JP2002266158A - Heat-resistant polypropylene fiber, heat-resistant polypropylene multifilament yarn, and method for producing heat-resistant polypropylene fiber - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heat-resistant polypropylene fiber having a combination of high heat-resistant performance with high tenacity and emitting no toxic gas, and to provide a method for producing the above fiber. SOLUTION: This heat-resistant polypropylene fiber is produced by the following process: a resin material 5-25 g/10 min in MFR value based on a highly stereoregular polypropylene resin >=96 mol% in NMR value (mmmm fraction) is melt-spun at a spinning temperature of 210-270 deg.C, the resultant undrawn yarn is drawn by a factor of 2-7 at a temperature of 50-100 deg.C or drawn combinedly with a simultaneous air processing; the heat-resistant propylene fiber thus obtained has a heat resistance temperature of >=150 deg.C; wherein the heat resistance temperature is defined as follows: a loop-shaped sample made by tying both ends of the heat-resistant polypropylene fiber is hooked about a hot pin, a load of 0.49 cN/dtex is applied on the lower end of the sample, the hot pin is then put to temperature rise at a rate of 20 deg.C/min until the sample is melt-fractured; the heat resistance temperature is a temperature at which the sample is melt-fractured.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polypropylene fiber having sufficient strength and high heat resistance and a method for producing the same, and more particularly, to a polypropylene fiber suitably used for forming a carpet such as a carpet for an automobile interior. The present invention relates to a heat-resistant polypropylene fiber obtained and a method for producing the same.

[0002]

2. Description of the Related Art Conventionally, as a polypropylene fiber product having heat resistance, a mixed fiber product composed of a polypropylene fiber and another material is generally used. For example, a mixed fiber product of a polypropylene fiber and a nylon fiber and a mixed fiber product of a polypropylene fiber and a natural fiber are known.

[0003] When discarding used fiber products, it is difficult to separate each fiber in such a mixed fiber product comprising two or more types of fibers, and the separation cost is large. Was the common method of disposal.

[0004] However, in recent years, the recyclability of textile products has been required from the viewpoint of environmental aspects and resource saving, and for that purpose, textile products made of a single resin have been required.
In particular, for carpet applications, there is a need for a fiber product made of a polyolefin resin which is environmentally friendly without generating harmful gas when incinerated and is also suitable for recyclability. Further, among such polyolefin resins, a carpet made of a polypropylene resin having relatively high heat resistance has been demanded from the market.

[0005] By the way, polypropylene fiber has heat resistance,
Since it is excellent in alkali resistance, it has been conventionally used as a reinforcing material for a cement molded product, and enables autoclave curing at a high temperature (about 140 ° C.) for the purpose of improving strength. For example, JP-A-6-219797 discloses that in order to enhance dispersibility in cement and affinity with the cement, a highly crystalline polypropylene resin is used as a core and a polypropylene resin kneaded with fine calcium carbonate powder is used as a sheath. A polypropylene fiber for cement reinforcement having a core-in-sheath structure is disclosed.

[0006] Even with such a polypropylene fiber for reinforcing cement, an increase in the processing temperature is required in order to shorten the processing time of autoclave curing and improve production efficiency. However, there is a problem that when the processing temperature of the autoclave curing increases, the reinforcing effect of the reinforcing fibers decreases.

To solve the problem, Japanese Patent Application Laid-Open No. H10-5910
No. 754 discloses a cement reinforcing polypropylene fiber having a melt flow rate (hereinafter referred to as “MFR”).
Value. " ) Is low polypropylene fiber.
If the MFR value is low, the fiber does not easily flow even at high temperatures, and the shape of the fiber is easily maintained, so that a reduction in the reinforcing effect after curing can be suppressed.

[0008] A high heat-resistant polypropylene fiber for cement reinforcement disclosed in Japanese Patent Application Laid-Open No. 11-61554 is a polypropylene fiber having a specific stereoregularity.
It is obtained by adding a predetermined amount of a nucleating agent for forming a β crystal. As an index of stereoregularity, ranges of an isotactic pentad fraction (hereinafter referred to as “IP fraction”) and an MFR value by 13 C nuclear magnetic resonance spectrum are defined.

The polypropylene fiber for cement reinforcement disclosed in JP-A-11-131319 has a xylene extraction insoluble portion at 25 ° C. from the viewpoint of melting point, heat resistance, heat shrinkage, strength and the like.
The IP fraction, the average isotactic chain length, and the average chain length of each fraction of the xylene-insoluble portion by the column fractionation method are set in predetermined ranges. Further, a nucleating agent is added in a predetermined amount in order to improve the heat resistance and elastic modulus of the fiber.

Japanese Unexamined Patent Application Publication No. 11-181419 discloses that a polypropylene having a specific molecular weight, a specific molecular weight distribution, and an IP fraction and an MFR value which are indicators of specific stereoregularity is added to a Zn-containing nucleating agent, It is disclosed that a polypropylene fiber for cement reinforcement having high heat resistance, cement affinity and antibacterial performance can be obtained from a composition containing a nucleating agent and a divalent metal compound.

Further, Japanese Patent Application Laid-Open No. 2000-144523 discloses a resin composition obtained by blending a saturated fatty acid bisamide compound with a polypropylene having a specific stereoregularity (that is, an IP fraction and an MFR value). It is disclosed that a high melting point polypropylene fiber oriented and crystallized can be obtained.

[0012]

However, since the polyolefin fibers disclosed in these publications are fibers for cement reinforcement, their heat resistance is 180 ° C.
It is sufficient that the fiber form is maintained even after the autoclave curing treatment is performed. Therefore, the heat resistance in each publication merely evaluates whether or not autoclaving at 180 ° C. is possible.

On the other hand, a three-dimensional molding process is generally employed in a carpet for a vehicle.
A backing treatment has been applied. Although high heat resistance is required to prevent the fibers from being melted during the backing treatment, the heat resistance of the polyolefin fibers disclosed in the above-mentioned publication is insufficient.

The present invention has been made in order to solve such a conventional problem, and uses a polypropylene resin which does not generate any harmful substances even when incinerated. It is an object of the present invention to provide a polypropylene fiber excellent in heat resistance, which does not cause a problem such as fusing of a fiber even during a backing treatment, and a method for producing the same.

[0015]

In order to achieve the above object, the invention according to the first aspect of the present invention is to loop a loop-shaped sample connecting both ends of a polypropylene fiber around a heating pin, and to heat the sample. 0.49 cN / dtex at bottom
When the load is applied, the temperature of the heating pin is raised from room temperature at a heating rate of 20 ° C./min. The main component is the characteristic heat-resistant polypropylene fiber.

The polypropylene fiber having a heat-resistant temperature of 150 ° C. or more can sufficiently withstand high-temperature processing such as three-dimensional molding and backing of carpets for vehicles and the like, and the fiber is blown during such processing. There is no problem such as.

The heat-resistant polypropylene fibers of the present invention include, in addition to fibers mainly composed of propylene homopolymer, fusible polypropylene such as copolymers of propylene with other α-olefin monomers such as ethylene and butene-1. It also includes fibers mainly composed of resin.

According to the second aspect of the invention, the raw material resin material of the polypropylene fiber is a mixture of a lactone-based processing heat stabilizer, a phosphorus-based stabilizer, and a phenolic antioxidant. 0-0.5
% By weight.

By containing the above stabilizer in the range of 0 to 0.5% by weight, a greater effect of improving heat resistance can be obtained.
The mixing ratio of the lactone-based processing heat stabilizer, the phosphorus-based stabilizer and the phenolic antioxidant is such that the lactone-based processing heat stabilizer: the phosphorus-based stabilizer: the phenol-based antioxidant is 1
The ratio is preferably 5: 42.5: 42.5.

The present stabilizer has an effect of suppressing an increase in MFR value (a decrease in molecular weight) by capturing radicals in a polymer when the polypropylene resin is in a molten state. In particular, the lactone-based processing heat stabilizer has a function of not only capturing radicals but also regenerating a phenolic antioxidant.

According to the third aspect of the present invention, the raw material resin material for the polypropylene fiber contains less than 0.3% by weight of an ultraviolet absorber as a light stabilizer.

The preferred amount of the ultraviolet absorber is 0.1.
It is in the range of 1 to 0.3% by weight. The ultraviolet absorber can be arbitrarily selected from commonly used ultraviolet absorbers such as benzotriazole, benzophenone, benzoate and cyanoacrylate. Particularly, a benzophenone-based ultraviolet absorber is preferably used.

As a method for mixing a highly regular polypropylene resin with a stabilizer for improving heat resistance and, if necessary, an ultraviolet absorber, a stabilizer for improving heat resistance and an ultraviolet absorber are added to the polypropylene resin immediately before melt spinning. And melt-spinning. Alternatively, in consideration of the dispersibility of a stabilizer for improving heat resistance, a master batch (hereinafter, referred to as “MB”) in which a stabilizer and an ultraviolet absorber are each added in a high concentration to a polypropylene resin in advance is prepared. Then, a method of blending each MB of a stabilizer for improving heat resistance and an ultraviolet absorber to pellets of highly regular polypropylene resin so as to have the required contents described above and melt-spinning is preferable.

The amount of the stabilizer for improving heat resistance and the amount of the ultraviolet absorber added to the MB are preferably 1.5 to 60% by weight. If the amount of the stabilizer or absorbent added to the MB exceeds 60% by weight, it is difficult to prepare a masterbatch, and the MB particle size becomes irregular, which causes a malfunction in the spinning stage.

Further, other additives such as a coloring pigment, a dispersing agent, a fluorescent brightening agent, a matting agent, a lubricant, an antistatic agent and an antibacterial agent may be blended as long as the physical properties of the fiber are not impaired. .

The heat-resistant polypropylene fiber of the present invention may be either a short fiber or a long fiber. The fineness of the heat-resistant polypropylene fiber of the present invention is not particularly limited, and any fineness can be used. The fiber cross-sectional shape of the heat-resistant polypropylene fiber may be an irregular cross-section such as a circular cross-section, a hollow cross-section, or a triangle.

Further, the present invention also has a main structure of a yarn such as a monofilament yarn or a multifilament yarn made of heat-resistant polypropylene filament. The invention according to claim 4 of the present application relates to a heat-resistant polypropylene multifilament yarn comprising the heat-resistant polypropylene fiber according to any one of claims 1 to 3 above. This heat-resistant polypropylene multifilament yarn is particularly preferable because it is excellent in strength when formed into a fabric, denseness of the fabric, and the like.

Further, in order to obtain such heat-resistant polypropylene fibers, the present inventors have studied diligently by focusing on the fact that the lower the MFR value of the raw material resin, the higher the heat resistance of the shaped fibers. went.

As a result, the invention according to claim 5 of the present invention
Mainly a highly stereoregular polypropylene resin having an MR value (mmmm fraction) of 96 mol% or more, and an MFR value of 5
２５25 g / 10 min resin material at a spinning temperature of 210 to 270
And the resulting undrawn yarn is drawn at a draw ratio of 2-7.
The main configuration is a method for producing a heat-resistant polypropylene fiber, which comprises performing drawing or simultaneous drawing air processing at a drawing temperature of 50 to 100 ° C.

In the method for producing a heat-resistant polypropylene fiber of the present invention, first, the raw material resin material of the polypropylene fiber has an NMR value (mmmm fraction) of 96 mol%.
It is characterized in that the above-mentioned highly stereoregular polypropylene resin is mainly used. This NMR value (mmmm fraction) is 9
If it is less than 6 mol%, the melting point is low and the heat resistance is poor.

The raw resin material of the polypropylene fiber is mainly composed of a polypropylene resin and has an MFR value of 5 to 5.
It is also characterized by 25 g / 10 min.

The MFR value is set in consideration of the fiber strength, and is more preferably from 10 to 20 g / 10 minutes. When the MFR value is less than 5 g / 10 minutes, it is necessary to set a high spinning temperature in melt spinning to ensure sufficient spinnability, and a coloring pigment or an ultraviolet absorber added to the polyolefin resin may be used. Inconveniences such as deterioration and coloring or discoloration occur. On the other hand, the MFR value is 25 g / 10
If it is higher than the above value, it is impossible to obtain a heat-resistant polypropylene fiber having the above-mentioned heat-resistant temperature evaluated by the above-mentioned method of 150 ° C. or more.

Further, if the spinning temperature is lower than 210 ° C., even if a polypropylene resin having an MFR value of 25 g / 10 minutes is used, only low-strength fibers can be obtained.
If the temperature is higher than ℃, the coloring pigments and stabilizers added to the polyolefin resin will be altered and colored or discolored.

When the draw ratio is less than 2 times, the strength of the obtained fiber is low and the elongation is high, and when the draw ratio exceeds 7 times, the spinnability deteriorates. On the other hand, if the stretching temperature is lower than 50 ° C., high-magnification stretching cannot be performed, resulting in low fiber strength and poor yarn production stability. On the other hand, when the stretching temperature exceeds 100 ° C., the yarn production stability decreases.

Further, after the stretching, heat setting may be performed, and the heat setting may be performed by either a hot plate method or a hot roller method. If the heat setting temperature is lower than 60 ° C., shrinkage remains in the obtained fiber, and the dimensional stability of the product deteriorates after processing as a product such as an industrial material or a carpet. On the other hand, when the heat setting temperature exceeds 140 ° C., the spinning property is reduced.

In the method of the present invention, the fiber can be formed by a direct spin drawing method in which the melt spun fiber is continuously drawn without winding the melt spun undrawn yarn.

Further, according to the invention of claim 6, the resin material is a mixture of a lactone-based processing heat stabilizer, a phosphorus-based stabilizer and a phenolic antioxidant, and the stabilizer is intended to improve heat resistance. Is contained in an amount of 0 to 0.5%.

Among these mixtures, a lactone-based processing heat stabilizer particularly contributes significantly to the improvement of heat resistance. The mixing ratio of the lactone-based processing heat stabilizer, the phosphorus-based stabilizer, and the phenolic antioxidant in this mixture is not particularly limited.

[0039]

Embodiments of the present invention will be specifically described below with reference to the drawings. FIG. 1 is a diagram showing the heat resistance evaluation method of the present invention. In the present invention, first, a loop-shaped sample 1 connecting both ends of a polypropylene fiber cut to an arbitrary length is prepared. The sample 1 is hung on the heating pin 2 and hung. Then, 0.49 cN was applied to the lower end of sample 1.
A load W of / dtex is applied. In this state, the heating pin 2 is heated from room temperature at a heating rate of 20 ° C./min, and the temperature at which the sample 1 is blown is defined as a heat-resistant temperature.

FIG. 2 is a graph showing the relationship between the amount of the heat-resistant stabilizer added and the heat-resistant temperature of the obtained heat-resistant polypropylene fiber. The stabilizer is a lactone-based processing heat stabilizer (“HP-13” manufactured by Ciba Specialty Chemicals).
6 "), a phosphorus-based stabilizer (" IRGAFOS "from Ciba Specialty Chemicals), and a phenolic antioxidant (" IRGANOX "from Ciba Specialty Chemicals) in a ratio of 15: 42.5: 42.5. . From this graph, it can be seen that the maximum heat resistance was exhibited when the amount of the stabilizer added was 0.3% by weight, and the heat resistance was flat even when the stabilizer was added in an amount of 0.3% by weight or more.

FIG. 3 is a graph showing the relationship between the added amount of the heat resistance improving stabilizer and the MFR value of the raw material resin material. NMR value (mmmm fraction) of 9 as polypropylene resin
For three types of polypropylene resins of 5 mol%, 96 mol%, and 97 mol%, the same resin was used for 20 times.
The resulting polypropylene resin was shaped using a twin screw extruder with a length of 5 mm so that the residence time was 5 minutes, and the MFR value of the obtained polypropylene resin was measured.

Regardless of the NMR value (mmmm fraction), the MFR value was low when 0.3% by weight of the heat resistance improving stabilizer was added, that is, the decrease in molecular weight was small. . In particular, a raw material having an NMR value (fraction of mmmm) of 96 mol% and an MFR value of 11 g / 10 min.
It can be seen that the raw material having an MR value (mmmm fraction) of 97 mol% and an MFR value of 8.3 g / 10 min has a small increase in the MFR value despite setting the extruder temperature high.

Hereinafter, the present invention will be described with reference to specific examples and comparative examples. In addition, the heat resistance and crimp rate of the fiber were evaluated as follows.

<Heat resistance evaluation method> A loop-shaped sample 1 connecting both ends of a polypropylene fiber
Is hooked on the heating pin 2 and hung. A load W of 0.49 cN / dtex on the lower end of the sample 1
multiply. The temperature of the heating pin 2 is raised from room temperature at a heating rate of 20 ° C./min, and the temperature at which the sample 1 melts is defined as a heat-resistant temperature.

<Crimp Ratio> A bunch-shaped sample is prepared by bundling the samples. Heat-treat the sample at 130 ° C. for 10 minutes.・ Leave for at least 10 minutes after heat treatment. Apply a measurement load A to one end of the sample yarn and measure the yarn length (L1) one minute later. Measurement load A = dtex x 1/10 x (2 x number of windings)-Except for measurement load A, leave for 2 minutes. Apply a measurement load B to one end of the sample yarn and measure the yarn length (L2) one minute later. Measurement load B = dtex × 1/10 × (2 × number of windings) Calculation formula: Crimp rate (%) = [(L1−L2) / L1] ×
The value calculated by 100 was taken as the crimp ratio.

Example 1 A benzophenone-based ultraviolet absorber was previously added at 0.1% by weight, and the MFR value was 9 g / 10
And a polypropylene resin having an NMR value (mmmm fraction) of 97 mol% was used as a raw material. Extruder temperature 26
Melting is performed using a melt spinning machine adjusted to 5 ° C. and a spinning head temperature of 260 ° C., shaped by a circular 60-hole spinneret having a hole diameter of 0.8 mm, drawn at a drawing speed of 460 m / min, and subsequently drawn. Magnification 2.61 times, stretching temperature 100
C., and heat-set at a heat-setting temperature of 125.degree. C. and stretch-and-air-process at a hot-air temperature of 185.degree. C. to obtain a crimped polypropylene multifilament yarn. The obtained fiber was in a good crimped state, and its processability was also good. Table 1 shows the physical properties of the obtained crimped yarn and the heat resistance temperature according to the heat resistance evaluation method described above.

[Examples 2 and 3] Except that the MFR value and the NMR value (mmmm fraction) were changed to the polypropylene resin having the values shown in Table 2, and the spinning temperature was changed to the conditions shown in Table 2, Under the same conditions as in Example 1, a polypropylene multifilament crimped yarn was obtained. The obtained fiber was in a good crimped state, and its processability was also good. Table 1 shows the physical properties of the obtained crimped yarn and the heat resistance temperature according to the heat resistance evaluation method described above.

[Examples 4, 5, and 6] A lactone-based processing heat stabilizer (“HP-13” manufactured by Ciba Specialty Chemicals) was added to the polypropylene resin used in Examples 1 to 3.
6)), a phosphorus-based stabilizer ("IRGAFOS" from Ciba Specialty Chemicals), and a phenolic antioxidant ("IRGANOX" from Ciba Specialty Chemicals) in a ratio of 15: 42.5: 42.5 to improve heat resistance. A polypropylene multifilament crimped yarn was obtained under the same conditions as in Examples 1 to 3 except for using a raw material to which 0.3% by weight of the stabilizer was added. The obtained fiber was in a good crimped state, and its processability was also good. Table 1 shows the physical properties of the obtained crimped yarn and the heat resistance temperature according to the heat resistance evaluation method described above.

[Comparative Example 1] The MFR value was 30 g / 10 min.
A polypropylene multifilament crimped under the same conditions as in Example 1 except that the temperature of the extruder was adjusted to 205 ° C and the spinning head temperature was adjusted to 200 ° C, using a general-purpose polypropylene resin having an NMR value (mmmm fraction) of 95 mol% as a raw material. A processed yarn was obtained. The crimped state was the same as that of the example, and the processability was good. Table 1 shows the yarn physical properties and heat resistance temperature of the obtained crimped yarn.

[Comparative Example 2] In the production process of Comparative Example 1, an undrawn yarn was once wound up and hot drawn at a draw ratio of 3.65 to obtain a polypropylene multifilament drawn yarn having high crystallinity. Table 1 shows the yarn physical properties and heat resistance temperature of the obtained fiber. This fiber has increased strength,
The heat resistance was about the same as the fusing temperature of Comparative Example 1.

Comparative Example 3 The raw materials used in Comparative Example 1
A crimped polypropylene multifilament yarn was obtained under the same conditions as in Comparative Example 1, except that the raw material to which the heat resistance improving stabilizer used in Examples 4 to 6 was added in an amount of 0.3% by weight.
The obtained fiber was in a good crimped state, and its processability was also good. Table 1 shows the yarn physical properties and heat resistance temperature of the obtained crimped yarn. High MFR value and NMR value (mm
Even when a general-purpose polypropylene resin having a low mm fraction is used, the addition of a heat resistance improving stabilizer allows the M
Although it is possible to suppress an increase in the FR value, sufficient heat resistance targeted by the present invention was not obtained.

[0052]

[Table 1]

[0053]

[Table 2]

As described above, according to the present invention,
The present invention can provide a polypropylene fiber which is an environmentally friendly material, has sufficient fiber strength for carpet applications having good three-dimensional processability, and has good heat resistance.

[Brief description of the drawings]

FIG. 1 is a schematic view showing a method for evaluating heat resistance of the present invention.

FIG. 2 is a graph showing the relationship between the amount of a heat resistance improving stabilizer added and the heat resistance temperature of the obtained heat resistant polypropylene fiber.

FIG. 3 is a graph showing the relationship between the amount of a heat resistance improving stabilizer added and the MFR value of a resin material.

[Explanation of symbols]

 1 loop-shaped sample 2 heating pin W load

 ────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Akira Igarashi 4-1-1 Ushikawadori, Toyohashi-shi, Aichi F-term (reference) at Toyohashi Works, Mitsubishi Rayon Co., Ltd. 4L035 BB31 BB89 BB91 EE01 EE08 EE20 FF01 HH10 JJ16 JJ17 JJ25 KK05 MC10

Claims (6)

[Claims] 1. A loop-shaped sample connecting both ends of a polypropylene fiber is wrapped around a heating pin, a load of 0.49 cN / dtex is applied to the lower end of the sample, and the heating pin is heated from room temperature to 20 ° C./min. When the temperature was raised at a speed and the temperature at which the sample was blown was taken as the heat-resistant temperature, the heat-resistant temperature was 1
A heat-resistant polypropylene fiber having a temperature of 50 ° C or higher. 2. The raw material resin material for the polypropylene fiber contains a stabilizer for improving heat resistance, which is a mixture of a lactone-based processing heat stabilizer, a phosphorus-based stabilizer, and a phenol-based antioxidant. 2. The heat-resistant polypropylene fiber according to claim 1, which contains 5% by weight. 3. The heat-resistant polypropylene fiber according to claim 1, wherein the raw resin material of the polypropylene fiber contains less than 0.3% by weight of an ultraviolet absorber as a light stabilizer. 4. A heat-resistant polypropylene multifilament yarn comprising the heat-resistant polypropylene fiber according to claim 1. 5. An NMR value (mmmm fraction) of 96 mol.
% Of a high stereoregularity polypropylene resin having a melt flow rate of 5 to 25 g / 10 min at a spinning temperature of 210 to 270 ° C., and the obtained undrawn yarn is drawn at a draw ratio of 2%. ~ 7 times, stretching temperature 50 ~ 100
A method for producing a heat-resistant polypropylene fiber, which comprises performing drawing or air processing at the same time as drawing under the condition of ° C. 6. The resin material contains 0 to 0.5% of a stabilizer for improving heat resistance, which is a mixture of a lactone-based processing heat stabilizer, a phosphorus-based stabilizer and a phenolic antioxidant. The method for producing a heat-resistant polypropylene fiber according to claim 5, wherein