JP2781201B2 - Cement admixture - Google Patents

Description

Description: TECHNICAL FIELD OF THE INVENTION The present invention relates to a cement admixture, and more particularly, to a cement admixture.
It consists of a molecularly oriented molded product of ultra-high molecular weight polyolefin,
Light weight, high strength, excellent water resistance, excellent alkali resistance,
The present invention relates to a cement admixture having creep resistance and weather resistance, and also having excellent impact resistance and fatigue resistance.

TECHNICAL BACKGROUND AND PROBLEMS OF THE INVENTION Cement compositions such as cement concrete or cement mortar shrink during drying to cause cracks, not only the strength of which is greatly reduced, but also the waterproofness of the dried cement due to the cracks. And there is a serious problem that its durability is reduced.

Therefore, attempts have been made to reduce drying shrinkage of cement products by blending fibers such as steel fibers, polymer fibers and carbon fibers or polymer dispersions for cement admixture into the cement composition. However, fibers such as steel fibers, polymer fibers, and carbon fibers all have various problems, such as heavy weight or poor mechanical strength. Also,
When the polymer dispersion for cement admixture is blended with the cement composition, there is a problem that the compressive strength of the obtained cement product is reduced depending on the blending amount.

On the other hand, in order to reduce the shrinkage of the cement composition, it is also known to add a surfactant, but when a surfactant is added to the cement composition, depending on the amount, the bending strength of the resulting cement product, There was a problem that the compressive strength was reduced.

For this reason, while the shrinkage at the time of drying is reduced, the appearance of a cement composition which is lightweight and has excellent bending strength and compressive strength has been strongly desired.

It is already known that by molding ultrahigh molecular weight polyethylene into fibers, tapes and the like and stretching them, a molecularly oriented molded article having a high elastic modulus and a high tensile strength can be obtained. For example, JP-A-56-15408 describes spinning a dilute solution of ultra-high molecular weight polyethylene and stretching the resulting filament. Further, JP-A-59-130313 discloses that ultra-high molecular weight polyethylene and wax are melt-kneaded, and the kneaded product is extruded, cooled, solidified and then stretched, and further disclosed in JP-A-59-187614. Describes that the above-mentioned melt-kneaded material is extruded, drafted, cooled and solidified, and then stretched.

SUMMARY OF THE INVENTION The present invention is intended to solve the problems associated with the prior art as described above, and is lightweight, has excellent mechanical strength and impact resistance, and has alkali resistance and creep resistance. Another object of the present invention is to provide a cement admixture excellent in fatigue resistance.

SUMMARY OF THE INVENTION The cement admixture according to the present invention is a molecular orientation body of an ultrahigh molecular weight ethylene / α-olefin copolymer having an intrinsic viscosity [η] of at least 5 dl / g, and was measured by a differential scanning calorimeter. Sometimes at least 20 ° C higher than the original crystal melting temperature (Tm) of ultra-high molecular weight ethylene / α-olefin copolymer
It is composed of a molecularly oriented molded product having at least one crystal melting peak (Tp) at a high temperature and having a heat of crystal melting based on the crystal melting peak (Tp) of 15% or more of the total heat of crystal melting. Further, the intrinsic viscosity [η] is at least 5 dl / g, and the content of α-olefin having 3 or more carbon atoms is 0.1 to 2 per 1000 carbon atoms.
It is characterized by comprising a molecularly oriented molded article of zero ultrahigh molecular weight ethylene / α-olefin copolymer.

The cement admixture according to the present invention is made of a molecularly oriented molded article of the ultrahigh molecular weight ethylene / α-olefin copolymer as described above, and has excellent mechanical strength, alkali resistance,
It has wear resistance, weather resistance, and water resistance, and also has excellent creep resistance and impact resistance.

Specific description of the invention Hereinafter, the cement admixture according to the present invention will be specifically described.

First, the molecular orientation molded product of the ultrahigh molecular weight polyolefin constituting the cement admixture according to the present invention, particularly, the molecular orientation molded product of the ultrahigh molecular weight ethylene / α-olefin copolymer will be described.

The molecularly oriented molded article used in the present invention is an ultrahigh molecular weight ethylene / α-olefin copolymer molecular oriented molded article.

Further, as the ultrahigh molecular weight ethylene / α-olefin copolymer constituting the molecular orientation molded product used in the present invention, ultrahigh molecular weight ethylene / propylene copolymer, ultrahigh molecular weight ethylene / 1-butene copolymer, Ultra high molecular weight ethylene / 4-methyl-1-pentene copolymer, ultra high molecular weight ethylene / 1-hexene copolymer, ultra high molecular weight ethylene
Ultrahigh molecular weight ethylene / α-olefin copolymers of ethylene and α-olefins having 3 to 20, preferably 4 to 10 carbon atoms, such as 1-octene copolymers and ultrahigh molecular weight ethylene / 1-decene copolymers A polymer can be exemplified. In this ultrahigh molecular weight ethylene / α-olefin copolymer,
The α-olefin having 3 or more carbon atoms has 10 carbon atoms in the polymer.
It is contained in an amount of 0.1 to 20, preferably 0.5 to 10, and more preferably 1 to 7, per 100 pieces.

A molecularly oriented molded article obtained from such an ultrahigh molecular weight ethylene / α-olefin copolymer is particularly excellent in impact resistance and creep resistance as compared with a molecularly oriented molded article obtained from ultrahigh molecular weight polyethylene. . This ultra-high molecular weight ethylene / α-olefin copolymer is lightweight and high-strength, excellent in alkali resistance, abrasion resistance, impact resistance, creep resistance, excellent in weather resistance, water resistance, salt water resistance. ing.

The ultrahigh molecular weight ethylene / α-olefin copolymer constituting the molecular orientation molded product used in the present invention has an intrinsic viscosity [η] of 5 dl / g or more, preferably 7 to 30 dl / g. The mechanical properties or heat resistance of the molecular orientation molded product obtained from the polymer is excellent. That is, the molecular terminals do not contribute to the fiber strength, and the number of molecular terminals is the reciprocal of the molecular weight (viscosity). Therefore, those having a large intrinsic viscosity [η] give high strength.

The density of the molecular orientation molding used in the present invention is 0.940
0.990 g / cm ^3, preferably 0.960 to 0.985 g / cm ³ . Here, the density was measured by a density gradient tube method according to a conventional method (ASTM D 1505). At this time, the density gradient tube was prepared by using carbon tetrachloride and toluene.
C).

Dielectric constant (1 KHz,
23 ° C.) is 1.4 to 3.0, preferably 1.8 to 2.4, and the dielectric loss tangent (1 KHz, 80 ° C.) is 0.05 to 0.008%, preferably 0.040 to
0.010%. Here, the dielectric constant and the dielectric loss tangent were measured by ASTM D150 using a film-shaped sample in which fibers and a tape-shaped molecular alignment material were densely aligned in one direction.

The stretching ratio of the molecular orientation molded product used in the present invention is 5
8080 times, preferably 10 to 50 times.

The degree of molecular orientation in the molecular orientation molded product used in the present invention can be known by an X-ray diffraction method, a birefringence method, a fluorescence polarization method, or the like. When the ultrahigh molecular weight polymer of the present invention is a drawn filament, for example, Yukichi Kure and Teruichiro Kubo: The degree of orientation according to the half-value width described in detail in Kogaku Kagaku Magazine Vol. 39, page 992 (1939), that is, the formula: (Where H ゜ is the half width (゜) of the intensity distribution curve along the Debye ring of the strongest paratropic plane on the equator line). The orientation degree (F) defined by the formula is 0.90 or more, particularly 0.95 or more. It is desirable that the molecules are oriented so that

Furthermore, the molecularly oriented molded article used in the present invention has excellent mechanical properties, for example, in the form of a drawn filament, an elastic modulus of 20 GPa or more, particularly 30 GPa or more, and a tensile strength of 1.2 GPa or more, particularly 1.5 GPa or more. And

The impulse voltage breakdown value of the molecular orientation molded product used in the present invention is 110 to 250 KV / mm, preferably 150 to 220 KV / mm. The impulse voltage breakdown value was measured by using a sample similar to the case of the dielectric constant and increasing the pressure with a brass (25 mmφ) JIS type electrode while applying a negative impulse in 2 KV / 3 steps on a copper plate.

When the molecularly oriented molded article used in the present invention is an ultrahigh molecular weight ethylene / α-olefin copolymer molecular oriented molded article, this molecularly oriented molded article has remarkable impact resistance, breaking energy and creep resistance. It has the feature of being excellent. The characteristics of the molecularly oriented molded product of these ultrahigh molecular weight ethylene / α-olefin copolymers are represented by the following physical properties.

The breaking energy of the molecular orientation molded product of the ultra-high molecular weight ethylene / α-olefin copolymer used in the present invention is 8 k.
It is at least g · m / g, preferably at least 10 kg · m / g.

Further, the ultra-high molecular weight ethylene α- used in the present invention
The molecularly oriented molded article of the olefin copolymer has excellent creep resistance. In particular, it excels in creep resistance at high temperatures, which is equivalent to the conditions for promoting normal temperature creep, and is calculated as elongation (%) after 90 seconds at a load of 30% at an ambient temperature of 70 ° C. And the creep rate (ε, sec ⁻¹ ) after 90 seconds to 180 seconds is 4 × 10 ⁻⁴ sec ⁻¹ or less, especially 5% or less.
× 10 ⁻⁵ sec ⁻¹ or less.

Among the molecular orientation bodies used in the present invention, the molecular orientation body of the ultra-high molecular weight ethylene / α-olefin copolymer has the above-mentioned ordinary temperature physical properties. It is preferable to have the above thermal properties, because the above-mentioned properties at room temperature are further improved and the heat resistance is also excellent.

The molecular orientation molded product of the ultrahigh molecular weight ethylene / α-olefin copolymer used in the present invention is at least 20 ° C. higher than the intrinsic crystal melting temperature (Tm) of the copolymer as measured by a differential scanning calorimeter. It has at least one crystal melting peak (Tp) at a temperature, and the heat of crystal fusion based on this crystal melting peak (Tp) is at least 15%, preferably at least 20%, especially at least 30% of the total crystal melting heat. It is.

Ultra-high molecular weight ethylene copolymer intrinsic crystal melting temperature (T
m) This molded body is completely melted once and then cooled,
A method of relaxing the molecular orientation in the molded body and then raising the temperature again, the second method in a so-called differential scanning calorimeter
You can ask by run.

More specifically, in the molecularly oriented molded article of the present invention, no crystal melting peak exists at all in the crystal melting temperature range of the above-mentioned copolymer, or if present, it exists only as a slight tailing. . The crystal melting peak (Tp) is generally in the temperature range Tm + 20 ° C to Tm + 50 ° C, especially Tm
It is usually expressed in the range of + 20 ° C. to Tm + 100 ° C., and this peak (Tp) often appears as a plurality of peaks within the above temperature range. In other words, the crystal melting peak (Tp) is defined as a high-temperature side melting peak (Tp ₁ ) in the temperature range Tm + 35 ° C. to Tm + 100 ° C.
Often appearing decomposed into two low temperature side melting peak (Tp ₂₎ at + 35 ° C., depending on the production conditions of molecular orientation moldings, also Tp ₁ and Tp ₂ consists further plurality of peaks is there.

These high crystal melting peaks (Tp ₁ , Tp ₂ ) significantly improve the heat resistance of the molecularly oriented molded product of ultra-high molecular weight ethylene / α-olefin copolymer, and maintain the strength after a high-temperature heat history. Alternatively, it seems to contribute to the elastic modulus retention.

The total heat of fusion based on the high-temperature side melting peak (Tp ₁ ) in the temperature range Tm + 35 ° C. to Tm + 100 ° C. is desirably 1.5% or more, particularly 3.0% or more, based on the total heat of fusion.

In addition, as long as the sum of the heats of fusion based on the high-temperature side melting peak (Tp ₁ ) satisfies the above-mentioned value, when the high-temperature side melting peak (Tp ₁ ) does not protrude as a main peak, Even if an aggregate or a broad peak occurs, the heat resistance may be slightly lost, but the creep resistance is excellent.

The melting point and the heat of crystal fusion in the present invention were measured by the following methods.

The melting point was determined by a differential scanning calorimeter as follows. As a differential scanning calorimeter, DSC II type (manufactured by PerkinElmer) was used. Approximately 3 mg of the sample was wrapped around a 4 mm x 4 mm, 0.2 mm thick aluminum plate to restrain it in the orientation direction. Next, the sample wound around the aluminum plate was sealed in an aluminum pan to obtain a sample for measurement. Normally, the same aluminum plate as that used for the sample was sealed in an empty aluminum pan to be placed in the reference holder, and the heat balance was maintained. First, place the sample at 30 ° C for about 1
Then, the temperature was raised to 250 ° C. at a rate of 10 ° C./min, and the melting point measurement at the first temperature rise was completed. Reading
The sample was kept at 250 ° C. for 10 minutes, then cooled at a rate of 20 ° C./min, and further kept at 30 ° C. for 10 minutes. Next, the second heating was performed at a heating rate of 10 ° C./min to 250 ° C., and at this time, the melting point measurement at the second heating (second run) was completed. At this time, the maximum value of the melting peak was defined as the melting point. When it appeared as a shoulder, a tangent was drawn at the inflection point immediately on the low temperature side and the inflection point immediately on the high temperature side of the shoulder, and the intersection point was taken as the melting point.

Further, connecting the point between 60 ° C. and 240 ° C. of the endothermic curve with the straight line (base line) and the original crystal melting temperature (Tm) of the ultra-high molecular weight ethylene copolymer obtained as the main melting peak at the second heating, Draw a perpendicular line to the point higher by ℃, and the lower part surrounded by these is based on the original crystal melting (Tm) of ultra high molecular weight ethylene copolymer, and the higher part is the function of the molded article of the present invention. Based on the crystal melting (Tp) that appeared, the heat of crystal melting was calculated from these areas. In addition, the heat of fusion based on the melting of Tp ₁ and Tp ₂ was also determined according to the method described above, with the perpendicular from Tm + 20 ° C. and Tm + 35.
A portion surrounded by a vertical line from ° C. was determined to have the heat of fusion based on the melting of Tp ₂ , and the portion on the high temperature side was determined to have the heat of fusion based on the melting of Tp ₁ .

The drawn filament of the ultrahigh molecular weight ethylene / α-olefin copolymer of the present invention has a strength retention of 95% or more and an elastic modulus retention of 90% after giving a heat history at 170 ° C. for 5 minutes.
% Or more, particularly 95% or more, and has excellent heat resistance which is not observed at all in conventional drawn filaments of polyethylene.

Method for Producing Molecularly Oriented Molded Product of Ultra-High-Molecular-Weight Polyolefin As a method for obtaining an ultra-high-molecular-weight polyolefin stretched product having high elasticity and high tensile strength as described above, for example,
JP-A-56-15408, JP-A-58-5228, JP-A-5959
No.-130313, JP-A-59-187614, etc., or dilute solution of ultra-high molecular weight polyolefin, or add low molecular weight compounds such as paraffin wax to ultra-high molecular weight polyolefin Then, a method of improving the stretchability of the ultrahigh molecular weight polyolefin and stretching at a high magnification can be exemplified.

Next, the present invention will be described below in the order of the raw materials, the production method, and the objects for easy understanding.

Raw Materials The ultrahigh molecular weight ethylene / α-olefin copolymer used in the present invention is obtained by slurry polymerizing ethylene and an α-olefin having 3 or more carbon atoms, for example, in an organic solvent using a Ziegler-based catalyst. Can be

Examples of the α-olefin having 3 or more carbon atoms include propylene, butene-1, pentene-1, and 4-methylpentene.
1, hexene-1, heptene-1, octene-1 and the like are used, and among them, butene-1, 4-methylpentene-1, hexene-1, octene-1 and the like are particularly preferable. Such α-olefins are copolymerized with ethylene such that they are present in the amounts described above per 1000 carbon atoms in the resulting copolymer. Further, the ultrahigh molecular weight ethylene / α-olefin copolymer used as a base when producing a molecular alignment body in the present invention should have a molecular weight corresponding to the intrinsic viscosity [η] described above.

The quantification of the α-olefin component in the ultrahigh molecular weight ethylene / α-olefin copolymer used in the present invention is performed by an infrared spectrophotometer (manufactured by JASCO Corporation). Specifically, the absorbance at 1378 cm ^-1 representing the bending vibration of the methyl group of the α-olefin incorporated in the ethylene chain was measured by an infrared spectrophotometer, and this value was previously measured at ¹³ C.
In a nuclear magnetic resonance apparatus, the amount of α-olefins in the ultrahigh molecular weight ethylene / α-olefin copolymer was calculated by converting the number of methyl branches per 1,000 carbon atoms into a calibration curve prepared using a model compound using a calibration curve. Is quantified.

Production Method In the present invention, a diluent is blended with the copolymer when producing a molecular orientation body from the ultrahigh molecular weight ethylene / α-olefin copolymer. Such diluents include:
A solvent for the ultrahigh molecular weight ethylene / α-olefin copolymer or various wax-like substances having dispersibility in the ultrahigh molecular weight ethylene / α-olefin copolymer is used.

As such a solvent, a boiling point higher than the melting point of the copolymer, more preferably 20 ° C. than the melting point of the copolymer
A solvent having a higher boiling point is used.

As such a solvent, specifically, n-nonane,
n-decane, n-undecane, n-dodecane, n-tetradecane, n-octadecane or liquid paraffin,
Aliphatic hydrocarbon solvents such as kerosene, xylene, naphthalene, tetralin, butylbenzene, p-cymene, cyclohexylbenzene, diethylbenzene, ventilbenzene, dodecylbenzene, dicyclohexyl, decalin,
Aromatic hydrocarbon solvents such as methylnaphthalene and ethylnaphthalene or hydrogenated derivatives thereof, 1,1,2,2-tetrachloroethane, pentachloroethane, hexachloroethane, 1,2,3-trichloropropane, dichlorobenzene,
Halogenated hydrocarbon solvents such as 1,2,4-trichlorobenzene and bromobenzene; and mineral oils such as paraffin-based process oils, naphthene-based process oils, and aromatic-based process oils.

As the wax as the diluent, specifically, an aliphatic hydrocarbon compound or a derivative thereof is used.

As such an aliphatic hydrocarbon compound, a compound called a paraffin-based wax mainly containing a saturated aliphatic hydrocarbon compound and having a molecular weight of 2,000 or less, preferably 1,000 or less, more preferably 800 or less is used.

Specific examples of such an aliphatic hydrocarbon compound include n-alkanes having 22 or more carbon atoms, such as docosane, tricosan, tetracosane, and triacontan, and mixtures thereof with lower n-alkanes containing these as a main component, and petroleum. So-called paraffin wax separated and purified from ethylene, medium or low pressure polyethylene wax, which is a low molecular weight polymer obtained by copolymerizing ethylene or ethylene and other α-olefin, high pressure polyethylene wax, ethylene copolymer wax or medium Waxes obtained by reducing the molecular weight of polyethylene such as low-pressure polyethylene and high-pressure polyethylene by thermal degradation or the like; oxides of these waxes; oxidized waxes such as maleic acid-modified wax; maleic acid-modified wax;

As the aliphatic hydrocarbon compound derivative, for example, one or more, preferably 1 to 2, terminal or internal terminal of an aliphatic hydrocarbon group (alkyl group, alkenyl group)
, More preferably one compound having a functional group such as one carboxyl group, hydroxyl group, carbamoyl group, ester group, meltcapto group, carbonyl group, etc., having 8 or more carbon atoms, preferably 12 to 50 carbon atoms or a molecular weight of 130 to 2000. Preferably, 200 to 800 fatty acids, aliphatic alcohols, fatty acid amides, fatty acid esters, aliphatic mercaptans, aliphatic aldehydes, aliphatic ketones and the like are used.

As such aliphatic hydrocarbon compound derivatives, specifically, capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, fatty acids such as oleic acid,
Examples thereof include aliphatic alcohols such as lauric alcohol, myristyl alcohol, cetyl alcohol, and stearyl alcohol; fatty acid amides such as caprinamide, laurinamide, paramitinamide, and stearylamide; and fatty acid esters such as stearyl acetate.

The ultra-high molecular weight ethylene / α-olefin copolymer and the diluent differ depending on these types, but generally,
It is used in a weight ratio of 3:97 to 80:20, particularly 15:85 to 60:40. If the amount of the diluent is lower than the above range, the melt viscosity becomes too high, so that melt-kneading and melt-molding become difficult, and the obtained molded article is extremely rough, and is liable to cause stretch breakage and the like. On the other hand, when the amount of the diluent is more than the above range, melt kneading also becomes difficult, and the stretchability of the obtained molded article becomes poor.

Melt kneading is generally performed at a temperature of 150 to 300 ° C, especially 170 to 270 ° C. At a temperature lower than the above range, the melt viscosity is too high and melt molding becomes difficult. When the temperature is higher than the above range, ultra-high molecular weight ethylene
The molecular weight of the α-olefin copolymer decreases, and it becomes difficult to obtain a molded article having excellent high elastic modulus and high strength. The compounding may be performed by dry blending using a Henschel mixer, a V-type blender, or the like, or may be performed using a single-screw extruder or a multi-screw extruder.

Melt molding of a dope (stock spinning solution) comprising an ultrahigh molecular weight ethylene / α-olefin copolymer and a diluent is generally performed by melt extrusion molding. Specifically, the dope is melt-extruded through a spinneret to obtain a drawing filament. At this time, the melt extruded from the spinneret may be drafted, that is, stretched in a molten state. The ratio of the extrusion speed V ₀ of the molten resin in the die orifice to the winding speed V of the unstretched material that has been cooled and solidified can be defined as a draft ratio by the following formula.

Draft ratio = V / V ₀ (2) Such a draft ratio varies depending on the temperature of the mixture, the molecular weight of the ultrahigh molecular weight ethylene copolymer, and the like, but can be usually 3 or more, preferably 6 or more. .

Next, the ultra-high molecular weight ethylene
The unstretched molded article of the α-olefin copolymer is stretched. Stretching is performed so that at least a uniaxial molecular orientation is effectively imparted to the unstretched molded product obtained from the ultrahigh molecular weight ethylene / α-olefin copolymer.

Stretching of an unstretched molded article obtained from an ultra-high molecular weight ethylene / α-olefin copolymer is generally performed at 40 to 160 ° C., particularly 8 ° C.
The reaction is performed at a temperature of 0 to 145 ° C. As a heat medium for heating and holding the unstretched molded body at the above temperature, air, steam,
Any of the liquid media can be used. However, as a heat medium, a solvent capable of eluting and removing the diluent described above, and a liquid medium having a boiling point higher than the melting point of the molded product composition, specifically, decalin, decane,
It is preferable to perform the stretching operation using kerosene or the like, since the above-mentioned diluent can be removed, stretching unevenness does not occur during stretching, and a high stretching ratio can be achieved.

Means for removing the diluent from the ultra-high molecular weight ethylene / α-olefin copolymer is not limited to the above-described method, and a method of stretching an unstretched material after treatment with a solvent such as hexane, heptane, hot ethanol, chloroform, or benzene, By removing the diluent in the molded product, a stretched product having a high elastic modulus and a high strength can be obtained by a method of treating the stretched product with a solvent such as hexane, heptane, hot ethanol, chloroform, and benzene.

The stretching operation can be performed in one stage or in two or more stages. The stretching ratio depends on the desired molecular orientation and the effect of improving the melting temperature associated therewith.
8080 times, preferably 10 to 50 times.

In general, the stretching operation is preferably performed by two or more stages of multi-stage stretching.In the first stage, the stretching operation is performed while extracting the diluent in the extruded product at a relatively low temperature of 80 to 120 ° C. Thereafter, it is preferable to perform the stretching operation of the molded body at a temperature of 120 to 160 ° C. and higher than the first-stage stretching temperature.

In the case of a uniaxial stretching operation, the stretching may be performed between rollers having different peripheral speeds.

The thus obtained molecularly oriented molded article can be subjected to a heat treatment under constrained conditions, if desired. This heat treatment is generally at a temperature of 140-180 ° C, preferably 150-175 ° C,
It can be carried out for 1 to 20 minutes, preferably 3 to 10 minutes.
By the heat treatment, the crystallization of the oriented crystal part further progresses, the crystal melting temperature shifts to a high temperature side, the strength and the elastic modulus improve,
Furthermore, an improvement in creep resistance at high temperatures is provided.

In the present invention, the ultra-high molecular weight ethylene α-
The fibrous molecularly oriented molded article of the olefin copolymer is used as a cement admixture, and the length of the fibrous molecularly oriented molded article is about 5 to 100 mm, preferably about 10 to 70 mm,
The fiber diameter is about 2 to 100 μm, preferably about 10 to 50 μm.

As the cement to which the cement admixture according to the present invention is blended, ordinary Portland cement is mainly used. In addition to ordinary Portland cement, for example, alumina cement, lime alumina cement, manganese cement, chromium cement, titanium cement and other special cements are used. Can be widely used.

As the aggregate, river sand and mountain sand as fine aggregate, river gravel and crushed stone as coarse aggregate can be widely used.

The cement admixture consisting of a fibrous molecularly oriented molded product of an ultra-high molecular weight ethylene / α-olefin copolymer may be used in the cement composition in an amount of 0.5 to 10% by volume, preferably 1 to 5% by volume. desirable.

In the cement composition according to the present invention, if necessary,
In addition to the above components, a cement admixture such as an antifoaming agent, a water reducing agent, and an AE agent can also be used.

Effects of the Invention As described above, in the present invention, ultrahigh molecular weight ethylene α-
Since the molecular orientation molded product of the olefin copolymer is a cement admixture, it is lightweight, and has excellent mechanical strength, alkali resistance, abrasion resistance, weather resistance, water resistance,
In addition, it has excellent creep resistance and impact resistance.

Hereinafter, the present invention will be described with reference to examples, but the present invention is not limited to these examples.

Example 1 <Polymerization of ultrahigh molecular weight ethylene / butene-1 copolymer> Slurry polymerization of ultrahigh molecular weight ethylene / butene-1 copolymer was carried out using a Ziegler catalyst and n-decane 1 as a polymerization solvent. . A mixed monomer gas having a composition of ethylene and butene-1 in a molar ratio of 97.2: 2.35 was continuously supplied to the reactor such that the pressure was maintained at a constant pressure of 5 kg / cm ² . The polymerization was completed at a reaction temperature of 70 ° C. in 2 hours.

The yield of the obtained ultra high molecular weight ethylene / butene-1 copolymer powder was 160 g, and the intrinsic viscosity [η] (decalin: 135 ° C.)
8.2 dl / g, butene-1 content by infrared spectrophotometer is 1000
It was 1.5 per carbon atom.

<Preparation of stretched oriented product of ultrahigh molecular weight ethylene / butene-1 copolymer> 20 parts by weight of ultrahigh molecular weight ethylene / butene-1 copolymer powder obtained by the above polymerization and paraffin wax (melting point = 69 ° C., molecular weight) = 490) The mixture with 80 parts by weight was melt spun under the following conditions.

3,5-di- as a process stabilizer was added to 100 parts by weight of the mixture.
0.1 parts by weight of tert-butyl-4-hydroxytoluene was blended. Next, the mixture is fed into a screw type extruder (screw diameter = 25 mm, L / D = 25, manufactured by Thermoplastics).
And melt kneading was performed at a set temperature of 190 ° C. Subsequently, the orifice diameter 2 m attached to the extruder was added to the mixed melt.
It was melt spun from a spinning die of m. The extruded melt was drawn at a draft ratio of 36 times with an air gap of 180 cm, cooled and solidified in air to obtain an undrawn fiber. Further, the undrawn fiber was drawn under the following conditions.

Two-stage stretching was performed using three godet rolls.
At this time, the heat medium of the first stretching tank is n-decane, and the temperature is
At 110 ° C., the heat medium of the second stretching tank was triethylene glycol, and the temperature was 145 ° C. The effective length of the tank is 50c each
m. At the time of drawing, the rotation speed of the first godet roll was set to 0.5 m / min and the rotation speed of the third godet roll was changed to obtain oriented fibers having a desired drawing ratio. The rotation speed of the second godet roll was appropriately selected within a range where stable stretching was possible. Almost all of the paraffin wax initially mixed was extracted into n-decane during stretching. Thereafter, the oriented fibers were washed with water, dried under reduced pressure at room temperature for 24 hours, and used for measurement of various physical properties. The stretching ratio was calculated from the rotation speed ratio between the first godet roll and the third godet roll.

<Measurement of Tensile Properties> The elastic modulus and tensile strength were measured at room temperature (23 ° C.) using a DCS-50M tensile tester manufactured by Shimadzu Corporation.

At this time, the sample length between the clamps was 100 mm, and the pulling speed was 1
It was 00 mm / min (100% / min strain rate). The elastic modulus was calculated using the tangent slope at the initial elastic modulus. The fiber cross-sectional area required for the calculation was calculated from the weight with the density set to 0.960 g / cc.

<Tensile Elastic Modulus and Strength Retention after Thermal History> The thermal history test was performed by leaving the device in a gear oven (Perfect Oven: manufactured by Tabai Seisakusho).

The sample was about 3 m in length, and was folded over a stainless steel frame having a plurality of pulleys mounted at both ends to fix both ends of the sample. At this time, fix both ends of the sample so that the sample does not sag.
No tension was actively applied to the sample. The tensile properties after the thermal history were measured based on the description of the measurement of the tensile properties described above.

<Measurement of creep resistance> The creep resistance was measured using a TMA / SS10 thermal stress / strain measuring device (manufactured by Seiko Denshi Kogyo Co., Ltd.) with a sample length of 1 cm, an ambient temperature of 70 ° C. %, Under accelerated conditions corresponding to the weight. The following two values were obtained to quantitatively evaluate the amount of creep. That is, the creep elongation (%) CR ₉₀ at the time of 90 seconds after applying a load to the sample,
The average creep speed from this 90 seconds to 180 seconds (s
ec ^-1 ) is the value of ε.

Table 1 shows the tensile properties of a multifilament obtained by bundling a plurality of obtained oriented fibers.

The original crystal melting peak of the ultrahigh molecular weight ethylene / butene-1 copolymer drawn filament (sample-1) was 126.7
° C, the ratio of Tp to the total crystal melting peak area was 33.8%. The creep resistance is CR ₉₀ = 3.1%, ε = 3.03 × 1
It was 0 ^-5 sec ^-1 . Further, the modulus of elasticity retention after thermal history at 170 ° C. for 5 minutes was 102.2%, and the strength retention was 102.5%. No deterioration in performance due to thermal history was observed.

The work required to break the drawn filament is 10.3
a kg · m / g, density of 0.973 g / cm ^3, the dielectric constant is 2.2
The dielectric loss tangent was 0.024%, and the impulse voltage breakdown value was 180 KV / mm.

Example 2 <Polymerization of ultrahigh molecular weight ethylene-octene-1 copolymer> Slurry polymerization of ethylene was performed using n-decane 1 as a polymerization solvent using a Ziegler-based catalyst. At this time, 125 ml of octene-1 as a comonomer and 40 Nml of hydrogen for adjusting the molecular weight were added all at once before the start of the polymerization, and the polymerization was started. Ethylene gas was continuously supplied so that the pressure in the reactor was kept constant at 5 kg / cm ² , and the polymerization was completed at 70 ° C. for 2 hours. Ultra high molecular weight ethylene octene-1 obtained
The yield of the copolymer powder was 178 g, the intrinsic viscosity [η] (decalin, 135 ° C.) was 10.66 dl / g, and the octene-1 comonomer content by infrared spectrophotometry was 0.5 per 1000 carbon atoms. Was.

<Preparation of stretched oriented product of ultrahigh molecular weight ethylene / octene-1 copolymer and its physical properties> A stretched oriented fiber was prepared by the method described in Example 1. Table 2 shows the tensile properties of a multifilament obtained by bundling a plurality of obtained oriented fibers.

The original crystal melting peak of the ultrahigh molecular weight ethylene / octene-1 copolymer drawn filament (sample-2) is 132.1
° C., the proportion of Tp and Tp ₁ to the total crystal fusion peak area was 97.7% and 5.0%. The creep resistance of Sample-2 was CR ₉₀ = 2.0% and ε = 9.50 × 10 ⁻⁶ sec ⁻¹ . Further, the elastic modulus retention after a heat history at 170 ° C. for 5 minutes was 108.2%, and the strength retention was 102.1%. Further work load required to break the sample -2 was 10.1 kg · m / g, density of 0.971 g / cm ^3, a dielectric constant is 2.2, the dielectric loss tangent
0.031%, and the impulse voltage breakdown value was 185 KV / mm.

Comparative Example 1 Ultra high molecular weight polyethylene (homopolymer) powder (intrinsic viscosity [η] = 7.42 dl / g, decalin, 135 ° C): 20 parts by weight and paraffin wax (melting point = 69 ° C, molecular weight = 490):
The mixture with 80 parts by weight was melt-spun and drawn by the method of Example 1 to obtain a drawn oriented fiber. Table 3 shows the tensile properties of a multifilament obtained by bundling a plurality of obtained oriented fibers.

Ultra-high molecular weight polyethylene drawn filament (sample-
3) The original crystal melting peak was 135.1 ° C., and the ratio of Tp to the total crystal melting peak area was 8.8%. Similarly the proportion of the high temperature side peak TP ₁ to the total crystal fusion peak area was 1% or less. Creep resistance CR ₉₀ = 11.9%, ε
= 1.07 × 10 ⁻³ sec ⁻¹ . Further, the elastic modulus retention after a heat history at 170 ° C. for 5 minutes was 80.4%, and the strength retention was 78.2%. Further, the work required for breaking Sample-3 is 6.8 kg.
M / g, density was 0.985 g / cm ³ , dielectric constant was 2.3, dielectric loss tangent was 0.030%, and impulse voltage breakdown value was 182 KV / mm.

The ultra-high molecular weight ethylene / α-olefin copolymer fiber or the ultra-high molecular weight polyethylene fiber obtained in Examples 1 and 2 and Comparative Example 1 was cut into a 2-inch fiber length with a cutter,
It was chop strand. These chop strands were mixed so that the mixing amount in the cement composition was 2% by volume to prepare a portland cement admixture-dispersed cement block. The shape of the prepared admixture-dispersed cement block was 50 mm × 100 mm × 1000 mm. This was subjected to a three-point bending test with a span of 800 mm.

 Table 4 shows the results.

Table 5 shows the relationship between the drop height and the block appearance when each block was held horizontally and dropped on a hardened soil surface.

Claims (4)

(57) [Claims] Claims: 1. An ultra-high molecular weight ethylene / α-olefin copolymer having an intrinsic viscosity [η] of at least 5 dl / g, which is an ultra-high molecular weight ethylene / α-olefin copolymer molecular weight when measured with a differential scanning calorimeter. The α-olefin copolymer has at least one crystal melting peak (Tp) at a temperature at least 20 ° C. higher than the original crystal melting temperature (Tm), and the heat of crystal melting based on this crystal melting peak (Tp) is A cement admixture consisting of a molecularly oriented compact that is at least 15% of the total crystal fusion heat. 2. An ultra-high molecular weight ethylene / α-olefin copolymer having a molecular orientation of from 0.1 to 20 carbon atoms per 1,000 carbon atoms and comprising an α-olefin having 3 or more carbon atoms. A cement admixture according to claim 1. 3. The cement admixture according to claim 1, wherein the α-olefin is butene-1, 4-methylpentene-1, hexene-1, octene-1 or decene-1. 4. The cement admixture according to claim 1, wherein the content of the α-olefin is 0.5 to 10 per 1000 carbon atoms.