Composition comprising a buffered lactic acid

Abstract

A composition including a buffered lactic acid having a pH within the range of from 3.0 to 6.5 is disclosed. The composition is a lubricant composition and has a water activity of from 0.03 to 0.60. The friction between the absorbent product and the skin/mucous membrane of the user is reduced when in contact with the skin or mucous membrane of the user. An additional advantage is that the composition has a pH in the acidic range which is close to the pH of the skin and/or mucous membrane.

Claims

1. A lubricant composition suitable for contacting mucous membrane or skin, comprising a buffered lactic acid present in an amount from 60 to 100 weight-%, based on the total weight of the lubricant and having a pH within the range of from 3.0 to 6.5, wherein the composition has a water activity of from 0.30 to 0.80, wherein the desired water activity has been obtained by drying.

2. A method for protecting skin and/or mucous membrane against chafing, comprising applying to the skin and/or mucous membrane a layer of the lubricant composition according to claim 1.

3. A method for protecting skin and/or mucous membrane against chafing, comprising applying to at least a portion of a hygiene and/or an absorbent product a layer of the lubricant composition according to claim 1, wherein the composition is brought in contact with the skin of the wearer during use.

4. The lubricant composition according to claim 1, wherein the pH of the composition is within the range of from 3.5 to 5.5.

5. The lubricant composition according to claim 1, wherein the water activity is from 0.30 to 0.60.

6. The lubricant composition according to claim 1, wherein a salt buffering the lactic acid in the composition is an alkali metal salt of lactic acid.

7. The lubricant composition according to claim 6, wherein the alkali metal salt is potassium lactate.

8. The lubricant composition according to claim 1, wherein the composition also comprises an essentially water-free additive.

9. The lubricant composition according to claim 8, wherein the water-free additive is naturally essentially water-free.

10. The lubricant composition according to claim 8, wherein the water-free additive is dried to be essentially water-free.

11. The lubricant composition according to claim 10, the water-free additive is chosen from the group consisting of botanical actives, prebiotic substances, probiotic bacteria, minerals, inorganic additives, salts and vitamins.

12. The lubricant composition according to claim 1, wherein the amount of the buffered lactic acid in the lubricant is about 100 weight-%, based on the total weight of the lubricant.

13. The lubricant composition according to claim 1, wherein the pH of the composition is within the range of from 3.5 to 5.5, wherein the water activity is from 0.34 to 0.80, and wherein a salt buffering the lactic acid in the composition is potassium lactate.

14. An absorbent product comprising the lubricant composition according to claim 1.

15. A lubricant composition suitable for contacting mucous membrane or skin, consisting of a buffered lactic acid present in an amount from 10 to 100 weight-%, based on the total weight of the lubricant and having a pH within the range of from 3.0 to 6.5 and optionally a water-free additive chosen from the group consisting of botanical actives, prebiotic substances, minerals, inorganic additives, salts and vitamins, wherein the composition has a water activity of from 0.30 to 0.80, wherein the desired water activity has been obtained by drying.

16. The lubricant composition according to claim 15, consisting of 0 to 40% by weight water-free additive, based on the total weight of the lubricant and of 60 to 100 wt. % buffered lactic acid.

17. An absorbent product comprising the lubricant composition according to claim 15.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Embodiments of the invention will be described in more detail, with reference to the figures that are shown on the appended drawings. In the drawings:

(2) FIG. 1 shows a perspective view of a tampon including the composition according to an embodiment of the invention,

(3) FIGS. 2a-2d show top view of examples of panty liners including the composition according to embodiments of the invention,

(4) FIG. 3 shows a top view of a sanitary towel including the composition according to an embodiment of the invention,

(5) FIG. 4 shows a perspective view of a diaper including the composition according to an embodiment of the invention,

(6) FIG. 5 shows a perspective view of a diaper including a belt including the composition according to an embodiment of the invention,

(7) FIG. 6 shows a front view of the arrangement used in example 1 to measure slip-force,

(8) FIG. 7 shows a side view of the arrangement of FIG. 6,

(9) FIG. 8 shows a diagram with the measured slip-force values,

(10) FIG. 9 shows a diagram with the measured pH values.

DETAILED DESCRIPTION OF PARTICULAR EMBODIMENTS

(11) The tampon 100 shown in FIG. 1 includes an absorption body 102 enclosed in a liquid permeable cover 103 and having two withdrawal string ends 104 that are joined together in a knot 105. The tampon 100 has an elongate bullet-shape with a longitudinal direction L and a radial direction R, perpendicular to the longitudinal direction L and an insertion end 106 and a withdrawal end 107, and a middle part 108. Each of the insertion end 106 and the withdrawal end 107 and the middle part 108 occupy approximately one third of the total length of the tampon 101. The insertion end is shown with a rounded tip 117 and a flat withdrawal end surface 120. The tampon length between the tip 117 and the withdrawal end surface 120 may be determined by means of a slide caliper. Tampons commonly have a length in the dry, non-expanded state of from 30 to 70 mm, more common from 40 to 50 mm. The length will commonly vary with the size and design absorption capacity of the tampon. In FIG. 1, the whole surface of the tampon 100 is coated with the lubrication composition 111 in accordance with an embodiment of the present invention. The lubricating composition on the surface of the tampon thus reduces the friction between the tampon and the mucous membrane of the vagina of the user.

(12) The tampon 100 is provided with longitudinally extending grooves or channels in the form of compression lines 108, 109. The compression lines are wave-shaped in FIG. 1 but they may be straight or any other suitable shape.

(13) As described above, the lubricating composition may be also be used on wearable absorbent products to reduce friction between the absorbent product and for example urogenital region of the user and/or other areas of the body of the user.

(14) The lubricating agent may be used on the wearable absorbent product to reduce the friction between the wearable absorbent product and the urogenital region of the user.

(15) FIGS. 2a-2d schematically show examples of a panty liner 200 in accordance with an embodiment of the present invention. Generally, all the panty liners 200 include a covering layer in the form of a liquid-permeable top sheet 201, as shown in FIG. 2a, that is arranged on the side of the panty liner 200 which during use faces towards the wearer. The panty liner also includes a second covering layer, a back sheet (not shown), which during use faces away from the wearer. Further, the panty liner 200 includes an absorbent core (not shown) arranged between the top sheet 201 and the back sheet. The top sheet and back sheet can be joined together in the reinforcement region 203, as shown in FIG. 2a, for example by means of gluing or ultrasonic welding. Other means for joining together the panty liner may be also used.

(16) As best shown in FIGS. 2a and 2d, the lubricating composition is coated on a crotch region 219 of the panty liner 200. The lubricating composition is applied on the surface of the panty liner 200. The lubricating composition can be positioned in the areas of the wearable absorbent product that come into contact with the urogenital region of the user, i.e. the areas in the crotch region of the wearable absorbent product. In this way, friction may be reduced between the absorbent product and the user while optimal skin care is provided due to the low pH of the composition.

(17) As shown in FIGS. 2c and 2d, the lubricating composition is coated to the surface in a spotted pattern that can be obtained for example by means of printing. In the embodiment shown in FIG. 2b, the lubricating composition is coated to the surface in a striped pattern, which may also be obtained by for example means of printing.

(18) Generally, the printing method may be chosen from any suitable means, e.g. flexographic, gravure or digital printing utilizing e.g. spray application.

(19) Of course, any coating method and the different coating patterns may be used in all kinds of tampons and/or wearable absorbent products.

(20) In another embodiment, only the outer edges on the reinforcement region 203, as illustrated in FIG. 2a, are coated with the lubrication composition to reduce friction between the thighs of the wearer and the panty liner and thus reduce the risk for chafing.

(21) In yet another embodiment, the whole surface of the panty liner 200 is coated with the lubricating composition.

(22) FIG. 3 shows a sanitary napkin 300 in accordance with an embodiment of the present invention. The sanitary napkin 300 includes a covering layer in the form of a liquid-permeable top sheet 301, which is arranged on the side of the sanitary napkin 300 which during use faces towards the wearer. The sanitary napkin 300 also includes a second covering layer, a back sheet (not shown), which during use faces away from the wearer. The sanitary napkin 300 further includes an absorbent core arranged between the top sheet 301 and the back sheet. The top sheet and back sheet are joined together in the reinforcement region 303 by means of gluing or ultrasonic welding. The sanitary towel includes wings 305 to facilitate the attachment of the sanitary napkin to an undergarment. The sanitary napkin 300 can include the lubricating composition in the crotch region of the napkin, i.e. approximately in the area located between the wings 305 so that the lubricating composition comes into contact with the urogenital region of the user.

(23) Alternatively, the outer edges on the reinforcement region 303 and/or the wings are coated with the lubrication composition 311 to reduce friction between the thighs of the wearer and the panty liner and thus reduce the risk for chafing.

(24) In a similar manner as in connection with the panty liner shown in FIGS. 2a-2d, the lubricating composition may be coated in a specific pattern to the surface of the absorbent product.

(25) FIG. 4 shows a diaper 400 for an infant or an incontinent adult in accordance with an embodiment of the present invention. The diaper includes a chassis including a liquid permeable top sheet 401, a liquid impermeable back sheet 409 and an absorbent body or core 407 enclosed there between. The top sheet 401 and the back sheet material 409 have a somewhat greater extension in the plane than the absorbent core 407 and extend outside the edges thereof. The layers 401 and 409 are connected to each other within the projecting portions thereof, e.g., by gluing or welding by heat or ultrasonic. The top sheet and/or the back sheet may further be attached to the absorbent core 407 by any method known in the art, such as adhesive, heat-bonding, etc. The absorbent core may also be unattached to the top sheet and/or the back sheet. The diaper 400 includes a front portion 415 intended during use to be worn on the front part of the user's body, a rear portion 417 intended during use to be worn on the rear part of the user's body, and a more narrow crotch region 419 located between the front and rear portions and which is intended to be worn in the crotch region of the user between the legs. The rear portion 417 is provided with a pair of adhesive tape tabs 421 or other type of attachment means such as hook-and-loop type fasteners. The diaper further includes elastic barrier flaps 423 that form leakage barriers and are at their proximal edges secured to the top sheet 401. The diaper 400 may further include an elasticized waist feature in the form of elastic members 411 extending in the transverse direction of the article in the waist portion thereof.

(26) The lubricating composition may be coated on part of the surface facing the wearer, or the composition may be coated for example on the front portion 415 and/or rear portion 417 and/or on the elastic barrier flaps 423, i.e. on the areas where there is a risk for chafing and where friction between the wearer and the diaper needs to be reduced.

(27) Alternatively, the lubricating composition may be coated on the parts of the crotch region 419 that come into contact with the urogenital region of the user. As above, in this way friction may be reduced between the absorbent product and the user while optimal skin care is provided due to the low pH of the composition.

(28) The diaper 500 shown in FIG. 5, has a similar construction as the diaper in FIG. 4, except that the diaper 500 includes belt portions 511, 521 attached to the rear portion 517 of the diaper 500 and intended to be fastened together around the waist of the wearer. Fastening means on the front part of the diaper are then attached to the outside of the belt to fasten together the diaper to the desired pant-like shape. An example of a belted diaper is shown in WO 01/00129. Similarly as in connection with the diaper shown in FIG. 4, the lubricating composition may be coated on part of the surface facing the wearer, or the composition may be coated for example on the front portion 515 and/or rear portion 517 and/or on the belt portions 511, 521, i.e. on the areas where there is a risk for chafing and where friction between the wearer and the diaper needs to be reduced.

(29) Alternatively, the lubricating composition may be coated on the parts of the crotch region 519 that come into contact with the urogenital region of the user. As above, in this way friction may be reduced between the absorbent product and the user while skin care is provided due to the low pH of the composition.

EXAMPLES

Example 1

(30) This test was performed to show if the lubricating composition including the buffered lactic acid could be used to lower shear forces and hence possibly chafe when for example used on the surfaces of tampons.

(31) The test was performed using a device illustrated in FIGS. 6 and 7. The device 600 consisted of a flat support surface 601 which was at a 30 angle from horizontal and covered with film, which was prolonged and attached to the support surface. A tampon 603 (LibresseNormalnew twist wrap) was mounted on this surface and standardized pressed on to this surface by means of a plastic ruler 605. The ruler 605 had a fixed length of 20 cm and was fixed to the flat support surface in the ends. The tampon was always positioned at the centre of the ruler, i.e. at 10 cm.

(32) A tensometer, DIA-STRON MMT 170, measured the force during the pulling of the tampon 603 from its position, pressed to the surface and under the ruler, and out. The Start position was 20 mm, displacement was 50 mm and rate was 150 mm/min. During the process of pulling out the tampon, the force varied. In the Table 1 below, the slip-force (force when tampon starts to move) was registered.

(33) Since there are small variations in size of tampons even within the same package the same tampon was measured both before and after treatment with the lubricating composition including buffered lactic acid. First, the slip-force was measured three times with the untreated tampon and thereafter the lubricating composition was distributed on the surface of the tampon and the slip-force was measured three more times. The lubricating composition was evenly distributed on the lower half of surface of the tampon by means of a tiny brush. The amount of lubricating composition on the tampons was between 0.7-0.8 g. The measured values are also shown in Table 1.

(34) In this test, many different lubricating compositions including buffered lactic acid were tested. The lactic acid was buffered with either potassium lactate or potassium hydroxide. It was buffered to different pH. The lubricating composition was dried to different levels to achieve different water activities. The instrument used to measure water activity was: AquaLab, Model Series 3 TE, Serial# TE8105. It was calibrated using lithium chloride 13.41 M and all measurements were performed in 23 C.

(35) Table 1 below shows the different lubricating compositions and the measured pH, water activity and slip-forces. The slip-force is a mean value from three repetitions.

(36) In FIG. 8, the slip force of the tampons is displayed before and after treatment with the lubricating composition.

(37) TABLE-US-00001 TABLE 1 The different samples: Tampons with buffered Lactic acid and reference tampon without Lactic acid. Slip- Salt Measured Slip- force (N) Tam- buff- water Measured force (N) Reference pon ering Mea- activity amount of with without num- Lactic sured (measured Lactic Lactic Lactic ber acid pH at 23 C.) acid (g) acid acid 1 Potassium 3.7 0.42 0.79 11.85 17.14 Lactate 2 Potassium 4.6 0.41 0.70 12.03 17.93 Lactate 3 Potassium 6.2 0.29 0.79 11.62 15.20 Lactate 4 Potassium 4.0 0.80 0.80 11.18 17.43 Lactate 5 Potassium 3.8 0.40 0.72 10.61 19.23 Hydroxide 6 Potassium 5.6 0.34 0.79 10.69 15.55 Hydroxide 7 Potassium 7.1 0.23 0.73 12.66 18.81 Hydroxide 8 Potassium 4.5 0.76 0.80 10.69 17.00 Hydroxide

(38) Based on the results in the tests it can be concluded that there was a reduced slip-force for all the tampons including the lubricating composition including lactic acid. In all cases, the tampon covered with the composition showed lower slip-force compared to the untreated tampon.

Example 2

(39) This test was performed to investigate if the lubricating composition including buffered lactic acid was able to adjust pH on skin when it was used alone and in a hydrophobic blend with Petrolatum (Snow white P1 from Sonneborn) according to table 2.

(40) 0.1 g of the composition was applied on the fore arm skin of a test person as a circular spot of about 2 cm diameter and covered by a plastic film. The composition was kept on the skin for 1 hour. Thereafter the excess of lubricating composition was gently removed with a soft wipe, gently flushed with deionised water and gently dried with a dry piece of paper. After another one minute of rest in air, pH on skin was measured using a pH meter (flat probe VWRSYMPHONY SB80PI).

(41) The composition used was produced with 15.2 ml of DL-lactic acid solution (85 weight %) which was blended with 46.6 ml potassium lactate solution (50 weight %). This blend was further dried in a dry chamber to a water activity of 0.2. This lubricating composition was further equilibrated in a climate of 25 C. and 50% rH which resulted in a water activity of 0.3. pH on the readymade lubricating composition was measured to be 4.3.

(42) TABLE-US-00002 TABLE 2 The different blends Lactate gel Petrolatum Sample (%) (%) 1 100 0 2 60 40 3 10 90 4 0 100

(43) TABLE-US-00003 TABLE 3 Measured values of pH Start value End value Sample Forearm skin Forearm skin 1 4.9 3.5 2 5.3 3.5 3 5.3 3.6 4 5.4 5.1

(44) FIG. 9 figure shows pH on forearm skinbefore and after exposure to the samples described in Table 3. As can be seen in FIG. 9 all lubricating composition containing the buffered lactic acid resulted in a pH of about 3.5 after 1 hour of exposure.

(45) Thus it can be concluded that the lubricating composition including buffered lactic acid was able to adjust pH on the fore arm skinboth alone or blended with petrolatum. The same final pH was achieved for all the blends containing the lubricating composition including buffered lactic acid.

(46) The above embodiments are merely illustrative and are in no way intended to limit the present invention.