JPS5818343B2 - Compounds for cement - Google Patents

Description

[Detailed description of the invention] The present invention relates to cement formulations.

More specifically, the initial elastic modulus is 250 to 400 kg/
This invention relates to a cement formulation prepared by cutting an embossed stretched polyolefin tape having an average thickness of 0.2 to 1 mm into appropriate lengths.

It has been known to mix synthetic resin fibers, split fibers, metal edge J fibers, glass fibers, etc. with the aim of improving the bending strength, crack resistance, etc. of cement products.

However, among these fibers, for example, synthetic resin fibers do not mix well with cement, and the fibers intertwine with each other and are difficult to disperse in cement, which often causes uneven strength in cement products.

stomach.

Moreover, since the shape is simple, it easily comes off when bending stress is applied, and the reinforcing effect is not sufficient.

Furthermore, synthetic resin split fibers have a complex shape and are thought to have a greater physical bond with the cement, but in reality they are kneaded into the cement in a bent state, so their reinforcing effect is not as great. .

Furthermore, since the split fibers themselves are bulky, they have the disadvantage of being difficult to disperse uniformly.

Metal fibers and glass fibers have a relatively good affinity with cement and can provide a considerable reinforcing effect, but they are expensive and the fibers are highly entangled, so special defibration machines or mixers, such as fiber dispensers, are required. , an omni mixer, an auger mixer, etc. were required.

The present invention has been made in view of the above points, and it is an object of the present invention to provide a cement compound that is easily dispersed in cement and has an excellent reinforcing effect.

The polyolefins used in the present invention include, for example, ethylene, pyrene, ■-butene, 1-pentene, 3-methyl-1-butene, ■-hexene, 4-methyl-1-pentene, 1-heptene, - Homopolymers or copolymers of 1-olefins such as octene, or 1-
A copolymer of an olefin and a small amount of other polymerizable monomer, such as vinyl acetate, acrylic acid, methacrylic acid, methyl acrylate, methyl methacrylate, etc., or a copolymer of the above polyolefin with vinyl acetate, acrylic acid, methacrylic acid, etc.
The present invention also includes graft-modified polyolefins grafted with polymerizable monomers such as maleic acid, fumaric acid, methyl acrylate, methyl methacrylate, methyl maleate, ethyl acrylate, ethyl methacrylate, ethyl maleate, and maleic anhydride. It is included in polyolefin.

Among these, highly crystalline polymers such as polyethylene, polypropylene, and poly-1-butene are preferred because they have high rigidity, and polypropylene is particularly preferred because it has excellent rigidity and good moldability. most preferred.

The polyolefin used in the present invention may contain a heat stabilizer, a weather stabilizer, a lubricant, a slip agent, a dye, a pigment flame retardant, an antistatic agent, a filler, and the like.

Examples of cements with which the composition of the present invention can be mixed include hydraulic cements such as Bordeaux land cement, white Portland cement, alumina cement, silica cement, magnesia cement, and pozzolanic cement, and air-hard cements such as plaster and lime. Various types of cements can be mentioned.

The method for producing the cement compound of the present invention includes heating and melting the polyolefin, extruding it from a die or forming it into a sheet by calendering, and then stretching the sheet in the longitudinal direction to form a tape. do.

The present invention requires that the tape be embossed.

This type of embossing is performed by passing the sheet through an embossing roll before or after stretching, and this embossing creates irregularities on the surface or the entire tape, and these irregularities create a physical bond to the concrete. plays an important role in significantly increasing

The embossed surface may have some cracks during stretching.

The shape of the embossing may be arbitrary, but preferably 1-
There is one pattern in 10-.

Further, the depth may be arbitrary, but it is preferably as deep as possible without significantly impairing the rigidity of the tape.

The stretching temperature is below the melting point of the raw polyolefin and above the secondary transition point, and the stretching ratio is preferably about 3 to 10 times, particularly about 5 to 8 times.

Due to this stretching process. A tape with high rigidity and low elongation can be obtained.

The stretched tape is appropriately cut in the length direction and, if necessary, in the width direction to obtain a blend.

The formulation thus obtained has a length with a stretching force of 10 to 60 mm, in particular 30 to 40 mm, and a width of 1 mm.
from 10 mm to 10 mm, especially from 1.5 to 57 nTIL1 average thickness from 0.2 to 11 n7 IL%, especially from 0.2 tr
ay to 0.6 mm, initial elastic modulus is 250 kg7
mA to 400 kg/my7t, and elongation at break is preferably 30 modulus or less.

If the length of the compound is less than the above range, the reinforcing effect will be poor; on the other hand, if it is too long, the dispersibility in cement will be poor and the compound will come out to the surface and spoil the appearance. .

The reinforcing effect is excellent when the width is within the above range, and the reinforcing effect decreases as the width deviates from this range.

If the average thickness is less than the above range, the rigidity of the film will be poor, and the ease of dispersion into cement and reinforcing effect will be reduced.

The amount of the cement composition of the present invention is usually 1 to 30% by weight, preferably 3 to 15% by weight based on cement.
Below this range, the reinforcing effect will be poor; on the other hand, if it exceeds the above range, the proportion of the blend will become too large, making uniform dispersion difficult.

The method of blending the compound of the present invention into cement is to mix cement with raw materials such as sand and silica if necessary, then add and mix the compound of the present invention, and further add water and knead. , a method of curing this, or a method of adding and mixing the compound of the present invention into a raw material mixture mixed with water.

The cement composition of the present invention has high rigidity and does not cause entanglement, so it can be easily dispersed in cement.

Therefore, a normal cement mixer is sufficient and no special equipment is required.

In addition, since the tape surface is roughened by embossing, it has a strong physical bond with the cement and exhibits an excellent reinforcing effect on the bending resistance and crack prevention of cement products.

Since the cement composition of the present invention has high rigidity and exists in an elongated state in a cement product, it also exhibits a sufficient reinforcing effect.

Therefore, various cement molded bodies are used for underwater structures such as tetrapods, runways, bridges, tunnels, etc., as well as mortar, walls, precast boards, speaker boxes, revetment blocks, fence blocks, roof tiles, sleepers, and humid pipes. , paving blocks, tiles, planters, park benches, etc.

EXAMPLES Next, the present invention will be described in detail with reference to examples, but the present invention is not limited to these examples in any way.

Example 1 [Preparation of formulation] Melt index (ASTM D 1238-65T
.

A mixture of 95 parts by weight of polypropylene (230°C) 1.5 and 5 parts by weight of calcium carbonate powder was supplied to a 65 mmφ extruder, and a sheet was extruded from a T-die at a resin temperature of 230°C.

While the surface temperature of the obtained sheet is 90 to 100°C, it is passed through a first embossing roll with ridges in the circumferential direction to form parallel grooves, and then separated by a slitter to form five tapes with a width of 40 mvt. I got it.

The tape was stretched 7 times using a stretching device to a thickness of 0.5 m.
A tape of m was obtained.

Next, the stretched tape was stretched to a peak height of 0.5 mrn and 2 m.
Diagonal with m spacing.

The tape was embossed through a second embossing roll with a checkered pattern engraved on it.

The embossed stretched tape thus obtained had an initial elastic modulus of 295 kg/mu and an elongation at break of 19.5%.

Cut this into pieces with a length of 40 mm 1 rl] 2 mm,
Semen.

It was used as a formulation for

[Preparation of specimen]

It was conducted according to JISR5201.

That is, after thoroughly mixing 100 parts by weight of Portland cement and 200 parts by weight of Toyoura standard sand, 10 parts by weight of the mixture obtained by the above method was added, and after further thorough kneading, 65 parts by weight of fishing rod was added. After kneading the whole mixture to make it uniform, it was packed in a mold of 40 m x 40 mm x 160 mrn, and cured for a total of 7 days, 24 hours in the air and 6 days in water.

[Measurement of bending strength]

The specimen obtained by the above method was measured using an Instron testing machine with a span of 100 mm, a bending speed of 1 nm, Am, and a bending jig tip curvature of 5R.

Example 2 The same procedure as in Example 1 was carried out, except that an embossed stretched tape obtained in the same manner as in Example 1 was cut into pieces of 30 mm in length and 2 mm in width and used as a cement composition.

Example 3 The same procedure as in Example 1 was carried out, except that an embossed stretched tape obtained in the same manner as in Example 1 was cut into pieces having a length of 20 m and a width of 2 mm and used as a cement composition.

Examples 4 to 6 Examples 4 to 6 were carried out in the same manner as in Example 1, except that cement formulations obtained by cutting embossed stretched tapes obtained in the same manner as in Example 1 to a length of 40 m7 rL and various widths shown in Table 1 were used. I did the same.

Comparative Example 1 A specimen was prepared and tested in the same manner as in Example 1, except that no cement compound was added.

Comparative Example 2 A stretched tape obtained in the same manner as in Example 1 except that it was not passed through the second embossing roll was cut into pieces of 40 mm in length and 2 mm in width and used as a cement compound. Except for this, the same method as in Example] was carried out.

Example 7.8 The test specimens in Example 1 were prepared in the same manner as in Example 1 except that the amounts of the compounds were as shown in Table 1.

The results of Examples 1 to 8 and Comparative Examples 1 to 2 are shown in Table 1.

Comparative Examples 3 to 7 Comparative examples were carried out in the same manner as in Example 1, except that the various formulations shown in Table 2 were used instead of the formulation of the present invention.

The results are shown in Table 2.

Claims (1)

Claims: 1. Embossed po with an initial modulus of elasticity of 250 to 400 kg/mA and an average thickness of 0.2 to 1 mrn. A cement compound made by cutting lyolefin stretched tape into appropriate lengths.