JPS60139814A - Fiber having high specific gravity and strength - Google Patents

Abstract

PURPOSE:The titled fibers, consisting of sheath-core type conjugate fibers constituted of a sheath layer of polyethylene resin and a resin, containing dispersed powder of the specific gravity, and having compatibility with the above-mentioned resin of the sheath layer in a specific proportion, having a high specific gravity and strength, and suitable for fisheries materials, e.g. fishing nets. CONSTITUTION:Fibers which are sheath-core type conjugate fibers, formed from (A) a sheath layer consisting of polyethylene resin and a core layer consisting of (C) a resin, e.g. ethylene-vinyl acetate copolymer, containing dispersed (B) powder of high specific gravity, e.g. trilead tetroxide, the resin (C) of the core layer having compatibility with the resin (A) of the above-mentioned sheath layer and a lower softening point than the resin (A) of the sheath layer, the powder (B) of high specific gravity having <=10mu average particle diameter, and satisfying the following relations; (C/B)>=1.5 and 0.6<=A/(A+B+C)<=0.85 [(A), (B) and (C) are volumes of the resin (A), powder (B) and resin (C)].

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides fibers for fishery materials, particularly high specific gravity fibers used in fish nets;
Concerning fibers with high strength.

Traditionally, fibers as fishery materials are important for high sedimentation speed and shape retention of fishing nets against tidal currents. It is known to have good sex. For these reasons, vinylidene chloride fibers, which have a relatively high specific gravity, have been widely used as fibers made from a single resin, but with the development of net-making technology, they have also been developed to have high strength that can be used for high-speed net-making. As a result, conventional vinylidene chloride fibers have become insufficient in strength.

In other words, there are various net structures when braiding fibers into a fishing net, but in order to prevent high net costs, fish net fibers are desired to be economical and have high-speed net-making properties. is most desired. It is said that the net-making efficiency of Russell nets is several times higher than that of conventional ones.
The fibers are required to have high strength, and if the fibers do not have sufficient strength, high-speed net making cannot be achieved. Conventional vinylidene chloride fibers lack strength for raschel mesh (tensile strength 30
kg/mm2), and on the other hand, polyethylene fibers with a strength suitable for raschel nets (tensile strength 50 kg/mm)
' front and rear) and polyester fibers (tensile strength 50 kg/m
m'') has the disadvantage of low specific gravity and lack of high sedimentation speed.

Under these circumstances, development of high specific gravity and high strength marine materials is underway, and various products have been proposed. As one means of achieving this, fibers made of a combination of a resin that develops high strength through drawing treatment and a high specific gravity powder are considered.Specifically, (1) fibers made by uniformly dispersing a high specific gravity powder in a resin ( For example, Japanese Patent Publication No. 51-373T8, Japanese Patent Publication No. 56-61936), <2) A high specific gravity powder is mixed and dispersed in a low softening point resin, and this mixture is further mixed with a resin for imparting strength. Textile (Special Publication No. 57-20407
No. 1) and (3) a cored fiber having a core layer made of a mixture of a low softening point resin and a high specific gravity powder and a sheath layer made of a strength-imparting resin (Japanese Unexamined Patent Publication No. 58-4819), etc. are disclosed.

However, the fibers and literature described in the examples specifically disclosed in these patent-related publications [r Textile and Industry J VOI
29 N1112 (1973) P 443-P 4
47 Figure 4] When looking at the relationship between specific gravity and tensile strength for the fibers described, even though the type of resin and the type of high specific gravity powder are not the same, as shown in Figure 1, these are approximately straight lines. The graphs on the top indicate that the higher the specific gravity, the lower the strength. In this way, the combination of a general-purpose resin and a normal high specific gravity powder has a specific gravity (approximately 1.5 or more) and strength (tensile strength of 50 kg / Fibers having a diameter of 1 mm2 or more have not yet been provided, and FIG. 1 also shows the difficulty.

Fibers for fishing nets are required not only to have the above-mentioned high sedimentation rate and high-speed net-forming properties, but also to have durability. The above cored fibers are
Unlike other types of fibers that use high-density powder, the surface is composed only of high-strength resin, so there is no disadvantage caused by the presence of high-density powder on the surface, which is a preferable structure, but the sheath layer Interfacial delamination between the core layer and the core layer is likely to occur, resulting in poor practical durability. That is, when a fishing net is put into practical use, the fibers are scraped from the surface by friction with various objects and become fibrillar, causing vertical cracks in the sheath layer, and when these reach the core layer, glabellar peeling occurs. The tensile strength suddenly decreases and becomes unusable.

In view of the current situation, the present inventors have researched fibers that are made of a combination of general-purpose resin and high specific gravity powder, have high specific gravity, can be used for high-speed net making, and have excellent practical durability.
For composite fibers with a structure of a sheath layer and a core layer, the selected combination of types of sheath layer resin, core layer resin, and high specific gravity powder, as well as their volume ratios, stabilize the properties of the manufactured fiber and the homogeneous fiber. The present invention was developed based on the discovery that this has a subtle influence on the production of fibers and has extremely important meaning in providing practical fibers. The present invention will be explained in detail below.

The present invention is a sheath-core composite fiber comprising a sheath layer made of polyethylene resin and a core layer having a high specific gravity powder dispersed in the resin, wherein the core layer resin (A> is compatible with the sheath layer resin (B)). has solubility,
The resin has a softening point lower than that of the sheath layer resin, and the high specific gravity powder (C) has an average particle size of 10'μ or less, and the above (A)
), (B) and (C), the capacity ratio of the champions satisfies the following formula.

Moreover, the present invention is constructed to satisfy the above formula by using the core layer resin and the sheath layer resin in the above invention containing 2 to 50% by volume and 0 to 20% by volume of rubber elastic material, respectively. include.

Specific physical properties of the high specific gravity, high strength, and durable fiber targeted by the present invention include a specific gravity of 1.5 or more and a tensile strength of 50.
kg/mm2 or more, and the durability is 36 kg/mm2 or more in tensile strength after 100 times of back and forth friction according to the friction test method described below.
Refers to those that hold mm2 or more.

For sheath-core type fibers that maintain such physical properties, the volume ratios of the resin (B) forming the sheath layer, the resin (A) forming the core layer, and the high specific gravity powder (C) play an important role. It is necessary that the relationship in the above formula be satisfied. To do this, first of all, the amount of sheath layer resin (B) should be 6
It is necessary that the content be in the range of 0 to 85% by volume. In other words, the sheath layer resin accounts for almost all of the strength of the fibers, and if its amount is less than 60% by volume, it will be difficult to maintain the strength that can withstand high-speed net making, and the thickness of the sheath layer will be too high. This is not preferable because it is not sufficient and the abrasion resistance is lacking. Preferably it is 65% by volume or more.

On the other hand, if the above amount is 85% by volume or more, it means that the core layer is 15% by volume or less, and for the reason described below, the content of high specific gravity powder in the core layer is limited, so that fibers with a desired specific gravity can be obtained. is not obtained.

The amount ratio of resin (A) and high specific gravity powder (C) in the core layer is A
/C>1.0, preferably A/C>1.0.
C≧1.5. That is, if the resin is not present at a certain volume or more with respect to the high specific gravity powder, a stagnation phenomenon will occur due to phase separation of the powder during melt extrusion spinning, making it impossible to operate the melt spinning stably and making it impossible to produce homogeneous fibers. This is related to the specific gravity or particle size of high specific gravity powder,
In the case of a high specific gravity powder with a specific gravity of 8 to 11 and an average particle size of 10 μm or less, preferably a high specific gravity powder with an average particle size of 6 μm or less and substantially containing no particles of 10 μm or more, the core When the layer resin is used in the same amount as the high specific gravity powder, preferably at least 1.5 times the volume, the core layer mixture will not undergo phase separation and the resulting fiber will be homogeneous.

The sheath layer resin is responsible for the strength of the fiber, and a resin selected from any extrudable thermoplastic synthetic fiber-forming resin that develops high strength through stretching treatment is used. Polyethylene resins are preferred when considered. The polyethylene resin may be high-density polyethylene, medium-density polyethylene, low-density polyethylene, or a mixture thereof, and preferably high-density polyethylene or a mixture mainly thereof. Further, pigments, stabilizers, etc. may be added to the sheath layer as long as the properties of the polyethylene resin are not lost.

On the other hand, it is necessary for the core layer resin to be in a fluid state at the stretching temperature of the polyethylene resin, which is the sheath layer resin, in order to avoid the generation of voids, and its softening point is preferably 20°C or more than the sheath resin, preferably 40°C. ``It must be lower than C.

Moreover, it is natural that the core layer resin is selected to have good compatibility with the sheath layer resin. Such resins include, for example, modified polyethylene, low density polyethylene, ethylene copolymers such as ethylene-vinyl acetate copolymers, ethylene-vinyl acetate copolymers, etc.
Mention may be made of ethyl acrylate copolymers and ethylene-acrylic acid copolymers.

As mentioned above, the composite fiber obtained by selecting two types of resins and the volume ratios of both resins and high specific gravity powder, spinning them into a sheath-core type structure, and then drawing them has high strength and high specific gravity that cannot be achieved outside of these volume ratios. It can be a fiber.

Furthermore, in order to improve the durability of the fibers, it is effective to add an ethylene-α-olefin copolymer elastomer to the core layer and the sheath layer without changing the volume ratio of the three components mentioned above.

The core layer contains 2 to 50% by volume, preferably 3 to 25% by volume,
By adding 0 to 20% by volume, preferably 1 to 10% by volume, of the sheath layer, abrasion resistance is improved and a fishing net with even better practical durability can be obtained.

Here, the ethylene-α-olefin copolymer elastomer refers to at least one α-olefin having 3 to 12 carbon atoms, such as propylene, butene, pentene, hexene, octene, and 4-methyl-1-pentene. It means a product obtained by copolymerizing 7 mol% or less of one type with ethylene and having a density of 0.910 to 0.935 g/cd and a melt index of 0.2 to 10.

High specific gravity powders include various metal oxides such as lead oxide,
Barium oxide, zirconium oxide, various metal powders such as lead, and other inorganic salts such as barium sulfate can be used.

Next, a detailed explanation will be given using examples.

In addition, the measurement of strength and elongation in the examples is based on JIS
Performed in accordance with L 1070, unit: kg/mg
12 and %.

In addition, the friction resistance was measured using the following friction test method at a load of 3.2
kg/mm2, observation of the fiber surface after 100 times of back and forth friction,
It was determined by measuring and tensile strength.

The friction test method uses an apparatus as shown in Fig. 2, in which a fiber locking tool 2 is placed on a vibrating body 1 that reciprocates horizontally, and a metal hexagonal wrench 3 (made of S
CM-3, size 17 mm) was fixed, one end of the subject fiber (length 45 mm) was fixed to the locking tool 2, and a load of 3.2 kg/+nm2 was applied to the other end. A weight was attached, and the vibrating body 1 was reciprocated so that the distance between the locking tool 2 and the center of the hexagonal wrench 3 was 10 cm at the minimum and 22 cm at the maximum.

Example 1 High-density polyethylene (softening point 128°C, M,
I 1.2, Y6111 manufactured by Juyaki Petrochemical Co., Ltd.) and ethylene vinyl acetate copolymer (softening point 30°C, M
, I20, Sumitomo Chemical K 4010) and trilead tetraoxide (
Fibers with a diameter of 250 μm and a sheath material portion having different volume percentages were produced using pellets having different volume percentages with an average particle size of 4 μ and a specific gravity of 9.1>.

The fibers are manufactured using two extruders, and the sheathing is carried out at 250℃.
The core material was extruded at 150°C, the composite yarn was spun from a concentric two-layer nozzle heated to 250°C, water-cooled at 25°C, then stretched 8.5 times in boiling water, and then in a glycerin bath at 125°C. It was stretched 1.3 times. Furthermore, it was rolled up at 124 m/min after being subjected to a 10% relaxation treatment in boiling water.

The physical properties of the obtained fibers are shown in Table 1.

Example 2 Sheath material - high density polyethylene (same as Example 1).

Core material - ethylene/vinyl acetate copolymer (actual example 1)
Core material pellets with different resins/powders are made by appropriately mixing and dispersing trilead tetroxide, barium sulfate, and lead powder in (same as ).

Fibers with a constant volume % of the sheath material and a substantially constant fiber specific gravity were produced in the same manner as in Example 1, and the influence of resin/powder was examined. The results are shown in Table 2.

Example 3 Sheath material - high density polyethylene (softening point 128°C 1M, 1
1.2 Showa Yuka Co., Ltd. Showa Rex F 5012M) Core material - Ethylene/vinyl acetate copolymer (softening point 66°C
, M, I 15 Evaflex P manufactured by Mitsui Polychemicals
1407) 60 volumes (lead in J part (average particle size 6μ)
Pellets made by mixing 40 parts by volume.

Diameters of 150μ with different ratios of sheath material/core material using the above materials
produced fibers.

To manufacture the fibers, two extruders are used to extrude the sheath material at 260°C and the core material at 150°C.The composite yarn is spun from a concentric two-piece nozzle heated to 260°C, and then extruded at 25°C. Cooled in water, then stretched to 98"C57 (9.3 times in water), stretched 1,2 (+V) in a far-infrared heater dry heating lotus, and then
A 5% relaxation treatment was performed in boiling water. The physical properties of the obtained fibers are shown in Table 3.

Table 3 Example 4 Sheath material - High-density polyethylene and Tafmer (trade name: ethylene-α-olefin copolymer elastomer manufactured by Mitsui Petrochemicals, PO180)? IA compound.

Core material - mixture of ethylene vinyl acetate copolymer, Tafmer and trilead tetroxide.

Example 1 by changing the volume ratio of the sheath material and the core material 70/30, the core material 41i (fat/Pb ratio 70/30 constant), and the amount of Tafmer added to the core material.
Manufactured in the same way. The results are shown in Table 4.

In the table, O for friction resistance means that the tensile strength after friction treatment is 40 kg/mm2 or more.

△: 30kg/mm' or more.

×: 30kg/mm2 or less.

In A, there was no peeling between I and I.

B has some delamination.

C has severe peeling between the eyebrows.

Incidentally, the relationship between the specific gravity and tensile strength of each fiber obtained in Examples 1 to 4 is shown in FIG.

[Brief explanation of drawings]

FIG. 1 is a graph showing the relationship between specific gravity and tensile strength of fibers made of resin-high specific gravity powder described in known literature. FIG. 2 is a schematic diagram of the friction test apparatus used in the examples. FIG. 3 shows the relationship between specific gravity and tensile strength for each fiber obtained in Examples 1 to 4. Applicant Kureha Chemical Industry Co., Ltd. Agent Miya 1) Hirotoyo Figure 1 Deposit (c+/cm3) Tokitsuka

Claims (1)

[Scope of Claims] 1) A sheath-core type composite fiber formed of a sheath layer made of a polyethylene resin and a core layer made of a resin containing dispersed high-density powder, the fiber being made of a core layer resin (A ) is a resin that is compatible with the above-mentioned sheath layer resin <B) and has a lower softening point than the sheath layer resin, and the high specific gravity 15) powder (C) has an average particle size of 1
A high-density, high-strength fiber having a particle diameter of 0μ or less and satisfying the relationship of the capacity ratios of (A), (B), and (C). 2) 0 ethylene-α-olefin copolymer elastomer
A sheath-core type composite fiber formed of a sheath layer made of a polyethylene resin containing ~20% by volume and a core layer made of a resin containing dispersed high specific gravity powder, the core layer resin (A)
is an ethylene-α-olefin copolymer silastomer 2~
50% by volume, is compatible with the sheath layer resin (B), and has a lower softening point than the sheath layer resin, and the high specific gravity powder (C) has an average particle size of 10 μm or less. , above (A'
), (B) and (C).