CN116219575A - A kind of hot-melt composite fiber and its preparation method and fiber web - Google Patents

Abstract

This application relates to the field of air purification technology, in particular to a heat-meltable composite fiber, including a core layer and a skin layer, the skin layer is wrapped on the outer surface of the core layer, the material composition of the core layer includes polypropylene I, and the material composition of the skin layer includes polypropylene II and hydrogenated styrene-butadiene block copolymer, the melting point of polypropylene II in the skin layer is 30°C-40°C lower than the melting point of polypropylene I in the core layer. The blend melt made of SEBS-modified polypropylene for the skin layer of the heat-fusible composite fiber of the present application has better fluidity and good transparency than the single-component polypropylene melt. The application also defines that the melting point of the polypropylene II in the skin layer is 30°C-40°C lower than the melting point of the polypropylene I in the core layer, which can ensure that the physical properties of the core layer are not changed when the skin layer components are melted during the heating and pressing process. Change, so that the fiber has a certain strength and elasticity, and at the same time, it can realize the bonding between fibers, which is beneficial to the processing and forming of the fiber web.

Description

A kind of hot-melt composite fiber and its preparation method and fiber web

technical field

The present application relates to the technical field of air purification, and in particular to a heat-fusible composite fiber, a preparation method thereof and a fiber web.

Background technique

Heat-fusible composite fibers are usually made of low-melting point resin as the sheath component and high-melting point resin as the core component. It can be formed into a fiber network by carding and other processing methods, and then the skin component is melted by heating and pressure. It is used to bond the points where fibers intersect. Fusible composite fibers are widely used because they do not require the use of adhesives and are produced at high speeds.

The heat-fusible composite fiber composed of low melting point polypropylene (co-polypropylene, co-PP) sheath component and polypropylene (polypropylene, PP) core component contains poly The propylene component has a strong affinity between the sheath component and the core component in the composite fiber, and the sheath and core components are not easy to delaminate, which has attracted people's attention. However, in the existing heat-melt composite fibers of co-PP/PP, when hot-air composite is used for thermal bonding, the temperature of hot-air bonding is generally not higher than the melting temperature of the polypropylene core layer in order to prevent fiber deformation. , but when a relatively low temperature is used for hot-melt lamination in the production of monofilaments, due to the high production rate, the polypropylene in the cortex is too late to melt and bond, and the problem of low bond strength of the fiber web is prone to occur.

Contents of the invention

The application provides a hot-melt composite fiber and its preparation method and fiber web, which are used to solve the problems of poor bonding performance and unsatisfactory transparency of the existing hot-melt composite fiber.

According to the first aspect of the application, the application provides a heat-fusible composite fiber, comprising:

A core layer; the material composition of the core layer includes polypropylene I;

The skin layer is wrapped on the outer surface of the core layer; the material composition of the skin layer includes polypropylene II and hydrogenated styrene-butadiene block copolymer;

The melting point of the polypropylene II in the skin layer is 30°C-40°C lower than the melting point of the polypropylene I in the core layer.

In a possible design, the mass ratio of the skin layer to the core layer is 1:2-1:1.

In a possible design, in the skin layer, the weight ratio of the polypropylene II to the hydrogenated styrene-butadiene block copolymer is 4:1-9:1.

In a possible design, the melt index of the polypropylene I is 3g/10min-15g/10min; preferably, the melt index of the polypropylene I is 3g/10min-8g/10min;

In a possible design, the melting point of the polypropylene I is 160°C-170°C.

In a possible design, the polypropylene I is homopolypropylene.

In a possible design, in the skin layer, the melt index of the polypropylene II is 3g/10min-5g/10min, and the melt index of the hydrogenated styrene-butadiene block copolymer is 10g/10min -30g/10min.

In a possible design, the diameter of the heat-fusible composite fiber is 0.05mm-0.06mm.

In a possible design, the material composition of the skin layer and the material composition of the core layer each independently include a lubricant, the lubricant is selected from fatty acid amide compounds, fatty acid compounds, paraffin and hydrocarbon resins, silicone One or more of alkanes, polysiloxane polymers, fluorine compounds, copolymers of tetrafluoroethylene and propylene, copolymers of vinylidene fluoride and hexafluoropropylene;

In one possible design, the lubricant is selected from fatty acid amide compounds.

In a possible design, in the core layer, the content of the fatty acid amide compound is 0.05%-1% of the weight of the polypropylene I.

In a possible design, in the skin layer, the content of the fatty acid amide compound is 0.05%-1% of the weight of the polypropylene II.

According to the second aspect of the present application, the present application also provides the above-mentioned preparation method of the heat-melt composite fiber, comprising the following steps:

After the skin layer material composition containing polypropylene II and hydrogenated styrene-butadiene block copolymer is melted and extruded by the first screw, it enters the first metering pump for precise metering, and then enters the skin-core spinning dual-channel composite die head the cortical channel;

After the core layer material composition comprising polypropylene I is melted and extruded by the second screw, it enters the second metering pump for accurate metering, and then enters the core layer channel of the skin-core spinning dual-channel composite die;

After the skin layer material components and the core layer material components pass through their respective channels, they are compounded into fibers with a skin-core structure on a spinneret with a plurality of spinneret holes; the fibers with a skin-core structure are then sprayed Filament extruded to obtain a plurality of as-spun fibers with a sheath-core structure;

The primary spun fibers enter the cooling water tank for cooling, and each fiber in the cooling water tank is separated after entering its own silk path; the separated spun fibers are stretched in a first-stage water bath by drafting rollers, and Hot air stretching is carried out in the box; after stretching, each spun fiber is individually wound into a silk cake to obtain the heat-fusible composite fiber;

The multiple of the primary water bath stretching is 4 to 8 times, and the temperature of the water bath is 80°C to 95°C; the multiple of the hot air stretching is 1.1 to 1.5 times, and the temperature of the hot air is 85°C to 95°C.

According to the third aspect of the present application, the present application also provides a fiber web, which is prepared from the above-mentioned heat-fusible composite fiber.

The beneficial effect of this application:

A heat-meltable composite fiber of the present application includes a core layer and a skin layer, the skin layer is wrapped on the outer surface of the core layer, the material composition of the core layer includes polypropylene I, and the material composition of the skin layer includes polypropylene II and hydrogenated styrene-butadiene Block copolymer, considering the hot air bonding process, in order to keep the core layer PP from deformation during hot air bonding, the temperature of hot air bonding should not be higher than the melting point of the core layer PP, considering the need for skin layer fusion bonding The melting point of polypropylene II in the skin layer is 30°C-40°C lower than that of polypropylene I in the core layer, so that the skin layer can melt during bonding. The heat-fusible composite fiber of the present application includes a core layer and a skin layer wrapped around the core layer. Both the core layer and the skin layer contain polypropylene components, so that there is a strong affinity between the core layer and the skin layer, and delamination is not easy to occur. The material composition of the cortex includes PP and SEBS. SEBS is a linear tri-block copolymer of the middle elastic block, which has good stability and aging resistance, good temperature resistance, compression deformation resistance and excellent mechanical properties; SEBS and PP have good compatibility. After adding polypropylene, the crystallinity of polypropylene is destroyed, making the crystallization of PP finer; SEBS reduces the melting temperature of polypropylene, so that polypropylene can be melted at a lower temperature , At the same time, the prepared blend melt has better fluidity and stretchability than the single-component polypropylene melt, and the good fluidity and stretchability can also ensure the spinnability of the heat-melt composite fiber. The heat-meltable composite fiber of the present application also defines that the melting point of polypropylene II in the skin layer is 30°C-40°C lower than the melting point of polypropylene I in the core layer, and can be produced at a temperature lower than and Close to the melting temperature of the core layer, ensure that the physical properties of the core layer remain unchanged when the skin layer components are melted during the heating and pressurization process, so that the fibers have a certain strength and elasticity, and the skin layer melts at the same time to achieve the bonding between fibers. It is beneficial to the processing and forming of the fiber web.

It is to be understood that both the foregoing general description and the following detailed description are exemplary only and are not restrictive of the application.

Description of drawings

Fig. 1 is a schematic structural view of a heat-fusible composite fiber provided in an embodiment of the present application.

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the application and together with the description serve to explain the principles of the application.

Detailed ways

The following descriptions are preferred implementations of the embodiments of the present application. It should be pointed out that those skilled in the art can make several improvements and modifications without departing from the principles of the embodiments of the present application. These improvements and retouching are also regarded as the scope of protection of the embodiments of the present application.

In a first aspect, the present application provides a heat-fusible composite fiber, comprising:

The core layer; the material composition of the core layer includes polypropylene I;

The cortex is wrapped on the outer surface of the core layer; the material composition of the cortex includes polypropylene II and hydrogenated styrene-butadiene block copolymer;

The melting point of polypropylene II in the skin layer is 30°C-40°C lower than the melting point of polypropylene I in the core layer.

In the above scheme, the heat-fusible composite fiber of the present application includes a core layer and a skin layer wrapped outside the core layer, and both the core layer and the skin layer contain polypropylene components, so that there is a strong affinity between the core layer and the skin layer, and it is not easy to appear. layer phenomenon. The material composition of the skin layer includes PP and hydrogenated styrene-butadiene block copolymer (Styrene ethylene/butenetyrene, SEBS), SEBS is a linear tri-block copolymer of the middle elastic block, which has good stability and aging resistance , better temperature resistance, compression deformation resistance and excellent mechanical properties, the blend melt made of SEBS modified low melting point polypropylene has a lower melting point than the single component low melting point polypropylene melt, Better fluidity, at the same time, the blend also has good toughness, impact elasticity and tensile properties. Good toughness and impact elasticity make the skin layer of the heat-fusible composite fiber not easy to break when subjected to external impact, and better protect the core layer. Good fluidity and stretchability can also ensure the spinnability of heat-melt composite fibers. The heat-meltable composite fiber of the present application also defines that the melting point of polypropylene II in the skin layer is 30°C-40°C lower than the melting point of polypropylene I in the core layer, and the skin layer has good toughness and elasticity. In the production of fiber webs, It can ensure that the physical properties of the core layer remain unchanged when the skin layer components are melted during the heating and pressing process, so that the fibers have a certain strength and elasticity, and at the same time can realize the bonding between fibers, which is beneficial to the processing and forming of the fiber web.

The program is described in detail below:

In some embodiments, the mass ratio of the skin layer to the core layer is 1:2-1:1; preferably, the mass ratio of the skin layer to the core layer is 2:3-1:1.

It can be understood that by limiting the mass ratio of the skin layer to the core layer, it can be ensured that the heat-fusible composite fiber has low-temperature thermal adhesion and ideal strength. If the mass ratio of the skin layer to the core layer is lower than 1:2, the heat-fusible composite fiber produced will have insufficient thermal bonding force, and the purpose of low-temperature bonding cannot be achieved. If the mass ratio of the skin layer to the core layer is higher than 1:1, the strength of the hot-melt composite fiber produced is insufficient, and the strength of the monofilament fiber that does not meet the specified requirements is greater than 3.5cn/dtex. Easily damaged under action.

In some embodiments, in the skin layer, the weight ratio of the polypropylene II to the hydrogenated styrene-butadiene block copolymer is 4:1-9:1.

Alternatively, in the cortex, the weight ratio of polypropylene II and hydrogenated styrene-butadiene block copolymer can be 4:1, 4.5:1, 5:1, 5.5:1, 6:1, 6.5:1 , 7:1, 7.5:1, 8:1, 8.5:1 or 9:1, etc. Of course, other values within the above range may also be used, which are not limited here.

It can be understood that by limiting the weight ratio of polypropylene II and hydrogenated styrene-butadiene block copolymer in the skin layer, the skin layer can not only meet the spinning requirements, maintain the transparency of co-PP, but also have Good hot melt adhesive action.

In some embodiments, in the core layer, the melt index of the polypropylene I is 3 g/10 min-15 g/10 min. It should be noted that the melt index is a numerical value indicating the fluidity of plastic materials during processing. It is formulated by the American Society for Measurement Standards (ASTM) according to the method used by DuPont to identify the characteristics of plastics. The test method is: first let the plastic pellets melt into a plastic fluid, and then within a certain period of time, a certain temperature And pressure (various material standards are different), after passing through a circular tube with a diameter of 2.1mm, measure its gram (g) number. The larger the value, the better the processing fluidity of the plastic material, and vice versa.

Optionally, in the core layer, the melt index of polypropylene I can be 3g/10min, 4g/10min, 5g/10min, 6g/10min, 7g/10min, 8g/10min, 9g/10min, 10g/10min, 11g/10min, 11g/10min, 10min, 12g/10min, 13g/10min, 14g/10min or 15g/10min, etc., of course, can also be other values within the above range, which are not limited here. Preferably, in the core layer, the melt index of polypropylene I is 3g/10min-8g/10min.

It can be understood that through the special limitation of the melt index of polypropylene I, the core layer can have proper processing fluidity, which is more conducive to the processing and molding of heat-melt composite fibers.

In some embodiments, polypropylene I has a melting point of 160°C to 170°C.

Optionally, the melting point of polypropylene I can be 160°C, 161°C, 162°C, 163°C, 164°C, 165°C, 166°C, 167°C, 168°C, 169°C or 170°C, etc. Other values within the range are not limited here.

It can be understood that through the special limitation of the melting point of polypropylene I, the core layer can not be easily melted, so as to ensure the shape of the heat-fusible composite fiber.

In some embodiments, polypropylene I is a homopolypropylene. Polypropylene II is a copolymerized polypropylene.

It can be understood that homopolypropylene is polymerized from a single polypropylene monomer, does not contain ethylene monomer in the molecular chain, has high molecular chain regularity, and has good high temperature resistance. As a material component of the core layer, it can The core layer has high temperature resistance. The blend melt made by SEBS modified low-melting-point copolymerized polypropylene has lower melting temperature, better fluidity and can maintain good transparency than single-component low-melting-point copolymerized polypropylene melt. At the same time, the blend also has good toughness, impact elasticity and tensile properties. Good toughness and impact elasticity make the skin layer of the heat-fusible composite fiber not easy to break when subjected to external impact, and better protect the core layer. Good fluidity and stretchability can also ensure the spinnability of heat-melt composite fibers.

In some embodiments, in the skin layer, the melt index of the polypropylene II is 3g/10min-5g/10min, and the melt index of the hydrogenated styrene-butadiene block copolymer is 10g/10min-30g/10min.

Optionally, in the skin layer, the melt index of polypropylene II can be 3g/10min, 3.5g/10min, 4g/10min, 4.5g/10min, 5g/10min, etc., and of course it can also be other values within the above range. This is not limited. The melt index of the hydrogenated styrene-butadiene block copolymer can be 10g/10min, 12g/10min, 15g/10min, 18g/10min, 20g/10min, 23g/10min, 25g/10min, 28g/10min or 30g/10min 10min, etc., of course, may also be other values within the above range, which are not limited here.

It can be understood that through the special limitation of the melt index of polypropylene II and hydrogenated styrene-butadiene block copolymer, the skin layer can have suitable processing fluidity, which is more conducive to the processing and molding of heat-melt composite fibers.

In some embodiments, the heat-fusible composite fiber has a diameter of 0.05mm-0.06mm.

Optionally, the diameter of the hot-melt composite fiber can be 0.05mm, 0.051mm, 0.052mm, 0.053mm, 0.054mm, 0.055mm, 0.056mm, 0.057mm, 0.058mm, 0.059mm or 0.06mm, etc., of course, it can also be are other values within the above range, and are not limited here.

In some embodiments, the material composition of the skin layer and the material composition of the core layer also independently include a lubricant, and the lubricant is selected from fatty acid amide compounds, fatty acid compounds, paraffin and hydrocarbon resins, siloxane compounds, polysiloxane One or more of polymers, fluorine compounds, copolymers of tetrafluoroethylene and propylene, copolymers of vinylidene fluoride and hexafluoropropylene.

In some embodiments, the lubricant is selected from fatty acid amide compounds; in the core layer, the content of fatty acid amide compounds is 0.05%-1% of the weight of polypropylene I; in the cortex, the content of fatty acid amide compounds is 0.05% of the weight of polypropylene II %-1%;

Preferably, in the core layer, the content of the fatty acid amide compound is 0.1%-0.5% of the weight of the polypropylene I; in the skin layer, the content of the fatty acid amide compound is 0.1%-0.5% of the weight of the polypropylene II.

It can be understood that adding a lubricant to the skin layer and the core layer can increase the fluidity of the skin layer and the core layer in the molten state, which is beneficial to the processing and molding of the heat-melt composite fiber and the fiber web prepared from the heat-melt composite fiber. Processing and forming.

In some embodiments, the material composition of the skin layer and the material composition of the core layer also independently include a color paste, and the color paste can be prepared from pigments of different colors, so that the skin layer and the core layer present different colors and achieve different aesthetics. Effect.

In a second aspect, the present application also provides a method for preparing the above-mentioned heat-fusible composite fiber, comprising the following steps:

After the skin layer material composition containing polypropylene II and hydrogenated styrene-butadiene block copolymer is melted and extruded by the first screw, it enters the first metering pump for precise metering, and then enters the skin-core spinning dual-channel composite die head the cortical channel;

After the core layer material composition comprising polypropylene I is melted and extruded by the second screw, it enters the second metering pump for accurate metering, and then enters the core layer channel of the skin-core spinning dual-channel composite die;

After passing through their respective channels, the skin material components and the core material components are compounded into fibers with a skin-core structure on a spinneret with multiple spinneret holes; the fibers with a skin-core structure are then extruded through the spinneret Obtain a plurality of as-spun fibers with a sheath-core structure;

The primary spun fibers enter the cooling water tank for cooling, and each fiber in the cooling water tank is separated after entering its own silk path; the separated spun fibers are stretched in a first-stage water bath by drafting rollers, and are drawn in a hot box Hot air stretching; after stretching, each spun fiber is individually wound into a silk cake to obtain a hot-melt composite fiber;

The multiple of the primary water bath stretching is 4 to 8 times, and the temperature of the water bath is 80°C to 95°C; the multiple of hot air stretching is 1.1 to 1.5 times, and the temperature of the hot air is 85°C to 95°C.

Optionally, the multiple of the primary water bath stretching can be 4 times, 4.5 times, 5 times, 5.5 times, 6 times, 6.5 times, 7 times, 7.5 times or 8 times, etc., of course, it can also be other in the above range value, which is not limited here. The water temperature of the water bath can be 80°C, 82°C, 84°C, 86°C, 88°C, 90°C, 92°C, 94°C or 95°C, etc. Of course, it can also be other values within the above range, which is not limited here. The multiple of hot air stretching can be 1.1 times, 1.2 times, 1.3 times, 1.4 times or 1.5 times, etc. Of course, it can also be other values within the above range, which is not limited here. The hot air temperature can be 85°C, 86°C, 87°C, 88°C, 89°C, 90°C, 91°C, 92°C, 93°C, 94°C or 95°C, etc. Of course, it can also be other values within the above range. This is not limited.

In the above scheme, the preparation method of the present application adopts a two-component composite spinning production line with a skin-core component to make a composite fiber with a skin-core structure, and through the cooling wind speed, cooling temperature, cooling humidity, spinning Conditions such as temperature and spinning speed are improved and controlled, so that the prepared heat-melt composite fiber has good spinnability.

In a third aspect, the present application also provides a fiber web, which is prepared from the above-mentioned heat-fusible composite fiber.

The embodiments of the present application will be further described below in several embodiments. Wherein, the embodiments of the present application are not limited to the following specific embodiments. Within the scope of protection, appropriate changes can be implemented.

Example 1

This embodiment provides a heat-fusible composite fiber with a diameter of 0.05mm. As shown in Figure 1, the heat-fusible composite fiber consists of a skin layer 2 and a core layer 1 wrapped in the skin layer 2 , the weight ratio of skin layer 2 and core layer 1 is 1:1. The skin layer 2 is made of co-PP and SEBS mixed raw materials with a weight ratio of 9:1, and the core layer 1 is made of PP raw materials. The interface of the heat-meltable composite fiber is circular, and the whole is fibrous.

Among them, the melting index of co-PP is 3-5g/10min, the melting point is 135°C, the melting index of SEBS is 10-30g/10min, and the density is 0.91g/ ^cm3 ; the melting index of PP is 3-5g/10min, The melting point is 168°C. The melting point of co-PP in the skin layer is 33°C lower than that of PP in the core layer.

The preparation method of the heat-fusible composite fiber of this embodiment comprises the following steps:

S1. After mixing the co-PP and SEBS components of the cortex material in a ratio of 9:1, after passing through the first screw melt extrusion, enter the first metering pump for precise metering, and then enter the skin-core spinning dual-channel composite die head The cortical channel in the cortical channel;

S2. After the core layer material component PP is melted and extruded by the second screw, it enters the second metering pump for accurate metering, and then enters the core layer channel of the skin-core spinning dual-channel composite die head;

S3. After passing through their respective passages, the skin layer material components and the core layer material components enter the composite spinning assembly for spinning, and are composited into fibers with a skin-core structure on a spinneret with multiple spinneret holes; The fibers with the core structure are then extruded through the spinneret to obtain multiple primary spun fibers with a skin-core structure;

The primary spun fibers enter the cooling water tank for cooling, and each fiber in the cooling water tank is separated after entering its own silk path; the separated spun fibers are stretched in a first-stage water bath by drafting rollers, and are drawn in a hot box Hot air stretching is carried out; after stretching, each spun fiber is individually wound into a silk cake to obtain a heat-fusible composite fiber.

During the spinning process, the spinning temperature of the skin layer is 245°C, and the spinning temperature of the core layer is 245°C; the temperature of the cold water tank during the cooling process is 30°C; During the hot box drawing process, the oven temperature is 90°C, and the oven draw ratio is 0.95 times.

The fineness of the hot-melt composite fiber prepared in this embodiment is 120 dtex, the breaking strength is ≥3.9 CN/dtex, and the breaking elongation is between 30% and 45%.

Example 2

The heat-fusible composite fiber described in this embodiment has a diameter of 0.05 mm. Wherein, the mass ratio of the cortex to the core layer is 1:2, and the cortex is prepared from a mixed raw material of co-PP and SEBS with a weight ratio of 9:1.

The preparation method of the heat-fusible composite fiber of this embodiment is the same as that of Embodiment 1.

The fineness of the hot-melt composite fiber prepared in this example is 125 dtex, the breaking strength is ≥4.9 CN/dtex, and the breaking elongation is between 20% and 35%.

Example 3

The heat-fusible composite fiber described in this embodiment has a diameter of 0.05 mm. Wherein, the mass ratio of the cortex to the core layer is 2:3, and the cortex is prepared from a mixed raw material of co-PP and SEBS with a weight ratio of 4:1.

The preparation method of the heat-fusible composite fiber of this embodiment is the same as that of Embodiment 1.

The fineness of the hot-melt composite fiber prepared in this embodiment is 113 dtex, the breaking strength is ≥4.3 CN/dtex, and the breaking elongation is between 30% and 40%.

Example 4

The heat-fusible composite fiber described in this embodiment has a diameter of 0.05 mm. Wherein, the mass ratio of the cortex to the core layer is 1:2, and the cortex is prepared from a mixed raw material of co-PP and SEBS with a weight ratio of 4:1.

The fineness of the hot-melt composite fiber prepared in this embodiment is 115 dtex, the breaking strength is ≥5.0 CN/dtex, and the breaking elongation is between 25% and 35%.

Example 5

Compared with Example 1, the difference is that the melting point of co-PP is 130°C, the melting point of PP is 160°C, and the melting point of co-PP in the skin layer is 30°C lower than that of PP in the core layer.

The heat-fusible composite fiber described in this embodiment has a diameter of 0.05mm. Among them, the mass ratio of the cortex to the core layer is 1:1, and the cortex is prepared from a mixed raw material of co-PP and SEBS with a weight ratio of 4:1.

The fineness of the hot-melt composite fiber prepared in this embodiment is 115 dtex, the breaking strength is ≥5.0 CN/dtex, and the breaking elongation is between 25% and 35%.

Example 6

Compared with Example 1, the difference is that the melting point of co-PP is 128°C, the melting point of PP is 168°C, and the melting point of co-PP in the skin layer is 40°C lower than that of PP in the core layer.

The heat-fusible composite fiber described in this embodiment has a diameter of 0.05 mm. Among them, the mass ratio of the cortex to the core layer is 1:1, and the cortex is prepared from a mixed raw material of co-PP and SEBS with a weight ratio of 4:1.

The fineness of the hot-melt composite fiber prepared in this embodiment is 115 dtex, the breaking strength is ≥5.0 CN/dtex, and the breaking elongation is between 25% and 35%.

In order to further illustrate the superior performance of the heat-fusible composite fiber of the present invention, the inventors have also conducted a large number of comparative experiments. Due to space limitations, only some specific examples of comparative experiments are listed below.

Comparative example 1

Compared with Example 1, the difference is that the skin layer in the heat-fusible composite fiber is only made of co-PP.

Comparative example 2

Compared with Example 1, the difference is that the weight ratio of the skin layer and the core layer is 3:2.

Comparative example 3

Compared with Example 3, the difference lies in that the weight ratio of the skin layer and the core layer in the heat-fusible composite fiber is 1:3.

Comparative example 4

Compared with Example 3, the difference is that the skin layer is prepared from a mixed raw material of co-PP and SEBS with a weight ratio of 7:3.

Comparative example 5

Compared with Example 1, the difference is that the melting point of co-PP is 140, the melting point of PP is 165, and the melting point of co-PP in the skin layer is 25°C lower than that of PP in the core layer.

Take 10 samples from each of Examples 1-6 and Comparative Examples 1-5, and conduct mechanical property tests with reference to GBT_9997-1988, and take the average value. The results are shown in Table 1:

Weave the hot-melt composite fiber obtained above into a filter screen, and pass the obtained filter screen through a hot air oven at 95°C for hot air bonding for 25 seconds, and manually apply external force to the bonded screen to stretch the screen, and observe the screen Adhesive parts, whether there is displacement to evaluate the bonding strength and bonding effect, when the wire mesh is stretched externally, no displacement is judged as good adhesion, the existence of displacement means that the part is not bonded, and a small amount of displacement means bonding The effect is poor, and the evaluation results obtained are shown in Table 1:

Table 1 Comparison table of heat-meltable composite fiber properties of Examples 1-6 and Comparative Examples 1-5

It can be seen from the data in Table 1 that the heat-fusible composite fiber of the present application is significantly better than the co-PP sheath-core composite fiber in terms of dimensional stability and strength (Comparative Examples 1-5).

The blend melt made by SEBS modified low-melting point co-PP has better fluidity, better cohesiveness, and can maintain good transparency than single-component co-PP.

The above descriptions are only preferred embodiments of the present application, and are not intended to limit the present application. For those skilled in the art, there may be various modifications and changes in the present application. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of this application shall be included within the protection scope of this application.

Claims (10)

1. A hot-melt-processable composite fiber, comprising:

a core layer; the material composition of the core layer comprises polypropylene I;

a skin layer wrapping the outer surface of the core layer; the material components of the skin layer comprise polypropylene II and hydrogenated styrene-butadiene block copolymer;

the melting point of the polypropylene II in the skin layer is 30-40 ℃ lower than the melting point of the polypropylene I in the core layer.

2. The hot melt-processable fiber of claim 1, wherein the mass ratio of the sheath layer to the core layer is 1:2-1:1.

3. The hot melt-processable fiber according to claim 1, wherein the weight ratio of the polypropylene II to the hydrogenated styrene-butadiene block copolymer in the sheath layer is from 4:1 to 9:1.

4. The hot-melt-processable composite fiber according to claim 1, wherein the polypropylene I has a melt index of 3g/10min-15g/10min; the melting point of the polypropylene I is 160-170 ℃.

5. The hot melt composite fiber of claim 4, wherein the polypropylene I is a homo-polypropylene.

6. The hot-melt-processable composite fiber according to claim 1, wherein the polypropylene II has a melt index of 3g/10min to 5g/10min and the hydrogenated styrene-butadiene block copolymer has a melt index of 10g/10min to 30g/10min in the sheath.

7. The heat fusible composite fiber of claim 1, wherein the diameter of the heat fusible composite fiber is 0.05mm to 0.06mm.

8. The hot melt composite fiber of claim 1, wherein the material composition of the sheath layer and the material composition of the core layer further each independently comprise a lubricant selected from one or more of fatty acid amide compounds, fatty acid compounds, paraffin and hydrocarbon resins, silicone compounds, silicone polymers, fluorine compounds, copolymers of tetrafluoroethylene and propylene, and copolymers of vinylidene fluoride and hexafluoropropylene.

9. A method of preparing a hot melt composite fiber according to any one of claims 1 to 8, comprising the steps of:

after melt extrusion of a skin material component containing a polypropylene II and hydrogenated styrene-butadiene segmented copolymer through a first screw, the skin material component enters a first metering pump for accurate metering, and then enters a skin channel of a skin-core spinning double-channel composite die head;

after the core layer material component containing the polypropylene I is melted and extruded by a second screw, the core layer material component enters a second metering pump for accurate metering, and then enters a core layer channel of a sheath-core spinning double-channel composite die head;

the sheath material component and the core material component are compounded into a fiber with a sheath-core structure on a spinneret plate provided with a plurality of spinneret holes after passing through respective channels; extruding the fiber with the sheath-core structure through a spinneret plate to obtain a plurality of primary spinning fibers with the sheath-core structure;

the primary spinning fibers enter a cooling water tank for cooling, and each fiber in the cooling water tank is separated after entering a respective yarn channel; the obtained spinning fiber is stretched in primary water bath by a stretching roller, and is stretched in hot air in a hot box; after being stretched, each spinning fiber is independently wound into a spinning cake, and the hot-melt composite fiber is obtained;

the first-stage water bath stretching multiple is 4-8 times, and the water bath temperature is 80-95 ℃; the hot air stretching multiple is 1.1-1.5 times, and the hot air temperature is 85-95 ℃.

10. A web prepared from the hot melt composite fiber of any one of claims 1-8.

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