DK168324B1 - Self-adhesive absorbent mold body and suitable melt adhesives - Google Patents

Abstract

The adhesive article has a core of liquid-absorbing material and a covering of liquid-permeable sheet material. Arranged on one side of the article, on the surface of its covering, is a pressure-sensitive, self-sticking layer of hot-melt adhesive, which is covered, prior to use, with a removable protective film. The hot-melt adhesive is based on atactic polymers and contains, in addition to these polymers, tackifying resins and processing oils in such proportions that the self-sticking adhesive layer possesses an adequate adhesion to textiles, such as underwear materials, and an adequate cohesion, so that it can be removed again from an item of underwear without leaving any residue. The adhesion of the self-sticking hot-melt adhesive is adapted in such a way that it ensures a good fitting of the article on a support, such as an item of underwear, on which it is stuck. <IMAGE>

Description

in DK 168324 B1

The present invention relates to an absorbent mold body, for example a sanitary napkin or panty lining, with a core of absorbent material and a wrapper of liquid-permeable sheet material, wherein on the one side of the mold body is provided a pressure-sensitive self-adhesive adhesive layer. a removable protective film, which adhesive layer consists of a melt adhesive of 20 to 80% substantially amorphous olefinic polymers, 20 to 80% tackifier resins, and 0 to 80% plasticizer oil. The invention further relates to a melting adhesive for the mold body according to the invention, consisting of 20 to 80% substantially amorphous olefinic polymers, 20 to 80% tackifier resins and 0 to 80% plasticizer oil.

It is known to provide absorbent molds such as sanitary napkins, panty liners and other hygiene articles with a self-adhesive hot-melt adhesive to affix and secure the molding to a garment such as, for example, a panty. For this, it is required, first, for a secure retention of the impeccable attachment and partly for the removal of it from the fabric of the garment without leaving any residue.

20 For self-adhesive labels, adhesive strips, carpet tiles, hygiene articles and other articles with self-adhesive equipment, pressure-sensitive melt adhesives are used, consisting mainly of polymers, emollients, adhesive resins and additives. As a polymer, thermoplastic rubber such as SEBS, SBS, SBR, SIS were used either alone or in combination with each other and in some cases also EVA. The polymer components of the pressure sensitive melt adhesive primarily affect the cohesion of the melt adhesive, while the resin components primarily determine the adhesion forces.

A distinctive feature of pressure-sensitive hot melt adhesives over other 30 hot melt adhesives is that they allow a clean adhesive adhesive. According to the different applications and the resulting requirements for the use characteristics, the cohesion and adhesion are different for the pressure-sensitive melt adhesives. The ratio of these is especially critical in cases where the adhesive must be able to be resealed without destroying the adhesive substrates and leaving no adhesive residue on the non-adhesive coated substrate.

This is especially important for hygiene articles such as sanitary napkins, panty liners and incontinence articles, where special requirements are made for the DK 168324 B1 2 adhesive, as it must provide sufficient adhesion for good adhesion and secure retention, however, the adhesion must not exceed the strength of one or the other. part of the hygiene article in order for the hygiene article to be removed intact again, and at the same time must have one to -5 extensible cohesion to ensure easy and residual removal of the hygiene article from the garment. Thus, no adhesive transfer must take place during the adhesion of the hygiene article to the garment.

The adhesion of a pressure-sensitive melt adhesive is determined by the tensile strength and the cohesion by the shear strength. Known pressure-sensitive hot-melt adhesives used for hygiene articles have, according to usual standard test methods according to PSTC and FINAT, an adhesion range with peel strength values between 9 and 40 N / 25 mm. Pressure sensitive melt adhesives with thermoplastic polymer base 15 polymer generally have a high cohesion with shear strength values of more than 2 hours. Also, pressure sensitive melt adhesives on EVA basis with similar adhesion properties are known, but lower cohesion with shear strength values of about 5 minutes that can be released residues. However, such pressure-sensitive melt adhesives, which have heretofore been used for 20 self-adhesive hygiene articles, are relatively expensive because of the polymer base composition mentioned.

It is known from European Patent Specification No. 3,194 to make melt adhesives from certain amorphous or partially crystalline olefin copolymers with certain adhesive resins and plasticizers. The 25 olefinic copolymers must contain at least one linear Cg 2 a-olefin and 15 to 60 mole percent of at least one linear C g There is no mention of whether it is an atactic polymer. On the other hand, it is emphasized time and again that the melt adhesives in question exhibit high shear strengths. In column 5, lines 31-42, it is emphasized that the 30 melt adhesives in question exhibit shear strengths in the range from over 200 minutes to over 10,000 minutes. The examples show continuous shear forces in the range of several thousand minutes. The lowest shear strength given at all is in Example 4 with 19 minutes.

Thus, the doctrine that can be deduced from European Patent Specification No. 3,194 is to design the known melt adhesives in such a way that they exhibit shear strengths of at least 19 minutes and to a great extent between 1000 and over 10,000 minutes. Thus, the writing supports the view that only melt adhesives with very high shear strengths are usable DK 168324 B1 3.

This view is supported by US Patent No. 4,264,756, which consistently shows even higher shear strengths than the aforementioned EP patent application. The melt adhesives according to the US patent differ from the 5 melt adhesives according to the EP patent by not containing any plasticizer oil.

The object of the present invention is to provide a self-adhesive absorbent mold body with a pressure-sensitive hot-melt adhesive coating which is cheaper than previously considered and has sufficient strength to be securely attached to a garment and again could be removed from this without breaking and leaving no residue.

According to the invention, this task is solved with an absorbent mold body having the characteristics specified in claim 1. Advantageous embodiments of this mold body are the subject of claim 2. The invention further relates to a melt adhesive as claimed in claim 3. Advantageous embodiments of the melt adhesive according to the invention are given in claim 4.

With the invention, the prevailing prejudice of the prior art overcomes that a high shear strength is a prerequisite for a suitable melt adhesive.

The pressure-sensitive melting adhesives used according to the invention contain, as a polymer base, atactic copolymers of α-olefins, either alone or in admixture with atactic polypropylene and in addition the usual additives for known pressure-sensitive melting adhesives. The adhesion values of such melting adhesives are within the usual limits, but their cohesion values are very low. Atactic polymers are polymers with irregular spatial arrangement of their substituents or side chains (e.g., the methyl groups for polypropylene), cf.

30 Ullmann's Encyclopedia of Technic Chemistry, Volume 15, 1978, Verlag Chemie GmbH, Weinheim, p. 206, and Rompps Chemie-Lexikon, 1979, Franckh'sche Veriagshandlung, Stuttgart, p. 299. Pressure-sensitive melt adhesives according to the invention are not available. remove at the usual standard test conditions (adhesion and release ratio to steel) again without leaving any residue. However, it has been found that such pressure-sensitive hot melt adhesives have the necessary suitability for use in hygiene articles. These hot-melt adhesives can be manufactured cheaper than the hot-melt adhesives hitherto considered suitable for hygiene articles, such that the price of absorbent molded bodies can thereby be lowered noticeably, since the hot-melt adhesive used is a not insignificant cost factor for such molds.

The suitability of the pressure-sensitive melt adhesives for hygiene articles used in accordance with the invention was, as opposed to the usual standard test methods, determined as follows:

The adhesive properties of a standard coating (60 g / m pressure sensitive polyester adhesive) to cotton fabric at room temperature (RT) and according to simulated conditions of use (TTP = temperature 38T, hour = time 15 10 hours, pressure = pressure 0.13 N / cm) were specific. Thus, for the pressure sensitive melt adhesives, pull-off strength values were obtained in the following ranges: RT 0.1 - 2.5 N / 25 mm 15 TTP 0.7-4.0 N / 25 mm

Also within these limits are the values of the pressure-sensitive hot-melt adhesives used according to the invention, which exhibit the adhesion necessary for a secure retention of the body to the garment, but at the same time can also be easily removed from the garment's fabric without leaving any residue. The following peel strengths were determined for such a pressure sensitive melt adhesive:

Applicant's standard test against cotton: 25 Tensile strength RT approx. 0.6 N / 25 mm TTP approx. 1.8 N / 25 mm In both cases, the solution is made from the cotton without leaving any residue.

The following examples of pressure-sensitive melt adhesives on the basis of atactic copolymers of α-olefins serve to further illustrate the invention: 35. ___________________ ^

Example 1 DK 168324 B1 5 30 parts mineral oil 33 parts atactic copolymer of α-olefins, 5 melt viscosity at 190 ° C approx. 50,000 mPa.s, ring + ball softening point approx. 110 ° C, penetration approx. 14 35 parts cyclopentadiene resin,

ri ng + ball softening point approx. 125 ° C

10 2 parts EVA

If such a pressure-sensitive melting adhesive was evaluated by the standard test against steel, it would be considered unsuitable due to the particular shear strength.

15

Standard testing against steel

Peel strength 28 N / 25 mm, cohesion break at solution, ie adhesive -20 residues

Shear strength <1 minute

Standard test against cotton 25 Tensile strength RT approx. 0.6 N / 25 mm TTP approx. 1.8 N / 25 mm

Physical data for the melt adhesive

30 Ring + ball softening point: approx. 78 ° C

Melt viscosity at 175 ° C: approx. 1600 mPa.s

Penetration: approx. 95

Example 2 35 35 parts mineral oil 28 parts atactic copolymer of α-olefins, melt viscosity at 190 ° C approx. 50,000 mPa.s, DK 168324 Bl 6 ring + ball softening point approx. 110 * 0, penetration approx. 14 35 parts cyclopentadiene resin,

ring + ball softening point approx. 140eC

5 2 parts EVA

Standard testing against steel

Tensile strength 19.0 N / 25 mm, cohesion break at solution, 10

Shear strength <1 minute

Standard test against cotton 15 Tensile strength RT approx. 0.50 N / 25 mm TTP approx. 1.00 N / 25 mm

Physical data for the melt adhesive

20 Ring + ball softening point: approx. 76 ° C

Melt viscosity at 175 ° C: approx. 1100 mPa.s

Penetration: approx. 95

EXAMPLE 3 40 parts mineral oil 28 parts atactic copolymer of α-olefins, melt viscosity at 190 ° C approx. 50,000 mPa.s, ring + ball softening point approx. 110 ° C, penetration approx. 14 30 parts cyclopentadiene resin,

ring + ball softening point approx. 140 ° C 2 parts EVA

35 Standard testing against steel

Peel strength 11.0 N / 25 mm, cohesion break at solution, DK 168324 B1 7

Shear strength <1 minute

Standard test against cotton 5 Tensile strength RT approx. 0.20 N / 25 mm TTP approx. 0.30 N / 25 mm

Physical data for the melt adhesive

10 Ring + ball softening point: approx. 75 ° C

Melt viscosity at 175 ° C: approx. 850 mPa.s

Penetration: approx. 125

EXAMPLE 4 40 parts mineral oil 28 parts atactic copolymer of α-olefins, melt viscosity at 190 ° C approx. 50,000 mPa.s, ring + ball softening point approx. 110 ° C, 20 penetration approx. 14 30 parts cyclopentadiene resin,

ring + ball softening point approx. 160 ° C 2 parts EVA

25 Standard testing against steel

Tensile strength 19.0 N / 25 mm, cohesion break at solution,

Shear strength <1 minute 30

Standard test against cotton

Tensile strength RT approx. 0.50 N / 25 mm TTP approx. 1.00 N / 25 mm 35

Physical data for the melt adhesive

Ring + ball softening point: approx. 77 ° C

DK 168324 Pg 8

Melt viscosity at 175 ° C: approx. 900 mPa.s

Penetration: approx. 120

Example 5 5 45 parts mineral oil 28 parts atactic copolymer of α-olefins, melt viscosity at 190 ° C approx. 50,000 mPa.s, ring + ball softening point approx. 110 ° C, 10 penetration approx. 14 25 parts cyclopentadiene resin,

ring + ball softening point approx. 160 eC 2 parts EVA

15 Standard testing against steel

Peel strength 9.0 N / 25 mm, cohesion fracture in solution,

Shear strength <1 minute 20

Standard test against cotton

Tensile strength RT approx. 0.20 N / 25 mm TTP approx. 0.30 N / 25 mm 25

Physical data for the melt adhesive

Ring + ball softening point: approx. 74 ° C

Melt viscosity at 175 ° C: approx. 800 mPa.s 30 Penetration: approx. 130

Recipe ranges of the basic raw materials: atactic polymer 20 - 80% 35 resin 20 - 80% oil 0 - 80%

It has been found that for mold bodies such as hygiene articles, pressure-sensitive melt adhesives whose cohesion against steel is insufficient are fully adequate. The tensile strength must be determined against cotton and not steel to determine whether a pressure sensitive hot melt adhesive is suitable for hygiene items. In this way, one will also be able to examine cheaper pressure-sensitive melt adhesives for suitability for hygiene items.

For further illustration of the invention, a graphical representation of an absorbent shaped body formed according to the invention is schematically shown in the drawing.

The mold body 1 shown in the drawing has an elongated absorption body 2 with rounded ends and some inward side edges, but the shape of the absorption body is not essential to the present invention. Absorbent body 2 has a liquid-permeable outer shell 3 and a body absorbed thereon of liquid absorbent material shown in the drawing.

On the side of the absorbent body 2 facing downwards, strips 4 of pressure-sensitive melt adhesives according to the invention are arranged which extend over most of the length of the absorption body, which are formed on the basis of atactic copolymers of alpha-olefins. This adhesive strip 4 side of the absorbent body 20 is covered with a thin removable protective film 5 before use. This protective film 5 is shown in the drawing partially separated from the absorbent body 3 and consists, for example, of silicone paper. It is removed from the mold body 1 immediately before its commissioning.

Although the adhesive coating of the drawing is shown in the form of 25 stripes 4, it may also be formed as a full surface and extend over the entire length of the absorbent body 2, or may exhibit any other patterns such as a stripe pattern.

Claims (4)

10 DK 168324 B1 An absorbent mold body, for example a sanitary napkin or panty lining, with a core of absorbent material and a wrapper of liquid-permeable sheet material, on which is provided, on one side of the mold body, on the surface of the mold a pressure-sensitive, self-adhesive adhesive layer having removable protective film, which adhesive layer consists of a melting adhesive of 20 to 80% substantially amorphous olefinic polymers, 20 to 80% tackifying resins and 0 to 80% plasticizer oil, characterized in that the polymeric content of the melt adhesive is copolymer. of α-olefins and that the melt adhesive exhibits a shear strength (standard test against steel) of less than 1 minute. 2. Form body according to claim 1, characterized in that the atactic copolymers are mixed with atactic polypropylene. A mold body adhesive according to claim 1, consisting of 20 to 80% substantially amorphous olefinic polymers, 20 to 80% 20 adhesive resins and 0 to 80% plasticizer oil, characterized in that the polymers are atactic copolymeric agents of a; olefins, and that the melting adhesive exhibits a shear strength (standard test against steel) of less than 1 minute. Melt adhesive according to claim 3, characterized in that the atactic copolymer is mixed with atactic polypropylene. 30 35