JP2984542B2 - Heat-shrinkable conjugate fiber with thermal adhesion - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat-shrinkable conjugate fiber having heat bonding property.

[0002]

2. Description of the Related Art Generally, as for heat-bondable fibers, as described in JP-A-62-69822 and JP-A-5-9809, wrinkles are prevented from being formed on a nonwoven fabric during bonding by heat treatment. The thing which is hard to shrink itself,
That is, fibers having a small heat shrinkage are mainly proposed.

Recently, various fibers utilizing polymers having a large heat shrinkage, such as olefin copolymers and ester copolymers, have been developed.
JP-A-44108 proposes a heat-shrinkable fiber comprising an ethylene-propylene copolymer.

[0004] It is possible to obtain a high-density non-woven fabric by subjecting a non-woven fabric composed of only these heat-shrinkable fibers or a mixture of the heat-shrinkable fibers and other fibers to heat treatment and shrinking the heat-shrinkable fibers. it can. In addition, many bulky nonwoven fabrics having crepe-like irregularities on the surface of the nonwoven fabric have been proposed by utilizing the shrinkage property, and most of them have integrated a non-shrinkable fiber layer and a shrinkable fiber layer. rear,
It is obtained by shrinking the shrinkable fiber layer by heat treatment and simultaneously wrinkling the non-shrinkable fiber layer.

In both the high-density non-woven fabric and the bulky non-woven fabric, if the non-woven fabric is to be maintained in a certain form and to have a certain degree of strength, it must be connected in some way between the constituent fibers or between the respective fiber layers. Must. Bonding is generally, for example, a method of entanglement between fibers by needle punching or high-pressure water jet treatment,
Alternatively, it is achieved by applying a method of bonding between fibers or between layers with some adhesive component.
An adhesive component generally used for bonding between fibers or between layers is a thermal adhesive component that is melted and softened by heat treatment.

[0006]

The fiber proposed by the present applicant does not have thermal adhesiveness itself, and therefore, when it is desired to bond between fibers or between fiber layers by heat treatment,
It is necessary to mix thermoadhesive fibers as thermoadhesive components.
However, the step of mixing two or more fibers, a so-called cotton blending step, is not preferable in terms of cost. Moreover,
If two or more types of fibers are not uniformly mixed, the homogeneity of the obtained nonwoven fabric may be impaired, and quality problems may occur. Therefore, the present inventor believes that if there is a fiber having both heat bonding property and heat shrinking property, these problems do not occur, and it is composed of a heat shrinking component and a heat bonding component. As a result of intensive studies to obtain a composite fiber that undergoes heat shrinkage, the present invention has been achieved.

[0007]

That is, the present invention provides an ethylene-propylene random copolymer and / or ethylene-butene-1-propylene terpolymer having a melting peak temperature (Tm ° C) of 130 <Tm <145. A polymer containing 70% by weight or more of the union as a first component, a vinyl carboxylic acid monomer and / or a vinyl carboxylic acid ester monomer 5
A composite fiber having both heat adhesion and heat shrinkage, characterized in that an ethylene copolymer consisting of -30% by weight and 95-70% by weight of ethylene is used as a second component.

In the conjugate fiber of the present invention, the first component, which is a heat-shrinkable component, has a melting peak temperature (Tm ° C.) of 130 <Tm.
<145: a polymer containing 70% by weight or more of the ethylene-propylene random copolymer and / or the ethylene-butene-1-propylene terpolymer. Here, the melting peak temperature means a temperature at which a DSC curve shows a maximum value when a heat of fusion of a polymer is measured by a differential scanning calorimeter (DSC). Ethylene-propylene random copolymer and ethylene-butene-1 used for the first component
-Peak temperature of melting of propylene terpolymer of 130 ° C
If it is less than 1, the selection range of the heat bonding component as the second component described later becomes narrow, and if it exceeds 145 ° C., the dry heat shrinkage of the fiber becomes undesirably about that of a normal polypropylene fiber.

The ethylene-propylene random copolymer and the ethylene-butene-1-propylene terpolymer have extremely high heat shrinkage. For example, a fiber drawn only about 3 times and composed of only an ethylene-propylene random copolymer shows a heat shrinkage of 93% within 1 minute at 135 ° C. just below the melting point. Similarly, a three-fold stretched fiber composed of only the ethylene-butene-1-propylene terpolymer exhibits a heat shrinkage of 80% at 135 ° C. just below the melting point. Therefore, other polymers can be mixed in order to control the heat shrinkability, but in the present invention, the ethylene-propylene random copolymer and / or ethylene-butene-1-propylene terpolymer contained in the first component is used. The proportion of the original copolymer is preferably at least 70% by weight. 70
If the amount is less than 10% by weight, the maximum heat shrinkage of the obtained composite fiber is less than 50%, and the heat shrinkage becomes insufficient. Here, the maximum heat shrinkage rate is 1 at an atmosphere of 145 ° C.
This is the shrinkage rate when the sample is left for one minute. Hereinafter, unless otherwise specified, the term “heat shrinkage rate” refers to the maximum heat shrinkage rate under this condition.

The polymer to be mixed with the ethylene-propylene copolymer and / or the ethylene-butene-1-propylene terpolymer is not particularly limited, and a polyolefin-based polymer such as polypropylene which is inferior in heat shrinkage to these polymers. Can be used.

The second component of the conjugate fiber of the present invention is composed of a heat bonding component. This heat bonding component must be composed of a polymer whose melting point is lower than the shrinkage onset temperature of the ethylene-propylene random copolymer. However, since the thermal shrinkage of the ethylene-propylene random copolymer starts slightly even under an atmosphere of about 90 ° C., it is not necessary to exactly understand the shrinkage onset temperature here, and the thermal shrinkage rate is 10%. % Can be regarded as a temperature lower than the shrinkage starting temperature. Examples of the polymer applicable to the second component include a vinyl carboxylic acid monomer and / or a vinyl carboxylic acid ester monomer 5
An ethylene copolymer having a melting point of 80 to 100 ° C., which is composed of 30% by weight and 95 to 70% by weight of ethylene, may be used. Here, the vinyl carboxylic acids include monocarboxylic acids such as acrylic acid and methacrylic acid, and dicarboxylic acids such as maleic acid, and the esters thereof include methyl acrylate and ethyl acrylate. Specifically, ethylene-acrylic acid copolymer, ethylene-methyl acrylate copolymer, ethylene-ethyl acrylate copolymer, ethylene-methyl methacrylate copolymer, ethylene-ethyl methacrylate copolymer, ethylene- A methyl acrylate-acrylic acid copolymer or the like can be used. Among them, the ethylene-methyl acrylate copolymer is most preferably applied because it has a low melting point and good thermal adhesion to non-olefin fibers such as acrylic fibers.

The composite fiber of the present invention may have a structure in which the second component occupies at least a part of the fiber surface. For example, in the fiber cross section, the first component and the second component are alternately arranged in parallel in a parallel type, the first component and the second component are alternately arranged in a chrysanthemum shape, or the first component is a core component And a core-sheath type in which the second component is a sheath component. Among them, the core-sheath type,
Most desirable in terms of adhesiveness. In addition, the composite ratio of the two components is a volume ratio, and the ratio of the first component / the second component is in the range of 3/7 to 7/3. It is desirable from the point of view.

The conjugate fiber of the present invention has a spinning temperature of 190-3.
It is obtained by melt-compound spinning in the range of 00 ° C.
Further, it is desirable that the melt flow rate value (MFR) of both components is 13 or more and less than 100 within this temperature range. If the spinning temperature is lower than 190 ° C., the melt spinnability deteriorates, which is not preferable. If the spinning temperature is higher than 300 ° C., the heat stabilizer added to the polymer is undesirably decomposed. If the MFR of both components during melt spinning is less than 13, the fluidity is insufficient, and if it exceeds 100, the fluidity becomes too large and the spinnability deteriorates. Therefore, when spinning the conjugate fiber of the present invention, the MFR is 13 to 100.
Is selected within the range of 190 to 300 ° C.
What is necessary is just to melt-spin at that temperature.

The conjugate fiber of the present invention thus obtained has both functions of heat bonding and heat shrinkage. These two functions are exerted individually by two-stage heat treatment. That is, first, heat treatment is performed at a temperature higher than the melting point of the heat bonding component and lower than the shrinkage start temperature of the heat shrinking component, thereby melting the heat bonding component and bonding the fibers. At this temperature, since the heat shrinkage of the heat shrinkage component is suppressed to within 10%, various problems caused by the heat shrinkage of the fiber at the time of heat bonding, for example, a spider web-like density unevenness in the nonwoven fabric may occur. Instead, the conjugate fiber of the present invention functions exclusively as a heat-adhesive fiber, and enables uniform heat bonding. A specific desirable heating temperature at the time of thermal bonding is 90 to 100 ° C. This is because the heat shrinkage component starts to shrink when the temperature exceeds 100 ° C.

Subsequently, a heat treatment is performed at a temperature higher than the shrinkage starting temperature of the heat shrinkage component, so that the heat shrinkage is positively caused. Since the heat shrinkage is performed in a state where the heat bonding is already completed, it is no longer necessary to consider density unevenness or the like caused by the heat shrinkage, and the heat shrinkage is achieved in a uniform state. A specific desirable heating temperature (T ° C.) at the time of heat shrinkage is 100 <T <= T
m + 30. If the temperature is lower than 100 ° C., the heat shrinkage is insufficient, and if it exceeds Tm + 30 ° C., the fiber is completely melted and the shrinkage stress is significantly reduced.

The conjugate fiber of the present invention can be used in various modes, and may be used by mixing with other fibers. For example, if another synthetic fiber and the composite fiber of the present invention are mixed and made into a web and then subjected to heat treatment, a high-density heat-bonded nonwoven fabric can be obtained. By subjecting the sheet to heat treatment, a bulky wet nonwoven fabric or paper can be obtained. In addition, a fiber layer containing the conjugate fiber of the present invention and a fiber layer made of non-shrinkable fiber are laminated and integrated by heat bonding, and then the fiber of the present invention is heat-shrinked to obtain a non-shrinkable fiber layer. Can be formed into a multi-wrinkled nonwoven fabric having a large number of wrinkles formed on the surface thereof.

[0017]

In the present invention, the first component acts as a heat shrink component and the second component acts as a heat bonding component. Therefore, when a non-woven fabric is formed using these fibers, the second component is a heat bonding between the fibers by heat treatment and becomes an element that determines the strength of the non-woven fabric, and the first component shrinks to increase the density of the non-woven fabric. do. In the case where the fiber layer containing the conjugate fiber of the present invention and the fiber layer made of the non-shrinkable fiber are laminated to form a nonwoven fabric, the second component exclusively contributes to the thermal bonding between the fibers and between the fiber layers. However, the first component thermally shrinks to form a large number of wrinkles and irregularities on the surface of the non-shrinkable fiber layer, and plays a role in increasing the bulk of the nonwoven fabric.

[0018]

The present invention will be described below with reference to examples.
Of course, the present invention is not limited to this embodiment.

Examples 1-3: Melting point: 133 ° C., 136
The first component (core component) is composed of an ethylene-propylene random copolymer (EP) at 140 ° C and 140 ° C as a first component, and an ethylene-methyl acrylate copolymer (EMA) having a melting point of 92 ° C as a second component. The core-in-sheath type composite fiber is spun at a spinning temperature of 26 so that the volume ratio of the second component (sheath component) becomes 5/5.
It was melt spun at 0 ° C. This was stretched 3.4 times in warm water at 50 ° C., and subsequently a room temperature antistatic fiber treating agent was applied. After further machine crimping in the staffer box,
It was dried with a 60 ° C. net conveyor hot air penetration dryer and cut into 51 mm lengths to form staple fibers. Here, the ethylene-propylene random copolymer having a melting point of 133 ° C. is referred to as Example 1, the one having a melting point of 136 ° C. is referred to as Example 2, and the one having a melting point of 140 ° C. is referred to as Example 3.

Example 4 Ethylene having a melting point of 136 ° C.
A first component (core component) / a second component (sheath component) using a propylene random copolymer as a first component and an ethylene-methyl acrylate copolymer (EMA) having a melting point of 82 ° C. as a second component.
The core-sheath type conjugate fiber was melt-spun at a spinning temperature of 260 ° C. so that the volume ratio of the composite fiber became 5/5. This was subjected to a post-treatment in the same manner as in Examples 1 to 3 above to form a staple fiber of 51 mm.

Examples 5 to 7 Ethylene-acrylic acid copolymer (EAA), ethylene-ethyl acrylate copolymer (EEA) containing ethylene-propylene random copolymer having a melting point of 136 ° C. as a first component. , A polymer selected from ethylene-methyl acrylate-acrylic acid copolymer (EMAA) as a second component, and the volume ratio of the first component (core component) / the second component (sheath component) is 5/5. Was melt-spun at a spinning temperature of 260 ° C. This was subjected to post-treatment in the same manner as in Examples 1 to 3, and cut into a length of 51 mm to form staple fibers. Here, the second component was an ethylene-acrylic acid copolymer in Example 5, and the ethylene-ethyl acrylate copolymer in Example 6, an ethylene-methyl acrylate-acrylic acid copolymer. An example is referred to as a seventh embodiment.

Example 8 70% by weight of an ethylene-propylene random copolymer (EP) and polypropylene (P
P) a polymer mixed with 30% by weight as a first component,
The first component (core component) / the second component (sheath component) is 5/5 with ethylene-methyl acrylate (EMA) as the second component.
The core-sheath type composite fiber was melt-spun at a spinning temperature of 260 ° C. This was post-processed in the same manner as in Examples 1 to 3 above to obtain 51 mm staple fibers. This is Example 8.

Example 9 An ethylene-butene-1-propylene terpolymer (EBP) was used as a first component, and an ethylene-methyl acrylate copolymer (EMA) was used as a second component. The core component) / the second component (sheath component) is 5 /
The core-sheath type composite fiber was melt-spun at a spinning temperature of 260 ° C. so as to obtain a composite fiber of No. 5. This was post-processed in the same manner as in Examples 1 to 3 above to obtain 51 mm staple fibers. This is Example 9.

COMPARATIVE EXAMPLES 1-2 High crystalline polypropylene (HCPP) and polypropylene (PP) were used as first components, respectively, and ethylene-methyl acrylate copolymer (EM
Using A) as the second component, the core-in-sheath type composite fiber was melt-spun at a spinning temperature of 260 ° C. such that the ratio of the first component (core component) / second component (sheath component) was 5/5. This was applied to Examples 1 to 3 above.
The post-treatment was carried out in the same manner as described above to obtain 51 mm staple fibers. Here, Comparative Example 1 uses high-crystalline polypropylene as the first component, and Comparative Example 2 uses polypropylene as the first component.

Comparative Example 3 The first component (core component) was prepared by using ethylene-propylene random copolymer (EP) as a first component and high-crystalline polyethylene (HDPE) as a second component.
The core-sheath type conjugate fiber was melt-spun at a spinning temperature of 260 ° C. so that the second component (sheath component) became 5/5. This was post-processed in the same manner as in Examples 1 to 3 above to obtain 51 mm staple fibers. This is referred to as Comparative Example 3.

Here, the above Examples 1 to 9 and Comparative Examples 1 to
Table 1 and Table 2 show the fiber performance of the fiber No. 3. Here, as a reference example, Table 2 also shows the fiber performance of the fiber composed of only the ethylene-propylene random copolymer. The heat shrinkage in the table is a value when the fiber is placed in an atmosphere at that temperature for 1 minute.

[0027]

[Table 1]

[0028]

[Table 2]

[Example 10] A web was prepared with a parallel card using only the fiber of Example 1, and the web was fed between hot rolls at 95 ° C and a linear pressure of 0.1 kg / cm to form a composite fiber. The heat bonding component was melted to bond the fibers together to obtain a nonwoven fabric having a basis weight of 40 g / m ² . The strength of the obtained nonwoven fabric was 2.5 kg / cm. Furthermore, when this nonwoven fabric was treated at 140 ° C. for 1 minute using a hot air penetration type thermal processing machine, the area shrank by 60% and the density increased by 40%, so that a high-density nonwoven fabric could be obtained.

Example 11 A web having a basis weight of 30 g / m ² was formed with a parallel card using only the fibers of Example 1. This is a basis weight of 40 g / m ² made of polypropylene.
By superimposing with a spunbonded non-woven fabric of 95 ° C. and supplying between hot rolls at a linear pressure of 0.1 kg / cm,
Thermal bonding was performed between the fibers in the web and between the web and the spunbonded nonwoven fabric to form a nonwoven fabric in which both were integrated. Furthermore, when this nonwoven fabric was treated at 140 ° C. for 1 minute using a hot air penetration type thermal processing machine, the fibers of Example 1 were thermally contracted, and the contraction force caused partial separation between the spunbonded nonwoven fabric and the web. Furthermore, a multi-wrinkled non-woven fabric having a large number of wrinkles formed on the spun-bonded non-woven fabric was obtained.

Example 12 The same fibers as those in Example 1 and Reference Example in Table 2 were melt-spun and stretched, and then a dispersibility improving fiber treating agent for paper was applied. Raw material for paper. 15 parts of the paper raw material composed of the fiber of Example 1, 15 parts of the paper raw material composed of the fiber of the reference example, and 70 parts of pulp were put into water, and a sizing agent and a surface tension reducing agent were further added thereto and mixed well. After that, papermaking was performed.
The papermaking sheet was dried with a 100 ° C. Yankee dryer and then processed in a 135 ° C. hot air penetration type thermal processing machine. As a result, the thickness became 1.5 times that before the heat treatment, and bulky paper could be obtained.

[0032]

The present invention relates to a conjugate fiber having both heat bonding property and heat shrinkability, wherein heat treatment is performed at the melting point of the heat bonding component and then heat treatment at the shrinking temperature of the heat shrinking component. Is characterized in that the heat bonding process and the heat shrinking process can be performed separately.
Therefore, when a nonwoven fabric is formed using this, it is not necessary to mix the heat-adhesive fibers, and since there is no influence of heat shrinkage during the heat bonding, a uniform heat-bonded nonwoven fabric can be obtained. And after heat bonding, it can be used as a heat-shrinkable fiber, and by a conventionally known method,
High-density nonwoven fabric, bulky paper, and multi-wrinkled nonwoven fabric can be formed.

As described above, the conjugate fiber of the present invention enables the heat-shrinkable fiber to be widely used for a heat-bonded nonwoven fabric.
And by utilizing its heat shrinkage properties, for example,
A high-density nonwoven fabric, multi-wrinkled nonwoven fabric, or bulky paper suitable for a filter material, a cushion material, a wiper, a towel, a wall material, a packaging material, and the like can be obtained.

Claims (2)

(57) [Claims] 1. A melting peak temperature (Tm ° C.) of 130 <T
a first component containing a polymer containing 70% by weight or more of an ethylene-propylene random copolymer and / or an ethylene-butene-1-propylene terpolymer having m <145, and a vinyl-based polymer such as acrylic acid, methacrylic acid, or maleic acid; An ethylene copolymer comprising 5 to 30% by weight of a monomer of a carboxylic acid and / or a monomer of a vinyl carboxylic acid ester and 95 to 70% by weight of ethylene is used as a second component. A heat-shrinkable conjugate fiber, characterized in that the second component occupies at least a part of the fiber surface. 2. The heat-shrinkable conjugate fiber according to claim 1, wherein the first component is a core-sheath conjugate fiber in which the second component is a sheath component.