JPH028048B2 - - Google Patents

Description

[Detailed description of the invention]

<<Industrial Application Field>> The present invention relates to a heat-fusible fiber mainly composed of a polyolefin resin having excellent heat-fusibility and used as a binder for nonwoven fabrics. ≪Prior art and its problems≫ In recent years, polypropylene fibers are used as the main fiber, and heat-fusible fibers are appropriately mixed therein, as skin materials for hygiene products such as masks, disposable diapers, and menstrual napkins. A nonwoven fabric is then used in which these fibers are thermally fused using hot air or an embossing roller. This type of nonwoven heat-fusible fiber does not use chemical adhesives, so it is hygienic with no risk of skin damage, and the surface material does not absorb even if it gets wet from urination etc. Polyolefin resins have been adopted for functional and economical reasons, such as their hydrophobicity that allows them to maintain a smooth feel, their relatively low price, and their stability. The field of disposable diapers is rapidly increasing due to social advancement, changes in lifestyle, and aging of society. Conventionally, this kind of nonwoven fabric has been made of single-component fibers with low tactility such as polypropylene, ethylene-propylene copolymer, or a mixture of polyester and polypropylene to lower the softening point, or with a high melting point. The main component is polypropylene on the side, and high-density polyethylene, low-density polyethylene, linear low-density polyethylene, ethylene vinyl acetate, etc. are used on the low-melting point side, and these are used in a sheath-core type or bonded type. A composite system is available, but it has the following problems. In other words, when using heat-fusible fibers, a wide range of fusing conditions is required in the nonwoven fabric manufacturing process, that is, one that does not require very strict temperature control and has high fusing strength. With conventional heat-fusible fibers, the temperature can be controlled within a narrow range of 1 to 2 degrees Celsius, and in order to increase the strength of nonwoven fabrics, the mixing ratio of heat-fusible fibers to the main fibers has been increased, and the overall basis weight has been improved. are forced to. For this reason, there were problems in that the quality became unstable due to fluctuations in outside temperature, etc., and that the fabric weight became high to satisfy the strength of the fusion bond, making it unprofitable in terms of cost. As a solution to these problems, a method has been proposed in which the low-melting point components of the composite fiber system are modified to increase the fusion strength, but this requires an additional modification step to adjust the raw material, and its effectiveness is also limited. It wasn't enough. In order to solve the problems of the prior art, the present inventors have developed a technology that allows for a wide range of fusion conditions and high fusion in the nonwoven fabric manufacturing process without adding a special process for adjusting raw materials. The present invention was achieved through extensive research into heat-fusible fibers that can provide strength. <<Means for solving the problems>> The structure of the present invention to achieve the above object is as follows:
1-20% by weight of petroleum resin in polyolefin resin
The basic composition is a polyolefin fiber in which the composition obtained by adding the composition alone or the composition is used as at least one component of a composite fiber having a parallel type or sheath-core type structure. In the present invention, the polyolefin resin refers to crystalline polypropylene, ethylene-propylene copolymer, or polyethylene and a mixture thereof, and in addition to this, aliphatic or aromatic petroleum resins made from petroleum resources, For example, a C5 aliphatic petroleum resin which is a polymer or copolymer mainly composed of isoprene, cyclopentadiene, 1,3-pentadiene, 1-pentene, 2-pentene, dicyclopentadiene, etc., or indene,
C8~ which is a polymer or copolymer mainly composed of styrene, methylindene, α-methylstyrene, etc.
Petroleum resins selected from C10 aromatics, hydrogenated alicyclic polymers or copolymers, and aromatic aliphatic copolymers are added to The main raw materials are those added and mixed at a ratio of 20% by weight, and various stabilizers, colorants, etc. may be added to these depending on the purpose. The amount of petroleum resin added is 1 to 20
If the amount is less than 1% by weight, a sufficient effect cannot be obtained, and if it is more than 21% by weight, the spinnability of the fiber decreases, making stable operation impossible. In addition, the softening point of the petroleum resin to be added is 70 to 150.
Must be within the range of ℃. If the softening point is below 70°C, the heat resistance will deteriorate and the fusion efficiency will not increase. On the other hand, if the temperature is 150°C or higher, the flow activation energy becomes large, and therefore the fusion efficiency does not increase as well. Furthermore, in cases where it is undesirable to color the fibers, such as fibers for hygiene products, it is desirable to use petroleum resins that have been decolored by hydrogenation. In this case, the addition of hydrogen has no effect on spinnability or fusion properties. The fiber of the present invention has the above-mentioned raw material composition, and can be a single-component fiber, a parallel-type single-component fiber in which two components are bonded together, or a high-melting-point component on the core side.
It is obtained by spinning a sheath-core type component with a low melting point component on the sheath side, stretching and heat treating it, and the difference in melting point between each component in the composite type fiber is 20℃. It is desirable that there be at least one. <<Example>> Hereinafter, preferred embodiments of the present invention will be described. Examples 1 to 4 High-density polyethylene (MI
= 20) 70 parts of alicyclic petroleum resin (Alcon p-100 manufactured by Arakawa Chemical Co., Ltd., softening point 100°C, molecular weight 700), which is obtained by adding hydrogen to C9 alkylbenzene, which is a C8-C10 aromatic petroleum resin. After adding 30 parts and kneading it uniformly, it is pelletized using a pelletizer to create a petroleum resin masterbatch. Using sheath-core type composite fiber spinning equipment consisting of two single-screw extruders and a composite fiber nozzle with a hole diameter of 0.6 mm, crystalline polypropylene (MI =
15), the sheath component is high-density polyethylene (MI=20)
Based on the above, the masterbatch was added so that the amount of petroleum resin was 1, 5, 10, and 20% by weight, respectively, and the spinning temperature was 250℃ and the take-up speed was 800m/min.
A sheath-core type composite fiber with a single yarn denier of 6.0 de was obtained. Although the cross-sectional area ratio of the sheath component to the core component was 1:1, both had excellent spinnability, and no breakage occurred even once during one hour. 300 of these multifilaments were collected to a total denier of approximately 400,000 yen, and then drawn, oiled, crimped, cut, dried, and heat treated using staple fiber prototype equipment, resulting in a single filament with a denier of 2de.
A staple fiber with a cut length of 51 mm and a number of crimps of 15/inch was obtained. The heat treatment is done with hot air at 100℃.
I did it for 10 minutes. The oil was alkyl phosphate and was deposited at 0.30%. Table 1 shows the properties of the single fiber thus obtained. This staple fiber was passed twice through a sample card machine with a width of 350 mm to produce a uniform web with a basis weight of 20 g/m ² . The card characteristics at this time are also shown in Table 1, and in all cases the card passageability is improved. This web has a seal area of 8% and a seal contact pressure of 5
Point-sealed nonwoven fabrics were made using an embossing roll with a sealing speed of 3 m/min and a sealing speed of 3 m/min, with the surface temperature varied from 117.5°C to 130°C. In addition, when the surface temperature was 135°C or higher, excessive melting occurred, resulting in a film-like appearance and at the same time, shrinkage increased. On the other hand, the web was placed on a wire mesh belt with a width of 350 mm and a speed of 5 m/min, the hot air temperature was varied from 132.5 to 145°C, and hot air was blown at a speed of 2 m/s for 5 seconds.
A hot air fused nonwoven fabric was also created. In this case, when the hot air temperature was 150° C. or higher, the nonwoven fabric became excessively melted and the shrinkage increased significantly. When we examined the tearing length and fly height of the nonwoven fabric created by hot air fusion (see Table 1 and Figures 1 to 4), we found that both had high fusion strength and excellent fusion strength over a wide temperature range. A nonwoven fabric was obtained with Therefore, there is no need for strict temperature setting and management as in the past.
Products with stable quality can be obtained even if there are slight changes in outside temperature, etc., and production speed and basis weight can be varied over a wide range.Moreover, they have excellent spreading properties and have a good feel to the touch, which is one of the required performances for disposable diapers. was gotten. As is clear from Table 1 and FIGS. 1 to 4, this tendency appears more prominently in hot-air fused nonwoven fabrics. Comparative Examples 1-3 Using the same method as Examples 1-4, high-density polyethylene alone and alicyclic petroleum resin (Alcon p-100 manufactured by Arakawa Chemical Co., Ltd.) were used as sheath components at 0 and 0, respectively.
Using high-density polyethylene containing 0.5% and 25% by weight, three types of sheath-core composite fibers with different raw material ratios were spun. As a result, both Comparative Examples 1 and 2 had good spinnability, with only 1 yarn breakage during 1 hour of spinning.
However, in Comparative Example 3, 5 to 5 times per hour occurred.
Spinning breakage occurred seven times, and stable spinning was not possible. Furthermore, regarding Comparative Examples 1 and 2, card characteristics,
When we investigated the properties of the nonwoven fabric, we found Table 1 and Figures 1 to 4.
As shown in the figure, in all cases, the card passing properties were inferior to those of the examples, and the heat-sealing strength and flowability were also inferior. Furthermore, the fusion strength has a large temperature dependence, and the fusion temperature affects the fusion strength and the feel. That is, if the fusion temperature is low, the fusion strength will be weak, and conversely, if the fusion temperature is high, it will become hard and the texture will be poor. Examples 5 to 7 Using the same method as Examples 1 to 4, the core component was crystalline polypropylene (J130G, manufactured by Ube Industries, Ltd.), and the sheath component was made of high-density polyethylene (J310, manufactured by Asahi Kasei Corporation).
As the aliphatic petroleum resin, isoprene polymer (Example 5, Finton A-100 manufactured by Nippon Zeon Co., Ltd.,
Also, the same polymer (Example 6, Quinton C-100 manufactured by Nippon Zeon Co., Ltd., softening point 95°C),
Higher hydrocarbon petroleum resin (Example 7, Mitsui Petrochemical
Co., Ltd.'s FTR-6100 (softening point: 97°C) was added to make a sheath-core composite fiber of 5% by weight, and the spinnability, carding properties, and nonwoven fabric properties were investigated.
Excellent results were obtained as shown in . Example 8 Using the same method as in Examples 1 to 4, crystalline polypropylene (manufactured by Ube Industries, Ltd., J130G) was used as the core component, and alicyclic petroleum resin (Alcon P-, manufactured by Arakawa Chemical Co., Ltd.) was used as the sheath component.
A sheath-core composite fiber was spun using maleic anhydride-modified high-density polyethylene (manufactured by Nippon Petrochemical Co., Ltd., N Polymer S0792) containing 5% by weight of 125, molecular weight 820, softening point 125°C). As a result, spinnability,
When the card properties and nonwoven fabric properties were investigated, excellent results were obtained in both cases as shown in Table 3. Example 9 Ethylene propylene random copolymer (manufactured by Ube Industries, Ltd., ethylene content 2% MI = 30) and polypropylene homopolymer were prepared using spinning equipment consisting of a single-screw extruder and a nozzle for single fibers with a hole diameter of 0.5 mm. (manufactured by Ube Industries, Ltd., MI=30) in a 1:1 ratio, and this is mixed with aromatic aliphatic copolymer (Toho Oil Resin).
A single heat-fusible fiber was prepared from a resin to which 3% by weight of Toho Hi-Resin #90 (softening point: 95°C) was added. When a single heat-fusible fiber is fused with hot air, a uniform nonwoven fabric cannot be obtained due to heat shrinkage, so the nonwoven fabric properties were investigated using a point seal fused nonwoven fabric. Note that point sealing was performed at a surface temperature of the embossing roll at this time of 137.5°C to 145°C.
As a result, the card properties and nonwoven fabric properties were superior as shown in Table 3, compared to Comparative Example 4 which did not contain the aromatic aliphatic copolymer petroleum resin. Examples 10 to 12 The heat-fusible fiber obtained in Example 2 was mixed with 50% each of polypropylene (regular) fiber, polyester fiber, and rayon fiber with a single yarn denier of 2de and a cut length of 51 mm, and a sample with a width of 350 mm was prepared. The mixture was passed through a card machine three times to create a uniformly mixed web with a basis weight of 20 g/m ² . The nonwoven fabric properties of this web were investigated using the same method as in Examples 1 to 4. Table 4 As shown, all were excellent. Example 13 Using the same method as in Examples 1 to 4, a low-temperature resin was prepared by adding 8% by weight of alicyclic petroleum resin (Alcon P-90 manufactured by Arakawa Chemical Co., Ltd., molecular weight 630, softening point 90°C) as a sheath component. A sheath-core composite fiber was spun at 240°C using density polyethylene (J2522 manufactured by Ube Industries, Ltd.). the result,
There was no problem with spinnability. In addition, card characteristics,
The properties of the nonwoven fabric were superior compared to Comparative Example 8, which did not contain an alicyclic petroleum resin. In addition, the embossing roll surface temperature during nonwoven fabric creation is 100 to 120℃, and the hot air temperature is
It was carried out at 110°C to 130°C. Examples 14 and 15 Crystalline polypropylene (Ube Industries, Ltd.) to which 5% by weight of alicyclic petroleum resin (Alcon p-125, manufactured by Arakawa Chemical Co., Ltd.) was added to the core component in the same manner as in Examples 1 to 4
J1159), the sheath component is high-density polyethylene (Santec J310, manufactured by Asahi Kasei Corporation) alone, and 5% by weight of alicyclic petroleum resin (Alcon P-125, manufactured by Arakawa Chemical Co., Ltd.).
A sheath-core composite fiber was spun at 250°C using the added high-density polyethylene (Santetsu J310 manufactured by Asahi Kasei Corporation). As a result, there was no problem with spinnability. In terms of the strength of the nonwoven fabric, superior results were obtained in all cases compared to Comparative Example 9, which did not contain an alicyclic petroleum resin. This is considered to be due to an increase in the adhesive strength between the sheath component and the core component. When the fractured part of the nonwoven fabric after the tensile test of Comparative Example 9 is observed with an electron microscope, it is observed that where the heat-fused fibers are fused, separation is observed at the interface between the sheath component and core component within the fiber. . This tendency is even stronger for parallel types. Therefore, in order to measure the adhesive strength between the sheath component and the core component, we used a nozzle for parallel type composite fibers with a hole diameter of 0.7 mm to Composite fibers were spun and peel tests were conducted on both components. Peeling tensile speed is 40mm/
The peel strength (g/mm) was obtained by dividing the obtained value by the contact width. As a result, those in which the alicyclic petroleum resin is added to the core component have a higher peel strength than those without the addition, and those in which the alicyclic petroleum resin is added to both the sheath component and the core component show an even greater value.
Therefore, it seems that the increased adhesive strength between the sheath component and the core component contributes to the strength of the nonwoven fabric. The evaluation method in each example or comparative example is as follows. *Spinning properties: Those with 1 or less spinning breaks per hour were considered good, those with 2 to 12 times were judged as poor, and those with 13 or more breaks were judged as unacceptable. *Single fiber properties: Measured according to JIS L1015 chemical fiber staple test method. Tensile strength at break, elongation, and apparent Young's modulus: Tensile at a gripping gap of 20 mm and a tensile speed of 20 ± 1 mm/min.
Calculated from the load when the sample is cut and the load change with respect to the elongation change near the origin of the load-elongation curve. The number of tests was 30. Number of crimp, crimp ratio, and crimp elasticity modulus: For the number of crimp, count the number of crimp when applying an initial load of 2 mg/denier to the sample, and calculate the number of crimp per 25 mm.
The number of tests was 20, and the average value was displayed.
In both Examples and Comparative Examples, the number was set to 15. The crimp rate and crimp modulus are 2
Length (a) when initial load of mg/denier is applied,
Measure the length (b) when applying an initial load of 50 mg/denier, then remove the full load, leave it for 2 minutes, apply an initial load of 2 mg/denier, and read the length (c). , was calculated using the following formula. The number of tests is 20.
times and expressed as the average value. Crimp ratio (%) = b-a/b x 100 Crimp modulus (%) = b-c/b-a x 100 *Card characteristics: 100g/m ² with sample card machine
A web was prepared, passed through a random card machine, and the web that came out was harvested after 5 and 10 minutes, and the basis weight per m ² was measured to determine card passing properties. At this time, the state and uniformity of the neps were observed, and the card characteristics were investigated. *Non-woven fabric properties: Pass through the sample card machine twice,
A uniform web with a basis weight of 20 g/m ² was prepared, and a point seal fused nonwoven fabric using an embossing roller and a hot air fused nonwoven fabric formed by blowing hot air were made, and the strength of thermal fusion bonding and high flyability were investigated. Strong thermal bonding; Machine direction from nonwoven fabric processed by thermal bonding according to JIS L-1068 tensile test method.
200mm x 50mm in width direction and 50mm in machine direction x width direction
Five specimens of 200 mm each were taken, the grip gap was 100 mm, and the tensile speed was 30 ± 2 cm per minute.
The tensile cutting strength in the machine direction (MD) and in the direction perpendicular to the machine direction (TD) was measured. Rupture length: The rip length was determined and compared using the following formula, taking into account the factor of the basis weight of the nonwoven fabric. In other words, this tearing length corresponds to the length at which the nonwoven fabric is cut under its own weight when suspended. Rupture length (m) = Thermal bonding strength (g) / Fabric weight (g/m ² ) x Sample width (0.05
0m) Thickness: 10 50mm/50mm test pieces were piled up, a load of 6.5g (0.26g/m ² ) was applied uniformly over the entire surface, and the total thickness was measured after 5 minutes. Tallness was investigated from the density. *Softening point: Measured by the ring and ball method according to JIS2207.

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[Table] ≪Effects≫ As explained above in the various examples, the strength of the nonwoven fabric can be improved by using the fibers of the present invention.
By adding a resin selected from C8 to C10 aromatic petroleum resins, alicyclic petroleum resins, and aromatic aliphatic copolymers, these components are Because of this, the fiber surfaces become sticky and the fibers that are in contact with each other are melted and bonded together with the adhesion of this adhesive force. This is thought to be due to the fact that it is possible to suppress the phenomenon of peeling off during driving or when the temperature drops even if the tires are attached. As explained in detail above, the polyolefin fibers of the present invention are suitable for nonwoven fabrics with high fusion strength, and are therefore suitable for use as skin materials for disposable diapers, for which demand is expected to increase, as well as nonwoven fabrics for various sanitary materials. It is.

[Brief explanation of drawings]

1 to 4 are graphs illustrating the breaking lengths of the embodiments of the present invention shown in Table 1.

Claims (1)

[Claims] 1 A polyolefin resin consisting of crystalline polypropylene, ethylene-propylene copolymer or polyethylene and a mixture thereof has a softening point selected from aliphatic, aromatic, alicyclic or aromatic aliphatic copolymers. Consisting of a raw material resin alone with 1 to 20% by weight of petroleum resin at 70 to 150°C added to the total weight, or the raw resin as at least one component of a composite fiber with a parallel type, sheath-core type structure. Characteristic polyolefin heat-fusible fiber.