JPH0649048B2 - How to make disposable diapers - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing a disposable diaper.

[Prior Art] Disposable disposable diapers are manufactured by bonding a polyethylene film and a non-woven fabric with an adhesive so that a water absorbing material is sandwiched between them, or a urethane film forming a gather is bonded with an adhesive. .

From the viewpoint of safety, such an adhesive is preferably a non-solvent type and a hot melt type. To bond the polyethylene film and the non-woven fabric together, for example, a hot melt adhesive containing a block copolymer of styrene and isoprene as a base polymer is used. Further, JP-A-60-158284 discloses a disposable diaper using a hot melt adhesive containing a block copolymer of styrene and butadiene as a base polymer.

[Problems to be Solved by the Invention]

A hot melt adhesive using a block copolymer composed of styrene and isoprene as a base polymer has poor heat stability. Therefore, this adhesive has a problem that its physical properties are deteriorated by heating for bonding, and it is subject to many restrictions when it is used for manufacturing a disposable diaper.

An adhesive containing a block copolymer composed of styrene and butadiene as a base polymer has good heat stability and weather resistance, but has poor adhesiveness, and therefore is used in applications where retention is required, such as laminating urethane films. There is a problem that it cannot be used for. Therefore, an adhesive that bonds the polyethylene sheet and the non-woven fabric,
There is also a problem that it is necessary to use a separate adhesive from an adhesive to which a urethane film or the like is attached in order to form the stretchable portion.

In view of the above, it is an object of the present invention to provide a method for manufacturing a disposable diaper that can reduce the types of hot melt adhesives used and can prevent the physical properties of the adhesives from being deteriorated.

[Means for Solving the Problems]

This invention relates to the production of a paper diaper by laminating, at least laminating elastic materials, styrene-butadiene block copolymer having a styrene content of less than 35% by weight, 15 to 40% by weight of the whole adhesive, and a tackifying resin. 35 to 70% by weight of the whole adhesive, a softener 5 to 30% by weight of the whole adhesive, and a wax 0% of the whole adhesive.
It is carried out by using a hot melt adhesive which is contained in each proportion of ˜20% by weight.

[Action]

In the paper diaper manufacturing method of the present invention, at least the bonding of the elastic material among the bonding of the water-permeable material, the water-impermeable material, the water-absorbing material and the elastic material is performed with a specific hot melt adhesive. It is possible to prevent the deterioration of the physical properties of the adhesive by keeping the bonding of the stretchable materials against the contraction due to the rubber-like elasticity. Also, other laminating can be done with the hot melt adhesive.

〔Example〕

FIG. 1 shows an example of an apparatus used for carrying out a method for continuously producing disposable diapers when the method for producing disposable diapers according to the present invention is a method. Fig. 2 shows a paper diaper in the process of being manufactured.
It is shown in three stages, and Fig. 3 (a) shows its CC cross section in
FIG. 3B shows the DD cross section, and FIG. 3C shows the EE cross section. Hereinafter, although detailed description will be given with reference to these drawings, the present invention is not limited to the following embodiments.

Tissue 2 is continuously supplied from roll 1. The water absorbing material 3 is placed on one surface of the tissue 2. Tissue 32 is continuously supplied from the roll 31 to cover the water absorbing material 3.

As shown in Part I of FIG. 2, the polyethylene film 2
In the width direction of 0, the hot melt adhesive 22 is applied in a line segment shape to the portion where the stretchable material 9 is fitted, and the hot melt adhesive 42 is applied in a multi-bead shape to the other portions. . In FIG. 1, 19 is a gun for applying the hot melt adhesive 22 for gathers, and 23 is a gun for applying the hot melt adhesive 42.

The polyethylene film 20 and the tissue 2 are bonded together with a hot melt adhesive 42 so that the polyethylene film 20 covers the lower tissue 2 and protrudes on both sides thereof. Polyethylene film 20 is roll 2
It is continuously supplied from 1.

The non-woven fabric 4 is attached to the tissue 32 with the hot-melt adhesive 42 so as to cover the tissue 32 and the stretchable material 9, and is also attached to the polyethylene film 20. This non-woven fabric 4 is a roll 5
It is continuously supplied from. The non-woven fabric 4 is the side that comes into contact with the skin when using a disposable diaper. In FIG. 1, reference numeral 6 is a hot melt adhesive application gun. Of the width direction of the non-woven fabric 4,
Like the polyethylene film 20, the hot melt adhesive 22 is applied in a line segment shape to the portion where the stretchable material 9 is fitted, and the hot melt adhesive 42 is applied in a multi-bead shape to the other portions. .

On the other hand, the elastic material 9 is continuously supplied from the roll 8,
Stretching is performed while receiving tensile stress by the stretching rolls 17 and 18. Stretchable material 9 under this tensile stress
Is adhered to the polyethylene film 20 at both sides of the middle portion in the longitudinal direction of the water absorbent material 3 with a hot melt adhesive 22 for gathers at desired intervals (see part II in FIG. 2).

Nonwoven fabric 4 and polyethylene film 20 as described above
After sticking together, the alternate long and short dash line A,
If you cut as shown by B and F, the tensile force applied to the elastic material will be lost and the elastic part (gather)
It becomes a paper diaper having. The part indicated by III is a disposable diaper 1
It will be enough. The gathers may be provided not only on the crotch but also on the waist.

The polyethylene film 20 is used to prevent water from leaking to the outside when using a disposable diaper.

In the present invention, the hot-melt adhesive is applied to the bonded product in a state of multi-line, multi-dot, etc., as is conventionally done, or a shape corresponding to the shape of the bonded part of the bonded product. It is also applied by. For example, it is applied as one or more streaks or a large number of streaks in a direction along the flow of a production line for disposable diapers or in a direction intersecting this direction. In addition, "streak" here not only refers to only one line,
It also includes a line segment or a sequence of points at certain intervals. Examples of the bonded article to which the hot-melt adhesive is applied include a water-permeable material, a water-impermeable material, a water-absorbing material, and a stretchable material used in a paper diaper.

The water-permeable material is not particularly limited as long as it is a sheet-like material having water permeability, and for example, woven cloth, non-woven cloth, paper and the like are used. Further, it is preferable that the water-permeable material that comes into contact with the skin when using a diaper has a good feel to the skin.

The water-impermeable material is not particularly limited as long as it is a sheet having no water permeability, and for example, a synthetic resin film, a synthetic resin sheet or the like is used.

The water absorbing material is not particularly limited as long as it can absorb water such as urine and sweat, and for example, a super absorbent polymer is used.

The stretchable material is not particularly limited as long as it stretches due to rubber-like elasticity. For example, a urethane film,
Urethane elastic thread or the like is used. The stretchable material may be supplied in a state of being wound around a roll or the like, but the stretchable material production line may be incorporated into the disposable diaper production line. For example, a production line for obtaining a stretchable material by cooling a molten mixture of a hot-melt composition having low tackiness is incorporated into a production line for disposable diapers.

The hot melt adhesive used in the present invention has the following properties and, therefore, has high versatility and can be used as a barrier coat of a disposable diaper. In this way, with one kind of hot melt adhesive, multi-line adhesion (adhesive indicated by 42 in FIG. 2), adhesion of elastic material for gather (adhesive indicated by 22 in FIG. 2), and , A barrier coat such as the two-dot chain line portion G in FIG. 2 can all be applied.

The adhesive strength is much higher than that of a hot melt adhesive containing a styrene-butadiene block copolymer having a styrene content of 35% by weight or more as a base polymer.

The holding power is very strong as compared with a hot melt adhesive containing a styrene-isoprene block copolymer as a base polymer.

The heat stability is superior to that of a hot melt adhesive containing a styrene-isoprene block copolymer as a base polymer.

The styrene-butadiene block copolymer used in the hot melt adhesive must have a styrene content of less than 35% by weight. When the styrene content is 35% by weight or more, the adhesiveness including the initial adhesiveness deteriorates.

As the styrene-butadiene block copolymer having a styrene content of less than 35% by weight, any styrene-butadiene block copolymer may be used as long as the styrene content is such a value, for example, manufactured by Asahi Chemical Industry Co., Ltd. Commercially available products such as TP-042 (styrene-butadiene block copolymer having a styrene content of 20% by weight) are used.

The tackifying resin used for the hot melt adhesive is not particularly limited, and examples thereof include those conventionally used as a tackifying resin for hot melt adhesives and the like. For example, rosin, rosin derivative, polyterpene resin, polyterpene resin derivative, aliphatic hydrocarbon resin, hydrogenated product of this resin,
An alicyclic hydrocarbon resin, a hydrogenated product of this resin, an aromatic hydrocarbon resin, a hydrogenated product of this resin, etc. may be used alone or in combination of two or more. The tackifying resin preferably has a softening temperature (sp) of about 80 to 150 ° C. If the softening temperature is below this range, the heat resistance, especially the holding power, may decrease, and if it exceeds this range, the hot melt adhesive becomes hard and the texture becomes poor, or the melt viscosity becomes too high. I have something to do.

The softening agent used for the hot melt adhesive is not particularly limited, and examples thereof include those conventionally used as a softening agent for hot melt adhesives and the like. For example, naphthenic process oils, paraffinic process oils, animal and vegetable oils and their derivatives, polyolefin low molecular weight polymers, etc. are used alone or in combination of two or more.

The hot melt adhesive used in the present invention contains a wax, if necessary, in order to improve its blocking property and set time. The wax is also not particularly limited, and those conventionally used as hot melt adhesives and the like are used. For example, paraffin wax, microcrystalline wax, Fischer-Tropsch wax and the like are used alone or in combination of two or more.

The hot melt adhesive used in the present invention may contain components other than the above components as long as the object of the present invention is not impaired. For example, an antiaging agent for preventing the aging of the adhesive and other stabilizers are added. Anti-aging agent,
It is not particularly limited, for example, phenolic antioxidant,
Those conventionally used for hot-melt adhesives such as phosphorus-based antioxidants may be used alone or in combination of two or more.

The mixing ratio of the styrene-butadiene block copolymer is
It should be 15-40% by weight of the total adhesive. Above this range, the melt viscosity will be high, making application difficult,
Below this range, sufficient cohesive force cannot be obtained.

The blending ratio of the tackifying resin needs to be 35 to 70% by weight of the entire adhesive. Above this range, it becomes hard and brittle, and below this range, sufficient adhesiveness cannot be obtained.

The blending ratio of the softening agent needs to be 5 to 30% by weight of the entire adhesive. If it exceeds this range, the cohesive force is low and the holding force becomes weak, and if it is below this range, it is hard and the texture becomes poor.

When wax is added, its content is preferably 20% by weight or less based on the whole adhesive. If it exceeds this range, the adhesiveness may be significantly reduced.

When the antiaging agent is added, its compounding ratio is preferably 0.01 to 2% by weight based on the whole adhesive.

When other substances are added, they are preferably used within a range not hindering achievement of the object of the present invention.

The hot melt adhesive is prepared by mixing the composition containing the above components so as to form a uniform mixture. This mixing is performed, for example, by mixing or kneading the composition in a molten state at a temperature of about 120 to 160 ° C.

Hereinafter, more specific examples will be shown together with comparative examples.
The present invention is not limited to the examples below.

Example 1 A styrene-butadiene block copolymer as a base polymer (Super Tack TP-0 manufactured by Asahi Kasei Corporation)
42: Styrene content 20% by weight), 30 parts by weight, and 5 as the tackifying resin, an aliphatic hydrocarbon resin (ESCOLETS 5300 manufactured by Exxon Chemical Co., Ltd., softening point 100 ° C.)
A composition containing 5 parts by weight, 15 parts by weight of naphthenic oil (Shell Rex 371N manufactured by Shell Chemical Co., Ltd.) as a softening agent, and 1 part by weight of hindered phenol (Irganox 1010 manufactured by Ciba-Geigy) as an anti-aging agent was used. A hot melt adhesive was obtained by mixing well in the molten state at 150 ° C. Using this hot melt adhesive, a paper diaper was manufactured in the following manner according to the above method in the apparatus shown in FIG.

Tissue 2,32 separately from two rolls 1,31
Is continuously supplied, and the water absorbing material 3 is supplied to the two tissues 2,
I put it between 32. The polyethylene film 20 is attached onto one tissue 2 with a hot melt adhesive 42 so as to largely stick out, and a urethane elastic thread is used to form stretchable portions on both sides of the water absorbent material 3 with the hot melt adhesive 22.
Pasted together. Hot melt adhesive 42 so that the non-woven fabric 4 is largely projected on the other tissue 32.
The polyethylene film 20 and the non-woven fabric 4 were bonded together with the hot-melt adhesive 42 so as to surround the water-absorbent material 3. A sandwich of tissue 2-water-absorbent material 3-tissue 32 was sandwiched between the polyethylene film 20 and the non-woven fabric 4, and the space between the sandwich bodies (indicated by the chain lines A and B in FIG. 2) was cut. At the same time, both sides of each sandwich were cut into a bay shape (indicated by a chain line F in FIG. 2) to obtain a disposable diaper.

(Example 2) A styrene-butadiene block copolymer as a base polymer (Super Tack TP-0 manufactured by Asahi Kasei Corporation)
42: Styrene content 20% by weight), 35 parts by weight, and 45% aliphatic hydrocarbon resin (Arcon M-100 manufactured by Arakawa Chemical Industry Co., Ltd., softening point 100 ° C.) as a tackifying resin.
10 parts by weight of naphthenic oil (Shell Chemical Co., Ltd. Shelf Rex 371N) as a softening agent, and 10 parts by weight of paraffin wax (Nippon Seiwa Co., Ltd. paraffin wax 140, melting point 61 ° C.) as a softening agent,
A composition containing 1 part by weight of hindered phenol (Irganox 1010 manufactured by Ciba Geigy) as an anti-aging agent was well mixed in a molten state at a temperature of 150 ° C. to obtain a hot melt adhesive. Using this hot melt adhesive, a paper diaper was produced in the same manner as in Example 1.

(Comparative Example 1) A styrene-isoprene block copolymer (Kreton TR-110 manufactured by Shell Chemical Co., Ltd.) was used as a base polymer.
7) 30 parts by weight, an aliphatic hydrocarbon resin (ESCOLETS 5300 manufactured by Exxon Chemical Co., Ltd., as a tackifying resin,
A composition containing 55 parts by weight of a softening point of 105 ° C., 15 parts by weight of a naphthenic oil as a softening agent, and 1 part by weight of hindered phenol (Irganox 1010 manufactured by Ciba-Geigy) as an antiaging agent in a molten state at a temperature of 150 ° C. And mixed well to obtain a hot melt adhesive. Using this hot melt adhesive, a paper diaper was produced in the same manner as in Example 1.

(Comparative Example 2) 20 parts by weight of a styrene-butadiene block copolymer (Sterone 840A manufactured by Firestone, 43% by weight of styrene) as a base polymer, and a modified terpene resin (Zona Tack manufactured by Arizona Chemical Co., Ltd.) as a tackifying resin. 105 lights, softening point 100 ° C.) 60 parts by weight, naphthene-based process oil (Shell Chemical Co., Ltd. Shelf Rex 371N) 20 parts by weight as a softening agent, hindered phenol as an anti-aging agent (Ciba-Geigy Irganox 1010) At a temperature of 150.
The mixture was mixed well in the molten state at ℃ to obtain a hot melt adhesive. Using this hot melt adhesive, a paper diaper was produced in the same manner as in Example 1.

The adhesive strength, creep characteristics, and heating stability of each hot melt adhesive were examined as follows, and the results are shown in Table 1.

The adhesive strength is determined by using the device (machine) shown in FIG. 1 (paper amount: 0.05 g / m · bead, application temperature: 130).
℃) MD direction (machine running direction) width 30mm, length 1
It was cut into 00 mm (3 beads), and its peel strength was measured by measuring with an autograph manufactured by Shimadzu at RT (room temperature). The pulling speed was 100 mm / min.

Creep characteristics are determined by using the device (machine) shown in FIG. 1 for a paper diaper (coating thickness 15 μm, coating temperature 150 ° C.).
The urethane elastic yarn is attached at a draw ratio of 2 times. )
The gathered portion was cut off, fixed in a completely stretched state, and the peeling (returning) distance of the urethane elastic yarn after 40 ° C. for 10 hours was measured and calculated by the following formula.

Here, L is the extended total length, S is the draw ratio, and Δl is the peeled distance.

About the heating stability, about 200 g of hot melt adhesive was put in a glass beaker, covered with aluminum foil, left in a constant temperature bath at 180 ° C, and skin was peeled and color change was observed every predetermined time. Was measured. Then, the rate of change in viscosity was obtained from the following formula.

As can be seen from Table 1, the paper diapers of Examples 1 and 2 were good in the adhesive strength, the creep characteristics and the heating stability of the hot melt adhesive used. Therefore, it was possible to bond the water-permeable material, the water-impermeable material, the water-absorbing material and the stretchable material with one kind of hot melt adhesive. In the paper diapers of Comparative Examples 1 and 2, the hot melt adhesive used had poor adhesive strength, creep properties and heat stability. For this reason,
The stretchable material was easy to peel off and I had to use another hot melt adhesive.

〔The invention's effect〕

In the method for producing the disposable diaper of the present invention, at least the stretchable material is bonded with a specific hot melt adhesive, so that the physical properties of the adhesive are prevented from being deteriorated and the number of kinds of the adhesive to be used is reduced. .

[Brief description of drawings]

FIG. 1 shows an apparatus 1 for carrying out the method for producing a disposable diaper according to the present invention.
A schematic diagram showing an example, Fig. 2 is an explanatory diagram showing a disposable diaper in three stages in the process of manufacture, Fig. 3 (a) is a partial view of the CC cross section, and Fig. 3 (b) is its D-D. Partial view of section, FIG. 3
(c) is a partial view of the EE cross section. 2, 32 ... Tissue as water-permeable material, 3 ... Water-absorbing material,
4 ... Nonwoven fabric as water permeable material, 9 ... Stretchable material, 20 ... Polyethylene film as water impermeable material, 22 ... Hot melt adhesive, 42 ... Hot melt adhesive

Claims (1)

[Claims] 1. When manufacturing a paper diaper by laminating a water-permeable material, a water-impermeable material, a water-absorbing material, and a stretchable material, at least the stretchable material is stuck to the styrene content of 35% by weight. Less than styrene-butadiene block copolymer 15 to 4 of the total adhesive.
Hot containing 0 wt%, tackifying resin 35-70 wt% of the total adhesive, softening agent 5-30 wt% of the total adhesive, and wax in each proportion 0-20 wt% of the total adhesive. A method for manufacturing a disposable diaper, which is characterized in that it is performed with a melt adhesive.