JPH02296756A - Cement admixture - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field of the Invention The present invention relates to a cement admixture, and more particularly, it is made of a molecularly oriented molded article of ultra-high molecular weight polyolefin, is lightweight, has high strength, has excellent water resistance, and has excellent alkali resistance. , relates to a cement admixture that has creep resistance and weather resistance, and also has excellent impact resistance and fatigue resistance.

Technical background of the invention and its problems Cement compositions such as cement concrete or cement mortar shrink and crack when drying.
There was a major problem in that not only the strength of the dried cement was greatly reduced, but also the waterproofness of the dry cement was reduced due to cracks, and its durability was reduced.

For this reason, attempts have been made to reduce the drying shrinkage of cement products by incorporating fibers such as steel fibers, polymer fibers, and carbon fibers, or polymer dispersion for cement admixture into cement compositions. However, fibers such as steel fibers, polymer fibers, and carbon fibers have various problems such as being heavy or having poor mechanical strength. Furthermore, when a cement-mixing polymer dispersion is blended into a cement composition, there is a problem in that the compressive strength of the resulting cement product decreases depending on the blending amount.

On the other hand, it is known that surfactants are added to cement compositions to reduce shrinkage; however, depending on the amount of surfactants added to cement compositions, the bending strength of the resulting cement product may be reduced. There was a problem that the compressive strength decreased.

Therefore, there has been a strong desire for a cement composition that reduces shrinkage during drying, is lightweight, and has excellent bending strength and compressive strength.

It is already known that a molecularly oriented molded article with high elastic modulus and high tensile strength can be obtained by forming ultra-high molecular weight polyethylene into fibers, tapes, etc. and stretching the fibers. For example, in Japanese Patent Application Laid-Open No. 56-15408,
Spinning dilute solutions of ultra-high molecular weight polyethylene and drawing the resulting filaments is described. Also,
JP-A-59-130313 discloses that ultra-high molecular weight polyethylene and wax are melt-kneaded, the kneaded product is extruded, cooled and assimilated, and then stretched, and JP-A-59-187614 describes , it is described that the above melt-kneaded product is extruded, drafted, cooled and solidified, and then stretched.

Purpose of the Invention The present invention aims 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. The purpose of the present invention is to provide a cement admixture with excellent fatigue resistance.

Summary of the Invention The cement admixture according to the present invention is characterized in that it is composed of a molecularly oriented molded article of ultra-high molecular weight polyolefin having an intrinsic viscosity [η] of at least 5 diJ/g, and furthermore, the cement admixture has an intrinsic viscosity [η] of at least 5 diJ/g. 5dD/g, and the content of α-olefin having 3 or more carbon atoms is 10 carbon atoms.
It is characterized by being composed of a molecularly oriented molded article of an ultra-high molecular weight ethylene/α-olefin copolymer having an average of 0.1 to 20 pieces per 00 pieces.

The cement admixture according to the present invention is made of a molecularly oriented molded product of the above-mentioned ultra-high molecular weight polyolefin or ultra-high molecular weight ethylene/α-olefin copolymer, and has excellent mechanical strength, alkali resistance, and wear resistance. It has excellent weather resistance, water resistance, and creep resistance and impact resistance.

DETAILED DESCRIPTION OF THE INVENTION The cement admixture according to the present invention will be specifically described below.

First, the molecularly oriented molded article of ultra-high molecular weight polyolefin constituting the cement admixture according to the present invention, particularly the molecularly oriented molded article of ultra-high molecular weight ethylene/α-olefin copolymer, will be explained.

The molecularly oriented molded product used in the present invention is a molecularly oriented molded product of an ultra-high molecular weight polyolefin or a molecularly oriented molded product of an ultra-high molecular weight ethylene/α-olefin copolymer.

The molecularly oriented molded product used in the present invention (the constituent ultra-high molecular weight polyolefins include ultra-high molecular weight polyethylene, ultra-high molecular weight polypropylene, ultra-high molecular weight poly-1-butene, and two or more types of α-olefins). Examples include ultra-high molecular weight copolymers such as ultra-high molecular weight copolymers, etc. This molecularly oriented molded article of ultra-high molecular weight poly No. ing.

In addition, as the ultra-high molecular weight ethylene/α-olefin copolymer constituting the molecularly oriented molded product used in the present invention,
Ultra-high molecular weight ethylene/propylene copolymer, ultra-high molecular weight ethylene/l-butene copolymer, ultra-high molecular weight ethylene/l-butene copolymer,
4-methyl-1-pentene copolymer, ultra-high molecular weight ethylene/l-hexene copolymer, ultra-high molecular weight ethylene/l-
Octene copolymers, ultra-high molecular weight ethylene/l-decene copolymers, etc. with ethylene and carbon atoms of 3 to 20. Preferred examples include ultra-high molecular weight ethylene/σ-olefin copolymers with 4 to 10 α-olefins.

In this ultra-high molecular weight ethylene/α-olefin copolymer, the number of α-olefins having 3 or more carbon atoms is preferably 0.1 to 20 per 1000 carbon atoms of the polymer1, and < is 0.5 to 20.
It is contained in an amount of 10, more preferably 1 to 7.

Molecularly oriented molded products obtained from such ultra-high molecular weight ethylene/α-olefin copolymers have particularly excellent impact resistance and creep resistance compared to molecularly oriented molded products obtained from ultra-high molecular weight polyethylene. . This ultra-high molecular weight ethylene/α-olefin copolymer is lightweight and has high strength, and has excellent alkali resistance, abrasion resistance, impact resistance, and creep resistance, as well as excellent weather resistance, water resistance, and salt water resistance. ing.

The ultra-high molecular weight polyolefin or ultra-high molecular weight ethylene/α-olefin copolymer constituting the molecularly oriented molded product used in the present invention has an intrinsic viscosity [η] of 5 dR/g or more, preferably in the range of 7 to 30 dlQ/g. The molecularly oriented molded product obtained from this copolymer has excellent mechanical properties and heat resistance. That is, since molecular terminals do not contribute to fiber strength and the number of molecular terminals is the reciprocal of the molecule ff1 (viscosity), a material with a large intrinsic viscosity [η] gives high strength.

The density of the molecularly oriented molded product used in the present invention is 0.94
0-0.990g/- preferably 0.960-0.98
5sr/-. Here, the density is determined by the standard method (ASTM D
1505) by the density gradient tube method. The density gradient tube at this time was prepared by using carbon tetrachloride and toluene, and the measurement was performed at room temperature (23° C.).

Dielectric constant (IKHz
, 23°C) is 1.4 to 3.0, preferably 1.8 to 2.
4, positive voltage contact (lKHz.

80°C) is 0.05 to 0.008%, preferably 0.0
It is 40-0.010%. Here, the dielectric constant and positive voltage junction are determined using ASTM
Measured by D150.

The stretching ratio of the molecularly oriented molded product used in the present invention is 5 to
80 times, preferably 10 to 50 times.

The degree of molecular orientation in the molecularly oriented molded product used in the present invention can be determined 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, the degree of orientation according to the half value "11" described in detail in Yukichi Go, Teruichi Kubo: Industrial Chemistry Magazine, Vol. 39, p. 992 (1939), The degree of orientation (F) defined by the formula (where Ho is the half-width (°) of the intensity distribution curve along the Debye ring of the strongest paratropic plane on the equator) is 0.90 or more, especially 0.9
From the viewpoint of mechanical properties, it is desirable that the molecules be oriented so that the number of particles is 5 or more.

Furthermore, the molecularly oriented molded product used in the present invention has excellent mechanical properties, such as an elastic modulus of 200 Pa or more, especially 30 GPa or more in the form of a drawn filament, and 1. ．． It has a tensile strength of 2 GPa or more, especially 1.5 GPa or more.

The impulse voltage breakdown value of the molecularly oriented 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 using the same sample as in the case of dielectric constant, using a brass (25 mraφ) JIS type electrode on a copper plate, and increasing the voltage while applying a negative impulse in steps of 2 KV/3 times.

When the molecularly oriented molded product used in the present invention is a molecularly oriented molded product of an ultra-high molecular weight ethylene/α-olefin copolymer, this molecularly oriented molded product has remarkable impact resistance, breaking energy, and creep resistance. It has excellent characteristics. The characteristics of the molecularly oriented molded products of these ultra-high molecular weight ethylene φα-olefin copolymers are expressed by the following physical properties.

The breaking energy of the molecularly oriented molded product of ultra-high molecular weight ethylene/α-olefin copolymer used in the present invention is 8
kg-m/g or more, preferably 10 kg-m/g or more.

Furthermore, the molecularly oriented molded product of the ultra-high molecular weight ethylene/α-olefin copolymer used in the present invention has excellent creep resistance. In particular, it has outstanding creep resistance at high temperatures, which corresponds to the conditions that promote creep at room temperature.
The load is 30% breaking load, the ambient temperature is 70°C, the creep calculated as elongation (%) after 90 seconds is 7% or less, especially 5% or less, and the creep rate after 90 seconds to 180 seconds ( ε, 5ec-') is 4X10-4s
ec or less, particularly 5 X 10-5 sec-' or less.

Among the molecularly oriented materials used in the present invention, the molecularly oriented materials of ultra-high molecular weight ethylene/α-olefin copolymers have the above-mentioned room temperature properties, but in addition to these room temperature properties, they also have the following properties: It is preferable that the material has the following thermal properties, since the above-mentioned room temperature physical properties are further improved and heat resistance is also excellent.

The molecularly oriented molded product of the ultra-high molecular weight ethylene/α-olefin copolymer used in the present invention has at least one crystal melted at a temperature at least 20°C higher than the original crystal melting temperature (Tm) of the copolymer. The heat of fusion based on the peak (T I) is 15% or more, preferably 20% or more, especially 30% or more
% or more.

Ultra-high molecular weight ethylene copolymer original crystal melting temperature (T
m) is by completely melting this molded body and then cooling it.
A method of raising the temperature again after relaxing the molecular orientation in the compact, the so-called second heating method in a differential scanning calorimeter.
It can be found by running.

To explain further, in the molecularly oriented molded article of the present invention, there is no crystal melting peak at all in the above-mentioned crystal melting temperature range inherent to the copolymer, or even if it exists, it exists only as a very slight tailing. . Crystal melting peak (
T11) is generally within the temperature range +20°C to Tl11+
It usually appears in the region of 50°C, especially Tm+20°C to Tm+100°C, and this peak (Tp) often appears as a plurality of peaks within the above temperature range.

That is, this crystal melting peak (Tp) includes a high temperature side melting peak (Tp 1) in the temperature range Tm+35°C to TI1+100°C, and a high temperature side melting peak (Tp 1) in the temperature range Tm+20°C to Tm+3
It often appears as two separate peaks, the melting peak on the low temperature side (Tp2) at 5°C, and depending on the manufacturing conditions of the molecularly oriented molded product, Tp and TIE2 may further consist of a plurality of peaks.

These high crystal melting peaks (Tp, Tp2) are
It is believed that this significantly improves the heat resistance of molecularly oriented molded articles of ultra-high molecular weight ethylene/α-olefin copolymers, and also contributes to strength retention or elastic modulus retention after high-temperature thermal history.

Further, it is desirable that the sum of the 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 1.596 or more, particularly 3.0% or more, based on the total heat of fusion.

In addition, as long as the sum of the heat of fusion based on the high temperature side melting peak (Tpt) satisfies the above value, if the high temperature side melting peak (Tpx) does not stand out as a main peak, in other words, it is a collection of small peaks. Alternatively, even if the peak becomes broad, the heat resistance may be slightly lost, but the creep resistance is excellent.

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

The melting point was determined using a differential scanning calorimeter as follows.

Differential scanning calorimeter is DSCII type (manufactured by Perkin Elma)
was used. The sample is approximately 3 mg in a 4 mm x 4 mm
The orientation direction was restrained by wrapping the film around an aluminum plate having a thickness of 0.2. Next, the sample wrapped around an aluminum plate was sealed in an aluminum pan and used as a measurement sample. Also, the empty aluminum pan that is usually placed in the reference holder contains
The same aluminum plate used for the sample was enclosed to maintain heat balance. First, the sample was held at 30°C for about 1 minute, and then
The temperature was raised to 250°C at a heating rate of °C/min, and the melting point measurement at the first temperature rise was completed. Subsequently, the temperature was maintained at 250"C for 10 minutes, then the temperature was lowered at a rate of 20°C/min, and the sample was further held at 30°C for 10 minutes.

Then, the second temperature increase was made to 250°C at a heating rate of 10°C/min.
At this time, the melting point measurement during the second temperature increase (second run) was completed. At this time, the maximum value of the melting peak was taken as the melting point. When it appears as a shoulder, a tangent is 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 is taken as the melting point.

In addition, the straight line (
Draw a perpendicular line to a point 20°C higher than the original crystalline melting temperature (Tm) of the ultra-high molecular weight ethylene copolymer, which is determined as the main melting peak during the second temperature rise, and the area on the low temperature side surrounded by these. is based on the crystalline melting (T m) inherent in the ultra-high molecular weight ethylene copolymer, and the high temperature side part is based on the crystalline melting (T m ) that exhibits the function of the molded article of the present invention.
The heat of fusion of each crystal was calculated from these areas. Also, Tpl and TI
) The heat of fusion based on the melting of 2 was also determined according to the method described above,
The part surrounded by the perpendicular line from 11+20°C and the perpendicular line from Tm+35°C was taken as the heat of fusion based on the melting of Tp2, and the high temperature side part was calculated in the same way as the heat of fusion based on the melting of Tpl.

The drawn filament of the ultra-high molecular weight ethylene/α-olefin copolymer of the present invention has a strength retention rate of 9596 or more after being subjected to a heat history of 5 minutes at 170°C, an elastic modulus retention rate of 90% or more, In particular, it has an excellent heat resistance of 9596 or higher, which is completely unrecognizable in conventional drawn polyethylene filaments.

Method for producing molecularly oriented molded product of ultra-high molecular weight polyolefin As a method for obtaining the above-mentioned drawn ultra-high molecular weight polyolefin product having high elasticity and high tensile strength, for example, JP-A No. 5
6-15408 Publication 1, JP-A-58-5228, JP-A-59-130313, JP-A-59-18
The stretchability of ultra-high molecular weight polyolefin can be improved by making ultra-high molecular weight polyolefin into a dilute solution, or by adding a low molecular weight compound such as paraffin wax to ultra-high molecular weight polyolefin, as described in detail in Publication No. 7614. An example of an improved method for stretching to a high magnification can be given.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in the order of raw materials, manufacturing method, and purpose for easy understanding.

Raw Materials The ultra-high molecular weight ethylene/α-olefin copolymer used in the present invention is produced by slurry polymerizing ethylene and an α-olefin having 3 or more carbon atoms using a Ziegler catalyst, for example, in an organic solvent. can get.

As the α-olefin having 3 or more carbon atoms, propylene,
butene-1, pentene-1,4-methylpentene-■,
Hexene-1, heptene-11octene-1, etc. are used, and among these, butene-1,4-methylpentene-11hexene-11octene-1 and the like are particularly preferred.

Such α-olefins are copolymerized with ethylene in the amount stated above per 1000 carbon atoms of the resulting copolymer. Further, the ultra-high molecular weight ethylene/α-olefin copolymer used as a base when producing the molecularly oriented product in the present invention should have a molecular weight corresponding to the above-mentioned intrinsic viscosity [η].

The α-olefin component in the ultra-high molecular weight ethylene/α-olefin copolymer used in the present invention is determined using an infrared spectrophotometer (manufactured by JASCO Corporation). Specifically, the absorbance at 1378 cm-', which represents the bending vibration of the methyl group of the α-olefin incorporated into the ethylene chain, was measured using an infrared spectrophotometer, and this value was determined in advance by 13c nuclear magnetic resonance. Using the equipment, quantify the amount of α-olefin in the ultra-high molecular weight ethylene/α-olefin copolymer by converting it into the number of methyl branches per 1000 carbon atoms using a calibration curve created using a model compound. .

Production method In the present invention, when producing a molecularly oriented body from the ultra-high molecular weight ethylene/α-olefin copolymer, a diluent is blended into the copolymer. As such a diluent (17), a solvent for the ultra-high molecular weight ethylene copolymer or various wax-like substances having compatibility with the ultra-high molecular weight ethylene copolymer are used.

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

Specifically, in 17 with such a solvent, n-nonane,
n-decane, n-undecane, I+-dodecane, n-tetradecane, n-octadecane or liquid paraffin, aliphatic hydrocarbon solvents such as kerosene, xylene, naphthalene, tetralin, butylbenzene, p-cymene, cyclohexylbenzene, diethylbenzene , pentylbenzene, dodecylbenzene, bicyclohexyl, decalin,
Aromatic hydrocarbon solvents such as methylnaphthalene and ethylnaphthalene or hydrogenated derivatives thereof, 1,1.2.2-
Halogenated hydrocarbon solvents such as tetrachloroethane, pentachloroethane, hexachloroethane, 1.2.3-trichloropropane, dichlorobenzene, 1.2.4-trichlorobenzene, bromobenzene, paraffinic process oil, naphthenic process oil, Examples include mineral oils such as aromatic process oils.

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

Such aliphatic hydrocarbon compounds are mainly composed of saturated aliphatic hydrocarbon compounds, and are usually compounds called paraffin waxes having a molecular weight of 2,000 or less, preferably 1,000 or less, more preferably 800 or less.

Examples of such aliphatic hydrocarbon compounds include n-alkanes having 22 or more carbon atoms such as tocosan, tricosane, tetracosane, and triacontane, mixtures of these with lower n-alkanes as main components, petroleum So-called paraffin wax separated and purified from ethylene or low molecular weight polymer obtained by copolymerizing ethylene with other α-olefins, medium/low pressure polyethylene wax, high pressure polyethylene wax, ethylene copolymer wax or medium・Waxes made by lowering the molecular weight of polyethylene such as low-pressure polyethylene and high-pressure polyethylene through heat degradation, oxides of these waxes, or oxidized waxes and waxes modified with maleic acid, maleic acid-modified waxes, etc. are used. It will be done.

Examples of aliphatic hydrocarbon compound derivatives include, for example, one or more carboxyl groups, preferably one to two carboxyl groups, particularly preferably one carboxyl group, at the terminal or inside of an aliphatic hydrocarbon group (alkyl group, alkenyl group), A compound having a functional group such as a hydroxyl group, a carbamoyl group, an ester group, a meltcapto group, or a carbonyl group with a carbon number of 8 or more, preferably a carbon number of 12 to 50 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, etc. are used.

Examples of such aliphatic hydrocarbon compound derivatives include fatty acids such as capric acid, lauric acid, myristic acid, valmitic acid, stearic acid, and oleic acid, lauric alcohol, myristyl alcohol, cetyl alcohol, and stearyl alcohol. Fatty acid amides such as caprinamide, lauramide, palmitinamide, and stearylamide, fatty acid esters such as stearyl acetate, and the like are used.

The ultra-high molecular weight ethylene/α-olefin copolymer and diluent differ depending on their type, but -
=97~80:20, especially 15:85~60:40
used in a weight ratio of If the amount of the diluent is lower than the above range, the melt viscosity will become too high, making melt kneading and melt molding difficult, and the resulting molded product will have a markedly rough surface and is prone to stretch breakage. On the other hand, if the amount of the diluent is larger than the above range, melt-kneading will become difficult, and the resulting molded product will have poor stretchability.

Melting crosstalk is generally 150~300℃, especially 170~2
It is carried out at a temperature of 70°C. If the temperature is lower than the above range, the melt viscosity will be too high and melt molding will be difficult, and if the temperature is higher than the above range, the molecular weight of the ultra-high molecular weight ethylene/α-olefin copolymer will decrease due to thermal degradation. death,
It becomes difficult to obtain a molded article having excellent high elastic modulus and high strength. The blending may be done by dry blending using a Henschel mixer V-type blender, etc.
Alternatively, it may be carried out using a single screw extruder or a multi-screw extruder.

Melt molding of a dope (spinning stock solution) comprising an ultra-high molecular weight ethylene/α-olefin copolymer and a diluent is generally performed by melt extrusion molding. Specifically, filaments for drawing are obtained by melt extruding the dope through a spinneret.

At this time, the molten material extruded from the spinneret may be drafted, that is, drawn in the molten state. Extrusion speed V of the molten resin within the die orifice. The ratio of the winding speed V of the cooled and solidified undrawn material can be defined as a draft ratio by the following formula.

Draft ratio -V/vo (2) This draft ratio varies depending on the temperature of the mixture, the molecular weight of the ultra-high molecular weight ethylene copolymer, etc., but is usually 3 or more, preferably 6 or more. can.

Next, the ultra-high molecular weight ethylene α obtained in this way
- Stretching the unstretched molded olefin copolymer. Stretching is carried out so as to effectively impart at least uniaxial molecular orientation to the unstretched molded article obtained from the ultra-high 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 carried out at a temperature of 40 to 160°C, particularly 80 to 145°C. As a heat medium for heating and maintaining the unstretched molded body at the above-mentioned temperature, any of air, water vapor, and a liquid medium can be used. However, as a heating medium, a liquid medium that can elute and remove the diluent described above and whose boiling point is higher than the melting point of the molded body composition, specifically, decalin,
It is preferable to carry out the stretching operation using decane, kerosene, or the like, as this makes it possible to remove the diluent described above, prevents uneven stretching during stretching, and enables achievement of a high stretching ratio.

The means for removing the diluent from the ultra-high molecular weight ethylene/α-olefin copolymer is not limited to the above-mentioned method, but may include a method of treating an unstretched material with a solvent such as hexane, heptane, hot ethanol, chloroform, or benzene, and then stretching it; A stretched product with high elastic modulus and high strength can also be obtained by removing the diluent in the molded product by treating the stretched product with a solvent such as hexane, heptane, hot ethanol, chloroform, or benzene.

The stretching operation can be performed in one stage or in multiple stages of two or more stages. The stretching ratio depends on the desired molecular orientation and the associated effect of increasing the melting temperature, but is generally between 5 and 5.
80 times, preferably 10 to 50 times.

In general, it is preferable to carry out the stretching operation in two or more stages, and in the -th stage, the stretching operation is carried out while extracting the diluent in the extrudate at a relatively low temperature of 80 to 120°C. From the second stage onward, it is preferable to stretch the molded body at a temperature of 120 to 160°C, and at a temperature higher than the first stage stretching temperature.

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

The molecularly oriented molded product thus obtained can be heat-treated under restrictive conditions if desired.

This heat treatment is generally carried out at a temperature of 140 to 180'C, preferably 150 to 175'C, for 1 to 20 minutes, preferably 3 to 30 minutes.
This can be done for ~10 minutes. The heat treatment further advances the crystallization of the oriented crystal parts, shifts the crystal melting temperature to a higher temperature side, improves the strength and elastic modulus, and further improves the creep resistance at high temperatures.

In the present invention, a fibrous molecularly oriented molded article of ultra-high molecular weight polyolefin or an ultra-high molecular weight ethylene α-
A fibrous molecularly oriented molded product of an olefin copolymer is used as a cement admixture, and the length of this fibrous molecularly oriented molded product is about 5 to 100 mm, preferably about 10 to 70 mm, and the fiber diameter is from 2 to 100μ preferably 10-50μ
That's about it.

As the cement in which the cement admixture according to the present invention is mixed, ordinary Portland cement is mainly used, but other than ordinary Portland cement, there are also special cements such as alumina cement, lime alumina cement, manganese cement, chromium cement, and titanium cement. can also be widely used.

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

A cement admixture consisting of a fibrous molecularly oriented molded product of ultra-high molecular weight polyolefin or a fibrous molecularly oriented molded product of ultra-high molecular weight ethylene/α-olefin copolymer is contained in the cement composition in an amount of 0.5 to 10% by volume. Preferably, it is used in an amount of 1 to 5% by volume.

In addition to the above components, cement admixtures such as antifoaming agents, water reducing agents, and AE agents can also be used in the cement composition according to the present invention, if necessary.

Effects of the Invention As described above, in the present invention, the molecularly oriented molded product of ultra-high molecular weight polyolefin and the molecularly oriented molded product of ultra-high molecular weight ethylene/α-olefin copolymer are used as cement admixtures, so they are lightweight and Moreover, it has excellent mechanical strength, alkali resistance, abrasion resistance, weather resistance, and water resistance, as well as excellent creep resistance and impact resistance.

EXAMPLES The present invention will be explained below with reference to Examples, but the present invention is not limited to these Examples.

Example 1 <Polymerization of ultra-high molecular weight ethylene/butene-1 copolymer> Slurry polymerization of ultra-high molecular weight ethylene/butene-1 copolymer was performed using a Ziegler catalyst and 1 g of n-decane as a polymerization solvent. . A mixed monomer gas containing ethylene and butene-1 in a molar ratio of 97.2:2.35 was continuously supplied to the reactor so as to maintain a constant pressure of 5 kg/cd. Polymerization was completed in 2 hours at a reaction temperature of 70°C.

The yield of the obtained ultra-high molecular weight ethylene/butene-■ copolymer powder was 160 g, and the intrinsic viscosity [η] (decalin: 13
5℃) is 8. 2 dff/g, butene-1 content by infrared spectrophotometer was 1.5 per 1000 carbon atoms.

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

3.5- as a process stabilizer to 100 parts by weight of the mixture.
Di-tert-butyl-4-hydroxytoluene 0
．． 1 part by weight was added. Next, the mixture was melt mixed using a screw extruder (screw diameter -25 Dragon, L/D-25, manufactured by Thermoplastics) at a set temperature of 190°C. Subsequently, the mixed melt was melt-spun using a spinning die with two orifice diameters attached to the extruder. The extrusion melt was taken off at a draft ratio of 36 times with an air gap of 180 marks, cooled and solidified in air, and undrawn fibers were obtained. Furthermore, the undrawn fibers were drawn under the following conditions.

Two-stage stretching was performed using a Godetstrol made by Ohdai. At this time, the heat medium in the first drawing tank is n-decane, and the temperature is 1
The heating medium in the second drawing tank was triethylene glycol, and the temperature was 145°C. The effective length of each tank was 50 marks.

During stretching, the rotational speed of the first godet roll is set to 0.
By changing the rotational speed of the third godet roll to 5 m/min, oriented fibers with a desired drawing ratio were obtained. The rotational speed of the second godet roll was appropriately selected within a range that allowed stable stretching. Almost all of the initially mixed paraffin wax was extracted into n-decane during stretching. After that, the oriented fibers were washed with water, dried under reduced pressure at room temperature for a day and night, and measured for various physical properties.The drawing ratio was calculated by calculating 51 from the rotational speed ratio of the first godet roll and the third godet roll. Ta.

<Measurement of tensile properties> Elastic modulus and tensile strength were measured at room temperature (23° C.) using a DC350M tensile tester manufactured by Shimadzu Corporation.

At this time, the sample length between the clamps was 100 mm, and the tensile rate was 100 mm/min (100%/min strain rate).

The elastic modulus was calculated using the slope of the tangent at the initial elastic modulus. The fiber cross-sectional area required for the calculation was calculated from the weight, assuming a density of 0.960 g/cc.

<Tensile modulus and strength retention after heat history> The heat history test was conducted by leaving the sample in a gear oven (manufactured by Perfect Oven Nitabai Seisakusho).

The sample had a length of about 3 m, and was folded over a stainless steel frame equipped with a plurality of pulleys at both ends to fix both ends of the sample. At this time, both ends of the sample were fixed to the extent that the sample did not sag, and 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.

1111 constant for creep resistance> 71 PI constant for creep resistance was determined by thermal stress strain measuring device TMA/
Using 5S10 (manufactured by Seiko Electronic Industries), sample length 1
mark, the ambient temperature is 70℃, the load is 30% of the breaking load at room temperature.
% by weight under accelerated conditions. In order to quantitatively evaluate the amount of creep, the following two values were determined. That is, the values are the value of creep elongation (%) CR9° when 90 seconds have elapsed after applying a load to the sample, and the value of the average creep rate (see-') ε when 180 seconds have elapsed from the time when 90 seconds have elapsed.

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

The original crystal melting peak of ultra-high molecular weight ethylene-butene-1 copolymer drawn filament (Sample-1) is 126.7
℃, the ratio of Tp to the total crystal melting peak area is 33.
It was 8%. Also creep resistance g, tCR-3.1%
, ε=3.03X10-"sea-'.Furthermore, the elastic modulus retention after heat history at 170°C for 5 minutes was 102.
2%, the strength retention rate was 102.5%, and no deterioration in performance due to thermal history was observed.

Also, the amount of work required to break the drawn filament is 10.
3 kg-m7g, density was 0.973 g/-, dielectric constant was 2.2, dielectric voltage contact was 0.024%, and impulse voltage breakdown value was 180 KV/fin.

Example 2 Polymerization of ultra-high molecular weight ethylene/octene-1 copolymer Ethylene slurry polymerization was carried out using a Ziegler catalyst and 1 g of n-decane as a polymerization solvent.

At this time, 125 ml of octene-■ as the conjugate m-form and 4 ON ml of hydrogen for adjusting the molecular weight were added all at once before starting the polymerization to start the polymerization. Ethylene gas was continuously supplied to the reactor to maintain a constant pressure of 5 kg/cd, and the polymerization was completed at 70°C for 2 hours.

The yield of the obtained ultra-high molecular weight ethylene/octene-1 copolymer powder was 178 g, and its intrinsic viscosity [η] (decalin,
135°C) is 10.66 dg/g.

The octene-1 comonomer content by infrared spectrophotometer is 10
The number was 0.5 per 00 carbon atoms.

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

The original crystal melting peak of the ultra-high molecular weight ethylene/octene-1 copolymer drawn filament (Sample-2) was 132.
Tp and Tpl relative to total crystal melting peak area at 1°C
The percentages were 97.7% and 5.0%, respectively.

The creep resistance of sample-2 is CR-2.0%, ε=9
, 50 x 10-6 sec-'. Also, 1
The elastic modulus retention after heat history at 70°C for 5 minutes was 108.
2%, and the strength retention rate was 102.1%. Furthermore, the amount of work required to fracture Sample-2 is 10.1 kg-m/y, the density is 0.971 g/-, the dielectric constant is 2.2, and the dielectric loss tangent is 0.031%. The impulse voltage breakdown value was 185 KV/mm.

Example 3 Ultra-high molecular weight polyethylene (homopolymer) powder (intrinsic viscosity [η] -7.42 dfI/g, Decalin, 135°C
): 20 parts by weight, paraffin wax (melting point -69°C
, molecular weight -490): 80 parts by weight in Example 1
The fibers were melt-spun and drawn using the method described above to obtain drawn-oriented fibers. Table 3 shows the tensile properties of the multifilament obtained by bundling a plurality of drawn and 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 high temperature side peak Tpt with respect to the total crystal melting peak area
The proportion was less than 1%. Creep resistance is CH2O-
11.9%, ε-1,07X 10-3sec-"'r
there were. Further, after heat history at 170° C. for 5 minutes, the elastic modulus retention rate was 80.4% and the strength retention rate was 78.2%.

Furthermore, the amount of work required to break sample-3 is 6.8 kg・m
/g, the density was 0.985 g/-, the dielectric constant was 2.3, the dielectric voltage junction was 0.030%, and the impulse voltage breakdown value was 182 KV/mm.

The ultra-high molecular weight polyethylene fibers obtained in Examples 1 to 3 were cut into 2-inch fiber lengths using a cutter to obtain chopped strands. These chopped strands were mixed into the cement composition in an amount of 2 volumes 96 to prepare a Portland cement admixture dispersed cement block. The shape of the prepared admixture-dispersed cement block was 50
mm x100mm+x1000mm. A three-point bending test was performed on this in order of 800 spans.

The results are shown in Table 4.

Table 4 Table 5 shows the relationship between the falling height and the block appearance when each block was held horizontally and dropped onto a hardened soil surface.

Table 5 A: Block C using the admixture of Example 1: Block C using the admixture of Example 2: Block D using the admixture of Example 3: Block O using no admixture: Visually No cracks on the exterior △: Cracks on the exterior visually observed X: Damaged

Claims (1)

[Scope of Claims] 1) A cement admixture comprising a molecularly oriented molded article of ultra-high molecular weight polyolefin having an intrinsic viscosity [η] of at least 5 dl/g. 2) Ultra-high molecular weight ethylene α- having an intrinsic viscosity [η] of at least 5 dl/g and containing an average of 0.1 to 20 α-olefins having 3 or more carbon atoms per 1000 carbon atoms. A cement admixture made of a molecularly oriented molded olefin copolymer. 3) α-olefin is butene-1,4-methylpentene-1, hexene-1, octene-1 or decene-1
The cement admixture according to claim 2. 4) The cement admixture according to claim 2, wherein the content of α-olefin is on average 0.5 to 10 per 1000 carbon atoms.