JPS593953B2 - Manufacturing method of cement dispersant - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing an improved cement dispersant containing lignin sulfonate as an active ingredient, and more specifically, to a method for producing an improved cement dispersant containing lignin sulfonate as an active ingredient. This invention relates to a method for producing a cement dispersant which improves the hardening retardation of cement by subjecting it to heat oxidation treatment under alkaline conditions and ultrafiltration to reduce low molecular weight substances, and by adding genin sulfonate as an active ingredient.

Traditionally, lignin sulfonate-based cement dispersants, which contain lignin sulfonate as an active ingredient, have been widely used to improve the workability of concrete, but this significantly delays the setting and strength development of concrete. Therefore, it is used in combination with salts such as calcium chloride when construction is carried out in winter or in cold regions, or when early curing is required.

However, recently there has been a shortage of aggregates for concrete, and it has become necessary to use aggregates containing salt, so adding salts such as calcium chloride to concrete as a strength promoter will increase the strength of concrete reinforcing steel. It is undesirable from the viewpoint of durability because it corrodes, and there is a demand for a ligninsulfonate-based cement dispersant that does not delay in developing strength without using salts such as calcium chloride.

In addition, the use of so-called highly fluidized concrete, which increases the strength of concrete by adding a large amount of cement dispersant without increasing the unit water volume, is rapidly increasing, but lignin sulfonate Acid-based cement dispersants have a drawback that they cannot be used in such concrete formulations because they have a large retardation property.

The purpose of the present invention is to meet such needs and eliminate the drawbacks thereof.The gist of the present invention is to reduce reducing sugars by heat oxidation treatment under alkaline conditions, and then to reduce the reducing sugars to the separation limit. Molecular weight 2,0, characterized by ultrafiltration using a membrane with a molecular weight of 500 to 500,000.
This is a method for producing a cement dispersant containing as an active ingredient a lignin sulfonate having 25% by weight or less of 00 or less.

In other words, the main features of the present invention are that pulp waste liquid is heated and oxidized under alkaline conditions and then ultrafiltered, and that the content of low molecular weight substances is reduced. However, in order to clarify the difference from the conventional technology, the general manufacturing method of the conventional cement dispersant based on geninsulfonate will be described as follows.

In other words, sulfite pulp waste liquid, which has a relatively low reducing sugar content after yeast or alcohol fermentation, is used as a cement dispersant either as it is or by concentrating it.The so-called Howard process involves adding slaked lime to pulp waste liquid to make lignin sulfonic acid insoluble. A method of separating and recovering sugars from waste liquid instead of salts,
Alternatively, it is produced by heat-treating pulp waste liquid under alkaline conditions to denature sugars into components that have little effect on the hardening of concrete.

On the other hand, to explain the present invention, the pulp waste liquid raw material is
It may be either broad-leaved pulp waste liquid or soft-wood pulp waste liquid, and there is no difference whether it is fermented with microorganisms or untreated.

This is because the amount of sugar content in the pulp waste liquid does not have a large effect on the present invention.

However, if you use something that has been fermented by microorganisms,
It is preferable to use this as a raw material because reducing sugars, which adversely affect the water usage of cement, are reduced.

In the oxidation treatment, salts (alkali or alkaline earth) such as sodium, potassium, calcium, and magnesium are added to the pulp waste liquid material to make it alkaline, and this is heated and oxidized to remove at least the content of the pulp waste liquid. Oxidizes reducing sugars to reduce reducing sugars.

In the present invention, oxidation treatment is a necessary requirement in order to eliminate the delay in strength development as shown in the examples.

The reason why thermal oxidation under alkaline conditions was selected from various oxidation treatment conditions in the present invention is to prevent excessive detachment of the sulfone groups bonded to the lignin skeleton molecules, and thereby to prevent a decrease in the dispersibility of cement. It also prevents
The purpose is to reduce reducing sugars, and if this is carried out at higher temperatures and pressures than necessary, or if oxidation treatment is performed using an oxidizing agent such as dichromate, not only the reducing sugars will be oxidized, but the lignin skeleton itself will also be oxidized. As a result, the dispersibility of cement decreases, which is contrary to the gist of the present invention.

The oxidation conditions of the present invention vary slightly depending on the sulfite pulp waste liquid production process, tree species, cooking conditions, etc., so it is difficult to define uniform reaction conditions, but at least conditions that oxidize reducing sugars are required. Good to have.

Usually, the treatment is carried out at a temperature of 60 to 90°C.

There are various methods that can be used to reduce the amount of low molecular weight substances (molecular weight 2,000 or less) to 25% by weight or less after oxidation treatment. This is the most preferable method because not only can lignin be recovered individually, but sugar can also be recovered at the same time.

The membrane used for this has a separation limit of 500 to 500,000
, preferably 5,000 to 10,000,
If such a membrane is used, a low molecular weight material having a molecular weight of 2,000 or less can be easily obtained in a concentration of 25% by weight or less.

Further, the solid content concentration of the acid-treated pulp waste liquid used for this is 0.1 to 40% by weight, preferably 1 to 20% by weight.

The reason why we limited the amount of low molecular weight substances (molecular weight 2,000 or less) to 25% by weight or less is that we use gel permeation chromatography (GPC) using silica gel that has been treated to make it hydrophilic. When the molecular weight distribution of the acid salt was measured and the sample was separated and added to cement, it was found that when the amount of low molecular weight substances (molecular weight 2,000 or less) exceeds 25% by weight, setting and strength development are significantly delayed, leading to serious problems. This is because the cement dispersant targeted by the invention cannot be obtained.

A preferable molecular weight distribution is such that the molecular weight of 2,000 or less is 20% by weight or less, and the molecular weight of 10,000 or more is 20% by weight or more, particularly preferably 40% by weight or more.

In ultrafiltration of this oxidized pulp waste liquid, the concentrated liquid obtained by ultrafiltration is further diluted and subjected to ultrafiltration again, and this operation is repeated for separation and purification. You can also improve your degree.

This operation may be repeated with the same type of membrane or with other membranes with different separation limits.

This operation can theoretically be repeated infinitely.

However, in consideration of economy and practicality, it is better to repeat the operation 1 to 10 times, preferably 1 to 5 times.

The cement dispersant of the present invention can be used as a dispersant for cement paste, mortar, and concrete, but when used as a dispersant for concrete, the effects of the present invention are markedly exhibited and it is most preferred from a practical standpoint.

When mixing fluidized concrete for construction using the product of the present invention, it is preferable to have a slump value of 15 CrrL or more, and in the case of fluidized concrete for civil engineering, it is preferable to use the product to have a slump value of 10 cIrL or more. be.

The addition method may be any one of batch addition, divided addition, pre-addition, delayed addition, etc., and may be used in combination with other retarders, curing accelerators, etc.

As explained above, the present invention oxidizes pulp waste liquid, refines it by ultra-tear filtration method, and reduces the amount of low molecular weight substances of 2.000 or less to 25% by weight or less, or disperses geninsulfonate-based cement. The effects of the method for producing the drug are as follows.

(1) Compared to conventional glue geninsulfonate-based cement dispersants, it has a smaller effect on cement hardening retardation, so it can be added in large amounts, making it possible to mix highly fluidized concrete.

(2) Air entrainment, which is said to be the biggest drawback of β-naphthalene sulfonic acid condensate cement dispersants conventionally used for the production of fluidized concrete, can be improved. Freeze-thaw resistance can be improved.

(3) When highly fluidized concrete is produced using a β-naphthalenesulfonic acid condensate cement dispersant, the change in slump over time is extremely large, but when the product of the present invention is used, this becomes smaller.

(4) The product of the present invention uses waste as a raw material, but because it is manufactured by a specific manufacturing method, it can be produced in large quantities with stable high quality.

(5) The method of the present invention has no particular restrictions on the raw materials, has simple processing means, and is highly economical.

The present invention will be further explained below with reference to Examples.

Example 1 A 5% solids aqueous solution of coniferous sulfite pulp waste liquid was
Using a flat membrane ultrafiltration device (Mitsui/DDS, module type 20-0.36) with an effective membrane area of 0.36 m and a membrane with an approximate separation limit molecular weight of 20,000, the liquid volume of the concentrated liquid was 51. An ultrafiltration permeate sample (B) and an ultrafiltration permeate sample (B) were obtained.

Similarly, a 20% solids solution of coniferous sulfite pulp waste liquid was prepared in 11 and placed in a glass autoclave having a volume of 51.

Calcium hydroxide was added to this solution to adjust the pH to 11, and the mixture was heated to 90°C and held for 3 hours.

After cooling to room temperature, the insoluble material produced was separated by centrifugation, and the resulting solution was neutralized by adding sulfuric acid.

The solution obtained by separating the re-generated precipitate is an oxidized sample (referred to as 0).

Oxidation sample (solution 101 with a solid content concentration of 5% by adding water to 0
and a flat membrane ultrafiltration device with an effective membrane area of 0.365 (
Mitsui/DDS, module type 20-0.36) was used to concentrate the concentrated liquid until the liquid volume was 51 using a membrane with an approximate separation limit molecular weight of 20,000, and the oxidation/ultrafiltration permeated sample (
mouth, and oxidized and ultrafiltrated permeate samples (trout were obtained.

Add water to the oxidation/ultrafiltration permeation sample (to) to make a solution ioz with a solid content concentration of 5%, and use a flat membrane ultrafiltration device (Mitsui/DDS1 module type 20-0
．． 36), using a membrane with an approximate separation limit molecular weight of 20.000, the concentrated solution was concentrated until the liquid volume was 51.

Water was added to the obtained concentrated solution to make the concentration 101, and the concentrated solution was concentrated again using the same ultralacrimation device until the concentrated solution amount became 51.

The same operation was repeated three times in total to finally obtain 51 concentrated liquids.

This concentrated liquid is designated as the oxidation/ultrafiltration permeate sample (F?).

Table 1 shows the concrete test results when samples (A) to (F') were added to concrete, when untreated softwood pulp waste liquid (0) was added, and when no additive I was added.

(To) dimensions are products of the present invention. Concrete test conditions: Admixture amount vs. cement 0.5% (solid f+), Cement: Ordinary Portland cement, Aggregate: Sagami river sand, Sagami river gravel, VC: 53%, Unit cement amount: 304 kg
/m”1s/a: 45%.

Example 2 A hardwood ultraconcentration sample (I) and a permeation sample (J) were obtained in the same manner as in Example 1 using a hardwood pulp waste liquid that had been fermented with microorganisms.

Further, oxidation treatment was performed in the same manner as in Example 1 to obtain a hardwood oxidized sample (2).

Furthermore, ultrafiltration of the oxidized liquid was performed in the same manner as in Example 1, and a broad-leaved oxidized/ultrafiltration superconcentrated sample (L4) was obtained.
An oxidation/ultrafiltrate (extremely) was obtained.

Further, the ultrafiltration of sample (L) was repeated three more times in the same manner as in Example 1 to obtain a hardwood oxidized/ultrafiltration x 4 concentrated sample N.

Samples (I) to N were added to concrete, and hardwood pulp waste liquid was subjected to microbial fermentation only (
Table 2 shows the concrete test results when 0 was added and when a commercially available β-naphthalene sulfonic acid condensate cement dispersant (P) (Kao Soap Mighty 150) was added.

(9 and N are products of the present invention.

The concrete test conditions are the same as in Example-1.

Example 3 Samples for which the production method was shown in Example 1 (1) was added to civil engineering concrete, and the sample (1) was added to civil engineering concrete, and the sample (1) was prepared using softwood pulp waste liquid (1) before treatment.
Concrete experiments were conducted in the case of adding G, the case of adding a commercially available β-naphthalene sulfonic acid condensate type water reducing agent (P), and the case of no additive.

The results are shown in Table-3. Concrete test conditions: Admixture added amount vs. cement 0.5% (solid content), Cement: Ordinary Portland cement, Aggregate: Sagami river sand, Sagami river gravel, W/C = 42%, Unit cement amount: 380 To! 9/m
3. s/a: 39%.

Freeze-thaw resistance was tested in water according to ASTM C-666.

In Table 3, a dynamic elastic modulus after 300 cycles of 60% or more of that before the test is evaluated as good, and a dynamic elastic modulus of less than 60% is evaluated as poor. In the sulfonate admixture, the content (weight ratio) of low molecular weight substances having a molecular weight of 2000 or less is as follows.

Claims (1)

[Claims] 1 Pulp waste liquid is heated and oxidized under alkaline conditions to reduce reducing sugars, and then this is separated with a molecular weight of 500~
A method for producing a cement dispersant containing as an active ingredient a lignin sulfonate having a molecular weight of 2,000 or less at 25% by weight or less, characterized by ultrafiltration using a 500,000 membrane. .