MXPA01010068A - Hygienic absorbent with odour control - Google Patents

Abstract

A superabsorbent material with enhanced odour control and control of bacterial growth comprises a non-acidic, alkali-neutralising compound selected from acid anhydrides, lactides, lactones and hydrolysable esters, especially cyclic acid anhydrides, lactides and lactones of&ggr;- or&dgr;-carboxylic acids. The superabsorbent material can be used in hygiene products such as diapers.

Description

HYGIENIC ABSORBENT WITH ODOR CONTROL Field of the Invention The present invention relates to a superabsorbent material for use in hygienic absorbent products such as diapers, sanitary napkins and the like, which has improved its odor control and prevents the proliferation of bacteria, and to a method for producing said material .

BACKGROUND OF THE INVENTION Various superabsorbent materials are known in the art. Examples are crosslinked polyacrylates, and polysaccharide grafts with polyacrylates. A problem related to the use of super absorbent materials is the odor caused by the components of the urine, which cause the super absorbent materials to become objectionable before their maximum absorbent capacity has been used. Because malodorous compounds are often alkaline materials such as amines, it has been proposed to improve odor control by adding acids to the super absorbent material. However, the use of acids has the disadvantages that acids will lead to skin irritation. US Pat. No. 4,685,909 discloses disposable diapers and the like containing polymeric acid pH control agents, such as cellulose phosphate, and polyacrylic acid. It has been discovered that a super absorbent material with improved odor control can be produced by incorporating into or combining with the super absorbent material an alkaline, non-acidic neutralizing compound selected from acid anhydrides, lactides, lactones and hydrolyzable esters. Lactides include cyclic esters of hydroxy acids, especially alpha-hydroxy such as glycolic acid and lactic acid (2,5-dioxo-1,4-dioxanes).

Lactones include cyclic esters of particularly hydroxy acids, hydroxy acids such as butyrolactone, valerolactone, gluconolactone, glucuronolactone, and the corresponding lactones of other sugar acids. Examples of the hydrolysable esters are cellulose acetate and starch acetate. The non-acidic compounds can be chemically bonded to a super absorbent material in the form of esters such as acetylated cellulose. Anhydrides are also suitable, although lactones and hydrolysable esters are somewhat less preferred than lactones, possibly because their susceptibility to hydrolysis is too high. They include anhydrides of carboxylic acids, especially cyclic anhydrides of dicarboxylic or polycarboxylic acids such as succinic acid, glutaric acid, maleic acid, citraconic acid, and phthalic acid. The amount of neutralizing agent (e.g., lactide and lactone) to be incorporated into or combined with the super absorbent material may be from 1 to 20% by weight, preferably from 3 to 12% by weight, based on the weight of the super polymer. absorbent. The amount of neutralizing agent can also be expressed in molar equivalents. In particular, the amount is between 0.05 and 1 mmol, in particular from 0.15 to 0.6 mmol per gram of the super absorbent polymer. Agents that facilitate hydrolysis to neutralizing agents can be added. A suitable example is a hydrolyzing enzyme, such as a lipase. The super absorbent materials according to the present invention can be used to absorb fluids, especially body fluids which can produce alkaline odorous components such as urine. The materials can be incorporated into any absorbent article such as sanitary napkins, incontinence pads, and baby diapers. As a model of human urine, the so-called synthetic urine (SU), is used to study the effectiveness of super absorbent materials. The composition of SU is given in table 1 below: Example 1: Baby diaper. In a baby diaper containing 13 g of polyacrylic acid as an absorbent (Libero Maxi Girl), four different alkaline neutralizing substances were placed under a non-woven part of the diaper, and at the top of the pulp. 250 ml of SU were added to the diaper. After the addition, the pH was measured at six different locations of the non-woven material using a contact electrode, and the values were averaged. The results are solved in table two. It can be seen from this table that despite the high regulatory capacity of the diaper (with >75% of the polyacrylic acid in a sodium salt form) the pH is decreased due to the hydrolysis of said precursor.

Example 2: Sanitary Towels In a sanitary napkin (Libresse) containing CTMP (chemically treated mechanical pulp) as an absorbent, three different alkaline neutralizing substances were placed in the middle part of the towel CTMP. 15 ml of SU were added to the towel. After the addition of the urine, the pH was measured at six different places of the non-woven material using a contact electrode, and the values were averaged. The results are summarized in the following table three. Table 3 shows that the addition of lactide rapidly decreases the pH, while the same amount of anhydride (maleic) results in a slower but continuous decrease in pH. A direct acid (citric acid) tends to be too acidic.

Example 3: Baby diaper. 250 ml of SURM was added to a baby diaper (Libero Maxi). Different amounts of glycolide were put into the diapers, from 0.2 g to 1.6 per diaper, below the non-woven material of the diaper and the upper part of the pulp. Each of the diapers also contains a g of lipolase 100 T (Novo Nordisk). For each pH measurement, the diaper was measured on the non-woven material at six different locations with a contact electrode. The averaged results are shown in table 4.

Table 4 Quantity of pH pH addition of pH pH after then after initial glycolide of 1 hour of 2 of 5 g mmol hours hours 0. 2 1.7 6.0 5.1 5.0 5.0 0.4 3.4 5.9 5.1 4.9 4.9 0.8 6.9 5.9 4.4 4.9 4.8 1.6 13.8 5.9 4.8 4.6 4.6

Claims (7)

1. NOVELTY OF THE INVENTION Having described the present invention, it is considered as a novelty and therefore, the property is claimed as contained in the following: CLAIMS 1. A super absorbent material comprising a non-acidic compound selected from acid anhydrides, lactones, lactones and hydrolysable esters.
2. 2. The super absorbent material according to claim 1, wherein the non-acidic compound is selected from lactones and lactones of α- or d-carboxylic acids.
3. 3. The super absorbent material according to claim 2, wherein the non-acidic compound is selected from lactic acid, glycolide and gluconolactone.
4. The super absorbent material according to any of the preceding claims, wherein the non-acidic compound is present in an amount of 1 to 20% by weight with respect to the weight of the super absorbent material.
5. 5. The super absorbent material according to any of the preceding claims, wherein the non-acidic compound is homogeneously divided into the super absorbent material.
6. 6. The super absorbent material according to any of the preceding claims, wherein the non-acidic compound is chemically bonded to the super absorbent material.
7. 7. A sanitary product such as a diaper, which comprises a super absorbent material according to any of the preceding claims.