KR101184857B1 - A composite fiber made of polyoxy methylene resins - Google Patents

Abstract

It provides a fiber having a number of excellent properties possessed by a polyoxymethylene resin and at the same time having a high nodule strength retention. The present invention mainly comprises two types of polyoxymethylene copolymers (a) and (b) each containing a specific amount of specific oxymethylene units in a polymer chain composed mainly of repetition of oxymethylene units and having different crystal melting temperatures as cores and shells, respectively. It relates to a composite fiber formed.

Description

Composite fiber made of polyoxymethylene resin {A COMPOSITE FIBER MADE OF POLYOXY METHYLENE RESINS}

The present invention relates to a composite fiber having a core and a shell formed of two specific polyoxymethylene copolymers, and having an excellent nodule strength retention.

Polyoxymethylene resin is a polymer having a polymer skeleton composed mainly of repetitions of oxymethylene units, and is known to have high crystallinity and excellent rigidity, strength, chemical resistance, solvent resistance, and the like. In view of its high crystallization rate and rapid molding cycle, it is widely used in the field of mechanical parts such as automobiles and electric machines as injection molding materials. In addition, polyoxymethylene resins are known to be high-strength and high-elastic bodies by orientation crystallization according to stretching in that they are highly crystalline (eg, "high strength-high modulus fibers", edited by the Polymer Society, Kyoritsu Publishing, p.48 , 1988).

Thus, polyoxymethylene resin is a resin material which has the outstanding various characteristic, and great expectation is used for using this as a material for fibers.

However, polyoxymethylene resins are difficult to process into fibers due to their crystallization properties, and fibers made of polyoxymethylene resins exhibit excellent strength due to orientation crystallization by stretching, but have a small nodule strength, which makes them practical. In order for that to be improved.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above problems and to provide a fiber having not only various excellent properties of the polyoxymethylene resin but also having a high nodule strength retention.

The present inventors earnestly studied in order to achieve the above object, and as a result of producing a fiber made of a polyoxymethylene resin by melt spinning method, a specific polyoxymethylene copolymer having a composite fiber made of a core and a shell and having a different core and a shell, respectively The present invention has been found to be excellent in workability in melt spinning, and the obtained composite fiber has high strength, high elastic modulus and excellent nodule strength.

That is, the present invention includes a oxyalkylene unit represented by the following general formula (1) of 0.1 to 7.5 mol per 100 mol of oxymethylene units in the polymer chain consisting mainly of repetition of oxymethylene units, while melting index (190 ° C, load 2160g) is A core consisting of a polyoxymethylene copolymer (a) which is 1 to 100 g / 10 min, and

A melt index (190 ° C., load 2160 g) of 1 to 100 g / 10 min, including 0.3 to 8 mol of oxyalkylene units represented by the following general formula (1) per 100 mol of oxymethylene units in a polymer chain consisting mainly of repetitions of oxymethylene units: Formed of a shell consisting of a polyoxymethylene copolymer (b),

In addition, when the polyoxymethylene copolymer (a) and the polyoxymethylene copolymer (b) each have a crystal melting temperature of Tma (° C.) and Tmb (° C.), a composite fiber characterized by satisfying the following formula (2) to be.

Where

R ₁ , R ₂ are selected from hydrogen, an alkyl group having 1 to 8 carbon atoms, an organic group having 1 to 8 carbon atoms, a phenyl group, and an organic group having a phenyl group, and R ₁ , R ₂ may be the same or different. ,

m represents the integer of 2-6.

Where

Tma (° C.) is the crystal melting temperature of the polyoxymethylene copolymer (a),

Tmb (° C) is the crystal melting temperature of the polyoxymethylene copolymer (b).

By this invention, the fiber which has the outstanding outstanding characteristic which polyoxymethylene resin has, and has a high nodule strength retention can be obtained, and it becomes possible to obtain fiber aggregates, such as a woven fabric and a nonwoven fabric, with high strength.

Hereinafter, the present invention will be described in detail.

As described above, the composite fiber of the present invention is characterized by consisting of a core and a shell formed of two different kinds of specific polyoxymethylene copolymers. In addition, the definition of the fiber in this invention includes what is called a filament.

In the composite fiber of the present invention, the polyoxymethylene copolymer (a) used as the core portion is 0.1 to 7.5 mol per 100 mol of the oxymethylene unit in the polymer chain consisting mainly of repetition of oxymethylene units, represented by the above formula (1). Melting index (190 degreeC, load 2160g) is 1-100g / 10min, including a lene unit. In this polyoxymethylene copolymer (a) used as the core portion, the ratio of oxyalkylene units represented by the formula (1) is preferably 0.5 to 6 mol per 100 mol of oxymethylene units, particularly preferably 1.0 per 100 mol of oxymethylene units To 5 mol.

In the present invention, it is important to have a specific temperature difference in the crystal melting temperature of the polyoxymethylene copolymer (a) forming the core portion and the polyoxymethylene copolymer (b) forming the shell portion. It is necessary to relatively adjust the amount of the oxyalkylene units introduced into the coalescing (a) and (b). When the proportion of the oxyalkylene units introduced into the polyoxymethylene copolymer (a) is too large in excess of the above range, the crystal melting temperature is lowered to form the crystal melting temperature with the polyoxymethylene copolymer (b) forming the shell portion. It becomes difficult to produce a difference, and there exists a problem that a nodule strength falls. On the other hand, when the proportion of the oxyalkylene unit introduced into the polyoxymethylene copolymer (b) forming the shell portion is made an excessive amount exceeding the range described later, the crystal melting temperature is further lowered and the polyoxymethylene copolymer (a) Although it is possible to generate a difference in crystal melting temperature with, in this case, the core portion and the shell portion are each formed of a polyoxymethylene copolymer having an excessive ratio of oxyalkylene units, and the heat resistance and strength after stretching of the fiber finally obtained are There is a problem of being lowered. On the contrary, when the ratio of the oxyalkylene unit introduced into the polyoxymethylene copolymer (a) is too small than the said range, thermal stability will fall and workability to a fiber will fall.

The polyoxymethylene copolymer (a) preferably has a melt index (MI) of 1.2 to 90 g / 10 minutes, particularly preferably 1.5 to 80 g / 10 minutes. In the polyoxymethylene copolymer (a) having a too low melt index (MI), since the melt viscosity becomes too high, the load during spinning increases and extrusion becomes difficult. When the melt index MI becomes excessive, filament production becomes unstable due to draw down of the resin and the like, and the strength of the filament also decreases as the molecular weight decreases. Meanwhile, the melt index (MI) of the polyoxymethylene copolymer used in the present invention is measured under a load of 190 ° C. and 2160 g according to ASTM D-1238, which is the same below.

Next, in the composite fiber of the present invention, the polyoxymethylene copolymer (b) used in the shell portion is 0.3 to 8 mol per 100 mol of the oxymethylene unit in the polymer chain composed mainly of repetition of the oxymethylene unit, represented by the oxyalkyl represented by the above formula (1). Melting index (190 degreeC, load 2160g) is 1-100g / 10min, including a lene unit. In this polyoxymethylene copolymer (b) for use in the shell portion, the ratio of oxyalkylene units represented by the formula (1) is preferably 1.1 to 7.1 mol per 100 mol of oxymethylene units, particularly preferably per 100 mol of oxymethylene units 1.6 to 5.6 mol.

When the proportion of the oxyalkylene units of the polyoxymethylene copolymer (b) constituting the shell portion is too small, the crystal melting temperature becomes high, and the ratio of the oxyalkylene units of the polyoxymethylene copolymer (a) forming the core portion Even if it is adjusted, it is very difficult to adjust the crystal melting temperature of the core portion and the shell portion to a desired temperature difference range, and thus, there is a problem that excellent nodule strength, which is an effect of the present invention, cannot be obtained. Moreover, the polyoxymethylene air which comprises a shell part is prepared by adjusting the ratio of the oxyalkylene unit of the polyoxymethylene copolymer (a) which forms a core part to a very small amount exceeding the said range, and forming a shell part further. Although the desired crystal melting temperature difference with the copolymer (b) can be achieved, in this case, both the core portion and the shell portion are formed of a polyoxymethylene copolymer having an insufficient ratio of oxyalkylene units, and thus thermal stability, radioactivity, and stretchability. There is a problem that this is not only impaired and impairs the workability, but also the desired physical properties cannot be obtained. On the contrary, when there are too many ratios of the oxyalkylene unit introduce | transduced into a polyoxymethylene copolymer (b), there exists a problem that the heat resistance of the finally obtained fiber and the strength after extending | stretching become low.

The melt index (MI) of the polyoxymethylene copolymer (b) is preferably 1.2 to 90 g / 10 minutes, particularly preferably 1.5 to 80 g / 10 minutes. The behavior in the case where the melt index MI of the polyoxymethylene copolymer (b) is too small and the behavior in the excessive case are the same as in the case of the polyoxymethylene copolymer (a).

In the composite fiber of the present invention, the polyoxymethylene copolymer (a) constituting the core portion and the polyoxymethylene copolymer (b) constituting the shell portion each have a crystal melting temperature of Tma (占 폚) and Tmb (占 폚). When doing so, it is necessary to satisfy the following equation (1).

Equation 1

Where

Tma (° C.) is the crystal melting temperature of the polyoxymethylene copolymer (a),

Tmb (° C) is the crystal melting temperature of the polyoxymethylene copolymer (b).

Here, the crystal melting temperature is a temperature measured as the peak temperature of the crystal melting peak when the temperature is raised to 10 ° C / min by DSC.

The crystal melting temperature of such a polyoxymethylene copolymer can be adjusted according to the ratio of the oxyalkylene unit represented by the said Formula (1) which comprises the said copolymer, Specifically, the poly obtained by increasing the ratio of an oxyalkylene unit The crystal melting temperature of the oxymethylene copolymer can be reduced. Based on this behavior, by specifically adjusting the ratio of the oxyalkylene unit of the polyoxymethylene copolymer (a) which forms a core part, and the polyoxymethylene copolymer (b) which forms a shell part within the range mentioned above, specifically, Relationship between the crystal melting temperature represented by the formula (1) by making the ratio of the oxyalkylene units of the polyoxymethylene copolymer (b) appropriately increased than the ratio of the oxyalkylene units of the polyoxymethylene copolymer (a) Can satisfy.

Thus, by using the polyoxymethylene copolymer (a) and the polyoxymethylene copolymer (b) which adjusted the crystal melting temperature by changing the ratio of the oxyalkylene unit, it inclines to the high-dimensional structure of the molecular orientation state of a core part and a shell part ( (I) a composite fiber, and in particular, the elongation of the nodule can be increased as the properties of the polyoxymethylene copolymer (b) forming the shell portion are adjusted, and as a result, as a ratio of the nodular strength to the original strength. The calculated nodule strength retention is high. In the composite fiber which consists of a polyoxymethylene copolymer (a) and a polyoxymethylene copolymer (b) whose relationship of crystal melting temperature does not satisfy | fill Formula (1), high nodule strength retention is hard to be obtained. From this viewpoint, more preferable composite fiber consists of a polyoxymethylene copolymer (a) and a polyoxymethylene copolymer (b) whose crystal melting temperature satisfy | fills following formula (2).

The method for producing the polyoxymethylene copolymers (a) and (b) as used in the present invention is not particularly limited. Generally, cyclic ether compounds or cyclic formal compounds which are trioxane and comonomers are mainly used. It can obtain by the method of bulk polymerization using a cation polymerization catalyst. As a polymerization apparatus, all well-known apparatuses, such as a batch type and a continuous type, can be used. Here, the introduction ratio of the oxyalkylene unit represented by the above formula (1) is determined by the amount of comonomer to be copolymerized, and the melt index (MI) is determined by the addition amount of a chain transfer agent, such as methylal, used in the polymerization. I can adjust it.

Examples of the cyclic ether compound or cyclic formal compound used as the comonomer include ethylene oxide, propylene oxide, butylene oxide, oxetane, tetrahydrofuran, trioxephane, 1,3-dioxolane, propylene glycol formal and di Ethylene glycol formal, triethylene glycol formal, 1,4-butanediol formal, 1,5-pentanediol formal, 1,6-hexanediol formal, and the like. Ethylene oxide, 1,3-dioxolane, diethylene glycol formal, and 1,4-butanediol formal are preferable. Moreover, as an oxyalkylene unit represented by General formula (1) formed by superposition | polymerization of comonomer, oxyethylene, oxytrimethylene, and oxytetramethylene are preferable. In addition, the polyoxymethylene copolymer used for this invention may introduce | transduce a branched structure or a crosslinked structure by copolymerizing a branch formation component and a polyfunctional component. In addition, in the polyoxymethylene copolymers (a) and (b) used in the present invention, the comonomers used for the preparation thereof may be the same or different, and are represented by the above-described formula (1) formed as a result of the polymerization. The alkylene units may be the same or different.

In the polyoxymethylene copolymers (a) and (b) used in the present invention, the oxyalkylene units represented by the formula (1) formed by such comonomers are extremely uniform in the molecular chain of the polyoxymethylene copolymer. It is preferable to disperse it, and it is preferable that the ratio of two or more oxyalkylene units represented by the said Formula (1) is chained is 5 mol% or less of the whole oxyalkylene unit.

The polyoxymethylene copolymer obtained by the polymerization is subjected to deactivation of the catalyst, removal of unreacted monomers, washing of the polymer, drying, stabilization of the unstable ends, and the like, followed by stabilization by the combination of various stabilizers. It is provided for practical use. Typical stabilizers include hindered phenolic compounds, nitrogen-containing compounds, hydroxides of alkali or alkaline earth metals, inorganic salts, carboxylates and the like.

In addition, polyoxymethylene copolymer used in the present invention, if necessary, common additives for thermoplastic resins, such as colorants such as dyes, pigments, lubricants, nucleating agents, mold release agents, antistatic agents, surfactants, or organic polymer materials One or two or more kinds of fillers such as inorganic or organic filamentary, plate and granular fillers can be added within a range not impairing the object of the present invention.

Next, the manufacturing method of the composite fiber of this invention which consists of the above polyoxymethylene copolymers (a) and (b) is demonstrated.

The composite fiber of the present invention is plasticized separately using two types of polyoxymethylene copolymers (a) and (b) described above by two extruders and the like, and the polyoxymethylene copolymer (a ) Can be obtained by melt spinning the polyoxymethylene copolymer (b) to be a shell part. The configuration of the melt spinning apparatus used herein is not particularly limited, and, for example, a spinning apparatus composed of two single-axis or twin-screw extruders, a gear pump, a ejection nozzle for composite spinning, and a molten polymer ejected from the ejection nozzle are fibers. It can take out in a shape, and can comprise with a roller for winding this up.

The polyoxymethylene copolymers (a) and (b) which are raw materials are melt | dissolved in such a melt spinning apparatus, are discharged in the form of fibers from a discharge nozzle, are taken out, and are wound up by the roller.

At this time, it is preferable to take out the fibrous material discharged from the discharge nozzle while heating at an ambient temperature of 140 to 250 ° C. If the atmospheric temperature to be heated is less than 140 ° C., the rate of solidification of the fibers is high, the productivity is lowered, and it is difficult to obtain fibers capable of stretching at a high draw ratio, and it is difficult to obtain fibers of high strength and high elastic modulus. On the other hand, if the ambient temperature is 250 ° C or higher, the fibers are wound around the rollers without being sufficiently solidified, resulting in poor operability. The ambient temperature for heating the fibrous material discharged from the discharge nozzle is preferably 140 to 220 ° C.

In the composite fiber of the present invention, a circular shape is generally used as the cross-sectional shape of the core portion, but other shapes such as star shape and polygonal shape can be used. Although the cross sectional area ratio of the core portion and the shell portion is not particularly limited, since the strength of the composite fiber tends to depend largely on the strength of the core portion, the cross sectional area ratio of the core portion in the total cross sectional area of the fiber is preferably 30% or more, more preferably. More than 70%.

The fibers obtained in the spinning process can be further sent to the stretching process to stretch continuously or discontinuously. A draw ratio can be adjusted by setting the speed ratio of a unwinding roll and a winding roll suitably, and the fiber of a desired draw ratio can be obtained. The heating method at this time can use a method such as a heating gas, a heating liquid, hot plate contact, far-infrared heating, laser light heating, electromagnetic induction heating, and the like, and is not particularly limited.

In this invention, it is preferable to extend | stretch at the temperature of the glass transition point of a polyoxymethylene copolymer (a) or more and below the crystal melting temperature of a polyoxymethylene copolymer (b). As a temperature at the time of extending | stretching, especially preferable is the range of (crystal melting temperature of a polyoxymethylene copolymer (a)-50 degreeC)-(crystal melting temperature of a polyoxymethylene copolymer (b)-5 degreeC).

When extending | stretching in the under heating state, extending | stretching stress becomes large and productivity falls, and single yarn also becomes easy to generate | occur | produce. In addition, in the overheated state, the polymer is in a molten state or in a state close thereto, which is not preferable because the melt tension is lowered and monolithic.

에 사용하는 등으로 고강도가 필요한 경우에는 8배 내지 20배 정도 의 고연신 배율로 연신하는 것이 바람직하다.In addition, it is preferable to set draw ratio suitably according to a use within the said range. In the setting of the draw ratio, the strength of the stretched body obtained as the draw ratio increases, on the contrary, the elongation is lowered, indicating a decrease in practical properties such as toughness and nodular elongation, and the fiber itself being easily fibrillated. In consideration of the general property balance, for example, a draw ratio of about 5 to 10 times and a warp of a woven fabric

When high strength is required, for example, when used at, it is preferable to stretch at a high draw ratio of about 8 to 20 times.

The fiber obtained by the stretching treatment in the stretching step is preferably subjected to a heat setting treatment for fixing the molecular state in a heated state, thereby reducing the dimensional change of the stretched body. As an example of heat setting conditions, heat setting at the temperature below (crystal melting temperature of a polyoxymethylene copolymer (a)-30 degreeC) is mentioned.

The composite fiber composed of two kinds of polyoxymethylene copolymers of the present invention has various uses utilizing excellent properties such as nodule strength retention, high strength, high elastic modulus, solvent resistance, heat resistance, flex fatigue resistance, and the like. It can be used for various industrial materials, such as civil engineering and construction, by processing the filament into the form of twisted yarn, woven fabric, and knitted fabric.

In addition, it is also possible to cut the fibers appropriately according to the purpose and use them as short fibers, taking advantage of excellent properties such as high strength, high elastic modulus, solvent resistance, heat resistance, fatigue resistance, alkali resistance, high temperature rigidity, and the like. It can be used for reinforcement of concrete, mortar, synthetic resin, gypsum), processing to non-woven fabrics, and other various purposes.

<Examples>

Hereinafter, although an Example demonstrates this invention further more concretely, this invention is not limited to this.

Examples 1 to 8

The polyoxymethylene copolymer (a) and the polyoxymethylene copolymer (b) were produced by the method described below. A jacket is attached to the outside and a paddle is attached using a continuous mixing reactor composed of a barrel having a shape in which two circles partially overlap the cross section and a rotating shaft with paddles. Cyclic ether or cyclic formal (1,3-dioxolane, 1,4-butanediol formal, diethylene glycol formal) as liquid trioxane and comonomer In addition, the mass polymerization was carried out while continuously supplying methylal as the molecular weight regulator and 50 ppm of boron trifluoride (at the same time with respect to all monomers) as the catalyst to the polymerization reactor, and the amount of the comonomer units shown in Table 1 (oxyalkylene, respectively). A polymer of a unit ratio) was prepared. The reaction product discharged from the polymerizer was quickly added to an aqueous solution at 60 ° C. containing 0.05% by weight of triethylamine while passing through the crusher to deactivate the catalyst. In addition, a crude polyoxymethylene copolymer was obtained after separation, washing and drying.

Subsequently, 4 parts by weight of a 5% by weight aqueous solution of triethylamine was added to 100 parts by weight of the crude polyoxymethylene copolymer, pentaerythritol-tetrakis [3- (3,5-di-tert-butyl-4 -Hydroxyphenyl) propionate] was added and melt kneaded at 210 ° C. with a twin screw extruder to remove the unstable portion.

0.03 weight of pentaerythryl-tetrakis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate] as a stabilizer in 100 weight part of polyoxymethylene copolymers obtained by the above method. Part and 0.15 parts by weight of melamine were added and melt kneaded at 210 ° C. with a twin screw extruder to obtain a pellet-shaped resin composition having a polyoxymethylene copolymer as a base resin.

The two polyoxymethylene copolymers (a) and (b) obtained above were fed to separate 25 mm single screw extruders and plasticized at a cylinder set temperature of 200 ° C. Melted and supplied to a concentric circular core shell composite die having a diameter of 0.5 mm, 24 holes, and a circular hole so that the polyoxymethylene copolymer (a) is the core and the polyoxymethylene copolymer (b) is the shell, and continuously from the composite die. And wound up at a take-up roll speed of 300 m / min. The ratio of the cross-sectional area of the core to the filament cross-sectional area was 72%. Next, the extending | stretching board heated at (crystal melting temperature of a polyoxymethylene copolymer (b)-10 degreeC) was continuously contacted, and it extended | stretched in the longitudinal direction. The draw ratio was performed by adjusting the roll winding speed ratio, and specifically, 6.2-fold stretching was performed by controlling the unwinding roller speed to 46 m / min and the winding roller speed to 285 m / min.

Comparative Examples 1 to 9

The composite yarn outside the stipulation of this invention was produced, the undrawn yarn was prepared on the conditions similar to an Example, and the drawn yarn was further prepared. The evaluation results in the same manner as in Example are shown in Table 1.

In addition, the evaluation item, the measuring method, evaluation criteria, etc. in an Example and a comparative example are as follows.

[Measuring Melt Index (MI)]

According to ASTM D-1238 it was measured under a load of 2160g at 190 ℃.

[Polymer Composition Analysis]

The polymer used for physical property evaluation was dissolved in hexafluoroisopropanol d2, and ¹ H-NMR measurement was performed. Quantification was made from the peak areas corresponding to each unit.

[Crystal Melting Temperature]

It measured as the peak temperature of the crystal melting peak when heated up at 10 degree-C / min by DSC.

[Knot strength]

The nodule strength in filament single yarn was evaluated in accordance with JIS L1013, and the nodule strength retention ratio, which is the ratio of the nodule strength to the filament strength, was calculated.

According to the present invention, two types of polyoxymethylene copolymers (a) and (b) each containing a specific amount of a specific oxymethylene unit in a polymer chain composed mainly of repetition of oxymethylene units and having different crystal melting temperatures are respectively used as core and Composite fibers formed from shells have excellent properties and at the same time have a high nodule strength retention.

Claims (2)

The melt index (190 ° C., load 2160 g) is 1 to 100 g / 10, while including 0.1 to 7.5 mol of oxyalkylene units represented by the following formula (1) per 100 mol of oxymethylene units in the polymer chain including oxymethylene repeating units: A core consisting of a polyoxymethylene copolymer (a) which is a powder, and In the polymer chain containing an oxymethylene repeating unit, a poly-containing polymer containing 0.3 to 8 mol of oxyalkylene units represented by the following general formula (1) per 100 mol of oxymethylene units, and having a melt index (190 ° C., load of 2160 g) of 1 to 100 g / 10 min. Formed of a shell consisting of an oxymethylene copolymer (b), In addition, the polyoxymethylene copolymer (a) and the polyoxymethylene copolymer (b) satisfy the following formula 1 'when the crystal melting temperatures are Tma (° C) and Tmb (° C), respectively. Composite fiber. Formula 1

Where R ₁ , R ₂ are selected from hydrogen, an alkyl group having 1 to 8 carbon atoms, an organic group having 1 to 8 carbon atoms, a phenyl group, and an organic group having a phenyl group, and R ₁ , R ₂ may be the same or different. , m represents the integer of 2-6. Equation 1 '

Where Tma (° C.) is the crystal melting temperature of the polyoxymethylene copolymer (a), Tmb (° C) is the crystal melting temperature of the polyoxymethylene copolymer (b). The method of claim 1, The composite fiber in which the oxyalkylene unit represented by General formula (1) is 1 type, or 2 or more types chosen from oxyethylene, oxytrimethylene, and oxytetramethylene.