JPH01139806A - Fiber material for molding - Google Patents

Abstract

PURPOSE:To obtain a fiber material for molding, consisting of a polytetrafluoroethylene based fiber composed mainly of tetrafluoroethylene, having a specific elongation and excellent moldability and capable of providing molded products with improved releasability, slipperiness, triboelectrostatic electricity and strain resistance, etc. CONSTITUTION:For example, a mixed liquid of viscose and a polytetrafluoroethylene dispersion is discharged into a coagulation bath and coagulated, washed with water, scoured, alkali-treated and then calcined. A polytetrafluoroethylene based fiber, containing >=90mol%, preferably >=95mol% tetrafluoroethylene, having >=100%, preferably >=200% elongation is obtained. This fiber preferably has >=50 counts per sec small angle X-ray scattering intensity, >=100Angstrom crystallite size perpendicular to (110) plane and <=3 denier single yarn size.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a moldable fiber material made of polytetrafluoroethylene fiber and having excellent moldability.

[Prior art] Polytetrafluoroethylene (hereinafter simply referred to as PTFE)
These fibers are useful in a wide range of fields including industrial materials.

However, no such example has been found for molding fiber materials made of PTFE fibers, such as stampable sheets.

[Problems to be Solved by the Invention] The present invention was achieved by discovering that fibers made of such a PTFE polymer are a material with unexpectedly large elongation.

In other words, we discovered that PTFE fiber has a breaking elongation of 900% after firing, and that this property is maintained even after oxidative aging treatment, and for the first time, we have achieved the development of its use as a fiber material for molding. It is.

According to the present invention, it is possible to provide a molded product with excellent moldability, mold releasability, and ease of sliding.Furthermore, the present invention can provide a molded product with excellent characteristics such as frictional electrostatic voltage resistance and stain resistance. This is what we were able to provide.

This greatly expands the degree of freedom in designing the use of resin moldings and products.

[Means for Solving the Problems] In order to achieve the above object, the present invention has the following configuration. That is, <1) A fiber material for molding, characterized in that it is a polytetrafluoroethylene fiber containing 90 mol% or more of tetrafluoroethylene, and the elongation of the fiber is 100% or more.

(2) The fiber material for molding according to claim (1), wherein the polytetrafluoroethylene fiber constitutes a knitted fabric or a nonwoven fabric.

(3) A fiber material for molding according to claim (1), in which polytetrafluoroethylene fibers are mixed with other fibers.

In the present invention, the PTFE polymer refers to a homopolymer of tetrafluoroethylene or a copolymer in which 90 mol% or more, preferably 95 mol% or more of the total amount is tetrafluoroethylene.

Monomers that can be copolymerized with tetrafluoroethylene include:
Examples include vinyl fluoride compounds such as trifluoroethylene, trifluorochloroethylene, tetrafluoropropylene, and hexafluoropropylene, and vinyl compounds such as propylene, ethylene, isobutylene, styrene, and acrylonitrile, but there is no need to limit them to these.

Among such monomers, vinyl fluoride compounds, especially compounds with a high fluorine content, are preferred from the viewpoint of fiber properties.

PTFE fibers made of such polymers have at least
It has an elongation of 100%, and in short, if it is an undrawn fiber, the elongation is high to a certain extent, and the maximum elongation at break is 90.
Some reach 0%. However, if the degree of elongation is high, it means that it has not been stretched, and the strength decreases accordingly.

Furthermore, in the present invention, the thinner the PTFE fibers are, the wider the range of application and the higher the fiber density, which is preferable.

Such fine denier PTFE fibers have a small-angle X-ray scattering intensity of 100CpS or less, preferably 8Qcps or less, particularly preferably 50C1)S or less when measured by a small-angle X-ray scattering method at 2θ = 1°. Has characteristics. If it exceeds 100 CpS, the fiber becomes brittle, but there is no problem in expanding its uses from the viewpoint of slipperiness. That is, the above-mentioned PTFE fiber having a low small-angle X-ray scattering intensity means that the concentration of microvoids in the polymer crystals constituting the fiber is small and dense.

The characteristics of such fibers include the low small-angle X-ray scattering intensity mentioned above, and the ability of the fibers to be measured by wide-angle X-ray diffraction (counter method) (110
) plane crystal size is 80 or more, preferably 95 Å or more,
Particularly preferably, the thickness is 100 mm or more. That is, the larger the crystal size, the thicker the crystal grows and the higher the strength.

In other words, as a result of the synergistic effect of the small-angle X-ray scattering intensity and the crystal size of the (110) plane, the crystals have grown sufficiently despite the thin fibers, and the fibers have excellent strength and dimensional stability! ! It is intended to provide security.

Small-angle X-ray scattering intensity is measured as follows.

Line up the sample fibers in the fiber axis direction and cut them into 4 cm lengths.
Weighing 60m (weigh 1 liter and measuring it to a depth of 1mm and a width of 2m)
m mold and solidified using a collodion solution to form a prism, which is used as a sample.

The sample is mounted so as to be perpendicular to the X-ray beam, and the scattering intensity at 2θ-1° is measured under the following conditions when a small angle of direction angle O to 3° is scanned.

Measurement method: Small-angle X-ray scattering method (small-angle X-ray diffraction method) X-ray generator: Rigaku Denki RU-200B (rotating anode cathode type) : 40 kV 200 mA Optical system device: Rigaku-Ei camera manufactured by Rigakudeniso Co., Ltd. U slit: width 70μ
m 1 height 1 omm light receiving side: light receiving slit 0.14m
m Vertical restriction slit 15 mm Anti-scattering slit 0.3 mm Vertical anti-scattering slit 6 mm Detector: Scintillation counter The data obtained from this counter is applied to a counting and recording device to draw a chart.

The crystal size of the (110) plane as used in the present invention is measured as follows.

Line up the sample fibers in the fiber axis direction and cut them into 4 cm lengths.
Weigh out 20mg and divide it into 1mm deep and 1mm wide.
The sample is loaded into a mold and solidified using a collodion solution to form a prism.

The obtained sample was mounted perpendicular to the X-ray beam, and the peak band of the (110) plane (approximately 18.3° ) at the position of 1/2 of the maximum value of the intensity distribution (
From the half width) B and the azimuth 2θ, the following 5Cher'r
Calculated using the formula er.

L=λ/ [(B-b)・COSθ] However, K=
1.0°b=0.0105rad.

λ = 1.5418 people.

The peak band of the (110) plane is measured by the following method.

Measurement method: Wide-angle X-ray diffraction method (counter method) X-ray generation bag @: Rigaku Denki RU-200B (rotating anode cathode type)
5kV15mA goniometer; goniometer slit system manufactured by Rigaku Denki Co., Ltd.:
2 mmφ 1°-1° detector; scintillation counter The data obtained from this counter is applied to a counting and recording device to draw a chart.

The PTFE system 11i1 of the present invention has the following fiber properties.

The PTFE fiber material for molding of the present invention may have any single fiber fineness, but from the viewpoint of strength and surface properties, the thinner the fiber is, for example, 10 d or less, preferably 7 d or less, and even 3 d or less, the better.

An example of the method for manufacturing the PTFE-based fiber material for molding of the present invention is shown below. Hereinafter, % in the present invention means % by weight.

That is, for the PTFE fiber referred to in the present invention, the water and chemicals used in each step of the spinning dope, washing, alkali treatment, etc. are all highly purified and contain few impurities (foreign substances). By employing such a system, it was possible for the first time to control single filament breakage and fluffing, and to provide fibers with well-grown crystals and fewer voids.

A mixed solution of viscose and PTFE dispersion is used as the spinning stock solution of the present invention, which is discharged into a coagulation bath, coagulated, and then washed and refined with water. After scouring, the fibers are soaked in alkaline water, squeezed, and then dried or fired as they are to obtain black fibers. This is further stretched if necessary.

Usually, this black fiber is used as the molding fiber material of the present invention. The fiber at this stage usually has a breaking elongation of about 900%. By stretching this fiber, the strength can be increased to a desired level. However, the elongation decreases as the draw ratio increases, so it is preferable to apply an appropriate draw ratio.

Such black fibers are further subjected to oxidative aging treatment in a high temperature atmosphere in a whitening treatment step, if necessary.

This fiber is roughly drawn in one or two stages if necessary.

The smaller the size of the dispersion, the more preferably the average particle diameter is adjusted to 0.6 μm or less. The viscose used is a composition having a degree of polymerization of 200 to 600 and suitably aged.

The PTFE dispersion and viscose are mixed to form a spinning dope. At this time, the PTFE content in the mixed polymer of the spinning dope is 60 to 98%, preferably 70 to 96%.
Although the composition is adjusted within the range of PTFE, the higher the PTFE concentration, the better the fiber properties. That is, the cellulose concentration in the spinning dope is about 5 to 20%.

When 0.5 to 30% of molybdenum disulfide having a particle size of 100 μm or less is mixed into such a stock solution, the fiber splitting properties, strong rigidity, and abrasion resistance are improved.

Such a spinning dope is then spun into an aqueous coagulation bath solution composed of an inorganic mineral acid or/and an inorganic mineral salt. As such an inorganic mineral acid, sulfuric acid is preferable, but nitric acid, hydrochloric acid, phosphoric acid, etc. can also be applied. The content of inorganic mineral acids is 0.1-5
It is 0%.

Such an inorganic mineral salt is added in an amount of about 30% or less.

The spinning stock solution is extruded into the coagulation bath, and is spun and coagulated as a multifilament. The spinning speed at this time is, for example, about 20 to 50 m/min, or even slower.

This coagulated multifilament is heated at 40 to 90℃ as it is.
It is preferably thoroughly refined under warm water at around 80°C. This scouring temperature is also related to the formation of cavities, so it is important to control it accurately.

The multifilament bundle after Argali treatment is 3
It is fired at a temperature of 00 to 450°C, preferably 320 to 400°C. In this case, firing and stretching may be performed separately or simultaneously. Stretching is performed at least 5 to 10 times. In this firing, it is preferable to select conditions that will carbonize the cellulose carbide to 3.0% by weight or less. Because the obtained fiber contains cellulose carbide,
It is brown or black in color.

In this way, 1q of PTFE fiber is heated to roughly 300°C.
above, preferably at 310-340°C, at least 50°C
Whitening is achieved by air oxidation and aging for a period of time, preferably 60 hours or more.

Such fibers, ie, black fibers or white fibers, may be undrawn or drawn, but it is important that the elongation remains at least 100%, preferably 200% or more.

It is of course possible to use 100% of such a fiber material for molding as a material for molding, but it is possible to improve the quality of these fibers by using them in combination with other fibers within a range that does not impede the performance of the present invention. We can provide molded products with additional functions.

For example, ordinary polyamide fibers and polyester fibers, fibers with high initial elastic modulus and fiber strength such as fully aromatic polyamide fibers, polysulfide fibers, and highly oriented synthetic fibers such as polyethylene, polyvinyl alcohol, polyacrylonitrile, etc. High strength fibers drawn at least 8 times are preferably applied.

On the other hand, fibers made of elastic elastomers, such as polyurethane fibers, are preferably used because they have a breaking elongation of 800%, which is similar to the PTFE fibers used in the present invention.

Such PTFE fibers and mixed fibers with black seed fibers are used as molding materials as they are or by being molded into a suitable knitted or woven structure or nonwoven fabric.

Such a fiAl material for molding can be subjected to adhesion improving treatment such as plasma treatment, if necessary.

Examples of resins used in combination with such fiber materials for fiber molding include natural rubber, synthetic rubber (including synthetic resin elastomers), polyamide resins, polyester resins, polyacrylic resins, polyolefin resins, etc. For synthetic rubber or hard resin molded articles, resins having high shear stress, such as polyamide resins, are preferably selected.

Next, the present invention will be explained in more detail with reference to Examples.

[Example] Example 1 PTFE resin dispersed in ion-exchanged water using alkylaryl polyether alcohol as a dispersant
% dispersion and viscose (8.9% cellulose and 5.4% caustic soda, 29% carbon disulfide/cellulose amount, remaining ion exchange water > 100 parts) in a vacuum mixer at 8 °C. and vacuum level 10 To
The mixture was mixed and defoamed at rr for 21 hours to prepare a spinning stock solution.

This spinning dope was introduced in 430 portions into a nozzle having 240 holes of 0.12 mmφ, and 23
It was discharged into a coagulation bath controlled at °C. The coagulation bath used was an aqueous solution prepared by dissolving 7% sulfuric acid and 20% sodium sulfate in ion-exchanged water.

The coagulated fibers were introduced into an ion exchange water tank at 80°C, washed slowly and thoroughly at a speed of about 29 m/min, and squeezed with a mangle to reduce the concentration of caustic soda to 0.05 mol.
/t in an ion-exchange aqueous solution containing 0.32% caustic soda based on the weight of the fiber.

This alkali-containing fiber was then brought into contact with a roll heated to 380°C and fired.

This fired fiber was used to form a fabric with a plain weave structure.

This plain woven fabric was subjected to plasma treatment in a nitrogen atmosphere.

This treated fabric was press-bonded to an ABS-based resin pot holder (push plate) via an epoxy adhesive.

This opening plate had good adhesion and comfortable movement.

(Effects of the Invention) The present invention provides a molding fiber material that can easily produce various molded products based on excellent moldability, and the stampable sheet according to the present invention has excellent moldability. It is possible to provide an excellent resin molded product that has features such as antistatic properties and antifouling properties. By using such a fiber material for molding, we have been able to provide a product that can be fully applied to the field of resin molded products, which has not been used in the past.

Claims (3)

[Claims] (1) A fiber material for molding, characterized in that it is a polytetrafluoroethylene fiber containing 90 mol% or more of tetrafluoroethylene, and the elongation of the fiber is 100% or more. (2) The fiber material for molding according to claim (1), wherein the polytetrafluoroethylene fiber constitutes a knitted fabric or a nonwoven fabric. (3) The fiber material for molding according to claim (1), wherein the polytetrafluoroethylene fiber is mixed with other fibers.