CN118022035B - Memory core and preparation method and application thereof - Google Patents

Abstract

The application discloses a memory core, a preparation method and application thereof, and belongs to the field of absorbent cores. The memory core is prepared by thermally bonding the following raw materials in parts by weight: 10-30 parts of wood pulp fiber; 20-100 parts of water-absorbent resin; 3-15 parts of composite fiber; the composite fiber comprises a core layer and a surface layer, wherein the core layer and the surface layer are both made of polymer materials, and the melting point of the polymer materials of the core layer is higher than that of the polymer materials of the surface layer. The application has the advantages of improving the elasticity of the absorbent core and improving the comfort when wearing the absorbent core.

Description

A memory core and its preparation method and application

Technical Field

The present application relates to the field of absorbent cores, and in particular to a memory core and a preparation method and application thereof.

Background Art

Absorbent cores are often used in sanitary products, such as diapers and sanitary napkins. They have the functions of absorbing and storing liquid, so they play an extremely important role in sanitary products.

The classification of absorbent cores includes wood pulp cores and composite cores. The wood pulp core is composed of wood pulp fibers and absorbent resins, and is characterized by rapid liquid absorption, but has the disadvantage of being prone to clumping. The composite core is made of multiple layers of non-woven fabrics and hot-melt adhesive pressed together with absorbent resins. The non-woven fabrics limit the movement of the absorbent resins, making the composite core smooth and less prone to clumping.

However, due to the non-woven fabric and hot-melt adhesive, the overall texture of the composite core is relatively hard and lacks elasticity, resulting in the core being unable to recover its shape in time after being squeezed, reducing the user's experience when wearing sanitary products.

Summary of the invention

In order to increase the elasticity of the absorbent core and improve the comfort when wearing the absorbent core, the present application provides a memory core and a preparation method and application thereof.

In the first aspect, the present application provides a memory core adopting the following technical solution:

A memory core is prepared by thermal bonding of the following raw materials in parts by weight:

10-30 parts of wood pulp fiber;

20 to 100 parts of water-absorbing resin;

3-15 parts of composite fiber;

The composite fiber comprises a core layer and a surface layer, wherein both the core layer and the surface layer are composed of a polymer material, and the melting point of the polymer material of the core layer is higher than the melting point of the polymer material of the surface layer.

By adopting the above technical solution, the surface layer of the composite fiber is partially melted and softened during the thermal bonding process, generating bonding force, so that the composite fiber and the wood pulp fiber are interwoven to form a network structure, and the high melting point of the core layer provides strength and stability for the network structure, and the interweaving of the composite fiber and the wood pulp fiber also surrounds and supports the water-absorbing resin dispersed in the network structure, thereby improving the dispersion stability of the water-absorbing resin, ensuring the liquid absorption capacity of the core body, and effectively reducing the possibility of agglomeration and lumping of the water-absorbing resin, thereby improving the flatness of the core body. In addition, due to the stable structure, non-woven materials such as non-woven fabrics are not required as the basis of the core body. The structure formed by the wood pulp fiber, the water-absorbing resin and the composite fiber has high elasticity, so that the core body can quickly recover its original shape after being squeezed, and a deformation recovery function similar to that of memory sponge is obtained, that is, a memory core body is obtained.

Optionally, the core layer is made of polypropylene material or polyester material, and the surface layer is made of polyethylene material.

By adopting the above technical scheme, polypropylene and polyester have higher strength and higher melting points than polyethylene, so they are suitable as core layer materials. Polyethylene has a lower melting point and is suitable for partial melting and softening during the thermal bonding process, thereby achieving connection and bonding between composite fibers and between composite fibers and wood pulp fibers and absorbent resins.

Optionally, the wood pulp fiber is a modified wood pulp fiber, which is obtained by pretreating the wood pulp fiber with an epoxy silane coupling agent and a vinyl silane coupling agent, copolymerizing and grafting acrylonitrile and isoprene, and then grafting a polyamine compound to obtain the modified wood pulp fiber.

By adopting the above technical scheme, the pretreatment of epoxy silane coupling agent and vinyl silane coupling agent allows the epoxy functional group and vinyl functional group to be connected to the surface of the wood pulp fiber, wherein the vinyl functional group can provide an access basis for the copolymerization grafting of acrylonitrile and isoprene, so that the copolymer of acrylonitrile and isoprene is grafted on the surface of the wood pulp fiber. Since the copolymer structure of acrylonitrile and isoprene has a similar part to the polyolefin structure of the composite fiber, the compatibility of the wood pulp fiber and the composite fiber is improved, and the dispersibility and bonding effect are better; the epoxy functional group can provide an access basis for the grafting of polyamine compounds, and the polyamine can form a functional group bond with the water-absorbent resin, thereby the wood pulp fiber, the water-absorbent resin and the composite fiber form a core with higher strength, and the guide channel in the core is more stable, and since the connection stability between the wood pulp fiber and the water-absorbent resin is improved, the liquid absorption capacity is also improved.

Optionally, the mass ratio of the wood pulp fiber, epoxy silane coupling agent, vinyl silane coupling agent, acrylonitrile, isoprene and polyamine compound is 10:(0.5-1):(0.5-1):(0.15-0.3):(0.2-0.4):(0.18-0.3).

By adopting the above technical scheme, the addition ratio of epoxy silane coupling agent, vinyl silane coupling agent, acrylonitrile, isoprene and polyamine compounds is controlled, and the surface grafting state of wood pulp fiber is adjusted, so as to better combine with composite fiber and water-absorbing resin.

Optionally, the polyamine compound is one or both of butanediamine and hexamethylenediamine.

By adopting the above technical solution, butanediamine and hexamethylenediamine have longer carbon chains, which makes the bonding structure between wood pulp fiber and water-absorbing resin more reasonable, promotes the flow of liquid in the core, and improves the liquid storage capacity.

Optionally, the water-absorbing resin is an acrylic water-absorbing resin.

By adopting the above technical solution, the acrylic acid in the water-absorbing resin forms a bond with the polyamine compound in the wood pulp fiber, thereby improving the connection stability between the wood pulp fiber and the water-absorbing resin.

In a second aspect, the present application provides a method for preparing a memory core using the following technical solution:

A method for preparing a memory core comprises the following steps:

The wood pulp fiber and the composite fiber are mixed, broken up, and air-laid. During the air-laid process, a water-absorbent resin is added to form a fiber web, which is then thermally bonded and reinforced, compacted, and cooled to obtain a memory core.

By adopting the above technical solution, the wood pulp fibers and composite fibers are evenly dispersed in the air-laid manner, so after adding the water-absorbent resin, the water-absorbent resin can be ensured to have good dispersion, thereby improving the flatness and elasticity of the core.

Optionally, the thermal bonding is performed by hot air penetration, and the hot air temperature is 120-140°C.

By adopting the above technical solution, the hot air penetration method causes the composite fibers to be heated evenly, melt and soften better, thereby generating bonding force and forming a stable fiber web.

Optionally, before mixing the wood pulp fibers and the composite fibers, the process further includes crushing and loosening the wood pulp fibers and loosening the composite fibers.

By adopting the above technical solution, the agglomeration of wood pulp fibers and composite fibers is reduced, and the wood pulp fibers and composite fibers are mixed evenly.

Optionally, the step of forming the fiber web is performed multiple times, and a subsequent step is performed on the fiber web bearing surface formed in the previous step.

By adopting the above technical solution, the fiber webs are stacked layer by layer, which is beneficial to improving the dispersion of the water-absorbing resin in the core.

Optionally, the method for preparing the modified wood pulp fiber comprises the following steps:

Dispersing wood pulp fibers in a first solvent, adding an epoxy silane coupling agent and a vinyl silane coupling agent, heating for reaction, and filtering after the reaction is completed to obtain first wood pulp fibers;

The first wood pulp fiber is dispersed in the second solvent, acrylonitrile and isoprene are added, the mixture is heated, an initiator is slowly added, and the reaction is continued after the addition is completed. After the reaction is completed, the mixture is filtered to obtain the second wood pulp fiber;

The second wood pulp fiber is dispersed in the third solvent, a polyamine compound is added, and the mixture is heated for reaction. After the reaction is completed, the mixture is filtered to obtain the modified wood pulp fiber.

In a third aspect, the present application provides an application of a memory core, including applications in diapers, sanitary napkins, breastfeeding towels, sweat-absorbing towels and kitchen paper.

In summary, this application has the following beneficial effects:

1. The present application utilizes the low melting point of the surface layer of the composite fiber. During the thermal bonding process, the surface layer partially melts and softens, generating bonding force, so that the composite fiber and the wood pulp fiber are interwoven to form a network structure. The interweaving of the composite fiber and the wood pulp fiber also surrounds and supports the water-absorbing resin dispersed in the network structure, thereby improving the dispersion stability of the water-absorbing resin, ensuring the liquid absorption capacity of the core body while effectively reducing the possibility of the water-absorbing resin agglomerating and lumping, thereby improving the flatness of the core body. In addition, due to the stable structure, there is no need for non-woven materials such as non-woven fabrics as the basis of the core body. The structure formed by the wood pulp fiber, the water-absorbing resin and the composite fiber has high elasticity, so that the core body can quickly recover its original shape after being squeezed, and obtain a deformation recovery function similar to that of memory sponge, that is, a memory core body is obtained.

2. The present application also uses modified wood pulp fibers to improve the compatibility of wood pulp fibers and composite fibers, as well as the bonding ability of wood pulp fibers and water-absorbent resins. As a result, wood pulp fibers, water-absorbent resins and composite fibers form a core with higher strength, and the flow guide channels in the core are more stable. In addition, since the connection stability between wood pulp fibers and water-absorbent resins is improved, the liquid absorption capacity is also improved.

DETAILED DESCRIPTION

The present application is described in further detail below.

Preparation Example 1

The method for preparing modified wood pulp fiber comprises the following steps:

Weigh 1kg of wood pulp fiber, 0.05kg of epoxy silane coupling agent, 0.05kg of vinyl silane coupling agent, 0.015kg of acrylonitrile, 0.02kg of isoprene, and 0.018kg of polyamine compound, wherein the epoxy silane coupling agent is KH-560, the vinyl silane coupling agent is KH-570, and the polyamine compound is butanediamine.

In addition, an initiator solution was prepared, which contained 2 g of benzoyl peroxide and 500 mL of toluene.

Dispersing wood pulp fibers in 7 L of 80 wt% ethanol solution, adding epoxy silane coupling agent and vinyl silane coupling agent, heating to 65° C. to react for 1.5 h, filtering after the reaction to obtain first wood pulp fibers;

The first wood pulp fiber is dispersed in 7 L of toluene, acrylonitrile and isoprene are added, and the mixture is heated to 95° C. The initiator solution is slowly added dropwise, and the reaction is continued for 2 hours after the addition is completed. After the reaction is completed, the mixture is filtered to obtain the second wood pulp fiber;

The second wood pulp fiber was dispersed in 5L of 50wt% ethanol solution, 50g of sodium carbonate was added, and the mixture was stirred evenly, and then the polyamine compound was added. The mixture was heated to 55°C and reacted for 3h. After the reaction was completed, the modified wood pulp fiber was filtered to obtain the modified wood pulp fiber.

Preparation Example 2

The method for preparing modified wood pulp fiber comprises the following steps:

The difference between this preparation example and preparation example 1 is that the amounts of the preparation raw materials are different.

Weigh 1kg of wood pulp fiber, 0.1kg of epoxy silane coupling agent, 0.1kg of vinyl silane coupling agent, 0.03kg of acrylonitrile, 0.04kg of isoprene, and 0.03kg of polyamine compound, wherein the epoxy silane coupling agent is KH-560, the vinyl silane coupling agent is KH-570, and the polyamine compound is hexamethylenediamine.

Preparation Example 3

The method for preparing modified wood pulp fiber comprises the following steps:

The difference between this preparation example and preparation example 2 is that the amount of the polyamine compound used is 0.015 kg, and ethylenediamine is selected as the polyamine compound.

Preparation Example 4

The method for preparing modified wood pulp fiber comprises the following steps:

Weigh 1 kg of wood pulp fiber, 0.057 kg of aminosilane coupling agent, 0.05 kg of vinylsilane coupling agent, 0.015 kg of acrylonitrile, and 0.02 kg of isoprene. The aminosilane coupling agent is KH-550, and the vinylsilane coupling agent is KH-570.

In addition, an initiator solution was prepared, which contained 2 g of benzoyl peroxide and 500 mL of toluene.

Dispersing wood pulp fibers in 7 L of 80 wt% ethanol solution, adding aminosilane coupling agent and vinylsilane coupling agent, heating to 65° C. for reaction for 1.5 h, filtering after the reaction to obtain first wood pulp fibers;

The first wood pulp fiber was dispersed in 7 L of toluene, acrylonitrile and isoprene were added, and the mixture was heated to 95° C. The initiator solution was slowly added dropwise. After the addition was completed, the reaction was continued for 2 h. After the reaction was completed, the mixture was filtered to obtain modified wood pulp fiber.

Preparation Example 5

The method for preparing modified wood pulp fiber comprises the following steps:

Weigh 1 kg of wood pulp fiber, 0.05 kg of epoxy silane coupling agent, and 0.018 kg of polyamine compound, wherein the epoxy silane coupling agent is KH-560, and the polyamine compound is hexamethylenediamine.

Dispersing wood pulp fibers in 7 L of 80 wt% ethanol solution, adding epoxy silane coupling agent, heating to 65° C. for reaction for 1.5 h, filtering after the reaction to obtain first wood pulp fibers;

The first wood pulp fiber was dispersed in 5L of 50wt% ethanol solution, 50g of sodium carbonate was added, and the mixture was stirred evenly, and then a polyamine compound was added. The mixture was heated to 55°C and reacted for 3h. After the reaction was completed, the mixture was filtered to obtain modified wood pulp fiber.

Preparation Example 6

The method for preparing modified wood pulp fiber comprises the following steps:

The difference between this preparation example and preparation example 2 is that, in the process of preparing the second wood pulp fiber, acrylonitrile is not added, but 0.058 kg of styrene is added instead.

Example 1

The method for preparing a memory core comprises the following steps:

The wood pulp fiber is crushed and opened, and the composite fiber is opened, wherein the wood pulp fiber is coniferous wood fiber with a length of 2.5 mm; the composite fiber is ES fiber, the core layer of the composite fiber is polypropylene, the surface layer is polyethylene, the composite fiber fineness is 2D, and the length is 8 mm.

The wood pulp fiber and the composite fiber are mixed and put into a forming box to be broken up and floated, and then they reach a net curtain under the action of airflow to obtain a coarse fiber net.

There are multiple forming boxes. After the coarse fiber web is formed in the previous forming box, the coarse fiber web enters the next forming box, and a resin feeding device is provided between adjacent forming boxes. The resin feeding device is used to spread water-absorbing resin. The water-absorbing resin is an acrylic polymer water-absorbing resin purchased from Chunhui Polymer Materials Company. The water-absorbing resin is spread on the coarse fiber web to form a fiber web, and then the next fiber web is formed on the supporting surface of the fiber web. In this embodiment, there are three forming boxes. The mass ratio of the wood pulp fiber, water-absorbing resin and composite fiber used is 10:20:3.

After forming, the fiber web enters the hot air box and is thermally bonded and reinforced by hot air penetration. The hot air temperature is 120°C. Then it is compacted by a compaction roller, cooled, and rolled up to obtain a memory core.

Example 2

The method for preparing a memory core comprises the following steps:

The difference between this embodiment and embodiment 1 is that the mass ratio of the wood pulp fiber, the water-absorbing resin and the composite fiber is 30:100:15.

Example 3

The method for preparing a memory core comprises the following steps:

The difference between this embodiment and embodiment 1 is that the mass ratio of the wood pulp fiber, the water-absorbing resin and the composite fiber is 20:50:7.

Embodiment 4 to Embodiment 9

The difference between Example 4 to Example 9 and Example 1 is that the wood pulp fiber is modified wood pulp fiber, and the source of the modified wood pulp fiber is shown in Table 1.

Table 1

Modified Wood Pulp Fiber Sources Example 4 Preparation Example 1 Example 5 Preparation Example 2 Example 6 Preparation Example 3 Example 7 Preparation Example 4 Example 8 Preparation Example 5 Example 9 Preparation Example 6

Comparative Example 1

The method for preparing a memory core comprises the following steps:

The difference between this comparative example and Example 1 is that no composite fiber is added.

Comparative Example 2

The composite core body on the market adopts the structure of dust-free paper-polymer resin-non-woven fabric-polymer resin-dust-free paper, and hot melt adhesive is sprayed between the dust-free paper and the polymer resin.

Performance Testing

With reference to GB/T 24442.1-2009 “Determination of compression properties of textiles”, the compression elasticity of the core was tested, with a light pressure of 0.02 kPa for 10 s, a heavy pressure of 1 kPa for 60 s, and a recovery time of 60 s. The test results are shown in Table 2.

Take 100mL of normal saline (mass concentration 0.9%) and heat it to 40°C, then add the normal saline to the core, place the absorbent core sample in a 40±1°C, 65±1%RH test box for 10 minutes, and then take out the absorbent core sample for testing; the tester holds the two ends of the absorbent core sample with both hands, first swings one end of the absorbent core sample with one hand, repeats 10 times, then stretches the two ends of the absorbent core sample back and forth with both hands, repeats 10 times, then rubs the core with both hands, repeats 10 times, and finally observes whether the absorbent core has any lumping phenomenon, and records the phenomenon results in Table 2.

Referring to QB/T 5650-2021 "Composite absorbent core for disposable paper sanitary products", the absorption rate, absorption rate and rewet amount of the core were tested. The test solutions were normal saline, simulated menstrual blood and milk, and the test results are recorded in Table 3.

Table 2

Compression elasticity (%) Lumping phenomenon Example 1 88 No lumps Example 2 90 No lumps Example 3 87 No lumps Example 4 86 No lumps Example 5 85 No lumps Example 6 85 No lumps Example 7 86 No lumps Example 8 85 No lumps Example 9 85 No lumps Comparative Example 1 83 Lump Comparative Example 2 67 No lumps

Table 3

As can be seen from Table 2, compared with the traditional non-woven fabric-water-absorbent resin composite core and the wood pulp core of wood pulp fiber-water-absorbent resin, the memory core composed of wood pulp fiber-water-absorbent resin-composite fiber has the advantages of no lumping and high compression elasticity, that is, the structure is stable and has high elasticity and comfort.

Combined with the analysis in Table 3, for the liquid absorption and storage capacity of the core base, the memory core composed of wood pulp fiber-absorbent resin-composite fiber has a higher absorption rate, faster absorption speed and smaller re-seepage amount for physiological saline, simulated menstrual blood and milk. Therefore, the memory core shows good liquid absorption and storage capacity in various usage scenarios and can be applied to diapers, sanitary napkins, breastfeeding wipes, sweat-absorbing wipes and kitchen paper.

By comparing Example 1 with Examples 4-5, it can be seen that the modified wood pulp fiber can achieve better liquid absorption and storage effects, and when the difficult-to-absorb simulated menstrual blood and milk are used as test solutions, obvious liquid absorption and storage effects are also obtained.

By comparing Example 5 with Example 6, it can be seen that compared with using ethylenediamine as a polyamine compound to modify wood pulp fibers, long-chain polyamine compounds such as hexamethylenediamine have better modification effects; by comparing Example 5 with Example 7, it can be seen that compared with directly accessing wood pulp fibers through aminosilane coupling agents, first accessing wood pulp fibers with epoxy silane coupling agents and then using hexamethylenediamine to react with epoxy groups to achieve access, the modification effect of wood pulp fibers and the final liquid absorption and storage effects of the core are better improved.

By comparing Example 5 with Examples 8-9, it can be seen that the modification of wood pulp fibers by accession of acrylonitrile-isoprene copolymer helps to improve the compatibility of wood pulp fibers with composite fibers, thereby making the fiber web constituting the core more stable and the flow guide channels in the core more stable, thereby improving the liquid absorption and storage capabilities of the core.

This specific implementation manner is merely an explanation of the present application and is not a limitation of the present application. After reading this specification, those skilled in the art may make non-creative modifications to the specific implementation manner as needed, but such modifications are protected by the patent law as long as they are within the scope of the claims of the present application.

Claims (9)

1. A memory core, characterized in that it is prepared by thermal bonding of the following raw materials in parts by weight: Wood pulp fiber 10~30 parts; Water-absorbing resin 20~100 parts; Composite fiber 3~15 parts; The composite fiber comprises a core layer and a surface layer, wherein the core layer and the surface layer are both composed of a polymer material, and the melting point of the polymer material of the core layer is higher than the melting point of the polymer material of the surface layer; The wood pulp fiber is a modified wood pulp fiber. The modified wood pulp fiber is obtained by pretreating the wood pulp fiber with an epoxy silane coupling agent and a vinyl silane coupling agent, copolymerizing and grafting acrylonitrile and isoprene, and then grafting a polyamine compound. 2. A memory core according to claim 1, characterized in that the core layer is made of polypropylene material or polyester material, and the surface layer is made of polyethylene material. 3. A memory core according to claim 1, characterized in that the mass ratio of the wood pulp fiber, epoxy silane coupling agent, vinyl silane coupling agent, acrylonitrile, isoprene and polyamine compound is 10:(0.5~1):(0.5~1):(0.15~0.3):(0.2~0.4):(0.18~0.3). 4. A memory core according to claim 1, characterized in that the polyamine compound is one or both of diaminobutane and diaminohexamethylene. 5. A memory core according to claim 1, characterized in that the water-absorbing resin is an acrylic water-absorbing resin. 6. A method for preparing a memory core according to any one of claims 1 to 5, characterized in that it comprises the following steps: The wood pulp fiber and the composite fiber are mixed, broken up, and air-laid. During the air-laid process, a water-absorbent resin is added to form a fiber web, which is then thermally bonded and reinforced, compacted, and cooled to obtain a memory core. 7. A method for preparing a memory core according to claim 6, characterized in that the thermal bonding is performed by hot air penetration. 8. The method for preparing a memory core according to claim 6, characterized in that: the method for preparing the modified wood pulp fiber comprises the following steps: Dispersing wood pulp fibers in a first solvent, adding an epoxy silane coupling agent and a vinyl silane coupling agent, heating for reaction, and filtering after the reaction is completed to obtain first wood pulp fibers; The first wood pulp fiber is dispersed in the second solvent, acrylonitrile and isoprene are added, the mixture is heated, an initiator is slowly added, and the reaction is continued after the addition is completed. After the reaction is completed, the mixture is filtered to obtain the second wood pulp fiber; The second wood pulp fiber is dispersed in the third solvent, a polyamine compound is added, and the mixture is heated for reaction. After the reaction is completed, the mixture is filtered to obtain the modified wood pulp fiber. 9. An application of the memory core according to any one of claims 1 to 5, characterized in that it is applied to diapers, sanitary napkins, breastfeeding towels, sweat-absorbing towels and kitchen paper.