JPS59169959A - Dispersant for hydraulic cement - 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 The present invention relates to a dispersant for hydraulic cement, more specifically, a salt of a high condensate of polyethylene glycol (hereinafter abbreviated as PEG) and naphthalene sulfonic acid formalin having an average molecular weight of 6,000 to 30,000 (hereinafter abbreviated as PEG). , abbreviated as N5FC) in uniform coexistence at a predetermined ratio.

In recent years, with the rise of concrete IJ-type structures, plastering mortars, and other hydraulic cement-related industries, N5FC has been used as an admixture to improve the physical properties of concrete and cement mortar that have not yet hardened or have hardened. This makes it possible to significantly reduce the amount of water required, contributing to improvements in their physical properties. However, when N5FC is used in the form of a fine powder or aqueous solution, as is usually done, although the plasticity of the ready-mixed concrete 1 is relatively thick, the time required to cast it ( Normally, the plasticity of the concrete decreases significantly over time during a maximum of about one hour, making it difficult to handle.9 However, this decrease in plasticity still causes problems such as the formation of slab-shaped concrete.

Conventionally, various proposals have been made to solve this problem with N5FC. For example, there is a method of re-adding N5FC to ready-mixed concrete that has been mixed in a ready-mixed concrete plant immediately before pouring (Japanese Patent Laid-Open No. 52-50319, etc.). However, this method imposes a large burden on personnel and equipment due to re-adding N5FC.

There is also a method using aggregates of fine particles of NSF, C, etc. with a particle size of 0.1 to 10 g, optionally provided with a coating (JP-A-54-139'927).However,
In this case, the resulting aggregates tend to collapse by self-disintegration, resulting in insufficient ability to prevent the deterioration of the plasticizing effect over time, and during summer storage, aggregates tend to stick to each other and form agglomerates, causing the coating to deteriorate. There is a risk that N5FC may temporarily exhibit its effects after being dissolved, making it difficult to handle, and since the manufacturing method involves pelletizing and then crushing, the number of manufacturing steps is large, and additional equipment is required. . Furthermore, N5F
There is also a method using a dispersant prepared by molding C into powder together with a water-insoluble carrier (Japanese Patent Publication No. 54460/1983). However, in this case, for example, the neutralization method is unreasonable, and N
It is difficult to obtain powder particles containing 5FC uniformly.

On the other hand, at work sites in the hydraulic cement industry, N.S.
Including Ii'C, the materials used tend to be handled relatively roughly, and the specific working hours tend to be highly irregular. Therefore, under these circumstances, the dispersant according to the present invention is sufficiently strong, has good storage stability, and has a large ability to prevent the plasticizing effect from decreasing over time for about 1 hour. What is required is that it continues without change.

In order to eliminate the conventional drawbacks and provide an improved dispersant for hydraulic cement that meets the above-mentioned demands, the present inventors have investigated the high temperature stability of N5FC (70-b PEG with a molecular weight of 6,000 or more). The high temperature stability (70-b) is due to the large physical or chemical affinity between PEG and N5FC, the fact that the dissolution rate of the PEG in water decreases as the molecular weight increases, and the chemical structure of the PEG. Focusing on its flexibility, solidification properties at room temperature, and melting properties at temperatures above 50°C, we conducted extensive research into the combination of PEG and N5FC, and found that PEG with an average molecular weight of 6,000 to 30,000
The present inventors have discovered that the intended purpose can be achieved by pulverizing the solid matter obtained by heating, dehydrating, and drying a homogeneous mixed aqueous solution of a suitable amount of N5FC and N5FC, and have completed the present invention.

That is, in the present invention, the average molecular weight is 6,000 to 30,000.
The present invention relates to a dispersant for hydraulic cement, which is made of a pulverized solid material obtained by dehydrating and drying a homogeneous mixed aqueous solution of 20 to 70 parts by weight of PEG and 80 to 30 parts by weight of N5F.

In the present invention, if the molecular weight of PEG is smaller than 6000, its immediate solubility in water becomes significant, and the lasting effect of plasticity when added to concrete decreases, and unstable air bubbles are still generated in concrete. , undesirable.

Conversely, if the molecular weight of PEG is greater than 30,000, the rate of dissolution in water is low, and furthermore, it is difficult to produce it industrially. PEGs having an average molecular weight of 6,000 to 30,000 are preferred and are produced by conventional methods using alkaline catalysts. Further, N5FC is a salt of Na, Ca, ammonium, etc. of a high condensate of naphthalene sulfonic acid formalin, and all of the NSFCs currently commercially available as highly water reducing agents can be used. And PEG and N5 explained above
The blending ratio with FC is PEG/N5FC=20/70~8
It is 0/20 (parts by weight). If the amount of N5FC is more than this, the obtained powder or granules are likely to crumble, making it difficult to stably produce products of a desired size, and the performance will also deteriorate. On the other hand, if the N5FC content is less than this, the original performance will be degraded, which is not preferable from the economic point of view.

In order to maintain the effect of N'SFC that does not vary greatly, the powder and granules must be strong and have a relatively large relative surface area (relatively small particle size), which will gradually dissolve. In this sense, the particle size of the dispersant according to the present invention is preferably in the range of 03 to 6nnn,
Particularly preferred is a range of +41 to 3 ynm. The amount of the dispersant of the present invention made of such powdery material is as follows:
Although not particularly limited, it is usually 0 for cement.
They are in sections 1-30.

Next, an example of a method for producing a dispersant according to the present invention will be described.

First, a 10-60% aqueous solution of N5FC is prepared. Then, the dissolved or undissolved PEG is uniformly dissolved in this while stirring at room temperature or heating at 40 to 50°C. next,
Pour the aqueous solution into a vat and heat it under normal pressure or reduced pressure for 70~
After heating to 140° C. to evaporate water and cooling, a firm cake-like solid is formed. Finally, the solid material is coarsely or finely ground to a particle size in the range of 0.3 to 6 mm using a feather mill or the like to obtain powder.

The dispersant according to the present invention is obtained by dehydrating and drying a homogeneous mixed aqueous solution of a predetermined PEG and N5FC in a certain range of proportions and crushing the resulting solid, thereby achieving the desired effect. , PEG,! : If a solid material obtained by simply kneading a powder or granular material with N5FC is crushed, the desired effect cannot be obtained because, for example, PEG and N S l'C do not coexist uniformly. I can't do it.

The dispersant according to the present invention described above has the following effects.

(1) Strong. Therefore, the production of finely pulverized materials during the crushing process using a feather mill or the like is extremely small, and it is easy to obtain a product with a constant diameter. Furthermore, there is almost no self-destruction that starts immediately after manufacturing. Furthermore, it can sufficiently withstand rough handling at work sites, and when added to concrete, it is unlikely to be pulverized by mechanical force or frictional force of fine aggregate during mixing of concrete or cement mortar. In addition to these, since it gradually dissolves into water from the surface over a long period of time, it is possible to stably prevent a decrease in plasticity over time as desired over a long period of time.

(2) Excellent weather resistance, especially storage stability in summer. In warehouses exposed to direct sunlight and poor ventilation, it is not uncommon for the room temperature to rise to 50 to 70°C.
No surface dissolution occurs, and no agglomeration of powder particles occurs.

(3) As mentioned above, its manufacture is simple.

Hereinafter, the present invention will be explained in more detail with reference to four test examples.

・Strength test (Test-1) PEG was added to N5FC at 40 to 50°C so that the ratio of PE (, N, and SFC) was as shown in Table 1 (in terms of solid content).
It was uniformly dissolved in the aqueous solution while stirring. This homogeneous mixed aqueous solution was placed in Bano 1, water was evaporated in a ventilation dryer at 110 to 120°C for 72 hours, and then cooled to obtain a solid. After pounding the solids with a hammer to form a cake, 3
Feather mill equipped with M sieve (manufactured by Seiyou Tekko Co., Ltd., FM
-1 type). Then, 1.2 m of coarsely crushed material was
I sifted it with a m sieve. The residual amount (% by weight) on the 1.2 g sieve is shown in Table 1. Incidentally, the larger the residual amount, the smaller the amount of fine particles generated during crushing and the larger the amount of particles with a certain range of particle diameters, and this is due to the strength of the particles.

Table 1 [Rice 1: EG is ethylene glycol (the same applies below).

Rice 2: Comparative Example 8 is a mixture of finely powdered N5FC of 0.2 mm or less and finely powdered PEG6000 mixed in a pellet manufacturing pan, sprayed with EG, kneaded well to make it dense, and heated to 50% in a rotary evaporator. The solid material was heat-treated at ℃ for 50 minutes.

Rice 3, Rice 4: Comparative Examples 9 and 10 are N5F of 0 to 03πm
C powder was sprayed with water, molded into pellets, and dried to obtain a solid material. However, in Comparative Example 10, the powder was coarsely crushed using a feather mill equipped with an 8-sieve. Rice 5: The cake was so sticky that it was extremely difficult to coarsely crush it using a feather mill or the like, and it was not possible to produce three types of coarsely crushed cake. ] From the results in Table 1, it is clear that in the present invention, the greater the molecular weight of PEG, and the greater the blending ratio of PEG is from 20 to 80%, the greater the strength of the particles. Furthermore, it is clear that the residual amount in Comparative Example 9 is significantly smaller than in each of the Examples.

・Cement Mortar Plasticity Test M (Test S-2) JIS-R
According to the strength test method in ``Physical Test Methods for 5201r Cement'', solids prepared in the same manner as Test-1 above were used at the mixing ratios listed in Table 2, and 3 m
Hue with M sieve installed.

A plasticity test was conducted when the material that passed through the Zamil was used as a cement mortar dispersant using the following blending and kneading methods.

Mixture: Cement Niube Ordinary Portland Cement = 52
0g, fine aggregate: Toyoura standard sand - 104 (1, water double water - 281g, dispersant: N SFC amount, 024 ratio of cement amount, kneading method and test method - Sand, cement, in a kneading pot City water was added, followed by the dispersant.After stirring at low speed for 30 seconds, stirring at high speed for 60 seconds, and then scraping off the mortar on the edge of the kneading bowl with a spatula for another 30 seconds.
Stir at high speed for 2 seconds. Using this as a sample, the flow and air amount (unit weight method) immediately after kneading were determined according to JIS-R-5200.
It was measured using the method. Then, return the sample to the kneading bowl and
Flow was measured in the same manner after 0 and 60 minutes.

The results are shown in Table 2.

Table 2 [Rice 6: Example 61a, 6 A feather mill equipped with a pnm sieve was used. Rice 7: Comparative Example 11 is Test-1
The preparations were made in the same manner as in Comparative Example 8, except that a feather mill equipped with an 8-m sieve was used. Note: Comparative Examples 9 and 10 were prepared in the same manner as Test-1. ] From the results in Table 2, it can be seen that the dispersant according to the present invention stably exhibits the effect of preventing a decrease in plasticity of cement mortar after 30 to 60 minutes of kneading, compared to the comparative example.
is clear.

・Concrete plasticity test (Test-3) At the mixing ratio shown in Table 3, the material passed through the feather mill with a sieve attached for 3 hours in the same manner as in Test 2 was hardened using the following materials, mixtures, and kneading methods. A plasticity test was conducted when it was used as a dispersant for mixed concrete.

Materials used: Cement 2 Onoda Ordinary Portland Cement / Sumitomo Ordinary Portland Cement = 1/□ Fine aggregate: Oi river sand, specific gravity -26 2, FM = 2.80 Coarse aggregate: Crushed stone from Mt. Hachichi, 25m or less, specific gravity = 2.66, FM=6 7 AE agent: Admixture for hard mixing concrete, Chewpol fX (manufactured by Takemoto Yushi Co., Ltd.) Water: City water blend - Kneading detection method and test method...Used as described above for 601 tilting mixer After adding the materials in the above-mentioned formulation, a dispersant in an amount of 0.25% of the amount of cement in terms of N5vC was added and kneaded for 30 minutes. Slump immediately after crosstalk, 30 minutes later, 60 minutes later,
The amount of air immediately after the crosstalk was measured, and the compressive strength of the samples sampled 60 minutes later was measured after 28 days. The test method is JIS-A-1101 for slump, JIS-A-1-j18 for air volume, and JIS-A-110 for compressive strength.
According to 8.

The results are shown in Table 3.

Table 3 [Company: Example 6 and Comparative Examples 9 to 11 were prepared or coarsely ground in the same manner as in Test-2 (Table 2)] From the results in Table 3, it is clear that the It is clear that the dispersant stably exhibits the effect of preventing the plasticity of fresh concrete from decreasing after 30 to 60 minutes of mixing compared to the comparative example.

- Agglomeration test (Test-4) The dispersants of Examples 1 to 5 in Test-1 and Test-2 and the following dispersant (Comparative Example 12) were prepared, and 200% of each was prepared.
g was placed in a 500 ml beaker VC and stored at 60°C overnight. The next day, the sample was sieved through a Sannokawa sieve, and the presence or absence of agglomeration was determined from the amount remaining on the sieve.

Comparative Example 12... 40 parts by weight of E'G was sprayed on 100 parts by weight of a mixture of 0.2 wn or less fine powder N5FC/fine powder PEG mixed in a pelletizing pan at a weight ratio of 6000 = 9515, and kneaded well. After densification,
Heat treated in a rotary evaporator at 50°C for 50 minutes, and then
Powder and granules passed through a sieve.

Results The entire amount of the dispersant of each example passed through a 3 myn sieve, and no caking phenomenon occurred. Comparative example 12
(29% remained on the 4.3 tnyn sieve, exhibiting a caking phenomenon.Patent applicant: Takemoto Yushi Co., Ltd. Patent attorney: Hiromasa Iriyama

Claims (1)

[Claims] 1 Powder-like material obtained by crushing a solid obtained by dehydrating and drying a homogeneous mixed aqueous solution of 20 to 70 parts by weight of polyethylene glycol having an average molecular weight of 6,000 to 30,000 and 80 to 30 parts by weight of a salt of naphthalene sulfonic acid formalin high condensate. A dispersant for hydraulic cement consisting of: