JPS63211369A - Surface material for water absorbent articles with permanent hydrophilicity - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a surface layer material for water-absorbent articles, such as a diaper top sheet, which is made of a synthetic fiber nonwoven fabric treated with a surfactant to make it hydrophilic.

[Conventional technology]

In diapers for infants, etc., it is necessary to reliably capture urine excreted by infants, etc., so some diapers use a synthetic fiber nonwoven fabric coated with a surfactant to make it hydrophilic as its top sheet. many.

[Problem that the invention seeks to solve]

By the way, the performance of recent diapers has improved, and many have the ability to absorb several doses of urine. However, once the diaper urinates and is absorbed into the diaper, there is a problem that the surfactant also flows with the urine and is absorbed, resulting in a decrease in water absorption performance.

The present invention has been made in view of these points, and it is an object of the present invention to provide a surface layer material for water-absorbing articles that can permanently maintain water-absorbing performance, not only for top sheets of diapers.

[Means for solving problems]

In order to solve the above problems, the present invention takes the following technical measures.

In other words, the present invention focuses on the fact that permanent hydrophilicity is exhibited when hydrophilic treatment is performed using a specific surfactant.
The specific surfactant is a surfactant whose main component is at least one member selected from the group consisting of sodium dialkylsulfosuccinate, alkyl ester of polyoxyalkylene, and polysiloxane/polyoxyethylene copolymer. A nonwoven fabric made of synthetic fibers is treated to make it hydrophilic and used as a surface layer material for water-absorbing articles.

[Effect]

Permanent water-resistance can be obtained by performing hydrophilic treatment with at least one of the three types of surfactants mentioned above.

<Raw material for synthetic fiber non-woven fabric> Here, the raw material for synthetic fiber non-woven fabric to be subjected to hydrophilic treatment is low-density polyethylene, as long as it is a synthetic resin that can be formed into fibers, regardless of whether it is crystalline or non-woven. , high density polyethylene, polypropylene, poly l-butene, poly 4-
Polyolefins such as random or block copolymers of α-olefins such as methyl-1-pentene, ethylene, propylene, ■-butene, and 4-methyl-I-pentene, ethylene/acrylic acid copolymers, ethylene/acetic acid Vinyl copolymers, ethylene/vinyl alcohol copolymers, ethylene/vinyl compound copolymers such as ethylene/vinyl chloride copolymers, polystyrene, acrylonitrile/styrene copolymers, ABS, methyl methacrylate/styrene copolymers, Styrenic resins such as α-methylstyrene/styrene copolymer, polyvinyl chloride, polyvinylidene chloride, vinyl chloride/vinylidene chloride copolymer, polyvinyl compounds such as polymethyl acrylate, polymethyl methacrylate, nylon 6, nylon 6-6, polyamides such as nylon 6-10, nylon 111 and nylon 12, thermoplastic polyesters such as polyethylene terephthalate and polybutylene terephthalate, polycarbonate,
Polyphenylene oxide or a mixture thereof can be used.

In the present invention, nonwoven fabrics of polyolefin, polyester, polyamide, and polyethylene terephthalate are particularly suitable.

Further, when a polyolefin is used, it may contain a modified polyolefin such that all or part of it is graft-modified with an unsaturated carboxylic acid such as maleic acid or maleic anhydride.

Method for producing nonwoven fabric> As a method for producing a nonwoven fabric, conventionally known production methods can be used. This method is roughly divided into a wet method that uses a papermaking method, and a dry method that does not.The dry method is further divided into an adhesive type that binds filaments with adhesive, a mechanical bonding type that connects filaments by mechanically entangling them, and a dry method that uses papermaking methods. It can be divided into spinning types that collect spun filaments on a moving collection surface using static electricity or air currents. Further, examples of the spinning type nonwoven fabric manufacturing method include the so-called sprayed fiber method, spunbond method, split fiber method, and net method.

Any of these manufacturing methods can be used when manufacturing the nonwoven fabric of the present invention.

Furthermore, if the basis weight of the nonwoven fabric to be produced becomes high, the hydrophilic properties will deteriorate, so it is preferably 309/I" or less, particularly about 10 g/l" to 259/a".

<Composition of surfactant> As the surfactant used in the present invention, at least 19 types selected from the group consisting of sodium dialkyl sulfosuccinate, alkyl ester of polyoxyalkylene, and polysiloxane/polyoxyethylene copolymer are substantially used. It is a surfactant whose main ingredient is

Since there is at least one type, these may be mixed.
Alternatively, three types of surfactants may be applied to the same nonwoven fabric in layers, although they are not mixed.

The term "substantially the main component" means that the above component alone or as a mixture accounts for approximately 60% by weight or more of the total weight.

Sodium dialkyl sulfosuccinate is an anionic surfactant represented by the following formula (1), and sodium di-2-ethylhexyl sulfosuccinate is particularly preferably used. Such a surfactant is available, for example, from Toho Chemical under the trade name Nearol CT-1.

R'0OC I CH.

■ The alkyl ester of polyoxyalkylene is expressed by the following formula (
Among the nonionic surfactants shown in 2), those particularly preferably used are polyoxyethylene alkyl (R
= C. ~Cto) ester, polyoxypropylene alkyl (R='C,, ~Cto) ester, polyoxyethylene polyoxypropylene alkyl (R=C
,. ~C2°) esters, etc.

Such a surfactant is available, for example, from Toho Chemical Co., Ltd. under the trade name Pronal 502.

RCOO(CHzCH0)it(CHt, CHtO)n
f-[CH3...(2) R...C1° to C3° polysiloxane polyoxyethylene copolymer is a nonionic surfactant represented by the following formula (3), and is particularly preferably used. is for N'=10 to 15. Such a surfactant is available, for example, from Sanyo Kasei Co., Ltd. under the trade name Sunsilicone M-84.

When these surfactants are applied to the present invention, since the surfactants are made into an aqueous solution during application, it is desirable that they have good water solubility and that foaming is as low as possible. Sodium dialkyl sulfosuccinates and polysiloxane-polyoxyethylene copolymers are good in terms of seedlings, and alkyl esters of polyoxyalkylene are good in the latter respect. However, the poor water solubility of polyoxyalkylene alkyl esters can be solved by improving the means to increase the concentration as an aqueous solution and the stirring method when applied to nonwoven fabrics.

The amount of these surfactants applied to the nonwoven fabric can be changed as appropriate depending on the type and basis weight of the nonwoven fabric, and the required hydrophilicity level, but it is usually applied in the range of 2 to 10 g/x''. .

<How to apply surfactant> Surfactant can be applied to nonwoven fabric by spraying with a spray gun, or by placing the surfactant on the uneven surface of a gravure plate and scraping off the surfactant with a spatula. Coating is done by the gravure coating method, in which the nonwoven fabric is placed on a gravure plate and pressed with a rubber roll, and the surfactant in the concave portions of the uneven surface is transferred to the nonwoven fabric, and the reverse coater method, in which the surfactant is applied with a reverse coater. Of course, a coating method may also be used.

〔Example〕

Examples of the present invention will be described below while comparing them with comparative examples.

The details of the surfactant used in this example are as follows.

Pronal 502 (Toho Chemical Co., Ltd.)...Polyoxyethylene/polyoxypropylene copolymer fatty acid (C,) ester/polyether phosphate = 9ht%/10wt%, PH4.3, acid value 3.4 Nearol CT (Toho Kagakusha) Sodium di-2-ethylhexylsulfosuccinate/1,2-propanediol = 87wt%/1:ht%, PH5.7, active ingredient 72% Sunsilicone M-84 (Sanyo Kasei Co., Ltd.) ... Polysiloxane polyoxyethylene cobolimer nonal 208 (Toho Chemical Co., Ltd.) ... Polyoxyethylene nonylphenol ether type nonionic surfactant, HLB12.3 Pebol B-184 (Toho Chemical Co., Ltd.) ... Propylene oxide. Ethylene oxide copolymer type nonionic surfactant, EO addition amount 40% Alscope LE-40 (Toho Chemical Co., Ltd.)...Lauryl alcohol sulfate ester sodium salt type anionic surfactant Alscope LE-240 (Toho Chemical Co., Ltd.) )...Lauryl alcohol ether sulfate ester amine salt type anionic surfactant Begnol TL-8 (Toho Chemical Co., Ltd.)...Polyoxyethylene lauryl ether type nonionic surfactant Begnol HA-120 (Toho Chemical Co., Ltd.) ... Polyoxyethylene alkylamine type nonionic surfactant Begnol L-12 (Toho Chemical Co., Ltd.) ... Polyoxyethylene lauryl ether type nonionic surfactant, HL814.8 Emulgen 109P (Kao Corporation) ... Poly Oxyethylene lauryl ether type nonionic surfactant, HL B 13.6 Homotex PT (Kao Corporation)... Caprylic acid monodiglyceride, acid value 2 or less Levon 105L (Sanyo Chemical Co., Ltd.)... Alkylimidacillin type Amphoteric surfactant Sofnon GF-2 (Toho Chemical Co., Ltd.) Phosphate ester type anionic surfactant Labosufu 5037 (Toho Chemical Co., Ltd.) Carboxyl-modified silicone type surfactant Revon 2000 (Sanyo Chemical Co., Ltd.)...・Amidopetane type amphoteric surfactant Ionet T-600 (Sanyo Kasei Co., Ltd.)...Polyoxyethylene sorbitan monostearate type nonionic surfactant, HL B 14.9 Ionet M
S-1000 (Sanyo Kasei Co., Ltd.): Polyoxyethylene monostearate type nonionic surfactant, HLB15. Fionet PS (Sanyo Chemical Co., Ltd.)...Phosphate ester/
Fatty acid ester mixed type anionic surfactant, PH7 <Examples 1 to 7> An aqueous solution was prepared by diluting the surfactant shown in Table 1 with water on a polypropylene spunbond nonwoven fabric with a basis weight of 209/x'' or 2597y. The hydrophilicity of the sample was evaluated by applying it using the gravure coating method and drying it naturally.

Hydrophilicity was evaluated using Method A and Method B described below.
A hydrophilicity test was performed on a 30c shoulder to evaluate the initial hydrophilicity, and a similar specimen was placed in an air oven at 130°C for 5 minutes.
A hydrophilicity test was conducted after standing for a minute to evaluate heat-resistant hydrophilicity, and a hydrophilicity test was conducted after being immersed in 120 cc of water for 1 hour to evaluate the presence or absence of permanent hydrophilicity.

Here, in method A, a sample is placed on an absorbent body of a commercially available disposable diaper, with the top sheet removed, and fixedly arranged with a 45° angle. In this method, one drop of an I% NaCj aqueous solution is dropped with a pipette from a height of about 10 atx, and the time (seconds) until it is absorbed into the absorber is measured.

It is judged that the shorter the time, the better the hydrophilicity.

In this example, the measurement was carried out for up to 60 seconds, and those that were not absorbed even after 60 seconds were marked as ■.

In addition, in method B, a sample is placed on a stack of 10 sheets of toilet paper, and 17
The number of samples that require 2 seconds or more to start absorption after dropping is measured during the 1O measurement.The smaller the number, the better the hydrophilicity is.

In addition to the hydrophilicity test, the water solubility of the surfactant and the degree of foaming were also examined. For foaming, the beaker method involves stirring the water-soluble surfactant in a beaker and checking for foaming, and the other method involves soaking water in a surfactant-treated nonwoven fabric and kneading it in the palm of your hand to check for foaming. According to the web method. The results are shown in Table 1.

<Comparative Examples 1 to 18> Hydrophilicity and other tests were conducted using surfactants other than those in the Examples described above. Other conditions were the same as in the previous example. The results are shown in Table 1.

<Example 8~it> The nonwoven fabric made of polypropylene was replaced with a nonwoven fabric made of polyethylene terephthalate or nylon 6, and an aqueous surfactant solution was applied to Table 1. The results are shown in Table 1.

<Example 12> In order to investigate the influence of mixing the surfactant used in the present invention with other surfactants, 70w of Sunsilicant 84 was used.
The same procedure as in Example 1 was carried out except that 30 wt % of Ionet T-60C was mixed. The results are shown in Table 1.

<Example 13> The same procedure as in Example 1 was carried out except that a spunbond nonwoven fabric made of a polypropylene composition (fabric weight 20 g/z2) consisting of 95 wt% polypropylene and 5 wt% maleic anhydride graft-modified polypropylene was used.

The results are shown in Table 1.

(This page, blank space below) <Comparative Study> As can be seen from Table 1, surfactants made of sodium dialkyl sulfosuccinate, alkyl ester of polyoxyalkylene, or polysiloxane/polyoxyethylene copolymer were applied. It can be seen that the permanent hydrophilicity of the material is equivalent to the initial hydrophilicity, and the hydrophilicity does not decrease no matter how many times it comes into contact with urine etc. over a long period of time. Moreover, it has good heat resistance and hydrophilicity, and even if an unexpected situation occurs during the manufacturing process and high heat is applied for a long time, there is no risk of the hydrophilicity decreasing. Furthermore, it has been found that as long as these surfactants are essentially the main components, the same performance can be achieved even when other surfactants are mixed, and that the composition is effective for various nonwoven fabrics.

On the other hand, with surfactants other than those used in the present invention,
It can be seen that even if the initial hydrophilicity is good, the permanent hydrophilicity is poor, and there are also cases where the initial hydrophilicity is insufficient.

〔Effect of the invention〕

According to the present invention, by applying a specific surfactant, it can be used as a surface layer material of a water-absorbent article with permanent hydrophilic property, and when used as a top sheet of a diaper, it can withstand several times of urine. Since the diaper does not impair its hydrophilicity, the water absorption performance of the diaper can be maintained for a long time, and the discomfort caused by urinary loss can be eliminated for infants and the like. Furthermore, it can be similarly used as a surface layer material for water-absorbent articles such as sanitary products. moreover,
It may also be used as disposable cloths for industrial and household use.

Claims (2)

[Claims] (1) A surface layer material for a water-absorbing article in which a nonwoven fabric made of synthetic fibers is subjected to hydrophilic treatment with a surfactant, the surfactant comprising:
Permanently hydrophilic, characterized in that it is a surfactant whose main component is at least one member selected from the group consisting of sodium dialkyl sulfosuccinate, alkyl ester of polyoxyalkylene, and polysiloxane/polyoxyethylene copolymer. A surface layer material for water-absorbent articles with properties. (2) Claim 1, which is a top sheet of a diaper
Surface layer material of the water-absorbent article described in Section 1.