KR950013728B1 - Molecularly oriented, silane-cross linked ultra-high-molecular-weight polyethylene molded articla and process for preparation thereof - Google Patents

Abstract

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Description

Molecular orientation and silane crosslinking Ultra high molecular weight polyethylene molded article and its preparation

1 is a graph showing the melting characteristic curve of the raw material ultra high molecular weight polyethylene.

2 is a graph showing a melting characteristic curve of stretched filaments of ultra high molecular weight polyethylene of FIG.

3 is a graph showing a melting characteristic curve of stretched filaments subjected to silane graft on the ultra high molecular weight polyethylene of FIG.

4 is a graph showing a melting characteristic curve of crosslinked filaments after silane graft and stretching of the ultrahigh molecular weight polyethylene of FIG.

5 is a graph showing the melting characteristic curve when the sample of FIG. 4 is subjected to the second temperature measurement.

6 is a graph showing the crystallization characteristic curve when the sample of FIG. 4 is subjected to the first temperature measurement.

7 is a graph showing the relationship between the investment length and the pulling force in the adhesion test for Sample 1 and Sample 2 of Example 1. FIG.

8 and 9 are graphs showing the measurement results of creep characteristics for Sample 2 of Comparative Example of Example 1 (Fig. 8 shows a load of 500 MPa, and Fig. 9 shows a 30% load of breaking load measured at room temperature. to be.)

10 is a polarization micrograph showing the presence of a crystal structure at 200 ° C with respect to the molecular orientation and silane crosslinked high molecular weight polyethylene filament of the present invention (Example 1).

11 is a polarized light micrograph showing the presence of a crystal structure at 150 ℃ in the ultra high molecular weight polyethylene filament of Comparative Example 1.

12 is a graph showing melting characteristic curves of molecular orientation and silane crosslinked polyethylene filaments of Comparative Example 2. FIG.

13 is a graph showing the melting characteristic curves of molecular orientation and silane crosslinked ultrahigh molecular weight polyethylene filaments of Example 2. FIG.

14 is a graph showing a melting characteristic curve of molecular orientation and silane crosslinked ultrahigh molecular weight polyethylene filament of Example 3. FIG.

15 is a graph showing melting characteristic curves of molecular orientation and silane crosslinked ultrahigh molecular weight polyethylene filaments of Example 4. FIG.

16 is a graph showing the melting characteristic curves of molecular orientation and silane crosslinked ultrahigh molecular weight polyethylene filaments of Example 5. FIG.

17 is a graph showing melting characteristic curves of molecular orientation and silane crosslinked polyethylene filaments of Comparative Example 6. FIG.

18 is a graph showing the crystallization characteristic curve of the sample of FIG. 17. FIG.

19 is a graph showing a melting characteristic curve when a second temperature rise measurement of the sample of FIG. 17 is performed.

The present invention relates to a molecular orientation and a silinic crosslinked ultra high molecular weight polyethylene molded article and a method for manufacturing the same, and more particularly, has high elastic modulus and high tensile strength unique to stretch molded articles of ultra high molecular weight polyethylene, and at the same time improves heat resistance and adhesion significantly. A molded article and its manufacturing method are related.

It is already known to form a molecularly oriented molded article having a high modulus of elasticity and high tensile strength by molding ultra high molecular weight polyethylene with a fiber tape or the like. For example, Japanese Patent Laid-Open No. 56-15408 discloses stretching a filament obtained by spinning a dilute solution of ultra high molecular weight polyethylene. Further, Japanese Patent Application Laid-Open No. 59-130313 describes melt-kneading ultra high molecular weight polyethylene and wax, extruding and kneading the kneaded product, followed by cooling and stretching. It is described to draw an extrudate after it has cooled and solidified.

On the other hand, silane crosslinking is already known for the purpose of imparting heat resistance to polyolefins. For example, Japanese Unexamined Patent Publication No. 48-1711 discloses crosslinking by grafting a silane compound in polyethylene in the presence of a radical generator and then immersing in water in the presence of a silanol catalyst. Further, Japanese Patent Application Laid-Open No. 54-11154 describes immersion of a silane graft polyolefin molded product into a mixture of a silanol condensation catalyst and a solvent to speed up the crosslinking treatment, and Japanese Patent Application Laid-Open No. 52-154872 describes the orientation of silane graft polyolefin. It is described to extract water after crosslinking.

However, stretched molded articles of ultra high molecular weight polyethylene, such as fibers and tapes, have high elastic modulus, high tensile strength, light weight, and excellent water resistance and weather resistance, but have the inherent disadvantages of polyethylene, that is, poor heat resistance and adhesion. I have it.

In addition, in the conventional silane crosslinking technique of polyethylene, a stretched article having high elastic modulus and high tensile strength is not obtained, and the effect of improving heat resistance is also insufficient.

In general, it is known that the heat resistance of polyolefins is improved by molecular orientation of polyethylene or by crosslinking of polyethylene. However, there is a limit to improvement of heat resistance in the prior art. As a reason, the disadvantage that the melting point of polyethylene is in a relatively low range of 110-140 ° C. cannot be overcome in recent years, and as far as the inventors know, after exposing the molded article of polyethylene to a temperature of 180 ° C. for 10 minutes, For everything melts and loses its strength.

Accordingly, an object of the present invention is to provide an ultra high molecular weight polyethylene molecular orientation molded article which is remarkably improved in heat resistance, adhesion and creep resistance.

Another object of the present invention is to maintain the shape of the stretched molded article without melting even when exposed for 10 minutes at a temperature of 180 ℃ as well as molecular orientation and silane crosslinked having a heat resistance that can maintain a high strength retention even after the thermal history An ultra high molecular weight polyethylene molded body is provided.

It is another object of the present invention to provide a silane crosslinked ultra high molecular weight polyethylene molded article having heat resistance, adhesiveness and creep resistance suitable for use as a reinforcing fiber of a resin composite material, and a method of manufacturing the same.

The present inventors have extruded after grafting a silane compound in the presence of an ultra high molecular weight polyethylene radical initiator having an intrinsic viscosity (η) of 5dl / g or more, and then, after stretching or extruding the silanol condensation catalyst during stretching. When exposed to moisture and crosslinked, it is possible to see a directional phenomenon of melting temperature which is not seen at all in the stretched or crosslinked molded products of the conventional polyethylene. Thus, a novel molecular orientation molded product can be obtained. It was found that even when exposed to temperature for 10 minutes, the shape of the stretched molded body was maintained without melting, and the high strength preservation rate could be maintained even after the thermal history. In this stretched molded article, it was found that the ultra-high molecular weight polyethylene stretched molded article retains high elastic modulus and high tensile strength, and also significantly improves adhesion and creep resistance.

That is, according to the present invention, as a molded article of molecular orientation and silane crosslinked ultra high molecular weight polyethylene, the isomer is an original crystal melting temperature of the ultrahigh molecular weight polyethylene which is obtained as the main melting peak at the second elevated temperature when measured by a differential scanning calorimeter in a restrained state. It has at least two crystal melting peaks (Tp) at a temperature of at least 10 ° C higher than (Tm), and the amount of heat of fusion due to this crystal melting peak (Tp) per mol of melting is 50% or more and the temperature range (Tm + 35 ° C). -A compact is provided in which the total amount of heat of fusion resulting from the high temperature side melting peak (Tp1) at (Tm + 120 ° C) is not less than 5% of the heat melting temperature.

In addition, according to the present invention, a composition of an ultra high molecular weight polyethylene having an extreme viscosity (η) of 5dl / g or more of ultra high molecular weight polyethylene, a silane compound, a radical initiator and a diluent is thermoformed and silane compound is grafted, Or there is provided a method for producing a molecular orientation and silane crosslinked ultra high molecular weight polyethylene molded body, characterized in that after the stretching, the fused condensation catalyst in the stretched molded product of the molding, and then the stretched molded body is brought into contact with water to crosslink.

The present invention surprisingly found that the melting point of at least a part of the polymer rings constituting the stretched crosslinked molded article under the constraint condition is obtained by molding grafted silanes into ultra high molecular weight polyethylene, stretching the molded article and then performing silane crosslinking. It is due to.

The melting point of the polymer depends on the melting of the crystals in the polymer and is generally measured as the endothermic peak temperature due to the melting of the crystals in a differential scanning calorimeter. The endothermic peak temperature is constant when the type of polymer is determined, and it hardly varies by post-treatment such as stretching or crosslinking. Even if it is fluctuating, even the stretch heat treatment, which is well known as the case of fluctuation, only moves to the high temperature side at about 15 ° C.

In the accompanying drawings, FIGS. 1 to 4 show the raw material ultra high molecular weight polyethylene (FIG. 1), the stretched filament of the polyethylene (FIG. 2), and the unstretched filament (FIG. 3) subjected to silane crosslinking to the polyethylene, and the silane graph according to the present invention. The endothermic curve measured by the differential scanning calorimetry measured under constraint conditions for each of the filaments subjected to crosslinking treatment after drawing ultra high molecular weight polyethylene (FIG. 4). In addition, processing conditions are demonstrated in the Example mentioned later.

From these results, when the ultra high molecular weight polyethylene is a simple stretched or silane crosslinked material, it shows an endothermic peak due to crystal melting at about 135 ° C, which is almost the same as that of the untreated ultra high molecular weight polyethylene, and in the silane crosslinked product, the peak area (heat of fusion) is not treated. In the stretch-cross-linked molded article according to the present invention, the small peak remains at the melting peak temperature of the untreated ultra high molecular weight polyethylene, but the large peak is moved to the relatively high temperature side. Can be.

FIG. 5 shows an endothermic curve in the second run of the sample in FIG. 4 (second temperature measurement after the measurement in FIG. 4 is performed). From the results of FIG. 5, it can be seen that in the case of reheating, the main peak of the fusion is almost the same as the fusion peak temperature of the untreated ultra high molecular weight polyethylene. In the measurement of FIG. 5, the molecular orientation in the sample is almost lost. From this, it can be seen that the movement of the endothermic peak to the high temperature side in the sample of FIG. 4 is closely related to the molecular orientation in the molded body.

In the present invention, the fact that the crystal melting temperature of at least a part of the polymer rings constituting the molded body is moved to the high temperature side by stretching and silane crosslinking of ultra high molecular weight polyethylene has not been known as a means for raising the crystal melting temperature. It was a new discovery.

The reason why the crystal melting temperature moves to the high temperature side in the orientation crosslinked molded article of the present invention is not yet fully understood, but the present inventors estimate the reason as follows.

In other words, when silane kraft ultrahigh molecular weight polyethylene is applied to the stretched piece, the silane graft portion is selectively made into an amorphous portion, and an orientation crystal portion is formed through the amorphous portion. Subsequently, when the stretched product is crosslinked in the presence of a silanol condensation catalyst, a crosslinked structure is selectively formed in the amorphous portion, resulting in a structure in which both ends of the alignment crystal portion are corrected by silane crosslinking. In a typical stretched molded article, crystal melting proceeds in the amorphous portions at both ends of the oriented crystal parts, whereas in the stretched crosslinked molded article of the present invention, non-condensed parts are selectively crosslinked at both ends of the oriented crystal parts, so that the polymer ring is hard to move. It is thought that negative melting temperature is improved. This structure can be characterized as follows again by observation with a differential scanning calorimeter. FIG. 6 shows an exothermic curve at the time of crystallization measured using the heating process for moving to the second run, that is, the measurement at the elevated temperature shown in FIG. Here, a shoulder or broad sub peak is observed on the high temperature side of the main heating peak. In addition, the shoulder is observed on the high temperature side of the Tm peak also in the second run at the second elevated temperature (FIG. 5). Normally, one row of sharp exothermic peaks is observed during cooling in the molten state in polyethylene, and no shoulders or peaks are observed on the hot side of the pitch. Moreover, even in normal crosslinked polyethylene, although a peak may broaden, similarly, a shoulder or a heat generating peak is not observed on the high temperature side. Even in the second run, the endothermic shoulder and the peak are observed on the high temperature side of Tm in all of ordinary polyethylene and crosslinked polyethylene. After all, it is considered that this enumeration copper is a trace of a novel orientation crosslinking structure and is related to excellent heat resistance and creep resistance.

Therefore, the molded article according to the present invention is safely maintained in shape even at a high temperature of 160 ° C., and high strength preservation ratio is maintained even after such a thermal history.

The present invention will be described in detail below in order of a raw material, a processing means, and a target object in order to facilitate understanding thereof.

[Raw material]

The ultrahigh molecular weight polyethylene used in the method of this invention is an intrinsic viscosity (eta) in 135 degreeC in a decalin solvent, 5dl / g or more, Preferably it is the range of 7-30dl / g. If the intrinsic viscosity η is less than 51 dl / g, a stretched product having excellent tensile strength cannot be obtained even if the draw ratio is large. Although the upper limit of (η) is not particularly limited, the melt viscosity exceeding 30 dl / g is extremely high under high concentration, melt melt occurs during extrusion, and the melt spinning property deteriorates. Such ultra high molecular weight polyethylene is considerably high in molecular weight even in polyethylene obtained by polymerizing ethylene or ethylene with a small amount of other 1-olefins such as propylene, 1-butene, 4-methyl-1-pentene, 1-hexene, etc. by a so-called Ziegler polymer. It's a category.

The silane compound used for the graft treatment may be any silane compound capable of graft treatment and crosslinking treatment. Such a silane compound has both a radical polymerizable organic group and a hydrolyzable organic group.

R _n SiY _4-n (1)

(Wherein R is an organic group containing ethylenic unsaturation which is radically polymerizable, Y is a hydrolyzable organic group and n is a number of 1 or 2).

As a radically polymerizable organic group, the alkyl group containing ethylenically unsaturated hydrocarbons, such as vinyl group, an aryl group, butenyl group, and cyclohexenyl group, and ethylenically unsaturated carboxylic ester units, such as an acryloxyalkyl group and a methacrylicoxyalkyl group, etc. are mentioned. Although enumerated, a vinyl group is the most preferable. As an organic group which can be hydrolyzed, an alkoxy group, an acyloxy group, etc. are mentioned.

Suitable examples of the silane compound include, but are not limited to, vinyltriethoxysilane, vinyltrimethoxysilane, vinyltris (methoxyethoxy) silane, and the like.

[Graft and molding]

According to the present invention, silane grafts and molding are performed by thermally decomposing a composition containing the ultrahigh molecular weight polyethylene, a silane compound, a radical initiator, and a diluent by melt extrusion or the like. That is, polymer radicals are generated in ultra high molecular weight polyethylene by the action of radical initiator and heat during melt kneading, and graft of silane compound to ultra high molecular weight polyethylene is generated by reaction of the polymer radical and silane compound.

As radical initiators, all radical initiators used in this kind of graft treatment are used, for example, organic peroxides, organic peresters, for example benzoyl peroxide, dichlorobenzoyl peroxide, dicumyl peroxide, di-tert. -Butyl peroxide, 2, 5-di (peroxidebenzoate) hexyn-3, 1, 4-bis (tert-butylperoxy isopropyl) benzene, lauroyl peroxide, tert-butylperacetate, 2, 5-dimethyl-2, 5-di (tert-butylperoxy) hexyn-3, 2, 5-dimethyl-2, 5-di (tert-butylperoxy) hexane, tert-butylperbenzoate, ter t- Butylpiphenylacetate, tert-butylperisobutyrate, tert-butylper-sec-octoate, tert-butylperpivalate, cumylperpivalate and tert-butylperdiethylacetate, other azo compounds such as azobis Isobutylonitrile, dimethylazoisobutyrate. In order to perform graft effectively under melt kneading conditions of ultra high molecular weight polyethylene, it is preferable that the half-life temperature of a radical initiator exists in the range of 100-200 degreeC.

In the present invention, a diluent is formulated together with the above components to enable melt molding of the silane graft ultra high molecular weight polyethylene. As such a diluent, solvents for ultra high molecular weight polyethylene and various waxy substances suitable for ultra high molecular weight polyethylene are used.

The boiling point of the solvent used is preferably higher than the melting point of the ultrahigh molecular weight polyethylene, and particularly preferably at least 20 ° C higher than the melting point of the ultrahigh molecular weight polyethylene.

Specific examples of such solvents include aliphatic hydrocarbon solvents such as n-nonane, n-decyne, n-undecane, n-dodecane, n-tetradecane, n-octadecane or liquid paraffin, kerosene, xylene, naphthalene, te Aromatic hydrocarbon solvents such as traline, butylbenzene, p-cymene, cyclohexylbenzene, diethylbenzene, pentylbenzene, dodecylbenzene, biscrohexyl, decalin, methylnaphthalene, ethylnaphthalene or hydrogenated derivatives thereof 1, 1, Halogenated hydrocarbon solvents such as 2, 2-tetrachloroethane, pentachloroethane, hexachloroethane, 1, 2, 3-tricholopropane, dichlorobenzene, 1, 2, 4-tricholobenzene, and bromobenzene, Mineral oils, such as a paraffin process oil, a naprene process oil, and an aromatic process oil, are mentioned.

As the wax, an aliphatic hydrocarbon compound or an oil solid thereof is used.

The aliphatic hydrocarbon compound mainly contains a saturated aliphatic hydrocarbon compound and is usually called a paraffin wax having a molecular weight of 2000 or less, preferably 1000 or less, and more preferably 800 or less. Specific examples of these aliphatic hydrocarbon compounds include n-alkanes having 22 or more carbon atoms, such as docoic acid, tricoic acid, tetracoic acid, and triacontane, or mixtures with lower n-alkanes containing these as main components, so-called paraffin waxes purified from petroleum, In low molecular weight polymer obtained by copolymerization of ethylene or ethylene and another alpha-olefin. Low pressure polyenylene wax, high pressure polyethylene wax, ethylene copolymer wax or medium. Low pressure polyethylene The wax which reduced molecular weight by polyethylene etc., such as high pressure polyethylene by thermal sensitivity, waxes, such as oxides or maleic acid modified | denatured wax of these waxes, maleic acid modified wax, etc. are mentioned.

As the aliphatic hydrocarbon compound derivative, for example, one or more, preferably 1 to 2, particularly preferably 1 carboxyl group, hydroxyl group, carbamoyl group, at the terminal or inside of the aliphatic hydrocarbon group (alkyl group, alkenyl group), Fatty acids, aliphatic alcohols, fatty acid amides, fatty acid esters having 8 or more carbon atoms, preferably 15-20 carbon atoms or 130-2000 molecular weights, preferably 200-800, which are compounds having functional groups such as ester groups, mercapto groups and carbonyl groups, Aliphatic mercaptan, aliphatic aldehyde, aliphatic ketone, etc. can be mentioned.

Specifically, capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, oleic acid, fatty acid, and lauryl alcohol, myristyl alcohol, cetyl alcohol, stearyl alcohol, and fatty acid amide are caprinamide and laurin as fatty acids. Stearyl acetic acid ester etc. can be illustrated as an amide, palmitamide, stearylamide, fatty acid ester.

In the present invention, the silane compound per 100 parts by weight of the ultra-high molecular weight polyethylene is 0.1 to 10 parts by weight, in particular 0.2 to 5.0 parts by weight, the lidacal initiator is a catalytic amount, generally 0.01-3.0 parts by weight, especially 0.05-0.5 parts by weight and diluent It is recommended to use in an amount of 9900-33 parts by weight, in particular 1900-100 parts by weight. When the amount of the silane compound is lower than the above range, the crosslinking density of the final stretched crosslinked molded article becomes too low, so that the desired crystal melting temperature cannot be improved.

On the other hand, when the amount of the silane compound exceeds the above range, there is a tendency that the crystallinity of the final stretched crosslinked molded product is lowered and the mechanical properties, that is, the elasticity rate and tensile strength, are lowered. In addition, the silane compound is expensive and disadvantageously economically. When the amount of the diluent is lower than the above range, the melt viscosity becomes too high, making melt kneading and melt molding difficult, the surface roughness of the molded product is severe, and stretching and the like are likely to occur. On the other hand, when the amount of the diluent is larger than the above range, melt kneading is also difficult and the stretchability of the molded article is lowered.

The compounding of the above-mentioned drugs with respect to ultra high molecular weight polyethylene can be performed by arbitrary means. For example, a silane compound, a radical initiator, and a diluent may be simultaneously mixed and melt kneaded, or a silane compound and a radical initiator may be first mixed, followed by a diluent. Alternatively, the ultrahigh molecular weight polyethylene may be first mixed with a diluent first. And a method of blending a radical initiator first followed by blending a silane compound and a radical initiator.

Melt kneading is generally performed at a temperature of 150-200 ° C., especially 170-270 ° C., and melting temperature becomes too high at a temperature lower than the above range, making it difficult to melt molding. The molecular weight of the ultrahigh molecular weight polyethylene decreases, making it difficult to obtain a molded article having a high modulus of elasticity and high strength. In addition, the mixing may be a dry mixer using a Henschel mixer, a V-type mixer, or the like, or may be melt mixing using a single screw or a multiaxial extruder.

Melt molding is generally performed by melt extrusion molding. For example, a filament for drawing is obtained by melt extrusion through spinning exposure, and a drawing film or tape is obtained by extruding through a plate die or a ring die, and a drawing blow molding pipe (Parisson is extruded through a circular die again). ) Can be obtained. The present invention is particularly useful for the production of stretched filaments, whereby the melt extruded from the radiation nozzle may be drafted, i.e., tensioned in the molten state. Die of molten resin. The ratio between the extrusion speed Vo in the orifice and the winding speed V of the cooled unstretched material is called the draft ratio and can be defined by the following equation.

Draft ratio = V / Vo (2)

Such draft ratio can be generally 3 or more, preferably 6 or more, depending on the temperature of the mixture and the molecular weight of the ultrahigh molecular weight polyethylene.

Of course, melt molding is not limited to extrusion molding, and in the case of manufacturing various stretch molding containers, it is also possible to manufacture a preliminary mold for stretching blow molding by injection molding. The cooling solidification of the molded product can be performed by forced cooling means such as air cooling or water cooling.

[Extension]

The unstretched molded article of the obtained silane graft ultra high molecular weight polyethylene is stretched. The temperature of the stretching treatment is such that the molecular orientation in at least uniaxial direction becomes effective for the ultra high molecular weight polyethylene of the molded body.

It is preferable to extend | stretch a silane graft polyethylene molded object generally at the temperature of 40-160 degreeC, especially 80-145 degreeC. As the heat medium for heating and maintaining the unstretched molded body at the above temperature, any of air, water vapor and a liquid medium can be used. However, as the heat medium, a solvent capable of eluting and removing the above-mentioned diluent, and its boiling point is higher than the melting point of the molded body composition, specifically, when the stretching operation is performed using decarin, decane, kerosene, etc., the diluent described above. It is preferable to eliminate the uneven stretching at the time of stretching and to achieve high draw ratio.

Of course, the means for removing the excess diluent from the ultra-high molecular weight polyethylene is not limited to the electric method, and the unstretched product is treated with a solvent such as hexane, heptane, heated ethanol, chloroform, benzene and the like, and the stretched product is hexane, heptane, and heating. Also by the method of treating with a solvent such as ethanol, chloroform, benzene, it is possible to effectively remove the excess diluent in the molded product to obtain a high elastic modulus and a high strength stretched product.

The stretching operation can be performed in one or two or more stages. Although the draw ratio depends on the desired molecular orientation effect, in general, the stretching operation to have a draw ratio of 5-80 times, in particular 10-50 times, yields satisfactory results.

In the case of uniaxial stretching operations such as filament, tape, or uniaxial stretching, tensile stretching may be performed between rollers having different circumferential speeds. In the case of biaxially oriented films, tensile stretching is performed longitudinally between rollers having different circumferential speeds. Tensile stretching is also performed in the transverse direction with a tenter or the like. In addition, biaxial stretching by the inflation method is also possible. In the case of a three-dimensional molded article such as a container, a biaxially stretched molded article can be obtained by a combination of tensile stretching in the axial direction and expansion stretching in the circumferential direction.

[Cross-linking]

According to the present invention, after the impregnation of the silanol condensation catalyst in the molded product during or after the stretching, the stretched molded product is brought into contact with water to crosslink.

As a silanol condensation catalyst, it is well-known by itself, For example, dialkyl tin dicarboxylates, such as dibutyl tin dilaurate, dibutyl tin diacetate, dibutyl tin dioctoate; Organic titanates such as tetrabutyl ester titanate; Lead naphthenate and the like can be used. These silanol condensation catalysts can be effectively impregnated in the molded bodies by contacting the unstretched or stretched molded bodies in a dissolved state in a liquid medium. For example, when the stretching treatment is performed in a liquid medium, the silanol condensation catalyst is dissolved in the stretching liquid medium, and the impregnation treatment of the silanol condensation catalyst into the molded body can be performed simultaneously with the stretching operation. In the method of the present invention, it is assumed that diluents such as waxes contained in the molded body act to promote uniform impregnation of the silanol condensation catalyst into the molding agent.

The amount of silanol condensation catalyst impregnated in the molded body is preferably a catalytic amount, and it is difficult to define the amount directly, but generally 10-100% by weight, especially 27-75 in a liquid medium in contact with the unstretched or stretched molded body. Satisfactory results are obtained by adding the silanol condensation catalyst in an amount by weight to bring this liquid medium into contact with the shaped body.

The crosslinking treatment of the stretched molded product is carried out by bringing the stretched molded product of the silane graft ultra high molecular weight polyethylene impregnated with the silanol condensation catalyst into contact with moisture. There is no particular restriction on the crosslinking conditions, but generally low treatment temperature requires a long treatment time, so industrially, it is advantageous to contact the stretched molded body with water for 3 to 24 hours at a temperature of 50-130 ° C. Do. For this purpose, the moisture is preferably applied to the stretched molded body in the form of hot water or steam. In this crosslinking treatment, the stretched molded product can be placed under constraints to prevent orientation relaxation, or a degree of orientation relaxation may occur under unconstrained conditions.

[Molecular Orientation-Silane Crosslinked Body]

If the stretched molded product is crosslinked and then stretched (usually 3 times or less), the mechanical strength such as tensile strength is improved again.

The molecular orientation and silane crosslinked ultra high molecular weight polyethylene molded body according to the present invention have a surprising feature that, under the constraint conditions, the crystal melting peak (Tp) is exhibited even at a much higher temperature than the original crystal melting temperature (Tm) of ultra high molecular weight polyethylene.

The intrinsic crystal melting temperature (Tm) of ultra high molecular weight polyethylene can be obtained by melting the molded body once completely, cooling it to relax molecular orientation in the molded body, and then raising the temperature again, so-called second run in a differential scanning calorimeter.

In addition, the constraint condition means a condition in which the end is fixed to prevent the free deformation, although no specific tension is given to the molded body.

As is apparent from FIG. 4 described above, the molded article according to the present invention has at least two crystal melting peaks (Tp) at a temperature of at least 10 ° C higher than the original crystal melting temperature (Tm) of ultra-molecular weight, The heat of fusion by the crystal melting peak Tp has a specificity of 40% or more, particularly 60% or more.

Generally, the crystal melting peak (Tp) in the molded article of the present invention is the high temperature side melting peak (Tp1) and the temperature range (Tm + 10 ° C) in the temperature range (Tm + 35 ° C)-(Tm + 120 ° C). -At (Tm + 35 ℃), it is often shown as two with the cold side peak (Tp2), and the melting peak of Tm itself is very small.

In addition, when the amount of silane graft of the molded body is small, the high temperature side melting portion Tp1 does not show a clear maximum point (peak) in the melting curve, and the high temperature of the broad maximum point (peak) or the low temperature side melting portion (Tp2) is high. It is often represented as a shoulder or a tail over (Tm + 35 degreeC)-(Tm + 120 degreeC) on the side.

When the melting peak of Tm is extremely small, it may be hidden by the melting peak shoulder of Tp1. For example, even without the harmful peak of Tm, it does not interfere with the function of the ultra high molecular weight polyethylene molded product. The high temperature side melt peak (Tp1) and the low temperature side melt peak (Tp2) in the temperature range (Tm + 10 ° C)-(Tm + 35 ° C) at (Tm + 35 ° C)-(Tm + 120 ° C), respectively. Depending on the preparation conditions of the sample and the measurement conditions of the melting point, it may be further divided into two or more melting peaks.

These high crystal melting peaks (Tp1, Tp2) act to remarkably improve the heat resistance of the ultra high molecular weight polyethylene molded body, and it is called the high temperature side melting peak (Tp1) that contributes to the improvement of the strength retention rate after the high temperature thermal history. I think.

Therefore, it is preferable that the total heat of fusion due to the high temperature side melting peak Tp1 in the temperature range (Tm + 35 ° C)-(Tm + 120 ° C) should be at least 5%, in particular at least 10% of the heat of fusion.

In addition, as long as the total amount of heat of fusion caused by the high temperature side melting peak Tp1 satisfies the above-mentioned value, the high temperature side melting peak Tp1 does not appear to protrude as the main peak, that is, an aggregate of broad peaks or broad peaks. Even if it is, the heat resistance may be slightly lost, but the creep resistance is excellent.

In the present invention, the above-mentioned shift of the crystal melting peak to the high temperature side does not occur in the simple stretched polyethylene molded body or the simple stretched crosslinked polyethylene molded body, and the molecular orientation by grafting and stretching the silane to the polyethylene composition containing such diluent and crosslinking of the silane. This can be done by combining in the above order.

Melting | fusing point and the heat of crystal melting in this invention were measured with the following method.

The melting point was as follows with a differential scanning calorimeter. Differential scanning calorimeter DSC type II (manufactured by Perkin Elmer) was used. The sample was restrained in the direction of direction by winding about 3 mg on an aluminum plate of 4 mm x 4 mm thickness 100 mu. Next, the sample wound up to the aluminum plate was enclosed in the aluminum pan, and it was set as the sample for measurement. In addition, in the normal empty aluminum pan put in a reference holder, the thing used for a sample and the aluminum plate were enclosed, and thermal equilibrium was taken. The sample was first held at 30 ° C. for about 1 minute, and then heated to 250 ° C. at a temperature rising rate of 10 ° C./min to complete the melting point measurement at the first temperature increase. Subsequently, it hold | maintained for 10 minutes in the state of 250 degreeC, and then heated at the temperature-fall rate of 20 degree-C / min, and hold | maintained the sample for 10 minutes at 30 degreeC again. Subsequently, the second temperature was raised to 250 ° C. at a temperature rising rate of 10 ° C./min, and the melting point measurement at the time of the second temperature rising (second.run) was completed. The maximum value of the melting peak at this time was taken as the melting point. In the case of appearing as a shoulder, a tangent was drawn at the inflection point on the closest low temperature side of the shoulder and the inflection point on the closest high temperature side to make the intersection point the melting point.

In addition, water is repaired at a point 10 ° C higher than the original crystal melting temperature (Tm) of the ultra-molecular weight polyethylene, which is obtained by connecting the point between the endothermic curve at 60 ° C and 240 ° C and obtained the main melting peak at the straight line (base line) and the second elevated temperature. The low temperature side partitioned by these is made by the ultra-high molecular weight polyethylene original crystal melting (Tm), and the high temperature side is the crystal melting (Tp) which expresses the function of the molded object of this invention. The amount of heat of fusion of crystals was calculated from these areas. Also, the amount of heat of fusion due to melting of Tp1 and Tp2 is determined by the above-described method, and the portion of heat of fusion due to melting of Tp2 is divided by the waterline at (Tm + 10 ° C) and the waterline at (Tm + 35 ° C). The high temperature side part was computed by the same method as the quantity of heat of fusion by melting of Tp1.

The degree of molecular orientation in the molded product can be known by X-ray diffraction, birefringence, fluorescence polarization, or the like. In the case of the stretched silane crosslinked filaments of the present invention, for example, the degree of orientation by half-valne width described in detail in Kure, Gubo: Industrial Chemical Magazine 39 , 992 (1939), that is, the equation

(Where H ° is the half width of the intensity distribution curve along the Deby-ring of the strongest paratroupe on the equator, in degrees), and the molecular orientation is defined so that the degree of orientation (F) is at least 0.90, in particular at least 0.95. It is preferable from the viewpoint of heat resistance and mechanical properties.

The grafted amount of the silane can be obtained by extracting the stretched crosslinked molded product in p-xylene at a temperature of 135 ° C for 4 hours, extracting and removing unreacted silane or the diluent contained, and quantifying Si by weight or atomic method. . In the present invention, the amount of silane graft is expressed in terms of Si% by weight per ultra high molecular weight polyethylene, and preferably in the range of 0.01 to 5% by weight, particularly 0.035 to 3.5% by weight, in terms of heat resistance. In other words, when the graft amount is smaller than the above range, the crosslinking density is smaller than in the case of the present invention. On the other hand, when the graft amount is larger than the above range, the crystallinity is lowered and all of them have insufficient heat resistance.

In the molecular orientation-silane crosslinked molded article of the present invention, the crystal melting temperature of at least a part of the polymer rings constituting the molded article is extremely excellent in heat resistance from being lost and moved to the high temperature side as described above. The strength retention rate after giving the heat history for a minute is 80% or more, preferably the strength retention rate after giving the heat history for 10 minutes at 180 ° C. is 60% or more, in particular 80% or more, more particularly at 200 ° C. for 5 minutes. The conventional ultra high molecular weight polyethylene having a strength preservation ratio of 80% or more after imparting exhibits surprising heat resistance that cannot be expected at all.

In addition, the molded article of the present invention exhibits elongation of 50% or more after the uncrosslinked material is left for 1 minute under conditions of heat-resistant creep characteristics, for example, a load: 30% breaking load and a temperature of 70 ° C. Especially 20% or less is extremely good. In addition, the molded article of the present invention exhibits 20% or less of elongation after standing for 1 minute, while uncrosslinked material does not stand for 1 minute under elongation under load: 50% breaking load and temperature: 70%.

In addition, since the molded product contains grafted and crosslinked silanes, the molded article is also excellent in adhesiveness, in particular in contact with various resins, and this fact can be easily understood by referring to the examples described below.

In addition, the molded body is made of ultra high molecular weight polyethylene and is effectively provided with molecular orientation, so it is also excellent in mechanical properties. For example, the shape of the stretched filament shows an elastic modulus of 20 GPa or more and a tensile strength of 1.2 GPa or more.

Effects of the Invention

The molecular orientation and silane crosslinked ultra high molecular weight polyethylene molded article of the present invention are excellent in combination of heat resistance, mechanical properties, adhesiveness and the like. Therefore, when the molded article is used in the filament form as a reinforcing fiber for various resins such as epoxy resins, unsaturated polyesters, synthetic rubbers, etc., it is obvious that a significant improvement in heat resistance and adhesiveness is achieved compared to conventional ultra high molecular weight polyethylene stretched filaments. Do. In addition, the filament has a high strength and a low density, which is particularly effective in weight reduction compared to conventional molded products using glass fibers, carbon fibers, boron fibers, aromatic polyamide fibers, aromatic polyimide fibers, and the like. Like composite materials using glass fiber, it can be molded into UD (unit directional), laminated board, SMC (sheet molding compound), BMC (bulk molding compound), and so on. It is expected to use various composite materials in light and high strength fields such as plates.

EXAMPLE

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to the following examples without exceeding the scope thereof.

Example 1

[Grafts and radiation]

Ultra high molecular weight polyethylene (intrinsic viscosity (η) = 8.20 dl / g): 100 parts by weight of vinyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd.): 10 parts by weight and 2, 5-dimethyl-2, 5-di (tert-butylperoxy) hexane (Nihon Oil Holdings: Trade Name, PHAhexa 25B): After uniformly blending 0.1 parts by weight, powder of paraffin wax (100% by weight of ultra high molecular weight polyethylene) Goose 1266, melting | fusing point = 69 degreeC): 370 weight part addition mixing was performed and the mixture was obtained. Subsequently, the mixture was melt-kneaded at a set temperature of 200 ° C. using a screw extruder (screw diameter = 20 mm, L / D = 25), and then the melt was spun into a die having an orifice diameter of 2 mm to complete silane graft. . The spinning fiber was cooled and solidified with air at room temperature with an air gap of 180 cm to obtain an unstretched ultrahigh molecular weight polyethylenesilane graft fiber. The undrawn yarn was 800 denier and the graft rate at spinning was 36.4. Moreover, the winding speed at this time was 90 m / min.

[Quantification of Silane Graft]

About 8 g of the unstretched graft fiber prepared by the above method was melted in 200 kPa of p-crylene heated and maintained at 135 ° C. Subsequently, ultra high molecular weight polyethylene was precipitated in excess hexane at room temperature to remove paraffin wax and unreacted silane compound. Then, the graft amount which calculated | required Si weight% as a gravimetric method was 0.57 weight%.

[Extension]

The grafted unstretched fiber spun in the ultrahigh molecular weight polyethylene mixture by the above method was stretched under the following conditions to obtain an orientation stretched fiber. Two stages of stretching were carried out in a drawing tank using n-decane as a heating medium using three Gothic rollers. At this time, the temperature in the first drawing tank was 110 ° C, the temperature in the second drawing tank was 120 ° C, and the effective length of the bath was 50 cm, respectively. In extending | stretching, the rotation speed of a 1st high pitch roller was changed into 0.5 m / min, and the rotation speed of a 3rd high pitch roller was changed, and the fiber of predetermined draw ratio was obtained. In addition, the rotation speed of the second gourd roller was appropriately selected within a range capable of stable stretching. However, the draw ratio was calculated by calculating the rotation ratio between the first gothic roller and the third gothic roller.

The obtained fiber was depressurized and dried at room temperature to obtain a stretched ultra high molecular weight polyethylene silane graft fiber.

[Impregnation of crosslinking catalyst]

In the case of crosslinking the orientation fibers of the silane compound graft ultra high molecular weight polyethylene prepared by the above method, a mixture of n-decane and n-decane and the same amount of dibutyltin dilaurate is used as a heating medium in a second stretching bath during stretching. Paraffin wax was extracted, and dibutytin dilaurate was impregnated in the fiber. The obtained fiber was dried at reduced pressure room temperature until the smell of decane disappeared.

[Bridge]

The fibers were then left to stand in boiling water for 12 hours to complete crosslinking.

[Measurement of gel fraction]

About 0.4 g of the silane crosslinked ultrahigh molecular weight polyethylene fiber obtained by the above method was added to a Erlenmeyer flask equipped with a cooling tube containing 200 ml of paraxylene, and stirred for 4 hours in a boiling state. The insolubles were then filtered through a stainless steel mesh of 300 mesh, dried under reduced pressure at 80 ° C., and weighed to obtain the insolubles. The gel fraction was made into the following formula | equation.

The gel fraction of the prepared sample was 51.4%.

Tensile modulus, tensile strength, and elongation at break were measured at room temperature (23 ° C) using an Instron universal testing machine type 1123 (manufactured by Instron). The sample length between clamps was 100 mm, and the tensile speed was 100 mm / min. The tensile modulus, however, is the initial modulus. The fiber cross-sectional area required for the calculation was obtained by measuring the length of the weight with a polyethylene density of 0.96 g / cm 3.

The physical properties of the silane crosslinked stretch ultrahigh molecular weight polyethylene fiber thus obtained are shown in Table 1.

TABLE 1

In addition, the crystal melting temperature (Tm) of the ultrahigh molecular weight polyethylene, which is obtained as the main melting peak at the second elevated temperature, is 132.2 ° C, and the ratio of the heat of fusion due to Tp to the total crystal heat of fusion and the heat of fusion due to Tp1. The percentages of heat of fusion were 73% and 22%, respectively. At this time, the main one of Tp2 was 151.0 ° C and the main one of Tp1 was 226.5 ° C.

FIG. 1 shows the melting characteristic curve at the first elevated temperature of the ultra high molecular weight polyethylene used in Example 1 molded into an air pressure sheet having a thickness of 100 µ at 200 ° C. 2, the melting characteristic curve at the time of the 1st temperature increase of the non-grafted stretch ultrahigh molecular weight polyethylene fiber prepared by the comparative example 1 mentioned later is shown. In addition, Figure 3 is extracted from the silane-grafted unstretched fly pin wax of Example 1 with hexane at room temperature, and press-molded to a pressure sheet, and then impregnated with dibutyl tin dilaurate and crosslinked by the method of Example 1 again. The melting characteristic curve at the first elevated temperature of one sample is shown. 4 shows the melting characteristic curve of the silane crosslinked stretch ultrahigh molecular weight polyethylene fiber prepared in Example 1 at the first temperature increase, and again the melting characteristic curve of the fiber at the second temperature rise (second.run). . 6 shows the crystallization characteristic curve at the time of temperature transfer transferred from the first elevated temperature to the second elevated temperature.

[Evaluation of Adhesiveness]

Evaluation of adhesiveness was made by the drawing method. Adhesion zone water purification was performed by using aradite and rabbit (epoxy resin, Showa Polymer Co., Ltd.), and the method was carried out by the adhesion force A method (P test) of JISL-1017 chemical fiber tire cord test method. The results are shown in FIG.

The silane crosslinked stretched ultra high molecular weight polyethylene fiber (Sample-1) prepared in this example has improved the adhesive force (pulling force) about three times as compared to the stretched ultra high molecular weight polyethylene fiber (Sample-2) prepared in Comparative Example 1 described later. Able to know.

[Evaluation of Creep Characteristics]

The creep test was performed at 1 cm of sample length and 70 degreeC of ambient temperature using the thermal stress stress measuring apparatus TMA / SSIO (made by Seiko Electronics Co., Ltd.). The result at 500 MPa load is shown in FIG. 8, and the result at 30% load of breaking load is shown in FIG. The silane crosslinked stretched high molecular weight polyethylene fiber (Sample-1) prepared in the present Example was significantly improved in any case compared with the stretched ultrahigh molecular weight polyethylene fiber (Sample-2) prepared in Comparative Example 1 described later. Able to know. Table 2 shows the elongation at 1 minute, 2 minutes and 3 minutes immediately after the load in the creep test performed at a load corresponding to 50% of the breaking load at room temperature at 70 ° C.

TABLE 2

Strength Preservation Rate after Thermal History

The thermal history test was carried out by standing in a gaya oven (fect oven: Dahai Manufacturing Co.). The sample was fixed to both ends by attaching a plurality of pulleys at both ends of the stainless steel frame to a length of about 3 m. At this time, both ends of the sample were fixed to the extent that the sample did not loosen, and the sample was not actively tensioned. The results are shown in Table 3.

TABLE 3

It can be seen from Table 3 that it has surprising heat resistance strength preservation characteristics.

[Measurement of Orientation by X-ray Diffraction]

The fiber was wound up 10-20 times in a philips holder, cut | disconnected one side, and it measured in bundle shape. The degree of orientation was obtained by measuring the (110) plane reflection of polyethylene crystals on the equator line with a diffractometer to determine the reflection intensity distribution. The calculation was performed according to the method described above. The orientation degree thus obtained was 0.955.

[Observation of Crystal Fusion by Polarizing Microscope]

The observation sample was prepared by winding a fiber sample on a glass plate having a width of about 2 mm and a thickness of about 0.5 mm to fix both ends. Subsequently, the observation sample was observed with the polarization microscope, heating up at the temperature increase rate of 10 degree-C / min on the heating stage (the model PF20 by the Met company). The silane crosslinked stretch ultrahigh molecular weight polyethylene fiber prepared in this example was found to have crystals at 200 ° C (FIG. 10), but became darkfield at 220 ° C, and crystal melting was confirmed.

Comparative Example 1

[Preparation of Ultra High Molecular Weight Polyethylene Stretch Fiber]

100 parts by weight of the powder of ultra high molecular weight polyethylene (intrinsic viscosity (η) = 8.20) and 320 parts by weight of the powder of paraffin wax described in Example 1 were spun by the method described in Example 1. In this example, the draft ratio was 25 times and the undrawn island was 100 denier. Then stretched in the same manner to prepare a stretched fiber. The abf property of the produced fiber is shown in Table 4.

TABLE 4

The melting characteristic curve of this fiber (sample-2) is shown in FIG. Adhesive force was measured by the method as described in the row of <evaluation of adhesiveness> of Example 1. The result was shown in FIG. 6 with Example 1. FIG. Creep characteristics were measured by the method described in the section of <Evaluation of creep characteristics> of Example 1. The results at 500 MPa load are shown in FIG. 8 and the results at 30% load of breaking load are shown in FIG. In addition, in the measurement of creep characteristics (ambient temperature: 70 ° C., load: 50% of the breaking load at room temperature) performed in the same manner as described in Example 1, the sample broke immediately after the load. 2 shows a DSC melting characteristic curve at the first temperature increase. The original crystal melting temperature Tm, which is obtained as the main melting peak at the second temperature increase, is 132.2 ° C. The ratio of the heat of fusion due to Tp to the heat of fusion and the heat of fusion due to Tp1 The proportions were 32.1% and 1.7%, respectively. The measurement of the strength preservation rate after heat history was carried out by the method described in the section of <Strength preservation rate after heat history> in Example 1, but was completely melted in an oven temperature of 180 ° C. in less than 10 minutes. Crystal melting observation under a polarizing microscope was similarly performed according to the method described in the section of <observation of crystal melting by polarizing microscope> of Example 1. Crystals were observed (FIG. 11) at 150 ° C, but became darkfield near 180 ° C.

Comparative Example 2

[Preparation of Silane Crosslinked Polyethylene Fiber]

Powder of polyethylene (density: 0.955 g / cm 3 intrinsic viscosity (η) = 2.30 dl / g): 100 parts by weight of 10 parts by weight of vinyltrimethoxysilane, peroxide and paraffin wax powder, respectively, described in Example 1 The mixture was uniformly mixed with the parts by weight and 33 parts by weight, and then spun from a 1 mm die by the method described in Example 1 to obtain 1800 denia unstretched fibers. The graft ratio at this time is obtained by Si weight%. 1.23 weight%. Continued, the drawing was carried out in the method described in Example 1, the catalyst was impregnated, fibrized to complete the crosslinking. The prepared fiber properties are shown in Table 5.

TABLE 5

The measurement of strength retention after thermal history was carried out by the method described in the section on strength retention after thermal history in Example 1. The results are shown in Table 6.

TABLE 6

In the thermal history of 180 ° C, the melting time was less than 10 minutes. Since the molecular weight is lower than that of Sample-1 of Example 1, the strength before the thermal history is also low, and the strength retention rate after the thermal history is also inferior.

In addition, the creep characteristics were measured by the method described in Example 1 (a load corresponding to 50% of the breaking load at ambient temperature = 70 ° C and load = room temperature), and the sample was broken immediately after the load. 12 shows the DSC melting characteristic curve at the first elevated temperature. The original crystal melting temperature Tm obtained as the primary melting peak at the third temperature increase is the ratio of the heat of fusion due to Tp to the total crystal melting heat and the heat of fusion due to Tp1 at 128.0 ° C. 47% and 9.5%, respectively. As in Example 1, creep test was performed under a load corresponding to 50% of the breaking load at room temperature at an ambient temperature of 70 ° C., and fracture occurred immediately after the load.

Comparative Example 3

[Preparation of crosslinked stretched fiber by peroxide]

Paraffin wax was extracted using an excess of hexane in the non-drawn yarn prepared by the method described in Comparative Example 1. The undrawn yarn was dried at room temperature under reduced pressure. Subsequently, 20 weight% of dicumyl peroxide (Mitsui Petrochemical Co., Ltd., brand name, Mitsui DCP) was impregnated with an acetone solution, depressurized again, dried at room temperature, and manufactured by unstretched yarn. Content of dicumyl peroxide measured by the gravimetric method was 0.51 weight%.

Subsequently, two stages of stretching were performed using three goddet rollers using an infrared gold imager (RHL-E416, manufactured by Shinkuriko Co., Ltd.) as a drawing tank. The temperature in a 1st drawing tank at this time was 110 degreeC, the temperature in a 2nd drawing tank was 145 degreeC, and the effective length of the tank was 42 cm, respectively. In drawing, the fiber of a predetermined draw ratio is obtained by adjusting the rotational speed of the third gourd roller by setting the rotational speed of the first gourd roller to 0.5 m / min. In addition, the rotational speed of the second gourd roller was appropriately selected within a range capable of extending the safety. However, the draw ratio was calculated from the rotation ratios of the third gothic roller of the first gothic roller and the third gothic roller. The physical properties of the produced fiber are shown in Table 7.

TABLE 7

In addition, the original crystal melting temperature Tm, which is obtained as the main melting peak at the second elevated temperature, is 133.1 ° C, and the ratio of the heat of melting due to Tp to the heat of precrystallization melting and the heat of melting due to Tp1 are determined. The percentages of calories were 73% and 2%, respectively. The measurement of the strength preservation rate after heat history was performed by the method described in the section <Strength preservation rate after heat history> in Example 1. The fiber shape did not change with the history of 10 minutes at 180 ° C., but the fiber melted.

Example 2

Ultra high molecular weight polyethylene (intrinsic viscosity (η) = 8.20 dl / g): 100 parts by weight of vinyl tris (methoxyethoxy) silane (manufactured by Shin-Etsu Chemical Co., Ltd.): 10 parts by weight and 2, 5-dimethyl-2 , 5-di (tert-butylperoxy) hexane (Nihon Holdings: Trade Name, Perhexa 25B): After uniformly blending 0.1 parts by weight, powder of paraffin wax with respect to 100 parts by weight of ultra high molecular weight polyethylene : Brand name, Lubox 1266, melting | fusing point = 69 degreeC): 235 weight part was added and mixed, and the mixture was obtained. This mixture was then melt kneaded and grafted at a set temperature of 250 ° C. using a screw extruder (screw diameter = 20 mm, L / D = 25), followed by spinning, stretching and crosslinking in the manner described in Example 1 The silane crosslinked stretch ultrahigh molecular weight polyethylene fiber was prepared.

The physical properties of the fibers thus produced are shown in Table 8.

TABLE 8

In addition, the intrinsic crystal melting temperature Tm of ultra high molecular weight polyethylene, which is obtained as the main melting peak at the second elevated temperature, is 132.1 ° C, and the ratio of the heat of fusion due to Tp to the heat of fusion and the heat of fusion due to Tp1 The percentage of calories was 59% and 11%, respectively. At this time, Tp2 was 148.1 ° C and the main one of Tp1 was 170.5 ° C. Further, the melting characteristic curve at the first elevated temperature is shown in FIG. Table 9 and Table 10 show the amount of silane graft (Si wt%), gel fraction, and tensile characteristic retention measured by the method described in Example 1.

TABLE 9

TABLE 10

As in Example 1, the creep test was performed at a load corresponding to 50% of the breaking load at room temperature at an ambient temperature of 70 ° C. The elongation after 1 minute, 2 minutes, and 3 minutes immediately after the load is shown in Table 11.

TABLE 11

The degree of orientation determined by the method of Example 1 was 0.950.

Example 3

Ultra high molecular weight polyethylene (intrinsic viscosity (η) = 15.5 dl / g): 100 parts by weight of vinyltriethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd.): 3 parts by weight and 2, 5-dimethyl-2, 5-di (tert-Butyl peroxy) hexane (Nihon Oil Holdings: Trade Name, Perhexa 25B): After uniformly blending 0.1 parts by weight, powder of paraffin wax (100 parts by weight of high molecular weight polyethylene) Box 1266 melting point = 69 ° C.): 400 parts by weight was added and mixed to obtain a mixture. The mixture was then melt kneaded and grafted at a set temperature of 250 ° C. using a screw extruder (screw diameter = 20 mm, L / D = 25), followed by spinning, stretching, Crosslinking was performed to prepare silane crosslinked stretch ultrahigh molecular weight polyethylene fibers. The physical properties of the fibers thus produced are shown in Table 12.

TABLE 12

In addition, the intrinsic crystal melting temperature Tm of ultra high molecular weight polyethylene, which is obtained as the main melting peak at the time of the second elevated temperature, is 133.7 ° C, and the ratio of the amount of heat of fusion due to Tp to the amount of heat of fusion and the amount of heat of fusion due to Tp1 The ratios of heat of fusion were 67.4% and 12.4%, respectively. At this time, Tp2 was 152.2 ° C and the main one of Tp1 was 181.4 ° C. Moreover, the DSC melting characteristic curve at the 1st temperature rising is shown in FIG. Tables 13 and 14 show the amount of silane graft (Si weight%), gel fraction and tensile property retention measured by the method described in Example 1.

TABLE 13

TABLE 14

As in Example 1, crepe test was carried out under a load corresponding to 50% of the breaking load at room temperature at an ambient temperature of 70 ° C. Table 15 shows the elongation after 1 minute, 2 minutes, and 3 minutes immediately after the load.

TABLE 15

The degree of orientation determined by the method of Example 1 was 0.964.

Example 4

Ultra High Molecular Weight Polyethylene (Intrinsic Viscosity (η) = 8.20 dl / g) Powder: 100 parts by weight of triethoxysilane (manufactured by Shin-Etsu Chemical): 5 parts by weight and dicumyl peroxide (Nihon Holdings: trade name, Percumyl ): 0.05 parts by weight of the mixture was uniformly added, and then 100 parts by weight of ultra-high molecular weight polyethylene was added and mixed with 400 parts by weight of paraffin wax powder (Nihon Solder: trade name, Lubox 1266, melting point = 69 ° C). The mixture was then melt kneaded and grafted at a set temperature of 230 ° C. using a screw extruder (screw diameter = 20 mm, L / D = 25), and then spun, stretched, and treated according to the method described in Example 1. The silane crosslinked stretch ultra high molecular weight polyethylene fiber was prepared. The physical properties of the fibers thus produced are shown in Table 16.

TABLE 16

In addition, as the differential scanning calorimeter, the original crystal melting temperature Tm of ultra-high molecular weight polyethylene obtained as the main melting peak at the second elevated temperature is 133.2 ° C, and the ratio of the heat of fusion due to Tp to the total crystal heat of fusion and the heat of solvent due to Tp1. The proportions of heat of fusion were 71.5% and 19.0%, respectively. At this time, Tp2 was 150.3 and the main one of Tp1 was 234.7 ° C. In addition, the DSC melting characteristic curve at the first elevated temperature is shown in FIG. The amount of silane graft (Si weight%) gel fraction and tensile property retention measured by the method described in Example 1 are shown in Tables 17 and 18.

TABLE 17

TABLE 18

In addition, as in Example 1, creep test was conducted under a load corresponding to 50% of the breaking load at room temperature at an ambient temperature of 70 ° C. Table 19 shows the elongation rates after 1 minute, 2 minutes and 3 minutes immediately after the load.

TABLE 19

Moreover, the orientation degree calculated | required by the method of Example 1 was 0.954.

Example 5

Ultra high molecular weight polyethylene (powder with intrinsic viscosity (η) = 8.20: vinyltriethoxysilane (manufactured by Shin-Etsu Chemical Co.) with respect to 100 parts by weight): 5 parts by weight and 2, 5-dimethyl-2, 5-di (tert-butylper Oxy) hexyne-3 (Nihon Oil Holding, trade name, Perhexa 25B): A powder of paraffin wax (Nihon Soldering Agent: trade name, Lubox 1266, melting point with respect to 100 parts by weight of ultra high molecular weight polyethylene after uniformly blending 0.05 parts by weight. = 69 ° C.): 400 parts by weight of the mixture was added to obtain a mixture, which was then melt kneaded and grafted at a set temperature of 200 ° C. using a screw extruder (screw diameter = 20 mm, L / D = 25). Subsequently, the silane crosslinked stretched ultrahigh molecular weight polyethylene fibers were produced by spinning, stretching and crosslinking according to the method described in Example 1. Table 20 shows the physical properties of the fibers thus prepared.

TABLE 20

In addition, the intrinsic crystal melting temperature Tm of ultra high molecular weight polyethylene, which is obtained as the main melting peak at the time of the second elevated temperature, is 133.6 ° C, and the ratio of the heat of fusion due to Tp to the heat of fusion and the heat of fusion due to Tp1 The ratio of heat of fusion was 76.2% and 6.2%, respectively. At this time, Tp2 was 153.1 degreeC. Moreover, the main peak of Tp1 was not seen, but the shoulder peak of Tp2 over the high temperature side was confirmed at (Tm + 35 degreeC).

The endothermic characteristic curve at the first temperature rise is shown in FIG.

The amount of silane graft, gel fraction and tensile property retention measured by the method described in Example 1 are shown in Tables 21 and 22.

TABLE 21

Table 22

As in Example 1, the creep test was carried out at a load corresponding to 50% of the breaking load at room temperature at an ambient temperature of 70 ° C. Table 23 shows the elongation rates 1, 2 and 3 minutes immediately after loading.

TABLE 23

Moreover, the orientation degree calculated | required by the method of Example 1 was 0.980.

Example 6

Ultra high molecular weight polyethylene (intrinsic viscosity (η) = 8.20 dl / g): 100 parts by weight of vinyltriethoxysilane (manufactured by Shin-Etsu Chemical): 1 part by weight and 2, 5-dimethyl-2, 5-di (tert-butylperoxy) hexyne-3 (Nihon holding agent, brand name, Perhexine 25B): After uniformly blending 0.05 parts by weight, powder of paraffin wax with respect to 100 parts by weight of ultra high molecular weight polyethylene (Nihon Soldering Agent: , Lubox 1266, Melting point = 69 ° C): 400 parts by weight was added and mixed to obtain a mixture. The mixture was then melt kneaded and grafted at a set temperature of 230 ° C. using a screw extruder (screw diameter = 20 mm, L / D = 25), followed by spinning in accordance with the method described in Example 1 , Stretching and crosslinking were performed to produce silane crosslinked stretch ultrahigh molecular weight polyethylene fibers. The physical properties of the fibers thus obtained are shown in Table 24.

TABLE 24

In addition, as the differential scanning calorimeter, the ultra-high molecular weight polyethylene inherent crystal melting temperature Tm, which is obtained as the main melting peak at the second elevated temperature, is 134.4 ° C, and the amount of heat of fusion due to Tp to the total heat of fusion and the heat of fusion due to Tp1. The ratio of calorific value of total crystal melting was 75.4% and 8.3%, respectively. Tp2 at this time was 154.0 ° C. Moreover, although the main peak of Tp1 was not seen (Tm + 25 degreeC), the shoulder peak of Tp2 over the high temperature side was confirmed. Tables 25 and 26 show the amount of silane graft (Si weight%), gel fraction and tensile property retention measured by the method described in Example 1.

TABLE 25

TABLE 26

As in Example 1, the creep test was carried out at a load corresponding to 50% of the breaking load at room temperature at an ambient temperature of 70 ° C. Table 27 shows the elongation rates 1, 2 and 3 minutes immediately after loading.

TABLE 27

[Comparative Example 4]

Ultra high molecular weight polyethylene (ultra-viscosity (η) = 8.20 dl / g) powder: 100 parts by weight of paraffin wax powder (Nippon Solvent: trade name, Lubox 1266, melting point = 69 ° C): 235 parts by weight A mixture was obtained. The mixture was then melt kneaded and spun at a set temperature of 200 ° C. using a screw extruder (screw diameter = 20 mm, L / D = 25). The draft ratio of spinning was 31 times and the winding speed was 15 m / min. The undrawn yarn was about 1000 denier. Subsequently, the undrawn yarn was drawn in two stages in a drawing tank made of n-decanol heating medium using four Gothic rollers. In addition, a total of three stages of stretching were performed using triethylene glycol. At this time, the 1st drawing tank temperature was 110 degreeC, the 2nd drawing tank temperature was 120 degreeC, and the 3rd drawing tank temperature was 140 degreeC, and the effective length of each tank was 50 cm. In drawing, the fiber of a predetermined draw ratio was obtained by changing the rotational speed of the first gourd roller to 0.5 m / min and changing the rotational speed of the fourth gourd roller. In addition, the rotation speeds of the second and third gothic rollers were appropriately selected within a range capable of stable stretching. However, the draw ratio was calculated and calculated from the rotation ratio between the first gothic roller and the third gothic roller. The physical properties of the fibers thus obtained are shown in Table 28.

TABLE 28

The intrinsic crystal melting temperature Tm of ultra-high molecular polyethylene, which is obtained as the main melting peak at the second temperature increase, is 133.1 ° C, and the ratio of heat of fusion due to Tp to heat of fusion and heat of fusion due to Tp1 The percentages were 72.0% and 2.2%, respectively. Tp2 at this time was 155.0 ° C. The retention rate of the tensile properties measured by the method described in Example 1 is shown in Table 29.

TABLE 29

In addition, creep test (load equivalent to 50% of breaking load at ambient temperature = 70 ° C and load = room temperature) was carried out in the same manner as in Example 1, and was stretched and melted to 49% 50 seconds after the load.

[Comparative Example 5]

Polyethylene powder used in Comparative Example 2: 100 parts by weight, and 1.0 parts by weight and 0.03 parts by weight of vinyltrimethoxysilane and dicumyl peroxide (Mitsui Petrochemical Co., Ltd., trade name, Mitsui DCP) described in Example 1, respectively After mixing, the granulated product was granulated at a set temperature of 185 ° C. with an extruder of 20 mm to obtain grafted pellets. Subsequently, 1.0 parts by weight of dibutyl tin dilaurate was uniformly mixed with 100 parts by weight of polyethylene powder used in Comparative Example 2, and granulated at a set temperature of 190 ° C. by the method described above to obtain an accelerator catalyst master batch. Thereafter, 95 parts by weight of the grafted pellet and 5 parts by weight of the crosslinking catalyst master batch were uniformly mixed, and spinning was performed at a set temperature of 270 ° C. as a spinner provided with a 25 mm screw. However, polyethylene could not be solidified and spun in a spinning machine.

Comparative Example 6

The silane grafted pellets prepared in Comparative Example 5 were spun in a melt tension tester (manufactured by Toyo Seiki Co., Ltd.) to obtain grafted undrawn yarn. At that time, the nozzle diameter was 2 mm and the set temperature was 250 ° C. Then, it extended | stretched on condition of the following, and obtained orientation oriented fiber. A pair of gothic rollers was used to draw triethylene glycol in a drawing bath as a heating medium. At this time, the elongation internal temperature was 102 ° C. and the length of the bath was 50 cm. The rotational speed of the delivery fan roller was 0.5 m / min, and the elongation was calculated | required by the method described in Example 1. The resulting stretched fiber was washed with warm water and dried at room temperature. The drawn yarn was then immersed in a 30% by weight n-decane solution of dibutyltin dilaurate under a reduced pressure of 70 cmHg to impregnate the water crosslinking catalyst. The obtained stranded catalyst-impregnated grafted stretched fiber was then left in boiling water for 1 day to complete water crosslinking. The physical properties of the silane crosslinked stretched polyethylene fiber thus obtained are shown in Table 30.

TABLE 30

In addition, the original crystal melting temperature Tm of polyethylene obtained as the primary melting peak at the second elevated temperature as a differential scanning calorimeter is 131.5 ° C, and the ratio of the heat of fusion due to Tp to the total crystal heat of fusion and the heat of fusion due to Tp1 The ratios of heat of fusion were 6.4% and 0%, respectively. The intrinsic crystal melting temperature of polyethylene, Tm, could not be highly melted despite the results of cross-linking orientation and did not form a major peak in the region of Tp2. In addition, in the region of Tp1, traces of a peak, a shoulder, etc. accompanying melting could not be confirmed. Moreover, the sub peak peculiar to the molded article of the present invention was not found in the exothermic characteristic curve at the time of recrystallization for transferring to the second elevated temperature and the endothermic characteristic curve at the second elevated temperature (second run). The endothermic characteristic curve at the first temperature increase, the exothermic characteristic curve at the time of transferring to the second elevated temperature, and the endothermic characteristic curve at the second elevated temperature are shown in FIGS. 17 to 19, respectively. As apparent from FIGS. 17-29, no characteristic peaks or shoulders on the hot side with respect to the main peaks that can be found in the stretched molded product of the present invention were found in the stretched molded product of this comparative example. The gel fraction determined by the method of Example 1 was 3.5%. In addition, the fibers melted at 140 ° C and did not exhibit preservation of tensile properties at high temperatures.

Claims (18)

Molecular orientation and silane crosslinked ultra high molecular weight polyethylene, the molded body is at least than the original crystal melting temperature (Tm) of the ultra high molecular weight polyethylene, which is obtained as the main melting peak at the second elevated temperature when measured by a differential scanning calorimeter in a restrained state. It has a high temperature of 10 ° C. and at least two crystal melting peaks (Tp), while the amount of heat of fusion due to its crystal melting peak (Tp) per heat of melting is at least 50% and the temperature range (Tm + 35 ° C.)-(Tm + And a total heat of fusion resulting from the high temperature side melting peak (Tp1) at 120 ° C) is at least 5% of the heat of fusion. The molded article according to claim 1, wherein the molded article has heat-resistant creep resistance which does not break at least for 1 minute as measured under a 30% load of the breaking load and a temperature condition of 70 ° C. 2. The molded article according to claim 1, wherein the molded article has a strength preservation ratio of at least 60% after 10 minutes of thermal history at 180 占 폚. 2. The molded article according to claim 1, wherein the molded article is expressed as Si wt% per ultra high molecular weight polyethylene and has a silane graft amount of 0.01-5 wt%. 2. A shaped body according to claim 1, which is in the form of a filament. 6. A molded article according to claim 5, having an orientation degree (F) of at least 0.90. 6. The molded article according to claim 5, having an elastic modulus of at least 20 GPa and a tensile strength of at least 1,2 GPa. After forming a composition comprising an ultrahigh molecular weight polyethylene, a silane compound, a radical initiator, and a diluent having an intrinsic viscosity (η) of 5dl / g or more, and stretching a molded article of the ultrahigh molecular weight polyethylene grafted with the silane compound, during or after stretching A method for producing a molecular orientation and silane-crosslinked high molecular weight polyethylene molded article, comprising impregnating a silanol condensation catalyst in the molded article and then crosslinking the stretched molded article by contact with water. 9. The silane compound according to claim 8, wherein the silane compound is R _n SiY _4-n (Wherein R is an organic group containing an ethylenic unsaturation capable of radical polymerization, Y is a hydrolyzable organic group, and n is a number of 1 or 2). The production method according to claim 8, wherein the silane compound is vinyltriethoxysilane, vinyltrimethoxysilane or vinyltris (methoxyethoxy) silane. 9. A process according to claim 8 wherein the radical initiator is a radical initiator having a half-life temperature of 100-200 ° C. 9. The process according to claim 8, wherein the diluent is a solvent having a boiling point above the melting point of the ultrahigh molecular weight polyethylene or a wax or waxy material suitable for the ultrahigh molecular weight polyethylene. The method according to claim 8, wherein 0.1-10 parts by weight of the silane compound, 0.01-3.0 parts by weight of the radical initiator and 9900-33 parts by weight of the diluent are mixed per 100 parts by weight of ultra high molecular weight polyethylene. The method according to claim 8, wherein the composition containing the ultrahigh molecular weight polyethylene silane compound, the radical initiator and the diluent is melt-extruded through a spinneret. 9. The method according to claim 8, wherein the silane graft polyethylene molded article is drawn at a draw ratio of 5-80 times in a heating medium at a temperature of 40-160 占 폚. The method according to claim 15, wherein the heating medium has a boiling point higher than the melting point of the molded body composition as a solvent capable of eluting off the electric diluent. 9. The process according to claim 8, wherein the silanol condensation solvent is dialkyltin dicarboxylate, organotitanate or lead naphthenate. The method according to claim 8, wherein the stretched product is crosslinked by contacting water with a temperature of 50-130 ° C for 3-24 hours.

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