a non-woven fabric obtained by mixing webs of the spunbond method and the melt blown method. Waterproof pressure is 2000 by using non-woven fabric
mmH ₂ O or more, while being comparable to a film having almost no water permeability, the moisture permeability is set to 2500-600.
0 g / m ² · 24 hrs, air permeability 700 to 900 sec
Since a high value of / 100 cc can be maintained, stuffiness due to the diaper can be significantly reduced, and diaper fogging can be greatly reduced.

On the other hand, as a nonwoven fabric of a liquid-permeable surface material,
When a nonwoven fabric produced from the above polyester resin is used, a thick fiber web, nonwoven fabric, or the like obtained by subjecting the polyester resin of the present invention to a thermal bond method (core-sheath method), a spun bond method, or the like is used.

Both the web and the non-woven fabric are breathable and have little water absorption unlike cotton and pulp-based tissues, so that they have good texture.

Further, a nonwoven fabric made of the polyester resin by a melt blown method and a spun bond method is used for a portion of the liquid permeable surface material which requires particularly water repellency as a side portion. At this time, the melt blown method alone is insufficient in strength, and the spun bond method alone is insufficient in strength, and the water repellency tends to be insufficient due to the thick fiber. When the liquid-permeable surface material and the leak-proof backing material are made of the same polyester resin, thermal bonding becomes extremely simple, and this has the advantage that disposable diapers can be manufactured with high productivity.

Of course, in a disposable diaper, if a waist band other than fluff pulp or elastic is made of the polyester resin, it is of course preferable for biodegradability.

[0049]

According to the present invention, the liquid-permeable surface material of the disposable diaper is made of a biodegradable polyester resin, combined with a biodegradable leak-proof backing material, and the entire diaper is made biodegradable. Also completely solves the problem of environmental destruction.

In particular, by forming the leak-proof backing material further into a nonwoven fabric, air permeability was provided without deteriorating waterproofness, and the diaper was successfully reduced in stuffiness.

Further, a liquid-permeable surface material is manufactured by using the above-mentioned biodegradable polyester resin by a thermal bond (core-sheath method), a web or a nonwoven fabric by a spun bond method, and a diaper can be manufactured by thermal bonding. Improved productivity.

[0052]

The present invention will be described below with reference to examples and comparative examples.

[Resin Synthesis Method] (Resin A) After replacing a 700 L reactor with nitrogen,
183 kg of 4-butanediol and 224 kg of succinic acid were charged. The temperature is raised under a nitrogen stream, and is 192 to 220 ° C.
For 3.5 hours, further stop nitrogen and 20 ~ 2mmHg
The esterification reaction by dehydration condensation was performed for 3.5 hours under reduced pressure. The collected sample has an acid value of 9.2 mg.
/ G, number average molecular weight (Mn) was 5,160, and weight average molecular weight (Mw) was 10,670. Subsequently, 34 g of tetraisopropoxytitanium as a deglycol-reaction catalyst was added under a nitrogen stream at normal pressure. Raise the temperature to 15-0.2 mmHg at a temperature of 215-220 ° C.
The deglycol-reaction was performed under reduced pressure for 5.5 hours.
The collected sample had a number average molecular weight (Mn) of 16,80.
0 and the weight average molecular weight (Mw) was 43,600. The yield of this polyester prepolymer, excluding condensed water, was 339 kg.

In a reactor containing 339 kg of the polyester prepolymer, 5.42 of hexamethylene diisocyanate was added.
Kg was added, and a coupling reaction was performed at 180 to 200 ° C. for 1 hour. The viscosity increased rapidly but no gelling occurred. Next, Irganox 101 was used as an antioxidant.
1.70 kg (Ciba-Geigy) and 1.70 kg of calcium stearate as a lubricant were added, and the mixture was further stirred for 30 minutes.

The reaction product was extruded into water by an extruder and cut into a pellet by a cutter. 90
The yield of the polyester resin after vacuum drying at 60 ° C. for 6 hours was 300 kg.

The obtained aliphatic saturated polyester resin A is a slightly ivory white wax-like crystal having a melting point of 110 ° C., a number average molecular weight (Mn) of 35,500 and a weight average molecular weight (Mw) of 170,000. , MFR (190
° C) is 1.0 g / 10 min, temperature is 190 ° C, shear rate is 10
The melt viscosity at ⁰ sec ^-1 was 1.5 × 10 ⁴ poise.

The average molecular weight can be measured by using Shodex GP.
C System-11, solvent: CF ₃ COONa 2 mmol solution of hexafluoroisopropyl alcohol, concentration 0.1% by weight, calibration curve: Showa Denko KK PMMA standard sample Shodex Standard M-75
I went in.

(Resin B) A 700 L reactor was purged with nitrogen, and then 200 kg of 1,4-butanediol, 250 kg of succinic acid and 2.84 kg of trimethylolpropane were charged. The temperature is raised under a nitrogen stream, and is 192 to 220 ° C.
For 3.5 hours, further stop nitrogen and 20 ~ 2mmHg
The esterification reaction by dehydration condensation was performed for 3.5 hours under reduced pressure. The collected sample has an acid value of 2.5 mg
/ G, the number average molecular weight (Mn) was 8,660, and the weight average molecular weight (Mw) was 9,520. Subsequently,
37 g of tetraisopropoxytitanium as a catalyst was added under a nitrogen stream at normal pressure. Raise the temperature and increase the temperature to
A deglycol-reaction was performed at 0 ° C. under a reduced pressure of 15 to 0.3 mmHg for 8.0 hours. The collected sample had a number average molecular weight (Mn) of 16,200 and a weight average molecular weight (M
w) was 67,900. The yield of this polyester prepolymer, excluding condensed water, was 367 kg.

A reactor containing 367 kg of the polyester prepolymer was charged with 330 g of hexamethylene diisocyanate.
Was added and a coupling reaction was performed at 170 to 185 ° C. for 1 hour. The viscosity increased rapidly but no gelling occurred. Next, Irganox 1010 was used as an antioxidant.
(Ciba Geigy) and 370 g of calcium stearate as a lubricant were added, and stirring was further continued for 30 minutes.

The reaction product was extruded into water with an extruder, and cut into a pellet by a cutter. 90
The yield of the polyester resin after vacuum drying at 6 ° C. for 6 hours was 360 kg.

The obtained aliphatic saturated polyester resin B is a slightly ivory white wax-like crystal having a melting point of 110 ° C., a number average molecular weight (Mn) of 25,600 and a weight average molecular weight (Mw) of 122,000. , MFR (190
° C) is 18 g / 10 min, temperature is 190 ° C, and shear rate is 100.
The melt viscosity at sec ^-1 was 4.0 × 10 ⁴ poise.

The measurement of the average molecular weight was carried out using Shodex GP.
C System-11, solvent: CF ₃ COONa 2 mmol solution of hexafluoroisopropyl alcohol, concentration 0.1% by weight, calibration curve: Showa Denko KK PMMA standard sample Shodex Standard M-75
I went in.

(Resin C) A 700 L reactor was purged with nitrogen, and then 196 kg of 1,4-butanediol and 204 kg of succinic acid were charged. The temperature was increased under a nitrogen stream, and 19
5.0 hours at 0 to 220 ° C.
The esterification reaction by dehydration condensation was performed for 3.5 hours under reduced pressure of ２2 mmHg. The collected sample had an acid value of 8.5 mg / g and a number average molecular weight (Mn) of 5,20.
0, and the weight average molecular weight (Mw) was 10,100. Subsequently, 30 g of tetraisopropoxy titanium as a catalyst was added under a nitrogen stream at normal pressure. Raise the temperature,
A deglycol-reaction was performed at a temperature of 215 to 220 ° C. under a reduced pressure of 5 to 0.2 mmHg for 15 hours. The collected sample had a number average molecular weight (Mn) of 23,300 and a weight average molecular weight (Mw) of 89,300. This polyester prepolymer has a theoretical yield of 327 K excluding condensed water.
g.

327 kg of the polyester prepolymer was added to 1
After cooling to 80 ° C., 41 g of phosphorous acid as a coloring inhibitor, 327 g of Irganox B225 (manufactured by Ciba Geigy) as an antioxidant and 327 g of calcium stearate as a lubricant were added to the reactor, and stirring was continued for another 30 minutes. Was. This reaction product was extruded into water with an extruder and cut into a pellet by a cutter. 90 ° C
The yield of the polyester resin C after vacuum drying for 6 hours was about 310 kg.

The obtained aliphatic saturated polyester resin C
Is a white solid crystal having a melting point of 120 ° C., a number average molecular weight (Mn) of 23,100, and a weight average molecular weight (Mw) of 9
0,500, MFR (190 ° C) is about 500g / 10
Min, the viscosity of a 10% solution of orthochlorophenol is 20
The melt viscosity at a poise temperature of 190 ° C. and a shear rate of ^{1 to} 10 sec ⁻¹ was 100 poise (Tokimec, rotational viscometer). The average molecular weight is measured by Shodex G
PC System-11 (Gel chromatography manufactured by Showa Denko KK), the solvent was HFIPA of CF ₃ COONa
A 5 mmol solution, a concentration of 0.1% by weight, and a calibration curve are PMDA standard sample ShodexStand manufactured by Showa Denko KK
ard M-75.

(Resin D) After replacing the reactor of 700 L with nitrogen, 222.5 kg of 1,4-butanediol and 277.5 kg of succinic acid were charged. The temperature was raised under a nitrogen stream, and the esterification reaction by dehydration condensation was performed at 195 to 210 ° C. for 5.0 hours, and further with the nitrogen stopped, under a reduced pressure of 15 to 5 mmHg for 3.5 hours. The collected sample had an acid value of 9.1 mg / g, a number average molecular weight (Mn) of 5,300, and a weight average molecular weight (Mw) of 11,20.
It was 0. Subsequently, 50 g of tetraisopropoxytitanium as a catalyst was added under a nitrogen stream at normal pressure. Raise the temperature to 5 to 0.2 mmH at a temperature of 215 to 220 ° C.
The glycol was subjected to a deglycol-reaction for 7.5 hours under reduced pressure.
The collected sample had a number average molecular weight (Mn) of 17,20.
0 and the weight average molecular weight (Mw) was 58,700. This polyester prepolymer had a theoretical yield of 415.5 Kg excluding condensed water.

The polyester prepolymer 415.5K
Irganox 101 as an antioxidant in a reactor containing g
0 (manufactured by Ciba Geigy), 416 g of calcium stearate as a lubricant, 52 g of phosphorous acid as a coloring inhibitor, and 3.74 kg of hexamethylene diisocyanate are added, and a coupling reaction is performed at 160 to 200 ° C. for 2 hours. Was. The viscosity increased rapidly but no gelling occurred.

The reaction product was extruded into water with an extruder, and cut into pellets with a cutter. 90
The yield of polyester resin D after vacuum drying at 6 ° C. for 6 hours was about 410 kg.

The obtained aliphatic saturated polyester resin D is a white solid crystal having a melting point of 120 ° C. and a number average molecular weight (M
n) is 26,700, the weight average molecular weight (Mw) is 98,
000, MFR (190 ° C.) was 120 g / 10 min, temperature was 190 ° C., and the melt viscosity at a shear rate of ^{1 to} 10 sec ^-1 was 700 poise (Tokimec, rotational viscometer).

The pellets of these resins were dried at 100 to 120 ° C. for 2 to 4 hours using a hot air circulating drier of a dew point control type, and then subjected to molding.

[Inflation Film] Calcium carbonate is blended with resin A, a lip gap of 1.2 mm and a circular die of 300 mmφ are used in a 60 mmφ extruder, blow-up ratio is 3.0 times, and take-up speed is 135 m.
/ Min to give a 30 μm thick blown film and then a satin finished film. Strength is 65 in MD direction
0 kg / cm ^2, the TD 670 kg / cm ^2, elongation MD direction 660%, was the TD direction 790%.

[Spunbond-Meltblown Nonwoven Fabric] A nonwoven fabric forming apparatus capable of forming a spunbond nonwoven fabric and a meltblown nonwoven fabric in an in-line type manufacturing process was used. In the spun bond method, the resin B is diced to a die width of 100.
65m with 0mmφ, 200 holes x 5 rows of dies
Use an extruder with mφ. In the melt blown method, a resin C is used as a high-speed jet gas flow using a 40 mmφ extruder equipped with a die of 1000 holes × 1 row at a pitch of 1 mm.
Superheated steam of 5 kg / cm ² G was used. The filament spun by the spunbond method was deposited on a collect conveyor, and pressed by a pair of hot press devices consisting of a flat roll and an engraving roll to obtain a spunbond nonwoven fabric. The spunbond-meltblown nonwoven fabric is produced by spinning, blending, depositing, and transporting meltblown filaments ejected onto a web of spunbond filaments being conveyed by a collect conveyor, and pressed into contact with the hot press apparatus to form SBs. -An MB mixed nonwoven fabric was used.

[Thermal Bonded Nonwoven Fabric]
Using a 40 mmφ extruder equipped with a 6 mmφ, 68 hole multifilament nozzle, continuously extruding, stretching,
The drawn yarn was crimped and cut into a length of 52 mm to obtain a staple fiber. 3. As a single fiber
3 denier, strength 42 g / d, elongation 43%. This cotton was deposited with a cutting machine, formed into a web, and pressed with a calender roll to obtain a thermally bonded nonwoven fabric.

[Sewing of a diaper] A superabsorbent polymer was placed in fluff pulp, and a walnut liquid absorbing portion was made with absorbent paper. A film or a non-woven fabric was attached to the front and rear surfaces of the liquid absorbing material to form a diaper.

Example 1 A fluff pulp containing a resin B as a liquid-permeable surface material, a spunbond nonwoven fabric having a basis weight of 20 g / m ² and a thickness of 0.19 mm, and a superabsorbent polymer as a liquid absorbing material And a resin A as a leak-proof backing material, and a 30 μm-thick inflation film was combined to obtain a biodegradable disposable diaper. The performance of the materials used is shown in Table 1. Artificial urine 200 for this diaper
After absorbing the cc, the soil was buried in the soil, and after three months, the whole was almost completely corroded and decomposed.

Example 2 Resin B was used as a liquid-permeable surface material, a non-woven fabric of a thermal bond method having a basis weight of 20 g / m ² and a thickness of 0.22 mm was used. The same as was used. The performance of the materials used is shown in Table 1. When the soil was buried in the soil in the same manner as in Example 1, the whole was almost decomposed three months later.

Example 3 A thermal bond web made of resin B having a basis weight of 45 g / m ² was used as a leak-proof backing material.
A melt-blown web having a basis weight of 15 g / m ^{2 made} of resin C is laminated and pressed with an embossing roll to obtain a basis weight of 60 g / m ^2.
A disposable diaper was prepared in the same manner as in Example 2 except that a nonwoven fabric having a thickness of m ² and a thickness of 0.5 mm was used. The performance of the materials used is shown in Table 1. This diaper was also subjected to the same biodegradability test as in Example 1 and found to be almost completely corroded and decomposed in three months.

Example 4 A melt-blown web of 15 g / m ² of resin D was mixed and deposited on a spunbond web of 45 g / m ² of resin B as a leak-proof backing material. And a disposable diaper was prepared in the same manner as in Example 1 except that a nonwoven fabric having a basis weight of 60 g / m ² was used. The performance of the materials used is shown in Table 1.
This diaper was also subjected to the same biodegradability test as in Example 1 and found to be almost completely corroded and decomposed in three months.

(Example 5) As a liquid-permeable surface material, a melt-blown web made of resin C having a basis weight of 2 g / m ² was mixed and deposited on a spunbonded web made of resin B having a basis weight of 18 g / m ^2. , Which are pressed against each other and have a basis weight of 20 g /
except for using m ² of non-woven fabric was prepared disposable diaper in the same manner as in Example 1. The performance of the materials used is shown in Table 1. When the same diaper was subjected to the same biodegradability test as in Example 1, it was almost completely corroded and decomposed in 3 months.

[0080]

[Table 1]

[0081]

According to the present invention, a biodegradable thermoplastic film or the like is used as a liquid-permeable surface material and a leak-proof backing material of a disposable disposable diaper. Despite using certain materials,
The biodegradability of the diaper as a whole was lost, and it was impossible to adopt disposal methods such as burying in soil. Therefore, the only way to complete the treatment is by incineration, which is a burden on incineration plants that have insufficient capacity.

The present invention solves such a problem by reacting a coupling agent with a saturated polyester prepolymer having a substantially hydroxyl group terminal group as a raw material for a liquid-permeable surface material and a leak-proof backing material. By using a liquid-permeable surface material and a leak-proof backing material composed of an aliphatic saturated polyester resin or an aliphatic saturated polyester resin not subjected to a coupling treatment with the resin, the entire diaper was successfully made biodegradable. Things.

These materials can also be used as a nonwoven fabric obtained by blending or laminating a web produced from the polyester resin by a spun bond method or a melt blown method, so as to improve the air permeability of the diaper as a whole without impairing the biodegradability and waterproofness. It has been greatly improved, and has succeeded in reducing stuffiness caused by diapers.

The liquid-permeable surface material and leak-proof backing material produced from the polyester resin can be combined with a conventional liquid-absorbing material to provide not only biodegradability, air permeability and waterproofness but also mechanical strength. It is excellent in flexibility, texture, etc., and has good thermal bonding and heat setting properties, and can produce biodegradable disposable diapers with high productivity.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Takashi Fujimaki 634-4-442, Nobamachi, Konan-ku, Yokohama-shi, Kanagawa Prefecture (72) Inventor Eiichiro Takiyama 4-12-4, Nishi-Kamakura, Kamakura-shi, Kanagawa (56) References JP-A-6-248551 (JP, A) JP-A-4-57953 (JP, A) JP-A-6-248510 (JP, A) JP-A-6-248511 (JP, A) JP-B-60-11148 (JP, B2)

Claims (4)

(57) [Claims] 1. A liquid absorbent material and end groups substantially hydroxyl groups at which aliphatic saturated polyester aliphatic obtained prepolymer is reacted with a coupling agent to the polyester resin or the polyester resin and the coupling agent A biodegradable disposable diaper characterized by combining a liquid-permeable surface material comprising an untreated aliphatic saturated polyester resin and a leak-proof backing material. 2. The biodegradable disposable diaper according to claim 1, wherein the leak-proof backing material is a nonwoven fabric made of an aliphatic polyester resin. 3. The nonwoven fabric according to claim 1 , wherein the leakproof backing material is a nonwoven fabric obtained by mixing or laminating a fiber made of an aliphatic polyester resin by a spunbond method and a web made by a meltblown method. Disposable diapers. 4. A nonwoven fabric produced from an aliphatic saturated polyester treated with a coupling agent in a dry method, a spun bond method, a thermal bond method, a stitch bond method or a needle punch method, and a coupling agent in a melt blown method. fiber produced from the treated aliphatic polyester resin or untreated aliphatic saturated polyester resin
The biodegradable disposable diaper according to any one of claims 1 to 3, wherein a nonwoven fabric obtained by blending or laminating fibers with fibers obtained by a spun bond method is used for a liquid-permeable surface material, a diaper side portion and the like.