Single-layer elastic material

Abstract

The utility model belongs to the field of elastic materials, and relates to a single-layer elastic material, which comprises an elastic chain distributed along the warp direction and provided with entanglement pores, the elastic chain is a braided wire or a stranded wire of elastic plied yarns; all the elastic chains are connected through a plurality of non-elastic strands; each strand of non-elastic plied yarn shuttles back and forth between the left elastic chain and the right elastic chain in the warp direction to form an inflection point, and the non-elastic plied yarn at the inflection point penetrates into entanglement holes of the elastic chains to form entanglement points; the elongation at break of the inelastic strands is less than or equal to 45%; in a relaxed state, the average value of the distance between every two adjacent left and right elastic chains is recorded as D *, the standard deviation is recorded as p1, D * is larger than or equal to 2 mm, and p1 is smaller than or equal to 0.2. According to the utility model, the problem that the distance between the elastic bodies is too small when the non-woven fabric is used as a substrate to fix the arrangement of the elastic bodies in the prior art is solved.

Description

Technical Field

[0001] The utility model belongs to the field of elastic materials and relates to a single-layer elastic material. Background Art

[0002] In existing disposable absorbent products such as baby diapers, women's menstrual pants, adult diapers and other sanitary and medical products, these absorbent products usually contain elastic material components to achieve the wearing function or to achieve the fit and fixation of the products to the skin. The core material constituting the elastic material is elastic strands, and the elastic strands are typically wires mainly composed of high-elastic spandex yarns.

[0003] Traditionally, elastic materials are made by bonding and assembling elastic strands with outer non-woven fabrics (including one or more layers of surface non-woven fabrics and possible bottom non-woven fabrics) in parallel arrangement. In this process, since the material structure has specific arrangement requirements for spandex yarns, multiple spandex yarns need to be used and go through a series of processes such as warping, pulling, bonding, or using specific devices to meet the requirements of use.

[0004] At present, the mainstream process is to use non-woven fabric as the substrate, and regularly arrange multiple groups of elastic strands in the horizontal direction to prepare elastic materials (i.e., three-layer non-woven fabric-based elastic materials). Subsequently, this elastic material is further used to prepare elastic components suitable for human body wear. At present, technicians in this field are still mainly improving and developing this process. For example, CN117338518A patent discloses a method for preparing elastic materials and absorbent products. The method includes the following steps: first, prepare a number of elastomers (i.e., elastic strands) and non-woven fabric substrates; then, pre-treat these elastomers; finally, according to a preset distribution method, pass the pre-treated elastomer through the non-woven fabric substrate in the form of sewing thread, and reinforce it to obtain the desired elastic material. In this way, the pre-treated elastomer is sewn to the non-woven fabric substrate, and it is firmly fixed to the non-woven fabric substrate by one or more fixing methods. This method can ensure that the elastic material will not be derailed and deformed, while also maintaining the thin and breathable properties of the elastic material, thereby improving the comfort of the user.

[0005] However, the spacing between the elastomers of the three-layer non-woven fabric-based elastic material needs to be controlled at 1mm. When the spacing between the elastomers is large, there is no supporting force between the elastomers, resulting in a large blank space after bonding with the top and bottom materials, causing poor product bonding and a high probability of wrinkles, dislocations, and cavitations, which in turn leads to a decrease in the rebound effect. Utility Model Content

[0006] The utility model aims to solve the problems existing in the prior art and provide a single-layer elastic material.

[0007] In order to achieve the above purpose, the technical solution adopted by the utility model is as follows:

[0008] A single-layer elastic material comprises elastic braids with entangled pores distributed along the warp direction;

[0009] Elastic braids are braided or twisted wires of elastic strands;

[0010] All elastic braids are connected by multiple inelastic strands;

[0011] Each non-elastic strand shuttles between the left and right elastic braided chains along the warp direction to form a turning point. When the non-elastic strand shuttles between the left and right elastic braided chains along the weft direction to form a turning point, it cannot help achieve the expected support of the elastic strand spacing. The non-elastic strand at the turning point penetrates into the entanglement pores of the elastic braided chain and forms an entanglement point by knotting, etc., so that the position of the turning point on the elastic braided chain is fixed;

[0012] The elongation at break of the non-elastic strands is ≤45% to ensure that the elastic braided chain can obtain sufficient support;

[0013] In the relaxed state, the elastic braids are distributed in equally spaced parallel lines. The average value of the spacing between all adjacent elastic braids is recorded as D*, and the standard deviation is recorded as p1. D*≥2mm, p1≤0.2. D* and p1 are calculated by randomly measuring the spacing D of 10 groups of adjacent elastic braids on a single layer of elastic material. When p1≤0.2, the elastic braids in the single-layer elastic material are considered to be distributed in equally divided parallel lines.

[0014] Traditional elastic materials require non-woven fabrics as a base to fix the arrangement of several elastic bodies (i.e. elastic strands), and are supported by two non-woven fabrics in the direction perpendicular to the elastic bodies. The inventors found that this structural design has specific requirements for the spacing between the elastic bodies. When the spacing between the elastic bodies is too large, the finished product is prone to wrinkles, dislocations, and cavitations during actual use, resulting in a decrease in the rebound effect.

[0015] The inventor has ingeniously designed a single-layer elastic material, in which the arrangement and fixation of the elastomer (i.e., elastic braid) no longer relies on the upper and lower layers of non-woven fabrics with certain support. The utility model arranges non-elastic strands between the left and right elastic braids, and utilizes the non-elastic strands to hook the elastomer to achieve the fixation of the arrangement of the elastomer.

[0016] The utility model controls each non-elastic strand to shuttle between the two elastic braided chains along the warp direction. It is found that such a strand arrangement method is beneficial to maintaining the distance between the elastic bodies.

[0017] The inventor found that on the single-layer elastic material developed by him, compared with the 1mm level of elastic body spacing commonly used in the prior art, when the elastic body spacing (i.e., braiding chain spacing) of the utility model is 2mm or larger, the single-layer elastic material actually exhibits a better rebound effect. On the other hand, the elastic material of the traditional non-woven three-layer structure shows the opposite trend. It is speculated that it may be affected by the inelastic strands. The denser the elastic body spacing, the denser the inelastic strands on the single-layer elastic material, which causes a certain obstacle to the stretching of the elastic strands.

[0018] The manufacturing process of this type of elastic material is similar to that of warp and weft knitted clothing fabrics, but they actually belong to different technical fields. The elastic material of the utility model is not suitable for clothing fabrics, specifically because this material pursues a loose arrangement between fibers, resulting in low strength, and is therefore more suitable for disposable sanitary products rather than conventional clothing fabrics. Similarly, the existing warp and weft knitted clothing fabrics cannot use the elastic material of the utility model, because the elastic material of the utility model has specific requirements for the spacing of the elastomers, and this spacing does not meet the needs of clothing fabrics and does not meet the wearability of clothing. In addition, the warp and weft knitted structure is not conducive to the elastomer obtaining good support.

[0019] As the preferred technical solution:

[0020] A single-layer elastic material as described above, at least one inelastic strand X is arranged between any two adjacent elastic braided chains on the left and right; in a relaxed state, the spacings between the inflection points on the same inelastic strand X are equal, the average spacing between all two adjacent inflection points on the same inelastic strand X is recorded as L*, the standard deviation is recorded as p2, L* / D* is greater than 1 and less than 1.4, p2≤0.2, L* and p2 are calculated by randomly measuring 10 groups of spacings L between two adjacent inflection points on the same inelastic strand X, When p2≤0.2, the spacing between the inflection points on the same inelastic strand X is considered to be equal;

[0021] The equal spacing between any two adjacent inflection points on the same inelastic strand X can make the minimum unit support force between two adjacent braided chains of the single-layer elastic material come from the V-shaped structure formed by the single inelastic strand X. If the spacing between any two adjacent inflection points on the same inelastic strand X differs too much, that is, the lengths of the two line segments forming the V-shaped structure differ too much, then when subjected to external force, the support force allocated to the inelastic strand X at the same entanglement point is uneven, which will cause the support for the elastic braided chain to deteriorate.

[0022] The utility model controls L* / D* to be greater than 1 and less than 1.4, thereby ensuring that the non-elastic strands can effectively support the two adjacent elastic braided chains on the left and right.

[0023] In the above-mentioned single-layer elastic material, a non-elastic strand X is arranged between any two adjacent elastic braided chains on the left and right, or two or more non-elastic strands X with the same or different shapes are arranged; during preparation, the same crochet speed process parameter can be set to adjust the L value of the non-elastic strand X. Under the same process, the relative deviation fluctuation of L* corresponding to the two non-elastic strands X is normal within ±5%, and the two non-elastic strands X can be regarded as having the same shape; otherwise, the two non-elastic strands X are regarded as having different shapes; relative deviation = (absolute value of the difference of L* corresponding to the two non-elastic strands X / average value of L* corresponding to the two non-elastic strands X) × 100%.

[0024] In the single-layer elastic material as described above, the number and shape of the inelastic strands X between any two adjacent elastic braids on the left and right are the same; that is, when one inelastic strand X is set between any two adjacent elastic braids on the left and right, the shapes of all the inelastic strands X are the same; when more than two inelastic strands X with the same shape are set between any two adjacent elastic braids on the left and right, the shapes of all the inelastic strands X are the same; when more than two inelastic strands X with different shapes are set between any two adjacent elastic braids on the left and right, assuming that the more than two inelastic strands X with different shapes are inelastic strands X1, inelastic strands X2..., then the shapes of all the inelastic strands X1 are the same, and the shapes of all the inelastic strands X2 are the same; such an arrangement can make the single-layer elastic material have a better feel.

[0025] As described above, a single-layer elastic material, the elastic chain is composed of a single strand of elastic yarn, and the elastic yarn itself is woven to form the elastic chain; or, the elastic chain is composed of two or more strands of elastic yarn, and the elastic yarns are connected to form the elastic chain in any form (such as S-winding or twisted weaving, etc.); entanglement pores are formed at the weaving entanglement of the elastic chain.

[0026] A single-layer elastic material as described above, wherein the elastic strands in all elastic braids have the same material, specification, and number of crocheted strands, and the number of crocheted strands of the elastic strands in the elastic braid is adjusted according to actual needs, for example, it can be 1 strand, 3 strands, 5 strands, 10 strands, etc., to control the overall thickness of the elastic braid to meet target needs; the materials and specifications of all non-elastic strands are the same; the linear density of the elastic strand is 16.5-155 dtex; the linear density of the non-elastic strand = α × the linear density of the elastic strand × the number of crocheted strands of the elastic strand in the elastic braid, and the value range of α is 1.1-2.0; in the field of sanitary materials , especially in the field of diaper wearing, there is a high requirement for feelingless wearing, that is, it should not cause obvious wearing pressure to the human body. The utility model sets the linear density of the non-elastic strands according to the linear density of the elastic strands and the number of hooked strands of the elastic strands in the elastic chain. This can avoid the situation where the linear density of the non-elastic strands is too large relative to the linear density of the elastic chain, the non-elastic strands are seriously exposed, and their material is relatively hard, resulting in excessive friction, which is easy to cause uncomfortable body feeling during use. It can also avoid the situation where the linear density of the non-elastic strands is too small, resulting in insufficient support for the non-elastic strands, making it difficult to maintain the target spacing between the elastic chains.

[0027] For a single-layer elastic material as described above, the breaking strength of the elastic strand is ≥0.7 cN / dtex, the elongation at break is ≥470%, and the 300% elastic recovery rate is ≥90%; the breaking strength of the inelastic strand is ≥2.5 cN / dtex, and the inelastic strand should have a certain breaking strength to meet the processability of the single-layer elastic material, and the elongation at break is ≥20%. If the elongation at break of the inelastic strand is too low, the rigidity of the fiber is too strong, resulting in the single-layer elastic material feeling too hard, which can easily make the sanitary product uncomfortable to wear and cause a sense of oppression on the skin.

[0028] For a single-layer elastic material as described above, D*≤10mm; the larger the spacing between the elastic bodies, the more difficult it is to achieve the supporting effect, and the corresponding rebound effect will also be attenuated. Therefore, the utility model sets an upper limit for the spacing between the braided chains to reduce the difficulty of achieving the supporting effect.

[0029] A single-layer elastic material as described above has a tensile elastic recovery rate of 95-99% and a stiffness of 5-10.5 mm; the wear performance test result of the single-layer elastic material is comfortable to wear and has no marks. The non-elastic strands in the single-layer elastic material have a good supporting effect on the elastic braid, showing better stiffness. The single-layer elastic material has good elastic recovery. When the single-layer elastic material is subjected to external force in any direction, after the external force is removed, the distance between any two adjacent elastic braids on the left and right is restored to the distance before the external force is applied.

[0030] Beneficial effects:

[0031] The utility model arranges non-elastic strands between the left and right elastic braided chains, and uses the non-elastic strands to hook the elastic body to achieve the fixation of the elastic body arrangement, thereby solving the problem of too small spacing between the elastic bodies when the non-woven fabric is used as a base to fix the arrangement of several elastic bodies (i.e., elastic strands) in the prior art. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 Schematic diagrams of elastic chains woven by single, double and triple elastic strands, respectively; a is a schematic diagram of an elastic chain woven by a single elastic strand, b is a schematic diagram of an elastic chain woven by twisting double elastic strands, and c is a schematic diagram of an elastic chain woven by twisting three elastic strands;

[0033] Figure 2 It is a schematic diagram of a non-elastic strand of the utility model being knotted in an entanglement pore of an elastic braided chain composed of a single elastic strand to form an entanglement point;

[0034] Figure 3 It is a schematic diagram of a non-elastic strand of the utility model being knotted in an entanglement hole of an elastic braided chain consisting of three elastic strands to form an entanglement point;

[0035] Figure 4 The figure is a schematic diagram of the shuttling of the inelastic strands between any two adjacent elastic braided chains on the left and right sides of the single-layer elastic material of the utility model; wherein A1 to A3 represent three adjacent inflection points respectively;

[0036] Figure 5 Schematic diagrams of the shuttling of the inelastic strands between the 1st to 3rd elastic braids from the left in the single-layer elastic material of Examples 1 to 5 of the present invention; wherein, a is a schematic diagram of the shuttling of the inelastic strands between the 1st to 3rd elastic braids from the left in the single-layer elastic material of Examples 1 and 4 to 5, b is a schematic diagram of the shuttling of the inelastic strands between the 1st to 3rd elastic braids from the left in the single-layer elastic material of Example 2, and c is a schematic diagram of the shuttling of the inelastic strands between the 1st to 3rd elastic braids from the left in the single-layer elastic material of Example 3;

[0037] Figure 6 Schematic diagrams of the shuttling of the inelastic strands between the 1st to 3rd elastic braids from the left in the single-layer elastic material of Examples 6 to 7 of the present invention; wherein a is a schematic diagram of the shuttling of the inelastic strands between the 1st to 3rd elastic braids from the left in the single-layer elastic material of Example 6, and b is a schematic diagram of the shuttling of the inelastic strands between the 1st to 3rd elastic braids from the left in the single-layer elastic material of Example 7;

[0038] Figure 7 Schematic diagram of the stiffness test of the utility model; wherein a corresponds to the initial stage of the test, and b corresponds to the termination stage of the test;

[0039] Among them, 1-entanglement pores, 2-non-elastic strands, 3-elastic braided chains, 4-entanglement points, and 5-elastic strands. DETAILED DESCRIPTION

[0040] The present invention is further described below in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and are not used to limit the scope of the present invention. In addition, it should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms also fall within the scope defined by the claims attached to this application.

[0041] The following is an explanation of the terms used in this utility model:

[0042] "Relaxed state" refers to the state of a single layer of elastic material when no external force is applied.

[0043] "Stress state" refers to the state of a single layer of elastic material when it is subjected to an external force.

[0044] Unless otherwise specified, all numerical values ​​representing the specification and dimension parameters herein should be understood to include rounded values ​​in all cases. For example, the actual calculated average deviation p of 0.18 and 0.23 should be considered equal to the value of 0.2.

[0045] The utility model defines elastic strands by parameters such as linear density, stretch ratio and stretch recovery rate, and is not limited to specific fiber material categories. For example, spandex, rubber, TPEE fiber, etc., as long as the fiber materials meet these parameters, they belong to the selection range of the elastic strands of the utility model. The selection and restriction of elastic strands are already within the scope of the prior art. Therefore, technicians in this field can make appropriate adjustments according to specific application requirements.

[0046] The present invention defines the inelastic strands by parameters such as linear density and tensile strength, and is not limited to a specific fiber material category. For example, polyester filament, polyester low-elastic yarn, nylon filament, nylon low-elastic yarn, PLA filament and PLA low-elastic yarn, as long as the fiber materials meet the specified linear density, tensile strength and other parameters, they all fall within the selection range of the inelastic strands of the present invention. The selection and restriction of inelastic strands are already within the scope of the prior art. Therefore, those skilled in the art can make appropriate adjustments according to specific application requirements.

[0047] The testing methods of the relevant performance indicators in the following embodiments and comparative examples are as follows:

[0048] Line density: elastic and inelastic strands are tested according to FZ / T54010-2014 standard.

[0049] Breaking strength: elastic and inelastic strands were tested according to FZ / T54010-2014 standard;

[0050] Elongation at break: elastic and inelastic strands were tested according to FZ / T54010-2014 standard;

[0051] 300% elastic recovery rate: elastic strands are tested according to FZ / T54010-2014 standard;

[0052] Rebound effect: The single-layer elastic material was tested with reference to the method standard 8.3.1.1 of FZ / T70006-2022 standard, and the tensile elastic recovery rate was measured. The predetermined elongation was 200%, the pre-tension was 0.1N, and the stretching speed was 300mm / min.

[0053] Stiffness test: Figure 7 As shown, a single-layer elastic material is made into a sample with a length (i.e., l1) × width of 200mm × 60mm. The sample is placed on the plane of a sample table with a slope angle of 30° (length × width of 500mm × 80mm), and pushed in the direction of the slope at a speed of 100mm / min. When the head direction of the sample touches the slope, the pushing is stopped. At this time, the length l2 of the sample located on the plane of the sample table is measured. Calculate a=l1-l2, and use a to represent the stiffness. The smaller a is, the worse the stiffness of the sample is.

[0054] Wearing performance test: a single layer of elastic material is made into a circle with a length × width of 60 cm × 15 cm, and worn on a person with a waist circumference of 75-85 cm. After 4 hours, the comfort and marks are evaluated.

[0055] Example 1

[0056] A method for preparing a single-layer elastic material, the specific steps are as follows:

[0057] (1) Preparation of raw materials;

[0058] Elastic strands: Line density is 16.5dtex, breaking strength is 0.9cN / dtex, breaking elongation is 470%, 300% elastic recovery is 90%;

[0059] Non-elastic strands: Line density 33dtex, breaking strength 3.5cN / dtex, breaking elongation 25%;

[0060] (2) Warping and arranging;

[0061] Warping the elastic strands and pulling each of the elastic strands onto each needle eye of the needle bed 1, respectively, and adjusting the distance between two adjacent needle eyes until the needle eyes of the needle bed 1 are arranged at equal intervals;

[0062] Warping the inelastic strands and pulling each inelastic strand onto each needle eye of the needle bed 2, respectively, and adjusting the distance between two adjacent needle eyes until the needle eyes of the needle bed 2 are arranged at equal distances;

[0063] The needle eyes of two adjacent needle beds 1 each have a corresponding needle eye of needle bed 2;

[0064] (3) Crochet;

[0065] The needle holes of two adjacent needle beds 1 respectively knit two strands of elastic yarn to form a left elastic knitted chain and a right elastic knitted chain with entangled pores;

[0066] The left elastic braided chain and the right elastic braided chain move forward along the warp direction at a uniform speed;

[0067] The needle eyes of the corresponding needle bed 2 reciprocate at a uniform speed in the weft direction. When it moves to the left elastic chain, a single inelastic strand is inserted into the entanglement pores of the left elastic chain and a knot is formed by inserting a crochet hook into the knot. When it moves to the right elastic chain, a single inelastic strand is inserted into the entanglement pores of the right elastic chain and a knot is formed by inserting a crochet hook into the knot.

[0068] The final single-layer elastic material is composed of non-elastic strands and elastic braids with entangled pores distributed along the warp direction;

[0069] The elastic braided chain is a braided line composed of a single elastic strand, as shown in the figure. Figure 1 As shown in a, the entangled pores 1 are distributed along the warp direction; the linear density of the non-elastic strands = α × the linear density of the elastic strands × the number of crocheted strands of the elastic strands in the elastic braid, and the value of α is 2.0;

[0070] In the relaxed state, the elastic braids are distributed in equally spaced parallel lines. The average value of the spacing between all adjacent elastic braids is recorded as D*, and the standard deviation is recorded as p1. D* is 2 mm, and p1 is 0.2.

[0071] A non-elastic strand is arranged between any two adjacent elastic braided chains on the left and right;

[0072] Each non-elastic strand shuttles along the warp direction between the two adjacent elastic braided chains on the left and right to form a turning point, such as Figure 2 As shown, the non-elastic strand 2 at the inflection point penetrates into the entanglement pore 1 of the elastic braided chain 3 and forms an entanglement point 4 by knotting or the like;

[0073] The entire single-layer elastic material is composed of Figure 5 The structure shown in a is used as a basic unit and is laid repeatedly to the right. In the relaxed state, the spacing between the inflection points on the same inelastic strand is equal. The average spacing between all two adjacent inflection points on the same inelastic strand is recorded as L*, and the standard deviation is recorded as p2. L* / D* is 1.4, and p2 is 0.2.

[0074] The tensile elastic recovery rate of the single-layer elastic material is 96%, and the stiffness is 5mm. The wearing performance test result of the single-layer elastic material is that it is comfortable to wear and leaves no marks.

[0075] The above-described single-layer elastic material can be used to prepare elastic components of disposable absorbent articles.

[0076] Comparative Example 1

[0077] A single-layer elastic material, which is basically the same as the first embodiment, except that: in a relaxed state, the elastic braids are distributed in parallel lines equally spaced, and the average value D* of the spacing between two adjacent elastic braids on the left and right is 1.5 mm; in a relaxed state, the average value L* of the spacing between two adjacent inflection points on the same non-elastic strand is 2.1;

[0078] The tensile elastic recovery rate of the single-layer elastic material is 89% and the stiffness is 6mm.

[0079] By comparing Comparative Example 1 with Example 1, it can be seen that the single-layer elastic material prepared in Example 1 has a better rebound effect. This is because when the braiding chain spacing is 2 mm or larger, a better rebound effect is exhibited.

[0080] Comparative Example 2

[0081] A single-layer elastic material, which is substantially the same as that of Embodiment 1, except that: in a relaxed state, the average distance L* between all two adjacent inflection points on the same non-elastic strand is 3, and L* / D* is 1.5;

[0082] The tensile elastic recovery rate of the single-layer elastic material is 95%, and the stiffness is 2.5mm.

[0083] By comparing Comparative Example 2 with Example 1, it can be seen that the non-elastic strands in the single-layer elastic material prepared in Example 1 can effectively support two adjacent elastic braided chains on the left and right.

[0084] Comparative Example 3

[0085] A method for preparing a single-layer elastic material is basically the same as that of Example 1, except that the elongation at break of the non-elastic strand prepared in step (1) is 16%.

[0086] The tensile elastic recovery rate of the single-layer elastic material finally prepared is 93%, and the stiffness is 7.2 mm. The wearing performance test result of the single-layer elastic material is that there is a sense of oppression, and there will be marks after wearing for 4 hours.

[0087] By comparing Comparative Example 3 with Example 1, it can be seen that the single-layer elastic material prepared in Comparative Example 3 has poor rebound effect and high stiffness. The product prepared therefrom will have a sense of oppression during use and will have marks after wearing for 4 hours.

[0088] Comparative Example 4

[0089] A method for preparing a single-layer elastic material is basically the same as that of Example 1, except that the elongation at break of the non-elastic strand prepared in step (1) is 55%.

[0090] The final single-layer elastic material has a tensile elastic recovery rate of 94% and a stiffness of 2.7 mm.

[0091] By comparing Comparative Example 4 with Example 1, it can be seen that the single-layer elastic material prepared in Comparative Example 4 has poor stiffness and insufficient support.

[0092] Comparative Example 5

[0093] A method for preparing a single-layer elastic material is basically the same as that in Example 1, except that the linear density of the non-elastic strands prepared in step (1) is 50 dtex.

[0094] The single-layer elastic material finally obtained is basically the same as that in Example 1, except that: the value of α is 3.0;

[0095] The tensile elastic recovery rate of the single-layer elastic material is 92%, and the stiffness is 6.5mm. The wearing performance test result of the single-layer elastic material is that there is a sense of oppression, and there will be marks after wearing for 4 hours.

[0096] By comparing Comparative Example 5 with Example 1, it can be seen that the single-layer elastic material prepared in Comparative Example 5 has a poor rebound effect. This is because the linear density of the non-elastic strands is too large, which will lead to excessive friction. The product prepared therefrom is likely to cause an uncomfortable feeling during use, and there will be marks after being worn for 4 hours.

[0097] Comparative Example 6

[0098] A method for preparing a single-layer elastic material is basically the same as that in Example 1, except that the linear density of the non-elastic strands prepared in step (1) is 10 dtex.

[0099] The single-layer elastic material finally obtained is basically the same as that in Example 1, except that the value of α is 0.6.

[0100] The tensile elastic recovery rate of the single-layer elastic material is 95%, and the stiffness is 3.1mm.

[0101] Comparing Comparative Example 6 with Example 1, it can be seen that the stiffness of the single-layer elastic material prepared in Comparative Example 6 is poor. This is because the linear density of the non-elastic strands is too small, which leads to insufficient support of the non-elastic strands and makes it difficult to maintain the target spacing between the elastic braids.

[0102] Example 2

[0103] A method for preparing a single-layer elastic material, the specific steps are as follows:

[0104] (1) Preparation of raw materials;

[0105] Elastic strands: Line density 33.3dtex, breaking strength 1.05cN / dtex, breaking elongation 500%, 300% elastic recovery 91%;

[0106] Non-elastic strands: Line density 56dtex, breaking strength 3.2cN / dtex, breaking elongation 35%;

[0107] (2) Warping and arranging;

[0108] Warping the elastic strands and pulling each of the elastic strands onto each needle eye of the needle bed 1, respectively, and adjusting the distance between two adjacent needle eyes until the needle eyes of the needle bed 1 are arranged at equal intervals;

[0109] Warping the inelastic strands and pulling each inelastic strand onto each needle eye of the needle bed 2, respectively, and adjusting the distance between two adjacent needle eyes until the needle eyes of the needle bed 2 are arranged at equal distances;

[0110] The needle eyes of two adjacent needle beds 1 each have a corresponding needle eye of needle bed 2;

[0111] (3) Crochet;

[0112] The needle holes of two adjacent needle beds 1 respectively knit two strands of elastic yarn to form a left elastic knitted chain and a right elastic knitted chain with entangled pores;

[0113] The left elastic braided chain and the right elastic braided chain move forward along the warp direction at a uniform speed;

[0114] The needle eyes of the corresponding needle bed 2 reciprocate at a uniform speed in the weft direction. When it moves to the left elastic chain, a single inelastic strand is inserted into the entanglement pores of the left elastic chain and a knot is formed by inserting a crochet hook into the knot. When it moves to the right elastic chain, a single inelastic strand is inserted into the entanglement pores of the right elastic chain and a knot is formed by inserting a crochet hook into the knot.

[0115] The final single-layer elastic material is composed of non-elastic strands and elastic braids with entangled pores distributed along the warp direction;

[0116] The elastic braided chain is a braided line composed of a single elastic strand, as shown in the figure. Figure 1 As shown in a, the entangled pores 1 are distributed along the warp direction; the linear density of the non-elastic strands = α × the linear density of the elastic strands × the number of crocheted strands of the elastic strands in the elastic braid, and the value of α is 1.7;

[0117] In the relaxed state, the elastic braids are distributed in equally spaced parallel lines. The average value of the spacing between all adjacent elastic braids is recorded as D*, and the standard deviation is recorded as p1. D* is 3 mm, and p1 is 0.2.

[0118] A non-elastic strand is arranged between any two adjacent elastic braided chains on the left and right;

[0119] like Figure 4 As shown, each non-elastic strand shuttles between two adjacent elastic braided chains along the warp direction to form an inflection point, and the non-elastic strand at the inflection point penetrates into the entanglement pores of the elastic braided chain and forms an entanglement point by knotting or the like;

[0120] The entire single-layer elastic material is composed of Figure 5 The structure shown in b is used as a basic unit, which is formed by repeatedly laying to the right. In the relaxed state, the spacing between the inflection points on the same inelastic strand is equal. The average spacing between all two adjacent inflection points on the same inelastic strand is recorded as L*, and the standard deviation is recorded as p2. L* / D* is 1.23, and p2 is 0.2.

[0121] The tensile elastic recovery rate of the single-layer elastic material is 98%, and the stiffness is 5.5mm. The wearing performance test results of the single-layer elastic material are comfortable to wear and leave no marks.

[0122] The above-described single-layer elastic material can be used to prepare elastic components of disposable absorbent articles.

[0123] Example 3

[0124] A method for preparing a single-layer elastic material, the specific steps are as follows:

[0125] (1) Preparation of raw materials;

[0126] Elastic strands: Line density 44dtex, breaking strength 1cN / dtex, breaking elongation 520%, 300% elastic recovery 92%;

[0127] Non-elastic strands: Line density 78dtex, breaking strength 3.8cN / dtex, elongation at break 36%;

[0128] (2) Warping and arranging;

[0129] Warping the elastic strands and pulling each of the elastic strands onto each needle eye of the needle bed 1, respectively, and adjusting the distance between two adjacent needle eyes until the needle eyes of the needle bed 1 are arranged at equal intervals;

[0130] Warping the inelastic strands and pulling each inelastic strand onto each needle eye of the needle bed 2, respectively, and adjusting the distance between two adjacent needle eyes until the needle eyes of the needle bed 2 are arranged at equal distances;

[0131] The needle eyes of two adjacent needle beds 1 each have a corresponding needle eye of needle bed 2;

[0132] (3) Crochet;

[0133] The needle holes of two adjacent needle beds 1 respectively knit two strands of elastic yarn to form a left elastic knitted chain and a right elastic knitted chain with entangled pores;

[0134] The left elastic braided chain and the right elastic braided chain move forward along the warp direction at a uniform speed;

[0135] The needle eyes of the corresponding needle bed 2 reciprocate at a uniform speed in the weft direction. When it moves to the left elastic chain, a single inelastic strand is inserted into the entanglement pores of the left elastic chain and a knot is formed by inserting a crochet hook into the knot. When it moves to the right elastic chain, a single inelastic strand is inserted into the entanglement pores of the right elastic chain and a knot is formed by inserting a crochet hook into the knot.

[0136] The final single-layer elastic material is composed of non-elastic strands and elastic braids with entangled pores distributed along the warp direction;

[0137] The elastic braided chain is a braided line composed of a single elastic strand, as shown in the figure. Figure 1 As shown in a, the entangled pores 1 are distributed along the warp direction; the linear density of the non-elastic strands = α × the linear density of the elastic strands × the number of hooked strands of the elastic strands in the elastic braided chain, and the value of α is 1.8;

[0138] In the relaxed state, the elastic braids are distributed in equally spaced parallel lines. The average value of the spacing between all adjacent elastic braids is recorded as D*, and the standard deviation is recorded as p1. D* is 3.7 mm, and p1 is 0.2.

[0139] A non-elastic strand is arranged between any two adjacent elastic braided chains on the left and right;

[0140] Each non-elastic strand shuttles between two adjacent elastic braided chains along the warp direction to form an inflection point. At the inflection point, the non-elastic strand penetrates into the entanglement pores of the elastic braided chain and forms an entanglement point by knotting or the like.

[0141] The entire single-layer elastic material is composed of Figure 5 The structure shown in c is used as a basic unit, which is laid repeatedly to the right. In the relaxed state, the spacing between the inflection points on the same inelastic strand is equal. The average spacing between all two adjacent inflection points on the same inelastic strand is recorded as L*, and the standard deviation is recorded as p2. L* / D* is 1.08, and p2 is 0.1.

[0142] The tensile elastic recovery rate of the single-layer elastic material is 98%, and the stiffness is 6.2mm. The wearing performance test results of the single-layer elastic material are comfortable to wear and leave no marks.

[0143] The above-described single-layer elastic material can be used to prepare elastic components of disposable absorbent articles.

[0144] Example 4

[0145] A method for preparing a single-layer elastic material, the specific steps are as follows:

[0146] (1) Preparation of raw materials;

[0147] Elastic strands: Line density 78dtex, breaking strength 1.1cN / dtex, breaking elongation 550%, 300% elastic recovery 93%;

[0148] Non-elastic strands: Line density 111dtex, breaking strength 4.1cN / dtex, breaking elongation 42%;

[0149] (2) Warping and arranging;

[0150] Warping the elastic strands and pulling each of the elastic strands onto each needle eye of the needle bed 1, respectively, and adjusting the distance between two adjacent needle eyes until the needle eyes of the needle bed 1 are arranged at equal intervals;

[0151] Warping the inelastic strands and pulling each inelastic strand onto each needle eye of the needle bed 2, respectively, and adjusting the distance between two adjacent needle eyes until the needle eyes of the needle bed 2 are arranged at equal distances;

[0152] The needle eyes of two adjacent needle beds 1 each have a corresponding needle eye of needle bed 2;

[0153] (3) Crochet;

[0154] The needle holes of two adjacent needle beds 1 respectively knit two strands of elastic yarn to form a left elastic knitted chain and a right elastic knitted chain with entangled pores;

[0155] The left elastic braided chain and the right elastic braided chain move forward along the warp direction at a uniform speed;

[0156] The needle eyes of the corresponding needle bed 2 reciprocate at a uniform speed in the weft direction. When it moves to the left elastic chain, a single inelastic strand is inserted into the entanglement pores of the left elastic chain and a knot is formed by inserting a crochet hook into the knot. When it moves to the right elastic chain, a single inelastic strand is inserted into the entanglement pores of the right elastic chain and a knot is formed by inserting a crochet hook into the knot.

[0157] The final single-layer elastic material is composed of non-elastic strands and elastic braids with entangled pores distributed along the warp direction;

[0158] The elastic braided chain is a braided line composed of a single elastic strand, as shown in the figure. Figure 1As shown in a, the entangled pores 1 are distributed along the warp direction; the linear density of the non-elastic strands = α × the linear density of the elastic strands × the number of crocheted strands of the elastic strands in the elastic braid, and the value of α is 1.4;

[0159] In the relaxed state, the elastic braids are distributed in equally spaced parallel lines. The average value of the spacing between all adjacent elastic braids is recorded as D*, and the standard deviation is recorded as p1. D* is 6.5 mm, and p1 is 0.2.

[0160] A non-elastic strand is arranged between any two adjacent elastic braided chains on the left and right;

[0161] Each non-elastic strand shuttles between two adjacent elastic braided chains along the warp direction to form an inflection point. At the inflection point, the non-elastic strand penetrates into the entanglement pores of the elastic braided chain and forms an entanglement point by knotting or the like.

[0162] The entire single-layer elastic material is composed of Figure 5 The structure shown in a is used as a basic unit and is formed by repeatedly laying to the right. In the relaxed state, the spacing between the inflection points on the same inelastic strand is equal. The average spacing between all two adjacent inflection points on the same inelastic strand is recorded as L*, and the standard deviation is recorded as p2. L* / D* is 1.12, and p2 is 0.2.

[0163] The tensile elastic recovery rate of the single-layer elastic material is 99%, and the stiffness is 9mm. The wearing performance test results of the single-layer elastic material are comfortable to wear and leave no marks.

[0164] The above-described single-layer elastic material can be used to prepare elastic components of disposable absorbent articles.

[0165] Example 5

[0166] A method for preparing a single-layer elastic material, the specific steps are as follows:

[0167] (1) Preparation of raw materials;

[0168] Elastic strands: Line density is 155dtex, breaking strength is 0.7cN / dtex, breaking elongation is 560%, 300% elastic recovery is 93%;

[0169] Non-elastic strands: Line density 165dtex, breaking strength 2.5cN / dtex, breaking elongation 23%;

[0170] (2) Warping and arranging;

[0171] Warping the elastic strands and pulling each of the elastic strands onto each needle eye of the needle bed 1, respectively, and adjusting the distance between two adjacent needle eyes until the needle eyes of the needle bed 1 are arranged at equal intervals;

[0172] Warping the inelastic strands and pulling each inelastic strand onto each needle eye of the needle bed 2, respectively, and adjusting the distance between two adjacent needle eyes until the needle eyes of the needle bed 2 are arranged at equal distances;

[0173] The needle eyes of two adjacent needle beds 1 each have a corresponding needle eye of needle bed 2;

[0174] (3) Crochet;

[0175] The needle holes of two adjacent needle beds 1 respectively knit two strands of elastic yarn to form a left elastic knitted chain and a right elastic knitted chain with entangled pores;

[0176] The left elastic braided chain and the right elastic braided chain move forward along the warp direction at a uniform speed;

[0177] The needle eyes of the corresponding needle bed 2 reciprocate at a uniform speed in the weft direction. When it moves to the left elastic chain, a single inelastic strand is inserted into the entanglement pores of the left elastic chain and a knot is formed by inserting a crochet hook into the knot. When it moves to the right elastic chain, a single inelastic strand is inserted into the entanglement pores of the right elastic chain and a knot is formed by inserting a crochet hook into the knot.

[0178] The final single-layer elastic material is composed of non-elastic strands and elastic braids with entangled pores distributed along the warp direction;

[0179] The elastic braided chain is a braided line composed of a single elastic strand, as shown in the figure. Figure 1 As shown in a, the entangled pores 1 are distributed along the warp direction; the linear density of the non-elastic strands = α × the linear density of the elastic strands × the number of crocheted strands of the elastic strands in the elastic braid, and the value of α is 1.1;

[0180] In the relaxed state, the elastic braids are distributed in equally spaced parallel lines. The average value of the spacing between all adjacent elastic braids is recorded as D*, and the standard deviation is recorded as p1. D* is 10 mm, and p1 is 0.2.

[0181] A non-elastic strand is arranged between any two adjacent elastic braided chains on the left and right;

[0182] Each non-elastic strand shuttles between two adjacent elastic braided chains along the warp direction to form an inflection point. At the inflection point, the non-elastic strand penetrates into the entanglement pores of the elastic braided chain and forms an entanglement point by knotting or the like.

[0183] The entire single-layer elastic material is composed of Figure 5 The structure shown in a is used as a basic unit and is laid repeatedly to the right. In the relaxed state, the spacing between the inflection points on the same inelastic strand is equal. The average spacing between all two adjacent inflection points on the same inelastic strand is recorded as L*, and the standard deviation is recorded as p2. L* / D* is 1.11, and p2 is 0.2.

[0184] The tensile elastic recovery rate of the single-layer elastic material is 97%, and the stiffness is 10.5mm. The wearing performance test results of the single-layer elastic material are comfortable to wear and leave no marks.

[0185] The above-described single-layer elastic material can be used to prepare elastic components of disposable absorbent articles.

[0186] Example 6

[0187] A method for preparing a single-layer elastic material, the specific steps are as follows:

[0188] (1) Preparation of raw materials;

[0189] Elastic strands: Line density is 16.5dtex, breaking strength is 0.9cN / dtex, breaking elongation is 470%, 300% elastic recovery is 90%;

[0190] Non-elastic strands: Line density 33dtex, breaking strength 3.5cN / dtex, breaking elongation 25%;

[0191] (2) Warping and arranging;

[0192] Warping the elastic strands and pulling each of the elastic strands onto each needle eye of the needle bed 1, respectively, and adjusting the distance between two adjacent needle eyes until the needle eyes of the needle bed 1 are arranged at equal intervals;

[0193] Warping the inelastic strands and pulling each inelastic strand onto each needle eye of the needle bed 2, respectively, and adjusting the distance between two adjacent needle eyes until the needle eyes of the needle bed 2 are arranged at equal distances;

[0194] The needle eyes of two adjacent needle beds 1 each have a corresponding needle eye of needle bed 2;

[0195] (3) Crochet;

[0196] The needle holes of two adjacent needle beds 1 respectively knit two strands of elastic yarn to form a left elastic knitted chain and a right elastic knitted chain with entangled pores;

[0197] The left elastic braided chain and the right elastic braided chain move forward along the warp direction at a uniform speed;

[0198] The needle eyes of the corresponding needle bed 2 reciprocate at a uniform speed in the weft direction. When it moves to the left elastic chain, a single inelastic strand is inserted into the entanglement pores of the left elastic chain and a knot is formed by inserting a crochet hook into the knot. When it moves to the right elastic chain, a single inelastic strand is inserted into the entanglement pores of the right elastic chain and a knot is formed by inserting a crochet hook into the knot.

[0199] The final single-layer elastic material is composed of non-elastic strands and elastic braids with entangled pores distributed along the warp direction;

[0200] The elastic chain is a twisted wire composed of two elastic strands, as shown in the figure. Figure 1 As shown in b, the entangled pores 1 are distributed along the warp direction; the linear density of the non-elastic strands = α × the linear density of the elastic strands × the number of crocheted strands of the elastic strands in the elastic braid, and the value of α is 1;

[0201] In the relaxed state, the elastic braids are distributed in equally spaced parallel lines. The average value of the spacing between all adjacent elastic braids is recorded as D*, and the standard deviation is recorded as p1. D* is 3.5 mm, and p1 is 0.11.

[0202] Two inelastic strands are arranged between any two adjacent elastic braided chains, namely, an elastic strand X1 and an elastic strand X2;

[0203] Each non-elastic strand shuttles between two adjacent elastic braided chains along the warp direction to form an inflection point. At the inflection point, the non-elastic strand penetrates into the entanglement pores of the elastic braided chain and forms an entanglement point by knotting or the like.

[0204] The entire single-layer elastic material is composed of Figure 6 The structure shown in a is the basic unit, which is laid repeatedly to the right. Figure 6 The structure shown in a has four elastic strands in total, two elastic strands X1 have the same shape, two elastic strands X2 have the same shape, and the elastic strands X1 and the elastic strands X2 have the same shape; in a relaxed state, the spacing between the inflection points on the same inelastic strand X1 is equal, the average spacing between all two adjacent inflection points on the same inelastic strand X1 is recorded as L1*, the standard deviation is recorded as p2, L1* / D* is 1.37, and p2 is 0.24; in a relaxed state, the spacing between the inflection points on the same inelastic strand X1 is equal, the average spacing between all two adjacent inflection points on the same inelastic strand X2 is recorded as L2*, the standard deviation is recorded as p2, L2* / D* is 1.34, and p3 is 0.22;

[0205] The tensile elastic recovery rate of the single-layer elastic material is 95%, and the stiffness is 5.5mm. The wearing performance test results of the single-layer elastic material are comfortable to wear and leave no marks.

[0206] The above-described single-layer elastic material can be used to prepare elastic components of disposable absorbent articles.

[0207] Example 7

[0208] A method for preparing a single-layer elastic material, the specific steps are as follows:

[0209] (1) Preparation of raw materials;

[0210] Elastic strands: Line density 33.3dtex, breaking strength 1.05cN / dtex, breaking elongation 500%, 300% elastic recovery 91%;

[0211] Non-elastic strands: Line density 80dtex, breaking strength 3.3cN / dtex, elongation at break 32%;

[0212] (2) Warping and arranging;

[0213] Warping the elastic strands and pulling each of the elastic strands onto each needle eye of the needle bed 1, respectively, and adjusting the distance between two adjacent needle eyes until the needle eyes of the needle bed 1 are arranged at equal intervals;

[0214] Warping the inelastic strands and pulling each inelastic strand onto each needle eye of the needle bed 2, respectively, and adjusting the distance between two adjacent needle eyes until the needle eyes of the needle bed 2 are arranged at equal distances;

[0215] The needle eyes of two adjacent needle beds 1 each have a corresponding needle eye of needle bed 2;

[0216] (3) Crochet;

[0217] The needle holes of two adjacent needle beds 1 respectively knit two strands of elastic yarn to form a left elastic knitted chain and a right elastic knitted chain with entangled pores;

[0218] The left elastic braided chain and the right elastic braided chain move forward along the warp direction at a uniform speed;

[0219] The needle eyes of the corresponding needle bed 2 reciprocate at a uniform speed in the weft direction. When it moves to the left elastic chain, a single inelastic strand is inserted into the entanglement pores of the left elastic chain and a knot is formed by inserting a crochet hook into the knot. When it moves to the right elastic chain, a single inelastic strand is inserted into the entanglement pores of the right elastic chain and a knot is formed by inserting a crochet hook into the knot.

[0220] The final single-layer elastic material is composed of non-elastic strands and elastic braids with entangled pores distributed along the warp direction;

[0221] The elastic braided chain is a twisted wire consisting of three elastic strands, as shown in the figure. Figure 1 As shown in c, the entangled pores 1 are distributed along the warp direction; the linear density of the non-elastic strands = α × the linear density of the elastic strands × the number of crocheted strands of the elastic strands in the elastic braid, and the value of α is 0.8;

[0222] In the relaxed state, the elastic braids are distributed in equally spaced parallel lines. The average value of the spacing between all adjacent elastic braids is recorded as D*, and the standard deviation is recorded as p1. D* is 3.6 mm, and p1 is 0.1.

[0223] Two inelastic strands are arranged between any two adjacent elastic braided chains on the left and right;

[0224] Each non-elastic strand shuttles along the warp direction between the two adjacent elastic braided chains on the left and right to form a turning point, such as Figure 3 As shown, the non-elastic strand 2 at the inflection point penetrates into the entanglement pore 1 of the elastic braided chain 3 and forms an entanglement point 4 by knotting or the like;

[0225] The entire single-layer elastic material is composed of Figure 6 The structure shown in b is the basic unit, which is laid repeatedly to the right. Figure 6 The structure shown in b has four elastic strands in total, two elastic strands X1 have the same shape, two elastic strands X2 have the same shape, and the elastic strands X1 and X2 have different shapes; in a relaxed state, the spacing between the inflection points on the same inelastic strand X1 is equal, the average spacing between all two adjacent inflection points on the same inelastic strand X1 is recorded as L1*, the standard deviation is recorded as p2, L1* / D* is 1.17, and p2 is 0.11; in a relaxed state, the spacing between the inflection points on the same inelastic strand X2 is equal, the average spacing between all two adjacent inflection points on the same inelastic strand X2 is recorded as L2*, the standard deviation is recorded as p3, L2* / D* is 1.19, and p3 is 0.12;

[0226] The tensile elastic recovery rate of the single-layer elastic material is 96%, and the stiffness is 6.2mm. The wearing performance test results of the single-layer elastic material are comfortable to wear and leave no marks.

[0227] The above-described single-layer elastic material can be used to prepare elastic components of disposable absorbent articles.

Claims

1. A single-layer elastic material, characterized in that: The invention comprises an elastic braided chain having entangled pores distributed along the warp direction; Elastic braids are braided or twisted wires of elastic strands; All elastic braids are connected by multiple inelastic strands; Each non-elastic strand shuttles between the two elastic braided chains on the left and right sides along the warp direction to form an inflection point. At the inflection point, the non-elastic strand penetrates into the entanglement pores of the elastic braided chain to form an entanglement point. The elongation at break of the non-elastic strand is ≤45%; In the relaxed state, the average value of the spacing between all two adjacent elastic braids on the left and right is recorded as D*, and the standard deviation is recorded as p1, D*≥2mm, p1≤0.

2.

2. A single-layer elastic material according to claim 1, characterized in that: At least one inelastic strand X is arranged between any two adjacent elastic braided chains on the left and right sides; in a relaxed state, the average distance between all two adjacent inflection points on the same inelastic strand X is recorded as L*, the standard deviation is recorded as p2, L* / D* is greater than 1 and less than 1.4, and p2≤0.

2.

3. A single-layer elastic material according to claim 2, characterized in that: A non-elastic strand X is arranged between any two adjacent elastic braided chains on the left and right, or two or more non-elastic strands X with the same or different shapes are arranged.

4. A single-layer elastic material according to claim 3, characterized in that: The number and shape of the non-elastic strands X between any two adjacent elastic braided chains on the left and right are the same.

5. A single-layer elastic material according to claim 1, characterized in that: The elastic chain is composed of a single elastic strand, which is woven by itself to form the elastic chain; or, the elastic chain is composed of two or more elastic strands, which are formed by any form between the elastic strands; and the entanglement pores are formed at the weaving entanglement of the elastic chain.

6. A single-layer elastic material according to claim 5, characterized in that: The material, specification and number of crocheted strands of all elastic strands in the elastic chain are the same; the material and specification of all inelastic strands are the same; the linear density of the elastic strands is 16.5-155dtex; the linear density of the inelastic strands = α×linear density of the elastic strands×number of crocheted strands of the elastic strands in the elastic chain, and the value range of α is 1.1-2.

0.

7. A single-layer elastic material according to claim 1, characterized in that: The breaking strength of the elastic strand is ≥0.7cN / dtex, the elongation at break is ≥470%, and the 300% elastic recovery rate is ≥90%; the breaking strength of the non-elastic strand is ≥2.5cN / dtex, and the elongation at break is ≥20%.

8. A single-layer elastic material according to claim 1, characterized in that: D*≤10mm.

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