JPH01104805A - Production of paper diaper - Google Patents

Abstract

PURPOSE: To inexpensively prepare paper diaper having good touch feeling by applying tensile tension to a stretchable raw material obtained by continuously feeding a melt in which a plasticizer or a compatibility-improving agent are added to a thermoplastic elastomer, and cooling the melt and applying an adhesive to continuously feed objective material at desired intervals so as to provide an expanding and contracting part. CONSTITUTION: A melt in which at least either one of <=40wt.% plasticizer and <=40wt.% wax and 0-70wt.% compatibility-improving agent is added to 15-70wt.% thermoplastic elastomer is applied to a rotating cooling roll 8 in tape-like shape to form a stretchable raw material 9, and a water-absorbing material 3 is put onto a tissue 2 continuously fed from a roll 1 while applying tensile force by rolls 17 and 18 for drawing and is covered with a tissue 32 from a roll 31 and an adhesive is applied from a gun 6 to a nonwoven fabric 4 fed from a roll 5 and the nonwoven fabric 4 is laminated to the tissue 32 to provide the objective paper diaper.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] This invention relates to a method for manufacturing a paper diaper that has some elasticity.

[Conventional technology]

Disposable diapers are made to have elasticity so that there are no gaps between the edges and the skin when worn, especially at the legs and around the waist. . Rubber, urethane, and the like are used as materials for making parts of disposable diapers stretchable.

These materials are processed by material manufacturers into threads, sheets, or films, wound into rolls, and supplied to paper diaper manufacturers. Paper diaper manufacturers apply a tensile force to the stretchable material, which has been processed into a thread shape, and attach it to an object at desired intervals using an adhesive, and these bonded parts serve as stretchable parts.

On the other hand, Japanese Patent Publication No. 61-27182 discloses a method of imparting elongation-resistant pleats to a portion of Honmelt, which has adhesive properties and also has stretchability.

[Problem to be solved by the invention]

As shown above, the elastic material supplied in a roll is attached to each other (self-adhesive).
Therefore, when drawing out and feeding continuously,
The problem is that it breaks easily. Once the elastic material wound around the roll runs out, it is necessary to stop the production line and replenish it.

Further, although rubber is often used as a material for stretchable materials, there is a problem in that the rubber contains impurities, making it easy to break when stretched.

In this case as well, it is necessary to stop the production line.

Paper diapers are easy to use, but because they are disposable,
It is important that the price is low. The price of disposable diapers is low due to continuous mass production. However, the cost of materials, especially elastic materials, is very high;
It is desired to reduce this cost.

It is also possible to apply the method described in the above publication to the production of disposable diapers. However, the hot melt disclosed there doubles as both an adhesive and an elastic material, so when manufacturing disposable diapers, it wraps around the feed roll and is difficult to peel off due to its strong adhesiveness, making it difficult to work with. The problem is that it gets worse. This hot melt has a relatively high melt viscosity, so in order to incorporate it into a line and supply it continuously, it is necessary to
Another problem is that special dispensing equipment is required.

In addition, new equipment investment is required because the extrusion equipment that can keep up with high-speed production lines such as disposable diapers is special.

In view of the above, this invention is made from a relatively low viscosity melt material, is cheaper than conventional stretchable materials, has sufficient stretchability, and has substantial adhesive properties itself. By using stretchable material that does not have any An object of the present invention is to provide a method for manufacturing a paper diaper in which an elastic part can be formed.

[Means to solve the problem]

Therefore, in manufacturing a disposable diaper, the first invention contains at least one of a plasticizer of 40% by weight or less and a wax of 40% by weight or less with respect to a thermoplastic elastomer of 15% to 7% Offi, and 0 to 70% by weight of a wax. A stretchable material is formed by continuously supplying and cooling a melt to which a compatibility improver of % by weight is added, and this stretchable material is continuously supplied and attached to an object with an adhesive. I am attaching it to create an elastic part.

In addition, the method for manufacturing a disposable diaper according to the second invention includes:
The molten material is continuously supplied while being foamed.

[For production]

In the first invention, a stretchable material is formed by cooling a melt containing the above-mentioned components in the above-mentioned proportions, so that the stretchable material is inexpensive. The inventor has confirmed that the cost is about 1/3 that of conventional elastic materials such as rubber and urethane supplied by material manufacturers. Since the viscosity of the melt is relatively low, a commonly used hot melt applicator or the like can be used, and there is no need to use a special dispensing device for high viscosity. Since disposable diaper manufacturers also form stretchable materials when manufacturing disposable diapers, they can prevent impurities from entering the materials themselves. The formed stretchable material has no adhesive properties and is continuously supplied as is, so there is no risk of it adhering to rolls, etc., and workability is good. Also, you don't have to worry about it wearing itself.

In addition, in the second invention, since the melt is continuously supplied while being foamed, a stretchable material with good texture can be obtained.

〔Example〕

If the proportion of the thermoplastic elastomer is less than 15% by weight based on the total weight of the thermoplastic elastomer, plasticizer, wax, and compatibility improver, there is a problem that the elasticity is extremely reduced, and if it exceeds 70% by weight. However, there is a problem that the viscosity of the melt increases.

The thermoplastic elastomer is not particularly limited, but includes, for example, polystyrene/polyisoprene/polystyrene block copolymer (SI S), polystyrene/polyisoprene radial block copolymer (SI), polystyrene/polybutadiene/polystyrene block copolymer (S B S), polystyrene/polyolefin (ethylene/butylene)/polystyrene block copolymer (eg, 5EBS), ethylene/vinyl acetate rubber (E/A), α-olefin, etc. may be used alone or in combination of two or more.

Plasticizers and waxes are used to lower the viscosity of the melt to obtain stretchable materials, and to prevent unnecessary adhesive properties such as wrapping around rolls. may be used, or both may be used.

When a plasticizer is used, the proportion thereof must be 40% by weight or less based on the total weight of the thermoplastic elastomer, plasticizer, wax, and compatibility improver. When the amount exceeds dQffi amount %, there is a problem that the cohesive force decreases.

When wax is used, its proportion must be 40% by weight or less based on the total weight of the thermoplastic elastomer, plasticizer, wax, and compatibility improver. If it exceeds 40% by weight, there is a problem that elasticity decreases.

The plasticizer is not particularly limited, but for example, naphthenic oil, paraffin oil, liquid rubber, etc. may be used alone or in combination of two or more.

The wax is not particularly limited, but paraffin wax, microcrystalline wax, Fischer-Tropsch wax, and the like may be used singly or in combination of two or more.

The compatibility improver improves the compatibility of the above essential components,
It is used as necessary to reduce viscosity. When used, the proportion should be 70% by weight or less based on the total weight of the thermoplastic elastomer, plasticizer, wax and compatibility improver. If the proportion exceeds 70% by weight, there is a problem that elasticity decreases.

There are no particular limitations on the compatibility improver, but for example,
Aromatic hydrocarbon resins, aliphatic hydrocarbon resins, polyterpene resins, at least one of these hydrogenated (hydrogenated) resins, modified wood rosin, etc. may be used alone or in combination of two or more.

An anti-aging agent can be used to impart weather resistance to the stretchable material and prevent its thermal deterioration. The anti-aging agent is not particularly limited, but for example, phenolic antioxidants, phosphorus-based antioxidants, etc. may be used alone or in combination of two or more. The blending ratio of the anti-aging agent is not particularly limited as long as it does not impair the achievement of the two objectives of the invention. Further, other compounds may be added as necessary.

Since the stretchable material used for disposable diapers comes into direct or indirect contact with the skin, it is preferable that the material has a good texture. For example, when producing a stretchable material, if the melt is continuously supplied while being foamed and cooled, a stretchable material with a good feel can be produced. In this case, in order to increase the stability of foaming, one or both of the surfactant and the filler is added to the total weight of the thermoplastic elastomer, plasticizer, wax and compatibility improver, respectively, from 0 to 0. The content may be 3% by weight.

The surfactant is not particularly limited, but for example, nonionic surfactants, anionic surfactants, cationic surfactants, etc. may be used alone or in combination of two or more. Further, as the filler, colloidal silica, carbon black, titanium oxide, etc. may be used alone or in combination of two or more.

In these two inventions, a molten material containing the above components in the above proportions is continuously supplied and cooled to form a stretchable material. It is preferable that the melt contains the above-mentioned components as uniformly as possible. The melt is cooled to a temperature below the softening point of its components (desirably about 50° C. or below, depending on the formulation) and solidified to obtain a solidified material having stretchability, that is, a stretchable material.

The obtained elastic material is continuously supplied to a disposable diaper production line without being wound up into a roll or the like. The stretchable material is applied with a tensile force applied thereto at desired intervals, for example, to each portion of a continuously supplied object to which stretchability is desired. At this time, the adhesive may be applied over the entire portion to be pasted, or may be applied at appropriate intervals. Here, the object is not particularly limited, but includes, for example, a nonwoven fabric placed on the side that contacts the skin, a polyethylene sheet placed on the outside, and the like.

Table 1 shows the physical properties of the stretchable material used in these two inventions and the properties of the stretchable material made of hot melt disclosed in Japanese Patent Publication No. 61-27182. Sample lights 1 to 9 are stretchable materials used in these two inventions, and sample light 10 is a stretchable material made of hot melt described in the above publication. Each formulation has a total weight of thermoplastic elastomer, plasticizer, wax, and compatibility improver of 100 parts by weight. Sample magnets 8 and 9 were made by foaming a molten material by a method that utilizes gas mixture and dissolution as described below.

Examples of thermoplastic elastomers include SBS (trade name Tuffprene A manufactured by Asahi Kasei Corporation) and SI (trade name TURPRENE (SQLPRENE) manufactured by Philips Chemical Co., Ltd.).
1B) was used.

Process oil (trade name: Shell Flex 371N, manufactured by Shell Chemical Co., Ltd.) was used as the plasticizer.

Paraffin wax (trade name: Paraffin Wax 150, manufactured by Hiki Seiro Co., Ltd.) was used as the wax.

As the compatibility improver, aliphatic hydrocarbon resin (trade name Alcon M-100, manufactured by Arakawa Chemical Co., Ltd.), polyterpene resin [trade name WINGTACK (WINGTACK) 95, manufactured by Gutdeyer Tire & Rubber Co., Ltd.
), and coumarone indene resin (trademark CUMAR LX-509 manufactured by Nehir Corporation) were used.

As a surfactant, sodium dioctyl sulfosuccinate (Dioctyl 5ulfosuccinate) is used as a surfactant.
Sodium 5a1t) [○T manufactured by American Cyanamide
-100) was used.

As a filler, titanium oxide (R manufactured by Ishihara Sangyo Co., Ltd.) was used.
-780) was used.

As an antioxidant, high molecular weight hindered phenol [
Ciba Geigy's IRGANOX
) was used.

The viscosity was measured at 180°C using a B-type viscosity needle equipped with a thermocell.

The ease of peeling from the roll was examined as follows.

Each sample (hot melt) was coated on the same silicone rubber used for the roll surface at a coating temperature of 180° C. into a sheet having a width of 25 mm and a thickness of 100 μm, and was left overnight at room temperature. Each produced hot melt sheet and silicone rubber were peeled 180 degrees and the peel strength was measured. Peel strength was expressed as ease of peeling. Note that the peeling speed was 300 mm/min.

Stretchability was examined as follows. Each sample (hot melt) was coated onto a release paper at a coating temperature of 180° C. into a sheet having a width of 25 mm, a length of 200 mm, and a thickness of 100 μm, and was left overnight at room temperature.

Peel each generated hot melt sheet from the release paper and
After being held in a 00% stretched state for 4 hours, it was opened and the percentage elongation from the original length was measured. ◎ if this elongation is less than 5%, 0110% if it is 5% or more and less than 10%
The above items were evaluated as x and elasticity was evaluated.

The texture was examined as follows. Using the apparatus shown in Figure 1, each sample was attached to a nonwoven fabric (manufactured by Asahi Kasei Industries, Ltd.) with a hot melt adhesive (Nilatite HT-940F, manufactured by Nitta Gelatin Co., Ltd.), and 10 panelists ( Both women) evaluated the results by touch with their fingers.

The evaluation is very excellent...5 points Fairly good...4 points Average...3 points Somewhat bad...2 points Very bad...1 point The results are ranked and the average score is shown.

In addition, each sample of No. 8 and 9 has a foaming ratio of 2.5.
The film was coated to a width of 10 mm and a thickness of 100 μm at a coating temperature of 180° C., and the stretching rate was 200%. The Nal~7 and 11h10 samples were each 11kL8.1, except that they were not foamed. The same procedure as for sample No. 9 was carried out.

As shown in Table 1, the melt (
Samples IVk11-9) have a lower viscosity than the hot melt melt described in the above publication (sample number 10). The elastic materials used in these two inventions are also easier to peel off from the roll and have better elasticity. In addition, a stretchable material produced while foaming a melt has a better feel than one that is not foamed, and has the same other physical properties.

In order to make the stretchable material used in these two inventions, any method may be used to continuously supply and cool the melt, but for example, the melt may be continuously supplied to a rotating cooling roll. This can be easily done by applying it directly. This cooling roll is preferably equipped with cooling means to remove solidification heat. The method of applying the melt to the cooling roll is not particularly limited, but for example,
There is a method using a hot melt applicator. There are no particular limitations on hot melt applicators, but
It is preferable to use a gear pump type pump because the discharge amount is constant. The stretchable material obtained by solidifying the molten material is guided by an appropriate method, such as guide rolls, and sent to the object. The stretchable material is applied to the object at desired intervals using hot melt adhesive or the like while being subjected to tensile force. Therefore, when the tensile force is released, the part attached to the object contracts due to its own elastic force, giving this part elasticity. Although there is no particular limitation on the method of applying tensile force to the stretchable material, for example, there is a method using stretching rolls. Further, the adhesive for pasting the stretchable material onto the object may be other than hot melt adhesive.

For example, when manufacturing stretchable materials with good texture,
Gas is mixed and dissolved in the molten material while pressurizing inside a tank or supply path, and the molten material is sent to atmospheric pressure using a coating gun or the like and is applied to a cooling roll or the like. This results in
When the pressure is removed, the molten gas is released in the form of bubbles, causing the melt to foam, and upon cooling, solidifies while entrapping the bubbles to form a homogeneous pore-filled elastic material. The gas used for foaming the melt is not particularly limited, and includes, for example, nitrogen gas, carbon dioxide, air, and other gases that are inert to the melt. Furthermore, the device for dissolving the gas in the molten material is not particularly limited, but for example,
An applicator with a gas mixing device as disclosed in Japanese Patent No. 645 is used. This applicator includes a melting tank, a gas supply source, a gear pump connected to each of these via a tube, and an application gun connected to the gear pump via a tube. A molten material containing the above components in the above proportions is supplied from a melting tank and a gas is supplied from a gas supply source to a gear pump, and the mixture is mixed by the meshing teeth of a pair of gears of this pump, and the mixture is pressurized. Dissolve the gas in the melt. This is supplied under pressure to a coating gun, and is allowed to flow out from the coating gun under atmospheric pressure to be coated onto a cooling roll or the like.

Note that the foaming of the above-mentioned melt is preferably carried out by the above-mentioned method. This is because uniform foaming can be obtained and the foaming ratio can be controlled.

However, foaming of the above-mentioned melt is not limited to the above-mentioned method, and includes, for example, a method using a decomposition-type blowing agent that generates gas through a chemical reaction or a solvent-type blowing agent such as a readily volatile organic liquid, stirring, etc. A mechanical foaming method, a spray foaming method, or the like may be used.

The expansion ratio of the stretchable material with good texture is not particularly limited, but it is preferably adjusted to about 1.5 to 3.5 times.

If it is below this lower limit, the effect of improving the texture may be insufficient, and if it exceeds the upper limit, bubbles may combine to form a non-uniform foam.

Hereinafter, these two inventions will be described in more detail with reference to the accompanying drawings, showing an example of an apparatus used for carrying out the invention.

FIG. 1 shows an example of an apparatus for implementing the two methods of manufacturing disposable diapers of the invention. Figure 2 shows a part of the disposable diaper in the process of being manufactured, and Figure 3 shows its II-I cross section.
Figure 4 shows its ■-■ cross section. As seen in these figures, tissue-2 is continuously supplied from roll 1. Water-absorbing material 3 is placed on one side of this tissue-2.
will be posted. On top of this, tissue from roll 3 -
32 is continuously supplied to cover the water absorbing material 3. moreover,
The non-woven fabric 4 is attached to the tissue 32 using a hot melt adhesive 42 or the like so as to cover the upper tissue 32 and protrude from both sides thereof. This nonwoven fabric 4 is
It is continuously supplied from roll 5. The nonwoven fabric 4 becomes the side that comes into contact with the skin when the disposable diaper is used. In the figure, 6 is a gun for applying hot melt adhesive. A hot melt adhesive 42 is applied to the nonwoven fabric 4 in the width direction except for the portion where the stretchable material 9 is to be joined.

On the other hand, the melt having the above composition is applied in the form of a tape onto the rotating cooling roll 8 by the true melt application gun head 7. The melt may be applied while being foamed as described above, if necessary.

The melt is cooled to some extent by cooling rolls 8 to form a stretchable material 9. The stretchable material 9 is peeled off from the cooling roll 8 by a mold release treatment roll 10, and then transferred to the guide roll 1.
1 to 16, it is sufficiently cooled so that it does not fully stretch even when subjected to tensile stress. Then, it is stretched while being subjected to tensile stress by stretching rolls 17 and 18.

Under this tensile stress, the stretchable material 9 is exposed to the polyethylene film 2 on both sides of the longitudinally intermediate portion of the water absorbent material 3.
0 at desired intervals using a hot melt adhesive for gears 22. The polyethylene film 20 covers the tissue 2 and the elastic material 9,
It is attached to the tissue-2 using a hot-melt adhesive 42 or the like, and is also attached to the non-woven fabric 4. Polyethylene film 20 is continuously supplied from roll 21. In FIG. 1, 19 is a gun for applying the hot melt adhesive 22 for gears, and 23 is a gun for applying the hot melt adhesive 42. In the width direction of the polyethylene film 20, excluding the part where the elastic material 9 is combined,
True melt adhesive 42 is applied.

Nonwoven fabric 4 and polyethylene film 20 as described above
After pasting them together, as shown by the dashed-dotted lines in Figures 2 and 3, if the entire body is canted between the water-absorbing materials 3 and 3, the tensile force applied to the stretchable material will be eliminated. ,
This is a paper diaper with elastic parts (gathers). The part indicated by A will be enough for one disposable diaper. Note that the gears may be provided not only at the crotch area but also at the waist area.

The polyethylene film 20 becomes the outer side when the disposable diaper is used, and is used to prevent water from leaking to the outside.

If a stretchable material is made by continuously supplying and cooling the melt while foaming it, the feel of the disposable diaper will be better.

Corresponding to the speed of the paper diaper manufacturing line, the speed of the elastic material manufacturing line can also be adjusted as appropriate by adjusting the rotational speed of the cooling roll 8 as appropriate. In addition, the width, thickness, etc. of the elastic material can be freely and easily changed by changing the width or position of the outlet of the gutter 7 on the hot melt application gun. .

More specific examples and comparative examples of these two inventions are shown below, but these inventions are not limited to the following examples.

(Examples 1 to 7) Disposable diapers were manufactured by the method described above using melts having the components and formulations of Samples 1IkL1 to 7 shown in Table 1.

The melt was applied using an applicator ZH-5 manufactured by Suntool Co., Ltd. under the following conditions.

・Tank temperature: 160°C ・Hose temperature = 160°C ・Gun temperature: 160°C ・Coating width: IO Tsuru ・Coating thickness: 100 μm (Examples 8 and 9) Sample Na8. Disposable diapers were manufactured in the same manner as in Examples 1 to 7, using the melt having the components and composition of No. 9, and foaming the melt by the method utilizing gas mixture and dissolution as described above.

The melt was applied using a foam melt applicator (model FM-101A) manufactured by Nordson Corporation under the following conditions.

・Tank temperature: 160℃ ・Hose temperature: 160℃ ・Gun temperature: 160℃ ・Back pressure: 60kgf/enf ・Air motor pressure: 3.5 kgf/ct ・Nitrogen gas pressure:
3 kgf/cn (・Coating width: 10 mm・Coating thickness: 100 μm (Comparative example) Disposable diapers were manufactured by the same method as Examples 1 to 7 using a melt having the components and composition of sample 11hlo shown in Table 1.

The melt was applied using an applicator ZH-5 manufactured by Suntool Co., Ltd. under the following conditions.

・Tank temperature = 190°C ・Hose temperature: 190°C ・Gun temperature: 190°C ・Coating width: 10n ・Coating thickness: 100 μm In Examples 1 to 9, even if the speed of the production line is increased, the formation and rolling of the elastic material will be difficult. There is no problem with peeling from the
A paper diaper with good elasticity could be manufactured.

In contrast, in the comparative example, when the speed of the production line was increased, the elastic material was not formed with a uniform width and thickness;
There were also interruptions. In addition, there was a problem that the peelability from the rolls was poor and it wound around rolls 10 to 17 shown in FIG. The paper diaper obtained in this comparative example had too strong cohesive force and poor texture. The paper diapers obtained in Examples 8 and 9 had better texture than those in other Examples.

Note that these two inventions are not limited to the above embodiments.

〔Effect of the invention〕

As described above, the method for manufacturing a disposable diaper according to the invention of claim 1 is to form a stretchable material by continuously supplying and cooling a molten material, and to continuously supply the material to a manufacturing line for disposable diapers. Because it is supplied, the cost is lower than using other elastic materials, and it can be made endless, so there is no need to stop the line to replenish the elastic material. Since the above-mentioned melt has the above-mentioned specific formulation, it has a low viscosity (and has almost no adhesive properties either before or after solidification. Therefore, it has good workability. Because it is manufactured with
Thickness etc. can be freely and easily changed when cooling the molten material. The elastic material can be formed at the speed of the disposable diaper production line, making it possible to speed up production.

In addition, the method for manufacturing a disposable diaper according to the invention of claim 2 is characterized in that, since the molten material is continuously supplied while being foamed and cooled, a stretchable foam material is formed and the diaper has a good texture. Can be done.

[Brief explanation of the drawing]

Fig. 1 is a schematic diagram of an example of an apparatus for carrying out the method of manufacturing disposable diapers of these two inventions, Fig. 2 is a plan view of a paper diaper in the middle of manufacturing, with some parts removed, and Fig. 3 is a FIG. 4 is a sectional view taken along line I-1, and FIG. 4 is a sectional view taken along line nn. 7... Gun head for hot melt application 8... Cooling roll 9... Stretchable material 17. 18... Roll for stretching 22... Hot melt adhesive agent for Gearsor Patent attorney Takehiko Matsumoto

Claims (1)

[Scope of Claims] 1. A continuously supplied stretchable material is attached to a continuously supplied target object with an adhesive at desired intervals while applying a tensile force to the stretchable material. In a method for manufacturing a disposable diaper that includes a step of creating an elastic part in an object, the elastic material contains at least 40% by weight of a plasticizer and 40% by weight or less of a wax based on 15 to 70% by weight of a thermoplastic elastomer. 1. A method for manufacturing a disposable diaper, characterized in that the product is formed by continuously supplying and cooling a melt to which 0 to 70% by weight of a compatibility improver is added. 2 Create a stretchable part on the continuously supplied object by applying a tensile force to the continuously supplied stretchable material and attaching it with adhesive at desired intervals to the object. In the method for manufacturing a disposable diaper, the elastic material contains at least one of 40% by weight or less of a plasticizer and 40% by weight or less of wax, based on 15% to 70% by weight of a thermoplastic elastomer, and 0 to 70% by weight of a wax. 1. A method for manufacturing a disposable diaper, characterized in that a molten material to which 70% by weight of a compatibility improver has been added is continuously supplied while foaming and cooled.